Dong Thap University

We study the optical absorption coefficient in a Hartmann potential-confined quantum dot (QD), demonstrating that accounting for angular-radial coupling and excited states is important for the optical response. We solve the Schrödinger equation analytically, obtain a discrete spectrum, and use it to calculate intra- and inter-band transitions. The absorption spectra are determined by the structure of E_nℓ and its position with respect to the Fermi level, as well as temperature through Pauli blocking and thermal broadening. Larger angular quantum number ℓ leads to narrower radial level spacing and a systematic red-shift of the resonance peaks. We also demonstrate that r_0 and V_0 are useful tuning parameters: increasing r_0 diminishes confinement and leads to reduced level spacing, while increasing V_0 strengthens both the radial and angular components, with an increase in transition energies. These results show the flexibility of Hartmann confinement for tuning optical properties in non-central QD systems.

Climate variability is expected to alter global temperatures and precipitation, significantly impacting cassava (Manihot esculenta) water requirements. This study investigated the impacts of climate variability on rainfed cassava in the Song Hinh district, Phu Yen province of Vietnam, utilizing the CSM-MANIHOT-Cassava (Version 4.8) crop simulation model. The model was calibrated and validated using local field data, demonstrating strong model performance (R2 up to 0.93, RMSE of 12.84%, and NRMSE of 2.74% for root yield validation). Future cassava water requirements were simulated for the Vu Xuan and Vu He cassava crops under RCP4.5 and RCP8.5 scenarios for the 2025s, 2055s, and 2085s time windows, relative to a climate baseline of 1986-2005 and a crop parameter baseline of 2001-2021. The results revealed divergent trends in the cassava water requirements. Under the moderate RCP4.5 scenario, total cassava water requirements were projected to decrease for both Vu Xuan (by 11.8 to 16.9%) and Vu He (by 9.0 to 13.7%). In contrast, the high-emission RCP8.5 scenario indicated a significant eventual increase by 2085, with requirements rising by 13.6% for Vu Xuan and 21.3% for Vu He. These findings highlight the critical need for adaptive solutions. Adjusting planting schedules to better align with changing rainfall patterns emerges as a key strategy to sustain cassava production. For instance, under future scenarios, particularly RCP8.5, strategic adjustments such as delaying planting for Vu Xuan and advancing planting for Vu He could optimize water use efficiency and sustain cassava production in the Song Hinh district.

We investigate the optical absorption coefficient of spherical semiconductor quantum dots confined by a modified Kratzer-ring-shaped potential (MKRSP). The ring-shaped term introduces angular anisotropy that reshapes the low-lying spectrum and modifies dipole-allowed transitions beyond conventional radial confinement models. Analytical solutions of the Schr & ouml;dinger equation are obtained via the Nikiforov-Uvarov method, enabling closed-form evaluation of intra-and inter-band absorption. The confinement parameters r0 and V0 independently tune effective dot size and confinement depth, while the ring-shaped contribution activates additional transitions and enhances spectral weight. Increasing temperature reduces the occupation difference between states, suppressing intra-band peaks and broadening the spectra, whereas inter-band transitions remain comparatively robust. These results demonstrate that MKRSP confinement provides multi-parameter control of spectral position and oscillator strength beyond purely central potentials.

Promoting green service consumption is essential for advancing the sustainable development of the tourism industry. However, limited research has examined the underlying value-based mechanisms that shape tourists’ intention to choose environmentally friendly services in emerging markets. Employing the theory of consumption values, the study identifies values that influence tourists’ intention to select green services in Vietnam, and how external factors facilitate these values. A structured questionnaire survey was administered, with 514 valid responses. Using structural equation modeling (SEM), the study tests the relationships among publicity, virtual community engagement, green service values, and tourists’ intention to select green services. Social and epistemic values are determined as drivers of tourists’ preferences toward green services. Moreover, the study highlights the role of publicity and virtual communities in activating the values of green services, which is underexplored in prior studies. These findings offer novel theoretical insights into value-based green consumption behavior and provide practical implications for policymakers and managers seeking to foster pro-environmental choices among Vietnamese tourists.

We report new distributional records and natural history observations for three poorly known snake species of the ther, 1856) is newly recorded from Thanh Hoa and Vinh Phuc provinces, and G. pallidonuchale (Poyarkov, Nguyen et Vogel, 2019) is reported for the first time from Quang Tri and Quang Nam provinces. Additionally, Liopeltis stoliczkae (Sclater, 1891) is confirmed for the second time in Vietnam based on a specimen collected in Di Linh District, Lam Dong Province. These new records expand the known ranges of all three species and emphasise the need for continued herpetofaunal surveys in underexplored regions of northern and central Vietnam.