In vivo Kinetic Biodistribution of Nano‐Sized Outer Membrane Vesicles Derived from Bacteria

Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter‐species, and inter‐kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)—bacterial extracellular vesicles—with immune‐modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF‐α and IL‐6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM‐1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post‐injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo.     

Measurement and numerical simulation of three‐dimensional fiber orientation states in injection‐molded short‐fiber‐reinforced plastics

To determine three‐dimensional fiber orientation states in injection‐molded short‐fiber composites, a confocal laser scanning microscope (CLSM) is used. Since the CLSM optically sections the specimen, more than two images of the cross sections on and below the surface of the composite can be obtained. Three‐dimensional fiber orientation states can be determined by using geometric parameters of fiber images obtained from two parallel cross sections. For experiments, carbon‐fiber‐reinforced polystyrene is examined by the CLSM and geometric parameters of fibers on each cross‐sectional plane are measured by an image analysis. In order to describe fiber orientation states compactly, orientation tensors are determined at different positions of the prepared specimen. Three‐dimensional orientation states are obtained without any difficulty by determining the out‐of‐plane angles utilizing fiber images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell–core structure along the thickness of the specimen. Fiber orientation tensors are predicted by a numerical analysis and the numerically predicted orientation states show good agreement with measured ones. However, some differences are found at the end of cavity. They may result from the fountain flow effects, which are not considered in the numerical analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 500–509, 2003     

A new time-domain discontinuous space-vector PWM technique in overmodulation region

A new discontinuous modulation method based on space-vector control is proposed and analyzed. The proposed technique employs a pulse-dropping method and is designed in the time domain. It features a very wide modulation range while maintaining the required waveform qualities and switching numbers in the overmodulation region. Since the modulation method and modulation index equation are simple, the proposed technique can be easily implemented by software and is applicable to the overmodulation region in ac motor drives. The performance indexes are discussed and experiments have been performed.     

On detecting the presence of fetal R-wave using the moving averagedmagnitude difference algorithm

An efficient algorithm detecting the presence of a fetal QRS complex is presented. The proposed fetal QRS detection method computes the averaged magnitude of the difference between the fetal ECG signal and the reference signal to detect the fetal QRS event. The detected fetal QRS complexes are exponentially averaged to generate the template signal which can track the slowly varying shape of the fetal ECG signal. As an effort to obtain improved detection performances, two approaches of normalizing the fetal ECG signal and the template are considered.     

On the modelling of scalar and mass transport in combustor flows

The results of a numerical study of swirling and non-swirling combustor flows with and without density variations are presented. Constant-density arguments are used to justify closure assumptions invoked for the transport equations for turbulent momentum and scalar fluxes, which are written in terms of density-weighted variables. Comparisons are carried out with measurements obtained from three different axisymmetric model combustors. The three experiments cover recirculating flow, swirling flow and variable-density, swirling flow inside model combustors. Together, they offer wide ranging flow conditions to test the validity of the models. Results show that the Reynolds stress/flux models do a credible job of predicting constant-density, swirling and non-swirling combustor flows with passive scalar transport. However, their improvements over algebraic stress/flux models are marginal. The extension of the constant-density models to variable-density flow calculations shows that the models are equally valid for such flows. Therefore, the present results argue well for the adoption of constant-density models for variable-density flows until a successfully validated variable-density model is available.     

Effects of brefeldin-A on Golgi morphology in human cultured fibroblasts observed in three-dimensional stereo scanning electron microscopy

Brefeldin A (BFA) has been reported to cause disassembly of the Golgi. We have used three-dimensional (3-D) high-resolution scanning electron microscopy (HRSEM) to investigate these effects in human skin fibroblast cells. The spontaneous reassembly during prolonged exposure to BFA and some effects of forskolin were observed. A BFA concentration of 5μg/ml caused Golgi complexes to become vesicular, resulting in a progressive decrease in the size of the Golgi. Morphologic changes were visible within 2 min of BFA incubation, and by 30 min no identifiable Golgi could be found. Spontaneous reassembly of the Golgi apparatus upon the removal of the BFA or with continued long-term exposure with BFA could not be confirmed. Preliminary experiments with forskolin were not effective in reversing or inhibiting the effects of BFA in human fibroblast cells grown in culture. This inability for spontaneous reassembly and nonreversal by forskolin may reflect a differential effect of BFA in various cell types. HRSEM has proven to be useful for observing 3-D morphologic effects of BFA in Golgi.     

On-line dead-time compensation method using disturbance observer

A new on-line dead-time compensation method for a permanent magnet (PM) synchronous motor drive is proposed. Using a simple disturbance observer without any additional circuit and off-line experimental measurement, disturbance voltages in the rotor reference dq frame caused by the dead time and nonideal switching characteristics of power devices are estimated in an on-line manner and fed to voltage references in order to compensate the dead-time effects. The proposed method is applied to a PM synchronous motor drive system and implemented by using software of a digital signal processor (DSP) TMS320C31. Simulations and experiments are carried out for this system and the results well demonstrate the effectiveness of the proposed method.     

Photodegradation mechanism and stabilization of polyphenylene oxide and rigid‐rod polymers

Poly(2,4‐dimethyl‐1,4‐phenylene oxide) (PPO), poly(benzo[1,2‐d:5,4‐d′]bisoxazole‐2,6‐diyl‐1,4‐phenylene) (PBO) and poly(benzo[1,2‐d:4,5‐d′]bisthiazole‐2,6‐diyl‐1,4‐phenylene) (PBZT), which are polymers with extended conjugated structures, undergo a self‐sensitized photo‐induced electron‐transfer reaction. A second component is not required. This article presents many similar observations on these polymers when they are exposed to light and evidence to support the proposed photo‐induced electron‐transfer mechanism. Methods to stabilize these polymers against photo‐oxidation are also described. Workers investigating other conjugated polymeric systems may find the experimental methods, observations and polymer stabilization approaches discussed in this review useful. Copyright © 2005 Society of Chemical Industry     

Amorphous Ni---N---W film as a diffusion barrier between aluminum and silicon

The influence of nitrogen on the diffusion barrier properties of amorphous Ni---W films was studied. Nitrogen was introduced into the amorphous Ni---W film by co-sputtering nickel and tungsten in a premixed gas mixture of 90% Ar and 10% N₂, resulting in the formation of amorphous Ni₃₀N₂₁W₄₉ film. X-ray analysis indicates a detectable crystallization of the amorphous film after 30 min annealing in vacuum at 600°C, accompanied by the formation of W₂N, but backscattering spectrometry (BS) reveals a reaction with silicon only at about 725°C. The Schottky barrier height of this amorphous film on n-Si is stable for 30 min annealing up to at least 550°C. With an aluminum overlayer, BS indicates that an amorphous Ni₃₀N₂₁W₄₉ film effectively prevents the metallurgical interaction between aluminum and silicon for 30 min up to 600°C. The Schottky barrier height of that contact configuration is also stable up to at least 550°C, suggesting that amorphous Ni---N---W films have attractive features as diffusion barriers.