Effect of a home bleaching agent on the fracture toughness of resin composites, using short rod design

Statement of Problem: Resin composites are brittle materials and their major shortcomings are manifested in their sensitivity to flaws and defects. Although various mechanical properties of resin composites have been described, few studies are available on assessing the effect of bleaching agents on resin composites using the short rod design

Purpose: To place various resin composites into distilled water at 37°C for 21 days and determine the effect of immersion time in distilled water, with and without exposure to 10% carbamide peroxide by employing short rod design fracture toughness test

Materials and Method: Specimens were prepared from three resin composites; Rok [SDI], Esthet [Dentsply], and Estelite [Tokuyama]. For each material, a total of 24 disc-shaped specimens were prepared using a custom-made mould. Specimens were randomly divided into 3 groups of 8 and conditioned in 37°C distilled water for either 24 hours, or 21 days. 21 day specimens were tested both with and without applying bleaching agent; Polanight [SDI]. Study group specimens were bleached for 21 days, 2 hours a day. The specimens were loaded using a universal testing machine with a crosshead speed of 0.5 mm per minute. The maximum load at specimen failure was recorded and the K[Ic] [MPa. M [0.5]] was calculated

Results: Statistical analysis using two-way ANOVA showed a significant relationship between material and time [p< 0.05].Tukey's test showed that after 24 h of immersion in distilled water, Rok revealed the highest K[Ic] followed by Esthet and Estelite. The bleaching agent significantly improved the fracture toughness values of Esthet while it decreased that of Estelite

Conclusion: The fracture toughness of the resin composites was affected by the bleaching agent and distilled water. In comparison with Rok and Estelite, fracture toughness of Esthet was increased due to aging and application of bleaching agent

Experimental investigation of adsorption of copper from aqueous solution using vermiculite and clinoptilolite

Considering the point that the existence of heavy metals in the wastewater are so dangerous for the environment and it would have many bad consequences for all the creatures including human beings, we must try out the ways that make us capable of adsorbing these heavy metals. In order to accomplish this goal we should use a method called adsorbing. In this study the adsorption of copper ions in hydrated copper nitrate [Cu [NO[3]][2], 3H[2]O] aqueous solution on natural zeolite [Clinoptilolite] and vermiculite was studied in batch reactors. The effect of temperature [25, 50, 75 °C], solution pH [1.00-5.5] and concentration effect on the traditionally defined adsorption isotherm in the adsorbate range 100-325 mg/L for clinoptilolite and 100- 650 mg/L for vermiculite on the removal of copper was studied. The results showed that an increase in pH increases the adsorptivity of vermiculite. Pseudo second order model best described the reaction rate. Batch adsorption experiments conducted at room temperature [25 +/- 1 °C] showed that the adsorption pattern followed the Langmuir and Freundlich isotherm models. Optimum conditions for adsorption were determined at pH 5.5, and vermiculite and clinoptilolite at a dose of 3g. The concentration of metal ions was measured by Atomic Absorption Spectrometer [AAS]. The results indicated that vermiculite and clinoptilolite are appropriate for adsorbing copper ions

Legal criteria and executive standards of solid waste disposal subjected to solid waste management act

This research work attempts to compare the legal and technical criteria of locating household and municipal landfills and discuss them along with legal and technical principles. For this purpose, it was attempted to discuss and compare the related most important national and international standards. Due to say, employing the legal standards of locating household and municipal landfills in corporation with managerial decision making is considered as the most significant issues. Thus, selection of evaluation legal methods of and weighting the criteria of locating the landfills were technically investigated. The main landfill location of Tehran [Kahrizak] was investigated in order to analyze the analytical hierarchical process of its impacts resulted from environmental problems along with the legal aspects of the main landfill site's by the means of Delphi, AHP and Expert Choice techniques, in conflict with the rules adopted from waste act, enacted executive guidelines and content of the published references on Guidelines of Department of the Environment. Ultimately, regarding the questionnaires, recommendations of the learnt and through the items resulted from investigation and analysis of hierarchical process; the following 4 conclusions were achieved: 1] Education and discipline of people as well as the authorities who enforce the rules; 2] Investigation and amendment of Waste Management Act clauses; 3] Receiving the costs of waste management from waste producers and 4] Setting up waste exchange market to utilize the wastes economically. Considering the results [investigation and amendment of Waste Management Act clauses] was selected and recommended as the best option. As a result of further technical investigations on the Waste Management Act, the necessity of employing the criteria of impact evaluation in amending the clauses of Waste Management Act was also recommended

[Effect of zataria multifloraboiss essential oil on the growth of bacillus cereus ATCC 11778 in a commercial barley soup]

The growing interest in substitution of chemical food preservatives by naturalones has fostered researchs on plantessentiak oils and extracts. In this study effect of different concentrations of Zataria multiflora Boiss. Essential oil [0, 0.005, 0.015 and 0.03%] on Bacillus cereus ATCC 11778, [10[3]cfu /ml], was evaluated using sterilized samples [16 bottles containing 80 ml barley soup] and 4 different incubating temperatures [8, 10, 15 and 25°C] during 21 days. Data analysis was done using two way ANOVA. It was found that effect of different concentrations of essential oil on growth rate of Bacillus cereus ATCC 11778 was statistically significant [p<0.01]. The results suggested that Zataria multiflora Boiss. essential oil can be considered as a natural preservative in some foods

Thermal comfort evaluation in Tehran metro using relative warmth index

Underground railway systems, can generate heat from their operations to raise the temperatures of carriages and the station substantially. This may lead to passenger discomfort and complain especially in warm weather conditions that prevail in Tehran if underground environment is not cooled. Transportation air conditioning Committee of American Society of Heating, Refrigerating and air-conditioning Engineers proposed the Relative Warmth Index for thermal comfort design and investigation in subway environment. In this research, thermal comfort at Tehran metro stations and carriages of lines 1 and 2 has been studied using this index. The measurements were taken during two periods of September 2006 and July 2007 at different zones of stations. For this purpose, temperature, relative humidity and air velocity were measured at different times. The status of the air-conditioning systems together with passenger traffic was also recorded. A total number of 231 measurements including 114 and 117 measurements were carried out in September 2006 and in July 2007 respectively. The measurements in September 2006 did not exceed the thermal limit. However, it did exceed in July 2007. In comparison, with thermal comfort level of metros all over the world, Tehran Metro stands in an acceptable condition, while the maximum capacity of air-conditioning systems was not used, if so the thermal comfort condition would be better

Effect of gamma irradiation and frozen storage on microbial, chemical and sensory quality of fish fillet

In this study the effects of gamma irradiation and frozen storage on sensory, chemical and microbial quality of fish fillets was investigated. Hypophtalmyctis molitrix were equally divided to 12 fillets, then these 12 fillets were equally arranged in 4 groups [1-4]. One group considered as control with no treatment and the other 3 groups was treated by 0.75, 3 and 5 KGy of gamma irradiation, respectively. All of the groups were kept in -18?c for 3 month. All of the samples were examined for microbial, chemical and sensory examinations at day zero and 3 months later. The data were analysed by ANOVA [Kruskal-Wallis] using SPSS 10. The results showed treatment with 0.75 KGy of gamma irradiation plus frozen storage in extension of shelf life of fish fillets without any unacceptable effects on sensory and chemical characteristics of them

Land assessment for flood spreading site selection using geospatial information system

Irregular patterns of precipitations from temporal as well as spatial perspectives not only cause destructions but also waste surface water resources. Hence, controlling surface water and leading the flood to underground stores improve the efficiency of water usage. Selecting appropriate sites for optimal use of water floods is one of the most important factors in recharging underground water tables in dry lands where the agricultural and rangelands are vulnerable. Traditional methods of site selections are, however, time consuming and error prone. This paper attempts to; analyze existing schemes of site selection; introduces an appropriate method of locating flood-spreading sites using Geospatial Information System; implements the strategy in a case study; and scientifically assesses its results. The study area of this research is Samal sub-basin covering 31571.7 ha of Ahrom basin in Boushehr province. In the present research, factors pertain to earth sciences [quaternary units, slope and landuse] and hydrology [runoff infiltration rate and aquifers' depth] are considered. Information layers are weighted, classified and integrated through several models such as boolean logics, index overlay and fuzzy logics. The results are then checked against the existing sites to estimate their accuracy. The results of this research demonstrated that fuzzy logic operators including gamma=0.1, gamma=0.2 and products of fuzzy logics yield the best when compared to control fields and therefore, the models are introduced as the most suitable site selection strategies for flood spreading

[Measurement of anterior-posterior diameter of IVC by ultrasonography: a non invasive method for estimation of central venous pressure]

The assessment of intravascular volume in severely traumatized patients or patients admitted in ICU is very essential. At present the accurate method for estimating the intravascular volume requirement is by measuring the CVP which is an invasive method. The measurement of IVC diameter by ultrasound has been suggested as an easily available and simple method for measuring the intravascular volume status. The purpose of this study was to compare the results of IVC diameter measurement by ultrasonography and CVP measurement for calculating the intravascular volume in ICU admitted patients. This was a descriptive and prospective stud]' including 50 patients admitted in ICU with a central Venous catheter placed for any reason whatsoever and no signs of increased right atrial pressure. CVP was measured in supine position by CVP manometer. The anterior- posterior IVC diameter was assessed by ultrasonography during inspiration and expiration. Data analysis was performed by SPSS and evaluated statistically with Pearsons regression and linear correlation test. The mean CVP at inspiration and during expiration was 11.35 +/- 5.53, 12.20 +/- 5.65 cm H2O, respectively. The mean of inspiratory and expiratory IVC diameter was 7.71 +/- 3.5, 11.37 +/- 3.28 mm, respectively. There was significant correlation between CVP and IVC diameter both during inspiration [r= 0.64, p-value= 0.001] and expiration [r=0.495, p-value=0.001] The result of this study suggests that IVC diameter measurement by ultrasound can be used as a reliable and non- invasive method for estimating the intravascular volume

[Effect of serum zinc levels on humoral immune response to hepatitis b vaccination in patients on dialysis]

Zinc deficiency causes abnormalities in immune response. In chronic hemodialysis [I-ID] and continuous ambulatory peritoneal dialysis [CAPD] patients, impaired immune responses to vaccination have been reported. Therefore, we performed a study to determine the correlation between serum zinc levels and immune response to hepatitis B vaccination in patients on dialysis. A cross-sectional study including 95 CRF patients on dialysis [70 HD and 25 CAPD], [63 male and 32 female] with three dose regimens of vaccination against HBV was performed. Four months after vaccination, there were 34 [36%] patients with sufficient HBs Antibody response [HBs Ab >/= 10 MU/mL] and 61[64%] patients with insufficient HBs antibody response[HBs Ab< 10mU/mL]. The mean serum zinc level was 23.35 +/- 3.87 micmol/L [13.20-33 micmol/L]. The mean serum zinc concentration was significantly higher in patients with sufficient HBs antibody level than patients with insufficient HBs antibody levels [24.94 +/- 4.17 versus 22.15 +/- 3.46, P= 0.005]. In logistic regression analysis, independent variables that correlated with sufficient HBs Ab level >/= 10 MU/mL included higher mean serum zinc level [OR=1.44 [1.02-2.02], P=0.006] and female gender [OR=1.8 [1.01-4.01], P=0.048]. Factors found to be insignificant included type of dialysis, age, diabetes mellitus as a cause of ESRD, serum creatinine and albumin levels. We conclude that failure to respond to HBV vaccination is significantly related to a low levels of serum zinc. However, clinical trial studies should be performed in order to confirm this finding

[Determining the diagnostic value of alkaline phosphatase in comparison with parathyroid hormone [PTH] of renal osteodystrophy for treatment with calcitriol in hemodialysis patients]

Serum parathyroid hormone [PTH] is one of the most important tests for treatment of hemodialysis patients with calcitriol. This drug should be started when the PTH >/= 200 pg/ml. However, the appropriate level of serum alkaline phosphates [ALP] for starting calcitriol is unclear. The aim of this study was to determine serum ALP as cutoff point for treatment of secondary hyperparathyroidism with calcitriol. This study was a cross sectional. The serum level of PTH and ALP were measured in 75 chronic hemodialysis patients. The correlation between PTH and ALP in diagnosis for treatment with calcitriol was significant [Kappa test P-Value=0.000]. In determination of diagnostic value of ALP [at level 300IU/L] for treatment with calcitriol, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 88.9%, 93.9%, 66.7%, 98.4% and 93.3%, respectively. The cutoff point of ALP for treatment with calcitriol was 300IU/L [normal 100-290IU/L]. These findings suggest that serum ALP is a good test for treatment of secondary hyperparathyroidism. The results also indicate that calcitriol administration should not be started with ALP<300 IU/L

case report of adrenocortical carcinoma of adrenal gland

Primary neoplasms of the adrenal cortex are rare in children and differ from their counterparts in term of clinical characteristics. The studies revealed that prognosis of these tumors are not as bad as previous expectation. Differentiation between adenoma and carcinoma adrenal tumors in the absence of metastasis to other organs is impossible. The survival of the patients depends on the age, being longer in children under 5 years old The utilization of imaging surveys particularly CT scan and MRI facilitated the investigation of the children with early puberty and Cushing 's syndrome. However a combination of clinical finding and imaging methods is required. the patient was a 4.5 months old infant with Cushing's syndrome who presented with generalized edema. She was suspected to have adrenocortical neoplasm and subjected to the operation of left side adrenalectomy. The diagnosis was confirmed by pathological examination of the patient biopsy

Echocardiographic evaluation of R and L venticular diastolic function in thalassemia major

Beta thalassemia major [BTM] is a hereditary severe and fatal hemolytic anemia associated with organ failure and iron overload. Cardiac complications are the major cause of morbidity and death in BTM. The purpose of this study was to assess early diagnosis of cardiac involvement by echocardiography. This is a case-control study on 80 patients with BTM and 80 age and sex matched healthy children as control group from September 2002 to December 2003 in AliAsghar hospital of Zahedan, Complete echocardiographic study was done and diastolic function indices compared with control group statistically. From 80 patients 42 patients were males. The mean age was 14.3 +/- 2.3 years. In comparison with control group: The mean of E/A Ratio of left ventricle [LV] and right ventricle [RV] was 1.81 +/- 0.35 and 1.33 +/- 0.33 respectively that increased significantly [p< 0.05]. The mean of deceleration time [DT] of mitral and tricuspid valves was 144.67 +/- 23, 134/87 +/- 25 msec respectively that decreased only significantly in RV. [P<0.05] Isovolumic relaxation time [IVRT] was the most frequent abnormal diastolic index increased significantly in both ventricles [p< 0.05]. The mean of pre ejection period / Ejection time [PEP/ET] ratio of LV and RV was 0.33 +/- 0.06 and 0.31 +/- 0.06 respectively. Although increased significantly in both ventricles [p<0.05] but abnormal PEP/ ET was more frequent in RV. Only 9 patients had LV systolic dysfunction. In patients with BTM, diastolic dysfunction especially in RV was more frequent and begun earlier than LV systolic dysfunction. Increased IVRT, PEP/ET ratio and decreased DT had more sensitivity in early diagnosis especially in RV. Therefore assessment of diastolic function in addition to LV systolic function is mandatory and leads to early diagnosis of cardiac dysfunction