Bone loss in a new rodent model combining spinal cord injury and cast immobilization.

OBJECTIVES: Characterize bone loss in our newly developed severe contusion spinal cord injury (SCI) plus hindlimb immobilization (IMM) model and determine the influence of muscle contractility on skeletal integrity after SCI. METHODS: Female Sprague-Dawley rats were randomized to: (a) intact controls, (b) severe contusion SCI euthanized at Day 7 (SCI-7) or (c) Day 21 (SCI-21), (d) 14 days IMM-alone, (e) SCI+IMM, or (f) SCI+IMM plus 14 days body weight supported treadmill exercise (SCI+IMM+TM). RESULTS: SCI-7 and SCI-21 exhibited a >20% reduction in cancellous volumetric bone mineral density (vBMD) in the hindlimbs (p⋜0.01), characterized by reductions in cancellous bone volume (cBV/TV%), trabecular number (Tb.N), and trabecular thickness. IMM-alone induced no observable bone loss. SCI+IMM exacerbated cancellous vBMD deficits with values being >45% below Controls (p⋜0.01) resulting from reduced cBV/TV% and Tb.N. SCI+IMM also produced the greatest cortical bone loss with distal femoral cortical area and cortical thickness being 14-28% below Controls (p⋜0.01) and bone strength being 37% below Controls (p⋜0.01). SCI+IMM+TM partially alleviated bone deficits, but values remained below Controls. CONCLUSIONS: Residual and/or facilitated muscle contractility ameliorate bone decrements after severe SCI. Our novel SCI+IMM model represents a clinically-relevant means of assessing strategies to prevent SCI-induced skeletal deficits.

Simple theoretical analysis of the photoemission from quantum confined effective mass superlattices of optoelectronic materials.

The photoemission from quantum wires and dots of effective mass superlattices of optoelectronic materials was investigated on the basis of newly formulated electron energy spectra, in the presence of external light waves, which controls the transport properties of ultra-small electronic devices under intense radiation. The effect of magnetic quantization on the photoemission from the aforementioned superlattices, together with quantum well superlattices under magnetic quantization, has also been investigated in this regard. It appears, taking HgTe/Hg(1-) (x)Cd(x)Te and In(x)Ga(1-) (x)As/InP effective mass superlattices, that the photoemission from these quantized structures is enhanced with increasing photon energy in quantized steps and shows oscillatory dependences with the increasing carrier concentration. In addition, the photoemission decreases with increasing light intensity and wavelength as well as with increasing thickness exhibiting oscillatory spikes. The strong dependence of the photoemission on the light intensity reflects the direct signature of light waves on the carrier energy spectra. The content of this paper finds six different applications in the fields of low dimensional systems in general.

Further theoretical studies of modified cyclone separator as a diesel soot particulate emission arrester.

Soot particulate emission reduction from diesel engine is one of the most emerging problems associated with the exhaust pollution. Diesel particulate filters (DPF) hold out the prospects of substantially reducing regulated particulate emissions but the question of the reliable regeneration of filters still remains a difficult hurdle to overcome. Many of the solutions proposed to date suffer from design complexity, cost, regeneration problem and energy demands. This study presents a computer aided theoretical analysis for controlling diesel soot particulate emission by cyclone separator--a non contact type particulate removal system considering outer vortex flow, inner vortex flow and packed ceramic fiber filter at the end of vortex finder tube. Cyclone separator with low initial cost, simple construction produces low back pressure and reasonably high collection efficiencies with reduced regeneration problems. Cyclone separator is modified by placing a continuous ceramic packed fiber filter placed at the end of the vortex finder tube. In this work, the grade efficiency model of diesel soot particulate emission is proposed considering outer vortex, inner vortex and the continuous ceramic packed fiber filter. Pressure drop model is also proposed considering the effect of the ceramic fiber filter. Proposed model gives reasonably good collection efficiency with permissible pressure drop limit of diesel engine operation. Theoretical approach is predicted for calculating the cut size diameter considering the effect of Cunningham molecular slip correction factor. The result shows good agreements with existing cyclone and DPF flow characteristics.

Analysis and characterization of alumina particles reinforced ultra high molecular weight polyethylene composite for acetabular cup.

Composites of ultra high molecular weight polyethylene (UHMWPE) reinforced with 5, 10 and 15 percent of alumina were prepared by a technique of uniform mixing and moulding. Acetabular cups were produced by compression moulding methods. A new walk simulator was also developed in-house for testing the tribological performances of these cups. The results from walk simulator tests are encouraging. Using a human walk simulator machine we did in vitro wear testing. Characterizations were performed to analyse the microstructure, composition, phase purity and crystalline by using XRD, DSC/TGA. Biocompatibility test was done by cytotoxicity, hemocompatibility and MTT assay methods. Biocompatibility tests gave hemolysis counts with these polymer composites well within the acceptable range and the results indicate a significant improvement in biocompatibility of the polymer composites over the in parent polymers.

Evidence for covalent binding between copper ions and cyclodextrin cavity: a vibrational circular dichroism study.

Vibrational absorption and circular dichroism (VCD) spectra were obtained for parent cyclodextrins, hydroxyl deuterated alpha-cyclodextrin, cyclodextrin-copper complexes, and for the cyclodextrin inclusion complexes with Methyl Orange, methyloxirane, 1-propanol, and substituted cyclohexanones, in the solution phase. Changes in the VCD spectra, reflecting perturbations of cyclodextrin cavity, were found in the case of an inclusion complex with Methyl Orange, but for the remaining inclusion complexes measurable changes in VCD were not found. Significant changes observed in the VCD spectra of cyclodextrin-copper complexes suggest that the covalent binding of copper ions to the hydroxyl groups of cyclodextrin is involved.