The cost-benefit analysis and constraints of pineapple production in Bangladesh

The main purpose of the study was to estimate the profitability of pineapple production in Sreemangal, Moulvibazar District. Structured questionnaires and face to face interviews were done to collect raw data from 100 pineapple farmers during harvesting season. These farmers were chosen using a multi-stage sampling approach. Net return analysis, Benefit-Cost Ratio, and Kruskal-Wallis One Way Analysis of Variance (ANOVA) were used to analyze the prepared data. Findings from net return analysis showed that pineapple production was a profitable activity in the study area. The total cost of production was Tk. 740,767 and the total return was also substantial, resulting in a net return of Tk. 501,445 for pineapple production. The Benefit-Cost Ratio (BCR) was 1.48, indicating that pineapple farming was profitable for the farmers. However, the study also discovered several constraints perceived by the farmers that hindered pineapple production. These constraints included issues like animal damage, lack of credit availability, natural calamities, labor supply shortages, expensive fertilizer, inadequate storage facilities, and poor seed quality. By mitigating these constraints, pineapple productivity may rise not just in the study area but also in other regions of Bangladesh where the fruit is grown intensively. Thus, this improvement could significantly contribute to the well-being of farmers and enhance their disposable income

Quantum Chemical Investigation of Light-Activated Spin State Change in Pyrene Coupled to Oxoverdazyl Radical Center

Low-spin ground states and low-lying excited states of higher spin were investigated for four pyrene oxoverdazyl monoradicals <b>1</b>–<b>4</b> and eight pyrene dioxoverdazyl diradicals <b>5</b>–<b>12</b>. The ground states for quartet and quintet spin symmetries that are in reality excited states were found in the region of 565–775 nm above the respective electronic ground states. We calculated the “adiabatic” magnetic exchange coupling constant in the electronic ground state of each isolated biradical (<b>5</b>–<b>12</b>) by unrestricted density functional theory. A number of hybrid functionals such as B3LYP, PBE0, M06, and M06-2X were used. We also used range-separated functionals such as LC-ωPBE and ωB97XD to compare their effects on the coupling constant and the relative energy of the high-spin state. Molecular geometries were optimized for the doublet and quartet spin states of every monoradical (<b>1</b>–<b>4</b>), and the broken symmetry and triplet solutions were optimized for every biradical (<b>5</b>–<b>12</b>), by systematically using 6-311G, 6-311G­(d,p), and 6-311++G­(d,p) basis sets with each functional. The geometry of each quintet diradical (<b>5</b>–<b>12</b>) was optimized using 6-311G basis set. B3LYP produced the best spin values. The excited state (quartet or quintet)–ground state energy difference (Δ<i>E</i>) increases in the presence of para-phenylene connectors. These energy differences were predicted here. The nature of spin coupling and consequently the ground state spin agree with spin alternation rule and the calculated atomic spin population. The adiabatic coupling constants were predicted for the biradicals (<b>5</b>–<b>12</b>) in their electronic ground states. Electron paramagnetic resonance parameters were determined at 6-311++G** level for the ground state and the quartet state of <b>1</b> and compared with the available experimental data. Low-lying excited states were found for the radical center (oxoverdazyl), pyrene, molecule <b>1</b>, and diradical <b>5</b> by time-dependent density functional theory (TDDFT) method using B3LYP hybrid, 6-311++G­(d,p) basis set, and the molecular geometry in the electronic ground state. Data from these calculations were used to discuss possible mechanisms for the achievement of the high-spin (excited) states in <b>1</b> and <b>5</b> and to predict a similar outcome for radicals <b>2</b>–<b>4</b> and <b>6</b>–<b>12</b> upon excitation. A comprehensive mechanism for the first excitation is proposed here. In particular, we show that the initial excitation of <b>1</b> involves large contributions from mixed transitions between pyrene and oxoverdazyl moieties, whereas the initial excitation of <b>5</b> is basically that of only the pyrene fragment. Subsequent internal conversion and intersystem crossing are likely to lead to the high-spin states of lower energy. Sample spin-flip TDDFT calculations were also done to confirm the energetic location and composition of the quartet state of <b>1</b> and the quintet state of <b>5</b>

Solvation of CO₂ in Water: Effect of RuBP on CO₂ Concentration in Bundle Sheath of C₄ Plants

An understanding of the temperature-dependence of solubility of carbon dioxide (CO₂) in water is important for many industrial processes. Voluminous work has been done by both quantum chemical methods and molecular dynamics (MD) simulations on the interaction between CO₂ and water, but a quantitative evaluation of solubility remains elusive. In this work, we have approached the problem by considering quantum chemically calculated total energies and thermal energies, and incorporating the effects of mixing, hydrogen bonding, and phonon modes. An overall equation relating the calculated free energy and entropy of mixing with the gas-solution equilibrium constant has been derived. This equation has been iteratively solved to obtain the solubility as functions of temperature and dielectric constant. The calculated solubility versus temperature plot excellently matches the observed plot. Solubility has been shown to increase with dielectric constant, for example, by addition of electrolytes. We have also found that at the experimentally reported concentration of enzyme RuBP in bundle sheath cells of chloroplast in C₄ green plants, the concentration of CO₂ can effectively increase by as much as a factor of 7.1–38.5. This stands in agreement with the observed effective rise in concentration by as much as 10 times

Catastrophic risk perceptions and the analysis of risk attitudes of Maize farming in Bangladesh

Risk perceptions and attitudes play a crucial role in agriculture. However, few researches on risk management have been conducted in developing countries. Therefore, keeping view on this knowledge gap, this research made an attempt to measure farmers' perceptions of catastrophic risks, their risk attitude and to assess the influence of farm and farm household features by using probit model, Equally Likely Certainty Equivalent approach and risk matrix. The data were collected through a stratified random sampling method where 350 maize farmers were interviewed from four different agro-ecological districts in Bangladesh. The results showed that most farmers had a risk averse attitude, and floods, heavy rains, pests, and diseases posed potential threats to maize production in the study area. Age, educational status, income, and land ownership were the key determinants for risk attitude while social and farm features play an insignificant role for the farmer's risk perceptions. The vibrant interpretations may further improve understanding of the risk management decisions and will help policymaker to better anticipate which farmer will adopt government support tool in the presence of traditional risk management tools. Also, the extension authority can improve their programs to guide the farmer in a better way to improve the risk management situation

Theoretical Investigation of Photomagnetic Properties of Oxoverdazyl-Substituted Pyrenes

We have investigated the ground state spin of 10 pairs of possible photochromic diradical isomers by quantum chemical methods. Dihydrogen pyrenes and dinitrile pyrenes have been chosen as spacers with radical centers attached at (1,7) and (1,8) locations. Oxoverdazyl has served as a radical center, and both C and N linkages have been investigated. Triplet molecular geometries have been optimized at the UB3LYP/6-311G­(d,p) level. Single-point calculations on triplet and broken symmetry states have been performed using the 6-311++G­(d,p) basis set. Careful designs have led to the prediction of strongly coupled dihydropyrene (DHP) isomers, and the cyclophenadiene (CPD) isomers have always been found as weakly coupled. The effect of the functional M06-2X has been investigated. Calculated TDDFT spectra have been sufficient to guarantee photochromism of the designed diradicals. It has been estimated that compounds of diradicals with large coupling constants in the DHP form would show a pronounced change in molar susceptibility on photoconversion. This has led us to identify two molecules that can serve as a photomagnetic switch at room temperature

Seven-quasiparticle bands in Ce-139

The high spin states in the Ce-139 nucleus have been studied by in-beam gamma-spectroscopic techniques using the reaction Te-130(C-12,3n)Ce-139 at E-beam=65 MeV. A gamma detector array, consisting of five Compton-suppressed Clover detectors was used for coincidence measurements. 15 new levels have been proposed and 28 new gamma transitions have been assigned to Ce-139 on the basis of gamma gamma coincidence data. The level scheme of Ce-139 has been extended above the known 70 ns 19/2 isomer up to similar to 6.1 MeV in excitation energy and 35/2h in spin. The spin-parity assignments for most of the newly proposed levels have been made using the deduced Directional Correlation from Oriented states of nuclei (DCO ratio) and the Polarization Directional Correlation from Oriented states (PDCO ratio) for the de-exciting transitions. The observed level structure has been compared with a large basis shell model calculation and also with the predictions from cranked Nilsson-Strutinsky (CNS) calculations. A general consistency has been observed between these two different theoretical approaches