Study of calcium signaling in non-excitable cells.

The fundamental importance of calcium signaling in the control of cellular physiology is widely recognized. A dramatic illustration of this is the fact that a Medline search for review articles containing the word "calcium" in the title reveals 4,629 hits, whereas the whole body of calcium signaling literature (approximately 2 x 10(6) pages) is more than enough to fill a decent-sized library. Most of this literature deals with calcium signaling in excitable cells types (mainly neurons and muscle cells), but non-excitable cell types are capable of calcium signaling as well. Although calcium fluxes in the latter cell types have attracted much less interest, the literature involved is still vast. Nevertheless, in this review article we hope to contribute some valuable insights to the field. First we shall discuss the experimental techniques available to the researcher interested in calcium signaling in non-excitable cell types with special attention to patch clamp electrophysiology. Subsequently, we shall review some of the results obtained with these techniques by focussing on the calcium-regulating mechanisms in non-excitable cells and discussing the importance of these mechanisms for physiology.     

Fluorescence rejection in resonance Raman spectroscopy using a picosecond-gated intensified charge-coupled device camera

A Raman instrument was assembled and tested that rejects typically 98-99% of background fluorescence. Use is made of short (picosecond) laser pulses and time-gated detection in order to record the Raman signals during the pulse while blocking most of the fluorescence. Our approach uses an ultrafast-gated intensified charge-coupled device (ICCD) camera as a simple and straightforward alternative to ps Kerr gating. The fluorescence rejection efficiency depends mainly on the fluorescence lifetime and on the closing speed of the gate (which is about 80 ps in our setup). A formula to calculate this rejection factor is presented. The gated intensifier can be operated at 80 MHz, so high repetition rates and low pulse energies can be used, thus minimizing photodegradation. For excitation we use a frequency-tripled or -doubled Ti : sapphire laser with a pulse width of 3 ps; it should not be shorter in view of the required spectral resolution. Other critical aspects tested include intensifier efficiency as a function of gate width, uniformity of the gate pulse across the spectrum, and spectral resolution in comparison with ungated detection. The total instrumental resolution is 7 cm(-1) in the blue and 15 cm(-1) in the ultraviolet (UV) region. The setup allows one to use resonance Raman spectroscopy (RRS) for extra sensitivity and selectivity, even in the case of strong background fluorescence. Excitation wavelengths in the visible or UV range no longer have to be avoided. The effectiveness of this setup is demonstrated on a test system: pyrene in the presence of toluene fluorescence (lambda(exc) = 257 nm). Furthermore, good time-gated RRS spectra are shown for a strongly fluorescent flavoprotein (lambda(exc) = 405 nm). Advantages and disadvantages of this approach for RRS are discussed.     

Enhancement of the Traffic Differentiation Architecture for WBAN Based on IEEE 802.15.4

In the healthcare domain, Wireless Body Area Network has emerged as a vital technology that is capable of providing better methods to diagnose various hazardous diseases. The CANet projet is a project that proposes alternative monitoring solutions. This paper studies the possibility of transmitting different types of information through an IEEE 802.15.4 MAC layer that not supports the transmission of heterogeneous information. We have proposed an extension to the MAC layer which makes possible the transmission of various information types. This solution designed by “diffrentiation layer” uses a purge function to ensure the use of CAP and CFP by the same node in the same superframe and allows the differentiation between several information. Our results show that our solution is reliable under worst-case.     

中、英两国规范对桅杆风振设计规定的比较

本文研究了我国《高耸结构设计规范》(GBJ-90)和英国规范BS8100对于桅杆风振设计的具体规定,通过算例分析了我国规范的不足之处,为规范的修订提供参考.     

Validation and application of adsorption breakthrough models for the chemical filters used in the make-up air unit (MAU) of a cleanroom

The dynamic adsorption capacity calculated from the breakthrough curves progressively decreased with the increases in the face velocity, suggesting that the effect of intraparticle diffusion and possibly the rate of adsorption as the rate-limiting mechanism were increasingly more profound for a chemical filter-type adsorber configuration. The Yoon–Nelson model generally matched well with the experimental breakthrough curved for breakthrough fraction less than 50%. However, the proportionality constant in the Yoon–Nelson model needed modification through the method from which the mass transfer coefficient (k_v) in the Wheeler–Jonas equation is determined. Subsequently, a series of breakthrough curves for the hypothetical toluene concentrations and face velocities simulating realistic operating conditions was generated, and their validity was verified against the adsorption capacity predicted by the Dubinin–Radushkevich isotherm equation. The useful life of a chemical filter could henceforth be estimated with confidence using the breakthrough curves predicted by the modified Yoon–Nelson model.     

Stationary Phase 5. Evaluation of Stationary Phases for HPLC of Explosives

The retentions of 11 explosives on two commercially RP-18 and Si 100 stationary phases and one prepared 3-[9′-(10′-methylanthryl)]- propylsilane stationary phase (MAPS-phase) were examined by modified mobile phases. The evaluation of these three stationary phases results as follows:

• (1) Most explosives were effectively separated on a column of MAPS-phase not only with methanol/water (75/25-85/15) as mobile phase but also with n-hexane/dichloromethane (75/25) as mobile phase.
• (2) Few explosives were effectively separated on a column of RP-18 with methanol/water (75/25-85/15) as mobile phase.
• (3) The separation of most explosives on Si 100 was achieved only under normal phase condition such as n-hexane/dichloromethane (75/25) as mobile phase.

     

Inferring the degradation of pultruded composites from dynamic nonlinear resonance measurements

The Chemical resistance of pultruded polyester composites to various chemical immersion solutions is investigated as a function of the exposure time, and the observations from static tests are compared with the results from nonlinear dynamic vibration experiments. The mechanical properties were measured according to ASTM standards, both in flexural and tensile tests. Barcol hardness and sorption measurements provide complemntary information. In addition, a novel nondestructive (NDE) method, called Single Mode Nonlinear Resonance Acoustic Spectroscopy (SIMONRAS), was applied to measure the linear and nonlinear dynamical properties of the samples as a funtion of exposure time. This new NDE method focuses on the strain amplitude dependence of the resonance frequency while driving a sample at relatively low excitation levels. The obtained relative frequency shift is a measure of the internal microstructural properties of the material. The correlation between this nonlinearity parameter and the mechanical properties is extremely good, which implies that the SIMONRAS technique can be applied to predict the chemo‐mechanical degradation of composites in a nondestructive manner.     

An infrared analysis method to determine the aromatic carbon content of mineral lubricant base oils based on correlation with carbon-13 NMR aromaticities

A widely used method to determine base oil aromaticity was introduced by G. Brandes in 1956 and is based on a correlation between the infrared aromatic absorption band at 1610 cm⁻¹ and the aromaticity determined by the n-d-M method. Accurate and absolute aromaticities can be measured by carbon-13 NMR but, infortunately, this technique is not suitable for routine analysis. The aromaticities measured by NMR are almost invariably significantly lower than those obtained by Brandes' method. In this study, the areas of the infrared aromatic bands at 1610 and 815 cm⁻¹ of over 70 base oils with aromaticities ranging from 1–16% were correlated by multilinear regression with their carbon-13 NMR aromaticities. An equation to calculate the aromaticity from infrared absorptions was derived. These aromaticities show an excellent match with carbon-13 NMR data. This new infrared method can be applied as a fast and convenient base-oil quality control tool.