Upright MRI of glenohumeral dysplasia following obstetric brachial plexus injury

The purpose of this study was to evaluate the role of upright magnetic resonance imaging (MRI) shoulder scanning in the diagnosis of glenohumeral deformity following obstetric brachial plexus injury (OBPI). Eighty-nine children (ages 0.4 to 17.9 years) with OBPI who have medial rotation contracture and reduced passive and active lateral rotation of the shoulder were evaluated via upright MRI of the affected glenohumeral joint. Qualitative impressions of glenoid form were recorded, and quantitative measurements were made of glenoid version and posterior subluxation. Glenoid version of the affected shoulder averaged -16.8 +/- 11.0 degrees (range, -55 degrees to 1 degrees ), and percentage of the humeral head anterior to the glenoid fossa (PHHA) averaged 32.6 +/- 16.5% (range, -17.8% to 52.4%). The glenoid form was normal in 43 children, convex in 19 children and biconcave in 27 children. Standard MRI protocols were used to obtain bilateral images from 14 of these patients. Among the patients with bilateral MR images, glenoid version and PHHA were significantly different between the involved and uninvolved shoulders (P<.000). Glenoid version in the involved shoulder averaged -19.0 +/- 13.1 degrees (range, -52 degrees to -3 degrees ), and PHHA averaged 29.7 +/- 18.4% (range, -16.2% to 48.7%). In the uninvolved shoulder, the average glenoid version and PHHA were -5.2 +/- 3.7 degrees (range, -12 degrees to -1 degrees ) and 47.7 +/- 3.0% (range, 43% to 54%), respectively. The relative beneficial aspects of upright MRI include lack of need for sedation, low claustrophobic potential and, most important, natural, gravity-influenced position, enabling the surgeon to visualize the true preoperative picture of the shoulder. It is an effective tool for demonstrating glenohumeral abnormalities resulting from brachial plexus injury worthy of surgical exploration.     

Synthesis of hydroxystilbenes and their derivatives via Heck reaction

A group of differently substituted acetoxy- and methoxystilbenes were synthesised via Heck reaction. A comparison between the use--as coupling reagents--of iodobenzene derivatives and diazonium salts was performed. A successful microwave-assisted demethylation by pyridine hydrochloride of some methoxystilbenes was carried out.     

129Xe NMR Studies of Pecan Shell-Based Biochar and Structure-Process Correlations

Pecan shell-based biochar is utilized as a filtration medium, sequestrant for metallic ions, soil conditioner, and other applications. One process for creating the biochar involves the use of phosphoric acid at high temperature in a partial oxygen atmosphere to produce a highly porous carbonaceous material. In this work, we found ¹²⁹Xe NMR to be an excellent technique to study micropores in biochar. Thus, the ¹²⁹Xe chemical shift in biochar was found to vary linearly with the xenon pressure; from the data an estimate of about 8–9 Å could be proposed for the average pore diameter in pecan shell-based biochar. Through saturation recovery and 2-D NMR exchange experiments, information on the exchange between free versus bound xenon was obtained. Furthermore, correlations of ¹²⁹Xe NMR data with the carbonization process conditions were made.     

Incompressible laminar flow through hollow fibers: a general study by means of a two-scale approach

We study the laminar flow of an incompressible Newtonian fluid in a hollow fiber, whose walls are porous. We write the Navier?CStokes equations for the flow in the inner channel and Darcy??s law for the flow in the fiber, coupling them by means of the Beavers?CJoseph condition which accounts for the (possible) slip at the membrane surface. Then, we introduce a small parameter ${\varepsilon \ll 1}$ (the ratio between the radius and the length of the fiber) and expand all relevant quantities in powers of ??. Averaging over the fiber cross section, we find the velocity profiles for the longitudinal flow and for the cross-flow, and eventually, we determine the explicit expression of the permeability of the system. This work is also preliminary to the study of more complex systems comprising a large number of identical fibers (e.g., ultrafiltration modules and dialysis).     

Stable Solutions of Elliptic Equations on Riemannian Manifolds

This paper is devoted to the study of rigidity properties for special solutions of nonlinear elliptic partial differential equations on smooth, boundaryless Riemannian manifolds. As far as stable solutions are concerned, we derive a new weighted Poincaré inequality which allows us to prove Liouville type results and the flatness of the level sets of the solution in dimension 2, under suitable geometric assumptions on the ambient manifold.     

Validation of the determination of tin by <Emphasis Type="Italic">k</Emphasis><Subscript>0</Subscript>-instrumental neutron activation analysis in foodstuff

Several recent intercomparisons and certification exercises have shown that the determination of tin in e.g. food samples and plastics is not straightforward. k ₀-Instrumental Neutron Activation Analysis (k ₀-INAA) offers some intrinsic quality control opportunities for the determination of the tin content in samples since several monitoring radioisotopes are formed. In this work we will discuss the validation of the determination of tin by k ₀-INAA using different reference materials. The results show that only few of these radioisotopes are reliable in terms of accuracy and that from a survey of the tin content in a range of canned foods detection limits as low as 2 mg/kg can be achieved.     

Dielectric coatings for optimized low-loss saturable absorbers for high-power ultrafast laser

With the development of high power ultrafast laser passively mode-locked by a semiconductor saturable absorber mirror （SESAM）, the damage threshold and degeneration mechanism of the SESAM become more and more important. One way to reduce the maximum electric field inside the active part of the SESAM is the use of a dielectric coating on the top of the semiconductor structure. With Presnel formula, optical transfer matrix, and optical thin film theory, the electric field distribution and reflectance spectrum can be simulated. We introduce the design principles of SESAM including the dependence of reflectance spectrum on dielectric function of absorber, and investigate the dependences of the electric field distribution, modulation depth, reflectance spectrum, and the relative value of incident light power at the top quantum well of SESAM on the number of SiO2/Ta2O5 layers.     

Schwinger's method for the fermionic Casimir effect

The Casimir energy of a massive Dirac field confined between two parallel infinite plates is computed using a method proposed by Schwinger. The massless case is obtained as a limit of the massive case. The boundary conditions are those of zero current through the plates, as inspired by quark confinement in the MIT bag model for hadrons. We use an analytical continuation method of regularization which allows the employment of Epstein function techniques. The calculation using Schwinger's original regularization by a cutoff in proper time is also outlined.