bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aerosol effects on summer monsoon over Asia during 1980s and 1990s
Authors: Tsai I‐Chun , Wang Wei‐Chyung , Hsu Huang‐Hsiung , Lee Wei‐Liang 
Published: September 2016

AbstractThe Community Earth System Model is used to study the aerosol climate effects during the 1980s and 1990s in which the anthropogenic SO2 emissions decreased in North America and Western Europe and increased in East and South Asia. From the 100 year simulations, aerosol forcing results in cooler (−0.13 K) and drier (−0.01 mm/day) atmosphere with less shortwave radiation flux at the surface (−0.37 W/m2). The clear‐sky shortwave radiation flux decreased over East Asia (−0.81 W/m2) and South Asia (−1.09 W/m2), but increased over Western Europe (+1.16 W/m2) and North America (+0.39 W/m2), consistent with aerosol loading changes. While changes in spatial distributions of all‐sky shortwave radiation and surface temperature are closely related to cloud changes, the changes in wind and precipitation do not correspond to aerosol loading changes, indicating the complexity of aerosol‐cloud circulation interactions. The East and South Asia monsoons were generally weakened due mainly to southward shift of the 200 hPa East Asia Jet (EAJ) and decrease in 850 hPa winds; annual precipitation decreased by 2% in South Asia but increased by 2% in Yangtze‐Huai River Valley over East Asia. The uncertainties associated with aerosol climate effects are addressed within the context of model variability and the global warming effect. For the latter, while the aerosol effects decrease the greenhouse warming on the global mean, the regional responses are different. Nevertheless, the characteristics of aerosol climate effects, including the southward 200 hPa EAJ and weakened South Asia monsoon, still persist when the climate becomes warmer, although the strength and the geographical distribution are slightly modulated.
Measuring and modeling the impact of a severe drought on terrestrial ecosystem CO2 and water fluxes in a subtropical forest
Authors: Xie Zhenghui , Wang Linying , Jia Binghao , Yuan Xing 
Published: September 2016

AbstractA severe drought occurred in central and southern China in the summer of 2013. The precipitation dropped to less than 25% of the long‐term average, and temperatures were abnormally high for more than 2 months with return periods of 125 years and 301 years, respectively, which induced significant changes in the terrestrial ecohydrological cycle. In this study, the impact of the severe drought on a subtropical forest ecosystem was investigated using measurements from a newly established flux tower and simulations performed by the Community Land Model version 4.5 (CLM4.5). Based on in situ observations, we found that both gross primary production (GPP) and evapotranspiration experienced strong reductions of 76% and 40%, respectively, during the prolonged dry and hot spell. There was an exponential relationship between ecosystem respiration (Reco) and temperatures when soil moisture was not too dry, but Reco decreased along with GPP when the temperature exceeded 32°C and soil moisture was below 0.14 m3 m−3. The ecosystem even switched to a net source of carbon in late August. The model captured the variations in water vapor fluxes well, with correlation coefficients r > 0.88, but overestimated net ecosystem CO2 exchange because it did not adequately represent carbon fluxes responses to water stress and failed to capture the nonlinear relationship between GPP and Reco during the drought period. The long‐term simulation suggested that water availability severely limited carbon sequestration, and both the underlying water use efficiency and inherent water use efficiency reached their maximum values.
Vertically resolved weak temperature gradient analysis of the Madden‐Julian Oscillation in SP‐CESM
Authors: Wolding Brandon O. , Maloney Eric D. , Branson Mark 
Published: September 2016

AbstractThe collective effects of convection can influence large‐scale circulations that, in turn, act to organize convective activity. Such scale interactions may play an important role in moisture‐convection feedbacks thought to be important to both convective aggregation and the Madden‐Julian Oscillation, yet such interactions are not fully understood. New diagnostics based on tropical weak temperature gradient (WTG) theory have begun to make this problem more tractable, and are leveraged in this study to analyze the relationship between various apparent heating processes and large‐scale vertical moisture advection in SP‐CESM. WTG theory provides a framework for accurately diagnosing intraseasonal variations in large‐scale vertical motion from apparent heating, allowing large‐scale vertical moisture advection to be decomposed into contributions from microphysical processes, subgrid scale eddy fluxes, and radiative heating. This approach is consistent with the column moist static energy (MSE) budget approach, and has the added benefit of allowing the vertical advection term of the column MSE budget to be quantitatively partitioned into contributions from the aforementioned apparent heating processes. This decomposition is used to show that the MJO is an instability strongly supported by radiative feedbacks and damped by horizontal advection, consistent with the findings of previous studies. Periods of low, moderate, and high MJO amplitude are compared, and it is shown that changes in the vertical structure of apparent heating do not play a dominant role in limiting the amplitude of the MJO in SP‐CESM. Finally, a diagnostic approach to scale analysis of tropical dynamics is used to investigate how the governing dynamics of various phenomena differ throughout wavenumber‐frequency space. Findings support previous studies that suggest the governing dynamics of the MJO differ from those of strongly divergent convectively coupled equatorial waves.
It Is Just Harder to Construct Memories for False Autobiographical Events
Authors: Pezdek Kathy , Blandon‐Gitlin Iris 
Published: September 2016

SummaryBrewin and Andrews (2016) review studies using three research paradigms—imagination inflation, false feedback, and memory implantation—and the prevalence rate for false memories differs widely across paradigms. Vast differences also result depending on the scheme used to code the recall data. Framing memory as a constructive process reveals many of the similarities between cognitive processes involved in memory for true and false events, similarities that account for why memories are far less likely to result for false events than true events. Memories for false events are just not as easy to construct and plant as has been suggested elsewhere. Copyright © 2016 John Wiley & Sons, Ltd.
An Unexpected Potassium Iodide‐Promoted Nucleophilic Substitution Reaction between 2‐Acyloxy‐2H‐azirines and Carboxylic Acids
Authors: Duan Xiyan , Yang Kun , Liu Jianwei , Kong Xianglei , Liang Ju , Zhou Dongju , Zhou Huiyun , Zhang Yanping , Liu Ning , Feng Shuxiao , Gu Guangna , Lu Jun , Song Nazi , Zhang Dongliang , Ma Junying 
Published: September 2016

AbstractThe acyloxy group of 2‐acyloxy‐2H‐azirines has been displaced by carboxylic acids to generate the corresponding 2‐acyloxy‐2H‐azirines by using potassium iodide as a promotor. This metal‐free method can be performed with a wide scope of substrates readily generating products in moderate to high yields. It also represents an example of nucleophilic substitution between esters and carboxylic acids under metal‐free reaction conditions for the first time.magnified image
Radical Stability as a Guideline in C–H Amination Reactions
Authors: Šakić Davor , Zipse Hendrik 
Published: September 2016

AbstractThe stability of N‐centered radicals and radical cations of potential relevance in C–H amidation reactions has been quantified using highly accurate theoretical methods. Combination with available C–H bond energies for substrate fragments allows for the prediction of reaction enthalpies in 1,5‐hydrogen atom transfer (HAT) steps frequently encountered in reactions such as the Hofmann–Löffler–Freytag (HLF) reaction. Protonation of N‐radicals is found to be essential in classical HLF reactions for thermochemically feasible HAT steps. The stability of neutral N‐radicals depends strongly on the type ofN‐substituent. Among the electron‐withdrawing substituents, the trifluoroacetyl (TFA) group is the least and the toluenesulfonyl (tosyl) group the most stabilizing. This implies that TFA‐aminyl radicals have the broadest and tosyl‐aminyl radicals the smallest window of synthetic applicability. In how far the intramolecular C–H amidation reactions compete with hydrogen abstraction from common organic solvents can be judged based on a comparison of reaction thermodynamics.magnified image
HF‐Free Boc Synthesis of Peptide Thioesters for Ligation and Cyclization
Authors: Raz Richard , Burlina Fabienne , Ismail Mohamed , Downward Julian , Li Jiejin , Smerdon Stephen J. , Quibell Martin , White Peter D. , Offer John 
Published: September 2016

AbstractWe have developed a convenient method for the direct synthesis of peptide thioesters, versatile intermediates for peptide ligation and cyclic peptide synthesis. The technology uses a modified Boc SPPS strategy that avoids the use of anhydrous HF. Boc in situ neutralization protocols are used in combination with Merrifield hydroxymethyl resin and TFA/TMSBr cleavage. Avoiding HF extends the scope of Boc SPPS to post‐translational modifications that are compatible with the milder cleavage conditions, demonstrated here with the synthesis of the phosphorylated protein CHK2. Peptide thioesters give easy, direct, access to cyclic peptides, illustrated by the synthesis of cyclorasin, a KRAS inhibitor.
Mixed Directing‐Group Strategy: Oxidative C−H/C−H Bond Arylation of Unactivated Arenes by Cobalt Catalysis
Authors: Du Cong , Li Peng‐Xiang , Zhu Xinju , Suo Jian‐Feng , Niu Jun‐Long , Song Mao‐Ping 
Published: September 2016

AbstractA mixed directing‐group strategy for inexpensive [Co(acac)3]‐catalyzed oxidative C−H/C−H bond arylation of unactivated arenes has been disclosed. This strategy enables the arylation of a wide range of benzamide and arylpyridines effectively to afford novel bifunctionalized biaryls, which are difficult to achieve by common synthetic routes. Two different pathways, namely, a single‐electron‐transmetalation process (8‐aminoquinoline‐directed) and a concerted metalation–deprotonation process (pyridine‐directed), were involved to activate two different inert aromatic C−H bonds. Moreover, the aryl radicals have been trapped by 2,6‐di‐tert‐butyl‐4‐methylphenol to form benzylated products. This unique strategy should be useful in the design of other arene C−H/C−H cross‐couplings as well.
A Conformationally Stable Contorted Hexabenzoovalene
Authors: Baumgärtner Kevin , Meza Chincha Ana Lucia , Dreuw Andreas , Rominger Frank , Mastalerz Michael 
Published: September 2016

AbstractContorted two‐dimensional aromatic molecules are fascinating synthetic targets because they are molecular “cutouts” of nonplanar graphene structures, fullerenes, or carbon nanotubes. In most cases, the curvature is introduced by the implementation of either five‐, seven‐, or eight‐membered rings into the fused aromatic plane. Curvature can also be generated for two‐dimensional systems consisting of six‐membered rings exclusively, by the introduction of cove or fjord regions. The synthesis of a polycyclic aromatic hydrocarbon (PAH) that contains two peripheral triptycene units and six tert‐butyl substituents is described. As a result of steric repulsion, the structure is highly contorted with two phenylene blades of the peripheral triptycene units oriented almost coplanar with respect to each other at a distance of 16 Å, as has been verified by single crystal X‐ray diffraction. The conformation is stable in solution even at a temperature of 150 °C. Additionally, internal tert‐butyl groups could be selectively removed, allowing a UV/Vis‐spectroscopic comparison of two structures with the same π‐system, but different degrees of contortion.
Asymmetric Organocatalysis: The Emerging Utility of α,β‐Unsaturated Acylammonium Salts
Authors: Vellalath Sreekumar , Romo Daniel 
Published: September 2016

AbstractAlthough acylammonium salts are well‐studied, chiral α,β‐unsaturated acylammonium salts have received much less attention. While these intermediates are convenient synthons, which are readily available from several commodity unsaturated acids and acid chlorides, and possess three reactive sites, their application in organic synthesis has been limited because of the lack of appropriate chiral Lewis bases for their generation. In recent years, the utility of chiral, unsaturated acylammonium salts has expanded considerably, thus demonstrating the unique reactivity of this intermediate leading to the development of a diverse array of catalytic, asymmetric transformations including organocascade processes. This Minireview highlights the recent and growing interest in these intermediates which might spark further research into their untapped potential for asymmetric organocascade catalysis. A cursory comparison is made to related unsaturated iminium and acylazolium intermediates.
Social Work Student Learning Experiences of Family Therapy: Improving Competency in Pedagogy Through Qualitative Research
Authors: Peterson Lance , Jones Ellie , Salscheider Kaitlin 
Published: September 2016

The purpose of this qualitative study is to evaluate graduate social work student experiences of pedagogy intended to improve competency in family therapy practice. Students from two classes (N = 37) completed open‐ended surveys assessing: perceptions of most helpful pedagogical practices; understanding of needed competencies; and perceived opportunities offered to them during their graduate training for learning about work with couples and families. Results, analysed using grounded theory methodology, revealed that students: (1) believed that experiential activities were especially critical for learning how to do clinical practice with couples and families; (2) understood important competencies related to professional development, therapeutic engagement with the family, and how to approach family practice; and (3) believed they were ‘somewhat prepared’ for practice. Implications include improving understanding of abstract skills in practice with couples and families, and emphasising relationship dynamics more in graduate social work education and training.
Post selection shrinkage estimation for high‐dimensional data analysis
Authors: Gao Xiaoli , Ahmed S. E. , Feng Yang 
Published: September 2016

In high‐dimensional data settings wherep ≫ n, many penalized regularization approaches were studied for simultaneous variable selection and estimation. However, with the existence of covariates with weak effect, many existing variable selection methods, including Lasso and its generations, cannot distinguish covariates with weak and no contribution. Thus, prediction based on a subset model of selected covariates only can be inefficient. In this paper, we propose a post selection shrinkage estimation strategy to improve the prediction performance of a selected subset model. Such a post selection shrinkage estimator (PSE) is data adaptive and constructed by shrinking a post selection weighted ridge estimator in the direction of a selected candidate subset. Under an asymptotic distributional quadratic risk criterion, its prediction performance is explored analytically. We show that the proposed post selection PSE performs better than the post selection weighted ridge estimator. More importantly, it improves the prediction performance of any candidate subset model selected from most existing Lasso‐type variable selection methods significantly. The relative performance of the post selection PSE is demonstrated by both simulation studies and real‐data analysis. Copyright © 2016 John Wiley & Sons, Ltd.
Simultaneous determination of epalrestat and puerarin in rat plasma by UHPLC–MS/MS: Application to their pharmacokinetic interaction study
Authors: Sun Hong , Bo Yunhai , Zhang Mingjie , Wu Xiao , Zhou Mingyang , Zhao Longshan , Xiong Zhili 
Published: September 2016

AbstractIn the present study, a simple, rapid and reliable ultrahigh‐performance liquid chromatography–tandem mass spectrometric (UHPLC–MS/MS) method was developed and validated to determine simultaneously epalrestat (EPA) and puerarin (PUE) in rat plasma for evaluation of the pharmacokinetic interaction of these two drugs. Both the analytes and glipizide (internal standard, IS) were extracted using a protein precipitation method. The separation was performed on a C18 reversed phase column using acetonitrile and 5 mmol/L ammonium acetate in water as the mobile phase with a gradient elution program. The analytes, including IS, were quantified with multiple reaction monitoring under negative ionization mode. The optimized mass transition ion pairs (m/z) were 318.1 → 274.0 for EPA, 415.1 → 266.9 for PUE and 444.2 → 166.9 for IS. The linear calibration curves for EPA and PUE were obtained in the concentration ranges of 10–4167 and 20–8333 ng/mL, respectively (r > 0.99). The current method was successfully applied for the pharmacokinetic interaction study in rats following administration of EPA and PUE alone or co‐administration (EPA 15 mg/kg, oral; PUE 30 mg/kg, intravenous). The results showed that the combination of EPA and PUE could increase t1/2 of EPA and reduce Tmax of EPA. These changes indicated that EPA and PUE might cause drug–drug interactions when co‐administrated.
Recombinant canstatin inhibits VEGF‐A‐induced lymphangiogenesis and metastasis in an oral squamous cell carcinoma SCC‐VII animal model
Authors: Hwang‐Bo Jeon , Park Jong‐Hwa , Bae Mun Gyeong , Chung In Sik 
Published: September 2016

AbstractWe describe the inhibitory effects of recombinant canstatin on tumor growth and lymphangiogenesis induced by an oral squamous cell carcinoma (SCC) using an orthotropic oral SCC animal model. Recombinant canstatin treatment decreased final tumor volumes and weights, as well as densities of blood and lymphatic vessels. Lung metastasis of oral SCC was significantly reduced in recombinant canstatin‐treated animals. Recombinant canstatin reduced vascular endothelial growth factor (VEGF)‐A expression in SCC‐VII cells treated with the hypoxia mimetic agent, CoCl2. VEGF‐A induced in vivo lymphatic vessel formation in a Matrigel plug, but this was remarkably reduced in a recombinant canstatin‐treated Matrigel. Recombinant canstatin suppressed the expression of vascular endothelial growth factor receptors (VEGFR)‐1 and ‐2 stimulated by VEGF‐A. Based on immunohistochemical analysis, recombinant canstatin significantly reduced the expression of VEGF‐A, VEGFR‐1, and ‐2 in SCC‐VII‐induced tumors. Recombinant canstatin did not affect the expression of VEGF‐C or VEGFR‐3. In addition, recombinant canstatin suppressed the VEGF‐A‐induced phosphorylation of VEGFR‐1 and ‐2. Our results indicate that recombinant canstatin exhibits antitumoral and antilymphangiogenic activities against oral SCC cells. Antilymphangiogenic signaling by recombinant canstatin is probably mediated by the suppression of the integrin αvβ3/VEGFR‐1 and/or ‐2 signaling induced by VEGF‐A. Our results also suggest that recombinant canstatin has a high potential to inhibit oral SCC‐induced tumors and lymphatic metastasis.
Structure and Substrate Recognition of the Bottromycin Maturation Enzyme BotP
Authors: Mann Greg , Huo Liujie , Adam Sebastian , Nardone Brunello , Vendome Jeremie , Westwood Nicholas James , Müller Rolf , Koehnke Jesko 
Published: September 2016

AbstractThe bottromycins are a family of highly modified peptide natural products, which display potent antimicrobial activity against Gram‐positive bacteria, including methicillin‐resistant Staphylococcus aureus. Bottromycins have recently been shown to be ribosomally synthesized and post‐translationally modified peptides (RiPPs). Unique amongst RiPPs, the precursor peptide BotA contains a C‐terminal “follower” sequence, rather than the canonical N‐terminal “leader” sequence. We report herein the structural and biochemical characterization of BotP, a leucyl‐aminopeptidase‐like enzyme from the bottromycin pathway. We demonstrate that BotP is responsible for the removal of the N‐terminal methionine from the precursor peptide. Determining the crystal structures of both apo BotP and BotP in complex with Mn2+ allowed us to model a BotP/substrate complex and to rationalize substrate recognition. Our data represent the first step towards targeted compound modification to unlock the full antibiotic potential of bottro‐ mycin.
A Second, Druggable Binding Site in UDP‐Galactopyranose Mutase from Mycobacterium tuberculosis?
Authors: Shi Yun , Colombo Cinzia , Kuttiyatveetil Jijin R. A. , Zalatar Nataliya , van Straaten Karin E. , Mohan Sankar , Sanders David A. R. , Pinto B. Mario 
Published: September 2016

AbstractUDP‐galactopyranose mutase (UGM), a key enzyme in the biosynthesis of mycobacterial cell walls, is a potential target for the treatment of tuberculosis. In this work, we investigate binding models of a non‐substrate‐like inhibitor, MS‐208, with M. tuberculosis UGM. Initial saturation transfer difference (STD) NMR experiments indicated a lack of direct competition between MS‐208 and the enzyme substrate, and subsequent kinetic assays showed mixed inhibition. We thus hypothesized that MS‐208 binds at an allosteric binding site (A‐site) instead of the enzyme active site (S‐site). A candidate A‐site was identified in a subsequent computational study, and the overall hypothesis was supported by ensuing mutagenesis studies of the A‐site. Further molecular dynamics studies led us to propose that MS‐208 inhibition occurs by preventing complete closure of an active site mobile loop that is necessary for productive substrate binding. The results suggest the presence of an A‐site with potential druggability, opening up new opportunities for the development of novel drug candidates against tuberculosis.