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NNadir

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Gender: Male
Current location: New Jersey
Member since: 2002
Number of posts: 25,690

Journal Archives

Frustrated Inner-City Students Running Out Of Ideas To Motivate Teachers

The Effect of Closing TVA Nuclear Plants on Infant Health.

I hadn't noticed, but Nature started a new Journal called Nature Energy. The parent journal is, of course, one of the world's most important scientific journals, and Google Scholar in fact rates it (in terms of h index) as the most prestigious journal.

No matter.

Having discovered the journal, and being interested in issues in Energy as they apply to climate change - which is getting worse, not better - I decided to leaf through some issues of this new journal.

I was pleased to find a paper on what I personally regard as the only acceptable form of centralized energy, nuclear energy.

The paper is here: Impacts of nuclear plant shutdown on coal-fired power generation and infant health in the Tennessee Valley in the 1980s (NATURE ENERGY 2, 17051 (2017))

Some excerpts from the text:

Nuclear accidents usually give rise to public backlash against nuclear energy. Three major accidents the 1979 Three Mile Island partial nuclear meltdown in the US, the 1986 Chernobyl disaster in the Soviet Union, and the 2011 Fukushima accident in Japan have led to the discontinuation of nuclear programs in several countries. After the Fukushima disaster, for instance, German support for nuclear energy dropped by about 20 per cent1, and Germany permanently shut down eight of its seventeen reactors, pledging to complete the phase-out by 2022. In the US, Fukushima added pressure to the power industry. Facing cheap natural gas, stalled carbon emissions legislation, and growing safety concerns, they eventually announced the closure of six large nuclear power plants2. Although the media has discussed the public health consequences of potential exposure to radioactivity associated with nuclear accidents extensively, emissions and health costs prevented by nuclear power generation have been overlooked.


"...stalled carbon emission legislation..."

"...cheap natural gas..."

In reference to the latter, I would ask, "cheap for whom?" The people who are using it while we all wait for the make believe solar and wind miracle that has not come, is not come and will never come, or for all future generations who will live with the consequences of the absolute and total failure of so called "renewable energy" to actually work?

More from the paper's text:

The Three Mile Island Unit 2 reactor partially melted down on 28 March 1979, near Middletown, Pennsylvania. Being the worst accident in US commercial nuclear power plant history, the accident crystallized anti-nuclear safety concerns among activists and the general public. Following the public backlash, the Nuclear Regulatory Commission (NRC) intensified inspections in nuclear facilities, leading to new regulations and the shutdown of several nuclear plants around the nation in the 1980s, including Browns Ferry and Sequoyah in the TVA area in 1985. At Browns Ferry, NRC inspectors identified 652 violations bet ween 1981 and 1984, and the agency imposed $413,000 (1986 USD) in fines9_11. In July 1984, the NRC issued an order requiring TVA to implement its Regulatory Performance Improvement Program (RPIP) and provide periodic reports. In February 1985, reactor vessel water level instrumentation problems happened in Unit 3, leading TVA to cease operations in March 19 at all three Browns Ferry units to undertake programmatic improvements. By September 1985, the NRC found the RPIP to be ineffective and required another plan from TVA. The shutdown of Browns Ferry would last for many years, as shown by the timeline in Fig. 1.


The timeline shows that the Sequoyah Nuclear Plant shut in August of 1985 and restarted in November of 1988, the Browns Ferry Reactors shut in 1985 with Browns Ferry 2 restarting in 1991, Browns Ferry 3 restarting in 1995, and Browns Ferry 1 restarting in 2007.

Wow! This reads like an account written by that anti-nuke asshole Ed Lyman over at the Union of Concerned "Scientists."

Bad huh? 652 violations, this while the plant was operating! It's a wonder everyone in the Tennessee Valley wasn't killed, just like everyone in Japan was killed by Fukushima and everyone in Harrisburg PA died from Three Mile Island.

The author continues:

In this study, I exploit the shutdown of nuclear facilities in the TVA after the Three Mile Island accident in 1979 to estimate its direct impact on coal-fired power generation, particle pollution as measured by total suspended particulate (TSP), and infant health as captured by birth weight, a health indicator that has high predictive power for later-life outcomes. In fact, low birth weight infants experience severe health and developmental diffculties that can impose large costs on society14. It has a negative e ect on IQ, height and earnings15, and an inverse relationship with adult mortality particularly cardiovascular mortality16.Using econometricmethods with plant-level monthly electricity generation data, county-level TSP concentration, and birth-level data, I find three key results.


Three key results:

First, the shutdown of nuclear facilities in the TVA in the 1980s led to a shift in electricity generation towards coal-fired power plants. The substitution between nuclear and coal seems to be one to one, that is, each megawatt-hour not produced by nuclear power plants because of the shutdown appears to have been generated by coal-powered plants. Second, air pollution increased substantially in counties where coal-fired plants were producing large shares of the electricity originally generated by the nuclear facilities. The additional coal burning triggered by the nuclear shutdown led to an increase in TSP concentration by around 10 _gm􀀀3, which is equivalent to reversing the gains observed after two years of the implementation of the Clean Air Act Amendments of 1970 17. Third, and last, infant health may have deteriorated in places experiencing higher levels of air pollution induced by the nuclear shutdown. In fact, average birth weight in the most affected areas decreased considerably. The decline was approximately 134 g, or 5.4 per cent, which is large even when we rescale it by the change in TSP concentration.


Thank goodness the Tennessee Valley had people like Ed Lyman to protect its citizens from healthy full weight babies who would grow up to be intelligent, tall, human beings with a low incidence of heart disease and a normal life span.

The paper speaks for itself, but it is worth noting that the author kind of shrugs and says, more or less, "Well, we could always replace nuclear plants with natural gas."

Seven million people die each year from air pollution according to a paper I often reference from Lancet, which is by the way #4 on the Google Scholar list of the world's most prestigious scientific journals.

A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010 (Lancet 2012, 380, 2224–60: For air pollution mortality figures see Table 3, page 2238 and the text on page 2240.)

These papers speak for themselves, or should speak for themselves were it not for the fact that we on the left are only a little less willing to lie to ourselves than our opponents on the left.

Oh, and maybe you've been hearing that coal is dead because solar and wind energy are so wonderful. This too is a lie, a lie on a Trumpian scale.

If you don't think so, I consider it my duty to direct you to the EIA web page containing a graph of all electric power sources in the United States.

EIA ELECTRICITY DATA BROWSER

The graph is interactive, you can highlight the line associated with any form of energy by moving your cursor over the caption at the bottom for each form of energy.

After 50 years of cheering by people who hate nuclear energy because they are incompetent to understand a damned thing about it - but who are perfectly fine with dangerous natural gas because in their useless imaginations they regard it as "transitional" - the solar and wind industry combined can't even produce a fraction of the energy provided by nuclear energy using reactors mostly built 30 years ago by a generation of engineers this country can no longer match. To separate the (light blue) solar line from the x-axis, you may need a magnifying glass, and wind and hydroelectric are about tied for second closest to zero.

The fastest growing form of electrical energy generation in the United States, for anyone who can read a graph, is natural gas. The solar, wind, and hydroelectric industries are trivial in comparison to dangerous natural gas, and are in fact still trivial compared to coal.

The brown line is coal and it is more or less tied with dangerous natural gas for the #1 spot for fuels for electricity, after having been the chief supply of American electricity from the dawn of the 21st century up until 2015, when the surge in dangerous natural gas use - a crime against all future generations - began to surge.

By the way, there are no "Fossil Fuel Free" groups, few "Fossil Free" activists here at DU, except maybe me, even though we have had lots of "nuclear free" activists at DU, and of course a "nuclear free" group, not that I know all that much about them anymore after years of expressing my low opinion of their education and knowledge, since I've been liberally utilizing the wonderful "ignore" button here to address the worst and least educated of these people.

And if we care about the future, no, we can't always replace nuclear with natural gas. To do so, given the climate impact of this fuel, not to mention the permanent, irreversible damage to the subsurface structures through which much of water flows, is, again, a crime against all future generations, a crime more odious than low birth rates, short life spans, and impaired intellects. It is a crime that all future generations will not even have the resources to address, as we have selfishly determined to leave them with nothing.

It is difficult to think. It takes work. But, if you care about the future, and I personally regard this as an ethical imperative, it is your responsibility to do it.

Tomorrow's Friday. Enjoy it.

On the Solubility of Carbon Dioxide in Ionic Liquids.

A few years back, it was my privilege to attend this lecture, given at Princeton University, by Dr. Joan Brennecke of Notre Dame University on carbon dioxide capture using phase change ionic liquids:



"Ionic Liquids" are salts, generally where at least either the cation or the anion or both are organic molecules (although a few inorganic eutectic salts nearly qualify) that are liquids either near or at room temperature.

In my writing around the internet, I have never evinced a fondness for carbon capture of the dangerous fossil fuel waste carbon dioxide since I believe dangerous fossil fuels need to be phased out quickly.

However, to the extent that carbon dioxide can be removed from the atmosphere by biological materials, perhaps under reformation conditions at high temperatures provided by clean energy - by clean energy I mean nuclear energy - I believe this may offer an opportunity for future generations to reverse, to whatever extent possible, the great screwing over our generation gave them while claiming that, for one example of a worthless rationalization, that dangerous natural gas burning is only "transitional" while we all wait for the wonderful solar and wind utopia that did not come, is not here, and will never come.

To the extent that carbon capture is utilized to make carbon products, for instance carbides, nanotubes, graphene, and even polymers, this is value added sequestration.

And that is why I made sure I could leave work early and attend this lecture.

After the lecture, which was quite interesting, I collected some of Dr. Brennecke's papers and just got around to reading a few tonight.

Dr. Brennecke is the editor of the Journal of Chemical Engineering Data, where she's imposed some rather rigorous standards, much to the betterment of the world in general.

Here's one of the papers I collected:

On the High-Pressure Solubilities of Carbon Dioxide in Several Ionic Liquids (Joan Brennecke et al J. Chem. Eng. Data 2013, 58, 2642−2653)

Some excerpts from the text, beginning with the introductory paragraphs:

Ionic liquids (ILs) are arguably among the most interesting and important solvents to be developed in recent years. They are highly versatile due to their remarkably low vapor pressures, generally high thermal and chemical stability, nonflammability, and the ability to tune the chemical and physical properties by the incorporation of various functional groups into the anions and cations. As a result, they are effective media for reactions,1 have been considered as solvents for CO2 separation,2−8 can be used as absorbents in absorption refrigeration systems,9,10 serve in reactive catalysis,11−13 and have been evaluated for a wide variety of other separation processes.14−18 CO2 solubilities in the ILs are important for a number of these applications.

In addition, supercritical or near-critical CO2 has been studied by several authors as a way to recover valuable products from IL mixtures. For instance, CO2 can be used to separate the product from an IL + catalyst reaction mixture, leaving the IL and the catalyst ready for reuse.15,17 Scurto et al.19 demonstrated that CO2 could be used to separate ILs from aqueous solutions. Subcritical and supercritical CO2 has also been used successfully to induce separations of IL and organic compounds.16,17,19,20 It is well-known that high-pressure CO2 can affect the solvent strength of mixtures, especially when the solvent swells significantly with the addition of CO2. Thus, this is another situation where high pressure IL + CO2 phase behavior is important.


Note that some of the applications are actually carbon dioxide utilization schemes, where the (supercritical) carbon dioxide acts as a cosolvent.

An interesting and fun paragraph from the editor (and author in) this journal dedicated to accuracy and precision:

The Span−Wagner58 equation of state was used to calculate the density of the CO2 and determine the amount of CO2 transferred from the delivery system to the cell side. Knowing the volume of the lines on the cell side and the headspace of the cell, it is possible to determine the solubility of CO2 in the IL by difference, once again using the Span−Wagner equation of state for the vapor phase. Assuming that the vapor is pure CO2 is a very good assumption for the liquids investigated here since the ILs have very low volatility. Using a cathetometer to determine the height changes of the liquid level, one can also get the molar volume of the liquid mixture. The combined expanded uncertainty of the molar volume is calculated from the standard uncertainty of the cell volume which is determined from the height measurement with the cathetometer, the IL mass (± 0.0002 g), and the moles of CO2 dissolved in the liquid. This last uncertainty is determined from propagation of the uncertainties of the temperatures, Ruska pump volume, and volumes of the cell and lines.


The Span-Wagner equation is a wonderfully Rube Goldbergish equation that works to give highly reliable state variables for carbon dioxide. I had a little riff on this equation earlier in this space:

Paper on the Equation of State for High Efficiency Supercritical Carbon Dioxide Driven Turbines. (I wrote it before the subscript and superscript codes became unavailable at DU)

She finds that fluoroalkyl containing anions are the best at dissolving CO2.

The solubility behavior is [OTf]− < [Tf2N]− < [eFAP]−. Increasing the fluorination of the anion increases the solubility dramatically, as reported by Muldoon et al.39 We attribute this to both stronger interactions of the CO2 with the electronegative fluorine atoms and the higher free volume of anions with fluoroalkyl chains.



(This is unfortunate, because fluoroalkonic acids (notably PFOS) are a huge environmental problem to which we are too busy to pay attention. The only sink for these types of persistent pollutants, which are now present pretty much in every living thing on the planet, is radiation, which suggests yet another application for so called "nuclear waste" not that people who spend their lives uselessly on cartoonish anti-nuke websites are bright enough or informed enough to allow such use.)

The solubility of carbon dioxide in the alkyl phosphonium salts discussed in the paper are higher than those using imidazolium cations.

However the mixed organic/inorganic ionic liquid emim HSO4 shows very high solubility.

I thought this interesting.

Have a nice day tomorrow.

Thermochemical Conversion of Water and Carbon Dioxide into Synthesis Gas.

A great deal has been written in the energy field about the solid state structural class known as perovskites.

Here is the Wikipedia picture (not bad) of the perovskite structure:



Much of this interest has been directed at the quixotic enterprise of making the so called "renewable" solar industry actually work - it hasn't, it isn't and it won't - research has involved perovskite type structure consisting of lead, a halogen, usually iodine or bromine and an element like cesium.

For example: Imaging the Anomalous Charge Distribution Inside CsPbBr3 Perovskite Quantum Dots Sensitized Solar Cells (Panagrahi et al ACS Nano, ASAP accessed 10/02/17)

Perovskites of this type show high light to electricity efficiency, but like most all solar cells, they suffer from the usual draw backs, low energy to mass ratios which means that their material environmental impact will be enormous. Of course the fact that these cells contain the highly toxic element lead will have no bearing on people declaring them "green," any more that the equally stupid idea of "distributing" for "distributed energy" cadmium in cadmium telluride solar cells prevented these future toxic nightmares from being declared "green." Were they ever to make it to 10 exajoules (out of 570 exajoules used by humanity as a whole) per year - they won't - they would rival dangerous fossil fuels as environmental disasters, simply because of the volume and mass of toxic waste that would be required to be processed.

When I read about perovskite solar cells - and one really has no choice given the cockamamie energy funding pop culture has promoted - I usually want to throw up.

History will not forgive this generation, nor should it.

In more than half a century of nuclear operations in the United States, by contrast to the much more toxic and far less sustainable, successful or safe solar industry, only 75,000 MT of used nuclear fuel - a valuable resource - has accumulated, almost all of it easily contained at the site where it was generated. By contrast any wasteful scheme intended to make the solar industry work - it won't - would require the processing of tens of thousands of toxic materials per day, worse, distributed, where, much of it will be abandoned, making lots of little Flint Michigans (or their cadmium equivalents) all of the world.

Solar waste will never be as easily confined as fission products and actinides are.

My own interest in perovskites goes back a little longer than this recent solar fad. I've been interested in them as oxygen conducting membranes.

Way back in 2011, I spent a few weeks compiling all kinds of literature about perovskite oxygen conducting membranes, and actually built a spreadsheet listing the references I'd reviewed, the elements in the periodic table that they used, and the oxygen flux at reported temperatures...blah...blah...blah.

My interest was motivated by consideration of thermochemical water splitting cycles, of which a great many are known. I was investigating several that would theoretically make a 1:1 stoichiometric mixture of oxygen and carbon dioxide, and I was thinking about separations. (There are much better approaches, by the way, than such separations, but that's another issue.)

Thus my interest was piqued when I came across a paper in the current issue, released today (10/2/17), of the Journal ACS Sustainable Chemistry and Engineering

It's this one:

Oxygen Transport Membrane for Thermochemical Conversion of Water and Carbon Dioxide into Synthesis Gas (Jiang et al ACS Sustainable Chem. Eng. 2017, 5, 8657−8662)

With synthesis gas, one can pretty much make any large scale organic chemical obtained from petroleum, including those utilized in polymers. To the extent these chemicals are obtained from carbon dioxide and water, they represent value added sequestration of carbon dioxide. If the carbon dioxide is removed chemically (or physically) from the atmosphere, or is obtained by the controlled combustion of biomass, this sequestered carbon in theory at least could reverse climate change. (Realistically that is not going to happen. We're going to burn fossil fuels until we simply can't do so any more, all the time prattling on about the grand renewable future that never arrived, is not arriving and will not arrive. I'm speaking "in theory" and not "in practice." )

From the introductory text:

In the past few decades, transforming H2O and CO2 into high energy chemicals by artificial photosynthesis with the aid of solar power is getting more and more attractive, because of its important role in mitigation of energy shortage and global warming.1,2 Synthesis gas, a mixture of CO and H2, is a precursor to liquid hydrocarbon fuels. Synthesis gas can be obtained from splitting of CO2 and H2O using photocatalytic processes,3−7 high-temperature steam/CO2 coelectrolysis,8−11 or solar thermochemical loop processes.12,13 In the photocatalytic process, oxidic materials can decompose H2O and/or CO2 into H2 and/or CO. However, photocatalysis is impeded by its inherently limited energy conversion efficiency associated with band gap excitation.14 By contrast, thermochemical processes operating at elevated temperature can use the solar spectrum for thermal energy and possess fast chemical reaction kinetics. Previous research has demonstrated that the direct thermolysis of H2O and CO2 requires ultrahigh temperatures (>2500 K). To avoid the recombination and the formation of an explosive mixture, the generated gas products have to be separated at such high temperatures.15 To tackle the two issues of (i) ultrahigh temperature and (ii) gas separation at these temperatures, multistep thermochemical cycles - especially two step thermochemical loop cycles using metal oxide redox reactions - have been put forward and widely studied in the past several decades.


I'm not entirely sanguine about this description of thermochemical cycles, first because many are known thermochemical that do not require temperatures >2500K, (including the most famous thermochemical cycle, the sulfur iodine cycle) and secondly, I find the perfunctory and obligatory reference to solar thermal plants absurd. All of the thermal solar plants ever built on this planet after decades of cheering have been huge commercial and environmental disasters, the most egregious case being the Ivanpah plant in California, which has been more successful on shooting down precooked (or overcooked or even vaporized) birds in flight than in providing meaningful energy. If solar thermal plants were workable, decades of cheering for them would have made them practical and significant. They are neither.

Nevertheless, the paper is interesting; not all "solar thermal" thermochemical cycles are useless simply because it is straight forward to convert them to cleaner energy, that being nuclear energy.

The perovskite oxygen containing membranes are "cobalt free" although they do contain small amounts of praseodymium and cerium, generally the most available (along with neodymium) of the lanthanide elements to which I recently referred in this space while trashing the useless wind industry. Cerium in this case serves at the multivalent element necessary to conduct oxygen gas, along with iron. Their are two perovskites in this paper, utilized as a mixture, a cerium strontium iron version, and a praseodymium strontium iron version.

In order for this system to function efficiently, to remove oxygen from the splitting of carbon dioxide and water, the oxygen must be consumed. In some incarnations of similar systems, this is done by reacting the oxygen with the dangerous fossil fuel methane obtained from dangerous natural gas. And that's what they do here. (There are, of course, better things to do with oxygen, but we'll leave that aside for now.)

In this work, methane was used not only as a sweep gas to consume the permeated oxygen by the POM reaction, but also to produce additional synthesis gas with a H2/CO ratio of 2. Figure S5 presents the influence of temperature on the CH4 conversion, CO selectivity, and yield on the permeate/sweep side. It is shown that both CH4 conversion and CO yield increased with rising temperature. At 930 °C, a CH4 conversion of 62% and a CO selectivity of 99% were achieved, and synthesis gas at a rate of 3.9 mL min−1 cm−2 was obtained.


In any case, the thermochemical cycle can proceed in its entirety at less than 1000 degrees centigrade, and its certainly interesting, if less than entirely practical.

From the conclusion:

In conclusion, for the first time the effective generation of synthesis gas with H2/CO ratio of 2 by the simultaneous decomposition of water and carbon dioxide at the relatively low temperature of <1000 °C was experimentally demonstrated in an oxygen transport membrane reactor. Benefiting from the in situ fast removal of the generated oxygen by the membrane, the effective splitting of CO2 and H2O was achieved at lower temperatures, compared to the usual thermochemical decomposition. A synthesis gas flow rate of 1.3 mL min−1cm−2 on the feed side was obtained at 930 °C at a H2O/CO2 feed ratio of 5. To have a stable and sufficient driving force for oxygen permeation through the membrane, the oxygen partial pressure on the sweep side was effectively reduced using reactive methane as sweep gas. Simultaneously, synthesis gas at a rate of 3.9 mL min−1cm−2 was obtained on the methane side.


In consideration of the disadvantages of the conventional two-step thermochemical route on the requirement of ultrahigh-temperature and discontinuous oxygen transport, the combination of solar energy, catalytic thermolysis, and oxygen transport membrane reactor proposed in this work offers a new perspective and an alternative route to convert water and CO2 into synthesis gas.


Full details can be obtained by accessing the paper in a good science library or with a subscription.

I wish you a pleasant day tomorrow.

Some Reactor Physics for the Production of Anti-Proliferation Plutonium.

All of humanity's puny efforts to address climate change have failed. I keep a spreadsheet of data from the Mauna Loa Carbon Dioxide Observatory which compares the weekly measurement with the same measurement the year before. This week, the level of carbon dioxide was 2.07 ppm higher than it was a year ago, which compared with most of the data over the last 5 years, is relatively mild, but over the broader scale, highly disturbing. In the 20th century, the average of all such data (collected beginning in 1958) was 1.54 ppm per year. In the 21st century this same figure is 2.12 ppm. Of the 30 highest such data points, 19 occurred in the last 5 years, 21 in the last 10 years, and 23 in the 21st century. The highest ever such recorded piece of data was recorded on July 31, 2016, 5.04 ppm over the value for the same week in in 2015.

We are now approaching the late September/Early October annual minimum for atmospheric concentrations of the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere. It will be well above 400 ppm, 22 ppm or 23 ppm more than it was just ten years ago. No one now living will ever see carbon dioxide concentrations below 400 ppm in their lifetimes.

The popular response to addressing climate change consists these days almost entirely of hyping so called "renewable energy." Since so called "renewable energy" has not worked, is not working, and will not work, this approach is extremely dangerous to humanity, and indeed, all living things, particularly when one considers the trillions of dollars squandered on it in just the last ten years. Combined, all the solar and wind energy produced by all the expensive and useless facilities ever built in half a century of wild cheering cannot produce as much energy in a year as is produced by the annual increase in the use of the dangerous fossil fuel natural gas, said use being secured by the popular imagination about so called "renewable energy." ("Renewable" is, by the way is a fraudulent term, since wind and solar plants depend on access to either exotic or extremely dangerous materials.)

In more than 3 decades of study, I have convinced myself that the only option that might work to mitigate climate change, even to arrest it (although that's very unlikely), is nuclear energy.

Of course, nuclear energy suffers from a negative public perception owing to selective attention paid to its risks - and like all energy systems nuclear energy has risks - to the exclusion of the risks of all other forms of energy. For example, half of the 7 million air pollution deaths that take place each year result from dangerous fossil fuel waste, the other half from dangerous "renewable" dangerous biomass waste, and yet very little concern is expressed about this point compared to so called "nuclear waste," which I will argue below is not even "waste" at all.

Another fun comparison is the risk of nuclear war. Since the early 20th century, the vastly overwhelming number of people killed by weapons of mass destruction have been killed by fossil fuel weapons. The number of people killed by petroleum based weapons of mass destruction dwarfs the number of people killed by nuclear weapons of mass destruction; and yet no one calls for shutting petroleum refineries because crude oil can be and is diverted to make Napalm and jet fuel.

We cannot un-invent nuclear weapons, nor can we ever make them impossible, since the supply of uranium on this planet is inexhaustible. I showed this by appeal to the scientific literature elsewhere on the internet:

Is Uranium Exhaustible?

I offered my views on the implications of this fact in yet another place on the internet: On Plutonium, Nuclear War, and Nuclear Peace

We now have accumulated sufficient used nuclear fuel, which is incorrectly called by people who can't think clearly "nuclear waste" to do some of the remarkable things that scientists in the 1950's and 1960's envisioned for radioactive materials; this back when most of the world's nuclear reactors were designed not to generate energy, but to make weapons grade plutonium. Back then there simply wasn't enough, say, cesium-137, to destroy organohalides contaminating water supplies worldwide. Regrettably fear and ignorance of all things radioactive has prevented application of this superior approach to addressing such serious environmental issues.

Used nuclear fuel also contains considerable amounts of the elements neptunium and americium, which, I argued in one of the links above, are excellent tools for making plutonium - the key to any effort to serious effort to address climate change - that is simply unusable in nuclear weapons.

These ideas certainly don't originate with me; I merely report them. (I refer to them, as short hand, to the "Kessler solution" since Kessler is one of the nuclear scientists who has worked to advance this idea, although he is surely not the only one.)

Despite catcalls from the peanut gallery of folks who know nothing at all about nuclear energy but hate it anyway, highly educated and hightly trained nuclear engineers around the world have been working on these ideas, one hopes with a growing sense of urgency, since nuclear weapons are now being controlled by petulant brats who grew up isolated from the real world, the puerile so called "President of the United States" and the disgusting little twerp who rules North Korea.

In my files this morning, as I stumbled through some collected literature that I have had not yet reviewed, I came across this paper:

Long-life fast breeder reactor with highly protected Pu breeding by introducing axial inner blanket and minor actinides (Hamase et al Annals of Nuclear Energy 44 (2012) 87–102)

From the introductory text of the paper (with some artifacts of its translation from Japanese), we can grasp the basic idea:

In the wake of an interest in nuclear electricity production due to exhaustion of fossil fuels and issue of global warming, today the requirement of uranium (U) is increasing in the world. On the other hand, the prospect of U supply in the world has been reported to be about 100 years (OECD/NEA-IAEA, 2008) and the exhaustion of U resources is concerned with the expansion of nuclear power use. To meet the energy demand, a FBR has been focused on as a Pu producer. However, in the conventional FBR, generated Pu in axial/radial outer blankets consists of more than 93% of 239Pu. This kind of Pu is categorized as a ‘‘weapon-grade Pu’’ (Pellaud, 2002) and is concerned for nuclear proliferation. Recently, the concept of Protected Plutonium Production (P3) to increase the proliferation resistance of Pu by transmutation of MA has been proposed by Saito (2002, 2004, 2005). In this concept, MA can be utilized as an origin of 238Pu since dominant nuclides of MA such as 237Np and 241Am are mainly well transmuted to that isotope. The features of 238Pu, high decay heat (567 W/kg) and high spontaneous fission neutron rate (2660 n/g/s) (Matsunobu et al., 1991) are well known to hinder the assembling Pu in a nuclear explosive device (NED) and reduce the nominal explosive yield. Furthermore, it has been reported that 240Pu and 242Pu also play an important role for denaturing of Pu (Sagara et al., 2005), since 240Pu and 242Pu transmuted from MA has relatively large BCM and high spontaneous fission neutron rate (1030 n/g/s and 1720 n/g/s) (Matsunobu et al., 1991). Also, based on the P3 proposal, Meiliza et al. (2008) has reported that the proliferation resistance of Pu produced in axial/radial blankets of conventional FBR was increased by doping a small amount of MA into axial/radial outer blankets. MA is, therefore, effective to mitigate the nuclear proliferation concern.


"BCM" is "bare critical mass."

The paper contains a great deal of technical information about the reactor design and properties, and various cases are shown.

Depending on the type of fuel used, (oxide or metal) the reactor can be designed to operate for as long as 6000 full power days, roughly 16 years. Plutonium that is undergoing fission is hardly available for making nuclear weapons, and in any case, the usefulness of any plutonium in the reactor for use in nuclear weapons is greatly reduced by the presence of denaturing isotopes, in particular the heat generating isotope 238Pu (the same isotope that powered the Cassini mission).

Basically these types of reactors are essentially fueled by depleted uranium. One can show that the uranium already mined, along with the waste thorium generated by the failed and useless wind and electric car industry, can easily fuel all of humanity's energy needs for several centuries to come without any mining of any energy related material of any type, no petroleum, no coal, no natural gas, and indeed, no lanthanides, cadmium, etc, etc for useless wind and solar junk.

From the paper's conclusion:

The feasibility study on simultaneous approaches to the extension of core life-time and the high protected Pu breeding by introducing the axial inner blanket and doping MAs in a large-scale sodium-cooling FBR has been performed for mix-oxide MOX and metallic fuel. Firstly, as the extension of core life-time, the analytical results showed that if MA was doped into the axial inner blanket, the main fission reaction zones were shifted from the active core to the axial inner blanket, and the core life-time was extended remaining reactivity swing small because 238Pu transmuted from MA was the fissionable nuclide in the fast neutron region. The maximum available EFPDs in MOX-fueled FBR with introducing the axial inner blanket and MA was extended from 1700 to 2900 compared with the conventional MOX-fueled FBR. The maximum available EFPDs in the case of metallic-fueled FBR with introducing the axial inner blanket and MA was extended to 5900.

Secondly, as the proliferation resistance of Pu, it has been reported that Pu produced in axial/radial outer blankets of conventional FBR was increased by doping a small amount of MA into them, and ATTR, an evaluation function of proliferation resistance of Pu based on isotopic material barriers such as DH and SN, has been suggested to categorize produced Pu. In the present paper, conventional ATTR was modified by taking into account BCM as ATTRmod, which was applied to evaluate the proliferation resistance of Pu generated in the axial inner blanket and axial/radial outer blankets. It was found that if 40 wt.% and 28.5 wt.% of MA were doped into the axial inner blanket in MOX and metallic fuel, respectively, the proliferation resistance of Pu generated in the axial inner blanket was significantly increased to satisfy the criteria of ‘‘practically unusable for an explosive device’’ proposed by Pellaud and ‘‘technically unfeasible for a high-technology HNEDs’’ proposed by Kessler and Kimura. Assumed that Pu generated in the axial inner blanket and also axial/radial outer blankets were collected and reprocessed together, the proliferation resistance of Pu generated in all blankets was also increased. Furthermore, in order to increase the proliferation resistance of Pu generated in axial/radial outer blankets, only 4 wt.% of MA was required in MOX and metallic fuel. For not purpose of extension of core life-time, only 5 wt.% of MA doping into the axial inner blanket was needed to increase the proliferation resistance of Pu in MOX and metallic fuel.


I am not necessarily, by the way, endorsing this particular reactor; it's sodium cooled, and I personally don't like sodium coolants. But the basic ideas of plutonium management are very important, since plutonium is the last best hope of Earth.

Have a nice Sunday afternoon.

Working with one of the most refractory and hardest materials known Tantalum Hafnium Pentacarbide.

Generally, most people are aware that spacecraft and supersonic aircraft require refractory (high melting) materials to avoid being burned up by air friction.

Since the end of the "space race" and the "cold war" there has been less interest in refractory materials than there might have been some years back, something I know from having attended a bunch of presentations of materials science departments while my son was selecting a school.

Be that as it may, whether it is generally known or not, is that future generations, owing to our inattention, fixation on dumb ideas that don't work, and general irresponsibility, will require refractory materials to reverse whatever can be reversed from our willingness to screw them over by dumping trillion ton quantities of dangerous fossil fuel waste (at a rate of over 30 billion tons per year) while we all wait, insipidly, like Godot, for the grand solar and wind Nirvana that never comes (and never will come.)

I could discuss that for hours, but rather than do so, I'd rather simply focus on a paper I collected some time ago on a rather remarkable material that fits the bill, Ta4HfC5, tetratantalum hafnium pentacarbide.

The paper I'll discuss is this one: Reduced-temperature processing and consolidation of ultra-refractory Ta4HfC5 (Int. Journal of Refractory Metals and Hard Materials 41 (2013) 293–299)

The introduction gives a nice description of the remarkable properties of this material:

Carbides, nitrides, and borides are of interest for many applications because of their high melting temperatures, high elastic moduli, and high hardness. Among all refractory compounds, 4TaC-HfC ranks among the highest, with an estimated melting temperature of 3942 °C and hardness of approximately 20 GPa at 100 g-f [1–3]. TaC is the most metallic of the IV and V transition metal monocarbides. It has the NaCl-type structure (B1, space group Fm3−m) and an exceptionally high melting point of 3880 °C [4–7]. TaC's relatively good oxidation resistance and resistance to chemical attack have been attributed to strong covalent-metallic bonding [8]. Other relevant properties of TaC include high strength, high hardness (11 to 26 GPa), wear resistance, fracture toughness (KIC ≈ 12.7 MPa-m1/2), low electrical resistivity (42.1 μΩ-cm at 25 °C), and high elastic modulus (up to 550 GPa). TaC is also reported to exhibit a ductile-to-brittle transition in the temperature range 1750–2000 °C that allows it to be shaped above the DBTT, and it also exhibits ductility of 33% at 2160 °C [9–12]. Similarly, HfC also crystallizes in the NaCl-type structure (B1, space group Fm3−m, close packed), and exhibits a high melting point (3890 °C, the highest among the binary metallic compounds) [13–15]. HfC also has good chemical stability, high oxidation resistance, high hardness (up to 33 GPa [16]), high electrical and thermal conductivity, and a high Young's modulus (up to 434 GPa) [17–24]. HfC has found applications in coatings for ultrahigh-temperature environments due to its high hardness, excellent wear resistance, good resistance to corrosion, and low thermal conductivity. HfC is also found in high-temperature shielding, field emitter tips, and arrays (HfC has the lowest work function of all transition metal carbides). In addition, HfC can be used as a reinforcing phase in tool steels [25–27].


However, if you reflect on it for even a moment, you realize the difficulty of working with such a material. It cannot be worked easily, and as it's melting point is higher than almost any container in which it can be processed, it certainly can't be cast. It's melting point is even higher than remarkable materials like uranium nitride, thorium nitride and thorium carbide. (Thorium oxide, which is mildly radioactive, has been widely used for ceramic refractory crucibles for handling molten metals.)

Such materials can only be handled by sintering, which involves heating them to roughly two thirds of their melting temperature (pretty extreme in any case) and applying extreme pressure, conditions under which the elements can diffuse to a smaller to larger extent.

In this case, the authors milled hafnium carbide and tantalum carbide powders for a long period of time (18 hours) and placed them in a graphite press under a pressure roughly 1000 times atmospheric pressure, and heated them at 1500 C (much lower than the melting point) and got pretty decent tetratantalum hafnium tetracarbide. (Machining this stuff is yet another problem, not addressed here.)

This material is not ready for prime time, nor will it ever be.

Tantalum is mostly utilized in cell phones, where it is a constituent of the supercapacitors on which those devices depend. The mining of tantalum is a great human tragedy, the "coltan" issue. (Tantalum is always found in ores that also contain niobium which was formerly known as columbium, hence the name "coltan" for the ore.) Tantalum is one of the "conflict" elements, and mining it is simply a horror.

This disturbing documentary, "Blood Coltan" is available on line:



Hafnium is a side product of the nuclear industry. It is always found in ores of its cogener zirconium, which is widely used in nuclear reactors. Typically the amount of hafnium in zirconium ores is on the order of 1-3% However, since hafnium has a very large neutron capture cross section (and is sometimes used in control rods, particularly in small reactors like those on nuclear powered ships) it must be removed from zirconium before the zirconium can be used in nuclear reactors.

It is possible however, to obtain pure hafnium free zirconium from used nuclear fuel, where it is a major fission product. The chemical separation of hafnium and zirconium is nontrivial, as is the chemical separation of niobium and tantalum, owing to the "lanthanide contraction." It is possible to obtain monoisotopic zirconium, zirconium-90, (which is lighter than "natural zirconium) from the decay of the fission product Sr-90, itself a useful heat source. Thus at some point it may be cheaper to utilize fission product zirconium instead of natural zirconium, at least it would be so in a sensible world run by intelligent and responsible people, a nuclear powered world.

But we don't live in such a world. (One may hope that future generations will be smarter than ours.)

This said, this information might be useful under many imaginable exotic conditions, and I found it interesting.

Have a nice Sunday.

Biodegradable Hydrogels for Glucose Sensitive Insulin Delivery to Treat Diabetics.

Insulin is not a cure for Type I diabetes; it is a treatment. The distinction is important for this disease which, unlike type II diabetes which strikes older people, tends to strike people in their childhood.

A diagnosis of Type I insulin dependent diabetes means, at best, a life time of carefully monitoring one's own blood for glucose concentrations, and repeatedly, as appropriate, injecting one's self with insulin. A miscalculation can lead to hypoglycemia and sometimes serious health effects.

Many alternative ways of delivering insulin have been explored, and a few commercialized, but needles remain the main way of addressing the disease, and moreover, it is not always easy to calibrate the times at which one needs or needs to avoid such an injection.

It would be nice if there were a method for delivering insulin in a way that was responsive to sugar concentrations. Thus it was encouraging to come across a paper published in the scientific journal ACS Applied Materials and Interfaces, this one:

Supersensitive Oxidation-Responsive Biodegradable PEG Hydrogels for Glucose-Triggered Insulin Delivery (Li et al ACS Appl. Mater. Interfaces, 2017, 9 (31), pp 25905–25914)

The authors write thusly:

Hydrogels have been investigated extensively and utilized widely in the fields of biotechnology, regenerative medicine, pharmaceutics, and personal hygiene.1−4 In the past two decades, responsive hydrogels have attracted particular attention owing to their great promise for delivery of drugs and bioactive macromolecules,5−7 sensing,8,9 diagnosis,10 bioanalysis and bioseparation,11,12 cell culture or tissue engineering,13,14 and so forth. Although various physical or (bio)chemical stimuli, including temperature, pH, light, enzymes or other biomolecules, reduction or electrochemical redox potential, mechanical force, and magnetic field, have been applied as triggers to induce the formation, change in shape or morphology, and degradation or dissociation of hydrogels,15−17 there are only a few papers on oxidation-responsive polymeric hydrogels that suffer from the weaknesses of low sensitivity or low response rate toward reactive oxygen species (ROS) or low mechanical strength...

... Although a number of papers report polymeric or supramolecular hydrogels that contain phenylboronic acid/ ester moieties, a majority of them are associated with the glucose- or pH-sensitivities of these hydrogels.43−50 Recently, Hamachi and co-workers have reported H2O2-responsive supramolecular hydrogels formed by self-assembly of the hydrophobic p-boronophenyl methoxycarbonyl-capped di- or tripeptides. By incorporating various oxidative enzymes, such as glucose oxidase (GOx), into these hydrogels, they demonstrated a simple strategy for constructing, without tedious synthesis, soft materials responsive to various biochemical stimuli, such as glucose.51,52 Their works greatly expanded the applications of oxidation-responsive hydrogels. In this article, we describe a novel kind of oxidationresponsive hydrogels that were fabricated by the redox-initiated radical polymerization of a 4-arm-poly(ethylene glycol) (PEG) macromonomer having H2O2-cleavable acrylic bonds at the chain ends (Scheme 1). The hydrogels can be degraded by H2O2 via the sequential oxidation and 1,6-/1,4-elimination of the phenylboronic acid linker.53 These hydrogels are designed to be biocompatible and extremely sensitive to H2O2 because they were composed of hydrophilic PEG network and a small fraction (<10 wt %) of hydrophobic but highly sensitive linkers.54


The authors have only tested their hydrogen in vitro, it's degradation by glucose, as well as it's cytotoxicity against cultured cells.

I would imagine that their tox work will be significant, both in China and in the US if they bring the product here. Thus any commercial application is at least a decade off. It's interesting work though, and one hopes that if not this product, similar products will become available to serve as quasi-synthetic pancreases.

Their work was supported by the National Science Foundation of China, China being a government that unlike the current US government, does not hate science and scientists.

Enjoy the weekend.

A Beautiful Review Article on the Total Synthesis of Vancomycin.

Recently in this space, I mused on the biosynthetic origins of very complex natural products from the natural (by which I mean "genetically coded" ) amino acids.

A wonderful place to consider the interface of RNA catalysis and enzyme catalysis.

My post by the way, contains a statement that is wrong, this one:

We see some very complex natural products of extreme importance to humanity, the total synthesis of which remains even in these times synthetically inaccessible. Examples include the core of taxanes, an important class of cancer drugs, as well as many complex antibiotics like for instance, vancomycin, which clearly involves tyrosine and phenylalanine origins...


I certainly knew better about both taxanes and vancomycins, but somehow wrote this statement anyway. Perhaps I meant to say "industrially synthetically accessible." I can't say. I wrote that post apparently late at night, several weeks ago.

Whatever.

The lab scale synthesis of these kinds of molecules, including Vancomycin, is a part of a very beautiful scientific discipline, "natural product synthesis," for which many Nobel Prizes have been awarded.

I have just alluded to one reason for doing these kinds of syntheses, which is that they are beautiful, works of art, works of high art. The other reason is more practical. By understanding how to manipulate the features of molecules of this complexity, one can make analogues which may be better suited for reasons of pharmacokinetics, toxicology, and (very importantly) bioavailability, bioavailability being the property of delivering a drug to the cellular or biochemical pathologically active regions.

The total synthesis of Vancomycin has been reviewed in a very nice article in the current issue of Chemical Reviews, this one:

Total Syntheses of Vancomycin-Related Glycopeptide Antibiotics and Key Analogues



One of the authors is Dale Bolger, who received his Ph.D. from one of the great synthetic chemists of all time, E.J. Corey. (I have had two friends who worked in Corey's lab, both reported he was personally a bit of an ass, but irrespective of that, he is one of the greatest American scientists of all time.)

Bolger is one of the world's great synthetic chemists (now at the Scripps Institute) worked himself on Vancomycin syntheses, and reviews the great work of other labs.

Bolger's text reiterates the practical raison d’être for syntheses of this type, in the text of the introductory paragraphs of the review:

An important development in the field of glycopeptide antibiotics occurred in the late 1990s when three groups independently achieved the total synthesis of vancomycin. Given the sheer structural complexity of the natural product, this series of synthetic accomplishments was remarkable and at the frontier of the field of organic synthesis at that time. With reports of the rapid increase in resistant bacterial strains by health officials, this effort was driven not only by the challenge of developing an effective route to the complex natural product but also to pave the way for biological interrogation of previously inaccessible synthetic analogues. Herein, we review only work completing total syntheses of members of the vancomycin-related glycopeptide antibiotics, their aglycons, and synthetic analogues. Work on their semisynthetic modifications(1, 2) and methodological studies are not reviewed as they have been covered elsewhere.

The glycopeptide antibiotics are currently among the leading members of the clinically important natural products discovered through the isolation of bacterial metabolites. They possess a broad spectrum of antibacterial activity against Gram-positive pathogens with manageable side effects. Since their clinical introduction, the glycopeptide antibiotics vancomycin (1) and teicoplanin (6) have become the drugs of “last resort” when resistant bacterial infections are encountered (Figure 1). With the emergence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin (1) has been widely used in the clinic as the “go to” treatment.(3, 4) Originally restricted to hospitals, today more than 60% of both ICU (intensive care unit) and community acquired S. aureus infections are MRSA(5, 6) and were responsible for nearly 12 000 deaths in the United States in 2011 alone.(7) Moreover, infectious diseases (e.g., influenza and pneumonia), complicated by additional bacterial infections often requiring treatment with vancomycin, are ranked among the leading causes of death in the United States. The glycopeptide antibiotics are also recommended for use with patients allergic to β-lactam antibiotics and those undergoing cancer chemotherapy or ongoing dialysis therapy.(8) Consequently, the importance and clinical use of vancomycin continues to steadily increase since its introduction 60 years ago.(9) As vancomycin-resistant bacteria have been observed in the clinic in both enterococci (VRE, 1987)(10) and S. aureus (VRSA, 2002)(11-17) and as the prevalence of antibiotic-resistant pathogens has increased, discovery of the next-generation durable antibiotics capable of addressing such bacterial infections has become an increasely urgent problem.(18)


Since the establishment of the structures of glycopeptide antibiotics, extensive synthetic efforts have been made through both semisynthetic and total synthesis means. These studies have laid the foundation for ongoing structure–function studies of the antibiotics, aiding in the definition of their mechanism(s) of action. They have also elucidated unanticipated new roles for added non-naturally occurring functionality that have led to the discovery of improved or rationally designed glycopeptide antibiotics.


Here's a figure from the text which particularly appealed to me:



Figure 4. Evans retrosynthetic analysis of vancomycin aglycon.

Organic chemists will recognize that molecule 28 itself, an oxazolidone derived (probably by phosgenation) from (3-chloro-5-nitro-4-fluorophenyl)-β-hydroxyalanine, a early stage precursor in the Evans synthesis it itself a nontrivial synthetic target, owing to its substitution pattern. Early in my career, I had the pleasure of working on BOC and FMOC N protected oxalidones, albeit diones.

Final stages of the Evans synthesis:



Esoteric, but interesting, I think.

A Minor Problem For Sound Science of the Effect of Offshore Windfarms on Seabirds: There Isn't Any.

I've just been leafing through a wonderful book that one wishes didn't have to be written.

It's um, this one: Why Birds Matter

One of my scientific interests is material flows in which I focus on particular elements in the periodic table, and I've collected and read a great deal of literature on that subject. One very important element is the element phosphorous, on which the real "green revolution" - that would be the fertilizer revolution in the 1950's and not the absurd scheme to lace the world with wind turbines and solar cells - depended.

Why Birds Matter is written for our times, inasmuch the argument consists of a great deal of comment on the economic importance of birds, and what it would cost to the human economy if they ceased to exist, and they may cease to exist; many species have already done so, and more are sure to follow.

The only thing we really, really, really care about is, um, money, right and left.

And one of the big economic drivers on this planet is, um, food.

We absolutely must have phosphorous, to feed humanity and for that matter, all living things, whether or not we decide that the only people who should eat are those who can pay for it.

It turns out that one of the most important sources for phosphorous on this planet is, um - well there's no nice way to put it - bird shit. And this is the topic of chapter 9 in "Why Birds Matter."

The island nation of Nauru once had the highest per capita income in the world because it was the chief exporter of bird shit, or what bird shit had become after a few million years, phosphate rock. After Nauru, a small country, dug up all the bird shit on the island and exported it to Australia and New Zealand and elsewhere, the government decided to "invest" all the money, and all the investments went bad, and now Nauru is a very poor country with no resources, very little remaining phosphate, a population with a diabetes problem and an economy based on warehousing Islamic refugees who tried to make it to Australia but who were intercepted by the Australian Navy.

So Nauru needs seabirds to shit on it again. But seabirds are in trouble.

And one of the big trouble for seabirds is, um, wind farms, which are often, to my personal regret, described by people on our end of the political spectrum as "green" and good for the environment.

They are no such thing. I was recently challenged here to produce some um, "peer reviewed" literature (which isn't by the way, magical) on the negative impact of wind farms on the environment, and I pulled some stuff out of my files, and poked around the recent literature on the topic. Here is my response to the challenge: Sure, I'd be pleased to...

After poking around a bit for some more updated stuff than what's in my files, I came across this nice piece: Lack of sound science in assessing wind farm impacts on seabirds (Green et al, Journal of Applied Ecology 2016, 53, 1635–1641) I believe it may be open sourced, so you can read it yourself if you're not in a library. (I'm in a library as I write, so I can't tell if it's open sourced, but I think it is.)

Some text from the paper:

Electrical power generation from wind farms has grown rapidly in the UK and European Union (EU) in the last decade and is set to grow further. By 2020, the EU proposes to source 20% of energy from renewable sources (Directive 2009/28/EC). Wind energy is expected to provide 9–14% of global electricity generation by 2050 (IPCC 2011). This may eventually reduce climatic change and its negative impacts on biodiversity, but there are also several poorly quantified negative effects on wild species of renewable energy generation, including wind turbines. For example, birds and bats are killed by colliding with turbine blades or towers and there may be effects of wind farms on mortality and reproductive rates of a wide range of species from avoidance and displacement. Birds may incur additional costs or forego benefits because of reduced transit or foraging within or near to wind farms (Drewitt & Langston 2006; Searle et al. 2014). Depending upon the strength of density-dependent compensatory processes, these effects could reduce the population to a lower stable level or cause its extinction (Wade 1998; Niel & Lebreton 2005)...


And...

Estimates of the effects of wind farms on seabird demographic rates are neither robust nor validated

Collision risk models (CRMs) are used to predict the number of fatal collisions of flying birds with wind turbines and per capita additional mortality rates. In the UK, the most widely used CRM is that of Band (2012) (see review by Masden & Cook (2016)). The model requires estimates or assumptions about bird numbers and ages at the wind farm, attribution of birds at the wind farm to source populations, sizes and age structure of source populations, flight behaviour and avoidance rates. Data specific to the project and species being assessed are usually collected on seabird numbers and flight heights, judged by eye, but these estimates are subject to substantial uncertainties, variability and potential biases (Johnston et al. 2014), including:

1.accuracy of input variables is rarely quantified, is often poor, and the CRM outputs are highly sensitive to the values used, including flight speed (Masden 2015), and avoidance rate estimates;
2.in many cases, birds at risk are not attributed to source populations because recently developed tracking technologies are either not deployed at all or not on a sufficient scale for robust estimation;
3.count and flight height data are usually insufficient in quantity and quality for precise estimation of seasonal variation, age structure and age differences (Band 2012).

Total avoidance rates used for CRM calculations for seabirds, including within-wind farm avoidance of individual turbines and macro-avoidance by movement of birds around the turbine array, are most often based upon judgement or extrapolation from other contexts rather than pertinent data. Empirical values are only available from a few species (mostly gulls and terns) and usually extrapolated from studies of onshore wind farms, where different circumstances prevail (Cook et al. 2014). Robust direct estimates of within-wind farm avoidance rates are lacking for seabird species frequently present in and near planned and consented offshore wind farms in the UK, such as northern gannet Morus bassanus and black-legged kittiwake Rissa tridactyla (Cook et al. 2014). Macro-avoidance and displacement rates have been estimated using radar, visual surveys and imaging, but robust quantitative estimates...


By the way, birds and bats are only part of the reason that the wind industry sucks, but it is, I think, an important part.

The wind and solar industries are nothing more than fig leafs for the dangerous gas industry, and the dangerous natural gas industry is killing us as surely as the dangerous coal industry is.

This post won't get the more than 60 recs a post on this website got for a poorly reported blurb about how wonderful the wind industry is for, um, mussels, but I think if we cannot question our own assumptions, cannot rethink our biases, we will not serve humanity.

Don't be rote. Think.

Have a nice day tomorrow.


Quorum-Sensing Peptide-Modified Polymeric Micelles for Brain Tumor-Targeted Drug Delivery

The title of this post comes directly from the paper I'll briefly discuss here, this one: d-Retroenantiomer of Quorum-Sensing Peptide-Modified Polymeric Micelles for Brain Tumor-Targeted Drug Delivery (Lu et al ACS Appl. Mater. Interfaces, 2017, 9 (31), pp 25672–25682)

I don't spend as much time with this journal as I'd like, and I'd never have the time to follow it entirely; it's a rich journal published weekly, and it's full of wonderful stuff.

This paper caught my eye though: My mother died from a brain tumor as a relatively young woman. It wasn't pretty, and the memory of that event never went away; it never will go away, until at least, I die. I can touch anyone of those horrible associated events as if they were taking place now; it was that awful.

But this is a very cool paper from a purely scientific stance, since it begins with a discussion of the lives of bacteria (which generally have nothing to do with brain tumors) and moves to the behavior of cells in our brains. (That's beautiful.)

The text from introduction to the paper says pretty much what it's about:

Bacteria communicate with each other by secreting chemical signal molecules into the surrounding environment during their growth processes.1,2 When the number of signal molecules reach a certain threshold level, biological effects, such as regulation of gene expression, biofilm formation, or bioluminescence, will be exerted.3,43,4 This phenomenon is called bacterial quorum sensing (QS). QS peptides are a class of biologically attractive molecules. They have a wide variety of structures and display many functions.2,4−6 Recently, QS has received widespread attention because it can influence cancer and different central nervous system-related disorders, such as anxiety, depression, and autism.7−13 For example, Salmonella produces anticancer proteins with the potential to kill tumors through QS systems.14 Some QS peptides have also been reported to cross the blood−brain barrier (BBB).15 LWSW (also named PhrCACET1) is a recently reported peptide originating from Clostridum acetobutylicum. It could effectively cross the BBB and showed a measured brain clearance.16 Currently, many researchers focus on peptides acting in brain and their therapeutic potential.5,17 WSW peptides could be ideal targeting moieties to facilitate brain-targeted drug delivery. In addition, WSW peptides are able to target glioma cells and tumor neovasculature, suggesting that WSW peptides may be useful ligands for intracranial glioma targeting.


The authors synthesize some "retro-inverso" peptides and put a paclitaxel payload on them. Paclitaxel is a very famous anti-cancer drug in the taxol family; it slows the replication of wildly dividing cells like cancer cells by interfering with spindle formation in mitosis. This drug was originally discovered in the bark of relatively rare yew trees in the Pacific Northwest, causing some people to worry about the extinction of the tree to make cancer drugs. The world chemical community was, however, able to synthesize the drug from precursors found in dead yew pine needles, saving the trees and saving lives.

The payload approach, attaching a cancer drug to a protein (or in this case a peptide) that will recognize a target is very popular these days, particularly with antibodies. Antibodies having cancer (or other) drugs attached to them are known as "ADC's" or "Antibody Drug Conjugates." Peptides (which are short stretches of coupled amino acids not long enough to be considered a protein) also have recognition ability, although their conjugated use for payload delivery is somewhat more rare.

"Retro-inverso" peptides are peptides where the sterochemistry, the three dimensional arrangement of the constituent amino acids, is inverted from the stereochemistry of the natural amino acids, all of which (except cystine for reasons of nomenclature) have an "S" configuration as opposed to the unnatural "R" configuration. R and S in the case of amino acids refers to D and L configurations; all natural amino acids are L; their mirror images are D.

(If you are unfamiliar with this concept, this nice internet picture may help:


These are different molecules because like your hands, which are also mirror images, they cannot be superimposed upon one another.)

A "retro-inverso" peptide is one in which all the amino acids are D rather than L. This gives them a much longer biological half-life than they would have if they were L, giving them more time to have their biological effect.

(The "retro-inverso" approach was pioneered by the late Dr. Murray Goodman at UCSD. I knew him well enough personally to be on a first name basis with him; he once took me to lunch at the faculty club where he wanted to know how it was that I spoke French. He was a very nice man, and a very impressive scientist.)

This approach seems to have worked quite well on mice having gliomas (brain cancer tumors).

From the text:

Our results showed that WSW peptide-modified functional materials endowed micelles with the abilities of binding to and penetrating the BBB and BBTB. The retro-inverso isomerization strategy was applied to improve the stability of the WSW peptides. The cocultured BBB (or BBTB)/U87 tumor spheroid model was also constructed to confirm the superiority of the DWSW peptide. The DWSW peptide could transverse the BBB more efficient than the LWSW peptide both in healthy mice and in glioma-bearing mice. DWSW could remain intact after traversing the BBB and enzymatic barrier, exerting targeting capability to the glioma site. WSW-modified micelles loading PTX demonstrated good inhibitory effects against U87 cells, HUVECs, VM, and HUVEC three-dimensional tubes in vitro. By specifically targeting tumor cells, tumor angiogenesis, and VM, DWSW Micelle/PTX significantly prolonged the survival time compared with other groups and achieved the best antitumor effect.


Here's a nice picture of what's going on in this work from the paper itself:



This work by the way comes out of the Department of Pharmaceutics, School of Pharmacy, Fudan University & Key Laboratory of Smart Drug Delivery (Fudan University), Ministry of Education, Shanghai 201203, China.

This science was supported by the Chinese government.

At one time we had a government that supported and encouraged science and funded it.

We now have a government composed entirely of a class of people who hold science and scientists in total contempt; who hate science and scientists. They're called "Republicans."

We allow these awful people to rule us at terrible risk to ourselves and all future generations of Americans.

I wish you a happy and productive work week.





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