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Jing Guo, Lili Lin, Yangbin Liu, Xiangqiang Li, Xiaohua Liu, Xiaoming Feng
The enantioselective α-vinylation of β-keto amides/esters using hypervalent iodine salts has been accomplished via a chiral N,N'-dioxide-nickel(II) complex promoted electrophilic addition and reductive elimination process. A wide range of vinyl-substituted all-carbon quaternary β-keto amides/esters were obtained in high yields and ee values (up to 99% yield and 99% ee). Moreover, the catalytic system has been applied to the enantioselective alkynylation/arylation of β-ketoamides with good results.
October 25, 2016: Organic Letters
Aleksandar Ž Kostić, Lazar M Kaluđerović, Biljana P Dojčinović, Miroljub B Barać, Vojka B Babić, Marina P Mačukanović-Jocić
BACKGROUND: Bee pollen has already proved to be a good supplement rich in content of iron and zinc. Studies about application of flower pollen in food industry and medicine have been started. Bearing in mind prevalence of maize as crop culture its pollen will be easily available. The mineral composition of pollen of seven Serbian maize hybrids was analyzed in order to establish its nutritional value and benefits of its implementation in the human diet using ICP method. RESULTS: Presence of twenty four different macro- (nine) and micronutrients (fifteen) was detected...
October 24, 2016: Journal of the Science of Food and Agriculture
Ali A Alshatwi, Jegan Athinarayanan, Vaiyapuri Subbarayan Periasamy, Khalid A Alatiah
Nanographene- and graphene-based nanohybrids have garnered attention in the biomedical community owing to their biocompatibility, excellent aqueous processability, ease of cellular uptake, facile surface functionalization, and thermal and electrical conductivities. NiO nanoparticle-graphene nanohybrid (G-NiO) was synthesized by first depositing Ni(OH)2 onto the surface of graphene oxide (GO) sheets. The Ni(OH)2-GO hybrids were then reduced to G-NiO using date palm syrup at 85 °C. The prepared G-NiO nanohybrids were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy (EDX)...
October 24, 2016: Applied Biochemistry and Biotechnology
Mehmet Emin Kaval, Ismail Davut Capar, Hüseyin Ertas
INTRODUCTION: The purpose of this study was to evaluate the cyclic fatigue and torsional resistance of Hyflex EDM, ProTaper Gold (PTG), and ProTaper Universal (PTU) instruments. METHODS: For the cyclic fatigue test, 10 instruments from each group were tested by using a stainless steel block with 1.5-mm diameter and 3-mm radius of 60° angle of curvature. The instruments were allowed to rotate by using a low-torque motor, and number of cycles from the beginning to the fracture was recorded...
October 21, 2016: Journal of Endodontics
Kamlesh Shrivas, Pathik Maji, Khemchand Dewangan
We report a simple, selective and sensitive colorimetric assay for onsite determination of Ni(II) and Ba(II) from river, pond and tap water samples using the localized surface plasmon resonance (LSPR) of malonate capped gold nanoparticles (AuNPs) as a chemical sensor. The method is based on the color change and red shift of LSPR absorption band in visible region that caused by the aggregation of NPs because of the coordination complex between Ba(II) and Ni(II) with carboxylate ions of malonate capped AuNPs...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Thi Xuan Trang Nguyen, Marc Amyot, Michel Labrecque
A pot experiment was conducted to investigate the effect of diverse plant species (four herbaceous and four woody species) on the labile pool of six metals (Ag, Cu, Pb, Zn, Ni and Se) present in their rhizosphere. After three months of cultivation, concentrations of trace elements (TE) in above and below-ground biomass of each species were determined. The labile and presumably bioavailable fraction of these TE in the rhizosphere as well as key soil parameters (e.g. pH, electrical conductivity (EC), percent of organic matter and dissolved organic carbon (DOC)) were also measured and compared as a function of plant species...
October 21, 2016: Chemosphere
Yu-Chung Tsao, Po-Wen Gu, Su-Hsun Liu, Yi-Shiang Tzeng, Jau-Yuan Chen, Jiin-Chyuan John Luo
CONTEXT: The mechanism of nickel-induced pathogenesis remains elusive. OBJECTIVE: To examine effects of nickel exposure on plasma oxidative and anti-oxidative biomarkers. MATERIALS AND METHODS: Biomarker data were collected from 154 workers with various levels of nickel exposure and from 73 controls. Correlations between nickel exposure and oxidative and anti-oxidative biomarkers were determined using linear regression models. RESULTS: Workers with a exposure to high nickel levels had significantly lower levels of anti-oxidants (glutathione and catalase) than those with a lower exposure to nickel; however, only glutathione showed an independent association after multivariable adjustment...
October 24, 2016: Biomarkers: Biochemical Indicators of Exposure, Response, and Susceptibility to Chemicals
Yan Qu, Qiu Gen Zhang, Faizal Soyekwo, Run Sheng Gao, Rui Xue Lv, Chen Xiao Lin, Meng Meng Chen, Ai Mei Zhu, Qing Lin Liu
Two-dimensional nanosheets of late show great promise as novel materials for size-selective separation membranes of high efficiency. Herein, we demonstrate a novel laminated nanofiltration membrane for fast water purification and organic solvent nanofiltration using the 1 nm-thick and 50 nm-wide nickel hydroxide nanosheets that are facilely prepared by a green chemistry method. The resulting membranes exhibit uniform and flectional two-dimensional laminated structure. With about 1 nm high laminated channels, they allow super-fast transport of water and organic solvents...
October 24, 2016: Nanoscale
Venkata A K Adiraju, Gregory M Ferrence, Timothy D Lash
Azuliporphyrins are intriguing porphyrin analogues that incorporate an azulene ring in place of a pyrrolic unit. This system undergoes regioselective oxidation reactions and favors the formation of stable organometallic derivatives. Reaction of meso-unsubstituted azuliporphyrins with Co2(CO)8 or CoCl2·6H2O gave 21-oxyazuliporphyrins, while Cu(OAc)2 produced the corresponding copper(ii) complexes. Treatment of an oxyazuliporphyrin with Ni(OAc)2 or Pd(OAc)2 afforded analogous nickel(ii) and palladium(ii) derivatives...
October 24, 2016: Organic & Biomolecular Chemistry
Norihiko L Okamoto, Shu Fujimoto, Yuki Kambara, Marino Kawamura, Zhenghao M T Chen, Hirotaka Matsunoshita, Katsushi Tanaka, Haruyuki Inui, Easo P George
High-entropy alloys (HEAs) comprise a novel class of scientifically and technologically interesting materials. Among these, equatomic CrMnFeCoNi with the face-centered cubic (FCC) structure is noteworthy because its ductility and strength increase with decreasing temperature while maintaining outstanding fracture toughness at cryogenic temperatures. Here we report for the first time by single-crystal micropillar compression that its bulk room temperature critical resolved shear stress (CRSS) is ~33-43 MPa, ~10 times higher than that of pure nickel...
October 24, 2016: Scientific Reports
Younes Hanifehpour, Ali Morsali, Behzad Soltani, Babak Mirtamizdoust, Sang Woo Joo
Ultrasound was used to synthesize nano-structures of [Ni(bpzB)2]2(1), a new two-nuclear discrete-coordination compound of divalent nickel with bis-pyrazolyl borate(bpzB). The nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction, infrared, and elemental analysis. The single-crystal X-ray data show that the coordination number of Ni(II) ions is four (Ni1N4 and Ni2N4) with square planar geometry. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions...
January 2017: Ultrasonics Sonochemistry
S D Heintze, A Eser, D Monreal, V Rousson
OBJECTIVE: Dynamic loading is a more important predictor for the clinical longevity of ceramic crowns than static loading. However, dynamic loading machines are costly and mostly have only one test station. The SD Mechatronik Chewing Simulator (formerly Willytec) may be a cost-effective alternative to evaluate the fatigue resistance of metal ceramic crowns. METHOD: Four metal ceramic materials were tested on lower first molar crowns: GC InitiaI, Creation (Willy Geller), IPS InLine (Ivoclar Vivadent) and the new low-fusion IPS Style Ceram (Ivoclar Vivadent)...
September 14, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Carmen Franken, Gudrun Koppen, Nathalie Lambrechts, Eva Govarts, Liesbeth Bruckers, Elly Den Hond, Ilse Loots, Vera Nelen, Isabelle Sioen, Tim S Nawrot, Willy Baeyens, Nicolas Van Larebeke, Francis Boonen, Daniëlla Ooms, Mai Wevers, Griet Jacobs, Adrian Covaci, Thomas Schettgen, Greet Schoeters
BACKGROUND: We investigated whether human environmental exposure to chemicals that are labeled as (potential) carcinogens leads to increased (oxidative) damage to DNA in adolescents. MATERIAL AND METHODS: Six hundred 14-15-year-old youngsters were recruited all over Flanders (Belgium) and in two areas with important industrial activities. DNA damage was assessed by alkaline and formamidopyrimidine DNA glycosylase (Fpg) modified comet assays in peripheral blood cells and analysis of urinary 8-hydroxydeoxyguanosine (8-OHdG) levels...
October 20, 2016: Environmental Research
Sanjib K Shrestha, Liliia M Kril, Keith D Green, Stefan Kwiatkowski, Vitaliy M Sviripa, Justin R Nickell, Linda P Dwoskin, David S Watt, Sylvie Garneau-Tsodikova
The emergence of multidrug-resistant bacterial and fungal strains poses a threat to human health that requires the design and synthesis of new classes of antimicrobial agents. We evaluated bis(N-amidinohydrazones) and N-(amidino)-N'-aryl-bishydrazones for their antibacterial and antifungal activities against panels of Gram-positive/Gram-negative bacteria as well as fungi. We investigated their potential to develop resistance against both bacteria and fungi by a multi-step resistance-selection method, explored their potential to induce the production of reactive oxygen species, and assessed their toxicity...
October 10, 2016: Bioorganic & Medicinal Chemistry
Damoon Sohrabi Baba Heidary, Clive A Randall
Both Li2CO3-coated nickel particles and fast firing technique were utilized in the manufacturing of MLCCs. They preserved the conductivity of Ni electrodes and provided the possibility of sintering the devices in oxidizing atmospheres. By using our method, the partial pressure of oxygen increase from 10-10 atm in conventional methods to 10-4 atm. The oxidizing atmosphere reduced the oxygen vacancy concentration as illustrated by the color change of the samples, and the results of EELS (electron energy loss spectroscopy)...
October 21, 2016: ACS Applied Materials & Interfaces
Fengjiao Chen, Qishan Zhu, Yeyun Wang, Wei Cui, Xiaodong Su, Yanguang Li
Increasing attention has now been focused on the photoelectrochemical (PEC) hydrogen evolution as a promising route to transform solar energy into chemical fuels. Silicon is one of the most studied PEC electrode materials, but its performance is still limited by its inherent PEC instability and electrochemical inertness toward water splitting. To achieve significant PEC activities, silicon-based photoelectrodes usually have to be coupled with proper cocatalysts, and thus formed semiconductor/cocatalyst interface represents a critical structural parameter in the rational design of efficient PEC devices...
October 21, 2016: ACS Applied Materials & Interfaces
Deborah Brazzolotto, Marcello Gennari, Nicolas Queyriaux, Trevor R Simmons, Jacques Pécaut, Serhiy Demeshko, Franc Meyer, Maylis Orio, Vincent Artero, Carole Duboc
Hydrogen production through water splitting is one of the most promising solutions for the storage of renewable energy. [NiFe] hydrogenases are organometallic enzymes containing nickel and iron centres that catalyse hydrogen evolution with performances that rival those of platinum. These enzymes provide inspiration for the design of new molecular catalysts that do not require precious metals. However, all heterodinuclear NiFe models reported so far do not reproduce the Ni-centred reactivity found at the active site of [NiFe] hydrogenases...
November 2016: Nature Chemistry
Blake T Riley, Olga Ilyichova, Mauricio G S Costa, Benjamin T Porebski, Simon J de Veer, Joakim E Swedberg, Itamar Kass, Jonathan M Harris, David E Hoke, Ashley M Buckle
The kallikrein-related peptidase (KLK) family of proteases is involved in many aspects of human health and disease. One member of this family, KLK4, has been implicated in cancer development and metastasis. Understanding mechanisms of inactivation are critical to developing selective KLK4 inhibitors. We have determined the X-ray crystal structures of KLK4 in complex with both sunflower trypsin inhibitor-1 (SFTI-1) and a rationally designed SFTI-1 derivative to atomic (~1 Å) resolution, as well as with bound nickel...
October 21, 2016: Scientific Reports
Sinziana Mirela Popescu, Anders J Barlow, Sami Ramadan, Srinivas Ganti, Biswajit Ghosh, John Hedley
We report the first investigation into the potential of electroless nickel deposition to form ohmic contacts on single layer graphene. Aiming to minimize the contact resistance on graphene, a statistical model was used to optimize metal purity, surface roughness and coverage of the deposited film by controlling the nickel bath parameters (pH and temperature). The metalized graphene layers were patterned using photolithography and contacts deposited at temperatures as low as 60°C. The contact resistance was 215 ± 23 Ω over a contact area of 200 μm x 200 μm, which improved upon rapid annealing to 107 ± 9 Ω...
October 21, 2016: ACS Applied Materials & Interfaces
Rosamaria Lappano, Roberta Malaguarnera, Antonino Belfiore, Marcello Maggiolini
Certain environmental chemicals may accumulate in human serum and tissues eliciting estrogenic and/or carcinogenic effects. Therefore, there is heightened interest in determining whether environmental chemicals may increase the risk for endocrine-related tumors like breast cancer. For instance, metals as cadmium, zinc, copper, iron, nickel and aluminum have been shown to mimic estrogen action. Moreover, the exposure to these chemicals has been reported to stimulate diverse malignancies including breast cancer, which is the most common tumor in women worldwide...
October 17, 2016: Molecular and Cellular Endocrinology
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