Investigating the Mechanical Properties of RDX Crystals Using Nano‐Indentation

The shock sensitivity of RDX is of major interest for the development of insensitive munitions. Previous research has implied that internal defects that form within RDX crystals have a strong sensitising effect, increasing the probability of shock initiation. During the NATO Reduced sensitivity RDX Round Robin (R⁴) program the number of internal defects within RDX crystals of differing qualities were assessed by optical microscopy and a scoring system. The results suggested that RDX crystals with many internal defects were more sensitive. Studies investigating the mechanical properties of bulk RDX have shown that lots consisting of poorer crystals are weaker. This study investigates the mechanical properties of individual crystals from different RDX lots using nano‐indentation. It is shown that crystals with many internal defects have reduced modulus of elasticity, stiffness and prone to greater deformation under applied load. The results also show a correlation between these parameters and previously reported shock sensitivity data.     

Mussel Adhesion: Finding the Tricks Worth Mimicking

The byssus is a holdfast structure that allows the marine mussel (Mytilus) to adopt a sessile mode of life even in the most wave-swept habitats. The success of byssus as an adaptation for attachment is at least in part responsible for the fouling caused by these organisms, but it has also provided inspiration for the design of underwater adhesives and coatings. A valuable bio-inspired concept emerging from mussel adhesion is that of polymers with catecholic and phosphate functionalities for robust underwater surface coupling. Prepolymer processing by complex coacervation for good spreading and functional gradients is also likely to find applications.     

Mussel Adhesion: Finding the Tricks Worth Mimicking

The byssus is a holdfast structure that allows the marine mussel (Mytilus) to adopt a sessile mode of life even in the most wave-swept habitats. The success of byssus as an adaptation for attachment is at least in part responsible for the fouling caused by these organisms, but it has also provided inspiration for the design of underwater adhesives and coatings. A valuable bio-inspired concept emerging from mussel adhesion is that of polymers with catecholic and phosphate functionalities for robust underwater surface coupling. Prepolymer processing by complex coacervation for good spreading and functional gradients is also likely to find applications.     

Investigating the Effect of Si3N4 Reinforcement on the Morphological and Mechanical Behavior of AA2219 Alloy

Silicon - The present investigation aims to investigate the mechanical, metallurgical and morphological study of Aluminium Alloy AA2219 reinforced with various percentage of Si3N4 (0,3,6 and 9)...     

On the Worth of Perfect Information in Bandits with Random Discounting

Abstract

A discrete-time bandit process is a sequential decision problem in which one selects from a finite number of stochastic processes at each stage, and receives as a reward the product of the value of the observed process and a discount factor. In the classical formulation of the problem, the sequence of discount factors is known in advance, but the distributions governing the observations on the stochastic processes are not known. In this paper we consider the case in which the discount sequence is random and compare the reward of observers who have information about the discount sequence from the start with those who do not. In particular, we obtain bounds on the expected rewards for processes in which the discount sequence is random.     

Examining the True Cost of Cartridge Filter Change-out

John Hampton, Filtration Technology Corp, USA, and Guy Weismantel, Weismantel International, USA, consider the costs (both direct and indirect) associated with changing out cartridge filters used in hazardous applications, and discuss the contribution of these costs to the total cost of cartridge filter ownership and the benefits of using high capacity (HC) filters.     

Investigating the Effects of SiC Particle Sizes on Microstructural and Mechanical Properties of AA5059/SiC Surface Composites During Multi-Pass FSP

Silicon - Friction stir processing (FSP) is a quite recently developed solid-state process involving surface modifications for fabricating metal matrix surface composites (SCs). In this work, FSP...     

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《盛世牡丹》 品类：琉璃花瓶 规格：24cm×24cm×40cm 出品：宁波干玉水晶工艺品发展有限公司 “唯有牡丹真国色，花开时节动京城。”一幅国色天香的盛世牡丹，雍容华贵中带着自信，灵秀雅致中散发着张扬。     

Investigating the hydrophilicity of phenol formaldehyde foams: Effects of synthesis parameters

Open-cell phenol (P) formaldehyde (F) foams are used for various applications such as hydroponic seed germination, flower arrangements, and sound insulation. This study investigated the influence of various parameters such as F/P molar ratios, blowing agents, surfactants, wetting agents, polymeric and inorganic additives, and oxidizing agents on the hydrophilicity of PF foams. Experimental results indicate that an F/P ratio of 1.8 was ideal for producing phenolic foams with good foam structure, uniform pore distribution, and favorable mechanical properties. A mixture of pentane and hexane at a mass ratio of 1:3 (wt/wt) used as a blowing agent resulted in a foam with the lowest density. With the optimal foaming catalyst (p-toluene sulfonic acid) at a loading of 28 wt%, the foam exhibited a low density and excellent mechanical properties. A phenolic foam with a low density (39.27 kg/m³), high water absorption capacity (1210 wt%) and high open cell content (78.94%), was achieved by combining 6 wt% Tween-80 as the surfactant and 3 wt% sodium dodecyl sulfate as the wetting agent. Additionally, 6.5 wt% loading of H₂O₂ led to a slight decrease in the foam density (38.46 kg/m³), but with a remarkable improvement in the wetting characteristics (water absorption capacity—2404 wt% and nearly 100% open cell content of the produced foam.     

Investigating the electrochemical windows of ionic liquids

The structure effect on the electrochemical windows (EWs) was studied using cyclic voltammetry (CV) in 16 ionic liquids (ILs), consisting of various cations such as piperidinium, pyridinium, pyrrolidinium, phosphonium, morpholinium, ammonium, sulfonium and imidazolium, and anions including bis(trifluoromethylsulfonyl)imide, tris(pentafluoroethyl)trifluorophosphate, dicyanamide, trifluoroacetate and trifluoromethanesulfonate. It was found that all studied ILs have good EWs to be utilized as electrolytes in different electrochemical applications pertaining to industry. Furthermore, it was found that the structure of ILs affected the EW and both the cation and anion have important effect on the reductive and oxidative limits, respectively. The reductive limits of the studied ILs were found to follow the sequence of [P14,666]⁺ > [N112,1O2]⁺ > [HMPyrr]⁺ > [BMPyrr]⁺ > [EMIm]⁺ > [MOEMMor]⁺ ≈ [MOPMPip]⁺ > [S222]⁺ > [BMPy]⁺ ≈ [HPy]⁺ ≈ [HPPy]⁺. The oxidative limits were found to follow the sequence of [TFSI]^? > [TPTP]^? > [TfO]^? > [DCA]^? > [TFA]^?.