STATEMENT OF PROBLEM: Long-term exposure of dental porcelain to saliva during temporary cementation of a porcelain-fused to metal (PFM) restoration could affect mechanical strength of dental porcelain if the restoration is refired. PURPOSE: This work was performed to verify the effect of water on the mechanical strength in aged dental porcelain. MATERIAL AND METHOD: 63 specimens(Vintage Metalbond opaque and opal powder) were distributed to three experimental groups; non-water immersed control, immersed and pedried, and immersed and non-predired groups. The changes in flexural strength and fracture toughness after specimen refiring related to Fourier Transform Infrared (FT-IR) spectroscopy. RESULTS: 1. The FT-IR reflectances assigned to molecular bonds of H2O were noted as significantly different between the first-fired group and three refired groups and between two water-immersed groups and control group after refiring( p<0.05). They were also significantly different between predried group and non-predried group after refiring( p<0.05). 2. For opal specimens, FT-IR absorbances for hydrogen bond of H2O and silanols were significantly higher in non-predried group than in predreid group( p<0.05). 3. Predried opal group showed the highest mean flexural strength( p<0.05). Non-predried group indicated higher mean flexural strength than control group( p<0.05). 4. The mean fracture toughness for predired group was higher than non-predried group( p<0.05). 5. The difference of leucite crystal size is noted between control group and water-immersed, predried group in scanning electron microscopic study(x10000).
Cementation ; Dental Porcelain* ; Fourier Analysis ; Hydrogen ; Saliva ; Spectrum Analysis ; Water*

Air ; analysis ; Hydrogen Peroxide ; analysis ; Spectrophotometry ; methods ; Workplace

OBJECTIVETo predict the percutaneous drug permeability coefficients with modified regression equation.

METHODSThe semiempirical self-consistent field molecular orbital calculation AM1 method was used to calculate the quantum chemical parameters and the modified theoretical linear solvation energy relationship was used to obtain the regression equation of the permeability coefficients of drugs through human epidermis.

RESULTThe permeability coefficients (P) of 36 nonelectrolytes were well linearly correlated with their theoretical descriptors including molecular volume (V), hydrogen bond acidity (sum alpha(2)(H)), hydrogen bond basicity (sum beta(2)(H)) and polarizability index (pi(1)). The regression equation was logP=-6.790+1.571 V+0.1550 pi(1)-1.295 sum alpha(2)(H)-2.485 sum beta(2)(H)(n=36,r=0.9777).

CONCLUSIONThe modified theoretical linear solvation energy relationship can be used to predict the skin permeability of drugs.

BACKGROUND: Arterial blood gas analysis are highly susceptible to preanalytic error due to improper method of obtaining or handling the blood sample before analysis. The error in measurement of blood gas analysis are loss of CO2 by exposure to atmospheric air, effect of anticoagulant itself, temperature difference between the experimental subject and the measuring electrode and metabolic change which occur between blood sampling and measurement. METHOD: To study the effect of the delay in estimation of blood gas and drawn blood on values of blood gas partial pressure and pH. Blood sample were divided into 2 groups according to the method of storage, group I stored at 24~25degrees C(room temperature) under anaerobic condition. ;group II stored at 0~4degrees C(refrigerator) under anaerobic condition. The samples were analyzed by time interval through 180 minutes in each group. RESULTS: The result were as follows: 1) PaO2 decreased significantly after 10 mins in group I, whereas it decreased significantly after 20 mins in group II. 2) PaO2 increased significantly after 20 mins in group I, whereas it increased significantly after 120 mins in group II. 3) pH decreased significantly after 60 mins in group I, whereas it decreased significantly after 120 mins in group II. 4) No significant changes of bicarbonate and SaO2 were noted in each group CONCLUSION: From above results, it would be advisable to analyze the sample in a short period of time or to store in a refrigerator when the measuring will be delayed. So we highly recommend that blood gas analysis should be performed as soon as possible after sampling, especially within 10 minutes.
Blood Gas Analysis ; Electrodes ; Hydrogen-Ion Concentration ; Partial Pressure

The most important factor in clinical development of respiratory care has been the clinical availabiTity of blood gas and pH measurement and it is important to get the accurate values of those. There can be an error to get the value of PCO2, PO2 and pH by dilutional effect of liquid-Naheparin that is usally used as an anticoagulant. We compared values of 20 arterial blood gases sampled with 1 cc plastic syringe utilizing liquid-Na-heparin with those ones sampled with 1 cc arterial blood gas kits which were pre-filled with dry-Lithium-heparin. The results were as follows; 1) There are no difference in values of PO2 and pH between two groups. 2) The value of PCO2 sampled with 1 cc plastic syringe utilizing liquid-Na-heparin is 1.62 torr less than the value of that with 1 cc arterial blood gas kits which were pre-filled with dry-Lithium-heparin (p<0.05).
Blood Gas Analysis* ; Gases ; Hydrogen-Ion Concentration ; Plastics ; Syringes*

Hydrogen Peroxide ; analysis ; Sensitivity and Specificity ; Spectrophotometry ; methods ; Titanium ; Workplace

OBJECTIVE: To develop a fast, sensitive and cost-effective method based on resonance light scattering (RLS) for characterization of protein solubility to facilitate detection of changes in solubility of mutant proteins. METHODS: We examined the response curve of RLS intensities to the protein concentrations in synchronous scanning mode. The curve intersection points were searched to predict the maximal concentrations of the protein in dispersion state, which defined the solubility of the protein in this given state. Bovine serum albumin (BSA, 0-50 g/L) was used as the model to investigate the influences of pH values (6.5, 7.0, and 7.4) and salt concentrations (0.05, 0.10, 0.15, and 0.20 mol/L) on the determined solubility. The solubility of glutathione S-transferase isoenzymes alpha (GSTA, 0-27.0 g/L) and Mμ (GSTM, 0-20.0 g/L) were estimated for comparison. The RLS-based method was used to determine the solubility of uricase (MGU, 0-0.4 g/L) to provide assistance in improving the solubility of its mutants. RESULTS: We identified two intersection points in the RLS response curves of the tested proteins, among which the lower one represented an approximation of the maximal concentration (or the solubility of the protein) in single molecular dispersion, and the higher one the saturated concentration of the protein in multiple molecular aggregation. In HEPES buffer, the two intersection points of BSA (isoelectric point 4.6) both increased with the increase of pH (6.5-7.4), and their values were ~1.2 g/L and ~33 g/L at pH 7.4, respectively; the latter concentration approached the solubility of commercial BSA in the same buffer at the same pH. The addition of NaCl reduced the values of the two intersection points, and increasing salt ion concentration decreased the values of the lower intersection points. Further characterizations of GSTA and GSTM showed that the low concentration intersection points of the two proteins were ~0.7 g/L and ~0.8 g/L, and their high concentration intersection points were ~10 g/L and ~11 g/L, respectively, both lower than those of BSA, indicating the feasibility of the direct characterization of protein solubility by RLS. The two concentration intersection points of MGU were 0.24 g/L and 0.30 g/L, respectively, and the low concentration intersection point of its selected mutant was increased by 2 times. CONCLUSIONS RLS allows direct characterization of the solubility of macromolecular proteins. This method, which is simple and sensitive and needs only a small amount of proteins, has a unique advantage for rapid comparison of solubility of low-abundance protein mutants.
Hydrogen-Ion Concentration ; Light ; Scattering, Radiation ; Solubility ; Spectrum Analysis

The output and agronomic characters of 3-year-old Panax notoginseng cultured under stereo structure (upper, middle and down layers) were investigated, and the annual change of N, P and K of its planting soil were also studied. Results showed that, compared with field cultured Panax notoginseng, growth vigour and output of stereo-cultivation were significantly lower. But the total production of the 3 layers was 1.6 times of field. The growth vigor and production of P. notoginseng was in the order of upper layer > middle layer > down layer. The content of ginsenoside in rhizome, root tuber and hair root of P. notoginseng was in the order of upper layer > field > middle layer > down layer. Organic matter content and pH of stereo-cultivation soil decreased with the prolonging of planting time, which with the same trend of yield. Organic matter content of stereo-cultivation soil was significantly higher than field, but the pH was significantly lower. Contents of total and available N, P and K in stereo-cultivation soil and field decreased with the prolonging of planting time. The content of N and P were in the order of upper layer > middle layer > yield > down layer, the content of K was in the order of upper layer > middle layer > down layer > yield. Compared with field, the proportion of N and P in the organ of underground (rhizome, root tuber and hair root) of upper layer were increased, while decreased in middle and down layers. Proportion of K in underground decreased significantly of the 3 layers. In conclusion, the agronomic characters and production of stereo-cultivation were significantly lower than that of yield. But the total production of the 3 layers were significantly higher than field of unit area. And the aim of improving land utilization efficiency was achieved. Nutritions in the soil of stereo-cultivation were enough to support the development of P. notoginseng, which was not the cause of weak growth and low production. The absorbing ability of P. notoginseng to N, P and K nutrients was decreased by stereo-cultivation mode. So, improve the growth vigour of P. notoginseng from the perspective of adjusting the stereo-cultivation mode so as to improve the nutrient absorption capacity is the future direction.
Food ; Hydrogen-Ion Concentration ; Nitrogen ; analysis ; Panax notoginseng ; growth & development ; Phosphorus ; analysis ; Potassium ; analysis ; Soil ; chemistry

We report physicochemical characteristics of various kinds of liquid milk commercially available in Pakistan in comparison with those of fresh natural milk from animals. Milk samples were collected from local markets at Peshawar, Pakistan, and analyzed for their physical features, including moisture, total solids, specific gravity, conductivity, viscosity and titratable acidity (lactic acid equivalent), and chemical components and macro-minerals, including total protein, casein, lactose, ash and minerals (Na, K and Mg). These items were compared with the physicochemical characteristics of the fresh natural milk samples from buffalo, cow and goat. The results were also compared with reported nutritional quality of milk from various countries and World Health Organization (WHO) standards. We found that all the physical features and chemical components of commercially available milk in Pakistan markets meet WHO's requirements, except for Na, K, Ca and Mg, which are below the standards.
Animals ; Buffaloes ; Calcium ; analysis ; Cattle ; Goats ; Hydrogen-Ion Concentration ; Metals ; analysis ; Milk ; chemistry ; Potassium ; analysis ; Sodium ; analysis ; Viscosity

We studied the hydrogen evolution (HE) of green alga Chlorella pyrenoidosa grown in normal (nutrients sufficient) media and nitrogen, manganese or sulfur deprived medium. The results showed that photo-hydrogen evolution could occur under all conditions herein before, but the efficiency of HE was maximum under nitrogen deprivation, and the total hydrogen yield was 88.613 microL H2/mg Chla, which was 4.61, 1.92, 3.63 times of control, manganese deprivation, sulfur deprivation groups, respectively. We also measured the growth, the photosynthesis and respiration of the alga. The data demonstrated that manganese deprivation had less influence than nitrogen and sulfur deprivation on the growth, the photosynthesis and respiration of C. pyrenoidosa. Compared with the normal (nutrients sufficient), manganese and sulfur deprivation inhibited the photosynthesis and growth of the alga while bringing small impact on respiration. Nitrogen deprivation, however, greatly restrained the photosynthesis and growth while enhancing the respiration. Those data provide clues for the further study on both the conditions optimization and mechanism of hydrogen evolution.
Chlorella ; growth & development ; metabolism ; Hydrogen ; analysis ; metabolism ; Manganese ; analysis ; metabolism ; Nitrogen ; analysis ; metabolism ; Photosynthesis ; Sulfur ; analysis ; metabolism