effect of gap angle on tensile strength of preceramic base metal solder joints

Statement of the Problem: Soldering is a process commonly used in fabricating dental prosthesis. Since most soldered prosthesis fail at the solder joints; the joint strength is of utmost importance

Purpose: The purpose of this study was to evaluate the effect of gap angle on the tensile strength of base metal solder joints

Materials and Method: A total number of 40 Ni-Cr samples were fabricated according to ADA/ISO 9693 specifications for tensile test. Samples were cut at the midpoint of the bar, and were placed at the considered angles by employing an explicitly designed device. They were divided into 4 groups regarding the gap angle; Group C [control group] with parallel gap on steady distance of 0.2mm, Group 1: 10[degree sign], Group 2: 20[degree sign], and Group3: 30[degree sign] gap angles. When soldered, the specimens were all tested for tensile strength using a universal testing machine at a cross-head speed of 0.5 mm/min with a preload of 10N. Kruskal-Wallis H test was used to compare tensile strength among the groups [p< 0.05]

Results: The mean tensile strength values obtained from the study groups were respectively 307.84, 391.50, 365.18, and 368.86 MPa. The tensile strength was not statistically different among the four groups in general [p

Conclusion: Making the gap angular at the solder joints and the subsequent unsteady increase of the gap distance would not change the tensile strength of the joint

passive noise control approach utilizing air gaps with fibrous materials in the textile industry

Noise pollution is currently a major risk factor in industries in both developed and developing countries.The present study assessed noise pollution in the knitting industry in Iran in 2009 and presented a control method to reduce the rate of noise generation. The overall noise level was estimated using the network environmental noise as-sessment method in Sina Poud textile mill in Hamadan. Then, frequency analysis was per-formed at indicator target stations in the linear network. Finally, a suitable absorbent was rec-ommended for the ceilings, walls, and aerial panels at three phases according to the results found for the sound source and destination environment. The results showed that the highest sound pressure level was 98.5 dB and the lowest was 95.1 dB. The dominant frequency for the industry was 500 Hz. The highest and lowest sound suppression was achieved by intervention at 4000 Hz equivalent to 14.6 dB and 250 Hz in the textile industry. When noise control at the source is not available or insufficient because of the wide distribution of the acoustic field in the workplace, the best option is to increase the absorp-tive surface of the workplace using adsorbents such as polystyrene.

Investigation of the impact of HBM-based training on BSE in women referred to health centers in Zahedan in 2010-2011

Women of all ages are at risk for developing breast cancer. More than 90% of patients can be treated if diagnosed early. However, most women do not perform a regular BSE [Breast Self-Examination], which is an effective and inexpensive way to prevent considerable cancer-related death and morbidity. This study was performed to investigate the impact of Health Belief Model [HBM]- based training on BSE behavior. The study involved a controlled intervention performed with 200 women referred to health centers in Zahedan; 100 women were included in the intervention group and 100 other women in the control group. Before undertaking intervention training, a questionnaire designed according to HBM principles was completed by the subjects. The intervention training was then carried out with the intervention group using a lecture, question and answer sessions, and a film. Two months after the intervention, the questionnaire was readministered. Data were analyzed using SPSS 19 software, an independent t-test, a paired t-test, and a chi-square analysis; P < 0.05 was considered significant. The independent t-test showed that before the intervention, there was no statistically significant difference in mean knowledge scores or HBM parameters among the control and intervention groups [P > 0.05]. However, a significant difference was found after the intervention as the mean knowledge score increased and the HBM parameters differed in the intervention group [P < 0.05]. A paired t-test showed that the mean differences in knowledge scores and HBM parameters before and after the intervention were statistically significant [P < 0.05], but no significant before and after differences were identified among the control group [P > 0.05]. Before the study, the percentage of women who regularly performed a BSE was 7% in the intervention group, but this was increased to 51% after the intervention. It seems that a training program based on HBM principles is effective for inducing BSE behavior. Also, based on the findings of this study, there may be a need to increase the awareness of the perceived severity of breast cancer and the possible benefits of BSE and a self-efficacy approach to health. It is recommended that training programs emphasizing such changes be designed and implemented

Analysis of relation between C677T genotype in MTHFR gene and prostatic cancer in Iranian males

Methylenetetrahydrofolate reductase [MTHFR] enzyme is one of the most important enzymes with a pivotal role in the folate metabolism and DNA synthesis pathways. Single nucleotide polymorphism [SNPs] in the coding gene has been related to many medical diseases as well as diverse malignancies including the prostate cancer which is the leading cause of the cancer deaths in men and one of the major public health problems. The goal of this study is to determine the relationship between the MTHFR C677T SNP and the prostate adenocarcinoma in Iranian males attending to the Labbafi-nezhad hospital in Tehran. In this Case-control unmatched study, 67 and 75 paraffinized tissue samples were taken out of the specimens diagnosed previously as the prostatic adenocarcinoma and nodular prostatic hyperplasia for the case and control groups respectively. MTHFR C677T genotyping was done by the use of multiplex ARMS-PCR and frequencies of the alleles were compared between the case and control groups as well as calculating the deviation from Hardy-Weinberg equilibrium and Odds Ratio for the "T" allele regarding the prostatic carcinoma. The observed rates in the control group were not too different from that of expected from Hardy- Weinberg equilibrium [P=0.407]. Frequencies of the possible genotypes were as follows: CC, 43.28% vs. 42.67%; CT, 49.25% vs. 52% and CT, 7.46% vs. 5.33% in the case and control groups respectively [P=0.85]. 1.37 times increased risk was found for the homozygote carriers of C677T variant [OR: 1.37, 95% CI: 0.33- 5.6; P=0.653] which is however statistically not significant. No association has been evident between the MTHFR 677C>T polymorphism and the risk of prostatic carcinoma in this study confirming the findings of some of the previous attempts; however, [OR: 1.37, 95% CI: 0.33-5.6] implies a slight effect of the homozygote on the carcinogenesis. Thus larger studies especially with a greater number of the smaples are recommended

Evaluation the effect of change in convergence angle of tooth preparation and copping thickness on fracture resistance of all ceramic crowns

Low fracture resistance is one of the most important disadvantages of all-ceramic restorations. The aim of the present study was to assess the effect of convergence angle and change in copping thickness related to it on fracture resistance of all ceramic crowns. This study was an experimental study in which 30 brass dies were fabricated as crowns with a height of 5.5mm, base diameter of 6.2mm and marginal thickness of 1.2mm in the following design: [10 shoulder 90° -" Convergence 6°], [20 shoulder 90° - Convergence 12°]. With a special index, 0.6mm thickness acrylic cores were made on 20 dies [10 with 6° convergence, 10 with 12° convergences]. With the 6° index and 12° dies, 10 cores were made with the thickness of 0.6mm+difference in thickness of 6° and 12° convergence angle. Cores were casted with IPS e.max porcelain of core and veneered with another index with parallel cylindrical wall and then cemented with Panavia F2 on the brass dies. After storage in distilled water of 37°c for 24 hours, the specimens were placed in compressive test ring within an Instron universal testing machine and loaded in the center of occlusal surface with a 4mm diameter stainless steel ball. An axial preload of 20N was applied followed by a compressive load until fracture occurred. The data were analyzed with one way analysis of variance [ANOVA]. Average fracture load in 6° convergence angle and 0.6mm core thickness was 1951.40N, in 12° convergence angle and 0.6mm core thickness, it was 2798.46N and in 12° convergence angle and 0,6mm+additional core thickness because of increase in convergence angle, it was 3151.05N. The results revealed no significant difference in the fracture load between two core thickness but fracture load of 12° convergence angle was significantly greater than 6° [P<0.001]. Copping thickness didn't affect the fracture load of all ceramic crowns but increase in convergence angle increased the fracture load significantly

comparison of serum ferritin concentration between healthy people with and without history of family diabetes

This study aims to compare serum ferritin of the first degree relatives of diabetic patients with the control group. This is a case control study. Thirty five adults in each group of case and control group were chosen by random technique. For each individual a questionnaire was completed and serum ferritin and fasting blood sugar concentration of the subjects were measured. Parametric and non parametric tests were used for comparing groups were appropriate. About 74.2% of subjects were female and 25.8% were males in each group. Mean frittin concentration in case group was higher than this mean among respondents in control group [63 +/- 58.73ng/dl versus 58.07 +/- 54.57ng/dl]. The fasting blood sugar concentration in the case group was also higher than the control group [100.6 +/- 37.38mg/dl versus 95.9 +/- 17.02mg/dl]. However these differences were not significant between the two groups. There was a significant correlation between the ferritin concentration and fasting sugar in case group. Although there wasn't a significant difference in mean ferritin concentration between the two groups, the higher ferritin concentration among respondents in the case group comparing to it's concentration among respondents in control group is very important. More investigation of this type recruiting larger groups as case and control is suggested