Effect of macroscopic deformation on lung microstructure

Using an anisotropic theory of diffuse light scattering in lungs, we measured the fractional changes in geometric mean linear intercepts in orthogonal directions when freshly excised rabbit lungs were subjected to isovolume uniaxial strains. Results from the optical technique were compared with morphometric estimates of fractional changes in mean linear intercepts from the same strained and unstrained (control) lobes, with the conclusion that diffuse light scattering is adequate to estimate changes in mean free paths in different directions. We compared optical estimates of fractional changes in mean linear intercepts with the macroscopic strain field measured by displacements of pleural markers; this relationship did not significantly differ from the line of identity. We conclude that the microscopic strain field is closely matched to the macroscopic strain field during uniaxial distortion. This suggests that surface reorientation may not play a large role in the origin of the low shear modulus of the lung, but this cannot be definitively stated without comparison of these experimental results to specific model predictions of the changes in mean linear intercepts in shear deformation.     

Aligned double exposure in deep X-ray lithography

Deep X-ray lithography with synchrotron radiation is a powerful tool to generate threedimensional microstructures with high aspect ratios. In order to complement and enhance the normal shadow printing with methods to generate true threedimensional structures, we investigated the aligned multiple exposure process to produce step-like LIGA structures also involving the sacrificial layer technique to obtain movable structures. Irradiations have been performed utilizing a newly developed X-ray Scanner (JENOPTIK GmbH) with internal optical alignment system.

Multiple exposure requires the alignment of mask and substrate. We used silicon nitride mask membranes with 10 μm thick gold absorber patterns, which show excellent transmission in the visible light range for alignment purposes and good X-ray transparency in the hard X-ray regime.

The first results of double exposure experiments obtained with the scanner prototype are promising. With the exception of a systematic error an alignment accuracy of σ_x = 0.26 μm and σ_y = 0.4 μm (standard deviation) has been achieved. Present work concentrates on the improvement of the adjustment system.

All the exposures have been carried out at the BESSY wavelength shifter (Berlin/Germany).     

Promoting successful school completion: Critical conceptual and methodological guidelines.

Conceptual issues related to dropping out, student engagement, and school completion are raised. Thirteen criteria are described as guidelines for designing, evaluating, and documenting programs to enhance successful school completion for all students. The status of the current intervention research is summarized relative to the specified criteria. Recommendations for future research and practice include implementation of interventions, systematic application of criteria in evaluating interventions, focus on school completion across school years, and capturing students' experiences and using the information to develop contextualized interventions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

On the optimal performance of long-rod penetrators subjected to transverse accelerations

The paper deals with theoretical considerations on the conception and optimization of long-rod penetrators with regard to bending strain and penetration efficiency. In a first step we describe a method allowing to design long penetrators in such a manner that given values of bending stress and deflection are met if the rods are subjected to lateral forces. On the assumption of a constant lateral acceleration this results in rods with various dimensions; the aspect ratio remarkably does not remain constant. Then these penetrators are examined for maximum penetration efficiency while considering rods of equal energy. For the case studied the procedure results in an optimum velocity of about 2700 m/s. This demonstrates a fundamental difference in comparison to the optimization process with L/D-scaled penetrators where a much lower optimum velocity (2300 m/s) is obtained. In comparison to the reference penetrator (L/D=34, V=1800 m/s) the optimum penetrator — still at constant stress level and at an impact velocity of 2700 m/s — has of course a reduced mass, but also a reduced length and diameter showing an aspect ratio of 40. The perforation power could be increased by some 17%. On the other hand, the linearly scaled penetrator at constant energy only shows an increase of about 7% in penetration capability if the impact velocity reaches its optimum value at 2300 m/s. The optimization procedure of the energy-efficient penetration of constant-stress projectiles leads to an optimal velocity well in the hypervelocity regime. Furthermore, the special design of the penetrators with constant stress level results in a gain of penetration efficiency.     

A Vector Derivation Useful in Impedance Plethysmographic Field Calculations

A vector relationship similar to Green's theorem incorporating simplifications which can be made for impedance plethysmography is derived. The mathematics involved are simplified by the use of current density instead of electric field. Geselowitz's lead theory result [1] is rederived and a limitation of such proofs is discussed.     

John Thomson (1837–1921)

Abstract

Abstract Thomson did some of his most important work in Asia but was not, of course, the first European photographer to travel there. Thus, Eliphalet Brown, Jr. had accompanied Commodore Perry's expedition to Asia in 1852–1854. His daguerreotypes were reproduced by means of woodcuts and lithographs in the official report of the expedition. A Narrative of the Expedition to the China Seas and Japan ¹. Felice Beato photographed the Crimean War of 1855 with James Robertson, continued eastward photographing India during the next five years, and then attached himself to the Anglo-French campaign against China. There he covered the capture of Fort Taku at Tiensin, and later the destruction of the Imperial Summer Palace north of Peking in October 1860. Thomson appeared on the site 10 years later. He photographed Fort Taku also, and noted that it ‘looked like a deserted mud quarry’².     

Cationic silica nanoparticles as gene carriers: synthesis, characterization and transfection efficiency in vitro and in vivo

The potential of cationic SiO2 nanoparticles was investigated for in vivo gene transfer in this study. Cationic SiO2 nanoparticles with surface modification were generated using amino-hexyl-amino-propyltri-methoxysilane (AHAPS). The zeta potential of the nanoparticles at pH = 7.4 varied from -31.4 mV (unmodified particles; 10 nm) to +9.6 mV (modified by AHAPS). Complete immobilization of DNA at the nanoparticle surface was achieved at a particle ratio of 80 (w/w nanoparticle/DNA ratio). The surface modified nanoparticle had a size of 42 nm with a distribution from 10-100 nm. The ability of these particles to transfect pCMVbeta reporter gene was tested in Cos-1 cells, and optimum results were obtained in the presence of FCS and chloroquine at a particle ratio of 80. These nanoparticles were tested for their ability to transfer genes in vivo in the mouse lung, and a two-times increase in the expression levels was found with silica particles in comparison to EGFP alone. Very low or no cell toxicity was observed, suggesting silica nanoparticles as potential alternatives for gene transfection.