Role of non-timber forest products in sustaining forest-based livelihoods and rural households' resilience capacity in and around protected area- a Bangladesh study

People in developing world derive a significant part of their livelihoods from various forest products, particularly non-timber forest products. This article attempts to explore the contribution of NTFPs in sustaining forest-based rural livelihood in and around a protected area of Bangladesh, and their potential role in enhancing households resilience capacity. Based on empirical investigation our study revealed that, local communities gather a substantial amount of NTFPs from national park despite the official restrictions. 27 percent households of the area received at least some cash benefit from the collection, processing and selling of NTFPs, and NTFPs contribute as HHs primary, supplementary and emergency sources of income. NTFPs also constituted an estimated 19 percent of HHs net annual income, and were the primary occupation for about 18 percent of the HHs. HHs dependency on nearby forests for various NTFPs varied vis-a-vis their socio-economic condition as well as with their location from the park. Based on our case study the article also offers some clues for improving the situation in PA.Comment: To appear in Journal of Environmental Planning and Management, 201

Steady MHD Flow of Nano-Fluids over a Rotating Porous Disk in the Presence of Heat Generation/Absorption: a Numerical Study using PSO

In this paper, a numerical integration technique, based on particle swarm optimization is proposed to investigate the effects of internal heat generation/absorption, on MHD boundary-layer flow of different types of nano-fluids over a rotating disk with uniform suction. Thermo-physical properties are modeled based on a wide range of experimental data. In the model, effect of nature of base fluid, nature of nano-particle material, size of nano particle, concentration of nanoparticle in the base fluid, nano-thermal layer formed around the nano particle etc. are taken into consideration. The two dimensional non-linear partial differential equations governing the flow are reduced to a system of coupled non-linear ordinary differential equations by using similarity transformations. These non-linear equations have been solved by using shooting based integration technique along with particle swarm optimization. In this study, four different types of water bases nanofluids are compared with respect to heat transfer enhancement, and the effects of nano-particle concentration, nano-particle size and heat generation/absorption parameters are studied in detail. The effects of different parameters on the dimensionless velocity profile and temperature distribution are discussed graphically. It is found that out of the four nano fluids considered, the heat transfer rate for CuO water based nano fluid is highest. It is also concluded that small sized nano-particles, high suction and high heat absorption increase the heat transfer rate

Two-dimensional materials for improved resolution in total internal reflection fluorescence microscopy

We propose and theoretically demonstrate that two-dimensional materials at the interface between glass and water layers in a total internal reflection fluorescence microscopy (TIRFM) technique can decrease the detection volume of a target sample, and hence improve the resolution of the obtained image. In particular, we calculate the change in fluorescence characteristics of the fluorophore labels on a target sample when monolayer black phosphorus, hexagonal boron nitride, and graphene are added at the glass-water interface of a TIRFM structure. We also calculate the change in the detection volume due to the presence of two-dimensional materials, and when the polarization, wavelength, and angle of the incident light vary. We find $\gtrsim$ 10% and $\gtrsim$ 5% decrease in the detection volume when monolayer black phosphorus and hexagonal boron nitride are used, respectively, and up to  ~50% decrease when monolayer graphene is used. The proposed use of the two-dimensional material will significantly improve the resolution of TIRFM technique, and hence facilitate the study of nanoscale biological features

Colloidal Single-Layer Photocatalysts for Methanol-Storable Solar H₂ Fuel

Molecular surfactants are widely used to control low-dimensional morphologies, including 2D nanomaterials in colloidal chemical synthesis, but it is still highly challenging to accurately control single-layer growth for 2D materials. A scalable stacking-hinderable strategy to not only enable exclusive single-layer growth mode for transition metal dichalcogenides (TMDs) selectively sandwiched by surfactant molecules but also retain sandwiched single-layer TMDs' photoredox activities is developed. The single-layer growth mechanism is well explained by theoretical calculation. Three types of single-layer TMDs, including MoS2 , WS2 , and ReS2 , are successfully synthesized and demonstrated in solar H2 fuel production from hydrogen-stored liquid carrier-methanol. Such H2 fuel production from single-layer MoS2 nanosheets is COx -free and reliably workable under room temperature and normal pressure with the generation rate reaching ≈617 µmole g-1 h-1 and excellent photoredox endurability. This strategy opens up the feasible avenue to develop methanol-storable solar H2 fuel with facile chemical rebonding actualized by 2D single-layer photocatalysts