Instrumented indentation and scratch testing evaluation of tribological properties of tin-based bearing materials

This paper describes a study of some fundamental tribological behavior of two different tin-based bearing materials using scratch and Martens hardness techniques. The scratch test results obtained from the two different tin-based bearing materials were correlated with a function of scratch hardness and coefficient of friction. It is easily observed that the friction coefficients of WM5 are lower than those of WM2 under all scratch test conditions. Beside this, it is clearly distinguished that both materials give higher friction coefficients at higher normal loads and scratch velocities. Also it is found that scratch hardness values of the WM5 materials are higher than WM2 generally. Moreover, optical microscopy was used to determine the scratch hardness of two different tin-based bearing materials by examining the scratch widths. Scanning electron microscopic observations of two different tin-based bearing materials were performed in order to identify the scratch-deformation mechanisms and trace morphology. Beside scratch tests, Martens hardness tests were carried out to evaluate the indentation of materials by considering both the force and displacement during plastic and elastic deformation. By monitoring the complete cycle of increasing and removal of the test force, hardness values were determined.     

Sex hormones affect spatial abilities during the menstrual cycle.

The aim of this study was (a) to show that different measures of spatial cognition are modulated by the menstrual cycle and (b) to analyze which steroid is responsible for these cognitive alterations. The authors collected blood samples in 3-day intervals over 6 weeks from 12 young women with a regular menstrual cycle to analyze concentrations of estradiol, progesterone, testosterone, luteinizing hormone, and follicle-stimulating hormone. The performance on 3 spatial tests was measured during the menstrual and the midluteal phases. A significant cycle difference in spatial ability as tested by the Mental Rotation Test was found, with high scores during the menstrual phase and low scores during the midluteal phase. Testosterone had a strong and positive influence on mental rotation performance, whereas estradiol had a negative one. These results clearly indicate that testosterone and estradiol are able to modulate spatial cognition during the menstrual cycle. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental failure analysis of bolted joints in moisture‐ and temperature‐induced composite laminates under preload

In this study, an experimental investigation was carried out in a bolted glass fiber‐reinforced laminate under preload moments. The stacking sequence at the composite laminate was chosen as [90°/0°/45°/−30°]_s. The preload moments were selected as 2, 4, and 6 Nm, in order to compare the influence of preload moments on failure modes and strengths. Some specimens were subjected to hot pure water at 70°C for 7 days. The bearing strength in this case was measured again under the same preload moments of 2, 4, and 6 Nm. It is found that the bearing strength of the specimen waited in hot water was 5.4% smaller than that of the specimen in dry condition. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Hot-air optical turbulence generator for the testing of adaptive optics systems: principles and characterization

A statistically repeatable, hot-air optical turbulence generator, based on the forced mixing of two air flows with different temperatures, is described. Characterization results show that it is possible to generate any turbulence strength up to CN2 Dh approximately 6 x 10(-10) m1/3, allowing a ratio of beam diameter to Fried's parameter as large as D/r0 approximately 25 for one crossing through the turbulator or D/r0 approximately 38 for two crossings. The outer scale (L0 approximately 133 +/- 60 mm) is found to be compatible with the turbulator mixing chamber size (170 mm), and the inner scale (l0 approximately 7.6 +/- 3.8 mm) is compatible with the values in the literature for the free atmosphere. The temporal power spectrum analysis of the centroid of the focused image shows good agreement with Kolmogorov's theory. Therefore the device can be used with confidence to emulate realistic turbulence in a controlled manner. A calibrated CN2 profile, both in layer altitude and strength, is necessary for the testing of off-axis adaptive optics correction (multiconjugate adaptive optics). Testing was done to calibrate the CN2 profile using the slope detection and ranging technique. The first results, with only one layer, show the validity of the approach and indicate that a multiple-pass scheme is viable with a few modifications of the current setup.     

Screening-engineered field-effect solar cells

Photovoltaics (PV) are a promising source of clean renewable energy, but current technologies face a cost-to-efficiency trade-off that has slowed widespread implementation. (1, 2) We have developed a PV architecture-screening-engineered field-effect photovoltaics (SFPV)-that in principle enables fabrication of low-cost, high efficiency PV from virtually any semiconductor, including the promising but hard-to-dope metal oxides, sulfides, and phosphides. (3) Prototype SFPV devices have been constructed and are found to operate successfully in accord with model predictions.     

Polyols and chocolate technology: recent developments and advances

Reducing the sugar level in chocolate and developing low-calorie products are important for meeting consumer expectations, supporting public health and adapting to current consumption trends. However, the identification of bulking agents to be used for this aim is a critical factor. The most commonly used sugar alternatives for this aim are polyols. In this study, recent advances and developments for using possibilities of polyols in chocolate technology were discussed and future perspectives were highlighted. Partially and/or complete replacing of sugar with polyols can provide a low-calorie product. In addition, the use of mixtures consisting of more than one polyol is an approach that can be used in chocolate sugar substitution. Optimization of refining, conching and tempering processes by considering polyol type and content may contribute to the development of chocolate with improved quality properties and shelf life. However, polyol and bioactive compounds interactions and possible effects on bioaccesibility, bioavalibility and stability of these compounds in chocolate composition and pre- and post-digestion periods should be deeply investigated. In addition, the conching methods and conditions used is another factor to be considered in the use of polyols.     

Monotonic torsional resistance and fatigue resistance of novel SCOPE RS instruments

To evaluate monotonic torsional resistance and fatigue resistance of novel SCOPE RS instruments and to compare ROTATE, Hyflex CM, OneCurve, and ProTaper Next instruments as a counterpart. The instrument groups were as follows: SCOPE RS; ROTATE; HyflexCM; OneCurve; ProTaperNext. The cyclic fatigue resistance of unused instruments was tested at both room and body temperatures (n = 10). The time to fracture, the mean number of cycles until failure, and the length of the fractured fragments were analyzed. The monotonic torsional resistance of new instruments was measured in accordingly American National Standards/American Dental Association No. 28 and International Organization for Standardization 3630–1:2008 specifications (n = 10). The maximum torque and angular deflection at break were recorded. The fractographic examination was performed by scanning electron microscope. Energy‐dispersive X‐ray spectroscopy was used to investigate the microstructure of NiTi instruments. One‐way ANOVA with Games‐Howell Post Hoc multiple comparisons tests were used (p < .05). The ROTATE had superior cyclic fatigue resistance than other groups in both temperature conditions (p < .01). However, it exhibited lower torsional resistance than SCOPE RS (p < .01). SCOPE RS had superior torsional resistance than other groups (p < .01). Micrographs revealed typical features of fatigue behaviors in all groups. Weight percentages of the Ni and Ti revealed similarity for all instruments. The novel SCOPE RS instruments presented superior monotonic torsional resistance but failed to show any improvement in the cyclic fatigue resistance compared with its counterparts, ROTATE, HyflexCM, and OneCurve.     

Effects of particle size and sintering atmosphere on the structure and performance of 316L/SiC composite hollow fiber membranes

Journal of Porous Materials - 316L stainless steel hollow fiber membranes (HFs) are alternatives for polymer and ceramic based membranes. Chemical and waste treatment industries are application...     

The role of MRI in prostate cancer: current and future directions

Magnetic Resonance Materials in Physics, Biology and Medicine - There has been an increasing role of magnetic resonance imaging (MRI) in the management of prostate cancer. MRI already plays an...     

Treatment of dyehouse waste‐water by supercritical water oxidation: a case study

BACKGROUND: Supercritical water oxidation (SCWO) of dyehouse waste‐water containing several organic pollutants has been studied. The removal of these organic components with unknown proportions is considered in terms of total organic carbon concentration (TOC), with an initial value of 856.9 mg L^?1. Oxidation reactions were performed using diluted hydrogen peroxide. The reaction conditions ranged between temperatures of 400–600 °C and residence times of 8–16 s under 25 MPa of pressure. RESULTS: TOC removal efficiencies using SCWO and hydrothermal decomposition were between 92.0 and 100% and 6.6 and 93.8%, respectively. An overall reaction rate, which consists of hydrothermal decomposition and the oxidation reaction, was determined for the hydrothermal decomposition of the waste‐water with an activation energy of 104.12 ( ± 2.6) kJ mol^?1 and a pre‐exponential factor of 1.59( ± 0.5) × 10⁵ s^?1. The oxidation reaction rate orders for the TOC and the oxidant were 1.169 ( ± 0.3) and 0.075 ( ± 0.04) with activation energies of 18.194 ( ± 1.09) kJ mol^?1, and pre‐exponential factor of 5.181 ( ± 1.3) L^0.244 mmol^?0.244 s^?1 at the 95% confidence level. CONCLUSION: Results demonstrate that the SCWO process decreased TOC content by up to 100% in residence times between 8 and 16 s under various reaction conditions. The treatment efficiency increased remarkably with increasing temperature and the presence of excess oxygen in the reaction medium. Color of the waste‐water was removed completely at temperatures of 450 °C and above. Copyright © 2010 Society of Chemical Industry