Role of machining defects and residual stress on the AISI 304 fatigue crack nucleation

Machining defects as rebuilt material and dislodgement were often induced by cutting of difficult to machining AISI 304 stainless steel. Their density increases with a decreasing of cutting speed. The effect of these defects on surface topography and residual stress was evaluated by roughness and X‐ray diffraction measurements coupled with numerical simulation. The role of the rebuilt material on the distribution of fatigue crack nucleation sites was investigated by scanning electron microscope examination of post fatigue samples loaded at different imposed strain amplitudes. The association of machining defects and fatigue crack nucleation sites was attributed to the contribution of additional tensile residual stresses induced by rebuilt material rather than local stress concentration. Moreover, the fatigue crack coalescence is promoted by increasing the rebuilt material density. When the machining defect density increases from 5 to 60 particles/mm², the fatigue life decreases from ?22% to ?65% with respect to the electropolished surface.     

Damage evolution and infrared thermography in woven composite laminates under fatigue loading

An analytical model based on cumulative damage has been used for predicting the damage evolution in composite materials. The model is verified with experimental data from a carbon/epoxy composite fatigued under tension–tension load. Fatigue tests of specimens have been monitored with an infra-red thermography system. By analysing the temperature of the external surface during the application of cyclic loading, it is possible to evaluate the damage evolution. The model agrees well with the experimental data, and it can be used to predict the evolution of damage in composites.     

Reconstructing the flight kinematics of swarming and mating in wild mosquitoes

We describe a novel tracking system for reconstructing three-dimensional tracks of individual mosquitoes in wild swarms and present the results of validating the system by filming swarms and mating events of the malaria mosquito Anopheles gambiae in Mali. The tracking system is designed to address noisy, low frame-rate (25 frames per second) video streams from a stereo camera system. Because flying A. gambiae move at 1–4 m s⁻¹, they appear as faded streaks in the images or sometimes do not appear at all. We provide an adaptive algorithm to search for missing streaks and a likelihood function that uses streak endpoints to extract velocity information. A modified multi-hypothesis tracker probabilistically addresses occlusions and a particle filter estimates the trajectories. The output of the tracking algorithm is a set of track segments with an average length of 0.6–1 s. The segments are verified and combined under human supervision to create individual tracks up to the duration of the video (90 s). We evaluate tracking performance using an established metric for multi-target tracking and validate the accuracy using independent stereo measurements of a single swarm. Three-dimensional reconstructions of A. gambiae swarming and mating events are presented.     

The determination of volume ratios by gas depletion through multiple expansions

We present a new technique for the determination of the volume ratio of two vacuum chambers connected through a valve. The method is based on the measurement of the pressure in a chamber filled with a gas that is repeatedly depleted by expansion in a second chamber that was previously evacuated. Our calculation shows that under the reported measurement conditions, this technique has an uncertainty comparable to that obtained from the gas accumulation technique [Elliott KWT, Clapham PB.The accurate measurement of the volume ratios of vacuum vessels. NPL Report MOM 28, January 1978]. An excellent equivalence between the results obtained with this new technique and the measurements obtained by the gas accumulation technique is demonstrated.     

60]fullerene is a powerful antioxidant in vivo with no acute or subacute toxicity

In the present work, we report the effects of C(60)-pretreatments on acute carbon tetrachloride intoxication in rats, a classical model for studying free-radical-mediated liver injury. Our results show that aqueous C(60) suspensions prepared without using any polar organic solvent not only have no acute or subacute toxicity in rodents but they also protect their livers in a dose-dependent manner against free-radical damage. To be sure, according to histopathological examinations and biological tests, pristine C(60) can be considered as a powerful liver-protective agent.     

Application of top seeding in the melt processing of Nd<Subscript>123</Subscript> thick films on YSZ substrates: I buffer layer optimization

A new concept of a buffer layer in superconducting thick film technology was tested. The idea is based on increasing the NdBa₂Cu₃O_x melt viscosity at the processing temperature near the substrate by using higher ratios of Nd₄Ba₂Cu₂O_z solid phase in the first screen printed pass which is considered as a buffer layer. Different compositions, thicknesses and thermal schedules were used to optimise the buffer layer. The optimised buffer layer was employed in the fabrication of NdBa₂Cu₃O_y thick films on yttria stabilized zirconia (YSZ) substrates using the top seeding melt growth (TSMG) technique. Using the buffer layer was effective in preventing a large amount of liquid (BaCuO₂-CuO) from severe interaction with the substrate during the prolonged time in the TSMG technique. Consequently, a large superconducting single domain was obtained. Thick films were melt processed in 0.1% O₂ in Ar atmosphere to suppress the Nd_{1 + x}Ba_{2 − x}Cu₃O_y (Nd_123SS) solid solution formation. The produced thick films have high transition temperature (T_C) and improved microstructures.     

Stenting after optimal lesion debulking (sold) registry. Angiographic and clinical outcome

BACKGROUND: Coronary stenting has reduced restenosis in focal de novo lesions, but its impact has been less pronounced in complex lesion subsets. Preliminary data suggest a role for plaque burden in promoting intimal hyperplasia after stent implantation. The aim of this study was to test the hypothesis that plaque removal with directional atherectomy before stent implantation may lower the intensity of late neointimal hyperplasia, reducing the incidence of in-stent restenosis. METHODS AND RESULTS: Seventy-one patients with 90 lesions underwent directional atherectomy before coronary stenting. Intravascular ultrasound-guided stenting was performed in 73 lesions (81%). Clinical success was achieved in 96% of patients. Procedural complications were as follows: emergency bypass surgery in 1 patient (1.4%), who died 2 weeks later; Q-wave myocardial infarction in 2 patients (2.8%); and non-Q-wave myocardial infarction in 8 patients (11.3%). None of the patients had stent thrombosis at follow-up. Angiographic follow-up was performed in 89% of eligible patients at 5.7+/-1.7 months. Loss index was 0.33 (95% CI, 0.26 to 0.40), and angiographic restenosis was 11% (95% CI, 5% to 20%). Clinical follow-up was performed in all patients at 18+/-3 months. Target lesion revascularization was 7% (95% CI, 3% to 14%). CONCLUSIONS: Directional atherectomy followed by coronary stenting could be performed with good clinical success rate. Also, these data point to a possible reduction in angiographic restenosis and a significant reduction in the need for repeated coronary interventions. Therefore, a randomized clinical trial seems appropriate to test the validity of this approach.     

Cyclosporin C is the main antifungal compound produced by Acremonium luzulae

A strain of Acremonium luzulae (Fuckel) W. Gams was selected in screening new microorganisms for biological control of fruit postharvest diseases, especially gray and blue mold diseases on apples and strawberries. This strain manifests a very strong activity against a large number of phytopathogenic fungi. In this work, the product responsible for this antifungal activity was isolated from modified Sabouraud dextrose broth cultures of A. luzulae. It was purified to homogeneity by reverse-phase column chromatography. On the basis of UV, infrared, and 1H and 13C nuclear magnetic resonance spectra, mass spectral analysis, and the amino acid composition of the acid hydrolysates, the antibiotic was determined to be cyclosporin C. Cyclosporin C showed a broad-spectrum activity against filamentous phytopathogenic fungi but no activity against bacteria or yeasts. Its antifungal activity is only fungistatic. In contrast to Tolypocladium inflatum, another cyclosporin-producing strain, A. luzulae, did not produce additional cyclosporins. This was confirmed by in vivo-directed biosynthesis.     

Use of modelling for optimization and upgrade of a tropical wastewater treatment plant in a developing country.

This paper presents results of a novel application of coupling the Activated Sludge Model No. 3 (ASM3) and the Anaerobic Digestion Model No.1 (ADM1) to assess a tropical wastewater treatment plant in a developing country (Surat, India). In general, the coupled model was very capable of predicting current plant operation. The model proved to be a useful tool in investigating various scenarios for optimising treatment performance under present conditions and examination of upgrade options to meet stricter and upcoming effluent discharge criteria regarding N removal. It appears that use of plant-wide modelling of wastewater treatment plants is a promising approach towards addressing often complex interactions within the plant itself. It can also create an enabling environment for the implementations of the novel side processes for treatment of nutrient-rich, side-streams (reject water) from sludge treatment.