An investigation of fracture and fatigue in a metal/polymer composite

This article presents the results of a combined experimental and analytical study of the fatigue and fracture behavior of a polymer/metal composite which was developed recently for self-lubricating applications in automotive engines that utilize liquefied natural gas as fuel. For comparison, the microstructure and the fatigue and fracture behavior of a nonpolymer-containing “matrix” material are also presented. Since the crack profiles observed in both systems under monotonic or cyclic loading reveal significant components of ligament bridging, micromechanics models are presented for the modeling of crack bridging. The resulting predictions of resistance-curve behavior are compared with measured resistance curves. The shielding effects of ligament bridging are also quantified under cyclic loading. The implications of the work are also discussed for the modeling of fatigue damage and fracture in polymer/metal coatings.     

Critical times in single-layer reaction diffusion

Reaction diffusion has applications to a wide range of areas, including industrial, geological, and medical problems. An important aspect is the phenomenon of ‘critical time’, which is a measure of how long the reaction and diffusion processes take. In this work, an exact solution using a linear reaction function is used to explore three critical time definitions. The outcome of the analysis is a simple, novel relationship between the reaction and diffusion time scales.     

平板电视在欧洲市场将大幅增长

据国外媒体报道,2005年,英国的数字电视家庭已经占欧洲全部数字电视家庭的42%,其中,英国是欧洲数字电视的“超级获胜者”。在英国,数字电视家庭用户普及率上升到53%左右;而德国目前通过普通有线电视可以收看50个频道,因此他们未曾感觉订购数字电视的优越性。     

Study of cellular adhesion with scanning acoustic microscopy

A mechanical scanning acoustic reflection microscope was applied to living cells (e.g., osteoblasts) to observe their undisguised shapes and to evaluate their adhesive conditions at a substrate interface. A conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. To characterize the cellular adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for 2 days, then assayed with the scanning acoustic reflection microscope. At 600 MHz the scanning acoustic reflection microscope clearly indicated that MC3T3-E1 cells cultured with MDA-MB-231 conditioned medium had both an abnormal shape and poor adhesion at the substrate interface. The results are compared with those obtained with laser scanning confocal microscopy and are supported by a simple multilayer model.     

Factors affecting agreement between severely mentally ill alcohol abusers' and collaterals' reports of alcohol and other substance abuse.

This study examined subject-collateral reports of alcohol use among a sample of 167 dually diagnosed individuals seeking outpatient treatment at a community mental health clinic. All subjects met Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) criteria for a schizophrenia-spectrum or bipolar disorder and for alcohol abuse or dependence. Subjects were recruited within 2 weeks of treatment entry and completed measures of cognitive functioning, alcohol dependence severity, psychiatric symptoms, and quantity and frequency of substance use over the previous 60 days using the Timeline Follow-Back interview (L. C. Sobell & M. B. Sobell, 1996). They also provided a urine sample, which was screened for recent drug use. Collateral interviews were conducted by phone and included an assessment of the subject's alcohol and drug use over the same 60-day period. Collaterals also reported their confidence in the accuracy of their reports. Overall, the results indicated generally poor subject-collateral agreement. However, subject-collateral agreement appeared better for those individuals (n = 97) with negative urine drug screens. The most consistent predictor of subject-collateral discrepancy scores was subjects' recent drug use. Recommendations for enhancing the validity of self-reports of substance use in a severely mentally ill population are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An investigation of the microstructure and strength of open-cell 6101 aluminum foams

This article presents the results of a study of the microstructure and strength of open-cell 6101 aluminum alloy fans with three different levels of pore size (measured in pores per inch (PPI)). The macrostructures and microstructures of open-cell foam struts are characterized using a combination of optical and scanning electron microscopy (SEM). The compositions of the individual phases are also determined via energy-dispersive spectroscopy (EDS). The variations in strut microhardness are then measured using Vickers microindentation techniques. Following the measurement of the mechanical properties of foams, a modified model is used to estimate the relative density from measured strut dimensions. The mechanisms of compressive deformation are then elucidated before presenting a discussion on unit-cell modeling, strut plastic deformation, and the relationships between strut microstructure and microhardness.     

A C-terminal di-leucine is required for localization of the Menkes protein in the trans-Golgi network

The human X-linked recessive disorder of copper metabolism, Menkes disease, is caused by a defect in the MNK ( ATP7A ) gene which encodes a transmembrane copper-transporting P-type ATPase (MNK). MNK is an important component of the mammalian copper transport pathway, and previous studies in cultured cells have localized MNK to the final compartment of the Golgi apparatus, the trans -Golgi network (TGN). At this location, MNK is predicted to supply copper to copper-dependent enzymes as they migrate through the secretory pathway. However, under conditions of elevated extracellular copper, the MNK protein undergoes a rapid relocalization to the plasma membrane where it functions in the efflux of copper from cells. In this study, three di-leucine motifs and a cluster of four acidic amino acids within the C-terminal region of MNK were investigated as candidate signals necessary for steady-state TGN localization. In vitro mutagenesis of the human MNK cDNA and immunofluorescence detection of mutant forms of MNK expressed in cultured cells demonstrated that the di-leucine, L1487L1488, was essential for localization of MNK within the TGN, but not for copper efflux. We suggest that this di-leucine motif is a putative endocytic targeting motif necessary for the retrieval of MNK from the plasma membrane to the TGN. Our data, along with the recent demonstration that the third transmembrane region of MNK functions as a TGN targeting signal, suggests that MNK localization to the TGN may be a two-step process involving TGN retention via the transmembrane region, and recycling to this compartment from the plasma membrane via the L1487L1488 motif.     

Munchausen syndrome by proxy: social work's role

Munchausen syndrome by proxy is the diagnosis used to describe a variation of child abuse whereby the parent or adult caregiver fabricates a medical history or induces symptoms in the child, or both, resulting in unnecessary examinations, treatments, hospitalizations, and even death. This article reviews the assessment procedures, provides case studies, and describes family dynamics of the syndrome. The authors make recommendations for team management of the child-family system and recommendations for social workers. They propose broadening the assessment of the family on the basis of knowledge of the widespread physical and economic oppression of women and children in our society.     

Ambiguity in the Operator's Sense

Ambiguity is a central problem for operators working in dynamic, high‐risk environments. Operators must decide on a course of action before knowing with certainty how the system will respond. Though ambiguity is expected, how it presents is unexpected. We reduce ambiguity when we can give meaning to information and events through use of context, responsiveness of the system, and when we can view events from a higher level. Preparation and training for routine operations helps identify potential ambiguities before events begin. The experienced operator engages the situation relying on real‐time experience to learn what works through action, thus further reducing ambiguity.     

Histochemistry in rat brain and spinal cord with an antibody directed at the cholecystokininA receptor

The role of D2/D3 receptors in striatum was electrophysiologically examined in vitro in chloralose-anesthetized rats. In addition, in vitro patch clamp method with rat brain slices was followed. Stimulations of the substantia nigra pars compacta (SN) in vivo elicited spike generation which was inhibited by microiontophoretically applied domperidone, a D2 antagonist. These domperidone-sensitive neurons were activated by microiontophoretic application of D2 agonists such as talipexole, quinpirole and bromocriptine as well as the D2 agonist, 7-OH-DPAT. They were also excited by either intravenous injection of bromocriptine or talipexole in a dose-dependent manner. Furthermore, the SN-induced increases in neuronal firing were blocked during microiontophoretic application of domperidone. In patch clamp whole-cell recording large-sized cells, identified visually under Ramanosky microscope, were depolarized with repetitive firing on bath application of talipexole and 7-OH-DPAT at a current clamp mode. Talipexole-induced depolarization in the large-sized cell was similarly observed in the presence of TTX and high Mg2+ in Ca(2+)-free physiological solution. In contrast, the medium-sized cells were hyperpolarized on bath application of talipexole without being affected by 7-OH-DPAT. These findings suggest that the large-sized cells, which were presumably cholinergic interneurons, are activated by dopamine derived from the SN via D2 and/or D3 receptors, while the medium-sized cells are inhibited by dopamine via D2 receptors.