Synthesis, spectroscopic characterizations and DFT studies on the metal complexes of azathioprine immunosuppressive drug

ABSTRACT. A complex of the immunosuppressive drug azathioprine with Cr(II), Mn(II), Fe(II), Zn(II), Cu(II), Ni(II), and Co(II) were synthesized and characterized through spectroscopic and thermal studies. The infrared spectra show the coordination of azathioprine via N(9) to the metal, also, the range around 640–650 cm−1 remains unchanged in the complexes, indicating the possibility that the ether group may not be involved in the binding. Thermogravimetric analysis (TG), thermogravimetric derivational analysis (DTG), and differential thermogravimetric analysis (DTA) have been studied in the temperature range from 0 °C to 1000 °C. The study of pyrolysis showed that all complexes decompose in more than one step and that the final decomposition product is metal oxide. The DFT (density functional theory) with B3LYP/6-31G++ level of theory was used to study the optimized geometry, HOMO→LUMO energy gap, and molecular electrostatic potential map of azathioprine before and after deprotonation.                 KEY WORDS: Azathioprine, Spectral study, Thermal study, Decomposition products, DFT Bull. Chem. Soc. Ethiop. 2022, 36(1), 73-84.                                                                   DOI: https://dx.doi.org/10.4314/bcse.v36i1.

Synthesis and Biological Activity of Novel Arylazothiazole Disperse Dyes Containing Selenium for Dyeing Polyester Fibers

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Evaluation and characterization of indigenous rice (Oryza sativa L.) landraces resistant to brown planthopper Nilaparvata lugens (Stål.) biotype 4

Evaluation and identification of resistant donors for brown planthopper (BPH) Nilaparvata lugens (Stål.), an economically important insect pest of rice, is a continuous process to develop new resistant rice varieties. However, several rice landraces of north-eastern India are not yet characterized for BPH resistance. In the present study, a set of 218 rice landraces were screened in both greenhouse and open-field conditions for three consecutive years, and thereafter forty selected promising entries were explored to evaluate their phenotypic and genotypic reactions against BPH biotype 4. Based on phenotypic evaluations, five landraces were identified as resistant, while 31 were moderately resistant, and grouped under the major cluster I and II, respectively, in a circular dendrogram. Antixenosis and antibiosis studies of these landraces divulged that, compared to the susceptible check variety, resistant landraces exhibited the lowest feeding rate, survival, and nymphal and adult settling, but higher frequency of unhatched eggs of BPH. Un-infested resistant landraces registered higher levels of ascorbic acid, oxalic acid and crude silica, however, elevated levels of total free amino acid, potassium and crude silica were observed under BPH herbivory. The present study focuses on identifying new donors having BPH resistance resources which could be useful in genomic studies for the development of BPH biotype 4 resistant rice varieties

ICT Uses, Constraints, and Challenges in Flash Flood Risk Management: A Case Study in North-Eastern Haor Areas of Bangladesh

This study intends to explore the extent of the use of information and communication technology (ICT) in flash-flood-prone haor (wetland ecosystem) areas of north-eastern Bangladesh. Addressing the situation of severe flash floods in 2017 at the community level, this study aims to examine the constraints and challenges in using ICT for flash flood risk management. An empirical study was conducted in two upazilas (administrative sub-districts) within the Sunamganj, the most affected district. A total of 120 household heads were interviewed using a semi-structured questionnaire. Focused group discussions (FGD) and key informant interviews (KII) were also used. Results reveal that people in these areas do not use computers or Internet. However, the use of mobile phones is common for communication during disasters. Illiteracy, poor quality of life, poor social capital, poor infrastructure, and poor communication with institutions are highlighted as the main constraints and challenges in the effective application of ICT in flash flood management. The results showed that the local community people of the study area receive early warning and hazards preparedness-related information through mobile phones, television, radio, and Facebook. However, the results also highlighted the constraints and challenges in applying ICT in DRR at the community level. By addressing a remote region and a relatively less focused disaster (flash flood), this study contributes to boosting the application of ICT in DRR, especially in remote, disadvantaged communities

Interactive Effects of Tillage Systems and Nitrogen Fertilizer Rates on the Performance of Mustard-Boro-aman Rice Cropping Systems under Conservation Agriculture Practices

In intensive crop production systems, sustainable agricultural development strives to find the balance between productivity and environmental impact. To reduce the N fertilizer-associated environmental risks of intensive cropping, sound agronomic and environmentally acceptable management practices are urgently needed. To attain high yields, improve soil health, and ensure economic return and N usage efficiency in conservation-based intensive agriculture, N management must be optimized, which has not yet been studied systematically in the mustard-boro rice-aman rice cropping pattern. During 2016/17, 2017/18, and 2018/19 cropping seasons in Bangladesh, cropping system experiments were conducted to investigate the interactive effects of tillage practices and nitrogen fertilizer rates on soil characteristics, crop productivity, and profitability under conservation agriculture (CA) systems. The trial featured two tillage systems: (i) conventional tillage (CT) and (ii) strip-tillage (ST). It also used three doses of N fertilizer: N1: 75% of the recommended N fertilizer dose (RND); N2: 100% of the RND; and N3: 125% of the RND. Each crop&rsquo;s experiment was set up in a split-plot design with three replications, with the main plot assigned tillage practices and the sub-plot assigned nitrogen fertilizer rates. For rice, neither the tillage systems nor the interactions between the tillage systems and N levels affected any of the growth parameters, yield, and yield components, but the N levels did. Across the tillage systems, the rice grain and straw yield were similar for the N levels of 100% RND and 125% RND, which were significantly higher than the N level of 75% RND. In mustard, the highest seed yield was recorded from the tillage system ST, with an N level of 125% RND, which was at par with the tillage system ST with 100% RND and CT with 125% RND. The highest system rice equivalent yield (SREY, 14.9 to 15.8 t ha&minus;1) was recorded from the tillage system ST, with an N level of 125% RND, which was at par with the same tillage system with an N level of 100% RND. The soil penetration and bulk density (BD) were higher for the CT than the ST, but soil organic matter (OM), total nitrogen (TN), phosphorus (P), potassium (K), and boron (B) content were higher for the tillage system ST than the CT. Across N levels, the tillage system CT had a 2&ndash;4% higher production cost than the ST. Total production cost increased as N levels increased across all tillage systems. The tillage system ST with an N level of 125% RND had the highest system gross return and net profit, which was at par with the same tillage system with 100% RND. This study suggested that farmers should apply slightly higher N for the mustard-boro-aman rice systems for the first couple of years when commencing CA; however, after a few years of consistent CA practice, the N rate may be reduced

Modification of Nutrient Requirements for a Four Crop-Based Cropping System to Increase System Productivity, Maintain Soil Fertility, and Achieve Sustainable Intensification

Sustainable and resilient cropping intensity is now a global focus to address the food demand and nutrition security of the growing population. For sustainable intensification, maintaining soil fertility is a key concern. The nutrient management for the recently developed four crop-based cropping system in Bangladesh has not yet been studied. Hence, field experiments were conducted on the nutrient management of the four crop-based cropping system [Aus (pre-monsoon rice), Aman (monsoon rice), lentil, and mungbean] in calcareous soil in Bangladesh during the years of 2016/17 and 2017/18 to determine the appropriate fertilizer management package to improve crop productivity and sustain soil fertility. The experiment had six treatments assigned in a randomized complete block design with three replications. The treatments included T1 = control (without synthetic fertilizer), T2 = 50% recommended dose of fertilizer (RDF), T3 = 75% RDF, T4 = 100% RDF, T5 = 125% RDF, and T6 = farmers&rsquo; practice (FP). The results revealed that the 125% RDF significantly contributed to higher yields of all four crops. The rice equivalent yield (REY) was the highest for the fertilizer management of 125% RDF, which was 45.5%, 9.4%, and 12.2% higher than the control (T1), 100% RDF (T4), and FP, respectively. Considering the uptake of nutrients (N, P, K, S, Zn, and B) by the crops in the cropping system, the 125% RDF was superior to the other treatments. The nutrient management practices had a positive influence on the apparent nutrient recovery (ANR) efficiency of the cropping system. The fertilizer management of 125% RDF was also economically more profitable due to the increment in the cost&ndash;benefit ratio of 26.8%, 4.4%, and 4.9% over the control, 100% RDF, and FP, respectively. The results indicate that the current fertilizer recommendations and FP for aus, aman, lentil, and mungbean are not adequate for the change from the three crop to the four crop-based pattern, and an increased dose of fertilizer is required to increase the yield of each individual crop as well as the total system&rsquo;s productivity. The fertilizer use efficiency is also higher for 125% RDF than the 100% RDF and FP indicating that to sustain the soil fertility in the four crop-based system, the current RDF and FP are not sufficient. This finding will help intensive cropping areas in preventing nutrient deficiencies that would lead to a reduction in the crop yield