Current challenges and future perspectives of solar-PV cell waste in Bangladesh.

This study focused on the current situation and management after the end-of-life solar photovoltaic (PV) module in Bangladesh. The solar PV cells have a lifetime to serve properly, which is about 15-25 years from installation. Solar PV cell has recycling potentiality as well as the risk of producing hazardous wastes. After the end-of-life, the solar panel would turn into waste, specifically e-waste, which might be an environmental concern in the long run. Thus, it is crucial to estimate the waste production and to delineate the environment-friendly management. Therefore, this study aims to visualize the present status of solar PV cells, potential waste generation, and their management perspectives in Bangladesh. We also studied the existing policy of waste management. This study followed a mixed methodological approach, including the key informant interview (KIIs), synthesis of existing literature-based findings, stakeholder consultation and secondary data inventory. From the results, it was found that Bangladesh has huge potential to generate solar PV-based e-waste in the near future that needs to be tackled with high priority. A total about 33205.36 tonnes of potential e-waste can be generated from installed PV cells. A suitable management system might be able to recover materials such as glass (24,468 tonnes), aluminium (2,656.43 tonnes), silicon (1404. 92 tonnes), and copper (49.89 tonnes) from the PV cells wastes. As there is an excellent opportunity to recover resources from the waste panels, there is also scope to grow enterprise for recycling of waste panels. Unfortunately, such policy or plan from the government is yet to be taken into account. However, a long-term national plan is required to manage this waste, maintaining the high standard based on in-depth research.

Antimicrobial activity of different solvent extracted samples from the leaves and fruits of Capsicum annuum.

The current research describes the antimicrobial potential of methanol, n-hexane, n-butanol, ethyl acetate and aqueous extracted samples from the leaves and fruits tissues of Capsicum annuum. Different solvent extracted samples were screened against six pathogenic microorganisms including five bacterial and one fungal specie by disc diffusion susceptibility assay using 1, 2 and 3 mg disc-1 concentrations. When analyzed statistically the data showed that different solvent extracted samples from both leaves and fruits of Capsicum annuum revealed varying degrees of antibacterial and antifungal activities. n-butanol and ethyl acetate extracted fractions from both leaves and fruits showed significant inhibition of growth against all the tested microorganisms at 1, 2 and 3 mg disc-1 concentrations. Escherichia coli were completely resistant to aqueous extracts obtained from the leaves at all the three concentrations. Klebsiella pneumonia was resistant to n-hexane extracted fraction from leaves at 1mg disc-1 concentration, however, was susceptible at 2 and 3 mg disc-1 concentrations. The growth of Pseudomonas aeruginosa and Staphylococcus aureus were effectively inhibited by all the solvent extracted fractions from the fruits while aqueous fraction was not able to inhibit the growth of Bacillus subtilis. The growth of Candida albicans was effectively inhibited by ethyl acetate extracted fraction from leaves at 3 mg disc-1 concentration.

Bioavailability of heavy metals in contaminated soil as affected by different mass ratios of biochars.

The biochars are efficient adsorbent of heavy metals. However, the type of biochar species determines the effectiveness of biochars for immobilization of heavy metals. In this experiment, we mixed different biochars in variable mass ratios and evaluated their effects on plant growth and bioavailability of heavy metals. The results revealed that amendment of single and mixed biochars has increased pH, EC, available P and K of soil. The straw block biochar with maize straw biochar at a mass ratio of 1:2 (SDM) has significantly decreased Pb and Cu concentration in soil. The straw block biochar with maize straw biochar at a mass ratio of 2:1 (DSM) has highly increased the dry biomass of Chinese cabbage than single biochar or control, whereas plant physiological properties were mostly not affected. It is concluded that peanut shell biochar with maize straw biochar at a mass ratio of 2:1 (DPS) and DSM have significantly decreased Pb, Zn and Cu concentration in plants. The single peanut shell biochar has significantly decreased the plant Cd concentration. The ability of transport of heavy metals in Chinese cabbage was in the sequence of Cd > Zn > Cu > Pb. The mixing of different biochars has decreased the concentration of heavy metals in plants more effectively than single biochar.

Source apportionment of heavy metals in farmland soil with application of APCS-MLR model: A pilot study for restoration of farmland in Shaoxing City Zhejiang, China.

The conditions of the sources of heavy metals are essential to assess its potential threats to human health. The identification of the origin of heavy metals is essential for planning effective measures to control long-term accumulation of heavy metals. In this study, analysis of pollution sources was performed on 100 soil samples with geostatistics and absolute principal component score-multiple linear regression (APCS-MLR) receptor model. The descriptive statistics revealed that concentrations of heavy metals (Pb, Zn, Cu, Ni) have exceeded the background value of Zhejiang Province. The coefficient of variation is Pb > Cd > Cu > Zn > Ni > Cr. The APCS-MLR and geo statistical analysis showed that sources of pollution: PC1 was Ni, Cr, Cu, Zn because of soil parent material. The contribution rates were 89.42%, 87.19%, 29.64%, and 33.58%, respectively. The PC2 was Pb, Zn and Cu which were mainly caused by anthropogenic mining activities. The contribution rates were 95.92%, 24.81%, and 40.62%, respectively. The PC3 was Cd、Zn and Cu which was mainly caused by agricultural inputs, and their contribution rates were 91.96%, 41.61%, and 30.14% respectively. According to Nemero Synthesis Index evaluation method, the Shaoxing City Zhejiang, China is heavily polluted with heavy metals.

Bioinspired synthesis and characterization of gold nano-particles from medicinally important Periploca hydaspidis and their in vitro antioxidant and antimicrobial activity.

This research investigates the synthesis and characterization of gold nanoparticles from Periploca hydaspidis and their antimicrobial and anti oxidant activity. The synthesis of AuNPs was confirmed by UV-Vis spectrophotometer and structure by a high resolution atomic force microscope. X-ray diffraction and Fourier transformed infrared spectroscopy was used to study the crystallite size and different functional groups. DPPH radical scavenging activity and disc diffusion protocol was applied for the determination of antioxidant and antimicrobial activity. A ratio of 1:8 of 1mM AuCl3 solutions with plant boiled extract used for synthesis of gold nano-particles. The formation of the gold nano-particles was determined by the color change from yellow to dark purple which were confirmed by UV-Vis spectrophotometer. Gold nano-particles were stable between 24°C and 39°C, mM concentration of the salt and neutral pH. The groups responsible for the synthesis of gold nano-paricles were Alkenes and aliphatic amines. The AuNP were cubic in nature and the nanocrystallite size was 6.99nm. Gold nano-particles revealed good antioxidant activity and controlled the growth of K. pnemoniae, E. coli, X. compestris, C. albicans and P. chrysogenum.

Effect of different solvent extracted samples from the leaves and fruits of Datura stramonium on the growth of bacteria and fungi.

Different solvent extracted samples from the leaves and fruits tissues of D. stramonium were tested against five pathogenic microorganisms by disc diffusion susceptibility method using 1, 2 and 3mg disc-1 concentrations. Methanol and chloroform extracted fractions from both leaves and fruits measured good growth inhibition of all the tested microorganisms at all concentrations. Bacillus subtilis was very resistant to n-butanol and aqueous extracted fractions of fruits tissues at all the tested three concentrations. The growths of Pseudomonas aeruginosa and Klebsiella pnuemonia were efficiently reduced by all the solvent extracted fractions from the fruits while aqueous fraction was unable to restrain the growth of Bacillus subtilis. The growth of Candida albicans was effectively reduced by aqueous extracted fraction from the leaves tissue at the highest concentration. Maximum growth reduction of (77%) was shown by chloroform extracted fractions from the leaves against Klebsiella pneumonia at 3mg disc-1 concentration. Minimum zone of inhibition (35.4%) was measured by n-butanol extracted fractions from the leaves against Pseudomonas aeruginosa at the lowest concentrations of 1mg disc-1. In case of leaves the most vulnerable bacteria was Bacillus subtilis while in case of fruits Klebsiella pneumonia was the most susceptible while Bacillus subtilis was the most resistant one.

Effects of biochar on growth, and heavy metals accumulation of moso bamboo (Phyllostachy pubescens), soil physical properties, and heavy metals solubility in soil.

Pot experiment was conducted to investigate the effects of wood biochar (5%), bamboo biochar (5%), rice straw biochar (5%) and Chinese walnut shell biochar (5%) on growth, accumulation of heavy metals in moso bamboo, soil physical properties, and solubility of heavy metals in soil. The results revealed that dry weight of moso bamboo was significantly increased in treatments of wood biochar (5%), rice straw biochar (5%) and Chinese walnut shell biochar (5%) except bamboo biochar (5%). Application of straw biochar (5%) was most effective in enhancing plants biomass, with increase of 157%, 113% and 111% in leaves, roots and stems of moso bamboo. All treatments of biochar have significantly improved soil electrical conductivity with maximum increase of 360% compared to CK. In case of heavy metals accumulation, application of 5% bamboo biochar, straw biochar and Chinese walnut shell biochar has reduced Cu uptake in roots by 15%, 35% and 26%, respectively. The biochars have significantly reduced solubility of soil heavy metals with maximum reduction of 58.91 mg kg-1 and 10.59 mg kg-1 of Cu and Pb with application of rice straw biochar. It is concluded that dry weight of moso bamboo was significantly enhanced by all treatments of biochar except bamboo biochar.

Extraction and isolation of important bioactive compounds from the fruit of Physalis ixocarpa.

The current study investigates pharmaceutically important bioactive compounds in the fruits of Physalis ixocarpa. Two different extractions methods were used to study its effect on percent extract yield, recovery of bioactive compounds and antioxidant activity of the extracts. The data indicated that Soxhlet extraction had high efficiency of recovery than maceration method for extracting compounds; percent extract yield and antioxidant activity of the extracts. In maceration, the percent extract yield was found to be in order of water >methanol >ethyl acetate whereas in Soxhlet extraction, it was in order of methanol >water >ethyl acetate. Ethyl acetate extract produced by Soxhlet extraction showed strong antioxidant activity of 59.7% (250ppm) as compared to other extracts. Analysis of ethyl acetate extract showed the presence of Triglyceride. GC-MS study of triglyceride revealed the presence of trilinoleinic acid (9,12-Octadecdienoic acid), tripalmitin (hexadecanoic acid) and trioleinic acid (9-Octa decenoic acid). Four impure and three pure compounds were isolated from crude methanol extract of the fruit. The structure of pure compounds were identified by NMR and characterized as sugar, glucose and fructose.

Impact of different solvent extracts from leaves and fruits of Eucalyptus globulus on growth of different bacteria and fungi.

The present research investigates the antimicrobial activities of the samples extracted from the leaves and fruits of Eucalyptus globulus through disc diffusion susceptibility assay using 1, 2 and 3mg disc-1 concentrations. Different extracted samples from the leaves and fruits of Eucalyptus globulus exhibited different degrees of antimicrobial. The data indicated that n-butanol and ethyl acetate extracted fraction of both the leaves and fruits inhibited the growth of all microorganisms at all the tested concentrations. Aqueous extracted sample of the leaves inhibited the growth of Candida albicans while the same fraction from the fruits showed no activity against Bacillus subtilis at any concentration. N-hexane extracted samples of the leaves inhibited the growth of Bacillus subtilis, E. coli and Pseudomonas aeruginosa at the tested concentrations while no activity was recorded against Klebsiella pneumonia, Candida albicans and Stephylococcus aureus. N-butanol extracted samples from the leaves and fruits showed activity against Pseudomonas aeruginosa at the tested concentrations. In case of leaves, the most susceptible bacteria was Bacillus subtilis (gram positive) and Stephylococcus aureus (gram positive) was the most resistant one. In case of fruits the most susceptible bacteria was Stephylococcus aureus (gram positive) and E. coli (Gram negative) was the most resistant one.

GC-MS profile of bioactive compounds from medicinally important Periploca hydaspidis.

The aim of the present study was to investigate bioactive compounds in different solvent extracted samples from the stem tissues of P. hydaspidis using Gas Chromatography and Mass Spectroscopy techniques. GC-mass spectrum was compared with the data base of National Institute of Standards and Technology (NIST) containing more than 62000 patterns of the mass spectrum. During matching with NIST library the match factor greater than 700 was considered only for better and pure results. The results revealed that different solvent extracted samples analyzed through GC-MS contained appreciable quantities of different bioactive molecules including antibiotics, fatty acids and protein which have important pharmacological significance.

Effect of amendments on contaminated soil of multiple heavy metals and accumulation of heavy metals in plants.

The contamination of soil with heavy metals is a severe problem due to adverse impact of heavy metals on environmental safety and human health. It is essential to remediate soil contaminated with heavy metals. This study has evaluated the effects of pine biochar, kaolin, and triple super phosphate (TSP) on multiple heavy metals (Ni, Zn, Cu, and Cd) in contaminated soil and accumulation of heavy metals in plants. The amendments can reduce availability of heavy metals in soil by increasing pH, adsorption, complexation, or co-precipitation. Different amendments have variable effects on accumulation of heavy metals in plants and in soil due to its diverse mechanism of stability. The results showed that application of triple super phosphate (TSP) has significant reduced soil Cd exchangeable (EXC) fraction from 58.59 to 21.30%. Bound to carbonates (CAR) fraction decreased from 9.84 to 5.11%, and bound to Fe-Mn oxides (OX) fraction increased from 29.61 to 69.86%. The triple super phosphate (TSP) has the ability to stabilize Cu and especially Cd. However, triple super phosphate (TSP) has enhanced ecological risk of Zn and Ni. Application of pine biochar has significantly enhanced soil pH. The kaolin has significantly reduced EXC fraction of Cd and increased OX fraction of Cu. The amendments and heavy metals have not caused significant effect on SPAD value of Buxus microphylla Siebold & Zucc (B. microphylla). The triple super phosphate (TSP) has significant decreased biomass of B. microphylla and bamboo-williow (Salix sp.) by 24.91 and 57.43%, respectively. Pine biochar and kaolin have increased the accumulation of Zn and Cd in plants. It is concluded that triple super phosphate (TSP) was effective in remediation of Cd and kaolin was effective in remediation of Cd and Cu. Pine biochar was effective in remediation of Cd, Cu, and Zn.

Antinociceptive, antimicrobial potential and phytochemical screening of different solvent extracted samples from the stem of Acer pentapomicum.

The present study investigates the antinociceptive, antimicrobial activity and phytochemical assessment of samples from A. pentapomicum. Different microbes were tested using disc diffusion assay at three concentrations (1, 2 and 3 mg/disc). Antinociceptive activity was determined by acetic acid induced and hot plate methods. The tested plant extracts revealed significant antinociceptive activity at dose dependent manner when measured by acetic acid induced method. The growth of all the tested microbes was inhibited by methanol, butanol, and ethyl acetate extracted samples at all concentrations. Chloroform, n-hexane and aqueous extracts inhibited the growth of the different microbes at high concentration. The most susceptible microbe was P. aeruginosa measuring 94% and 79% zone of inhibition by butanol and ethyl acetate extracts at 3mg /disc. C. fruendii, however, was the most resistant bacterium followed by S. aureus. The presence of alkaloids, proteins, amino acids, carbohydrates, flavonoids, tannins, saponins, and fats were confirmed in phytochemical screening of different extracts.

Effect of EDTA and citric acid on absorption of heavy metals and growth of Moso bamboo.

The effect of EDTA and citric acid on accumulation, toxicity of heavy metals (Cu, Zn, Cd, and Pb), and growth of Moso bamboo was investigated in current experiment. The availability of heavy metals in soil and its uptake by plants has indicated toxicity. The results revealed that EDTA and citric acid has reduced biomass of Moso bamboo but non-significant difference in biomass was observed compared with control. Application of EDTA (10 mmol kg-1) has significantly improved copper (Cu) by 56.5 and 84.9% in roots and above ground parts of plants. Application of EDTA (10 mmol kg-1) has significantly enhanced lead (Pb) by 51.8 and 210.8% in roots and above ground parts of Moso bamboo. Furthermore, treatment of EDTA has significantly improved activities of water-soluble Cd, Cu, and Pb in soil by 98.9, 70.1, and 73.1 times compared with control. In case of contents of diethylenetriaminepentaacetic acid (DTPA)-extractable metals, the treatment of EDTA (10 mmol kg-1) has produced maximum increase of 244.5 mg kg-1 Zn and 157.9 mg kg-1 Pb, respectively. It is concluded that effect of EDTA was superior compared with citric acid for improvement of phytoremediation potential of Moso bamboo.

Phytochemical analysis, phytotoxic and insecticidal activities of medicinally important Periploca hydaspidis.

The present study investigates the phyto-chemical analysis, phytotoxic activity and insecticidal activity of the stem and root tissues of medicinally important Periploca hydaspidis. All the extracted samples exhibited the phytotoxic activity. The data confirmed that water was the best solvent to extract the phytotoxic compounds from stem and root tissues. Roots extracted with different solvents exhibited better phytotoxic potential than samples obtained from the stem tissues. Samples extracted in methanol and water from both stems and roots tissues were active against the subject insects while hexane, ethyl acetate and butanol extracted samples in both parts exhibited no insecticidal activity. Water extracted samples of the stem and root exhibited better insecticidal activity compared with methanol extracted samples. Tribolium castaneum and Rhizopertha dominica were more sensitive in both the cases than Callosobruchus maculates. The plant contained alkaloids, flavonoids, carbohydrate, proteins and saponins.

Postgraduate Medical Trainees Understanding of Biostatistics: A Pre- and Post-Research Methodology Workshop Experience.

OBJECTIVE: To evaluate understanding of biostatistics among postgraduate medical trainees before and after biostatistics workshop. STUDY DESIGN: Quasi experimental study. PLACE AND DURATION OF STUDY: Regional Centre, Islamabad, College of Physicians and Surgeons Pakistan, from March to September 2017. METHODOLOGY: Two hundred and seventy postgraduate trainees were enrolled after taking informed consent. Structured questionnaire containing 21 multiple choice questions regarding understanding and application of biostatistics was given to all participants on the first and the last day of workshop and compared pre- and post-workshop by McNemar test of significance. SPSS version 21 was used for data analysis with p-value <0.05 as significant level. RESULTS: The response rate was 100%. Among these participants, males were 81 (30%) and females were 189 (70%), mean age was 28.5 ±2.5 years. One hundred and twenty-five (46%) postgraduate trainees were from Islamabad. Most of the doctors were in the first year (37%) and second year (57%) of their training. With total correct answers of 42.9% (preworkshop) and 57% (post-workshop), p-value was <0.001. CONCLUSION: Understanding regarding application of biostatistics in research among PGTs improved significantly and immediately after teaching biostatistics in research methodology workshop.

Phytochemical screening and antibacterial activity of different solvent extracted samples of Arisaema jacquemontii.

The current research was carried out to assess the antibacterial activities and phytochemical analysis of the methanol, n-hexane, ethyl acetate, n-butanol soluble fractions and aqueous extracts of the tubers of Arisaema jacquemontii. All the extracts were tested for their antibacterial potential at 1, 2 and 3 mg disc-1 concentrations against 6 bacterial strains through disc diffusion suseptibility assay. The data suggested that different extracts showed varying degree of growth inhibition against the tested microbes. Statistical analysis revealed that n-hexane and ethyl acetate soluble fractions significantly inhibited the growth of all the bacterial strains at the tested concentrations. Moderate activities were recorded for n-butanol and methanolic extracted samples at different concentrations against all the tested strains of bacteria. P. aeruginosa, S. aureus and X. campestris showed resistance to all the tested concentrations of the aqueous extract. B. subtilis and K. pneumoniae were resistant at 1 and 2 mg disc-1 concentrations of the aqueous extract and 3 mg disc-1 of the same extract reduced the growth of the same bacteria. Phytochemical analysis of the different solvent extracted samples suggested the presence or absence of various metabolites including alkaloids, saponins, tannins, sterols, flavonoids, protein, carbohydrates and fats.

Fractionation of crude extracts from controlled dried and commercially available stem bark of Juglans regia and their antimicrobial effects.

The current research investigates the anti-microbial activities of methanol, ethyl acetate, n-hexane , n-butanol and water extracted samples from controlled dried and commercial bark of walnut (Juglans regia) against five bacterial (Staphylococcus aureus, Bacilus subtilis, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia and one fungal pathogenic specie (Candida albicans) by discs diffusion susceptibility assay using 0.5 and 1mg disc-1 concentrations. Our results revealed that all the extracts from controlled dried and commercial bark of walnut showed varying degrees of antimicrobial activities. Ethyl acetate fraction from both sources exhibited maximum activity against all tested microbial species followed by n-butanol and crude methanolic extraxt. N-hexane and aqueous extracted samples from controlled dried bark reduced the growth of all studied microbes except Staphylococcus aureus in case of commercial available bark. Aqueous extracted sample showed inhibitory effects against all tested microbes except Candida albicans respectively in case of commercial bark. The most susceptible gram positive bacteria were S. aureus while Bacillus subtilis was the most resistant one. Among Gram negative bacteria, Pseudomonas aeruginosa was the most susceptibility while Klebsella pneumonia showed some resistively. Compared to commercial bark samples, controlled dried bark extract and fractions were found to be more active in reducing the growth of all the tested microbes at both concentrations.

Report - Screening of medicinally important Berberis lyceum for their antimicrobial activity by disc diffusion assay.

The present research was focused on the anti-microbial activities of different solvent extracted fractions from commercial available and fresh plants of Berberis lyceum against Gram positive, Gram-negative bacteria and fungi using 1 and 2 mg disc-1 concentrations. Our results showed that fractions from both sources revealed different degree of antimicrobial activities. Our result indicated that Escherichia coli, Citorbacter freundii and Candida albicans were more susceptible to crude methanolic extract and the same microbes were resistant to water extracted fractions. Similarly, maximum reduction in the growth of Pseudomonas aeruginosa, Bacillus subtilis and Xanthomonas campestris was measured by hexane-extracted fractions and minimum growth inhibition by water-extracted fractions. Klebsiella pneumoniae and Staphylococcus aureus were more susceptible to ethyl acetate fraction. Majority of the tested microbes were resistant to water and butanol extracted samples. Staphylococcus aureus was the most susceptible gram-positive bacteria and Bacillus subtilis was resistant one. Among Gram-negative bacteria, Citorbacter freundii showed maximum susceptibility while Xanthomonas campestris revealed resistivity.

In vitro antibacterial and antifungal activities of different solvent extracted samples from the stem of Euphorbia heliscopia.

This paper presents the anti-microbial potentials of methanol, ethyl acetate, n-hexane, butanol and water extracted samples from the stem of Euphorbia heliscopia against S. aureus (Gram positive), B. subtilis (Gram positive), P. aeruginosa (Gram negative), K. pneumonia (Gram negative), E. coli (Gram negative), C. albicans (fungal specie) by discs diffusion susceptibility assay using 0.5 and 1mg disc-1 concentrations. Our results showed that all the extracted samples from the stem of E. heliscopia exhibited varying degree of antimicrobial activity. Ethyl acetate extracted samples measured maximum activity against the studies microbial species followed by the n-butanol and crude methanolic extract. n-hexane extracted samples inhibited the growth of all microbial species except P. aeruginosa and E. coli at lower concentration. Aqueous fractions showed inhibitory activity against B. subtilis, K. pneumonia and C. albicans. The most susceptible gram positive bacteria were S. aureus while B. subtilis was the most resistant one. Among Gram negative bacteria, P. aeruginosa showed more susceptibility while K. pneumonia was resistant.