Semi-empirical tight binding method for calculating energy levels of hydrogenated silicon nanoclusters as a function of size

A semi-empirical tight binding model is used for calculating energy levels of spherical hydrogenated silicon nanoclusters in the form of Si_mH_n and two independent bases. The first basis is the nearest neighbor approximation of sp³s^⁎ orthogonal basis and the second basis is the third nearest neighbor approximation of sp³ nonorthogonal basis. Also, bulk properties of silicon crystal are used in the calculations. As we expected, obtained results show that the change in the size of nanoclusters has a great influence on their energy levels. So optical properties of these nanoclusters can be controlled externally. A comparative study on the calculated results and experimental results also reveals a good agreement between the two approaches.     

An emerging pollutant contributing to the cytotoxicity of MSWI ash wastes: Strontium

In this study, we used the multiple toxicity characteristic leaching procedure to test the long-term leaching behavior of bottom ash, scrubber residue, and baghouse ash from a municipal solid waste incinerator (MSWI). We used the short-term viability percentage of African green monkey kidney cells (Vero cells) as a bioindicator to investigate the cytotoxicity of the leachates from the MSWI ash wastes. We found that strontium was a significant contributor to the cytotoxicity of the bottom ash.     

Assessment of structure variation in silicon nanowire FETs and impact on SRAM

Impact of device structure variability of silicon nanowire FETs is assessed and SRAM design implication is presented based on 3-D numerical simulation. Both the conventional and junctionless nanowire FETs are shown to be sensitive to structural variation whereas the former is more tolerable. Both the circular wire and non-circular wire cases for feasible SRAM design with a focus on read/write noise margin are included in our study.     

Effect of lasalocid on growth, blood gases, and nutrient utilization in dairy goats fed a high forage, low protein diet

This study investigated the effect of lasalocid on weight gain, blood gases, nutrient digestibility, and nitrogen utilization in growing dairy goats. In a growth experiment, 24 crossbred dairy does were assigned to diets without or with lasalocid (approximately 30 mg per head per day) for 12 wk. Goats were group fed bermudagrass hay for free choice plus concentrate at a fixed level (approximately 0.264 kg DM per head per d). Goats grew faster when fed lasalocid than those fed the control diet. Jugular blood partial pressure of O2 was lower when goats were supplemented with lasalocid. In contrast, goats fed lasalocid tended to have a higher partial pressure of CO2 than control goats. Percent O2 saturation tended to increase, and concentrations of total CO2 tended to decrease in goats fed lasalocid. Serum glucose and urea N did not differ between treatments. In a metabolism experiment, 8 castrated male goats were fed hay and concentrate identical to those of the growth experiment to determine whole tract nutrient digestibility and N utilization. Lasalocid did not affect feed intake or nutrient digestion coefficients. Daily urinary N output was reduced by lasalocid supplementation. In spite of this, N retention was not significantly affected. With use of ionophore, the proportion of urinary N relative to digested N tended to decrease, and the retained N as a proportion of digested N tended to increase.     

3PRS: a personalized popular program recommendation system for digital TV for P2P social networks

Digital TV channels require users to spend more time to choose their favorite TV programs. Electronic Program Guides (EPG) cannot be used to find popular TV programs. Hence, this paper proposes a personalized Digital Video Broadcasting — Terrestrial(DVB-T) Digital TV program recommendation system for P2P social networks. From the DVB-T signal, we obtain EPG of TV programs. The frequency and duration of the programs that users have watched are used to extract programs that users are interested in. The information is collected and weighted by Information Retrieval (IR). The program information is then clustered by k-means. Clusters of users are also grouped by k-means to find cluster relationships. In each group, we decide the most popular program in the group according to the program weight of the channel. When a new user begins to watch the TV program, the K-Nearest Neighbor (kNN) classification method is used to determine the user’s predicted cluster label. Then, our system recommends popular programs in the predicted cluster and similar clusters.     

Effects of Al2O3 on the hydration activity of municipal solid waste incinerator fly ash slag

This study investigates the effects of slag composition on the hydration activity of slag-blended cement (SBC) pastes. Synthetic slag samples were prepared by melting Al₂O₃-modified, municipal solid-waste incinerator (MSWI) fly ash. In addition to the original slag (containing 25.0% CaO and 17% Al₂O₃), two other synthetic slag types, A1 and A2 slag, were prepared, having a 15% or 5% Al₂O₃ content, respectively. These synthetic slags were blended with ordinary Portland cement (OPC) at weight ratios ranging from 10% to 40%. The results indicate that the incorporation of 10% A1 slag tended to enhance the degree of hydration in SBC pastes during the early ages (3-28 days), but at later ages, significant difference in the degree of hydration between the OPC and SBC pastes with 10% A1 slag was not observed. The tendency of the 10% A2 slag case was similar, but with a limited enhancement during the early ages (3-28 days). However, samples that incorporated the Al₂O₃-modified slag (AMS) showed decreased degrees of hydration. The degree of hydration of the 40% blend ratio sample decreased significantly.     

Toxicity assessment of volatile organic compounds and polycyclic aromatic hydrocarbons in motorcycle exhaust

This study investigates the toxicity of various pollutant species from motorcycle exhaust via dose-response analysis and margin of safety using Escherichia coli DH5 alpha. The toxicity evaluation of the major components of motorcycle exhaust volatile organic compounds (VOCs), collected with impinger, and polycyclic aromatic hydrocarbons (PAHs), collected with filter and XAD-2, is essential to determine emission standards for motorcycles. The toxicity of benzene (B), toluene (T), ethyl benzene (E) and xylene (X) was selected for comparison as standard VOCs emitted from motorcycles. In addition, three types of reformulated gasoline (high oxygenate and high benzene content (No. 1), low oxygen and high benzene (No. 2), and low oxygen and low benzene (No. 3) were prepared to reveal combined toxicity of individual compositions. Motorcycle exhaust is significantly more toxic than BTEX due to the highly toxic VOCs generated from incomplete combustion. Overall toxicity evaluation showed that the toxicity, indicated as EC50, was approximately as follows: PAHs>two-stroke engines>four-stroke engines>BTEX.     

Thermophoretic particle deposition efficiency in turbulent tube flow

This study investigated the thermophoretic particle deposition efficiency numerically. The critical trajectory was used to calculate thermophoretic particle deposition in turbulent tube flow. The numerical results obtained in turbulent flow regime in this study were validated by particle deposition efficiency measurements with monodisperse particles (particle diameter ranges from 0.038 to 0.498 μm) in a tube (1.18 m long, 0.43 cm i.d., stainless-steel tube). The theoretical predictions are found to fit the experimental data of Tsai et al. [Tsai, C. J., J. S. Lin, S. G. Aggarwal, and D. R. Chen, “Thermophoretic Deposition of Particles in Laminar and Turbulent Tube Flows,” Aerosol Sci. Technol., 38, 131 (2004)] very well in turbulent flows. In addition, an empirical expression has been developed to predict the thermophoretic deposition efficiency in turbulent tube flow.     

Some thermodynamic remarks on non-equilibrium fluid streams

The non-reversible heat transfer between two fluid streams is a complex problem requiring many data and becomes more complicated if the two streams involved in the process include two-phase and two-component fluids.This paper is presented to make some thermodynamic remarks and, in particular, to show that along a heat exchanger, in whatever section normal to the flow rate, every non-equilibrium fluid state can be represented by its corresponding equilibrium state and a nonequilibrium–equilibrium deviation measured by the corresponding entropy difference or essergy difference. Within this general statement, somewhat different results are obtained in the cases of single-phase fluids, two-phase one-component fluids, two-phase two-component fluids, and mixtures of a single-phase fluid and a two-phase fluid. It is necessary to point out that the concepts of “maximum obtainable work” and of “distance from equilibrium” have been often associated, directly or implicitly, to the concept of exergy, also in good books, that have considered exergy as the basic argument. The analysis developed by Evans and by others showed that not always the two concepts can be represented by a unique parameter. In the presence of non-equilibrium states in the system, the hypothesis of a reversible way cannot be assumed, not even as a limit. Thus, it was suitable the definition of essergy as a potential which never increases in the system time evolution and which represents the distance of the system state from the environment state. In addition, it is to be remarked that, if one determine the essergy ε for a system and F is a whatever strictly increasing function, also F∘ε is an essergy parameter with the same properties of the parameter ε.     

Revealing interactive toxicity of aromatic amines to azo dye decolorizer Aeromonas hydrophila

This study attempted to combine chemostat pulse technique (CPT) and dose-mortality assessment in pursuit of quantitative rankings of toxicity of model aromatic amines (MAAs) in the presence of diazo dye reactive red 141 (or Evercion Red H-E7B; RR141) upon Aeromonas hydrophila. As known, bacterial decolorization performance of azo dyes is directly dependent upon both the characteristics of biochemical reactivity and biotoxicity of dyes and related aromatic amines towards color removal. Thus, the findings herein indicated that the relative toxicity series of MAAs were (1) ortho > para > MAA-free control > meta position (for isomeric aminophenols); (2) –OH > –SO₃H > MAA-free control (–NH₂ at ortho position); (3) –COOH > MAA-free control > –OH (–NH₂ at meta position) through the CPT at 200 mg/L MAAs. Comparison on results in higher levels of MAAs at 1000 mg/L almost showed parallel relative toxicity rankings at 200 mg/L. Quantification using traditional plate count method also confirmed nearly similar trends for corresponding MAAs except 3-aminophenol, revealing the promising feasibility of CPT for the toxicity assessment in practical applications. In addition, dose-mortality analysis regularly used in toxicology was used to quantitatively determine toxicity rankings of MAAs. In conclusion, this study directly provided a kinetic model to quantify the relative toxicity ranking of MAAs in the presence of RR141. It could provide a feasible guideline for assessment on the toxicity or treatability of azo dyes and MAAs to A. hydrophila in wastewater treatment.