Processing Conditions for Boron Nitride Coatings in Fiber Bundles via Chemical Vapor Deposition

A model for the transport and reaction of BCI₃ and NH₃ for the deposition of BN on individual filaments in a fiber bundle at low pressures has been developed using previously published kinetic data. An operating diagram is presented which summarizes the results of the model and facilitates the choice of deposition parameters for obtaining uniform coatings throughout the bundle. The uniformity of coatings deposited on individual fibers of Nicalon, Sumitomo-A1₂O₃ fiber bundles, and straight weave Nicalon cloth is consistent with the model predictions.     

Client architecture for MPEG-4 streaming

As Web-based services increasingly include streaming media, broadband service providers must address the challenges inherent in the real-time delivery of high-bandwidth content over a best-effort network. The Multilevel Buffer Architecture is a buffering mechanism for MPEG-4 decoder players, providing a set of services for accommodating network jittering, precise A/V sync, and QoS management.     

Predictive value of morphological nuclear parameters and DNA ploidy pattern in precancerous lesions of the uterine cervix

To evaluate the supportive role of image cytometry and DNA ploidy analysis in the precancerous and cancerous lesions of the uterine cervix, the present study was performed on 45 cervical smears, initially diagnosed as dysplasia and malignant. Twenty normal and inflammatory smears were taken as a control for the study. Morphometric parameters and microphotometric DNA measurements were performed on 50 cells in each case. On the basis of nuclear area dysplastic lesions were categorised into two groups i.e. low grade lesions having nuclear area upto 85 sq. mu m and high grade lesions having nuclear area above 85 sq. mu m. The results were compared with DNA ploidy analysis. It is revealed from the study that 85.7% low grade lesions with diploid and polyploid DNA, value mostly regressed to inflammation and 78.5% high grade lesion with aneuploid DNA value progressed to malignancy. However, initial malignant cases having aneuploid DNA value exhibit invasive cancer during their follow up. It indicates that combination of morphometry and DNA cytometry can be used as an adjunct to cytologic diagnosis to predict the biologic outcome of the lesions.     

Oxidation-Resistant Fiber Coatings for Non-oxide Ceramic Composites

Oxidation of fiber/matrix interfaces can degrade the strength and toughness of ceramic composites containing non-oxide constituents. Oxidation can occur when the fiber ends are exposed or in the presence of cracks. Theoretical considerations indicate that, contrary to popular belief, oxide fiber coatings should be worse than non-oxide fiber coatings for protection against oxidation. Furthermore, oxidation of fiber/matrix interfaces is a composite system problem rather than that of the fiber coating.     

Dynamic backlight adaptation for low-power handheld devices

Backlight power minimization can effectively extend battery life for mobile handheld devices. This article proposes an adaptive middleware-based approach to optimize backlight power consumption when playing streaming video. The technique simultaneously minimizes the negative impact on perceived video quality.     

Developing textile entrepreneurial inclination model by integrating experts mining and ISM-MICMAC

The Indian textile industry is lacking in an entrepreneurial inclination of a skilled young generation; because of this, the industry is facing a challenge to achieve sustainable development and growth. To overcome this problem, the goal of this work is to build an entrepreneurial inclination model in the context of the textile industry. For achieving this goal, a combined approach of an extensive literature review and experts mining has been used to establish the entrepreneurial inclination factors in phased of the study. In the second phase, an Interpretive Structural Modelling with Matrice d’Impacts Croisés Multiplication Appliqués à un Classement (MICMAC) has been applied to build a structural model and to find the driving force factors and dependence power. The results show that effective entrepreneurship courses, institutional policy, training and internship, institutional corporation and the involvement of institutional heads play a very significant role in encouraging youth towards entrepreneurship. The outcomes of the study can help both the government and academic institutes to draw up effective policy and develop an entrepreneurial culture which can help to create more entrepreneurs in the textile field.     

Genetic alterations at 5p15: a potential marker for progression of precancerous lesions of the uterine cervix

BACKGROUND: Development of uterine cervical cancer is preceded by preneoplastic proliferative changes in the cervical epithelium called "intra-epithelial neoplasia" or "dysplasia." The genetic basis of the origin and progression of such preneoplastic lesions is not known. By analysis of carcinomas for loss of constitutional heterozygosity (LOH), we have previously shown a high frequency of allelic loss in the short arm of chromosome 5 (5p), suggesting loss of a candidate tumor suppressor gene located in 5p and associated with the development of this tumor. PURPOSE: To further understand the role of genetic alterations that affect 5p in cervical carcinogenesis, we evaluated the status of microsatellite polymorphisms at five loci mapped to 5p14-ter in precancerous and cancerous lesions. METHODS: Biopsy specimens from two groups of patients were analyzed for genetic alterations affecting 5p. One group comprised 14 cases of precancerous lesions (i.e., dysplasias) and five cases of carcinoma in situ (CIS); the second group comprised 46 previously untreated patients with invasive carcinoma. Tumor and normal DNAs were analyzed by polymerase chain reaction for genetic losses and instability at five polymorphic microsatellite loci (D5S392, D5S406, D5S208, D5S117, and D5S432) mapped to 5p. RESULTS: LOH was observed in 25 (55.6%) of 45 informative invasive carcinomas, one (20%) of five cases of CIS, and three (21%) of 14 precancerous lesions. Among the loci tested, D5S406 (5p15.1-15.2) exhibited LOH in 12 (48%) of 25 invasive carcinomas, one (33%) of three cases of CIS, and three (60%) of five precancerous lesions, suggesting this to be the site in 5p of the novel candidate tumor suppressor gene. In addition, replication error-type alterations were noted in the 5p14-ter region in six (13%) of 46 invasive carcinomas, two (40%) of five cases of CIS, and three (21%) of 14 precancerous lesions. Instability affected D5S406 in eight (66.7%) of 12 instances that showed microsatellite instability. CONCLUSION: These observations suggest that allelic loss and microsatellite instability in the region of D5S406 may play a role early in the development of cervical carcinoma and identify the site of a candidate tumor suppressor gene. These genetic markers (allelic loss and microsatellite instability) may also define CIS and precancerous lesions at high risk for progression to invasive cancer. IMPLICATIONS: The future molecular cloning of the candidate tumor suppressor gene at 5p15.1-15.2 may provide new insights into the genetic mechanisms of cervical carcinogenesis. Analysis and clinical follow-up of a large cohort of prospectively ascertained cases of precancerous lesions would help to validate the usefulness of these markers.     

Chemical Considerations in Carbon-Fiber/Oxide-Matrix Composites

Thermochemical calculations are performed to evaluate the chemical compatibility of oxides with carbon at temperatures of the order of 1650°C and to evaluate the implications of carbon oxidation. These calculations indicate that Al₂O₃, BeO, Y₂O₃, and Ce₂O₃ are stable with carbon provided there are no cracks or pores for CO gas to escape. In the presence of cracks or interconnected pores, both the direct reduction of oxides with carbon as well as the oxidation of carbon can proceed rapidly. The calculations also indicate that even in the absence of such cracks the oxidation of carbon can generate high enough CO partial pressures to degrade the composite properties by formation of CO gas bubbles or of cracks in the oxide. The results of these calculations are confirmed by conducting experiments on samples of pyrolytic and vitreous carbon disks hot-pressed within Al₂O₃ and Y₂O₃disks and exposing them in argon and oxygen environments at 1650–1800°C. An oxidation model is then proposed that includes thermodynamic and kinetic considerations as well as creep behavior of oxides. The model quantitatively predicts the times required to initiate the formation of gas bubbles and qualitatively considers the factors influencing the growth rate of bubbles and formation of cracks.     

Some New Perspectives on Oxidation of Silicon Carbide and Silicon Nitride

This study provides new perspectives on why the oxidation rates of silicon carbide and silicon nitride are lower than those of silicon and on the conditions under which gas bubbles can form on them. The effects on oxidation of various rate-limiting steps are evaluated by considering the partial pressure gradients of various species, such as O₂, CO, and N₂. Also calculated are the parabolic rate constants for the situations when the rates are controlled by oxygen and/or carbon monoxide (or nitrogen) diffusion. These considerations indicate that the oxidation of silicon carbide and silicon nitride should be mixed controlled, influenced both by an interface reaction and diffusion.