Implementing surfactant mass balance in 2D FEM�CALE models

Practical aspects of implementing surfactant mass balance computation in finite elements models, where the model geometry shape change is captured by utilizing the arbitrary Lagrange–Eulerian method are discussed briefly. The discussion and the reported simulations are carried out in two-dimensional Cartesian coordinates. Two alternative approaches to formulating the governing equation of surfactant mass balance for solving it computationally are presented and discussed. One of the approaches is based on computing the boundary curvature and boundary tangential velocity, as well as their differentials on the boundary, directly. The other approach is based on reformulating the governing equation in order to track the proportional rate of change of local surface area. As a conclusion, it is found that though both of the presented approaches can be configured to perform adequately in terms of surfactant mass conservation, surface differentials that are necessary to compute the surface curvature and surface tangential velocity in the first one of the methods evoke numerical oscillations near those points of the boundary where it is not smooth. The text is accompanied by example simulations and figures.     

Real-time effective density monitor (DENSMO) for aerosol nanoparticle production

A new instrument, density monitor (DENSMO), for aerosol particle size distribution characterization and monitoring has been developed. DENSMO is operationally simple and capable of measuring the effective density as well as the aerodynamic and the mobility median diameters with a time resolution of 1 s, from unimodal particle size distributions. The characterization is performed with a zeroth order mobility analyzer in series with a low pressure impactor and a filter stage. The operation of DENSMO was investigated with sensitivity analysis and, based on the results, optimal operation parameters were determined. DENSMO was also compared, in lab test measurements, against a reference method with several particle materials with bulk densities from 0.92 to 10.5 g/cm³. The results show that the deviation from the reference method was less than 25% for suitable materials.

Copyright © 2016 American Association for Aerosol Research     

Enhanced performance in the deteriorated area of multicrystalline silicon wafers by internal gettering

The deteriorated area of the multicrystalline silicon (mc‐Si) ingots grown by directional solidification, commonly known as the Red Zone, is usually removed before wafering. This area, characterized by poor minority carrier lifetime, is located on the sides, at the top, and the bottom of the mc‐Si ingots. In this study, the effect of internal gettering by oxygen precipitates and structural defects has been investigated on the bottom zone of a mc‐Si ingot. Nucleation and growth of oxygen precipitates as well as low temperature annealing were studied. Photoluminescence imaging, lifetime mapping, and interstitial iron measurements performed by μ‐PCD reveal a considerable reduction of the bottom Red Zone. An improvement of lifetime from below 1 µs to about 20 µs and a reduction of interstitial iron concentration from 1.32 × 10¹³ at/cm³ to 8.4 × 10¹⁰ at/cm³ are demonstrated in this paper. Copyright © 2013 John Wiley & Sons, Ltd.     

Distribution of Nitrogen in the Cationized Potato Starch Granule

The distribution of a cationic reagent in the potato starch granule derivatized by reaction with 1,2-epoxypropyl trimethylammonium chloride was studied by ESCA spectroscopy. It was possible to detect and quantify the contents of nitrogen derived from proteinous material and nitrogen derived from the cationizing reagent on the surfaces of starch preparations. The results show that the differences in nitrogen distribution between cationic starches prepared by different (dry or wet) methods are negligible. According to the result it seems that the cationization takes place more easily in the amorphous material of the inner parts of the granule than in the crystalline amylopectin layer of the surface.     

Development of testing procedure for ceramic disc filters

Small-scale laboratory tests for sizing and designing disc filters are typically performed by using leaf test equipment. Although the basic tests are fairly simple and quick, the accuracy and repeatability of the results may be poor due to various reasons. In addition to errors caused by variations in the structure of the equipment, also the skills and experience of the person performing the tests is of great importance. This paper introduces an experimental study carried out for defining the most important sources of errors in these kinds of laboratory tests and for estimating their influence on the final test results. The results obtained in this study were utilized for designing an improved version of the test equipment and also for creating a standard procedure for performing the tests. The results acquired with the small-scale laboratory tests were in good agreement with the performance results obtained from full-scale ceramic disc filters operating in industrial processes.     

3‐Heterocycle‐Phenyl N‐Alkylcarbamates as FAAH Inhibitors: Design,Synthesis and 3D‐QSAR Studies

Carbamates are a well‐established class of fatty acid amide hydrolase (FAAH) inhibitors. Here we describe the synthesis of meta‐substituted phenolic N‐alkyl/aryl carbamates and their in vitro FAAH inhibitory activities. The most potent compound, 3‐(oxazol‐2yl)phenyl cyclohexylcarbamate ( 2 a ), inhibited FAAH with a sub‐nanomolar IC₅₀ value (IC₅₀=0.74 nM ). Additionally, we developed and validated three‐dimensional quantitative structure–activity relationships (QSAR) models of FAAH inhibition combining the newly disclosed carbamates with our previously published inhibitors to give a total set of 99 compounds. Prior to 3D‐QSAR modeling, the degree of correlation between FAAH inhibition and in silico reactivity was also established. Both 3D‐QSAR methods used, CoMSIA and GRID/GOLPE, produced statistically significant models with coefficient of correlation for external prediction (R²_PRED) values of 0.732 and 0.760, respectively. These models could be of high value in further FAAH inhibitor design.     

Strength retention of drawn self-reinforced polyglycolide rods and fixation properties of the distal femoral osteotomies with these rods. An experimental study on rats

Drawn self-reinforced polyglycolide (SR-PGA) rods, Ø 2 mm and 26 mm long, were implanted in the dorsal subcutaneus tissue of 16 rats. Osteotomies of the distal femur were fixed with SR-PGA rods (2 mm by 15 mm) in another 38 rats. The follow-up times varied from one week to one year. After sacrifice, three-point bending and shear tests were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of osteotomized and intact control femora were also performed. At three weeks the flexural strength of the rods was 50% of the initial value, and the flexural modulus was 46% of the initial value. Five osteotomy specimens had to be excluded due to dislocation or non-union. One of the 33 evaluated osteotomy specimens showed signs of postoperative infection. Thirty-two osteotomies healed uneventfully. No gross signs of inflammatory or foreign-body reaction were observed. The amount of osteoid surface and active osteoid formation surface reached their highest value in the histomorphometrical analysis at 24 weeks. The present investigation demonstrated that the mechanical strength and fixation properties of the drawn SR-PGA rods are suitable for fixation of cancellous bone osteotomies in rats. The present article is the first report on the successful application of drawn SR-PGA rods for fixation of cancellous bone osteotomies.     

Neural network modelling of word production in Finnish: coding semantic and non-semantic features

The objective of our research is to computationally model word production and its disorders by means of artificial neural networks. In the current study we develop and analyze an algorithm that generates a distributed semantic coding from a given semantic tree-structure classification of words. With the algorithm it is possible to generate semantic representations that are compact and easy to modify. This renders the coding method suitable for our multilayer perceptron-based neural network model of word production. The model is shown to be able to account for a variety of performance patterns observed in four Finnish aphasia patients suffering from word-finding difficulties.