Asymmetric Dimethylarginine in Chronic Obstructive Pulmonary Disease (ADMA in COPD)

l-Arginine metabolism including the nitric oxide (NO) synthase and arginase pathways is important in the maintenance of airways function. We have previously reported that accumulation of asymmetric dimethylarginine (ADMA) in airways, resulting in changes in l-arginine metabolism, contributes to airways obstruction in asthma and cystic fibrosis. Herein, we assessed l-arginine metabolism in airways of patients with chronic obstructive pulmonary disease (COPD). Lung function testing, measurement of fractional exhaled NO (FeNO) and sputum NO metabolites, as well as quantification of l-arginine metabolites (l-arginine, l-ornithine, l-citrulline, ADMA and symmetric dimethylarginine) using liquid chromatography-mass spectrometry (LC-MS) were performed. Concentrations of l-ornithine, the product of arginase activity, correlated directly with l-arginine and ADMA sputum concentrations. FeNO correlated directly with pre- and post-bronchodilator forced expiratory volume in one second (FEV₁). Sputum arginase activity correlated inversely with total NO metabolite (NO_x) and nitrite concentrations in sputum, and with pre- and post-bronchodilator FEV₁. These findings suggest that ADMA in COPD airways results in a functionally relevant shift of l-arginine breakdown by the NO synthases towards the arginase pathway, which contributes to airway obstruction in these patients.     

Stabilization of mid-sized silicon nanoparticles by functionalization with acrylic acid

The random architecture of a commercial copolymer of poly(DL-lactic acid) and poly(??-caprolactone), poly(DL-lactide-co-caprolactone), has been characterized by chemical structure analysis from hydrogen-1 nuclear magnetic resonance results. Moreover, spherical nanodomains have been detected in the thin films of this copolymer obtained after solvent evaporation. These nanodomains studied by atomic force microscopy and transmission elecron microscopy grow progressively under annealing until they collapse and form a homogenous disordered structure. This is the first time that the nanostructure of random poly(DL-lactic acid)/poly-(??-caprolactone) copolymers is revealed, representing one of few experimental evidences on the possible nanostructuration of random copolymers.     

Efficient Detection of 3 THz Radiation from Quantum Cascade Laser Using Silicon CMOS Detectors

In this paper, we report on efficient detection of the radiation emitted by a THz quantum cascade laser (QCL) using an antenna-coupled field effect transistor (TeraFET). In the limiting case when all radiated power would be collected, the investigated TeraFET can show up to 230 V/W responsivity with the noise equivalent power being as low as 85 pW/\(\sqrt {\text {Hz}}\) at 3.1 THz, which is several times lower than that of the typical Golay cell. A combination of the QCL and a set of off-axis parabolic mirrors with 3-inch and 2-inch focal lengths was used to measure the signal-to-noise ratio (SNR) of the TeraFET. The practically achieved SNR was five times lower than that of the Golay cell and two orders of magnitude lower than a bolometer’s. However, TeraFETs are much faster and do not need a signal modulation, thus can be used both in a continuous mode for power monitoring or for investigation of transient processes on a sub-microsecond time scale.     

Optical and chemical characterization of thin TiNx films deposited by DC-magnetron sputtering

Thin titanium nitride (TiN_x) films were deposited on silicon substrates by means of a reactive DC-magnetron plasma. Layers were synthesized under various conditions of discharge power and nitrogen flows in two operation modes of the magnetron (the so-called “balanced” and “unbalanced” modes). The optical constants of the TiN_x films were investigated by spectroscopic ellipsometry (SE). X-ray photoelectron spectroscopy (XPS) was used to determine the relative atomic concentration and chemical states of the TiN_x films. The density and thickness of the films have been investigated by means of grazing incidence X-ray reflectometry (GIXR). The results of the layer analyses were combined with plasma investigations carried out by means of energy resolved mass spectrometry (ERMS) under the same conditions. It is shown that the magnetron mode has a clear influence on the titanium deposition rate and the incorporation of nitrogen into the layers.     

带双质量飞轮的动力传动系统各种工况的仿真

节约实车试验和减少开发周期和成本的一个必不可少的工具是通过各种行驶条件下的仿真来确定双质量飞轮（DMF）的最优参数。另外,仿真还能确定应用于当前设计的新方法的效能。     

Functionalization of track-etched poly (ethylene terephthalate) membranes as a selective filter for hydrogen purification

This paper reports on the carboxylic and amino group functionalization of track-etched poly(ethylene terephthalate) (PET) membranes with different pore size and pore density. Glycolic acid groups were formed by oxidation of hydroxyethyl end groups while amino groups were introduced by amidation of these carboxylic groups with tetraethylenepentamine. These membranes were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) to follow the effect of the oxidation process on the molecular weight of the PET and to access the formation of functional groups. As concluded from NMR and XPS results, the density of carboxyl and amino group increases in comparison to pristine PET membranes. The larger the pore diameter and the pore density, the higher is the extent of functionalization. We demonstrate the deposition of palladium (Pd) nanoparticles onto pore walls and pore surfaces of PET membranes for potential use in hydrogen separation or sensing. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (in SEM) results show presence of Pd nanoparticles in functionalized PET membranes pointing to an enhanced binding capability of Pd nanoparticles that can be used for hydrogen extraction from a mixture of gases.     

Radiation quality of photons in small and large receptors--a microdosimetric analysis

The quality of different photon radiations in small and largereceptors is assessed in terms of microdosimetry. Monte Carlosimulations are performed for the electrons released by photons.To represent the case of a small receptor, only electrons releasedby the non-degraded incident photons are tracked. For a largereceptor, all electrons released in the complete degradationprocess are followed. Dose averaged values, y_D, of the linealenergy are derived from the simulated tracks for monoenergeticphotons from 10 keV to 2 MeV. In microdosimetry, the dose meanlineal energy is the major parameter of radiation quality. Theresults demonstrate distinct differences in radiation qualitybetween high-energy gamma rays and conventional X rays thatare present not just in small cell samples but also in largereceptors, such as the human body. The values of y_D suggestthat, for both small and large receptors, conventional X raysshould be about twice as effective as gamma rays from ⁶⁰Co.     

Growing one-dimensional metallic nanowires by dielectrophoresis

We report an electrical-field-controlled growth process for the directed bottom-up assembly of one-dimensional palladium nanowires between microfabricated electrodes. The wires, grown from an aqueous palladium salt solution by dielectrophoresis, have a thickness of only 5-10 nm and a length of up to several micrometers. The growth process depends largely on both the strength of the applied ac field and the concentration of the metal salt solution. The conditions for optimum growth are evaluated. Room-temperature current-voltage measurements show ohmic behavior and indicate electromigration effects at higher voltages. Low-temperature transport measurements reveal localization effects with a characteristic resistance minimum at 20 K. The temperature dependence below the minimum shows the wires to be one dimensional in their electron-transport properties. The investigated growth method is capable of building complex circuit patterns for future nanoelectronics.     

Measurement of a low-absorption sample of OH-reduced fused silica

Low-absorption optics made of OH-reduced fused silica are a key technology for future gravitational wave detectors such as the Advanced LIGO. We developed a sensitive method to measure the absorption inside the beam splitter of the GEO 600, taking advantage of the effect of thermal lensing. Using this method, we derived a bulk absorption of less than 0.25 ppm/cm for a piece of Suprasil 311 SV at a wavelength of 1064 nm. To the best of our knowledge, this is the lowest value of light absorption inside fused silica reported so far in the literature.