Creation of Superhydrophobic Electrospun Nonwovens Fabricated from Naturally Occurring Poly(Amino Acid) Derivatives

Creation of superhydrophobic materials bio‐inspired by nature fascinates many scientists. One of the most intriguing challenges in this field is the fabrication of these materials using biopolymers from the viewpoint of green chemistry and environmental chemistry. Here, superhydrophobic and biodegradable nonwovens are constructed by electrospinning from a naturally occurring poly(amino acid), poly(γ‐glutamic acid) (γ‐PGA), modified with a hydrophobic α‐amino acid, l ‐phenylalanine. The contact angle of a water droplet on the materials is 154°, and the droplet remains stuck to the material surface even if it is inverted, clearly indicating a petal‐type superhydrophobic property. Biodegradability and post‐functionalization of the nonwovens as well as cell adhesion on the superhydrophobic materials are also evaluated. As far as we know, this is the first report on biodegradable materials exhibiting a petal‐type superhydrophobicity. The material design and processing shown here can be applied to various bioresources and such functional materials will become a new class of functional materials satisfying some of the requirements in green science.     

Polymer-based fabrication techniques for enclosed microchannels in biomedical applications

Investigations and analyses of body fluids like serum or whole blood are essential tasks in biomedical research in order to understand and diagnose diseases, to conduct pharmacological tests or to culture cells. Therefore, microfluidic systems provide a favorable tool for processing fluid samples as they allow downscaling of sample volumes and handling of single fluid components such as cells or proteins. For this reason, we present simple fabrication techniques for microchannel systems using polymer materials only. The demonstrated fabrication procedures are based on combinations of acrylic glass and the photo resists SU-8 and PerMX3020. On the one hand, these materials are low-priced compared to conventional silicon or glass. On the other hand, they have not shown any interaction with blood or other cell suspensions within the frame of our study. Furthermore, their transparency guarantees an easy observability of all processes within the system. Depending on the channel dimensions, different adhesion bonding techniques for closing of the systems are applied, whereas the fluidic interfaces are included by mechanical drilling. Summing up, we provide complete fabrication processes for fluidic systems which are simpler and more cost-effective than conventional methods and yet cope with all essential requirements for microfluidic applications.     

Impact of podcasting on student motivation in the online learning environment

Researchers investigated the impact of podcasting on student motivation in the online environment during fall 2008 and spring 2009. Data were collected from students enrolled in fourteen online courses at a research university in the United States. One hundred and ninety-one students completed a modified version of the Instructional Materials Motivation Survey (Keller, 2006); it has four subscales: attention, relevance, confidence, and satisfaction. Strong positive relationships between all subscales were detected. Results indicate students were moderately motivated by the use of podcasts in their online courses. Statistically significant differences in student motivation based on gender, class standing, and prior online learning experience were found. Benefits of using podcasts and recommendations for improvement of the multimedia files were offered by users.     

Theoretical and Experimental Analysis of a Laser Textured Thrust Bearing

In this article, a laser partially textured thrust bearing is theoretically and experimentally analyzed. An adiabatic model is developed in order to theoretically investigate the performances of the bearing. The bearing sample is partially textured both in radial and circumferential direction using the laser texturing process. The performance of the bearing (fluid film thickness and friction torque) is evaluated on a specially adapted test rig and the experimental results are compared with the theoretical model. A good agreement is found between the theoretical model and the experimental data. Also a comparison between a laser textured bearing and a bearing textured using the photolithographic method is presented.     

Managing People to Promote Innovation

There is growing evidence available to suggest that Human Resource Management (HRM) practice is an important predictor of organizational performance. Drawing upon organizational learning perspectives, we argue that HRM systems also have the potential to promote organizational innovation. We present longitudinal data from thirty‐five UK manufacturing organizations to suggest that effective HRM systems – incorporating sophisticated approaches to recruitment and selection, induction, appraisal and training – predict organizational innovation in products and production technology. We further show that organizational innovation is enhanced where there is a supportive learning climate, and inhibited (for innovation in production processes) where there is a link between appraisal and remuneration.     

Analysis of ternary mixtures with a single dynamic microbial sensor and chemometrics using a nonlinear multivariate calibration

An amperometric biosensor based on immobilized bacterial cells of Alcaligenes eutrophus KT02 and an oxygen electrode was integrated in a flow-through system. Because microorganisms metabolize various organic analytes in a specific manner, the sensor shows for different pure analytes distinct time-dependent oxygen consumption rates that can be treated as characteristic patterns. This behavior is conserved also when the biosensor is exposed to a mixture of these organic analytes; the sensor with a particular type of microorganisms responds with a total signal. The respiration curves as time-dependent amplitudes were subdivided into several time channels. This procedure creates an additional data dimension and makes the single sensor "dynamic". Using multivariate calibration models with only one single biosensor, simultaneous quantitative analysis of ternary mixtures of acetate, L-lactate, and succinate was realized. A nonlinear algorithm that compensated for conceivable interactions of the analytes was superior to a partial least-squares algorithm. Each analyte was predicted more precisely by the nonlinear approach resulting in root-mean-square errors of prediction of 0.20 mg/L for acetate, 0.43 mg/L for L-lactate, and 0.73 mg/L for succinate.     

Observation of the dynamics of live cardiomyocytes through a free-running scanning near-field optical microscopy setup

We report the observation of live-cell dynamics by noncontact scanning near-field optical microscopy (SNOM) modified to work with living biological samples that are fully immersed in liquid. We did not use the SNOM setup in strictly near-field conditions (we used 1-mum constant-height mode); however, we could examine the dynamics of rhythmically beating cardiac myocytes in culture with extremely high vertical sensitivity below the nanometric range. We could halt scans at any point to record localized contraction profiles of the cell membrane. We show that the contractions of the organisms changed shape dramatically within adjacent areas. We believe that the spatial dependency of the contractions arises because of the measurement system's ability to resolve the behavior of individual submembrane actin bundles. Our results, combining imaging and real-time recording in localized areas, reveal a new, to our knowledge, noninvasive method for using SNOM setups for studying the dynamics of live biological samples.     

Action of pure ethanol and some alcoholic beverages on the gastric mucosa in healthy humans: a descriptive endoscopic study

A method for the simultaneous determination of residues of 17 beta-trenbolone and 17 beta, 19-nortestosterone and their epimers in animal tissues is described, involving immunoaffinity chromatography clean-up and high-performance liquid chromatography with dual-wavelength UV detection. The method has been validated at 2 micrograms/kg in pig and cattle liver and corned beef with recoveries of 41% upwards. The method has been applied to the determination of incurred residues of 19-nortestosterone and trenbolone. Various alternative extraction steps for incurred trenbolone have been investigated, including direct extraction, protease digestion, heating and ultrasonic probe treatment. Glucuronidase digestion has been shown to be the most effective method for this analyte.