Toward 300 mm wafer-scalable high-performance polycrystalline chemical vapor deposited graphene transistors.

The largest applications of high-performance graphene will likely be realized when combined with ubiquitous Si very large scale integrated (VLSI) technology, affording a new portfolio of "back end of the line" devices including graphene radio frequency transistors, heat and transparent conductors, interconnects, mechanical actuators, sensors, and optical devices. To this end, we investigate the scalable growth of polycrystalline graphene through chemical vapor deposition (CVD) and its integration with Si VLSI technology. The large-area Raman mapping on CVD polycrystalline graphene on 150 and 300 mm wafers reveals >95% monolayer uniformity with negligible defects. About 26,000 graphene field-effect transistors were realized, and statistical evaluation indicates a device yield of ∼ 74% is achieved, 20% higher than previous reports. About 18% of devices show mobility of >3000 cm(2)/(V s), more than 3 times higher than prior results obtained over the same range from CVD polycrystalline graphene. The peak mobility observed here is ∼ 40% higher than the peak mobility values reported for single-crystalline graphene, a major advancement for polycrystalline graphene that can be readily manufactured. Intrinsic graphene features such as soft current saturation and three-region output characteristics at high field have also been observed on wafer-scale CVD graphene on which frequency doubler and amplifiers are demonstrated as well. Our growth and transport results on scalable CVD graphene have enabled 300 mm synthesis instrumentation that is now commercially available.

Transformation of the electrical characteristics of graphene field-effect transistors with fluoropolymer.

We report on the improvement of the electronic characteristics of monolayer graphene field-effect transistors (FETs) by an interacting capping layer of a suitable fluoropolymer. Capping of monolayer graphene FETs with CYTOP improved the on-off current ratio from 5 to 10 as well as increased the field-effect mobility by as much as a factor of 2 compared to plain graphene FETs. Favorable shifts in the Dirac voltage toward zero with shift magnitudes in excess of 60 V are observed. The residual carrier concentration is reduced to ~2.8 × 10(11) cm(-2). Removal of the fluoropolymer from graphene FETs results in a return to the initial electronic properties before depositing CYTOP. This suggests that weak, reversible electronic perturbation of graphene by the fluoropolymer favorably tune the electrical characteristics of graphene, and we hypothesize that the origin of this improvement is in the strongly polar nature of the C-F chemical bonds that self-organize upon heat treatment. We demonstrate a general method to favorably restore or transform the electrical characteristics of graphene FETs, which will open up new applications.

Medication taking behavior of students attending a private university in Bangladesh.

The objective of this study was to investigate the patterns of self-reported medication use, including both prescription and OTC drugs, and to assess the possible predictors of self-medication and medication non-compliance (non-adherence), for 929 non-medical undergraduate students of the American International University, a private university situated in Dhaka city, Bangladesh. Although a high proportion (69%, n = 644) of students of this university had fallen sick in the last six months before the study, the rate of visiting qualified health practitioners was much lower (53%). A good proportion of the sick students were reported to have practiced self-medication (16%, n = 100) and medication non-adherence (15%, n = 98). The average treatment cost involved in self medication was much lower than that offered by a qualified physician (Tk 463 vs Tk 2546 per case). Those students living with parents were more likely to have visited qualified health practitioners (56%, p < .05), and students whose families kept a well-stocked medicine cabinet at home were more likely to have completed the full course (39%, p < .05) of prescribed medicine. No significant difference was found in the rates of self medication and medication compliance incidence for variables like age groups, gender, residence status, financial level, engagement in part-time jobs etc. The study also showed that antimicrobials are widely available (170 incidents) in the home medicine cabinets of the Dhaka City population. The storage of leftover antibiotics in the home constitutes an alternative potential source of self-medication that can have untoward consequences. Further elaborate studies are required to reveal the true pattern of antibiotic usage in Bangladesh.

Midline Fractures in Single Maxillary Complete Acrylic vs Flexible Dentures.

BACKGROUND: Patients using single maxillary denture against their natural mandibular teeth face the problem of midline fracture in their routine acrylic dentures. Various techniques have failed over the years to address the problem. In this study, flexible denture material (Lucitone) with injection moulding system has been used and evaluated for midline fracture in these patients. METHODS: A total of 58 patients in the age group of 38 to 80 years, who had experienced midline fracture in their acrylic maxillary dentures were selected. They were provided with new dentures using flexible denture material. Various parameters, namely, mastication, phonetics, esthetics and comfort level were evaluated. RESULT: Only two cases reported slight crack in the palatal region of the-maxillary dentures after 18 months of use. Mastication and phonetics were found to be improved with flexible dentures. CONCLUSION: The flexible denture is a promising material for preventing midline fractures in a single maxillary denture. It is well tolerated by the patients as compared to the methyl meth-acrylate dentures.

The spatial distribution of leprosy in four villages in Bangladesh: an observational study.

BACKGROUND: There is a higher case-detection rate for leprosy among spatially proximate contacts such as household members and neighbors. Spatial information regarding the clustering of leprosy can be used to improve intervention strategies. Identifying high-risk areas within villages around known cases can be helpful in finding new cases. METHODS: Using geographic information systems, we created digital maps of four villages in a highly endemic area in northwest Bangladesh. The villages were surveyed three times over four years. The spatial pattern of the compounds--a small group of houses--was analyzed, and we looked for spatial clusters of leprosy cases. RESULTS: The four villages had a total population of 4,123. There were 14 previously treated patients and we identified 19 new leprosy patients during the observation period. However, we found no spatial clusters with a probability significantly different from the null hypothesis of random occurrence. CONCLUSION: Spatial analysis at the microlevel of villages in highly endemic areas does not appear to be useful for identifying clusters of patients. The search for clustering should be extended to a higher aggregation level, such as the subdistrict or regional level. Additionally, in highly endemic areas, it appears to be more effective to target complete villages for contact tracing, rather than narrowly defined contact groups such as households.

The spatial distribution of leprosy cases during 15 years of a leprosy control program in Bangladesh: an observational study.

BACKGROUND: An uneven spatial distribution of leprosy can be caused by the influence of geography on the distribution of risk factors over the area, or by population characteristics that are heterogeneously distributed over the area. We studied the distribution of leprosy cases detected by a control program to identify spatial and spatio-temporal patterns of occurrence and to search for environmental risk factors for leprosy. METHODS: The houses of 11,060 leprosy cases registered in the control area during a 15-year period (1989-2003) were traced back, added to a geographic database (GIS), and plotted on digital maps. We looked for clusters of cases in space and time. Furthermore, relationships with the proximity to geographic features, such as town center, roads, rivers, and clinics, were studied. RESULTS: Several spatio-temporal clusters were observed for voluntarily reported cases. The cases within and outside clusters did not differ in age at detection, percentage with multibacillary leprosy, or sex ratio. There was no indication of the spread from one point to other parts of the district, indicating a spatially stable endemic situation during the study period. The overall risk of leprosy in the district was not associated with roads, rivers, and leprosy clinics. The risk was highest within 1 kilometer of town centers and decreased with distance from town centers. CONCLUSION: The association of a risk of leprosy with the proximity to towns indicates that rural towns may play an important role in the epidemiology of leprosy in this district. Further research on the role of towns, particularly in rural areas, is warranted.

Etiology and Management of Zygomaticomaxillary Complex Fractures in the Armed Forces.

BACKGROUND: The nature of duties in the Armed Forces predisposes its personnel to various kinds of injuries. The rise in violence coupled with an exponential increase in motorized population has contributed towards maxillofacial injuries. The aim of this study was to determine the incidence, cause and pattern of various injuries resulting in fracture of the zygomaticomaxillary complex in Armed Forces personnel and their families. METHODS: A study was conducted between January 2001 - December 2002 in maxillofacial surgical wing of an Army Dental Centre with specific regard to age, sex, location and etiology of zygomaticomaxillary complex fracture. Out of 201 maxillofacial injuries received, 87 individuals were treated for zygomaticomaxillary fractures. Majority of the individuals were in their third decade of life and road traffic accident was the leading cause of the fractures. RESULTS: Uneventful recovery was there in 81 individuals (93.10%). Six patients (6.89%) had post operative complications in the form of enophthalmos, hypophthalmos, paraesthesia, diplopia and facial asymmetry. These complications were subsequently treated successfully as a secondary procedure for all the patients. CONCLUSION: Facial bones, especially of the middle third of the face, are composed of a network of fragile bones which give way in case of force to a lesser extent than other parts of the body. It is imperative to educate people regarding the importance of restraints and use of protective headgears/use of seat belts while travelling in motorized transport.

Maxillofacial Injuries in Counter Proxy War Posture of the Armed Forces.

BACKGROUND: Various maxillofacial injuries, sustained in counter insurgency operations in the counter proxy war posture (CPWP) of the Armed Forces in the Kashmir valley are being treated at various maxillofacial surgical centres. METHOD: Proper triage, documentation of injuries and mode of injuries along with various clinical, radiological and other investigations were carried out before operating these individuals for primary reconstruction of skeletal tissue and facial soft tissue. RESULT: A total of 324 persons with various types of maxillofacial injuries were treated within the period ranging from 01 January 2000 to 30 June 2002 successfully in this centre as a part of the advanced trauma life support (ATLS) system of Combat Medical Support. CONCLUSION: Proper primary reconstruction (soft tissue and skeletal tissue) of the facial region goes a long way in reducing subsequent disfigurement and morbidity. Improving the structural design of the combat head gear for safety and comfort will go a long way in preventing majority of maxillofacial injuries or can at least reduce the severity of these injuries.

Liquid chromatography/mass spectrometry methods for distinguishing N-oxides from hydroxylated compounds

This study describes the application of liquid chromatography/mass spectrometry (LC/MS) methods for distinguishing between aliphatic and aromatic hydroxylations and between hydroxylations and N-oxidations. Hydroxylations and N-oxidations are common biotransformation reactions of drugs. Electrospray (ESI) and atmospheric pressure chemical ionization (APCI) were used to generate ions from liquid chromatographic effluents. ESI-MS, ESI-MS/MS, APCI-MS, and APCI-MS/MS experiments were performed on several metabolites and derivatives of loratadine (a long-acting and nonsedating tricyclic antihistamine) using an ion trap mass spectrometer (LCQ) and a triple-quadrupole mass spectrometer (TSQ). The observations are as follows: (1) LC/ESI-MS produced predominantly [M + H]+ ions with minor fragmentation. (2) LC/ESI-MS/MS data, however, showed a predominant loss of water from metabolites with aliphatic hydroxylation while the loss of water was not favored when hydroxylation was phenolic. N-Oxides (aromatic and aliphatic) showed only a small amount of water loss in the MS/MS spectra. (3) Under LC/APCI-MS conditions, aliphatic hydroxylation could be readily distinguished from aromatic hydroxylation based on the extent of water loss. In addition, N-oxides produced distinct [M + H - O]+ ions. These [M + H - O]+ ions were not produced in the APCI-MS spectra of hydroxylated metabolites. (4) Similar to the ESI-MS/MS spectra, the APCI-MS/MS spectra from the (M + H)+ ions of N-oxides yielded a small amount of water loss but no [M + H - O]+ ions. These results indicate that LC/APCI-MS can be used to distinguish between hydroxylated metabolites and N-oxides.