Characterization and removal of microplastics in the Guheshwori Wastewater Treatment Plant, Nepal.

Contamination of river water systems by microplastic particles (MPPs) is one of the emerging global environmental concerns with potentially widespread ecological, socioeconomic, and health implications. A wastewater treatment plant (WWTP) processes and treats wastewater to remove pollutants and release safe water into the environment. There has been limited research on the characterization of microplastics and their removal in WWTP in South Asia. In this work, we report on the characterization of microplastics in wastewater and sludge samples (n = 300) from Guheshwori WWTP located on the bank of the Bagmati River in Kathmandu city, Nepal representing inlet, secondary aeration tank (SAT), outlet, and sludge from November 2021 to November 2022. On average, we detected 31.2 ± 17.3 MPPs/L, 11.2 ± 9.4 MPPs/L, 8.5 ± 5.6 MPPs/L, and 6.6 ± 4.8 MPPs/g in the samples collected from inlet, SAT, outlet, and sludge, respectively. Commonly found MPPs were in the form of fiber, fragments, foam, and pellets. Largely, MPPs were red, yellow, white, blue, and black. Among the 44 µm - 150 µm, 150 µm - 500 µm and 500 µm - 5 mm categories of size fractions, the most dominant fractions were 500 µm - 150 µm in inlet, SAT, and sludge, and 150 µm - 44 µm in the outlet sampling unit. The Guheshwori WWTP was able to remove 72.5 % of MPPs on average, that mostly occurred in the inlet. The effluent released into the river and the sludge still contained a significant number of MPPs.

Material Properties of Traditional Handmade Paper Samples Fabricated from Cellulosic Fiber of Lokta Bushes.

Handmade papers (HPs) are fabricated from fibrous biomass of Lokta bushes and other plant species following traditional eco-friendly method in Nepal. Although HP fabricated from Lokta bushes is believed to be durable and resistant to bugs and molds, material properties of this paper are not reported in literature. In this study, we measured several material properties of 10 handmade Lokta paper samples collected from local enterprises and paper industries. The mean caliper, grammage, apparent density, equilibrium moisture content, Cobb 60, brightness, opacity, tensile strength, and tensile index values in the paper samples ranged from ∼90 to 700 µm, 50 to 150 g/m2, 0.2 to 0.4 g/cm3, 4 to 7%, 50 to 400 g/m2, 56 to 67%, 83 to 98%, 30 to 2900 N/m, and 1 to 27 Nm/g, respectively. These properties suggested that the HPs are lightweight papers with intermediate to high strength. The tensile strength was found to be significantly higher along the length direction (p < 0.05). Characteristic features of cellulose, hemicellulose, and lignin were observed in FTIR spectra. The crystalline and amorphous phases were also identified in X-ray diffraction (XRD) data. Electron microscopy images revealed a nicely cross-linked network of intact fibers having almost parallel arrangement of microfibrils. These features could provide strength and durability to the paper samples. Understanding the material properties of HPs down to the sub-microscopic level may help improve the paper quality and find novel applications in the future.

A PCBM Electron Transport Layer Containing Small Amounts of Dual Polymer Additives that Enables Enhanced Perovskite Solar Cell Performance.

A polymer/PCBM hybrid electron transport layer is reported that enables high-performance perovskite solar cells with a high power conversion efficiency of 16.2% and with negligible hysteresis. Unlike previous approaches of reducing hysteresis by thermal annealing or fullerene passivation, the success of our approach can be mainly attributed to the doping of the PCBM layer using an insulating polymer (polystyrene) and an amine-containing polymeric semiconductor named PFNOX.

Biometric parameters and intra ocular lens power used for cataract eyes in Karnali, Nepal.

INTRODUCTION: The biometric parameters of the eye are measured for the calculation of the intra ocular lens power to be used in cataract surgery. OBJECTIVE: To report the keratometry reading, axial length and intra ocular lens power used for eyes operated for cataract in Karnali Zone, Nepal, and to compare these findings with those reported in other similar studies. SUBJECTS AND METHODS: The data for the study were retrospectively collected from the case files of patients who had undergone cataract surgery between January 2011 and July 2012 in Karnali Zone, Nepal. These surgeries were performed in an outreach surgical camp organized by the Himalaya Eye Hospital, Nepal, as a part of its annual program. The SPSS 16.0 and Microsoft Excel 2007 software were used for the data analysis. RESULTS: The total number of patients taken for the study was 1055 and the total number of eyes was 1055. There were 530 (50.23%) males and 525 (49.77%) females, with the mean age of 64.34±11.25, ranging from 8 to 98 years.The mean keratometry reading for the total sample was 44.11±1.6 (range, 34.00D to 49.00D). The mean axial length for the total sample was 22.68±0.88 (range, 17.75 to 26.17). The mean IOL power for the total sample was 21.60±1.74 (range, +15.00 to +30.00). CONCLUSION: The biometric eye parameters of keratometry, axial length and IOL power of this study required for cataract surgery in a Karnali population are similar to those presented in other similar studies from Nepal and abroad.

Effect of isoelectronic substitution on magnetic properties of Ni(2)Mn(GaB) Heusler alloys.

We have studied the structural and magnetic properties of Ni(2)MnGa(1-x)B(x) Heusler alloys with 0≤x≤0.25 using x-ray diffraction, thermal expansion, electrical resistivity, and magnetization measurements. The magnetization measurements were made within the temperature interval of 5-400 K and at applied magnetic field of 0-5 T. The samples with low B concentrations (x<0.05) were found to be of the cubic L2(1) phase at 300 K. A martensitic phase along with the cubic L2(1) phase appears for x≥0.05, and the amount of the martensitic phase was found to increase with increasing x. The critical concentration of the boron substitution (within which Heusler phases exist) was found to be around x = 0.1. The cubic cell parameter was observed to decrease with increasing x in the interval 0≤x≤0.1. The alloys were ferromagnetically ordered at 5 K and the saturation magnetization (M(S)) was found to decrease with increasing boron concentration. The Curie temperatures (T(C)) and martensitic transition temperatures (T(M)) for the alloys with 0≤x≤0.25 have been determined and a phase (T-x) diagram has been constructed. T(M) increases rapidly and T(C) decreases slowly with increasing B concentration in the interval 0≤x≤0.1. The dependence of the phase transition temperatures and magnetization on B concentration is discussed.