Effect of Fiber Diameter and Air Gap on Acoustic Performance of Nanofibrous Membrane

The absorption of sound in the low frequency range is problematic with fibrous materials made up of coarser fibers. In that case, highly efficient sound absorption materials from much finer fibers must be developed. Although studies on the acoustic properties of conventional textile materials started in the nineties, analysis of the acoustic properties of the electrospun nanofibrous membranes is a novel subject. Nanofibrous membranes can improve acoustic insulation products by increasing the sound absorption coefficient, reducing material thickness, and decreasing material weight offering a competitive advantage. The purpose of this study is to analyze the effect of fiber diameter on the acoustic behavior of nanofibrous membranes.

Key changes in denervated muscles and their impact on regeneration and reinnervation

The neuromuscular junction becomes progressively less receptive to regenerating axons if nerve repair is delayed for a long period of time. It is difficult to ascertain the denervated muscle＇s residual receptivity by time alone. Other sensitive markers that closely correlate with the extent of denervation should be found. After a denervated muscle develops a fibrillation potential, muscle fiber conduction velocity, muscle fiber diameter, muscle wet weight, and maximal isometric force all decrease; remodeling increases neuromuscular junction fragmentation and plantar area, and expression of myogenesis-related genes is initially up-regulated and then down-regulated. All these changes correlate with both the time course and degree of denervation. The nature and time course of these denervation changes in muscle are reviewed from the literature to explore their roles in assessing both the degree of detrimental changes and the potential success of a nerve repair. Fibrillation potential amplitude, muscle fiber conduction velocity, muscle fiber diameter, mRNA expression levels of myogenic regulatory factors and nicotinic acetylcholine receptor could all reflect the severity and length of denervation and the receptiveness of denervated muscle to regenerating axons, which could possibly offer an important clue for surgical choices and predict the outcomes of delayed nerve repair.

Controllable diameter of electrospun nanofibers based on the velocity of whipping jets for high-efficiency air filtration

Electrospun nanofibers are regarded as a promising candidate for filtration because of their prominent size effect.The precise control of nanofiber diameter is the key to the material’s outstanding filtration capability,but it remains a challenge.Herein,an electrohydrodynamic scaling model is established for the accurate prediction of fiber diameter based on the velocity of the whipping jet.In this model,the velocity reflects jet stretching and is tuned by adding salt.The theoretical predictions agree well with the experimental results.With the proposed diameter model,the filtration property of the membrane is significantly optimized by governing the fiber diameter.When the nanofiber is slenderized to 183 nm,an ultralight (0.521 g m;) membrane exhibits high filtration efficiency (99.93%) and low pressure drop (105.2 Pa) against ultrafine aerosol particles (≤0.26μm) under an airflow face velocity of 5.33 cm s^(-1).These findings demonstrate that the established surface charge-based diameter model provides an excellent platform to timely and accurately control the nanofiber diameter via the velocity of whipping jets for highefficiency air filtration.

Prickle of Light-Weight Worsted Woven Wool Fabrics

Using the forearm test, the prickle of 26 commercially available light-weight worsted woven wool fabrics and 7 other fiber fabrics were studied under (24±1)℃ temperature and (65±5)% RH conditions. The surface fiber diameter of part of the wool fabrics was measured using a microscope. It was found that most of the light-weight worsted woven wool fabrics gave a prickle sensation under the above conditions. The prickle sensation was significantly correlated with the mean fiber diameter of the surface hairiness. It was also found that the prickle of the light-weight worsted woven wool fabrics was significantly correlated with the number of surface fibers which were coarser than 26 μm diameter.

Thermal Residual Stresses in W Fibers/Zr-based Metallic Glass Composites by High-energy Synchrotron X-ray Diffraction

Thermal residual stresses in W fibers/Zr-based metallic glass composites were measured by in situ high energy synchrotron X-ray diffraction(HEXRD). The W fibers for the composites were 300,500,and 700 m m in diameter,respectively. Coaxial cylinder model(CCM) and finite element model(FEM) were employed to simulate the distribution of thermal residual stress,respectively. HEXRD results showed that the selected diameters of W fiber had little influence on the value of thermal residual stresses in the present composites. Thermal residual stresses simulated by CCM and FEM were in good agreement with HEXRD measured results. In addition,FEM results exhibited that thermal residual stress concentrated on interface between the two phases and area where the two W fibers were the closest ones to each other.

Experimental investigation of cluster properties in dense gas-solid fluidized beds of different diameters

The local solid flow structure of a bubbling fluidized bed of sand particles was investigated m three different columns to characterize the properties of clusters. The experiments were performed using a reflective optical fiber probe. The variations in size, velocity, and void fraction of the clusters due to changes in the superficial gas velocity, particle size, and radial positions were studied. The results indicate that the velocity of the clusters remained unchanged while their size increased as the column diameter increased. In addition, the radial profile of the clusters＇ velocity did not depend on the radial position. The results indicate that larger particles form larger clusters, which move slower.

Extraction and characterization of bovine collagen Type V and its effects on cell behaviors

Collagen Type V(Col.V)plays an essential role in cell behaviors and has attracted increasing attention in recent years.Highpurity Col.V is needed for evaluating its biological properties.In this research,the enzymatic hydrolysis process was combined with ultrafiltration to purify Col.V from the bovine cornea.The purity of Col.V was determined to be above 90%by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and high-performance liquid chromatography methods.The effect of Col.V on cell behaviors was evaluated.The circular dichroism spectroscopy results demonstrated that the extracted Col.V exhibited a complete triple helix structure.SDS-PAGE suggested that the molecular weight of Col.V was 440 kDa.The self-assembly experiment revealed that the proportion of Col.V in the collagen mixture can affect the Col.I fiber diameter.The cell culture results implied that Col.V can inhibit fibroblasts(L929)proliferation.The L929 showed maximum mobility when the addition of Col.V was 30%.Thus,Col.V has the effect of inhibiting L929 proliferation and promoting migration.The high-purity Col.V provides useful information for further understanding its biological implications.