Dimensional stability of two polyvinyl siloxane impression materials in different time intervals

Statement of Problem: Dental prosthesis is usually made indirectly; therefore dimensional stability of the impression material is very important. Every few years, new impression materials with different manufacturers' claims regarding their better properties are introduced to the dental markets which require more research to evaluate their true dimensional changes

Objective: The aim of this study was to evaluate dimensional stability of additional silicone impressionmaterial [Panasil[R] and Affinis] in different time intervals

Materials and Methods: In this experimental study, using two additional silicones [Panasil[R] and Affinis[R]], we made sixty impressions of standard die in similar conditions of 23 °C and 59% relative humidity by a special tray. The die included three horizontal and two vertical lines that were parallel. The vertical line crossed the horizontal ones at a point that served as reference for measurement. All impressions were poured with high strength dental stone. The dimensions were measured by stereo-microscope by two examiners in three interval storage times [1, 24 and 168 hours].The data were statistically analyzed using t-test and ANOVA

Results: All of the stone casts were larger than the standard die. Dimensional changes of Panasil and Affinis were 0.07%, 0.24%, 0.27% and 0.02%, 0.07%, 0.16% after 1, 24 and 168 hours, respectively. Dimensional change for two impression materials wasn't significant in the interval time, expect for Panasilafter one week [p = 0.004]

Conclusion: According to the limitations of this study, Affinis impressions were dimensionally more stable than Panasil ones, but it was not significant. Dimensional change of Panasil impression showed a statistically significant difference after one week. Dimensional changes of both impression materials were based on ADA standard limitation in all time intervals [< 0.5%]; therefore, dimensional stability of this impression was accepted at least until one week

Predicting the mortality risk of ICU patients in Booali hospital using APACHE III system

The ability to estimate the mortality risk, especially in costing setting like ICU, is of great importance in order to evaluate new treatments, resource consumption control and improve quality control. Acute physiology and chronic health evaluation system [APACHE] is developed to predict critical care outcomes. In this system, according to the setting, a score is considered for each patients. Then using an equation, predicted mortality risk for each patients could be estimated. In a prospective study, we observed 269 ICU patients over a 10-month period. We calculated APACHE III scores for each patient and predicted mortality risk. Accuracy of the results were checked with regression analysis. Totally, 51.7% of patients were female while the mean age was 61.2 years. APACHE III average score was 60.6. Predicted mortality risk was 25.6% while actual death rate was 27.1%, therefore, SMR [actual death rate to predicted mortality risk ratio] was 1.05. Results revealed an association between actual death rate and APACHE III score and patient's age [P =0.0001], however, sex and death rate were not statistically correlated. The obtained SMR represents direct linear association between predicted and actual death rate [P=0.0001]

Adsorption of chromium from wasterwater by platanus orientalis leaves

The Cr [VI] adsorption characteristics of platanus orientalis leaves and their ash were examined as a function of contact time, initial pH and metal ion concentration. Batch adsorption experiments were performed. The effects of Ca[2+], Mg[2+], Na[+] and K[+] on adsorption were studied. The effect of this adsorbent on COD in wastewater showed that 2g/L of adsorbent caused increase of 110 mg/L and 76mg/L COD in deionized water in 120 minutes for platanus orientalis leaves and their ash, respectively. The maximum removal took place in the pH range of 6-7, contact time of 60 minutes and initial concentration of 2mg/L. Studies showed that the Freundlich adsorption model better fitted with the results than Langmuir with R[2]>0.85. The study showed platanus orientalis leaves ash was more favorable than living ones as well as in removing chromium fro the aqueous solution

Removal of chromium [VI] from aqueous solution by Ulmus leaves

The Cr [VI] adsorption characteristics of Ulmus leaves [UL] and their ash were examined as a function of contact time, initial pH, and initial metal ion concentration. Batch adsorption experiments were performed. The effects of Ca[2+], Mg[2+], Na[+]and K[+] on adsorption were studied. Maximum removal was achieved in the pH=7, contact time of 60 minutes and with initial Cr [VI] concentration of 2 mg/L. Because at pH>/=6.5, precipitation of chromium may take place, optimum pH was selected at 6. Maximum adsorption rate values were found at the first 60 min at pH=6. The effect of the adsorbent on COD removal from aqueous solution showed that 2g/L of adsorbent caused 130 and 75 mg/L increase in COD of deionized water in 60 min for UL and its ash, respectively. The chromium adsorption data obtained under the optimum condition were described by the Langmuir and Freundlich isotherms. Studies showed that the Langmuir adsorption model better fitted than Freundlich, with R[2]>0.99. Also UL ash was more efficient than living leaves in removing chromium from aqueous solution