cssi/SciSciGPT-SciSciNet huggingface dataset:
Image compression

Digital image compression methods reduce the space necessary to encode, store or transmit digital images by changing the way those images are represented. To see why image compression is desirable, consider an 8 × 10 inch color picture, digitized using a resolution of 600 pixels per inch and a byte for each of three color planes. Then the number of bytes required to represent each image is:
Quantitative Methods in Personality Research

The science of personality documents and explains ways that people differ with respect to their thoughts, feelings, social relationships, and experiences. Quantitative methods such as factor analysis played an important role in facilitating the discovery of the fundamental dimensions of personality. Recent developments in the application of multiple regression, structural equation modeling, hierarchical linear modeling, item response theory, and taxometrics allow personality researchers to test increasingly sophisticated models of personality processes. Keywords: personality; measurement; individual differences; factor analysis; multiple regression; item response theory; structural equation modeling
COFFINITE, A URANOUS SILICATE WITH HYDROXYL SUBSTITUTION: A NEW MINERAL

Report discussing the properties of coffinite, a uranous silicate mineral. Coffinite was newly discovered at the time of this report's publication.
Witches and Aliens: How an Archaeologist Inspired Two New Religious Movements

Margaret Murray (1863–1963) was a major figure in the creation of professional archaeology, president of the Folklore Society, and advocate for women’s rights. Her popular legacy today is the concept of the “witch-cult,” a hidden ancient religion persecuted as witchcraft. Murray’s witch-cult not only inspired Neopaganism but is foundational for author H. P. Lovecraft’s Cthulhu Mythos. These modern myths cast a long shadow on not only fantastical literature but on paranormal beliefs, preserving outdated elements of Victorian archaeology in popular culture concerned with alternative archaeology and the occult.
Physician Participation in Lethal Injection.

Physician Participation in Lethal Injection In Bucklew v. Precythe, the Supreme Court decided against a death-row inmate with a rare medical condition. The case reveals to an unprecedented degree t...
Drought regimens predict life history strategies in Heliophila.

Explaining variation in life history strategies is an enduring goal of evolutionary biology and ecology. Early theory predicted that for plants, annual and perennial life histories reflect adaptations to environments that experience alternative drought regimens. Nevertheless, empirical support for this hypothesis from comparative analyses remains lacking. Here, we test classic life history theory in Heliophila L. (Brassicaceae), a diverse genus of flowering plants native to Africa, controlling for phylogeny and integrating 34 yr of satellite-based drought detection with 2192 herbaria occurrence records. We find that the common ancestor of these species was likely to be an annual, and that perenniality and annuality have repeatedly evolved, an estimated seven and five times, respectively. By comparing historical drought regimens, we show that annuals rather than perennial species occur in environments where droughts are significantly more frequent. We also find evidence that annual plants adapt to predictable drought regimens by escaping drought-prone seasons as seeds. These results yield compelling support for longstanding theoretical predictions by revealing the importance of drought frequency and predictability to explain plant life history. More broadly, this work highlights scalable approaches, integrating herbaria records and remote sensing to address outstanding questions in evolutionary ecology.
Ultrafast Welding Dynamics of Plasmonic Nanorod Dimers

Transient absorption (TA) experiments were performed to determine the mechanisms controlling the welding process of plasmonic nanorod dimers using ultrafast light pulses. The TA signals during the self-assembly and welding of the nanorod dimers were temporally and spectrally resolved, enabling each potential mechanism to be isolated by their associated time scales. For all the TA measurements collected between 5 and 1000 ps, no abrupt or anomalous TA signals were observed that would indicate a welding event had occurred during this temporal regime. A cumulative multipulse welding mechanism beyond 1000 ps is unlikely since the nanorods return to their ground state before the next laser pulse arrives. To understand the dynamics below 5 ps, we fit the welding kinetics data to a rate equation and determined a threshold fluence of 79 μJ/cm2 was needed to initiate welding. To correlate the threshold fluence to a physical mechanism, finite element calculations were used to show the nanorods reached temperatures ...
Mild, selective cleavage of amino acid and peptide β-(trimethylsilyl)ethoxymethyl (SEM) esters by magnesium bromide

Abstract Magnesium bromide etherate has been previously shown to cleave β-(trimethylsilyl)ethoxymethyl (SEM) esters of aliphatic acids. This methodology has now been extended to amino acid and peptide derivatives in the presence of protecting groups typically encountered in peptide chemistry, including the Boc, Cbz, Fmoc and Troc carbamates as well as benzyl-, tert-butyl- and tert-butyldimethylsilyl ethers. The stability of fluoride sensitive protecting groups to magnesium bromide allows for added selectivity in the removal of SEM esters in organic synthesis.
GREIN: An Interactive Web Platform for Re-analyzing GEO RNA-seq Data

The vast amount of RNA-seq data deposited in Gene Expression Omnibus (GEO) and Sequence Read Archive (SRA) is still a grossly underutilized resource for biomedical research. To remove technical roadblocks for reusing these data, we have developed a web-application GREIN (GEO RNA-seq Experiments Interactive Navigator) which provides user-friendly interfaces to manipulate and analyze GEO RNA-seq data. GREIN is powered by the back-end computational pipeline for uniform processing of RNA-seq data and the large number (>6,500) of already processed datasets. The front-end user interfaces provide a wealth of user-analytics options including sub-setting and downloading processed data, interactive visualization, statistical power analyses, construction of differential gene expression signatures and their comprehensive functional characterization, and connectivity analysis with LINCS L1000 data. The combination of the massive amount of back-end data and front-end analytics options driven by user-friendly interfaces makes GREIN a unique open-source resource for re-using GEO RNA-seq data. GREIN is accessible at: https://shiny.ilincs.org/grein , the source code at: https://github.com/uc-bd2k/grein , and the Docker container at: https://hub.docker.com/r/ucbd2k/grein .
Enhanced solid-state metathesis routes to carbon nanotubes.

Ignition of three solids creates multiwalled carbon nanotubes in seconds. A solid-state metathesis (exchange) reaction between hexachloroethane (C2Cl6) and lithium acetylide (Li2C2) with 5% cobalt ...
Explosion and Ion Association Chemistry of the Anion Radicals of 2,4,6-Trinitrotoluene, 2,6-Dinitrotoluene, and Trinitrobenzene.

EPR analysis shows that the anion radical of 2,6-dinitrotoluene (DNT) in liquid ammonia exists with the counterion (either K+ or Na+) associated with one of the two nitro groups. This tight association (−NO2•-M+) persists after solvent removal, and it renders the anion radical very susceptible to loss of metal nitrite. The slightest agitation of the solid potassium salt of DNT•- leads to detonation, and formation of KNO2 and polymer (in the solid phase) and CH4, HCN, H2, and N2O (in the gas phase). Trapping experiments suggest that the methane comes from carbenes, and it is suggested that the HCN comes from an anthranil radical intermediate. The potassium anion radical salts of 1,3-dinitrobenzene, 2,6-dinitrotoluene, 1,3,5-trinitrobenzene, and 2,4,6-trinitrotoluene all readily lose KNO2, and the ease of C−NO2•-M+ bond rupture increases with the degree of nitration. In the cases of the two trinitrated systems dissociation takes place immediately upon anion radical formation in liquid ammonia. This observat...
Synthesis of the tripeptide (C1–N12) and hydroxylated hexadecene (C26–C41) domains of sanglifehrin A and C

Abstract Fully enantio-controlled routes to two major segments of the newly discovered immunosuppressants sanglifehrin A and C are described.
Salt-inclusion synthesis of Ba2MnSi2O7Cl. A fresnoite-type polar framework containing the acentric [Si2O7]6 - polyanion in the anti-ReO3 type [(Ba2Mn)Cl]6+) cage

A novel non-centrosymmetric (NCS) solid, Ba 2 Mn(Si 2 O 7 )Cl (CU-13), was isolated via high-temperature, salt-inclusion reactions. This manganese(III) silicate chloride adopts the fresnoite structure exhibiting pseudo-one-dimensional channels in which the Ba 2 + cations reside. The framework can be viewed alternatively as made of a fascinating anti-ReO 3 type (Ba 2 Mn)Cl lattice centered on the acentric Si 2 O 7 unit. This new compound crystallizes in one of the 10 NCS polar crystal classes, 4mm (C 4 v ), which is cooperatively attributed to the MnO 4 Cl 2 tetragonal distortion and the oriented Si 2 O 7 polyhedral unit. This discovery once again demonstrates the utility of salt inclusion with the formation of NCS frameworks.
An Efficient “One Pot” Synthesis of Isoflavones

Abstract Initial formation of deoxybenzoin 3 from phenyl acetic acid 1 and phenol 2 in the presence of BF3.Et2O followed by its treatment at room temperature with N, N'-dimethyl (chloromethylene) ammonium chloride, generated by reacting PCl5 with DMF provides a mild and efficient route for a “one pot” synthesis of Isoflavones in high yields.
Bootstrapping and Empirical Bayes Methods Improve Rhythm Detection in Sparsely Sampled Data

There is much interest in using genome-wide expression time series to identify circadian genes. However, the cost and effort of such measurements often limit data collection. Consequently, it is difficult to assess the experimental uncertainty in the measurements and, in turn, to detect periodic patterns with statistical confidence. We show that parametric bootstrapping and empirical Bayes methods for variance shrinkage can improve rhythm detection in genome-wide expression time series. We demonstrate these approaches by building on the empirical JTK_CYCLE method (eJTK) to formulate a method that we term BooteJTK. Our procedure rapidly and accurately detects cycling time series by combining information about measurement uncertainty with information about the rank order of the time series values. We exploit a publicly available genome-wide data set with high time resolution to show that BooteJTK provides more consistent rhythm detection than existing methods at typical sampling frequencies. Then, we apply BooteJTK to genome-wide expression time series from multiple tissues and show that it reveals biologically sensible tissue relationships that eJTK misses. BooteJTK is implemented in Python and is freely available on GitHub at https://github.com/alanlhutchison/BooteJTK .
Enzymatic Resolution of Aminocyclopentenols as Precursors to d- and l-Carbocyclic Nucleosides

Racemic cis-4-aminocyclopent-2-en-1-ols were synthesized in three steps utilizing hetero Diels−Alder chemistry. Starting from suitably protected hydroxylamines, oxidization with sodium periodate and trapping with cyclopentadiene afforded cycloadducts (±)-5a−d. The N−O bond of the cycloadducts was reduced with Mo(CO)6 to afford (±)-cis-4-aminocyclopent-2-en-1-ols (±)-6a−d. These compounds, or their corresponding acetates, were kinetically resolved by enzymatic acetylation or hydrolysis, respectively. Enzymatic acetylation of cis-N-(benzylcarbamoyl)-4-aminocyclopent-2-enol [(±)-6a] with Candida antarctica B lipase and Pseudomonas species lipase gave the corresponding acetate (−)-7a in 90% and 92% ee, respectively, after 40% conversion. Enzymatic hydrolysis of cis-N-acetyl-4-aminocyclopent-2-enol 1-O-acetate (±)-7d with electric eel acetylcholine esterase was successful in providing both cis-N-acetyl-4-aminocyclopent-2-enols (+)-6d and (+)-7d in 92% ee (99% ee after a single recrystallization) after 40% conv...
The preparation of (EtO)2P(O)CFHZnBr and (EtO)2P(O)CFHCu and their utility in the preparation of functionalized α-fluorophosphonates

Abstract The organometallic reagent, (EtO)2P(O)CFHZnBr, was generated in situ in excellent yields via the reaction of (EtO)2P(O)CFHBr with zinc metal. Metathesis with Cu(I)Br gave (EtO)2P(O)CFHCu. The reagents exhibit excellent reactivity with substrates, such as allyl halides, alkynyl halides, vinyl halides, aryl halides and acyl or phosphoryl halides, and provide a useful one flask route to functionalized α-fluorophosphonates.
A direct synthesis of α-keto five- and six-membered cyclic ethers

A simple synthesis of tetrahydro-2H-pyran-2-yl and tetrahydrofuran-2-yl ketones from their corresponding carboxylic acids was studied. A comparison was made of organolithium and Grignard alkylating reagents as a means of reducing the formation of byproducts and improving the yields.
Structure and Spectra of UO2F2 and Its Hydrated Species

The electronic spectra of UO2F2, both isolated and hydrated, have been studied using ab initio spin−orbit configuration interaction calculations based on relativistic effective core potentials. The structures of UO2F2 species were obtained by the density functional theory method. The initial structure has a (nonplanar) C2v geometry, while adding solvating water molecules and optimizing the structure UO2F2(H2O)n give a very stable structure for n = 4, with D2 geometry. The ground state and some excited states were studied for UO2F2(H2O)n using the structures obtained. Electric-dipole transition moments were calculated for UO2F2(H2O)4. Spin−orbit and equatorial−ligand (F-, H2O) interactions compete in determining the splittings of the known 3Δg state of the uranyl ion, particularly the 3Δ1g luminescent state.
Microwave-assisted preparation of cyclic ureas from diamines in the presence of ZnO

Abstract A microwave-assisted facile method for the preparation of various ureas, cyclic ureas, and urethanes has been developed that affords nearly quantitative yield of products at 120 °C (150 W), 71 kPa within 10 min using ZnO as a catalyst. The enhanced selectivity in this reaction is attributed to the deployment of ZnO whose absence results in poor yield and the generation of byproducts.
Functionalization of 2,3-Disubstituted-2,3-dihydro-5,10,15,20-tetraphenylporphyrins

Abstract A reduced pyrrole subunit directs electrophilic functionalizations of dihydroporphyrins to the antipodal pyrrole ring by confining the chromophore 18-π-electron delocalization pathway to its N(22)H-N(24)H tautomer. The 2,3-disubstituents inhibit oxidation, this being exemplified by the synthesis of perbrominated dodecasubstituted metallochlorins. Regiospecific nitration (using N2O4) of metal-free chlorins provides access to Michael acceptors such as 12-nitro-2,3-disubstituted chlorins which are used in the preparation of highly functionalized tetraaryl-bacteriochlorins by conjugate addition of carbon-centered nucleophiles.
Theta-gamma cascades and running speed

Often, the theta and gamma oscillations in the hippocampus have been believed to be a consequence of two marginally overlapping phenomena. This perspective, however, runs counter to an alternative ...
New Triterpene-Ketides (Merotriterpenes), Haliclotriol A and B, from an Indo–Pacific Haliclona Sponge

Abstract Two new terpene-ketides, haliclotriol A and B ( 1 and 3 ), have been isolated from the Indonesian sponge Haliclona sp. Their structure and relative stereochemical features were determined by 1D and 2D NMR spectroscopy and by converting 1 to its corresponding triacetate 2 . The hexacyclic core of 1 and 3 appears to arise via a biosynthetic cyclization of a hexaprenylbenzoquinone type precursor and 1 has an additional C 2 functionalization on the aromatic ring. Haliclotriol B demonstrated weak antimicrobial activity against B. subtilis and S. aureus .
A Convenient Preparation of Triisopropylsilyl Acyl Silanes.

Abstract Treatment of α-epoxytriisopropylsilane with selected nucleophiles leads to α-silyl alcohols which are readily oxidized to the corresponding TIPS acyl silanes in good overall yields.
Homoaromaticity in carbene intermediates

Analyses of isodesmic reactions for singlet 7-carbenanorbornene (4S), 8-carbena-endo-tricyclo[3.2.1.02,4]octane (5S), 3-carbenabicyclo[3.1.0]hexane (3S), 2-carbenanorbornene 6S, and 2-carbenabicyclooctadiene 7S at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31G* level provide stabilization energies of 13.83, 13.50, 3.00, −2.22, and −3.01 kcal/mol, respectively. The C7 carbene in 4S and the C8 carbene center in 5S are strongly bent toward the double bond and cyclopropane ring, respectively, in contrast to their related triplets, 4T and 5T and parent hydrocarbons. The geometric change for 3S compared to 3T or to parent bicyclo[3.1.0]hexane is minimal. Comparison of the stability of 6S with 2-carbenanorbornane and the geometry of 6S with that of 6T and also with the singlet and triplet 2-carbenanorbornane suggests very modest bridging. The stabilization energy and geometry of 2-carbenabicyclooctadiene 7 resemble antihomoaromatic bicyclooctadienyl cation 9 rather than the related homoaromatic bicyclooctadienyl anion 8...
New and improved ligands for highly enantioselective catalytic diphenylzinc additions to aryl aldehydes

Abstract By introducing electron-withdrawing fluorine atoms to a chiral 1,1′-binaphthyl ligand ( R )- 1 , a new catalyst ( S )- 5d has been obtained which shows improved catalytic properties for the asymmetric diphenylzinc addition to aldehydes. This new ligand allows the synthesis of chiral diarylcarbinols with high enantioselectivity in shorter reaction time under simple reaction conditions.
Evolution of hierarchy in bacterial metabolic networks.

Abstract Flow hierarchy is a useful way to characterize the movement of information and matter throughout a network. Hierarchical network organizations are shown to arise when there is a cost of maintaining links in the network. A similar constraint exists in metabolic networks, where costs come from reduced efficiency of nonspecific enzymes or from producing unnecessary enzymes. Previous analyses of bacterial metabolic networks have been used to predict the minimal nutrients that a bacterium needs to grow, its mutualistic relationships with other bacteria, and its major ecological niche. We use metabolic network inference to obtain metabolite flow graphs of 2935 bacterial metabolic networks and find that flow hierarchy evolves independently of modularity and other network properties. By inferring the ancestral metabolic networks and estimating the hierarchical character of the inferred network, we show that hierarchical structure first increased and later decreased over evolutionary history. Furthermore, hierarchical structure in the network is associated with slower growth rates; bacteria with hierarchy scores above the median grow on average 2.25 times faster than those with hierarchy scores below the median.
X-ray Crystal Structures of [XF6][Sb2F11] (X = Cl, Br, I); 35,37Cl, 79,81Br, and 127I NMR Studies and Electronic Structure Calculations of the XF6+ Cations

The single-crystal X-ray structures of [XF6][Sb2F11] (X = Cl, Br, I) have been determined and represent the first detailed crystallographic study of salts containing the XF6+ cations. The three sal...
Enantioselective synthesis of bicarbocyclic structures with an all-carbon quaternary stereocenter through sequential cross metathesis and intramolecular Rauhut–Currier reaction

Abstract A new extension of the Birch–Cope sequence is described which allows the efficient enantioselective construction of highly functionalized, fused bicarbocyclic structures with an all-carbon quaternary stereocenter in two steps. The two-step sequence includes a cross metathesis between a terminal alkene and a polarized alkene followed by an intramolecular Rauhut–Currier reaction with a trialkylphosphine catalyst.
Pt-Ag Catalyst System for Hydroarylations with Unactivated Arenes and Olefins

A series of Pt complexes activated by Ag(I) salts have been shown to catalyze Markovnikov hydroarylations of unactivated olefins under mild conditions.
Push–pull alkenes by reacting N,N′-dimethyl cyclic ketene N,N′-acetals with isocyanates: synthesis, structures, and reactivities

Abstract N , N′ -Dimethyl cyclic ketene N , N′ -acetals react with two or three equivalents of isocyanates to generate tetrasubstituted push–pull alkene derivatives in one-pot sequential reactions. X-ray crystallography showed significant elongations and out of plane distorsions of the polarized carbon–carbon double bonds.
Nomenclature and Structural Representation for Linear, Single-Strand Polymers Aftertreated to Hyperconnected Networks

Source-based versus structure-based representations are discussed for linear, single-strand structural-repeating unit (SRU) type polymers that are aftertreated (post-reacted) with bifunctional cross-linking agents to give completely cross-linked, three-dimensional networks. The problems of their structure registration by use of the Chemical Abstracts Service Registry System are discussed, and a structure-based nomenclature and representation system for them is presented.
An efficient and general urazole synthesis

Abstract A general two-step scheme for the synthesis of N4 substituted urazoles (i.e., 1,2,4-triazolin-3,5-diones) is described. The first step involves the reaction of a primary amine with 2.5 equiv of phenyl chloroformate to produce diphenyl (N-substituted)imidodicarbonates. The second step involves the reaction of these compounds with hydrazine to produce N4 substituted urazoles. The mild reaction conditions permit synthesis of N4 oxygenated urazoles, not available via existing methodology. Bicyclic urazoles can be prepared through the subsequent reaction of these N4-protected urazoles with 2.5 equiv of NaH in DMF together with either 1,3-dibromopropane or 2-( tert -butyldimethylsilyloxy)-1,3-dibromopropane in the presence of NaI. The resultant bicyclic urazoles are observed to display varying degrees of pyrimidalization at N1 and N2, depending on substituents.
Endogenous viable cells in lyopreserved amnion retain differentiation potential and anti-fibrotic activity in vitro

Abstract Human amniotic membrane (AM) has intrinsic anti-inflammatory, anti-fibrotic and antimicrobial properties. Tissue preservation methods have helped to overcome the short shelf life of fresh AM allowing “on demand” use of AM grafts. Cryopreserved AM that retains all native tissue components, including viable cells, has clinical benefits in treating chronic wounds. However, cryopreservation requires ultra-low temperature storage, limiting the use of cryopreserved products. To overcome this limitation, a new lyopreservation method has been developed for ambient storage of living tissues. The goal of this study was to investigate the viability and functionality of AM cells following lyopreservation. Fresh AM and devitalized lyopreserved AM (DLAM) served as positive and negative controls, respectively. Using live/dead staining, we confirmed the presence of living cells in viable lyopreserved AM (VLAM) and showed that these cells persisted up to 21 days in culture medium. The functionality of cells in VLAM was assessed by their differentiation potential and anti-fibrotic activity in vitro. With osteogenic induction, cells in VLAM deposited calcium within the membrane, a marker of osteogenic cells, in a time-dependent manner. The migration of human lung fibrotic fibroblasts in a scratch wound assay was reduced significantly in the presence of VLAM-derived conditioned medium. Quantitative PCR analyses indicated that VLAM reduced the expression of pro-fibrotic factors such as type I collagen and increased the expression of anti-fibrotic factors such as hepatocyte growth factor and anti-fibrotic microRNA in fibrotic fibroblasts. Taken together, these results demonstrate that endogenous cells in VLAM remain viable and functional post-lyophilization. Statement of Significance This study, for the first time, provides direct evidence showing that tissue viability and functional cells can be preserved by lyophilization. Similar to fresh amniotic membrane (AM), viable lyopreserved AM (VLAM) retains viable cells for extended periods of time. More importantly, these cells are functional and maintain their osteogenic differentiation potential and anti-fibrotic activity. Our results confirmed that the novel lyophilization method preserves tissue viability.
Facile stereoselective synthesis of γ-substituted γ-amino acids from the corresponding α-amino acids

Abstract A facile stereoselective method for the synthesis of γ-substituted, γ-amino acids from α-amino acids was developed. The key step of the procedure is complete reduction of the keto functionality of α-amino acyl Meldrum's acid by sodium acetoxyborohydride. The resulting amino alkyl Meldrum's acid undergoes thermal decarboxylative ring closure to a 5-substituted pyrrolidinone which yields the corresponding γ-amino acid after basic hydrolysis. The overall yield of the procedure ranges from 40 to 65%.
Cation Mobility and Kinetics of Ion Exchange in Zirconium Hydrogen Monothiophosphate Hydrate, Zr(HPO3S)2·1.5H2O

The ion conductivity of zirconium hydrogen monothiophosphate (Zr(HPO 3 S) 2 .1.5H 2 O) has been measured by impedance spectroscopy. The measured value of proton conductivity is 3 x 10 - 5 S/cm at 298 K. Conductivity was shown to decrease with increasing temperature due to a dehydration process. Above 450 K, the conductivity is likely governed by proton transport in the anhydrous phase Zr(HPO 3 S) 2 . The activation energies of proton conductivity were measured to be 18 ′ 2 kJ/mol for Zr(HPO 3 S) 2 .1.5H 2 O and 60 ′ 3 kJ/mol for the anhydrous compound. The kinetics of ion exchange was studied with the use of potentiometric titration for several ion pairs, H + /Na + , H + /Zn 2 + , and Na + /Zn 2 + in Zr(HPO 3 S) 2 .1.5H 2 O. The diffusion coefficient values for H + /Na + ion exchange in Zr(HPO 3 S) 2 . 1.5H 2 O are lower than those reported in α-zirconium phosphate. At the same time, the mobility of zinc ions in Zr(HPO 3 S) 2 .1.5H 2 O is higher than sodium ion mobility. The ion exchange H + /Zn 2 + is accompanied by the slow hydrolysis of the initial compound. In all cases, the powdered solids were evaluated by powder X-ray diffraction, and particle sizes were controlled by grinding and sieving the powders.
A Versatile Strategy for the Synthesis of 2,6-Disubstituted Dihydropyranones

A concise synthesis of 2,6-disubstituted dihydropyranones was developed. This sequence is based on the Smith three-component dithiane linchpin coupling strategy. By simply switching the order of epoxide addition in the linchpin coupling step, two analogous dihydropyranones were prepared in good yield from the same starting materials. This sequence allows for considerable flexibility in the nature of R1 and R2 groups, which facilitates the preparation of a diverse array of 2,6-disubstituted dihydropyranones.
Rhodium carbenoid N-H insertion reactions of primary ureas: solution and solid-phase synthesis of imidazolones.

The solution and solid-phase synthesis of imidazolones is reported. The key step for the preparation of these compounds is the N−H insertion reaction of primary ureas into highly reactive rhodium carbenoid intermediates. Typically, a soluble or support-bound α-diazo-β-ketoester is treated with a rhodium carboxylate catalyst in the presence of a primary urea to give the corresponding N−H insertion product. Subsequent acid-catalyzed cyclodehydration of these insertion products affords the desired imidazolone products.
Simultaneous CRISPR/Cas9-mediated editing of cassava eIF4E isoforms nCBP-1 and nCBP-2 reduces cassava brown streak disease symptom severity and incidence

Cassava brown streak disease (CBSD) is a major constraint on cassava yields in East and Central Africa and threatens production in West Africa. CBSD is caused by two species of positive-sense RNA viruses belonging to the family Potyviridae, genus Ipomovirus: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Diseases caused by the family Potyviridae require the interaction of viral genome-linked protein (VPg) and host eukaryotic translation initiation factor 4E (eIF4E) isoforms. Cassava encodes five eIF4E proteins: eIF4E, eIF(iso)4E-1, eIF(iso)4E-2, novel cap-binding protein-1 (nCBP-1), and nCBP-2. Protein-protein interaction experiments consistently found that VPg proteins associate with cassava nCBPs. CRISPR/Cas9-mediated genome editing was employed to generate ncbp-1, ncbp-2, and ncbp-1/ncbp-2 mutants in cassava cultivar 60444. Challenge with CBSV showed that ncbp-1/ncbp-2 mutants displayed delayed and attenuated CBSD aerial symptoms, as well as reduced severity and incidence of storage root necrosis. Suppressed disease symptoms were correlated with reduced virus titre in storage roots relative to wild-type controls. Our results demonstrate the ability to modify multiple genes simultaneously in cassava to achieve tolerance to CBSD. Future studies will investigate the contribution of remaining eIF4E isoforms on CBSD and translate this knowledge into an optimized strategy for protecting cassava from disease.
The tricarbonylchromium template for stereocontrol in radical reactions of arenes.

Chromium tricarbonyl complexed aryl aldeyhydes and ketones underwent Sm(II)-promoted radical lactone formation in the presence of α,β-unsaturated esters to produce diastereomerically pure lactones in good yields. The completely diastereoselective lactone formation involves capture of the benzylic ketyl radical by the ester anti to the chromium tricarbonyl moiety. The relative stereochemistry of the lactone and chromium tricarbonyl moieties was proven by X-ray crystallography and supports the proposed mechanism. Enantiopure chromium tricarbonyl complexed arenes afforded single enantiomers when subjected to Sm(II)-promoted radical lactone formation condiditions. The enantio- and diastereomerically pure chromium tricarbonyl complexed lactones were subsequently treated with BF3·OEt2 to generate a mixture of diastereomers via Lewis acid promoted chromium tricabonyl directed cationic rearrangement. The diastereomers were separated and individually decomplexed with I2 to afford both of the corresponding chromium...
Palladium/Cuprous Iodide Catalyzed Coupling of Substituted Tetrafluorophenyl Halides With 1-Alkynes

Abstract In the presence of cuprous iodide, the palladium catalyzed coupling reaction of substituted tetrafluorophenyl halides with 1- alkynes gives the corresponding fluoroaryl alkynes in good to excellent yields under mild conditions. Both 4-substituted (methoxy, N,N-dimethylamino, morpholino) tetrafluorophenyl iodides and bromides work well, and alkyl, trimethylsilyl, phenyl, hydroxy, and ether functionalities in the alkyne moiety are tolerated under the reaction conditions. This methodology provides a practical synthesis of substituted fluorinated aryl alkynes.
Mimicking aldolases through organocatalysis: syn-selective aldol reactions with protected dihydroxyacetone.

A practical organocatalytic strategy designed to mimic the l-rhamnulose 1-phosphate and d-fructose 1,6-diphosphate aldolases has been developed and shown to be effective in the preparation of carbo...
Synthesis of [5,6-3H](+/−) Gamma Vinyl GABA

Abstract An efficient synthesis of [5,6-3H] (+/−) gamma vinyl GABA 5 from 4-aminohex-5-ynoic acid 3 is described.
Self-assembly of metal-organometallic coordination networks

A range of neutral metal-organometallic coordination networks (MOMNs) containing both backbone and pendant metal sites have been synthesized and characterized. These materials consist of metal ions or metal ion clusters as nodes that are linked by the bifunctional organometalloligand (η 4 -benzoquinone)Mn(CO) 3 - , which binds through the quinone oxygen atoms. The resulting MOMNs can be rationally designed to a significant extent based upon a knowledge of the electronic and geometrical requirements of the metal ion nodes, the solvent, organometalloligand substituents, and the presence or absence of organic spacers. An impressive range of architectures have been accessed in this manner, suggesting that the use of π-organometallics in coordination directed self-assembly holds much promise.
Exploration of fundamental and synthetic aspects of the intramolecular 4 + 3 cycloaddition reaction.

In this Account, a summary of our work in the exploration and development of intramolecular 4 + 3 cycloaddition reactions between dienes and allylic cations is presented. Alkoxyallylic sulfones are...
Social evolution and genetic interactions in the short and long term.

The evolution of social traits remains one of the most fascinating and feisty topics in evolutionary biology even after half a century of theoretical research. W.D. Hamilton shaped much of the field initially with his 1964 papers that laid out the foundation for understanding the effect of genetic relatedness on the evolution of social behavior. Early theoretical investigations revealed two critical assumptions required for Hamilton’s rule to hold in dynamical models: weak selection and additive genetic interactions. However, only recently have analytical approaches from population genetics and evolutionary game theory developed sufficiently so that social evolution can be studied under the joint action of selection, mutation, and genetic drift. We review how these approaches suggest two timescales for evolution under weak mutation: (i) a short-term timescale where evolution occurs between a finite set of alleles, and (ii) a long-term timescale where a continuum of alleles are possible and populations evolve continuously from one monomorphic trait to another. We show how Hamilton’s rule emerges from the short-term analysis under additivity and how non-additive genetic interactions can be accounted for more generally. This short-term approach reproduces, synthesizes, and generalizes many previous results including the one-third law from evolutionary game theory and risk dominance from economic game theory. Using the long-term approach, we illustrate how trait evolution can be described with a diffusion equation that is a stochastic analogue of the canonical equation of adaptive dynamics. Peaks in the stationary distribution of the diffusion capture classic notions of convergence stability from evolutionary game theory and generally depend on the additive genetic interactions inherent in Hamilton’s rule. Surprisingly, the peaks of the long-term stationary distribution can predict the effects of simple kinds of non-additive interactions. Additionally, the peaks capture both weak and strong effects of social payoffs in a manner difficult to replicate with the short-term approach. Together, the results from the short and long-term approaches suggest both how Hamilton’s insight may be robust in unexpected ways and how current analytical approaches can expand our understanding of social evolution far beyond Hamilton’s original work.
Improving Open Information Extraction via Iterative Rank-Aware Learning

Open information extraction (IE) is the task of extracting open-domain assertions from natural language sentences. A key step in open IE is confidence modeling, ranking the extractions based on their estimated quality to adjust precision and recall of extracted assertions. We found that the extraction likelihood, a confidence measure used by current supervised open IE systems, is not well calibrated when comparing the quality of assertions extracted from different sentences. We propose an additional binary classification loss to calibrate the likelihood to make it more globally comparable, and an iterative learning process, where extractions generated by the open IE model are incrementally included as training samples to help the model learn from trial and error. Experiments on OIE2016 demonstrate the effectiveness of our method. Code and data are available at https://github.com/jzbjyb/oie_rank.
Studies directed toward the synthesis of ulapualide A: Phosphorus-based olefination as model studies for (Schlosser-like) fragment coupling

Abstract Preliminary studies aimed at developing reaction conditions for the fragment coupling between the C26C42 fragment and the tris-oxazole fragment of ulapualide A are described. Our approach utilizes Schlosser-Wittig olefination conditions for the construction of a trans-double bond. In this study, seven different tri-alkyl and tri-aryl phosphines were evaluated in an attempt to determine the extent of trans cis selectivity for the prospective construction of the trans-C25C26 double bond of ulapualide A.
Accounting for Apparent Deviations between Calorimetric and van’t Hoff Enthalpies

Abstract Background In theory, binding enthalpies directly obtained from calorimetry (such as ITC) and the temperature dependence of the binding free energy (van't Hoff method) should agree. However, previous studies have often found them to be discrepant. Methods Experimental binding enthalpies (both calorimetric and van't Hoff) are obtained for two host-guest pairs using ITC, and the discrepancy between the two enthalpies is examined. Modeling of artificial ITC data is also used to examine how different sources of error propagate to both types of binding enthalpies. Results For the host-guest pairs examined here, good agreement, to within about 0.4 kcal/mol, is obtained between the two enthalpies. Additionally, using artificial data, we find that different sources of error propagate to either enthalpy uniquely, with concentration error and heat error propagating primarily to calorimetric and van't Hoff enthalpies, respectively. Conclusions With modern calorimeters, good agreement between van't Hoff and calorimetric enthalpies should be achievable, barring issues due to non-ideality or unanticipated measurement pathologies. Indeed, disagreement between the two can serve as a flag for error-prone datasets. A review of the underlying theory supports the expectation that these two quantities should be in agreement. General significance We address and arguably resolve long-standing questions regarding the relationship between calorimetric and van't Hoff enthalpies. In addition, we show that comparison of these two quantities can be used as an internal consistency check of a calorimetry study.
Acid- and isobutylene-free synthesis of t-butyl ethers by in situ formation of 2-t-butoxy-1-methylpyridinium triflate

Abstract The title reagent is formed in situ by alkylation of 2-t-butoxypyrine. The subsequent addition of an alcohol substrate leads to the formation of t-butyl ethers without the need for isobutylene gas or acid activators.
Electrochemical conversion of nitrate to ammonia in water using cobalt-DIM as catalyst

Abstract Co-DIM [DIM=2,3-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,3-diene], a Co(cyclam) analog, is reported to catalyze the electrochemical reduction of nitrate to ammonia. The Co(II)/Co(I) reduction of this compound in aqueous sodium bromide solutions was nearly reversible on pyrolytic graphite electrodes. The complex was catalytically active for reduction of NO 3 − as well as its reduction intermediates NO 2 − and hydroxylamine. Ammonia was the sole product found after electrolysis of sodium nitrate in the presence of Co-DIM on a carbon felt cathode.
Open air palladium catalyzed cyanation—the use of PMHS to protect from oxygen

PMHS (polymethylhydrosiloxane) used in catalytic amounts has a remarkable ability to prevent catalyst poisoning by oxygen contamination during palladium catalyzed cyanation reactions. The procedure is applicable to a wide range of substrates and is so effective that it allows the reactions to be run fully open to the atmosphere.
Dual Role of Cell-Cell Adhesion In Tumor Suppression and Proliferation

Abstract It is known that mechanical interactions couple a cell to its neighbors, enabling a feedback loop to regulate tissue growth. However, the interplay between cell-cell adhesion strength, local cell density and force fluctuations in regulating cell proliferation is poorly understood. Here, we show that variations in the tumor growth rates, which depend on the location of cells within tissue spheroids, are strongly influenced by cell-cell adhesion. As the strength of the cell-cell adhesion increases, intercellular pressure initially decreases, enabling dormant cells to more readily enter into a proliferative state. We identify an optimal cell-cell adhesion regime where pressure on a cell is a minimum, allowing for maximum proliferation. We use a theoretical model to validate this novel feedback mechanism coupling adhesion strength, local stress fluctuations and proliferation. Our results, predicting the existence of a non-monotonic proliferation behavior as a function of adhesion strength, are consistent with experimental results. Several experimental implications of the proposed role of cell-cell adhesion in proliferation are quantified, making our model predictions amenable to further experimental scrutiny. We show that the mechanism of contact inhibition of proliferation, based on a pressure-adhesion feedback loop, serves as a unifying mechanism to understand the role of cell-cell adhesion in proliferation.
On Bayesian Fisher Information Maximization for Distributed Vector Estimation

In this paper, we consider the problem of bandwidth-constrained distributed estimation of a Gaussian vector with linear observation model. Each sensor makes a scalar noisy observation of the unknown vector, employs a multi-bit scalar quantizer to quantize its observation, and maps it to a digitally modulated symbol. Sensors transmit their symbols over orthogonal-power-constrained fading channels to a fusion center (FC). The FC is tasked with fusing the received signals from sensors and estimating the unknown vector. We derive the Bayesian Fisher Information Matrix (FIM) for three types of receivers: (i) coherent receiver; (ii) noncoherent receiver with known channel envelopes; and (iii) noncoherent receiver with known channel statistics only. We also derive the Weiss–Weinstein bound (WWB). We formulate two constrained optimization problems, namely maximizing trace and log-determinant of Bayesian FIM under network transmit power constraint, with sensors’ transmit powers being the optimization variables (we refer to as FIM-max schemes). We show that for coherent receiver, these problems are concave. However, for noncoherent receivers, they are not necessarily concave. The solution to the trace of Bayesian FIM maximization problem can be implemented in a distributed fashion, in the sense that each sensor calculates its own transmit power using its local parameters. On the other hand, the solution to the log-determinant of Bayesian FIM maximization problem cannot be implemented in a distributed fashion and the FC needs to find the powers (using parameters of all sensors) and inform the active sensors of their transmit powers. We numerically investigate how the FIM-max power allocation across sensors depends on the sensors observation qualities and physical layer parameters as well as the network transmit power constraint. Moreover, we evaluate the system performance in terms of mean square error (MSE) using the solutions of FIM-max schemes, and compare it with the solution obtained from minimizing the MSE of the LMMSE estimator (MSE-min scheme), and that of uniform power allocation. These comparisons illustrate that, although the WWB is tighter than the inverse of Bayesian FIM, it is still suitable to use FIM-max schemes, since the performance loss in terms of the MSE of the LMMSE estimator is not significant. Furthermore, comparing the performance of different receivers, our numerical results reveal that coherent receiver and noncoherent receiver with known channel statistics have the best and the worst performance, respectively.
Power-traffic coordinated operation for bi-peak shaving and bi-ramp smoothing – A hierarchical data-driven approach

Abstract The power distribution system and urban transportation system are two networked system bare their own operation constraints, such peak load in power systems and traffic congestion in transportation system. With the increasing number of electrical vehicles and charging/discharging stations, two systems are become tightly coupled. However, to optimize the two systems target using electrical vehicles as decision control variables cannot be easily solved using a uniformed optimization frame work. Thus we propose a hierarchical optimization approach to address this problem, which consists of a higher and a lower level. In the higher level, the power distribution system and urban transportation system are treated together to minimize the social cost. Meanwhile, the electrical vehicles and the charging/discharging stations are treated as customers to minimize their own expenditures. Then, an equilibrium is designed to determine the optimal charging/discharging price. In the lower level, the models of power distribution system and urban transportation system are developed to provide a detailed analysis. Specifically, in power distribution system, the three-phase unbalanced optimal power flow problem is relaxed with the semidefinite relaxation programming, and solved with alternating direction method of multiplier. A dynamic user equilibrium problem is formulated for the urban transportation system. For electrical vehicles, the state of charge is considered to optimize the charging/discharging schedule and reduce the impacts of power distribution systems. We conducted the simulation and numerical analysis using the IEEE 8500-bus distribution system and the Sioux Falls system with about 10,000 cars. The results demonstrate the feasibility and effectiveness of the proposed approach.
Decentralized computation of effective resistances and acceleration of consensus algorithms

The effective resistance between a pair of nodes in a weighted undirected graph is defined as the potential difference induced between them when a unit current is injected at the first node and extracted at the second node, treating edge weights as the conductance values of edges. The effective resistance is a key quantity of interest in many applications and fields including solving linear systems, Markov Chains and continuous-time averaging networks. We develop an efficient linearly convergent distributed algorithm for computing effective resistances and demonstrate its performance through numerical studies. We also apply our algorithm to the consensus problem where the aim is to compute the average of node values in a distributed manner. We show that the distributed algorithm we developed for effective resistances can be used to accelerate the convergence of the classical consensus iterations considerably by a factor depending on the network structure.
Mining Attribute-Based Access Control Policies

Attribute-based access control (ABAC) provides a high level of flexibility that promotes security and information sharing. ABAC policy mining algorithms have potential to significantly reduce the cost of migration to ABAC, by partially automating the development of an ABAC policy from an access control list (ACL) policy or role-based access control (RBAC) policy with accompanying attribute data. This paper presents an ABAC policy mining algorithm. To the best of our knowledge, it is the first ABAC policy mining algorithm. Our algorithm iterates over tuples in the given user-permission relation, uses selected tuples as seeds for constructing candidate rules, and attempts to generalize each candidate rule to cover additional tuples in the user-permission relation by replacing conjuncts in attribute expressions with constraints. Our algorithm attempts to improve the policy by merging and simplifying candidate rules, and then it selects the highest-quality candidate rules for inclusion in the generated policy.