Cell-associated glucans of Burkholderia solanacearum and Xanthomonas campestris pv. citri: a new family of periplasmic glucans

The cell-associated glucans produced by Burkholderia solanacearum and Xanthomonas campestris pv. citri were isolated by trichloroacetic acid treatment and gel permeation chromatography. The compounds obtained were characterized by compositional analysis, matrix-assisted laser desorption ionization mass spectrometry, and high-performance anion-exchange chromatography. B. solanacearum synthesizes only a neutral cyclic glucan containing 13 glucose residues, and X. campestris pv. citri synthesizes a neutral cyclic glucan containing 16 glucose residues. The two glucans were further purified by high-performance anion-exchange chromatography. Methylation analysis revealed that these glucans are linked by 1,2-glycosidic bonds and one 1,6-glycosidic bond. Our 600-MHz homonuclear and 1H-13C heteronuclear nuclear magnetic resonance experiments revealed the presence of a single alpha-1,6-glycosidic linkage, whereas all other glucose residues are beta-1,2 linked. The presence of this single alpha-1,6 linkage, however, induces such structural constraints in these cyclic glucans that all individual glucose residues could be distinguished. The different anomeric proton signals allowed complete sequence-specific assignment of both glucans. The structural characteristics of these glucans contrast with those of the previously described osmoregulated periplasmic glucans.     

Synthesis of S-dithiocarbonates with polymer-supported xanthates

Summary Polymer-supported ammonium salts of methyl and ethyl xanthates react with alkyl halides to yield S-dithiocarbonates.     

State-space caching revisited

State-space caching is a verification technique for finite-state concurrent systems. It performs an exhaustive exploration of the state space of the system being checked while storing only all states of just one execution sequence plus as many other previously visited states as available memory allows. So far, this technique has been of little practical significance: it allows one to reduce memory usage by only twoo to three times, before an unacceptable blow-up of the run-time overhead sets in. The explosion of the run-time requirements is due to redundant multiple explorations of unstored parts of the state space. Indeed, almost all states in the state space of concurrent systems are typically reached several times during the search.In this paper, we present a method to tackle the main cause of this prohibitive state matching: the exploration of all possible interleavings of concurrent executions of the system which all lead to the same state. Then, we show that, in many cases, with this method, most reachable states are visited only once during state-space exploration. This enables one not to store most of the states that have already been visited without incurring too much redundant explorations of parts of the state space, and makes therefore state-space caching a much more attractive verification method. As an example, we were able to competely explore a state space of 250,000 states while storing simultaneously no more than 500 states and with only a three-fold increas of the run-time requirements.     

Specific respiratory manifestations associated with hemorrhagic rectocolitis. Analysis of a case and review of the literature

In a 59-year-old woman suffering from the syndrome of inappropriate antidiuretic hormone secretion, a small cell carcinoma of the uterine cervix was detected. The tumor was immunoreactive for antidiuretic hormone as well as for neuron specific enolase, chromogranin A, and Leu-7, but not vimentin. Electron microscopic examination of the tumor revealed neurosecretory granules. To our knowledge, this is only the second report of the syndrome of inappropriate antidiuretic hormone secretion with small cell carcinoma of the uterine cervix and the first one confirmed immunohistopathologically.     

Determination of fruit origin by using 26S rDNA fingerprinting of yeast communities by PCR–DGGE: preliminary application to Physalis fruits from Egypt

The determination of geographical origin is a demand of the traceability system of import–export food products. One hypothesis for tracing the source of a product is by global analysis of the microbial communities of the food and statistical linkage of this analysis to the geographical origin of the food. For this purpose, a molecular technique employing 26S rDNA profiles generated by PCR–DGGE was used to detect the variation in yeast community structures of three species of Physalis fruit (Physalis ixocarpa Brat, Physalis pubescens L, Physalis pruinosa L) from four Egyptian regions (Qalyoubia, Minufiya, Beheira and Alexandria Governments). When the 26S rDNA profiles were analysed by multivariate analysis, distinct microbial communities were detected. The band profiles of Physalis yeasts from different Governments were specific for each location and could be used as a bar code to discriminate the origin of the fruits. This method is a new traceability tool which provides fruit products with a unique biological bar code and makes it possible to trace back the fruits to their original location. Copyright © 2009 John Wiley & Sons, Ltd.     

A TRL-Like Calibration for Tunable Interdigitated BST Varactors

We report on a de-embedding technique for measuring the reflection coefficients of comblike capacitors patterned on barium-strontium-titanate (BST) ferroelectric films. The technique is derived from the thru-reflect-line calibration technique and is combined with conformal mapping to retrieve the complex permittivity of BST thin films. The accuracy of the method is demonstrated over a broad frequency for 0.3-mum-thick Ba_xSr_1-xTiO₃, with x = 0.5, in a paraelectric state, grown by a sol-gel technique. The samples are characterized up to 35 GHz and exhibit a constant permittivity of 245 plusmn 12%, which is in good agreement with the values deduced from propagation wave constants of BST transmission lines.     

Role of microstructure and residual stresses on fatigue crack initiation of carbonitrided steels

In this paper the role of microstructure and residual stresses on fatigue crack initiation of gaseous carbonitrided steels is examined. Optimum for austenite content in the case is investigated for microstructures containing bainite and for those without bainite. Fractographic study suggests subsurface initiation sites for notched specimens when austenite content is high and initiation sites at the surface when austenite is low.     

A coupled study by floating-gate and charge-pumping techniques ofhot carrier-induced defects in submicrometer LDD n-MOSFET's

The creation of defects by hot-carrier effect in submicrometer (0.85-μm) LDD n-MOSFETs is analyzed by the floating-gate and the charge-pumping techniques. It is emphasized that the floating-gate technique is an attractive tool for characterizing the oxide traps located in the drain-gate overlap region, near the oxide spacer of the LDD structures. This work gives new insight into the creation of acceptorlike oxide traps which are electrically active only after electron injection phases. These defects are generated in the whole stress gate bias range (from V_d/8 to V_d) by hot-hole and/or hot-electron injections, and their generation rates (10^-9 and 10^-2 for electron and hole injections, respectively) are one decade greater than for the interface state generation. Two-dimensional simulations show that they are mainly responsible for the I_d-V_g degradation of the LDD MOSFETs, and that the trap concentrations deduced from charge-pumping experiments are consistent with the I _d-V_g degradation     

Conformal anodic oxidation of aluminum thin films

Membrane-based synthesis, also called template synthesis, is a very general approach used to prepare arrays of nanomaterials with monodispersed geometrical features. The most commonly used porous templates are track-etched polycarbonate and porous anodic alumina membranes. Common to all these templates is the fact that the pores are perpendicular to the surface of the membrane. Here, a novel approach is presented, where the pores are synthesized parallel to the surface of the membrane. For the first time, the anodic oxidation of an aluminum thin film is performed laterally, i.e., parallel to the surface of the substrate, instead of perpendicular as usually done. For low anodic oxidation voltages (between 3 and 5 V) we obtain highly regular and ordered pore arrays, at least over a few hundred nanometers length, with a minimum pore size of approximately 3 to 4 nm. With such porous alumina structures, the controlled in-plane organization of arrays of template-grown nanowires and carbon nanotubes for reproducible device fabrication should be much easier.