Controlling the Er content of porous silicon using the doping current intensity

The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process.

PACS

81.05.Rm; 82.45.Rr     

Phase-II randomized study of pre-operative IL-2 administration in operable NSCLC

In recent years, the Th1/Th2 concept has become of prime importance in the understanding of heterogeneous responses of the immune system and implications thereof for infectious and autoimmune diseases. Originally established on the basis of different cytokines produced by T cell clones, it is now known that the Th1/Th2 concept really defines totally different immune pathways that affect most if not all cells of the immune system. Murine experimental leishmaniasis was the first model to confirm the relevance of the Th1/Th2 concept in vivo. Herein, we summarize the current knowledge on the characteristics and generation of Th1 and Th2 cells, as well as on recent advances of the application of this concept to murine cutaneous leishmaniasis.     

Human apolipoproteins A-I and A-II in cell cholesterol efflux: studies with transgenic mice

The first step in reverse cholesterol transport is the movement of cholesterol out of cells onto lipoprotein acceptors in the interstitial fluid. The contribution of specific lipoprotein components to this process remains to be established. In this study, the role of human apolipoproteins (apo) A-I and A-II in the efflux of cellular cholesterol was investigated in transgenic mouse models in which the expression of murine apoA-I was abolished due to gene targeting (A-IKO). Serum from A-IKO mice and from mice expressing human apoA-I and/or human apoA-II was incubated with [3H]cholesterol-labeled Fu5AH rat hepatoma cells for 4 hours at 37 degrees C. The cholesterol efflux to the serum of A-IKO mice was markedly lower than that to the serum of mice transgenic for human apoA-I (5.0 +/- 1.5% versus 25.0 +/- 4.0%). Expression of human apoA-II alone did not modify the cholesterol efflux capacity of A-IKO mouse serum. Cholesterol efflux to serum of mice expressing human apoA-II together with human apoA-I was significantly lower than that to human apoA-I mouse serum (20.0 +/- 2.3% versus 25.0 +/- 4.0%). Regression analysis of cholesterol efflux versus the lipid/apolipoprotein concentrations of mouse serum suggested that 3 independent factors contribute to determine the cholesterol efflux potential of serum: the apolipoprotein composition of HDL, the serum concentration of HDL phospholipids, and the presence of a small fraction of particles containing apoA-I.     

The characterization of the V species and the identification of the promoting effect of dopants in V/Ti/O catalysts for o-xylene oxidation

The present work deals with the study of the role of promoters in TiO₂-supported vanadium oxide, catalyst for the oxidation of o-xylene to phthalic anhydride. Two different series of catalysts were prepared, the first one consisting of undoped samples having different vanadium oxide content, and the second one of samples having 7 wt.% V₂O₅ and variable amounts of Sb and Cs as promoters. All the samples were characterized by means of Raman spectroscopy, X-ray diffraction and thermal-programmed reduction and oxidation, in order to define a method for the quantification of the different V species (i.e., isolated vanadium, dispersed polyvanadate and bulk vanadium oxide) that develop on TiO₂ support in the presence of promoters. It was found that polyvanadate and bulk vanadium oxide spontaneously release molecular oxygen at 600–650 °C, whereas the isolated V is not susceptible of self-reduction. The latter species is predominant in samples having low vanadium oxide loading (≤2 wt.% V₂O₅, with TiO₂ surface area 22.5 m²/g), and possesses the highest intrinsic activity in o-xylene conversion. The presence of Sb, a promoter of activity, increases the dispersion of the most active species and also hinders its segregation in the reaction environment. These promoting effects are more pronounced when both Cs and Sb are present.     

Dynamic provisioning of availability-constrained optical circuits in the presence of optical node failures

This paper investigates what impact optical node failures may have on wavelength-division-multiplexed networks, in which reliable end-to-end optical circuits are provisioned dynamically. At the node level, the optical cross-connect (OXC) equipment availability measure is estimated using proven component level availability models. At the network level, end-to-end optical circuits are provisioned only when the level of connection availability required by the application can be guaranteed. With the objective of yielding efficient utilization of the network resources, i.e., fibers and OXCs, circuit redundancy is achieved by means of shared path protection (SPP) switching, in combination with differentiated reliability (DiR). The resulting optimal routing and wavelength assignment problem is proven to be NP-complete. To produce suboptimal solutions in polynomial time, a heuristic technique is presented, which makes use of a time-efficient method to estimate the end-to-end circuit availability in the presence of multiple (link and node) failures. Using the proposed heuristic, a selection of representative OXC architectures and optical switching technologies is examined to assess the influence of the node equipment choice on the overall network performance.     

Quality of service provision in electric power distribution systems through reliability insurance

Traditional methods for regulating electricity distribution grids have several weaknesses in terms of incentives, risk allocation, consumer preferences, and the value of reliability. Rate of Return and Performance Based Regulation do not provide incentives for both cost efficiency and quality of service. These regulatory structures also allocate the risk of outages almost entirely to consumers and fail to incorporate consumer preferences for reliability/service quality. Additionally, investments in system reliability are not explicitly valued. This paper proposes an insurance scheme for reliability as a possible solution. Reliability insurance provides economically efficient investment incentives and alleviates consumers' reliability risk. Consumers provide economic signals to the distribution provider for their desired quality of service through insurance contracts. The value of reliability to consumers is thereby made transparent, allowing Distribution Companies (DisCo's) to make efficient investment decisions. Insurance also allocates outage risk to the DisCo (which controls the system), instead of consumers (who have little or no control over reliability). Reliability insurance effectively unbundles delivery and reliability services and enables consumers to receive differentiated reliability based upon their value for this service. This paper describes the potential for reliability insurance to improve both efficiency and risk allocation compared to conventional regulatory structures.     

Clinical significance of erythrosedimentation rate in cancer in relation to cytokine production: correlation with high IL-6 and low IL-2 blood concentrations

Despite its well documented unfavourable prognostic significance in several human diseases, including cancer, the cytokinic mechanisms responsible for an increased erythrosedimentation rate (ESR) still remain to be better analyzed and defined. The recent possibility to measure cytokine concentrations in the blood of patients has allowed us to explore the possible relation between ESR values and endogenous cytokine secretions. This preliminary study was performed to evaluate the relationship between ESR values and serum levels of IL-2 and IL-6, which represent the most important cytokines responsible for the activation and the suppression, respectively, of host anticancer immune reaction. The study included 33 consecutive solid tumor patients, 22 of whom showed distant organ metastases. Abnormally high values of ESR were present in 21 patients, including 18/22 metastatic patients and 3/11 nonmetastatic patients. Patients with elevated values of ESR showed significantly higher mean levels of IL-6 and significantly lower mean concentrations of IL-2 with respect to those found in patients with normal ESR values. These results would show that cancer-related increase in ESR values is associated with low levels of IL-2 and high levels of IL-6. Since IL-2 plays an essential role in the anticancer immunity and IL-6 may suppress the antitumor immune defenses, the evidence of low levels of IL-2 and high values of IL-6 in cancer patients with increased ESR values would explain the unfavourable prognostic significance of high ESR values in human neoplasms.     

Clinico-radiological and functional aspects of respiratory syndromes caused by collagen diseases

The clinical and radiological features in 100 patients with collagen diseases (rheumatoid arthritis, lupus, sclerodermia, dermatomyositis, and panarteritis nodosa) were compared with respiratory performance. 56 patients were drawn from the series of Pende et Al. and 44 from a personal series. The results are set out in tables and graphs. It was found that lung lesions due to collagen disease have no special clinical and radiological features. Respiratory performance is that of a restrictive syndrome that gradually progresses from A.R. to E.S., S. and P.M., accompanied by obstruction of the large airways, as shown by hyperinsufflation in sclerodermia and reduced specific conductance in rheumatoid arthritis.