bluuebunny/crossref_metadata_2025_split huggingface dataset:
Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities
Authors: Li Ying , Shiraiwa Manabu 
Published: May 2019

Abstract. Secondary organic aerosols (SOA) account for a substantial fraction of air
particulate matter, and SOA formation is often modeled assuming rapid
establishment of gas–particle equilibrium. Here, we estimate the
characteristic timescale for SOA to achieve gas–particle equilibrium under
a wide range of temperatures and relative humidities using a
state-of-the-art kinetic flux model. Equilibration timescales were
calculated by varying particle phase state, size, mass loadings, and
volatility of organic compounds in open and closed systems. Model
simulations suggest that the equilibration timescale for semi-volatile
compounds is on the order of seconds or minutes for most conditions in the
planetary boundary layer, but it can be longer than 1 h if particles
adopt glassy or amorphous solid states with high glass transition
temperatures at low relative humidity. In the free troposphere with lower
temperatures, it can be longer than hours or days, even at moderate or
relatively high relative humidities due to kinetic limitations of bulk
diffusion in highly viscous particles. The timescale of partitioning of
low-volatile compounds into highly viscous particles is shorter compared to
semi-volatile compounds in the closed system, as it is largely determined by
condensation sink due to very slow re-evaporation with relatively quick
establishment of local equilibrium between the gas phase and the
near-surface bulk. The dependence of equilibration timescales on both
volatility and bulk diffusivity provides critical insights into
thermodynamic or kinetic treatments of SOA partitioning for accurate
predictions of gas- and particle-phase concentrations of semi-volatile
compounds in regional and global chemical transport models.
Development of an Efficient Extraction Method for Separating Solasodine, an Steroidal Alkaloid, From an Oily Matrix: A Comparison Between LLE and SPE
Authors: Khandani Shahram Kalantari , Mehrabani Mitra , Sharififar Fariba , Pardakhty Abbas , Pournamdari Mostafa 
Published: May 2019

Aims: In many references of Traditional Iranian Medicine (TIM), there are methods to produce medicinal products from plant fruit based on extraction of active substances into oils. One of these recommendations is to import cucurbit or pumpkin seed oil into an entirely ripe fruit of Solanum melongena plant. In this study for the first time, the extraction of solasodine from the oily matrix has been investigated to find a precise method with suitable extraction recovery.
Study Design: Original Research Article.
Place and Duration of Study: The study took place in herbal and traditional medicines research center of Kerman, Iran from February 2015 to November 2017.
Methodology: Solasodine, an active steroidal alkaloid metabolite of the plant, was used for standardization of the product. Two methods of (Liquid-liquid extraction) LLE and (Solid phase extraction) SPE were evaluated and their conditions were optimized by assessment of seven effective factors at five levels using HPLC as the method of choice for solasodine determination.
Results: Results showed that LLE and SPE in optimized conditions had recoveries of about 76.5 and 94.7%, respectively. For the extraction of low concentrations of the analyte, the SPE method had better accuracies (88 to 105%), but its precision was less than that of LLE method. In contrast, the LLE method had a higher precision in the whole range while its relevant accuracy was lower. The LOD and LOQ of SPE-HPLC method were 0.2 and 0.6 μg/ml and those of the LLE-HPLC method were 0.2 and 0.7 μg/ml, respectively.
Conclusion: In general, both methods of LLE-HPLC and SPE-HPLC showed acceptable validation parameters including linearity, precision, accuracy, LOD, and LOQ; and they can be used for routine extraction and determination of solasodine in traditional medicine products.
Stretch Induces Invasive Phenotypes in Breast Cells Due to Activation of Aerobic‐Glycolysis‐Related Pathways
Authors: Ansaryan Saeid , Khayamian Mohammad Ali , Saghafi Mohammad , Shalileh Shahriar , Nikshoar Mohammad Saied , Abbasvandi Fereshteh , Mahmoudi Morteza , Bahrami Farideh , Abdolahad Mohammad 
Published: May 2019

AbstractIt is increasingly being accepted that cells' physiological functions are substantially dependent on the mechanical characteristics of their surrounding tissue. This is mainly due to the key role of biomechanical forces on cells and their nucleus' shapes, which have the capacity to regulate chromatin conformation and thus gene regulations. Therefore, it is reasonable to postulate that altering the biomechanical properties of tissue may have the capacity to change cell functions. Here, the role of cell stretching (as a model of biomechanical variations) is probed in cell migration and invasion capacity using human normal and cancerous breast cells. By several analyses (i.e., scratch assay, invasion to endothelial barrier, real‐time RNA sequencing, confocal imaging, patch clamp, etc.), it is revealed that the cell‐stretching process could increase the migration and invasion capabilities of normal and cancerous cells, respectively. More specifically, it is found that poststretched breast cancer cells are found in low grades of invasion; they substantially upregulate the expression of manganese‐dependent superoxide dismutase (MnSOD) through activation of H‐Ras proteins, which subsequently induce aerobic glycolysis followed by an overproduction of matrix metalloproteinases (MMP)‐reinforced filopodias. Presence of such invadopodias facilitates targeting of the endothelial layer, and increased invasive behaviors in breast cells are observed.
Guided Assembly of Microporous/Mesoporous Manganese Phosphates by Bifunctional Organophosphonic Acid Etching and Templating
Authors: Hu Yating , Zhang Yu , Li Changjian , Wang Ling , Du Yonghua , Mo Guang , Li Xu , Cheetham Anthony K. , Wang John 
Published: May 2019

AbstractManganese (Mn)‐based compounds are important materials for both energy conversion and energy storage. Unfortunately, it has been a significant challenge to develop highly ordered microporous/mesoporous structures for them to provide more active sites for these applications. In order to do so using the soft‐templating method, three conditions have to be met, namely, a strong interaction between the inorganic precursor and the organic templates; eliminating the formation of bulk manganese phosphate; and the preservation of the manganese phosphate framework without it collapsing upon template removal. Herein, a soft‐templating approach is reported using an organophosphonic acid (n‐hexylphosphonic acid) as both the etching and the templating agent, followed by high‐vacuum‐assisted annealing. This approach simultaneously satisfies the above conditions. Both microporous and mesoporous manganese phosphates with uniform pore sizes and well‐defined pore structures are obtained. The utilization of the organophosphonic acid is shown to be the key in the transformation from bulk manganese oxide into a highly ordered microporous phosphate. A very high surface area of 304.1 m2 g−1 is obtained for the microporous manganese phosphate, which is the highest among the reported values for Mn‐based compounds. The ultrafine micropores and high specific surface area of our manganese phosphate promote electrocatalytic activity for the oxygen evolution reaction.
Analysis of the Emergency Medicine Clinical Learning Environment
Authors: Ramana Feeser V. , Zemore Zachary , Appelbaum Nital , Santen Sally A. , Moll Joel , Aboff Brian , Hemphill Robin R. 
Published: May 2019

AbstractBackgroundResidencies are grappling with ways to identify methods to internally monitor and improve their learning environments. Building on prior work, the objective of this study was to determine emergency medicine (EM) internal evaluations of perceived organizational support and psychological safety and compare to the results from the Accreditation Council for Graduate Medical Education (ACGME) Resident Survey for the purpose of program improvement and to explore factors affecting residents’ perception of their learning environment.MethodsIn 2017, the Virginia Commonwealth University School of Medicine Office of Graduate Medical Education and Office of Quality and Safety conducted an in‐person, anonymous safety survey of the residents across 19 residency programs on the Short Survey of Perceived Organizational Support (SPOS) and Psychological Safety Scale (PSS). These were compared to the ACGME Resident Survey for 19 programs. Resident interviews and open response evaluation data informed content analysis on program experiences.ResultsInstitutional response rates were 63% for the internal learning environment survey and 96% for ACGME Resident Safety Survey. EM residents responded positively on the SPOS and PSS compared to other programs (ranked second highest scores on both scales). One‐hundred percent of respondents agreed or strongly agreed on SPOS items: “Help is available from my department when I have a problem.” “My department really cares about my well‐being.” “My department values my contribution to its well‐being.” Furthermore, EM had the highest overall training experience score (mean = 4.83) on the ACGME survey compared to the 18 other training programs. Qualitative responses suggest program strengths included supportive program leadership, positive working relationships with faculty, and emphasis on trainee wellness.ConclusionsCompared to other programs, EM has created a positive environment of safety and support as perceived by their residents. Internal surveys of the learning environment can help programs understand their culture for purposes of improvement and align with the ACGME survey.
Multiproxy isotopic analyses of human skeletal material from Rapa Nui: Evaluating the evidence from carbonates, bulk collagen, and amino acids
Authors: Commendador Amy S. , Finney Bruce P. , Fuller Benjamin T. , Tromp Monica , Dudgeon John V. 
Published: May 2019

AbstractObjectivesStable isotope ratio analysis of bulk bone collagen dominates research into past diet; however, bone carbonate and compound specific isotope analyses (CSIA) of amino acids provide alternative, yet complementary, lines of evidence toward that same research goal. Together they inform on different aspects of diet, allowing greater certainty in reconstructions. Here we present new data on carbonate isotopes for Rapa Nui and reevaluate prehistoric diet in the context of these new and previously published bulk collagen and CSIA data.Materials and methodsWe analyzed carbon isotopes in bone carbonate from 28 prehistoric human teeth from Rapa Nui. These represent a subset of material examined previously for carbon and nitrogen isotope ratios in bulk collagen. We then reevaluate prehistoric diet in light of these and other published data. In addition, we analyzed carbon and nitrogen isotope ratios in 28 modern plant specimens from Rapa Nui to better approximate the isotopic value of the terrestrial endmember.ResultsBulk data suggest a predominantly terrestrial diet, with the amount of marine sources incorporated varying though time. While previously argued to reveal greater amounts of marine consumption, reanalysis of recently published CSIA data suggests this result may relate to the proportion of carbon assimilated rather than consumed. Utilizing models incorporating concentration dependence for estimating dietary proportions results in much lower estimates of marine consumption, in line with findings of the bulk data.DiscussionWhile these data indicate a larger focus on terrestrial resources, limitations in all forms of analysis make it difficult to determine exact dietary contributions in this mixed system. Better understanding of the complex physiological processes governing isotopic routing and fractionation, and knowledge of appropriate isotopic endmember values are needed to advance this research.
Highly Crystalline Mesoporous Phosphotungstic Acid: A High‐Performance Electrode Material for Energy‐Storage Applications
Authors: Ilbeygi Hamid , Kim In Young , Kim Min Gyu , Cha Wangsoo , Kumar Paskalis Sahaya Murphin , Park Dae‐Hwan , Vinu Ajayan 
Published: May 2019

AbstractHeteropoly acids (HPAs) are unique materials with interesting properties, including high acidity and proton conductivity. However, their low specific surface area and high solubility in polar solvents make them unattractive for catalytic or energy applications. This obstacle can be overcome by creating nanoporosity within the HPA. We synthesized mesoporous phosphotungstic acid (mPTA) with a spherical morphology through the self‐assembly of phosphotungstic acid (PTA) with a polymeric surfactant as stabilized by KCl and hydrothermal treatment. The mPTA nanostructures had a surface area of 93 m2 g−1 and a pore size of 4 nm. Their high thermal stability (ca. 450 °C) and lack of solubility in ethylene carbonate/diethyl carbonate (EC/DEC) electrolyte are beneficial for lithium‐ion batteries (LIBs). Optimized mPTA showed a reversible capacity of 872 mAh g−1 at 0.1 A g−1 even after 100 cycles for LIBs, as attributed to a super‐reduced state of HPA and the storage of Li ions within the mesochannels of mPTA.
De Novo Synthesis of Highly Functionalized Benzimidazolones and Benzoxazolones through an Electrochemical Dehydrogenative Cyclization Cascade
Authors: Xu Fan , Long Hao , Song Jinshuai , Xu Hai‐Chao 
Published: May 2019

AbstractBenzimidazolone and benzoxazolone moieties are important scaffolds in a variety of pharmaceutical molecules. These bicyclic heterocycles are usually prepared from a benzene derivative through the construction of an additional five‐membered heterocyclic ring. We report herein a method that enables the efficient synthesis of highly substituted benzimidazolone and benzoxazolone derivatives by building both the benzene and the heterocyclic rings through a dehydrogenative cyclization cascade. Readily available arylamine‐tethered 1,5‐enynes undergo a biscyclization/dehydrogenation cascade to afford functionalized benzanellated heterocycles in a single step with complete control of regioselectivity. These electricity‐powered oxidative transformations proceed with H2 evolution, thus obviating the need for transition‐metal‐based catalysts and oxidizing reagents.
Asymmetric Allylic Alkylation with Deconjugated Carbonyl Compounds: Direct Vinylogous Umpolung Strategy
Authors: Ran Guang‐Yao , Yang Xing‐Xing , Yue Jing‐Fei , Du Wei , Chen Ying‐Chun 
Published: May 2019

AbstractAn atom‐economic and highly efficient vinylogous umpolung strategy is developed for deconjugated carbonyl compounds, which generate electron‐deficient π‐allylpalladium complexes with Pd(OAc)2 under ligand‐free conditions. In cooperation with a chiral‐phosphonium‐based phase‐transfer catalyst, the asymmetric direct oxidative allylic alkylations of 3‐substituted oxindoles are furnished under O2 atmosphere. The γ‐ or even remote ϵ‐regioselective alkylation products, with substantial substituents, are delivered with excellent enantioselectivity, and can be further used to access diverse chiral spirocyclic architectures effectively. The Mukaiyama dienol silyl ether can be utilized similarly, indicating that the current active π‐allylpalladium species results from tautomerization of the PdII‐dienolate intermediate.
Reactions of Fe2(μ‐odt)(CO)6 (odt = 1, 3‐oxadithiolate) with small bite‐angle diphosphines to afford the monodentate, chelate, and bridge diiron complexes: Selective substitution, structures, protonation, and electrocatalytic proton reduction
Authors: Hu Meng‐Yuan , Yan Lin , Li Jian‐Rong , Wang Yan‐Hong , Zhao Pei‐Hua , Liu Xu‐Feng 
Published: May 2019

Selective substitutions of Fe2(μ‐odt)(CO)6 (odt = 1,3‐oxadithiolate, A) and small bite‐angle diphosphines (Ph2P)2X [X = CH2 (dppm) or N (CH2CHMe2) (dppa)] have been well investigated in this study. With Me3NO·2H2O in MeCN at room temperature, the reaction of A and dppm produced the monodentate complex [Fe2(μ‐odt)(CO)5(κ1‐dppm)] (1), whereas the similar reaction with dppa afforded the chelate complex [Fe2(μ‐odt)(CO)4(κ2‐dppa)] (2). Using UV irradiation in toluene emitting at 365 nm, the treatment of A and dppm rarely resulted in the formation of the bridge complex [Fe2(μ‐odt)(CO)4(μ‐dppm)] (3), whereas the similar treatment with dppa formed the chelate complex 2. Under thermolysis condition, refluxing solution of A with dppm or dppa gave the bridge complex 3 and [Fe2(μ‐odt)(CO)4(μ‐dppa)] (4), respectively, in which the former was formed in toluene (110 °C) but the latter was produced in xylene (138 °C). All the new complexes 1–4 obtained above were characterized by element analysis, FT‐IR, NMR (1H, 31P) spectroscopies, and particularly for 1–3 by X‐ray crystallography. Furthermore, the in situ protonations of 2 with a weak acid HOAc (acetic acid) and a strong acid TFA (trifluoroacetic acid) are explored by means of FT‐IR and NMR (1H, 31P) spectra. In addition, the electrochemical behaviors of 2–4 are studied and compared through cyclic voltammetry (CV) in the absence and presence of a strong acid (TFA) as a proton source, indicating that they all are active for electrocatalytic proton reduction to hydrogen (H2).
1,3‐Diamino‐2‐propanol or 2‐aminoethanethiol modified active layer of thin‐film composite forward osmosis membrane
Authors: Sun Jiajin , Hu Xuhui , Huang Yangbo , Peng Ruichao , Luo Yunbai , Yu Ping 
Published: May 2019

ABSTRACTThis work proposes three easy and effective methods to improve the density of the active layer of the thin‐film composite (TFC) forward osmosis (FO) membrane. Amino groups are introduced to the polyamide layer to react with the exposed acid chloride groups after a small molecule of 1,3‐diamino‐2‐propanol (DH) or 2‐aminoethanethiol (AE) or DH–AE being introduced. This may lead to a higher degree of crosslinking and form a more complex and networked aggregate structure. In this work, three modified membranes are successfully prepared, and a series of characterizations are carried out. The result is that all methods can improve the density of the active layer and increase the salt rejection without adversely affecting the selectivity. The hydrophilicity of the TFC‐DH film is significantly improved, the reverse salt flux of the TFC‐AE film is remarkably improved, and the effect of the TFC‐DH–AE film is between the TFC‐DH film and the TFC‐AE film. Therefore, the method of adding a small molecular material can increase the degree of polymerization. The method of introducing an inorganic element provides a valuable solution for designing and developing a novel and efficient FO film, which is simple and easy to be operated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47923.
Preparation of Composite Filters Based on Porous Coordination Polymers by Using a Vacuum Filtration Method for Highly Efficient Removal of Particulate Matters
Authors: Gai Shuang , Fan Ruiqing , Xing Kai , Wang Ani , Zheng Xubin , Zhou Xuesong , Wang Ping , Yang Yulin 
Published: May 2019

AbstractIn this study, two novel crystal materials pcp1 and pcp1‐L have been synthesized successfully. The different conformations of the two crystals are mainly attributed to the introduction of the Schiff‐base ligand L (L=(E)‐4‐methyl‐N‐((6‐methoxypyridin‐2‐yl)methylene)aniline). Subsequently, pcp1 and pcp1‐L composites have been firstly produced by a vacuum filtration method on various substrates (i.e., melamine foam, plastic mesh, carbon fiber cloth and glass cloth). The obtained robust composites show excellent performance in removing PMs owing to high ζ potential, microporous structure, large conjugation system and electron cloud‐exposed metal center (DFT calculations) of pcp1 and pcp1‐L. Particularly, pcp1‐L@glass cloth with low pressure drop exhibits high thermal stability and high long‐term reproducibility. Additionally, the high removal efficiency of pcp1‐L@glass cloth towards particulate matters could also be maintained, even achieving >99.9 % in the car exhaust gas field test.
Determination of nikethamide by micellar electrokinetic chromatography
Authors: Purgat Krystian , Borowczyk Kamila , Zakrzewski Robert , Głowacki Rafał , Kubalczyk Paweł 
Published: May 2019

AbstractA simple, fast, sensitive and reproducible micellar electrokinetic chromatography (MEKC)–UV method for the determination of nikethamide (NKD) in human urine and pharmaceutical formulation has been developed and validated. The method exhibits high trueness, good precision, short analysis time and low reagent consumption. NKD is an organic compound belonging to the psychoactive stimulants used as an analeptic drugs. The proposed analytical procedure consists of few steps: dilution of urine or drug in distilled water, centrifugation for 2 min (12,000g), separation by MEKC and ultraviolet‐absorbance detection of NKD at 260 nm. The background electrolyte used was 0.035 mol/L pH 9 borate buffer with the addition of 0.05 mol/L sodium dodecyl sulfate and 6.5% ACN. Effective separation was achieved within 5.5 min under a voltage of 21 kV (~90 μA) using a standard fused‐silica capillary (effective length 51 cm, 75 μm i.d.). The determined limit of detection for NKD in urine was 1 μmol/L (0.18 μg/mL). The calibration curve obtained for NKD in urine showed linearity in the range 4–280 μmol/L (0.71–49.90 μg/mL), with R2 0.9998. The RSD of the points of the calibration curve varied from 5.4 to 9.5%. The analytical procedure was successfully applied to analysis of pharmaceutical formulation and spiked urine samples from healthy volunteers.
Studies on oral bioavailability and first‐pass metabolism of withaferin A in rats using LC–MS/MS and Q‐TRAP
Authors: Dai Tianming , Jiang Weifan , Guo Zizheng , Wang Zhenyu , Huang Mingping , Zhong Guorui , Liang Chuxin , Pei Xuzhe , Dai Renke 
Published: May 2019

AbstractWithaferin A (WA) is one of the major bioactive steroidal lactones with extensive pharmacological activities present in the plant Withania somnifera. The absolute oral bioavailability of WA remains unknown and human‐related in vitro data are not available. Therefore, in the present study, the absolute oral bioavailability of WA in male rats and the in vitro screening of absorption factors by Q‐trap and LC–MS/MS analysis were conducted to explore possible clinical properties of WA. The developed and validated analytical methods were successfully applied to the pharmacokinetic studies and in vitro measurement of WA. The oral bioavailability was determined to be 32.4 ± 4.8% based on intravenous (5 mg/kg) and oral (10 mg/kg) administrations of WA in male rats. The in vitro results showed that WA could be easily transported across Caco‐2 cells and WA did not show as a substrate for P‐glycoprotein. Moreover, the stability of WA was similar between male rat and human in simulated gastric fluid (stable), in intestinal microflora solution (slow decrease) and in liver microsomes (rapid depletion, with a half‐life of 5.6 min). As such, the first‐pass metabolism of WA was further verified by rat intestine‐liver in situ perfusion, revealing that WA rapidly decreased and 27.1% remained within 1 h, while the content of three major metabolites (M1, M4, M5) identified by Q‐trap increased. This perfusion result is consistent with the oral bioavailability results in vivo. The first‐pass metabolism of WA might be the main barrier in achieving good oral bioavailability in male rats and it is predicted to be similar in humans. This study may hold clinical significance.