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The strain hardening exponent and strength coefficient of the Ramberg-Osgood flow rule are required for the accurate design analysis of the materials of aeroengine components. A direct method of deriving these parameters involves the processing of the complete raw data of tensile testing as per ASTM E-646. More often, a first design effort of aeroengine components is made using catalogue data, as the evaluation of material tensile properties is a time-consuming process that takes place concurrently. Catalogue-supplied data on the monotonic loading typically contains elastic modulus, 0.2% proof stress, and ultimate tensile stress along with other data for various temperatures. A methodology was evolved in this work to construct the Ramberg-Osgood flow rule with these three parameters and was validated with laboratory test results and published data through a comparison with ASTM E-646. The strain hardening exponents and strength coefficients were established for a family of aeroengine metallic materials for various temperatures, which can serve as a first design effort input.

Aluminum alloy based metal matrix composites are widely used in aerospace, military and automotive industry. The aluminium grades used in present research work are Aluminium alloy 6061, Aluminium alloy 2024, LM6. In this research, composites with Aluminum alloy as matrix with 6 weight % of nano alumina as reinforcement were fabricated using two processing technique namely, powder metallurgy technique (cold pressing and microwave sintering), and by squeeze casting technique. Thus fabricated samples were used to study the effect of processing technique on mechanical properties and wear aspects of the composite. Scanning electron microscope data and mechanical property characteristics reveals the presence of nano alumina particles and their uniform distribution in case of powder metallurgy processed samples. Mechanical and wear properties achieved on the fabricated samples were compared with the existing aerospace brake pad material. The data related to wear characteristics correlated with the number of landings for the existing brake pad material is considered as the bench mark data and the feasibility of replacing it with the developed composites were studied.

Background : Oral submucous fibrosis (OSF) may be considered a collagen metabolic disorder resulting from areca-nut alkaloid exposure and individual variation in collagen metabolism. Due to the complexity of OSF pathogenesis, it is important to elucidate independent and interactive effects of polymorphisms of collagen-related genes on OSF risk. Materials and Methods : This study is focused on seven polymorphisms (SNPs) of transforming growth factor-beta-1 (TGF-beta-1) gene in patients with oral submucous fibrosis (OSF), belonging to south Indian ethnic extraction. The mean age at presentation was 43.9 years, range 23-72 years (n=50, M:F ratio, 2.6:1). DNA samples from 50 subjects of the same ethnic group and comparable demographic features who have had practiced the habit of areca-chewing of almost equal duration, but remained free of disease constituted the controls. All DNA samples were collected progressively and purified from peripheral blood employing standard protocols and tested for SNPs. They included two polymorphisms in the promoter region (C-509T and G-800A), three polymorphisms in exon-1 (Arg25Pro(G915C), Leu10Pro(T869C), Glu47Gly(A979G) and two in 5 ¢UTR regions (C→T(rs13306708) and G→A (rs9282871). The extracted DNA samples along with the primers underwent PCR amplification and the genotypic and allelic frequencies were calculated. All calculations were performed using the SPSS software. The PCR products were purified and subsequently sequenced using Flour S™ multi-imager system (Biorad). The sequenced data were analyzed using the BioEdit sequence analysis software. Results : Out of the seven polymorphisms analyzed, six such as two in the promoter region, three in exon-1 and one in 5¢UTR were found to have a " P" value above 0.05 and hence were not significant. The C→T transition (rs13306708) in the 5¢UTR region recorded a " P" value of 0.03 on comparison and hence was found to be significant. The allelic frequencies for this C→T transition in patients were 68.7% C and 31.2% T (27CC, 15CT, 8TT) and that in controls were 89.5% C and 10.4% T (42CC, 6CT, 2TT). Conclusions : The polymorphism in 5¢UTR C-T in TGF beta 1 gene has a significant association with OSF, being a prime determinant in the pro-angiogenic pathway which has got direct bearing with the pathophysiology of the disease. The proximity of this polymorphism to the transcription site and the associated risk involved is discussed.

The oral cavity has been considered a potential reservoir for Helicobacter pylori (H pylori) , from where the organism causes recurrent gastric infections. Aim: With this case-control study we tried to evaluate the role of H pylori in the etiology of mucosal inflammation, a condition that compounds the morbid state associated with oral submucous fibrosis (OSF). Materials and Methods : Subjects ( n = 150) were selected following institutional regulations on sample collection and grouped into test cases and positive and negative controls based on the presence of mucosal fibrosis and inflammation. The negative controls had none of the clinical signs. All patients underwent an oral examination as well as tests to assess oral hygiene/periodontal disease status; a rapid urease test (RUT) of plaque samples was also done to estimate the H pylori bacterial load. We used univariate and mutivariate logistic regression for statistical analysis of the data and calculated the odds ratios to assess the risk posed by the different variables. Results : The RUT results differed significantly between the groups, reflecting the variations in the bacterial loads in each category. The test was positive in 52% in the positive controls (where nonspecific inflammation of oral mucosa was seen unassociated with fibrosis), in 46% of the test cases, and in 18% of the negative controls (healthy volunteers) (χ2 = 13.887; P < 0.01). A positive correlation was seen between the oral hygiene/periodontal disease indices and RUT reactivity in all the three groups. Conclusions: The contribution of the H pylori in dental plaque to mucosal inflammation and periodontal disease was significant. Logistic regression analysis showed gastrointestinal disease and poor oral hygiene as being the greatest risk factors for bacterial colonization, irrespective of the subject groups. A positive correlation exists between RUT reactivity and the frequency of mucosal inflammation.

Objective: We tested the hypothesis that inducible nitric oxide synthase (iNOS) modulates angiogenesis in human models and this information could be extrapolated in elucidating the pathophysiology of oral submucous fibrosis (OSF). A hypothesis which looks inadequate, but is deep rooted in literature is the epithelial alteration ("atrophy") seen in OSF and the events that lead to its causation. This aspect was tried to be addressed and an alternative pathogenetic pathway for the disease is proposed. Materials and Methods: This immunohistochemical study sought to investigate the expression of iNOS in OSF samples (n= 30) a using monospecific antibody (SC- 2050, Santa Cruz Biotechnology, Inc) to the protein and also to correlate it with different grades of epithelial dysplasia associated with the disease. Twenty (20) healthy adults acted as controls. Results: iNOS staining was not demonstrated in normal oral epithelium. In oral epithelial dysplasia, staining was seen in all cases (100%) in the basal layers of the epithelium and in 30% of cases it extended into the parabasal compartments as well. iNOS staining was uniformly positive in moderate dysplasia with an increase in intensity and distribution noted as the severity of dysplasia progressed. There were highly significant differences in overall positivity for iNOS in epithelium between cases and controls (Mann-Whitney U = 11.000, Wilcoxon W = 221.00, P = 0.000). Significant comparisons were made of mild Vs moderate dysplasia (Mann-Whitney U = 48.000, P = 0.014) Conclusions: This study supports our earlier morphological assessment (image analysis) of the nature of vascularity in OSF mucosa. The significant vasodilation noticed in these cases argues against the concept of ischemic atrophy of the epithelium. This observation of vascularity and iNOS expression helped to explain the vasodilation noticed (sinusoids) in this disease; NO being a net vasodilator. The mechanism of activation of iNOS in dysplasia is difficult to explain. The role of contingent paracrine-activating factors on keratinocytes and macrophages is discussed.

This work compares conventional unidirectional rolling (UDR) and cross rolling (CR) based on mechanical properties, microstructure, and stored energy. Pure copper is subjected to UDR and CR to true strains of 0.69, 1.39, 2.08, and 2.77, respectively. The UDR samples show high strength and hardness compared to the CR. Investigation of microstructures of formed samples using optical microscopy and EBSD revealed that the grains were elongated along with the rolling directional for UDR and fairly equiaxed grains with reduced anisotropy for CR. The stored energy calculated using calorimetry experiments was correlated with mechanical and microstructure evolution. [ABSTRACT FROM AUTHOR]

OBJECTIVE : This study was designed to determine the effect of pentoxifylline (Trental) on the clinical and pathologic course of oral submucous fibrosis. This drug is a methylxanthine derivative that has vasodilating properties and was envisaged to increase mucosal vascularity. STUDY DESIGN : This investigation was conducted as a randomized clinical trial incorporating a control group (Standard drug group SDG, multivitamin, and local heat therapy) in comparison to pentoxifylline test cases (Experimental drug group EDG, 400mg 3 times daily, as coated, sustained release tablets). The stipulated treatment period was 7 months and a total of 29 cases of advanced fibrosis (14 test subjects and 15 age and sex matched diseased controls) were included in this study and 100% compliance was reported at the end ofthe test period. RESULTS : Mild gastric irritation that could be managed by diet protocols was the only untoward symptom reported during this trial. Review of the patients and controls was done at an interval of 30 days and subjective and objective measurements were recorded. The follow up data at each visit with respect to each other and to base-line values was calibrated using a nonparametric test of Mann-Whitney (Kruskal-Wallis test). Significant comparisons with regard to improvement were recorded as objective criteria of mouth opening (t=11.285, p= 0.000), tongue protrusion (t= 3.898, p = 0.002), and relief from perioral fibrotic bands (p = 0.0001554). Subjective symptoms of intolerance to spices (p = 0.0063218), burning sensation of mouth (p = 0.0005797), tinnitus (p=0.000042), difficulty in swallowing (p=0.0000714). and difficulty in speech (p=0.0000020) were also recorded significant improvement at the end of the trial period. CONCLUSION : This pilot investigation points to the effectiveness of pentoxifylline as an adjunct therapy in the routine management of oral submucous fibrosis.

Immunohistochemical staining of formalin fixed, paraffin embedded tissue sections of OSF for MMPs-1,2,9 and their tissue inhibitors TIMP-1and 2 was performed using monospecific antibodies coupled with gelatin zymography (MMP-2 and 9) for measuring enzymatic activity quantitatively and for distinguishing the active from the inactive variants of enzymes. The present study, contrary to earlier reports, recorded statistically significant increase in the levels of stromal expression of MMP-1, MMP-2 and MMP-9 and TIMP-1 and TIMP-2 using monospecific antibodies reacting against tissue antigens.The simultaneous increase in reactivity of MMPs and TIMPs poise difficulty in interpretingthe results of this study. The possible reasons for this result, against the backdrop of existing knowledge, were attempted in this study.