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PubMed2005

First reaction of a bare silicon surface with acid chlorides and a one-step preparation of acid chloride terminated monolayers on scribed silicon.

Methyl-terminated and acyl chloride terminated monolayers are produced when silicon is scribed under mono- and diacid chlorides, respectively. To the best of our knowledge, this is the first report of the reaction between a bare silicon surface and acid chlorides. This reaction takes place by wetting the silicon surface in the air with the acid chloride and scribing. Scribing activates the silicon surface by removing its passivation layer. We propose that scribed silicon abstracts chlorine from an acid chloride to form an Si-Cl bond and that the resulting acyl radical diffuses back to the surface to condense with the surface and form an alkyl monolayer. X-ray photoelectron spectroscopy (XPS) confirms the presence of chlorine and shows a steady increase in the amount of carbon with increasing alkyl chain lengths of the acid chlorides. Time-of-flight secondary ion mass spectrometry shows SiCl(+) species and a steady increase in representative hydrocarbon fragments with increasing alkyl chain lengths of the acid chlorides. XPS indicates that diacid chlorides react primarily at one of their ends to create acyl chloride terminated surfaces in a single step. The resulting surfaces are shown to react with various amines (piperazine, morpholine, and octylamine) and a protein. Calculations at Hartree-Fock and density functional theory levels are consistent with the proposed mechanism.

Journal Article↗
PubMed1978

Gas chromatographic studies of vinyl chloride in air by catalytic hydrogenation to ethyl chloride.

In order to investigate the amount of vinyl chloride in air, the hydrogenation of vinyl chloride to ethyl chloride is used. This method of determination is preferable to the other methods described in the literature because: (a) it proves that only vinyl chloride goes through hydrogenation by its displacement to the ethyl chloride peak in the chromatogram; (b) the actual amount of vinyl chloride can be obtained in the case of superimposed or interfering peaks (e.g., various gases contained in air samples), either by calculating the ethyl chloride peak area or by the reduction of the peak area in the region of the same retention time as the vinyl chloride peak in the related chromatogram. In this study various kinds of catalysts for hydrogenation purposes at temperatures ranging from -20 to 250 degrees have been used. Among the catalysts used palladium gives the best results at low temperature.

Air Pollutants↗
PubMed1989

A flavor paired with lithium chloride blocks the formation of a pentobarbital-lithium chloride association.

Thirsty rats were used in order to determine whether a vinegar solution, which had been paired with an injection of lithium chloride, could block the formation of an association between a pentobarbital- and a lithium chloride-induced state. During phase 1 the rats in the blocking group had a 2.0% vinegar solution paired with an injection of 240 mg/kg of lithium chloride, during phase 2 these rats were reexposed to the vinegar prior to each injection of 20 mg/kg of pentobarbital and 240 mg/kg of lithium chloride, and during phase 3 these rats were given access to a novel 0.75% saccharin solution and were injected with pentobarbital after saccharin removal. Animals with this history did not form an association between the pentobarbital- and lithium chloride-induced states during phase 2 as evidenced by their refusal to consume the saccharin solution over repeated pairings of saccharin with pentobarbital during phase 3. Control groups that received forward pairings of pentobarbital and lithium chloride, in the absence of a previously conditioned vinegar solution during phase 2, formed an association between pentobarbital and lithium chloride. These findings indicate that drug states and flavors can interfere with each others' capacity to predict the occurrence of lithium chloride.

Acetates↗
PubMed2001

Formation of dioxins during the combustion of newspapers in the presence of sodium chloride and poly(vinyl chloride).

Exhaust gases from the combustion of newspaper alone, from branches of London plane tree alone, and from newspapers mixed with sodium chloride (NaCl), polyethylene, or poly(vinyl chloride) (PVC) were collected. The samples were analyzed for dioxins by gas chromatography/mass spectrometry. Total amounts of dioxins found in the samples were 0.186 ng/g from newspapers alone, 1.42 ng/g from the branches of London plane, 102 ng/g from newspapers impregnated with sodium chloride (CI wt % = 3.1), 101 ng/g from newspapers impregnated with sodium chloride mixed with PVC (Cl wt % = 2.6), and 146 ng/g from newspapers mixed with PVC (Cl wt % = 5.1). Samples with a higher chloride content produced more dioxins, and there is a clear correlation between dioxin formation and chloride content. The amount of dioxins formed in the samples according to the number of chlorides was Cl5 > Cl4 > Cl6 > Cl7 > Cl8 in PCDD isomers and Cl4 > Cl5 > Cl6 > Cl7 > Cl8 in PCDF isomers, except in the case of newspapers alone. Benzofurans composed 78-92% of the total dioxins formed in the exhaust gases. The higher the number of the chlorides, the lower the production of benzofuran observed. NaCl vaporized at the temperature of the flame used for combustion of the samples (760-1080 degrees C). The results indicate that NaCl and PVC contribute significantly to dioxin formation from waste materials combusted in incinerators.

Air Pollution↗
PubMed1993

Effect of cytoplasmic chloride concentration on open-state preference of glycine-activated chloride channels in cultured spinal cord cells.

1. Glycine was bath-applied to outside-out patches taken from cultured mouse spinal cord neurons. Glycine-activated chloride channels had at least six open states with permeabilities of 40 (A), 68 (B), 100 (C), 145 (D), 180 (E), and 250 (F) al/s (1 attoliter = 10(-18) liter). Usually no more than two such states were seen in any given patch. The usual extracellular chloride concentration was 157 mM; chloride concentration in the electrode (on the cytoplasmic face of the patch) was varied between 7 and 170 mM, replaced at lower concentrations with either of the inert anions gluconate or methane sulphonate. 2. With normal (7 mM) chloride concentration in the electrode, openings to state D were the most probable, and the average permeability of all openings was 115 al/s. When the cytoplasmic chloride concentration was 20 mM, the most probable open state was the lower-permeability state (C), and the average permeability was 92 al/s. In symmetrical 170 mM chloride, the most probable open state was B and the mean permeability 77 al/s. 3. The glycine-activated channels had a vanishingly small permeability to fluoride. However, in experiments in which 150 mM gluconate in the pipette was replaced by fluoride, the most probable open state was B, as in the high-chloride solution. Thus the two halides had similar effects on open state preference. 4. With external and internal chloride concentrations of 7 and 157 mM, respectively, single-channel current-voltage relations could be fit with constant field relations appropriate to one or more of the permeability states.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Blocking chloride channels in the rat lens: localized changes in tissue hydration support the existence of a circulating chloride flux.

PURPOSE: To investigate the effects of inhibitors of chloride channels on lens volume and tissue architecture under isotonic conditions. METHODS: Rat lenses were maintained in organ culture under isotonic conditions in the presence of various putative chloride channel inhibitors. The effect of an inhibitor on lens wet mass and tissue morphology was determined by weighing and histologic examination, respectively. RESULTS: Exposure to 100 microM of either 5-nitro-2- (3-phenylpropylamino) benzoic acid (NPPB) or 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) caused an increase in wet mass and severe tissue disruption in the lens equatorial region. Two distinctly different zones of tissue damage were evident: a peripheral zone of fiber cell swelling and an inner zone of extensive tissue breakdown. Extracellular space dilations caused the extensive tissue damage in the inner zone and preceded the peripheral fiber cell swellings. That the observed effects were a consequence of the inhibition of chloride channels was supported by (1) the effectiveness of NPPB at the lower dose of 10 microM, (2) the absence of any NPPB effect in chloride-free medium, and (3) an identical effect after exposure to tamoxifen, an inhibitor of the chloride channel regulator p-glycoprotein. CONCLUSIONS: Study results indicate that chloride channels are active in the lens under isotonic conditions. The spatial and temporal pattern of morphologic changes that was observed is consistent with a steady state efflux of chloride ions and water from peripheral fiber cells and a corresponding influx into fiber cells deeper in the lens. These observations may therefore represent the first visualization of the chloride flux postulated by others to be a component of the lens internal circulation system.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1997

Enzymatic assay for chloride ion with chloride-dependent sarcosine oxidase created by site-directed mutagenesis.

Serum chloride ion is routinely assayed in clinical laboratories. We have developed a new enzymatic assay for determining the chloride ion concentration. The method involves the use of a mutant sarcosine oxidase, which was created as desired by site-directed mutagenesis and showed chloride-dependent activity. The enzyme which is reactivated by the chloride ion forms hydrogen peroxide from sarcosine. The production of hydrogen peroxide is measured by the 4-amino-antipyrine peroxidase system. The increase of the reaction rate was proportional to the chloride ion concentration. A lag time of the time course was not observed, and the reaction rate for a blank was not detected. Therefore, a rate assay could be adopted. A standard curve of the assay reagent was linear up to 180 mM chloride ion of the sample. The specificity for the bromide ion was 43% of that of the chloride ion, although it was 0% for other ion species. When serum samples were used, within-day coefficient variations (CVs) and day-to-day CVs were below 1.5%. A good correlation with the comparison assay was observed by using 160 samples of normal and abnormal patient sera. This method can easily and reliably be used for the accurate determination of chloride ion concentration in serum or other samples.

Amino Acid Sequence↗
PubMed1979

Chloride cells and chloride exchange in the skin of a sea-water teleost, the shanny (Blennius pholis L.).

The fine structure of the skin and its importance in chloride outfluxes were investigated in a sea-water teleost, the shanny (Blennius pholis L.). The epidermis is composed of three cells types: epithelial cells, mucous cells and chloride cells. These chloride cells typically contain a great number of mitochondria and an extensive agranular reticulum extending through the whole cell body. They open at the surface of the epidermis into an apical pit. An undifferentiated small cell is often observed near these chloride cells and probably corresponds to the "adjacent chloride cell". The values of chloride outfluxes through the skin and the gills are respectively 5333+/-884 muEq.h-1.kh-1 and 4479+/-2521 muEq.h-1.kg-1; n = 6; t degrees = 13+/-0.5 degrees C. Thus the ratio between skin chloride outflux and total chloride outflux is 64.7 +/- 9.3%.

Animals↗
PubMed1985

Determination of chloride procedure based upon diffusion of hydrogen chloride.

We describe a simple, inexpensive sample preparation method that involves the isolation of chloride as hydrogen chloride from serum and urine prior to chloride analysis with the chloride ion-selective electrode. Chloride analyses of clinical chemistry standards with the present method were found to be in good agreement with analyses reported by the manufacturer. Reliability of the method is also evident by complete recovery of chloride added to serum and urine, minimal day-to-day variation of analyses, and a coefficient of variation that generally is less than 2%. An evaluation of factors influencing the procedure is also reported. The usefulness of the chloride ion-selective electrode to determine chloride in serum or urine is greatly enhanced by the sample preparation method described since matrix interference by other sample components is removed prior to analysis.

Chlorides↗
PubMed1993

Determination of the intracellular free chloride concentration in rat brain synaptoneurosomes using a chloride-sensitive fluorescent indicator.

The chloride-sensitive fluorescent indicator MQAE (N-(6-methoxyquinolyl) acetoacetyl ester) has been used for determination of the intracellular free chloride concentration in rat brain synaptoneurosomes. Loading of the synaptoneurosomes with MQAE occurs by transmembrane diffusion. Calibration of the intracellular MQAE was done by determining the correlation between fluorescence intensity and intrasynaptoneurosomal Cl- concentration in the presence of the Cl-/OH- exchanger tributyltin and the K+/H+ exchanger nigericin, starting from zero Cl- concentration. The total quenchable signal of MQAE was determined by adding KSCN in the presence of the K+ ionophore valinomycin. The correlation between the reciprocal of the fluorescence intensity and the chloride concentration was linear at least up to 50 mM Cl-. The fluorescence of freshly prepared synaptoneurosomes was then measured and the obtained value was plotted into the calibration curve and the corresponding Cl- was read. The mean intrasynaptoneurosomal chloride concentration was 14 +/- 4 mM. We also quantitatively estimated the Cl- flux after addition of the barbiturate, pentobarbitone that opens GABAA receptor-Cl(-)-channels, to the synaptoneurosomes. An addition of 1 mM pentobarbitone corresponded to an approx. 0.59 mM change in the intrasynaptoneurosomal free chloride concentration. The results show that the chloride-sensitive fluorescent indicator MQAE is a useful tool when determining intracellular chloride activity, and in quantitative determination of chloride fluxes in living cells and subcellular preparations.

Animals↗
PubMed1984

Segmental chloride and fluid handling during correction of chloride-depletion alkalosis without volume expansion in the rat.

To determine whether chloride-depletion metabolic alkalosis (CDA) can be corrected by provision of chloride without volume expansion or intranephronal redistribution of fluid reabsorption, CDA was produced in Sprague-Dawley rats by peritoneal dialysis against 0.15 M NaHCO3; controls (CON) were dialyzed against Ringer's bicarbonate. Animals were infused with isotonic solutions containing the same Cl and total CO2 (tCO2) concentrations as in postdialysis plasma at rates shown to be associated with slight but stable volume contraction. During the subsequent 6 h, serum Cl and tCO2 concentrations remained stable and normal in CON and corrected towards normal in CDA; urinary chloride excretion was less and bicarbonate excretion greater than those in CON during this period. Micropuncture and microinjection studies were performed in the 3rd h after dialysis. Plasma volumes determined by 125I-albumin were not different. Inulin clearance and fractional chloride excretion were lower (P less than 0.05) in CDA. Superficial nephron glomerular filtration rate determined from distal puncture sites was lower (P less than 0.02) in CDA (27.9 +/- 2.3 nl/min) compared with that in CON (37.9 +/- 2.6). Fractional fluid and chloride reabsorption in the proximal convoluted tubule and within the loop segment did not differ. Fractional chloride delivery to the early distal convolution did not differ but that out of this segment was less (P less than 0.01) in group CDA. Urinary recovery of 36Cl injected into the collecting duct segment was lower (P less than 0.01) in CDA (CON 74 +/- 3; CDA 34 +/- 4%). These data show that CDA can be corrected by the provision of chloride without volume expansion or alterations in the intranephronal distribution of fluid reabsorption. Enhanced chloride reabsorption in the collecting duct segment, and possibly in the distal convoluted tubule, contributes importantly to this correction.

Absorption↗