Assessment of radioactivity and radiological hazards associated with bricks in eastern Nepal.

This comprehensive study examines the concentration of natural radionuclides in bricks from the Terai region of the Koshi province, aiming to assess the radioactivity levels and associated radiological hazards, ultimately quantifying the dose limit. The average concentrations of 226Ra, 232Th, and 40K were 27.1 ± 5.7, 42.6 ± 9.8, and 601.5 ± 93.8 Bq/kg, with their respective contributions to total activity being 20.18 %, 45.35 %, 34.48 %,. Despite this, their concentration distribution followed the pattern 40K > 232Th > 226Ra. The elevated presence of 40K in the bricks is attributed to the use of phosphate fertilizers in the soil to enhance crop productivity. Notably, the calculated values of radiological hazard parameters, including radium equivalent activity, absorbed gamma dose, and effective dose, are well below the recommended safety thresholds. Consequently, this study suggests that bricks, when used in substantial quantities, pose no significant radiological risks and are considered safe for use as a building material. The extension of such investigations nationwide is recommended to assess the overall radioactivity levels and establish dose limits.

Assessment of radioactivity in sand samples from eastern Nepal in perspective of radiological hazards.

This study was conducted to investigate the activity concentrations of 226Ra, 232Th and 40K in the sand samples and the health hazards associated with them utilizing a NaI (Tl) gamma spectrometer. The average activity concentrations of 226Ra, 232Th and 40K were found to be 24.8 ± 10.1, 39.8 ± 16.4 and 531.3 ± 52.8 Bq kg-1, respectively. The calculated radiological hazard parameters, including radium equivalent activity, absorbed gamma dose and effective dose rate, were found to be 122.7 ± 34.0 Bq kg-1, 57.7 ± 14.9 nGy h-1 and 0.3 ± 0.1 mSv y-1, respectively. Notably, these results were observed to be below the recommended thresholds. Other measured hazard indices were also lower than the prescribed values. From a radiological perspective, the present study concludes that the sand samples do not pose any threat to human health when utilized as a building material.

A preliminary assessment of spatial variation of water quality of Ratuwa river.

This work helps to identify the source of pollution in water and characterize the water quality which is essential to water management for sustainable development. Therefore, the main objective of this work is to evaluate the spatial distribution of the water quality of Ratuwa river and its tributaries. The water samples were collected from six discrete sampling locations and fifteen parameters were tested using respective well-calibrated equipment and standard APHA methods. The physicochemical analysis, water quality index, and correlation matrix method were employed to evaluate the spatial variation of the water quality of Ratuwa river. Turbidity was the most polluting factor in river water. The results showed the spatial variation of the water quality index (WQI) from 39.3 to 70.5, which fell in the range of "good" to "poor" water quality status. None of the water samples was either "excellent" or "unsuitable for drinking." The water quality was "Poor" upstream and downstream of Ratuwa river due to the high value of turbidity. Chaju river was found to have unpolluted whereas Dipeni river was slightly polluted due to domestic and municipal wastes. Hence, the deterioration of water quality can be attributed to natural and anthropogenic sources.

N-Alkylated Analogues of Indolylthio Glycosides as Glycosyl Donors with Enhanced Activation Profile.

While studying indolylthio glycosides, previously we determined their activation profile that required large excess of activators. This drawback was partially addressed in the present study of N-alkylated SInR derivatives. The activation process was studied by NMR and the increased understanding of the mechanism led to a discovery of different activation pathways taking place with SIn versus SInR derivatives. Also investigated was orthogonality of the SInR leaving groups versus thioglycosides and selective activation of thioimidates over SInR glycosides.

Development of a Simple and Effective Lipid-A Antagonist Based on Computational Prediction.

Sepsis is a serious medical condition characterized by bacterial infection and a subsequent massive systemic inflammatory response. In an effort to identify compounds that block lipopolysaccharide (LPS)-induced inflammation reported herein is the development of simple Lipid-A analogues that lack a disaccharide core yet still possess potent antagonistic activity against LPS. The structure of the new lead compound was developed based on predictive computational experiments. LPS antagonism by the lead compound was not straightforward, and a biphasic effect was observed suggesting a possibility of more than one binding site. An IC50 value of 13 nM for the new compound was determined for the possible high affinity site. The combination of computational, synthetic, and biological studies revealed new structural determinants of these simplified analogues. It is expected that the acquired information will aid future design of LPS targeting glycopharmaceuticals.

Streamlined access to carbohydrate building blocks: Methyl 2,4,6-tri-O-benzyl-α-d-glucopyranoside.

Presented herein is an improved synthesis of a common 3-OH glycosyl acceptor. This compound is a building block that is routinely synthesized by many research groups to be used in glycosylation refinement studies. The only known direct synthesis by Koto lacks regioselectivity and relies on chromatography separation using hazardous solvents. Our improved synthetic approach relies on Koto's selective benzylation protocol, but it is followed by acylation-purification-deacylation sequence. Although this approach involves additional manipulations, it provides consistent results and is superior to other indirect strategies. Also obtained, albeit in minor quantities, is 4-OH acceptor, another common building block.

Indolylthio Glycosides As Effective Building Blocks for Chemical Glycosylation.

The S-indolyl (SIn) anomeric moiety was investigated as a new leaving group that can be activated for chemical glycosylation under a variety of conditions including thiophilic and metal-assisted pathways. Understanding of the reaction pathways for the SIn moiety activation was achieved via the extended mechanistic study. Also reported is how the new SIn donors fit into selective activation strategies for oligosaccharide synthesis.

Emission Measurements from Traditional Biomass Cookstoves in South Asia and Tibet.

Traditional biomass stoves are a major global contributor to emissions that impact climate change and health. This paper reports emission factors of particulate matter (PM2.5), carbon monoxide (CO), organic carbon (OC), black carbon (EC), optical absorption, and scattering from 46 South Asian, 48 Tibetan, and 4 Ugandan stoves. These measurements plus a literature review provide insight into the robustness of emission factors used in emission inventories. Tibetan dung stoves produced high average PM2.5 emission factors (23 and 43 gkg-1 for chimney and open stoves) with low average EC (0.3 and 0.7 gkg-1, respectively). Comparatively, PM2.5 from South Asian stoves (7 gkg-1) was in the range of previous measurements and near values used in inventories. EC emission factors varied between stoves and fuels ( p < 0.001), without corresponding differences in absorption; stoves that produced little EC, produced enough brown carbon to have about the same absorption as stoves with high EC emissions. In Tibetan dung stoves, for example, OC contributed over 20% of the absorption. Overall, EC emission factors were not correlated with PM2.5 and were constrained to low values, relative to PM2.5, over a wide range of combustion conditions. The average measured EC emission factor (1 gkg-1), was near current inventory estimates.