Chemical Lithography with Monomolecular Templates

Motivation für diese Arbeit was die Entwicklung einer neuen Präparationsmethode, um eine Einzelstrang-DNA (engl.: single stranded DNA, ssDNA ) innerhalb eines biokompatiblen Templats zu immobilisieren und zudem ssDNA-Muster beliebiger Form und Größe herzustellen. Als Ansatz wurde eine strahlungsinduzierte Austauschreaktion (engl.: irradiation promoted exchange reaction, IPER) im Rahmen des konzepts der Chemischen Lithographie verwendet. IPER ermöglicht es mittels Elektronenbestrahlung, das Ausmaß der Austauschreaktion zwischen einer primären, das Substrat bedeckenden selbstorganisierten Monoschicht (engl.: self-assembled monolayer, SAM ) und einem molekularen Substituent je nach Dosis zu steuern. Physikalisch bedeutet IPER die Erzeugung von chemischen und strukturellen Defekten in dem primären SAM, die die Austauschreaktion fördern. Im dieser Arbeit wurde der IPER Ansatz auf eine kontrollierte und ortsspezifische Immobilisierung von ssDNA auf Au(111)-Substraten erweitert. Um eine unspezifische Adsorption außerhalb der ssDNA bedeckten Bereiche zu verhindern, wurde als Ausgangsmatrix eine biokompatible Oligoethylenglykol-substituierte Alkanthiol (OEG-AT) Monolage verwendet. Im ersten Abschnitt wurden thiol-terminierte ssDNA als Substituenten eingesetzt. IPER mit diesen Substituenten und einem OEG-AT-SAM als Vorlage führten zu homogen gemischten ssDNA/OEG-AT Filmen der gewünschten Zusammensetzung, die anhand der eingestellten Dosis angepasst werden konnte. Basierend auf diesen Ergebnissen wurde IPER mit Elektronenstrahllithographie (EBL) verwendet, was die Herstellung komplexer ssDNA-Muster mit der gewünschten Form und Nanometergröße (bis zu 25-50 nm) innerhalb der biokompatiblen Matrix erlaubte. Diese Muster wurden dann als Vorlagen für die oberflächeninitiierte, enzymatische Polymerisation (SIEP) eingesetzt, was die Präparation von komplexen, räumlichen ssDNA Bürsten erlaubte. Ausgehend von den genannten Ergebnissen wurde die Möglichkeit überprüft, IPER mit kommerziell verfügbaren ssDNA-Disulfid Substituenten durchzuführen. Zunächst wurde eine Studie unter Verwendung eines Referenzfilms aus einem nicht-substituierten AT auf Gold und einem symmetrischen COOH-substituierten Dialkyldisulfid als Substituent durchgeführt. Dabei wurde festgestellt, dass IPER mit Disulfid-Substituenten in der gleichen Weise wie mit Thiolen durchgeführt werden kann. Es konnte gezeigt werden, dass die Kinetik der Austauschreaktion in beiden Fällen ähnlich ist, wenn auch das Ausmaß der Reaktion bei den Disulfiden geringer war. Dennoch konnten gemischten SAMs mit einer Konzentration der substituenten Spezies von bis zu 60% hergestellt werden. Basierend auf diesen Ergebnissen wurde die Möglichkeit verschiedener symmetrischer wie asymmetrischer ssDNA-Disulfide als Substituenten für IPER untersucht, wobei beide Systeme sich als geeignet für die IPER erwiesen. Die asymmetrischen Disulfide zeigten ähnlich hohe Wirkungsgrade, während die Effizienz der symmetrischen Disulfide insbesondere bei niedrigen Bestrahlungsdosen (< 0,6 mC/cm² ) deutlich niedriger war. Die Verwendung von IPER erfordert Hochvakuum und im Fall komplexer Strukturierung aufwändige Versuchsaufbauten wie Rasterelektronenmikroskop. Daher wurde in einem weiteren Abschnitt UV-Licht als Initiator für die Austauschreaktion zwischen der primären OEG-AT Matrix und den ssDNA Substituenten eingesetzt. UV-Licht wurde zur homogenen und lithographischen Strukturierung, zur Herstellung gemischter ssDNA/OEG-AT Filme und ssDNA Muster eingebetten in eine biokompatible OEG-AT Matrix verwendet. Auch hierbei konnte die Zusammensetzung der gemischten Filme durch die Wahl der Dosis eingestellt werden. Es wurde auch gezeigt, dass das UV-Licht unterschiedlicher Wellenlängen (254 oder 365 nm) neue Möglichkeiten für die Lithographie eröffnet. Zuletzt wurde eines der Systeme, ssDNA Polymerbürsten gekoppelt an ein monomolekulares ssDNA Templat, im Rahmen dieser Arbeit detailliert untersucht. Eine Kombination von mehreren komplementären spektroskopische Techniken wurde verwendet, um die chemische Integrität, Reinheit und molekulare Ausrichtung dieser mittels SIEP hergestellten Objekte zu untersuchen. Die Spektren der Polymerbürsten waren nahezu identisch mit denen der monomolekularen ssDNA Vorläufer und wiesen keine Spuren von Verunreinigungen auf. Neben der wohldefinierten chemischen Integrität und dem kontaminationsfreien Charakter, zeigten die Bürsten eine vergleichsweise hohe Orientierungsordnung, mit vorzugsweise aufrechter Ausrichtung der einzelnen Stränge. Die entwickelten Herstellungsmethoden beiten die Möglichkeit, ssDNA/OEG–AT Filme und Muster für die Bindung und den Nachweis der komplementär ssDNA Stränge sowie für die Erkennung von DNA-bindenden Proteinen zu präparieren, was unter anderem eine Grundlage für Sensorfabrikation bildet. Ferner dienen sie als vielseitige Plattform für Nanofabrikation, wie anhand der komplexen ssDNA Bürste in dieser Arbeit demonstriert wurde

A population-level data linkage study to explore the association between health facility level factors and unintended pregnancy in Bangladesh

The objective of this study was to investigate the effects of health facility-level factors, including the availability of long-acting modern contraceptives (LAMC) at the nearest health facility and its distance from women’s homes, on the occurrence of unintended pregnancy that resulted in a live birth. We analysed the 2017/18 Bangladesh Demographic and Health Survey data linked with the 2017 Bangladesh Health Facility Survey. The weighted sample comprised 5051 women of reproductive age, who had at least one live birth within 3 years of the survey. The outcome variable was women’s intention to conceive at their most recent pregnancy that ended with a live birth. The major explanatory variables were the health facility level factors. A multi-level multinomial logistic regression model was used to assess the association of the outcome variable with explanatory variables adjusting for individual, household, and community-level factors. Nearly 21% of the total respondents reported that their most recent live birth was unintended at conception. Better health facility management systems and health facility infrastructure were found to be 14–30% protective of unintended pregnancy that resulted in a live birth. LAMC availability at the nearest health facility was associated with a 31% reduction (95% CI 0.50–0.92) in the likelihood of an unwanted pregnancy that resulted in a live birth. Health facility readiness to provide LAMC was also associated with a 14–16% reduction in unintended pregnancies that ended with a birth. The likelihood of unintended pregnancy that resulted in a live birth increased around 20–22% with the increased distance of the nearest health facility providing LAMC from the women’s homes.The availability of health facilities near women’s homes and access to LAMC can significantly reduce unintended pregnancy. Policies and programs to ensure access and affordability of LAMC across current health facilities and to increase the number of health facilities are recommended

Effect of exclusive breastfeeding on selected adverse health and nutritional outcomes: a nationally representative study

Background: Despite growing evidence in support of exclusive breastfeeding (EBF) among infants in the first 6 months of birth, the debate over the optimal duration of EBF continues. This study examines the effect of termination of EBF during the first 2, 4 and 6 months of birth on a set of adverse health and nutritional outcomes of infants. Methods: Three waves of Bangladesh Demographic and Health Survey data were analysed using multivariate regression. The adverse health outcomes were: an episode of diarrhea, fever or acute respiratory infection (ARI) during the 2 weeks prior to the survey. Nutritional outcomes were assessed by stunting (height-for-age), wasting (weight-for-height) and underweight (weight-for-age). Population attributable fraction was calculated to estimate percentages of these six outcomes that could have been prevented by supplying EBF. Results: Fifty-six percent of infants were exclusively breastfed during the first 6 months. Lack of EBF increased the odds of diarrhea, fever and ARI. Among the babies aged 6 months or less 27.37% of diarrhea, 13.24% of fever and 8.94% of ARI could have been prevented if EBF was not discontinued. If EBF was terminated during 0-2 months, 2-4 months the odds of becoming underweight were 2.16 and 2.01 times higher, respectively, than babies for whom EBF was not terminated. Conclusion: Children who are not offered EBF up to 6 months of their birth may suffer from a range of infectious diseases and under-nutrition. Health promotion and other public health interventions should be enhanced to encourage EBF at least up to six-month of birth. Trail registration: Data of this study were collected following the guidelines of ICF International and Bangladesh Medical Research Council. The registration number of data collection is 132,989.0.000 and the data-request was registered on September 11, 2016

Editorial: COVID-19 and entrepreneurial mindset

[Extract] he entrepreneur’s importance is well-recognized in the economy, especially during critical times. The COVID-19 pandemic is already considered to be one of the biggest socio-economic crises in history. As it is ongoing and bringing many business-related uncertainties, it is very challenging to foresee its impact on the future. However, despite the challenges created, the COVID-19 pandemic also created entrepreneurial opportunities

COMPARISON OF EARLY OUTCOME OF AORTIC VALVE REPLACEMENT BETWEEN MINIMALLY INVASIVE CARDIAC SURGERY AND STANDARD MEDIAN STERNOTOMY

Background: Minimally invasive cardiac surgery (MICS) for aortic valve replacement (AVR) has gained attention due to its potential advantages over conventional sternotomy, including reduced surgical trauma, faster recovery, and lower complication rates. This study aimed to compare early postoperative outcomes between MICS and sternotomy in a Bangladeshi population. Methods: This comparative prospective cohort study included 30 patients who underwent AVR, with 15 undergoing MICS and 15 undergoing sternotomy at BSMMU, Dhaka, Bangladesh. Baseline characteristics, operative parameters, and early postoperative outcomes were analyzed. Statistical comparisons were performed using appropriate tests, with p &lt; 0.05 considered significant. Results: Baseline characteristics were comparable between groups. MICS had longer operative (180.5 ± 25.3 vs. 160.2 ± 20.1 min, p = 0.04) and cardiopulmonary bypass times (95.1 ± 14.6 vs. 85.7 ± 12.8 min, p = 0.05). However, MICS was associated with shorter ventilation time (6.2 ± 2.4 vs. 10.5 ± 3.1 hours, p = 0.02), ICU stay (48.3 ± 10.7 vs. 72.1 ± 15.2 hours, p = 0.01), and hospital stay (6.4 ± 1.2 vs. 10.2 ± 1.5 days, p &lt; 0.001). MICS patients had lower chest tube drainage (300 ± 85 vs. 450 ± 120 ml, p = 0.003), transfusion rates (20% vs. 53.3%, p = 0.04), and postoperative pain scores (3.1 ± 1.0 vs. 5.2 ± 1.3, p &lt; 0.001). Complication rates, including mortality, bleeding, atrial fibrillation, and acute kidney injury, were similar. Conclusion: MICS for AVR demonstrated superior early recovery outcomes compared to sternotomy, with shorter hospital stays, reduced pain, and lower blood loss, without increasing major complications. These findings support the broader adoption of MICS in appropriate patients

Phenotypic and Genotypic Characteristics of Antimicrobial Resistance in Citrobacter freundii Isolated from Domestic Ducks (Anas platyrhynchos domesticus) in Bangladesh

Antimicrobial resistance (AMR) in Citrobacter freundii poses a serious challenge as this species is one of the sources of nosocomial infection and causes diarrheal infections in humans. Ducks could be the potential source of multidrug-resistant (MDR) C. freundii; however, AMR profiles in C. freundii from non-human sources in Bangladesh have remained elusive. This study aimed to detect C. freundii in domestic ducks (Anas platyrhynchos domesticus) in Bangladesh and to determine their phenotypic and genotypic antibiotic susceptibility patterns. A total of 150 cloacal swabs of diseased domestic ducks were screened using culturing, staining, biochemical, polymerase chain reaction (PCR), and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) to detect C. freundii. Phenotypic and genotypic antibiotic susceptibility patterns were done by the disk diffusion method and PCR, respectively. In total, 16.67% (25/150) of the samples were positive for C. freundii. C. freundii isolates showed a range of 20% to 96% resistance to cefotaxime, gentamicin, levofloxacin, ciprofloxacin, cotrimoxazole, tetracycline, ampicillin, and cephalexin. More than 60% of the isolates were phenotypically MDR, and the index of multiple antibiotic resistance ranged from 0.07 to 0.79. Genes encoding resistance to beta-lactams [blaTEM-1-88% (22/25), blaCMY-2-56% (14/25), blaCMY-9-8% (2/25), and blaCTX-M-14-20% (5/25)], sulfonamides [sul1-52% (13/25), sul2-24% (6/25)], tetracyclines [tetA-32% (8/25) and tetB-4% (1/25)], aminoglycosides [aacC4-16% (4/25)], and fluoroquinolones [qnrA-4% (1/25), qnrB-12% (3/25), and qnrS-4% (1/25)] were detected in the isolated C. freundii. To the best of our knowledge, this is the first study in Bangladesh to detect MDR C. freundii with their associated resistance genes from duck samples. We suggest addressing the burden of diseases in ducks and humans and associated AMR issues using the One Health approach

Synthesis, Characterization and Bioactivities of Some Novel Oxovanadium(IV) Glycinato Complexes

The novel oxovanadium(IV) complexes, [VIVO(GlyH)(Gly)]+ClO4 - .H2O (1), [VIVO(GlyH)(Gly)]+NO3 - .H2O (2), [VIVO(GlyH)(Gly)]+CH3COO- .H2O (3) were synthesized and characterized by FT-IR, UV-Vis and 1H NMR spectroscopic measurements. The cumulative spectroscopic assessment envisaged that, the complexes adopt a square pyramidal structure, in which the two glycine ligands coordinate to vanadium(IV) center in bidentate fashions conforming a homoleptic structure. The amino nitrogen and a carboxylato oxygen atom coordinate the vanadium(IV) center from both sides making a five members chelate by each side. All the complexes are stable in amorphous state and in aerobic and anaerobic solution. Significantly, all the complexes have the antifungal activities against Aspergillus niger and Penicillium notatum but ineffective against Candida tropicalis. No antibacterial activity was observed for the complexes against tested bacteria and unfortunately, they were found cytotoxic against brine shrimp bioassay

Impacts of Aquaculture Extension on Pond Operators and the Rural Community

In 1990-1993 in Kapasia sub-district in central Bangladesh ICLARM introduced low-input aquaculture for pond owners to adapt into their farming systems. Impacts on production, fish consumption and markets were assessed in 1998-1999. The percentage of ponds stocked increased from 1990 to 1998, but did not differ significantly between past participants (increased from 61% to 90%), neighboring pond operators or a control area. In 1992 participants produced 2 t/ha compared with 0.5 t/ha in 1990. In 1997-1998 the previous participants produced significantly more 2.2 t/ha, compared with 1.6 t/ha for other pond operators in Kapasia and 1.3 t/ha in the control area (p<0.001, t-test). Non-participants learnt of aquaculture from neighbors or mass media. Total production from ponds in the project area in 1998 was 4.2 times greater than in 1990. Without that project, production would probably have gradually increased 2.8 times. Local fish markets were surveyed in 1991 and 1999. The volume of fish traded increased 8 times. Carp from local ponds now dominate trade. Consequently the real price of carp has fallen, while that of indigenous fish has increased. Detailed participatory monitoring revealed much higher fish consumption than recall data. Pond owning households consumed 211 kg per household in 1998-1999 (just under 90 g/person/day), about 25% came from their own ponds. Small fish purchased or caught in flooded fields were mainly consumed, pond fish were sold for income.Keywords: aquaculture, impact, consumption, market

Prevalence of, and risk factors for, diabetes and prediabetes in Bangladesh : Evidence from the national survey using a multilevel Poisson regression model with a robust variance

To estimate the age-standardized prevalence of diabetes and prediabetes and identify factors associated with these conditions at individual, household, and community levels. Data from 11952 Bangladeshi adults aged 18–95 years available from the most recent Bangladesh Demographic and Health Survey 2017–18 were used. Anthropometric measurements and fasting blood glucose samples were taken as part of the survey. Prevalence estimates of diabetes and prediabetes were age-standardized with direct standardization, and risk factors were identified using multilevel mix-effects Poisson regression models with robust variance. The overall age-standardised prevalence of diabetes was 9.2% (95%CI 8.7–9.7) (men: 8.8%, women: 9.6%), and prediabetes was 13.3% (95%CI 12.7–13.9) (men: 13.0%, women: 13.6%). Among people with diabetes, 61.5% were unaware that they had the condition. 35.2% took treatment regularly, and only 30.4% of them had controlled diabetes. Factors associated with an increased prevalence of having diabetes were increasing age, male, overweight/obesity, hypertension, being in the highest wealth quintile, and living in the Dhaka division. People currently employed and living in the Rangpur division were less likely to have diabetes than those currently not employed and living in the Barishal division. Diabetes and prediabetes affect a substantial proportion (over one-quarter) of the Bangladeshi adult population. Continuing surveillance and effective prevention and control measures, focusing on obesity reduction and hypertension management, are urgently needed

Impact of salinity changes on growth, oxygen consumption and expression pattern of selected candidate genes in the orange mud crab (Scylla olivacea)

Change in environmental salinity level is a major limiting factor for the aquaculture productivity because it imposes severe stress on organisms that in turn retards growth. The orange mud crab (Scylla olivacea) is an important coastal aquaculture species (farming is practised in 10‰–20‰ salinity levels) in Bangladesh. The present study was conducted to investigate the changes in growth, O2 consumption and mRNA expression levels of five selected genes in the orange mud crab (S. olivacea) exposed to three different experimental salinity levels (0‰, 10‰ and 20‰) for three months. Crabs reared at 10‰ and 20‰, showed significantly higher (p < .05) growth performance and expression of growth regulatory genes (Actin and α-amylase). The highest levels (p < .05) of O2 consumption and expression of ion regulatory genes (Na+-K+-ATPase, V-type H+-ATPase and Diuretic Hormone) were obtained at 0‰. Moderate levels of growth and expression of selected candidate genes were observed at 10‰ treatment while the highest levels of growth and gene expression were obtained at 20‰ (control salinity). Strong interactions were observed between growth performance and expression of growth genes (R2 = 0.81–0.91), and rate of O2 consumption and expression of ion regulatory genes (R2 = 0.83–0.93), implying that the selected genes are important candidates for growth and ionic balance in S. olivacea. Growth performance was found to be very low at 0‰ initially, after 30 days crabs showed better growth performance at this salinity level. It is thus inferred that orange mud crab individuals might require 3–5 days for acclimation to salinity stress but it can take at least 30 days for acclimation to regular growth. Results indicate that with proper acclimation, the orange mud crab (Scylla olivacea) can be farmed at low salinity conditions and possibly in freshwater condition