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PubMed2006

Use of laterite for the removal of fluoride from contaminated drinking water.

The effects of different operational variables on the mechanistic function of laterite in removal of fluoride have been investigated. Thermodynamic parameters such as free energy change, enthalpy, and entropy of the process, as well as the sorption isotherm, were evaluated. The extent of solute removal is determined by initial solute concentration, operational conditions, laterite dose, and solution pH. For a fixed set of experimental conditions, a model equation is developed from which the percent removal corresponding to each load of fluoride is determined. The mechanism of fluoride adsorption is governed by the zero point charge of laterite and follows a first-order rate equation. pH has a vital role influencing the surface characteristics of laterite. To simulate the flow dynamics, fluoride solution was run through a fixed bed column. The pattern of breakthrough curves for different influent fluoride concentration, pH, and column bed height was characterized. The column efficiency was tested from the bed depth-service time model. The elution of the retained fluoride was studied and the effectiveness of column operation was determined by the retention-elution cycles.

Adsorption↗
PubMed2006

Calorimetric studies on the thermal hazard of methyl ethyl ketone peroxide with incompatible substances.

In Taiwan, Japan, and China, methyl ethyl ketone peroxide (MEKPO) has caused many severe thermal explosions owing to its thermal instability and reactivity originating from the complexity of its structure. This study focused on the incompatible features of MEKPO as detected by calorimetry. The thermal decomposition and runaway behaviors of MEKPO with about 10wt.% incompatibilities, such as H(2)SO(4), HCl, NaOH, KOH, FeCl(3), and FeSO(4), were analyzed by dynamic calorimeter, differential scanning calorimetry (DSC) and adiabatic calorimeter, vent sizing package 2 (VSP2). Thermokinetic data, such as onset temperature, heat of decomposition, adiabatic temperature rise, and self-heat rate, were obtained and assessed. Experimental data were used for determining the incompatibility rating on hazards. From the thermal curves of MEKPO with assumed incompatible substances detected by DSC, all the onset temperatures in the other tests occurring earlier advanced, especially with alkaline or ferric materials. In some tests, significant incompatible reactions were found. Adiabatic runaway behaviors for simulating the worst case scenario were performed by using VSP2. These calorimetric data led to the same results that the alkaline or ferric solution was the most incompatible with MEKPO.

Butanones↗
PubMed2003

Adsorption of phosphate from aqueous solution onto alunite.

The phosphate removal potential of alunite, a low cost and abundantly available material, has been investigated. The effects of calcination temperature and time of alunite, adsorbent particle size, pH and initial phosphate concentration on the phosphate adsorption by the calcined alunite have been studied. Phosphate removal was seen to increase with increasing calcination temperature, decreasing adsorbent particle size and pH. Adsorption of phosphate followed first-order rate kinetics. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of phosphate onto calcined alunite fitted to the Langmuir model more than Freundlich model. Specific surface areas of the calcined alunite were calculated at different calcination temperatures and particle sizes.

Adsorption↗
PubMed1985

Mechanism of depolarization of rat cortical synaptosomes at submicromolar external Ca2+ activity. The use of Ca2+ buffers to control the synaptosomal membrane potential.

Rat cortical synaptosomes responded to a reduction of external Ca2+ from pCa 3.5 to pCa 4.8 in the absence of MgCl2 with a slight decrease of internal K+ and an increase of Na+. The effects were prevented by tetrodotoxin or millimolar concentrations of MgCl2. Further lowering of external pCa to 7.7 with N-hydroxyethylethylenediaminetriacetate evoked a rapid fall of internal K+, which was specifically blocked by Ruthenium Red; tetrodotoxin and nifedipine were ineffective. A linear relationship was established between K+ and methyltriphenylphosphonium cation distribution ratios by varying external pCa between 4.8 and 7.7, indicating that K+ efflux resulted from a depolarization of the plasma membrane. An increase of Na+ permeability was suggested by the synaptosomes' gain of Na+ and the disappearance of the depolarization in an Na+-free sucrose medium. According to the constant field equation, the permeability ratio PNa/PK increased from 0.029 at pCa4.8 to 0.090 at pCa 7.7 with plasma membrane potentials of -74mV and -47mV, respectively. Since the plasma membrane responded to variation of external Ca2+ activities in the micromolar range with a graded and sustained depolarization, the use of Ca2+ buffers to control membrane potentials is suggested.

Animals↗
PubMed1997

Rehydration of desiccated Baralyme prevents carbon monoxide formation from desflurane in an anesthesia machine.

BACKGROUND: Desiccated carbon dioxide absorbents degrade desflurane, enflurane, and isoflurane to carbon monoxide (CO) in vitro and in anesthesia machines, which can result in significant clinical CO exposure. Carbon monoxide formation is highest from desflurane, and greater with Baralyme than with soda lime. Degradation is inversely related to absorbent water content, and thus the greatest CO concentrations occur with desflurane and fully desiccated Baralyme. This investigation tested the hypothesis that rehydrating desiccated absorbent can diminish CO formation. METHODS: Baralyme was dried to constant weight. Carbon monoxide formation from desflurane and desiccated Baralyme was determined in sealed 20.7-ml vials without adding water, after adding 10% of the normal water content (1.3% water), and after adding 100% of the normal water content (13% water) to the dry absorbent. Similar measurements were made using an anesthesia machine and circle system. Carbon monoxide was measured by gas chromatography-mass spectrometry. RESULTS: Carbon monoxide formation from desflurane in vitro was decreased from 10,700 ppm with desiccated Baralyme to 715 ppm and less than 100 ppm, respectively, when 1.3% and 13% water were added. Complete rehydration also decreased CO formation from enflurane and isoflurane to undetectable concentrations. Desflurane degradation in an anesthesia machine produced 2,500 ppm CO in the circuit, which was reduced to less than 180 ppm when the full complement of water (13%) was added to the dried absorbent. CONCLUSIONS: Desflurane is degraded by desiccated Baralyme in an anesthesia machine, resulting in CO formation. Adding water to dried Baralyme is an effective means of reducing CO formation and the risk of intraoperative CO poisoning. Although demonstrated specifically for desflurane and Baralyme, rehydration is also applicable to enflurane and isoflurane, and to soda lime.

Anesthesia, Inhalation↗
PubMed1981

A simple method for the use of gallocyanin-chrome alum as an electron strain.

A method has been elaborated for the demonstration of DNA in the electron microscope. The method uses glutaraldehyde fixed tissue pieces from which RNA has been removed by incubation with RNase. DNA is stained by gallocyanin-chrome alum in the tissue block. Embedding and cutting is done in the usual manner. The method is based on histochemical observations at the light microscope level which show sufficient specificity and a good stoichiometry of the staining reaction.

Animals↗
PubMed1991

[Mechanism of myocardial protection with potassium arrest in isolated ischemic rat hearts].

Isolated working rat hearts were exposed to 25 min ischemia, and functional recovery was assessed by aortic flow (AoF) and rate-pressure product (RPP) to evaluate the beneficial effects of potassium (20 mM) induced arrest (K-arrest) prior to ischemia. K-arrest improved the recovery of function after 30 min of reperfusion compared with the control group (%AoF: 68 +/- 6 vs 0%, %RPP: 90 +/- 3% vs 60 +/- 3%, p less than 0.01). The accumulation of Ca++ at the end of reperfusion was less in hearts with K-arrest (2.2 +/- 0.1 vs 4.5 +/- 0.3 mumol/g dry, p less than 0.01). There was no difference between the two groups in high energy phosphate content at the end of ischemia. The increase in intracellular Na+ (Nai) during ischemia was reduced in hearts with K-arrest (delta: 19 vs 46 mumol/g dry), and the level of intracellular K+ (Ki) was higher at the end of ischemia in hearts with K-arrest (341 +/- 4 vs 318 +/- 2 mumol/g dry, p less than 0.01). During the first 5 min of reperfusion, the level of Ki in K-arrested hearts jumped to a higher level than in the control group (delta: 15 vs 2 mumol/g dry, p less than 0.01). The level of Nai was lower in hearts with K-arrest after 5 min of reperfusion. These data suggested that K-arrest might preserve the activity of Na+/K+ ATPase during ischemia and early reperfusion, and that it attenuated the increase in Nai during ischemia and reperfusion, which resulted in less Ca++ overload during reperfusion via the Na+/Ca++ exchange mechanism and led to improved recovery.

Animals↗
PubMed1985

Improved in situ hybridization and G-banding by pretreatment with Denhardt's solution and gelatin-chrome alum.

Various pretreatments of metaphase spreads were examined to obtain optimal DNA labelling patterns while maintaining chromosome integrity during in situ hybridization procedures. Preparations of African green monkey (AGM) chromosomes fixed in methanol-acetic acid (CV-1 cell line) were treated by coating with Denhardt's solution, dilute gelatin-chrome alum, nonfat instant dry milk dissolved in saline-citrate solution (SSC) and/or acetylation prior to denaturation of chromosomal DNA in 70% formamide-2 X SSC for 2 min at 70 degrees C. A 3H-labelled, cloned DNA fragment of the highly repetitive AGM component alpha DNA was hybridized to the chromosomes by incubation at 45 degrees C for 16 h. Treatment with gelatin-chrome alum prior to denaturation greatly improved chromosome morphology and decreased background, but reduced pericentromeric labelling. Sequential treatment with 5 X Denhardt's solution followed by gelatin-chrome alum resulted in enhanced specificity of labelling and excellent chromosome morphology, as well as reduced levels of background. Acetylation had little effect after pretreatment with gelatin-chrome alum, but reduced background levels after pretreatment with Denhardt's solution. Chromosomes treated with Denhardt's solution plus gelatin-chrome alum can be routinely G-banded using trypsin after in situ hybridization.

Animals↗
PubMed1991

The effect of subchronic poisoning with potassium nitrate and sodium nitrite on the processes of intestinal absorption of D-xylose in rats.

The intestinal transport of D-xylose was studied during subchronic poisoning of male Wistar rats with the oral administration of potassium nitrate and sodium nitrite. The metabolic parameters of small intestine mucosa were determined one hour after xylose administration, i.e., Na+/K(+)-ATPase, alkaline phosphatase, oxygen consumption, and lactic acid level. Nitrite reduced the absorption of xylose and decreased the activity of Na+/K(+)-ATPase and alkaline phosphatase. No effect of sodium nitrite was demonstrated on the aerobic metabolism of intestinal mucosa with an increased lactic acid level. Potassium nitrate did not effect the processes of intestinal absorption of xylose nor the metabolic parameters of small intestine mucosa.

Administration, Oral↗
PubMed1991

The effect of acute poisoning with potassium nitrate and sodium nitrite on the processes of intestinal absorption of D-xylose in rats.

The intestinal transport of D-xylose was studied during the acute poisoning of male Wistar rats with orally administered potassium nitrate and sodium nitrite. At the peak of xylose absorption, the metabolic parameters of Na+/K(+)-ATPase, alkaline phosphatase, oxygen uptake, and lactic acid level were determined in the small intestine mucosa. Nitrite in a dose of 80 mg NaNO2/kg b.w. increased the permeability of gastric mucosa for D-xylose and raised the uptake of oxygen by the small intestine mucosa. No changes were observed in the activity of Na+/K(+)-ATPase and alkaline phosphatase. A dose of 10 mg NaNO2/kg b.w. was not followed by increased absorption of this sugar. It was also demonstrated that potassium nitrate had no effect on the process of intestinal absorption of D-xylose and failed to change the determined metabolic parameters of the small intestine mucosa.

Administration, Oral↗