Study of the adhesion of Staphylococcus aureus to coated glass substrates

The adhesion of Staphylococcus aureus was studied using a selection of laboratory-prepared and commercially available coated glass substrates using a simple methodology. Substrates were examined by scanning electron microscopy, atomic force microscopy and water droplet contact angles. It was found that microbial adhesion was independent of surface roughness, when this was of a lower magnitude than microbial size. It was also found that microbial adhesion was greater for hydrophilic surfaces than for hydrophobic ones, but that on a photoinduced superhydrophilic surface, microbes were more spread out—a potential benefit for more effective photocatalytic disinfection. It is suggested that hydrophobic and photoinduced superhydrophilic surface coatings both have potential as a means of reducing microbial fouling of surfaces.     

Thermodynamic and Acoustic Properties of Mixtures of Dibromomethane + Heptane

Densities and speeds of ultrasound in binary mixtures of dibromomethane with heptane have been measured within the temperature range from 288.15 K to 318.15 K. From the experimental data, the thermodynamic excess volume, molar isobaric expansion, molar isentropic compression, and ultrasonic speed were calculated. The excess volume and excess isentropic compression have opposite signs, whereas the excess isobaric expansion is an S-shaped function of the mole fraction. An explanation was suggested to account for the excesses in terms of intermolecular interactions. It involved energetic and steric factors. Moreover, it was shown that the positive excess sound speed results almost entirely from the negative excess compression.     

Properties of CO2 laser-welded butt joints of dissimilar magnesium alloys

The paper presents results of keyhole laser beam welding of dissimilar magnesium alloys that have been carried out with the CO₂ laser of maximum power of 2.5 kW. The workpieces of die-cast alloys AZ91 and AM50 with thicknesses of 4.5 mm have been butt-welded with helium used as a shielding gas. With the chosen flow rate of helium shielding and the focal position set on the metal surface the nearly parallel fusion zones boundaries were obtained. The analysis of microstructures of the joints, measurements of hardness distribution and the elemental distribution in the weld cross-sections permitted to find the changes due to heating in the fusion zones and recrystallization. The static tensile strength tests and the three point bending tests have allowed to determine the mechanical properties of the joints. The corrosion resistance tests performed by the electrochemical method on samples of as-cast materials and samples with the welds of similar and dissimilar alloys have not displayed the differences in the corrosion resistance. However, the microscopic observations of surfaces of welded samples have shown the influence of the joints on corrosion development.     

Cutting data correction in Inconel 718 turning

The paper presents research work concerning difficult-to-cut materials turning and chipbreakers reliability in local operating features. Inconel 718 alloy was used as a sample material and two different chipbreakers were tested. The aim of the research was to check the efficiency of chipbreakers in the area of applications recommended by tool manufacturers. As a result, the algorithm for cutting data selection and correction which combines experiments and simulation processes concerning chip breakage effectiveness was built. To estimate chip forms in tests, the visual system equipped with a high-speed camera was used. The cutting forces measuring system provided information for verification of simulation results. The simulation based on the FEM was applied to estimate chip groove filling. Distributions of temperature and stresses on the tool rake face in the function of distance from the cutting edge were calculated. The paper gives recommendations for cutting data correction to achieve acceptable chip forms.     

ENDER: a statistical framework for boosting decision rules

Induction of decision rules plays an important role in machine learning. The main advantage of decision rules is their simplicity and human-interpretable form. Moreover, they are capable of modeling complex interactions between attributes. In this paper, we thoroughly analyze a learning algorithm, called ENDER, which constructs an ensemble of decision rules. This algorithm is tailored for regression and binary classification problems. It uses the boosting approach for learning, which can be treated as generalization of sequential covering. Each new rule is fitted by focusing on examples which were the hardest to classify correctly by the rules already present in the ensemble. We consider different loss functions and minimization techniques often encountered in the boosting framework. The minimization techniques are used to derive impurity measures which control construction of single decision rules. Properties of four different impurity measures are analyzed with respect to the trade-off between misclassification (discrimination) and coverage (completeness) of the rule. Moreover, we consider regularization consisting of shrinking and sampling. Finally, we compare the ENDER algorithm with other well-known decision rule learners such as SLIPPER, LRI and RuleFit.     

Society of self: The emergence of collective properties in self-structure.

Using cellular automata, the authors show how mutual influences among elements of self-relevant information give rise to dynamism, differentiation, and global evaluation in self-concept. The model assumes a press for integration that promotes internally generated dynamics and enables the self-structure to operate as a self-organizing dynamical system. When this press is set at high values, the self can resist inconsistent information and reestablish equilibrium after being perturbed by such information. A weak press for integration, on the other hand, impairs self-organization tendencies, making the system vulnerable to external information. Paradoxically, external information of a random nature may enhance the emergence of a stable self-structure in an initially disordered system. The simulation results suggest that important global properties of the self reflect the operation of integration processes that are generic in complex systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analyzing semiconductor devices using modulation spectroscopy

Improvements in the quality and yield of semiconductor devices will rely on characterization methods that are informative, nondestructive, convenient, easy to use, and inexpensive. Ideally, one would like to perform the characterization procedure at room temperature on entire wafers, possibly even before the structure is removed from the growth chamber. Because of their simplicity and proven ability, the contactless electro-modulation methods of photoreflectance and contactless electroreflectance are ideally suited for this purpose. Modulation spectroscopy has already been applied to examine such devices as heterojunction bipolar transistors, pseudomorphic high-electron-mobility transistors, quantum-well lasers, vertical cavity surface-emitting lasers, multiple-quantum-well infrared detectors, superlattice optical mirrors, resonant tunneling structures, solar cells, and metal-oxide-semiconductor configurations.     

High molecular arborescent polyoxyethylene with hydroxyl containing shell

Arborescent polyoxyethylene of high molar mass (2×10⁵ g/mol) and narrow molar mass distribution was synthesized in a three-stage process. In the first stage a triblock copolymer of ethylene oxide (central block, DP ca. 90) and 2,3-epoxypropanol-1 (short flanking blocks, DP ca. 5) was synthesized. The potassium alcoholate derived from this copolymer was used to initiate the polymerization of ethylene oxide and the subsequent addition of protected glycidol (1-etoxyethyl glycidyl ether). After deprotection the short polyglycidol blocks were used as branching units for the next generation. Repeated step by step process leads to the ‘pom-pom like’ branched polyoxyethylene macromolecules enriched with the reactive hydroxyl groups in the outer shell. The branched structure of the obtained polymers was evidenced by the size exclusion chromatography and NMR spectroscopy.     

Ambient fine particulate air pollution triggers ST-elevation myocardial infarction, but not non-ST elevation myocardial infarction: a case-crossover study

Background

We and others have shown that increases in particulate air pollutant (PM) concentrations in the previous hours and days have been associated with increased risks of myocardial infarction, but little is known about the relationships between air pollution and specific subsets of myocardial infarction, such as ST-elevation myocardial infarction (STEMI) and non ST-elevation myocardial infarction (NSTEMI).

Methods

Using data from acute coronary syndrome patients with STEMI (n?=?338) and NSTEMI (n?=?339) and case-crossover methods, we estimated the risk of STEMI and NSTEMI associated with increased ambient fine particle (<2.5 um) concentrations, ultrafine particle (10-100 nm) number concentrations, and accumulation mode particle (100-500 nm) number concentrations in the previous few hours and days.

Results

We found a significant 18% increase in the risk of STEMI associated with each 7.1 μg/m³ increase in PM_2.5 concentration in the previous hour prior to acute coronary syndrome onset, with smaller, non-significantly increased risks associated with increased fine particle concentrations in the previous 3, 12, and 24 hours. We found no pattern with NSTEMI. Estimates of the risk of STEMI associated with interquartile range increases in ultrafine particle and accumulation mode particle number concentrations in the previous 1 to 96 hours were all greater than 1.0, but not statistically significant. Patients with pre-existing hypertension had a significantly greater risk of STEMI associated with increased fine particle concentration in the previous hour than patients without hypertension.

Conclusions

Increased fine particle concentrations in the hour prior to acute coronary syndrome onset were associated with an increased risk of STEMI, but not NSTEMI. Patients with pre-existing hypertension and other cardiovascular disease appeared particularly susceptible. Further investigation into mechanisms by which PM can preferentially trigger STEMI over NSTEMI within this rapid time scale is needed.