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Chemical Activation (chemical + activation)
Selected AbstractsThe behavioral importance of dynamically activated descending inhibition from the nucleus reticularis gigantocellularis pars alpha. (University Hospital of Wales, Cardiff, United Kingdom) Pain 2001;92:53,62.PAIN PRACTICE, Issue 4 2001J. Azami This study demonstrates the effects of nucleus reticularis gigantocellularis pars alpha (GiA) on the behavioral response during application of standardized noxious stimuli. As this system is activated in response to noxious stimulation, it is possible that chronic pain states may also activate GiA. Therefore, this study investigated this possibility in animals following partial sciatic nerve ligation (an animal model of chronic pain). Male Wistar rats (280,310 g) were anesthetized with halothane (0.5% to 2% in O2). Guide cannulae for microinjections were stereotaxically placed above GiA. In one group of animals the sciatic nerve was partially litigated. Animals were allowed to recover for 4,6 days. The responses of each animal during the formalin test and the tail flick test were recorded on different days. Microinjections (0.5 ,l) of either ,-aminobutyric acid (GABA, 200 mM), D-L homocysteic acid (DLH, 25 mM), or 0.9% saline (as control) into GiA were preformed during these tests in a randomized, blind manner. In animals without sciatic nerve ligation, microinjection of GABA to GiA did not significantly affect the animal's response during the tail flick test. However, microinjection of DLH significantly increased the latency of tail flick from 6.2 ± 0.8 to 8.4 ± 0.5 seconds for up to 15 minutes. Microinjection of GABA to GiA increased the behavioral response to formalin between 10 and 20 minutes postinjection, while microinjection of DLH reduced this response at all time points except 10 minutes postinjection (n = 8, p < 0.05, Mann-Whitney U -test). In animals with sciatic nerve ligation, microinjections (0.5 ,l) of either GABA (200 mM), or saline (as control) into GiA contralateral to the partial sciatic ligation were performed during these tests in a randomized, blind manner. Partial sciatic ligation significantly reduced the behavioral response to contralaterally applied formalin from 15 minutes postinjection onwards, compared to controls without sciatic nerve ligation. Microinjection of GABA GiA significantly increased the behavioral response to formalin from 20 to 50 minutes postinjection. The inactivation of GiA only causes behavioral effects in nociceptive tests of a long enough duration to activate the system (ie, the formalin test but not the tail flick test). Chemical activation of the system affects both tests. Conclude that these data strongly support the concept of an important analgesic system that is activated in response to noxious stimulation, and subsequently acts to reduce behavioral responses to noxious stimuli. Comment by Leland Lou, M.D. This is a rat study that looked at the presence of inhibitory spinal multireceptive cells modifying and decreasing the behavioural response to noxious stimuli. While no direction was given as to the source of noxious stimuli inhibition in chronic pain, great effort was made to report a possible differential response of the C-fiber pain system versus the large sensory fibers. After review it seems that the authors believed that the nucleus reticularis gigantocellularis pars alpha maybe a central processor of the inhibitory response. It is still too early to assess the clinical impact of this study. [source] Facile Conjugation of Biomolecules onto Surfaces via Mussel Adhesive Protein Inspired CoatingsADVANCED MATERIALS, Issue 4 2009Haeshin Lee A new surface bioconjugation strategy is presented. A polydopamine surface coating provides chemical activation on material surfaces, is resistant to hydrolysis, and offers selectivity in coupling of biomolecules via nucleophilic groups through simple pH control. Control of orientation of immobilized biomolecules may be possible using terminally modified DNA or His-containing proteins. [source] Multiple-Well, multiple-path unimolecular reaction systems.INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2001Vibrationally excited 2-methylhexyl radicals formed by shock wave activation or by chemical activation can isomerize by multiple pathways to form any of six stable isomers, can fragment by multiple CH and CC bond fission pathways, and can be collisionally stabilized. Master equation simulations of chemical activation and of shock wave activation are used to explore the generic behavior of this complicated coupled system. Selecting the argon pressure in chemical activation systems that produce the 2-methyl-1-hexyl radical isomer (1) can control the yield of specific isomers. Shock heating of 1 also shows a highly regular sequence of isomer formation. This regular behavior is because the first isomerization steps are faster than subsequent steps. Other radical isomers, such as 2-methyl-3-hexyl (3), do not show such regular behavior, because the first isomerization step is slower than subsequent steps. Incubation and unimolecular rate-constant fall-off are observed in the shock wave simulations. The unimolecular rate-constant fall-off for the coupled system produces low-pressure limiting rate constants proportional to [M]n, where n can be greater than unity. The fact that n can be greater than unity is a natural feature of multichannel coupled unimolecular reaction systems, but detection of the effect in experiments may be very demanding. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 246,261, 2001 [source] Towards waste minimisation in WWTP: activated carbon from biological sludge and its application in liquid phase adsorptionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2002Maria J Martin Abstract Surplus sludge produced during the biological treatment of wastewater requires costly disposal procedures. With increasing environmental and legislative constraints, increasing sludge production and more limited disposal options, new recycling alternatives have to be found. The possibility of obtaining activated carbons from surplus biological sludge by chemical activation with H2SO4 has been investigated. Operational parameters such as the amount of H2SO4 added, the temperature, and activation time were modified to ascertain their influence on the quality of the activated carbon obtained. The quality of the sludge-based activated carbons was evaluated by established characterisation parameters for adsorption from solution such as phenol value, iodine number, methylene blue number and tannin value and compared with commercial activated carbons. Activation at 700,°C for 30,min in the presence of 0.5,cm3 H2SO4,g,1 dry solids in the sludge led to an activated carbon with a good capacity for iodine and tannic acid. The sludge-derived activated carbon obtained is mesoporous in nature with a high presence of large macropores. Weak and moderate acidic surface functional groups were detected on the surface, which impart a hydrophilic nature to the solid. When compared with a commercial activated carbon, the sludge-derived activated carbon performed better when removing dyes with a high presence of anionic solubilising groups and heavy metals. The results indicate that COD adsorption from a biologically-treated effluent may also be an area for application. © 2002 Society of Chemical Industry [source] Kinetic study of the decomposition of 2-butanol on carbon-based acid catalystAICHE JOURNAL, Issue 6 2010J. Bedia Abstract The catalytic conversion of 2-butanol on a carbon-based acid catalyst prepared by chemical activation of olive stone with phosphoric acid was investigated. The carbon catalyst showed a considerable amount of surface phosphorus, presumably in form of phosphate groups, as revealed by XPS, despite a washing step carried out after the activation process. Conversion of 2-butanol yields mainly dehydration products, mostly cis-2-butene and trans-2-butene with lower amounts of 1-butene, and a very small amount of mek as dehydrogenation product. Kinetic interpretation of the experimental data was performed using two elimination mechanisms for the dehydration reaction; an E1-mechanism (two-step mechanism) and an E2-mechanism (one-step mechanism). The rate expressions derived from both models fit properly the experimental results, suggesting that probably the two mechanisms occur simultaneously. This is supported by the similar rate constant obtained for the formation of the carbocation and the olefins in the E1 and E2 mechanisms, respectively. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Expression analysis of genes induced in barley after chemical activation reveals distinct disease resistance pathwaysMOLECULAR PLANT PATHOLOGY, Issue 5 2000Katrin Beßer Salicylic acid (SA) and its synthetic mimics 2,6-dichloroisonicotinic acid (DCINA) and benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH), protect barley systemically against powdery mildew (Blumeria graminis f.sp. hordei, Bgh) infection by strengthening plant defence mechanisms that result in effective papillae and host cell death. Here, we describe the differential expression of a number of newly identified barley chemically induced (BCI) genes encoding a lipoxygenase (BCI-1), a thionin (BCI-2), an acid phosphatase (BCI-3), a Ca2+ -binding EF-hand protein (BCI-4), a serine proteinase inhibitor (BCI-7), a fatty acid desaturase (BCI-8) and several further proteins with as yet unknown function. Compared with SA, the chemicals DCINA and BTH were more potent inducers of both gene expression and resistance. Homologues of four BCI genes were detected in wheat and were also differentially regulated upon chemical activation of disease resistance. Except for BCI-4 and BCI-5 (unknown function), the genes were also induced by exogenous application of jasmonates, whereas treatments that raise endogenous jasmonates as well as wounding were less effective. The fact that BCI genes were not expressed during incompatible barley,Bgh interactions governed by gene-for-gene relationships suggests the presence of separate pathways leading to powdery mildew resistance. [source] | ||||||||||