bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper‐Catalyzed Aerobic Oxidative Dehydrogenative Ring‐Opening Reaction of Glycine Esters with α′‐Angelicalactone: Approach to Construct α‐Amino‐γ‐Ketopimelates
Authors: Wu Rui , Li Jun , Wang Yajun , Quan Zhengjun , Su Yingpeng , Huo Congde 
Published: April 2019

AbstractA copper‐catalyzed aerobic oxidative dehydrogenative reaction of glycine derivatives with α′‐angelicalactone is achieved under mild and simple reaction conditions. This strategy can be applicable to a wide range of gylcine esters, including complex substrates derived from (+)‐dehydroisoandrosterone or menthol, thus enabling the oxidative dehydrogenative ring‐opening reaction for producing diverse functionalized α‐amino‐γ‐ketopimelate derivatives in an atom‐economic manner.magnified image
Transition Metal‐Catalyzed Synthesis of 3‐Coumaranone‐Containing NH‐Aziridines from 2H‐Azirines: Nickel(II) versus Gold(I)
Authors: Sakharov Pavel A. , Rostovskii Nikolai V. , Khlebnikov Alexander F. , Khoroshilova Olesya V. , Novikov Mikhail S. 
Published: April 2019

AbstractA catalytic nucleophilic addition reaction of 3‐hydroxybenzofuran‐2‐carboxylic acid derivatives to 2H‐azirines for the high‐yield synthesis of NH‐aziridines with a 3‐coumaranone substituent has been developed. The Ph3PAuNTf2‐catalyzed reaction is diastereoselective to give predominantly (RS,SR)‐isomer of aziridine in good yield. The Ni(hfacac)2‐catalyzed reaction affords aziridines in up to 98% yield and low or moderate diastereoselectivity, which in some cases is opposite to that observed for the gold(I)‐catalyzed reaction. The Ph3PAuNTf2 works well for sterically hindered azirines as well as benzofurans bearing electron‐withdrawing groups, whereas Ni(hfacac)2 is the catalyst of choice for the preparation of aziridines having diazoacetyl substituent. The latter compounds can serve as substrates for the synthesis of fused aziridines via Buchner ring expansion reaction.magnified image
Pyridine‐Based Organocatalysts for Regioselective syn‐1,2‐Silaboration of Terminal Alkynes and Allenes
Authors: Morimasa Yohei , Kabasawa Kosuke , Ohmura Toshimichi , Suginome Michinori 
Published: April 2019

AbstractAn organocatalytic silaboration of terminal alkynes and allenes was established using pyridine‐based catalysts. In the presence of 4‐cyanopyridine (1–2 mol%), alkyl propiolates underwent regio‐ and stereoselective addition of silylboronic esters in toluene at 135 °C to afford (Z)‐3‐boryl‐2‐silylacrylates in good yields. 2,6‐Dichloro‐4,4′‐bipyridine and 4‐(3,5‐dichlorophenyl)pyridine also exhibited high catalyst efficiency for the 1,2‐silaboration of ethyl propiolate, whereas 1,1‐silaboration was induced by P(n‐Bu)3, t‐BuOK, and ICy to afford ethyl 3‐boryl‐3‐silylacrylates as Z/E mixtures. The silaboration of ethynylbenzenes and terminal allenes was also catalyzed by 4‐cyanopyridine to afford (Z)‐β‐boryl‐α‐silylstyrenes and β‐borylallylsilanes in a regioselective manner.
Synthese, Eigenschaften und Anwendung von Tetrakis(pentafluorethyl)gallat, [Ga(C2F5)4]−
Authors: Niemann Mark , Neumann Beate , Stammler Hans‐Georg , Hoge Berthold 
Published: April 2019

AbstractSchwach koordinierende Anionen (WCA) sind sowohl aus akademischen Gründen als auch für technische Anwendungen von hohem Interesse. Tetrakis(pentafluorethyl)gallat, [Ga(C2F5)4]−, ein neues WCA, ist durch die Reaktion von [GaCl3(dmap)] (dmap=4‐Dimethylaminopyridin) mit LiC2F5 zugänglich. Das Anion [Ga(C2F5)4]− zeigte gegenüber Salzsäure oder wässriger Lithiumhydroxid‐Lösung keine Zersetzung. Verschiedene Salze von [Ga(C2F5)4]− wurden mit den Kationen [PPh4]+, [CPh3]+, [(O2H5)2(OH2)2]2+ und [Li(dec)2]+ (dec=Diethylcarbonat) synthetisiert. Die Thermolyse von [(O2H5)2(OH2)2][Ga(C2F5)4]2 führt zum Tris(pentafluorethyl)gallan‐Dihydrat, [Ga(C2F5)3(OH2)2]. Alle Produkte wurden durch NMR‐ und IR‐Spektroskopie, Massenspektrometrie, Röntgenkristallstrukturanalyse und mittels Elementaranalyse charakterisiert. Ergänzend wird ein Ausblick für die Anwendung von [Li(dec)2][Ga(C2F5)4] als Leitsalz in Lithium‐Ionen‐Batterien gegeben.
Regio‐ and Enantioselective Formal Hydroamination of Enamines for the Synthesis of 1,2‐Diamines
Authors: Yu Lu , Somfai Peter 
Published: April 2019

AbstractThe asymmetric formal hydroamination of enamines using a CuH catalyst is reported. The method provides a straightforward and efficient approach to the synthesis of chiral 1,2‐dialkyl amines in good yields with high levels of enantioselectivities for a broad range of substrates, and should have significant value for the preparation of molecules bearing a 1,2‐diamine motif.
Cooperative effect through different bridges in nickel catalysts for polymerization of ethylene
Authors: Khoshsefat Mostafa , Dechal Abbas , Ahmadjo Saeid , Mortazavi S. Mohammad M. , Zohuri Gholamhossein , Soares Joao B.P. 
Published: April 2019

A series of mononuclear (M1 and M2) and dinuclear (C1–C6) Ni α‐diimine catalysts activated by modified methylaluminoxane were used in polymerization of ethylene. Catalyst C2 bearing the optimum bulkiness showed the highest activity (1.6 × 106 g PE (mol Ni)−1 h−1) and the lowest short‐chain branching (32.5/1000 C) in comparison to the dinuclear and mononuclear analogues. Although the mononuclear catalysts M1 and M2 polymerized ethylene to a branched amorphous polymer, the dinuclear catalysts led to different branched semicrystalline polyethylenes. Homogeneity and heterogeneity in the microstructure of the polyethylene samples was observed. Different trends for each catalyst were assigned to syn and anti stereoisomers. In addition, thermal behavior of the samples in the successive self‐nucleation and annealing technique exhibited different orders and intensities from methylene sequences and lamellae thickness in respect of each stereoisomer behavior. Higher selectivity of hexyl branches obtained by catalyst C2 showed a cooperative effect between the centers. The results also revealed that for catalysts C5 and C6, selectivity of methyl branches led to very high endotherms and crystalline sequences with melting temperatures higher than that of 100% crystalline polyethylene indicating ethylene/propylene copolymer analogues. For catalysts C3 and C4, more vinyl end groups were a result of the long distance between the Ni centers. Kinetic profiles of polymerization along with a computational study of the precatalysts and catalysts demonstrated that there is a direct relation between rate constant, energy interval of catalyst and precatalyst, and interaction energy of Et···methyl cationic active center (Et···MCC or π–Comp.). Based on this, narrow energy interval (activation energy) of precatalyst and catalyst leads to fast and higher activation rate (catalyst M2), and strong interaction of ethylene and catalyst leads to high monomer uptake and productivity (catalyst C2). Moreover, theoretical parameters including electron affinity, Mulliken charge on Ni, chemical potential and hardness, and global electrophilicity showed optimum values for C2.
Fabrication of PEI‐grafted porous polymer foam for CO2 capture
Authors: Deng Jingqian , Liu Zuolong , Du Zhongjie , Zou Wei , Zhang Chen 
Published: April 2019

ABSTRACTA polymer foam material with both the open‐cell porous structure and the polyethylenemine (PEI)‐grafted inner face was constructed for CO2 capture. The porous poly(tert‐butyl acrylate) foam was first prepared via a concentrated emulsion polymerization, and then the carboxyl groups were introduced on the interface of porous polymer after the hydrolysis reaction. Subsequently, the surface of the foam was grafted with PEI, and finally the PEI‐grafted porous polymer foam designed as a CO2 capture material was obtained. The structures of the foams were characterized by infrared spectroscopy, EDS, and SEM. The CO2 adsorption properties were measured by adsorption/desorption cycles. As a result, the polymer foam contained a large number of amine groups (13.9 wt % N), and therefore possessed a high CO2 adsorption capacity (5.91 mmol g−1 at 40°C and 100 kPa). In addition, they also exhibited high CO2 adsorption rate, good selectivity for CO2‐N2 separation, and good stability according to CO2 cyclic adsorption/desorption test. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47844.
Microstructure of Vertebrae, Ribs, and Gastralia of Triassic Sauropterygians—New Insights into the Microanatomical Processes Involved in Aquatic Adaptations of Marine Reptiles
Authors: Klein Nicole , Canoville Aurore , Houssaye Alexandra 
Published: April 2019

ABSTRACTIsolated ribs and vertebrae of Middle Triassic sauropterygians are studied. The vertebrae have a well‐defined large cavity in their centra, which is a unique feature and is without any modern analogue. The articular facets of vertebrae are made of endochondral bone including calcified as well as uncalcified cartilage. Vertebrae are pachyosteosclerotic in the pachypleurosaurs Neusticosaurus and Serpianosaurus from the Alpine Triassic, and osteosclerotic in the placodont, in the medium‐sized Nothosaurus marchicus, and in the pachypleurosaur Anarosaurus. In large Nothosaurus specimens, the vertebrae are cavernous. The ribs of all sampled specimens are osteosclerotic, which resembles the microanatomy of long bones in all studied taxa. The proximal to medial part of ribs mainly consists of a compact periosteal cortex surrounding an inner endosteal territory. Toward the distal end of the ribs, the periosteal thickness decreases whereas the endosteal territory increases. Despite a shift from periosteal versus endosteal tissues, global rib compactness remains relatively constant. Osteosclerosis in ribs and vertebrae is reached by the same processes as in the long bones: by a relative increase in cortex thickness that is coupled by a reduction of the medullary cavity, by the persistence of calcified cartilage, and by an inhibition of remodeling although some resorption may occur but without complete redeposition of bone. Processes differ from those observed in Permian marine reptiles and some mosasaurines, where either extensive remodeling or inhibition of bone resorption leads to osteosclerosis. Besides differences regarding the microanatomy, all studied bones of a taxon are consistent in their bone tissue type. Anat Rec, 302:1770–1791, 2019. © 2019 American Association for Anatomy
Development of a simple method for simultaneous determination of tazarotene and betamethasone dipropionate and their metabolites using LC–MS method and its application to dermatopharmacokinetic study
Authors: Li Lingjun , Zhang Mengli , Ma Pengcheng , Qian Kun 
Published: April 2019

AbstractIn our study, a method for the determination for tazarotene and betamethasone dipropionate in human tissue‐engineered skin was established. Tazarotene gel, betamethasone dipropionate cream or a combination cream was administered to the skin. Then the skin was taken off at 0.25, 0.75, 1.75, 3, 5, 8, 12, 24, 36, 48 h time points after the residual drug was removed. The concentrations of tazarotene, betamethasone dipropionate and their major metabolites in skin were determined by LC–MS. Tazarotene and tazarotenic acid were detected in the concentration range of 2–200 μg/mL with an LLOQ of 2 μg/mL. Betamethasone dipropionate was detected in the concentration range 0.5–300 μg/mL with an LLOQ of 0.5 μg/mL, and betamethasone was detected at 2–200 μg/mL with an LLOQ of 2 μg/mL. The intra‐ and inter‐day precisions of the four analytes in the skin homogenate were all <15% (RSD, %). The results showed that tazarotene could be metabolized to tazarotenic acid and betamethasone dipropionate could be metabolized to betamethasone in tissue‐engineered skin. The results also revealed that this method was suitable for the simultaneous determination of tazarotene, betamethasone dipropionate and their metabolites in tissue‐engineered skin.
Quantitative Isotopomer Rates in Real‐Time Metabolism of Cells Determined by NMR Methods
Authors: Reed Michelle A. C. , Roberts Jennie , Gierth Peter , Kupče Ēriks , Günther Ulrich L. 
Published: April 2019

AbstractTracer‐based metabolism is becoming increasingly important for studying metabolic mechanisms in cells. NMR spectroscopy offers several approaches to measure label incorporation in metabolites, including 13C‐ and 1H‐detected spectra. The latter are generally more sensitive, but quantification depends on the proton–carbon 1JCH coupling constant, which varies significantly between different metabolites. It is therefore not possible to have one experiment optimised for all metabolites, and quantification of 1H‐edited spectra such as HSQCs requires precise knowledge of coupling constants. Increasing interest in tracer‐based and metabolic flux analysis requires robust analyses with reasonably small acquisition times. Herein, we compare 13C‐filtered and 13C‐edited methods for quantification and show the applicability of the methods for real‐time NMR spectroscopy of cancer‐cell metabolism, in which label incorporations are subject to constant flux. We find an approach using a double filter to be most suitable and sufficiently robust to reliably obtain 13C incorporations from difference spectra. This is demonstrated for JJN3 multiple myeloma cells processing glucose over 24 h. The proposed method is equally well suited for calculating the level of label incorporation in labelled cell extracts in the context of metabolic flux analysis.
Two‐year safety evaluation of a biodegradable polymer sirolimus‐eluting stent with increased drug elution and polymer absorption kinetics in complex patient and lesion cohort
Authors: Jia Sida , Guan Changdong , Yuan Jinqing , Cao Xuebin , Qin Lei , Li Yi , Li Zhanquan , Nie Shaoping , Hou Shuang , Zhang Min , Brouwer Marc , Suryapranata Harry , Xu Bo , Gao Runlin 
Published: April 2019

AbstractObjectivesThe aim of the present report was to compare 2‐year safety outcomes of two biodegradable polymer (BP) sirolimus‐eluting stents (SESs) with different drug eluting and polymer absorption kinetics in a subgroup of complex patients and lesions.BackgroundThe previously published PANDA III study showed the BuMA BP SES, with faster drug elution and polymer absorption, was non‐inferior to the Excel SES in target lesion failure (TLF).MethodsIn PANDA III trial, patients who fulfilled one or more of the following criteria were included: Small vessel disease (reference vessel diameter ≤ 2.5 mm); long lesion (lesion length ≥ 20 mm); chronic total occlusion lesion; and diabetic patients.ResultsAmong 2,348 patients randomly assigned to treatment with BuMA (n = 1,174) or Excel SES (n = 1,174) in the PANDA III study, 858 in the BuMA group and 855 in the Excel group satisfied the inclusion criteria. At 2‐year follow‐up, the incidence of definite/probable stent thrombosis (ST) was significantly lower with BuMA SES as compared with Excel SES (0.7% vs. 1.9%, p = 0.03). This difference was mainly caused by decreased subacute stent thrombosis rate (0% vs. 0.6%, p = 0.03). In patients who did not fulfill the complex patient and lesion criteria, there were no between‐group difference in ST (0.7% vs. 0%, p = 0.50). Myocardial infarction and TLF rates were similar (5.7% vs. 6.0%, p = 0.79 and 8.8% vs. 7.5%, p = 0.34, respectively), whereas patient‐oriented composite endpoint was higher with BuMA SES mainly due to high risk of revascularization (15.6% vs. 11.4%, p = 0.01; 8.4% vs. 4.6%, p < 0.01).ConclusionsTwo‐year subgroup analysis of the all‐comer PANDA III trial revealed the increased safety benefit of the BuMA SES is more prominently seen in complex patient and lesion population.Clinical Trial
ClinicalTrial.gov, Identifier—NCT02017275.
Cyclometalated AuIII Complexes for Cysteine Arylation in Zinc Finger Protein Domains: towards Controlled Reductive Elimination
Authors: Wenzel Margot N. , Bonsignore Riccardo , Thomas Sophie R. , Bourissou Didier , Barone Giampaolo , Casini Angela 
Published: April 2019

AbstractWith the aim of exploiting the use of organometallic species for the efficient modification of proteins through C‐atom transfer, the gold‐mediated cysteine arylation through a reductive elimination process occurring from the reaction of cyclometalated AuIII C^N complexes with a zinc finger peptide (Cys2His2 type) is here reported. Among the four selected AuIII cyclometalated compounds, the [Au(CCON)Cl2] complex featuring the 2‐benzoylpyridine (CCON) scaffold was identified as the most prone to reductive elimination and Cys arylation in buffered aqueous solution (pH 7.4) at 37 °C by high‐resolution LC electrospray ionization mass spectrometry. DFT and quantum mechanics/molecular mechanics (QM/MM) studies permitted to propose a mechanism for the title reaction that is in line with the experimental results. Overall, the results provide new insights into the reactivity of cytotoxic organogold compounds with biologically important zinc finger domains and identify initial structure–activity relationships to enable AuIII‐catalyzed reductive elimination in aqueous media.
Long‐term outcomes in Japanese nonagenarians undergoing transcatheter aortic valve implantation: A multi‐center analysis
Authors: Yokoyama Hiroaki , Tobaru Tetsuya , Muto Yuki , Hagiya Kenichi , Higuchi Ryosuke , Saji Mike , Takamisawa Itaru , Shimizu Jun , Takanashi Shuichiro , Takayama Morimasa , Tomita Hirofumi , Tamura Harutoshi , Doi Shinichiro , Okazaki Shinya , Isobe Mitsuaki 
Published: April 2019

AbstractBackground and HypothesisJapan is an aging society, and the number of nonagenarians with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI) is increasing, but their outcomes have not been determined fully.MethodsWe prospectively enrolled 767 consecutive patients who underwent TAVI in three Japanese institutions. Clinical characteristics and outcomes of nonagenarians (n = 94) were evaluated and compared with those of patients aged <90 years (n = 673).ResultsPrevalence of New York Heart Association (NYHA) class III/IV was not different between the two groups. Preoperative risk scores were significantly higher in nonagenarians compared with those in non‐nonagenarians, whereas the Clinical Frailty Scale was not different. Thirty‐day mortality tended to be higher (P = .06) and major vascular complication was significantly higher in nonagenarians than in non‐nonagenarians (P < .05), but 3‐year mortality was equivalent between the two groups. Even after adjustment for covariates, female sex (hazard ratio, 0.41; 95% confidence interval: 0.25‐0.67), body mass index (0.87, 0.80‐0.94), and NYHA class III/IV (1.84, 1.06‐3.29) were associated with all‐cause mortality. Age ≥ 90 years was not associated with all‐cause mortality.ConclusionsTAVI could be undertaken safely and effectively in nonagenarians, who had acceptable long‐term results compared with those for younger patients, although careful attention should be paid to major vascular complication.
Static malware clustering using enhanced deep embedding method
Authors: Ng Chee Keong , Jiang Frank , Zhang Leo Yu , Zhou Wanlei 
Published: April 2019

SummaryMalware refers to any software, programs, or files that are intentionally utilised to compromise the system and cause unexpected losses to end‐users such as economical losses or privacy breaches. The rapid growth of malware makes it impossible to keep up with its progress merely via human interventions or manual analysis. One of the challenges for the human‐oriented approaches is they will cause backlog and inability to keep up with the development traces of the malware. Hence, an efficient method is needed urgently to analyse effectively and identify accurately the malware in their domain. Malware clustering has been extensively studied in the machine learning area with regards to distance functions, grouping algorithm and cluster validation. A large number of research studies have been done via behavioral analysis for clustering to achieve high performance of malware detections. However, there is a trade‐off for better detection performance between behaviorial approaches and high computational forces. Up to date, little work focuses on the deep learning representations for malware clustering. Therefore, in this paper, we propose an enhanced deep embedded clustering method to facilitate an effective and efficient malware clustering process. The new method takes advantage of linear dimensionality reduction and a customised deep neural network to learn malware representations in an orthogonal space and performs cluster assignments. Our experimental results demonstrate that the proposed clustering model outperforms the traditional K‐means method with regards to the enhanced features using various auto‐encoder, pre‐trained weight and principle component analysis (PCA).
Fast and scalable algorithm for product large data on multicore system
Authors: Bahig Hazem M. , Bahig Hatem M. , Fathy Khaled A. 
Published: April 2019

SummaryThe problem of designing efficient parallel algorithms to calculate the product of n numbers when the multipliers are large is a fundamental problem in many applications of computer science such as cryptography. In this work, we present a new parallel algorithm on exclusive read shared memory model. The performance of the introduced algorithm is measured based on three factors, namely, (1) the number of cores, (2) the size of the array, and (3) the size of the multiplier. The experimental study on a multi core system reveals that the introduced algorithm is faster than the best‐known optimal parallel algorithm. The improvement of the proposed algorithm in processing time compared to the best known parallel algorithm is 80% when the size of the array was 220 and the sizes of the multiplier were 1024, 2048, and 4096 bits. Moreover, our algorithm is a highly scalable parallel algorithm compared with the best‐known optimal parallel algorithm.
Superhalogens as Building Blocks of Super Lewis Acids
Authors: Reddy G. Naaresh , Parida Rakesh , Jena Puru , Jana Madhurima , Giri Santanab 
Published: April 2019

AbstractLewis acids play an important role in synthetic chemistry. Using first‐principle calculations on some newly designed molecules containing boron and organic heterocyclic superhalogen ligands, we show that the acid strength depends on the charge of the central atom as well as on the ligands attached to it. In particular, the strength of the Lewis acid increases with increasing electron withdrawing power of the ligand. With this insight, we highlight the importance of superhalogen‐based ligands in the design of strong Lewis acids. Calculated fluoride ion affinity (FIA) values of B[C2BNO(CN)3]3 and B[C2BNS(CN)3]3 show that these are super Lewis acids.
Ecological insights from environmental disturbances in mesophotic coral ecosystems
Authors: Pinheiro Hudson T. , Eyal Gal , Shepherd Bart , Rocha Luiz A. 
Published: April 2019

AbstractMesophotic coral ecosystems (MCEs) have historically been considered more stable than shallow reefs and thus suggested to provide refuge to coral reef communities against natural and anthropogenic impacts. Despite this assumption, a growing body of literature has shown that deep reefs are not immune to natural disturbance. Here, based on our in situ observations, we propose that disturbance may actually represent an important mechanism for maintaining biodiversity in MCEs, as is the case for shallow reefs. Our observations suggest that disturbances can provide microhabitat and space necessary for the recruitment and occurrence of different species, increasing overall diversity. Since bioerosion rates are lower at depth, and most well‐developed coral reefs on MCEs are formed by dense aggregations of a single or a few species, intermediate levels of disturbance could represent a critical driver of community structure balancing. Therefore, instead of long‐term stability, intermediate disturbances should be expected on MCEs. However, high frequency and intensity of natural disturbances, or their association with anthropogenic stressors, might have stronger negative impacts on MCEs than on shallower reefs due to slower coral growth and calcification rates.