A micro-chip exploding foil initiator based on printed circuit board technology

Conventional exploding foil initiator (EFI) in ignition or detonation applications hosts many performance advantages, but was hindered by the bulky, inaccurate, inefficient and expensive shortcomings. We highlight a novel micro-chip exploding foil initiator (McEFI) using printed circuit board (PCB) technology. The structural parameters were determined based on energy coupling relationship at the component interfaces. Next, the prototype McEFI has been batch-fabricated using PCB technology, with a monolithic structure of 7.0 mm (l) × 4.5 mm (w) × 4.0 mm (δ). As expected, this PCB-McEFI illustrated the successful firing validations for explosives pellets. This paper has addressed the cost problem in both military munitions and civil markets wherever reliable, insensitive and timing-dependent ignition or detonation are involved.

Recent advances in the synthesis of monolithic metal–organic frameworks

Although considerable achievements have been realized in recent years with respect to the syntheses of metal–organic frameworks(MOFs),majority of the developed MOFs are in the form of polydisperse microcrystalline powders,which cause dustiness,abrasion,and clogging and decrease pressure when used in industrial applications.Monolithic MOFs overcome these drawbacks and exhibit various promising characteristics.In this review,we present the recent advances associated with monolithic MOFs based on metal centers and a brief outline of the most prominent examples.Furthermore,the challenges and prospects associated with monolithic MOFs in terms of large-scale production and engineering applicability are analyzed based on our knowledge to conclude this review.

Review of the crushing response of collapsible tubular structures

Studies on determining and analyzing the crushing response of tubular structures are of significant interest,primarily due to their relation to safety.Several aspects of tubular structures,such as geometry,material,configuration,and hybrid structure,have been used as criteria for evaluation.In this review,a comprehensive analysis of the important findings of extensive research on understanding the crushing response of thin-walled tubular structures is presented.Advancements in thin-walled structures,including multi-cell tube,honeycomb and foam-filled,multi wall,and functionally graded thickness tubes,are also discussed,focusing on their energy absorption ability.An extensive review of experimentation and numerical analysis used to extract the deformation behavior of materials,such as aluminum and steel,against static and dynamic loadings are also provided.Several tube shapes,such as tubes of uniform and nonuniform(tapered)cross sections of circular,square,and rectangular shapes,have been used in different studies to identify their efficacy.Apart from geometric and loading parameters,the effects of fabrication process,heat treatment,and triggering mechanism on initiating plastic deformation,such as cutouts and grooves,on the surface of tubular structures are discussed.

PREPARATION OF POROUS NANOCOMPOSITE SCAFFOLDS WITH HONEYCOMB MONOLITH STRUCTURE BY ONE PHASE SOLUTION FREEZE-DRYING METHOD

Biodegradable porous nanocomposite scaffolds of poly（lactide-co-glycolide）（PLGA） and L-lactic acid（LAc） oligomer surface-grafted hydroxyapatite nanoparticles（op-HA） with a honeycomb monolith structure were fabricated with the single-phase solution freeze-drying method.The effects of different freezing temperatures on the properties of the scaffolds,such as microstructures,compressive strength,cell penetration and cell proliferation were studied.The highly porous and well interconnected scaffolds with a tunable pore structure were obtained.The effect of different freezing temperature（4℃,-20℃,-80℃and -196℃） was investigated in relation to the scaffold morphology,the porosity varied from 91.2%to 83.0%and the average pore diameter varied from（167.2±62.6）μm to（11.9±4.2）μm while theσ_（10） increased significantly.The cell proliferation were decreased and associated with the above-mentioned properties.Uniform distribution of op-HA particles and homogeneous roughness of pore wall surfaces were found in the 4℃frozen scaffold.The 4℃frozen scaffold exhibited better cell penetration and increased cell proliferation because of its larger pore size,higher porosity and interconnection.The microstructures described here provide a new approach for the design and fabrication of op-HA/PLGA based scaffold materials with potentially broad applicability for replacement of bone defects.