cssi/SciSciGPT-SciSciNet huggingface dataset:
When Can Exemplars Shape White Racial Attitudes? Evidence from the 2012 U.S. Presidential Campaign

Prior research finds that exposure to outgroup exemplars reduces prejudice, but it has focused on most-likely cases. We examine whether salient outgroup exemplars can reduce prejudice under more challenging conditions, such as when they are counter-stereotypical but not well-liked and the audience is heterogeneous and holds strong priors. Specifically, we assess the impact of the Obama exemplar under the less auspicious conditions of the 2012 U.S. presidential campaign. Using panel data, we find that racial prejudice declined during the campaign, especially among whites with the most exposure to Obama through political television. Liking Obama proved irrelevant to these effects, as did partisanship. Racial prejudice increased slightly after the campaign ended, but the effects remained largely intact weeks later.
The glutathione cycle shapes synaptic glutamate activity

Glutamate is the most abundant excitatory neurotransmitter, present at the bulk of cortical synapses, and participating in many physiologic and pathologic processes ranging from learning and memory to stroke. The tripeptide, glutathione, is one-third glutamate and present at up to low millimolar intracellular concentrations in brain, mediating antioxidant defenses and drug detoxification. Because of the substantial amounts of brain glutathione and its rapid turnover under homeostatic control, we hypothesized that glutathione is a relevant reservoir of glutamate and could influence synaptic excitability. We find that drugs that inhibit generation of glutamate by the glutathione cycle elicit decreases in cytosolic glutamate and decreased miniature excitatory postsynaptic potential (mEPSC) frequency. In contrast, pharmacologically decreasing the biosynthesis of glutathione leads to increases in cytosolic glutamate and enhanced mEPSC frequency. The glutathione cycle can compensate for decreased excitatory neurotransmission when the glutamate-glutamine shuttle is inhibited. Glutathione may be a physiologic reservoir of glutamate neurotransmitter.
Genome reorganization of the GmSHMT gene family in soybean showed a lack of functional redundancy in resistance to soybean cyst nematode

In soybeans, eighteen members constitute the serine hydroxymethyltransferase (GmSHMT) gene family, of which the cytosolic-targeted GmSHMT08c member has been reported to mediate resistance to soybean cyst nematode (SCN). This work presents a comprehensive study of the SHMT gene family members, including synteny, phylogeny, subcellular localizations, haplotypes, protein homology modeling, mutational, and expression analyses. Phylogenetic analysis showed that SHMT genes are divided into four classes reflecting their subcellular distribution (cytosol, nucleus, mitochondrion, and chloroplast). Subcellular localization of selected GmSHMT members supports their in-silico predictions and phylogenetic distribution. Expression and functional analyses showed that GmSHMT genes display many overlapping, but some divergent responses during SCN infection. Furthermore, mutational analysis reveals that all isolated EMS mutants that lose their resistance to SCN carry missense and nonsense mutations at the GmSHMT08c, but none of the Gmshmt08c mutants carried mutations in the other GmSHMT genes. Haplotype clustering analysis using the whole genome resequencing data from a collection of 106 diverse soybean germplams (15X) was performed to identify allelic variants and haplotypes within the GmSHMT gene family. Interestingly, only the cytosolic-localized GmSHMT08c presented SNP clusters that were associated with SCN resistance, supporting our mutational analysis. Although eight GmSHMT members respond to the nematode infestation, functional and mutational analysis has shown the absence of functional redundancy in resistance to SCN. Structural analysis and protein homology modeling showed the presence of spontaneous mutations at important residues within the GmSHMT proteins, suggesting the presence of altered enzyme activities based on substrate affinities. Due to the accumulation of mutations during the evolution of the soybean genome, the other GmSHMT members have undergone neofunctionalization and subfunctionalization events.
The Happiness-Energy Paradox: Energy Use is Unrelated to Subjective Well-Being

Earth’s per capita energy use continues to grow, despite technological advances and widespread calls for reduction in energy consumption. The negative environmental consequences are well known: resource depletion, pollution, and global warming. However many remain reluctant to cut energy consumption because of the widespread, although, implicit, belief that a nation’s well being depends on its energy consumption. This article systematically examines the evidential support for the relationship between energy use and subjective well-being at the societal level, by integrating data from multiple sources, collected at multiple levels of government, and spanning four decades. This analysis reveals, surprisingly, that the most common measure of subjective well-being, life satisfaction, is unrelated to energy use -- whether measured at the national, state or county level. The nil relationship between happiness and energy use is reminiscent of the well-known Easterlin Paradox, however the causal mechanisms responsible to each remain in question. We discuss the possible causes for the Happiness-Energy paradox and potential policy implications.
Photonic topological phase transition on demand

On-demand, switchable phase transitions between topologically non-trivial and trivial photonic states are demonstrated. Specifically, it is shown that integration of a 2D array of coupled ring resonators within a thermal heater array enables unparalleled control over topological protection of photonic modes. Importantly, auxiliary control over spatial phase modulation opens up a way to guide topologically protected edge modes along generated virtual boundaries. The proposed approach can lead to practical realizations of topological phase transitions in many photonic applications, including topologically protected photonic memory/logic devices, robust optical modulators, and switches.
Simulation of H Behavior in p-GaN(Mg) at Elevated Temperatures

The behavior of H in p-GaN(Mg) at temperatures >400°C is modeled by using energies and vibration frequencies from density-functional theory to parameterize transport and reaction equations. Predictions agree semiquantitatively with experiment for the solubility, uptake, and release of the H when account is taken of a surface barrier.
Monotone Properties of k-Uniform Hypergraphs Are Weakly Evasive

A Boolean function in n variables is weakly evasive if its decision-tree complexity is Ω(n). By k-graphs, we mean k-uniform hypergraphs. A k-graph property on v vertices is a Boolean function on n = vk variables corresponding to the k-subsets of a v-set that is invariant under the ve permutations of the v-set (isomorphisms of k-graphs).In 1976, Rivest and Vuillemin proved that all nonconstant monotone graph properties (k = 2) are weakly evasive, confirming a conjecture of Aanderaa and Rosenberg in 1973. Then, in 2013, Kulkarni, Qiao, and Sun (KQS) proved the analogous result for 3-graphs. We extend these results to k-graphs for every fixed k. From this, we show that monotone Boolean functions invariant under the action of a large primitive group are weakly evasive.Although KQS employ the powerful topological approach of Kahn et al. in 1984 combined with heavy number theory, our argument is elementary and self-contained (modulo some basic group theory). Inspired by the outline of the KQS approach, we formalize the general framework of “orbit augmentation sequences” of sets with group actions. We show that a parameter of such sequences, called the spacing, is a lower bound on the decision-tree complexity for any nontrivial monotone property that is Γ-invariant for all groups Γ involved in the orbit augmentation sequence, assuming all those groups are p-groups. We develop operations on such sequences such as composition and direct product that will provide helpful machinery for our applications. We apply this general technique to k-graphs via certain liftings of k-graphs with wreath product action of p-groups.
Petaflop Seismic Simulations in the Public Cloud

During the last decade cloud services and infrastructure as a service became a popular solution for diverse applications. Additionally, hardware support for virtualization closed performance gaps, compared to on-premises, bare-metal systems. This development is driven by offloaded hypervisors and full CPU virtualization. Today’s cloud service providers, such as Amazon or Google, offer the ability to assemble application-tailored clusters to maximize performance. However, from an interconnect point of view, one has to tackle a 4–5\(\times \) slow-down in terms of bandwidth and 25\(\times \) in terms of latency, compared to latest high-speed and low-latency interconnects. Taking into account the high per-node and accelerator-driven performance of latest supercomputers, we observe that the network-bandwidth performance of recent cloud offerings is within 2\(\times \) of large supercomputers. In order to address these challenges, we present a comprehensive application-centric approach for high-order seismic simulations utilizing the ADER discontinuous Galerkin finite element method, which exhibits excellent communication characteristics. This covers the tuning of the operating system, normally not possible on supercomputers, micro-benchmarking, and finally, the efficient execution of our solver in the public cloud. Due to this performance-oriented end-to-end workflow, we were able to achieve 1.09 PFLOPS on 768 AWS c5.18xlarge instances, offering 27,648 cores with 5 PFLOPS of theoretical computational power. This correlates to an achieved peak efficiency of over 20% and a close-to 90% parallel efficiency in a weak scaling setup. In terms of strong scalability, we were able to strong-scale a science scenario from 2 to 64 instances with 60% parallel efficiency. This work is, to the best of our knowledge, the first of its kind at such a large scale.
Enantioselective Synthesis of Fused Cycloheptadienes by a Tandem Intramolecular Cyclopropanation/Cope Rearrangement Sequence

The asymmetric induction in the intramolecular cyclopropanations of allyl vinyldiazoacetates catalyzed by tetrakis[N-[4-dodecylphenyl)sulfonyl]-(S)-prolinato]dirhodium [Rh2(S-DOSP)4] is very dependent on the allyl substitution pattern. The reactions of cis-alkenes result in much higher asymmetric induction than trans-alkenes while the highest enantioselectivity was obtained with a disubstituted terminal alkene. The intramolecular cyclopropanation of dienylmethyl vinyldiazoacetates results in the synthesis of fused cycloheptadiene ring systems with full control of relative stereochemistry and variable enantioselectivity. The synthetic utility of this process was demonstrated by a short synthesis of 5-epi-tremulenolide in 93% ee.
Stable Monopyrrole Atropisomers

Malonic ester derivatives of ethyl and methyl 3,5-dimethyl-4-(1′-iodoneopentyl)-1H-pyrrole-2-carboxylate exhibit restricted rotation about the pyrrole C(4)–C(1′) bond due to the bulky 1′-tert-butyl and malonic ester groups and the ortho effect at C(4) of the sterically crowded 3,5-dimethylpyrrole. The malonates belong to a rare class of atropisomers with restricted rotation about an sp3–sp2 C–C bond, and they undergo diastereomeric separation by TLC and crystallization: the diastereomers are stable in solution at room temperature. A crystal of one of the diastereomers, suitable for X-ray crystallography, gave the relative configuration of the chiral axis and stereogenic center at C(1′). Dynamic NMR studies of the purified diastereomers provide kinetic and thermodynamic parameters associated with the atropisomerism: ΔG ‡ = 132–134 kJ/mol (∼32 kcal/mol) at 383 K in C2D2Cl4 solvent.
Surfactant-Like Porphyrins in Homogeneous Solution and Organized Media: Studies of Metalation and Diprotonation

A diverse range of reactivities is reported for Cu(II) incorporation into meso-tetrakis (Iƒ-alkylamidopheny)porphyrins in organized media (SDS micelles and AOT reversed micelles) as side-chain length and atropisomer structure are varied. Much more comparable reactivities are noted in homogeneous solution. The reactivity patterns in the organized assemblies are consistent with two separate, equilibrating interfacial orientations for the 4,0 atropisomer whose relative proportions vary with side chain length. The proposed orientations result in an inverted reactivity order for the short chain compounds in organized media (i.e. 4,0 3,1 > cis 2,2 > trans 2,2). A strong correlation between porphyrin core protonation constants and metalation anionic reactivities at the interfaces confirms the orientational hypothesis while catalytic metalation and elevated porphyrin basicities strongly support interfacial solubilization.
Intramolecular Michael reactions of aliphatic aldehyde enolates generated by imidazolium carbenes

Abstract Due to the high reactivity of the formyl group under either basic or acidic reaction conditions required for the direct generation of aldehyde enolates, intramolecular Michael additions of aldehyde enolates to α,β-unsaturated carbonyl compounds have been underexplored for the stereoselective synthesis of carbocyclic compounds. The intramolecular Michael reaction of aldehyde enolates generated by imidazolium carbenes was explored for the synthesis of cyclopentane aldehydes. The imidazolium carbenes were used as Bronsted bases to directly generate the aldehydes enolates.
The Development of the New Processes for Manufacturing the Key Intermediates of β-Lactam Antibiotics

It is well-known that (3R, 4R) -4-acetoxy-3- [(R) -1'- ((t-butyldimethylsilyl) oxy) ethyl] -2-azetidinone (4-AA) and (3S, 4S) - [(R) -1'- (t-butyldimethylsilyl) oxyethyl] -4- (R) -1-carboxyethyl-2-azetidinone (1β-methylcarboxylic acid) are very important intermediates for the synthesis of carbapenems and 1β-methyl carbapenems.We have developed the industrial processes for the syntheses of these intermediates. The synthesis of 4-AA was accomplished by the use of the ruthenium-BINAP complex catalyzed asymmetric hydrogenation of methyl 2-benzamidomethyl-3-oxobutanoate followed by the cyclization to β-lactam and the ruthenium catalyzed acetoxylation of β-lactam as the key technologies. In addition, for the synthesis of 1β-methylcarboxylic acid, we have developed three processes which involve a palladium catalyzed deallyloxycarbonylation, a rhodium catalyzed asymmetric hydroformylation and a magnesium enolate addition reaction as the key reaction, respectively.
Growth of Group III Nitrides. A Review of Precursors and Techniques

The AlGaInN quaternary alloy system is uniquely suited for numerous device applications because the bandgap can be varied from 1.9 to 6.2 eV by changing the alloy composition. Growth of epitaxial device-quality group III (Al, Ga, In) nitride films has been hindered by a lack of suitably lattice matched substrates, the large equilibrium dissociation pressure of N2 from the nitrides at typical growth temperatures, and predeposition reactions in the commonly employed metal−organic chemical vapor (MOCVD) precursors. The most successful films have been grown at temperatures in excess of 900 °C by MOCVD. However, high growth temperatures may limit compatibility and incorporation of group III nitrides with existing fabrication technologies and devices. Attempts to lower deposition temperature include activated nitrogen sources and alternative precursors. This review will discuss improvement in film properties as a function of growth chemistry and will focus on MOCVD precursors used specifically for the growth of...
FiberNET: An Ensemble Deep Learning Framework for Clustering White Matter Fibers

White matter tracts are commonly analyzed in studies of micro-structural integrity and anatomical connectivity in the brain. Over the last decade, it has been an open problem as to how best to cluster white matter fibers, extracted from whole-brain tractography, into anatomically meaningful groups. Some existing techniques use region of interest (ROI) based clustering, atlas-based labeling, or unsupervised spectral clustering. ROI-based clustering is popular for analyzing anatomical connectivity among a set of ROIs, but it does not always partition the brain into recognizable fiber bundles. Here we propose an approach using convolutional neural networks (CNNs) to learn shape features of the fiber bundles, which are then exploited to cluster white matter fibers. To achieve such clustering, we first need to re-parameterize the fibers in an intrinsic space. The clustering is performed in induced parameterized coordinates. To our knowledge, this is one of the first approaches for fiber clustering using deep learning techniques. The results show strong accuracy - on a par with or better than other state-of-the-art methods.
Accurate nucleon-nucleon potential based upon chiral perturbation theory.

Abstract We present an accurate nucleon–nucleon (NN) potential based upon chiral effective Lagrangians. The model includes one- and two-pion exchange contributions up to chiral order three. We show that a quantitative fit of the NN D-wave phase shifts requires contact terms (which represent the short range force) of order four. Within this framework, the NN phase shifts below 300 MeV lab. energy and the properties of the deuteron are reproduced with high-precision. This chiral NN potential represents a reliable starting point for testing the chiral effective field theory approach in exact few-nucleon and microscopic nuclear many-body calculations. An important implication of the present work is that the chiral 2π exchange at order four is of crucial interest for future chiral NN potential development.
LRH-1 mitigates intestinal inflammatory disease by maintaining epithelial homeostasis and cell survival

Epithelial dysfunction and crypt destruction are defining features of inflammatory bowel disease (IBD). However, current IBD therapies targeting epithelial dysfunction are lacking. The nuclear receptor LRH-1 (NR5A2) is expressed in intestinal epithelium and thought to contribute to epithelial renewal. Here we show that LRH-1 maintains intestinal epithelial health and protects against inflammatory damage. Knocking out LRH-1 in murine intestinal organoids reduces Notch signaling, increases crypt cell death, distorts the cellular composition of the epithelium, and weakens the epithelial barrier. Human LRH-1 (hLRH-1) rescues epithelial integrity and when overexpressed, mitigates inflammatory damage in murine and human intestinal organoids, including those derived from IBD patients. Finally, hLRH-1 greatly reduces disease severity in T-cell-mediated murine colitis. Together with the failure of a ligand-incompetent hLRH-1 mutant to protect against TNFα-damage, these findings provide compelling evidence that hLRH-1 mediates epithelial homeostasis and is an attractive target for intestinal disease.
Nutrient stoichiometry shapes microbial coevolution.

Coevolution is a force contributing to the generation and maintenance of biodiversity. It is influenced by environmental conditions including the scarcity of essential resources, which can drive the evolution of defence and virulence traits. We conducted a long-term chemostat experiment where the marine cyanobacterium Synechococcus was challenged with a lytic phage under nitrogen (N) or phosphorus (P) limitation. This manipulation of nutrient stoichiometry altered the stability of host-parasite interactions and the underlying mode of coevolution. By assessing the infectivity with > 18 000 pairwise challenges, we documented directional selection for increased phage resistance, consistent with arms-race dynamics while phage infectivity fluctuated through time, as expected when coevolution is driven by negative frequency-dependent selection. The resulting infection networks were 50% less modular under N- versus P-limitation reflecting host-range contraction and asymmetric coevolutionary trajectories. Nutrient stoichiometry affects eco-evolutionary feedbacks in ways that may alter the dynamics and functioning of environmental and host-associated microbial communities.
Scanning tunneling microscopy of ordered arrays of heteropolyacids deposited on a graphite surface

Keggin-type heteropolyacids (water-soluble H3PMo12O40, H4PMo11VO40, and H8PMo10VCuO40 and water-insoluble K3PMo12O40 and H3-xCsxPMo12O40, x = 1, 2, 2.5, 3) deposited on highly oriented pyrolytic graphite (HOPG) surfaces were successfully imaged by scanning tunneling microscopy (STM). All of these heteropoly acids (HPAs) formed clear two-dimensional ordered arrays on graphite, and their periodicities were in good agreement with values determined by X-ray crystallography. Spatially resolved tunneling spectroscopy was used to demonstrate that the arrays imaged represented HPA monolayers, as the characteristic tunneling spectrum of graphite was obtained at high-symmetry interstitial sites in these arrays. The periodicity of the ordered arrays of the water-soluble Keggin-type HPAs was ca. 10−11 A. However, ordered arrays of the water-insoluble K3PMo12O40 and H3-xCsxPMo12O40 showed periodicities of ca. 12−14 A, values somewhat larger than that of the pure acid form. The array spacing increased monotonically wit...
Complexation of 4f and 5f Cations with Polyoxometalates

Polyoxometalates (POMs) have distinct macromolecular structures, large sizes (6 to 25 A), high symmetry, large molecular weight (1,000 to 10,000 g/mol), high anionic charges (-3 to - 40) and good aqueous solubility and stability. Metal cations are bound to POMs via surface edge or bridging oxygens in plenary structures or by encapsulation in the defect site for lacunary structures. The binding of Ca2+, Eu3+, UO22+ and Th4+ was studied by solvent extraction, calorimetry and fluorescence with MnMo9O326-, TeMo6O246-, SiW12O404-, P2W18O626-, and P2W17O6110-. Eu3+ was studied as an analog of trivalent actinides as it allows use of macroscale techniques and fluorescence spectroscopy. The sequence of the log β101 values, Ca2+ < UO22+ < Eu3+ < Th4+, reflects ionic interaction and, for UO22+, steric hindrance. For the 1:1 complexes, the residual hydration of Eu3+ is decreased by 5 H2O molecules in the lacunary defect and by 4 in the plenary structure. The binding of all cations is stronger for the lacunary structu...
INTRAMOLECULAR SULFOXIDE ELECTROPHILIC SULFENYLATION IN 1- AND 3-ACYLINDOLES

Heating 1-(2-ethylsulfinyl)benzoylindole (1) in refluxing p-xylene [thermal Sulfoxide Electrophilic Sulfenylation (SES)] produces indolo[2,1-b][1,3]benzothiazin-12-one (2) in 66% yield. Similar treatment of 1-methyl-3-(2-ethylsulfinyl)benzoylindole (8) provides three products: sulfide 7 and cyclized products 9 and 10 in 10, 19 and 15% yield, respectively. Conversion of 10 to 9 under the reaction conditions is demonstrated and a spirocyclic intermediate 12, which may form from both 9 and 10 but undergoes only preferential S-migration, is postulated to account for the rearrangement.
Central and peripheral innervation patterns of defined axial motor units in larval zebrafish

Spinal motor neurons and the peripheral muscle fibers they innervate form discrete motor units that execute movements of varying force and speed. Subsets of spinal motor neurons also exhibit axon collaterals that influence motor output centrally. Here, we have used in vivo imaging to anatomically characterize the central and peripheral innervation patterns of axial motor units in larval zebrafish. Using early born "primary" motor neurons and their division of epaxial and hypaxial muscle into four distinct quadrants as a reference, we define three distinct types of later born "secondary" motor units. The largest is "m-type" units, which innervate deeper fast-twitch muscle fibers via medial nerves. Next in size are "ms-type" secondaries, which innervate superficial fast-twitch and slow fibers via medial and septal nerves, followed by "s-type" units, which exclusively innervate superficial slow muscle fibers via septal nerves. All types of secondaries innervate up to four axial quadrants. Central axon collaterals are found in subsets of primaries based on soma position and predominantly in secondary fast-twitch units (m, ms) with increasing likelihood based on number of quadrants innervated. Collaterals are labeled by synaptophysin-tagged fluorescent proteins, but not PSD95, consistent with their output function. Also, PSD95 dendrite labeling reveals that larger motor units receive more excitatory synaptic input. Collaterals are largely restricted to the neuropil, however, perisomatic connections are observed between motor units. These observations suggest that recurrent interactions are dominated by motor neurons recruited during stronger movements and set the stage for functional investigations of recurrent motor circuitry in larval zebrafish.
Synthesis of two 1,3‐2,4‐calix[4]bis‐crown ethers containing two 1,2‐phenylene and one pyridine or anisole units in each crown ether moiety

Syntheses of 1,3–2,4-calix[4]bis-crown ethers (1 and 2) fixed in the 1,3-alternate conformation by 1,3- and 2,4-bridges made of two modified polyether chains each containing two 1,2-phenylene residues and one pyridine or anisyl unit are reported. The structures of compounds 1 and 2 were established by 1H nmr, 13C nmr, hrms and elemental analyses.
Novel syntheses of camptothecin alkaloids, part 2. concise synthesis of (S)-camptothecins

Abstract A 9-step, convergent total synthesis of ( S )-camptothecin alkaloids is described. The intramolecular [4+2] cycloaddition of an N-arylimidate with an alkyne is used to prepare the alkaloid ABC ring system. 1 The chiral center is derived utilizing Seebach's chemistry 2 for the diastereoselective Michael addition of a chiral dioxolanone enolate to a methylene malonate acceptor. The total synthesis of non-racemic topotecan is accomplished from (S)-10-hydroxycamptothecin in an additional step.
Photochemistry of tetramethyl-4-pyrone in alcohol solvents

Irradiation of tetramethyl-4-pyrone in alcohol solvents leads to the formation of tetramethyl-2-pyrone and to a variety of cyclopent-2-enone and cyclopent-3-enone solvent adducts. The structure and mode of product formation is consistent with photochemical generation of a short-lived 2,6-bridged oxabicyclohexenyl zwitterion which undergoes sigmatropic rearrangement to a longer-lived epoxycyclopentenone. Although the zwitterion is efficiently trapped by methanol solvent, in less nucleophilic alcohol solvents it rearranges to the epoxycyclopentenone which isomerizes to the 2-pyrone or reacts with the alcohol solvent to form the observed solvent adducts.
Solar neutrinos: Models, observations, and new opportunities

I discuss the development and resolution of the solar neutrino problem, as well as opportunities now open to us to extend our knowledge of main-sequence stellar evolution and neutrino astrophysics.
Microwave-accelerated crossed Cannizzaro reaction using barium hydroxide under solvent-free conditions

Abstract A solventless and expeditious method for the preparation of alcohols is described from aldehydes using barium hydroxide, Ba(OH)2.8H2O, and paraformaldehyde. A comparison of this microwave-accelerated Cannizzaro reaction to the one under conventional heating mode is also reported.
Total synthesis of a dibromotyrosine alkaloid inhibitor of mycothiol S-conjugate amidase

Two complementary synthetic sequences are described for the first total synthesis of a dibromotyrosine alkaloid (1) reported to inhibit a critical mycobacterial enzyme, mycothiol S-conjugate amidase. The O-benzyloxime of 4-hydroxyphenylpyruvic acid was dibrominated and successively linked to a 3-aminopropyl chain, then to a 4-aminobutylguanidine unit, followed by selective deprotections to yield alkaloid 1. In an improved variant, the O-tetrahydropyranyloxime 12 was condensed with 4-aminobutylguanidine then dibrominated to phenol 14, which upon Mitsunobu coupling to a 3-aminopropyl segment and deprotection produced the target 1.
An efficient method for solution-phase parallel synthesis of 2-quinoxalinol salen Schiff-base ligands.

A solution-phase parallel method for the synthesis of 2-quinoxalinol salen ligands was designed and optimized. The synthesis begins with commercially available 1,5-difluoro-2, 4-dinitrobenzene (DFDNB) and employs a sequence of five straightforward and high-yielding reaction steps. Simple laboratory techniques with low sensitivity to water or air for solution-phase parallel reactions were coupled with convenient workup and purification procedures to give high-purity and yield a small ligand library of 20 compounds. The final step, a Schiff-base condensation of an aldehyde with the diaminoquinoxaline results in a new category of ligands for metal coordination or of potential bioactivity, based on the skeleton 2,2‘-(1E,1‘E)-(quinoxaline-6,7-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)diphenol. The approach described here is easily adaptable for parallel synthesis of a larger library.
Cyclohexenone Construction by Intramolecular Alkylidene C−H Insertion: Synthesis of (+)-Cassiol

We report new procedures for stereoselective cyclopentene and cyclohexenone construction employing the alkylidene carbene C−H insertion reaction. Described are diastereoselective insertion into methylene and enantiospecific insertion into methine C−H bonds. The latter case leads directly to the enantioselective synthesis of (+)-cassiol (1).
Gene expression patterns in synchronized islet populations.

In vivo levels of insulin are oscillatory with a period of ~5–10 minutes, indicating that the islets of Langerhans within the pancreas are synchronized. While the synchronizing factors are still un...
Rapidly Processed Stool Swabs Approximate Stool Microbiota Profiles

ABSTRACT Studies of the intestinal microbiome commonly utilize stool samples to measure the microbial composition in the distal gut. However, collection of stool can be difficult from some subjects under certain experimental conditions. Sampling of fecal material using sterile swabs can streamline sample collection, handling, and processing. In this study, we validate the use of swabs of fecal matter to approximate measurements of microbiota in stool using 16S rRNA gene Illumina amplicon sequencing and evaluate the effects of shipping time at ambient temperatures on accuracy. The results indicate that swab samples reliably replicate the stool microbiota bacterial composition, alpha diversity, and beta diversity when swabs are processed quickly (≤2 days) but that sample quality quickly degrades after this period and is accompanied by increased abundances of Enterobacteriaceae. Fresh swabs appear to be a viable alternative to stool sampling when standard collection methods are challenging, but extended exposure to ambient temperatures prior to processing threatens sample integrity. IMPORTANCE Collection of fecal swab samples simplifies handling, processing, and archiving compared to collection of stool. This study confirms that fecal swabs reliably replicate the bacterial composition and diversity of stool samples, provided that the swabs are processed shortly after collection. These findings support the use of fecal swabs, when shipping and handling are done properly, to streamline measurements of intestinal microbiota.
Major QTL controls adaptation to serpentine soils in Mimulus guttatus

Spatially varying selection is a critical driver of adaptive differentiation. Yet, there are few examples where the fitness effects of naturally segregating variants that contribute to local adaptation have been measured in the field. Plant adaptation to harsh soil habitats provides an ideal study system for investigating the genetic basis of local adaptation. The work presented here identifies a major locus underlying adaptation to serpentine soils in Mimulus guttatus and estimates the strength of selection on this locus in native field sites. Reciprocal transplant and common-garden studies show that serpentine and nonserpentine populations of M. guttatus differ in their ability to survive on serpentine soils. We directly mapped these field survival differences by performing a bulk segregant analysis with F2 survivors from a field transplant study and identify a single QTL where individuals that are homozygous for the nonserpentine allele do not survive on serpentine soils. Genotyping the survivors from an independent mapping population reveals that this same QTL controls serpentine tolerance in a second, geographically distant population. Finally, we show that this QTL controls tolerance to soil properties, as opposed to some other aspect of the field sites that may differ, by performing a laboratory-based common-garden experiment in native serpentine soils that replicates the survival differences observed in the field. These results indicate that despite the myriad chemical and physical challenges plants face in serpentine habitats, adaptation to these soils in M. guttatus has a simple genetic basis.
Method for the rapid synthesis of highly functionalized 2-hydroxy-1-naphthoates. Syntheses of the naphthoic acid components of neocarzinostatin chromophore and N1999A2.

We describe a four-step sequence for the synthesis of complex 2-hydroxy-1-naphthoic acids involving Z-selective olefination of benzaldehyde derivatives with a novel dioxolenone-containing phenyl phosphonate reagent, followed by dioxolenone cleavage with alkaline trifluoroethanol and oxidative cyclization (Mn(OAc)3) of the resultant trifluoroethyl β-keto esters.
Synthesis of Transition-Metal Nitrides from Nanoscale Metal Particles Prepared by Homogeneous Reduction of Metal Halides with an Alkalide

Transition-metal nitrides have been synthesized by heating nanoscale metal particles under flowing N2(g) or NH3(g). In some cases reaction temperatures are significantly lower than those required by conventional heating procedures. Nanoscale metal particles of Mo, Nb, Ta, Fe−Mo, Fe−Nb, and Cu−Nb were prepared by reduction of the respective metal chloride or mixture of chlorides with the sodide, [K+(15-crown-5)2]Na-, in dimethyl ether solution. The previously characterized nitrides that were prepared (with synthesis conditions indicated) include γ-Mo2N (800 °C, N2) and Mo2N (720 °C, N2), Ta3N5 (650 °C, NH3), Fe3Mo3N (>650 °C, N2), and a mixture of niobium nitride phases (800 °C, N2). A previously unreported phase has been found in the Ba−Nb−N system.
Connecting Touch and Vision via Cross-Modal Prediction

Humans perceive the world using multi-modal sensory inputs such as vision, audition, and touch. In this work, we investigate the cross-modal connection between vision and touch. The main challenge in this cross-domain modeling task lies in the significant scale discrepancy between the two: while our eyes perceive an entire visual scene at once, humans can only feel a small region of an object at any given moment. To connect vision and touch, we introduce new tasks of synthesizing plausible tactile signals from visual inputs as well as imagining how we interact with objects given tactile data as input. To accomplish our goals, we first equip robots with both visual and tactile sensors and collect a large-scale dataset of corresponding vision and tactile image sequences. To close the scale gap, we present a new conditional adversarial model that incorporates the scale and location information of the touch. Human perceptual studies demonstrate that our model can produce realistic visual images from tactile data and vice versa. Finally, we present both qualitative and quantitative experimental results regarding different system designs, as well as visualizing the learned representations of our model.
Actinide Selective Systems for Environmental Extraction and Sensing Applications

The potential environmental and health concerns surrounding actinides and the use of nuclear fuels limits the acceptance of nuclear power by the public. This in turn, hinders the capability of this country to take advantage of nuclear power. Expanding our fundamental knowledge of actinide coordination chemistry will allow for the development of improved actinide sensors, new separations methods, or new means of radioactive waste remediation. We have designed and optimized a solution-phase parallel method for the synthesis of a library of symmetrical 2-quinoxalinol salens, Schiff-base type ligands with a 2-quinoxalinol incorporated into the salen backbone. This combines the rigid salen coordination framework with the quinoxaline properties that impart properties for use in colorimetric or fluorescent sensors. These have now been incorporated into organic soluble resins for metal extraction. (authors)
The Total Synthesis of Allosamidin. Expansions of the Methodology of Azaglycosylation Pursuant to the Total Synthesis of Allosamidin. A Surprising Enantiotopic Sense for a Lipase-Induced Deacetylation

Allosamidin, recently isolated from mycelial extracts of Streptomyces sp. 1713, is a powerful and selective chitinase inhibitor. The total synthesis of allosamidin is described herein. The electric eel acetylcholinesterase-mediated enantioselective hydrolysis of (trans,trans)-2-(benzyloxy)cyclopentene-1,3-diol diacetate accessed a monoacetyl derivative. Five additional steps produced a protected version of the aglycon (“allosamizoline”) sector of allosamidin. An allal derivative stereoselectively reacted with benzenesulfonamide in the presence of a halonium source to afford a 2β-halo-1α-sulfonamidohexose. Treatment of this product with a strong base generated an intermediate 1,2-sulfonylaziridine, which was trapped with a protected allal derivative to provide a disaccharide glycal. Reiteration of this scheme gave access to the required trisaccharide. Following deprotection, the total synthesis of allosamidin was accomplished. In addition, the method, with modification, gave access to several allosamidin a...
Claudin-4 reconstituted in unilamellar vesicles is sufficient to form tight interfaces that partition membrane proteins.

Tight junctions have been hypothesized to act as molecular fences in the plasma membrane of epithelial cells, helping to form differentiated apical and basolateral domains. While this fence function is believed to arise from the interaction of four-pass transmembrane claudins, the complexity of tight junctions has made direct evidence of their role as a putative diffusion barrier difficult to obtain. Here we address this challenge by reconstituting claudin-4 into giant unilamellar vesicles using microfluidic jetting. We find that reconstituted claudin-4 is sufficient to form adhesive membrane interfaces without accessory proteins present in vivo. By controlling the molecular composition of the inner and outer leaflets of jetted vesicle membranes, we show that claudin-4-mediated interfaces can drive partitioning of extracellular membrane proteins with ectodomains as small as 5 nm but not of inner or outer leaflet lipids. Our findings indicate that homotypic interactions of claudins and their small size can contribute to the polarization of epithelial cells.
Novel synthesis of 4,5-diarylphenanthrenes via C2-C6 cyclization of benzannulated enyne-allenes.

A new synthetic pathway to the 4,5-diarylphenanthrenes 8 having a helical twist in their structures was developed. The synthetic sequence involves condensation of the diketone 5 with 2 equiv of the lithium acetylides derived from the diacetylenes 4 followed by protonation to produce the propargylic alcohols 6. Reduction of 6 with triethylsilane in the presence of trifluoroacetic acid furnished the tetraacetylenic hydrocarbons 7 in nearly quantitative yields. Treatment of 7 with potassium tert-butoxide under refluxing toluene at 110 °C for up to 10 h then furnished the 4,5-diarylphenanthrenes 8. Apparently, the transformation from 7 to 8 involves initial prototropic isomerizations to form the benzannulated enyne−allenes 9. Two subsequent formal intramolecular Diels−Alder reactions via the biradicals 10 and 12 derived from the C2−C6 cyclizations then led to 13, which in turn underwent tautomerizations to give 8. The structure of 8a was established by the X-ray structure analysis, showing that the two phenyl...
Antibiotic-Induced Shifts in Fecal Microbiota Density and Composition during Hematopoietic Stem Cell Transplantation

Dramatic microbiota changes and loss of commensal anaerobic bacteria are associated with adverse outcomes in hematopoietic cell transplantation (HCT) recipients. In this study, we demonstrate these dynamic changes at high resolution through daily stool sampling and assess the impact of individual antibiotics on those changes. We collected 272 longitudinal stool samples (with mostly daily frequency) from 18 patients undergoing HCT and determined their composition by multiparallel 16S rRNA gene sequencing as well as the density of bacteria in stool by quantitative PCR (qPCR). We calculated microbiota volatility to quantify rapid shifts and developed a new dynamic systems inference method to assess the specific impact of antibiotics. The greatest shifts in microbiota composition occurred between stem cell infusion and reconstitution of healthy immune cells. Piperacillin-tazobactam caused the most severe declines among obligate anaerobes. Our approach of daily sampling, bacterial density determination, and dynamic systems modeling allowed us to infer the independent effects of specific antibiotics on the microbiota of HCT patients.
Orbital Angular Momentum (OAM) of Light in Fiber

Light carries spin (polarization) and orbital angular momentum (OAM). We review recent work on the stable propagation and nonlinear properties of such states in fibers, which have spawned applications ranging from telecommunications to biomedical imaging.
Bases of the quantum matrix bialgebra and induced sign characters of the Hecke algebra

We combinatorially describe entries of the transition matrices which relate monomial bases of the zero-weight space of the quantum matrix bialgebra. This description leads to a combinatorial rule for evaluating induced sign characters of the type A Hecke algebra $$H_n(q)$$ at all elements of the form $$(1 + T_{s_{i_1}}) \cdots (1 + T_{s_{i_m}})$$ , including the Kazhdan–Lusztig basis elements indexed by 321-hexagon-avoiding permutations. This result is the first subtraction-free rule for evaluating all elements of a basis of the $$H_n(q)$$ -trace space at all elements of a basis of $$H_n(q)$$ .
Classification of subdivision rules for geometric groups of low dimension

Subdivision rules create sequences of nested cell structures on CW-complexes, and they frequently arise from groups. In this paper, we develop several tools for classifying subdivision rules. We give a criterion for a subdivision rule to represent a Gromov hyperbolic space, and show that a subdivision rule for a hyperbolic group determines the Gromov boundary. We give a criterion for a subdivision rule to represent a Euclidean space of dimension less than 4. We also show that Nil and Sol geometries can not be modeled by subdivision rules. We use these tools and previous theorems to classify the geometry of subdivision rules for low-dimensional geometric groups by the combinatorial properties of their subdivision rules.
Estimating the state of AC power systems using semidefinite programming

An important monitoring task for power networks is to estimate accurately the underlying grid state, which is useful for security-constrained dispatch and power system control. For nonlinear AC power systems, the state estimation (SE) problem is inherently nonconvex giving rise to many local optima. As a result, existing estimators used extensively in practice rely on iterative optimization methods, which are destined to return only locally optimal solutions. A semidefinite programming (SDP) based approach is introduced in this paper, which relies on convex relaxation of the original SE problem and thereby renders it efficiently solvable. A sufficient condition also becomes available to guarantee that the dual SDP problem attains zero duality gap, and thus ensure that the globally optimal SE solution is achievable in polynomial time. The novel scheme's ability to markedly outperform existing iterative alternatives is corroborated through numerical tests on the standard IEEE 14-bus benchmark system.
Energy dissipation in the Smagorinsky model of turbulence

Abstract The Smagorinsky model often severely over-dissipates flows and, consistently, previous estimates of its energy dissipation rate blow up as R e → ∞ . This report estimates time averaged model dissipation, 〈 e S 〉 , under periodic boundary conditions as 〈 e S 〉 ≤ 2 U 3 L + Re − 1 U 3 L + 32 27 C S 2 ( δ L ) 2 U 3 L , where U , L are global velocity and length scales and C S ≃ 0.1 , δ 1 are model parameters. Thus, in the absence of boundary layers, the Smagorinsky model does not over dissipate.
Gauss–Christoffel quadrature for inverse regression: applications to computer experiments

Sufficient dimension reduction (SDR) provides a framework for reducing the predictor space dimension in statistical regression problems. We consider SDR in the context of dimension reduction for deterministic functions of several variables such as those arising in computer experiments. In this context, SDR can reveal low-dimensional ridge structure in functions. Two algorithms for SDR—sliced inverse regression (SIR) and sliced average variance estimation (SAVE)—approximate matrices of integrals using a sliced mapping of the response. We interpret this sliced approach as a Riemann sum approximation of the particular integrals arising in each algorithm. We employ the well-known tools from numerical analysis—namely, multivariate numerical integration and orthogonal polynomials—to produce new algorithms that improve upon the Riemann sum-based numerical integration in SIR and SAVE. We call the new algorithms Lanczos–Stieltjes inverse regression (LSIR) and Lanczos–Stieltjes average variance estimation (LSAVE) due to their connection with Stieltjes’ method—and Lanczos’ related discretization—for generating a sequence of polynomials that are orthogonal with respect to a given measure. We show that this approach approximates the desired integrals, and we study the behavior of LSIR and LSAVE with two numerical examples. The quadrature-based LSIR and LSAVE eliminate the first-order algebraic convergence rate bottleneck resulting from the Riemann sum approximation, thus enabling high-order numerical approximations of the integrals when appropriate. Moreover, LSIR and LSAVE perform as well as the best-case SIR and SAVE implementations (e.g., adaptive partitioning of the response space) when low-order numerical integration methods (e.g., simple Monte Carlo) are used.
Multispeed Klein–Gordon Systems in Dimension Three

We consider long time evolution of small solutions to general multispeed Klein-Gordon systems in 3+1 dimensions. We prove that such solutions are always global and scatter to a linear flow, thus extending previous partial results. The main new ingredients of our method is an improved linear dispersion estimate exploiting the asymptotic spherical symmetry of Klein-Gordon waves, and a corresponding bilinear oscillatory integral estimate.
A Brooks-type result for sparse critical graphs

A graph G is k-critical if it has chromatic number k, but every proper subgraph of G is (k-1)-colorable. Let f k (n) denote the minimum number of edges in an n-vertex k-critical graph. Recently the authors gave a lower bound, \({f_k}\left( n \right) \geqslant \left\lceil {\frac{{\left( {k + 1} \right)\left( {k - 2} \right)\left| {V\left( G \right)} \right| - k\left( {k - 3} \right)}}{{2\left( {k - 1} \right)}}} \right\rceil \), that solves a conjecture by Gallai from 1963 and is sharp for every n≡1 (mod k-1). It is also sharp for k=4 and every n≥6. In this paper we refine the result by describing all n-vertex k-critical graphs G with \(\left| {E\left( G \right)} \right| = \frac{{\left( {k + 1} \right)\left( {k - 2} \right)\left| {V\left( G \right)} \right| - k\left( {k - 3} \right)}}{{2\left( {k - 1} \right)}}\). In particular, this result implies exact values of f5(n) for n≥7.