Nanocrystalline TiO2 photosensitized with natural polymers with enhanced efficiency from 400 to 600 nm

TiO₂ sensitization for solar applications requires not only efficient but also stable and inexpensive sensitizers. Different condensed tannins extracted from bark wastes of tropical wood trees were studied as possible sensitizers of TiO₂. These natural polymers adhere strongly to the TiO₂ even from aqueous solutions. Absorption spectra are presented for 1 mM aqueous sensitizing solutions prepared with lyophilized condensed tannins which absorb light in the visible range. Spectral photocurrent measurements and I–V characterization show that no bias is required for electron injection to the TiO₂ from all studied condensed tannins. Incident photon to current efficiency (IPCE) analysis indicates that surface complexation originates absorption bands with different electron injection efficiencies. These play a dominant role in determining IPCE spectral shape. We propose that surface modification by the sensitizer changes the surface trap density, thereby decreasing recombination losses.     

Grouped Approach for the Design of H.264/AVC Motion Estimation Architectures

This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state‐of‐the‐art designs.     

Use of recycled copper slag for blended cements

Copper slag is a by‐product generated during smelting to extract copper metal from the ore. The copper slag obtained may exhibit pozzolanic activity and may therefore be used in the manufacture of addition‐containing cements. In this paper the effect of the incorporation of the copper slag in cement is measured. Blends of copper slag with Portland cement generally possess properties equivalent to Portland cement containing fly ash, but very different to the silica fume incorporation. Copper slag and fly ash reduce the heat of hydration more effectively than silica fume in mortars. The replacement of 30% cement by copper slag reduces the flexural and compressive strength in a similar way to fly ash; however, after 28 days, the reduction is less than the percentage of substitution. Hydrated calcium aluminate phases were analysed using scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques. The pozzolanic activity of copper slag is similar to that of fly ash and higher than silica fume. In the presence of low water/cement ratios, certain pozzolanic materials produce a very compact cement paste that limits the space available for hydration products, a determining factor in the formation of hydrated calcium aluminates. SEM was found to be a useful analytical technique when aluminates are formed and can be clearly detected by XRD. Copyright © 2008 Society of Chemical Industry     

Challenges in the Application of Stochastic Modal Identification Methods to a Cable-Stayed Bridge

This paper presents an analysis of the data collected in the ambient vibration test of the International Guadiana cable-stayed Bridge, which links Portugal and Spain, based on different output-only identification techniques: peak-picking, frequency domain decomposition, covariance-driven stochastic subspace identification, and data-driven stochastic subspace identification. The purpose of the analysis is to compare the performance of the four techniques and evaluate their efficiency in dealing with specific challenges involved in the modal identification of the tested cable-stayed bridge, namely the existence of closely spaced modes, the perturbation produced by the local vibration of stay-cables, and the variation of modal damping coefficients with wind velocity. The identified natural frequencies and mode shapes are compared with the corresponding modal parameters provided by a previously developed numerical model. Additionally, the variability of some modal damping coefficients is related with the variation of the wind characteristics and associated with a component of aerodynamic damping.     

Experimental and simulation studies of gas sorption processes in polycarbonate films

This work reports the experimental isotherms describing the concentration of oxygen and nitrogen in poly(bisphenol A carbonate-co-4,4′-(3,3,5-trimethylcyclohexylidene) diphenol carbonate) vs pressure, at 30 °C. The solubility coefficients are interpreted in terms of the Flory-Huggins theory, obtaining reasonable values for the enthalpic polymer-gas parameter. A new method is outlined to simulate the probabilities of inserting/removing a gas molecule in a host matrix already containing n molecules of gas. The simulated isotherms representing the pressure dependence of the concentration exhibit the same pattern as those experimentally obtained.     

Autoimmune hemolytic anemia and posthepatitis-C liver cirrhosis

Here we are presenting the case of a 70-years-old woman who has hepatic cirrhosis anti-HCV and insulin-dependent diabetes mellitus, without relevant epidemiologic ascendants or previous transfusions and HBV, HIV negatives. On admission to our hospital she showed signs of autoimmune hemolytic anaemia (AHA) which was confirmed by positive direct Coombs test and an improvement in blood test after corticoid treatment. Having discarded other possible causes such as drugs infectious diseases or essential mixed cryoglobulinemia (CME), we put forward the possible association between AHA and infection by HCV, where AHA was an extrahepatic immunological manifestation of HCV. This fact has never been brought to light in previous medical literature.     

Effect of cyclosporin on the activity of cytidine deaminase and adenosine deaminase in the serum and polymorphonuclear leukocytes of patients with rheumatoid arthritis

Cytidine deaminase (CDA) and adenosine deaminase (ADA) were investigated in the serum and polymorphonuclear leukocytes (PMNLs) of healthy controls and ten patients with rheumatoid arthritis before and during cyclosporin therapy. CDA was significantly raised in the serum and decreased in the cells of patients. A dramatic increase (10-fold or more) in CDA activity was observed in the cells of some patients after only one month of cyclosporin therapy. Serum CDA significantly increased after three months' therapy. While the increase in serum CDA level during therapy was transient, the enzyme level in cells remained permanently raised, as shown in two patients evaluated for sixteen months. ADA in the serum of RA patients was somewhat higher as compared with healthy controls and remained almost unchanged during cyclosporin therapy. ADA activity in the cells also increased, but compared with the increase in CDA activity this increase was lower. Cyclosporin increased both CDA and ADA activities in PMNLs of RA patients. The dramatic increase in CDA observed in PMNLs of patients could be the cause of the transient increase in CDA in the serum. Further investigations will show to what extent this property of cyclosporin can reflect the immunoregulatory effect of this drug.     

Treatment of essential arterial hypertension with hypercholesterolemia. Effects of an alpha-adrenergic blocker and an inhibitor of the angiotensin converting enzyme

BACKGROUND: Hypertension and hypercholesterolemia are frequently associated with this leading to considerable cardiovascular risk. METHODS: An open parallel randomized study was performed in which the effects of doxazosin, an alpha-adrenergic blocker and enalapril, an inhibitor of the angiotensin converting enzyme were compared in 70 patients with essential high blood pressure and plasma cholesterol levels greater than 240 mg/dl. Following 2-4 weeks of placebo administration the patients were randomly treated with one of the two drugs. When required doses were increased and hydrochlorothiazide added until blood pressure lower than 160/95 mmHg was achieved. After this period the patients were observed for a minimum of 8 weeks. The mean length of the study was of 22 weeks. RESULTS: Both drugs significantly reduced blood pressure without modifying cardiac frequency. Doxazosin tended to favorably modify the lipid profile of the plasma while enalapril significantly reduced the levels of cholesterol, lipids and high density lipoproteins (HDL). Upon termination of the study the total HDL/cholesterol index increased 8.6% in those treated with doxazosin and decreased 5.5% in those receiving enalapril (p < 0.05). CONCLUSIONS: Although doxazosin and enalapril are potent antihypertensive drugs, the effects on plasma lipid obtained with doxazosin indicate that a reduction in cardiovascular risk was achieved with this drug in the patients included in this study.     

Acetohydroxy acid synthase and threonine deaminase activities, and the biosynthesis of isoleucine-leucine-valine in Streptococcus bovis

Acetohydroxy acid synthase (AHAS) and threonine deaminase (TD) activities were found in Streptococcus bovis and shown to be involved in the biosynthesis of the branched chain amino acids isoleucine, leucine and valine. Apparent lack of repression of AHAS synthesis by the end-products and reduced sensitivity of S. bovis growth to analogues of the branched chain amino acids suggested that secretion of isoleucine, leucine and valine in the growth medium may be a consequence of the regulatory features of AHAS. A glycyl-leucine-resistant mutant with reduced TD activity secreted a reduced amount of isoleucine and an increased amount of valine, which might be a result of the reduced rate of synthesis of the isoleucine precursor alpha-ketobutyrate and of a consequent preferential carbon flow through the valine branch of the pathway.