Bio-mediated silver nanoparticle synthesis: mechanism and microbial inactivation

Even though plenty of literature is available on the biosynthesis of metal nanoparticles, there are serious lacunae on the mechanisms of their formation. In the present study, the mechanism of formation of mono-crystalline silver nanoparticles using a fruit extract of the ornamental tree Thevetia peruviana is emphasized, i.e. how the pH of the reaction mixture affected reaction kinetics and size of the nanoparticles. The facilitation of formation of Ag₂O at higher pH resulted in a faster rate of particle formation. The diameter of the bare particles at neutral pH determined by field emission scanning electron microscopy and the hydrodynamic diameter determined by dynamic light scattering were 53 and 104 nm, respectively. The silver nanoparticles exhibited good inactivation of Escherichia coli due to participation of free radicals as evidenced by electron spin resonance spectroscopy.     

Photocatalytic degradation of p-nitrophenol using biologically synthesized ZnO nanoparticles

Environmental Science and Pollution Research - The present work deals with the photocatalytic degradation of p-nitrophenol as it is a United States Environmental Protection Agency-listed priority...     

Ground water quality in the Kathmandu valley of Nepal

A study was undertaken to assess the quality of groundwaters in the Kathmandu Valley, Nepal. The groundwater samples were randomly collected from shallow well, tube well, and deep-tube wells located at different places of Kathmandu, Lalitpur, and Bhaktapur districts in the Kathmandu valley. Physical, chemical, and microbiological parameters of the samples were evaluated to estimate the groundwater quality for drinking water. It was found that the groundwater in the valley is vulnerable to drink due to presence of iron and coliform bacteria. Iron was estimated to be much higher then the acceptable limit of World Health Organization (WHO) drinking-water quality guidelines (1.9 mg/L). Total coliform bacteria enumerated in groundwaters significantly exceeded the drinking-water quality standard and observed maximum coliform (267 CFU/100 mL) in shallow wells. The electrical conductivity and turbidity were found to be 875 ??S/cm and 55 NTU, respectively, which are above the WHO recommendations for drinking water guidelines. However, pH value was measured within the acceptable limit. Arsenic, chloride, fluoride, and hardness concentrations were found to be in agreement with the recommendations of WHO drinking-water quality guidelines.     

Co-benefits of a carbon tax in Nepal

This paper analyzes the co-benefits of introducing a time variant carbon (C) tax scheme in Nepal, a hydropower resourceful country, by using a bottom up integrated energy system model based on the MARKet ALlocation (MARKAL) framework with time horizon of 2005–2050. It discusses the effects of C tax on energy mix, environmental emissions, energy supply security, energy efficiency, energy system cost, and employment benefit. The study shows that the C tax (that gradually increases from US13/tCO < sub > 2 < /sub > e in 2015 to US 13/tCO₂e in 2015 to US 200/tCO₂e by 2050) results in a reduction of the cumulative emission of greenhouse gases by 83.9 million tons CO₂e (12%) as compared to that in the base case. With the introduction of the C tax, there would be a need for additional hydropower capacity of 945 MW by 2050 as compared to the capacity in the base case. The emission of local pollutants consisting of sulphur dioxide (SO₂), nitrogen oxides (NO_x) and non-methane volatile organic compound (NMVOC) in 2050 would be reduced by 12%, 7% and 1% respectively under the C tax scenario. Total amount of imported energy would decrease by 13%, which corresponds to a reduction in discounted net fuel import cost by 5% during the study period. Furthermore, the C tax would result in new employment generation of 151 thousand man-years associated with the additional hydropower capacity requirement.     

Heterogeneity, collective action and management sustainability in common property forest resources: case study from the Indian state Odisha

Several studies have revealed that the presence of heterogeneity amongst the user groups of common property natural resources considerably affects the effectiveness of resource management and their sustainable use. Primary research conducted in six sample villages from three districts of the Indian state Odisha has found that heterogeneity in economic and social dimensions amongst the members of the management committee acts as major determinants in respect of common property forest resource management. The findings of this piece of work reveal that common property forests are best managed in the villages where the management committee is homogeneous by both social and economic considerations; better managed where the committee members are economically homogeneous but socially heterogeneous; and least managed where the members are socially homogeneous but economically heterogeneous. The same result has been obtained from the composite index developed for the user group’s assessment about the functioning of the forest management institutions in the three study districts of the state Odisha.     

Efficient arsenic depollution in water using modified maize powder

This article reports the synthesis of an efficient, low-cost material from maize powder to depollute arsenic-contaminated water. Arsenic is toxic for humans and other organisms even at low concentrations. The most well-known and severe case of arsenic poisoning through drinking water has been found in India and Bangladesh. Numerous inorganic materials have been tested for the removal of arsenic from water bodies over the last two decades. However, all such materials have several disadvantages such as unpredictable arsenic ion removal, high cost and the generation of toxic sludge that is often more difficult to manage. Alternatively, organic material from agricultural waste may be modified to enrich functional groups responsible for As sorption and, in turn, used to depollute contaminated waters. Here, Zea mays cob powder has been modified to remove arsenic species from water. Two modified materials were produced: an aminated maize powder and a thiolated maize powder. Amination was done using epichlorohydrin and dimethylamine. Thiolation was done using thioglycolic acids. Amination increased As (III) sorption from 70 to 75.8 % and As (V) sorption from 85 to 94.42 %, compared with unmodified maize powder. Thiolation increased As (III) sorption from 70 to 81.7 % and As (V) sorption from 85 to 90 %. Amination increased usability cycles from 3 to 5. Thiolation increased usability cycles from 3 to 6. The novel modified maize biosorbent has enough potential for the development of a low-cost technological pre-treatment step, prior to high-tech chemical treatments.     

Mechanical and Dynamic Mechanical Analysis of Woven Banana/Epoxy Composite

In this work, three types of woven (Plain, twill and Basket) composites are made of banana fibers/epoxy resin using hand-layup method. Mechanical properties (tensile, flexural and impact) of three types of woven composites are compared to evaluate the effect of weaving architecture on the properties. Dynamic Mechanical Analysis is carried out to analyse the visco-elastic behavior of the composite. Dynamic Mechanical Analysis is carried out in the temperature range of 40?C140?°C at 0.1,1,10?Hz frequencies. Scanning Electron Microscopic analysis is carried out to investigate the fracture behaviour of the composite. From the investigation it is found that plain type of woven composite has better mechanical and dynamic mechanical behaviour.     

Applications of smart grid technology in Nepal: status,challenges, and opportunities

Environmental Science and Pollution Research - Energy transformation and sustainability have become a challenge, especially for developing countries, which face broad energy-related issues such as...     

Assessment of environmental footprint using geospatial approach to ascertain the Sustainable Development Goal 2030s of India

Utilization of natural resources has multiplied globally, resulting in serious environmental deterioration and impeding the achievement of the Sustainable Development Goals (SDGs). For the harmonious development of human nourishment and the balance of nature, it is vital to evaluate environmental segments' resource usage, transformation, and residue, referred to as ‘footprint,’ in order to highlight carrying capacity and sustainability. This analysis highlights the Environmental Footprint (EF) of India per state from 2010 to 2020 in terms of hectares per capita. This study evaluates India's biological, hydrological, energy, ecological, and pollution footprints, carrying capacity, environmental pressure, and environmental deficit using 17 distinct parameters categorized under the themes of biological resource, hydrological resource, energy resource, and pollution concentration. We proposed a reoriented methodology and EF concepts that determine India's footprint, carrying capacity, nature of sustainability, environmental pressure index, and its consequential links to the 2030 SDGs. As a result, the biological resources contributed to ~50% of the environmental footprint, while hydrological, energy, and pollutants made up the remaining. Between 2010 and 2020, Delhi, Uttar Pradesh, Bihar, and West Bengal had the highest EF, while Jammu and Kashmir and the north-eastern provinces had the lowest. During the research period, the ecological deficit in India has increased overall. India impedes the 2030 SDGs; therefore, the study provides a picture of resource consumption, waste generation, economic growth, and societal changes, enabling academics and policymakers to redefine or document policy for a more sustainable future.