The vapour-liquid-solid (VLS) method is by far the most extended procedure for bottom-up nanowire growth. This method also allows for the manufacture of nanowire axial heterojunctions in a straightforward way. To do t...
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The vapour-liquid-solid (VLS) method is by far the most extended procedure for bottom-up nanowire growth. This method also allows for the manufacture of nanowire axial heterojunctions in a straightforward way. To do this, during the growth process, precursor gases are switched on/off to obtain the desired change in the nanowire composition. Using this technique, axially heterostructured nanowires can be grown, which are crucial for the fabrication of electronic and optoelectronic devices. SiGe/Si nanowires are compatible with complementary metal oxide semiconductor (CMOS) technology, which improves their versatility and the possibility of integration with current electronic technologies. Abrupt heterointerfaces are fundamental for the development and correct operation of electronic and optoelectronic devices. Unfortunately, the VLS growth of SiGe/Si heterojunctions does not provide abrupt transitions because of the high solubility of group IV semiconductors in Au, with the corresponding reservoir effect that precludes the growth of sharp interfaces. In this work, we studied the growth dynamics of SiGe/Si heterojunctions based on already developed models for VLS growth. A composition map of the Si-Ge-Au liquid alloy is proposed to better understand the impact of the growing conditions on the nanowire growth process and the heterojunction formation. The solution of our model provides heterojunction profiles that are in good agreement with the experimental measurements. Finally, an in-depth study of the composition map provides a practical approach to the drastic reduction of heterojunction abruptness by reducing the Si and Ge concentrations in the catalyst droplet. This converges with previous approaches, which use catalysts aiming to reduce the solubility of the atomic species. This analysis opens new paths to the reduction of heterojunction abruptness using Au catalysts, but the model can be naturally extended to other catalysts and semiconductors.
Most modern analysts of Newton's laws of motion, whether they have approached the subject from a historical or from a philosophical viewpoint, have tended to concentrate on the status of the first two laws; the th...
Most modern analysts of Newton's laws of motion, whether they have approached the subject from a historical or from a philosophical viewpoint, have tended to concentrate on the status of the first two laws; the third law has largely been overlooked, or else it has been dismissed as somehow less interesting. My purpose in this paper is to reverse this approach—I intend to investigate some of the historical aspects of the third law, particularly the empirical background to Newton's statement of it, and in so doing, I intend to skirt most of the questions which have been raised concerning the status of the other two laws. In concentrating on the historical aspects of the third law, I shall also by-pass Mach's controversial re-interpretation of its role in mechanics, for while Mach saw the law as the basis for an operational definition of “mass”, it is quite clear that Newton did not so regard it. On the contrary, Newton seems to have regarded all three of his laws as straightforward statements of fact about the world, so that a knowledge of the factual background to the laws is a fundamental pre-requisite to an understanding of Newton's thought.
A novel platform of simple and cost-effective carbon paste electrode (CPE)-modified with a binuclear copper (II)8-hydroxyquinoline complex was used for catalytic electroxidation of L-Cysteine. The modified electrode d...
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A novel platform of simple and cost-effective carbon paste electrode (CPE)-modified with a binuclear copper (II)8-hydroxyquinoline complex was used for catalytic electroxidation of L-Cysteine. The modified electrode described was observed to significantly reduce the electrooxidation potential of L-Cysteine. Electrochemical impedance spectroscopy confirmed a significant decrease in the charge transfer resistance at the electrode surface by introducing the binuclear copper complex in the CPE. It was proposed that the two molecules of cysteine, adsorbed to the modified electrode surface, are oxidized to a cystine molecule via copper (II) centers of the complex which are consequently reduced to copper (I) species, responsible for the voltammetric peak observed when the potential was scanned toward the positive direction. To improve the electrode signal for cysteine, the electrode composition was also optimized. Two electrochemical techniques of cyclic voltammetry and amperometry were applied for the establishment of the calibration curve for cysteine determination by this electrode. The linear ranges of the calibration curves are obtained utilizing two electrochemical techniques of cyclic voltammetry and amperometry were 286-5000 mu M and 11.6-500 mu M, respectively. Also, the detection limits of cysteine assay by the above-cited techniques were calculated and equal to 86.7 mu M and 3.5 mu M, respectively. The electrode described was applied for cysteine determination in some vegetable samples which showed satisfactory results. Also, the selectivity of the sensor was checked against some biomolecules and amino acids such as Glycine, Alanine, Arginine, Methionine, Glucose, Urea, BrO3 - and Citric acid. The introduced sensor exhibited excellent selectivity for cysteine determination in food samples.
We demonstrate the role of various potentials in nuclear flow for Fe-26(58) + Fe-26(58) and Ni-28(58) + Ni-28(58) systems using the isospin-dependent quantum molecular dynamics (IQMD) model. Our simulations include al...
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We demonstrate the role of various potentials in nuclear flow for Fe-26(58) + Fe-26(58) and Ni-28(58) + Ni-28(58) systems using the isospin-dependent quantum molecular dynamics (IQMD) model. Our simulations include all the components of the interaction potential to predict the value of the balance energy and is in agreement with the available experimental data.
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