Impact of light intensity on flowering time and plant quality of Antirrhinum majus L. cultivar Chimes White

Shades of different light intensities (29%, 43%, 54%,60% or 68%) along with control (no shade) were studied to observe their effects on the flowering time and plant quality. A hyperbolic relationship was observed between different light intensities under shade,and time to flowering.The total number of flower buds showed a curvilinear relationship with light intensities. Growth parameters related to the plant characteristics such as plant height,leaf area and plant fresh weight were improved under shading treatments at the expense of flowering time and number of flower buds.However,both linear and polynomial models applied assumed that cultivar Chimes White was equally sensitive to light intensity throughout development.     

Cells on chips

Microsystems create new opportunities for the spatial and temporal control of cell growth and stimuli by combining surfaces that mimic complex biochemistries and geometries of the extracellular matrix with microfluidic channels that regulate transport of fluids and soluble factors. Further integration with bioanalytic microsystems results in multifunctional platforms for basic biological insights into cells and tissues, as well as for cell-based sensors with biochemical, biomedical and environmental functions. Highly integrated microdevices show great promise for basic biomedical and pharmaceutical research, and robust and portable point-of-care devices could be used in clinical settings, in both the developed and the developing world.     

Anti-allergic effects of ethanol extracts from brown seaweeds

Ethanol extracts of brown seaweeds from Pakistan and China were isolated and compared for their antiallergenic activities. They included Sargassum tennerimum (ST) and Sargassum cervicorne (SC) from Pakistan, and Sargassum graminifolium turn (SG), Sargassum thunbergii (STH), and Laminaria japonica (LJ) from China. The ethanol extracts of these brown seaweeds were optimized at 85% (v/v) ethanol for the maximum yield of phlorotannin, an inhibitor against hyaluronidase. Total phlorotannins contained in the crude extracts were measured as 1.71% (SG), 0.74% (STH), 0.97% (LJ), 3.30% (SC), and 5.06% (ST). The 50% inhibitory concentrations (IC₅₀) of Pakistani SC and ST were 109.5 and 21 μg/ml, respectively, lower than those of Chinese SG, STH, and LJ (134, 269, and 148 μg/ml, respectively). An antiallergic drug, disodium cromoglycate (DSCG), had an IC₅₀=39 μg/ml, and a natural inhibitor of hyaluronidase, catechin, had an IC₅₀=20 μg/ml. The IC₅₀ of ST extract was found similar to that of catechin (21 vs 20 μg/ml) and lower than that of DSCG (21 vs 39 μg/ml). This suggests that ST is a potent inhibitor of hyaluronidase, indicating a promising future development of natural antiallergic medicines or functional foods.     

Silicon nanowires as efficient thermoelectric materials

Thermoelectric materials interconvert thermal gradients and electric fields for power generation or for refrigeration. Thermoelectrics currently find only niche applications because of their limited efficiency, which is measured by the dimensionless parameter ZT-a function of the Seebeck coefficient or thermoelectric power, and of the electrical and thermal conductivities. Maximizing ZT is challenging because optimizing one physical parameter often adversely affects another. Several groups have achieved significant improvements in ZT through multi-component nanostructured thermoelectrics, such as Bi(2)Te(3)/Sb(2)Te(3) thin-film superlattices, or embedded PbSeTe quantum dot superlattices. Here we report efficient thermoelectric performance from the single-component system of silicon nanowires for cross-sectional areas of 10 nm x 20 nm and 20 nm x 20 nm. By varying the nanowire size and impurity doping levels, ZT values representing an approximately 100-fold improvement over bulk Si are achieved over a broad temperature range, including ZT approximately 1 at 200 K. Independent measurements of the Seebeck coefficient, the electrical conductivity and the thermal conductivity, combined with theory, indicate that the improved efficiency originates from phonon effects. These results are expected to apply to other classes of semiconductor nanomaterials.     

热机械循环淬火调质处理对AISI 1345钢组织、力学和电化学性能的影响

Thermomechanical cyclic quenching and tempering (TMCT) can strengthen steels through a grain size reduction mechanism. The effect of TMCT on microstructure, mechanical, and electrochemical properties of AISI 1345 steel was investigated. Steel samples heated to 1050°C, rolled, quenched to room temperature, and subjected to various cyclic quenching and tempering heat treatments were named TMCT-1, TMCT-2, and TMCT-3 samples, respectively. Microstructure analysis revealed that microstructures of all the treated samples contained packets and blocks of well-refined lath-shaped martensite and retained austenite phases with varying grain sizes (2.8–7.9 μm). Among all the tested samples, TMCT-3 sample offered an optimum combination of properties by showing an improvement of 40% in tensile strength and reduced 34% elongation compared with the non-treated sample. Nanoindentation results were in good agreement with mechanical tests as the TMCT-3 sample exhibited a 51% improvement in indentation hardness with almost identical reduced elastic modulus compared with the non-treated sample. The electrochemical properties were analyzed in 0.1 M NaHCO₃ solution by potentiodynamic polarization and electrochemical impedance spectroscopy. As a result of TMCT, the minimum corrosion rate was 0.272 mm/a, which was twenty times less than that of the non-treated sample. The impedance results showed the barrier film mechanism, which was confirmed by the polarization results as the current density decreased.