Controlled release of imatinib mesylate from PLGA microspheres inhibit craniopharyngioma mediated angiogenesis

Poly(lactic-co-glycolic acid) microspheres loaded with imatinib mesylate has been developed as a new therapeutic strategy to prevent craniopharyngioma recurrence. Microspheres composed of different lactic/glycolic acid ratios, molecular weights and drug compositions were synthesized and loaded with imatinib mesylate by modified double-emulsion/solvent evaporation technique and subsequently characterized by particle-size distribution, scanning electron microscopy, encapsulation efficiency and in vitro drug release. Inhibitory potential of imatinib containing microspheres on tumor neovascularization was investigated on craniopharyngioma tumor samples by rat cornea angiogenesis assay. Results showed that microspheres in different LA:GA ratios [LA:GA 50:50 (G50), 75:25 (G25), 85:15 (G15)] considerably reduced neovascularization induced by recurrent tumor samples in an in vivo angiogenesis assay (P < 0.01). Our data indicate that local delivery of imatinib mesylate to the post-surgical tumoral cavity using biodegradable microspheres may be a promising biologically selective approach to prevent the recurrence of craniopharyngiomas, via inhibition of neovascularization.     

Fabrication of stretchable and high-filtration performance melt-blown nonwoven webs for PM0.3 aerosol filtration

Polypropylene (PP) is a semi-crystalline polymer that displays simple manufacturing, high stiffness, lightweight, chemical resistance, and inexpensive. However, PP has significant drawbacks, such as poor brittleness at low temperatures, high shrinkage ratio, and low impact resistance, which limit its development. Thermoplastic polyurethane (TPU) possesses recyclable and eco-friendly characteristics, along with the elasticity of rubber and exceptional mechanical properties. In this study, a flexible and high-filtration performance PP-TPU textile material was developed by melt-blowing for filtering PM_0.3 aerosols. For the first time, a melt-blown PP-TPU nonwoven was used as an air filter. The fiber morphological studies exhibited that addition of 10 and 20 wt.% TPU into PP resulted in a fiber diameter increment from 0.94 to 1.24 μm. Also, melt-blown PP-TPU forms helical fibers, which are different from fibers noticed in melt-blown PP. Corona-charged double-layer 80PP-20TPU nonwovens have a filtration efficiency of 99.25% and quality factor (QF) of 0.13 mm H₂O⁻¹ at an air flow rate of 95 L/min. Moreover, PP's tensile strength was increased by 72.22%, and elongation was raised by 38.1% with the addition of 20 wt.% TPU. Thus, PP-TPU melt-blown composites may bring novel perspectives into the design and development of high-performance filtering materials for a variety of applications.     

Selective growth of Ge nanowires by low-temperature thermal evaporation

High-quality single-crystalline Ge nanowires with electrical properties comparable to those of bulk Ge have been synthesized by vapor-liquid-solid growth using Au growth seeds on SiO(2)/Si(100) substrates and evaporation from solid Ge powder in a low-temperature process at crucible temperatures down to 700?°C. High nanowire growth rates at these low source temperatures have been identified as being due to sublimation of GeO from substantial amounts of GeO(2) on the powder. The Ge nanowire synthesis from GeO is highly selective at our substrate temperatures (420-500?°C), i.e., occurs only on Au vapor-liquid-solid growth seeds. For growth of nanowires of 10-20?μm length on Au particles, an upper bound of 0.5?nm Ge deposition was determined in areas of bare SiO(2)/Si substrate without Au nanoparticles.     

Analysis of guided-resonance-based polarization beam splitting in photonic crystal slabs

We present an analysis of the phase and amplitude responses of guided resonances in a photonic crystal slab. Through this analysis, we obtain the general rules and conditions under which a photonic crystal slab can be employed as a general elliptical polarization beam splitter, separating an incoming beam equally into its two orthogonal constituents, so that half the power is reflected in one polarization state, and half the power is transmitted in the other state. We show that at normal incidence a photonic crystal slab acts as a dual quarter-wave retarder in which the fast and slow axes are switched for reflection and transmission. We also analyze the case where such a structure operates at oblique incidences. As a result we show that the effective dielectric constant of the photonic crystal slab imposes the Brewster angle as a boundary, separating two ranges of angles with different mechanisms of polarization beam splitting. We show that the diattenuation can be tuned from zero to one to make the structure a circular or linear polarization beam splitter. We verify our analytical analysis through finite-difference time-domain simulations and experimental measurements at infrared wavelengths.     

铝含量对AS系列铸造镁合金机械加工性能的影响(英文)

研究铝含量对AS系列铸造镁合金机械加工性能的影响。通过测量切削力和表面粗糙度对镁合金的机械加工性能进行评估。研究合金的微观结构和拉伸性能。结果表明,切削力随着铝含量的增加而增大;AS91镁合金的表面粗糙度和力学性能最高;对力学性能有影响的主要机制是存在金属间相Mg2Si和Mg17Al12。在机械加工镁合金中,切削力随着切割速度的增大而增大。所测得的数据与机械加工合金的力学性能一致。     

Effect of Cr and Zr on the grain structure of extruded EN AW 6082 alloy

The effects of Cr and Zr addition on the coarse grain surface layer in EN AW 6082 tube extrusions were investigated. The decoration of the tube surfaces and the weld seams with coarse recrystallized grains reflects the strain as well as the temperature gradients that predominate across the section of the tubes during extrusion. The recrystallization resistance provided by Mn does not suffice to avoid the coarse surface grains. With structural features that are almost identical to those of the base 6082 alloy, the 6082 alloy with 0.06 wt% Zr also fails to offer any improvement. The coarse grain surface layer is much thinner and recrystallization is entirely avoided across the weld seams upon the addition of 0.15 wt% Cr. The superior recrystallization resistance of the revised alloy is attributed to the increase in the population of the Cr-rich Al(Cr,Mn,Fe)Si as well as (Al, Si)₃Zr dispersoid particles. It is reasonable to conclude that the coaddition of Zr and Cr has a favourable impact on the resistance to recrystallization of EN AW 6082 alloy.     

Effect of Starch Induced Bacterial Growth and Amylase Production in Bacillus subtilis

The amylases produced by a Bacillus subtilis were purified from three different media which occurred nonstarch, starched and after eight hours shocked by starch media. Purified enzymes were compared each other Km, purification steps, thermal stability, pH and bacterial growth. In shocked medium, bacterial growth and amylase production are much more than in starched medium. The enzyme was stable at 65°C in three media. Km values were found different in three media where maltose inhibited the amylase activity. This inhibition is a competitive inhibition.