Influence of load on the tribological conditions in piston ring and cylinder liner contacts in a medium-speed diesel engine

The present work is an attempt to determine the oil film thickness in a medium-speed four-stroke diesel engine with a cylinder diameter of 200 mm. Experimental research on this topic was found necessary due to the limited amount of published information available with reference to engines of the present size. The experimental part of the study was carried out as firing engine tests, with an instrumented piston, equipped with telemetric data transmission, and an instrumented cylinder liner in a 6-in-line test engine. The study was carried out for different parts of the four-stroke working cycle and for different levels of engine power output. The results were compared with the results of computer simulations, carried out using a commercial software package. The conclusions of the study comprise aspects on the formation and development of the oil film between the rings and the liner under a set of load levels together with the periodical fluctuation during different strokes of the working cycle.     

Physically aggressive boys from ages 6 to 12: Family background, parenting behavior, and prediction of delinquency.

Boys from low socioeconomic environments were rated on physical aggression at ages 6, 10, 11, and 12 yrs by teachers and classified according to stability of fighting over time: stable high fighters, high fighters with late onset, desisting high fighters, variable high fighters, and nonfighters. The fighter groups differed from each other both in family background and parenting behavior. They were also significantly associated with delinquency across ages 10 to 14 yrs. A stepwise logistic regression with fighter groups, family adversity index, and parenting behavior variables as predictors showed that the Punishment?×?Fighter Group interaction, together with supervision, predicted self-reported delinquency. The study thus showed that the developmental pathways of physically aggressive behavior for boys in low socioeconomic environments were related to familial adversity and poor parenting, and that they predicted delinquency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

KLK3 in the Regulation of Angiogenesis—Tumorigenic or Not?

In this focused review, we address the role of the kallikrein-related peptidase 3 (KLK3), also known as prostate-specific antigen (PSA), in the regulation of angiogenesis. Early studies suggest that KLK3 is able to inhibit angiogenic processes, which is most likely dependent on its proteolytic activity. However, more recent evidence suggests that KLK3 may also have an opposite role, mediated by the ability of KLK3 to activate the (lymph)angiogenic vascular endothelial growth factors VEGF-C and VEGF-D, further discussed in the review.     

Abrasive wear of steel against gravel with different rock–steel combinations

Wear testing equipment and tests used in research laboratories are often miniature or simplified versions of real applications. For example standardized ASTM dry sand rubber wheel abrasion test G 65 and pin abrasion test G 132 are widely used to study materials’ abrasion wear resistance. The test results, however, do not always correlate too well with the results obtained from real wear conditions. One reason for this is, for example, that in the crushing applications of mining industry the abrasive size is usually much larger than that used in the laboratory wear tests. To study the abrasive wear caused by larger size gravel, new three-body abrasion test equipment was therefore constructed. The equipment uses the pin-on-disk principle with free abrasive particles of sizes up to 10 mm. During the test the pin is repeatedly pressed against a fixed amount of abrasive that is rotating with the disk having confining walls. As the pin is prevented from touching the counterbody, only the abrasive acts as the wearing agent.Three steels of different hardnesses were cross-tested as pin–disk pairs and as pins against a rubber disk using three igneous rock gravels with different crushability properties as abrasives. The wear was measured as mass loss from both the pin and the disk, and the rock comminution was measured by sieving. The results indicate that the mechanism of wear is greatly affected by the hardness of the counterbody. When using large size abrasives, the rate of comminution is also a very important factor that can significantly affect the wear test results.     

Upconversion fluorescence resonance energy transfer in a homogeneous immunoassay for estradiol

We recently described a novel homogeneous assay principle based on upconversion fluorescence resonance energy transfer (UC-FRET), where an upconverting phosphor (UCP) is utilized as a donor. The UC-FRET has now been applied to a competitive homogeneous immunoassay for 17beta-estradiol (E2) in serum, using a small-molecular dye as an acceptor. The assay was constructed by employing an UCP coated with an E2-specific recombinant antibody Fab fragment as a donor and an E2-conjugated small-molecular dye, Oyster-556, as an acceptor. Standard curves for the assay were produced both in buffer and in male serum. Sensitized acceptor emission was measured at 600 nm under continuous laser diode excitation at 980 nm. In buffer, the IC50 value of the assay was 1 nM and in serum 3 nM. The lower limits of detection (mean of zero calibrators, 3 SD) were 0.4 and 0.9 nM, respectively. The measurable concentration range extended up to 3 nM in buffer and 9 nM in serum. Equilibrium in the assay was reached in 30 min. The novel principle of UC-FRET has unique advantages compared to present homogeneous luminescence-based methods and can enable an attractive assay system platform for clinical diagnostics and for high-throughput screening approaches.     

In vitro fermentation of cereal dietary fibre carbohydrates by probiotic and intestinal bacteria

A range of probiotic and other intestinal bacteria were examined for their ability to ferment the dietary fibre carbohydrates β‐glucan, xylan, xylo‐oligosaccharides (XOS) and arabinoxylan. β‐Glucan was fermented by Bacteroides spp and Clostridium beijerinckii but was not fermented by lactobacilli, bifidobacteria, enterococci or Escherichia coli. Unsubstituted xylan was not fermented by any of the probiotic bacteria examined. However, many Bifidobacterium species and Lactobacillus brevis were able to grow to high yields using XOS. XOS were also efficiently fermented by some Bacteroides isolates but not by E coli, enterococci, Clostridium difficile, Clostridium perfringens or by the majority of intestinal Lactobacillus species examined. Bifidobacterium longum strains were able to grow well using arabinoxylan as the sole carbon source. These organisms hydrolysed and fermented the arabinosyl residues from arabinoxylan but did not substantially utilise the xylan backbone of the polysaccharide. Arabinoxylan was not fermented by lactobacilli, enterococci, E coli, C perfringens or C difficile and has potential to be an applicable carbohydrate to complement probiotic Bif longum strains in synbiotic combinations. © 2002 Society of Chemical Industry     

Assessing children's competence: Mothers' and teachers' ratings of competent behavior.

The purposes of this study were to test the replicability of the factor structure of the Health Resources Inventory (HRI; E. L. Gesten [see PA, Vol 57:7209]) for teachers, to describe the factor organization of the HRI when used with parents, and to assess the strength of agreement between parents' and teachers' views of children's competence. Parents' ratings were available for 269 children (ages 4 to 12 years), and teachers' ratings were gathered for a subset of 102. Analysis of teachers' responses confirmed a 5-factor structure of the HRI. The factor structure for mothers closely mirrored that of teachers. The similarity of factor structure argues for the usefulness of the HRI in assessing children's competence at home and school. The relatively modest correlation between mothers' and teachers' ratings suggests possible setting differences in children's behavior and/or variance related to rater source. (PsycINFO Database Record (c) 2010 APA, all rights reserved)