Comparison and Optimization of Quantification Methods for Shigella flexneri Serotype 6 O-antigen Containing Galacturonic Acid and Methyl-Pentose

Shigella is a leading diarrheal cause of morbidity and mortality worldwide, especially in low- and middle-income countries and in children under five years of age. Increasing levels of antimicrobial resistance make vaccine development an even higher global health priority. S. flexneri serotype 6 is one of the targets of many multicomponent vaccines in development to ensure broad protection against Shigella. The O-antigen (OAg) is a key active ingredient and its content is a critical quality attribute for vaccine release in order to monitor their stability and to ensure appropriate immune response. Here, the optimization of two methods to quantify S. flexneri 6 OAg is reported together with the characterization of their performances. The optimized Dische colorimetric method allows a tenfold increment of the sensitivity with respect to the original method and is useful for fast analysis detecting selectively methyl-pentoses, as rhamnose in S. flexneri 6 OAg. Also, a more specific HPAEC-PAD method was developed, detecting the dimer galacturonic acid-galactosamine (GalA-GalN) coming from S. flexneri 6 OAg acid hydrolysis. These methods will facilitate characterization of S. flexneri 6 OAg based vaccines. The colorimetric method can be used for quantification of other polysaccharide containing methyl-pentoses, and the HPAEC-PAD could be extended to other polysaccharides containing uronic acids.     

INTERFERENCE AND SHARING CONSIDERATIONS BETWEEN THE SPACE OPERATIONS/SPACE RESEARCH SERVICE AND NEW APPLICATIONS OF THE FIXED SERVICE NEAR 2 GHz

Many satellite projects use radio frequencies in the bands 2025–2110 MHz and 2200–2290 MHz for spacecraft operations and data transmission. Frequencies below a few GHz are of particular interest because of favourable propagation conditions and attractive antenna designs. The above bands have to be shared with the fixed service and the mobile service. The fixed service has announced plans for the introduction of vast quantities of a new type of application, referred to as the point-to-multipoint system to be used for data distribution or local access systems. At International Telecommunications Union (ITU) meetings, scenarios assuming the worldwide deployment of more than one million new fixed service installations have been presented. This paper assesses the interference potential from point-to-multipoint systems to conventional direct links between spacecraft and earth stations. The interference into the space as well as into the ground segment has been investigated. Typical earth stations with a 15 m dish size have been assumed. Interference received at low earth orbiters as well as geostationary satellites has been evaluated. It is shown that sharing will not be possible without technical or operational constraints on the fixed service systems. © 1997 by John Wiley & Sons, Ltd.     

一种基于区分服务和AMR编码技术的VoIP QoS解决方案

文章提出了一个将网络和终端相结合的VoIPQoS方案.该方案在网络提供区分服务的基础上,终端采用AMR(Adaptive Multi-Rate)语音编码技术,编码率根据网络状况自适应地调整.模拟实验表明,此方案能够较好地使网络和终端协调工作来保证QoS.     

Finite cladding effects in W-fibres: a new interpretation of leakage losses

According to both experiments and calculations, the HE11 mode in depressed inner-cladding single-mode fibres should not be described beyond cutoff with the leaky mode formalism but with a formalism of coupling between a core mode and discrete, lossy cladding modes.     

Matrices de répartition pour des systèmes ouverts. application aux problèmes de couplage en optique guidée

The theory of scattering matrix is extended for connections between two open waveguides. The scattering matrices are infinite, but they may be denumerable. In case of reciprocal lossless connections, they are unitary and symmetrical. Some previous results on the excitation of an optical waveguide are generalized and the problem of the transition from a multimode fiber to a monomode guide is discussed. Generally one cannot specify the performances of such a transition without specifying the incident field, i.e., one must say how the light is launched into the fiber and what is the propagation length.     

Plasma cleaning technique for the removal of mixed materials

Erosion of materials by physical sputtering is the most fundamental of plasma–surface interactions in tokamaks. Carbon and tungsten materials planned to be used in ITER divertor are subjected to erosion, which produces local redeposition of mixed layers. Tritium retention in mixed materials is the major concern due to the limits imposed for safety reason by nuclear licensing. No technique has yet been proven capable of remove trapped tritium in ITER operating environment. In-situ oxidative cleaning techniques have been developed to remove co-deposits. Since oxygen can be incompatible with Be first wall (getter effect), a plasma cleaning using hydrogen–argon gas mixture has been proposed in this work. C–W mixed materials were produced for this purpose by capacitively coupled RF plasma sputtering. The process has been investigated by optical emission spectroscopy and Langmuir probe.