cssi/SciSciGPT-SciSciNet huggingface dataset:
Spatial resource heterogeneity creates local hotspots of evolutionary potential

Do local conditions influence evolution's ability to produce new traits? Biological data demonstrate that evolutionary processes can be profoundly influenced by local conditions. However, the evolution of novel traits has not been addressed in this context, owing in part to the challenges of performing the necessary experiments with natural organisms. We conduct in silico experiments with the Avida Digital Evolution Platform to address this question. We created eight different spatially heterogeneous environments and ran 100 replicates in each. Within each environment, we examined the distribution of locations where nine different focal traits first evolved. Using spatial statistics methods, we identified regions within each environment that had significantly elevated probabilities of containing the first organism with a given trait (i.e. hotspots of evolutionary potential). Having demonstrated the presence of many such hotspots, we explored three potential mechanisms that could drive the formation of these patterns: proximity of specific resources, variation in local diversity, and variation in the sequence of locations the members of an evolutionary lineage occupy. Resource proximity and local diversity appear to have minimal explanatory power. Lineage paths through space, however, show some promising preliminary trends. If we can understand the processes that create evolutionary hotspots, we will be able to craft environments that are more effective at evolving targeted traits. This capability would be useful both to evolutionary computation, and to efforts to guide biological evolution.
Thinking Broad and Deep: Why Some Directors Exert an Outsized Influence on Strategic Change

This study addresses the oft-debated questions of whether, when, and how corporate board members help shape firm strategy by advancing a new perspective on heterogeneous director influence that int...
Monte Carlo methods for x-ray dispersive spectrometers

We discuss multivariate Monte Carlo methods appropriate for X-ray dispersive spectrometers. Dispersive spectrometers have many advantages for high resolution spectroscopy in the X-ray band. Analysis of data from these instruments is complicated by the fact that the instrument response functions are multi-dimensional and relatively few X-ray photons are detected from astrophysical sources. Monte Carlo methods are the natural solution to these challenges, but techniques for their use are not well developed. We describe a number of methods to produce a highly efficient and flexible multivariate Monte Carlo. These techniques include multi-dimensional response interpolation and multi-dimensional event comparison. We discuss how these methods have been extensively used in the XMM-Newton Reflection Grating Spectrometer in-flight calibration program. We also show several examples of a Monte Carlo applied to observations of clusters of galaxies and elliptical galaxies with the XMM-Newton observatory.
Shared and Distinct Genetic Risk Factors for Childhood-Onset and Adult-Onset Asthma: Genome-Wide and Transcriptome-Wide Studies

Summary Background Childhood-onset and adult-onset asthma differ with respect to severity and comorbidities. Whether they also differ with respect to genetic risk factors has not been previously investigated in large samples. The goals of this study were to identify shared and distinct genetic risk loci for childhood-onset and adult-onset asthma, and to identify the genes that might mediate the effects of associated variation. Methods We did genome-wide and transcriptome-wide studies, using data from the UK Biobank, in individuals with asthma, including adults with childhood-onset asthma (onset before 12 years of age), adults with adult-onset asthma (onset between 26 and 65 years of age), and adults without asthma (controls; aged older than 38 years). We did genome-wide association studies (GWAS) for childhood-onset asthma and adult-onset asthma each compared with shared controls, and for age of asthma onset in all asthma cases, with a genome-wide significance threshold of p Findings Of 376 358 British white individuals from the UK Biobank, we included 37 846 with self-reports of doctor-diagnosed asthma: 9433 adults with childhood-onset asthma; 21 564 adults with adult-onset asthma; and an additional 6849 young adults with asthma with onset between 12 and 25 years of age. For the first and second GWAS analyses, 318 237 individuals older than 38 years without asthma were used as controls. We detected 61 independent asthma loci: 23 were childhood-onset specific, one was adult-onset specific, and 37 were shared. 19 loci were associated with age of asthma onset. The most significant asthma-associated locus was at 17q12 (odds ratio 1·406, 95% CI 1·365–1·448; p=1·45 × 10−111) in the childhood-onset GWAS. Genes at the childhood onset-specific loci were most highly expressed in skin, blood, and small intestine; genes at the adult onset-specific loci were most highly expressed in lung, blood, small intestine, and spleen. PrediXcan identified 113 unique candidate genes at 22 of the 61 GWAS loci. Single-nucleotide polymorphism-based heritability estimates were more than three times larger for childhood-onset asthma (0·327) than for adult-onset disease (0·098). The onset of disease in childhood was associated with additional genes with relatively large effect sizes, with the largest odds ratio observed at the FLG locus at 1q21.3 (1·970, 95% CI 1·823–2·129). Interpretation Genetic risk factors for adult-onset asthma are largely a subset of the genetic risk for childhood-onset asthma but with overall smaller effects, suggesting a greater role for non-genetic risk factors in adult-onset asthma. Combined with gene expression and tissue enrichment patterns, we suggest that the establishment of disease in children is driven more by dysregulated allergy and epithelial barrier function genes, whereas the cause of adult-onset asthma is more lung-centred and environmentally determined, but with immune-mediated mechanisms driving disease progression in both children and adults. Funding US National Institutes of Health.
Crack formation and self-closing in shrinkable, granular packings.

Many clays, soils, biological tissues, foods, and coatings are shrinkable, granular materials: they are composed of packed, hydrated grains that shrink when dried. In many cases, these packings crack during drying, critically hindering applications. However, while cracking has been widely studied for bulk gels and packings of non-shrinkable grains, little is known about how packings of shrinkable grains crack. Here, we elucidate how grain shrinkage alters cracking during drying. Using experiments with model shrinkable hydrogel beads, we show that differential shrinkage can dramatically alter crack evolution during drying—in some cases, even causing cracks to spontaneously “self-close”. In other cases, packings shrink without cracking or crack irreversibly. We developed both granular and continuum models to quantify the interplay between grain shrinkage, poromechanics, packing size, drying rate, capillarity, and substrate friction on cracking. Guided by the theory, we also found that cracking can be completely altered by varying the spatial profile of drying. Our work elucidates the rich physics underlying cracking in shrinkable, granular packings, and yields new strategies for controlling crack evolution.
Patient-reported outcomes for dental health, shoulder-neck dysfunction, and overall quality of life after treatment with radiation for head and neck cancer.

e23064Background: The current exploratory cross-sectional study was designed to better characterize survivorship issues among patients treated with radiation for head and neck cancer with regard to...
The missing link: synthesis, crystal structure, and thermogravimetric studies of InPO4*H2O

A new binary indium phosphate monohydrate, InPO4·H2O, was synthesized under hydrothermal conditions. Its crystal structure was determined using single-crystal X-ray diffraction methods. InPO4·H2O crystallizes in the triclinic system, space group P1, with a = 5.4342(6) A, b = 5.5508(4) A, c = 6.5446(5) A, α = 97.593(6)°, β = 94.558(6)°, γ = 107.565(6)°, and Z = 2. The 3-D framework is built from (In2O8(OH2)2) dimers connected through (PO4) tetrahedra. Water molecules directly bond to indium. Thermogravimetric studies indicate that InPO4·H2O loses one water molecule in the temperature range between 370 and 480 °C to yield the previously reported anhydrous InPO4. The loss of water corresponds to condensation of the (In2O8(OH2)2) dimers into linear chains of edge-sharing (InO6) octahedra. InPO4·H2O represents the missing link between InPO4 and InPO4·2H2O. The structural relationships between InPO4·2H2O, InPO4·H2O, InPO4, and other MIII(PO4)·2H2O are discussed.
The Spatial Distribution of O-B5 Stars in the Solar Neighborhood as Measured by Hipparcos

We have developed a method to calculate the fundamental parameters of the vertical structure of the Galaxy in the solar neighborhood from trigonometric parallaxes alone. The method takes into account Lutz-Kelker–type biases in a self-consistent way and has been applied to a sample of O–B5 stars obtained from the Hipparcos catalog. We find that the Sun is located 24.2 ± 1.7 (random) ± 0.4 (systematic) pc above the Galactic plane and that the disk O–B5 stellar population is distributed with a scale height of 34.2 ± 0.8 (random) ± 2.5 (systematic) pc and an integrated surface density of [1.62 ± 0.04 (random) ± 0.14 (systematic)] × 10-3 stars pc-2. A halo component is also detected in the distribution and constitutes at least ≈5% of the total O–B5 population. The O–B5 stellar population within ~100 pc of the Sun has an anomalous spatial distribution, with a less than average number density. This local disturbance is probably associated with the expansion of the Gould Belt.
Enthalpies of Formation of Compounds in the P2O5−CaO−H2O System

The enthalpies of formation were determined for Ca4(PO4)2O, α-Ca3(PO4)2, and the hydroxyapatite compositions Ca10(PO4)6(OH)2 and Ca9(HPO4)(PO4)5OH by the analysis of isothermal calorimetric results obtained at 37.4 °C. Both hydroxyapatite compositions were formed by reaction of Ca4(PO4)2O with CaHPO4 or with CaHPO4· 2H2O in water depending on the molar proportions of the reactant used. Ca9(HPO4)(PO4)5OH was also formed by direct hydrolysis of α-Ca3(PO4)2 in water. Enthalpy of formation values were calculated by a Hess's Law analysis using several sets of equations. In summary, the enthalpy of formation values are: for Ca4(PO4)2O, −4762.4 kJ/mol, for α-Ca3(PO4)2, −4096.5 kJ/mol, for Ca9(HPO4)(PO4)5OH, −12719.7 kJ/mol, and for Ca10(PO4)6(OH)2, −13744.0 kJ/mol at 37.4 °C.
Structural Correlations of Organooxotin Compounds

A review of the basic structural features of organooxotin cluster chemistry is followed by a presentation of more recent work that illustrates interrelationships apparent on examining other chemistries that exhibit similar structural types. For examples, ladders, partial cubes, cubes, and double cubes are now more extensively known that incorporate a mixture of elements other than tin. Some compositions of organotin clusters that combine different elements are the ladder form, [Fe6(μ3-S)4(μ2-SR)4] core, the cube forms, [n-BuSn(O)O2AsMe2]4, [Mo3(SnCl3)Se4(NCS)9]6−, the butterfly compounds, [n-BuSn(OH)-(O2AsMe2)OP(O)Me2]2 and [n-BuSn(OH)(O2AsMe2)2]2 and the double cubes, [{n-BuSn(S)O2P(p-ClC6H4)2}3O]2Sn, [{(H2O)9Mo3S4} Sn]8+, and [Mo6AsS8(H2O)18]8+. Also of interest are double cubanes with sulfur or oxygen bridges, e.g., [(Fe4S4Cl3)2S]4− and adamantyl derivatives, e.g., (t-Bu)4Ge4S6 and [Fe4(SPh)10]2−. By taking advantage of the insight gained from such comparisons, synthetic procedures may reveal themselve...
Reinvestigation of Np2Se5: a clear divergence from Th2S5 and Th2Se5 in chalcogen-chalcogen and metal-chalcogen interactions.

Single crystals of Np2Se5 have been prepared through the reactions of Np and Se at 1223 K in an Sb2Se3 flux. The structure of Np2Se5, which has been characterized by single-crystal X-ray diffraction methods, crystallizes in the tetragonal space group P42/nmc. The crystallographic unit cell includes one unique Np and two Se positions. Se(1) atoms form one-dimensional infinite chains along the a and b axes with alternating intermediate Se-Se distances of 2.6489 (8) and 2.7999 (8) A, whereas Se(2) is a discrete Se(2-) anion. Each Np is coordinated to 10 Se atoms and every NpSe10 polyhedron shares faces, edges, or vertices with 14 other identical metal polyhedra to form a complex three-dimensional structure. Np LIII-edge X-ray Absorption Near Edge Structure (XANES) measurements show a clear shift in edge position to higher energies for Np2Se5 compared to Np3Se5 (Np(3+)2Np(4+)Se(2-)5). Magnetic susceptibility measurements indicate that Np2Se5 undergoes a ferromagnetic-type ordering below 18(1) K. Above the transition temperature, Np2Se5 behaves as a paramagnet with an effective moment of 1.98(5) μB/Np, given by a best fit of susceptibilities to a modified Curie-Weiss law over the temperature range 50-320 K.
Benzothiazines in synthesis. Formal synthesis of erogorgiaene

A benzothiazine, readily available in enantiomerically pure form via a completely selective, intramolecular addition of a sulfoximine-stabilized carbanion to an α,β-unsaturated ester, could be converted to a precursor to erogorgiaene in good overall yield.
How to Enrich the Message Space of a Cipher.

Given (deterministic) ciphersE andE that can encipher messages ofl andn bits, respectively, we construct a cipherE = XLS[E;E] that can encipher messages of l +s bits for any s < n. Enciphering such a string will take one call to E and two calls to E. We prove that E is a strong pseudorandom permutation as long as E and E are. Our construction works even in the tweakable and VIL (variable-input-length) settings. It makes use of a multipermutation (a pair of orthogonal Latin squares), a combinatorial object not previously used to get a provablesecurity result.
Solution Synthesis of Germanium Nanocrystals Demonstrating Quantum Confinement

HRTEM image of a single Ge nanocrystal. The image has been rotationally filtered to improve clarity. The lattice fringes imaged are for Ge 〈111〉, with a d spacing of 3.27 A. Reaction between the Zintl salt NaGe and GeCl4 is shown to produce Ge nanocrystals. The reaction proceeds readily in refluxing diglyme at ambient pressure. The nanocrystals produced may be surface-terminated by reaction with RLi or RMgBr and demonstrate quantum confinement.
CONFORMATIONAL PROPERTIES OF EPOTHILONE

The epothilones are macrolide natural products, produced by myxobacterium Sorangium cellulosum (So ce 90), which mimic the biological activity of the anticancer agent Taxol. These interesting compounds have been shown to bind tubulin, induce microtubule polymerization, and stabilize microtubule dynamics. Coupled with its biological activity, epothilone's relatively simple structure has made it an exciting target for total synthesis and analogue preparation. To date, only limited information has been reported with regard to epothilone's conformation in solution. We have used a combination of NMR studies and computational modeling to investigate the conformational properties of this exciting new lead in cancer chemotherapy. One- and two-dimensional 1H NMR experiments as well as computational methods suggest that the epothilone A prefers to exist in two conformations in both CD2Cl2 and DMSO/D2O. Knowledge of the solution conformation of epothilone in both organic and biological media may allow for the determ...
Analysis of heterogeneous computing approaches to simulating heat transfer in heterogeneous material

Abstract The simulation of heat flow through heterogeneous material is important for the design of structural and electronic components. Classical analytical solutions to the heat equation PDE are not known for many such domains, even those having simple geometries. The finite element method can provide approximations to a weak form continuum solution, with increasing accuracy as the number of degrees of freedom in the model increases. This comes at a cost of increased memory usage and computation time; even when taking advantage of sparse matrix techniques for the finite element system matrix. We summarize recent approaches in solving problems in structural mechanics and steady state heat conduction which do not require the explicit assembly of any system matrices, and adapt them to a method for solving the time-depended flow of heat. These approaches are highly parallelizable, and can be performed on graphical processing units (GPUs). Furthermore, they lend themselves to the simulation of heterogeneous material, with a minimum of added complexity. We present the mathematical framework of assembly-free FEM approaches, through which we summarize the benefits of GPU computation. We discuss our implementation using the OpenCL computing framework, and show how it is further adapted for use on multiple GPUs. We compare the performance of single and dual GPUs implementations of our method with previous GPU computing strategies from the literature and a CPU sparse matrix approach. The utility of the novel method is demonstrated through the solution of a real-world coefficient inverse problem that requires thousands of transient heat flow simulations, each of which involves solving a 1 million degree of freedom linear system over hundreds of time steps.
MONTE CARLO INVESTIGATIONS OF SOLVENT EFFECTS ON THE DECARBOXYLATION REACTION OF NEUTRAL N-CARBOXY-2-IMIDAZOLIDINONE IN AQUEOUS SOLUTION

The solvent effects on the decarboxylation reaction of neutral N-carboxy-2-imidazolidinone in aqueous solution have been investigated by a combined quantum mechanical and molecular mechanical (QM/MM) Monte Carlo simulation method. In the present approach, the gas-phase intrinsic reaction coordinate of the reaction was first obtained by ab initio molecular orbital calculations at the RHF/6-31+G(d) level. Then, the potential of mean force for the decarboxylation reaction was determined via statistical perturbation theory using the combined QM/MM-AM1/TIP3P potential in Monte Carlo simulations. A two-stage mechanism consisting of the intramolecular proton transfer and N−C bond cleavage with the N−C bond breaking as the rate-limiting step was found. The computed free energy of activation in water is 21.0 ± 0.2 kcal/mol, in good agreement with the experimental value of 20.7 kcal/mol. Analyses of the structural and energetic nature of the differential solvation along the reaction coordinate are presented.
BinSanity: unsupervised clustering of environmental microbial assemblies using coverage and affinity propagation

Metagenomics has become an integral part of defining microbial diversity in various environments. Many ecosystems have characteristically low biomass and few cultured representatives. Linking potential metabolisms to phylogeny in environmental microorganisms is important for interpreting microbial community functions and the impacts these communities have on geochemical cycles. However, with metagenomic studies there is the computational hurdle of 'binning' contigs into phylogenetically related units or putative genomes. Binning methods have been implemented with varying approaches such as k-means clustering, Gaussian mixture models, hierarchical clustering, neural networks, and two-way clustering; however, many of these suffer from biases against low coverage/abundance organisms and closely related taxa/strains. We are introducing a new binning method, BinSanity, that utilizes the clustering algorithm affinity propagation (AP), to cluster assemblies using coverage with compositional based refinement (tetranucleotide frequency and percent GC content) to optimize bins containing multiple source organisms. This separation of composition and coverage based clustering reduces bias for closely related taxa. BinSanity was developed and tested on artificial metagenomes varying in size and complexity. Results indicate that BinSanity has a higher precision, recall, and Adjusted Rand Index compared to five commonly implemented methods. When tested on a previously published environmental metagenome, BinSanity generated high completion and low redundancy bins corresponding with the published metagenome-assembled genomes.
An ab initio study of substituent effects in [1,3]-hydrogen shifts.

Reports in the literature place the TS for the [1,3]-H shift in propene comparable to or higher in energy than loss of the allylic H. However, [1,3]-H shifts have been repeatedly observed experimen...
Baculovirus AC102 is a nucleocapsid protein that is crucial for nuclear actin polymerization and nucleocapsid morphogenesis

The baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV), the type species of alphabaculoviruses, is an enveloped DNA virus that infects lepidopteran insects and is commonly known as a vector for protein expression and cell transduction. AcMNPV belongs to a diverse group of viral and bacterial pathogens that target the host cell actin cytoskeleton during infection. AcMNPV is unusual, however, in that it absolutely requires actin translocation into the nucleus early in infection and actin polymerization within the nucleus late in infection coincident with viral replication. Of the six viral factors that are sufficient, when coexpressed, to induce the nuclear localization of actin, only AC102 is essential for viral replication and the nuclear accumulation of actin. We therefore sought to better understand the role of AC102 in actin mobilization in the nucleus early and late in infection. Although AC102 was proposed to function early in infection, we found that AC102 is predominantly expressed as a late protein. In addition, we observed that AC102 is required for F-actin assembly in the nucleus during late infection, as well as for proper formation of viral replication structures and nucleocapsid morphogenesis. Finally, we found that AC102 is a nucleocapsid protein and a newly recognized member of a complex consisting of the viral proteins EC27, C42, and the actin polymerization protein P78/83. Taken together, our findings suggest that AC102 is necessary for nucleocapsid morphogenesis and actin assembly during late infection through its role as a component of the P78/83-C42-EC27-AC102 protein complex.IMPORTANCE The baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is an important biotechnological tool for protein expression and cell transduction, and related nucleopolyhedroviruses are also used as environmentally benign insecticides. One impact of our work is to better understand the fundamental mechanisms through which AcMNPV exploits the cellular machinery of the host for replication, which may aid in the development of improved baculovirus-based research and industrial tools. Moreover, AcMNPV's ability to mobilize the host actin cytoskeleton within the cell's nucleus during infection makes it a powerful cell biological tool. It is becoming increasingly clear that actin plays important roles in the cell's nucleus, and yet the regulation and function of nuclear actin is poorly understood. Our work to better understand how AcMNPV relocalizes and polymerizes actin within the nucleus may reveal fundamental mechanisms that govern nuclear actin regulation and function, even in the absence of viral infection.
Dihydroporphyrin Synthesis: New Methodology.

Selective formation of trans-nitrochlorins 16−19, cyclopropylchlorins 14, 15, and 20−23, or functionalized trans-chlorins 5−13 by reaction of 2-nitro-5,10,15,20-tetraphenylporphyrin 1 with “active” methylene compounds such as malonates or malononitrile in the presence of base has been achieved. Reaction control is accomplished via sequential Michael additions, followed by intramolecular nucleophilic displacement of a secondary nitro group. Steric as well as thermodynamic effects have been found to govern the selectivity of product formation. Ambient temperature or bulky carbanion substituents lead to nitrochlorins and/or cyclopropylchlorins. Increased reaction temperatures, combined with sterically less encumbered carbanion substituents, favor the formation of disubstituted trans-chlorins. Nucleophilic ring-opening reactions of cyclopropyl-derivative 14 afford disubstituted trans-chlorin products 5 and 25 and provide additional mechanistic evidence for the intermediacy of the cyclopropylchlorin. Use of po...
Ammonia Triborane: A New Synthesis, Structural Determinations, and Hydrolytic Hydrogen-Release Properties

Iodine oxidation of B3H8− in glyme solution to produce (glyme)B3H7, followed by displacement of the coordinated glyme by reaction with anhydrous ammonia provides a safe and convenient preparation of ammonia triborane, NH3B3H7 (1). X-ray crystallographic determinations and DFT computational studies of both NH3B3H7 and the NH3B3H7·18-crown-6 adduct demonstrate that while computations predict a symmetric single bridging-hydrogen conformation, NH3B3H7 has a highly asymmetric structure in the solid-state that results from intermolecular N−H+···H−−B dihydrogen bonding interactions. Studies of its hydrolytic reactions have shown that upon the addition of acid or an appropriate transition metal catalyst, aqueous solutions of 1 rapidly release hydrogen, with 6.1 materials wt % H2-release being achieved from a 22.7 wt % aqueous solution of 1 at room temperature in the presence of 5 wt % Rh/Al2O3 (1.1 mol% Rh). The rate of H2-release was controlled by both the catalyst loadings and temperature.
Stratification of drying particle suspensions: Comparison of implicit and explicit solvent simulations

Large scale molecular dynamics simulations are used to study drying suspensions of a binary mixture of large and small particles in explicit and implicit solvents. The solvent is first modeled explicitly and then mapped to a uniform viscous medium by matching the diffusion coefficients and the pair correlation functions of the particles. "Small-on-top" stratification of the particles, with an enrichment of the smaller ones at the receding liquid-vapor interface during drying, is observed in both models under the same drying conditions. With the implicit solvent model, we are able to model much thicker films and study the effect of the initial film thickness on the final distribution of particles in the dry film. Our results show that the degree of stratification is controlled by the Peclet number defined using the initial film thickness as the characteristic length scale. When the Peclet numbers of large and small particles are much larger than 1, the degree of "small-on-top" stratification is first enhanced and then weakens as the Peclet numbers are increased.
Synthesis and Cytotoxicity of 1,2-Disubstituted Naphth[2,3-d]imidazole-4,9-diones and Related Compounds

As part of our continuing search for potential anticancer drug candidates that are selective against slowly growing solid tumors, we have synthesized several series of 1- and 2-substituted derivatives of the lead structure, 1-ethyl-2-methylnaphth[2,3-d]imidazole-4,9-dione (5). Their cytotoxic activity in the National Cancer Institute's in vitro cancer cell line panel is reported. In general, substitution of various alkyl, phenyl, or benzyl moieties did not improve activity, and compound 5 remains the most active naphth[2,3-d]imidazole-4,9-dione derivative. However, high levels of activity and selectivity were found with several related 2-(acylamino)-3-chloro-1,4-naphthoquinones (2f-j). Compound 2i, 2-[(2-fluorophenyl)acetamido]-3-chloro-1,4-naphthoquinone, has been selected for further in vivo testing and as an additional lead compound for further structural modification.
Sr10[Mo2N6][MoN4]2 and β‐Sr3MoN4

Two new phases in the strontium-molybdenum-nitrogen phase diagram have been synthesized. Single crystals of Sr10[Mo2N6][MoN4]2 were grown from a mixed sodium-gallium melt at 900 °C in a sealed niobium tube. It crystallizes in the triclinic space group (Z = 1) with a = 6.421(1), b = 9.190(2), c = 9.263(2) A and α = 64.939(5), β = 82.961(6) and γ = 89.692(6)°. The new, orthorhombic polymorph of Sr3MoN4 was synthesized as a polycrystalline powder from an intimate mixture of Sr2N and molybdenum metal in the presence of N2. Rietveld analysis shows it to crystallize in Pbca (Z = 8) with a = 10.4835(2), b = 9.7374(2) and c = 11.5114(2) A. Studies suggest that excess nitrogen is essential to the formation of this polymorph. Sr10[Mo2N6][MoN4]2 is the first molybdenum nitride to contain the anionic unit [Mo2N6]8-, which appears as isolated, edge-sharing pairs of MoN4 that facilitate MoV-MoV bonding. This compound also contains isolated [MoN4]6- tetrahedra and the presence of these two units results in the first mixed valent molybdenum nitride. Resistivity measurements show it to be insulating. Sr10[Mo2N6][MoN4]2 and β-Sr3MoN4 Zwei neue Phasen sind im Strontium-Molybdan-Stickstoff-Phasendiagramm synthetisiert worden. Einkristalle von Sr10[Mo2N6][MoN4]2 wurden aus einer Natrium-Gallium-Schmelze bei 900 °C in einer Niobampulle erhalten. Die Verbindung kristallisiert in der triklinen Raumgruppe (Z = 1) mit a = 6.421(1), b = 9.190(2), c = 9.263(2) A and α = 64.939(5), β = 82.961(6) and γ = 89.692(6)°. Das neue, orthorhombische Polymorph von Sr3MoN4 wurde als polykristallines Pulver aus einer innigen Mischung von Sr2N und Molybdanmetall unter N2 erhalten. Die Rietveld-Analyse zeigt, dasss die Substanz in der Raumgruppe Pbca kristallisiert (Z = 8) mit a = 10.4835(2), b = 9.7374(2) and c = 11.5114(2) A. Die Untersuchungen zeigen, dass ein Uberschuss an Stickstoff fur die Bildung dieses Polymorphen notwendig ist. Sr10[Mo2N6][MoN4]2 ist das erste Molybdannitrid mit dem Anion [Mo2N6]8-, das als isoliertes, kantenverknupftes Paar von MoN4 die MoV-MoV-Bindung ermoglicht. Diese Verbindung enthalt auch isolierte [MoN4]6--Tetraeder und das Vorliegen dieser zwei Einheiten ergibt das erste gemischtvalente Molybdannitrid. Widerstandsmessungen zeigen, dass es sich um einen Isolator handelt.
Co(III) porphyrin/DMAP: an efficient catalyst system for the synthesis of cyclic carbonates from CO2 and epoxides

Abstract CoTPP(Cl)/DMAP was found to be a highly active catalyst system for the chemical fixation of CO 2 via reaction with epoxides. The corresponding cyclic carbonate products are produced in high yield and selectivity for a variety of terminal mono and disubstituted epoxides. 1,2-Disubstituted internal epoxides were also investigated as substrates and found to react with very high stereospecificity.
Norm inflation for generalized Navier-Stokes equations

We consider the incompressible magneto-hydrodynamic system with fractional powers of the Laplacian in the three-dimensional case. We discover a wide range of spaces where the norm inflation occurs and hence small initial data results are out of reach. The norm inflation occurs not only in scaling invariant (critical) spaces, but also in supercritical and, surprisingly, subcritical ones.
Behavioral analysis of substrate texture preference in a leech, Helobdella austinensis.

Leeches in the wild are often found on smooth surfaces, such as vegetation, smooth rocks or human artifacts such as bottles and cans, thus exhibiting what appears to be a “substrate texture preference”. Here, we have reproduced this behavior under controlled circumstances, by allowing leeches to step about freely on a range of silicon carbide substrates (sandpaper). To begin to understand the neural mechanisms underlying this texture preference behavior, we have determined relevant parameters of leech behavior both on uniform substrates of varying textures, and in a behavior choice paradigm in which the leech is confronted with a choice between rougher and smoother substrate textures at each step. We tested two non-exclusive mechanisms which could produce substrate texture preference: (1) a Differential Diffusion mechanism, in which a leech is more likely to stop moving on a smooth surface than on a rough one, and (2) a Smoothness Selection mechanism, in which a leech is more likely to attach its front sucker (prerequisite for taking a step) to a smooth surface than to a rough one. We propose that both mechanisms contribute to the texture preference exhibited by leeches.
An enantioselective strategy to macrocyclic bisindolylmaleimides. An efficient formal synthesis of LY 333531.

The ability to employ a bromo alcohol as a nucleophile in a palladium-catalyzed dynamic kinetic asymmetric transformation leads to an efficient synthesis of a selective PKC inhibitor under clinical development.
CHIRAL CROTYLSILANE-BASED APPROACH TO BENZOQUINOID ANSAMYCINS : TOTAL SYNTHESIS OF (+)-MACBECIN I

A highly convergent total synthesis of the antitumor antibiotic (+)-macbecin I (1) has been achieved through the homologation of the aldehyde 3 (C5−C21 aromatic fragment) to the E,Z-dienoate 2 by employing a sequential olefination strategy. Subsequent macrolactonization and a final two-step oxidation sequence were the principle steps used to complete the synthesis. Six of the seven syn-stereochemical relationships (C6−C7, C10−C11, and C14−C15) were introduced using our asymmetric crotylation bond construction methodology. The C12 stereocenter was introduced by an alkoxy-directed hydroboration reaction. An alternative strategy for introducing the C10 stereo center via a diastereoselective hydroboration reaction of 1,1-disubstituted olefin 6b provided a more atom efficient approach to intermediate 7.
Nanostructured magnetic cuprate cluster: synthesis, structure, UV-Vis spectroscopy, and magnetic properties of a new copper(II) arsenate NaCuAsO4 containing discrete [Cu4O16]24- clusters.

Crystals of copper(II) arsenate NaCuAsO4 were grown by conventional high-temperature, solid-state methods in molten-salt media. The compounds were characterized by single crystal X-ray diffraction,...
Analysis of a novel bioreactor designed for ultrasound stimulation of cell-seeded scaffolds

Although daily low intensity pulsed ultrasound (LIPUS) treatment has been shown to induce cellular responses supporting bone repair, in vitro studies in 3D models, such as cell-seeded scaffolds, are needed to further investigate the underlying cellular mechanisms. This requires well-controlled conditions in an US bioreactor. Computational studies are needed to investigate various effects on US wave propagation influenced by bioreactor configurations, such as reflections at interfaces and wave interference, and optimize the bioreactor design for experimental repeatability. In this study, an enclosed cylindrical sample holder that contained an inner well for placement of a scaffold immersed in culture medium was fabricated by stereolithography 3D printing and combined with an acoustic absorbent material to eliminate the presence of an air-liquid interface perpendicular to the wave propagation path. Finite element simulations conducted in the frequency domain demonstrated that weak standing waves were present within the culture medium, indicating the effects of reflections at solid-liquid interfaces within the sample holder, as expected. Focusing on the acoustic pressure at the inner well surface, it was found that the spatially-averaged pressure varied from a maximum to a minimum value as the thickness of the water layer beneath the sample holder was changed. Average pressure values at antinode positions were 2- fold higher than at node positions. A volume-averaged pressure was calculated within the culture medium corresponding to the region where a scaffold would be centrally located within the bioreactor. It was shown that the thickness of the volume analyzed had a minimal effect on the calculated average pressure. Time-dependent simulations for one complete pulse (i.e. 1 ms) showed that the acoustic pressure in volumes that would be occupied by scaffolds of two different thicknesses (diameter of 8.5 mm and thicknesses of 0.2 or 2.0 mm) reached a stable value after 45 μs, and then remained at that value until the active period of the pulse ceased. Once the active period ended, the acoustic pressure rapidly decreased to a low baseline pressure. Overall, this study showed that the proposed novel bioreactor design provided a controlled environment for the US treatment of a cell-seeded scaffold by removing the air-liquid interface using a custom-designed sample holder and an acoustic absorbent material.
IMPROVED ENANTIOSELECTIVE DIHYDROXYLATION OF BISHOMOALLYLIC ALCOHOL DERIVATIVES USING A MECHANISTICALLY INSPIRED BIS-CINCHONA ALKALOID CATALYST

Abstract The catalytic dihydroxylation of p-methoxybenzoate esters of various bishomoallylic alcohols proceeds with excellent enantioselectivity and, in the case of diolefins, with imporved regioselectivity using a designed catalyst that incorporates an N-anthracenylmethyl group to enhance catalyst-substrate binding interactions.
Variation in Context‐dependent Foraging Behavior Across Pollinators

Pollinator foraging behavior has direct consequences for plant reproduction and has been implicated in driving floral trait evolution. Exploring the degree to which pollinators exhibit flexibility in foraging behavior will add to a mechanistic understanding of how pollinators can impose selection on plant traits. Although plants have evolved suites of floral traits to attract pollinators, flower color is a particularly important aspect of the floral display. Some pollinators show strong innate color preference, but many pollinators display flexibility in preference due to learning associations between rewards and color, or due to variable perception of color in different environments or plant communities. This study examines the flexibility in flower color preference of two groups of native butterfly pollinators under natural field conditions. We find that pipevine swallowtails (Battus philenor) and skippers (family Hesperiidae), the predominate pollinators of the two native Texas Phlox species, Phlox cuspidata and Phlox drummondii, display distinct patterns of color preferences across different contexts. Pipevine swallowtails exhibit highly flexible color preferences and likely utilize other floral traits to make foraging decisions. In contrast, skippers have consistent color preferences and likely use flower color as a primary cue for foraging. As a result of this variation in color preference flexibility, the two pollinator groups impose concordant selection on flower color in some contexts but discordant selection in other contexts. This variability could have profound implications for how flower traits respond to pollinator-mediated selection. Our findings suggest that studying dynamics of behavior in natural field conditions is important for understanding plant-pollinator interactions.
A new synthesis of N‐phenyl lactams

The synthesis of N-phenyl lactams by phase transfer oxidation of N,N-(polymethylene) anilines with potassium permanganate is reported.
Catalytic enantioselective synthesis of azacycloalkenes via intermolecular rhodium carbenoid C–H insertion/ring-closing metathesis sequence

Abstract Enantiomerically enriched cyclopropanes and products of C–H insertion reactions were obtained in excellent combined yields and enantioselectivities as a consequence of rhodium-catalyzed decomposition of vinyl diazoacetate in the presence of tert -butoxycarbonyl-(Boc)-protected amines as trapping agents. A series of enantiomerically enriched six- to eight-membered nitrogen-containing heterocycles were subsequently prepared via ring-closing metathesis of the dienes catalyzed by ruthenium benzylidene complex.
Synthesis of Pyrrolo-isoquinolines Related to the Lamellarins Using Silver-Catalyzed Cycloisomerization/Dipolar Cycloaddition

Synthesis of pyrrolo-isoquinolines related to the lamellarin alkaloids employing silver-catalyzed cycloisomerization−dipolar cycloaddition of alkynyl N-benzylidene glycinates is described. Mechanistic studies revealed Ag(I)-catalyzed cycloisomerization to an azomethine ylide as a key step for formation of angular pyrrolo-isoquinolines.
Addition of α-Lithiated Nitriles to Azaheterocycles

The addition of α-deprotonated nitriles to azahetero­cycles followed by rearomatization is described. A simple two-step, one-pot procedure for the sequence is also presented.
Chiral P,N-Ligands Based on Ketopinic Acid in the Asymmetric Heck Reaction

Novel chiral P,N-ligands were synthesized from (1S)-(+)-ketopinic acid using palladium-catalyzed coupling reaction of a vinyl triflate and either a diarylphosphine or a dialkylphosphine as the key step. Palladium complexes of these ligands are efficient catalysts for asymmetric Heck reaction between aryl or alkenyl triflates and cyclic alkenes. Products were obtained with good to excellent enantioselectivity from arylation and alkenylation of 1,2-dihydrofuran, cyclopentene, and 4,7-dihydro-1,3-dioxepin.
Trifluoromethyl-substituted Δ3-imidazolines: Synthesis and reactivity

Abstract We describe the preparation of various 4-trifluoromethyl-substituted Δ3-imidazolines, which are precursors to amino acid-derived trifluoromethyl ketones. The imidazolines are prepared from α-silylimines and trifluoroacetonitrile by a 3+2 cycloaddition, and they can be hydrolyzed in weak acid to trifluoromethyl ketones. Additionally, we have identified several ring-opened compounds which result from treatment of the imidazolines with acid or base. Attempts to alkylate the imidazolines led to ring-opened products, so that the alkylation sequence ultimately produced N-alkylated amino acid-derived trifluoromethyl ketones.
An analysis of the influences dictating regioselectivity in platinum-catalyzed hydrosilylations of internal alkynes

Abstract A full account of our studies on internal alkyne hydrosilylations using platinum catalysis is described. We demonstrate that these transformations are highly governed by the electronic characteristics of the alkyne substituents, wherein the hydride will add preferentially to the more electron-deficient alkyne carbon. The steric and coordinative capabilities of the substituents influence the selectivity to a much lesser extent, with propargylic alcohols a lone exception. The choice of silane is relevant in some cases; specific silanes will afford high regioselectivities while others are much less selective. Ultimately, the regioselectivity of addition can be quite predictable using 13C NMR chemical shift data, allowing this reactivity to be incorporated into purposeful reaction design.
Palladium-Catalyzed Carbene Insertion and Trapping with Carbon Nucleophiles

Palladium catalysts are shown to catalyze the three-component coupling of vinyl halides, trimethylsilyldiazomethane, and stabilized carbon nucleophiles. The reaction is believed to proceed through a palladium-carbene intermediate LX(R)Pd═CHSiMe3 that undergoes migration of the vinyl substituent to the electrophilic carbene center to generate an η3-allylpalladium intermediate. The allylpalladium intermediate is attacked by the carbon nucleophile to generate a vinylsilane product.
New and Efficient Catalytic Route to Bicyclo[3.3.0]octa-1,5-dien-3-ones

The silylcarbobicyclization of 4,4-disubstituted 1,6-heptadiynes with tert-butyldimethylsilane catalyzed by Rh(acac)(CO)2, Co2Rh2(CO)12, or (t-BuNC)4RhCo(CO)4 under 50 atm of carbon monoxide gives ...
Information exchange in cartels

Antitrust authorities view the exchange of information among firms regarding costs, prices, or sales as anticompetitive. Such exchanges allow competitors to closely monitor each other, thereby facilitating collusion. But the exchange of aggregate information, perhaps via a third party, is legal. The logic is that collusion is difficult if the identity of a price‐cutting firm cannot be ascertained. Here, we examine this logic using Stigler's model of secret price cuts. We first identify circumstances such that when no information exchange is possible, collusion is difficult. We then show that if firms' aggregate sales are made public, nearly perfect collusion is possible.
Nurturing Nature: How Brain Development Is Inherently Social and Emotional, and What This Means for Education

New advances in neurobiology are revealing that brain development and the learning it enables are directly dependent on social-emotional experience. Growing bodies of research reveal the importance...
Metric Flips with Calabi Ansatz

We study the limiting behavior of the Kahler–Ricci flow on \({{\mathbb{P}(\mathcal{O}_{\mathbb{P}^n} \oplus \mathcal{O}_{\mathbb{P}^n}(-1)^{\oplus(m+1)})}}\) for m, n ≥ 1, assuming the initial metric satisfies the Calabi symmetry. We show that the flow either shrinks to a point, collapses to \({{\mathbb{P}^n}}\) or contracts a subvariety of codimension m + 1 in the Gromov–Hausdorff sense. We also show that the Kahler–Ricci flow resolves a certain type of cone singularities in the Gromov–Hausdorff sense.
Trajectory Optimization of Robots With Regenerative Drive Systems: Numerical and Experimental Results

In this paper, we investigate energy-optimal control of robots with ultracapacitor-based regenerative drive systems. Based on a previously introduced framework, a fairly generic model is considered for the robot and the drive system. An optimal control problem is formulated to find point-to point trajectories maximizing the amount of energy regenerated and stored in the capacitor. The optimization problem, its numerical solution, and an experimental evaluation are demonstrated using a PUMA manipulator with custom regenerative drives. Power flows, stored regenerative energy, and efficiency are evaluated. Tracking of optimal trajectories is enforced on the robot using a standard robust passivity based control approach. Experimental results show that when following optimal trajectories, a reduction of about $\text{10}\text{--}\text{22}\%$ in energy consumption can be achieved for the conditions of the study, relative to the nonregenerative case.
Geodesics in the Heisenberg Group

We provide a new and elementary proof for the structure of geodesics in the Heisenberg group $\mathbb{H}^n$. The proof is based on a new isoperimetric inequality for closed curves in $\mathbb{R}^{2n}$. We also prove that the Carnot-Caratheodory metric is real analytic away from the center of the group.
On Sutured Khovanov Homology and Axis-Preserving Mutations

This paper establishes that sutured annular Khovanov homology is not invariant for braid closures under axis-preserving mutations. This follows from an explicit relationship between sutured annular...
Integrating semi-supervised label propagation and random forests for multi-atlas based hippocampus segmentation

A novel multi-atlas based image segmentation method is proposed by integrating a semi-supervised label propagation method and a supervised random forests method in a pattern recognition based label fusion framework. The semi-supervised label propagation method takes into consideration local and global image appearance of images to be segmented and segments the images by propagating reliable segmentation results obtained by the supervised random forests method. Particularly, the random forests method is used to train a regression model based on image patches of atlas images for each voxel of the images to be segmented. The regression model is used to obtain reliable segmentation results to guide the label propagation for the segmentation. The proposed method has been compared with state-of-the-art multi-atlas based image segmentation methods for segmenting the hippocampus in MR images. The experiment results have demonstrated that our method obtained superior segmentation performance.
New Upper Bound for Sums of Dilates

For $\lambda \in \mathbb{Z}$, let $\lambda \cdot A = \{ \lambda a : a \in A\}$. Suppose $r, h\in \mathbb{Z}$ are sufficiently large and comparable to each other. We prove that if $|A+A| \le K |A|$ and $\lambda_1, \ldots, \lambda_h \le 2^r$, then \[ |\lambda_1 \cdot A + \ldots + \lambda_h \cdot A | \le K^{ 7 rh /\ln (r+h) } |A|. \] This improves upon a result of Bukh who shows that \[ |\lambda_1 \cdot A + \ldots + \lambda_h \cdot A | \le K^{O(rh)} |A|. \] Our main technique is to combine Bukh's idea of considering the binary expansion of $\lambda_i$ with a result on biclique decompositions of bipartite graphs.