Investigation of the Solid Electrolyte Interface on LiMn2O4 through Neutron Reflectometry.

The Solid Electrolyte Interface (SEI) is of significant importance to successful operation of new high-energy-density lithium-ion batteries. The SEI governs chemical interaction between the electrode (cathode or anode) and the electrolyte in addition to modulating the diffusion of lithium between the mediums. SEI stability throughout the lifetime of the lithium-ion battery is essential for long-term stable operation. While both the anode and cathode exhibit an SEI growth, the anode growth is much thicker and more easily probed. In contrast, the SEI on the cathode is very thin on the order of nanometers and has proven to be much more difficult to probe in-situ. This dissertation focuses on the application of Neutron Reflectometry (NR) to the study of the SEI on a Li_xMn_yO_z thin-film cathode. A cathode which meets the stringent morphological requirements for NR is developed with a roughness <2 nm rms. The thin-film cathode is produced by a sol-gel spinning technique on a silicon substrate with platinum and silicon dioxide thin-films which serve as charge collection and buffer layer. A method of electro-depositing lithium on a copper thin-film is developed to produce a dendrite-limited lithium thin-film anode to serve as the counter/reference electrode in an experimental cell. An electrochemical NR sample cell is built to produce a fully-functional full-cell battery for in-operando NR experimentation. Two in-operando NR experiments are performed where one sample is allowed to sit at an open-circuit, and the other has the potential held slightly above the reported open-circuit potential for LiMn2O4 to prevent self-discharge. NR results indicate a SEI of thickness between 10-16 nm is formed immediately upon introduction of the electrolyte. The scattering length density of the SEI which forms during the open circuit experiment is observed to be lower than that of the SEI on the potential hold experiment. The thickness of the cathode layer is observed to increase throughout the experiment to an extent which is not explainable by known volume expansion of LiMn2O4 through a Jahn-Teller effect. The SEI formed by cycling the battery prior to allowing self-discharge to form LiMnO2 is observed to prevent significant degradation of the cathode layer.PHDNuclear Engineering and Radiological SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111353/1/bkitchen_1.pd

Review: Applications of Bayesian Skyline Plots and Approximate Bayesian Computation for Human Demography

Bayesian methods have been adopted by anthropologists for their utility in resolving complex questions about human history based on genetic data. The main advantages of Bayesian methods include simple model comparison, presenting results as a summary of probability distributions, and the explicit inclusion of prior information into analyses. In the field of anthropological genetics, for example, implementing Bayesian skyline plots and approximate Bayesian computation is becoming ubiquitous as means to analyze genetic data for the purpose of demographic or historic inference. Correspondingly, there is a critical need to better understand the underlying assumptions, proper applications, and limitations of these two methods by the larger anthropological community. Here we present a review of Bayesian skyline plots and approximate Bayesian computation as applied to human demography, as well as provide examples of the application of these methods to anthropological research questions. We also review the two core components of Bayesian demographic analysis: the coalescent and Bayesian inference. Our goal is to describe their basic mechanics in attempt to demystify them

Conversion of an intensified fed-batch to an integrated continuous bioprocess

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Isotopic evidence for quasi-equilibrium chemistry in thermally mature natural gases

Natural gas is a key energy resource, and understanding how it forms is important for predicting where it forms in economically important volumes. However, the origin of dry thermogenic natural gas is one of the most controversial topics in petroleum geochemistry, with several differing hypotheses proposed, including kinetic processes (such as thermal cleavage, phase partitioning during migration, and demethylation of aromatic rings) and equilibrium processes (such as transition metal catalysis). The dominant paradigm is that it is a product of kinetically controlled cracking of long-chain hydrocarbons. Here we show that C₂₊ n-alkane gases (ethane, propane, butane, and pentane) are initially produced by irreversible cracking chemistry, but, as thermal maturity increases, the isotopic distribution of these species approaches thermodynamic equilibrium, either at the conditions of gas formation or during reservoir storage, becoming indistinguishable from equilibrium in the most thermally mature gases. We also find that the pair of CO₂ and C₁ (methane) exhibit a separate pattern of mutual isotopic equilibrium (generally at reservoir conditions), suggesting that they form a second, quasi-equilibrated population, separate from the C₂ to C₅ compounds. This conclusion implies that new approaches should be taken to predicting the compositions of natural gases as functions of time, temperature, and source substrate. Additionally, an isotopically equilibrated state can serve as a reference frame for recognizing many secondary processes that may modify natural gases after their formation, such as biodegradation

Nachweis und Quantifizierung von Drogen und anderen Fremdstoffen in Blutspuren auf verschiedenen Trägermaterialien

Es wurde ein gaschromatographisch-massenspektrometrisches (GC/MS)-Verfahren zum Screening und Nachweis von Morphin (4,5alpha-Epoxy-17-methyl-7-morphinen-3,6alpha-diol), Codein (4,5alpha-Epoxy-3-methoxy-17-methyl-7-morphinen-6alpha-ol), Heroin (4,5alpha-Epoxy-17-methyl-7-morphinen-3,6alpha-diyldiacetat), Kokain ((-)-Methyl-[3beta-benzoyloxy-2beta(1alphaH,5alphaH)-tropancarboxylat]), Benzoylecgonin (Tropin-2-carbonsäure-benzoylester, Methylecgonin (Tropin-3-carbonsäure-methylester), Cocethylen ((-)-Ethyl-[3beta-benzoyloxy-2beta(1alphaH,5alphaH)-tropancarboxylat]), THC (Delta-9-tetrahydrocannabinol), THC-Carbonsäure (11-Nor-9-carboxy-delta-9-tetrahydrocannabinol),, 11-OH-THC (11-hydroxy-delta-9-tetrahydrocannabinol), Amphetamin ((±)-alpha-Methylphenethylamin), Methamphetamin (N,alpha-Dimethylphenethylamin), MDA (Methylendioxyamphetamin; Tenamfetamin, alpha-Methyl-3,4-methylendioxy-phenethylamin), MDMA (Methylendioxymethamphetamin; N,alpha-Dimethyl-3,4-methylendioxy-phenethylamin) und MBDB (N-Methylbenzodioxazolylbutanamin) in kleinen Blutproben und Blutspuren unter Verwendung von Festphasen-SPE-Säulen und einem Pipettierroboter (Gilson Aspec XL) beschrieben. Die Nachweisgrenzen liegen zwischen 1,62 und 4,10 ng / 50 µl Spot (Amphetaminderivate), 0,15 und 0,82 ng / 50 µl Spot (Cannabinoide), 1,67 – 4,70 ng / 50 µl Spot (Kokain und dessen Derivate) sowie 4,53 und 4,91 ng / 50 µl Spot (Opiate) und die Korrelationsfaktoren zwischen 0,9957 und 0,9999. Weiterhin wurde die Nachweisbarkeit auf verschiedenen Spurenträgern (Holz, Stoff (Textil), Metall, Fliesen und Glas) untersucht. Dabei ergab sich, dass ein qualitativer Nachweis noch nach mindestens 64 Tagen möglich war, die quantitative Bestimmung jedoch auf Schwierigkeiten stieß. Ursachen hierfür sind beispielsweise Chargenunterschiede der Säulenmaterialien und andere Effekte, die beim Arbeiten im spurenanalytischen Bereich in der Nähe der Nachweis- und unteren Bestimmungsgrenze von großem Einfluss sind. Mit Hilfe der im Rahmen dieser Arbeit entwickelten Methode konnten 2 spektakuläre Kriminalfälle aufgeklärt werden.A GC/MS-method is developed for the screening and detection of morphine (4,5a-epoxy-17-methyl-7-morphinen-3,6a-diol), codeine (4,5a-epoxy-3-methoxy-17-methyl-7-morphinen-6a-ol), heroin (4,5a-epoxy-17-methyl-7-morphinen-3,6a-diyldiacetate), cocaine ((-)-methyl-[3beta-benzoyloxy-2ß(1alphaH,5alphaH)-tropancarboxylate]), benzoylecgonine (tropin-2-carboxylic acid-benzoylester, methylecgonin (tropin-3-carboxylic acid-methylester), cocethylene ((-)-ethyl-[3beta-benzoyloxy-2beta(1alphaH,5alphaH)-tropancarboxylate]), THC (delta-9-tetrahydrocannabinol), THC-carbonic acid (11-Nor-9-carboxy-delta-9-tetrahydrocannabinol), 11-OH-THC (11-hydroxy-delta-9-tetrahydrocannabinol), amphetamine ((±)-alpha-methylphenethylamine), methamphetamin (N,alpha-dimethylphenethylamine), MDA (methylendioxyamphetamine; tenamfetamine, alpha-methyl-3,4-methylendioxy-phenethylamine), MDMA (methylenedioxymethamphetamine; N,alpha-dimethyl-3,4-methylendioxy-phenethylamine) und MBDB (N-methylbenzodioxazolylbutanamine) in small blood samples and bloodstains using solid phase SPE columns and a pipetting robot (Gilson Aspec XL). The detection limits are in the order of 1.62 – 4.10 ng / 50 µl spot (amphetamines), 0.15 – 0.82 ng / 50 µl spot (cannabinoids), 1.67 – 4.70 ng / 50 µl spot (cocaine and derivatives) and 4.53 – 4.91 ng / 50 µl spot (opiates) and the correlation factors are between 0.9957 and 0.9999. The method has proven useful in forensic cases with only small sample volumes or bloodstains. Furthermore the detectability was tested using different trace-carriers (wood, textiles, metal, floor-tiles und glass). These investigations resulted in qualitative detectabilities within at least 64 days. The quantitative determination however raised difficulties, mainly caused by different brands of columns and other effects which are of important influence when working in the analytical range near the detection- and lower determination limit, respectively. By means of the methods developed within the scope of this study, two spectacular crime cases could be cleared up

Isotopic evidence for quasi-equilibrium chemistry in thermally mature natural gases

Natural gas is a key energy resource, and understanding how it forms is important for predicting where it forms in economically important volumes. However, the origin of dry thermogenic natural gas is one of the most controversial topics in petroleum geochemistry, with several differing hypotheses proposed, including kinetic processes (such as thermal cleavage, phase partitioning during migration, and demethylation of aromatic rings) and equilibrium processes (such as transition metal catalysis). The dominant paradigm is that it is a product of kinetically controlled cracking of long-chain hydrocarbons. Here we show that C₂₊ n-alkane gases (ethane, propane, butane, and pentane) are initially produced by irreversible cracking chemistry, but, as thermal maturity increases, the isotopic distribution of these species approaches thermodynamic equilibrium, either at the conditions of gas formation or during reservoir storage, becoming indistinguishable from equilibrium in the most thermally mature gases. We also find that the pair of CO₂ and C₁ (methane) exhibit a separate pattern of mutual isotopic equilibrium (generally at reservoir conditions), suggesting that they form a second, quasi-equilibrated population, separate from the C₂ to C₅ compounds. This conclusion implies that new approaches should be taken to predicting the compositions of natural gases as functions of time, temperature, and source substrate. Additionally, an isotopically equilibrated state can serve as a reference frame for recognizing many secondary processes that may modify natural gases after their formation, such as biodegradation

Modulation of the virus-receptor interaction by mutations in the V5 loop of feline immunodeficiency virus (FIV) following in vivo escape from neutralising antibody

&lt;b&gt;BACKGROUND:&lt;/b&gt; In the acute phase of infection with feline immunodeficiency virus (FIV), the virus targets activated CD4+ T cells by utilising CD134 (OX40) as a primary attachment receptor and CXCR4 as a co-receptor. The nature of the virus-receptor interaction varies between isolates; strains such as GL8 and CPGammer recognise a "complex" determinant on CD134 formed by cysteine-rich domains (CRDs) 1 and 2 of the molecule while strains such as PPR and B2542 require a more "simple" determinant comprising CRD1 only for infection. These differences in receptor recognition manifest as variations in sensitivity to receptor antagonists. In this study, we ask whether the nature of the virus-receptor interaction evolves in vivo.&lt;p&gt;&lt;/p&gt; &lt;b&gt;RESULTS:&lt;/b&gt; Following infection with a homogeneous viral population derived from a pathogenic molecular clone, a quasispecies emerged comprising variants with distinct sensitivities to neutralising antibody and displaying evidence of conversion from a "complex" to a "simple" interaction with CD134. Escape from neutralising antibody was mediated primarily by length and sequence polymorphisms in the V5 region of Env, and these alterations in V5 modulated the virus-receptor interaction as indicated by altered sensitivities to antagonism by both anti-CD134 antibody and soluble CD134.&lt;p&gt;&lt;/p&gt; &lt;b&gt;CONCLUSIONS:&lt;/b&gt; The FIV-receptor interaction evolves under the selective pressure of the host humoral immune response, and the V5 loop contributes to the virus-receptor interaction. Our data are consistent with a model whereby viruses with distinct biological properties are present in early versus late infection and with a shift from a "complex" to a "simple" interaction with CD134 with time post-infection.&lt;p&gt;&lt;/p&gt

Open Problems in Extracellular RNA Data Analysis: Insights From an ERCC Online Workshop.

We now know RNA can survive the harsh environment of biofluids when encapsulated in vesicles or by associating with lipoproteins or RNA binding proteins. These extracellular RNA (exRNA) play a role in intercellular signaling, serve as biomarkers of disease, and form the basis of new strategies for disease treatment. The Extracellular RNA Communication Consortium (ERCC) hosted a two-day online workshop (April 19-20, 2021) on the unique challenges of exRNA data analysis. The goal was to foster an open dialog about best practices and discuss open problems in the field, focusing initially on small exRNA sequencing data. Video recordings of workshop presentations and discussions are available (https://exRNA.org/exRNAdata2021-videos/). There were three target audiences: experimentalists who generate exRNA sequencing data, computational and data scientists who work with those groups to analyze their data, and experimental and data scientists new to the field. Here we summarize issues explored during the workshop, including progress on an effort to develop an exRNA data analysis challenge to engage the community in solving some of these open problems

Innovations, challenges, and minimal information for standardization of humanized mice.

Mice xenotransplanted with human cells and/or expressing human gene products (also known as "humanized mice") recapitulate the human evolutionary specialization and diversity of genotypic and phenotypic traits. These models can provide a relevant in vivo context for understanding of human-specific physiology and pathologies. Humanized mice have advanced toward mainstream preclinical models and are now at the forefront of biomedical research. Here, we considered innovations and challenges regarding the reconstitution of human immunity and human tissues, modeling of human infections and cancer, and the use of humanized mice for testing drugs or regenerative therapy products. As the number of publications exploring different facets of humanized mouse models has steadily increased in past years, it is becoming evident that standardized reporting is needed in the field. Therefore, an international community-driven resource called "Minimal Information for Standardization of Humanized Mice" (MISHUM) has been created for the purpose of enhancing rigor and reproducibility of studies in the field. Within MISHUM, we propose comprehensive guidelines for reporting critical information generated using humanized mice