Biopolymeric coatings for delivery of antibiotic and controlled degradation of bioresorbable Mg AZ31 alloys

Magnesium and magnesium alloys are attracting considerable interest as biodegradable materials with high potential for application as temporary implants. The high corrosion rate of Mg-based implants is considered a serious drawback, and it is crucial to design novel surface protection strategies that minimize the detrimental effects of corrosion, while contributing for introducing additional functionalities on the material surface. In this work, a layer-by-layer coating architecture composed of an inner poly(lactic-co-glycolic) acid layer, working as adhesion promoter, and additional polycaprolactone (PCL) layers working as reservoirs for antibiotic (levofloxacin) and for nanohydroxyapatite (nanoHA) particles was applied on the Mg alloy AZ31. The results demonstrate that the composition and number of PCL layers can tailor the biodegradation of the bare magnesium alloy, surface wettability, and the kinetics of release of antibiotic (levofloxacin). The distribution of nanoHA in the coating architecture plays a crucial role on tailoring the desired biocompatible functionalities and corrosion protection of the bare alloy.     

Normal relationships between cardiovascular variables in active orthostatism and clinostatism in postural change

OBJECTIVE: Autonomic modulation of hemodynamics, essential for the preservation of homeostasis, is well tested by the abrupt postural change from clinostatism to active orthostatism. The aim of this work was to study normal relationships between the cardiovascular variables in active orthostatism and those in clinostatism. METHODS: Hemodynamic parameters in clinostatism and orthostatism were easily measured in 20 healthy subjects of both sexes, aged between 33 and 78 years, without treatment, using the non-invasive thoracic electric bioimpedance method. RESULTS: Cardiovascular variables values in orthostatism are linearly related with their values in clinostatism. CONCLUSIONS: Results show that cardiovascular variables in active orthostatism are linearly related with their values in clinostatism, each variable being specially regulated. A clinostatism and orthostatism intraindividual correlation was obtained, which provides an easily accessible method of detection and interpretation of autonomic dysfunctions, without deleterious consequences for the subjects, which can be very useful for research on physiopathologic mechanisms.     

General strategy for biosensor design and construction employing multifunctional surface-tethered components

Biosensors function by reversibly linking bioreceptor-target analyte binding with closely integrated signal generation and can either continuously monitor analyte concentrations or be returned to baseline readout values by removal of analyte. We present an approach for producing fully reversible, reagentless, self-assembling biosensors on surfaces. In the prototype biosensor, quencher-dye-labeled biotin-linked E. coli maltose binding protein (MBP) bound in a specific orientation to a NeutrAvidin-coated surface is employed as a bioreceptor. To complete sensor formation, a modular tether arm consisting of a flexible biotinylated DNA oligonucleotide, a fluorescence resonance energy-transfer (FRET) donor dye, and a distal beta-cyclodextrin (beta-CD) analyte analogue is bound in an equimolar amount to the same surface by means of DNA-directed immobilization. After self-assembly, a baseline level of FRET quenching is observed due to specific interaction between the beta-CD of the flexible tether arm and the sugar binding site of MBP, which brings the two dyes into proximity. Addition of the target analyte, the nutrient maltose, displaces the linked beta-CD-dye of the DNA-based tether arm, and a concentration-dependent change in FRET results. Biosensor sensitivity and dynamic range can be controlled by either using MBP variants having different binding constants or by binding of modulator DNA oligonucleotides that are complementary to the flexible DNA tether. The sensor can be regenerated and returned to baseline quenching levels by washing away analyte. A complex set of interactions apparently exists on the sensing surface that may contribute to sensor behavior and range. This approach may represent a general way to assemble a wide range of useful biosensors.     

In-group members' perceptions of a social mobility attempt: Effects of boundary permeability and outcome.

This study examined in-group members' impressions of a fellow member who attempted to join a higher power group, along with the interactive effects of the permeability of group boundaries and relative success of this social mobility attempt on impressions. Because groups with less permeable boundaries are typically more cohesive, a group member's relative success in achieving mobility should have meaning for these groups, as opposed to those with more permeable boundaries. Thus, it was predicted that the effect of success versus failure on in-group members' evaluations would be stronger when group boundaries were less permeable. The results showed that a member successful at social mobility was evaluated more positively than one who was unsuccessful, and this difference was larger when boundaries were less permeable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nail surgery

Nail deformities may present as wither medical or cosmetic problems, often requiring surgical intervention. These deformities have a number of etiologic factors including infections, inflammatory disease processes, congenital abnormalities, trauma, tumors, and systemic diseases. This article discusses several nail problems and surgery techniques.     

The role of coherent vortices near the turbulent/non-turbulent interface in a planar jet

The role of coherent vortices near the turbulent/non-turbulent (T/NT) interface in a turbulent plane jet is analysed by a direct numerical simulation (DNS). The coherent vortices near the jet edge consist of large-scale vortical structures (LSVSs) maintained by the mean shear and intense vorticity structures (IVSs) created by the background fluctuating turbulence field. The radius of the LSVS is equal to the Taylor micro-scale R(lsvs)≈λ, while the radius of the IVS is of the order of the Kolmogorov micro-scale R(ivs)~η. The LSVSs are responsible for the observed vorticity jump at the T/NT interface, being of the order of the Taylor micro-scale. The coherent vortices in the proximity of the T/NT interface are preferentially aligned with the tangent to the T/NT interface and are responsible for the viscous dissipation of kinetic energy near the T/NT interface and to the characteristic shape of the enstrophy viscous diffusion observed at that location.     

Comparative estimation of the reproduction number for pandemic influenza from daily case notification data

The reproduction number, R, defined as the average number of secondary cases generated by a primary case, is a crucial quantity for identifying the intensity of interventions required to control an epidemic. Current estimates of the reproduction number for seasonal influenza show wide variation and, in particular, uncertainty bounds for R for the pandemic strain from 1918 to 1919 have been obtained only in a few recent studies and are yet to be fully clarified. Here, we estimate R using daily case notifications during the autumn wave of the influenza pandemic (Spanish flu) in the city of San Francisco, California, from 1918 to 1919. In order to elucidate the effects from adopting different estimation approaches, four different methods are used: estimation of R using the early exponential-growth rate (Method 1), a simple susceptible-exposed-infectious-recovered (SEIR) model (Method 2), a more complex SEIR-type model that accounts for asymptomatic and hospitalized cases (Method 3), and a stochastic susceptible-infectious-removed (SIR) with Bayesian estimation (Method 4) that determines the effective reproduction number Rt at a given time t. The first three methods fit the initial exponential-growth phase of the epidemic, which was explicitly determined by the goodness-of-fit test. Moreover, Method 3 was also fitted to the whole epidemic curve. Whereas the values of R obtained using the first three methods based on the initial growth phase were estimated to be 2.98 (95% confidence interval (CI): 2.73, 3.25), 2.38 (2.16, 2.60) and 2.20 (1.55, 2.84), the third method with the entire epidemic curve yielded a value of 3.53 (3.45, 3.62). This larger value could be an overestimate since the goodness-of-fit to the initial exponential phase worsened when we fitted the model to the entire epidemic curve, and because the model is established as an autonomous system without time-varying assumptions. These estimates were shown to be robust to parameter uncertainties, but the theoretical exponential-growth approximation (Method 1) shows wide uncertainty. Method 4 provided a maximum-likelihood effective reproduction number 2.10 (1.21, 2.95) using the first 17 epidemic days, which is consistent with estimates obtained from the other methods and an estimate of 2.36 (2.07, 2.65) for the entire autumn wave. We conclude that the reproduction number for pandemic influenza (Spanish flu) at the city level can be robustly assessed to lie in the range of 2.0-3.0, in broad agreement with previous estimates using distinct data.     

Development and validation of a grouping method for pesticides analysed in foodstuffs

The cost effective monitoring of hundreds of pesticide residues in foodstuffs of vegetable origin involves the definition of groups of analytes associated with homogeneous performance parameters of the used analytical method. The performance of the analytical method only needs to be tested on a daily base for some of these group’s compounds. This work proposes a strategy for defining groups of compounds with homogeneous physical–chemical properties based on the evaluation of the similarity of the multivariate pattern of five of these properties namely: molar mass, melting point, vapour pressure at 20 °C, n-octanol–water partition coefficient and solubility in water at 20 or 25 °C. Three independent and competing multivariate analysis tools, namely Principal Component Analysis, Hierarchical Clustering and K-Mean Clustering were used. This strategy was successfully used to group 100 pesticides into nine clusters, with 1–40 pesticides, represented by a compound with within group average properties. The developed grouping method was validated using physical–chemical data from other references or compounds and produced groups consistent with the performance of the studied determination of pesticide residues in dried red bean. The mean analyte recoveries of groups with larger dimension are statistically different for a confidence level of 95%. The within group coefficients of variance of mean analyte recoveries of larger groups ranged from 6.7% to 8.5%. This grouping method can reduce the number of recovery tests performed for the validation of the analytical method or test quality control.     

A Magneto-Sonic Type Rod Position Monitoring System for Nuclear Power Plants

Current nuclear power plant rod position monitoring systems utilize transducers that operate mainly on electro-magnetic principles. This paper describes a system that utilizes a magneto-sonic transducer operating on a combination of magnetic and sonics techniques. A magnetostrictive sonic torsional delay line provides the time interval-position relationship. The system exhibits continuous resolution, high reliability, and an accuracy of better than ±1% for a rod travel of 150 inches. The transducer has been qualified for nuclear power plant Safety Class IE operation.     

A comparison of attitude, personality, and knowledge predictors of service-oriented organizational citizenship behaviors.

Attitude, personality, and customer knowledge antecedents were compared in their predictive ability of 3 service-oriented forms of employee organizational citizenship behaviors (OCBs): loyalty, service delivery, and participation. For the 1st study, 236 customer-contact employees provided data concerning their OCBs and the attitude, personality, and knowledge antecedents. The 2nd investigation relied on data provided by 144 contact employees from a network of university libraries. Using hierarchical regression in both studies, the authors found that each of the 3 types of service-oriented OCBs was best predicted by different subsets of the antecedents. Job attitudes accounted for the most unique variance in loyalty OCBs, personality accounted for the most unique variance in service delivery OCBs, and customer knowledge and personality jointly were the best predictors of participation OCBs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)