Donor complex formation due to a high-dose Ge implant into Si

To investigate boron deactivation and/or donor complex formation due to a high‐dose Ge and C implantation and the subsequent solid phase epitaxy, SiGe and SiGeC layers were fabricated and characterized. Cross‐sectional transmission electron microscopy indicated that the SiGe layer with a peak Ge concentration of 5 at. % was strained; whereas, for higher concentrations, stacking faults were observed from the surface to the projected range of the Ge as a result of strain relaxation. Photoluminescence (PL) results were found to be consistent with dopant deactivation due to Ge implantation and the subsequent solid phase epitaxial growth of the amorphous layer. Furthermore, for unstrained SiGe layers (Ge peak concentration ≥7 at. %), the PL results support our previously proposed donor complex formation. These findings were confirmed by spreading resistance profiling. A model for donor complex formation is proposed

Numerical investigation of heat transfer enhancement of nanofluids in an inclined lid-driven triangular enclosure.

The behavior of nanofluids is investigated numerically in an inclined lid-driven triangular enclosure to gain insight into convective recirculation and flow processes induced by a nanofluid. The present model is developed to examine the behavior of nanofluids taking into account the solid volume fraction δ. Fluid mechanics and conjugate heat transfer, described in terms of continuity, linear momentum and energy equations, were predicted by using the Galerkin finite element method. Comparisons with previously published work on the basis of special cases are performed and found to be in excellent agreement. Numerical results are obtained for a wide range of parameters such as the Richardson number, and solid volume fraction. Copper–water nanofluids are used with Prandtl number, Pr = 6.2 and solid volume fraction δ is varied as 0%, 4%, 8% and 10%. The streamlines, isotherm plots and the variation of the average Nusselt number at the hot surface as well as average fluid temperature in the enclosure are presented and discussed in detailed. It is observed that solid volume fraction strongly influenced the fluid flow and heat transfer in the enclosure at the three convective regimes. Moreover, the variation of the average Nusselt number and average fluid temperature in the cavity is linear with the solid volume fraction

Electrical characterization of metal‐insulator‐semiconductor diodes fabricated from laser‐ablated Yba\u3csub\u3e2\u3c/sub\u3eCu\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3e7−δ\u3c/sub\u3e/yttria‐stabilized zirconia films on Si substrates

The purpose of this investigation is to study the electrical properties of the YBCO/YSZ/Si metal‐insulator‐semiconductor structure and the yttria‐stabilized zirconia (YSZ)/Si interface. The YBCO and YSZ layers were epitaxially grown in situ on Si by pulsed laser deposition. Current‐voltage measurements of devices fabricated on p‐type Si(100) showed a small leakage current density at 292 K, which decreased further at 80 K. Comparison of capacitance‐voltage measurements at 292 K for frequencies between 10 and 400 kHz showed a large variation of capacitance in the accumulation region demonstrating the presence of mobile ions in the YSZ layer. This variation is less pronounced at 80 K. A negative shift of about 5 V in threshold voltage from 292 to 80 K has been attributed to redistribution of charges in the YSZ buffer layer

Optimization of mixed convection in a Lid-driven enclosure with a heat generating circular body.

The physical model considered here is a lid-driven enclosure with bottom heating and top cooling conditions, and a heat generating circular body is placed at the center. The vertical walls of the cavity are kept thermally insulated, and the top lid moves at a constant speed. The steady two-dimensional governing equations for the physical problem are transformed in a dimensionless form with dimensionless governing parameters that decide the fluid flow and heat transfer characteristics in the system. The solution of these transport equations is obtained numerically with the finite element approach using the Galerkin method of weighted residuals. The parametric study has been carried out for variation of the heat generation parameters, the Reynolds numbers, solid-fluid thermal conductivity ratios as well as the Richardson numbers. The working fluid is assigned as air with a Prandtl number of 0.71 throughout the simulation. Results are presented in the form of streamlines, isotherms, average Nusselt number, bulk temperature, and drag force for the afore mentioned parameters. The numerical results indicate the strong influence of the mentioned parameters on the flow structure and heat transfer as well as average Nusselt number, average bulk temperature, and drag force. An optimum combination of the governing parameters would result in higher heat transfer and lower drag force

Properties and Device Applications of Hydrogenated Amorphous Silicon Carbide Films

Hydrogenated amorphous silicon carbide (a‐SiC:H) films were deposited with a radio‐frequency plasma‐enhanced chemical vapor deposition system which utilizes a dc electric field applied independently of the inductively coupled rf field. The source gases were SiH4 and CH4. It was found that application of an electric field directed out of the substrate surface enhances the growth rate and yields some improvements in photoconductivity. The compositions of the films were evaluated by x‐ray photoelectron spectroscopy for a range of source gas mixtures. In order to assess the applicability of a‐SiC:H thin films, heterojunction a‐SiC:H/crystalline Si (c‐Si) diodes were fabricated and their electrical characteristics evaluated. The diode capacitance‐voltage results confirmed a step junction, which was consistent with the abruptness of the interface demonstrated by high‐resolution transmission electron microscopy. The heterojunction diodes also showed good rectifying properties, suggesting promise for a‐SiC: H in device applications

Improvement of wastewater quality of Dhaleswari river, Bangladesh using submerged macrophyte Egeria densa

Clean water is one of the significant goals among the 17 Sustainable Development Goals (SDGs), which will be achieved by at least 2030. It includes six outcome-oriented targets- improve water quality, wastewater treatment, ensure freshwater supplies are three of them. In Bangladesh, Freshwater ecosystem is continuously degraded due to rapid industrialization, which occurred along the riverside areas. In this context, laboratory-based work has been conducted to analyze the water quality of Dhaleshwari River, Bangladesh, which has already been polluted by industrial waste. The collected water samples were treated by submerged macrophyte Egeria densa to observe the changing water quality parameters. The growth of plants and roots were assessed after 10 days of exposure to three categories of water treatment. Initial and final water quality parameters were observed by the analysis of pH, EC, TDS, TSS, Acidity, Alkalinity, Total Hardness, Ca Hardness, COD, Sulphate (SO42-), Phosphate (PO43) Total Chlorine (Cl-) and Copper (Cu2+). The result showed that almost all the toxic parameters of water were reduced significantly at the end of the experiment. The present study hypothesized that submerged macrophyte E. densa can be used as a potential tool to upgrade the water quality of polluted rivers.Keyword: Clean water, Submerged macrophyte, SDG 6, Dhaleswari River, Freshwater ecosyste

Ten years of survival among early-stage breast cancer patients: a hospital-based study

Background: The incidence rate of breast cancer is gradually increasing all over the world. In Bangladesh, we have very little research-based information regarding the survival of patients with early-stage breast cancer. The aim of this study was to determine the survival outcome of early-stage (Stages I- IIIA) breast cancer among female patients in respect to their age group, stage of the disease, tumor grade, nodal status, and hormone receptor status Methods: This was a prospective observational study focused on the survival outcome conducted in the department of clinical oncology, Bangabandhu Sheikh Mujib medical university (BSMMU), Dhaka, Bangladesh during the period from December 2011 to December 2021. One hundred and five (105) female patients with early-stage (Stages I-IIIA) breast cancer were selected following the inclusion and exclusion criteria as the study subjects. Properly informed written consent was taken from all the participants before starting data collection. All data were processed, analyzed, and disseminated by MS office and SPSS programs as per need.   Results: The survival rate was found 79% (n=83). We observed stage-wise 10-year overall survival among the participants where 51.60%, 36.10%, and 12.30% survived from tumor stage I, II, and III respectively. We also observed that 29%, 60% and 11% of patients had survived from tumor grade I, II, and III respectively (Out of 83 survival cases). On the other hand, among the 83 10-year survival patients, 53.8% were of negative nodal status whereas 34.20% were of positive nodal status patients. Among the survived 83 patients, 86% were from >40 years’ age group whereas the rest 14% were from <40 years of age group. Conclusions: Early detection and treatment of breast cancer provide a definitive survival benefit. The results of the study showed that comprehensive screening and early detection of breast cancer is required to improve the survival outcome

Disparities in risks of malaria associated with climatic variability among women, children and elderly in the Chittagong hill tracts of Bangladesh

Malaria occurrence in the Chittagong Hill Tracts in Bangladesh varies by season and year, but this pattern is not well characterized. The role of environmental conditions on the occurrence of this vector-borne parasitic disease in the region is not fully understood. We extracted information on malaria patients recorded in the Upazila (sub-district) Health Complex patient registers of Rajasthali in Rangamati district of Bangladesh from February 2000 to November 2009. Weather data for the study area and period were obtained from the Bangladesh Meteorological Department. Non-linear and delayed effects of meteorological drivers, including temperature, relative humidity, and rainfall on the incidence of malaria, were investigated. We observed significant positive association between temperature and rainfall and malaria occurrence, revealing two peaks at 19 °C (logarithms of relative risks (logRR) = 4.3, 95% CI: 1.1–7.5) and 24.5 °C (logRR = 4.7, 95% CI: 1.8–7.6) for temperature and at 86 mm (logRR = 19.5, 95% CI: 11.7–27.3) and 284 mm (logRR = 17.6, 95% CI: 9.9–25.2) for rainfall. In sub-group analysis, women were at a much higher risk of developing malaria at increased temperatures. People over 50 years and children under 15 years were more susceptible to malaria at increased rainfall. The observed associations have policy implications. Further research is needed to expand these findings and direct resources to the vulnerable populations for malaria prevention and control in the Chittagong Hill Tracts of Bangladesh and the region with similar setting

Stigma toward people with COVID-19 among Bangladeshi older adults

The onset of the coronavirus disease (COVID-19) pandemic and its overwhelming physical and mental health burden can result in stigmatization toward the disease and those affected. This study aimed to measure the prevalence of COVID-19-related stigma and its associated factors among older people in Bangladesh. This cross-sectional study was conducted among 1,045 Bangladeshi older adults aged 60 years and above through telephone interviews in September 2021. The outcome was measured using an eight-point Stigma Scale, adapted to the Bengali language. Level of stigma was indicated by the cumulative score of the eight-items, ranging from 0 to 8, with a higher score indicating a higher level of stigma. On average, participants had stigmas on three of the eight items, and 62.6% had a high stigma score. The most prevalent stigmas were as follows: COVID-19 is a punishment from God (79.3%), patients with previous COVID-19 must be isolated (67.3%), and people infected with COVID-19 did not meet hygiene standards (63.9%). Participants who lived in rural areas (β: 0.67, 95% CI: 0.39 to 0.95) and who perceived needing additional care during the pandemic (β: 0.35, 95% CI: 0.09 to 0.60) had a higher average stigma score, whereas stigma scores were lower among unemployed/retired participants (β: −0.22, 95% CI: −0.45 to 0.00). The study findings suggest implementing interventions to raise awareness through appropriate health literacy interventions and mass media campaigns