Chemical and biochemical similarity

Many of the components of PCB and PBB mixtures are both lipophilic and stable, chemically and biochemically. Similar to the persistent organochlorine insecticides and their stable metabolites, they can undergo strong bioconcentration and bioaccumulation to reach relatively high concentrations in predators. 

The most important stages of similarity in process and bioprocess engineering are (a) geometric similarity, (b) mechanical similarity, (c) thermal similarity, and (d) chemical and biochemical similarity. 

Chemical and biochemical similarities are associated with transformations due to chemical or biochemical reactions within the system. According to Johnstone and Thrings (1957), Geometrically and thermally similar systems are chemically similar when corresponding concentration dijferences bear a constant ratio to one another and when the systems, if moving, are kinematically similar."... 

Oxidation of DMS to DMSO and DMSO. DMS is chemically and biochemically oxidized to dimethylsulfoxide (DMSO). Mechanisms for the in situ oxidation of DMS to DMSO in seawater have received little attention, even though this may be an important sink for DMS. Hydrogen peroxide occurs in surface oceanic waters (22) and is produced by marine algae (98). It may participate in a chemical oxidation of DMS, since peroxide oxidizes sulfides to sulfoxides (991. Photochemical oxidation of DMS to DMSO occurs in the atmosphere and DMSO is found in rain from marine regions (681. DMS is also photo-oxygenated in aqueous solution to DMSO if a photosensitizer is present natural compounds in coastal seawater catalyzed photo-oxidation at rates which may be similar to those at which DMS escapes from seawater into the atmosphere (1001. 

To accompany the similarity of chemical and biochemical processes proceeding with membrane catalysts, let us also indicate their specific features, which show the elegancy of Nature s modernization of the chemical conjugation mechanism. 

More recently, Porta and co-workers [6] applied similar considerations of the polar effects to a new one-pot multicomponent process for the addition of nucleophilic radicals to aldimines, generated in situ in the presence of Ti(IV). In analogy with the Minisci reaction, Ti(IV), which acts as a Lewis acid, coordinates the nitrogen of the imine, strongly increasing the electron-deficient character of the carbon in the a-posilion and thus the reactivity of the imine toward nucleophilic radicals. This reaction, as well as the Minisci one, represents a useful route for the synthesis of a variety of poly-functionalized derivatives of chemical and biochemical relevance. 

Looking over the whole mosaic of findings related to degradation, be it in plants, in animals or in the soil, it becomes evident that chemical and biochemical reactions occur at similar sites of the triazine molecule. 

Electrophoretic microfluidic chips feature a number of microreactor characteristics and have been used for conducting chemical and biochemical reactions in channels and microfabricated chambers, mixing reagents, microextraction and microdialysis, post- and preseparation derivatizations, etc. The most recent achievements are reviewed in Ref. 63 and other similar publications. These integrated microdevices perform PCR amplification, cell sorting, enzymatic assays, protein digestion, affinity-based assays, etc. In this section we describe such integrated microsystems and the most recent advances in this field. 

The chemical and biochemical behaviors of humic substances can also be changed by GPC. Frimmel and Sattler (1982) studied the complexation/ adsorption of trace metals by dissolved humic substances and discovered that the affinity of humic substances for metals markedly increased following GPC. Similarly, Stewart and Wetzel (1982) observed that all Sephadex G-lOO fractions of dissolved humic material obtained from the aquatic macrophyte Typha were more stimulatory to C assimilation by algae than were the same humic substances that had not been fractionated. The observations indicated that the gel, eluent, or processing procedure (e.g., lyophilization, reconstitution, cleavage during separation) either reduced the toxicity of the humic substances or enhanced its stimulatory nature or affinity toward trace substances. 

Similar equations but based on other solute descriptors were proposed in literature with the aim of better chromatographic data [Abraham, Ibrahim et al, 2004]. In particular, five solute descriptors, here called LafFort solute descriptors (Table LI), were defined by Laffort et al. using GLC retention data on five stationary phases for 240 compounds [Laffort and Patte, 1976 Patte, Etcheto et al., 1982[. These solute descriptors were used to fit a number of physico-chemical and biochemical properties. Note that in the first paper [Laffort and Patte, 1976[, the five solute descriptors were obtained by Principal Component Analysis on the data obtained from 25 stationary phases for 75 compounds, thus their numerical values differ from those obtained in the later paper. 

Trichlorophenoxyethanol, having a chemical structure closely related to that of the phenoxy compound just mentioned, can undergo similar chemical and biochemical reactions. 

The MIMS method has been used to analyze VOCs in environmental water and air samples as well as in the monitoring of chemical and biochemical processes.MIMS is faster than GC-FID and GC-ELCD. In comparison, the MIMS method in single ion mode was the more sensitive and the linear dynamic ranges were similar to those of the GC-FID method, although not all compounds could be separated because of the similarity of their mass spectra. ... 

Recent studies have described the complex, constitutive, and MeJA- and insect-induced terpenoid defenses in Norway spruce and Sitka spruce at anatomical, chemical, and biochemical levels. " Miller et al. compared the effect of MeJA treatment and white pine weevil attack on induced terpenoid defenses in Sitka spruce. They found that MeJA and real insects induce very similar terpenoid responses at the biochemical and molecular levels. The cloning and functional characterization of a family of ten, functionally diverse Norway spruce TPS genes not only allowed an improved phylogeny of the conifer TPS-d gene family but also allowed a detailed molecular and biochemical characterization of induced changes in terpenoid metabolite profiles in spruce defense. Many of the products of the recently identified Norway spruce TPS genes correspond with components of terpenoid metabolite profiles after MeJA treatment or insect attack in species of spruce. Our work on Norway spruce terpenoid responses to MeJA treatment " is discussed here with an emphasis on those compounds that are products of the newly characterized spruce TPS genes. ... 

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