Dissociation mechanism for solid-phase epitaxy of silicon in the Si <100>/Pd2Si/Si (amorphous) system

Solid-phase epitaxial growth (SPEG) of silicon was investigated by a tracer technique using radioactive 31Si formed by neutron activation in a nuclear reactor. After depositing Pd and Si onto activated single-crystal silicon substrates, Pd2Si was formed with about equal amounts of radioactive and nonradioactive Si during heating at 400 °C for 5 min. After an 1-sec annealing stage (450-->500 °C in 1 h) this silicide layer, which moves to the top of the sample during SPEG, is etched off with aqua regia. From the absence of radioactive 31Si in the etch, it is concluded that SPEG takes place by a dissociation mechanism rather than by diffusion

Mapping the Dirac point in gated bilayer graphene

We have performed low temperature scanning tunneling spectroscopy measurements on exfoliated bilayer graphene on SiO2. By varying the back gate voltage we observed a linear shift of the Dirac point and an opening of a band gap due to the perpendicular electric field. In addition to observing a shift in the Dirac point, we also measured its spatial dependence using spatially resolved scanning tunneling spectroscopy. The spatial variation of the Dirac point was not correlated with topographic features and therefore we attribute its shift to random charged impurities.Comment: 3 pages, 3 figure

Heterostructure by solid‐phase epitaxy in the Si〈111〉/Pd/Si (amorphous) system

When a thin film of Pd reacts with a 〈111〉 Si substrate, a layer of epitaxial Pd_2Si is formed. It is shown that Si can grow epitaxially on such a layer by solid‐phase reaction

Active involvement of students in co-curriculum (sports) versus generic skills

The active involvement of students in sports activities is viewed from different levels of achievement beginning with the national representation of the residential colleges, faculties, and universities in prestigious sporting events at international levels. The skills that are developed through extra-curricular activities are generic skills. The involvement of students in co-curricular activities can help to shape their generic skills, thus leading to self-promotion in the workplace. Therefore, the purpose of this research was to examine the enhancement of generic skills among engineering and technical students of UTHM who are actively involved in co-curricular activities (sports). This study will focus on identifying the factors of involvement, the level of application among students, and the perceptions of the students through their active involvement in extra-curricular activities (sports). A survey was conducted using a quantitative approach. A general questionnaire, which was designed to fulfil the objectives and to answer the research questions for this study, was distributed to 213 engineering and technical student athletes of UTHM who are actively involved in co-curricular activities (sports). It was found that the engineering and technical student athletes of UTHM agreed that their active involvement in extra-curricular activities (sports) was due to interpersonal, intrapersonal and structural factors. The results showed that out of seven generic skills, three constructs of generic skills, namely communication, teamwork and management, demonstrate a high level of application through active involvement in extra-curricular activities (sports). These findings may also help the university to focus on the development of generic skills in engineering and technical students through co-curricular activities (sports) in addition to producing athletes who are able to create a name for the university at national or international level

Ultralow threshold graded-index separate-confinement heterostructure single quantum well (Al,Ga)As lasers

Broad area graded‐index separate‐confinement heterostructure single quantum well lasers grown by molecular‐beam epitaxy (MBE) with threshold current density as low as 93 A/cm^2 (520 μm long) have been fabricated. Buried lasers formed from similarly structured MBE material with liquid phase epitaxy regrowth had threshold currents at submilliampere levels when high reflectivity coatings were applied to the end facets. A cw threshold current of 0.55 mA was obtained for a laser with facet reflectivities of ∼80%, a cavity length of 120 μm, and an active region stripe width of 1 μm. These devices driven directly with logic level signals have switch‐on delays <50 ps without any current prebias. Such lasers permit fully on–off switching while at the same time obviating the need for bias monitoring and feedback control

Antimony doping of Si layers grown by solid-phase epitaxy

We report here that layers of Si formed by solid-phase epitaxial growth (SPEG) can be doped intentionally. The sample consists initially of an upper layer of amorphous Si (~1 µm thick), a very thin intermediate layer of Sb (nominally 5 Å), and a thin lower layer of Pd (~500 Å), all electron-gun deposited on top of a single-crystal substrate (1–10 Ω cm, p type, orientation). After a heating cycle which induces epitaxial growth, electrically active Sb atoms are incorporated into the SPEG layer, as shown by the following facts: (a) the SPEG layer forms a p-n junction against the p-type substrate, (b) the Hall effect indicates strong n-type conduction of the layer, and (c) Auger electron spectra reveal the presence of Sb in the layer

Predictive value of high-sensitivity troponin-I for future adverse cardiovascular outcome in stable patients with type 2 diabetes mellitus

INTRODUCTION: High-sensitivity cardiac troponin I(hs-TnI) and T levels(hs-TnT) are sensitive biomarkers of cardiomyocyte turnover or necrosis. Prior studies of the predictive role of hs-TnT in type 2 diabetes mellitus(T2DM) patients have yielded conflicting results. This study aimed to determine whether hs-TnI, which is detectable in a higher proportion of normal subjects than hsTnT, is associated with a major adverse cardiovascular event(MACE) in T2DM patients. METHODS AND RESULTS: We compared hs-TnI level in stored serum samples from 276 consecutive patients (mean age 65 +/- 10 years; 57% male) with T2DM with that of 115 age-and sex-matched controls. All T2DM patients were prospectively followed up for at least 4 years for incidence of MACE including heart failure(HF), myocardial infarction(MI) and cardiovascular mortality. At baseline, 274(99%) patients with T2DM had detectable hs-TnI, and 57(21%) had elevated hs-TnI (male: 8.5 ng/L, female: 7.6 ng/L, above the 99th percentile in healthy controls). A total of 43 MACE occurred: HF(n = 18), MI(n = 11) and cardiovascular mortality(n = 14). Kaplan-Meier analysis showed that an elevated hs-TnI was associated with MACE, HF, MI and cardiovascular mortality. Although multivariate analysis revealed that an elevated hs-TnI independently predicted MACE, it had limited sensitivity(62.7%) and positive predictive value(38.5%). Contrary to this, a normal hs-TnI level had an excellent negative predictive value(92.2%) for future MACE in patients with T2DM. CONCLUSION: The present study demonstrates that elevated hs-TnI in patients with T2DM is associated with increased MACE, HF, MI and cardiovascular mortality. Importantly, a normal hs-TnI level has an excellent negative predictive value for future adverse cardiovascular events during long-term follow-up.published_or_final_versio

Growth mechanism for solid-phase epitaxy of Si in the Si <100>/Pd2Si/Si(amorphous) system studied by a radioactive tracer technique

A tracer technique using radioactive 31Si (T1/2=2.62 h) was used to study solid-phase epitaxial growth (SPEG) of silicon. After depositing Pd and Si onto single-crystal substrates which had been activated in a nuclear reactor, Pd2Si was formed with about equal amounts of radioactive and nonradioactive silicon during heating at 400 °C for 5 min. After a second annealing stage (450 °C-->500 °C in 1 h) the silicide layer which moves to the top of the sample during SPEG was etched off with aqua regia. From the absence of radioactive 31Si in the etchant solution it is concluded that SPEG takes place by dissociation of the Pd2Si layer at the single-crystal interface to provide free Si for epitaxial growth, while new silicide is formed at the interface with the amorphous Si. These results were confirmed by evaporating radioactive silicon onto nonactivated silicon substrates before evaporation of Pd and stable amorphous Si and by measuring the activity in the SPEG sample before and after etching off the silicide layer

Learning hybrid locomotion skills—Learn to exploit residual actions and modulate model-based gait control

This work has developed a hybrid framework that combines machine learning and control approaches for legged robots to achieve new capabilities of balancing against external perturbations. The framework embeds a kernel which is a model-based, full parametric closed-loop and analytical controller as the gait pattern generator. On top of that, a neural network with symmetric partial data augmentation learns to automatically adjust the parameters for the gait kernel, and also generate compensatory actions for all joints, thus significantly augmenting the stability under unexpected perturbations. Seven Neural Network policies with different configurations were optimized to validate the effectiveness and the combined use of the modulation of the kernel parameters and the compensation for the arms and legs using residual actions. The results validated that modulating kernel parameters alongside the residual actions have improved the stability significantly. Furthermore, The performance of the proposed framework was evaluated across a set of challenging simulated scenarios, and demonstrated considerable improvements compared to the baseline in recovering from large external forces (up to 118%). Besides, regarding measurement noise and model inaccuracies, the robustness of the proposed framework has been assessed through simulations, which demonstrated the robustness in the presence of these uncertainties. Furthermore, the trained policies were validated across a set of unseen scenarios and showed the generalization to dynamic walking