bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnesium Stung by Nonclassical Scorpionate Ligands: Synthesis and Cone‐Angle Calculations
Authors: Stuhl Christoph , Maichle‐Mössmer Cäcilia , Anwander Reiner 
Published: July 2018

AbstractA series of tris(pyrazolyl)alkane (RCTp) scorpionate ligands of the type RCTp3‐R′ (R=Me, nBu, SiMe3; R′=H, Me, Ph, iPr, tBu) were synthesized and their ability to coordinate methylmagnesium moieties was examined. The reaction of Mg(AlMe4)2 with neutral proligands HCTp3‐Ph or Me3SiCTp3‐Me, containing a non‐innocent backbone methine moiety, led to deprotonation/rearrangement and SiMe3/AlMe3 exchange to afford [(Me3AlCTp3‐Ph)2Mg] and [(Me3AlCTp3‐Me)Mg(AlMe4)], respectively, with monoanionic tripodal ligands. Treatment of sterically less demanding RCTp3‐R′ with Mg(AlMe4)2 produced isostructural dicationic “metal‐in‐a‐box” complexes of the type [(RCTp3‐R′)2Mg][AlMe4]2 (R=Me, nBu; R′=H, Me). Utilization of the superbulky ligands MeCTp3‐Ph and MeCTp3‐tBu gave monocationic complexes [(MeCTp3‐Ph)MgMe][AlMe4] and [(MeCTp3‐tBu)MgMe][Al2Me7] as separated ion pairs. The reaction of Mg(AlMe4)2 with nBuCTp3‐Ph led to the formation of the dimagnesium complex [{(nBuCTp3‐Ph)Mg(AlMe4)}2(μ‐CH3)], which features a bridging methyl moiety and terminal η1‐coordinated tetramethylaluminato ligands. Isopropyl‐substituted ligand MeCTp3‐iPr emerged from further fine‐tuning of the steric and electronic parameters and, upon reaction with Mg(AlMe4)2, gave (MeCTp3‐iPr)Mg(AlMe4)2; this represents the first example of a magnesium bis(alkyl) complex with an intact RCTp3‐R′ ligand. The exact ligand cone angles Θ° of all magnesium complexes were determined according to the mathematical analysis developed by Allen et al. [J. Comput. Chem. 2013, 34, 1189–1197].
Carbon2Polymer – Conceptual Design of a CO2‐Based Process for the Production of Isocyanates
Authors: Kaiser Teresa , Rathgeb Andrea , Gertig Christoph , Bardow André , Leonhard Kai , Jupke Andreas 
Published: July 2018

AbstractThe capture of carbon dioxide and its utilization as a building block in chemical synthesis aim at reducing the depletion of fossil resources and the emission of greenhouse gases. The project Carbon2Chem®‐L5 is dedicated to the development of processes using CO2 for the production of polymer building blocks for polyurethanes. In this work, a process concept is presented for the CO2‐based synthesis of diisocyanates, the main starting material in polyurethane manufacture. Key parameters for process performance are discussed.
Fabrication of GaN(1−x)Asx, Zinc‐Blende, or Wurtzite GaN Depending on GaAs Nitridation Temperature in a CVD System
Authors: Ramírez‐González Francisco Sebastian , García‐Salgado Godofredo , Morales Crisóforo , Díaz Tomás , Rosendo Enrique , Nieto‐Caballero Fabiola Gabriela , Luna José Alberto , Coyopol Antonio , Romano Román , Galeazzi Reina 
Published: July 2018

AbstractThe study of GaN morphology and structure modification due to the variation of the nitridation temperature are reported. GaN is obtained by nitridation of GaAs (1 1 1) using the flow of a mixture of hydrogen and ammonia into a horizontal CVD system. The experiments are carried out at atmospheric pressures of 800, 900, and 1000 °C for 1 h. XRD results together with the pole figure indicate that GaN(1‐x)Asx is obtained at 800 °C, that zinc‐blende GaN structure is obtained at 900 °C, and that wurtzite GaN structure is obtained at 900 °C. The photoluminescence emission peak (obtained at room temperature) shifts to 420, 384, and 372 nm with the nitridation temperature change, in agreement with the XRD and pole figure results. SEM images show the morphology change, where GaN(1−x)Asx and GaN layers are obtained at 800 and 900 °C, respectively, while GaN columns are obtained at 1000 °C. The morphology and structure change due the nitridation temperature variation are also discussed based on the results.
Optimizing Mass Transfer Control Using a Stirring Paddle for the Rapid Growth of KDP Crystals
Authors: Hu Kaiwei , Zheng Lili , Zhang Hui , Chen Duanyang , Qi Hongji 
Published: July 2018

AbstractNumerical simulations are performed to study the rapid growth of potassium dihydrogen phosphate crystals with a designed stirring paddle. The paddle is expected to produce a downward flow and enhance mass transfer near the crystal surface. The effects of rotation rate and crystal size on downward flow speed are investigated. As the rotation rate and crystal size increase, the downward flow speed increases linearly. The mass transport in the turbulent boundary layer is analyzed, and the surface supersaturation is calculated theoretically. The solute supply can be guaranteed by controlling the rotation speed of the stirring paddle during crystal growth.
Technical comment—Ten fundamental principles on defining and expressing thermal exposure as boundary conditions in fire safety engineering
Authors: Wickström Ulf , Hunt Sean , Lattimer Brian , Barnett Jonathan , Beyler Craig 
Published: July 2018

SummaryPredicting the temperature of an exposed object or even a person is one of the most common tasks of fire safety engineering. However, the nonlinear nature of heat transfer and the challenge of changing material properties with temperature have plagued precise predictions. In addition, as methodologies are developed, one of the biggest challenges is to apply them to known scenarios where temperatures and heat fluxes have been measured. The interpretations of such measurements are, however, often clouded by the lack of common understanding of the reported values and how they shall be translated into boundary conditions to be used for calculations. This technical comment summarizes the Fundamental Principles that are crucial to properly identifying the fire exposure so that appropriate temperature predictions can be made.
Characterizing the heterogeneity of karst critical zone and its hydrological function: An integrated approach
Authors: Chen Xi , Zhang Zhicai , Soulsby Chris , Cheng Qinbo , Binley Andrew , Jiang Rui , Tao Min 
Published: July 2018

AbstractSpatial heterogeneity in the subsurface of karst environments is high, as evidenced by the multiphase porosity of carbonate rocks and complex landform features that result in marked variability of hydrological processes in space and time. This includes complex exchange of various flows (e.g., fast conduit flows and slow fracture flows) in different locations. Here, we integrate various “state‐of‐the‐art” methods to understand the structure and function of this poorly constrained critical zone environment. Geophysical, hydrometric, and tracer tools are used to characterize the hydrological functions of the cockpit karst critical zone in the small catchment of Chenqi, Guizhou Province, China. Geophysical surveys, using electrical resistivity tomography (ERT), inferred the spatial heterogeneity of permeability in the epikarst and underlying aquifer. Water tables in depression wells in valley bottom areas, as well as discharge from springs on steeper hillslopes and at the catchment outlet, showed different hydrodynamic responses to storm event rainwater recharge and hillslope flows. Tracer studies using water temperatures and stable water isotopes (δD and δ18O) could be used alongside insights into aquifer permeability from ERT surveys to explain site‐ and depth‐dependent variability in the groundwater response in terms of the degree to which “new” water from storm rainfall recharges and mixes with “old” pre‐event water in karst aquifers. This integrated approach reveals spatial structure in the karst critical zone and provides a conceptual framework of hydrological functions across spatial and temporal scales.
Assessment of alternative adsorption models and global sensitivity analysis to characterize hexavalent chromium loss from soil to surface runoff
Authors: Xia Chuan‐An , Tong Juxiu , Hu Bill X. , Wu Xiujie , Guadagnini Alberto 
Published: July 2018

AbstractWe investigate our ability to assess transfer of hexavalent chromium, Cr(VI), from the soil to surface runoff by considering the effect of coupling diverse adsorption models with a two‐layer solute transfer model. Our analyses are grounded on a set of two experiments associated with soils characterized by diverse particle size distributions. Our study is motivated by the observation that Cr(VI) is receiving much attention for the assessment of environmental risks due to its high solubility, mobility, and toxicological significance. Adsorption of Cr(VI) is considered to be at equilibrium in the mixing layer under our experimental conditions. Four adsorption models, that is, the Langmuir, Freundlich, Temkin, and linear models, constitute our set of alternative (competing) mathematical formulations. Experimental results reveal that the soil samples characterized by the finest grain sizes are associated with the highest release of Cr(VI) to runoff. We compare the relative abilities of the four models to interpret experimental results through maximum likelihood model calibration and four model identification criteria (i.e., the Akaike information criteria [AIC and AICC] and the Bayesian and Kashyap information criteria). Our study results enable us to rank the tested models on the basis of a set of posterior weights assigned to each of them. A classical variance‐based global sensitivity analysis is then performed to assess the relative importance of the uncertain parameters associated with each of the models considered, within subregions of the parameter space. In this context, the modelling strategy resulting from coupling the Langmuir isotherm with a two‐layer solute transfer model is then evaluated as the most skilful for the overall interpretation of both sets of experiments. Our results document that (a) the depth of the mixing layer is the most influential factor for all models tested, with the exception of the Freundlich isotherm, and (b) the total sensitivity of the adsorption parameters varies in time, with a trend to increase as time progresses for all of the models. These results suggest that adsorption has a significant effect on the uncertainty associated with the release of Cr(VI) from the soil to the surface runoff component.
Novel amides of 1,1‐bis‐(carboxymethylthio)‐1‐arylethanes: Synthesis, characterization, acetylcholinesterase, butyrylcholinesterase, and carbonic anhydrase inhibitory properties
Authors: Taslimi Parham , Osmanova Sabiya , Caglayan Cuneyt , Turkan Fikret , Sardarova Sabira , Farzaliyev Vagif , Sujayev Afsun , Sadeghian Nastaran , Gulçin İlhami 
Published: July 2018

AbstractThe thiolation reaction was carried out in a benzene solution at 80°C and p‐substituted ketones and mercaptoacetic acid in a molar ratio (1:4) of in the presence of a catalytic amount of toluene sulfonic acids. The enzyme inhibition activities of the novel amides of 1,1‐bis‐(carboxymethylthio)‐1‐arylethanes derivatives were investigated. These novel amides of 1,1‐bis‐(carboxymethylthio)‐1‐arylethanes derivatives showed good inhibitory action against acetylcholinesterase (AChE) butyrylcholinesterase (BChE), and human carbonic anhydrase I and II isoforms (hCA I and II). AChE inhibitors, interacting with the enzyme as their primary target, are applied as relevant drugs and toxins. Many clinically established drugs are carbonic anhydrase inhibitors, and it is highly anticipated that many more will eventually find their way into the market. The novel synthesized compounds inhibited AChE and BChE with Ki values in the range of 0.64–1.47 nM and 9.11–48.12 nM, respectively. On the other hand, hCA I and II were effectively inhibited by these compounds, with Ki values between 63.27–132.34 and of 29.63–127.31 nM, respectively.
The synthesis of N‐benzoylindoles as inhibitors of rat erythrocyte glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase
Authors: Bayindir Sinan , Temel Yusuf , Ayna Adnan , Ciftci Mehmet 
Published: July 2018

AbstractGlucose‐6‐phosphate dehydrogenase (G6PD) and 6‐phosphogluconate dehydrogenase (6PGD) play an important function in various biochemical processes as they generate reducing power of the cell. Thus, metabolic reprogramming of reduced nicotinamide adenine dinucleotide phosphate (NADPH) homeostasis is reported to be a vital step in cancer progression as well as in combinational therapeutic approaches. In this study, N‐benzoylindoles 9a‐‐9d, which form the main framework of many natural indole derivatives such as indomethacin and N‐benzoylindoylbarbituric acid, were synthesized through three easy and effective steps as an in vitro inhibitor effect of G6PD and 6PGD. The N‐benzoylindoles inhibited the enzymatic activity with IC50 in the range of 3.391505 μM for G6PD and 2.19–990 μM for 6PGD.
Association of CD28 and CTLA4 haplotypes with susceptibility to primary Sjögren′s syndrome in Mexican population
Authors: López‐Villalobos Erika Fabiola , Carrillo‐Ballesteros Francisco Josué , Muñoz‐Valle José Francisco , Palafox‐Sánchez Claudia Azucena , Valle Yeminia , Orozco‐Barocio Gerardo , Oregon‐Romero Edith 
Published: July 2018

BackgroundPrimary Sjögren's syndrome (pSS) is an autoimmune disease characterized by destruction of exocrine glands as a result of T and B cells infiltrated in glandular tissue. CD28 and CTLA‐4 play a crucial role in T cell activation and inhibition. The aim of this study was to associate CD28 and CTLA4 haplotypes with susceptibility to pSS in patients from western Mexico.MethodsPolymerase chain reaction and restriction fragment length polymorphism were performed to identify CD28 and CTLA4 genotypes in 111 patients with pSS and 138 control subjects (CS). Haplotype analysis was carried out by SHEsis program. Soluble serum levels of CD28 (sCD28) and CTLA‐4 (sCTLA‐4) were quantified by ELISA kit.ResultsThe CD28 GC haplotype was associated with low risk to pSS (2.5‐folds, P < 0.001). CTLA4 CAG and CGA were identified as genetic risk factor (P < 0.001;OR = 3.82[CI95%:2.022‐7.296] and P < 0.001; OR = 11.38[CI95%:3.282‐37.69] respectively). No difference in sCD28 and sCTLA‐4 were found between patients and CS. However, pSS patients carriers of CD28 IVS3 + 17TC genotype showed high sCD28 (P = 0.039 vs TT carriers in CS). In regard to sCTLA‐4, patient who carry CTLA4‐319C>T, +49 A>G, and +6230 G>A, or their haplotypes did not show any difference.ConclusionOur findings suggest that CD28 GC, CTLA4 CAG, and CGA haplotypes are associated with susceptibility to pSS in patients from western Mexico. It seems that genetic control of CD28 and CTLA4 as well as local immune response in glandular tissue may regulate the impact of the gene expression in pSS. It is necessary to confirm this hypothesis in an integrative study.
An optimized culture system for notochordal cell expansion with retention of phenotype
Authors: Humphreys Matthew D. , Ward Lizzy , Richardson Stephen M. , Hoyland Judith A. 
Published: July 2018

BackgroundNotochordal (NC) cells display therapeutic potential in treating degeneration of the intervertebral disc. However, research on their phenotype and function is limited by low‐cell yields and a lack of appropriate methodology for cell expansion. Utilizing porcine cells, this study aimed to develop an optimized culture system which allows expansion of NC cell populations with retention of phenotype.MethodsPost‐natal porcine and foetal human nucleus pulposus tissue was compared histologically and expression of known NC cell marker genes by porcine NC cells was analyzed. Porcine NC cells were isolated from six‐week post‐natal discs and cultured in vitro under varied conditions: (1) DMEM vs αMEM; (2) laminin‐521, fibronectin, gelatin and uncoated tissue culture‐treated polystyrene (TCP); (3) 2% O2 vs normoxia; (4) αMEM (300 mOsm/L) vs αMEM (400 mOsm/L); (5) surface stiffness of 0.5 and 4 kPa and standard TCP. Adherence, proliferation, morphology and expression of NC cell markers were assessed over a 14‐day culture period.ResultsNative porcine nucleus pulposus tissue demonstrated similar morphology to human foetal tissue and porcine NC cells expressed known notochordal markers (CD24, KRT8, KRT18, KRT19, and T). Use of αMEM media and laminin‐521‐coated surfaces showed the greatest cell adherence, proliferation and retention of NC cell morphology and phenotype. Proliferation of NC cell populations was further enhanced in hypoxia (2%) and phenotypic retention was improved on 0.5 kPa culture surfaces.DiscussionOur model has demonstrated an optimized system in which NC cell populations may be expanded while retaining a notochordal phenotype. Application of this optimized culture system will enable NC cell expansion for detailed phenotypic and functional study, a major advantage over current culture methods described in the literature. Furthermore, the similarities identified between porcine and human NC cells suggest this system will be applicable in human NC cell culture for investigation of their therapeutic potential.
Droplet‐Based Microfluidic Templating of Polyglycerol‐Based Microgels for the Encapsulation of Cells: A Comparative Study
Authors: Kapourani Era , Neumann Falko , Achazi Katharina , Dernedde Jens , Haag Rainer 
Published: July 2018

AbstractCell microencapsulation holds great promise as a therapeutic strategy for the controlled and sustained delivery of biologically relevant agents. The authors developed cell‐laden microgel scaffolds with excellent long‐term viabilities by combining bioorthogonal strain promoted azide–alkyne cycloaddition (SPAAC) and droplet‐based microfluidic templating. Star‐shaped polyglycerol hexaazide, α,ω‐bis azido‐linear polyglycerol or polyethylene glycol as well as dendritic polyglycerol‐(polycyclooctyne) served as bioinert hydrogel precursors. The authors demonstrate for the first time the generation of entirely polyglycerol‐based microcapsules with excellent stability and full retention of viability of the packed cells for longer than 3 weeks. As a result, our microgel particles could be used for long‐term immunoisolation of cells enabling their study during encapsulation.
Synthesis of Alkyl‐Substituted Quinoxaline‐Based Copolymers Along with Photophysical Property Modulation for Polymer Solar Cells
Authors: Kang Yeongkwon , Agneeswari Rajalingam , Lee Jihoon , Kwon Ji Hyeon , Tamilavan Vellaiappillai , Park Seong Soo , Park Sung Heum , Jin Youngeup 
Published: July 2018

AbstractA series of alkyl‐substituted quinoxaline‐based copolymers are prepared and their properties are studied. Stille copolymerization of 2,5‐bis(trimethylstannyl)thiophene (M3) with different ratios of 2,7‐dibromo‐9,9‐dioctyl‐9H‐fluorene (M4) and 5,8‐dibromo‐6,7‐difluoro‐2,3‐didodecylquinoxaline (M1) affords five new random copolymers, labeled P1–P5. Suzuki copolymerization of 4,5,5‐tetramethyl‐2‐[2‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)‐9,9‐dioctyl‐9H‐fluoren‐7‐yl]‐1,3,2‐dioxaborolane (M5) and 5,8‐bis(5‐bromothiophen‐2‐yl)‐2,3‐didodecyl‐6,7‐difluoroquinoxaline (M2) yielded a new alternating copolymer, labeled P6. All copolymers show high thermal stability, and the 5% weight loss temperature is above 400 °C. The estimated optical bandgap (E
g) values of random copolymers P1–P5 (E
g ≈ 1.93, 1.97, 1.97, 2.02, and 2.08 eV, respectively) are found to be relatively lower than that of alternating copolymer P6 (E
g ≈ 2.14 eV). All copolymers P1–P6 exhibit deep highest occupied molecular orbital (HOMO) energy levels, and the determined HOMO levels are −5.65, −5.67, −5.67, −5.60, −5.59, and −5.66 eV, respectively. The maximum power conversion efficiencies of polymer solar cells made with individual copolymers P1–P6 as a donor materials and PC70BM as an acceptor are 3.98, 2.91, 3.33, 3.55, 3.07, and 2.78%, respectively.
Enhancement of Mechanical Properties of FDM‐PLA Parts via Thermal Annealing
Authors: Wach Radoslaw A. , Wolszczak Piotr , Adamus‐Wlodarczyk Agnieszka 
Published: July 2018

AbstractThe objective of this study is to investigate the possibility of enhancing mechanical properties of poly(lactic acid) (PLA) samples processed by a rapid manufacturing (RM) technique by increasing PLA crystallinity degree via thermal annealing. The samples are manufactured by fused deposition modeling (FDM) at different temperatures and subsequently evaluated by three‐point bending flexural and tensile tests. The polymer processed at 215 °C is thermally annealed over its glass transition temperature in order to increase the degree of crystallinity to the maximum attainable level as measured by the differential scanning calorimetry and confirmed by X‐ray diffraction. The increase in the degree of crystallinity of FDM‐PLA enhances flexural stress of the samples by 11–17%. The study also demonstrates applicability of radiation sterilization for FDM‐PLA parts. Therefore, thermal annealing might be introduced into a standard RM technology of PLA, particularly for sterilizable customized implants, to efficiently improve their mechanical properties.
Understanding medicines with a propensity to increase the risk of heart failure: Combining existing knowledge with targeted population assessment
Authors: Tomlin Andrew M. , Woods David J. , Lloyd Hywel S. , Stewart Ralph A.H. , Tilyard Murray W. 
Published: July 2018

AbstractPurposeExisting knowledge of medicines that increase the risk of an adverse event may be corroborated and augmented by population studies specifically assessing the risk associated with the concurrent use of these medicines and use by patients with existing comorbidity. An American Heart Association review recently identified a variety of medicines that may cause or exacerbate heart failure (HF), many with evidence from limited evaluation of population data. We assessed the risk of first‐time HF associated with the use of 50 of these medicines by New Zealand's primary care population.MethodsCase‐control study utilising national pharmaceutical use and hospital admissions data 2007‐2015; 22,989 patients with first‐time HF 2008‐2015 were matched with 114 498 control patients. The primary outcome was first‐time HF and its association with medicine exposure in the prior 90 days, estimated using conditional logistic regression. We also assessed the risk associated with new use of medicines in the prior month, concurrent use, and in patients with existing comorbidity.ResultsEleven medicines were significantly associated with HF with several other infrequently used medicines providing signals of increased risk. A high risk was associated with the use of salbutamol (adjusted odds ratio 2.63; 95% CI, 2.48‐2.78), clozapine (2.70; 2.46‐4.98), diltiazem (1.52; 1.44‐1.60), indomethacin (2.51; 1.54‐4.10), pioglitazone (1.50; 1.16‐1.95), and antifungal medicines. New use of medicines and use of medicine combinations increased this risk in many cases.ConclusionsOur study provides further evidence to inform cautious use of these medicines in patients with HF or at risk of developing HF.