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Digital electronics course is one of the very fundamental courses for the students of undergraduate programme of electrical and electronic engineering (EEE) and the other undergraduate engineering disciplines. Therefore, "digital electronics" shall be taught effectively, so that students can apply the knowledge learned to solve their real-life engineering problems. A teacher needs to adopt new teaching methodologies to attract current generation of students, and thus, to prepare them with practical knowledge and skills. Skills in the cognitive domain of Bloom's taxonomy revolve around knowledge, comprehension and critical thinking of a particular topic. This makes teaching and learning more effective and efficient. In this paper, the teaching method of 'digital electronics' course for the undergraduate EEE students in the cognitive domain has been described with an example. Class performance evaluation in two different cohorts shows that the students' results improve after using this approach.Keywords: Bloom's taxonomy, cognitive domain, digital electronics course, teaching methods.

Background: Parathyroid dysfunction leading to symptomatic hypocalcemia is not uncommon following a total or completion thyroidectomy and is often associated with significant patient morbidity and a prolonged hospital stay. Objectives: To investigate whether postoperative parathyroid hormone level is a parameter to identify hypocalcaemia after total thyroidectomy. Methods: This prospective longitudinal study was carried out with variety of thyroid disorders with indication of total thyroidectomy at BSMMU. Total 103 patient were selected following the inclusion and exclusion criteria. The routine clinical assessment and the preoperative laboratory investigations of the study population were performed before operation. Preoperative and postoperative levels of serum PTH and serum calcium level were measured. Results: Immediate post-operative period 17(16.50%) patients PTH level were low (

Background: Nasogastric decompression in gastric surgery allows better surgical field and leads to reduction of postoperative complications. The placement of a NG tube can be uncomfortable for the patient, if the patient is not adequately prepared with anesthesia to the nasal passages. Some specific instructions need on how to cooperate with the operator during the procedure. Most surgeons traditionally continue to use nasogastric decompression, believing that its use facilitates a better surgical field and reduces complications such as nausea, vomiting, aspiration, and anastomotic leakage caused by postoperative ileus. Aim of the study: The aim of the study was to compare the postoperative outcome between the nasogastric tube Group (NG) and the non-nasogastric tube group (NNG). Methods: In this quasi-experimental study, we enrolled 60 patients as study population who had been surgically treated for malignant and benign diseases in the Department of General Surgery, Bangabandhu Sheikh Mujib Medical University, Bangladesh from April, 2017-March 2018. In total 30 patients (Group I) were randomized into the intubated group and the other 30 patients (Group II) were randomized into the tubeless group. All patients received epidural pain control. Preoperative serum albumin levels, postoperative complications, the passage of stools, mean time to first orally feeding, hospital stay, and cost of hospitalization were recorded. Statistical analysis of the results was done by SPSS version 22.0. Results: In this study, we found a significant correlation in time of the return of bowel sound, time of bowel movement, and time of oral resumption between the groups where the p values were 0.043, 0.004, and 0.045 respectively. The postoperative pulmonary complication was significantly higher in Group I than in Group II (33.3% versus 3.3%), but regarding the paralytic ileus, post-operative bleeding, anastomotic leakage, and wound dehiscence, no significant difference was observed .....

Background: Parathyroid dysfunction leading to symptomatic hypocalcemia is not uncommon following a total or completion thyroidectomy and is often associated with significant patient morbidity and a prolonged hospital stay. The current study is designed to evaluate the role of parathormone (PTH) levels detected in a standard time frame after total thyroidectomy as a predictor of post-thyroidectomy hypocalcemia. Objectives: To investigate whether postoperative parathyroid hormone level is a parameter to identify hypocalcemia after total thyroidectomy as well as to find out the optimum cut-off value of parathyroid hormone in early postoperative period. Methodology: This was a cross-sectional study. A total of 103 patients’ male-female with a variety of thyroid disorders with an indication of total thyroidectomy attended the outpatient department and inpatient department of Surgery and Otolaryngology, BSMMU. This study was carried out from March 2018 to September 2019. The routine clinical assessment and the preoperative laboratory investigations were performed before operation. Preoperative levels of serum PTH were measured. Statistical analysis was carried out using SPSS version.22.0. Results: The levels of PTH in the immediate postoperative period showed that 17(16.50%) patients belonged to low PTH (

Background: Helicobacter pylori (H. pylori) infection is the important cause of chronic gastritis which results in atrophy and metaplasia of the underlying mucosa. Both these conditions are known to be associated with an increased risk of gastric carcinoma. The role of H. pylori infection in the pathogenesis of gastric cancer is an important but unresolved issue. Aim of the study: The aim of this study was to assess the frequency of H. pylori inpatient with stomach cancer. Methods: This was a cross-sectional study conducted in the Department of General Surgery in Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka from October 2019 to September 2020. The data regarding clinical and surgical profiles was recorded. Serum IgG, endoscopic biopsy, or campylobacter-like organism test (CLO) was performed for diagnosis of H. pylori. All the information is recorded in the data collection sheet. Data were processed and analyzed by SPSS and Microsoft excel. Results: The study demonstrates that a maximum number of patients (42.6%) were between 51-60-year age group; the mean age of the patient was 49.35±11.7 years. Out of 100 patients, 76.4% were male and 23.6% were female. The male and female ratio was 3.25:1. The differentiation and classification of gastric cancer were assessed according to Lauren's classification. Tumors of the intestinal type constituted 42(61.7%) of the tumors and diffuse was noted in 26(38.3%) of the tumors. The prevalence of H. pylori infection was 47(69.1%). The prevalence was significantly higher in intestinal than in diffuse-type carcinoma. The difference was statistically significant (P

Background: For years, septal myectomy has been considered the best available treatment for hypertrophic cardiomyopathy. In Bangladesh, however, this technique is only nascent. We present a case series of septal myectomy with outcomes after 1 to 6 years at the National Heart Foundation Hospital & Research Institute. Methods: For this study, 21 patients who underwent septal myectomy from 2014 to 2019 were monitored retrospectively. Evidence was collected from the hospital database and followed up via telephone conversations using a structured questionnaire. Patients’ preoperative, postoperative, and follow-up clinical data were collected and analyzed. Results: The results reveal that after septal myectomy, there were significant improvements in terms of left ventricular outflow gradient (P ≤ .01), septal thickness (P ≤ .01), left ventricular ejection fraction (P = .001), pulmonary arterial systolic pressure (P ≤ .01), mitral regurgitation (P ≤ .01), systolic anterior motion (P ≤ .01), and New York Heart Association class (P ≤ .01). Conclusion: This study suggests that septal myectomy be offered to symptomatic hypertrophic obstructive cardiomyopathy patients, as its survival benefits and symptoms relief are excellent. This study suggests that septal myectomy that dynamic obstruction at the left ventricular outflow tract is the major hemodynamic problem. We hope that with appropriate measures, new myectomy programs in our country can provide extended longevity and restore the quality of life.

Carbon-rich biochar can be produced by pyrolysis of biomass. Depending on the precise production pathway, the surface chemistry and porosity can be tuned and made compatible for a defined application. This shear benefit has persuaded researcher to explore its suitability in various electrochemical applications related to energy storage and conversion. In this article, we succinctly discuss the potentials of biochar in electrocatalysis, fuel cell, supercapacitors, and rechargeable batteries. We have concluded this article with recommendations for future research.

This work evaluates the use of potassium hydroxide (KOH) and potassium oxalate monohydrate (K2C2O4•H2O) for the formation of nitrogen- and oxygen-doped porous carbons. Based on molar equivalent amo...

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.

Earth abundant iron pyrite (FeS2) has attracted considerable attention as a potential non-toxic absorber material in lieu of widely used but toxic and relatively rare Indium containing CIGS and CdTe for thin-film solar cells. Research in this regard has been progressed in understanding its fundamental electronic, optical and chemical properties, while its surface polarity is rarely been studied. In this contribution, we have investigated the adhesion of water to determine the wettability (i.e. hydrophilic or hydrophobic) of naturally grown FeS2, and thereof, the polarity of the surface. FeS2 has a cubic crystal structure that grows and cleaves along its cubic faces. Based on the measurements using Sessile drop method, we have found that the surfaces of the pyrite phase of FeS2 crystals are intrinsically super-hydrophilic and highly polar. Our finding is corroborated with X-ray diffraction, Fourier Transform Infrared, Raman Spectroscopy, particle size determination, and contact angle measurements of the pyrite phase. The surface polarity would be a critical factor for choosing surface passivation protocols and type of contact materials as well as for interpreting surface field effects in the system for solar cell application with material heterojunctions.

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.

Download : Download high-res image (160KB) Download : Download full-size image Dr. Mohammad Ziaur Rahman is an expert in low-dimensional materials synthesis, characterization, and application in solar energy conversion and storage. His current research is on making FeS2 a better solar cell material. Download : Download high-res image (174KB) Download : Download full-size image Professor Tomas Edvinsson is directing a research group that is working on low-dimensional materials for solar cells (FeS2, CIGS, DSSc, and perovskites) and photocatalysis. He is a principal investigator and project leader for several national projects from the Swedish Research Council, Swedish Energy Agency, and part of the Swedish node for a European H2020 project within solar fuels.

The research has been conducted to understand the training effectiveness where health professional participates for training who work under the Bangladesh Government. The research used the Kirkpatrick model. The paper has collected data form, 323 participants. The research measured the training effectiveness using survey questions. The multiple regression techniques have used to conduct analysis of the collected data. The findings of the research revealed that the training effectiveness has been affected significant positively by training motivation, trainer qualification, and training design. Moreover, the training environment does not have significant role on the impacting of the training effectiveness respectively. The study has specific recommendations based on the above findings as the bench mark to improve the effectiveness training in Bangladesh and the regions. DOI: https://doi.org/10.5281/zenodo.3380491

Photocatalytic solar fuel production, for example, production of hydrogen via water-splitting, is an effective means of chemical storage of solar energy and provides a potential option for achieving a zero-emissions energy system. Conveniently, hydrogen can be converted back to electricity either via fuel cells or through combustion in gas turbines, or it can be mixed in low concentrations with natural gas or biogas for combustion in existing power plants. The cornerstone of a practical solar fuel production process is a stable, efficient, and scalable photocatalyst (a semiconductor material that accommodates photon absorption, charge carrier generation and transport, and catalytic reactions). Therefore, the quest for suitable photocatalyst materials is an ongoing process. Recently, carbon nitride (CN) has attracted widespread interest as a metal-free, earth-abundant, and highly stable photocatalyst. However, the catalytic efficiency of CN is not satisfactory because of its poor charge transport attributes. There is a direct relation between the photocatalytic efficiency and charge transport because the basic principle of light-promoted overall photodecomposition of water into H

This work was intended to clarify if the dyeing treatment could modify the functional properties of white substrate as well as the surface finishing would alter the initial color of dyed textiles. Thus, in this work, a kind of surface coating was applied to modify the flame retardant and hydrophilic properties of both the undyed (white) and dyed polyamide 6.6 (PA6.6) textiles using some novel compounds like chitosan (CS), montmorillonite (MMT), sodium alginate (ALG) and phytic acid (PA) in a quadralayer (QL) or a hexalayer (HL) fashion. The obtained results revealed that the dyed fabric samples exhibited better flame retardancy and hydrophilicity compared to the undyed one; indicating the dyeing treatment contributed in improving the functional properties. For example, the 5HL-deposited dyed fabric sample (i.e., PA6.6-D-5HL) showed a maximum reduction in the peak heat release rate (pHRR) by 32% and the 7.5QL-deposited dyed fabric sample (i.e., PA6.6-D-7.5QL) brought a water contact angle (WCA) value of 0°. However, this kind of surface finishing caused a slight loss in depth of color for the dyed fabric samples.

In pursuit of inexpensive and earth abundant photocatalysts for solar hydrogen production from water, conjugated polymers have shown potential to be a viable alternative to widely used inorganic counterparts. The photocatalytic performance of polymeric photocatalysts, however, is very poor in comparison to that of inorganic photocatalysts. Most of the organic photocatalysts are active in hydrogen production only when a sacrificial electron donor (SED) is added into the solution, and their high performances often rely on presence of noble metal co‐catalyst (e.g. Pt). For pursuing a carbon neutral and cost‐effective green hydrogen production, unassisted hydrogen production solely from water is one of the critical requirements to translate a mere bench‐top research interest into the real world applications. Although this is a generic problem for both inorganic and organic types of photocatalysts, organic photocatalysts are mostly investigated in the half‐reaction, and have so far shown limited success in hydrogen production from overall water‐splitting. To make progress, this article exclusively discusses critical factors that are limiting the overall water‐splitting in organic photocatalysts. Additionally, we also have extended the discussion to issues related to stability, accurate reporting of the hydrogen production as well as challenges to be resolved to reach 10 % STH (solar‐to‐hydrogen) conversion efficiency., While half‐reactions using organic photocatalysts for hydrogen production are encouraging, systems with high efficiency without using sacrificing electron donors (SED) and showing full overall water‐splitting are still largely absent. Critical factors that are limiting the overall water‐splitting using organic photocatalysts are summarized, with a supplementary discussion on remaining challenges.

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.

Photocatalytic hydrogen production from water is a green and renewable path for solar fuel production. Hydrogen can be advantageously stored directly and burned without emission of deleterious CO and NOx gases. Photocatalysis therefore shows significant promise as a part solution to a sustainable and affordable energy supply in an era post-fossil fuels. Influenced by the Fujishima–Honda effect, significant advances in photocatalytic hydrogen production have occurred at the laboratory-scale. For wide adoption however, the photocatalysts will need to be made from earth-abundant materials, be stable and scalable from laboratory-to-large-scale, and have high conversion efficiency. In this regard, metal-free photocatalysts show practical promise in meeting these requirements. To foster research in materials design, here we critically review recent significant developments in metal-free photocatalysts consisting of carbon, nitrogen and phosphorus, and discuss how future large-scale hydrogen production via overall water-splitting could be accomplished economically.

We here introduce, for the first time, a topological carbon nitride (TCN) with built-in crystalline–amorphous phases. Topologically anchored dual complementary phases allow localized photon absorption of different wavelengths, and provide a twinned photocatalyst interface to facilitate geminate charge carrier pair separation. These unique attributes, which are absent in widely used graphitic carbon nitride (GCN) and amorphous carbon nitride (ACN) photocatalysts, are highly desirable for precious metal (i.e. Pt) cocatalyst-free hydrogen production via water-splitting. Our results are substantiated with both experiments and simulations.

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.

This contribution reports the synthesis, characterization and application of a new ternary homo-heterojunction photocatalyst for improved hydrogen production via water-splitting. The heterostructure is constructed by soft-grafting of graphitic carbon nitride (GCN) and graphene oxide (GO) into an amorphous carbon nitride (ACN) substrate. In this ternary hybrid, a cascaded redox-junction is formed that significantly facilitates the separation of photogenerated electron–hole pairs (EHPs), retards EHP recombination and shuttles electrons to the photocatalyst/liquid interface for proton reduction reactions. When deposited with 3 wt% Pt as a cocatalyst, this new photocatalyst exhibits hydrogen production of 251 μmol h−1 from 10 vol% aqueous triethanolamine solution under visible light (420 nm) irradiation with an apparent quantum efficiency of 6.3%. This ternary photocatalyst therefore outperforms stand-alone/binary photocatalysts and promises to be a viable alternative to metal-based photocatalysts.

Background In Bangladesh nomadic duck flocks are groups of domestic ducks reared for egg production that are moved to access feeding sites beyond their owners’ village boundaries and are housed overnight in portable enclosures in scavenging areas. The objectives of this study were to measure the prevalence of influenza A virus RNA and H5-specific antibodies in nomadic ducks and to characterize nomadic duck raising practices in northeastern Bangladesh. Methods We tested duck egg yolk specimens by competitive ELISA to detect antibodies against avian influenza A (H5) and environmental fecal samples by real time reverse transcription polymerase chain reaction (rRT-PCR) to detect influenza A virus RNA and H5 subtype. Results The median age of the ducks was 24 months (range: 8-36 months) and the median flock size was 300 ducks (range: 105-1,100). Of 1,860 egg yolk samples, 556 (30%, 95% confidence interval (CI): 28-32) were positive for antibodies against H5 and 58 flocks (94%) had at least one egg with H5 specific antibodies. Of 496 fecal samples, 121 (24%, 95% CI: 22-29) had detectable influenza A RNA. Thirty-three flocks (53%) had at least one fecal sample positive for influenza A RNA. Conclusions Nomadic ducks in Bangladesh are commonly infected with avian influenza A (H5) virus and may serve as a bridging host for transmission of avian influenza A (H5) virus or other avian influenza A viruses subtypes between wild waterfowl, backyard poultry, and humans in Bangladesh. This article is protected by copyright. All rights reserved.

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.

We describe here the metal-templated transformation of carbon nitride (C3N4) into nitrogen-containing carbons as anodes for Li-ion batteries (LIBs). Changing the template from the carbon- and nitrogen-immiscible Cu powder to the carbon- and nitrogen-miscible Fe powder yields different carbons; while Fe templating produces graphitized carbons of low (

The research has been conducted to understand the training effectiveness where health professional participates for training who work under the Bangladesh Government. The research used the Kirkpatrick model. The paper has collected data form, 323 participants. The research measured the training effectiveness using survey questions. The multiple regression techniques have used to conduct analysis of the collected data. The findings of the research revealed that the training effectiveness has been affected significant positively by training motivation, trainer qualification, and training design. Moreover, the training environment does not have significant role on the impacting of the training effectiveness respectively. The study has specific recommendations based on the above findings as the bench mark to improve the effectiveness training in Bangladesh and the regions.

Polymeric melon shows real promise to be a next generation photocatalyst material for solar hydrogen production. Because it is earth abundant, and highly stable in photoredox reactions. However, a long-standing problem with polymeric melon is that it is inactive for photocatalytic hydrogen evolution without a metal cocatalyst, such as Pt. Sluggish charge transfer kinetics and a high activation energy for proton reduction makes pristine melon overly dependent on a high loading of precious Pt-cocatalyst for hydrogen evolution. While Pt-assisted hydrogen evolution is not considered economic for scale-up, a modulation of intrinsic photophysical and physicochemical properties of melon is therefore crucial to overcome the Pt dependency. However, to our knowledge, no systematic study has been reported to date to make melon independent of Pt for solar hydrogen evolution. Here we show that the limiting factors of Pt-dependent hydrogen production can be overcome by amorphization. The amorphization lowers the band gap, shifts the proton reduction potential close to the origin, and enhances the light harvesting and charge transport. Therefore, it results in a Pt-free hydrogen evolution under visible light irradiation. We here also present a mechanistic understanding of the origin of this cocatalyst-free hydrogen evolution.

In this paper a scalable and controllable dc microgrid architecture has been presented with a source-end to load-end one-way communication based control interface to substantiate efficacious power sharing among five power management units (PMUs) attached to batteries. The system comprises a source converter and a load converter. The source converter consists of a maximum power point tracking (MPPT) controller with a boost average model and the load converter consists of a fanout node and five PMUs. The voltage of the photo voltaic (PV) array is boosted up to 400 V for transmission purpose. Perturb and observation algorithm is used for MPPT implementation. A pulse width modulation (PWM) switched full bridge (FB) converter in the fanout node is constructed to lower the source-end voltage and to generate a fixed intermittent dc bus of 48 V. Buck converter topology is used to design the PMUs and each PMU is controlled in a way to generate an output voltage suitable for a 12 V battery charging application. Sensing the solar irradiance level a one-way communication premise is designed to control the power flow towards and sharing among the PMUs so that the more important units receive more power in a crisis situation. The proposed framework has been tested in MATLAB/Simulink platform and the performance evaluations yield to system efficiencies of more than 85% for different irradiance levels.

A dual interaction-based (i.e., ionic/covalent) deposition of carbohydrate polymers, namely chitosan (CS) and oxidized sodium alginate (OSA) along with a plant-derived phosphorus-rich compound like phytic acid (PA) and a nitrogen rich compound like melamine (ME) was considered onto the phosphorylated chitosan (PCS) modified polyamide 6.6 (PA6.6) fabric surfaces in order to impart durable flame retardancy along with super-hydrophilicity of the same. Firstly, the pure PA6.6 textile surfaces were modified by PCS via UV-induced grafting and subsequently, the above-mentioned polyelectrolytes were assembled onto the fabric surfaces in a quadralayer fashion [i.e., (CS/ME-OSA-CS/ME-PA) n; “n” represents the number of quadralayers (QLs)]. Here, the amino groups of CS/ME and the aldehyde groups of the OSA were stabilized via covalent interaction and the deposition of positively charged CS/ME and negatively charged phytic acid (PA) formed ionic interaction. In the vertical burning (UL-94) test, both the only PCS grafted and the simultaneously PCS-grafted along with LbL assembled fabrics could completely stop the melt dripping tendency and attained a V-1 rating. In the meantime, the limiting oxygen index (LOI) value received a moderate increase from 18.5 % of pure PA6.6 to 23.5 % for the PCS grafted and 8-QLs deposited fabric sample (i.e., PA6.6-g-PCS-8QL). Moreover, the PA6.6-g-PCS-8QL fabric sample exhibited a dramatic decrease in the peak heat release rate (pHRR) and total heat release (THR) by about 45 % and 24.7 % respectively alongside enhanced thermal stability. Apart from the appreciable flame retardancy, this fabric sample (i.e., PA6.6-g-PCS-8QL) could boost up the hydrophilicity to attain a water contact angle of 0°. Finally, this dual interaction-based deposition of bio-inspired polyelectrolytes posed a positive impact in enhancing the coating stability in laundering and imparting durable flame retardancy to sustain even up to 20 laundering cycles.

Cotton fabrics are prone to ignite fire accidents as well as breed bacteria and fungi, which have hampered their applications in the field of packaging and home decorations. Guanazole complexes with silver and zinc ions were deposited to cotton fabrics through self-assembly to prepare the flame-retardant and antibacterial cotton fabrics. The effect of the guanazole-metal complex on the morphological structure, flammability and thermal degradation of cotton fabrics was studied by field emission scanning electron microscopy (FESEM), limiting oxygen index (LOI), vertical burning test (UL-94), thermogravimetric analysis (TGA). The antibacterial and antifungal activity of the coated fabric was evaluated as well. The guanazole-zinc and guanazole-silver treated cotton fabrics showed a high LOI of 29.5% and 27.5%, respectively. In the vertical burning test, both the guanazole-zinc and guanazole-silver treated cotton fabrics self-extinguished when removing the ignition source, displaying a UL-94 V-0 classification, while the untreated one and the guanazole-treated one completely burned out. Thermogravimetric analysis results confirmed that the guanazole-metal complex promoted the thermal decomposition of cotton and thus improved the char yield significantly. Micro-scale combustion calorimeter measurements clarified that the guanazole-zinc and guanazole-silver treated cotton displayed dramatically decreased peak heat release rate (64.4% and 59.1%, respectively) and total heat release (26.4% and 14.8%, respectively) in comparison to the untreated one. The significantly improved flame retardancy of guanazole-metal complex treated cotton fabrics could be attributed to their enhanced charring capability that blocked flammable volatiles into flame zone. The treated cotton fabric with guanazole-metal complexes exhibited better antibacterial capacity against Staphylococcus aureus and Escherichia coli than untreated and guanazole-treated ones. Furthermore, the guanazole-silver treated cotton fabrics also showed good antifungal activity against Penicillium, Fusarium chlamydosporum and Aspergillus niger.

Hydrogen from direct splitting of water molecules using photons is reckoned to be a sustainable and renewable energy solution for the post fossil-fuel era. Efficient photocatalysts, including metal-free photocatalysts, are key determinants of cost-effective hydrogen generation at a large-scale. The search for new materials that are metal-free is therefore ongoing. Recently, 2D phosphorene, a phosphorus analogue of graphene, has been added as a new semiconductor to the family of monolayer-flatland materials. In this review, we focus on analysing the fundamental electronic, optical and chemical properties of 2D phosphorene and assess its suitability as a metal-free water splitting photocatalyst. We also critically analyse its stability against claims from environmental antagonists and attempt to predict its future as a photocatalyst. This review provides timely information for researchers, scientists and professionals devoted to materials research for photocatalysis.

The layer by layer (LBL) deposition of chitosan/melamine/urea (CS/ME/UREA) and phytic acid (PA) onto the acrylic acid (AA) grafted Polyamide 6.6 (PA6.6) fabrics including a pad-dry-cure treatment with chitosan/graphene oxide (CS/GO) nanocomposites were considered to improve the hydrophilicity and durable flame retardancy. Obtained results indicated that these hybrid coatings could significantly improve the flame retardancy as the limiting oxygen index (LOI) value reached up to 25 % from 18.5 % and could completely stop the melt dripping where the fabric sample with two bilayers deposition and simultaneously treated with CS/GO nanocomposite (PA6.6-g-AA-2BL-CS/GO) achieved a V-1 rating. A 2BLs deposited hybrid coating (i.e., PA6.6-g-AA-2BL-CS/GO) could decrease the peak heat release rate (pHRR) by 47.1 %; whereas a maximum reduction of pHRR by about 56 % was achieved for 5BLs deposition. Moreover, a considerable improvement in thermal stability and char yield% were also realized in the thermogravimetric analysis (TGA) test. Furthermore, the as-prepared hybrid coatings imparted better hydrophilicity as a 2BLs deposition along with pad-dry-cure treatment by CS/GO could boost up the hydrophilicity of the treated fabrics further compared to the only 2BLs deposited fabric sample. In addition, the application of CS/GO nanocomposite could improve the stability of this coating and able to stop the dripping tendency even after 10 laundering cycles as well.

A DOPO-based phosphorus compound (DOPA) was synthesized and applied onto the pure and chitosan (CS) modified polyamide 66 (PA66) fabric surfaces via a simple pad-dry-cure method to improve the flame retardant properties of the same. The pure and chitosan modified fabric samples treated with DOPA at different content % degraded in a different way as the char residue formation and releasing of volatile and non-volatile gas species were dissimilar which were evident from the thermogravimatric and thermogravimetric-gas chromatography-mass spectroscopy (TG-GC-MS) test analysis. Obtained results also showed that no dripping occurred in the vertical burning test and a sharp increase in limiting oxygen index (LOI) values was noticed for all the treated fabric samples. CS modified PA66 fabric sample treated with a 10 wt % of DOPA exhibited a greater reduction in pHRR by 40% and showed superior flame retardant performance compared to the only DOPA treated pure fabric sample. The superb flame retardant properties of CS modified fabrics were due to the co-presence of DOPA and CS; where a synchronized gas phase and a condensed phase flame retardant mechanism was realized as DOPA showed a quenching effect in a gas phase mechanism and simultaneously, catalyzed the charring of CS in a condensed phase activity which was also justified from the TG-GC-MS analysis, TGA and FTIR analysis of char residues. However, this kind of facile application showed poor wash durability and deteriorated the physical properties of the fabric materials specifically treated with a higher DOPA content.

Recently developed molecular techniques facilitate the re-evaluation of phylogenetic relationships and taxonomic classification. This study evaluates 11 Japanese Phytophthora strains that previously had been identified morphologically, and three additional strains that had remained unidentified. The eleven previously identified strains exhibited low sequence homology with the species they were assigned to originally, but high homology with P. hedraiandra, P. multivora, P. niederhauserii, P. sansomeana, P. sp. kelmania, and P. sojae. The three previously unidentified strains showed low homology with representative strains of P. nicotianae or P. palmivora, according to previous analysis based on rRNA gene internal transcribed spacer (rRNA gene ITS), rRNA gene large sub-unit (LSU) and cytochrome c sub-oxidase (cox)1 sequences. To confirm previous phylogenetic identifications, we sequenced more two genes, β-tubulin and translation elongation factor 1 alpha (EF1-α), performed phylogenetic analyses in different gene combinations and obtained results that were in line with morphological data. The re-identified species P. hedraiandra, P. multivora, P. niederhauserii, P. sansomeana, and P. sp. kelmania are new to Japan, adding to the Phytophthora biodiversity in this country. Taken together, this and previous phylogenetic studies indicate that cox1 is a dependable gene for Phytophthora identification.

New diseases of Easter lily and lettuce were noticed in Japan and the pathogens were identified initially as Phytophthora megasperma and Phytophthora sp., respectively, based on morphological characteristics. We re-examined these isolates using phylogenetical and morphological analysis. In a detailed phylogenetic analysis of all clade members that was based on the sequences of eight genomic regions, Easter lily isolates formed a monophyletic group with high bootstrap support. The unique colony pattern supported this result. In separate analyses of Phytophthora clade 8 based on rRNA gene ITS and the cox 1 gene sequences, the lettuce isolates grouped with P. lactucae (described from lettuce in Greece) in the rRNA gene ITS tree but formed a distinct group in the cox 1 tree. The sporangia of Japanese lettuce isolates germinated directly, an uncommon feature in clade 8b. These results suggested that the Easter lily and lettuce isolates are novel species that we formally describe as Phytophthora lilii sp. nov. and P. pseudolactucae sp. nov., respectively. Moreover, P. lilii appears to represent a new Phytophthora clade.

Over the past 40 years in Japan, Phytophthora isolates have been collected from various diseased host tissues and infested soils and identified using morphological characters. In order to develop a molecular method for the characterization of Japanese Phytophthora species, we obtained nuclear ribosomal ITS and LSU and mitochondrial cox I DNA sequences from 151 isolates representing 21 known species and 10 unidentified isolates. These were compared with similar sequences from representative isolates of known species. Of these, 124 isolates were found to have been correctly identified. Among the remaining 37 isolates, 19 showed high homology with other described species. The remaining 18 isolates showed only low levels of homology with any known species, and generated monophyletic sub-clades in a phylogenetic tree based on the ITS and nLSU regions and the cox I gene. Therefore, these isolates are candidates for new species, falling into six groups. Together, the Japanese isolates were found to represent phylogenetically diverse groups of species. In a sequence variation analysis, the ITS regions and the cox I genes were found to be more variable than the nLSU sequences, suggesting that they will be more useful for Phytophthora identification.

A new disease of rose was noticed in Chiba Prefecture of Japan in 1968, and the pathogen was initially identified as Phytophthora megasperma based on morphological characteristics. Similar Phytophthora isolates have since been collected from rose plants in Chiba, Kanagawa, and Shizuoka Prefectures. In 2005, several Phytophthora isolates were recovered from crowns of strawberry plants in Hokkaido Prefecture. These were considered to be members of a new species. In this study, we re-examined all these isolates using morphological and physiological studies and a multilocus phylogenetic analysis. The rose and strawberry isolates were mostly similar morphologically and physiologically, with some exceptions. The rose isolates differed significantly from P. megasperma sensu stricto and other related Phytophthora species. The rose and strawberry isolates had external proliferation of sporangia, characteristic funnel-shaped oogonia, predominantly paragynous antheridia, and fast growth rates of 10.5 mm/24 h at an optimum temperature of 28 °C. In the multilocus phylogenetic tree constructed using sequences from the rDNA ITS regions, rDNA LSU, and the translation elongation factor 1-α, β-tubulin and coxI genes, they formed a distinct monophyletic group in clade 7 with strong bootstrap support. The rose and strawberry isolates separated into two distinct groups. The results indicate that the rose and strawberry isolates constitute two separate species, designated here as Phytophthoranagaii and P. fragariaefolia.

This paper discussed advances in several suitable passivation schemes and emitter optimization techniques available up to date. c-Si endowed with numerous crystal defects and impurities which are responsible for lower efficiency of solar cells made out of it. The surface passivations and emitter formations are the two inevitable processes to upgrade the solar cells efficiency by circumventing several induced effects due to associated crystal defects and impurities of c-Si. This work will act as a common place for the solar cell researchers, engineers and for the students to get the very recent results of surface passivation and emitter optimization techniques practiced both in the industries and R&D laboratories over the world. Key issues here to be considered while agglomerating the relevant information for each process step are the cost-effectiveness, added complexity, additional benefits, reliability, and efficiency potential.

A slow growing, nonpapillate, homothallic Phytophthora species was isolated from leaf and stem blights of kudzu (Pueraria lobata) in the Toyama and Ishikawa districts of Japan. The isolates could not be assigned to an existing taxon and were characterized in a morphological study and a phylogenetic analysis. They were found to differ from related Phytophthora species by their characteristic obturbinate, often distorted sporangia with external proliferation, moderately large oogonia with aplerotic oospores, predominantly amphigynous but occasionally paragynous and intercalary antheridia, the presence of catenulate hyphal swellings, their high optimum temperatures for growth, and their relatively slow radial growth rates. An unusual characteristic was the germination of zoospores within the sporangia. In the phylogenetic analyses involving sequences from seven nuclear and two mitochondrial genes, the isolates formed a distinct monophyletic group within Phytophthora clade 7 with strong bootstrap support. On the basis of their unique combination of characters, the isolates are considered to be a new species and are formally described as Phytophthora asiatica sp. nov.

A comparative study has been made to analyze the impact of interstitial iron in minority carrier lifetime of multicrystalline silicon (mc-Si). It is shown that iron plays a negative role and is considered very detrimental for minority carrier recombination lifetime. The analytical results of this study are aligned with the spatially resolved imaging analysis of iron rich mc-Si.