Acid Resistance Test Research Articles

Calculating colon transit time withradionuclide-filled capsules in constipated patients: a new method for colon transit study

Colon motility disorders require reliable methods for calculating segmental colonic transit time. This study evaluated bowel transit time by means of a safe, easy, cheap, non-digestive, and non-disintegrating radionuclide-filled capsule that provided accurate and clear images. Radionuclide-filled mini-containers (MCs) were prepared from infusion sets by an apparatus used for sealing blood bags or plasmapheresis sets. In vitro stability studies were performed by immersing 5% methylene blue dye-filled MCs in buffers of variable pH and enzymes simulating the conditions in the stomach and the small bowel. Colon transit scintigraphy was performed with MCs filled with iodine 131 (n = 5) and thallium 201 (n = 8) that were placed in a commercially available capsule. By in vitro acid, base, and intestinal enzyme resistance tests, no methylene blue leakage was determined visually and by spectrophotometric analysis. Accurate and clear images were obtained for colon transit study in constipated patients. After excretion of MCs in the feces, abdominal, myocardial, thyroid, and urinary bladder region counts were found to show the same activity as the background. Radionuclide leakage from MCs was not determined in vivo by gamma camera. This is a suitable, safe, easy, and cheap method to provide accurate and clear images for colon transit study in constipated patients.

Plasma-sprayed glass-ceramic coatings on ceramic tiles: microstructure, chemical resistance and mechanical properties

This article reports the characterisation and optimisation of glass-ceramic coatings plasma-sprayed on traditional ceramic substrates, dealing with microstructures, chemical resistance, and superficial mechanical properties. A CaO–ZrO 2–SiO 2 (CZS) frit, capable of complete crystallization after proper thermal treatment, has been employed: due to its refractory nature, its firing temperature in a traditional process would be unbearable for common substrates. The frit was plasma-sprayed onto ceramic tiles and a post-process thermal treatment has been developed in order to sinter and crystallize the coating, employing much lower temperatures than a traditional ceramic firing cycle. The microstructure of both as-sprayed and treated coatings has been evaluated with SEM and EDS, acid resistance tests have been performed. Vickers microhardness, superficial fracture toughness, deep abrasion resistance, elastic modulus and coating adhesion have been evaluated. Unglazed stoneware and an industrial glaze were also tested for comparison and an experiment was made to produce a CZS-based glaze to ascertain the inadequacy of traditional firing. As-sprayed coatings have a typical plasma-spraying defective microstructure, but a thermal treatment with 30′ isotherm at 850 °C plus 15′ isotherm at 1050 °C allows good densification, excellent adhesion and complete crystallization, with formation of wollastonite-2M and many small Ca 2ZrSi 4O 12 grains. Thus, the coating outperforms stoneware by 50% in abrasion resistance, possessing higher fracture toughness, thanks to the continuous crack deflections due to the numerous crystals. Fracture toughness appears to be the property most correlated to abrasion resistance, because brittle fracture is the dominant abrasion mechanism. Hardness and elastic modulus reflect quite well the coating inner cohesion. Treated coatings porosity is lower than industrial glazes and stoneware.

Characteristics of manganese-coated sand using SEM and EDAX analysis

“Manganese-coated sand” is a type of silica medium coated with manganese oxides, formed from the sorption of manganese oxides during long-term filtration via the process of rapid sand filtration, followed by aeration in a water treatment plant. Locally available manganese-coated sand, both for packing and as a byproduct of filtration processes for water treatment plants in Taiwan, was found to be a low-cost and promising adsorbent for removal of Mn 2+ from raw water. This study was conducted to build the basic data for coating hydrated manganese oxide on the sand surface to utilize the adsorbent properties of the coating and the filtration properties of the sand. In this study, gas adsorption porosimetry and scanning electron microscopy analyses were used to investigate the surface properties of the coated layer. An energy dispersive X-ray (EDAX) technique of analysis was used to characterize metal adsorption sites on a manganese-coated sand surface. Results indicated that manganese-coated sand had more micropores and higher specific surface area, owing to attachment of manganese sand. Manganese ions penetrated into the micropores and mesopores of manganese oxide on a sandy surface; regeneration of manganese-coated sand could be achieved by soaking with pH<2.0 acid solution. Results of EDAX analysis showed that the interfacial layer constructed the interface of manganese-coated sand. Acid and alkali resistance tests interpret a wide application range of pH for manganese-coated sand, and general temperature conditions do not affect the performance of this sand. Manganese-coated sand is potentially suitable for application as a packed bed for treatment of heavy metals from water. The results of this study can also benefit plant operational capacity data for engineering design.

Relationship between the fluoride concentration of the fluoride-releasing elastomers and the acquired acid resistance of human enamel in vitro.

The objective of the study was to evaluate the relationship between the fluoride concentration of the fluoride-releasing elastomers and the acquired acid resistance of human enamel. Four kinds of fluoride concentration of the experimental fluoride-releasing elastomers were 1.25, 2.5, 3.75 and 5.0 wt%. An enamel block was cut into two smaller enamel blocks, one of which was set with an elastomer, the other as a control not set with elastomer. A plastic block that had the same shape as the small enamel block was also set with elastomer. Fluoride release and acid resistance tests were carried out. The mineral loss of the demineralized enamel was measured by microradiography. The results showed that the fluoride-releasing ability significantly increased with the increase of fluoride concentration in the elastomer (p < 0.05). The acid resistance of the enamel appeared to be enhanced greatly, however, its change was not proportional to the fluoride concentration in the elastomers.

An Acid Resistance Test after Remineralization of Enamel in vitro : The Influence of Different Ratios of Demineralization and Remineralization Periods

An Acid Resistance Test after Remineralization of Enamel in vitro : The Influence of Different Ratios of Demineralization and Remineralization Periods

An Acid Resistance Test after Remineralization of Enamel in vitro : The Influence of an Equal Ratio of Demineralization and Remineralization Periods

An Acid Resistance Test after Remineralization of Enamel in vitro : The Influence of an Equal Ratio of Demineralization and Remineralization Periods

Biotypes of oral Candida albicans isolates in a Tanzanian child population

Although biotypes of Candida albicans from adult populations, especially in the West, have been described, there are no data either from a child population, or from the African continent. Hence a total of 200 oral C. albicans isolates from Tanzanian children aged 6-24 months were biotyped using two commercially available API micromethod kit systems and a boric acid resistance test. The predominant biotypes, which comprised two thirds of the organisms isolated, were J1S (19.5%), A1S (16.0%), J1R (14.5%), A1R (9.5%) and P1R (7.5%). In total, 16 new biotypes comprising 44 (22%) isolates which have not hitherto been described were found in this Tanzanian population and, of these, the P1R biotype predominated with 15 (7.5%) isolates. There was no significant association between predominant biotypes (with clusters > or = 15 isolates) and age, gender, breast feeding and malnutrition. These data indicate that the biotype profile of C. albicans isolates may differ in paediatric and adult populations, and/or global distribution of various subtypes of this common opportunistic pathogen.

Graphite particles in the diamond-like a-C films prepared with the pulsed arc-discharge method

Abstract Microparticle collection on the coating surface has been studied during the preparation of diamond-like amorphous carbon coatings with the pulsed arc-discharge method. The curved solenoid method was used for the particle filtering. The quality of the coatings was studied using profilometer, ESCA and SEM techniques and wear, friction and acid resistance tests. The coatings without and with filtering contained graphite particles (40% and less than 1% respectively) and the sp 2 sp 3 -bonding ratios were 51% and 78% respectively. The acid resistance of the nonfiltered films was poor. On the contrary, in pin-on-disc experiments with both types of coating against polyethylene, steel and Al2O3 pins, no clear differences in the friction and wear measurements were observed.

Oral Candida albicans biotypes in chinese patients with and without oral candidosis

A total of 53 oral Candida albicans isolates from Chinese patients with clinically diagnosed oral candidosis (27 patients) or without overt signs and mycological manifestations of infection (26) were biotyped using two commercially available API micromethod kits and a boric acid-resistance test. There were no significant differences in the biotypes in health and disease, although the biotype A1R was present only in diseased individuals. The biotype A1S accounted for 21% of the total isolates, as in a number of other previous studies from the West. However, 14 of the 27 biotypes characterized were new biotypes that have not been described before. These preliminary data indicate that biotypic profile of C. albicans may bear no relation to the virulence of the isolates, and that diverse subtypes of the fungus are globally prevalent.

フッ化物歯面塗布法に関する研究 塗布要領の再検討 第ＩＩ報

This study was designed to revalue topical fluoride treatment time and the time to refrain from rinsing, eating or drinking following a professional application.In order to investigate the application time, human enamel powder was given a topical fluoride application treatment with APF solution (pH 3.6, F-: 9, 000ppm) for 0, 1, 2, 3, 4, 6 and 8min. We compared fluoride uptake, Ca/P molar ratio and acid resistance test between all fluoride groups and the control.The fluoride concentrations in powder were similar in all groups of 3min or more, and were not statistically different in each group. After washing with 1 M KOH solution, fluoride concentration was decreased in all groups. Although in the 4min group some fluoride remained, all other fluoride groups proved not to be statistically different from each other in treatment time.In all groups, after treatment with fluoride, Ca/P molar ratio was increased significantly, suggesting the production of CaF2 in the enamel powder.The acid resistance test proved that release of calcium was inhibited in all fluoride groups both after treatment and after washing with 1 M KOH solution, though they showed a little difference depending on the demineralization time. All fluoride groups had the same or more acid resistance than the 4min group.To investigate the time for refraining from rinsing, eating or drinking, we measured the fluoride dissolved in water when the enamel powder treated for 4min with APF was immersed with or without stirring for 24h. When stirred, dissolved fluoride suddenly increased in all groups. We could not prove statistical difference in dissolved fluoride in the groups which were stirred directly after treatment, after 10, 20 and 30min.These findings suggested that the application time can be shortened to 4min and the time for refraining from rinsing, eating or drinking can be shortened to 30min.

フッ化物歯面塗布法に関する研究 塗布要領の再検討 第Ｉ報

This study was designed to revalue topical fluoride treatment time and the time to refrain from rinsing, eating or drinking following a professional application.In order to investigate the application time, human enamel powder was given a topical fluoride application treatment with APF solution (pH 3.6, F-: 9, 000ppm) for 0, 1, 2, 3, 4, 6 and 8min. We compared fluoride uptake, Ca/P molar ratio and acid resistance test between all fluoride groups and the control.The fluoride concentrations in powder were similar in all groups of 3min or more, and were not statistically different in each group. After washing with 1 M KOH solution, fluoride concentration was decreased in all groups. Although in the 4min group some fluoride remained, all other fluoride groups proved not to be statistically different from each other in treatment time.In all groups, after treatment with fluoride, Ca/P molar ratio was increased significantly, suggesting the production of CaF2 in the enamel powder.The acid resistance test proved that release of calcium was inhibited in all fluoride groups both after treatment and after washing with 1 M KOH solution, though they showed a little difference depending on the demineralization time. All fluoride groups had the same or more acid resistance than the 4min group.To investigate the time for refraining from rinsing, eating or drinking, we measured the fluoride dissolved in water when the enamel powder treated for 4min with APF was immersed with or without stirring for 24h. When stirred, dissolved fluoride suddenly increased in all groups. We could not prove statistical difference in dissolved fluoride in the groups which were stirred directly after treatment, after 10, 20 and 30min.These findings suggested that the application time can be shortened to 4min and the time for refraining from rinsing, eating or drinking can be shortened to 30min.

脱灰エナメル質の再石灰化に及ぼすレーザー照射ならびにフッ素の影響

The aim of this study was to evaluate the effect of the laser irradiation and the presence of fluoride in the remineralizing solution on the remineralization of deminalized enamel. The enamel of ninety human premolars was demineralized artificially. This was then irradiated with a Q-switch Nd-YAG laser and remineralized with two remineralizing solutions, one with and the other without fluoride. To evaluate the mineralized enamel, the mineral content of the enamel was calculated and two acid resistance tests (1. mineral content evaluation after HClO4 immersion, 2. dissolved Ca2+ measurement after lactic acid immersion) were performed.The results were as follows:1. In the acid resitance test with HClO4, the presence of fluoride in the remineralizing solution increased the acid resistance of the demineralized enamel.2. In the acid resistance test with lactic acid, 1) laser irradiation increased the acid resistance of the demineralized enamel, 2) the acid resistance effect of laser irradiation was the same as that of the presence of fluoride in the remineralizing solution, and3) the highest acid resistance was found in the combined treatment of laser irradiation and remineralization with fluoride.

Application of Orthogonal Array on the Calculation of the Refractory Index in Multi-Component Glasses

The “optimum firing temperature” (θf) of enamel frit is defined as the temperature at which the viscosity of the molten glass becomes 4000 poises. θfs of multi-component glasses were interpolated, measuring their viscosities by means of the counterbalance method. An orthogonal array of 3n-type was applied as the substituting means of the components among others, and the effects of each component substituting silica was calculated. Moreover, this effect can be used as the additive constant for θf, which also gives a base to derivate the “refractory index”. The new indices proved themselves more reasonable than those of R. R. Danielson's. The analysing method of the results of the acidresistance tests was also discussed, and the scale of the “rationality” of the acidresisting-enamel composition was given by means of the proper classification.