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Karen Bush
Recent regulatory approvals for the β-lactam inhibitor combinations of ceftazidime-avibactam and meropenem-vaborbactam have provided two novel therapeutic options for the treatment of multidrug-resistant infections caused by Gram-negative bacteria. Most importantly, these combination agents have satisfied an important medical need related to antibiotic-resistant Klebsiella pneumoniae that produce serine carbapenemases, especially the Klebsiella pneumoniae carbapenemase (KPC) enzymes. Both combinations contain non-β-lactam β-lactamase inhibitors of novel chemical classes not previously developed as antibacterial agents, the diazabicyclooctanes and cyclic boronic acid derivatives...
December 12, 2017: ACS Infectious Diseases
George G Zhanel, Courtney K Lawrence, Heather Adam, Frank Schweizer, Sheryl Zelenitsky, Michael Zhanel, Philippe R S Lagacé-Wiens, Andrew Walkty, Andrew Denisuik, Alyssa Golden, Alfred S Gin, Daryl J Hoban, Joseph P Lynch, James A Karlowsky
Relebactam (formerly known as MK-7655) is a non-β-lactam, bicyclic diazabicyclooctane, β-lactamase inhibitor that is structurally related to avibactam, differing by the addition of a piperidine ring to the 2-position carbonyl group. Vaborbactam (formerly known as RPX7009) is a non-β-lactam, cyclic, boronic acid-based, β-lactamase inhibitor. The structure of vaborbactam is unlike any other currently marketed β-lactamase inhibitor. Both inhibitors display activity against Ambler class A [including extended-spectrum β-lactamases (ESBLs), Klebsiella pneumoniae carbapenemases (KPCs)] and class C β-lactamases (AmpC)...
December 12, 2017: Drugs
Sung Jin Pai, Sang Soo Han
An electrophilic substitution (SE) reaction of BN isosteres has been investigated for the dehydrogenation of ammonia borane (AB) by metal chlorides (MCl2) using various ab initio calculations. In contrast to the typical SE reaction occurring at the carbon atom, the nitrogen atom in AB serves as the reaction center for the SE reaction with the boron moiety as the leaving group when the MCl2 approaches the AB. The SE2 backside reaction is favored as a trigger step for the dehydrogenation of AB by the MCl2 The SE2 reaction is found for 3d-transition-metal chlorides (e...
December 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
Koushik Sarkar, Parthasarathi Dastidar
A C3-symmetric triazine based triboronic acid (HG1) was designed and synthesized. HG1 was found to give hydrogel in DMSO-water (1:9). The hydrogel was rheo-reversible and thermoreversible over a few cycles. Single crystal X-ray diffraction (SXRD) studies on the crystals of HG1 established the presence of honeycomb network in which solvent molecules (DMSO and water) were occluded. SXRD data corroborated well with the hypothesis based on which HG1 was designed. Stimuli responsive release (in vitro) of insulin and doxorubicin from the hydrogel was also achieved...
December 11, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Bo Le Chen, Wei Guo Sun, Xiao Yu Kuang, Cheng Lu, Xin Xin Xia, Hong Xiao Shi, George Maroulis
Transition-metal (TM)-doped boron clusters have received considerable attention in recent years, in part, because of their remarkable size-dependent structural and electronic properties. However, the structures of medium-sized boron clusters doped with TM atoms are still not well-known because of the much increased complexity of the potential surface as well as the rapid increase in the number of low-energy isomers, which are the challenges in cluster structural searches. Here, by means of an unbiased structure search, we systematically investigated the structural evolution of medium-sized tantalum-doped boron clusters, TaBn0/- (n = 10-20)...
December 11, 2017: Inorganic Chemistry
Raphael Bigler, Varinder Kumar Aggarwal
A new strategy for the coupling of a broad scope of electronically diverse aromatics to boronic esters is reported. The coupling sequence, which relies on the directed ortho-lithiation of chromium arene complexes followed by boronate formation and oxidation, occurs with complete ortho-selectivity and enantiospecificity to give the coupling products in excellent yields and with high functional group tolerance. An intermediate chromium arene boronate complex was characterized by X-ray, NMR and IR to elucidate the reaction mechanism...
December 11, 2017: Angewandte Chemie
Giovanni Antonio Lutzu, Nurhan Turgut Dunford
Hydraulic fracturing technology is widely used for recovering natural gas and oil from tight oil and gas reserves. Large volumes of wastewater, flowback water, are produced during the fracturing process. This study examines algal treatment of flowback water. Thirteen microalgae strains consisting of cyanobacteria and green algae were examined. Wastewater quality before and after algae treatment and volatile matter, fixed carbon and ash contents of the biomass grown in flowback water were examined. The experimental results demonstrated that microalgae can grow in flowback water...
December 11, 2017: Environmental Technology
Pedro J Pérez, Javier Carreras, Ana Caballero
A novel, highly enantio- and diastereoselective synthesis of 1-boryl-2,3-disubstituted cyclopropanes has been developed by means of the cyclopropanation of alkenylboronates with ethyl diazoacetate in the presence of catalytic amounts of a chiral copper-(I) complex. The products can also be directly accessed from alkynes through an operationally simple sequential hydroboration-cyclopropanation protocol. The resulting enantioenriched 1-boryl-2,3-disubstituted-cyclopropanes are versatile synthetic intermediates through further transformations at the carbon-boron bonds...
December 11, 2017: Angewandte Chemie
Shuli You, Zhong-Jian Cai, Chen-Xu Liu, Qing Gu
A palladium(II)-catalyzed thioketone-chelation-assisted C-H direct arylation of ferrocenes is described. With thioketone as an efficient directing group, various mono- and di-aryl-substituted thiocarbonylferrocenes were obtained via Pd-catalyzed C-H direct functionalization reaction in high yields under mild and base-free conditions. Furthermore, the arylated thiocarbonylferrocene could undergo diverse transformations.
December 11, 2017: Angewandte Chemie
Sudip Pan, Susmita Kar, Ranajit Saha, Edison Osorio, Ximena Zarate, Lili Zhao, Gabriel Merino, Pratim K Chattaraj
The viability of noble gas axled boron nanowheel, NgnMB10- (Ng = Ar-Rn, M = Nb, Ta; n = 1, 2), is explored via ab initio computations. In the resulting Ng2-M complexes, the Ng-M-Ng nanorod passes through the center of B10- ring, providing them with an inverse sandwich like structure. While in single Ng bound analogue, the Ng binding enthalpy (Hb) at 298 K ranges from 2.5 to 10.6 kcal/mol, in two Ng bound cases it becomes very low for Ng2MB10- -> Ng + NgMB10- dissociation channel, except for Rn case. For a given Ng, Ta has slightly higher Ng binding ability than Nb...
December 11, 2017: Chemistry: a European Journal
Satoshi Nakamura, Shoji Imamichi, Kazuyoshi Masumoto, Masashi Ito, Akihisa Wakita, Hiroyuki Okamoto, Shie Nishioka, Kotaro Iijima, Kazuma Kobayashi, Yoshihisa Abe, Hiroshi Igaki, Kazuyoshi Kurita, Teiji Nishio, Mitsuko Masutani, Jun Itami
This study aimed to evaluate the residual radioactivity in mice induced by neutron irradiation with an accelerator-based boron neutron capture therapy (BNCT) system using a solid Li target. The radionuclides and their activities were evaluated using a high-purity germanium (HP-Ge) detector. The saturated radioactivity of the irradiated mouse was estimated to assess the radiation protection needs for using the accelerator-based BNCT system. 24Na, 38Cl, 80mBr, 82Br, 56Mn, and 42K were identified, and their saturated radioactivities were (1...
2017: Proceedings of the Japan Academy. Series B, Physical and Biological Sciences
Nora Hellou, Aurélie Macé, Clothilde Martin, Vincent Dorcet, Thierry Roisnel, Marion Jean, Nicolas Vanthuyne, Fabienne Berrée, Bertrand Carboni, Jeanne Crassous
Enantiopure carbo[6]helicenyl boronates were synthesized using a photocyclisation reaction as the key step. These compounds were further converted to various amino derivatives using copper-catalyzed azidation or amination and reductive alkylation of benzylazide by a helicenyl dichloroborane. Asymmetric Petasis condensation with glyoxylic acid and morpholine controlled by the helical chirality afforded the corresponding amino esters.
December 11, 2017: Journal of Organic Chemistry
Dongye Xing, Yanjun Hou, Haijun Niu
A series of difluoroboron β-diketonate complexes, containing the indon-β-diketonate ligand carrying methyl or methoxyl substituents was synthesized. The crystal structures of the complexes were confirmed by single crystal X-ray diffraction studies. The fluorescence properties of compounds were studied in solution state, solid state and on PMMA polymer matrix. The photophysical data of compounds 2a-2d exhibited strong fluorescence and photostability under the ultraviolet light (Hg lamp). The complex 2b showed higher fluorescence intensity in solution state as compared to other complexes of the series...
December 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Angelo Iannetelli, Graham Tizzard, Simon J Coles, Gareth R Owen
The sodium salt of a monosubstituted borohydride anion containing a 2-mercaptopyridyl unit (mp) is reported herein. This compound was coordinated to a rhodium(I) center providing the complex [Rh{κ3-H,H,S-H3B(mp)}(NBD)] (1) (where NBD = 2,5-norbornadiene) in which the boron-based ligand is coordinated to the rhodium center via the thione donor and two of the B-H bonds of the BH3 unit. Reaction of complex 1 with carbon monoxide results in the activation of the complex leading to the product of a formal intramolecular hydroboration reaction, where the NBD unit has, in effect, inserted into one of the B-H bonds...
December 8, 2017: Inorganic Chemistry
Jiheng Ding, Hongran Zhao, Yan Zheng, Qiaolei Wang, Hao Chen, Huimin Dou, Haibin Yu
Based on the unique material properties, two-dimensional (2D) nanomaterials such as graphene, molybdenum disulfide (MoS2), and boron nitride (BN) have been attracting increasing research interest. The potential of 2D materials in the form of nanoplatelets used as new materials will be important to both nanomaterials and advanced materials. Usually water is considered as the ideal dispersed medium, while the essential hydrophobicity of 2D nanoplatelets and limitation of mass production became the quite serious obstacles for the usage in various fields...
December 8, 2017: Nanotechnology
Jing Lin, Xiaohai Yuan, Gen Li, Yang Huang, Weijia Wang, Xin He, Chao Yu, Yi Fang, Zhenya Liu, Chengchun Tang
As a kind of macroscopic BN architectures, ultralight BN cellular materials with high porosity and great resilience would have broad range of applications in energy and environmental areas. However, creating such BN cellular materials in a large size has still been proven challenging. Here we report on the unique self-assembly of one-dimensional (1D) porous BN microfibers into an integral three-dimensional (3D) BN foam with open-cell cellular architectures. An ultrasonic-assisted self-assembly, freeze-drying and high-temperature pyrolysis process has been developed for the preparation of cellular BN foam with large size and desired shape...
December 8, 2017: ACS Applied Materials & Interfaces
Sarah M Greening, Katherine N Robertson, Alison Thompson
A series of synthetic analogs of the tripyrrolic natural product prodigiosin were complexed with boron trifluoride to generate the corresponding F-BODIPYs. The maximum wavelengths of absorption and emission of the pyrrolyldipyrrin F-BODIPYs were tuned through variation of the substituents about the pyrrolyldipyrrinato core. The limited variation of substituents on the C-ring did not significantly affect absorption and emission. However, variation of substituents on the B-ring and A-ring resulted in a corresponding red-shift in absorption and emission reaching maximum wavelengths of 600 nm...
December 8, 2017: Photochemical & Photobiological Sciences
Ji Feng Shao, Naoki Yamaji, Xin Wei Liu, Kengo Yokosho, Ren Fang Shen, Jian Feng Ma
Boron is especially required for the growth of meristem and reproductive organs, however, the molecular mechanisms underlying the preferential distribution of B to these developing tissues are poorly understood. Here, we show evidence that a member of nodulin 26-like intrinsic protein (NIP), OsNIP3;1, is involved in this preferential distribution in rice. OsNIP3;1 was highly expressed in the nodes and its expression was up-regulated by B deficiency, but down-regulated by high B. OsNIP3;1 was polarly localized at the xylem parenchyma cells of enlarged vascular bundles of nodes facing toward the xylem vessels...
December 7, 2017: Plant Physiology
Felipe Weidenbach Degrazia, Vicente Castelo Branco Leitune, Fernanda Visioli, Susana Maria Werner Samuel, Fabrício Mezzomo Collares
OBJECTIVE: The aim of this study was to evaluate physicochemical properties, long-term microtensile bond strength and cytotoxicity of methacrylate-based adhesive containing boron nitride nanotubes (BNNTs) as fillers. METHODS: A dental adhesive was formulated using BisGMA/HEMA, 66/33wt% (control). Inorganic BNNT fillers were incorporated into the adhesive at different concentrations (0.05, 0.075, 0.1 and 0.15wt%). Analyses of degree of conversion (DC), polymerization rate [Rp...
December 4, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
Vivekchandra Guruprasad Mishra, Mrinal Kanti Das, Dipti Jayesh Shah, Subbiah Jeyakumar, Bhupendra Singh Tomar, Karanam Lakshminarayana Ramakumar
Determination of concentrations of micronutrients in plant samples is important in order to assess the growth and quality of plants. An ion chromatography (IC) method was developed for the simultaneous determination of B, Cl and Mo (micronutrients present in their anionic form in aqueous samples) using a gradient elution with d-mannitol and NaOH. Despite their different chemical nature, these elements could be separated from the matrix by employing pyrohydrolysis. IC was employed for their sequential determination from single aliquot injection into the IC column...
December 4, 2017: Journal of Chromatography. A
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