scholarly journals Особенности спектров люминесценции ZnSе · О с привлечением теории антипересекающихся зон

2021 ◽  
Vol 55 (5) ◽  
pp. 403
Author(s):  
В.И. Олешко ◽  
С.С. Вильчинская ◽  
Н.К. Морозова
Keyword(s):  
Point Defects ◽  
Stacking Faults ◽  
Emission Spectra ◽  
Structural Features ◽  
Stimulated Emission ◽  
Stable States ◽  
Zone Structure ◽  
Structure Improvement ◽  
Band Anticrossing

Investigations are presented in the light of the band anticrossing theory (ВАС) of the influence on the emission spectra of the structural features self-activated zinc selenide and crystals with activators. The disunity of numerous literature data makes it difficult to understand this question. Theory-ВAС requires taking into account the influence of isoelectronic admixture of oxygen, which is invariably present in the ZnSе lattice, on the zone structure. Improvement of methods for calcu-lating the equilibrium of intrinsic point defects (STD) intendes use of these data in the analysis of the optical properties of АIIВVI, in particular zinc selenide.The aim of thе work was to re-veal the features and nature of individual luminescence bands that are widely used to obtain information on the quality of crystals.For this, the spectra of photo, cathode, pulsed lumines-cence, excitation, and stimulated emission of ZnSе are investigated in a single context with the use of these features. Stable states of crystals with stacking faults were revealed upon introduc-tion of activators or background copper impurity. The data are of interest for the diagnostics of crystals that are useful for creating lasers.

scholarly journals Излучательные свойства сильно легированных эпитаксиальных слоев нитрида индия

2019 ◽  
Vol 53 (10) ◽  
pp. 1395
Author(s):  
Б.А. Андреев ◽  
Д.Н. Лобанов ◽  
Л.В. Красильникова ◽  
П.А. Бушуйкин ◽  
А.Н. Яблонский ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Emission Spectra ◽  
Stimulated Emission ◽  
Buffer Layers ◽  
Free Electrons ◽  
Sapphire Substrates ◽  
Plasma Activation ◽  
Growth Change ◽  
Emission Threshold

AbstractThe results of studies of the spontaneous photoluminescence and stimulated emission spectra of epitaxial n -InN layers with a concentration of free electrons of ~10^19 cm^–3 are reported. The layers are grown by molecular-beam epitaxy with the plasma activation of nitrogen on sapphire substrates with AlN and GaN buffer layers. It is found that, as the InN layers are grown under conditions with enrichment with nitrogen at a growth temperature elevated to 470°C close to the beginning of the decomposition of InN, the crystal quality of the layers is improved and the stimulated-emission threshold is lowered. As the conditions of growth change to conditions with enrichment with the metal, two emission bands separated by an energy of 100 meV are observed in the spontaneous-photoluminescence spectra of InN. For such layers, a substantial increase in the stimulated-emission threshold and, in some cases, the lack of a transition to stimulated emission are observed. In the study, an interpretation of the observed emission bands is given and some inferences as to their nature are made.

Stimulated-emission spectra of high-indium-content InGaN/GaN multiple-quantum-well structures

2000 ◽  
Vol 77 (23) ◽  
pp. 3758-3760 ◽  
Author(s):  
Chii-Chang Chen ◽  
Hui-Wen Chuang ◽  
Gou-Chung Chi ◽  
Chang-Cheng Chuo ◽  
Jen-Inn Chyi
Keyword(s):  
Quantum Well ◽  
Multiple Quantum Well ◽  
Emission Spectra ◽  
Indium Content ◽  
Stimulated Emission ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
High Indium Content

scholarly journals Zoomqa: Residue-Level Single-Model QA Support Vector Machine Utilizing Sequential and 3D Structural Features

2021 ◽  
Author(s):  
Kyle Hippe ◽  
Cade Lilley ◽  
William Berkenpas ◽  
Kiyomi Kishaba ◽  
Renzhi Cao
Keyword(s):  
Protein Complex ◽  
Structure Prediction ◽  
Tertiary Structure ◽  
State Of The Art ◽  
Chemical Properties ◽  
Structural Features ◽  
Residue Level ◽  
Support Vector ◽  
Single Model

ABSTRACTMotivationThe Estimation of Model Accuracy problem is a cornerstone problem in the field of Bioinformatics. When predictions are made for proteins of which we do not know the native structure, we run into an issue to tell how good a tertiary structure prediction is, especially the protein binding regions, which are useful for drug discovery. Currently, most methods only evaluate the overall quality of a protein decoy, and few can work on residue level and protein complex. Here we introduce ZoomQA, a novel, single-model method for assessing the accuracy of a tertiary protein structure / complex prediction at residue level. ZoomQA differs from others by considering the change in chemical and physical features of a fragment structure (a portion of a protein within a radius r of the target amino acid) as the radius of contact increases. Fourteen physical and chemical properties of amino acids are used to build a comprehensive representation of every residue within a protein and grades their placement within the protein as a whole. Moreover, ZoomQA can evaluate the quality of protein complex, which is unique.ResultsWe benchmark ZoomQA on CASP14, it outperforms other state of the art local QA methods and rivals state of the art QA methods in global prediction metrics. Our experiment shows the efficacy of these new features, and shows our method is able to match the performance of other state-of-the-art methods without the use of homology searching against database or PSSM matrix.Availabilityhttp://[email protected]

scholarly journals Protein microcrystallography using synchrotron radiation

IUCrJ ◽  
2017 ◽  
Vol 4 (5) ◽  
pp. 529-539 ◽  
Author(s):  
Masaki Yamamoto ◽  
Kunio Hirata ◽  
Keitaro Yamashita ◽  
Kazuya Hasegawa ◽  
Go Ueno ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Data Collection ◽  
Diffraction Data ◽  
Structure Determination ◽  
Structural Features ◽  
X Ray ◽  
Data Collection Strategy ◽  
Technological Developments ◽  
Novel Method

The progress in X-ray microbeam applications using synchrotron radiation is beneficial to structure determination from macromolecular microcrystals such as smallin mesocrystals. However, the high intensity of microbeams causes severe radiation damage, which worsens both the statistical quality of diffraction data and their resolution, and in the worst cases results in the failure of structure determination. Even in the event of successful structure determination, site-specific damage can lead to the misinterpretation of structural features. In order to overcome this issue, technological developments in sample handling and delivery, data-collection strategy and data processing have been made. For a few crystals with dimensions of the order of 10 µm, an elegant two-step scanning strategy works well. For smaller samples, the development of a novel method to analyze multiple isomorphous microcrystals was motivated by the success of serial femtosecond crystallography with X-ray free-electron lasers. This method overcame the radiation-dose limit in diffraction data collection by using a sufficient number of crystals. Here, important technologies and the future prospects for microcrystallography are discussed.

scholarly journals Children's Television: The German Situation

1999 ◽  
Vol 93 (1) ◽  
pp. 77-89
Author(s):  
Ben Bachmair ◽  
Dirk Ulf Stötzel
Keyword(s):  
Structural Features ◽  
Children's Television ◽  
Federal Republic Of Germany ◽  
Public And Private ◽  
Media Regulation ◽  
Current State ◽  
The Social ◽  
Public Debates ◽  
Air Channels

This article provides an overview of the current state of and future prospects for children's television in the Federal Republic of Germany. It begins with a brief description of current television provision for children, and of children's viewing patterns, and it suggests that views of children's relations with the medium are heavily influenced by social class. The article goes on to describe the structural features of broadcasting and of media regulation in Germany, paying particular attention to the federal structure and the balance between public and private. The implications of this situation for children's programming are then analysed, with particular attention paid to the heavy regulation of advertising on free-to-air channels, and the need to protect children's slots in the context of a general move towards specialist channels. The article concludes by outlining the terms of recent public debates about the social purpose and quality of children's television.

scholarly journals The Retromolar Space and Wisdom Teeth in Humans: Reasons for Surgical Tooth Extraction

2020 ◽  
Author(s):  
Abed El Kaseh ◽  
Maher Al Shayeb ◽  
Syed Kuduruthullah ◽  
Nadeem Gulrez
Keyword(s):  
Homo Sapiens ◽  
Third Molar ◽  
Structural Features ◽  
Morphometric Study ◽  
Third Molars ◽  
Facial Skeleton ◽  
Lower Jaw ◽  
Wisdom Teeth ◽  
Retromolar Region

Abstract Objective This article explores the problem of developing pathologies in the retromolar region. Findings can serve a framework for disease prevention and for the improvement of the quality of life of patients. The present study aims to justify the possibility of utilizing morphometric methods to foresee problems in the eruption of third molars. Materials and Methods A comprehensive morphometric study of the lower jaw and facial skeleton involves 100 skulls of Homo sapiens to identify the anatomical causes of problems with wisdom teeth eruption. All said skulls are divided in two groups: I: skulls with intact dentition; II: skulls with impacted third molars. Results This work allows detecting abnormalities in the eruption of the third molar with high probability of success. The abnormalities in point are considered not only those associated with the generally accepted parameters but also those that occur in the leptoprosopic face cases. Conclusions Face type and the structural features of the facial skeleton play a significant role in the abnormal eruption of the lower third molar.

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