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At least 577 records · Page 32Linked to original sources
PubMed2006

[Synthesis of fluorine compounds based on special properties of fluorine compounds].

This review describes new syntheses of organofluorine compounds taking advantage of the special properties of fluorine compounds as synthones. The main reactions presented are as follows: 1) Trifluoromethylation of aryl or alkyl halides. Application of this reaction for the synthesis of fluorine analogues of nucleic acid bases is discussed. 2) Some syntheses of trifluoromethyl compounds using the Diels-Alder or the 1,3-dipolar reaction, trifluoromethylated carbene, and photoreaction. 3) The Friedel-Crafts reaction of 3,3,3-trifluoropropene, where linear alkylation occurs due to electronic effect of the trifluoromethyl group in good contrast with the Friedel-Crafts reaction of propene. 4) The ene reaction of trifluoromethylated carbonyl compounds, which work as good enophiles. Application of this reaction to the synthesis of trifluoro analogues of terpenes is discussed. 5) The ene reaction of trifluoromethylated imines. 6) Reaction of halothane, which has a highly acidic hydrogen and two halogens adjacent to the trifluoromethyl group and shows interesting reactivities with various bases and metals to give products with unexpected structures. 7) Reaction of 2-bromo-2,2-difluoroacetate with Cu, where the cross-coupling reaction, Michael-type reaction, and radical reaction for different types of difluoroacetates are presented. 8) Reaction of 2-bromo-2,2-difluoroacetate in the presence of Rh catalyst. This reaction provided a new methodology for the introduction of fluoroalkyl substituents to the alpha-position of alpha,beta-unsaturated ketones. The Rh catalyst solved some difficulties in the introduction of difluoroacetate to carbonyl compounds (Reformatsky reaction). Application of this reaction to imines provided easy access to beta,beta-difluoro-beta-lactams.

Acetylene↗
PubMed2003

Phase-slope and group-dispersion calculations in the frequency domain by simple optical low-coherence reflectometry.

We report a new method by which phase slope and group dispersion can be calculated with a simple optical low-coherence reflectometer to quantify physiological conditions. A discrete-time signal processing algorithm based on the first and second derivatives of the phase with respect to wave number was developed from discrete-time Fourier properties. The algorithm avoids the 2pi ambiguity associated with most phase unwrapping. Experimental data collected by use of well-characterized optical materials validated the algorithm, which was minimally sensitive to phase noise. The group dispersion of bovine cornea was measured at various hydrations and was significantly dependent on hydration. The results suggest that group dispersion is an indicator of corneal alterations.

Algorithms↗
PubMed1998

A new era in halitosis and periodontal treatment.

An effective, 12 hour, anti-halitosis remedy is a spectacular breakthrough in the dental field and a significant step toward improving the lives of millions of people in the United States who suffer from chronic halitosis and the resultant psychological trauma. The technology contained in TriOral Anti-Halitosis Treatment Rinse, along with its significant research, will provide dentists with the ability to accelerate their halitosis treatment success curve. I am excited to present the science of this product and resulting research in my upcoming seminar series, and I view this as one of my greatest contributions to other dental professionals and their patients.

Bacteria, Anaerobic↗
PubMed1992

[The effect of heavy metal salts on the embryonic development of the common frog].

To elaborate methods of biological testing during monitoring of the environment, a study was made of the effect of heavy metal salts on frog embryos and of the influence of temperature on the extent of toxicity of these substances. It was shown that the early stages of embryogenesis were more sensitive to this toxic effect. The differences in the effect of heavy metals are expressed not only in the extent of toxicity, but also in the pattern of change in toxicity as related to concentration. A rise in temperature of the solution containing heavy metals results in a relative increase in the number of abnormal larvae, whereas a decrease in temperature of the solution leads to a higher mortality at the earliest stages of embryogenesis. The latter, apparently, is due to a longer duration of development at low temperature, and thus, to a longer exposure of embryos to toxic effect. This is more pronounced at earlier stages of development, more vulnerable (sensitive) to toxicants. The estimation of toxicity of a substance by the pathological changes induced in embryos and larvae is one of the most sensitive methods, which allows not only to determine the extent of toxicity, but also to give prognosis of its possible effect on the population.

Animals↗
PubMed1978

[Isatin-enzyme interactions. VI. Inhibition of rat kidney alkaline phosphatase].

Interaction of isatin with rat kidney alkaline phosphatase has been studied. Mode of attachment of isatin with the enzyme protein is most likely through amino group(s), which is also imperative for catalysis. Sulphydryl group(s) do not seem to be involved in enzyme action. Zinc is also needed for enzyme activity. Use of sulphydryl compounds suggests that isatin inhibition of the enzyme is through attachment at the metal site. However, this inhibition may not only be due to simple chelation of the metal by isatin.

Alkaline Phosphatase↗
PubMedDate not supplied

[Effect of carbostimulin on biosynthetic processes in rabbits with alloxan diabetes].

In rabbits with alloxane diabetes the intensity of [I-14C] glycine label incorporation into various tissue components is considerably lowered. Stimulation of carboxylation in animals under these conditions intensifies the label incorporation into proteins of the liver, kidneys, spleen as well as into blood serum albumin and globulin. The level of lipids, glycogen in the liver, the total content of proteins in blood serum and their specific radioactivity increase. All this evidences for intensification of biosynthetic processes and for a possibility to normalize the metabolism with diabetes by stimulating the processes of carboxylation.

Animals↗
PubMedDate not supplied

[Treatment of anemia in pregnant women by a complex method with application of carbostimulin].

The medicinal effect of carbostimulin was studied under conditions of anemia in pregnant women. A group of pregnant women (n-54) who were given carbostimulin in addition to the ordinary antianemic therapy showed a 2.5-fold increase of erythrocytes and 1.6-fold rise of hemoglobin as compared to the control group. The number of labour complications decreased: a 5-fold decrease was observed for the intrauterine hypoxia of the fetus and the amount of delayed labour. The percentage of labour with surgical intervention lowered from 40.0 down to 18.5. The frequency of the instrumental examination of the womb cavity and digital removal of the placenta were 6 and 3.4 times as low, respectively. The number of children of small weight became more than twice as low (from 27 up to 12.2%). There were less newborns in the state of light and heavy asphyxia (1.5 and 3.7 times, respectively). No cases of perinatal mortality were observed. Parameters of the newborns peripheral blood improved.

Anemia↗
PubMed1997

The protective effect of zinc on rosin and resin acid toxicity in human polymorphonuclear leukocytes and human gingival fibroblasts in vitro.

Combinations of rosin and zinc are used in dentistry as components of periodontal dressings and cements and as root canal sealers. The composition and properties of rosins differ largely depending on source and refinement processes. Rosin (colophony) is composed of approximately 70% resin acids. In order to study the toxic effects of different natural rosins and purified resin acids and the detoxifying effects of zinc, these compounds were analyzed and tested on human polymorphonuclear leukocytes (PMN cells) and human gingival fibroblasts using the radiochromium release method. The rosins and the pure resin acids showed a strong dose-related cytotoxicity, which was inhibited by increased zinc concentrations. The purified resin acids (isopimaric, levopimaric, and neoabietic acid) were more toxic than the natural rosins. The contents of these resin acids might explain the difference in toxicity of the rosins tested. It is concluded that rosin and zinc are not to be considered inert compounds and that the cytoprotective effects of zinc and its role in dentistry products merit further investigations.

Adult↗
PubMed2000

Synthesis and characterization of a series of zinc bis[(alkyl)(trimethylsilyl)amide] compounds.

A series of 21 secondary (alkyl)(trimethylsilyl)amines HNR(TMS) [R = n-propyl (1), i-propyl (2), n-butyl (3), i-butyl (4), s-butyl (5), tert-butyl (6), c-pentyl (7), n-pentyl (8), i-pentyl (9), l-methylbutyl (10), 2-methylbutyl (11), 1-ethylpropyl (12), 1,2-dimethylpropyl (13), tert-pentyl (14), phenyl (15), c-hexyl (16), n-hexyl (17), N,N-dimethyl-3-aminopropyl (18), benzyl (19), n-heptyl (20), 1,1,3,3-tert-butyl (21); TMS = Si(CH3)3] has been prepared and fully characterized by elemental analyses, multinuclear (1H, 13C, 29Si, 14N) NMR, IR, UV/vis, MS, and boiling point. A new method for determination of boiling points of milligram-size samples, based on DSC (differential scanning calorimetry), is described. Each amine has been converted to the corresponding zinc bis(amide) compound Zn[N(TMS)(R)]2 [R = n-propyl (22), i-propyl (23), n-butyl (24), i-butyl (25), s-butyl (26), tert-butyl (27), c-pentyl (28), n-pentyl (29), i-pentyl (30), 1-methylbutyl (31), 2-methylbutyl (32), 1-ethylpropyl (33), 1,2-dimethylpropyl (34), tert-pentyl (35), phenyl (36), c-hexyl (37), n-hexyl (38), N,N-dimethyl-3-aminopropyl (39), benzyl (40), n-heptyl (41), 1,1,3,3-tert-butyl (42); TMS = Si(CH3)3] and subsequently fully characterized by elemental analyses, multinuclear (1H, 13C, 29Si, 14N) NMR, IR, UV/vis, MS, and TGA. The experimental IR has been compared to the computationally calculated one for compound 27. Observed trends in volatility of the compounds are discussed in the context of the dominant intermolecular forces present in the condensed phase.

Journal Article↗
PubMedDate not supplied

Identification of a crystalline cyanide-containing compound in blast furnace sludge deposits.

During blast furnace operation, a cyanide-containing muddy waste referred to as blast furnace sludge is generated in large amounts. In Germany it was and is still common practice to pump this sludge into surface deposits. Depending on species, cyanide has very different toxicity. To this day there is no information about the type of cyanide occurring in blast furnace sludge deposits. In order to identify the type of cyanide we investigated by means of wet chemical and powder X-ray diffraction analyses 37 samples of three blast furnace deposits. Wet chemical results indicate that both the extremely toxic free cyanide (HCN and CN ) and toxic weak metal-cyanide complexes, for example [Zn(CN)4]2-, are not present in the sludge. By powder X-ray diffraction we identified the crystalline cyanide-containing compound potassium zinc hexacyanoferrate(II) nonahydrate, K2Zn3[Fe(CN)6]2 x 9H2O, as the cyanide-bearing compound. Our study is the first that identifies potassium zinc hexacyanoferrate(II) nonahydrate in the environment. As the iron-cyanide complex [Fe(CN)6] is not acutely toxic, any direct hazard comes from cyanide occurring in the investigated wastes. Under the predominant pH milieu of the sludge (pH about 8) the solubility of potassium zinc hexacyanoferrate(II) nonahydrate is low, thus minimizing the mobility of cyanide.

Environmental Monitoring↗
PubMed2004

Alkyl- or arylthiolation of aryl iodide via cleavage of the S-S bond of disulfide compound by nickel catalyst and zinc.

Various aryl sulfides can be synthesized by nickel-catalyzed alkyl- or arylthiolation of aryl iodide with a disulfide compound. This reaction produces Ni(0) from NiBr2-bpy by the reduction with zinc, and this generated complex works as an activating species to convert ArI into ArSR under neutral conditions. Furthermore, this system enables the use of two RS groups in (RS)2.

Journal Article↗