Hollow-fiber flow field-flow fractionation for whole bacteria analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

This work proposes for the first time the use of hollow-fiber flow field-flow fractionation (HF FlFFF) for improved matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOFMS) of whole bacteria. HF FlFFF has proved to be able to prepurify or fractionate different species of whole bacteria. Sample preparation by HF FlFFF gives improved spectra quality because noncellular components possibly present in the sample can be separated from the cells. When a mixture of two bacteria (Bacillus subtilis and Escherichia coli) is fractionated through HF FlFFF, MALDI/TOFMS analysis of each separated bacterial species preserves the most characteristic ion signals of the species without the presence of characteristic signals of the other species. The main advantages of HF FlFFF for MALDI/TOFMS analysis of whole bacteria are miniaturization, simplicity, and low cost of the fractionator components. This low cost makes disposable usage of the fractionator possible, thus eliminating the risk of run-to-run contamination of spectra due to sample carryover. The low fractionator volume yields bacterial fractionation on the order of a few minutes, which is comparable to MALDI/TOFMS analysis time. The small fractionation volume makes sample dilution low enough so that additional sample concentration steps are not strictly required to preserve MALDI/TOFMS detection.     

Role of Gas1 down-regulation in mitogenic stimulation of quiescent NIH3T3 cells by v-Src

Quiescent mammalian fibroblasts can be induced to reenter the cell cycle by growth factors and oncoproteins. We studied the pathway(s) through which v-Src, the oncogenic tyrosine kinase encoded by the v-src oncogene of Rous sarcoma virus, forces serum-starved NIH3T3 cells to enter S-phase. To this purpose, we isolated and characterized a polyclonal population of NIH3T3 cells transformed by the MR31 retroviral vector, encoding G418 resistance and the v-src temperature-sensitive allele from the mutant ts LA31 PR-A. NIH(MR31) cells displayed a temperature-conditional transformed phenotype and could be made quiescent by serum deprivation at the restrictive temperature. Serum stimulation or thermolabile v-Src reactivation induced entry into S-phase to a comparable extent, although with different kinetics. The data suggest that v-Src mitogenic activity involves early activation of the Erk1/Erk2 MAP kinases with very little tyrosine phosphorylation of the Shc adaptor proteins at least during the early stages of v-Src reactivation and that v-Src-induced S-phase entry was strongly inhibited by drugs affecting MEK or PI 3-kinase. Our results also suggest that down-regulation of gas1 gene expression plays an important role in regulating the efficiency of entry into S-phase triggered by reactivated v-Src and that Gas1 down-regulation does not require PI 3-kinase dependent signals.     

Crystallization behavior of polyphenylene sulfide in blends with a liquid crystalline polymer

Blends of polyphenylene sulfide (PPS) with a commercial, wholly aromatic, liquid crystal copolyesteramide (Vectra-B950) have been prepared by meltblending. The crystallization behavior of neat and blended PPS has been studied by differential scanning calorimetry (DSC), under both non-isothermal and isothermal conditions. It has been found that blending PPS with Vectra-B leads to an increase of the temperature of non-isothermal crystallization and to a pronounced acceleration of the isothermal crystallization, without any reduction of the degree of crystallinity. All these effects have been found to occur independent of the Vectra-B concentration, within the investigated range (2 to 20%, w/w). The results have been interpreted in terms of an incrased nucleation density of the blends, probably due to heterogeneous substances, initially present in the Vectra-B bulk, which dissolve to saturation in the PPS phase, during melt-blending.     

A layered architecture for flexible Web service invocation

Web service composition is emerging as an interesting approach to integrate business applications and create intra‐organizational business processes. Single Web services are combined to create a complex Web service that will realize the process business logic. Once the process is created, it is executed by an orchestration engine that invokes individual Web services in the correct order. However, Web services composing the workflow sometimes become unavailable during the run‐time phase, blocking process execution. This paper describes an architecture that allows the flexible orchestration of business processes. With this approach, Web services composing the process can be automatically substituted with other compatible Web services during process execution. A methodology is defined to evaluate Web service compatibility based on interface matching, in order to select substitutable Web services. Copyright © 2005 John Wiley & Sons, Ltd.     

The ponding problem on flat steel roof grids

Due to several reasons, a flat steel roof grid of industrial or commercial single-story buildings may be very flexible in the vertical direction. Due to its flexibility, a ponding effect can take place. The rainwater fills the space created by vertical deflection of the roof grid and this space increases under the gradually accumulated rainwater until equilibrium is reached.Ponding may be full or partial, and it is a self exciting phenomenon that can lead to grid instability. The problem is strongly non-linear, since the rainwater distribution on the roof grid in not known a priori.A closed form response to particular ponding cases and a simple grid geometry is achieved. Moreover, a non-linear finite element technique is presented in order to study the small/large deflection solution to the ponding problem of a complex flat steel roof grid.Finally, several steel roof grids are examined in order to illustrate the effect of precambering, grid dimensions and vertical flexibility on the ponding effect. The practical significance of a large deflection analysis for practical situations is also elucidated.     

Dependence of kinetic variables in the short-term release of Hg<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> and Zn<Superscript>2+ </Superscript>ions into synthetic saliva from an high-copper dental amalgam

The short term (up to 14 days after restoration) release of selected ions (i.e., Hg(2+), Cu(2+) and Zn(2+)) from Dispersalloy into artificial saliva has been evaluated in regards to the nature of the saliva (Fusayama and McCarty and Shklar's solutions), the amount of amalgam, the time of contact and the periodical renewal (every 48 h interval) of artificial saliva. The evaluation of the ionic fraction of such metals has been accomplished by using anodic stripping methods (i.e., Differential Pulse Anodic Stripping Voltammetry, DPASV) with a 7 microm graphite disk microelectrode as a working electrode. Data obtained in this work are almost unprecedented in the literature due the fact that such analytical method exclude metals in non-ionic forms (e.g., metals or organometallic compounds). The high concentrations measured in every experimental condition confirm the concern for the short-term release of metals from amalgam into saliva.     

Linear MMSE estimation of time-frequency variant channels for MIMO-OFDM systems

This paper proposes two low-complexity two-dimensional channel estimators for MIMO-OFDM systems derived from a joint time-frequency channel estimator. The estimators exploit both time and frequency correlations of the wireless channel via use of Slepian-basis expansions. The computational saving comes from replacing a two-dimensional Slepian-basis expansion with two serially concatenated one-dimensional Slepian-basis expansions. Performance in terms of normalized mean square error (NMSE) vs. signal-to-noise ratio (SNR) is analyzed via numerical simulations and compared with the original estimator. The analysis of the performance takes into account the impact of both system and channel parameters. The estimators are finally tested when used within the loop of an iterative receiver for MIMO-OFDM systems.     

Fatigue behaviour of tensile steel/CFRP joints

In this paper the fatigue performance of tensile steel/CFRP (Carbon Fibre Reinforced Polymer) double shear lap joints is discussed. Joints were realized with two steel plates and two CFRP strips bonded using epoxy adhesive. Fatigue tests were performed on 16 specimens under constant stress range loading cycles. Two stress ratios (R = 0.1 and R = 0.4) were considered to investigate their influence on the fatigue lifetime. Debonding was observed to occur at stress concentration zones and propagate along the CFRP/adhesive interfaces. The stiffness degradation of the steel joint due to progressive debonding of the adhesive represents an index for the subsequent and progressive global failure. S–N curves are defined and compared to the fatigue resistance of welded detail categories of the Eurocode 3. The tests showed that the stress ratio, R, has a marginal influence on the fatigue lifetime of the steel/CFRP double shear lap joints. Finally, a fatigue limit corresponding to a stress range in the steel plate equal to 75 MPa was conservatively estimated during the tests. The fatigue limit seems to be insensitive to the stress ratio R.