An In Vitro Analyses of Three Body Wear Simulation in Four Posterior Resin Composites

Wear resistance of composite restorative materials has been a major concern especially when used as an posterior restorative material. The purpose of this study was to evaluate and compare the wear resistance of four newer posterior resin composites materials by three body wear simulation method. Wear was evaluated by measuring the amount weight loss using a highly sensitive physical balance, surface roughness was measured with a contact type surface profilometer and the wear surface characterized was by scanning electron microscope and optical microscope. Four newer posterior resin composite materials used in the study was methacrylate based nanohybrid posterior composite filtek z350 (3M ESPE), a silorane based composite filtek silorane p90 (3M ESPE), Ormocer based composite admira (VOCO) and packable composite surefil (DENTSPLY). The four posterior composites evaluated in the study were categorized as, group 1filtekz 350, group 2 - filtek silorane p-90 ,group 3 admira, group 4 surefil. The wear instrumentation used was a Dry abrasion tester, customized with stainless steel wheel, and distilled water was used as lubricant. Test instrument was designed such that a flat test sample is pressed radially against a wheel with a force of 20N. Abrasive media was introduced into the contact area between the sample under test and the wheel such that the wheel carries the abrasive media between the sample and the wheel creating a three body wear. The intial weight of each specimen was measured in milligrams using a highly sensitive physical balance. Material wear was measured by the loss of material at every 5000 cycles from 5000 cycles till 30000cycles. The samples were evaluated for surface roughness at every 5000 cycles from 5000 cycles till 30000 cycles by using contact type surface profilometer. The wear surface was analyzed with optical microscope and Scanning electron microscope to characterize the wear pattern. One-Way ANOVA followed by TUCKEYS post hoc test was used for statistical analysis at the 0.05 significance level. The mean weight loss values at the end of 30000 cycle was found to be highest in group 4 and weight loss values was found to be lowest in group1 with significance level of 1%. The mean wear depth values at the end of 30000 cycle was found to be highest in group 4 and lowest in group 1 with a significance level of 1% and this findings were confirmed by scanning electron microscope findings. CONCLUSION: From the results of the present study it can be concluded that: 1. Particle size plays a major role on the wear resistance of dental composites. FILTEKZ-350 a nano hybrid composite with a filler particle size of 5-20nm revealed least weight loss at the end of 30000 cycles when compared with other newer posterior resin composites namely silorane, ormocers and packable composites used in this study. 2. An interesting observation made in the present study was that the percentage volume of filler revealed a linear relationship of the filler particles to the wear resistance of that material. FILTEKZ350 with 88%filler volume had the least amount of weight loss when compared with other materials used in the study 3. Another valuable finding observed was the correlation between the filler particle size and the Ra, values that measures the wear depth. (in μm)

The Limits of intellectual property rights: Lessons from the spread of illegal transgenic seeds in India

Genetically modified seeds have to be approved by biosafety regulators before they can be commercialized. Illegal seeds are, however, common in many developing countries including Brazil, China and India. They potentially pose dangers to biosafety and also undermine the intellectual property rights of firms that own the genetically modifed traits. Their unchecked spread has been attributed to the near impossibility of enforcement when potential violators involve millions of small farmers. Based on a survey of cotton growers in Gujarat, India in 2004, and an examination of the structure of cotton seed production this paper finds that the government, in fact, possesed the information and means to enforce the law. A contingent valuation exercise reveals high relative valuations for illegal seeds correlated with the perceived costs of pesticide application. We discuss how that matters to the political cost of enforcement and to socially optimal policiesIntellectual Property Rights, Biosafety Regulation, Genetically Modified Seeds, Transgenic Varieties, Bt Cotton

CBR Anisotropy in an Open Inflation, CDM Cosmogony

We compute the cosmic background radiation anisotropy, produced by energy-density fluctuations generated during an early epoch of inflation, in an open cosmological model based on the cold dark matter scenario. At $\Omega_0 \sim$ 0.3 -- 0.4, the COBE normalized open model appears to be consistent with most observations.Comment: (12 pages, plain TeX; 3 figures available upon request from the authors), IASSNS-HEP-94/39, PUPT-1470, POP-568, CfPA-TH-94-27, UTAP-18

Identification of MHC Class II Binders/ Non-binders using Negative Selection Algorithm

The identification of major histocompatibility complex (MHC) class-II restricted peptides is an important goal in human immunological research leading to peptide based vaccine design. These MHC class–II peptides are predominantly recognized by CD4+ T-helper cells, which when turned on, have profound immune regulatory effects. Thus, prediction of such MHC class-II binding peptides is very helpful towards epitope-based vaccine design. HLA-DR proteins were found to be associated with autoimmune diseases e.g. HLA-DRB1*0401 with rheumatoid arthritis. It is important for the treatment of autoimmune diseases to determine which peptides bind to MHC class II molecules. The experimental methods for identification of these peptides are both time consuming and cost intensive. Therefore, computational methods have been found helpful in classifying these peptides as binders or non-binders. We have applied negative selection algorithm, an artificial immune system approach to predict MHC class–II binders and non-binders. For the evaluation of the NSA algorithm, five fold cross validation has been used and six MHC class–II alleles have been taken. The average area under ROC curve for HLA-DRB1*0301, DRB1*0401, DRB1*0701, DRB1*1101, DRB1*1501, DRB1*1301 have been found to be 0.75, 0.77, 0.71, 0.72, and 0.69, and 0.84 respectively indicating good predictive performance for the small training set

Development of Rate Expression for Glycerol Hydrogenation Reaction

AbstractThis paper highlights various routes for glycerol reaction and also pathway for heterogeneous catalyst and also being obtained as by product of biodiesel making it cost effective and easy availability. Whereby it also aims at development of rate model and compares values of calculated and experimentally obtained rate constant. It also aims at hydrogenation carried out at liquid phase and gas phase and also various types of catalyst, support and promoter that can be used in hydrogenation of glycerol, and also advantage of various by-products and intermediate formed by glycerol hydrogenation reaction. It also aims at various intermediate formed by acid/solid base catalyst

Study of changes in coagulation profile of patients undergoing laparoscopic cholecystectomy using carbon dioxide pneumoperitoneum

BACKGROUND: Laparoscopic cholecystectomy is a common surgical procedure and carbon dioxide pneumoperitoneum created for this purpose may alter the coagulation profile of these patients. This study aims to find the effects of carbon dioxide pneumoperitoneum on coagulation profile and assess if there is an increased risk of thrombosis. MATERIALS AND METHODS: A clinical observational study was conducted with 50 patients who underwent laparoscopic cholecystectomy using carbon di oxide pneumoperitoneum. The prothrombin time and D-dimer values were calculated before and after surgery .using the paired t test data was analyzed. RESULTS: The study showed a decrease in the prothrombin time and increase in the D-dimer value post operatively. The mean of prothrombin time after surgery was 0.13 seconds lower than the preoperative value and D-dimer was found to be elevated three times the pre operative values. The p value calculated for both were highly significant. CONCLUSION: Laparoscopic cholecystectomy using carbon dioxide pneumoperitoneum leads to hypercoagulable states. Hence stringent measures need to be taken to put the patient on prophylaxis for deep vein thrombosis to avoid dire consequences

Modeling mechanical properties of low carbon hot rolled steels

Steel is the most important material and it has several applications, and positions second to cement in its consumption in the world. The mechanical properties of steels are very important and vary significantly due to heat treatment, mechanical treatment, processing and alloying elements. The relationships between these parameters are complex, and nonlinear in nature. An artificial neural networks (ANN) model has been used for the prediction of mechanical properties of low alloy steels. The input parameters of the model consist of alloy composition (Al, Al soluble, C, Cr, Cu, Mn, Mo, Nb, Ni, P, S, Si, Ti, V and Nitrogen in ppm) and process parameters (coil target temperature, finish rolling temperature) and the outputs are ultimate tensile strength, yield strength, and percentage elongation. The model can be used to calculate properties of low alloy steels as a function of alloy composition and process parameters at new instances. The influence of inputs on properties of steels is simulated using the model. The results are in agreement with existing experimental knowledge. The developed model can be used as a guide for further alloy developmen

Pyrexia of unknown origin: a rare presentation of primary ovarian lymphoma

It is very rare to have a lymphomatous involvement of ovary. Malignant lymphoma of ovary is a well-known late manifestation of disseminated nodal disease. Primary ovarian lymphoma with ovarian mass as an initial manifestation is a rare entity and may have varied presentations which can cause confusion to the physician and cause delay in diagnosis. Study presents a case of non-Hodgkin’s lymphoma where the initial presentation was fever with weight loss, and was evaluated as pyrexia of unknown origin. When no other cause of fever was identified PET-CT was done showing metabolically active uterine mass with no lymphadenopathy. Exploratory laparotomy was planned followed by hysterectomy with bilateral salpingo ophorectomy with omentectomy. Ovarian malignancy was detected intraoperatively, which was diagnosed as diffuse large B cell lymphoma, NHL double expresser phenotype on histopathology and IHC. Patient was started on chemotherapy and is doing fine

Relation between Preference for Local or Global Brands and Various Demographic Features of Consumer

Now a days, dilemma of choosing between local and global brands is faced while purchasing most of the goods be it be a needle or a sophisticated machinery. Good quality and affordable prices of goods of global brands are overpowering the local brands. It is seen that young generation is getting very much inclined towards the global brands and gradually local brands are finding it difficult to survive in market. Along with age many other factors are also responsible for this phenomenon. In this situation a study on various factors which are related with preference for local or global brands is need of the hour. For the purpose of study a questionnaire was developed and sent to respondents in order to find out whether actually there is any relationship between demographic factors of respondents and their choice between branded and local goods. On the bases of survey it was found out that, actually there is a relation between demographic factors of respondents and their choice between local and branded goods to a large extent