bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Access to N‐Unprotected α‐ and/or β‐Tetrasubstituted Amino Acid Esters via Direct Catalytic Mannich‐Type Reactions Using N‐Unprotected Trifluoromethyl Ketimines
Authors: Sawa Masanao , Morisaki Kazuhiro , Kondo Yuta , Morimoto Hiroyuki , Ohshima Takashi 
Published: September 2017

AbstractDirect catalytic C−C bond‐forming addition to N‐unprotected ketimines is an efficient and straightforward method of synthesizing N‐unprotected tetrasubstituted amines that eliminates prior protection/deprotection steps and allows facile transformation of the products. Despite its advantages, however, N‐unprotected ketimines have difficulties in C−C bond‐forming reactions, and only a limited number of reactions and substrates are reported compared with their N‐protected counterparts. Herein we report that N‐unprotected trifluoromethyl ketimines are effective for C−C bond‐forming reactions using Mannich‐type reactions as a model case. We demonstrate that Lewis acid catalysis was effective for promoting reactions with various N‐unprotected trifluoromethyl ketimines, and thiourea organocatalysis was effective for promoting highly enantioselective reactions with various carbonyl nucleophiles, providing direct access to various N‐unprotected α‐ and/or β‐tetrasubstituted amino acid esters. Furthermore, direct construction of vicinal tetrasubstituted chiral carbon stereocenters was achieved for the first time in a highly enantio‐ and diastereoselective manner. These results demonstrate the potential of N‐unprotected ketimines as substrates applicable to many other addition reactions.
Environmental Gas Sensing with Cavitands
Authors: Pinalli Roberta , Pedrini Alessandro , Dalcanale Enrico 
Published: September 2017

AbstractEnvironmental gas sensing needs stringent sensor requirements in terms of sensitivity, selectivity and ruggedness. One of the major issues to be addressed is combining in a single device the conflicting requirements of molecular‐level selectivity and low‐ppb sensitivity. The exploitation of synthetic molecular receptors as sensing materials is particularly attractive to address the selectivity issue, to single out the desired analytes in the presence of overwhelming amounts of interferents. This minireview summarizes the strategies in environmental gas and vapor sensing using molecular receptors as selective hosts for specific analytes, with the main focus on cavitands. In particular, we highlight the use of these macrocycles as selective preconcentrator units to be integrated into portable devices for environmental monitoring. Depending on the class of analytes to be detected, the molecular recognition properties of cavitands can be manipulated through the proper choice of the bridging groups at the upper rim, and their transducer integration can be implemented through the manifold functionalization options at the lower rim.
Magnetic γ′‐Fe4N/Fe3C, χ‐Fe5C2, and θ‐Fe3C by a Simple Route for Application as Electrochemical Catalysts
Authors: Lei Xiang , Ye Zhantong , Zhao Nan , Lei Feifei , Yang Hua 
Published: September 2017

AbstractA new and simple method to fabricate magnetic Fe4N/Fe3C samples is reported. Meanwhile, pure phase iron carbides (θ‐Fe3C and χ‐Fe5C2) were obtained by controlling experimental conditions. The structures, magnetic properties, and morphology of the samples were investigated according to the generalized analysis of X‐ray diffraction, X‐ray photoelectron spectroscopy, as well as transmission electron microscopy and vibrating sample magnetometry. The magnetic properties measurement revealed the remarkable magnetic properties of the samples at 2 and 300 K. The application of the prepared samples as catalysts for oxygen evolution reaction was also investigated in alkaline solution. This simple and convenient route provides a new path to fabricate other metal nitrides and carbides.
An Efficient Method for the Synthesis of Boratrane Complexes of Late Transition Metals
Authors: Saha Koushik , Ramalakshmi Rongala , Borthakur Rosmita , Gomosta Suman , Pathak Kriti , Dorcet Vincent , Roisnel Thierry , Halet Jean‐François , Ghosh Sundargopal 
Published: September 2017

AbstractIn a quest for efficient precursors for the synthesis of boratrane complexes of late transition metals, we have developed a useful synthetic method using [L′M(μ‐Cl)Clx]2 as precursors (L′=η6‐p‐cymene, M=Ru, x=1; L′=COD, M=Rh, x=0 and L′=Cp*, M=Ir or Rh, x=1; COD=1,5‐cyclooctadiene, Cp*=η5‐C5Me5). For example, treatment of Na[(H3B)bbza] or Na[(H2B)mp2] (bbza=bis(benzothiazol‐2‐yl)amine; mp=2‐mercaptopyridyl) with [L′M(μ‐Cl)Clx]2 yielded [(η6‐p‐cymene)RuBH{(NCSC6H4)(NR)}2] (2; R=NCSC6H4), [{N(NCSC6H4)2}RhBH{(NCSC6H4)(NR)}2] (3; R=NCS‐C6H4), [(η6‐p‐cymene)RuBH(L)2] (5; L=C5H4NS), and [Cp*MBH(L)2] (6 and 7; L=C5H4NS, M=Ir or Rh). In order to delineate the significance of the ligands, we studied the reactivity of [(COD)Rh(μ‐Cl)]2 with Na[(H3B)bbza], which led to the formation of the isomeric agostic complexes [(η4‐COD)Rh(μ‐H)BHRh(C14H8N3S2)3], 4 a and 4 b, in parallel to the formation of 16‐electron square‐pyramidal rhodaboratrane complex 3. Compounds 4 a and 4 b show two different geometries, in which the Rh−B bonds are shorter than in the reported Rh agostic complexes. The new compounds have been characterized in solution by various spectroscopic analyses, and their structural arrangements have been unequivocally established by crystallographic analyses. DFT calculations provide useful insights regarding the stability of these metallaboratrane complexes as well as their M→B bonding interactions.
Thieno‐Fused Subporphyrazines: A New Class of Light Harvesters
Authors: Gotfredsen Henrik , Storm Freja Eilsø , Muñoz Alberto Viñas , Santella Marco , Kadziola Anders , Hammerich Ole , Mikkelsen Kurt V. , Nielsen Mogens Brøndsted 
Published: September 2017

AbstractBoron subphthalocyanines comprised of three isoindole units bridged by aza‐linkages are attractive light harvesters on account of their intense low‐energy absorptions. Herein, we present a class of related compounds, in which one or two isoindole units are substituted for thieno[3,4‐c]pyrrole units – thieno‐fused subporphyrazines. Such changes have remarkable consequences for the optical properties, as was revealed by combined experimental and theoretical studies. Thus, we find that the lowest‐energy absorptions cover a much broader region with a significantly redshifted end‐absorption and without compromising the absorption intensities. Thieno‐fused subporphyrazines also underwent more readily oxidation and reduction, indicating an increased HOMO energy and decreased LUMO energy. In addition, they were found to readily co‐crystallize with Buckminsterfullerene, C60. Altogether, these findings render this new class of chromophores attractive candidates for light‐harvesting applications.
(R‐X‐R)4‐Motif Peptides Containing Conformationally Constrained Cyclohexane‐Derived Spacers: Effect on Cellular Uptake
Authors: Bhosle Govind S. , Fernandes Moneesha 
Published: September 2017

AbstractArginine‐rich peptides having the (R‐X‐R)n motif are among the most effective cell‐penetrating peptides (CPPs). Herein we report a several‐fold increase in the efficacy of such CPPs if the linear flexible spacer (‐X‐) in the (R‐X‐R) motif is replaced by constrained cyclic 1,4‐substituted‐cyclohexane‐derived spacers. Internalization of these oligomers in mammalian cell lines was found to be an energy‐dependent process. Incorporation of these constrained, non‐proteinogenic amino acid spacers in the CPPs is shown to enhance their proteolytic stability.
Serum antibodies open the door to prediction and prognostication in human papillomavirus–related head and neck cancer
Authors: Sacco Assuntina G. , Cohen Ezra E. 
Published: September 2017

In human papillomavirus–related head and neck cancer, who can be de‐escalated, and who requires more intensive therapy to achieve similar oncologic efficacy? The answers may very well be circulating in saliva and serum.See also pages 4382‐90.
Decline in the acute insulin response in relationship to plasma glucose concentrations
Authors: Heinitz Sascha , Piaggi Paolo , Bogardus Clifton , Krakoff Jonathan 
Published: September 2017

AbstractBackgroundTo investigate (1) whether the decline in acute insulin response (AIR) precedes or coincides with defined glucose regulation categories and whether acute insulin response decline varies by race and adiposity, (2) linearity of the relationship between acute insulin response and increasing plasma glucose concentrations, (3) longitudinal changes in acute insulin response accounting for changes in insulin action across categories of glucose tolerance.MethodsClinical cross‐sectional and longitudinal study of nondiabetic subjects. Inpatient assessment of oral glucose tolerance (2‐h PG, fasting PG), and acute insulin response (intravenous glucose tolerance test) in 326 and 84 Native Americans of full and ≤6/8th Southwestern heritage, respectively, and 115 Whites. Linearity of acute insulin response vs plasma glucose concentrations investigated using spline analyses. Follow‐up (average = 2.07 years) glucose tolerance, acute insulin response, and insulin action (hyperinsulinemic‐euglycemic clamp) assessed in 230 full Native Americans.ResultsIn certain groups, the relationship between acute insulin response and increasing plasma glucose levels was non‐linear. In all groups, acute insulin response decline preceded the cut‐offs for traditional glucose regulation categories, although the timing with respect to increasing plasma glucose varied by race and adiposity. Longitudinal data indicated that improvement in insulin action is the key factor to preserve insulin secretion, underlying the reversion of glucose tolerance in prediabetic individuals.ConclusionsWith worsening insulin action, the decline in insulin secretion occurred prior to current diagnostic guidelines for impaired glucose regulation. However, the relationship between acute insulin response and increasing plasma glucose varies and was not always non‐linear. Understanding the dynamics of this relationship may determine when to initiate preventive pharmacotherapy directed at the preservation of β‐cell failure.
Invertebrate community response to coarse woody debris removal for bioenergy production from intensively managed forests
Authors: Grodsky Steven M. , Moorman Christopher E. , Fritts Sarah R. , Campbell Joshua W. , Sorenson Clyde E. , Bertone Matthew A. , Castleberry Steven B. , Wigley T. Bently 
Published: September 2017

AbstractIncreased market viability of harvest residues as forest bioenergy feedstock may escalate removal of coarse woody debris in managed forests. Meanwhile, many forest invertebrates use coarse woody debris for cover, food, and reproduction. Few studies have explicitly addressed effects of operational‐scale woody biomass harvesting on invertebrates following clearcutting. Therefore, we measured invertebrate community response to large‐scale harvest residue removal and micro‐site manipulations of harvest residue availability in recently clearcut, intensively managed loblolly pine (Pinus taeda) forests in North Carolina (NC;n = 4) and Georgia (GA;n = 4),USA. We captured 39,794 surface‐active invertebrates representing 171 taxonomic groups using pitfall traps situated among micro‐site locations (i.e., purposefully retained piles of hardwood stems and piles of conifer stems and areas without coarse woody debris inNC; windrows and no windrows inGA). Micro‐site locations were located within six, large‐scale treatments (7.16–14.3 ha) in clearcuts. Large‐scale treatments represented intensive harvest residue removal, 15% and 30% harvest residue retention, and no harvest residue removal. InNC, ground beetles (Coleoptera: Carabidae) and crickets (Orthoptera: Gryllidae) were three times more abundant in treatments with no harvest residue removal than those with the most intensive harvest residue removal and were reduced in treatments that retained 15% or 30% of harvest residues, although not significantly. Invertebrate taxa richness was greater at micro‐site locations with retained hardwood and pine (Pinusspp.) harvest residues than those with minimal amounts of coarse woody debris. In both states, relative abundances of several invertebrate taxa, including cave crickets (Orthoptera: Rhaphidophoridae), fungus gnats (Diptera: Mycetophilidae and Sciaridae), millipedes (Diplopoda), and wood roaches (Blattodea: Ectobiidae), were greater at micro‐site locations with retained harvest residues than those with minimal coarse woody debris. Intensified woody biomass harvesting without retention of ≥15% of harvest residue volume may reduce invertebrate taxa richness and abundances of some key invertebrate taxa in regenerating stands. Further, harvest residue management during and after woody biomass harvesting may be an important consideration for maintaining invertebrate diversity and conserving invertebrates that are influential in the maintenance of ecosystem function and integrity in young forests.
Selection of reference genes for qRT‐PCR and expression analysis of high‐altitude‐related genes in grassland caterpillars (Lepidoptera: Erebidae: Gynaephora) along an altitude gradient
Authors: Zhang Li , Zhang Qi‐Lin , Wang Xiao‐Tong , Yang Xing‐Zhuo , Li Xiao‐Peng , Yuan Ming‐Long 
Published: September 2017

AbstractChanges in gene expression patterns can reflect the adaptation of organisms to divergent environments. Quantitative real‐time PCR (qRT‐PCR) is an important tool for ecological adaptation studies at the gene expression level. The quality of the results of qRT‐PCR analysis largely depends on the availability of reliable reference genes (RGs). To date, reliable RGs have not been determined for adaptive evolution studies in insects using a standard approach. Here, we evaluated the reliability of 17 candidate RGs for five Gynaephora populations inhabiting various altitudes of the Tibetan Plateau (TP) using four independent (geNorm, NormFinder, BestKeeper, and the deltaCt method) and one comprehensive (RefFinder) algorithms. Our results showed that EF1‐α, RPS15, and RPS13 were the top three most suitable RGs, and a combination of these three RGs was the most optimal for normalization. Conversely, RPS2, ACT, and RPL27 were the most unstable RGs. The expression profiles of two target genes (HSP70 and HSP90) were used to confirm the reliability of the chosen RGs. Additionally, the expression patterns of four other genes (GPI, HIF1A, HSP20, and USP) associated with adaptation to extreme environments were assessed to explore the adaptive mechanisms of TP Gynaephora species to divergent environments. Each of these six target genes showed discrepant expression patterns among the five populations, suggesting that the observed expression differences may be associated with the local adaptation of Gynaephora to divergent altitudinal environments. This study is a useful resource for studying the adaptive evolution of TP Gynaephora to divergent environments using qRT‐PCR, and it also acts as a guide for selecting suitable RGs for ecological and evolutionary studies in insects.
A comprehensive population‐based characterization of heart failure with mid‐range ejection fraction
Authors: Koh Angela S. , Tay Wan Ting , Teng Tiew Hwa Katherine , Vedin Ola , Benson Lina , Dahlstrom Ulf , Savarese Gianluigi , Lam Carolyn S.P. , Lund Lars H. 
Published: September 2017

AimsClinical features and outcomes in the novel phenotype heart failure with mid‐range ejection fraction [HFmrEF, ejection fraction (EF) 40–49%] were compared with heart failure with reduced EF (HFrEF, EF <40%) and preserved EF (HFpEF, EF ≥50%).Methods and resultsIn the Swedish Heart Failure Registry, we assessed the association between baseline characteristics and EF group using multivariable logistic regressions, and the association between EF group and all‐cause mortality using multivariable Cox regressions. Of 42 061 patients, 56% had HFrEF, 21% had HFmrEF, and 23% had HFpEF. Characteristics were continuous for age (72 ± 12 vs. 74 ± 12 vs. 77 ± 11 years), proportion of women (29% vs. 39% vs. 55%), and 13 other characteristics. Coronary artery disease (CAD) was distinctly more common in HFrEF (54%) and HFmrEF (53%) vs. HFpEF (42%); adjusted odds ratio for CAD in HFmrEF vs. HFpEF was 1.52 [95% confidence interval (CI) 1.41–1.63]. For six additional characteristics HFmrEF resembled HFrEF, for seven characteristics HFmrEF resembled HFpEF, and for 10 characteristics there was no pattern. The adjusted hazard ratio (HR) for mortality in HFrEF vs. HFpEF was 1.35 (95% CI 1.14–1.60) at 30 days, 1.26 (95% CI 1.17–1.35) at 1 year, and 1.20 (95% CI 1.14–1.26) at 3 years. In contrast, HFmrEF and HFpEF had a similar prognosis (HR 1.06, 95% CI 0.86–1.30 at 30 days; HR 1.08, 95% CI 1.00–1.18 at 1 year; and HR 1.06, 95% CI 1.00–1.12 at 3 years). Three‐year mortality was higher in HFmrEF than in HFpEF in the presence of CAD (HR 1.11, 95% CI 1.02–1.21), but not in the absence of CAD (HR 1.02, 95% CI 0.94–1.12; P for interaction <0.001).ConclusionsHFmrEF was an intermediate phenotype, except that CAD was more common in HFmrEF and HFrEF vs. HFpEF, crude all‐cause mortality was lower in HFmrEF and HFrEF, adjusted all‐cause mortality was lower in HFmrEF and HFpEF, and CAD portended a higher adjusted risk of death in HFmrEF and HFrEF.
Resting and exercise haemodynamics in relation to six‐minute walk test in patients with heart failure and preserved ejection fraction
Authors: Wolsk Emil , Kaye David , Borlaug Barry A. , Burkhoff Daniel , Kitzman Dalane W. , Komtebedde Jan , Lam Carolyn S.P. , Ponikowski Piotr , Shah Sanjiv J. , Gustafsson Finn 
Published: September 2017

AimsPatients with heart failure and preserved ejection fraction (HFpEF) are characterized by functional impairment and an abnormal haemodynamic response to exercise. The six‐minute walk test (6MWT) serves as a standardized test for functional capacity quantification in heart failure patients, and is associated with cardiovascular outcomes. However, as the association between 6MWT and haemodynamic parameters during rest and exercise in HFpEF patients is unknown, we sought to elucidate this relationship.Methods and resultsOverall, 64 patients enrolled in the REDUCE LAP‐HF trial completed a 6MWT at baseline. Univariate and multivariable linear regression models were used to assess the associations between 6MWT and measured or derived haemodynamic variables at baseline, during light/moderate exercise (20 W), and at peak supine exercise. The average 6MWT distance was 318 ± 106 m. At rest, in a multivariable model, only pulmonary capillary wedge pressure (PCWP) was significantly associated with 6MWT [coefficient: –5.4, 95% confidence interval (CI) –10.4, –0.5, P = 0.033]. During light/moderate exercise, mean pulmonary artery pressure was associated with 6MWT in a multivariable model (coefficient: –3.5, 95% CI –6.8, –0.3, P = 0.033). During peak exercise, central venous pressure, cardiac index (CI), and PCWP/CI correlated with 6MWT; however, workload corrected PCWP was the only variable independently associated with 6MWT (coefficient: –0.8, 95% CI –1.3, –0.4, P < 0.001). The variance in 6MWT was modestly explained by measured or derived haemodynamic variables at rest or at any stage of exercise (r2 = 7–17%).ConclusionWorkload corrected PCWP correlated best with 6MWT performance in HFpEF patients. Baseline haemodynamic variables were modestly correlated with 6MWT, suggesting that 6MWT performance in HFpEF patients may be significantly influenced by extra‐cardiac factors.
Prognostic value of circulating microRNAs on heart failure‐related morbidity and mortality in two large diverse cohorts of general heart failure patients
Authors: Bayés‐Genis Antoni , Lanfear David E. , de Ronde Maurice W.J. , Lupón Josep , Leenders Joost J. , Liu Zhen , Zuithoff Nicolaas P.A. , Eijkemans Marinus J.C. , Zamora Elisabet , De Antonio Marta , Zwinderman Aeilko H. , Pinto‐Sietsma Sara‐Joan , Pinto Yigal M. 
Published: September 2017

AimsSmall studies suggested circulating microRNAs (miRNAs) as biomarkers for heart failure (HF). However, standardized approaches and quality assessment for measuring circulating miRNAs are not uniformly established, and most studies have been small, so that results are inconsistent. We used a standardized data handling protocol, optimized for circulating miRNA qPCRs to remove noise and used it to assess which circulating miRNAs robustly add prognostic information in patients with HF.Methods and resultsWe measured 12 miRNAs in two independent cohorts totalling 2203 subjects. Cohort I (Barcelona) comprised 834 chronic HF patients. Cohort II (Detroit) comprised 1369 chronic HF patients. Each sample was measured in duplicate, and normalized to a very abundant and stable miRNA (miR‐486‐5p). We used a multistep algorithm to distinguish false amplification signals and thus classify each miRNA measurement as ‘valid’, ‘undetectable’ or ‘invalid’. Higher levels of miR‐1254 and miR‐1306‐5p were significantly associated with risk of the combined endpoint of all‐cause mortality and HF hospitalization in both cohorts, with hazard ratios ranging from 1.11 to 1.21 per log increase (P‐values 0.004 to 0.009). However, adding these miRNAs to established predictors (age, sex, haemoglobin, renal function, and NT‐proBNP) did not further augment the c‐statistic beyond 0.69 (cohort I) or 0.70 (cohort II).ConclusionWe used a stringent quality assessment for miRNA testing, and were able to replicate the association of miR‐1254 and miR‐1306‐5p with risk of death and HF hospitalization in HF patients of two independent cohorts. However, these two circulating miRNAs failed to improve prognostication over established predictors.