Kalimpong College, established in 1962, is the oldest college in Kalimpong, Darjeeling. It offers undergraduate courses in arts, commerce and science. It is affiliated with the University of North Bengal.
Biodegradable piezoelectric materials have emerged as promising candidates for sustainable energy harvesting in self-powered electronics. Present work reports a flexible chitosan-based piezoelectric nanogenerator (CPENG) fabricated through a simple solution-casting method using commercially available chitosan, an abundant natural biopolymer. The device exploits the intrinsic dipolar structure of chitosan to convert low-frequency mechanical stimuli into electrical energy via piezoelectric polarization and efficient charge separation. Under periodic finger tapping, the CPENG delivers a stable open-circuit voltage of ~ 18 V and a short-circuit current of ~ 1.0 µA, corresponding to a maximum power density of ~ 18 µW cm⁻². The device exhibits highly reproducible electrical signals, indicating stable dipole alignment and rapid charge transport during repeated mechanical deformation. Furthermore, the nanogenerator efficiently harvests energy from various ambient sources, including finger touch (~ 1.6 V), body vibration (~ 1.2–1.5 V), and airflow (~ 200–380 mV). The practical energy-storage capability is demonstrated by charging a 1 µF capacitor to ~ 2.3 V within 20 s, and the harvested energy is sufficient to illuminate 13 light-emitting diodes. These results highlight chitosan as an eco-friendly and efficient piezoelectric material for next-generation flexible and self-powered energy harvesting systems.
Abstract Background The tea plant, Camellia sinensis (L.) Kuntze, is the source of the world’s second most consumed beverage. Its leaves are severely damaged by two major sucking pests: the red spider mite, Oligonychus coffeae (Nietner) (Acari: Tetranychidae) and the tea mosquito bug, Helopeltis theivora Waterhouse (Hemiptera: Miridae), leading to significant crop and quality loss. This study investigates the metabolomic changes in tea leaves following infestation by these pests and analyzes the corresponding metabolites found in the pests’ guts using GC-MS. Results The gut contents of both pests were predominantly composed of fatty acid derivatives. Key compounds identified included 2-oxabicyclo[2.2.2]octan-3-one, myristic acid, caffeine, oleic acid, and palmitic acid. Comparative analysis revealed that twelve unique metabolites are present in the guts of both the red spider mite and the tea mosquito bug. Conclusion The alteration (increase, decrease, or de novo appearance) of these metabolites suggests that the pests’ enzymatic or microbial gut systems actively modify plant-derived compounds with insecticidal properties. For the first time in analyses of tea and insects, large quantities of 2-oxabicyclo[2.2.2]octan-3-one was found in the pests’ guts. However, because the pests feed on a variety of different plants, it may be a case of contamination, and further targeted analyses are required to confirm its origin and biological relevance.
In this study, we develop and analyze a compartmental SEIA (Susceptible–Exposed–Infected–AIDS) model that incorporates both horizontal (sexual) and vertical (mother-to-child) HIV transmission mechanisms. The model further includes the impact of Antiretroviral Therapy (ART) efficacy in slowing the progression from HIV infection to AIDS. While traditional numerical techniques are often used to study such epidemiological systems, we adopt a cutting-edge Physics-Informed Neural Network (PINN) framework to solve the system of nonlinear ordinary differential equations. The PINN method combines data-driven learning with the underlying biological laws to estimate system dynamics and unknown parameters more efficiently and accurately. Analytical investigation of the model ensures positivity, boundedness, and local stability of equilibria based on the basic reproduction number ( ℛ_0 ). Our results demonstrate that the HIV-free steady state is locally stable when the basic reproduction number ℛ_0 < 1 , but becomes unstable as ℛ_0 > 1 , giving rise to a stable HIV infected steady state. Sensitivity analyses show that the rate of sexual transmission and the effectiveness of ART significantly affect the long-term disease dynamics. Notably, increasing ART efficacy reduces the AIDS population substantially but does not eliminate the infected class entirely, indicating the persistence of the virus. Additionally, scenarios with strong vertical transmission exhibit delayed but sustained resurgence of infections even under high ART coverage, highlighting the challenge of latent reservoirs and therapy fatigue. The PINN-based simulations corroborate theoretical findings and reveal critical thresholds for ART efficacy and transmission rates. This hybrid mathematical-ML approach provides a powerful framework for studying infectious disease dynamics and optimizing public health interventions.
This study focuses on analyzing the hyper-order associated with meromorphic solutions of nonlinear complex differential equations represented by P[g] - Qg gamma P= R, where P[g] denotes a differential polynomial in g, gamma P indicates for the degree of P[g], and the coefficients of P[g], along with Q = Q(z) and R =R(z), satisfy certain prescribed growth conditions.
A Sporadic flowering in bamboos, particularly in species such as Dendrocalamus hamiltonii, poses significant ecological and economic implications. This short communication reports the recent observations of sporadic flowering events of D. hamiltonii in the Kalimpong district of West Bengal. The study aims to document the occurrence, potential causes, and impacts of these flowering events on local bamboo populations and associated communities.
