Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Tissue engineering applications commonly encompass the use of three-dimensional (3D) scaffolds to provide a suitable microenvironment for the incorporation of cells or growth factors to regenerate ...

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Three-dimensional scaffolds for tissue engineering applications : role of porosity and pore size

Glass fibers reinforced polymer composites have been prepared by various manufacturing technology and are widely used for various applications. Initially, ancient Egyptians made containers by glass...

Glass fiber-reinforced polymer composites – a review:

Poly(styrene-co-acrylonitrile) (SAN) was used to modify diglycidyl ether of bisphenol-A (DGEBA) type epoxy resin cured with diamino diphenyl sulfone (DDS) and the modified epoxy resin was used as the matrix for fibre reinforced composites (FRPs) in order to get improved mechanical and thermal properties. E-glass fibre was used as the fibre reinforcement. The morphology, dynamic mechanical and thermal characteristics of the systems were analyzed. Morphological analysis revealed heterogeneous dispersed morphology. There was good adhesion between the matrix polymer and the glass fibre. The dynamic moduli, mechanical loss and damping behaviour as a function of temperature of the systems were studied using dynamic mechanical analysis (DMA). DMA studies showed that DDS cured epoxy resin/SAN/glass fibre composite systems have two Tgs corresponding to epoxy rich and SAN rich phases. The effect of thermoplastic modification and fibre loading on the dynamic mechanical properties of the composites were also analyzed. Thermogravimetric analysis (TGA) revealed the superior thermal stability of composite system.

Morphology, dynamic mechanical and thermal studies on poly(styrene-co-acrylonitrile) modified epoxy resin/glass fibre composites

Melt electrospinning is a cheaper, more environmentally friendly, and safer alternative to solution electrospinning. We have designed a novel melt spinning device which incorporates a reverse of the normal polarity, with the capillary grounded and the collector grid at positive potential. The apparatus is much simpler and more economical than conventional equipment because no syringe pump is required. Low-density polyethylene (LDPE) with a low-melt flow index of 2 g/10 min, which is not suitable for spinning using current commercial methods, was chosen to highlight the advantages of melt electrospinning in general, and our device in particular. The effects of varying the electrospinning parameters such as temperature, electrostatic field, spinning distance, and capillary inner diameter, have been studied. Although it was found that temperatures higher than normal processing temperatures had to be employed in our electrospinning system to reduce the viscosity of the polymer melt sufficiently, good quality fibers with smooth and even surfaces, most of which had diameters smaller than 15 μm, were electrospun successfully. It was observed that there was an optimum point for the spinning distance (14–15 cm) and the capillary inner diameter (0.4–0.6 mm) to get fine fiber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Melt electrospinning of low‐density polyethylene having a low‐melt flow index

Here, the internal structure and mechanical properties of the hydroxyapatite/polycaprolactone scaffolds, prepared by fused deposition modeling (FDM) technique, were explored. Using hydroxyapatite (HA) and polycaprolactone (PCL) as raw materials, nano-HA/PCL and micro-HA/PCL that composite with 20 wt% HA were prepared by melt blending technology, and HA/PCL composite tissue engineering scaffolds were prepared by self-developed melt differential FDM 3D printer. From the observation under microscope, it was found that the prepared nano-HA/PCL and micro-HA/PCL tissue engineering scaffolds have uniformly distributed and interconnected nearly rectangular pores. By observing the cross-sectional view of the nano-HA/PCL scaffold and the micro-HA/PCL scaffold, it is known that the HA particles in the nano-HA/PCL scaffold are evenly distributed and the HA particles in the micro-HA/PCL scaffold are agglomerated, which attribute nano-HA/PCL scaffolds with higher tensile strength and flexural strength than the micro-HA/PCL scaffolds. The tensile strength and flexural strength of the nano-HA/PCL specimens were 23.29 MPa and 21.39 MPa, respectively, which were 26.0% and 33.1% higher than those of the pure PCL specimens. Therefore, the bioactive nano-HA/PCL composite scaffolds prepared by melt differential FDM 3D printers should have broader application prospects in bone tissue engineering.

3D printing of HA / PCL composite tissue engineering scaffolds

This article is a detailed review of the measures to modify the high-temperature mechanical properties of silicon carbide ceramic matrix composites (SiC CMCs), namely toughness, high-temperature stability and wear resistance Additionally, it briefly describes the common processing methods of the SiC CMCs and their application in the high-temperature field of aerospace The advantages and disadvantages of various existing processing and molding methods for the SiC CMCs are also discussed The high-temperature mechanical properties of the SiC CMCs are mainly affected by the properties of the matrix, added phase and interface It is crucial to reduce the crystal defects of the matrix and select a suitable enhancement phase for an elevated performance Moreover, it is important to improve the bonding at the interface between the enhancement phase and the matrix This review is expected to provide useful information for the subsequent development of complex SiC CMCs for high-temperature applications

Advances in modifications and high-temperature applications of silicon carbide ceramic matrix composites in aerospace: A focused review

Novel and unique applications of nanocellulose are largely driven by the functional attributes governed by its structural and physicochemical features including excellent mechanical properties and biocompatibility. In recent years, thousands of groundbreaking works have helped in the development of targeted functional nanocellulose for conductive, optical, luminescent materials, and other applications. The growing demand for sustainable and renewable materials has led to the rapid development of greener methods for the design and fabrication of high-performance green nanomaterials with multiple features, and consequently new challenges and opportunities. The present review article discusses historical developments, various fabrication and functionalization methods, the current stage, and the prospects of flexible energy and hybrid electronics based on nanocellulose.

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Weimin Yang

Papers

Morphology, dynamic mechanical and thermal studies on poly(styrene-co-acrylonitrile) modified epoxy resin/glass fibre composites

Melt electrospinning of low‐density polyethylene having a low‐melt flow index

3D printing of HA / PCL composite tissue engineering scaffolds

Advances in modifications and high-temperature applications of silicon carbide ceramic matrix composites in aerospace: A focused review

Current State of Applications of Nanocellulose in Flexible Energy and Electronic Devices