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PubMed2003

Interaction between a capacitor electrolyte and gamma-aluminum oxide studied by Fourier transform infrared spectroscopy.

The interaction between y-aluminum oxide and an ethylene glycol (EG) based capacitor electrolyte was investigated by Fourier transform infrared (FT-IR) spectroscopy. It was found that only a few ingredients of the electrolyte react with the oxide (azelaic acid, poly(1-vinyl-2-pyrrolidone) (PVP), and phosphoric acid); the others act as pH or conductivity buffers (boric acid, ammonia, and water). The adsorption of azelaic acid and PVP from the electrolyte was studied as a function of temperature, pH, and time, and the result was compared to the adsorption from model solutions of simpler composition. The influence of other components such as phosphoric acid both in the electrolyte and on the aluminum oxide was also investigated, as was the presence of water. At low pH and high temperature (T > or = 105 degrees C) the acid formed an ester with EG and this product adsorbed on the oxide surface. The PVP was attached to the adsorbed azelaic acid by hydrophobic interaction, which is pH independent. Ester formation was found to be catalyzed by other electrolyte ingredients like boric acid. At high pH, surface adsorption of azelaic acid occurs through a deprotonated species, which is mainly coordinated through outer-sphere complexation. At high temperature or after a long equilibration time, the surface of the alumina changed, resulting in less adsorption of the organic substances, independent of pH. This change is due to a selective adsorption of phosphate species from the electrolyte, which block active surface sites.

Adsorption↗
PubMed2002

Vibrational spectra of melamine diborate, C3N6H62H3BO3.

IR and Raman spectra of melamine diborate have been recorded and analysed. Band assignments are given based on the vibrations of melamine and boric acid molecules. Three sets of frequencies observed for the N-H stretching mode region is ascribed to different types of hydrogen bonds in the amino groups of the triazine ring. Due to the lower symmetry of the melamine and boric acid molecules in the crystal, activation of inactive modes and lifting of the degeneracy of certain vibrational modes are observed. Lower symmetry of the melamine molecule in the crystal has resulted in the decrease of intensity of the Raman active melamine band around 1490 cm(-1). All the internal modes of boric acid molecule were identified. All the ring breathing modes of melamine molecule show frequency shift towards the high wavenumber side. In other words, hydrogen bonding affects the ring breathing modes of melamine.

Boric Acids↗
PubMed2006

Chronic suppurative otitis media in Tanzanian school children and its effects on hearing.

OBJECTIVES: To compare different treatment regimens of chronic suppurative otitis media (CSOM) in school children, in regard to their consequence in hearing and discharge from the ear drum perforation. DESIGN: Randomised controlled trial. SETTING: Randomly selected primary schools within Dar es Salaam. SUBJECTS: Three hundred and twenty eight children between 5-17 years of age with CSOM in one or both ears. RESULTS: Three to four months after the onset of treatment 31% of group 1, 54% of group 2, and 56% of group 3, had dry ears. Treatment with dry mopping and boric acid in alcohol ear drops was significantly better than dry mopping alone. Adding amoxicillin to the treatment did not improve the end results. Hearing test performed before and after treatment showed that the hearing thresholds were the same or better after the treatment. The possible risk that boric acid in alcohol ear drops should lead to sensorineural hearing loss has not been confirmed. CONCLUSION: Based on the above results, the treatment of choice for CSOM in children in Dar es Salaam should be dry mopping and boric acid in spirit ear drops.

Adolescent↗
PubMed1988

Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

Ionizing radiations were directed at the heads of anesthetized mice in doses that evoked the acute central nervous system (CNS) radiation syndrome. Irradiations were done using either a predominantly thermal neutron field at a nuclear reactor after intraperitoneal injection of 10B-enriched boric acid or 250-kilovolt-peak x-rays with and without previous intraperitoneal injection of equivalent unenriched boric acid. Since 10B concentrations were approximately equal to 3-fold higher in blood than in cerebral parenchyma during the reactor irradiations, more radiation from alpha and 7Li particles was absorbed by brain endothelial cells than by brain parenchymal cells. Comparison of the LD50 dose for CNS radiation lethality from the reactor experiments with the LD50 dose from the x-ray experiments gives results compatible with morphologic evidence that endothelial cell damage is a major determinant of acute lethality from the CNS radiation syndrome. It was also observed that boric acid is a low linear energy transfer radiation-enhancement agent in vivo.

Animals↗
PubMed1987

Drugs that promote renal excretion of riboflavin.

Enhanced urinary excretion of vitamins induced by drugs is a major factor in development of vitamin deficiencies. In addition to increasing urinary excretion, drugs can induce vitamin deficiencies by altering their intestinal absorption, transport, storage, and/or metabolic conversions. Aside from drugs, other factors known to influence urinary excretion of vitamins include the level of the vitamin in the diet, the degree of tissue saturation of the vitamin, and the extent of protein binding of the vitamin. Alterations in various aspects of flavin metabolism have been observed following administration of certain drugs, namely, antimalarial, antimicrobial, anticancer, and some tricyclic antidepressant and antipsychotic agents. Of these drugs, boric acid and its derivatives as well as the antipsychotic agent, chlorpromazine, have been shown to promote riboflavinuria in both animals and man. Boric acid complexes with the polyhydroxyl ribitol side chain of riboflavin and greatly increases its water solubility. Individuals who have accidentally consumed boric acid or one of its derivatives excrete high levels of riboflavin within the first 24 to 48 hours following ingestion. The phenothiazine ring of chlorpromazine and the isoalloxazine ring of riboflavin have a number of structural features in common and have been shown to form a molecular complex in vitro. In animals treated for a 3- and 7-week period with chlorpromazine, urinary levels of riboflavin are twice that of pair-fed, saline-treated animals. Recent studies have extended these findings to humans. The administration of certain agents, either therapeutic or toxic, which enhance urinary riboflavin excretion may be of particular concern for high-risk patients who are already nutritionally compromised because of illness or disease.

Animals↗
PubMed2006

Roles of BOR1, DUR3, and FPS1 in boron transport and tolerance in Saccharomyces cerevisiae.

The roles of three membrane proteins, BOR1, DUR3, and FPS1, in boron (B) transport in yeast were examined. The boron concentration in yeast cells lacking BOR1 was elevated upon exposure to 90 mM boric acid, whereas cells lacking DUR3 or FPS1 showed lower boron concentrations. Compared with control cells, cells overexpressing BOR1 or FPS1 had a lower boron concentration, and cells overexpressing DUR3 had a higher boron concentration. These results suggest that, in addition to the efflux boron transporter BOR1, DUR3 and FPS1 play important roles in regulating the cellular boron concentration. Analysis of the yeast transformants for tolerance to a high boric acid concentration revealed an apparent negative correlation between the protoplasmic boron concentration and the degree of tolerance to a high external boron concentration. Thus, BOR1, DUR3, and FPS1 appear to be involved in tolerance to boric acid and the maintenance of the protoplasmic boron concentration.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1999

[Clinical and bacteriology observation on intraoperation usage of tarivid otic solution in treatment of chronic otitis media with cholesteatoma].

OBJECTIVE: To determine the effect and safety of Tarivid (oflorxacin) otic solution used during the operation in treatment for chronic otitis media with cholesteatoma. METHOD: 42 patients were divided into two groups. In Tarivid group, 23 patients' operative cavities were soaked with 0.3% Tarivid, while other 19 patients' operative cavities in boric acid group were soaked with 4% boric acid during the open mastoidectomy with tympanoplasty. RESULT: The recovery rate was 82.6% and 50% respectively. There was significant difference between two groups (P < 0.05). No side effect was observed. CONCLUSION: It shows that using Tarivid otic solution in the operation can improve the outcome of the operation and has high security.

Adult↗
PubMed1995

Monte Carlo simulation of the biological effects of boron neutron capture irradiation with d(14)+Be neutrons in vitro.

It was shown that radiation effects in tumor cells treated with fast neutrons may be increased by the neutron capture reaction 10B(n, alpha)7Li. The classic approach for macroscopic dosimetry in fast-neutron therapy cannot be applied to the dose in boron neutron capture therapy (BNCT). The effectiveness of BNCT in killing tumor cells depends on the number of 10B atoms delivered to the tumor, the subcellular distribution of 10B and the thermal neutron fluence at the site of the tumor. Monte Carlo calculations of the energy depositions of short-range particles with high LET coming from 10B disintegrations were performed and compared to the observed biological effects. The simulation allows us to study the influence of the localization of intracellular 10B in the nucleus, cytoplasma, plasma membrane or extracellular space. The biological response function which describes the probability of the lethal effect produced by a single particle track through the cell nucleus was found by comparing the calculated microscopic dose distribution spectra for single events with the survival observed experimentally. Calculations for a human melanoma cell population treated as a monolayer in the presence or absence of boron with d(14)+Be neutrons will be demonstrated. Two different boron compounds enriched in 10B were investigated in this study: boric acid (H3 10BO3) and p-dihydroxyboryl phenylalanine (BPA). The study shows that a high fraction of BPA enters the cytoplasm while boric acid was found only in the extracellular space. The computer simulations indicate that BPA yields a higher potential effectiveness for inactivation of melanoma cells than boric acid.

Boron Neutron Capture Therapy↗
PubMed1975

[Possibilities of chemical germ-conservation and its meaning for the bacteriological urine diagnosis].

To estimate the germ-preserving effect of 15 percent disodium-calcium-ethylene-diamine-tetraacetate, 1.8 percent boric acid, 20 percent dimethyl sulfoxide and 3 solutions containing 0.001 percent merthiolate and 15 percent glycerin, 2 percent ethylene-diamine-tetraacetic acid and 15 percent glycerin, and 30 percent NaCl and 3 percent polyvinyl pyrrolidone respectively, comparative investigations were conducted in 4 series comprising a total of 400 urine samples. Boric acid, which is very easy to use, proved the most effective. After 24-h storage at room temperature of boric-acid-preserved urine samples with bacterial counts of over 10-4 per ml, the results were false-negative in 2-4 percent; after 48 h the rate was 6-8 percent and after 72 h nearly 10 percent. There were no false-positive results.

Bacteriological Techniques↗
PubMedDate not supplied

Evaluation and comparison of the growth and viability of yeast-like cells of Paracoccidioides brasiliensis.

The growth and viability of two Paracoccidioides brasiliensis strains were evaluated in PYG and MMcM media containing no boric acid. The two P. brasiliensis strains exhibited a similar growth pattern in PYG medium, which was considered to be good compared with the growth curves in defined MMcM medium without boric acid. Calculation of cell generation time in the media studied demonstrated that the cells had greater difficulty in forming new generations in MMcM medium containing no boric acid. The present data confirm the literature view that PYG medium is the most complete in terms of nutritive substances for the growth and development of P. brasiliensis.

Animals↗
PubMed2001

Phenotypes and randomly amplified polymorphic DNA profiles of Candida albicans isolates from root canal infections in a Finnish population.

A total of thirty-seven Candida albicans isolates from root canal infections in a Finnish population were subtyped using phenotypic and genotypic methods. A previously described biotyping method based on the presence of five different enzymes, assimilation of eleven different carbohydrates and boric acid sensitivity of the yeasts was used to determine the phenotype. Commercially available API ZYM and API 20 C test kits were used to determine the presence of enzymes and assimilation of carbohydrates. The sensitivity of the isolates to boric acid was tested by their ability to grow on yeast-nitrogen-agar with incorporated boric acid (1.8 mg. ml(-1)). Combination of the tests revealed a total of 14 different phenotypes. The majority of the isolates, 26 strains, were classifiable into three major phenotypes: 16 isolates (43.2%) belonged to phenotype A1R, six (16.2%) to A1S and four (10.8%) to B1S. The remaining 11 phenotypes represented only a single isolate each. The randomly amplified polymorphic DNA profiles were used to determine the genotypes. For this purpose two different primers, RSD6 and RSD12 were used to develop a combination randomly amplified polymorphic DNA profile for each isolate. Altogether 31 genotypes were noted among the 37 isolates, of which only three pairs of isolates presented with congruent phenotypic and genotypic profiles. The heterogeneity of both the phenotypic and randomly amplified polymorphic DNA profiles of C. albicans isolates from root canal infections is akin to previous reports from other oral and non-oral sources in different geographic locales.

Bacterial Typing Techniques↗
PubMed1983

Assay of UDP, GDP, CDP, and ADP reductase activities by column chromatography on polyethyleneimine cellulose.

Deoxyribonucleosides were separated from ribonucleosides by chromatography on polyethyleneimine cellulose columns (Pasteur pipettes. The deoxyribonucleosides were quantitatively eluted with 25 mM boric acid in less than 10 ml while the ribonucleosides were retained. The ribonucleosides were eluted with 1 M NaCl. This method was utilized to assay for GDP, UDP, ADP, and CDP reductase activities after hydrolysis of the substrate and product nucleotides to the corresponding nucleosides. All four reductase activities were assayed using identical conditions of column size, eluting solution (25 mM boric acid), and elution volume. The use of polyethyleneimine cellulose columns with boric acid can be adapted to other enzyme assays such as purine nucleoside phosphorylase and for the isolation of deoxyribonucleotides from cellular extracts.

Cellulose↗
PubMed1995

Seven-day viable analysis of some ophthalmic preparations with different concentrations of benzalkonium chloride.

The efficacy of zinc sulphate and boric acid ophthalmic preparations, containing benzalkonium chloride as preservative have been investigated against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria. The viability of bacteria was checked after 7 days though they were completely suppressed after 24 hours of inoculation. Zinc sulphate increased the antimicrobial activity of benzalkonium chloride, whereas the boric acid or its combination with zinc sulphate reduced the same. The Pseudomonas aeruginosa was found to be viable against zinc sulphate, boric acid or its combination at a concentration of 0.01% to 0.005% of the preservative. Escherichia coil and Staphylococcus aureus also exhibited resistance but to a lesser extent than Pseudomonas aeruginosa. This viability may be dangerous in case of multidose ophthalmic preparations.

Bacteria↗
PubMed2003

Electrochemical study on the keto-enol tautomerization of p-hydroxyphenylpyruvic acid in aqueous solution.

The keto-enol tautomerization of p-hydroxyphenylpyruvic acid (pHPP) in aqueous solutions and the complexation reaction between enolic pHPP and boric acid have been studied by electrochemical techniques including linear sweep voltammetry (LSV), pulse voltammetry, and cyclic voltammetry (CV), combining with UV spectrometry. Electrochemical techniques reveal that in aqueous solution, there are two tautomers of pHPP: enolic form and ketonic form; the former exists mainly in freshly prepared pHPP solution, and the latter exists mainly in equilibrium solution. Both enolic and ketonic pHPP are electroactive. The electrochemical oxidation of enolic pHPP gives rise to two anodic waves, I(a) and II(a), while the electrochemical oxidation of ketonic pHPP only results in the observation of the second wave II(a). The oxidation process I(a) is revealed to be associated with the quasi-reversible, two-electron two-proton oxidation of "C=C"group at the side chain of enolic pHPP, and the oxidation process II(a) is proposed to result from the irreversible oxidation of phenolic hydroxyl group. It is observed that in aqueous solution, enolic pHPP can quickly complex with boric acid to yield enol-borate complex that can also oxidize at a glassy carbon electrode to yield an anodic wave.

Boric Acids↗
PubMed2002

Selective removal of cobalt species using nanofiltration membranes.

Selective removal of cobalt species from simulated nuclear liquid waste was investigated with different nanofiltration (NF) membranes at various solution pH levels, initial cobalt concentrations, and background ion concentrations. This study provides insight into the understanding of the relationships between rejections of a target compound (cobalt) and chemical equilibria of various species in the feed solution during NF. Particularly, the ratio of electrostatic rejection to steric rejection for different membranes used was quantitatively evaluated to find outthe relative significance in NF. Substantial cobalt rejection by NF was achieved along with partial separation of monovalent ionic species, although it depended on the level of liquid pH and the presence of background species. Greater cobalt rejection at increased pH was attributed to the precipitation of CoCO3(s) associated with natural carbonates originating from atmospheric CO2 gas rather than that of Co(OH)2(s). A loose NF membrane (e.g., NTR7410) gave as high a rejection as other tighter ones due to the stronger influence of electrostatic rejection, particularly at low pH where no cobalt precipitation was occurring. The decrease of cobalt rejection with the addition of boric acid was found to occur due to the formation of complexes between cobalt and boric acid, which was verified by the analyses of solution turbidity and near-infrared spectroscopy.

Boric Acids↗