Effect of solid particle impact on light transmission of transparent ceramics: Role of the microstructure

2014 ◽  
Vol 37 ◽  
pp. 352-357 ◽  
Author(s):  
Lucile Lallemant ◽  
Vincent Garnier ◽  
Guillaume Bonnefont ◽  
Abdelhak Marouani ◽  
Gilbert Fantozzi ◽  
...  
Author(s):  
B.J. Panessa-Warren ◽  
G.T. Tortora ◽  
J.B. Warren

Some bacteria are capable of forming highly resistant spores when environmental conditions are not adequate for growth. Depending on the genus and species of the bacterium, these endospores are resistant in varying degrees to heat, cold, pressure, enzymatic degradation, ionizing radiation, chemical sterilants,physical trauma and organic solvents. The genus Clostridium, responsible for botulism poisoning, tetanus, gas gangrene and diarrhea in man, produces endospores which are highly resistant. Although some sporocides can kill Clostridial spores, the spores require extended contact with a sporocidal agent to achieve spore death. In most clinical situations, this extended period of treatment is not possible nor practical. This investigation examines Clostridium sporogenes endospores by light, transmission and scanning electron microscopy under various dormant and growth conditions, cataloging each stage in the germination and outgrowth process, and analyzing the role played by the exosporial membrane in the attachment and germination of the spore.


1987 ◽  
Author(s):  
J Arnout ◽  
A Van Hecken ◽  
I Delepeleire ◽  
Y Miyamoto ◽  
I Holmes ◽  
...  

Platelet activating factor (PAF) is a naturally occurring phospholipid with a wide spectrum of biological activities. Although PAF has been ascribed a potential role in various conditions including inflammation, asthma, glomerulonephritis and thrombosis, its precise function in physiologic/pathophysiologic processes remains unclear. The introduction of selective PAF receptor antagonists could represent a useful tool to extend our knowledge of the role of this mediator in health and disease.We have investigated the efficacy and tolerability of (RS)-2-methoxy-3-(octadecylcarbomoyloxy)propy1 2-(3-thiazolio)-ethyIphosphate (CV-3988, Takeda Chem. Ind), a selective PAF antagonist with structural analogies with PAF, after intravenous infusion in man in a double-blind, placebo-controlled study. The compound, in doses from 750 to 2,000 pg/kg, significantly reduced platelet sensitivity to PAF. The threshold aggregating concentration (TAC) of PAF was defined as the minimal concentration causing an irreversible aggregation with a maximal amplitude of at least 50% of the difference in light transmission between platelet rich plasma and platelet poor plasma. It increased in a dose-dependent manner reaching 3.6 times the basal TAC (p<0.0005) at the end and 2.60 times the basal TAC (p<0.0005) 4 hours after infusion of the highest dose. The TAC of PAF returned to the basal value within 24 hours after the end of the infusion.CV-3988 did not cause major side effects nor changes in blood pressure, pulse or respiratory rate. However, small but clinically insignificant changes in plasma haemoglobin and serum haptoglobin were seen at the end and four hours after the end of the infusion, indicating a slight haemolysis probably by high local concentrations at the infusion site.Our results indicate that, when adequate infusion volumes and infusion rates are used, CV-3988 can be safely administered to man and should be useful in elucidating the role of PAF in health and disease.


Author(s):  
Shijie Qian ◽  
Kuiying Chen ◽  
Rong Liu ◽  
Ming Liang

An advanced erosion model that correlates two model parameters—the energies required to remove unit mass of target material during cutting wear and deformation wear, respectively, with particle velocity, particle size and density, as well as target material properties, is proposed. This model is capable of predicting the erosion rates for a material under solid-particle impact over a specific range of particle velocity at the impingement angle between [Formula: see text] and [Formula: see text], provided that the experimental data of erosion rate for the material at a particle velocity within this range and at impingement angles between [Formula: see text] and [Formula: see text] are available. The proposed model is applied on three distinct types of materials: aluminum, perspex and graphite, to investigate the dependence behavior of the model parameters on particle velocity for ductile and brittle materials. The predicted model parameters obtained from the model are validated by the experimental data of aluminum plate under Al2O3 particle impact. The significance and limitation of the model are discussed; possible improvements on the model are suggested.


2019 ◽  
Vol 19 (6) ◽  
pp. 1739-1744 ◽  
Author(s):  
Bahman Taherkhani ◽  
Ali Pourkamali Anaraki ◽  
Javad Kadkhodapour ◽  
Nahid Kangarani Farahani ◽  
Haoyun Tu

Wear ◽  
1997 ◽  
Vol 203-204 ◽  
pp. 573-579 ◽  
Author(s):  
Y.I. Oka ◽  
H. Ohnogi ◽  
T. Hosokawa ◽  
M. Matsumura

Author(s):  
Amir Mansouri ◽  
Hadi Arabnejad Khanouki ◽  
Siamack A. Shirazi ◽  
Brenton S. McLaury

Solid particle laden flows are very common in many industries including oil and gas and mining. Repetitive impacts of the solid particles entrained in fluid flow can cause erosion damage in industrial equipment. Among the numerous factors which are known to affect the solid particle erosion rate, the particle impact speed and angle are the most important. It is widely accepted that the erosion rate of material is dependent on the particle speed by a power law Vn, where typically n = 2–3. Therefore, accurate measurements of abrasive particle impact speed and angle are very important in solid particle erosion modeling. In this study, utilizing a Particle Image Velocimetry (PIV) system, particle impact conditions were measured in a direct impinging jet geometry. The measurements were conducted with two different test rigs, for both air-sand and liquid-sand flows. In air-sand testing, two types of solid particles, glass beads and sharp sand particles, were used. The measurements in air-sand tests were carried out using particles with various sizes (75, 150, and 500 μm). Also, submerged testing measurements were performed with 300 μm sand particles. In the test conditions, the Stokes number was relatively high (St = 3000 for air/sand flow, St = 27 for water/sand flow), and abrasive particles were not closely following the fluid streamlines. Therefore, a Particle Tracking Velocimetry (PTV) technique was employed to measure the particle impact speed and its angle with the target surface very near the impact. Furthermore, Computational Fluid Dynamics (CFD) simulations were performed, and the CFD results were compared with the experimental data. It was found that the CFD results are in very good agreement with experimental data.


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