10,321 research outputs found

    The Amorphous-Crystal Interface in Silicon: a Tight-Binding Simulation

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    The structural features of the interface between the cystalline and amorphous phases of Si solid are studied in simulations based on a combination of empirical interatomic potentials and a nonorthogonal tight-binding model. The tight-binding Hamiltonian was created and tested for the types of structures and distortions anticipated to occur at this interface. The simulations indicate the presence of a number of interesting features near the interface. The features that may lead to crystallization upon heating include chains with some defects, most prominently dimers similar to those on the Si(001) 2x1 reconstructed free surface. Within the amorphous region order is lost over very short distances. By examining six different samples with two interfaces each, we find the energy of the amorphous-crystal interface to be 0.49 +/- 0.05 J/m^2Comment: Submitted to Phys. Rev.

    Averting Behavior Framework for Perceived Risk of Yersinia enterocolitica Infections

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    The focus of this research is to present a theoretical model of averting actions that households take to avoid exposure to Yersinia enterocolitica in contaminated food. The cost of illness approach only takes into account the value of a cure, while the averting behavior approach can estimate the value of preventing the illness. The household, rather than the individual, is the unit of analysis in this model, where one household member is primarily responsible for procuring uncontaminated food for their family. Since children are particularly susceptible and live with parents who are primary decision makers for sustenance, the designated household head makes the choices that are investigated in this paper. This model uses constrained optimization to characterize activities that may offer protection from exposure to Yersinia enterocolitica contaminated food. A representative household decision maker is assumed to allocate family resources to maximize utility of an altruistic parent, an assumption used in most research involving economics of the family

    Penghawaan Alami pada Unit dan Koridor Rusunami The Jarrdin

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    Vertical housing is one alternative solutions in solving the problem of settlements. Flats intended for middle class people down, then the operating costs of the building should cost without ignoring occupant comfort factor that is by optimizing natural air flow on the building. Vertical housing is used as a case study is Rusunami The Jarrdin on the part of the dwelling units and corridors. The purpose of this research is to know the level of thermal comfort by analyzing natural air flow system on the unit and the corridor rusunami The Jarrdin. The method used is quantitative method by measuring the air flow rate using the tool anemometer at 2 locations dwelling units and different corridors. Unit A2033 (+ 55 m) oriented towards the outside of the building while the unit A1129 (+ 35 m) oriented to face the other side of the building that contained the pool below. While the corridor section is done in two points in the section near the openings and the section between the two residential units. Every measurement at one point two times the area of ​​the study conducted measurements at different times. Results of the analysis showed that the natural penghawaan on rusunami The Jarrdin not very optimal. The natural air flow would be optimal if the requirements of an ideal system of cross ventilation openings adapted to the design of the building Rusunami The Jarrdin

    Kinematic Self-Similar Plane Symmetric Solutions

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    This paper is devoted to classify the most general plane symmetric spacetimes according to kinematic self-similar perfect fluid and dust solutions. We provide a classification of the kinematic self-similarity of the first, second, zeroth and infinite kinds with different equations of state, where the self-similar vector is not only tilted but also orthogonal and parallel to the fluid flow. This scheme of classification yields twenty four plane symmetric kinematic self-similar solutions. Some of these solutions turn out to be vacuum. These solutions can be matched with the already classified plane symmetric solutions under particular coordinate transformations. As a result, these reduce to sixteen independent plane symmetric kinematic self-similar solutions.Comment: 29 pages, accepted for publication in Classical Quantum Gravit

    Polyamine-Polyamine and Polyamine-Protein Transport Inhibitor Conjugates and Their Use as Pharmaceuticals and in Research Relating to Polyamine Transport

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    Novel classes of inhibitors which selectively inhibit the cellular transport of normally transported substances, specifically polyamines are taught which comprise (i) polymers of the transported substance or (ii) protein or polypeptide conjugates of the transported substance. These inhibitors may be used in vitro to assess the effect of the transported substance on cellular functions and in vivo for treating disease conditions involving transport of the particular substance, e.g., a polyamine

    Normal soaking extraction (NSE) of rotenone from Derris elliptica

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    Derris elliptica or the tuba plant contains rotenone, bio-active compound known that has the potential to be used as bio-pesticide. Bio-pesticide is the best-known alternative bio-pesticide which has the potential to replace the use of conventional pesticides, as it is more environmentally friendly. The main objective of the paper is to obtain the best extraction solvent for optimizing the yield in rotenone extraction. Rotenone was extracted from Derris root using three different parts of roots and three types of solvent in Normal Soaking Extraction (NSE). The types of Derris roots are: (1) Fine root (2) Coarse root (3) Stem. The three types of solvent system are: (1) Acetone 95 % (v/v), (2) Chloroform 99.9 % (v/v) and (3) a mixture of ethanol: H2O (9:1) added with oxalic acid (1mg/ml). The liquid crude extracts were further cleaned up to remove the fine debris of roots. The presence of rotenone was confirmed using qualitative analysis Thin Layer Chromatography (TLC) and thereupon the determination of rotenone content was carried out using High Performance Liquid Chromatography (HPLC). From the results obtained, it was found that the Normal Soaking Extraction (NSE) using acetone 95 % (v/v) was the best method to extract the highest yield of rotenone; 1.14 % (w/w)

    Single instillation of mitomycin C reduces 1st year recurrence following transurethral resection of non-muscle invasive bladder cancer

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    Objective: To study the impact of single instillation of 40 mg Mitomycin C (MMC-40) within first hour of transurethral resection (TUR), on first year recurrence of non-muscle invasive bladder cancer. Methods: In this study of two groups of patients with similar demographics and tumour profile were compared to assess first year tumour recurrence pattern. Group A received MMC-40 within 30 minutes of TUR. Group B patients only had TUR of bladder tumour. Patients\u27 charts were reviewed for demographic profile, preoperative diagnosis and imaging used, cytological work up, tumour profile both during cystoscopy and imaging used, patients records were also reviewed for all subsequent check cystoscopies for recurrence. Any adjuvant treatments like intravesical chemo/immunotherapy etc. were also noted. The results were analysed using a commercially available statistical package, SPSS. The level of significance was \u3c or = 0.05.Results: There were 29 and 46 patients in group A and B respectively. The demographic profile in terms of age, gender distribution, tumour characteristics (size, site, multiplicity) and pathological evaluation including, tumour grade and presence of carcinoma in situ were similar (p \u3c 0.4 and p \u3c 0.5) respectively. The first year recurrence rate in group A was 15% whereas it was 37.4% in group B (p \u3c 0.04).Conclusions: The first year recurrence rate is significantly decreased if MMC-40 is instilled following TUR. MMC-40 is safe and cost effective. Most low grade, low volume tumours would not require any further treatment if MMC-40 is given immediately following TUR

    High performance speed control of single-phase induction motors using switching forward and backward EKF strategy

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    The aim of this research is to provide a high performance vector control of single-phase Induction Motor (IM) drives. It is shown that in the rotating reference frame, the single-phase IM equations can be separated into forward and backward equations with the balanced structure. Based on this, a method for vector control of the single-phase IM, using two modified Rotor Field- Oriented Control (RFOC) algorithms is presented. In order to accommodate forward and backward rotor fluxes in the presented controller, an Extended Kalman Filter (EKF) with two different forward and backward currents that are switched interchangeably (switching forward and backward EKF), is proposed. Simulation results illustrate the effectiveness of the proposed algorithm

    A Novel Method for Rotor Field-Oriented Control of Single-Phase Induction Motor

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    This paper presents a novel rotor field-oriented control (RFOC) method for asymmetrical single-phase induction motor (SPIM). It is shown in this paper that by using a suitable transformation matrix (TM) for stator current variables, the asymmetrical equations of SPIM are transformed into symmetrical equations. Based on this similarity, a novel vector conrol technique for SPIM is presented. Performance of the proposed method is assessed using MATLAB/SIMULINK software. Simulation results showed the excellence speed and torque responses obtained using the proposed technique

    Optimization of corrosion inhibition of essential oils of Alpinia galanga on mild steel using Response Surface Methodology

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    The use of plant extracts as corrosion inhibitors has gained prominence as replacement for synthetic organic compounds. The plant natural products have been found to be effective, cheap and eco-friendly anticorrosion agents. Corrosion inhibitions of essential oils of Alpinia galanga were investigated on mild steel in hydrochloric acid solution using weight loss method. The interactive effects of inhibitor concentration, temperature and time were optimized for maximum response of inhibition efficiency using Response Surface Methodology with Central Composite Design. The optimum inhibition efficiency of 88.5% at 775 ppm of inhibitor concentration, temperature of 320.4 K and reaction time of 3.75 hours was accomplished. The effectiveness of the inhibitor was also supported using scanning electron microscopy. The mechanism of interaction of both the inhibitor on mild steel surface was found to conform to the Langmuir adsorption isotherm
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