bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Pressure on Organic Reactions in Fluids—a New Theoretical Perspective
Authors: Chen Bo , Hoffmann Roald , Cammi Roberto 
Published: July 2017

AbstractThis Review brings a new perspective to the study of chemical reactions in compressed fluid media. We begin by reviewing the substantial insight gained from more than 50 years of experimental studies on organic reactions in solution under pressure. These led to a proper estimation of the critical roles of volume of activation (Δ≠V) and reaction volume (ΔV) in understanding pressure effect on rates and equilibria of organic reactions. A recently developed computational method, the XP‐PCM (extreme pressure polarizable continuum model) method, capable of carrying out quantum mechanical calculations of reaction pathways of molecules under pressure, is introduced. A case study of the Diels–Alder cycloaddition of cyclopentadiene with ethylene serves, in pedagogical detail, to describe the methodology. We then apply the XP‐PCM method to a selection of other pericyclic reactions, including the parent Diels–Alder cycloaddition of butadiene with ethylene, electrocyclic ring‐opening of cyclobutene, electrocyclic ring‐closing of Z‐hexatriene, the [1,5]‐H shift in Z‐pentadiene, and the Cope rearrangement. These serve as examples of some of the most common combinations of Δ≠V and ΔV. Interesting phenomena such as a shift in a transition state along a reaction coordinate, a switch of rate‐determining step, and the possible turning of a transition state into a stable minimum are revealed by the calculations. A reaction volume profile, the change in the volume of the reacting molecules as the reaction proceeds, emerges as being useful.
Development of ethanolamine‐based ionic liquid membranes for efficient CO2/CH4 separation
Authors: Ur Rehman Rashid , Rafiq Sikander , Muhammad Nawshad , Khan Asim Laeeq , Ur Rehman Asif , TingTing Liu , Saeed Muhammad , Jamil Farrukh , Ghauri Moinuddin , Gu Xuehong 
Published: July 2017

ABSTRACTThis study is focused on the development of ionic liquids (ILs) based polymeric membranes for the separation of carbon dioxide (CO2) from methane (CH4). The advantage of ILs in selective CO2 absorption is that it enhances the CO2 selective separation for the ionic liquid membranes (ILMs). ILMs are developed and characterized with two different ILs using the solution‐casting method. Three different blend compositions of ILs and polysulfone (PSF) are selected for each ILMs 10, 20, and 30 wt %. Effect of the different types of ILs such as triethanolamine formate (TEAF) and triethanolamine acetate (TEAA) are investigated on PSF‐based ILMs. Field emission scanning electron microscopy analysis of the membranes showed reasonable homogeneity between the ILs and PSF. Thermogravimetric analysis showed that by increasing the ILs loading thermal stability of the membranes improved. Mechanical analysis on developed membranes showed that ILs phase reduced the amount of plastic flow of the PSF phase and therefore, fracture takes place at gradually lower strains with increasing ILs content. Gas permeation evaluation was carried out on the developed membranes for CO2/CH4 separation between 2 bar to 10 bar feed pressure. Results showed that CO2 permeance increases with the addition of ILs 10–30 wt % in ILMs. With 20–30 wt % TEAF‐ILMs and TEAA‐ILMs, the highest selectivity of a CO2/CH4 53.96 ± 0.3, 37.64 ± 0.2 and CO2 permeance 69.5 ± 0.6, 55.21 ± 0.3 is observed for treated membrane at 2–10 bar. The selectivity using mixed gas test at various CO2/CH4 compositions shows consistent results with the ideal gas selectivity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45395.
Synthesis and thiol–ene photopolymerization of (meth)allyl‐terminated polysulfides
Authors: Brei Mark R. , Donovan Brian R. , Patton Derek L. , Storey Robson F. 
Published: July 2017

ABSTRACTThiol‐terminated polysulfides (PS) are cured by mixing with an oxidant, resulting in limited shelf‐ and/or pot‐life, depending on whether formulated as a one‐ or two‐component system. Mixtures of thiol‐ and alkene‐terminated polysulfides offer the potential for an on‐demand curing process through thiol–ene photopolymerization. Thiol end groups of commercial polysulfides, PS‐1 (1000 g/mol) and PS‐2 (3000 g/mol), were converted to alkene by reaction with (meth)allyl bromide. Photopolymerizations were performed by irradiating films of equimolar thiol:ene mixtures at 320–500 nm (30 mW/cm2) in the presence of 5 wt % 2,2‐dimethoxy‐2‐phenyl‐acetophenone (DMPA). Reaction kinetics were measured using real‐time FTIR by monitoring absorbances at 3075 cm−1 (alkene) or 2550 cm−1 (thiol). In the absence of any reactive diluent, mixtures of thiol and alkene polysulfides failed to gel notwithstanding high reaction conversion (>90%). Partial or total replacement of the thiol polysulfide component with pentaerythritol tetrakis(3‐mercaptopropionate) (PETMP) yielded solid elastomeric films and ultimate reaction conversions of 80–96% after 5 min irradiation. Crosshatch adhesion measured on glass, aluminum, and steel was very poor (0B) for (meth)allyl PS‐1/PETMP and poor (2B) for (meth)allyl PS‐2/PETMP without adhesion promoters. (3‐Mercaptopropyl)trimethoxysilane (1 wt %) significantly improved adhesion of (meth)allyl PS‐2/PETMP on all substrates (4B) but yielded no improvement for (meth)allyl‐terminated PS‐1/PETMP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45523.
Solution self‐assembly behavior of A‐B‐C triblock polymers and the implications for nanoporous membrane fabrication
Authors: Sargent Jessica L. , Hoss Darby J. , Phillip William A. , Boudouris Bryan W. 
Published: July 2017

ABSTRACTSelf‐assembled block polymer membranes are rising to the fore of next‐generation separations technologies, and a particular fabrication process of significant interest is the self‐assembly and non‐solvent induced phase‐separation (SNIPS) method. This is because the SNIPS process allows for the facile manipulation of independent variables to produce simultaneously size‐ and chemically‐selective membranes in a scalable manner. Despite significant advances in the SNIPS membrane fabrication procedure, the early‐stage solution behavior of many of the polymer–solvent systems employed is still poorly understood. This work addresses the challenges posed by these systems and illuminates guiding relationships for the optimization of SNIPS membrane casting solutions. Specifically, polymer aggregate structures and critical micelle concentration (CMC) values are determined for an A‐B‐C triblock polymer dissolved in 1,4‐dioxane using a combination of scattering and atomic force microscopy techniques. The CMC of this system ranges from 20 to 80 μM and shows a strong dependence on the polymer composition and solution processing method. Additionally, the shape of the self‐assembled structures in solution can be altered by varying these parameters. These studies establish the relationships between polymer solution properties (i.e., the block polymer composition and the processing method) and assembly behavior as they impact membrane fabrication through SNIPS processing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45531.
Water‐soluble, antiyellowing polymeric fluorescence brighteners
Authors: Guo Mingyuan , Zhang Guanghua , Du Lun , Zheng Hua , Liu Guojun 
Published: July 2017

ABSTRACTIn this study, a type of polymeric fluorescence brightener (PFB) with a triazine–stilbene structure was synthesized through a three‐step condensation reaction, and the performance of this PFB on antiyellowing was also investigated by the whiteness of paper coated with the as‐prepared PFB. Fourier transform infrared spectra revealed that the chlorine atom (·Cl) was substituted by a poly(vinyl alcohol) (PVA) group ([CH2CHOH]n). According to the UV aging experiment, the PFB not only enhanced the whiteness of the paper but also improved the anti‐UV aging properties [compared to those of VBL 4′‐double‐(6‐diethanolamine‐4‐sulfanilic acid‐1,3,5‐triazine‐2‐amino)‐stilbene‐2,2′‐disulfonic acid sodium, a type of commonly used fluorescent whitening agent as a light stabilizer and fluorescent brightening agent]. Moreover, the results of UV–visible spectra indicated that the substitution of PVA suppressed the isomerization of trans conformers to cis conformers under UV light irradiation; this was attributed to the big space steric hindrance of PVA in the as‐prepared samples being restricted the isomerization reaction. Meanwhile, the solubility of the as‐prepared sample was also improved because more hydroxyl groups were introduced into the PFB with the substitution of PVA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45536.
Euler algorithm to solve reaction kinetic equations: Mathematical formulation, programing, and applications
Authors: Coto Baudilio , Suárez Inmaculada 
Published: July 2017

AbstractIntegration of rate laws to obtain the several concentrations in terms of time is well described in books of General Chemistry, Physical Chemistry, or Chemical Engineering including mathematical and graphical descriptions. When several reactions have to be considered simultaneously, the mathematical solution of involved differential equations became difficult for students and is a good task from the mathematical point of view. Qualitative interpretation has interest from the chemical and engineering point of view and it is usually related with the change of concentrations along reactions which in turns modifies the rate of the several processes involved. In this work, no differential equations are solved analytically and no functions are obtained in order to reduce the mathematical complexity for students but a numerical solution is obtained by using the differential method and the computation of changes in concentration. A general formulation of the involved equations is presented including the effect of reactant concentration in the rate laws and an arbitrary number of simultaneous reactions. Details for numerical solution of involved equations are indicated and the task for students is to create their own program to solve the rate laws. Student should be able to input a set of compounds and reactions, to compute the evolution of concentrations of the several species with time and to plot such concentrations. Some applications with increasing complexity were computed and analyzed. In order to show the quantitative obtained results, comparison with analytical functions was carried out for simple systems.
Comparison of local versus general anesthesia in patients undergoing transcatheter aortic valve replacement: A meta‐analysis
Authors: Villablanca Pedro A. , Mohananey Divyanshu , Nikolic Katarina , Bangalore Sripal , Slovut David P. , Mathew Verghese , Thourani Vinod H. , Rode's‐Cabau Josep , Núñez‐Gil Iván J. , Shah Tina , Gupta Tanush , Briceno David F. , Garcia Mario J. , Gutsche Jacob T. , Augoustides John G. , Ramakrishna Harish 
Published: July 2017

AbstractBackgroundTranscatheter aortic valve replacement (TAVR) is typically performed under general anesthesia (GA). However, there is increasing data supporting the safety of performing TAVR under local anesthesia/conscious sedation (LA). We performed a meta‐analysis to gain better understanding of the safety and efficacy of LA versus GA in patients with severe aortic stenosis undergoing TAVR.Methods and ResultsWe comprehensively searched EMBASE, PubMed, and Web of Science. Effect sizes were summarized using risk ratios (RRs) difference of the mean (DM), and 95% CIs (confidence intervals) for dichotomous and continuous variables respectively. Twenty‐six studies and 10,572 patients were included in the meta‐analysis. The use of LA for TAVR was associated with lower overall 30‐day mortality (RR, 0.73; 95% CI, 0.57–0.93; P = 0.01), use of inotropic/vasopressor drugs (RR, 0.45; 95% CI, 0.28–0.72; P < 0.001), hospital length of stay (LOS) (DM, −2.09; 95% CI, −3.02 to −1.16; P < 0.001), intensive care unit LOS (DM, −0.18; 95% CI, −0.31 to −0.04; P = 0.01), procedure time (DM, −25.02; 95% CI, −32.70 to −17.35; P < 0.001); and fluoroscopy time (DM, −1.63; 95% CI, −3.02 to −0.24; P = 0.02). No differences were observed between LA and GA for stroke, cardiovascular mortality, myocardial infarction, permanent pacemaker implantation, acute kidney injury, paravalvular leak, vascular complications, major bleeding, procedural success, conduction abnormalities, and annular rupture.ConclusionOur meta‐analysis suggests that use of LA for TAVR is associated with a lower 30‐day mortality, shorter procedure time, fluoroscopy time, ICU LOS, hospital length of stay, and reduced need for inotropic support.
Nitrogen‐Doped Graphene with a Three‐Dimensional Architecture Assisted by Carbon Nitride Tetrapods as an Efficient Metal‐Free Electrocatalyst for Hydrogen Evolution
Authors: Gangadharan Pranav K. , Unni Sreekuttan M. , Kumar Nandha , Ghosh Prasenjit , Kurungot Sreekumar 
Published: July 2017

AbstractCurrent polymer membrane‐based electrolyzers use Pt as a cathode catalyst for efficient reduction of water. The high cost of Pt‐based catalysts forces researchers to develop alternative electrocatalysts. Here, a simple strategy has been proposed to synthesize a metal‐free electrocatalyst for the hydrogen evolution reaction (HER) by high‐temperature annealing of graphene oxide‐coated melamine foam. The prepared catalyst possesses both structural and functional advantages with its three‐dimensional (3D) interconnected arms of carbon nitride (CNx) backbone wrapped with nitrogen‐doped graphene (N‐RGO) sheets (CNx@N‐RGO). CNx@N‐RGO faces only a 193 mV overpotential to achieve a current density of 10 mA cm−2, which is far superior to the previously reported Pt‐free systems. Along with the high exchange current density 34.7×10−6 A cm−2 and low Tafel slope of 54 mV dec−1, CNx@N‐RGO follows a Volmer‐Heyrovsky mechanism for the HER. DFT calculations show that the synergy between CNx and N‐RGO facilitates good electrical coupling between the two moieties and provides optimal binding to H+ ions on the catalyst that, in turn, results in efficient reduction of hydrogen ions.
Non‐Covalent Assembly Method that Simultaneously Endows a Liposome Surface with Targeting Ligands, Protective PEG Chains, and Deep‐Red Fluorescence Reporter Groups
Authors: Shaw Scott K. , Liu Wenqi , Brennan Seamus P. , de Lourdes Betancourt‐Mendiola María , Smith Bradley D. 
Published: July 2017

AbstractA new self‐assembly method is used to rapidly functionalize the surface of liposomes without perturbing the membrane integrity or causing leakage of the aqueous contents. The key molecule is a cholesterol‐squaraine‐PEG conjugate with three important structural elements: a cholesterol membrane anchor, a fluorescent squaraine docking station that allows rapid and high‐affinity macrocycle threading, and a long PEG‐2000 chain to provide steric shielding of the decorated liposome. The two‐step method involves spontaneous insertion of the conjugate into the outer leaflet of pre‐formed liposomes followed by squaraine threading with a tetralactam macrocycle that has appended targeting ligands. A macrocycle with six carboxylates permitted immobilization of intact fluorescent liposomes on the surface of cationic polymer beads, whereas a macrocycle with six zinc(II)‐dipicolylamine units enabled selective targeting of anionic membranes, including agglutination of bacteria in the presence of human cells.
Structural Infrared Analysis of Ultra Nanosized Crystals of Yttria‐Stabilized Zirconia
Authors: Miao Baoji , Zhang Meng , Shen Jianhong , Stuerga Didier 
Published: July 2017

AbstractThis paper describes the characterization of ultra nanosized crystals as monoclinic, tetragonal, cubic or mixed phases of ZrO2. Nanopowders are produced using the microwave method, which allows control of the ratio of zirconium to yttrium to yield various crystallographic structures. The synthesized ultra nanosized particles have very broad XRD peaks. In particular, the similarity of the XRD peaks of tetragonal and cubic nanocrystals makes it difficult to distinguish between these two crystals. In this paper, tetragonal and cubic nanocrystals were clearly distinguished using infrared spectroscopy (IR). An infrared spectroscopic method to quantitatively analyse the percentage distribution between the two crystal phases was proposed. The results showed that pure zirconium dioxide was composed of 60 % monoclinic and 40 % tetragonal phases, while 8 % yttria‐stabilized zirconia (YSZ) contained 50 % tetragonal and 50 % cubic phases, and 14 % YSZ contained 100 % cubic phase.
Conducting Polymers Crosslinked with Sulfur as Cathode Materials for High‐Rate, Ultralong‐Life Lithium–Sulfur Batteries
Authors: Zeng Shuaibo , Li Ligui , Xie Lihong , Zhao Dengke , Wang Nan , Chen Shaowei 
Published: July 2017

AbstractLow electrical conductivity and a lack of chemical confinement are two major factors that limit the rate performances and cycling stabilities of cathode materials in lithium–sulfur (Li−S) batteries. Herein, sulfur is copolymerized with poly(m‐aminothiophenol) (PMAT) nanoplates through inverse vulcanization to form the highly crosslinked copolymer cp(S‐PMAT) in which approximately 80 wt % of the feed sulfur is bonded chemically to the thiol groups of PMAT. A cp(S‐PMAT)/C‐based cathode exhibits a high discharge capacity of 1240 mAh g−1 at 0.1 C and remarkable rate capacities of 880 mAh g−1 at 1 C and 600 mAh g−1 at 5 C. Moreover, it can retain a capacity of 495 mAh g−1 after 1000 deep discharge–charge cycles at 2 C; this corresponds to a retention of 66.9 % and a decay rate of only 0.040 % per cycle. Such a remarkable rate performance is attributed to the highly conductive pathways of PMAT nanoplates, and the excellent cycling stability is ascribed mainly to the chemical confinement of sulfur through a large number of stable covalent bonds between sulfur and the thiol groups of PMAT. The results suggest that this strategy is a viable paradigm for the design and engineering of conducting polymers with reactive functional groups as effective electrode materials for high‐performance Li−S batteries.
Nanofiltration‐Enabled In Situ Solvent and Reagent Recycle for Sustainable Continuous‐Flow Synthesis
Authors: Fodi Tamas , Didaskalou Christos , Kupai Jozsef , Balogh Gyorgy T. , Huszthy Peter , Szekely Gyorgy 
Published: July 2017

AbstractSolvent usage in the pharmaceutical sector accounts for as much as 90 % of the overall mass during manufacturing processes. Consequently, solvent consumption poses significant costs and environmental burdens. Continuous processing, in particular continuous‐flow reactors, have great potential for the sustainable production of pharmaceuticals but subsequent downstream processing remains challenging. Separation processes for concentrating and purifying chemicals can account for as much as 80 % of the total manufacturing costs. In this work, a nanofiltration unit was coupled to a continuous‐flow rector for in situ solvent and reagent recycling. The nanofiltration unit is straightforward to implement and simple to control during continuous operation. The hybrid process operated continuously over six weeks, recycling about 90 % of the solvent and reagent. Consequently, the E‐factor and the carbon footprint were reduced by 91 % and 19 %, respectively. Moreover, the nanofiltration unit led to a solution of the product eleven times more concentrated than the reaction mixture and increased the purity from 52.4 % to 91.5 %. The boundaries for process conditions were investigated to facilitate implementation of the methodology by the pharmaceutical sector.
The Neurotensin NTS1 Receptor Agonist PD149163 Produces Antidepressant‐Like Effects in the Forced Swim Test: Further Support for Neurotensin as a Novel Pharmacologic Strategy for Antidepressant Drugs
Authors: Carey Lawrence M. , Rice Remington J. , Prus Adam J. 
Published: July 2017

ABSTRACT

Preclinical Research

Neurotensin is a nonbrain penetrant neuropeptide neurotransmitter that alters dopaminergic and serotonergic neurotransmission. Previous animal behavioral studies have demonstrated that intra‐ventral tegmental administration of neurotensin and system administration of the selective neurotensin NTS1 receptor agonist, PD149163 produce antidepressant‐like effects in a forced swim test and a differential reinforcement of low rate task, respectively. The present study sought to expand upon these past findings by assessing systemic administration of PD149163 in a forced swim test, a primary antidepressant preclinical screening model, in mice. The tricyclic antidepressant drug imipramine was tested for comparison, and both compounds were also assessed in an open field test. Both PD149163 and imipramine reduced time spent immobile, an antidepressant‐like effect, in the forced swim test. The highest dose of each compound significantly reduced locomotor activity. These findings provide further evidence for the putative antidepressant effects for PD149163 and suggest that NTS1 receptor activation may be a novel pharmacologic strategy for antidepressant drug development. Drug Dev Res 78 : 196–202, 2017. © 2017 Wiley Periodicals, Inc.
Antinociceptive Activity of Ent‐Dihydrotucumanoic Acid Isolated from Gymnosperma glutinosum Spreng Less
Authors: Alonso‐Castro Angel Josabad , González‐Chávez Marco Martin , Zapata‐Morales Juan Ramón , Verdinez‐Portales Alexia Karina , Sánchez‐Recillas Amanda , Ortiz‐Andrade Rolffy , Isiordia‐Espinoza Mario , Martínez‐Gutiérrez Fidel , Ramírez‐Morales Marco Antonio , Domínguez Fabiola , Juache‐Flores María Elizabeth , Martínez Roberto 
Published: July 2017

ABSTRACT

Preclinical Research

The diterpene ent‐dihydrotumanoic acid (DTA) was among the compounds isolated from Gymnosperma glutinosum (Spreng) Less (Asteraceae). There are no reports regarding the pharmacological effects of DTA. Cytotoxicity against cancer cells (1–250 µM), and the antibacterial (50–1400 µM) activity of DTA were evaluated using the MTT assay, and the minimum inhibitory concentration test, respectively. The antidiarrheal (1–100 mg/kg p.o.) and anti‐inflammatory (2 mg/ear) effects of DTA were evaluated using castor oil and 12‐O‐tetradecanoylphorbol‐13‐acetate, respectively. The antinociceptive and sedative effects of DTA (1–100 mg/kg p.o.) were evaluated using two models of chemically‐induced nociception, and the pentobarbital‐induced sleeping time test, respectively. The antinociceptive mechanism of DTA was evaluated using the acetic acid writhing test with inhibitors related to pain processing pathways. The effects of DTA (10–100 mg/kg p.o.) on locomotor activity were evaluated using the rotarod test. DTA lacked cytotoxic activity (IC50 > 100 µM) on cancer cells, possessed moderate antibacterial effects against B. subtillis (MIC= 175 µM), moderate antidiarrheal and anti‐inflammatory effects, and minimal vasorelaxant effects. In the formalin test, DTA showed antinociceptive effects in both phases. In the acetic acid test, DTA showed antinociceptive activity (ED50= 50.2 ± 5.6 mg/kg) with potency similar to that of naproxen (NPX; ED50=33.7 ± 4.5 mg/kg) an effect blocked by naloxone implicating an opioid mechanism. DTA also exerted antidiarrheal activity and showed no sedative effects or changes in locomotor activity in mice. Drug Dev Res 78 : 340‐348, 2017. © 2017 Wiley Periodicals, Inc.