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.

Excessive iodine in iodized household salt in Nepal.

Iodine is an essential trace element required for the regulation of physiological processes involving the thyroid gland. However, inadequate and excessive intake of iodine are responsible for health problems, such as iodine deficiency disorders, hypothyroidism, hyperthyroidism, thyroiditis, thyroid papillary cancer, and thyrotoxicosis. The Universal Salt Iodization (USI) program has become successful in providing supplemental iodine at the population level globally. Packaging quality, fortification level, and transportation and storage conditions of iodized salt determine the availability of iodine. Previous studies have reported severe health issues caused by excessive iodine intake after the implementation of the USI program. To understand the levels of iodine, we collected 2117 household salt samples from seven districts of Nepal and tested them for iodine content; among them, 98.1% were iodized. Overall median concentration of iodine was 53.9 ppm (range: 43.5-61.4 ppm). The majority (67.2%) of samples had iodine in the range of 45-75 ppm. Approximately 0.9% of samples had inadequate, 13.3% contained adequate, and 83.9% had excessive iodine than the World Health Organization-recommended value. Iodine content varied among the sampling districts and seasons, to some extent. Our study confirmed that iodized salt is widely used in Nepal and is excessively iodized. Excessive intake of iodine through iodized salt requires further attention by policy makers. The iodine level may need adjustment to address the health impact.

Cellulose-based micro-fibrous materials imaged with a home-built smartphone microscope.

Micro-fibrous materials are one of the highly explored materials and form a major component of composite materials. In resource-limited settings, an affordable and easy to implement method that can characterize such material would be important. In this study, we report on a smartphone microscopic system capable of imaging a sample in transmission mode. As a proof of concept, we implemented the method to image handmade paper samples-cellulosic micro-fibrous material of different thickness. With 1 mm diameter ball lens, individual cellulose fibers, fiber web, and micro-porous regions were resolved in the samples. Imaging performance of the microscopic system was also compared with a commercial bright field microscope. For thin samples, we found the image quality comparable to commercial system. Also, the diameter of cellulose fiber measured from both methods was found to be similar. We also used the system to image surfaces of a three ply surgical facemask. Finally, we explored the application of the system in the study of chemical induced fiber damage. This study suggested that the smartphone microscope system can be an affordable alternative in imaging thin micro-fibrous material in resource limited setting.

Status of chemistry lab safety in Nepal.

Chemistry labs can become a dangerous environment for students as the lab exercises involve hazardous chemicals, glassware, and equipment. Approximately one hundred thousand students take chemistry laboratory classes annually in Nepal. We conducted a survey on chemical lab safety issues across Nepal. In this paper, we assess the safety policy and equipment, protocols and procedures followed, and waste disposal in chemistry teaching labs. Significant population of the respondents believed that there is no monitoring of the lab safety in their lab (p<0.001). Even though many labs do not allow food and beverages inside lab and have first aid kits, they lack some basic safety equipment. There is no institutional mechanism to dispose lab waste and chemical waste is disposed haphazardly. Majority of the respondents believed that the safety training should be a part of educational training (p = 0.001) and they would benefit from short course and/or workshop on lab safety (p<0.001).

Doping induced structural changes in colloidal semiconductor nanowires.

Undoped and Mn(2+)-doped CdSe nanowires (NWs) grown by a solution-liquid-solid (SLS) method using Bi nanocatalysts have been studied by X-ray powder diffraction measurements. Except for heavily doped nanowires no measurable changes in nanowire lattice parameters were observed. The lattice parameter of heavily doped nanowires shrinks by about 0.5% compared with the undoped ones, which corresponds to a doping concentration of 1.6%. For the other samples no change in lattice parameter is measured referring to a doping level much below 1%. Real structural parameters of nanowires were found to vary as a function of doping level, such as the zinc blende to wurtzite ratio, the static Debye-Waller factor, axial strain, and the number of stacking faults. Compared with the undoped nanowires the overall perfection is slightly improved for low doping but deteriorates drastically for higher doping. Our results highlight the importance of controlling the dopant concentration during the preparation of doped nanostructures.