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This paper reports on an ultra-wideband low-noise distributed amplifier (LNDA) in a transferred-substrate InP double heterojunction bipolar transistor (DHBT) technology which exhibits a uniform low-noise characteristic over a large frequency range. To obtain very high bandwidth, a distributed architecture has been chosen with cascode unit gain cells. Each unit cell consists of two cascode-connected transistors with 500 nm emitter length and ft/fmax of ~360/492 GHz, respectively. Due to optimum line-impedance matching, low common-base transistor capacitance, and low collector-current operation, the circuit exhibits a low-noise figure (NF) over a broad frequency range. A 3-dB bandwidth from 40 to 185 GHz is measured, with an NF of 8 dB within the frequency range between 75 and 105 GHz. Moreover, this circuit demonstrates the widest 3-dB bandwidth operation among all reported single-stage amplifiers with a cascode configuration. Additionally, this work has proposed that the noise sources of the InP DHBTs are largely uncorrelated. As a result, a reliable prediction can be done for the NF of ultra-wideband circuits beyond the frequency range of the measurement equipment.
Lung surfactant (LS), a thin layer of phospholipids and proteins inside the alveolus of the lung is the first biological barrier to inhaled nanoparticles (NPs). LS stabilizes and protects the alveolus during its continuous compression and expansion by fine-tuning the surface tension at the air-water interface. Previous modelling studies have reported the biophysical function of LS monolayer and its role, but many open questions regarding the consequences and interactions of airborne nano-sized particles with LS monolayer remain. In spite of gold nanoparticles (AuNPs) having a paramount role in biomedical applications, the understanding of the interactions between bare AuNPs (as pollutants) and LS monolayer components still unresolved. Continuous inhalation of NPs increases the possibility of lung ageing, reducing the normal lung functioning and promoting lung malfunction, and may induce serious lung diseases such as asthma, lung cancer, acute respiratory distress syndrome, and more. Different medical studies have shown that AuNPs can disrupt the routine lung functions of gold miners and promote respiratory diseases. In this work, coarse-grained molecular dynamics simulations are performed to gain an understanding of the interactions between bare AuNPs and LS monolayer components at the nanoscale. Different surface tensions of the monolayer are used to mimic the biological process of breathing (inhalation and exhalation). It is found that the NP affects the structure and packing of the lipids by disordering lipid tails. Overall, the analysed results suggest that bare AuNPs impede the normal biophysical function of the lung, a finding that has beneficial consequences to the potential development of treatments of various respiratory diseases.
Cuprous oxide (Cu2O) thin films have been grown on both soda lime glass (SLG) microscope slides and Fluorine-doped Tin Oxide (FTO) substrates by a modified SILAR technique. The pH level of the bath solution was systematically varied in the range of 4.50 – 7.95 to elucidate their effect on the physical properties of the deposited product. The prepared films showed compact surface morphology composed of spherical grains evident from their SEM images. The XRD measurement showed that the as-deposited films were single phase Cu2O with (111) preferred orientation and this texturing was found to be increasing with increasing pH and annealing temperature. The annealed Cu2O films were found to be stable up to 200 °C and completely converted to cupric oxide (CuO) phases when the temperature reached to 350 °C. The estimated optical bandgaps of the as-grown samples were found in the range of 2.28 – 2.48 eV using UV-Vis-NIR transmission data and showing a bandgap narrowing trend with the decreasing level of solution pH. The effect of post-annealing temperatures (75-350 0C) on the as-deposited films was also studied and found to be crucial to control the optical bandgap (1.44 – 2.13) eV and electrical properties of the films. The sheet resistance of the as-deposited samples was found to be decreasing from 4120 MΩ/square to 800 MΩ/square while grown with increasing acetic acid content in the precursor solutions and decreasing up to 2.66 MΩ/square while annealing up to 250 °C in the air.
The objective of the study was to investigate the seasonal variations in proximate and fatty acid composition of wild sobaity (Sparidentex hasta) for a one-year period during (i) pre-spawning (October–December), (ii) spawning (January–March), (iii) post-spawning (April–June) and summer (July–September). Five male and five female fish were collected from market each month and used for the study. Skinless fillets from both sides of sobaity were taken, chopped, minced, frozen and freeze dried. Freeze-dried ground male and female fish samples were pooled separately and homogenized for proximate composition and fatty acid analysis. The results of the investigation showed that the muscle proximate composition and fatty acid profile of sobaity differed significantly (P < 0.05) among different seasons with the highest muscle lipid during the pre-spawning and spawning season. Palmitic acid (C16:0) was the most dominant muscle fatty acid followed by oleic acid (C18:1n-9). The muscle docosahexaenoic acid (DHA, C22:6n-3) levels in pre-spawning and spawning seasons were significantly (P < 0.05) higher than those in other seasons. A good n-3/n-6 ratio (2.26–3.11) and the higher DHA levels (10.16–11.47%) observed in muscles during the pre-spawning and spawning season indicated a better nutritional value of sobaity at this time of the year.
The Eastern Gangetic Plain is among the world's most intensively farmed regions, where rainfed and irrigated agriculture coexist. While the region and especially Bangladesh is a major producer of rice (Oryza sativa L. ssp. indica), there is potential to further develop sustainable rice production systems. Specifically, there is scope to include a replacement crop for the short fallow between rice crops in the dominant cropping pattern of rainfed monsoon rice harvest followed by irrigated spring rice. The aim of the current research was to identify a suitable cool-season legume crop – pea (Pisum sativum L.) or lentil (Lens culinaris Medik. ssp. culinaris) – that could be grown in the brief period between rice crops. The study comprised four crop sequence experiments comparing legume cultivars differing in maturity grown in between both long and short duration rice cultivars. These experiments were done at the Bangladesh Rice Research Institute regional station at Rajshahi over three cropping cycles. This was followed by an evaluation of pea vs. fallow between rice crops on three farmers’ fields in one cropping cycle. Here it is demonstrated that green pod vegetable pea is one of the best options to intensify the rainfed monsoon rice–fallow–spring irrigated rice cropping system, notwithstanding other remunerative rabi cropping options that could displace boro rice. The inclusion of an extra crop, pea as green pod vegetable, increased farm productivity by 1·4-fold over the dominant cropping sequence (rice–fallow–rice) and farm net income by fourfold. The study highlighted the advantages in total system productivity and monetary return of crop intensification with the inclusion of a pea crop between successive rice crops instead of a fallow period.
The aim of this study was to investigate the socioeconomic and demographic factors influencing the body mass index (BMI) of non-pregnant married Bangladeshi women of reproductive age. Secondary (Hierarchy) data from the 2011 Bangladesh Demographic and Health Survey, collected using two-stage stratified cluster sampling, were used. Two-level linear regression analysis was performed to remove the cluster effect of the variables. The mean BMI of married non-pregnant Bangladeshi women was 21.60±3.86 kg/m2, and the prevalence of underweight, overweight and obesity was 22.8%, 14.9% and 3.2%, respectively. After removing the cluster effect, age and age at first marriage were found to be positively (p<0.01) related with BMI. Number of children was negatively related with women’s BMI. Lower BMI was especially found among women from rural areas and poor families, with an uneducated husband, with no television at home and who were currently breast-feeding. Age, total children ever born, age at first marriage, type of residence, education level, level of husband’s education, wealth index, having a television at home and practising breast-feeding were found to be important predictors for the BMI of married Bangladeshi non-pregnant women of reproductive age. This information could be used to identify sections of the Bangladeshi population that require special attention, and to develop more effective strategies to resolve the problem of malnutrition.
We conducted a longitudinal assessment in 466 underweight and 446 normal-weight children aged 6–24 months living in the urban slum of Dhaka, Bangladesh to determine the association between vitamin D and other micronutrient status with upper respiratory tract infection (URI) and acute lower respiratory infection (ALRI). Incidence rate ratios of URI and ALRI were estimated using multivariable generalized estimating equations. Our results indicate that underweight children with insufficient and deficient vitamin D status were associated with 20% and 23–25% reduced risk of URI, respectively, compared to children with sufficient status. Underweight children, those with serum retinol deficiency were at 1·8 [95% confidence interval (CI) 1·4–2·4] times higher risk of ALRI than those with retinol sufficiency. In normal-weight children there were no significant differences between different vitamin D status and the incidence of URI and ALRI. However, normal-weight children with zinc insufficiency and those that were serum retinol deficient had 1·2 (95% CI 1·0–1·5) times higher risk of URI and 1·9 (95% CI 1·4–2·6) times higher risk of ALRI, respectively. Thus, our results should encourage efforts to increase the intake of retinol-enriched food or supplementation in this population. However, the mechanisms through which vitamin D exerts beneficial effects on the incidence of childhood respiratory tract infection still needs further research.
Magnetic core shell nanoparticles (NPs) have potential for applications in magnetic random access memory, spintronic devices, and drug delivery systems. Our investigations are focused on the synthesis of inverted core shell nanoparticles and characterization of their structural and magnetic properties. By using our hydrothermal nanophase epitaxy technique, we are able to synthesize well-ordered α-Cr2O3@α-MxCr2-xO3 (M = Co, Ni, Mn, Fe) inverted core-shell nanoparticles. This typically results in the formation of novel phases of MxCr2-xO3 shells having ferromagnetic/ferrimagnetic (FM/FiM) spin ordering and an antiferromagnetic (AFM) Cr2O3 core structure. The combined results from XRD and high-resolution TEM (HRTEM) provide evidence of the presence of corundum phase both in the shell and in the core regions. HRTEM results also show a sharp interface exhibiting epitaxial atomic registry of shell atoms over highly ordered core atoms whereas TEM-EDX analyses show that the M atoms reside predominantly in the shell regions. The XPS analyses of the NPs indicate the M transition metals incorporated in the shell are in the +2 oxidation state. Magnetic measurements show well developed hysteresis loops: The field cooled hysteresis loops reveal horizontal shifts in the applied field axis and vertical shifts in the magnetization axis, relative to the zero-field cooled hysteresis loops. This provides direct evidence for the exchange bias effect between the AFM α-Cr2O3 core and the FM/FiM α-MxCr2-xO3 shell. The XPS data are consistent with oxygen vacancy formation in order to maintain charge neutrality upon substitution of the M2+ ion for the Cr3+ ion in the α-MxCr2-xO3 shell. The FM/FiM ordering in the shell may at least partially result from the F-center exchange coupling between the oxygen-vacancy induced bound magnetic polaron and nearby cations.
Drinking raw date palm sap is the primary route of Nipah virus (NiV) transmission from bats to people in Bangladesh; subsequent person-to-person transmission is common. During December 2010 to March 2011, we investigated NiV epidemiology by interviewing cases using structured questionnaires, in-depth interviews, and group discussions to collect clinical and exposure histories. We conducted a case-control study to identify risk factors for transmission. We identified 43 cases; 23 were laboratory-confirmed and 20 probable. Thirty-eight (88%) cases died. Drinking raw date palm sap and contact with an infected person were major risk factors; one healthcare worker was infected and for another case transmission apparently occurred through contact with a corpse. In absence of these risk factors, apparent routes of transmission included drinking fermented date palm sap. For the first time, a case was detected in eastern Bangladesh. Identification of new epidemiological characteristics emphasizes the importance of continued NiV surveillance and case investigation.
This paper explores the utility of cluster- and case-based surveillance established in government hospitals in Bangladesh to detect Nipah virus, a stage III zoonotic pathogen. Physicians listed meningo-encephalitis cases in the 10 surveillance hospitals and identified a cluster when ⩾2 cases who lived within 30 min walking distance of one another developed symptoms within 3 weeks of each other. Physicians collected blood samples from the clustered cases. As part of case-based surveillance, blood was collected from all listed meningo-encephalitis cases in three hospitals during the Nipah season (January–March). An investigation team visited clustered cases’ communities to collect epidemiological information and blood from the living cases. We tested serum using Nipah-specific IgM ELISA. Up to September 2011, in 5887 listed cases, we identified 62 clusters comprising 176 encephalitis cases. We collected blood from 127 of these cases. In 10 clusters, we identified a total of 62 Nipah cases: 18 laboratory-confirmed and 34 probable. We identified person-to-person transmission of Nipah virus in four clusters. From case-based surveillance, we identified 23 (4%) Nipah cases. Faced with thousands of encephalitis cases, integrated cluster surveillance allows targeted deployment of investigative resources to detect outbreaks by stage III zoonotic pathogens in resource-limited settings.
Solar radiation assisted mixed convection boundary layer flow of Newtonian fluid along a non- reflecting, non-absorbing and ideally transparent semi-infinite vertical plate is studied here. Beer's law is used to express the solar radiation term. It is convenient to transform the non-linear dimensionless parabolic partial differential equations into (i) primitive variable formulation (PVF) and (ii) stream function formulation (SFF) before applying the numerical schemes. Coupled equations thus obtained from PVF are integrated numerically through implicit finite difference method together with the Gaussian elimination technique whereas block tridiagonal Keller-box technique is adopted to simulate the system of equations obtained from SFF. Numerical results from these two methods are also compared graphically in order to test the validation of the two schemes. However, due to less computation time and accuracy numeric results of shear stress, local Nusselt number coefficient, velocity and temperature profiles are obtained via SFF. It is found that velocity as well as temperature of the non-absorbing fluid enhances owing to the increase in solar radiation parameter.
We sought to examine the factors associated with bacteraemia and their outcome in children with pneumonia and severe acute malnutrition (SAM). All SAM children of either sex, aged 0–59 months, admitted to the Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh with radiologically confirmed pneumonia from April 2011 to July 2012 were enrolled (n = 405). Comparison was made between pneumonic SAM children with (cases = 18), and without (controls = 387) bacteraemia. The death rate was significantly higher in cases than controls (28% vs. 8%, P < 0·01). In logistic regression analysis, after adjusting for potential confounders, the SAM children with pneumonia and bacteraemia more often had a history of lack of bacillus Calmette-Guérin (BCG) vaccination (odds ratio 7·39, 95% confidence interval 1·67–32·73, P < 0·01). The results indicate the importance of continuation of BCG vaccination which may provide benefit beyond its primary purpose.
Early-life inorganic arsenic exposure influences not only child health and development but also health in later life. The adverse effects of arsenic may be mediated by epigenetic mechanisms, as there are indications that arsenic causes altered DNA methylation of cancer-related genes. The objective was to assess effects of arsenic on genome-wide DNA methylation in newborns. We studied 127 mothers and cord blood of their infants. Arsenic exposure in early and late pregnancy was assessed by concentrations of arsenic metabolites in maternal urine, measured by high performance liquid chromatography-inductively coupled plasma mass spectrometry. Genome-wide 5-methylcytosine methylation in mononuclear cells from cord blood was analyzed by Infinium HumanMethylation450K BeadChip. Urinary arsenic in early gestation was associated with cord blood DNA methylation (Kolmogorov–Smirnov test, P-value<10–15), with more pronounced effects in boys than in girls. In boys, 372 (74%) of the 500 top CpG sites showed lower methylation with increasing arsenic exposure (rS-values>−0.62), but in girls only 207 (41%) showed inverse correlation (rS-values>−0.54). Three CpG sites in boys (cg15255455, cg13659051 and cg17646418), but none in girls, were significantly correlated with arsenic after adjustment for multiple comparisons. The associations between arsenic and DNA methylation were robust in multivariable-adjusted linear regression models. Much weaker associations were observed with arsenic exposure in late compared with early gestation. Pathway analysis showed overrepresentation of affected cancer-related genes in boys, but not in girls. In conclusion, early prenatal arsenic exposure appears to decrease DNA methylation in boys. Associations between early exposure and DNA methylation might reflect interference with de novo DNA methylation.
Cytotoxicity study of magnetic nanomaterials is a key consideration for biomedical applications. Very little is known about the cytotoxic and anti-cancer effects of nickel nanowires (Ni NWs) on mammalian cells and their interaction with proliferating cancer cells. Current therapeutics do not address the full heterogeneity of pancreatic cancers due to the resistance to apoptosis and does not suffice for a successful treatment. Therefore, synthesis of novel anticancer drugs continues to be a potential topic for pancreatic cancer research. In this study, we have investigated the cellular toxicity and anti-cancer effects of Ni NWs in one of the most aggressive human pancreatic ductal cancer (Panc-1) cell lines with the objective of development of a potential treatment strategy. Ni NWs were fabricated in a custom-made setup utilizing the electrodeposition method. Elemental analysis, crystallographic structure, and morphological properties of the synthesized Ni NWs were investigated using Energy Dispersive X-ray Analysis (EDAX), X-Ray Diffraction (X-RD) and Scanning Electron Microscopy (SEM), respectively. Panc-1 cell cultures were maintained according to a slightly modified American Type Culture Collection (ATCC) protocol. Morphological apoptogenic characteristics assessment of the Ni NWs induced Panc-1 cell was accomplished using phase contrast microscopy (PCM). Two commercially available cytotoxicity procedures including 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) and trypan blue (TB) assays were utilized to determine the qualitative and quantitative cytotoxicity and anti-cancer effects of Ni NWs. As a negative control, Panc-1 cells without Ni NWs treatment were used in all experiments. Phase contrast microscopy (PCM) was used to confirm the Ni NWs internalization by Panc-1 cells. Both the MTT and TB assays, qualitatively and quantitatively confirmed the cytotoxic and anti-cancer effects of Ni NWs treated Panc-1 cells in vitro in both concentration and exposure-time dependent manners. We studied the cytotoxic and anti-cancer effects of Ni NWs on Panc-1 cells using novel integrated bionanotechnological approaches to understand the corresponding biological pathway with the objective of developing pancreatic cancer treatment. More specifically, we explored the molecular mechanisms associated with the pathway involved in Ni NWs induced toxicity against Panc-1 cells. Our results demonstrated that Ni NWs show strong candidacy for targeting cell selective applications in pancreatic cancer therapy. Key words: Nickel Nanowires, anti-cancer effects, pancreatic cancer.
Rabies is a major public health problem in Bangladesh, where most of the population live in rural areas. However, there is little epidemiological information on rabies in rural Bangladesh. This study was conducted in 30 upazilas (subdistricts) covering all six divisions of the country, to determine the levels of rabies and animal bites in Bangladesh. The total population of these upazilas was 6 992 302. A pretested questionnaire was used and data were collected by interviewing the adult members of families. We estimated that in Bangladesh, 166 590 [95% confidence interval (CI) 163 350–170 550] people per year are bitten by an animal. The annual incidence of rabies deaths in Bangladesh was estimated to be 1·40 (95% CI 1·05–1·78)/100 000 population. By extrapolating this, we estimated that 2100 (95% CI 1575–2670) people die annually from rabies in Bangladesh. More than three-quarters of rabies patients died at home. This community-based study provides new information on rabies epidemiology in Bangladesh.
Infectious diarrhoea caused by bacterial pathogens contributes to the high level of mortality in developing countries like Bangladesh. Following standard bacteriological procedures, a total of 14 428 bacterial pathogens were isolated from 56 132 stool samples and rectal swabs collected from diarrhoeal patients between 2005 and 2008. The rate of isolation and antimicrobial susceptibility data were retrospectively analysed for these isolates and among them Vibrio spp. (42·9%) were the most predominant, followed by Shigella spp. (20·3%), Aeromonas spp. (12·8%) and Salmonella spp. (6·4%). A decreasing trend in isolation of Vibrio spp. (P<0·001) and Salmonella spp. (P<0·001) was observed. While Vibrio cholerae isolates remained susceptible to ciprofloxacin, an increase in resistance was observed in Campylobacter spp. and Shigella flexneri. Variations in susceptibility to other tested antibiotics were observed among the isolated pathogens. Access to this current data will help in understanding the local burden of diarrhoeal disease and contribute to better design of prevention programmes.
The aim of this study was to determine the nationwide prevalence of smear-positive tuberculosis (TB) in Bangladesh. A multi-stage cluster survey of a random sample of persons aged ⩾15 years was included in 40 clusters (20 urban, 20 rural). Two sputum samples were collected from study participants and tested initially by fluorescence microscopy and confirmed by the Ziehl–Neelsen method. The crude and adjusted prevalence rates and 95% confidence intervals (CIs) were calculated using standard methods. A total of 33 new smear-positive TB cases were detected among 52 098 individuals who participated in the study. The average participation rate was over 80%. The overall crude prevalence of new smear-positive TB in persons aged ⩾15 years was estimated as 63·3/100 000 (95% CI 43·6–88·9) and the adjusted prevalence was 79·4/100 000 (95% CI 47·1–133·8). TB prevalence was higher in males (n=24) and in rural areas (n=20). The prevalence was highest in the 55–64 years age group (201/100 000) and lowest in 15–24 years age group (43·0/100 000). The prevalence was higher in persons with no education (138·6/100 000, 95% CI 78·4–245·0). The overall prevalence of smear-positive TB was significantly lower than the prevalence estimate of the previous nationwide survey in Bangladesh in 1987–1988 (870/100 000).
The imperfect quality of CdZnTe (CZT) crystals for radiation detectors seriously diminishes their suitability for different applications. Dislocations and other dislocation-related defects, such as sub-grain boundaries and dislocation fields around Te inclusions, engender significant charge losses and, consequently, cause fluctuations in the detector’s output signals, thereby hindering their spectroscopic responses. In this paper, we discuss our results from characterizing CZT material by using a high-spatial-resolution X-ray response mapping system at BNL’s National Synchrotron Light Source. In this paper, we emphasize the roles of these dislocation-related defects and their contributions in degrading the detector’s performance. Specifically, we compare the effects of the sub-grain- and coherent twin-boundaries on the X-ray response maps.
We investigated defects in CdZnTe crystals produced from various conditions and their impact on fabricated devices. In this study, we employed transmission and scanning transmission electron microscope (TEM and STEM), because defects at the nano-scale are not observed readily under an optical or infrared microscope, or by most other techniques. Our approach revealed several types of defects in the crystals, such as low-angle boundaries, dislocations and precipitates, which likely are major causes in degrading the electrical properties of CdZnTe devices, and eventually limiting their performance.
In this present work we report the growth of Cd0.9Zn0.1Te doped with In by a modified THM technique. It has been demonstrated that by controlling the microscopically flat growth interface, the size distribution and concentration of Te inclusions can be drastically reduced in the as-grown ingots. This results in as-grown detector-grade CZT by the THM technique. The three-dimensional size distribution and concentrations of Te inclusions/precipitations were studied. The size distributions of the Te precipitations/inclusions were observed to be below the 10-μm range with the total concentration less than 105 cm-3. The relatively low value of Te inclusions/precipitations results in excellent charge transport properties of our as-grown samples. The (μτ)e values for different as-grown samples varied between 6-20 x10-3 cm2/V. The as-grown samples also showed fairly good detector response with resolution of ∼1.5%, 2.7% and about 3.8% at 662 keV for quasi-hemispherical geometry for detector volumes of 0.18 cm3, 1 cm3 and 4.2 cm3, respectively.