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Hujun Xie, Yang Li, Lihong Wang, Jian Kuang, Qunfang Lei, Wenjun Fang
Quantum chemistry calculations have been employed to study the mechanisms of nickel-catalyzed Suzuki-Miyaura cross-coupling reactions of benzylic carbamates with arylboronic esters, and the energy profiles have been computed to evaluate possible origins for the generation of different stereochemistry products. It has been demonstrated that the mechanism can be divided into three steps: oxidative addition, transmetallation and reduction elimination. Transmetallation is the rate-limiting step for the whole reaction cycle, and oxidative addition controls the stereoselectivity of the resulting products...
September 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Rebecca J Schmidt, Vladimir Kogan, Janie F Shelton, Lora Delwiche, Robin L Hansen, Sally Ozonoff, Claudia C Ma, Erin C McCanlies, Deborah H Bennett, Irva Hertz-Picciotto, Daniel J Tancredi, Heather E Volk
BACKGROUND: Maternal folic acid (FA) protects against developmental toxicity from certain environmental chemicals. OBJECTIVE: We examined combined exposures to maternal FA and pesticides in relation to autism spectrum disorder (ASD). METHODS: Participants were California children born from 2000-2007 who were enrolled in the Childhood Autism Risks from Genetics and the Environment (CHARGE) case-control study at age 2-5 y, were clinically confirmed to have ASD (n=296) or typical development (n=220), and had information on maternal supplemental FA and pesticide exposures...
September 8, 2017: Environmental Health Perspectives
Phil Liebing
The mol-ecular and crystal structure of the l-proline-derived di-thio-carbamate-carboxyl-ate compound poly[tri-μ-aqua-(μ-2-carboxyl-atopyrrolidine-1-carbodi-thio-ato)dipotassium], [K2(C6H7NO2S2)(H2O)3] n or K2(SSC-NC4H7-COO)·3H2O, has been determined. The di-thio-carbamate moiety displays a unique coordination mode, comprising a 'side-on' π-coordinated K(+) cation besides a commonly σ-chelated K(+) cation. By bridging coordination of the CSS group, COO group and water mol-ecules, the K(+) cations are linked into a two-dimensional coordination polymer extending parallel to the ab plane...
September 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
Damian C Onwudiwe, Madalina Hrubaru, Eric C Hosten, Charmaine Arderne
The title compound, [Cd2(C7H10NS2)4], is a neutral dinuclear cadmium(II) complex bearing four bis N,N-di-allyl-di-thio-carbamate ligands coordinating to two Cd(II) cations. In each of the monomeric subunits, there are four S atoms of two di-thio-carbamate ligands [Cd-S = 2.5558 (3), 2.8016 (3), 2.6050 (3) and 2.5709 (3) Å] that coordinate to one Cd(II) atom in a bidentate mode. The dimers are located over an inversion centre bridged by two additional bridging Cd-S bonds [2.6021 (3) Å], leading to a substantial distortion of the geometry of the monomeric subunit from the expected square-planar geometry...
September 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
Pavel Poplaukhin, Edward R T Tiekink
The common structural feature of the title compounds, [Zn(C4H8NOS2)2(C5H5N)]·C5H5N (I) and [Zn(C5H10NOS2)2(C5H5N)]·C5H5N (II), which differ by having di-thio-carbamate N-bound methyl (I) and ethyl (II) groups, is the coordination of each Zn(II) atom by two non-symmetrically chelating di-thio-carbamate ligands and by a pyridine ligand; in each case, the non-coordinating pyridine mol-ecule is connected to the Zn-containing mol-ecule via a (hy-droxy)O-H⋯N(pyridine) hydrogen bond. The resulting NS4 coordination geometry is closer to a square-pyramid than a trigonal bipyramid in the case of (I), but almost inter-mediate between the two extremes in (II)...
July 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
Pierre Baillargeon, Tarik Rahem, Édouard Caron-Duval, Jacob Tremblay, Cloé Fortin, Étienne Blais, Victor Fan, Daniel Fortin, Yves L Dory
The crystal structures of tert-butyl (5-chloro-penta-2,4-diyn-1-yl)carbamate, C10H12ClNO2 (II), and tert-butyl (5-iodo-penta-2,4-diyn-1-yl)carbamate, C10H12INO2 (IV), are isomorphous to previously reported structures and accordingly their mol-ecular and supra-molecular structures are similar. In the crystals of (II) and (IV), mol-ecules are linked into very similar two-dimensional wall organizations with anti-parallel carbamate groups involved in a combination of hydrogen and halogen bonds (bifurcated N-H⋯O=C and C≡C-X⋯O=C inter-actions on the same carbonyl group)...
July 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
Pavel Poplaukhin, Hadi D Arman, Edward R T Tiekink
The title compound, {[Zn(C9H11N2S2)2]·0.5C6H7N} n , comprises two independent, but chemically similar, Zn[S2CN(Et)CH2py]2 residues and a 4-methyl-pyridine solvent mol-ecule in the asymmetric unit. The Zn-containing units are connected into a one-dimensional coordination polymer (zigzag topology) propagating in the [010] direction, with one di-thio-carbamate ligand bridging in a μ2-κ(3) mode, employing one pyridyl N and both di-thio-carbamate S atoms, while the other is κ(2)-chelating. In each case, the resultant ZnNS4 coordination geometry approximates a square pyramid, with the pyridyl N atom in the apical position...
July 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
Janice P Van Zee, Catherine A Hill
The availability of genome assemblies and other genomic resources is facilitating investigations of complex genetic traits for several species of ticks. Understanding the genetics of acaricide resistance is a priority for tick and tick-borne disease control. The synaptic enzyme acetylcholinesterase (ACE) is recognized as the target of organophosphates (OPs) and carbamates, and mutations in ACE have been tied to resistance. Multiple studies support three ACE (ace) loci in R. microplus but the molecular basis of OP-resistance in this tick remains elusive...
January 1, 2018: Frontiers in Bioscience (Landmark Edition)
Laura E McWilliams, Nicholas Valley, Nina Vincent, Geraldine L Richmond
Monoethanolamine (MEA) is a benchmark scrubber for CO2 gas emissions reductions. Preliminary studies have indicated surface monoethanolamine could influence the greater chemistry of CO2 uptake. MEA is known to be surface active and orients at aqueous surfaces such that its nitrogen lone pair electrons are pointing toward the gas phase. This MEA orientation has the potential to facilitate CO2 surface chemistry, however a thorough description of the chemistry at play during this important carbon capture reaction is lacking...
September 20, 2017: Journal of Physical Chemistry. A
Mustafa Şengül, Nida Kaçar, Mehmet Karaca, Sedef Zeliha Öner, Çağrı Ergin
Dermanyssus gallinae is one of the important hematophagous ectoparasite species of poultry like chicken, pigeon and wild bird species. These ectoparasites in the form of nymphs or adults who can not find their hosts are also seen in mammals and even in humans. For this reason, they are considered as important for public health. The ectoparasite causes a clinical condition named gamasoidosis among pet owners and people who live or work close to animal shelters, barns and chicken farms. Pruritus dermatitis is also caused by D...
July 2017: Mikrobiyoloji Bülteni
Davis Henry Hopkins, Nicholas J Fraser, Peter D Mabbitt, Paul D Carr, John G Oakeshott, Colin J Jackson
Carboxylesterase (CBE)-mediated metabolic resistance to organophosphate and carbamate insecticides is a major problem for the control of insect disease vectors, such as the mosquito. The most common mechanism involves overexpression of CBEs that bind to the insecticide with high affinity, thereby sequestering them before they can interact with their target. However, the absence of any structure for an insecticide-sequestering CBE limits our understanding of the molecular basis for this process. We present the first structure of a CBE involved in sequestration, Cqestβ21, from the mosquito disease vector, Culex quinquefasciatus...
September 20, 2017: Biochemistry
Benyl M Ondeto, Christopher Nyundo, Luna Kamau, Simon M Muriu, Joseph M Mwangangi, Kiambo Njagi, Evan M Mathenge, Horace Ochanda, Charles M Mbogo
BACKGROUND: Insecticide resistance has emerged as one of the major challenges facing National Malaria Control Programmes in Africa. A well-coordinated national database on insecticide resistance (IRBase) can facilitate the development of effective strategies for managing insecticide resistance and sustaining the effectiveness of chemical-based vector control measures. The aim of this study was to assemble a database on the current status of insecticide resistance among malaria vectors in Kenya...
September 19, 2017: Parasites & Vectors
Chaitali P Labade, Abhilash R Jadhav, Mehul Ahire, Smita S Zinjarde, Vaijayanti A Tamhane
The present study deals with glutathione-S-transferase (GST) based detoxification of pesticides in Helicoverpa armigera and its potential application in eliminating pesticides from the environment. Dietary exposure of a pesticide mixture (organophosphates - chlorpyrifos and dichlorvos, pyrethroid - cypermethrin; 2-15ppm each) to H. armigera larvae resulted in a dose dependant up-regulation of GST activity and gene expression. A variant GST from H. armigera (HaGST-8) was isolated from larvae fed with 10ppm pesticide mixture and it was recombinantly expressed in yeast (Pichia pastoris HaGST-8)...
September 15, 2017: Ecotoxicology and Environmental Safety
Takeshi Nanjo, Emilio Carlos de Lucca, M Christina White
Amide-containing molecules are ubiquitous in natural products, pharmaceuticals, and materials science. Due to their intermediate electron-richness, they are not amenable to any of the previously developed N-protection strategies known to enable remote aliphatic C-H oxidations. Using information gleaned from a systematic study of the main features that makes remote oxidations of amides in peptide settings possible, we developed an imidate salt protecting strategy that employs methyl trifluoromethanesulfonate (MeOTf) as a reversible alkylating agent...
September 18, 2017: Journal of the American Chemical Society
Pedro Diaz-Parga, Joy J Goto, V V Krishnan
Beta-N-methylamino-L-alanine (BMAA) has been demonstrated to contribute to the onset of the ALS/Parkinsonism-dementia complex (ALS/PDC) and is implicated in the progression of other neurodegenerative diseases. While the role of BMAA in these diseases is still debated, one of the suggested mechanisms involves the activation of excitatory glutamate receptors. In particular, the excitatory effects of BMAA are shown to be dependent on the presence of bicarbonate ions, which in turn forms carbamate adducts in physiological conditions...
September 18, 2017: Neurotoxicity Research
Siyao Liu, Jeannie Horak, Markus Höldrich, Michael Lämmerhofer
The ability to accurately quantify the protein coverage on nanoparticles is critical for assessing the quality of the surface chemistry and the success of the functionalization process of protein-nanoparticle conjugates. Surface coverage determination is therefore an integral part in the quality control of protein-modified nanoparticles in industrial nanotechnology. In this work, a novel and conventional method was established for direct quantification of the protein surface coverage on metallic nanoparticles...
October 9, 2017: Analytica Chimica Acta
Katarína Hroboňová, Anna Lomenova, Jozef Čižmárik, Jozef Lehotay
The paper deals with enantioselective separation of amino acids by the high performance liquid chromatography method. Separations of enantiomeric forms were tested on the chiral stationary phases based on β-cyclodextrine, isopropyl carbamate cyclofructan 6, and the macrocyclic antibiotic teicoplanin. The best enantioseparation was obtained on the teicoplanin-based chiral stationary phase in the reversed-phase mode. UV spectrophotometric detection at 210 nm was used for detection of amino acids. The method was validated with respect to linearity, precision, limit of detection, limit of quantitation, and recovery...
2017: Ceská a Slovenská Farmacie
A Sevastos, N E Labrou, F Flouri, A Malandrakis
Fusarium graminearum laboratory mutants moderately (MR) and highly (HR) benzimidazole-resistant, carrying or not target-site mutations at the β2-tubulin gene were utilized in an attempt to elucidate the biochemical mechanism(s) underlying the unique BZM-resistance paradigm of this fungal plant pathogen. Relative expression analysis in the presence or absence of carbendazim (methyl-2-benzimidazole carbamate) using a quantitative Real Time qPCR (RT-qPCR) revealed differences between resistant and the wild-type parental strain although no differences in expression levels of either β1- or β2-tubulin homologue genes were able to fully account for two of the highly resistant phenotypes...
September 2017: Pesticide Biochemistry and Physiology
Norma Susana Pano-Farias, Silvia Guillermina Ceballos-Magaña, Roberto Muñiz-Valencia, Jorge Gonzalez
In this paper a method of using the "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) extraction and gas chromatography coupled to mass spectrometry detection (GC-MS) was developed for the analysis of five frequently applied pesticides in papaya and avocado. The selected pesticides, ametryn, atrazine, carbaryl, carbofuran, and methyl parathion, represent the most commonly used classes (carbamates, organophosphorous, and triazines). Optimum separation achieved the analysis of all pesticides in < 6...
July 2017: Journal of Food and Drug Analysis
Phillip J Milner, Rebecca L Siegelman, Alexander C Forse, Miguel I Gonzalez, Tomče Runčevski, Jeffrey D Martell, Jeffrey A Reimer, Jeffrey R Long
A new diamine-functionalized metal-organic framework comprised of 2,2-dimethyl-1,3-diaminopropane (dmpn) appended to the Mg(2+) sites lining the channels of Mg2(dobpdc) (dobpdc(4-) = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) is characterized for the removal of CO2 from the flue gas emissions of coal-fired power plants. Unique to members of this promising class of adsorbents, dmpn-Mg2(dobpdc) displays facile step-shaped adsorption of CO2 from coal flue gas at 40 °C and near complete CO2 desorption upon heating to 100 °C, enabling a high CO2 working capacity (2...
September 14, 2017: Journal of the American Chemical Society
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