Physicochemical and structural characteristics of TiC and VC thin films deposited by DC reactive magnetron sputtering

Vanadium carbide and titanium carbide films were deposited on Si substrates by direct current reactive magnetron sputtering, varying the substrate temperature during deposition and the reactive gas (CH₄) pressure. The physicochemical and structural properties of the films were characterized for stoichiometric films (V/C = 1 and Ti/C = 1), which display good performance concerning wear, friction, and corrosion. The techniques used to characterize the films were Rutherford backscattering spectrometry in channeling geometry, ¹²C(α,α)¹²C nuclear resonant scattering, glancing angle X-ray diffraction, X-ray reflectometry, and X-ray photoelectron spectroscopy. The results revealed that the ideal conditions for deposition of these films are a CH₄ partial pressure of 0.5 × 10⁻³ mbar and a substrate temperature of 400 °C. In such conditions, the deposition rates are 7 nm s⁻¹ for TiC and 8.5 nm s⁻¹ for VC at a target power density of 5.5 W cm⁻². The density of the films, as determined here by X-ray reflectometry, are slightly higher than those for the bulk materials.     

Physicochemical, crystallinity, pasting and morphological properties of bean starch oxidised by different concentrations of sodium hypochlorite

The effect of bean starch oxidation at different active chlorine concentrations (0.5%, 1.0% and 1.5%) on the physicochemical, crystallinity, pasting and morphological properties of starch was investigated. The carbonyl content, carboxyl content, starch colour, swelling power, solubility, gel hardness, X-ray crystallinity, pasting properties, gelatinisation characteristics and morphology of the starches were evaluated. The bean starch oxidised with 0.5% active chlorine had the characteristic of a slightly crosslinked starch. As compared to the native and 0.5% active chlorine-oxidised starches, active chlorine at 1.0% and 1.5% increased the carbonyl content, carboxyl content and solubility of the starches. Moreover, these concentrations of active chlorine decreased the swelling power, gel hardness, relative crystallinity, breakdown, peak viscosity and setback, as compared to the native and 0.5% active chlorine-oxidised starches. The starch granules oxidised with 1.5% active chlorine had imperfections in their structure, and its surface appears to be rougher than the other granules.     

A study of the promoting effect of noble metal addition on niobia and niobia alumina catalysts

The catalytic activity of Nb₂O₅ and Nb₂O₅/Al₂O₃-supported metal catalysts was evaluated in the n-heptane conversion, CO hydrogenation and butadiene hydrogenation. After high temperature of reduction (HTR), the metal adsorption capacity decreases on all the samples, due to the reduction of Nb₂O₅ with subsequent blocking of metal atoms and bimetallic effect.

It was also observed that the activity decay caused by metal-support interaction was remarkably inhibited on the bimetallics with respect to the monometallics by comparing reaction rates after HTR. Thus, the addition of Rh to Co, Cu to Pd and Sn to Pt on niobia catalysts significantly altered the product distribution in Fischer–Tropsch synthesis (FTS) and in the hydrogenation and dehydrogenation of hydrocarbons, respectively. In addition, an unusual bifunctional effect was obtained in Pt/Nb₂O₅/Al₂O₃ catalyst.     

Multi-biochemical responses of benthic macroinvertebrate species as a complementary tool to diagnose the cause of community impairment in polluted rivers

Biological indexes, based on benthic macroinvertebrate taxa, are currently used worldwide to measure river ecological quality. These indexes assign a global ecological status of the biotic community, but not necessarily may detect specific effects of water pollutants. Conversely a large set of biochemical markers measured in macroinvertebrate benthic species can detect sublethal effects and inform us about additional environmental factors that are impairing benthic communities. This is especially interesting in moderately polluted sites, where other stressors are already affecting communities but not too strongly to be detected by biotic indexes. Up to ten different markers belonging to distinct metabolic paths and 42 contaminants measured in sample collections of the caddis fly Hydropsyche exocellata were assessed across a polluted gradient in the industrialized Mediterranean River basins of Besós and Llobregat (NE, Spain). Twenty four sample collections were selected to include macroinvertebrate communities representing the five impairment degrees defined by the Spanish Environmental authorities using the biotic metrics. Results evidenced a clear deterioration of the ecological water quality parameters and benthic communities towards downstream reaches. Biochemical responses varied significantly across the studied samples and were able to differentiate samples within communities having a good and deteriorated ecological stage. Principal Component Analyses indicated that salinity was one of the major stresses affecting macroinvertebrate assemblages, whereas antioxidant and metabolizing enzymes responded differently and were closely related to high and presumably toxic levels of accumulated organic pollutants. Therefore these results indicate that the use of multiple -markers sensitive to water pollution may provide complementary information to diagnose environmental factors that are impairing macroinvertebrate communities.     

Partial safety factors for homogeneous reliability of nonlinear reinforced concrete columns

The design of reinforced concrete structures is based on the verification of the rules defined by standard specifications, where partial safety factors are introduced to ensure safety. However, the use of constant factors for different kinds of columns leads to inhomogeneous safety levels. In this paper, a new format for concrete and steel safety factors is proposed, in order to ensure uniform target reliability. These factors are given in terms of the column design parameters, such as material strengths, steel ratio, slenderness and loading eccentricity. The adopted mechanical model takes into account material and geometrical nonlinearities. The response surface technique is used to evaluate the structural reliability. Numerical applications show how the calibrated safety factors lead to a better design than those proposed by the Eurocode2.     

Adverse effects of respiratory disease medicaments and tooth brushing on teeth: A scanning electron microscopy,X‐ray fluorescence and infrared spectroscopy study

The present study aims to evaluate the effect of brushing with fluoride dentifrice on teeth severely affected by erosion due to respiratory medicaments. Enamel (n = 50) and dentin (n = 50) bovine specimens were prepared and treated with artificial saliva (S‐control), acebrofilin hydrochloride (AC), ambroxol hydrochloride (AM), bromhexine hydrochloride (BR), and salbutamol sulfate (SS) and subjected to cycles of demineralization (immersing in 3 mL, 1 min, three times a day at intervals of 1 hr, for 5 days) followed by remineralization (saliva, 37°C, 1 hr). Simulated brushing with fluoridated toothpaste was performed using 810 strokes in a reciprocal‐action brushing simulator. Scanning electron microscopy, micro energy dispersive X‐ray fluorescence (μ‐EDXRF) spectroscopy and attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy were then performed. μ‐EDXRF images showed extensive erosion after treatment with all medicaments. SEM images showed enamel erosion in order SS > BR > AC = AM > S after brushing and fluoridation. FTIR results were in agreement. In case of dentin, μ‐EDXRF measurements showed significant difference in mineral content (percent weight of calcium and phosphate) in SS + brushing + fluoridation treated enamel compared to control, while μ‐EDXRF images showed erosive effects in the order SS > AM>BR > AC = S post brushing + fluoridation. SEM images showed erosion in the order SS > AM = BR > AC > S post brushing + fluoridation. Again, FTIR multivariate results were in agreement. Overall, our study shows that proper oral care is critical when taking certain medication. The study also demonstrates the possible use of FTIR for rapid clinical monitoring of tooth erosion in clinics.     

Metabolic effects of aspartame in adulthood: A systematic review and meta-analysis of randomized clinical trials

Data about harms or benefits associated with the consumption of aspartame, a nonnutritive sweetener worldwide consumed, are still controversial. This systematic review and meta-analysis of randomized controlled clinical trials aimed to assess the effect of aspartame consumption on metabolic parameters related to diabetes and obesity. The search was performed on Cochrane, LILACS, PubMed, SCOPUS, Web of Science databases, and on a gray literature using Open Grey, Google Scholar, and ProQuest Dissertations &; Theses Global. Searches across all databases were conducted from the earliest available date up to April 13, 2016, without date and language restrictions. Pooled mean differences were calculated using a random or fixed-effects model for heterogeneous and homogenous studies, respectively. Twenty-nine articles were included in qualitative synthesis and twelve, presenting numeric results, were used in meta-analysis. Fasting blood glucose (mmol/L), insulin levels (μU/mL), total cholesterol (mmol/L), triglycerides concentrations (mmol/L), high-density lipoprotein cholesterol (mmol/L), body weight (kg), and energy intake (MJ) were considered as the main outcomes in subjects that consumed aspartame, and results were presented as mean difference; % confidence interval, range. Aspartame consumption was not associated with alterations on blood glucose levels compared to control (?0.03 mmol/L; 95% CI, ?0.21 to 0.14) or to sucrose (0.31 mmol/L; 95% CI, ?0.05 to 0.67) and on insulin levels compared to control (0.13 μU/mL; 95% CI, ?0.69 to 0.95) or to sucrose (2.54 μU/mL; 95% CI, ?6.29 to 11.37). Total cholesterol was not affected by aspartame consumption compared to control (?0.02 mmol/L; 95% CI, ?0.31 to 0.27) or to sucrose (?0.24 mmol/L; 95% CI, ?0.89 to 0.42). Triglycerides concentrations were not affected by aspartame consumption compared to control (0.00 mmol/L; 95% CI, ?0.04 to 0.05) or to sucrose (0.00 mmol/L; 95% CI, ?0.09 to 0.09). High-density lipoprotein cholesterol serum levels were higher on aspartame compared to control (?0.03 mmol/L; 95% CI, ?0.06 to ?0.01) and lower on aspartame compared to sucrose (0.05 mmol/L; 95% CI, 0.02 to 0.09). Body weight did not change after aspartame consumption compared to control (5.00 kg; 95% CI, ?1.56 to 11.56) or to sucrose (3.78 kg; 95% CI, ?2.18 to 9.74). Energy intake was not altered by aspartame consumption compared to control (?0.49 MJ; 95% CI, ?1.21 to 0.22) or to sucrose (?0.17 MJ; 95% CI, ?2.03 to 1.69). Data concerning effects of aspartame on main metabolic variables associated to diabetes and obesity do not support a beneficial related to its consumption.     

Fatty acids and cholesterol oxidation in salted and dried shrimp

The aim of this work was to evaluate the occurrence of cholesterol oxidation products and to analyze the lipidic profile in salted–dried shrimp. Fifty samples of salted–dried shrimp were evaluated, and the cholesterol oxides (7β-OH, 7α-OH, 7-Keto and 25-OH) were quantified by high-performance liquid chromatography. The cholesterol oxides: 7β-OH (34.63–72.56 μg/g), 7α-OH (5.02–12.12μg/g), 7-Keto (7.44–32.68 μg/g) and 25-OH (2.37–22.88 μg/g) were determined in all samples analyzed. Regarding to the total cholesterol content and the average thiobarbituric acid reactive substances (TBARS) content, the results ranged from 73.88 to 247.69 mg/100 g, and 0.02 to 1.30 mgMA/kg, respectively. The fatty acids profile was: 27.48% saturated, 43.90% monounsaturated and 28.61% polyunsaturated. The presence of cholesterol oxidation products and the values of TBARS indicate the degree of oxidation of this product, which was probably initiated by inadequate conditions of processing and storage.     

Short communication: profile of virulence factors of Staphylococcus aureus isolated from subclinical bovine mastitis in the state of Rio de Janeiro, Brazil

Staphylococcus aureus produces exoproteins that contribute to its ability to colonize the mammary gland such as hemolysins, coagulase, slime, and protein A. This study characterized phenotypically and genotypically these virulence factors in 50 Staph. aureus isolates. These isolates were obtained from milk samples from subclinical mastitis cases identified in 15 dairy cattle farms located in the state of Rio de Janeiro, Brazil. All of the confirmed Staph. aureus samples were PCR positive for the coa gene, which displayed 3 different size polymorphisms. The amplification of the spaA X region yielded a single amplicon for each isolate with the prevalent amplicon sized 315 bp. The Staph. aureus isolates were 24 and 16% positive for the hla and hlb genes, respectively, and 22 and 20% positive for the icaA and icaD genes, respectively. Amplification of the agr gene RNAIII was positive in 74% of the strains. Twenty-seven different profiles were identified among the samples, indicating a great diversity of Staph. aureus involved in the etiology of mastitis cases in the analyzed region. These findings are valuable to the comprehension of the distribution of the profiles of Staph. aureus strains isolated from subclinical mastitis cases in the state of Rio de Janeiro.     

The effect of inorganic particles on the breakdown strength and mechanical properties of EVA-based composites

Ethylene-vinyl acetate (EVA) copolymer was melt-blended with different inorganic particles, such as alumina trihydrate (ATH), montmorillonite-based organoclay (CLO15A) and organophilic silica (R202) to produce (nano)composites with outstanding electrical breakdown strength. The composites loaded with different amount of particles were characterized by dielectric, rheological, morphological and mechanical properties. The addition of the particles resulted in an increase of electrical breakdown strength, whose results depend on the nature and amount of filler. The addition of 1%–5% of ATH resulted in an increase of 50% of this property. Similar results were observed for the composites loaded with 7% of CLO15A and R202. All composites displayed low values of dielectric constant and dielectric loss, which is interesting for insulator applications. The presence of the filler did not exert great influence on the rheological properties of the composites, thus keeping the good processability of EVA matrix. Finally, the composites containing the organoclay presented the best mechanical response.