نتایج جستجو برای: hexamethylenetetramine bromine
تعداد نتایج: 2569 فیلتر نتایج به سال:
In the official method for determination of total bromine in fruit and grain foods, bromine is derivatized with 3-pentanone for GC analysis. Co-existing substances sometimes interfere with measurement of the derivative, though the method is highly selective. In this study, the notification method was modified to reduce impurity peaks by applying 3-hexanone. Samples were alkalized and reduced to...
Occasionally children are the victims of mass poisoning from an environmental contaminant that occurs due to an unexpected common point source of exposure. In many cases the contaminant is a widely used chemical generally considered to be safe. In the following case, members of a sports team visiting a community for an athletic event were exposed to chemicals while staying at a local motel. Bro...
Iodine is an essential trace element for all mammals and may also influence climate through new aerosol formation. Atmospheric bromine cycling is also important due to its well-known ozone depletion capabilities. Despite precipitation being the ultimate source of iodine in the terrestrial environment, the processes effecting its distribution, speciation and transport are relatively unknown. The...
Dehydrohalogenation of 5,6-dihalogen-1,3-dioxepanes II with KOH/MeOH or NaOCH3/MeOH under controlled reaction conditions gave mainly 5-halogen-4,7-dihydro-1,3-dioxepines III. Further substitution of vinylic-bromine in III whit KO-t-Bu/tert-BuOH or KOH/MeOH led to corresponding 5-substituted-4,7-dihydro-1 ,3-dioxepines some of which underwent spontaneous isomerization to 6,7-dihydro-1,3-dioxepin...
We report transient grating measurements carried out on single crystals of bromine clathrate hydrates and on bromine dissolved in water. In all cases, excitation into the B-state of Br2 leads to prompt predissociation, followed by cage-induced recombination on the A/A' electronic surfaces. In liquid water, the vibrationally incoherent recombinant population peaks at t=1 ps and decays with a tim...
Haloacetamides (HAcAms) are an emerging class of nitrogenous disinfection by-products (N-DBPs) of health concern. However, there are very limited data on the formation and speciation of the nine bromine- and chlorine-containing haloacetamides (HAcAm9). In the study, their formation and speciation during chlor(am)ination were investigated for a group of waters with a range of specific ultraviole...
[1] Measurements of BrO suggest that inorganic bromine (Bry) at and above the tropopause is 4 to 8 ppt greater than assumed in models used in past ozone trend assessment studies. This additional bromine is likely carried to the stratosphere by short-lived biogenic compounds and their decomposition products, including tropospheric BrO. Including this additional bromine in an ozone trend simulati...
Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called "bromine explosions" and we employ a 1-D chemistry...
In an attempt to fractionate Cg acids produced by Ascaris with the aid of partition chromatography, it was noted that one fraction had distribution characteristics resembling those of n-valeric acid (2). Elution of this fraction began earlier than, but was completed simultaneously with, that of n-Valerie acid. Therefore, it appeared that this fraction may consist of at least two components. Evi...
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