bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of melt composition on crustal carbonate assimilation: Implications for the transition from calcite consumption to skarnification and associated CO2 degassing
Authors: Carter Laura B. , Dasgupta Rajdeep 
Published: September 2016

AbstractSkarns are residue of relatively low‐temperature magma‐induced decarbonation in the crust largely associated with silicic plutons. Mafic magmatic intrusions are also capable of releasing excess CO2 due to carbonate assimilation. However, the effect of mafic to silicic melt evolution on the decarbonation processes, in addition to temperature controls on carbonate‐intrusive magmatic systems, particularly at continental arcs, remains unclear. In this study, experiments performed in a piston cylinder apparatus at midcrustal depth (0.5 GPa) at supersolidus temperatures (900–1200°C) document calcite interaction with andesite and dacite melts at equilibrium under closed‐system conditions at calcite saturation in a 1:1 melt‐calcite ratio by weight. With increasing silica content in the starting melt, at similar melt fractions and identical pressure, assimilation decreases drastically (≤65% andesite‐calcite to ≤18% dacite‐calcite). In conjunction, the CaO/SiO2 ratio in melts resulting from calcite assimilation in andesitic starting material is >1, but ≤0.3 in those formed from dacite‐calcite interaction. With increasing silica‐content in the starting melt skarn mineralogy, particularly wollastonite, increases in modal abundance while diopsidic clinopyroxene decreases slightly. More CO2 is released with andesite‐calcite reaction (≤2.9 × 1011 g/y) than with more skarn‐like dacite‐calcite interaction (≤8.1 × 1010 g/y, at one volcano assuming respective calcite‐free‐superliquidus conditions and a magma flux of 1012 g/y). Our experimental results thus suggest that calcite assimilation in more mafic magmas may have first degassed a significant amount of crustal carbon before the melt evolves to more silicic compositions, producing skarn. Crustal decarbonation in long‐lived magmatic systems may hence deliver significant albeit diminishing amounts of carbon to the atmosphere and contribute to long‐term climate change.
Contribution of viscoelastic flow in earthquake cycles within the lithosphere‐asthenosphere system
Authors: Lambert Valère , Barbot Sylvain 
Published: September 2016

AbstractFaults slip relaxes lithospheric stress imposed by mantle flow and in turn transfers stress to the ductile regions. The interplay of these systems governs the style of deformation at plate boundaries including the recurrence of seismic events. However, such deep processes remain challenging to incorporate in numerical simulations of earthquake cycles. Here we propose a model that couples fault slip and viscoelastic deformation to simulate fault dynamics in the lithosphere‐asthenosphere system. Our method resolves all phases of the earthquake cycle, including dynamic rupture propagation, afterslip, slow‐slip events, and the modulation of strain rate incurred in the ductile regions. Transient strain accelerations in the asthenosphere may follow both earthquakes and slow‐slip events shortly after the rupture, depending on the rheology of the upper mantle and the magnitude of the event. This study opens the door to greater insight into the variability of earthquake cycles by incorporating the dynamics of distributed deformation.
Precipitation variation over eastern China and arid central Asia during the past millennium and its possible mechanism: Perspectives from PMIP3 experiments
Authors: Shi Jian , Yan Qing , Jiang Dabang , Min Jinzhong , Jiang Ying 
Published: September 2016

AbstractMultiproxies suggest a tripole humidity pattern in Asia in the Medieval Climate Anomaly (MCA, 950–1250 A.D.) and Little Ice Age (LIA, 1500–1800 A.D.), with drier (wetter) conditions in arid central Asia (ACA), wetter (drier) conditions in North China, and drier (wetter) conditions in South China. However, the mechanisms behind this reconstructed humidity variation remain unclear. In this study, we investigate Asian humidity changes by using the last millennium simulations of the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3). The results indicate that only one out of nine PMIP3 models (Meteorological Research Institute Coupled ocean‐atmosphere General Circulation Model version 3) can well reproduce the reconstructed humidity pattern. This model indicates that the tripole humidity pattern is mainly caused by precipitation changes in spring and summer and is prominent in the past millennium on a multidecadal time scale. In spring, the reduction (increase) of precipitation in ACA and South China is attributed to the northward (southward) shift of the westerlies and a weakened (strengthened) western Pacific subtropical high in the MCA (LIA). In summer, precipitation over ACA decreases (increases) due to a local descending (ascending) motion, while abundant (deficient) precipitation over eastern China results from the enhanced (depressed) summer monsoon. Moreover, we suggest that a La Niña (El Niño)‐like condition may be the primary reason the tripole precipitation pattern was maintained in the MCA (LIA), although a warmer (colder) North Pacific and North Atlantic also play a role. The mechanisms must be further validated since most simulations fail to reproduce the reconstructed humidity condition in the MCA/LIA, making model‐model comparisons difficult.
Iodide/tert‐Butyl Hydroperoxide‐Mediated Benzylic C–H Sulfonylation and Peroxidation of Phenol Derivatives
Authors: Yang Wen‐Chao , Dai Peng , Luo Kai , Wu Lei 
Published: September 2016

AbstractWe disclose here the first iodine/tert‐butyl hydroperoxide (I2/TBHP)‐mediated benzylic C–H sulfonylation of phenol derivatives. This new methodology provides an economic, operationally simple and metal‐free approach toward C(sp3)–S bond formation with medium to excellent yields at room temperature. Moreover, a novel sulfonylative and peroxidative bifunctionalization of phenol derivatives was also achieved by changing the amount of the oxidant. The reaction mechanism is exemplified via a radical pathway.magnified image
Iron(III)‐Catalyzed Peroxide‐Mediated C‐3 Functionalization of Flavones
Authors: Mir Bilal Ahmad , Banerjee Arghya , Santra Sourav Kumar , Rajamanickam Suresh , Patel Bhisma K. 
Published: September 2016

AbstractAn iron(III)‐catalyzed C‐3 functionalization of flavones has been achieved using tert‐butyl peroxybenzoate (TBPB)/potassium persulphate (K2S2O8) oxidant combinations with a suitable solvent. In the presence of iron(III)/tert‐butyl peroxybenzoate/potassium persulphate, the reaction of flavones in cycloalkanes afforded exclusive C‐3 cycloalkylation via C
–C
coupling, whereas the solvent N,N‐dialkylformamide provided C‐3 amidation via C
–C
coupling. Under identical reaction conditions just by switching the solvent to chlorobenzene, C‐3 methylated flavones were obtained where tert‐butyl peroxybenzoate (TBPB) served as the source of the methyl group.magnified image
The Construction of Anhydro Monosaccharides
Authors: Xie Weijia , Lin Aijun , Xu Jinyi , Wu Xiaoming 
Published: September 2016

AbstractAnhydro monosaccharide is a specific and distinctive category of carbohydrates, which is found in many naturally derived and artificial bioactive substrates. In the field of organic chemistry, some anhydro sugars can be used as common synthons to construct different carbohydrate structures. The development of efficient methodologies for the construction of various anhydro sugar fragments is very important in carbohydrate chemistry, which has attracted considerable attention in the past few years. This review mainly covers the development of new synthetic methods since 2000 and gives an overview of the development in the formation of anhydro monosaccharide structures. It systematically summarizes all methods to establish an intramolecular ether bridge in furanose and pyranose structures, which are the most commonly used monosaccharide fragments in carbohydrate chemistry.
Organocatalyzed Assembly of Chlorinated Quaternary Stereogenic Centers
Authors: Gómez‐Martínez Melania , Alonso Diego A. , Pastor Isidro M. , Guillena Gabriela , Baeza Alejandro 
Published: September 2016

AbstractThe catalytic asymmetric construction of chiral quaternary stereocenters is a continual area of research for organic chemists. In this sense, when a chlorine atom is introduced to a quaternary stereocenter, the synthetic difficulty of the resulting molecule increases along with its significance. This is true not only because of the intrinsic interest in such chlorinated molecules but also because they are highly valuable chiral building blocks in organic synthesis, as they can be converted into more complex molecules by a SN2 displacement reaction. Among the different strategies to create chlorinated quaternary stereogenic centers, organocatalysis has played a pivotal role over the past decade. In this review, a comprehensive analysis of such organocatalyzed transformations with a focus on the α‐chlorination of carbonyl compounds is presented.
An Integrated Chemical Cytometry Method: Shining a Light on Akt Activity in Single Cells
Authors: Mainz Emilie R. , Wang Qunzhao , Lawrence David S. , Allbritton Nancy L. 
Published: September 2016

AbstractTools to evaluate oncogenic kinase activity in small clinical samples have the power to guide precision medicine in oncology. Existing platforms have demonstrated impressive insights into the activity of protein kinases, but these technologies are unsuitable for the study of kinase behavior in large numbers of primary human cells. To address these limitations, we developed an integrated analysis system that utilizes a light‐programmable, cell‐permeable reporter deliverable simultaneously to many cells. The reporter's ability to act as a substrate for Akt, a key oncogenic kinase, was masked by a 2‐4,5‐dimethoxy 2‐nitrobenzyl (DMNB) moiety. Upon exposure to ultraviolet light and release of the masking moiety, the substrate sequence enabled programmable reaction times within the cell cytoplasm. When coupled to automated single‐cell capillary electrophoresis, statistically significant numbers of primary human cells were readily evaluated for Akt activity.
Biocatalytic Synthesis of Allylic and Allenyl Sulfides through a Myoglobin‐Catalyzed Doyle–Kirmse Reaction
Authors: Tyagi Vikas , Sreenilayam Gopeekrishnan , Bajaj Priyanka , Tinoco Antonio , Fasan Rudi 
Published: September 2016

AbstractThe first example of a biocatalytic [2,3]‐sigmatropic rearrangement reaction involving allylic sulfides and diazo reagents (Doyle–Kirmse reaction) is reported. Engineered variants of sperm whale myoglobin catalyze this synthetically valuable C−C bond‐forming transformation with high efficiency and product conversions across a variety of sulfide substrates (e.g., aryl‐, benzyl‐, and alkyl‐substituted allylic sulfides) and α‐diazo esters. Moreover, the scope of this myoglobin‐mediated transformation could be extended to the conversion of propargylic sulfides to give substituted allenes. Active‐site mutations proved effective in enhancing the catalytic efficiency of the hemoprotein in these reactions as well as modulating the enantioselectivity, resulting in the identification of the myoglobin variant Mb(L29S,H64V,V68F), which is capable of mediating asymmetric Doyle–Kirmse reactions with an enantiomeric excess up to 71 %. This work extends the toolbox of currently available biocatalytic strategies for the asymmetric formation of carbon–carbon bonds.
Transforming LiTMP Lithiation of Challenging Diazines through Gallium Alkyl Trans‐Metal‐Trapping
Authors: Uzelac Marina , Kennedy Alan R. , Hevia Eva , Mulvey Robert E. 
Published: September 2016

AbstractThis study establishes a new trans‐metal‐trapping (TMT) procedure based on a mixture of LiTMP (the base) and tris(trimethylsilylmethyl)gallium [Ga(CH2SiMe3)3, GaR3] (the trap) that, operating in a tandem manner, is effective for the regioselective deprotonation of sensitive diazines in hydrocarbon solution, as illustrated through reactions of pyrazine, pyridazine, and pyrimidine, as well as through the N‐S heterocycle benzothiazole. The metallo‐activated complexes of all of these compounds were isolated and structurally defined.
Hidden Hydride Transfer as a Decisive Mechanistic Step in the Reactions of the Unligated Gold Carbide [AuC]+ with Methane under Ambient Conditions
Authors: Li Jilai , Zhou Shaodong , Schlangen Maria , Weiske Thomas , Schwarz Helmut 
Published: September 2016

AbstractThe reactivity of the cationic gold carbide [AuC]+ (bearing an electrophilic carbon atom) towards methane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). The product pairs generated, that is, Au+/C2H4, [Au(C2H2)]+/H2, and [C2H3]+/AuH, point to the breaking and making of C−H, C−C, and H−H bonds under single‐collision conditions. The mechanisms of these rather efficient reactions have been elucidated by high‐level quantum‐chemical calculations. As a major result, based on molecular orbital and NBO‐based charge analysis, an unprecedented hydride transfer from methane to the carbon atom of [AuC]+ has been identified as a key step. Also, the origin of this novel mechanistic scenario has been addressed. The mechanistic insights derived from this study may provide guidance for the rational design of carbon‐based catalysts.
BOIMPYs: Rapid Access to a Family of Red‐Emissive Fluorophores and NIR Dyes
Authors: Patalag Lukas J. , Jones Peter G. , Werz Daniel B. 
Published: September 2016

AbstractA fundamental, highly fluorescent, and easily accessible scaffold derived from the BODIPY core is reported. The use of benzimidazole as a bridging ligand at the meso position enables the binding of two BF2 units to provide sufficient rigidity and enhanced electron‐withdrawing strength. Absorption and emission events thus take place in the red (λ≈600 nm); the fluorescence quantum yields can reach unity (0.96) and show little dependence on solvent polarity. The synthetic route was shortened to two steps starting from commercially available precursors while the preparation is modular and tolerates various pyrrole and benzimidazole moieties. Fluoride replacement by propynyl groups, various halogenations, as well as Knoevenagel‐type condensations were applied to extend the versatility of these new photostable fluorophores, which we termed BOIMPYs.
Understanding the Central Location of a Hexagonal Hole in a B36 Cluster
Authors: Liu Lei , Osorio Edison , Heine Thomas 
Published: September 2016

AbstractThe most stable form of a B36 cluster has a central hexagonal hole. Such an interesting finding has led to the possible synthesis of a 2D boron sheet by employing the B36 cluster as the building unit. Herein, a DFT study to investigate the reason for the central location of the hexagonal hole in the B36 cluster is presented. The results show that the B36 cluster with a central hexagonal hole is highly thermodynamically and kinetically stable. More importantly, such high stability is further understood through chemical bonding analysis.
Detecting the structure of marine atmospheric boundary layer over the Northern South China Sea by shipboard GPS sondes
Authors: Peng Shiqiu , Zhu Yuhang , Huang Ke , Ding Xuanru , Shi Rui , Wu Dongmei , Feng Yerong , Wang Dongxiao 
Published: September 2016

AbstractGlobal Positioning System (GPS) sondes has been launched over the Northern South China Sea (NSCS) during the marine survey cruise each summer since 2006. These GPS‐sounding data provide a great opportunity to monitor the vertical structure of marine atmospheric boundary layer (MABL) which is very important to the high‐impact weather systems influencing the coastal regions. Our analysis on these GPS soundings reveals that the vertical structure of MABL over the NSCS is apparently correlated with the surface atmospheric stability. These MABL observations collected by GPS sondes are quite valuable for the forecasting of high‐impact weather systems in the coastal regions of the southern China.
From lignocellulosic metagenomes to lignocellulolytic genes: trends, challenges and future prospects
Authors: Batista‐García Ramón A. , del Rayo Sánchez‐Carbente María , Talia Paola , Jackson Stephen A. , O'Leary Niall D. , Dobson Alan D. W. , Folch‐Mallol Jorge Luis 
Published: September 2016

AbstractLignocellulose is the most abundant biomass on Earth with immense potential to act as a primary resource for the production of a range of compounds currently obtained from fossil fuel sources. However, lignocellulosic feedstocks remain largely underexploited due to the complex mixture of recalcitrant polymers present, whose structural features hinder access to the utilizable monosaccharide reservoir within cellulose. Various fungi and bacteria have been identified that can enzymatically decompose lignocellulose to its monomeric compounds for use as carbon sources. The investigation of such lignocellulolytic organisms has proven very useful in gaining primary insights into degradation processes and key microbial enzymes, but the established limitations of culture‐based approaches suggest that we have yet to understand the full range of lignocellulolytic mechanisms, likely expressed within natural systems. In this review, we focus on metagenomic approaches to study lignocellulose degradation from structural and functional perspectives, which may provide novel insights into this process in order to rationally design methods for the extraction of compounds from biomass that could enhance biorefinery efficiencies. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd
Biodiesel program in Brazil: learning curve over ten years (2005–2015)
Authors: Nogueira Luiz A.H. , Capaz Rafael S. , Souza Simone P. , Seabra Joaquim E.A. 
Published: September 2016

AbstractThe biodiesel blending mandate was launched at 2005 in Brazil, by a governmental program based mainly on sustainability concerns, especially toward social and environmental aspects. Since 2007, B7, i.e., 7% biodiesel in diesel, in volume terms, has been mandatory, and B10 is the next target. In this context, this paper aims to evaluate the biodiesel program along the ten years from 2005 to 2015 in Brazil, considering the evolution of the estimated costs and the auction prices intending to verify some tendency in a learning curve perspective. A decreasing tendency of the biodiesel production costs and prices was observed, with a reduction of the profit margin in recent years, suggesting a learning trend. The Progress Ratio (PR) of the whole period was 101.7%, but in the 2011–2015, it was estimated at 59.3%. Relevant technology changes in biodiesel production process were not verified, but the increased competitiveness in the market, the gains of scale of plant profiles, and mainly the decrease of soybean oil prices explain this evolution. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd
Evaluating side effects of nanoparticle‐mediated siRNA delivery to mesenchymal stem cells using next generation sequencing and enrichment analysis
Authors: Malcolm Dominic W. , Sorrells Janet E. , Van Twisk Daniel , Thakar Juilee , Benoit Danielle S. W. 
Published: September 2016

AbstractRNA interference has immense potential to modulate cell functions. However, effective delivery of small interfering RNA (siRNA) while avoiding deleterious side effects has proven challenging. This study investigates both intended and unintended effects of diblock copolymer nanoparticle (NP) delivery of siRNA delivery to human mesenchymal stem cells (hMSC). Specifically, siRNA delivery was investigated at a range of NP‐siRNA:hMSC ratios with a focus on the effects of NP‐siRNA treatment on hMSC functions. Additionally, next generation RNA sequencing (RNAseq) was used with enrichment analysis to observe side effects in hMSC gene expression. Results show NP‐siRNA delivery is negatively correlated with hMSC density. However, higher NP‐siRNA:hMSC ratios increased cytotoxicity and decreased metabolic activity. hMSC proliferation was largely unaffected by NP‐siRNA treatment, except for a threefold reduction in hMSCs seeded at 4,000 cells/cm2. Flow cytometry reveals that apoptosis is a function of NP‐siRNA treatment time and seeding density; ∼14% of the treated hMSCs seeded at 8,000 cells/cm2 were annexin V+‐siRNA+ 24 hr after treatment, while 11% of the treated population was annexin V+‐siRNA−. RNAseq shows that NP‐siRNA treatment results in transcriptomic changes in hMSCs, while pathway analysis shows upregulation of apoptosis signaling and downregulation of metabolism, cell cycle, and DNA replication pathways, as corroborated by apoptosis, metabolism, and proliferation assays. Additionally, multiple innate immune signaling pathways such as toll‐like receptor, RIG‐I‐like receptor, and nuclear factor‐κB signaling pathways are upregulated. Furthermore, and consistent with traditional siRNA immune activation, cytokine–cytokine receptor signaling was also upregulated. Overall, this study provides insight into NP‐siRNA:hMSC ratios that are favorable for siRNA delivery. Moreover, NP‐siRNA delivery results in side effects across the hMSC transcriptome that suggest activation of the innate immunity that could alter MSC functions associated with their therapeutic potential.
Electrochemical Monitoring of Hydrogen Sulfide Release from Single Cells
Authors: Hu Xue‐Bo , Liu Yan‐Ling , Zhang Hai‐Wei , Xiao Chong , Qin Yu , Duo Huan‐Huan , Xu Jia‐Quan , Guo Shan , Pang Dai‐Wen , Huang Wei‐Hua 
Published: September 2016

AbstractReal‐time and in situ monitoring of H2S in biological systems has become crucial, but faces big challenges as H2S has been identified as an important endogenous gas signaling molecule. Herein, we prepare a poly(3,4‐ethylenedioxythiophene) (PEDOT)‐modified nanoporous gold (NPG) microelectrode for the electrochemical detection of H2S. The NPG framework possesses excellent conductivity, a 3D porous structure, and a large specific area. The PEDOT sensing film effectively retards electrode fouling during the detection, which ensures a stable response towards H2S over the range of interest. The synergetic properties of the NPG scaffold and the PEDOT sensing films endow the microelectrode with high sensitivity and a fast response, thus allowing H2S release from single cells to be monitored. This work represents the first step toward real‐time electrochemical monitoring of H2S from single cells, thereby potentially facilitating future studies to better understand the function of H2S in biological and pathological processes.
Kinetics of VIII and VII Sulfate Precipitation Processes in Negative Half‐Cell Electrolyte of the Vanadium Redox Flow Battery
Authors: Mousa Asem , Skyllas‐Kazacos Maria 
Published: September 2016

AbstractThe low‐temperature stability and precipitation behaviour of VIII and VII sulfate solutions are critical for the optimal operation of vanadium redox flow batteries. In this study, the kinetics of the VIII and VII sulfate precipitation processes have been studied at different temperatures and sulfate concentrations. Kinetic studies of the precipitation of stagnant vanadium(III) sulfate solutions followed a first‐order rate law with rate constants on the order of 0.007 h−1 and an activation energy of about 14.6 kJ mol−1. Stirring the solutions at low supersaturation causes a ten‐fold increase in the rate of precipitation and also resulted in a change in the precipitation mechanism from diffusion controlled to a surface reaction controlled mechanism with an activation energy of 37.0 kJ mol−1. Stagnant solutions at high supersaturation followed a second‐order rate law with an activation energy of 27.0 kJ mol−1 for the first 30 % of the precipitation process. The process becomes first order in the last 70 % with an activation energy of 14.3 kJ mol−1, indicating a change in the reaction mechanism to a diffusion‐controlled mechanism. Kinetic studies of the precipitation of vanadium(II) sulfate solutions showed that both stagnant and stirred solutions follow a first‐order rate law with a low activation energy (10.7 and 14.5 kJ mol−1, respectively). This indicates a diffusion‐controlled precipitation mechanism under both conditions.