Some harvesting system transforming energy wastes of compressed air to electricity

Energy harvesting devices are self-powered systems which are associated with input ambient energy and convert such energy to electrical one. In this study, we focus on input ambient energy deriving from compressed air. Using arbitrary pneumatic machine, the compressed air after work - with its typical parameters as overpressure 6 bar or higher and variable volume flow - is exhausted to atmosphere. This generates energy losses. We have constructed some device which transforms the loss of compressed air energy to electricity. It illustrates the principle of action very well and does not perturb operation of pneumatic machines being source of energy losses

Animal versus human research reporting guidelines impacts: literature analysis reveals citation count bias

The present study evaluated for the first time citation-impacts of human research reporting guidelines in comparison to their animal version counterparts. Re-examined and extended also were previous findings indicating that a research reporting guideline would be cited more for its versions published in journals with higher Impact Factors, compared to its duplicate versions published in journals with lower Impact Factors. The two top-ranked reporting guidelines listed in the Equator Network website (http://www.equator-network.org/) were CONSORT 2010, for parallel-group randomized trials; and STROBE, for observational studies. These two guidelines had animal study versions, REFLECT and STROBE-Vet, respectively. Together with ARRIVE, these five guidelines were subsequently searched in the Web of Science Core Collection online database to record their journal metrics and citation data. Results found that association between citation rates and journal Impact Factors existed for CONSORT guideline set for human studies, but not for STROBE or their counterparts set for animal studies. If Impact Factor was expressed in terms of journal rank percentile, no association was found except for CONSORT. Guidelines for human studies were much more cited than animal research guidelines, with the CONSORT 2010 and STROBE guidelines being cited 27.1 and 241.0 times more frequently than their animal version counterparts, respectively. In conclusion, while the journal Impact Factor is of importance, other important publishing features also strongly affect scientific manuscript visibility, represented by citation rate. More effort should be invested to improve the visibility of animal research guidelines.info:eu-repo/semantics/publishedVersio

Modeling of the Point Defect Migration across the AlN/GaN Interfaces—Ab Initio Study

The formation and diffusion of point defects have a detrimental impact on the functionality of devices in which a high quality AlN/GaN heterointerface is required. The present paper demonstrated the heights of the migration energy barriers of native point defects throughout the AlN/GaN heterointerface, as well as the corresponding profiles of energy bands calculated by means of density functional theory. Both neutral and charged nitrogen, gallium, and aluminium vacancies were studied, as well as their complexes with a substitutional III-group element. Three diffusion mechanisms, that is, the vacancy mediated, direct interstitial, and indirect ones, in bulk AlN and GaN crystals, as well at the AlN/GaN heterointerface, were taken into account. We showed that metal vacancies migrated across the AlN/GaN interface, overcoming a lower potential barrier than that of the nitrogen vacancy. Additionally, we demonstrated the effect of the inversion of the electric field in the presence of charged point defects VGa3− and VAl3− at the AlN/GaN heterointerface, not reported so far. Our findings contributed to the issues of structure design, quality control, and improvement of the interfacial abruptness of the AlN/GaN heterostructures

Visualization of the Differential Transition State Stabilization within the Active Site Environment

Abstract: Increasing interest in the enzymatic reaction mechanisms and in the nature of catalytic effects in enzymes causes the need of appropriate visualization methods. A new interactive method to investigate catalytic effects using differential transition state stabilization approach (DTSS) [1, 2] is presented. The catalytic properties of the active site of cytidine deaminase (E.C. 3.5.4.5) is visualized in the form of differential electrostatic properties. The visualization was implemented using scripting interface of VMD [3]. Cumulative Atomic Multipole Moments (CAMM) [4,5,6] were utilized for efficient yet accurate evaluation of the electrostatic properties. The implementation is efficient enough for interactive presentation of catalytic effects in the active site of the enzyme due to transition state or substrate movement. This system of visualization of DTTS approach can be potentially used to validate hypotheses regarding the catalytic mechanism or to study binding properties of transition state analogues

Mechanism of Hydrogen Sensing by AlGaN/GaN Pt-Gate Field Effect Transistors: Magnetoresistance Studies

Physical mechanism responsible for hydrogen sensing by AlGaN/GaN transistors was investigated. Original resistance studies versus magnetic fields (up to 8T) were used to determine precisely hydrogen induced change of carrier mobility and density. Results clearly show that the carrier mobility change is responsible for less than five percent and that the hydrogen sensitivity is mainly related (more than 95 percent) to the carrier density change. These results support the physical model that relates hydrogen sensing with a change of surface charges resulting in modification of the GaN depletion layer

Polarization doping— Ab initio verification of the concept: Charge conservation and nonlocality

International audienceIn this work, we study the emergence of polarization doping in Al x Ga 1−x N layers with graded composition from a theoretical viewpoint. It is shown that bulk electric charge density emerges in the graded concentration region. The magnitude of the effect, i.e., the relation between the polarization bulk charge density and the concentration gradient is obtained. The appearance of mobile charge in the wurtzite structure grown along the polar direction was investigated using the combination of ab initio and drift-diffusion models. It was shown that the ab initio results can be recovered precisely by proper parameterization of drift-diffusion representation of the complex nitride system. It was shown that the mobile charge appears due to the increase of the distance between opposite polarization-induced charges. It was demonstrated that, for sufficiently large space distance between polarization charges, the opposite mobile charges are induced. We demonstrate that the charge conservation law applies for fixed and mobile charge separately, leading to nonlocal compensation phenomena involving (i) the bulk fixed and polarization sheet charge at the heterointerfaces and (ii) the mobile band and the defect charge. Therefore, two charge conservation laws are obeyed that induces nonlocality in the system. The magnitude of the effect allows obtaining technically viable mobile charge density for optoelectronic devices without impurity doping (donors or acceptors). Therefore, it provides an additional tool for the device designer, with the potential to attain high conductivities: high carrier concentrations can be obtained even in materials with high dopant ionization energies, and the mobility is not limited by scattering at ionized impurities

Polarization Doping in a GaN-InN System—Ab Initio Simulation

Polarization doping in a GaN-InN system with a graded composition layer was studied using ab initio simulations. The electric charge volume density in the graded concentration part was determined by spatial potential dependence. The emerging graded polarization charge was determined to show that it could be obtained from a polarization difference and the concentration slope. It was shown that the GaN-InN polarization difference is changed by piezoelectric effects. The polarization difference is in agreement with the earlier obtained data despite the relatively narrow bandgap for the simulated system. The hole generation may be applied in the design of blue and green laser and light-emitting diodes

Polarization Doping in a GaN-InN System—Ab Initio Simulation

Polarization doping in a GaN-InN system with a graded composition layer was studied using ab initio simulations. The electric charge volume density in the graded concentration part was determined by spatial potential dependence. The emerging graded polarization charge was determined to show that it could be obtained from a polarization difference and the concentration slope. It was shown that the GaN-InN polarization difference is changed by piezoelectric effects. The polarization difference is in agreement with the earlier obtained data despite the relatively narrow bandgap for the simulated system. The hole generation may be applied in the design of blue and green laser and light-emitting diodes

Polarization doping— Ab initio verification of the concept: Charge conservation and nonlocality

International audienceIn this work, we study the emergence of polarization doping in Al x Ga 1−x N layers with graded composition from a theoretical viewpoint. It is shown that bulk electric charge density emerges in the graded concentration region. The magnitude of the effect, i.e., the relation between the polarization bulk charge density and the concentration gradient is obtained. The appearance of mobile charge in the wurtzite structure grown along the polar direction was investigated using the combination of ab initio and drift-diffusion models. It was shown that the ab initio results can be recovered precisely by proper parameterization of drift-diffusion representation of the complex nitride system. It was shown that the mobile charge appears due to the increase of the distance between opposite polarization-induced charges. It was demonstrated that, for sufficiently large space distance between polarization charges, the opposite mobile charges are induced. We demonstrate that the charge conservation law applies for fixed and mobile charge separately, leading to nonlocal compensation phenomena involving (i) the bulk fixed and polarization sheet charge at the heterointerfaces and (ii) the mobile band and the defect charge. Therefore, two charge conservation laws are obeyed that induces nonlocality in the system. The magnitude of the effect allows obtaining technically viable mobile charge density for optoelectronic devices without impurity doping (donors or acceptors). Therefore, it provides an additional tool for the device designer, with the potential to attain high conductivities: high carrier concentrations can be obtained even in materials with high dopant ionization energies, and the mobility is not limited by scattering at ionized impurities