Mechanical wear behavior of nanocrystalline and multilayer diamond coatings on temporomandibular joint implants

We used microwave plasma chemical vapor deposition to deposit nanocrystalline and multilayer (nanocrystalline/microcrystalline/nanocrystalline) diamond thin films on Ti-6AI-4V substrates imitating the condyle and fossa components of the temporomandibular joint. We tested the condyle/fossa pairs for wear in a mandibular movement simulator for an equivalent of two years of clinical use. Analysis of the wear surfaces by optical microscopy, scanning electron microscopy (SEM), and Raman spectroscopy showed that damage in both the films was minimal, no loss of film occurred and the wear performance was superior for the multilayer film. Comparisons with an uncoated condyle/fossa pair showed that the coated temporomandibular joint pairs had improved wear performance.     

Sphingolipid base metabolism. Sphinganine-1-phosphate lyase: identification of ethanolamine 1-phosphate as product

Ethanolamine 1-phosphate has been characterized as a product of the action of rat liver microsomal sphinganine 1-phosphate lyase on erythro-sphinganine 1-phosphate. The product was characterized by various forms of chromatography, gas-liquid chromatography-mass spectral analysis of appropriate derivatives, and by conversion to ethanolamine. The results of detailed studies of the mass spectral fragmentation of the tetra-trimethylsilyl derivative of ethanolamine 1-phosphate are also reported.     

Ultrasonic integrated backscatter coefficient profiling of human coronary arteries in vitro

A theoretical formulation for the profile of the integrated backscatter coefficient (IBC) is derived. This new formulation is based on a theoretical treatment. It includes correction for the diffraction of the ultrasonic beam and correction for the non-ideal nature of the reference signal. The inclusion of these correction factors permits accurate quantitative profiling of the IBC over the transducer focal zone. Experimental measurements are first performed on well-calibrated vessel-equivalent phantom materials and subsequently on human coronary arteries in vitro. A spherically focused 50.0 MHz f/1.83 transducer is used. IBC profiles are shown for three samples that are representative of early, mid, and advanced atherosclerotic coronary disease. The IBC profiles clearly differentiate the arterial tissues. However, variation between samples with histologically confirmed intimal thickening (N=24) was large. The mean IBC (±1 standard deviation), in (Sr.mm)^-1, for media, adventitia, and thickened intima were 3.86×10^-3, 1.53×10^-2, and 2.24×10^-2, respectively. The mean IBC of thickened intima is larger than previous measurements obtained from femoral arteries, and the mean IBC for media and adventitia layers are lower, reflecting differences in tissue composition between coronary and femoral vessels     

Electron beam irradiation effects on the mechanical, thermal and surface properties of a fluoroelastomer

Fluoroelastomer can be used as a sealing material for different purposes. The aim of this work is the evaluation of the effects of the ionizing radiation of an electron beam (EB) on the mechanical, thermal and surface properties of a commercial fluoroelastomer containing carbon black and inorganic fillers. The material was irradiated with overall doses between 10 and 250 kGy. Tensile strength (stress and strain at break), hardness (Shore A) and compression set were evaluated. Thermal behavior was evaluated by thermogravimetric analysis and differential scanning calorimetry. Surface modifications were inspected using scanning electron microscopy (SEM) and optical microscopy. The experiments have shown that EB irradiation promotes beneficial changes in the fluoroelastomer tensile strength behavior while compression set remain constant and the glass transition temperature increases. The SEM micrographs have shown compactness in the irradiated samples, although optical observations showed no surface morphology changes.     

Action planning in the presence of distracting stimuli: An investigation into the time course of distractor effects.

Humans have a remarkable capability to respond efficiently to a stimulus of interest despite other stimuli competing for neural resources. The current study investigated how the human system copes with distracting stimuli. During each trial, participants viewed 2 sequential stimuli that were each associated with a specific action based on an arbitrary mapping. The 1st stimulus served as a distractor, and the 2nd stimulus required a response (target). When the distractor preceded the target by more than a few hundred milliseconds, response latencies were slower when the 2 stimuli were associated with the same response. The authors propose that this negative compatibility effect stemmed from an inhibitory mechanism that the human system utilizes to prevent the distractor from eliciting an unwanted response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modelling gross primary production of a tropical semi-deciduous forest in the southern Amazon Basin

Semi-deciduous forest in the Amazon Basin is sensitive to temporal variation in surface water availability that can limit seasonal rates of leaf and canopy gas exchange. We estimated the seasonal dynamics of gross primary production (GPP) over 3 years (2005–2008) using eddy covariance and assessed canopy spectral reflectance using MODIS imagery for a mature tropical semi-deciduous forest located near Sinop, Mato Grosso, Brazil. A light-use efficiency model, known as the Vegetation Photosynthesis Model (VPM), was used to estimate seasonal and inter-annual variations in GPP as a function of the enhanced vegetation index (EVI), the land surface water index (LSWI), and local meteorology. Our results indicate that the standard VPM was incapable of reproducing the seasonal variation in GPP, primarily because the model overestimated dry-season GPP. In the standard model, the scalar function that alters light-use efficiency (ε_g) as a function of water availability (W_scalar) is calculated as a linear function of the LSWI derived from MODIS; however, the LSWI is negatively correlated with several measures of water availability including precipitation, soil water content, and relative humidity (RH). Thus, during the dry season, when rainfall, soil water content, and RH are low, LSWI, and therefore, W_scalar, are at a seasonal maximum. Using previous research, we derived new functions for W_scalar based on time series of RH and photosynthetic photon flux density (PPFD) that significantly improved the performance of the VPM. Whether these new functions perform equally well in water stressed and unstressed tropical forests needs to be determined, but presumably unstressed ecosystems would have high cloud cover and humidity, which would minimize variations in W_scalar and GPP to spatial and/or temporal variation in water availability.     

Human autoantibodies reveal titin as a chromosomal protein

Assembly of the higher-order structure of mitotic chromosomes is a prerequisite for proper chromosome condensation, segregation and integrity. Understanding the details of this process has been limited because very few proteins involved in the assembly of chromosome structure have been discovered. Using a human autoimmune scleroderma serum that identifies a chromosomal protein in human cells and Drosophila embryos, we cloned the corresponding Drosophila gene that encodes the homologue of vertebrate titin based on protein size, sequence similarity, developmental expression and subcellular localization. Titin is a giant sarcomeric protein responsible for the elasticity of striated muscle that may also function as a molecular scaffold for myofibrillar assembly. Molecular analysis and immunostaining with antibodies to multiple titin epitopes indicates that the chromosomal and muscle forms of titin may vary in their NH2 termini. The identification of titin as a chromosomal component provides a molecular basis for chromosome structure and elasticity.