The tribology (friction,lubrication and wear) of all-metal artificial hip joints

Total replacement of the human hip joint using artificial parts has now become a widely used treatment in many cases of osteoarthrosis and similar disabling conditions. This study was restricted to the McKee—Farrar type of joint, a ball-in-socket, where the parts were made from a cobalt—chrome—molybdenum alloy. A series of joints which had been removed from patients after service times of up to fourteen months were studied in several ways. The surface finishes of worn and unworn areas were compared, and the areas of contact plotted. Wear was deduced to be mainly abrasive, from entrapped particles formed firstly during “running-in”. The frictional torques, measured dynamically on a simulating machine, depended on the location of the contact area, minimum at “polar”, reaching high values at “equatorial”. A theory for this was proposed, and relevant clinical data was given also.     

Field transfer of periphytic diatom communities to assess short-term structural effects of metals (Cd,Zn) in rivers

Short-term effects of metal pollution were assessed by transferring periphytic diatom communities developed on artificial substrates from a reference site to a site polluted by heavy metals (around 15 microg Cd L(-1) and 800 microg Zn L(-1)), located in neighbouring streams. Metal sensitivity of mature assemblages (aged 1 month) was evaluated by studying changes in diatom density and taxonomic composition 2 and 4 weeks after the transfer. Resident communities of both sites were simultaneously collected on similar artificial substrates, in order to compare short-term effects of metals within transferred communities with long-term effects observed at the polluted site. Field transfer induced a marked shift of community structure towards that of the resident community of the polluted site: diatom density rapidly decreased after the transfer, from 35,000+/-4000 to 15,000+/-300 cells cm(-2) after 2 weeks, and taxonomic composition changed. Relative abundances of species characteristic of the reference site rapidly decreased, e.g. Nitzschia dissipata and Gomphoneis minuta, whereas species characteristic of the polluted site progressively increased within transferred communities, e.g. Gomphonema parvulum, Pinnularia sp. or Fragilaria crotonensis. The structure of periphytic diatom communities could therefore be an indicator of metal pollution, with marked taxonomic changes being identified within reference assemblages after only 2 weeks under relatively low metal exposure.     

Synthesis of FMOC-Protected S -arylcysteines and Modified Keratin Sequence Peptides as Specific Epitopes as Immunogens

The sulfhydryl group of cysteine residues is a site for the adduction of ultimate carcinogenic arene oxide metabolites to the proteins keratin 1 and keratin 10, dominant proteins of the squame. The putative cysteine adducts are: S -phenylcysteine, from benzene oxide and S -(1-naphthyl)- and S -(2-naphthyl)cysteine from naphthalene-1,2-oxide. In developing ELISAs for monitoring dermal exposures, we have embarked on synthesis of adducted head sequences GGRFSS(C*)GG (keratin 1) and GGGG(C*)GGGGG (keratin 10) by 9-fluorenyl-methoxycarbonyl chemistry to use in raising epitope-specific antibodies. Synthesis of the FMOC-protected cysteines was based on addition of arylthiols to 2-acetamidoacrylic acid, to give S -arylmercapturic acids. Removal of the N -acetyl group was accomplished quantitatively by extended refluxing in 1:1 t -butanol/concentrated HCl. FMOC derivatization of the S -arylcysteines was accomplished by a published procedure, modified because of the low solubility. The oligopeptides (C* = S -phenylcysteinyl residue) have been synthesized and characterized.     

Localized DC Field Produced by Diode Implanted in Isotropic Homogeneous Medium and Exposed to Uniform RF Field

Minimally invasive selective stimulation of biological tissue within the body can be achieved by implanting a small rectifying diode and then applying an RF field by means of electrodes or a coil on or near the surface of the body. A theoretical analysis of a simplified model consisting of a cylindrically symmetrical unit implanted in an isotropic homogeneous medium of conductivity ?and permittivity ? and exposed to a uniform RF field relates the dc component of electrode current to the detailed geometry of the electrodes of the implanted unit and to the amplitude of the applied field.     

Indoor carbon monoxide and PM2.5 concentrations by cooking fuels in Pakistan

Abstract Abstract In developing countries biomass combustion is a frequently used source of domestic energy and may cause indoor air pollution. Carbon monoxide (CO) and particulate matter with an aerodynamic diameter of 2.5 μm or less (PM_2.5) were measured in kitchens using wood or natural gas (NG) in a semi‐rural community in Pakistan. Daytime CO and PM_2.5 levels were measured for eight continuous hours in 51 wood and 44 NG users from December 2005 to April 2006. The laser photometer PM_2.5 (Dustrak, TSI) was calibrated for field conditions and PM_2.5 measurements were reduced by a factor of 2.77. CO was measured by an electrochemical monitor (Model T15v, Langan). The arithmetic mean for daytime CO concentration was 29.4 ppm in wood users; significantly higher than 7.5 ppm in NG users (P < 0.001). The arithmetic mean for daytime PM_2.5 concentrations was 2.74 mg/m³ in wood users; significantly higher than 0.38 mg/m³ in NG users (P < 0.001). Higher peak levels of CO and PM_2.5 were also observed in wood users. Time spent in the kitchen during fuel burning was significantly related to increasing CO and PM_2.5 concentrations in wood users. These findings suggest that cooking with wood fuel may lead to hazardous concentrations of CO and PM_2.5.     

The Rorschach: Toward a nomothetically based, idiographically applicable configurational model.

The authors argue that the Rorschach can and should be used best with a nomothetic foundation that adds an idiographic approach depending on the goal of the assessment. The research supporting this position is reviewed as are conceptual models that are advantageous to this conceptual position. The authors posit that method variance has a powerful impact on the measurement process. Each method is of value in some areas and of limited relevance in others. Self-report measures are most likely to be useful when interest is focused on consciously available and behavioral dimensions of functioning. Depth-oriented, indirect measures such as the Rorschach are most likely to be useful when interest is focused on unconscious, longitudinal, and structural dimensions of functioning. However, to have a full picture of human beings, heteromethod assessment is necessary to capture the full range of functioning and to implement the analytic model of assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)