bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of recyclable polybutadiene rubber based on acid–base complexation
Authors: Cui Kejian , Wang Dong , Zhang Huan , Guo Jing , Cai Chao , Zhu Caizhen , Zhao Ning , Xu Jian 
Published: May 2017

ABSTRACTThermoreversible polybutadiene (PB) rubber is prepared by the self‐assembly of thiol‐ene functionalized PB oligomers containing amine and carboxylic acid groups, respectively, via acid–base reaction. The as‐formed ionic hydrogen bonds between the amine and carboxylic acid groups function as the crosslinking points to construct the polymer network. By controlling the crosslinking density, a series of materials ranging from soft gel to stiff solid with different physical properties can be obtained. The thermal reversibility of the ionic hydrogen bonds is evidenced by rheometry and temperature‐dependent FTIR spectra. In contrast to conventional covalently crosslinked rubbers, the thermoreversible PB rubbers prepared exhibit the capability of thermally reshaping and recycling. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45280.
Palladium Nanoparticles Immobilized on Individual Calcium Carbonate Plates Derived from Mussel Shell Waste: An Ecofriendly Catalyst for the Copper‐Free Sonogashira Coupling Reaction
Authors: Saetan Trin , Lertvachirapaiboon Chutiparn , Ekgasit Sanong , Sukwattanasinitt Mongkol , Wacharasindhu Sumrit 
Published: May 2017

AbstractThe conversion of waste into high‐value materials is considered an important sustainability strategy in modern chemical industries. A large volume of shell waste is generated globally from mussel cultivation. In this work, mussel shell waste (Perna viridis) is transformed into individual calcium carbonate plates (ICCPs) and is applied as a support for a heterogeneous catalyst. Palladium nanoparticles (3–6 nm) are deposited with an even dispersion on the ICCP surface, as demonstrated by X‐ray diffraction and scanning electron microscopy. Using this system, Sonogashira cross‐coupling reactions between aryl iodides and terminal acetylenes were accomplished in high yields with the use of 1 % Pd/ICCP in the presence of potassium carbonate without the use of any copper metal or external ligand. The Pd/ICCP catalyst could also be reused up to three times and activity over 90 % was maintained with negligible Pd‐metal leaching. This work demonstrates that mussel shell waste can be used as an inexpensive and effective support for metal catalysts in coupling reactions, as demonstrated by the successful performance of the Pd‐catalyzed, copper‐free Sonogashira cross‐coupling process.
Activation of CO2 by Vanadium Nitrogenase
Authors: Sickerman Nathaniel S. , Hu Yilin , Ribbe Markus W. 
Published: May 2017

AbstractThe reduction of CO2 into useful products, including hydrocarbon fuels, is an ongoing area of particular interest due to efforts to mitigate buildup of this greenhouse gas. While the industrial Fischer–Tropsch process can facilitate the hydrogenation of CO2 with H2 to form short‐chain hydrocarbon products under high temperatures and pressures, a desire to perform these reactions under ambient conditions has inspired the use of biological approaches. Particularly, enzymes offer insight into how to activate and reduce CO2, but only one enzyme, nitrogenase, can perform the multielectron, multiproton reduction of CO2 into hydrocarbons. The vanadium‐containing variant, V‐nitrogenase, displays especial reactivity towards the hydrogenation of CO and CO2. This Focus Review discusses recent progress towards the activation and reduction of CO2 with three primary V‐nitrogenase systems. These systems span both ATP‐dependent and ATP‐independent processes and utilize approaches with whole cells, isolated proteins, and extracted cofactors.
Aqueous Oxidations Started by TiO2 Photoinduced Holes Can Be a Rate‐Determining Step
Authors: Gong Yuanzheng , Yang Chun , Ji Hongwei , Chen Chuncheng , Ma Wanhong , Zhao Jincai 
Published: May 2017

AbstractIn aqueous TiO2 photocatalytic hydroxylation of weakly polar aromatics, a series of inverse H/D KIEs of 0.7–0.8 were observed, which is different than the normal H/D kinetic isotope effects (KIEs) usually observed for polar aromatics. This result indicated that the oxidation started by photo‐induced hvb+ can be the rate‐determining step.
Exponential Stability and Stabilization for Quadratic Discrete‐Time Systems with Time Delay
Authors: Chen Fu , Kang Shugui , Qiao Shidong , Guo Caixia 
Published: May 2017

AbstractIn this note, we deal with the exponential stability and stabilization problems for quadratic discrete‐time systems with time delay. By using the quadratic Lyapunov function and a so called ‘Finsler's lemma', delay‐independent sufficient conditions for local stability and stabilization for quadratic discrete‐time systems with time delay are derived in terms of linear matrix inequalities (LMIs). Based on these sufficient conditions, iterative linear matrix inequality algorithms are proposed for maximizing the stability regions of the systems. Finally, two examples are given to illustrate the effectiveness of the methods presented in this paper.
A naphthalene derivative as ‘turn‐on’ fluorescent chemosensor for the highly selective and sensitive detection of Al3+
Authors: Zhu Zhong‐Xin , Yu Dong‐Dong , Liu Zhi‐Guo , Huang Ye‐Wei , Zhou A‐Yi , Chen Zhi‐Wei , Sun Jia , Wang Xu , Jin Li‐Tai , Cong Wei‐Tao 
Published: May 2017

AbstractA Schiff base compound derived from naphthalene has been synthesized and characterized as an Al3+‐selective fluorescent probe. The chemosensor (L) exhibits high selectively for Al3+ in aqueous solution, even in the presence of biologically relevant cations such as Na+, K+, Ca2+, Mg2+, Pb2+ and several transition metal ions. There was no observed interference from anions like Br−, Cl−, HSO3−, SO32−, S2O32−, NO2−, CO32− and AC−. The lowest detection limit for the chemosensor L was found to be 1.89 × 10−8 M with a linear response towards Al3+ over a concentration range of 5 × 10−6 to 4 × 10−5 M. Furthermore, the proposed chemosensor has been used for imaging of Al3+ in two different types of cells with satisfying results, which further demonstrates its value for practical application in biological systems.
Manganese‐enhanced magnetic resonance imaging combined with electrophysiology in the evaluation of visual pathway in experimental rat models with monocular blindness
Authors: Tang Zuohua , Wang Jie , Xiao Zebin , Sun Xinghuai , Feng Xiaoyuan , Tang Weijun , Chen Qian , Wu Lingjie , Wang Rong , Zhong Yufeng , Wang Wentao , Luo Jianfeng 
Published: May 2017

AbstractPurposeOur study aimed to explore the feasibility of manganese‐enhanced magnetic resonance imaging (MEMRI) combined with visual evoked potentials (VEP) and auditory evoked visual cortex responses (AVR) in evaluating for the establishment of visual/auditory compensatory pathways after monocular blindness.Materials and MethodsA total of 14 healthy neonatal male Sprague‐Dawley rats were randomly divided into two groups (n = 7 for Groups A and B). Right optic nerve (ON) transection was performed on the 7 rats of Group A to obtain a monocularly blind model, and the 7 rats of Group B were chosen as the control group. Four months later, 400 mmol MnCl2 was injected into the left eye in both groups via intravitreal injection. The changes in the visual pathways projected from the blind eye and the remaining eye in Group A and the normal eyes in Group B were compared to determine if new visual compensatory pathways were established. Additionally, VEP tests were performed to determine complete blindness, and AVR examinations were performed to help identify the generation of auditory compensatory function.ResultsThe VEP test indicated complete visual loss after ON transection. In the monocularly blind rats, the contrast‐to‐noise ratio (CNR) of ON, optic tract (OT), lateral geniculate nucleus (LGN), superior colliculus (SC), optic radiation (OR) and visual cortex (VC) of visual pathway projected from the left eye was significantly higher than that of the right pathway (p < .001). Moreover, the CNR of ON, OT, LGN, SC, OR and VC in the visual pathway projected from the left eye of monocularly blind rats was significantly lower than those of normal rats (p < .05). The AVR results revealed that the corresponding bilateral visual cortex in monocularly blind rats did not respond to the auditory stimulus or showed dissimilation with the low frequency.ConclusionMEMRI combined with electrophysiology, including VEP and AVR, may be potentially helpful in the evaluation of the possible generation of new visual/auditory compensatory pathways after monocular blindness.
High ubiquitin‐specific protease 44 expression induces DNA aneuploidy and provides independent prognostic information in gastric cancer
Authors: Nishimura Sho , Oki Eiji , Ando Koji , Iimori Makoto , Nakaji Yu , Nakashima Yuichiro , Saeki Hiroshi , Oda Yoshinao , Maehara Yoshihiko 
Published: May 2017

AbstractChromosomal instability (CIN), characterized by aneuploidy, is a major molecular subtype of gastric cancer. The deubiquitinase USP44 is an important regulator of APC activation in the spindle checkpoint and leads to proper chromosome separation to prevent aneuploidy. Aberrant expression of USP44 leads CIN in cells; however, the correlation between USP44 and DNA aneuploidy in gastric cancer is largely unknown. We analyzed USP44 expression in 207 patients with gastric cancer by immunohistochemistry and found that the proportion of USP44 expression was higher in gastric cancer tumors (mean, 39.6%) than in gastric normal mucosa (mean, 14.6%) (P < 0.0001). DNA aneuploidy was observed in 124 gastric cancer cases and high USP44 expression in cancer strongly correlated with DNA aneuploidy (P = 0.0005). The overall survival was significantly poorer in the high USP44 expression group compared with the low USP44 group (P = 0.033). Notably, USP44 expression had no prognostic impact in the diploid subgroup; however, high USP44 expression was a strong poor prognostic factor for progression‐free survival (P = 0.018) and overall survival (P = 0.036) in the aneuploid subgroup. We also confirmed that stable overexpression of USP44 induced somatic copy‐number aberrations in hTERT‐RPE‐1 cells (50.6%) in comparison with controls (6.6%) (P < 0.0001). Collectively, our data show USP44 has clinical impact on the induction of DNA aneuploidy and poor prognosis in the CIN gastric cancer subtype.
p62/sequestosome 1 in human colorectal carcinoma as a potent prognostic predictor associated with cell proliferation
Authors: Nakayama Shun , Karasawa Hideaki , Suzuki Takashi , Yabuuchi Shinichi , Takagi Kiyoshi , Aizawa Takashi , Onodera Yoshiaki , Nakamura Yasuhiro , Watanabe Mika , Fujishima Fumiyoshi , Yoshida Hiroshi , Morikawa Takanori , Sase Tomohiko , Naitoh Takeshi , Unno Michiaki , Sasano Hironobu 
Published: May 2017

Abstractp62/sequestosome 1 (p62) is a multi‐domain protein that functions as a receptor for ubiquitinated targets in the selective autophagy and serves as a scaffold in various signaling cascades. p62 have been reported to be up‐regulated in several human malignancies, but the biological roles and significance of p62 are still poorly understood in colorectal carcinoma. We immunohistochemically evaluated p62 in 118 colorectal adenocarcinoma and 28 colorectal adenoma cases. We used four colon carcinoma cells (HCT8, HT29, COLO320, and SW480) in the in vitro studies. p62 immunoreactivity was detected in 11% of colorectal adenoma cases and 31% of adenocarcinoma cases, while it was negligible in the normal epithelium. The immunohistochemical p62 status was significantly associated with synchronous liver metastasis, and it turned out to be an independent adverse prognostic factor in colorectal cancer patients. Following in vitro studies revealed that HCT8 and HT29 cells transfected with p62‐specific siRNA showed significantly decreased cell proliferation activity, whereas COLO320 and SW480 cells transfected with p62 expression plasmid showed significantly increased cell proliferation activity. The p62‐mediated cell proliferation was not associated with the autophagy activity. These findings suggest that p62 promotes the cell proliferation mainly as a scaffold protein, and that the p62 status is a potent prognostic factor in colorectal carcinoma patients.
Fischer–Tropsch Synthesis Bifunctional Catalysts: Cobalt Supported on 3D Mesoporous Cellular Silica Foams Assembled by Using ZSM‐5 Seeds
Authors: Wei Liang , Zhao Yanxi , Zhang Yuhua , Liu Chengchao , Hong Jingping , Xiao Qi , Xiong Haifeng , Li Jinlin 
Published: May 2017

AbstractMesoporous cellular silica foams (MCF) have 3D pore networks in which large spherical cell pores interconnect with small window pores. This novel characteristic provides an open pore structure that favors the accessibility of reactants and mass transfer in reactions. In this work, MCF was functionalized by assembling ZSM‐5 seeds to improve the acidity and the ZSM seed was found to disperse in the MCF structure homogeneously (MCF‐Z). The obtained MCF‐Z materials showed high surface acidity and were then used as supports for cobalt Fischer–Tropsch synthesis (FTS) bifunctional catalysts (20 wt % Co). Compared with Co/MCF catalyst, the Co/MCF‐Z catalysts showed higher CO conversion and improved durability in FTS at 260 °C and 1.0 MPa. Moreover, on increasing the amount of ZSM‐5 seed, the activity of Co/MCF‐Z catalysts gradually increased and then decreased. Co/MCF‐Z catalyst assembled with the highest amount of ZSM‐5 seed (Al/Si=1.5 %, molar ratio) exhibited the lowest deactivation rate, which was owing to the superior stability of the MCF‐Z support and an increased interaction between cobalt and MCF‐Z. The Co/MCF‐Z bifunctional catalyst showed higher iso‐paraffin/n‐paraffin ratios, higher olefin/paraffin ratios as well as lower C2–C4 alcohol selectivity in comparison to Co/MCF catalyst. For the Co/MCF‐Z catalyst, the decrease in space velocity led to hydrocarbon selectivity shifting toward middle distillate products.
Synthesis of Polyoxymethylene Dimethyl Ethers Catalyzed by Pyrrolidinonium‐Based Ionic Liquids
Authors: Yang Zhenyu , Hu Yufeng , Ma Weiting , Qi Jianguang , Zhang Xianming 
Published: May 2017

AbstractPolyoxymethylene dimethyl ethers (PODEn) are widely applied as diesel additives in engines. Ionic liquids (ILs) replace traditional liquid acids as catalysts in chemical processes. A series of pyrrolidinonium‐based Brønsted acidity ILs were synthesized, investigated, and employed as catalysts for the synthesis of PODEn from methylal and trioxane for the first time. The Hammett function values were measured to uncover the connection between catalytic performance and acidity‐activity of the ILs considered. The optimal experimental conditions for the synthesis of PODEn were determined. The maximum values of both the conversion of raw material and the selectivity of PODE3–8 were obtained with 1‐octyl‐2‐pyrrolidinonium trifluoromethanesulfonate ([NOP][TFO]) as the catalyst. [NOP][TFO] provides greater selectivity of PODE3–4 than the traditional catalysts such as H2SO4 and CF3SO3H.
Noninnocent β‐Diiminate Ligands: Redox Activity of a Bis(alkylimidazole)methane Ligand in Cobalt and Zinc Complexes
Authors: Ghosh Pradip , Naastepad Richard , Riemersma Charl F. , Lutz Martin , Moret Marc‐Etienne , Klein Gebbink Robertus J. M. 
Published: May 2017

AbstractA new β‐diiminate ligand (the bis(1‐methyl‐4,5‐diphenyl‐1H‐imidazol‐2‐yl)methane anion, BMIMPh2−) is introduced, in which the ligand framework bears an extended imidazole‐based π‐system in conjugation with a formal β‐diketiminates (NacNac) backbone. Bis‐ligated transition metal complexes (Co, Zn) featuring this anionic ligand undergo a series of four consecutive single‐electron oxidations that are all ligand‐based. The singly and doubly oxidized complexes can be synthesized on a preparative scale and have been fully characterized by various spectroscopic techniques. This is in sharp contrast to the corresponding NacNac‐based complexes in which only singly oxidized complexes were isolated and characterized. Single crystal X‐ray structure determination revealed a correlation between the intra‐ligand metrical parameters and the oxidation state of BMIMPh2−. These structural changes in the ligand framework make BMIMPh2− as a perceptible non‐innocent ligand in contrast to NacNac type ligands.
From Ligand to Phosphor: Rapid, Machine‐Assisted Synthesis of Substituted Iridium(III) Pyrazolate Complexes with Tuneable Luminescence
Authors: Groves Lara M. , Schotten Christiane , Beames Joseph , Platts James A. , Coles Simon J. , Horton Peter N. , Browne Duncan L. , Pope Simon J. A. 
Published: May 2017

AbstractA first‐generation machine‐assisted approach towards the preparation of hybrid ligand/metal materials has been developed. A comparison of synthetic approaches demonstrates that incorporation of both flow chemistry and microwave heating can be successfully applied to the rapid synthesis of a range of new phenyl‐1H‐pyrazoles (ppz) substituted with electron‐withdrawing groups (−F, −CF3, −OCF3, and −SF5). These, in turn, can be translated into heteroleptic complexes, [Ir(ppz)2(bipy)]BF4 (bipy=2,2′‐bipyridine). Microwave‐assisted synthesis for the IrIII complexes allows isolation of spectroscopically pure species in less than 1 h of reaction time starting from IrCl3. All of the new complexes have been characterised photophysically (including nanosecond time‐resolved transient absorption spectroscopy), electrochemically, and by TD‐DFT studies. The complexes exhibit ligand‐dependent, tuneable, green‐yellow luminescence (500–560 nm), with quantum yields in the range 5–15 %.
Dual‐Responsive Molecular Switches Based on Dithienylethene–RuII Organometallics in Self‐Assembled Monolayers Operating at Low Voltage
Authors: Mulas Andrea , He Xiaoyan , Hervault Yves‐Marie , Norel Lucie , Rigaut Stéphane , Lagrost Corinne 
Published: May 2017

AbstractTwo carbon‐rich ruthenium complexes bearing a dithienylethene (DTE) unit and a hexylthiol spacer were designed to be attached on gold surfaces. Both compounds display photochemically driven switching properties, allowing reversible conversion from open to closed forms of the DTE units upon irradiation in solution. In contrast, only the bimetallic complex undergoes an efficient electrochemical ring closure at low potential, (0.5 V vs. SCE), whereas the monometallic complex shows a simple one‐electron reversible redox event. These appealing switching properties could be successfully transferred within diluted self‐assembled monolayers (SAMs). Furthermore, the two immobilized organometallics exhibit fast electron‐transfer kinetics. Therefore, this organometallic strategy allows us to obtain multifunctional surfaces with the possibility of combining switching events triggered by an electrochemical oxidation at low potential and by light at distinct wavelengths for a write‐and‐erase function, along with an access to different oxidation states. Importantly, a non‐destructive electrochemical read‐out is achieved at a sufficiently high scan rate that prevents any electrochemical closing. On the whole, the two surface‐confined organometallic compounds exhibit appealing properties for application in molecular electronics.
Photo‐Responsive Soft Ionic Crystals: Ion‐Pairing Assemblies of Azobenzene Carboxylates
Authors: Yamakado Ryohei , Hara Mitsuo , Nagano Shusaku , Seki Takahiro , Maeda Hiromitsu 
Published: May 2017

AbstractThis report delineates the design and synthesis of negatively charged azobenzene derivatives that form photo‐responsive ion‐pairing assemblies. The azobenzene carboxylates possessing aliphatic chains were prepared as photo‐responsive anions that promote the formation of ion‐pairing dimension‐controlled assemblies, including mesophases, when used in conjunction with a tetrabutylammonium (TBA) cation. The photo‐responsive properties of the ion pairs and the precursory carboxylic acids in the bulk state were examined by polarized optical microscopy (POM) and X‐ray diffraction (XRD), demonstrating that liquid crystal (LC)–liquid and crystal–liquid phase transitions occurred, depending on the number and lengths of the aliphatic chains of each assembly. An ion pair exhibited photo‐induced crystal–crystal phase transitions upon switching between two irradiation wavelengths (365/436 nm).
The Role of Water in the Catalyst‐Free Aldol Reaction of Water‐Insoluble N‐Methyl‐2,4‐thiazolidinedione with N‐Methylisatin from QM/MM Monte Carlo Simulations
Authors: Zhao Jianming , He Fen , Zhang Fan , Yang Xin , Tian Zhiyue , Xue Ying 
Published: May 2017

AbstractThe role of water in the uncatalyzed aldol reaction of N‐methyl‐2,4‐thiazolidinedione with N‐methylisatin is investigated through Monte Carlo statistical mechanics simulations that utilize free energy perturbation theory and the mixed quantum mechanics and molecular mechanics (QM/MM) model with PDDG/PM3 for the QM method in “on‐water” and DMSO environments. There are several conceivable orientations between thiazolidinedione and isatin in the process of C−C bond formation. However, the formation of the C−C bond takes place between the re face of isatin and the si face of (E)‐enol of the thiazolidinedione to form the preferred anti‐type product, which results from enhanced hydrogen‐bonding interactions between water molecules and the oxygen atoms undergoing bond breakage and bond formation during the reaction. Novel insights into the effect of water on the aldol reaction are presented herein.
Activation of Ternary Transition Metal Chalcogenide Basal Planes through Chemical Strain for the Hydrogen Evolution Reaction
Authors: Kim Yongshin , Tiwari Anand P. , Prakash Om , Lee Hyoyoung 
Published: May 2017

AbstractCatalytically inactive basal planes pose challenges for the efficient hydrogen evolution reaction (HER) in two‐dimensional (2 D) transition metal chalcogenide (TMC) nanosheets. Herein, a new hybrid structure is reported in which zero‐dimensional TMC nanodots (NDs) are decorated on the basal planes of 2 D nanosheets of TMCs to enhance their catalytic activity towards the HER process. A novel process is developed to fabricate a hybrid Cu2MoS4 (2 D ternary transition metal chalcogenide Cu2MoS4 nanosheets)/MoSe2 (0 D binary transition metal chalcogenide MoSe2 ND) nanostructure by controlling the size of the MoSe2 NDs to enhance the HER activity. In acidic media, this optimal hybrid Cu2MoS4/MoSe2 nanostructure achieves excellent catalytic activity for HER, which exhibits a low overpotential of 166 mV at a current density of 10 mA cm−2, which corresponds to a Tafel slope of 74.7 mV dec−1. In addition, the synthesized hybrid nanostructure shows excellent stability when under acidic medium for 16 h of continuous electrolysis. Therefore, it is suggested that our strategy may open a new path for the design of hybrid nanostructures by using ternary transition metal chalcogenides (TTMCs) with binary transition metal chalcogenides (BTMCs) for alternative non‐noble metal catalysts towards HER.
Aliphatic‐Alcohol‐Induced Opaque‐to‐Transparent Transformation and Application of Solubility Theory in a Bis‐Dipeptide‐Based Supramolecular Gel
Authors: Xiao Tingting , Zhang Xiaoyang , Wu Jingyu , Yang Jiazhi , Yang Yong 
Published: May 2017

AbstractA bis‐dipeptide supramolecular gelator (DMPV) is prepared, based on l‐valine moieties having a pyridinyl group and a long fatty diamine. It is found that the gelator can immobilize organic/water binary mixed solvents, and gel‐to‐gel transitions with unprecedented opaque‐to‐transparent transformations are observed upon using aliphatic alcohols such as methanol, ethanol, 1‐propyl alcohol, and isopropanol as the organic components. Morphological investigations indicate that a reassembly process occurs, and microstructure evolutions from agglomerates to nanofibers are observed. Opaque and transparent assemblies can interconvert, and respond and restore under mechanical force and pH stimuli. Moreover, Hansen and Flory–Huggins parameters are used to investigate the effect of the solvent on the gelation performance of DMPV. This may facilitate the structure and solvent optimizations and aid the development of advanced gel systems.