نتایج جستجو برای: bromine
تعداد نتایج: 2325 فیلتر نتایج به سال:
A method to produce suspensions of graphene sheets by combining solution-based bromine intercalation and mild sonochemical exfoliation is presented. Ultrasonic treatment of graphite in water leads to the formation of suspensions of graphite flakes. The delamination is dramatically improved by intercalation of bromine into the graphite before sonication. The bromine intercalation was verified by...
a new, high yielding method for the preparation of vasicinone (7) is described. reaction of 2-nitrobenzoic acid with n, n¢-carbonyldiimidazole followed by 2-pyrrolidinone gave 1-(2-nitrobenzoyl)pyrrolidine-2-one (3). reduction of the latter with 10% pd-c afforded deoxyvasicinone (4). reaction of deoxyvasicinone (4) with bromine yielded monobromo-deoxyvasicinone (5). exchange of bromine of 5 wit...
Photodissociation of bromine on the Br2(1Piu) state is probed with ultrafast extreme ultraviolet (53.7 nm) single-photon ionization. Time-resolved photoelectron spectra show simultaneously the depletion of ground state bromine molecules as well as the rise of Br(2P3/2) products due to 402.5 nm photolysis. A partial photoionization cross-section ratio of atomic versus molecular bromine is obtain...
Our experience with infrequent and unfamiliar types of injury caused by various compounds of bromine are described and discussed. While bromine containing compounds share some of the characteristics of other common causes of chemical burns, they also have a specific, exclusive mode of affecting the skin. The delay in the appearance of clinical signs and symptoms is an important factor to be con...
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Coplanar polychlorinated/brominated biphenyls (Co-PXBs) belong to a class of structurally similar chemicals known as polyhalogenated aromatic hydrocarbons. We found that the milk of Japanese primiparous and multiparous mothers was similarly contaminated with Co-PXB congeners. Co-PXBs time- and dose-dependently increased ethoxyresorufin-O-deethoxylase (EROD activity) in HepG2 cells. The EROD act...
Indirect UV-absorption spectrometry was shown to be a valuable tool for chemical characterization of functionalized carbon nanotubes (CNTs). It complements data from X-ray photoelectron spectroscopy (XPS) or FTIR analysis since it helps to clarify the type and concentration of functional groups. The principles of indirect application of UV-spectrometry and its mathematical interpretation are di...
Relative yields of C-6, C-8. and C-6 and C-8 substituted catechins obtained from the reaction of (+ )-catechin or 3' 4',57-tetra-O-methvl-( + )-catechin with pyridinium hydrobromide-perbromide, bromine. p-hydroxybenzyl al~oh~I, or o-hydroxybenZyI alcohol showed differing selectivities depending upon the electrophile used. Ratios of C-6 to C-8 substituted products were 1 : 1.2 for the reaction o...
The charge carrier lifetime is an important parameter in solar cells as it defines, together with the mobility, the diffusion length of the charge carriers, thus directly determining the optimal active layer thickness of a device. Herein, we report on charge carrier lifetime values in bromine doped planar methylammonium lead iodide (MAPbI3) solar cells determined by transient photovoltage. The ...
The crystal structure of the title compound, C7H4BrNO, has been determined, revealing a partial mol-ecular packing disorder such that a 180° rotation of the mol-ecule about the phenol C-O bond results in disorder of the bromine and nitrile groups. The disorder has been parameterized as a disorder of only the bromine and nitrile substituents on a unique phenol ring. An intra-molecular O-H⋯Br con...
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