Motor recovery following spinal cord injury associated with cervical spondylosis: a collaborative study

A prospective multicenter study was conducted within the National Model Spinal Cord Injury System program to examine neurological deficits and recovery patterns following spinal cord injury (SCI) in individuals with cervical spondylosis and without a spinal fracture. Nineteen patients were evaluated. Sixty-eight percent presented initially with motor incomplete lesions. Of those who presented with motor incomplete injuries at their initial examination, 69 percent had less deficit in the lower than in the upper extremities, indicative of a central cord syndrome. At follow-up, 12 subjects were unable to ambulate, four required assistance and three were able to ambulate independently. On the average, subjects doubled their initial Asia Motor Score (AMS) scores by one year following injury. Residual upper extremity weakness, however, limited the ability to ambulate. Recovery of motor strength in this group is comparable to that of individuals with incomplete tetraplegia in general but the proportion who regain ambulatory function is less.     

Adsorption of methimazole on the mercury electrode

The electrosorption behaviour of methimazole (vetranal) at the mercury/1 M NaClO₄ interface was determined from a double layer differential capacity measurements extrapolated to zero frequency. Methimazole is the thiourea derivative, which is used as a drug in the overactivity of the thyroid gland. The values of zero charge potential were shifted to negative potentials ca. 230 mV with an increasing methimazole concentration from 10⁻⁴ M to 10⁻¹ M. The relative surface excesses Γ′ of methimazole were calculated from surface pressure at the density of surface charge σ = constant. The values of Γ′ increase with the increase of σ. Adsorption of methimazole was analyzed on the basis of the constants obtained from the Frumkin and virial isotherms. The values of the standard Gibbs energy of adsorption ΔG° increase with the increase of σ while the values of interaction parameters A and B decrease.     

A micro-volume viscosity measurement technique based on μPIV diffusometry

Liquid viscosity is a vital metric in numerous biochemical applications. A precise bio-assay often needs to determine viscosity prior to processing. This article presents a simple viscosity measurement technique based on the μPIV diffusometry. Assessing Brownian motion of neutrally buoyant particles in a micro-sized chamber provides a fast link to the liquid viscosity. The ensemble cross-correlation algorithm was used to extract the viscosity information out of a series of particle images. The width of a correlation peak decreased with the increased viscosity. For an accurate measurement, the study also evaluated deviations resulting from hindered diffusion. A correction factor was obtained by comparing the measured viscosity of glycerol solutions with the reference data. A calibration curve was made to fix the shifted measurements. The advantages of this technique are as follows: small volume (<1 μL), noninvasiveness, ease of use, and low cost. The good agreement between the data measured from the μPIV system and a commercial viscometer validated the approach. To prove the effectiveness, the technique was used to study the viscosity change of dextran solutions and its effect on the kinematics of the micro-swimmer, Caenorhabditis elegans. A broad range of viscosity measurements (>10³ mPa s) were achieved. The demonstration confirms the possible use of the technique in other biological applications that requires broad-range and small-volume measurement capabilities for viscosity.     

Effects of carbon nanofibers on the fracture,mechanical, and thermal properties of PP/SEBS‐g‐MA blends

Polypropylene/maleated (styrene‐ethylene‐butadiene‐styrene) (PP/SEBS‐g‐MA) blends reinforced with 0.2–2.5 wt% carbon nanofibers (CNFs) were prepared by injection molding. The structure, thermal, mechanical, and fracture behaviors of PP/SEBS‐g‐MA blends and their nanocomposites were studied. Wide‐angle X‐ray diffraction (WAXD) results showed that the SEBS‐g‐MA and/or CNF additions do not induce a structural change of PP. Tensile measurements showed that the Young's modulus and tensile yield strength increase with the increasing filler content. Izod impact and essential work of fracture test results demonstrated that CNFs are beneficial to improve the impact strength and specific essential work of fracture of PP/SEBS‐g‐MA blends. Therefore, tough PP‐nanocomposites can be achieved by melt‐blending low fractions of CNFs and appropriate elastomer contents. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Surveillance et cartographie des plans d'eau et des zones humides et inondables en régions arides avec l'instrument VEGETATION embarqué sur SPOT-4

Résumé.?L'observation régulière de l'état des petits plans d'eau et des zones humides est très utile dans les régions arides et semi-arides, car leur existence est entièrement contrôlée par le rythme des pluies. Sur les images en composition colorée des données VEGETATION les plans d'eau et les bas-fonds sont clairement identifiables. Une simple classification de la signature spectrale des zones observées ne suffit pas à les repérer car les conditions écologiques varient énormément de même que le comportement radiométrique. Dans cette étude, une méthode contextuelle basée sur le contraste local a été élaborée et testée. Une validation systématique a été menée et une carte des plans d'eau et des zones humides a été produite pour le Burkina Faso et les régions voisines.

Monitoring the state of small waterbodies and wetlands is very useful in dry regions, because their existence is entirely controlled by the rhythm of local rainfall. On VEGETATION image colour composites, waterbodies and marshy vegetation show up clearly. Yet simple image classification does not yield sufficiently good results because ‘spectral signatures' vary significantly together with the ecological conditions of these surfaces. A robust contextual procedure taking into account local contrast was successfully developed and tested. A systematic validation was carried out and a map of waterbodies and wetlands was produced for Burkina Faso and neighbouring regions.     

Flow of a Newtonian fluid and a yield stress fluid around a plate inclined at 45° in interaction with a wall

This experimental and numerical study focuses on the determination of drag and lifts forces acting on inclined plate at 45° placed near a wall in a uniform flow of Newtonian and yield stress fluid. The inertia of the fluid is considered negligible. The influences of yield stress, shear thinning, and the distance between the plate and the wall were examined precisely. It is shown that the drag and lift coefficients decrease as the Oldroyd number increases and increase as the gap decreases. The unyielded zones around the plate were also determined. Their surfaces increase with the Oldroyd number. When the yield stress is low, the decrease of the shear thinning index n tends to decrease these unyielded zones. For the experimental part, a Carbopol gel was used as a fluid model. Experimental measurements were compared with numerical and published results, particularly in the plasticity context developed for soil mechanics. Differences are discussed in terms of the influence of elasticity and plasticity.     

Heat-treated platinum nanoparticles embedded in nitrogen-doped ordered mesoporous carbons: Synthesis, characterization and their electrocatalytic properties toward methanol-tolerant oxygen reduction

Fabrication of N-doped ordered mesoporous carbons containing well-dispersed and methanol-tolerant Pt nanoparticles (Pt-NOMC) via an easy route is reported in this paper. These Pt-NOMC samples invoke the pyrolysis of co-fed carbon sources and Pt precursor with various carbonization temperatures (Pt-NOMC-T) in 3-[2-(2-Aminoethylamino)ethylamino]propyl-functionalized mesoporous silicas which were simultaneously used as N sources and hard templates. A series of different spectroscopic and analytical techniques was performed to characterize these Pt-NOMC-T catalysts. Combined the results from X-ray diffraction, N₂ adsorption-desorption isotherms, transmission electron microscopy and elemental analysis show that ca. 0.7-2.2 wt% of nitrogen was successfully doped on the high surface areas of ordered mesoporous carbon rods. Further studies by X-ray photoelectron spectroscopy indicated that Pt-NOMC-T catalysts with different ratios of quaternary-N and pyridinic-N were observed. Among various Pt-NOMC-T samples, the Pt-NOMC-1073 sample, which may be due to moderate electrical conductivity of ordered mesoporous carbons, unique nanostructure between Pt nanoparticles and N-doped carbon supports, and presence of more pyridinic-N atoms, was found to possess superior electrocatalytic activity for methanol-tolerant oxygen reduction in comparison with the typical commercial electrocatalyst (Pt/XC-72).     

Phase transformation and nanocrystallite growth behavior of 2 mol% yttria-partially stabilized zirconia (2Y-PSZ) powders

Two mol% yttria-partially stabilized zirconia (2Y-PSZ) precursor powders were obtained through a co-precipitation process using ZrOCl₂.8H₂O and Y(NO₃)₃.6H₂O as starting materials. Phase transformation and crystallite growth behavior have been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). XRD results show that the crystal structure to be composed of coexisting tetragonal ZrO₂ (t-ZrO₂) and monoclinic ZrO₂ (m-ZrO₂) when the 2Y-PSZ freeze dried precursor powders was calcined at 773–1273 K for 2 h. The fraction of m-ZrO₂ content is lower than 3.0 % when the calcination temperature is lower than 1073 K, whereas m-ZrO₂ content rapidly increases to 8.7 % with the increase of calcination temperature to 1273 K. The crystallite size of t-ZrO₂ increases from 12.3 to 30.2 nm when calcination temperature increased from 773 to 1273 K. In addition, the activation energy of t-ZrO₂ and m-ZrO₂ crytallite growth in 2Y-PSZ freeze dried precursor powders are 29.2 and 21.8 kJ/mol, respectively.     

Contrasting distribution of trace elements between representative antimony deposits in southern China

The Xuefeng uplifted belt and the neighboring Xikuangshan region of southern China is the largest antimony producing area in the world. The mineralizing solution which was responsible for the antimony deposition is considered to be derived mainly from deep crustal fluids during a large tectonic movement of the Jurassic time. We analyzed trace elements of ore minerals and fluid inclusions from this area by CSIRO’s micro-PIXE to understand characteristics of the mineralizing solution. We selected three representative “super-large” deposits, one in the Xikuangshan area and the others within the Xuefeng belt: (1) Xikuangshan (simple Sb) which is structurally controlled by large-scale transcrustal faults and fractures, and mainly hosted by limestone; (2) Wuxi (Sb–Au–W), embedded in slate and structurally controlled by large-scale faults and fractures; and (3) Banxi (simple Sb) which is hosted by slate and controlled by local fractures. Our preliminary result indicated that the trace element distribution is highly contrasting for these three deposits corresponding to each geologic setting. Our case study showed that being combined with field evidence, micro-PIXE can contribute to understand large tectonic movements and to establish an effective exploration model for super-large mineral deposits.