Genotoxic effect of Physalis angulata L. (Solanaceae) extract on human lymphocytes treated in vitro

Physalis angulata L (Solanaceae) is a medicinal plant from North of Brazil, whose different extracts and infusions are commonly used in the popular medicine for the treatment of malaria, asthma, hepatitis, dermatitis and rheumatism. However, the genotoxic effects of P. angulata on human cells is not well known. The main purpose of the present study was to evaluate the in vitro genotoxic effects of aqueous extract of P. angulata using the comet assay and the micronucleus assay in human lymphocytes provided from 6 healthy donors. Treatments with P. angulata extracts were performed in vitro in order to access the extent of DNA damage. The comet assay has shown that treatments with P. angulata at 0.5, 1.0, 2.0, 3.0 and 6.0 microg/mL in culture medium were genotoxic. Lymphocytes treated with P. angulata at the concentrations of 3.0 and 6.0 microg/mL in culture medium showed a statistically significant increase in the frequency of micronucleus (p<0.05), however, the cytokinesis blocked proliferation index (CBPI) was not decreased after P. angulata treatment. In conclusion, the present work demonstrated the genotoxic effects of P. angulata extract on human lymphocytes in vitro.     

Catalysis by intermetallic compounds II. The behaviour of the pseudobinary alloy systems CeRh3–x Pdx and ZrRh3–xPdx for buta-1,3-diene hydrogenation

The hydrogenation of buta-1,3-diene in the temperature range 45–110°C at 1 bar (101·5 kPa) total pressure has been studied using the pseudo-binary alloy systems MRh_3–x Pd_x (M = Ce, Zr; 0 ≤ x ≤ 3) as catalysts. Characterisation studies show that surface and bulk Rh/Pd ratios are very similar but the surfaces were enriched particularly in cerium, with strong indications of oxide formation. Similar conclusions can be drawn with respect to zirconium but to a smaller extent. Differencs in product distributions, particularly in butene distributions are discussed in terms of two mechanisms which can interpret differences between the Rh-rich system and the Pd-rich system in respect of cis/trans-but-2-ene ratios.     

Staphylococcus aureus nasal carriage in a Moroccan dialysis center and isolates characterization

Staphylococcus aureus, which has its ecological niche in the anterior nares, has been shown to cause a variety of infectious diseases mainly for patients in hemodialysis units. We performed this study to evaluate the prevalence of nasal S. aureus carriage among hemodialysis outpatients, to determine the antimicrobial susceptibility of isolates, to characterize the virulence genes, and to identify associated risk factors. Nares swab specimens were obtained from 70 outpatients on hemodialysis between March and June 2010. Samples were plated immediately onto S. aureus specific media and pattern of antibacterial sensitivity was determined using disk diffusion method. Polymerase chain reaction was used to detect nuc, mecA, and genes encoding staphylococcal toxins. Medical record of patients was explored to determine S.aureus carriage risk factors. Nasal screening identified 42.9% S. aureus carriers with only one (3.3%) methicillin‐resistant S. aureus isolate. Among the methicillin‐susceptible S. aureus isolates, high rate of penicillin resistance (81.8%) has been detected. The identified risk factors were male gender and age ≤ 30 years. Research of virulence factors showed a high genetic diversity among the 30 S. aureus isolates. Twenty‐one (70%) of them had at least one virulence gene, of which 3.3% were Panton‐Valentine leukocidin (lukS/F‐PV) genes. S. aureus carriage must be screened for at regular intervals in hemodialysis patients. Setting up a bacterial surveillance system is one of the strategies to understand the epidemiology of methicillin‐resistant S. aureus, to guide local antibiotic policy and prevent spread of antibiotic‐resistant S. aureus.     

An analytical mechanical model to describe the response of NiTi rotary endodontic files in a curved root canal

AimTo build a mathematical model describing the mechanical behavior of NiTi rotary files while they are rotating in a root canal.MethodologyThe file was seen as a beam undergoing large transformations. The instrument was assumed to be rotating steadily in the root canal, and the geometry of the canal was considered as a known parameter of the problem. The formulae of large transformations mechanics then allowed the calculation of the Green–Lagrange strain field in the file. The non-linear mechanical behavior of NiTi was modeled as a continuous piecewise linear function, assuming that the material did not reach plastic deformation. Criteria locating the changes of behavior of NiTi were established and the tension field in the file, and the external efforts applied on it were calculated. The unknown variable of torsion was deduced from the equilibrium equation system using a Coulomb contact law which solved the problem on a cycle of rotation.ResultsIn order to verify that the model described well reality, three-point bending experiments were managed on superelastic NiTi wires, whose results were compared to the theoretical ones. It appeared that the model gave a good mentoring of the empirical results in the range of bending angles that interested us.ConclusionsKnowing the geometry of the root canal, one is now able to write the equations of the strain and stress fields in the endodontic instrument, and to quantify the impact of each macroscopic parameter of the problem on its response. This should be useful to predict failure of the files under rotating bending fatigue, and to optimize the geometry of the files.     

Nonlinearly viscoelastic analysis of asphalt mixes subjected to shear loading

This study presents the characterization of the nonlinearly viscoelastic behavior of hot mix asphalt (HMA) at different temperatures and strain levels using Schapery’s model. A recursive-iterative numerical algorithm is generated for the nonlinearly viscoelastic response and implemented in a displacement-based finite element (FE) code. Then, this model is employed to describe experimental frequency sweep measurements of two asphalt mixes with fine and coarse gradations under several combined temperatures and shear strain levels. The frequency sweep measurements are converted to creep responses in the time domain using a phenomenological model (Prony series). The master curve is created for each strain level using the time temperature superposition principle (TTSP) with a reference temperature of 40°C. The linear time-dependent parameters of the Prony series are first determined by fitting a master curve created at the lowest strain level, which in this case is 0.01%. The measurements at strain levels higher than 0.01% are analyzed and used to determine the nonlinear parameters. These parameters are shown to increase with increasing strain levels, while the time–temperature shift function is found to be independent of strain levels. The FE model with the calibrated time-dependent and nonlinear material parameters is used to simulate the creep experimental tests, and reasonable predictions are shown.     

Catalysis by intermetallic compounds I. A comparison of the catalytic behaviour of CePd3, ZrPd3 and Pd sponge for buta-1,3-diene hydrogenation and but-1-ene hydroisomerisation

The hydrogenation of buta-1,3-diene and more briefly, the hydroisomerisation of but-1-ene catalysed by powdered CePd₃, ZrPd₃ and Pd sponge has been studied in a fixed bed continuous flow microreactor at 1 bar (101·5 k Pa) total pressure and in the temperature range 45–225°C. The two intermetallics (CePd₃, ZrPd₃) exhibited greater selectivity for butene formation than palladium, especially at high buta-1,3-diene conversions. The superior selectivity of the intermetallics was demonstrated further under the more demanding conditions, whereby but-1-ene was added to the feed buta-1,3-diene in the ratio C₄H₈/C₄H₆ = 24. The kinetics and apparent energies of activation were determined for the hydrogenation and isomerisation reactions. In the case of buta-1,3-diene hydrogenation, the kinetics suggest that for Pd sponge, hydrogen and buta-1,3-diene adsorb on similar sites, whereas in the case of the intermetallics different sites may be involved for hydrogen and buta-1,3-diene adsorption, which may result from palladium—metal oxide interactions. In the case of but-1-ene isomerisation, double bond migration appears to occur via addition–abstraction mechanisms on all three catalysts but in the case of the intermetallics hydrogenation and isomerisation involve different rate determining steps.     

A distributed lightweight Redundancy aware Topology Control Protocol for wireless sensor networks

WSN consists of a large number of sensor nodes randomly deployed, and, in many cases, it is impossible to replace sensors when a node failure occurs. Thus, applications tend to deploy more nodes than necessary to cope with possible node failures and to increase the network lifetime, which leads to create some sensing and communication redundancy. However, sensors in the same region, may collect and forward the same information, which will waste more energy. In this paper, we propose a distributed Lightweight Redundancy aware Topology Control Protocol (LRTCP) for wireless sensor networks. It exploits the sensor redundancy in the same region by dividing the network into groups so that a connected backbone can be maintained by keeping a minimum of working nodes and turning off the redundant ones. LRTCP identifies equivalent nodes in terms of communication based on their redundancy degrees with respect of some eligibility rules. Simulation results indicate that, compared with existing distributed topology control algorithms, LRTCP improves network capacity and energy efficiency.     

Effect of São Pedro do Sul thermal water on skin irritation

Many mineral waters are known for centuries for treating dermatological diseases but there is little scientific evaluation of the effects of these waters in skin. A total of 17 healthy Caucasian volunteers, including men and women, were enrolled in this study. Two skin sites were marked on each volunteer forearm and irritated with sodium lauryl sulphate at 2% (w/v) kept under occlusion for 24 h with Finn chambers. Afterwards, purified water or São Pedro do Sul (SPS) thermal water were applied to the irritated skin sites, and kept under occlusion for 48 h also with Finn chambers. Transepidermal water loss (TEWL) was used as a measure of the skin barrier function to evaluate the potential anti‐irritant effect of the thermal water on skin. Statistically significant differences in the mean TEWL variations were observed for the skin treated with SPS thermal water and with purified water (P = 0.036). The thermal water reduced the degree to which the skin barrier was disrupted compared with purified water alone in 82.4% of the volunteers. The SPS thermal water is anti‐irritant and, therefore, can be helpful to relieve skin irritation and in cosmetic formulations to improve the tolerability of the products.     

Effect of compaction conditions on aggregate packing using 2-dimensional image analysis and the relation to performance of HMA

Characterization of the asphalt mixture microstructure using two dimensional (i.e., 2-D) imaging techniques could be an economically efficient approach. However, the features that have been captured and quantified using 2-D imaging techniques in most published research are limited to simplistic analyses of aggregate structure. This paper focuses on introducing a more elaborate method for characterization of the internal structure of aggregates to define performance related parameters that could be used as quality indicators of mixes. These indicators are proposed as important properties that complement the volumetric properties so wide relied on for acceptance of mixture designs. The results of the study show that aggregate structure can be characterized using a combination of newly developed image analysis indices namely: number of aggregate-to-aggregate proximity zones, total proximity zone length, and proximity zone plane orientation. A software developed in a previous study and significantly modified for this study, is used to process digital images of a set of asphalt mixtures with different gradations, binder contents, types of modification, compaction efforts, compaction temperatures, and methods. The results demonstrate that the internal structure indices correlate well with rutting performance, as well as with low temperature thermal contraction of asphalt mixtures. Additionally, the indices can be successfully used to show the effects of compaction effort, compaction method and temperature, gradation of aggregates, and binder modification on the mixture internal structure. The results indicate potential for using this method for quality control of mixtures during production.