bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioselective Hydrogenation of Tetrasubstituted α,β‐Unsaturated Carboxylic Acids Enabled by Cobalt(II) Catalysis: Scope and Mechanistic Insights
Authors: Du Xiaoyong , Xiao Ye , Yang Yuhong , Duan Ya‐Nan , Li Fangfang , Hu Qi , Chung Lung Wa , Chen Gen‐Qiang , Zhang Xumu 
Published: February 2021

AbstractChiral carboxylic acids are important compounds because of their prevalence in pharmaceuticals, natural products and agrochemicals. Asymmetric hydrogenation of α,β‐unsaturated carboxylic acids has been widely recognized as one of the most efficient synthetic approaches to afford such compounds. Although related asymmetric hydrogenation of di‐ and trisubstituted unsaturated acids with noble metals is well established, asymmetric hydrogenation of challenging tetrasubstituted α,β‐unsaturated carboxylic acids is rarely reported. We demonstrate enantioselective hydrogenation of cyclic and acyclic tetrasubstituted α,β‐unsaturated carboxylic acids via cobalt(II) catalysis. This protocol showed broad substrate scope and gave chiral carboxylic acids in good yields with excellent enantiocontrol (up to 98 % yield and 99 % ee). Combined experimental and computational mechanistic studies support a CoII catalytic cycle involving migratory insertion and σ‐bond metathesis processes. DFT calculations reveal that enantioselectivity may originate from the steric effect between the phenyl groups of the ligand and the substrate.
Potential‐Induced Spin Changes in Fe/N/C Electrocatalysts Assessed by In Situ X‐ray Emission Spectroscopy
Authors: Saveleva Viktoriia A. , Ebner Kathrin , Ni Lingmei , Smolentsev Grigory , Klose Daniel , Zitolo Andrea , Marelli Elena , Li Jingkun , Medarde Marisa , Safonova Olga V. , Nachtegaal Maarten , Jaouen Frédéric , Kramm Ulrike I. , Schmidt Thomas J. , Herranz Juan 
Published: February 2021

AbstractThe commercial success of the electrochemical energy conversion technologies required for the decarbonization of the energy sector requires the replacement of the noble metal‐based electrocatalysts currently used in (co‐)electrolyzers and fuel cells with inexpensive, platinum‐group metal‐free analogs. Among these, Fe/N/C‐type catalysts display promising performances for the reduction of O2 or CO2, but their insufficient activity and stability jeopardize their implementation in such devices. To circumvent these issues, a better understanding of the local geometric and electronic structure of their catalytic active sites under reaction conditions is needed. Herein we shed light on the electronic structure of the molecular sites in two Fe/N/C catalysts by probing their average spin state with X‐ray emission spectroscopy (XES). Chiefly, our in situ XES measurements reveal for the first time the existence of reversible, potential‐induced spin state changes in these materials.
Magnetic‐Field‐Stimulated Efficient Photocatalytic N2 Fixation over Defective BaTiO3 Perovskites
Authors: Zhao Zhao , Wang Dandan , Gao Rui , Wen Guobin , Feng Ming , Song Guangxin , Zhu Jianbing , Luo Dan , Tan Huaqiao , Ge Xin , Zhang Wei , Zhang Yujun , Zheng Lirong , Li Haibo , Chen Zhongwei 
Published: February 2021

AbstractEfficient coupling solar energy conversion and N2 fixation by photocatalysis has been shown promising potentials. However, the unsatisfied yield rate of NH3 curbs its forward application. Defective typical perovskite, BaTiO3, shows remarkable activity under an applied magnetic field for photocatalytic N2 fixation with an NH3 yield rate exceeding 1.93 mg L−1 h−1. Through steered surface spin states and oxygen vacancies, the electromagnetic synergistic effect between the internal electric field and an external magnetic field is stimulated. X‐ray absorption spectroscopy and density functional theory calculations reveal the regulation of electronic and magnetic properties through manipulation of oxygen vacancies and inducement of Lorentz force and spin selectivity effect. The electromagnetic effect suppresses the recombination of photoexcited carriers in semiconducting nanomaterials, which acts synergistically to promote N2 adsorption and activation while facilitating fast charge separation under UV‐vis irradiation.
CBD activation of TRPV1 induces oxidative signaling and subsequent ER stress in breast cancer cell lines
Authors: de la Harpe Amy , Beukes Natasha , Frost Carminita L. 
Published: February 2021

AbstractEndoplasmic reticulum (ER) stress is an imbalance between the protein‐folding load and capacity of ER. It can be induced by various physiological conditions, activating the unfolded protein response (UPR) to re‐establish homeostasis, promoting cell survival. Under severe or chronic stress, apoptosis is induced. Normal cells generally do not experience continuous ER stress induction. The stressful conditions experienced in the tumor microenvironment facilitate chronic ER stress and UPR activation, which plays a pivotal role in tumour survival. Exacerbation of pre‐existing ER stress can trigger cancer cell death, with a minimal effect on normal cells. Current literature suggests that cannabinoid treatment may induce cancer cell death via ER stress; however, little is known about the mechanisms of induction. This study proposed that cannabidiol (CBD) mechanism occurred through the influx of Ca2+ via the TRPV1 receptor, and increasing reactive oxygen species (ROS) production affects protein folding and induces ER stress. ER stress was induced, and detection and quantification were completed using Thioflavin T staining and GRP78 by western blot analysis. The effect of cannabinoid treatment on ROS production and Ca2+ influx was measured. CBD was the most potent ER stress inducer, significantly increasing Ca2+ and ROS accumulation. Concomitant treatment with CBD and an antioxidant significantly increased cell viability and decreased ER stress induction in the MCF7 cell line. Concomitant treatment with a TRPV1 antagonist increased viability in this cell line. In conclusion, the data suggested that CBD induced ER stress via Ca2+ influx through the TRPV1 receptor, thereby elevating intracellular ROS levels and disrupting protein folding.
Development and validation of LC–MS method for the determination of heptaethylene glycol monomethyl ether in benzonatate bulk drugs
Authors: Katakam Lakshmi Narasimha Rao , Ettaboina Santhosh Kumar , Marisetti Vishnu Murthy 
Published: February 2021

AbstractA simple and isocratic reverse‐phase liquid chromatography with mass spectrometric method has been developed and validated for the determination of heptaethylene glycol monomethyl ether in benzonatate drug substance. Benzonatate is an oral antitussive drug used to relieve and suppress cough in patients older than 10 years. The presence of residual heptaethylene glycol monomethyl ether in the benzonatate drug substance affects the safety, strength, purity and quality of the drug substance. The subject compound separation was achieved using 0.1% formic acid and acetonitrile (50:50 v/v) at a flow rate of 0.3 ml/min. The Suplex PKB‐100 250 × 4.6 mm, 5 μm LC column was used for a better peak shape. Detection was carried out at anm/zvalue of 341. The linearity curve showed a correlation of coefficient of >0.999. The precision and intermediate precision (RSD) were <7.30. The accuracy values were >90% for all levels. The developed method was validated as per International Conference on Harmonization guidelines and found to be a novel, specific and sensitive analytical method for determination of components of interest.
Stabil: An educational Matlab toolbox for static and dynamic structural analysis
Authors: François Stijn , Schevenels Mattias , Dooms David , Jansen Miche , Wambacq Jef , Lombaert Geert , Degrande Geert , De Roeck Guido 
Published: February 2021

AbstractThe capability to analyze structures under static and dynamic loads is an essential skill for structural engineers. Structural analysis therefore is a key component in civil and architectural engineering education, where analytical methods are traditionally complemented by the use of (commercial) software packages. The latter are often closed source, which may obscure the links to the underlying matrix structural analysis or finite element formulation. To stimulate active, cooperative, and solution‐oriented learning, we developed Stabil, an electronic learning environment implemented as a Matlab toolbox. Stabil has an open structure to elucidate the links between theory and implementation and is presently used throughout the curricula of Civil and Architectural Engineering at KU Leuven. This paper explains the main principles of Stabil and discusses teaching experiences over the past 15 years. Stabil can be downloaded from http://bwk.kuleuven.be/bwm/stabil.
The accuracy of HPV genotyping in isolation and in combination with CD4 and HIV viral load for the identification of HIV‐infected women at risk for developing cervical cancer
Authors: Piyathilake Chandrika J. , Badiga Suguna , Burkholder Greer A. , Harada Shuko , Raper James L. 
Published: February 2021

AbstractBackgroundHuman papillomavirus (HPV) genotype testing has limited utility to identify human immunodeficiency virus‐infected (HIV+) women's risk for developing cervical cancer (CC) due to high positivity rate of high‐risk (HR) HPVs. We investigated the accuracy of HPV testing in isolation/in combination with CD4 and HIV viral load (VL) to identify HIV+ women at risk for developing CC.MethodsStudy consisted of 344 HIV+ women on combination antiretroviral therapy (cART), tested for cervical cytology/HPV using the Cobas test and had data on absolute CD4 count and VL measurements. We calculated the positive predictive value (PPV) and negative predictive value (NPV) of HPV testing, pre‐, post‐cART, and current CD4 and VL in isolation and in combinations to identify those with or free of higher than atypical squamous cells of unknown significance (ASCUS+) or low‐grade intraepithelial lesions (LSIL+).ResultsHPV test in combination with pre‐/post‐cART or current CD4 counts and VL had higher PPVs compared to HPV test alone for identifying ASCUS+ or LSIL+. PPV of HPV‐CD4 combinations yielded higher PPVs compared to HPV‐VL combinations. The NPVs with pre‐, post‐cART, or current CD4 count and VL in isolation or in combinations were comparable to that of HPV test alone.ConclusionsOur results provide a more accurate tool for managing HIV+ women by combining Cobas HPV with CD4 and VL, especially those who had an undesirable pre‐cART CD4 and VL status. Our results also indicate the usefulness of CD4 and VL measurements to identify those at lower risk in the absence of HPV testing.
Unrevealed foreign body in the deep neck space: A case report
Authors: Borin Marco , Pignataro Lorenzo , Ibba Tullio , Di Cicco Maurizio , Folino Francesco , Marchisio Paola , Capaccio Pasquale , Torretta Sara 
Published: February 2021

AbstractClinical data provided by the patient are not always reliable or could be difficult to collect. In this case, a difficult history collection resulted in a diagnostic delay. Major complications were avoided performing an urgent surgical intervention.
Preparation of Metal Oxide‐based Oxygen Carriers Supported with CeO2 and γ‐Al2O3 for Chemical Looping Combustion
Authors: Qasim Muhammad , Ayoub Muhammad , Aqsha Aqsha , Zulfiqar Muhammad 
Published: February 2021

AbstractThe development of efficient oxygen carriers (OCs) in chemical looping combustion (CLC) exhibited tremendous achievement considering inherent CO2 capture. The selectivity of CO2 in the CLC process depends on the performance of employed OCs during multiple redox cycles. Different types of OCs were prepared, including 5wt%Ni/5wt%Ce/γ‐Al2O3, 5wt%La/5wt%Ce/γ‐Al2O3, and 5wt%Pr/5wt%Ce/γ‐Al2O3, using the wet impregnation method and characterized by scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, temperature‐programmed reduction, and thermogravimetric analysis (TGA). The redox reactivity of OCs was investigated through TGA and tubular furnace reactor. The as‐prepared OCs revealed higher thermal stability along with excellent oxygen capacity. Pr/Ce/γ‐Al2O3‐based OCs showed moderate oxygen capacity, which may increase by the addition of active metals.
Preparation of a novel hydroxypropyl‐γ‐cyclodextrin functionalized monolith for separation of chiral drugs in capillary electrochromatography
Authors: Deng Miaoduo , Xue Mengyao , Liu Yanru , Zhao Min 
Published: February 2021

AbstractIn this study, a novel hydroxypropyl‐γ‐cyclodextrin (HP‐γ‐CD) functionalized monolithic capillary column was prepared by one‐pot sequential strategy and used for chiral separation in capillary electrochromatography for the first time. In one pot, GMA‐HP‐γ‐CD as functional monomer was allowed to be formed via the ring opening reaction between HP‐γ‐CD and glycidyl methacrylate (GMA) catalyzed by 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and then copolymerized directly with ethylene dimethacrylate (EDMA) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) in the presence of porogenic solvents via thermally initiated free radical polymerization. The preparation conditions of monoliths were optimized. Enantiomer separations of six chiral drugs including pindolol, clorprenaline, tulobuterol, clenbuterol, propranolol, and tropicamide were achieved on the monolith. Among them, pindolol, clorprenaline, and tropicamide were baseline separated with resolution values of 1.62, 1.73, and 1.55, respectively. The mechanism of enantiomer separation was discussed by comparison of the HP‐γ‐CD and HP‐β‐CD functionalized monoliths.
Percutaneous coronary intervention and 30‐day unplanned readmission with chest pain in the United States (Nationwide Readmissions Database)
Authors: Sykes RobertA. , Mohamed Mohamed O. , Kwok Chun Shing , Mamas Mamas A. , Berry Colin 
Published: February 2021

AbstractPercutaneous coronary intervention (PCI) improves anginal chest pain in most, but not all, treated patients. PCI is associated with unplanned readmission for angina and non‐specific chest pain within 30‐days of index PCI. Patients with an index hospitalization for PCI between January–November in each of the years 2010–2014 were included from the United States Nationwide Readmissions Database. Of 2 723 455 included patients, the 30‐day unplanned readmission rate was 7.2% (n = 196 581, 42.3% female). This included 9.8% (n = 19 183) with angina and 11.1% (n = 21 714) with non‐specific chest pain. The unplanned readmission group were younger (62.2 vs 65.1 years; P < 0.001), more likely to be females (41.0% vs 34.2%; P < 0.001), from the lowest quartile of household income (32.9% vs 31.2%; P < 0.001), have higher prevalence of cardiovascular risk factors or have index PCI performed for non‐acute coronary syndromes (ACS) (OR:3.46, 95%CI 3.39–3.54). Factors associated with angina readmissions included female sex (OR:1.28, 95%CI 1.25–1.32), history of ischemic heart disease (IHD) (OR:3.28, 95%CI 2.95–3.66), coronary artery bypass grafts (OR:1.79, 95%CI 1.72–2.86), anaemia (OR:1.16, 95%CI 1.11–1.21), hypertension (OR:1.13, 95%CI 1.09, 1.17), and dyslipidemia (OR:1.10, 95%CI 1.06–1.14). Non‐specific chest pain compared with angina readmissions were younger (mean difference 1.25 years, 95% CI 0.99, 1.50), more likely to be females (RR:1.13, 95%CI 1.10, 1.15) and have undergone PCI for non‐ACS (RR:2.17, 95%CI 2.13, 2.21). Indications for PCI other than ACS have a greater likelihood of readmission with angina or non‐specific chest pain at 30‐days. Readmissions are more common in patients with modifiable risk factors, previous history of IHD and anaemia.
Aromaticity/Antiaromaticity Effect on Activity of Transition Metal Macrocyclic Complexes towards Electrocatalytic Oxygen Reduction
Authors: Ni Youxuan , Lu Yong , Zhang Kai , Chen Jun 
Published: February 2021

AbstractThe effect of the coordination sphere around metal centers on the oxygen reduction reaction (ORR) activity of transition metal macrocyclic complexes is still unclear. Here, the aromaticity/antiaromaticity effect of macrocycles on ORR activity was investigated based on TM norcorrole (TM=Mn, Fe, Co, Ni), TM porphycene, and TM porphyrin by first‐principle calculations. It was found that the complexes with weaker aromatic macrocycles exhibited a stronger adsorption strength while the complexes with antiaromatic macrocycles showed further enhanced adsorption strengths. Further investigations indicated that the variation in the adsorption strengths of catalysts was attributed to the different redox activities of macrocycles with different aromaticities. Such difference in redox activities of macrocycles was reflected in the activities of metal centers via d–π conjugation, which acted as a bridge between π‐electrons on macrocycles and active d‐electrons on metal centers. This work deepens the understanding of the role of macrocycles in oxygen electroreduction.
Palynological evidence of Middle Pleistocene palaeoenvironmental changes from the ‘Buca dell’Onice’ flowstone (Alpi Apuane, Central Italy)
Authors: Bertini Adele , Piccini Leonardo , Ricci Marianna , Massini Marco 
Published: February 2021

AbstractBuca dell’Onice di Monte Girello is a small cave located in the Alpi Apuane (central Italy). It preserves an exceptionally thick flowstone deposited intermittently during the Middle Pleistocene. Two main depositional cycles, separated by a physical discontinuity, have been recognised and described. This discontinuity and the top surface of the flowstone attest to two main phases of interrupted growth related to palaeoenvironmental and palaeoclimate changes. Pilot palynological investigations support the existence of such changes. Despite the high number of barren pollen samples and the overall very low concentration of pollen grains per gram of sediment, palynology furnishes some interesting insights especially regarding floral composition, vegetation cover and local to regional climate. The pollen record also contributes to the definition of the stratigraphic distribution of taxa no longer growing in this area (i.e. Carya and Picea). According to the pollen assemblage characteristic of arboreal vegetation cover, the flowstone was deposited predominantly during humid phases under both warm and cool climate conditions (interglacials/interstadials and at the end of interglacials). The warm and cool phases correspond, respectively, to increases of mixed thermophilous forest taxa and montane arboreal taxa. On the other hand, the pollen record does not show the major expansion of open vegetation associated with the coldest and driest conditions, which apparently fall at the main middle discontinuity and at the top interruption of the flowstone. Previous data permit changes in precipitation to be identified as one of the major limiting factors for the growth of this flowstone, probably in a period including MISs 13‐10. The more significant lithological features of the flowstone as well as the vegetal and climate signatures suggest that its development principally represents a response to global events including teleconnections active between the Mediterranean and the Atlantic circulation, with minor contribution from local factors.
Mineral species and formation processes: Raman spectroscopic and microscopic analysis of stains from a late pleistocene continental drowned faunal bone assemblage, Central Chile
Authors: Cartajena Isabel , Celis Freddy , Flores‐Aqueveque Valentina , Pavez Jennifer , Carabias Diego , Simonetti Renato , Arancibia María José 
Published: February 2021

AbstractIn this study we address the analysis of bone staining and its sedimentary deposits to obtain a better understanding of the taphonomic trajectories of faunal assemblages in dynamic site formation processes. The fossil remains belong to continental fauna recovered at GNL Quintero 1, a Late Pleistocene drowned terrestrial site located nearshore at Quintero bay in the central coast of Chile (32° S). By conducting Raman spectroscopic and microscopic analyses we aim to identify the mineral compounds of bone staining and their sedimentary matrix, perform a first geochemical characterization of the depositional environments and carry out paleoenvironmental inferences. Stains are present on most remains and recur in a variety of colors, indicating the presence of minerals, such as hematite, goethite, pyrolusite, pyrite or marcasite, mackinawite, and greigite. Mineral species identified are associated with oxic and anoxic environments, suggesting that the bones and sediments underwent both sulfuricization and sulfidization processes. Spectroscopic data obtained suggest that the trajectory of the remains was much more dynamic than previously assumed. These geochemical scenarios of alternating oxidation and reduction reflects the diverse environments involved during the terrestrial phase, the transitional phase of rising sea level, and subsequently the marine phase.
Home and host distal context and performance appraisal in multinational enterprises: A 22 country study
Authors: Morley Michael J. , Murphy Kevin R. , Cleveland Jeanette N. , Heraty Noreen , McCarthy Jean 
Published: February 2021

AbstractContext is a central construct in the study of performance appraisal (PA) systems, but to date studies linking the distal context within which organizations operate to PA have been limited in two ways. First, these studies have focused predominantly on national culture, and have paid less attention to the legal/political and economic environment within which organizations. Second, few studies reflect the growing international nature of business organizations, which create multiple layers of context (e.g., home and host country context). Drawing on both situational strength and institutional theories, we hypothesize the links between the “big three” facets of distal context (i.e., culture, legal/political, and economic) and the processes and purposes of PA systems. Using data from 472 multinational enterprises (MNEs) in 22 countries, we show that all three facets of the distal context of the host country influence decisions about the conduct of PA systems. In addition, we show that the culture and legal/political systems of the home country from which the MNE originated are also linked to the PA processes and purposes. Finally, we find evidence that MNEs are more likely to develop hybridized PA systems that depart from host country norms.