bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of live oud music on physiological and psychological parameters in patients undergoing cardiac surgery
Authors: Luis Merna , Doss Ramy , Zayed Basel , Yacoub Magdi
Published: October 2019

Background. Music therapy has emerged as a promising evidence-based adjuvant method of intervention. This study aims to assess the effect of live oud music on physiological and psychological parameters in patients undergoing cardiac surgery, pre- and post-operatively.Methods. Twelve patients undergoing cardiac operations were randomly allocated into either intervention group or control group, six patients in each group. Patients in the intervention group listened to 20 minutes of improvised and personally customized live oud music before and after surgery while patients in the control group heard the normal hospital sounds. While anxiety scores were assessed preoperatively, vital signs and pain scores were assessed postoperatively together with serum levels of cortisol, which was used as a surrogate marker of the stress response.Results. In the intervention group, pain scores and respiratory rates showed statistically significant reduction after listening to music (P values of 0.043 and 0.034 respectively). Additionally, heart rates, anxiety scores and serum cortisol levels showed borderline significant reduction in patients who listened to music with P values, 0.063, 0.066 and 0.068 respectively. These changes were not found in the control group.Conclusions. This preliminary study suggests a role of live oud music therapy in decreasing stress response of the patients undergoing cardiac surgery, in addition to its positive effects on pain perception and anxiety scores.
Characterization of size, shape and pattern of flow in the neo-aorta and pulmonary artery in a patient following an innovative technique of repair for truncus arteriosus
Authors: El Sawy Amr , Nagy Mohamed , Afifi Ahmed , Hosny Hatem , Romeih Soha , Aguib Heba , Yacoub Magdi
Published: October 2019

Background. Truncus arteriosus (TA) caries a very poor prognosis. In the absence of early correction, only 12 percent of patients born with this anomaly survive beyond one year. There is no agreement about the best method of surgical correction of this anomaly. We have devised an innovative valveless technique using autologous arterial tissue to repair TA.Objectives. Characterizing the size, shape and pattern of flow in the neo-aorta and pulmonary artery, in a patient following the new technique.Patient and Methods. Cardiac MRI and multislice CT imaging, followed by offline computerized image analysis was used in a patient aged 3 months, within 3 weeks of operating.Results. The size, shape and topology of the neo-aorta and pulmonary artery, approximated that present in normal hearts. The pattern of flow in the reconstructed vessels was laminar, throughout the cardiac cycle with minor acceleration during systole. The pulmonary regurgitation resulting from the absence of a valve occurred during late diastole, and was well tolerated. The size of the right ventricle diminished considerably following operation, and the right ventricular ejection fraction was supernormal.Conclusion. This early study in one patient provides new unique data of the size, shape, topology and pattern of flow in the neo-aorta and pulmonary artery, which appear to approximate normality. The long-term results of this promising operation need to be studied.
Küreselleşme ve Medya-Ekonomi Politiği Bağlamında Reklamveren Unsurunun Rolü: Türkiye’de Yayınlanan Reklamlarda Kültürün Aktarılması Üzerine Bir İnceleme
Authors: Yılmaz Berkant , Yaman Akyar Burcu
Published: October 2019

Küreselleşme ve medya-ekonomi politiği bağlamında
reklamveren unsurunun rolünün incelendiği bu çalışmada, küresel ve yerel
markaların reklamlarında kültürün nasıl aktarıldığı üzerine odaklanılmıştır. Bu
çalışmanın temel amacı medya ekonomi
politiği çerçevesinde, medyanın ticari olarak yürürlüğünde rol oynayan
reklamların (2018 yılında Türk televizyonlarında en uzun süre reklamveren
markalar ve reklamları), reklamverenler boyutuna odaklanarak; medyada satın
alınan süre bakımından küresel ve yerel markalar ayrımında nasıl değişkenlik
gösterdiğini ortaya koymaktır. Aynı zamanda küresel ve yerel markaların
yayınladıkları reklamlarda kültürün nasıl yansıtıldığını tespit etmek
çalışmanın diğer önemli bir amacını oluşturmaktadır.

Bu doğrultuda  içerik
analizi yöntemiyle Medya Takip Merkezinin 2018 yılında yayınladığı
raporların aylık olarak analizi gerçekleştirilerek, hangi markaların en uzun
süre medyada yer aldıkları tespit edilmiş ve bu marklar arasından ilk dört
sırada yer alan markanın (2 küresel, 2 yerel) reklamları, Hofstede’in kültürel
farklılıkları yansıtan dört öğesi (semboller, kahramanlar, ritüeller,
değerler), göstergebilimsel analiz
yöntemi kullanılarak incelenmiştir.

Elde edilen sonuçlar
ışığında, 2018 yılında en uzun süre medyada yer alan ilk dört markanın; Türk
Telekom, Algida, Turkcell ve Vodafone olduğu tespit edilmiştir. Bu markaların
reklamları analiz edildiğinde ise en çok vurgulanan kültürel göstergelerin;
birliktelik, paylaşım, milliyetçilik, samimiyet, kolektiflik ve aile kavramları
olarak tespit edilmiştir.
The Chemistry of Drugs to Treat Candida albicans
Authors: Ortiz Aurelio , Sansinenea Estibaliz
Published: October 2019

Background::

Candida species are in various parts of the human body as commensals. However,
they can cause local mucosal infections and, sometimes, systemic infections in which Candida
species can spread to all major organs and colonize them.

Objective::

For the effective treatment of the mucosal infections and systemic life-threatening fungal
diseases, a considerably large number of antifungal drugs have been developed and used for clinical
purposes that comprise agents from four main drug classes: the polyenes, azoles, echinocandins, and
antimetabolites.

Method: :

The synthesis of some of these drugs is available, allowing synthetic modification of the
molecules to improve the biological activity against Candida species. The synthetic methodology for
each compound is reviewed.

Results: :

The use of these compounds has caused a high-level resistance against these drugs, and therefore,
new antifungal substances have been described in the last years. The organic synthesis of the
known and new compounds is reported.

Conclusion: :

This article summarizes the chemistry of the existing agents, both the old drugs and new
drugs, in the treatment of infections due to C. albicans, including the synthesis of the existing drugs.
The Contribution of Formyl Peptide Receptor Dysfunction to the Course of Neuroinflammation: A Potential Role in the Brain Pathology
Authors: Trojan Ewa , Bryniarska Natalia , Leśkiewicz Monika , Regulska Magdalena , Chamera Katarzyna , Szuster-Głuszczak Magdalena , Leopoldo Marcello , Lacivita Enza , Basta-Kaim Agnieszka
Published: October 2019

:

Chronic inflammatory processes within the central nervous system (CNS) are in part responsible for the development of neurodegenerative and psychiatric diseases. These processes are associated with, among other things, the increased and disturbed activation of microglia and the elevated production of proinflammatory factors. Recent studies indicated that the disruption of the process of resolution of inflammation (RoI) may be the cause of CNS disorders. It is shown that the RoI is regulated by endogenous molecules called specialized pro-resolving mediators (SPMs), which interact with specific membrane receptors. Some SPMs activate formyl peptide receptors (FPRs), which belong to the family of seven-transmembrane G protein-coupled receptors. These receptors take part not only in the proinflammatory response but also in the resolution of the inflammation process. Therefore, the activation of FPRs might have complex consequences.

:

This review discusses the potential role of FPRs, and in particular the role of FPR2 subtype, in the brain under physiological and pathological conditions and their involvement in processes underlying neurodegenerative and psychiatric disorders as well as ischemia, the pathogenesis of which involves the dysfunction of inflammatory processes.
Study of HIV Resistance Mutations Against Antiretrovirals using Bioinformatics Tools
Authors: Peixoto Roca Tárcio , Nogueira Lima Felipe Souza , de Oliveira Santos Alcione , Souza Vieira Deusilene , Felipo Botelho-Souza Luan
Published: October 2019

Background:

Antiretroviral drugs to HIV-1 (ARV) are divided into classes: Nucleotide Reverse Transcriptase Inhibitors (NRTIs); Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs); Protease Inhibitors (PIs); Integrase Inhibitors (INIs); fusion inhibitors and entry Inhibitors. The occurrence of mutations developing resistance to antiretroviral drugs used in HIV treatment take place in a considerable proportion and has accumulated over its long period of therapy.

Objective:

This study aimed to identify resistance mutations to antiretrovirals used in the treatment of HIV-1 in strains isolated from Brazilian territory deposited at Genbank, as well as to relate to the clinical significance and mechanism of action.

Methods:

Elucidation of these mutations was by comparative method of peptide sequence resulting from genes encoding therapeutic targets in HIV antiretroviral therapy (ART) of the strains with a reference sequence through bioinformatic genetic information manipulation techniques.

Results:

Of the 399 sequences analyzed, 121 (30.3%) had some type of mutations associated with resistance to some class of antiretroviral drug. Resistance to NNRTIs was the most prevalent, detected in 77 (63.6%) of the 121 mutated sequences, compared to NRTIs and PIs, whose resistance was detected in 60 (49.6%) and 21 (17.3%), respectively, and to INIs, only 1 (0.8%) sample showed associated resistance mutation.

Conclusion:

Resistance to HIV ARV was detected at a considerable rate of 30.3%, showing some concerns about the percentage of viral strains that escape the established therapeutic regimen and that circulate currently in Brazil. The non-use of NNRTIs in Brazil is justified by the emergence of resistance mutations. The low prevalence of mutations against INIs is because drugs in this class have a high genetic barrier.
Cyclization Effect on pKa of the Side Chain of Aspartic Acid in Dipeptides: A DFT Study
Authors: Sargolzaei Mohsen , Jorabchi Majid Namayandeh
Published: October 2019

Cyclic dipeptides are very important compounds that have a wide range of applications in pharmaceutical chemistry and life sciences. In the current work, the acidity of the side chain of aspartic acid was calculated for various linear and a cyclic dipeptide. pKa values were derived using the thermodynamics cycle and DFT/B3LYP approach. The obtained pKa values show strong acidity for cyclic with respect to linear dipeptides. We found an intramolecular hydrogen bond in cyclic dipeptide structure, which can be used to justify the increasing acidity of the side chain of Asp as compared to linear structures.
Envirocat EPZ-10: An Efficient Catalyst for the Synthesis of 1,2,4- Triazolidine-3-thiones
Authors: Mhaldar Pradeep M. , Pore Dattaprasad M.
Published: October 2019

A simple and environmentally benign room temperature synthesis of 1,2,4-triazolidine-3-
thiones is described using Envirocat EPZ-10R as a solid acid catalyst in the aqueous medium. The use
of Envirocat EPZ-10R as a green catalyst, reusability of the catalyst, water as a universal solvent and
good yields of the product are the attractive features of the present method.
Brain Volumes of very Low Birth Weight Infants Measured by Two-dimensional Cranial Ultrasonography: A Prospective Cohort Study
Authors: Şimşek Gülsüm Kadıoğlu , Canpolat Fuat Emre , Büyüktiryaki Mehmet , Kutman Gözde Kanmaz , Tayman Cüneyt
Published: October 2019

Background:

Cranial ultrasonography is the main neuroimaging technique for very low
birth weight infants. Low brain volume is associated with poor neurologic outcome. This study
aimed to calculate brain volumes of preterm infants with two-dimensional measurements of cranial
ultrasonography.

Methods:

Intracranial height, anteroposterior diameter, bi-parietal diamater, ventricular height,
thalamo-occipital distance and ventricular index were measured with routine cranial ultrasonographic
scanning. Brain considered a spheric, ellipsoid model and estimated brain volume (EBV)
was calculated by subtracting two lateral ventricular volumes from the total brain volume.

Results:

One hundred and twenty-one preterm infants under a birth weight of 1500 g and 32
weeks of gestational age were included in this study. The mean gestational age of study population
was 27.7 weeks, and mean birthweight was 1057 grams.

:

Twenty-two of 121 infants had dilated ventricle, in this group, EBV was lower than normal group
(202 ± 58 cm3 vs 250 ± 53 cm3, respectively, p<0.01). Advanced resuscitation, bronchopulmonary
dysplasia and late-onset sepsis were found to be independent risk factors for low brain volume in
our data.

Conclusion:

Estimated brain volume can be calculated by two-dimensional measurements with
cranial ultrasonography.
Targeting Peptidyl-prolyl Cis-trans Isomerase NIMA-interacting 1: A Structure-based Virtual Screening Approach to Find Novel Inhibitors
Authors: da Costa Kauê Santana , Galúcio João M. , de Jesus Deivid Almeida , Gomes Guelber Cardoso , Lima e Lima Anderson Henrique , Taube Paulo S. , dos Santos Alberto M. , Lameira Jerônimo
Published: October 2019

Background:

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) is an enzyme that isomerizes phosphorylated serine or threonine motifs adjacent to proline residues. Pin1 has important roles in several cellular signaling pathways, consequently impacting the development of multiple types of cancers.

Methods:

Based on the previously reported inhibitory activity of pentacyclic triterpenoids isolated from the gum resin of Boswellia genus against Pin1, we designed a computational experiment using molecular docking, pharmacophore filtering, and structural clustering allied to molecular dynamics (MD) simulations and binding free energy calculations to explore the inhibitory activity of new triterpenoids against Pin1 structure.

Results:

Here, we report different computational evidence that triterpenoids from neem (Azadirachta indica A. Juss), such as 6-deacetylnimbinene, 6-Oacetylnimbandiol, and nimbolide, replicate the binding mode of the Pin1 substrate peptide, interacting with high affinity with the binding site and thus destabilizing the Pin1 structure.

Conclusion:

Our results are supported by experimental data, and provide interesting structural insights into their molecular mechanism of action, indicating that their structural scaffolds could be used as a start point to develop new inhibitors against Pin1.
Antiangiogenic Effect of Isomalyngamide A Riboside CY01 in Breast Cancer Cells via Inhibition of Migration, Tube Formation and pVEGFR2/pAKT Signals
Authors: Shih Ching-Ying , Chang Tzu-Ting , Chen Chia-Ling , Li Wen-Shan
Published: October 2019

Background:

To block the metastatic and angiogenic pathways during the tumor progression arouses
considerable pharmacological interests in the development of anticancer drugs.

Objective:

To develop alternative antiangiogenic and antimetastic agents, we designed and prepared a series of
nature inspired isomalyngamide A analogs containing ribose conjugate with 1,2-diaminoethane or 1,3-
diaminopropane linkers (1-8).

Methods:

The target glycosylated isomalyngamide A analogs 1-8 were constructed through condensation of the
malonic acids 16-19 and the corresponding aminoethoxyl ribosides 20 and 21, using HBTU/DIPEA as the coupling
agent. The cell growth inhibition assay, cell migration assay, transwell invasion assay, adhesion assay,
tube formation assay and western blot analysis were used to validate the biological actions of compounds.

Results:

The most effective compound, isomalyngamide A riboside 1 (CY01), possessing a D-ribose core structure
and a 1,3-diaminopropane linker, showed significant suppression of MDA-MB-231 cell migration and
inhibited tube formation of Human Umbilical Vascular Endothelial Cells (HUVECs) in a dose-dependent manner.
Effect of the latter is comparable to that of sorafenib, an orally active multikinase inhibitor and an inhibitor
of angiogenesis. CY01 also showed slight inhibition on collagen type IV- and laminin-mediated cell adhesion.
These actions may be regulated through the blockade of the VEGF/VEGFR2 signaling pathway by inhibiting
the VEGF induced phosphorylation of p-VEGFR2 and p-AKT.

Conclusion:

In this effort, we have discovered synthetic and glycosylated marine metabolites which may serve
as an alternative antiangiogenic and antimetastic agent during multitherapy.
Microfluidics for the Production of Nanomedicines: Considerations for Polymer and Lipid-based Systems
Authors: Streck Sarah , Hong Linda , Boyd Ben J. , McDowell Arlene
Published: October 2019

Background:

Microfluidics is becoming increasingly of interest as a superior
technique for the synthesis of nanoparticles, particularly for their use in nanomedicine. In
microfluidics, small volumes of liquid reagents are rapidly mixed in a microchannel in a
highly controlled manner to form nanoparticles with tunable and reproducible structure
that can be tailored for drug delivery. Both polymer and lipid-based nanoparticles are utilized
in nanomedicine and both are amenable to preparation by microfluidic approaches.

Aim:

Therefore, the purpose of this review is to collect the current state of knowledge on
the microfluidic preparation of polymeric and lipid nanoparticles for pharmaceutical applications,
including descriptions of the main synthesis modalities. Of special interest are the
mechanisms involved in nanoparticle formation and the options for surface functionalisation
to enhance cellular interactions.

Conclusion:

The review will conclude with the identification of key considerations for the
production of polymeric and lipid nanoparticles using microfluidic approaches.
A Prototype Design of Scanning Mirror Used in MEMS and Its Experimental Verification
Authors: Luo Xianquan , Lv Junwei
Published: October 2019

Background:

The MEMS scanning mirror prototype is a spatial scanning device, which has advantages such as light mass, low drive voltage, large scanning and high angular measurement accuracy.

Methods:

The MEMS scanning mirror prototype uses the piezoelectric driving principle to drive the micro-structure to realize two-axis scanning. The corner of the MEMS scanning mirror is measured by using a piezoelectric resistance sensor. In the paper, the damping properties of MEMS scanning mirrors have been studied, which deduce the damping force formula of MEMS scanning mirrors. Moreover, the influence of different sizes and structures of MEMS scanning mirrors on the damping force and the amplitude of scanning mirror angles are analyzed, and a structural optimization design method to reduce the driving voltage of MEMS scanning mirrors is proposed.

Results:

The theoretical analysis, design and testing of piezoelectric driven MEMS scanning microscopes have been carried out.

Conclusion:

Through related experiments, it is verified that the maximum scanning range and the precision index of angle measurement meet the requirements of the index.
Влияют ли химические эффекты на накопление структурных нарушений при имплантации в GaN ионов фтора?
Authors: Титов А.И. , Карабешкин К.В. , Карасев П.А. , Стручков А.И.
Published: October 2019

Structural damage buildup in GaN under irradiation by
1.3 and 3.2 keV/amu F and Ne ions has been studied. It is shown
that chemical effects during irradiation with fluorine ions do not
enhance formation of stable structural damage on the surface or in
the bulk of GaN at all the doses considered.
Термический коэффициент движения резонансного уровня железа в сплавах Pb-=SUB=-1-x-y-=/SUB=-Sn-=SUB=-x-=/SUB=-Fe-=SUB=-y-=/SUB=-Te
Authors: Скипетров Е.П. , Ковалев Б.Б. , Скипетрова Л.А. , Кнотько А.В. , Слынько В.Е.
Published: October 2019

The phase composition, the elemental composition
and temperature dependences of the resistivity and of the Hall
coefficient (temperature interval 4.2≤T≤300K, magnetic fields
B≤0.07 T) in Pb1−x−ySnxFeyTe alloys are studied at variation
of the tin and iron concentrations along the single-crystal ingots
synthesized by the Bridgman−Stockbarger technique. The distributions
of tin and iron along the ingots are obtained and anomalous
temperature dependences of the Hall coefficient, associated with
the pinning of the Fermi level by the resonant level of iron, located
in the valence band, are found. The analysis of the experimental
results is carried out in the framework of the model of the
electronic structure rearrangement, involving the movement of the
iron level relative to the top of the valence band with increasing tin
concentration and temperature. The temperature coefficient of the
movement of the level of iron with respect to the middle of the gap
is determined and the possible diagrams for the rearrangement of
the electronic structure with increasing temperature in the alloys
with normal spectrum (0.06≤x≤0.35) are proposed.
Люминесцентные свойства высокоомного кремния, облученного тяжелыми ионами высоких энергий
Authors: Черкова С.Г. , Скуратов В.А. , Володин В.А.
Published: October 2019

The float zone (high-resistance) silicon irradiated with swift heavy ions was studied by photoluminescence (PL) spectroscopy method. In addition to well-known X, W, W’, R and C lines, a broad peak (1.3 – 1.5 μm) appears in PL spectra at low-temperatures. As the irradiation dose increases from 3•10_11 to 10_13 cm-2, the PL intensity decreases by about an order of magnitude, also a narrowing of the peak with red-shift is observed.
Квантовые поправки и магнитотранспорт в пленках 3D дираковского полуметалла Cd-=SUB=-3-x-=/SUB=-Mn-=SUB=-x-=/SUB=-As-=SUB=-2-=/SUB=-
Authors: Мехия А.Б. , Казаков А.А. , Овешников Л.Н. , Давыдов А.Б. , Риль А.И. , Маренкин С.Ф. , Аронзон Б.А.
Published: October 2019

In this work we investigated thin films of solid solutions based on the three-dimensional Dirac semimetal Cd3As2 with Mn. The Cd3-xMnxAs2 (x = 0, 0.05 и 0.1) films with thickness around 50 – 70 nm were synthesized on sitall substrates via vacuum thermal evaporation of Mn-doped cadmium arsenide ingots, obtained by the direct melting of components in vacuum ampoules. We measured temperature and magnetic field dependences of films resistivity and defined corresponding transport parameters. Films with x = 0 and 0.05 exhibited positive magnetoresistance with characteristic form, corresponding to the contribution of weak antilocalization effect. At higher Mn content (x = 0.1) we observed the contribution of weak localization effect. Such change of the quantum correction type, in case of topological semimetals, suggest the transformation of the band structure and transition from the Dirac semimetal state into trivial phase, which, in our case, corresponds to the critical Mn content of about xc ~ 0.07.
Исследование однородности состава по толщине слоев GaInAsP, полученных на подложках InP методом газофазной эпитаксии
Authors: Гагис Г.С. , Левин Р.В. , Маричев А.Е. , Пушный Б.В. , Щеглов М.П. , Бер Б.Я. , Казанцев Д.Ю. , Кудрявцев Ю.А. , Власов А.С. , Попова Т.Б. , Чистяков Д.В. , Кучинский В.И. , Васильев В.И.
Published: October 2019

GaInPAs/InP heterostructures grown by low pressure (0.1 bar, 600 oC) metal-organic chemical vapor phase deposition were investigated. The thicknesses of grown GaInAsP layers were about 1 µm. For the epitaxial layers Ga1-xInxP1-yAsy) with average compositions of x = 0.77 – 0.87 and y = 0.07 – 0.42 the variation of V group elements content y with the epilayer depth were revealed, weher the compositions of V-group elements were changed up to Δy = 0.1 atomic fractions in V group elements sublattice. In most cases, y change occurs in a GaInAsP region up to 200 nm thick adjacent to the InP. In some cases, y changes throughout the whole GaInPAs layer thickness. Fo the epitaxial layers with a satisfactory crystal perfection the less was the mismatch between the substrate and the GaInPAs epitaxial layer, the smaller was the value of Δy. For GaInPAs layers characterized by a low degree of crystal perfection and a high lattice mismatch between GaInAsP and InP layers, the value of Δy was about zero. These data let us suggest that the incorporation of atoms of the V group in the epitaxial layer strongly depends on elastic deformation of the growing monolayer, that is mismatched with the underlying crystal surface.
Фотолюминесценция с временным разрешением наноструктур InGaAs различной квантовой размерности
Authors: Надточий А.М. , Минтаиров С.А. , Калюжный Н.А. , Максимов М.В. , Санников Д.А. , Ягафаров Т.Ф. , Жуков А.Е.
Published: October 2019

By using time-correlated single-photon counting time-resolved photoluminescence of quantum-sized heterostructures of different dimensionality was investigated. InGaAs quantum dots, quantum well, and transitionally-dimensional structure — quantum well-dots were grown on GaAs substrates. It was observed, that photoluminescence decay strongly depends on structure dimensionality resulting in decay value of 6,7, and more than 20 ns for quantum dots, well-dots and well, respectively. As we believe localization centers in heterostructures may be responsible for such shortening of photoluminescence lifetime.
Анизотропные триггерные электрические свойства двумерных сверхрешеток
Authors: Завьялов Д.В. , Конченков В.И. , Крючков С.В.
Published: October 2019

The problem of spontaneous generation of a transverse electric field in a two-dimensional superlattice with an additive spectrum when the pulling field changes is considered. It is shown that in the case the width of the minizone coincides in the longitudinal and transverse directions, when the pulling field reaches a certain threshold value, two equally probable states of the system arise, corresponding to the appearance of a transverse field of different signs, which leads to a fracture on the longitudinal volt-ampere characteristic. In case of deviation from the width equality of the minizone, one of these states becomes energetically more preferable, but with some impulse action the system can move to the second state, which leads to a jump-like change in the longitudinal current in the superlattice.
Структура халькогенидного стеклообразного полупроводника Se-=SUB=-95-=/SUB=-As-=SUB=-5-=/SUB=-, легированного примесью EuF-=SUB=-3-=/SUB=-
Authors: Гарибова С.Н. , Исаев А.И. , Мехтиева С.И. , Атаева С.У.
Published: October 2019

The local structure of film samples of chalcogenide glassy semiconductor Se95As5 and Se95As5(EuF3)x (x = 0.01 ÷ 1 at%) have been studied by X-ray diffraction and Raman scattering. The ‘‘quasi-period’’ of the structure, the correlation length, the structural elements and chemical bonds that form the amorphous matrix of the materials studied have been determined. Interpretation of results obtained has been carried out within the framework of the Elliot voidscluster model, taking into account the chemical activity of europium ions.
Спектры пленок SmS в дальней и средней ИК областях
Authors: Улашкевич Ю.В. , Каминский В.В. , Соловьев С.М. , Шаренкова Н.В.
Published: October 2019

AbstractThe basic features of the band structure observed in bulk samples are retained in polycrystalline SmS thin films. Specifically, the bottom of the conduction band is formed from s -type states and there exist donor impurity levels in the band gap, at an energy of 0.04–0.065 eV below the bottom of the conduction band.
Формирование ncl-Si в аморфной матрице a-SiO-=SUB=-x-=/SUB=- : H, расположенной вблизи анода и на катоде, с помощью модулированной по времени DC-плазмы с (SiH_4-Ar-O-=SUB=-2-=/SUB=-)-газовой фазой (C-=SUB=-O_2-=/SUB=-=21.5 мол%)
Authors: Ундалов Ю.К. , Теруков Е.И. , Трапезникова И.Н.
Published: October 2019

AbstractThe formation of ncl -Si in the amorphous matrix a -SiO_ x :H using a time-modulated DC plasma at an elevated oxygen content of $${{C}_{{{{{\text{O}}}_{2}}}}}$$ = 21.5 mol % in a gas mixture of (SiH_4–Ar–O_2) is investigated. Plasma modulation implies the repeated ( n = 180) switching on (for t _on = 5, 10, 15 s) and switching off (for t _off = 5, 10, 15 s) of the magnet coil of the DC magnetron. The effect of self-induction is used to enhance the processes of SiH_4 dissociation, the formation of Si nanoparticles, and the ionization of oxygen and ncl -Si flows towards the electrodes. The samples are located both on an electrically isolated substrate holder near the anode and on the cathode (beyond its erosion zone). These experiments show that the shape of the dependences of the photoluminescence intensity $$I_{{{\text{PL}}}}^{{ncl - {\text{Si}}}}$$ on the wavelength Λ are identical for all pairs of samples on the anode and cathode. When the t _on value is small ( t _on = 5 s), the difference in the sample location only slightly affects the infrared (IR) spectra. At longer times t _on (≥10 s) and a short time t _off (5 s), the amorphous matrix located on the cathode is enriched with oxygen (as compared with that near the anode). The optimal plasma-modulation parameters are found to be t _off/ t _on = 5, 10, 15/10 and t _off/ t _on = 5, 10/15; under these conditions, the amorphous matrix has a “perfect structure” and is transparent to radiation, and the $$I_{{{\text{PL}}}}^{{ncl - {\text{Si}}}}$$ value is the largest in the range λ ≈ 0.75–0.9 μm.
Определение концентрации свободных носителей заряда в легированных бором кремниевых нанонитях при помощи инфракрасной спектроскопии в режиме нарушенного полного внутреннего отражения
Authors: Липкова Е.А. , Ефимова А.И. , Гончар К.А. , Преснов Д.Е. , Елисеев А.А. , Лапшин А.Н. , Тимошенко В.Ю.
Published: October 2019

Attenuated total reflection infrared spectroscopy was used to determine the free charge carrier concentration in the arrays of silicon nanowires of characteristic transverse dimension of 50–100 nm and the length of the order of 10 μm which were formed on low-doped crystalline p-type silicon via metal-stimulated chemical etching and subjected to additional thermodiffusion boron doping at the temperatures 850–1000 оС. It was found out that the free hole concentration varies from 5•1018 to 3•1019 cm-3 depending on the annealing temperature and reaches it’s maximum at 900–950 оС. The results can be used to expand the scope of silicon nanowires application in photonics, sensorics and thermoelectric power converters.
Противодействующий фотовольтаический эффект в верхней межгенераторной части трехпереходных GaInP/GaAs/Ge солнечных элементов
Authors: Минтаиров М.А. , Евстропов В.В. , Минтаиров С.А. , Шварц М.З. , Калюжный Н.А.
Published: October 2019

AbstractThe “top” intergenerator part situated between the GaInP and GaAs subcells (electric power generators) is analyzed. The shape of the light current–voltage characteristics and the V _ oc – J _ sc (open-circuit voltage–short-circuit current) dependence are examined. It is found that the p ^+– n ^+ tunnel heterojunction situated in the “top” intergenerator part can operate as a photoelectric source counteracting the base p – n junctions. In this case, the V _ oc – J _ sc characteristic has a descending part, and a sharp jump can be observed. This undesirable effect becomes weaker with increasing peak current of the tunnel junction.
Процессы самосборки нанокристаллов CdS, синтезированных методом Ленгмюра-Блоджетт
Authors: Свит К.А. , Журавлев К.С.
Published: October 2019

AbstractThe morphology of CdS nanocrystal arrays self-assembled during the evaporation of a behenic-acid organic matrix on a wetted substrate surface is studied by atomic force microscopy. The dependence of the morphology of nanocrystal arrays on the initial matrix surface is studied. The morphology of nanocrystal arrays noticeably changes from small fractal arrays to a porous submonolayer with an increase in the nanocrystal density. The nature of attractive forces between nanocrystals which prevents their reversible adhesion and ensures their comparatively high mobility in the array composition is proposed.
Комбинационное рассеяние света в кристаллах AlN, выращенных методом сублимации на затравках SiC и AlN
Authors: Бреев И.Д. , Анисимов А.Н. , Вольфсон А.А. , Казарова О.П. , Мохов Е.Н.
Published: October 2019

AbstractThe Raman-scattering technique is used to analyze the structural quality of bulk AlN crystals grown by sublimation on SiC and AlN seeds. Growth on SiC seeds is conducted with retention of the SiC seed during growth (type 1) and with total evaporation of the SiC seed (type 2). Growth on AlN seeds is conducted in tungsten containers with no graphite parts (type 3). According to the analysis of Raman spectra, the highest quality is inherent in type-3 crystals that exhibit minimal full widths at half maximum of Raman lines. The experimentally observed specific features are defined by differences in the mechanism of growth and by the content of dopant impurities in the crystals grown.
Механизм генерации синглетного кислорода на поверхности возбужденного нанопористого кремния
Authors: Самосват Д.М. , Чикалова-Лузина О.П. , Зегря Г.Г.
Published: October 2019

A theoretical analysis of the mechanism of generation of singlet oxygen on the surface of photoexcited nanoporous silicon is presented. It is shown that the nonradiative energy transfer from nanoporous silicon to the oxygen molecule by the Dexter exchange mechanism is the basis for the mechanism of singlet oxygen generation. An analytical expression is obtained and a numerical estimate of the probability of energy transfer from nanoporous silicon to an oxygen molecule is given. It was shown that its numerical value ~ (10^3-10^4) s^{-1} agrees quite well with experiment.
Об одном нелинейном эффекте в теории сверхпроводимости
Authors: Гладков С.О.
Published: October 2019

AbstractBased on the solution of the hydrodynamic equations and Maxwell’s equations, we show that an external quasi-homogeneous magnetic field leads to the emergence of a secondary electric field that is resulted from a nonlinear effect over magnetic potential A . This field is proved to exist in the region with a depth of $$\delta {\text{/}}2$$ , where δ is the London penetration depth. The hydrodynamic flow velocity is estimated.
Обнаружение новой фазы типа B1 в монокристаллах магнитомягких сплавов Fe-Al и Fe-Ga
Authors: Черненков Ю.П. , Ершов Н.В. , Лукшина В.А.
Published: October 2019

AbstractThe atomic structure of Fe–Al (7 and 9 at % Al) and Fe–Ga (18 at % Ga) alloys is studied by X‑ray diffraction using a laboratory four-circle diffractometer. After refining annealing, single-crystal alloy samples were annealed in the ferromagnetic state ( T < T _C). One sample of the Fe–18 at % Ga alloy, after short holding in the paramagnetic state ( T > T _C), was quenched in room temperature water. Earlier, the authors reported on the peculiarities of the ordering of alloying atoms in B 2 and D 0_3 phase structures in quenched and annealed samples of these alloys. Here, we present and discuss the results of our observations in these alloys of a new phase with a face-centered cubic (fcc) lattice ( B 1-type structure with NaCl prototype and unit cell parameter ~5.2 nm). The fcc phase appears in the Fe–Al alloy as the aluminum concentration increases from 7 to 9 at %; it is observed in the Fe–18 at % Ga alloy, and its volume fraction increases after annealing in the ferromagnetic state in comparison with a quenched alloy sample. In these alloys (9 at % Al) and (18 at % Ga), different ways of embedding fcc crystals in the bcc phase of single crystals are realized; i.e., the axes of the fcc lattice are directed in four different ways relative to the axes of the bcc lattice.
Дипольное упорядочение и ионная проводимость в NASICON-подобных структурах типа Na-=SUB=-3-=/SUB=-Sc-=SUB=-2-=/SUB=-(PO_4)-=SUB=-3-=/SUB=-
Authors: Ногай А.С. , Ногай А.А. , Стефанович С.Ю. , Солиходжа Ж.М. , Ускенбаев Д.Е.
Published: October 2019

AbstractProblems of the dipole ordering and ionic conductivity of Na_3Sc_2(PO_4)_3 polycrystal that has three polymorphic phases—α, β, and γ—are studied. The features of the α-Na_3Sc_2(PO_4)_3 crystal structure and the dipole ordering and relaxation polarization in the α and β phases are specified. The origin of the dipole ordering in the α phase and the partial dipole disordering in the β-Na_3Sc_2(PO_4)_3, as well as the high ionic conductivity in the β and γ phases of the Na_3Sc_2(PO_4)_3 polycrystal are associated with phase transformations α → β, β → γ that result in structural changes of the rhombohedral {[Sc_2(PO_4)_3]^3–}_3∞ crystalline framework. A model explaining the emergence of the dipole ordering and the ionic conductivity phenomena in Na_3Sc_2(PO_4) is proposed.
Примесная магнитная восприимчивость полупроводников в случае прямого обменного взаимодействия в модели Изинга
Authors: Богословский Н.А. , Петров П.В. , Аверкиев Н.С.
Published: October 2019

The dependence of the impurity magnetic susceptibility on temperature was studied by numerical simulation. The direct exchange interaction of magnetic moments of randomly distributed impurities was considered within the Ising model. The dependence of the magnetic susceptibility in such a system deviates from the Curie law at low temperature, which is associated with the formation of a spin glass phase. It is shown that the pre-exponential factor of the direct exchange interaction significantly influences on the temperature dependence of the magnetic susceptibility only in the case of ferromagnetic exchange.
Фотолюминесценция кристаллов Cu-=SUB=-2-=/SUB=-O различного происхождения
Authors: Агекян В.Ф. , Серов А.Ю. , Философов Н.Г.
Published: October 2019

The low-temperature luminescence spectra of Cu2O crystals grown by the different methods (copper oxidation, induction melting, magnetron sputtering, hydrothermal synthesis) and of natural crystal are compared. It was concluded that the high quality of natural crystals and crystals grown by the hydrothermal method is due to the low temperature process of their formation which minimizes the strains.
Расчет динамики решетки кристаллов RFe-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=- в квазигармоническом приближении
Authors: Павловский М.С. , Андрюшин Н.Д.
Published: October 2019

The lattice dynamic calculations and calculation of temperature dependence of the vibrational frequencies in the quasi-harmonic approximation were carried out for RFe3(BO3)4 crystals (R = Pr, Nd, Tb, Dy, Ho) in high temperature phase R32. It was obtained that in the boundary point Λ of Brillouin zone the frequency of instable vibrational mode, which associated with structural phase transition R32 -> P3121, change intensely with temperature in TbFe3(BO3)4, DyFe3(BO3)4 and HoFe3(BO3)4 crystals. The frequency of “soft” mode stabilizes with temperature increasing and takes a real value. Significant changes in phonon spectra, including in the boundary point Λ, in PrFe3(BO3)4 and NdFe3(BO3)4 crystals with temperature increasing were not observed.
Структурные механизмы и термодинамическое описание изосимметрийного орбитального упорядочения в редкоземельных манганитах
Authors: Ивлиев М.П. , Сахненко В.П.
Published: October 2019

It is shown that the observed features of the orbital phase transition in AMnO3 perovskites (A = La, Pr, ..., Lu) are due to the occurrence of rotational distortions of a cubic lattice at high temperatures, causing anion displacements that create an “internal field” which, by symmetry, coincides with the order parameter describing the ordering of octahedra distorted due to the Jahn-Teller effect (orbital ordering). The influence of this “field” essentially determines the type of orbital ordering, its temperature and the nature of the phase transition. A comparative analysis of orbitally ordered states was carried out for the entire series of AMnO3, both in the framework of the phenomenological theory of phase transitions and on the basis of the three-minimum multi-lattice model proposed in the article. The specific features of the magnetic transitions in manganites, due to the specific features of the structure, are discussed.
Корреляция между величинами фтор-ионной проводимости кристаллов Sr-=SUB=-1-x-=/SUB=-R-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- (тип CaF-=SUB=-2-=/SUB=-) и R-=SUB=-1-y-=/SUB=-Sr-=SUB=-y-=/SUB=-F-=SUB=-3-y-=/SUB=- (тип LaF-=SUB=-3-=/SUB=-) в системах SrF-=SUB=-2-=/SUB=--RF-=SUB=-3-=/SUB=- (R=La-Nd)
Authors: Сорокин Н.И. , Соболев Б.П.
Published: October 2019

AbstractThe “conductivity logarithm–composition” correlation logσ_dc( x ) = ax + b has been revealed for the strongly nonstoichiometric fluorite Sr_1 – _ x R_ x F_2 + _ x ( x is the RF_3 molar fraction, 0.15 ≤ x ≤ 0.47) and tysonite R_1 – _ y Sr_ y F_3 – _ y ( y is the SrF_2 molar fraction, y = 1 – x , 0.85 ≤ x ≤ 0.97) phases in the SrF_2–RF_3 systems (R = La, Ce, Pr, Nd). The conductivity σ_dc of the eutectic 70LaF_3 + 30SrF_2 (mol %) composite fits well with the dependence logσ_dc( x ) for the nonstoichiometric Sr_1 – _ x La_ x F_2 + _ x and La_1 – _ y Sr_ y F_3 – _ y phases.
Динамические перестройки трехмерной топологической структуры движущейся доменной границы в магнитной пленке при наличии случайных возмущений
Authors: Зверев В.В. , Байкенов Е.Ж. , Изможеров И.М.
Published: October 2019

Dynamic processes in a domain wall (DW) moving under a constant magnetic field in a soft-magnetic uniaxial film with in-plane anisotropy were studied using three-dimensional micromagnetic modeling. It was shown that the nature of the dynamics of topological transformations occurring in the DW can vary significantly due to disturbing factors depending randomly on coordinates or on time (spatially inhomogeneous anisotropy; magnetic field fluctuating in time). At the same time, typical configurations of the magnetization field in the vicinity of intrafilm vortex cores and singular (Bloch) points retain their appearance. The dependences of the energies and displacements of the DWs on time are found for a wide range of film thicknesses, temperatures, and magnetic fields. When analyzing the magnetization configurations, visualization methods based on the calculation of two types of topological charges were used.
Влияние текстуры на ширину доменов в спеченных магнитах (PrDy)(FeCo)B и (NdDy)(FeCo)B
Authors: Безверхний А.И. , Коплак О.В. , Валеев Р.А. , Королев Д.В. , Пискорский В.П. , Моргунов Р.Б.
Published: October 2019

AbstractWe analyzed magnetic force microscopy images of the surface of samples cut parallel and perpendicular to the texture created by applying a field in the process of pressing a magnet. The distribution of the linear size (width) of the domains correlates with the distribution of the projection area of grains onto the shear plane in sintered (PrDy)(FeCo)B magnets with radial magnetization and in prismatic (NdDy)(FeCo)B magnets. The effects of grain size and direction of the axes of easy magnetization of grains on the width of the domains, as the main factors controlling the domain structure, are discussed.
Бистабильное и многодоменное состояния ферромагнитных микропроводов alpha-Fe/(PrDy)(FeCo)B
Authors: Коплак О.В. , Сидоров В.Л. , Куницына Е.И. , Валеев Р.А. , Королев Д.В. , Пискорский В.П. , Моргунов Р.Б.
Published: October 2019

Microwire of α-Fe(50 at.%)(PrDy)(FeCo)B(48 at.%) was obtained by extracting a hanging melt drop of (PrDy)(FeCo)B in an electron beam. It was shown that a single microwire with a diameter of 50 μm and a length of 0.8 - 6 mm with an amorphous phase (PrDy)(FeCo)B content of ~ 48% and a polycrystalline α-Fe phase of ~ 52% has a rectangular narrow magnetic hysteresis loop and, accordingly, a bistable state with a switching field of ~ 100 Oe. The shortening of the wire to ~ 0.6 mm leads to a sharp deviation from the squareness of the loop, reducing the slope of the dependence of the magnetization on the field and the coercive force to 20 Oe. In the subsurface layers consisting of the amorphous phase (PrDy)(FeCo)B, oriented areas of reverse magnetization are observed. The role of the magnetic dipole interaction in the formation of a magnetic hysteresis loop of chaotic microwire assemblies of various compositions is discussed.
Структура и диэлектрические свойства наноструктурированной керамики Bi-=SUB=-1-x-=/SUB=-Sm-=SUB=-x-=/SUB=-FeO-=SUB=-3-=/SUB=-
Authors: Садыков С.А. , Алиханов Н.М-Р. , Каллаев С.Н. , Рабаданов М.Х. , Палчаев Д.К. , Мурлиева Ж.Х. , Эмиров Р.М.
Published: October 2019

The structure and dielectric properties of polycrystalline multiferroics of the Bi1-xSmxFeO3 system (x = 0-0.2) are investigated. X-ray diffraction revealed that two phases coexist in the x = 0.1 nanostructured sample: rhombohedral R3c and orthorhombic Pbam. On the temperature dependences of the dielectric constant ε'(T), four anomalies characteristic of phase transformations were found in the temperature range of ~ 180°С, ~ 250°С, ~ 300°С and TN ~ 350°С. It is shown that with increasing samarium concentration, the dielectric constant ε' increases, and tgδ decreases
Разрушение АБС-пластика в стеклообразном состоянии при динамическом нагружении
Authors: Атрошенко С.А. , Чеврычкина А.А. , Евстифеев А.Д. , Волков Г.А.
Published: October 2019

The article is devoted to experimental and theoretical research of fracture mechanisms of ABS-plastic in the range of strain rates of 10^(-4) - 10^3 1 / s at different test temperatures (from room temperature - 23 to 100 C). The change in the fracture type is analyzed depending on a strain rate and temperature. The model of temperature-time superposition is proposed based on the structural-time approach.
Механизм влияния дисперсных наночастиц на параметры мартенситных переходов в сплавах с эффектом памяти формы
Authors: Малыгин Г.А.
Published: October 2019

AbstractWithin the diffuse martensitic transition theory based on the thermodynamic and kinetic equations and relations, the mechanism of influence of disperse nanoparticles on the parameters of martensitic transitions in alloys with the shape memory effect (SME) is analyzed. The objects of the analysis are the TiNi alloy with the varied sizes of Ti_3Ni_4 particle at their constant volume concentration, and the NiMnGaTb alloy with Tb precipitate particles with constant sizes and variation of volume concentration of the precipitates. Information about these alloys is available in the literature. The analysis has shown that, due to the coherent coupling of the Ti_3Ni_4 particles with the substrate, the temperature width of the transition R – B 19' depends on the particle sizes, which confirms the earlier established regularity of the local interior strain influence on this parameter. Concerning the NiMnGaTb alloy, the analysis has shown that, due to the presence of interior local strains associated with the Tb particles, the temperature width of the martensitic transformations increases linearly alongside the growth of the particle concentration in the alloy. The existence of the critical value of the particle concentration, above which the temperature width of the transition becomes indefinitely large, and the martensitic transformation in the alloy is blocked, is shown.
Влияние неравновесных корреляций на эффективные сопротивления между центрами в теории прыжковой проводимости
Authors: Шумилин А.В. , Бельтюков Я.М.
Published: October 2019

AbstractIt has been shown that the nonequilibrium correlations in hopping conductivity can be taken into account by generalizing the Miller–Abrahams network of resistors. The resistances of resistors between nodes in such a network are related to their environment. Moreover, some nonlocal elements exist, which create the voltage on one resistor proportional to the current through the other resistor. These elements are required to make controllable the approximation used to construct the network. The greatest change in the resistance takes place in the resistors, whose resistance is lower than the critical resistance of the percolation theory.