| 1. |
- Amin, Nuhu, et al.
(författare)
-
Dependency of sanitation infrastructure on the discharge of faecal coliform and SARS-CoV-2 viral RNA in wastewater from COVID and non-COVID hospitals in Dhaka, Bangladesh
- 2023
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 867
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RNA in wastewater can be used as an indicator of the presence of SARS-CoV-2 infection in specific catchment areas. We conducted a hospital-based study to explore wastewater management in healthcare facilities and analyzed SARS-CoV-2 RNA in the hospital wastewater in Dhaka city during the Coronavirus disease (COVID-19) outbreak between September 2020-January 2021. We selected three COVID-hospitals, two non-COVID-hospitals, and one non-COVID-hospital with COVID wards, conducted spot-checks of the sanitation systems (i.e., toilets, drainage, and septic-tank), and collected 90 untreated wastewater effluent samples (68 from COVID and 22 from non-COVID hospitals). E. coli was detected using a membrane filtration technique and reported as colony forming unit (CFU). SARS-CoV-2 RNA was detected using the iTaq Universal Probes One-Step kit for RT-qPCR amplification of the SARS-CoV-2 ORF1ab and N gene targets and quantified for SARS-CoV-2 genome equivalent copies (GEC) per mL of sample. None of the six hospitals had a primary wastewater treatment facility; two COVID hospitals had functional septic tanks, and the rest of the hospitals had either broken onsite systems or no containment of wastewater. Overall, 100 % of wastewater samples were positive with a high concentration of E.coli (mean = 7.0 log10 CFU/100 mL). Overall, 67 % (60/90) samples were positive for SARS-CoV-2. The highest SARS-CoV-2 concentrations (median: 141 GEC/mL; range: 13-18,214) were detected in wastewater from COVID-hospitals, and in non-COVID-hospitals, the median SARS-CoV-2 concentration was 108 GEC/mL (range: 30-1829). Our results indicate that high concentrations of E. coli and SARS-CoV-2 were discharged through the hospital wastewa-ter (both COVID and non-COVID) without treatment into the ambient water bodies. Although there is no evidence for transmission of SARS-CoV-2 via wastewater, this study highlights the significant risk posed by wastewater from health care facilities in Dhaka for the many other diseases that are spread via faecal oral route. Hospitals in low-income settings could function as sentinel sites to monitor outbreaks through wastewater-based epidemiological surveillance systems. Hospitals should aim to adopt the appropriate wastewater treatment technologies to reduce the discharge of pathogens into the environment and mitigate environmental exposures.
|
|
| 2. |
|
|
| 3. |
- Haque, Rehnuma, et al.
(författare)
-
Monitoring SARS-CoV-2 variants in wastewater of Dhaka City, Bangladesh : approach to complement public health surveillance systems
- 2023
-
Ingår i: Human Genomics. - : Springer Nature. - 1473-9542 .- 1479-7364. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundWastewater-based epidemiological surveillance has been considered a powerful tool for early detection and monitoring of the dynamics of SARS-CoV-2 and its lineages circulating in a community. This study is aimed to investigate the complexity of SARS-CoV-2 infection dynamics in Dhaka city by examining its genetic variants in wastewater. Also, the study seeks to determine a connection between the SARS-CoV-2 variations detected in clinical testing and those found in wastewater samples.ResultsOut of 504 samples tested in RT-qPCR, 185 (36.7%) tested positive for SARS-CoV-2 viral RNA. The median log10 concentration of SARS-CoV-2 N gene copies/Liter of wastewater (gc/L) was 5.2, and the median log10 concentration of ORF1ab was 4.9. To further reveal the genetic diversity of SARS-CoV-2, ten samples with ORF1ab real-time RT-PCR cycle threshold (Ct) values ranging from 28.78 to 32.13 were subjected to whole genome sequencing using nanopore technology. According to clade classification, sequences from wastewater samples were grouped into 4 clades: 20A, 20B, 21A, 21J, and the Pango lineage, B.1, B.1.1, B.1.1.25, and B.1.617.2, with coverage ranging from 94.2 to 99.8%. Of them, 70% belonged to clade 20B, followed by 10% to clade 20A, 21A, and 21J. Lineage B.1.1.25 was predominant in Bangladesh and phylogenetically related to the sequences from India, the USA, Canada, the UK, and Italy. The Delta variant (B.1.617.2) was first identified in clinical samples at the beginning of May 2021. In contrast, we found that it was circulating in the community and was detected in wastewater in September 2020.ConclusionEnvironmental surveillance is useful for monitoring temporal and spatial trends of existing and emerging infectious diseases and supports evidence-based public health measures. The findings of this study supported the use of wastewater-based epidemiology and provided the baseline data for the dynamics of SARS-CoV-2 variants in the wastewater environment in Dhaka, Bangladesh.
|
|
| 4. |
|
|
| 5. |
- Haque, Rehnuma, et al.
(författare)
-
Wastewater surveillance of SARS-CoV-2 in Bangladesh : Opportunities and challenges
- 2022
-
Ingår i: CURRENT OPINION IN ENVIRONMENTAL SCIENCE & HEALTH. - : Elsevier BV. - 2468-5844. ; 27, s. 100334-
-
Tidskriftsartikel (refereegranskat)abstract
- The ongoing pandemic of the coronavirus disease 2019 (COVID-19) is a public health crisis of global concern. The progression of the COVID-19 pandemic has been monitored in the first place by testing symptomatic individuals for SARS-CoV-2 virus in the respiratory samples. Concurrently, wastewater carries feces, urine, and sputum that potentially contains SARS-CoV-2 intact virus or partially damaged viral genetic materials excreted by infected individuals. This brings significant opportunities for understanding the infection dynamics by environmental surveillance. It has advantages for the country, especially in densely populated areas where individual clinical testing is difficult. However, there are several challenges including: 1) establishing a sampling plan and schedule that is representative of the various catchment populations 2) development and validation of standardized protocols for the laboratory analysis 3) understanding hydraulic flows and virus transport in complex wastewater drainage systems and 4) collaborative efforts from government agencies, NGOs, public health units and academia.
|
|
| 6. |
- Rahman, Mohammad Ziaur, et al.
(författare)
-
How to Make a Most Stable Perovskite Solar Cell
- 2019
-
Ingår i: Matter. - : Elsevier BV. - 2590-2393 .- 2590-2385. ; 1:3, s. 562-564
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Perovskites have emerged as one of the hottest solar cell materials in the recent years, evident by more than 6,000 publications in 2018. Although intense research efforts on perovskite materials have made a significant progress in understanding its fundamental physicochemical properties, a long-term stability of perovskite solar cells (PSC) under operating conditions remains elusive. This article previews the recent findings on most stable PSC to date. Notably, an integrated effort of collaborative research has presented a simple but broadly applicable method to enhance the long-term operational stability of perovskite solar cells (over 1800 h at 70-75°C) under continuous simulated full-spectrum sunlight, which is up to ten times more stable than previous most stable devices.
|
|
| 7. |
- Rahman, Mohammad Ziaur, et al.
(författare)
-
Metal-free photocatalysts for hydrogen evolution
- 2020
-
Ingår i: Chemical Society Reviews. - : ROYAL SOC CHEMISTRY. - 0306-0012 .- 1460-4744. ; 49:6, s. 1887-1931
-
Forskningsöversikt (refereegranskat)abstract
- This review focuses on the discussion of the latest progress and remaining challenges in selected metal-free photocatalysts for hydrogen production. The scope of this review is limited to the metal-free elemental photocatalysts (i.e. B, C, P, S, Si, Se etc.), binary photocatalysts (i.e. BC3, B4C, CxNy, h-BN etc.) and their heterojunction, ternary photocatalysts (i.e. BCN) and their heterojunction, and different types of organic photocatalysts (i.e. linear, covalent organic frameworks, microporous polymer, covalent triazine frameworks etc.) and their heterostructures. Following a succinct depiction of the latest progress in hydrogen evolution on these photocatalysts, discussion has been extended to the potential strategies that are deemed necessary to attain high quantum efficiency and high solar-to-hydrogen (STH) conversion efficiency. Issues with reproducibility and the disputes in reporting the hydrogen evolution rate have been also discussed with recommendations to overcome them. A few key factors are highlighted that may facilitate the scalability of the photocatalyst from microscale to macroscale production in meeting the targeted 10% STH. This review is concluded with additional perspectives regarding future research in fundamental materials aspects of high efficiency photocatalysts followed by six open questions that may need to be resolved by forming a global hydrogen taskforce in order to translate bench-top research into large-scale production of hydrogen.
|
|
| 8. |
- Rahman, Mohammad Ziaur, et al.
(författare)
-
On the Mechanistic Understanding of Photovoltage Loss in Iron Pyrite Solar Cells
- 2020
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32:26
-
Tidskriftsartikel (refereegranskat)abstract
- Considering the natural abundance, the optoelectronic properties, and the electricity production cost, iron pyrite (FeS2) has a strong appeal as a solar cell material. The maximum conversion efficiency of FeS2 solar cells demonstrated to date, however, is below 3%, which is significantly below the theoretical efficiency limit of 25%. This poor conversion efficiency is mainly the result of the poor photovoltage, which has never exceeded 0.2 V with a device having appreciable photocurrent. Several studies have explored the origin of the low photovoltage in FeS2 solar cells, and have improved understanding of the photovoltage loss mechanisms. Fermi level pinning, surface inversion, ionization of bulk donor states, and photocarrier loss have been suggested as the underlying reasons for the photovoltage loss in FeS2. Given the past and more recent scientific data, together with contradictory results to some extent, it is timely to discuss these mechanisms to give an updated view of the present status and remaining challenges. Herein, the current understanding of the origin of low photovoltage in FeS2 solar cells is critically reviewed, preceded by a succinct discussion on the electronic structure and optoelectronic properties. Finally, suggestions of a few research directions are also presented.
|
|
| 9. |
- Rahman, Mohammad Ziaur, et al.
(författare)
-
Rational design and resolution of the mystery of the structure of Cyclo[18]carbon
- 2020
-
Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 8:17, s. 8234-8237
-
Tidskriftsartikel (refereegranskat)abstract
- C-18 is a cyclo[18]carbon that consists of 18 carbon atoms. Beyond the detection of an intermediate gas phase species, the synthesis of a solid-state C-18 and elucidation of its bonding structure have remained significant scientific challenges over the past half century. Until recently, this unorthodox carbon allotrope was conceptually feasible, while experimentally elusive in the solid state. Finally, this carbon allotrope has made its long-awaited debut when a collaborative research effort successfully synthesized and revealed the structure of cyclocarbon. The long 50 years of waiting is now over with the unveiling of this new form of chemistry's most celebrated element. This article highlights the discovery of this new allotrope from the carbon family, and discusses its chemical structure, potential applications, and challenges for future research.
|
|
| 10. |
- Rahman, Mohammad Ziaur, et al.
(författare)
-
X-ray diffraction and Raman spectroscopy for lead halide perovskites
- 2019. - 1
-
Ingår i: Characterization Techniques for Perovskite Solar Cell Materials. - Amsterdam : Elsevier. - 012814727X - 9780128147276 ; , s. 23-47
-
Bokkapitel (refereegranskat)abstract
- Lead halide perovskites (LHPs) have recently emerged as promising materials for solar energy conversions. Here, the underlying optoelectronic properties, charge transport abilities, energy level positions for alignment of contact materials, and the stability of LHPs are all dependence on the material composition and structure. Therefore, understanding the structure-to-property relationships is crucial from both a fundamental perspective as well as for constructing efficient and stable devices based on LHPs. XRD is a century old powerful tool to extract the structure of crystalline materials. It provides means to quantify atomic level distances, extraction of symmetries, densities, compositional and temperature dependent phase transitions as well as orientation and size of crystallites in polycrystalline films. Raman spectroscopy is a versatile characterization technique that provides information about the chemical composition and phases in crystalline materials, as well as the local vibration found in amorphous structures, molecular materials, solvents, and gases. With this knowledge, one can extract chemical identities via observed vibrations, bonding interactions, orientations, symmetries, local and lattice vibrations in a crystalline materials. In this contribution, we succinctly discuss the latest progress in understanding the physical properties of LHPs using XRD and Raman Spectroscopy.
|
|
