bluuebunny/crossref_metadata_2025 huggingface dataset:
Política e crença
Authors: Moreira Helce Amanda de Oliveira , Leal Marina Y Gonzales , Carvalho José Mauricio Avilla , Teixeira Pedro Pinheiro
Published: January 2023

Tomando como objeto a Base Nacional Comum Curricular (BNCC) e o movimento para regulamentação do homeschooling, este estudo propõe a identificação das crenças que fundamentam as ações dos atores envolvidos em suas defesas. Elaborou-se uma pesquisa documental com foco no Movimento pela Base (MPB), ator favorável à BNCC, e na Campanha EducAÇÃO Domiciliar - Direito Já!, que coaduna atores da coalizão em prol do ensino domiciliar. Para as análises, o trabalho utilizou categorias do Modelo de Coalizão de Defesa, criado por Sabatier e Jenkins-Smith na década de 1980. Como resultado, identificou-se que, apesar de ambas as políticas dialogarem com o direito à educação – seja pela vinculação desse direito à homogeneização do currículo ou pelo questionamento de a quem cabe a responsabilidade de provê-lo –, esses atores possuem crenças e modos de organização distintos, o que justifica a diferença em interesses e estratégias.
Metodologias de aprendizagens no ensino a distância
Authors: Rocha Jorge Vieira da , Santos Sonia Regina Mendes dos
Published: January 2023

Com o avanço tecnológico, as ferramentas digitais se tornaram presentes em todos os segmentos de trabalho, e com a educação aconteceu o mesmo. Novas tecnologias associadas a projetos de Educação a Distância (EAD) aumentam a capacidade de acesso a um programa de formação profissional. Com isso, novas metodologias de ensino são utilizadas pelos professores com o objetivo de levar um conhecimento de melhor qualidade a seus alunos. Com a democratização do ensino e o crescimento das novas tecnologias, as metodologias e processos EAD se tornam mais aplicáveis e flexíveis a quem queira estudar. O objetivo do estudo é o de conhecer como as metodologias de aprendizagem contribuem para esta evolução. A metodologia fundamenta-se na pesquisa exploratória, na qual se realizou o levantamento de trabalhos de tese, dissertação e artigos científicos que trazem para discussão as causas de desistências e evasão na EAD, entre os anos de 2002 e 2022.
Educação, corporeidade e a pessoa com deficiência visual
Authors: Teixeira Andressa Karoline Santana , Couto Hergos Ritor Fróes de
Published: January 2023

O corpo traz em si diferentes linguagens e significados, por meio dele se estabelecem relações nas quais estão envolvidas outras pessoas, outros seres, as coisas que se encontram no entorno, o mundo. Diante disso, o estudo tem como objetivo compreender as concepções de corpo de alunos com deficiência visual de escolas públicas de Santarém-PA, à luz da abordagem da corporeidade. Optou-se pela pesquisa descritiva de cunho qualitativo. A estrutura teórico/metodológica baseia-se nos pressupostos do fenômeno da corporeidade. Utilizou-se questionário de caracterização do participante e entrevista semiestruturada. Os dados foram analisados a partir da Elaboração e Análise de Unidades de Significado. Os resultados possibilitaram compreender que as pessoas com deficiência visual possuem concepções de corpo que apresentam diferentes sentidos e significados, transitando entre conceitos biologistas e mecânicos, mas também que se aproximam da abordagem da corporeidade, que considera o corpo como a existência e experiência do ser no mundo.
Inclusão escolar na perspectiva do professor especializado
Authors: Carneiro Relma Urel Carbone , Pedroso Cristina Cinto Araujo , Santos Denise Cristina França dos
Published: January 2023

O estudo objetivou analisar o trabalho desenvolvido pelo professor especializado em um contexto de transição do papel da Educação Especial de um modelo substitutivo para um modelo complementar. O desenvolvimento da pesquisa se deu numa abordagem qualitativa do tipo descritiva. Para a coleta de dados, utilizamos a técnica de grupo focal. Os dados mostraram resistência dos participantes em aceitar o direito do aluno PAEE de estudar em ambientes comuns e, também, que a atuação da Educação Especial, na maioria das vezes, continua sendo substitutiva e compensativa, mantendo a exclusão. Os dados indicaram que a história da Educação Especial como um serviço paralelo ainda está muito arraigada no ambiente escolar, sendo legitimada tanto por professores especializados, quanto por professores de classes comuns e gestores educacionais. Em síntese, ainda não contamos no Brasil uma escola para os alunos PAEE que supere as fragilidades da escola comum e da instituição especializada.
Experiência estética
Authors: Berkenbrock-Rosito Margaréte May , Oliveira Kiara Maia de
Published: January 2023

Busca-se compreender o lugar da experiência estética no contexto do trabalho docente e na formação inicial de pedagogos/as, por meio do sentido da autonomia e submissão, nas narrativas (Auto) Biográficas de 45 alunas, produzidas no Curso de Pedagogia por meio do dispositivo investigativo e formativo Colcha de Retalhos, em 2018. O referencial teórico adotado assenta-se no conceito de Experiência Estética, em Adorno (2008), da estética, em Schiller (2017), e a estética como pilar da autonomia, em Freire (1996). As narrativas mostram que a autonomia aparece limitada em seu silêncio, e se revela submissa, podendo atuar dentro de um limite imposto pela hierarquização da razão sobre a sensibilidade, por meio do medo. Considerando toda a violência e medo, a experiência estética denuncia a feiura do sistema e revela maneiras para que, com ousadia, encontremos caminhos de desenvolvimento da autonomia como processo de humanização dos sujeitos.
Liderazgo transformacional del directivo y su relación con el desempeño docente
Authors: Rojas Oscar , Martinez Marlenis , Moyano Genaro
Published: January 2023

El estudio tuvo como objetivo determinar el clima organizacional y su relación con el desempeño docente de las escuelas Municipales de la comuna Frutillar, Región de Los Lagos-Chile, año 2021. La metodología manejada fue el enfoque cuantitativo bajo una investigación de tipo básico con un diseño no experimental-correlacional. La población constituida por 57 docentes que laboran en las instituciones antes indicadas. Para efectos de la muestra se utilizó el muestreo probabilístico, tomando como muestra el total de la población. Para la recolección de la información se aplicó la técnica de la encuesta y como instrumento un cuestionario con escalamiento tipo Likert. Al mismo tiempo, la validez del instrumento se formalizó por medio del juicio de expertos y la confiabilidad por el Alpha de Cronbach con un valor de 0,63; considerándose alta la confiablidad. Concluyendo que el equipo directivo debe fortalecer los estilos de liderazgo para que en la escuela exista un efectivo desempeño docente.
Herbal Substances with Antiviral Effects: Features and Prospects for the Treatment of Viral Diseases with Emphasis on Pro-Inflammatory Cytokines
Authors: Bjørklund Geir , Lysiuk Roman , Semenova Yuliya , Lenchyk Larysa , Dub Natalia , Doşa Monica Daniela , Hangan Tony
Published: January 2023

Viral diseases have a significant impact on human health, and three novel coronaviruses (CoV) have emerged during the 21st century. In this review, we have emphasized the potential of herbal substances with antiviral effects. Our investigation focused on the features and prospects of viral disease treatment, with a particular emphasis on proinflammatory cytokines. We conducted comprehensive searches of various databases, including Science Direct, CABI Direct, Web of Science, PubMed, and Scopus. Cytokine storm mechanisms play a crucial role in inducing a pro-inflammatory response by triggering the expression of cytokines and chemokines. This response leads to the recruitment of leukocytes and promotes antiviral effects, forming the first line of defense against viruses. Numerous studies have investigated the use of herbal medicine candidates as immunomodulators or antivirals. However, cytokine-storm-targeted therapy is recommended for patients with acute respiratory distress syndrome caused by SARS-CoV to survive severe pulmonary failure. Our reviews have demonstrated that herbal formulations could serve as alternative medicines and significantly reduce complicated viral infections. Furthermore, they hold promising potential as specific antiviral agents in experimental animal models.
An Overview of Biosynthetic Pathway and Therapeutic Potential of Rutin
Authors: Goyal Jugnu , Verma Prabhakar Kumar
Published: January 2023

Flavonoids are compounds abundantly found in nature and known as a polyphenolic group
of compounds having flavancore and show the utmost abundant collection of complexes and are
found in fiber-rich root vegetables, fruits, and their eatable items. Due to the presence of hydroxyl
groups, flavonoids show various therapeutic activities like antioxidant, antibacterial, antiviral, and
anti-inflammatory. Substituent groups are responsible for the onset of biochemical actions of flavonoids,
which affect the metabolism. The major example of flavonol is rutin, which is constituted of
rutinose and quercetin. It is a glycosidic type of flavonoid, similarly identified as purple quercitrin and
Vitamin P with over 70 plant species and plant-derived foods, exclusively grapefruit, buckwheat
seeds, cherries, apricots, grapes, onions, plums, and oranges. Another name forrutin is a citrus flavonoid
known as rutoside, and sophorin. Rutin is a polyphenolic compound having a low molecular
weight.
In silico Identification of HDAC Inhibitors for Multiple Myeloma: A
Structure-based Virtual Screening, Drug Likeness, ADMET Profiling,
Molecular Docking, and Molecular Dynamics Simulation Study
Authors: Debnath Abhijit , Mazumder Rupa , Mazumder Avijit , Singh Rajesh , Srivastava Shikha
Published: January 2023

Background:

Multiple myeloma (MM) is a hematological malignancy of plasma cells that
produce a monoclonal immunoglobulin protein. Despite significant advances in the treatment of MM,
currently available therapies are associated with toxicity and resistance. As a result, there is an increasing
demand for novel, effective therapeutics. Inhibition of histone deacetylases (HDACs) is emerging as a
potential method for treating cancer. HDAC6 is one of 18 different HDAC isoforms that regulate tubulin
lysine 40 and function in the microtubule network. HDAC6 participates in tumorigenesis and metastasis
through protein ubiquitination, tubulin, and Hsp90. Several studies have found that inhibiting HDAC6
causes AKT and ERK dephosphorylation, which leads to decreased cell proliferation and promotes cancer
cell death via the PI3K/AKT and MAPK/ERK signaling pathways.

Objective:

The objective of this study is to target HDAC6 and identify potent inhibitors for the treatment
of multiple myeloma by employing computer-aided drug design.

Materials and Methods:

A total of 199,611,439 molecules from five different chemical databases, such
as CHEMBL25, ChemSpace, Mcule, MolPort, and ZINC, have been screened against HDAC6 by structure-
based virtual screening, followed by filtering for various drug-likeness, ADME, toxicity, consensus
molecular docking, and 100 ns MD simulation.

Results:

Our research work resulted in three molecules that have shown strong binding affinity
(CHEMBL2425964 -9.99 kcal/mol, CHEMBL2425966 -9.89 kcal/mol, and CSC067477144 -9.86
kcal/mol) at the active site HDAC6, along with effective ADME properties, low toxicity, and high stability.
Inhibiting HDAC6 with these identified molecules will induce AKT and ERK dephosphorylation
linked to reduced cell proliferation and promote cancer cell death.

Conclusion:

CHEMBL2425964, CHEMBL2425966, and CSC067477144 could be effective against multiple
myeloma.
Pituitary Adenoma with Multiple Calcifications in a Child: A Rare Case
Presentation
Authors: Wang Juan , Zhao Xinyu , Zhang Wei
Published: January 2023

Introduction:

Pediatric pituitary adenomas are rare, resulting in a limited amount of literature
on these patients. The incidence of calcification in adult patients with pituitary adenomas is only
0.2% to 8%, while the incidence of calcification in children has not been reported.

Case Report:

In this paper, we report a 10-year-old girl with a calcified pituitary adenoma. Laboratory
examination showed the growth hormone (GH) to be more than 50ug/L, and pituitary prolactin (PRL)
was 27.42 ng/mL. Non-contrast-enhanced computed tomography (CT) scans indicated a large sellar
occupation with multiple nodules of calcification. Subsequently, the patient underwent a transcranial
resection. Histopathologic evaluation confirmed the diagnosis of pituitary adenoma with multiple calcifications.

Conclusion:

Since the management and prognosis of adenomas with calcification from other occupations
of the pituitary gland differ significantly, it is important to differentiate between the two.
One-step Nonenzymatic Electrochemical Sensor for the Detection of
Sarcosine Using Nanozyme Glutathione Copper Complex
Authors: Udayakumar Janani , Selvaraj Stalin
Published: January 2023

Background:

The present study aims to develop the use of glutathione copper complex for the
detection of sarcosine, a marker for prostate cancer. The glutathione-copper complex was successfully
synthesized at room temperature and characterized using FTIR, UV, and Scanning Electron Micrograph.

Methods:

The structure of the glutathione copper complex was found to be a 1:2 Metal: Ligand ratio. The
cyclic voltammogram for the glutathione-copper complex modified electrode showed an oxidation peak
around -0.037 V, which indicates the irreversible oxidation of copper ions. The addition of sarcosine decreased
the oxidation potential of the glutathione copper complex indicating the ability of the working
electrode, for the detection of sarcosine in the sample using differential pulse voltammetry.

Results:

The results indicated that the glutathione-copper complex modified electrode revealed good sensitivity,
selectivity, and linearity against the detection of sarcosine in the range from 0.1 μM to 2.5 μM.
The LOD and LOQ were calculated using a linear prediction model, the data obtained from differential
pulse voltammetry technique for known and simulated urine samples was 0.72 μM, 5.13 μM, and 1.45
μM, 39.94 μM, respectively. The sensitivity for the developed working electrode obtained for the known
and simulated sample was 0.0567 μA/μM and 0.02913 μA/μM, respectively.

Conclusion:

Thus, we concluded that the glutathione copper complex decorated glassy carbon electrode
is a good candidate for the detection of sarcosine with good selectivity and sensitivity for real-time monitoring.
Seed Oils in Treatment of Skin Aging and Photoaging
Authors: Kothapalli Lata , Raut Vaidehi , Thomas Asha
Published: January 2023

Background:

Seed oils have been exploited for an array of purposes with their addition
to dietary, cosmetics, or therapeutic products. The process of skin aging is a natural and complex
phenomenon in living beings. Skin aging is classified into two independent processes, i.e., chronological
aging and premature aging. Aging is observed as a loss of strength and elasticity of the skin,
leading to wrinkles on the skin. It is due to a decrease in various components of the skin matrix,
like elastin, collagen, and hyaluronic acid. Furthermore, aging is potentiated by excessive exposure
to UV radiation (Photoaging) and can be prevented or reduced by using products that combat photoaging.

Objective:

Anti-aging and antiwrinkle agents are in demand for maintaining skin tone. Seed oils
composed of polyunsaturated fatty acids are traditionally used in cosmetic products as moisturizers
and emollients, while palmitic acid and oleic acid are known for their penetration-enhancing effect.
With the changing trend for extraction of oils like cold pressed methods, seed oils enriched with
polyphenols, flavonoids, carotenoids, and phytosterols are good antioxidants and antimicrobials
and therefore have an ever-growing demand for their usage in the treatment of skin diseases. In this
review, an attempt will be made to brief the phytoconstituents present in various seed oils and their
utilization against skin ailments. Furthermore, a mechanistic approach towards the benefit of oils in
skin barrier repair, antiaging, and photo-aging with the help of extensive well-designed clinical trials
carried out in the recent past is elaborated.

Methods:

A literature search in the Scopus database, Pubmed, and Medline was carried out using
the terminology “aging, photoaging, antioxidant, UV-protection, sunscreens, skin barrier repair,
and fatty acids, formulations” in the study. Data were retrieved over the last twenty years.

Results:

The review summarises the mechanistic approach and beneficial application of seed oils
for healthy and glowing skin. The oils obtained from olives, sesame, borage, grape seeds, and carrot
seeds have multitargeted effects. However, the variation in pharmacological effect may vary
based on geographically differing varieties, skin type, and person-to-person variation. The need to
standardize the varieties for their phytoactive ingredients and the composition of formulation used
for skin care can help utilize the seeds as a potential source of actives against skin diseases.

Conclusion:

The potential of seed oils can be increased with appropriate analytical tools, validation
protocols, and systematic experimental studies at preclinical and clinical trials for their application
to skin care products.
Comparación del desempeño sísmico de un puente continuo utilizando aisladores del tipo elastomérico y friccional deslizante
Authors: Trejo-Rodriguez Cristopher Manuel , Melchor Placencia Carlos Javier
Published: January 2023

El notable comportamiento de los puentes sísmicamente aislados en Sudamérica durante los dos últimos grandes eventos sísmicos, se ha visto reflejado en el aumento del uso de aisladores de base en este tipo de infraestructuras. En este trabajo, un puente no aislado de varios tramos fue reacondicionado para alcanzar una funcionalidad continua mediante la adopción de dispositivos de aislamiento sísmico. Con el objetivo de realizar una evaluación comparativa, se analizó el puente utilizando dispositivos de aislación del tipo elastomérico y deslizante. En este caso de estudio se escogió el aislador Elastomérico con Núcleo de Plomo (LRB) y el aislador Friccional de Triple Péndulo (TFPB) como modelos representativos. Para el diseño de ambos aisladores, se consideró que los valores de los periodos aislados, la rigidez post-fluencia y la fuerza de fluencia sean similares. Este criterio se adoptó con el fin de comparar los efectos únicos de cada tipo de aislador en la respuesta sísmica del puente. Se realizaron una serie de análisis dinámicos no lineales considerando las dos componentes del movimiento horizontal del suelo para realizar una evaluación comparativa. Se adoptaron modelos numéricos que consideran la respuesta bidireccional y describan las diferentes etapas de movimiento de los aisladores. Se consideraron análisis de límites superiores e inferiores para obtener una comprensión completa de la respuesta inducida por cada sistema de aislamiento. De los resultados, se concluye que el sistema LRB induce una distribución más uniforme de las fuerzas sísmicas en la subestructura; pero experimenta mayores desplazamientos en comparación con el sistema TFPB.
Evaluación de la vulnerabilidad sísmica del puente de carretera "Moche" ubicado en la carretera nacional pe1n usando el método de espectro de capacidad
Authors: Escudero Alcantara Jonathan Gianpatrick , Segura Guzman Laruz Amaliz , Gresia Munayco Juana Eva
Published: January 2023

In active seismic zones, such as the Peruvian coast, tools for predicting the potential negative impacts of earthquakes are essential for planning mitigation, emergency, and recovery of transportation facilities. For instance, the capacity of a road bridge network after a seismic event to carry traffic flow depends on the degree of expected damage and the related repair costs and downtime. This paper determines the degree of vulnerability of highway bridges to the action of probable earthquakes during the structure's lifetime by applying the capacity spectrum assessment method known as FRACAS (FRAgility through CApacity Spectrum assessment). This approach allows fragility curves to be obtained from analyzing a structure subjected to a series of seismic records of different characteristics. In this way, the method can explain the effect of variability in seismic demand and structural characteristics on the damage statistics simulated for the type of structure and evaluate the associated uncertainty in predicting fragility. As a case study, it is applied the methodology described in the evaluation of the Moche bridge, located in the region of La Libertad (Peruvian coast), which is in an Operational damage state according to an in situ inspection. From the seismic vulnerability assessment, it is obtained that until earthquakes with accelerations of 1.7g, the Moche bridge has a 60% probability of incursion into a Life Safety damage state, being the probability of incursion into a Collapse damage state less than 10%. This methodology is recommended to determine the reliability of bridges, considering the cumulative damage due to probable seismic events during the bridges' lifetime.
Evaluación del monitoreo de la salud estructural en el hospital Edgardo Rebagliati Martins con un número limitado de acelerómetros en la ciudad de Lima
Authors: Quispe Ccoyllo Ricardo , Diaz Figueroa Miguel Augusto , Jaramillo del Aguila Joseph Darwin , Inocente Flores Italo Alonso
Published: January 2023

Structural Health Monitoring (SHM) allows assessing the structural damage in observed buildings through different methodologies, which observe changes in the structural behavior immediately after an earthquake. Some methodologies assess the structural damage by observing its global capacity curve obtained through the displacement and acceleration in all stories, calculated using wavelet transform and double integration process. Due to limited resources, some floors are instrumented, and non-instrumented stories response could be estimated by additional procedures, for instance the spline shape function. In this paper, different arrangements of sensors in the Edgardo Rebagliati Martins Hospital (HERM) are evaluated to find the best possible configuration to estimate the global capacity curve and the interstories capacity curves. A 14-story building in the HERM is analyzed, and the optimal arrangement to estimate the capacity curve for each interstory capacity curve was using 7 sensors, and 4 sensors were sufficient to estimate the global capacity curve of this building.
Electrical resistance of Ni-=SUB=-42+x-=/SUB=-Mn-=SUB=-47-x-=/SUB=-Sn-=SUB=-11-=/SUB=- alloys
Authors: Volkova N. V.  , Chistyakov V. V.  , Patrakov E. I.  , Korenistov P. S.  , Perevalova A. N.  , Emelyanova S. M.
Published: January 2023

The electrical resistance and structure of Ni42+xMn47-xSn11 alloys have been studied; where x=0, 1, 2, 3, 4, At room temperature, Ni42+xMn47-xSn11 alloys are ordered in the cubic L21 Ni2MnSn structure characteristic of Heusler alloys. The phase transition between the cubic austenite phase and martensite with lower symmetry, characteristic of ferromagnetic non-stoichiometric Heusler alloys, is observed at temperatures below room temperature. It was found that the partial replacement of Mn atoms by Ni atoms leads to an increase in the phase transition temperatures and to their shift to room temperature. Keywords: Heusler alloys, electrical resistance, phase transition.
Magnetic properties of nanocrystalline material based on Bi-=SUB=-2-=/SUB=-Fe-=SUB=-4-=/SUB=-O-=SUB=-9-=/SUB=-
Authors: Buryanenko I. V.  , Semenov V. G.  , Lomanova N. A.  , Osipov A. V.  , Volkov M. P.  , Pleshakov I. V.
Published: January 2023

The magnetic characteristics of a nanocrystalline material based on bismuth ferrite Bi2Fe4O9 with 60±3 nm crystallites were studied. The obtained material demonstrates unusual magnetic properties, which are manifested in a significant increase in the value of magnetization in comparison with the data known from other works. Keywords: nanocrystals, bismuth ferrite, mullite, magnetic properties.
Phase transitions in the diluted 2D three-state Potts model on a square lattice
Authors: Murtazaev A. K.  , Babaev A. B.  , Ataeva G. Ya.  , Babaev M. A.
Published: January 2023

The computer simulation method was used to study phase transitions in a two-dimensional site-diluted 3-state Potts model. Systems with linear dimensions Lx L=N, L=10/160 at a spin concentration p=1.00, 0.80 are considered. The numerical data obtained indicate that in a pure 3-state Potts model on a square lattice, a phase transition of the second order is observed in accordance with the theory. The introduction of disorder in the form of non-magnetic impurities (p=0.80) in the 3-state Potts model preserves the phase transition of the second order. Keywords: Potts model, Monte Carlo method, thermodynamic parameters, disorder.
Resonant dynamics of the magnetization of uniaxial nanoparticle
Authors: Shytyi. A.M.  , Vasilevskaya T. M.  , Sementsov  D. I.
Published: January 2023

Analysis of equilibrium conditions was carried out and resonant precessional dynamics of magnetization of a single-domain magnetically uniaxial ellipsoidal particle. Considered the case when magnetic field is along the easy magnetization axis. the easy magnetization axis is directed parallel to the axis of symmetry of the ellipsoid and transverse to pumping by a weak high-frequency field. Features of the behavior of the magnetization were discovered. It has been revealed that the magnetization has features of resonant behavior: large resonant precession angles with amplitude 0.5M0, elliptical deviations of the precession trajectory from circular at a negative value of the effective anisotropy field, and the presence of a frequency region with nonlinear precession for an oblate nanoparticle. Keywords: ferromagnetic resonance, elliptical nanoparticles, transverse bias field, effective anisotropy, bistability, easy magnetization axis, nonlinear effects.
Structural and Dielectric Properties of Bi-=SUB=-3-=/SUB=-Ti-=SUB=-1.5-=/SUB=-W-=SUB=-0.5-=/SUB=-O-=SUB=-9-=/SUB=-
Authors: Zubkov S. V.  , Parinov I. A.  , Kuprin Yu. A.  , Nazarenko A. V.
Published: January 2023

Layered perovskite-like oxide Bi3Ti1.5W0.5O9 has been synthesized by the method of high-temperature solid-state reaction. The X-ray diffraction study showed that the compound is single-phase and has the structure of the family of Aurivillius phases (AP) with parameters close to the orthorhombic unit cell corresponding to the space group A21am. The temperature dependences of the relative permittivity ε/ε0 and the loss tangent tgsigma are measured at different frequencies. For the synthesized compound, the piezoelectric modulus d33 was measured. The microstructure of Bi3Ti1.5W0.5O9 has been obtained. Keywords: Aurivillius phases, Bi3Ti1.5W0.5O9, activation energy Ea, Curie temperature TC, piezoelectric modulus d33.
Structure, dielectric and ferroelectric properties of Ba-=SUB=-2-=/SUB=-NdFeNb-=SUB=-4-=/SUB=-O-=SUB=-15-=/SUB=- multiferroic thin films
Authors: Pavlenko A. V.  , Ilina T. S.  , Kiselev D. A.  , Stryukov D. V.  , Ochkurov M. V.
Published: January 2023

The phase composition, nanostructure, and properties of Ba2NdFeNb4O15 multiferroic thin films are studied by X-ray diffraction, dielectric spectroscopy, methods for analyzing ferroelectric properties, and scanning probe microscopy. Films were grown on the single-crystal Pt/MgO(001) substrate by a one-stage RF cathode sputtering technique in an oxygen atmosphere. It has been established that the Ba2NdFeNb4O15 films are single-phase, impurity-free, and c-oriented, which made it possible to study their dielectric properties along the polar direction. tensile deformation of the unit cell (1.35% along the polar axis) has found in the films, which led to the realization of the ferroelectric phase in the BNFNO film at room temperature. The revealed dependencies and the prospects for using this material in the nanosized thin films form are discussed. Keywords: multiferroic, dielectric characteristics, ferroelectric, tetragonal tungsten bronze.
Structure and properties of Co-=SUB=-x-=/SUB=-Mn-=SUB=-1-x-=/SUB=-Fe-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- nanoparticles depending on the amount of Co ions (0≤ x≤ 1.0)
Authors: Kamzin A. S.  , Obaidat  I. M.  , Semenov V. G.  , Narayanaswamy V.  , Al-Omari I. A.  , Issa B.  , Buryanenko I. V.
Published: January 2023

The properties of magnetic nanoparticles (MNPs) of spinel ferrites CoxMn1-xFe2O4 (at x=0.0; 0.2; 0.3; 0.4; 0.5; 0.6; 0.8; 1.0) synthesized by chemical co-precipitation method have been studied. The studies of the synthesized CoxMn1-xFe2O4 MNPs were carried out using X-ray diffraction (XRD), Raman scattering and Mossbauer spectroscopy. The results of XRD, Raman and Mossbaur studies indicate that the obtained CoxMn1-xFe2O4 MNPs are single-phase. It was established from XRD measurements that the average size of CoxMn1-xFe2O4 crystallites is 34.86 nm for MnFe2O4 (x=0) and decreases to 14.99 nm for CoFe2O4 (x=1.0) with increasing Co ions concentration. An analysis of the Mossbaur spectra showed that the average crystallite size varies from 25 nm for MnFe2O4 (x=0) to 12 nm for CoFe2O4 (x=1.0). On the Raman spectra of CoxMn1-xFe2O4 MNPs, in the region of ~620 cm-1, splitting of the A1g line is observed, which means that the studied MNPs have a reverse spinel structure. The intensity ratio of the A1g (1) and A1g (2) peaks indicates a significant redistribution of the Co2+ and Fe3+ cations between tetra- and octahedralpositions in MNPs of the CoxMn1-xFe2O4 ferrite, which is confirmed by Mossbauer data. Mossbaur spectroscopy data indicate that the synthesized CoxMn1-xFe2O4 MNPs consist of large particles with magnetic ordering and small particles in the paramagnetic phase. With an increase in the concentration of Mn ions, the proportion of fine particles increases, which leads to a decrease in the magnetic blocking temperature. The saturation magnetization of MNPs at x=0.2 (Co0.2Mn0.8Fe2O4) is 57.41 emu/g and this sample, as was found in [V. Narayanaswamy, I.A. Al-Omari, A.S. Kamzin, B. Issa, H.O. Tekin, H. Khourshid, H. Kumar, A. Mallya, S. Sambasivam, I.M. Obaidat. Nanomaterials 11, 1231 (2021)] has the highest specific absorption rate. As shown by Mossbauer studies, this is due to the fact that these particles are in a superparamagnetic state and the magnetic blocking temperature of these MNPs is in the region of ~315 K, which is most suitable for the treatment of malignant tumors by magnetic hyperthermia. Thus, the synthesized CoxMn1-xFe2O4 MNPs are promising for biomedical applications. Keywords: spinel ferrites CoxMn1-xFe2O4, magnetic structure, superparamagnetism, Mossbauer spectroscopy, materials for biomedicine.
Energy Spectrum and Optical Absorption Spectrum of exohedral Fullerene C-=SUB=-50-=/SUB=-Cl-=SUB=-10-=/SUB=- within the Hubbard Model
Authors: Silant'ev A. V.
Published: January 2023

Energy spectra of fullerene C50 and exohedral fullerene C50Cl10 with the D5h symmetry groups have been obtained within the Hubbard model and static fluctuation approximation. The energy states have been classified using the methods of group theory, and the allowed transitions in the energy spectra of molecules C50 and C50Cl10 have been determined. On the basis of the energy spectrum of exohedral fullerene C50Cl10 is given an interpretation of experimentally observed optical absorption bands molecule C50Cl10. Keywords: Hubbard model, Green's functions, energy spectrum, fullerenes, nanosystems, fullerene C50, exohedral fullerene C50Cl10.
Study of GaAs epitaxial growth on Si substrates modified by focused ion beams
Authors: Balakirev S. V.  , Eremenko M. M.  , Lakhina E. A.  , Kirichenko D. V.  , Shandyba N. A.  , Chernenko N. E.  , Ageev O. A.  , Solodovnik M. S.
Published: January 2023

In this paper, we present a study of the effect of the silicon substrate modification by focused ion beams on subsequent growth of GaAs layers by molecular beam epitaxy. We demonstrate that when samples exposed to the ion irradiation at various accelerating voltages and ion beam passes are annealed in the absence of the arsenic flux, an increase in the depth of the modified Si substrate areas occurs. At the same time, crystallization of gallium accumulations during annealing in the arsenic flux leads to the filling of holes formed during the ion bombardment. We reveal that the growth of GaAs on substrates with areas modified at an accelerating voltage of 30 kV and subjected to subsequent annealing in the arsenic flux at a temperature of 600oC is accompanied by the formation of nanowires, the density of which increases within areas with a large number of ion beam passes. The results of the conducted research can be used for the development of technological approaches to the formation of GaAs epitaxial layers on Si substrates. Keywords: molecular beam epitaxy, monolithic integration, gallium arsenide, silicon, focused ion beams.
Modeling of fracture and acoustic emission in polycrystalline solids with the discrete elements method
Authors: Hilarov V.L.  , Damaskinskaya E. E.
Published: January 2023

The discrete element method (DEM) is used to reveal the main features of the fracture in materials with different degree of heterogeneity. It is shown that this method adequately describes the main properties of materials in the fracture process such as brittle and ductile behavior, two-staged nature of fracture in heterogeneous materials, heterogeneity of the spatial distribution of local internal stresses depending on the degree of heterogeneity. Keywords: discrete element method, fracture of heterogeneous materials, computer modelling.
Influence of Strain Rate on the Effect of Plasticization of High-Strength Ultrafine-Grained Al-Cu-Zr Alloy
Authors: Sadykov D. I.  , Orlova T. S.  , Murashkin M. Yu.
Published: January 2023

The influence of the strain rate on the plasticization effect (PE) of ultrafine-grained (UFG) Al-1.47Cu-0.34Zr (wt%) alloy structured by high pressure torsion. A significant increase in plasticity (more than 2 times) while maintaining a high level of strength (ultimate tensile strength ~465 MPa) in the UFG alloy was achieved as a result of additional deformation-heat treatment (DHT), consisting of low-temperature annealing and a small additional deformation. It is shown that the PE after DHT is retained when the strain rate changes from 10-4 to 10-3 s-1 and decreases by half with its further increase to 10-2 s-1. The values of the strain-rate sensitivity coefficient for the UFG Al-1.47Cu-0.34Zr (wt%) alloy were determined in both states before and after DHT. Possible reasons of the PE suppression at high strain rates (≥10-2 s-1) are discussed. Keywords: aluminum alloys, severe plastic deformation, ultrafine-grained structure, strength, plasticity, strain-rate sensitivity.
Structure Analysis, Photoluminescence, and Non-linear/Linear Optical Parameters of Li-=SUB=-2-=/SUB=-Ge-=SUB=-4-=/SUB=-O-=SUB=-9-=/SUB=- : Mn-=SUP=-4+-=/SUP=- Transparent Glass-Ceramic
Authors: Morad I.  , Liu  X.  , Elhosiny  Ali H  , El-Desoky  M. M.  , Qiu  J.
Published: January 2023

In this study, Li2Ge4O9 : Mn4+ transparent glass-ceramic was prepared by conventional melt-quenching. The thermal treatment was used for the devitrification of the sample. The creation of a Li2Ge4O9 nanocrystalline precipitated through the glass matrix was verified by X-ray diffraction and HR-TEM. Electron paramagnetic resonance spectra were employed to confirm the oxidation of Mn2+ to Mn4+ in glass-ceramic after thermal treatment. The photoluminescence spectra displayed a narrow red band centered at 668 nm ascribed to the spin-forbidden 4Eg->4A2g transition of Mn4+. To estimate the optical parameters, UV-Vis-IR absorption spectroscopies were measured. The red shift of the direct optical band gap Eoptg, from 3.81 to 2.55 eV, was observed by increasing the Mn4+ concentration. The dispersion parameters, refraction indices (n, nбесконечность), and oscillator wavelength (λ0) were examined by using Wemple--DiDomenico single-oscillator model. The relationship between the refractive index and the energy gap has been investigated using various models such as Moss, Herve--Vandamme, Ravindra, and Singh--Kumar. In addition, the linear and non-linear optical properties of Li2Ge4O9 : Mn4+ were mentioned. The temperature-dependent luminescence intensity measurement was also carried out. The method of preparation exposed herein for the synthesis of Mn4+-doped GCs might be prevailing to produce identical luminescent ceramics in accordance with the glass's devitrification. Keywords: glass-ceramics, photoluminescence, optical properties, non-linear/linear optical, dispersion parameters, energy gap
Structure and magnetic properties of amorphous and nanocrystalline Co-Fe-B-(Nb, Ti) alloys
Authors: Chirkova V. V.  , Volkov N. A.  , Sholin I. A.  , Abrosimova G. E.  , Aronin A. S.
Published: January 2023

The structure and magnetic properties of amorphous and nanocrystalline Co56Fe16B20X8 (X=Nb, Ti) alloys have been studied by X-ray diffraction and vibrating sample magnetometry. It is shown that the saturation magnetization of the amorphous Co56Fe16B20Ti8 alloy is higher than that of the Co56Fe16B20Ti8 alloy. The temperature dependence of the saturation magnetization of amorphous alloys is measured and it is shown that the saturation magnetization of the Co56Fe16B20Ti8 alloy decreases with temperature more slowly than the magnetization of the Co56Fe16B20Nb8 alloy. Crystallization of amorphous alloys leads to a decrease in the saturation magnetization of both alloys. During crystallization, BCC nanocrystals are formed in the Co56Fe16B20Nb8 alloy and multiphase structure is formed in the Co56Fe16B20Ti8 alloy. Keywords: amorphous phase, crystallization, nanocrystals, magnetic properties.
Linear coefficient of thermal expansion and Debye temperature of PbTe at high temperatures
Authors: Sharov M. K.
Published: January 2023

The linear coefficient of thermal expansion and the Debye temperature of PbTe in the high-temperature range have been investigated using X-ray diffractometry. The studies were carried out on samples of two types: single crystal and PbTe powder, synthesized separately. Both types of samples showed fairly similar results in all measurements. It has been established that in the temperature range 293-773 K the linear thermal expansion coefficient is constant and for powder: α=20.1· 10-6± 0.9· 10-6 K-1 and for single crystal: α=19.7· 10-6± 0.8· 10-6 K-1. The Debye temperature measured in the temperature range 293-573 K equal to 105±3 K Keywords: lead telluride, linear thermal expansion coefficient, Debye temperature.
Effect of oxygen content "stabilization" in La-=SUB=-0.8-=/SUB=-Sr-=SUB=-0.2-=/SUB=-MnO-=SUB=-3-delta-=/SUB=- films at post annealing in air
Authors: Nikolaenko Yu.M.  , Efros N.B.  , Fedyuk D.O.  , Reshidova I.Yu.
Published: January 2023

The variation of oxygen content in the epitaxial La0.8Sr0.2MnO3-delta films of 12-75 nm thick onto NdGaO3 substrates was quantitatively investigated by indirect method during heat treatment procedure in air at temperature range 873-1073 K. The experimental time dependences of oxygen content variation were investigated theoretically with taking into account the effect of inhomogeneous diffusion of oxygen over the films thickness to provide optimal choice of temperature and duration of the heat treatment procedure. In films 25-75 nm thick, the effect of "stabilization" of the oxygen content (OC = 3) is revealed, which indicates the presence of an energy barrier that prevents the incorporation of an excess oxygen atom into the near-surface layer of the film at optimal conditions of heat treatment. Keywords: epitaxial films, strain, oxygen index, non-uniform oxygen diffusion.
Phase transition of quantum spin liquid in La-=SUB=-0.15-=/SUB=-Sm-=SUB=-0.85-=/SUB=-MnO-=SUB=-3+delta-=/SUB=- in weak magnetic field tochiral state with topological order during sample magnetization reversal
Authors:  Bukhanko F. N.  ,  Bukhanko A. F.
Published: January 2023

In this work, a detailed study of the nature of phase transitions in the Z2 quantum spin liquid in La La0.15Sm0.85MnO3+delta manganites induced at a temperature of 4.2 K by a weak external dc magnetic field in the ZFC and FC regimesof measuring the field dependences of the magnetization in the field range of ± 5 kOe is carried out. It is shown that during the magnetization reversal of the sample in the ZFC-regime near the external magnetic field H=0, a second-order phase transition Z2 quantum spin liquid occurs in the state of a chiral gap quantum spin liquid with a topological order. The transition is accompanied by an unusual hump-like increase in the number of magnetic excitations in the form of Majorana fermions and local gauge Z2 magnetic fluxes in the range of fields ± 500 Oe near zero field. A characteristic feature of the magnetization features is their strong dependence on the direction of growth of the external magnetic field, which is accompanied by the breakingof the mirror symmetry of the sample magnetization upon reversal of the sign of the external magnetic field, which is typical for the Z2 chiral state of a quantum spin liquid. In the FC-measurementregime, characteristic signs of excitation-destruction of 1D-fragments of gapless charge/spin density waves were found near H=0 during sample magnetization reversal due to confinement-deconfinement of spinon pairs in a system of spin chains. Keywords: chiral quantum spin liquid, Majorana fermions, confinement-deconfinement of spinon pairs, 1D-charge/spin density waves.
Luminescence of Hf-=SUB=-x-=/SUB=-Zr-=SUB=-1-x-=/SUB=-O-=SUB=-2-=/SUB=- thin films upon excitation with vacuum ultraviolet synchrotron radiation
Authors: Pustovarov V. A.  , Gritsenko V. A.  , Islamov D. R.
Published: January 2023

Using the methods of low-temperature luminescence spectroscopy and vacuum ultraviolet synchrotron radiation (MAX IV synchrotron, Lund, Sweden), charge transfer processes and the nature of charge carrier traps responsible for leakage currents in nanometer dielectric films of hafnium-zirconium-oxygen HfxZr1-xO2 solid solutions on silicon substrate, as well as in films doped with La-ions and annealed in argon atmosphere. The photoluminescence spectra, photoluminescence excitation spectra of the 2.7 eV emission band and previous simulation data within the framework of density functional theory confirm the presence of an oxygen vacancy in the studied films. Based on the study of competing channels for the relaxation of electronic excitations due to the radiative decay of self-trapped excitons (4.35 eV emission band) and the luminescence of defects (2.7 and 3.5 eV emission bands), a conclusion was made about the efficiency of transport and capture of excitons and separate charge carriers in films with varying degrees of defectiveness and films doped with lanthanum. The obtained data confirm the conclusion that oxygen vacancies are traps responsible for leakage currents in the films under study Keywords: Luminescence, synchrotron radiation, defects, energy transfer.
Combine XPS- and AFM Study of Silicon Oxide Film with Zinc Impurity for ReRAM Devices
Authors: Privezentsev V. V.  , Sergeev A. P.  , Firsov A. A.  , Kiselev D. A.
Published: January 2023

The composition, structure and properties, as well as the current-voltage characteristics of a layered structure consisting of two 50 nm thick amorphous SiO2 films deposited by electron beam evaporation, between which a Zn film with a thickness that varied from 100 nm to 50 nm was deposited. Then these structures were annealed in air in the temperature range from 300 up to 400oC with a step of 50oC for 30 min. Planar electrodes with different configuration were used. They were made from gold, platinum and aluminum. It was found that after deposition on the sample surface, a granular structure with a grain size of 50-100 nm of SiO2 composition was formed. After annealing at 400oC, the sample roughness decreases from 25 nm after deposition to 10 nm, and the grain size in plan increases to 100-200 nm. For films annealed at 400oC the current-voltage characteristics with hysteresis were obtained. Keywords: silicon oxide film, zinc impurity, electron beam evaporation, annealing, nanoclusters, ZnO.
X-ray photoelectron spectroscopy of ytterbium nanofilms with oxygen adsorbed on their surface
Authors: Kuzmin M.V.  , Mittsev M.A.
Published: January 2023

X-ray photoelectron spectra of nanoscale-thickness ytterbium films along with adsorbed oxygen layers have been studied for the first time. It is found that the spectra include features from both divalent and trivalent ytterbium. The intensity ratio of these features raises upon increasing the film thickness (the size effect). It is shown that the above behavior is due to the formation of two final states related to divalent and trivalent ytterbium at the photoionization of 4f-level by photons with the energy of 1253.6 eV, while only the trivalent state is realized by using the photons with the energy of 142 eV. Keywords: Ytterbium, nanofilms, adsorbed molecules, electronic state, X-ray photoelectron spectroscopy.
Features of the low-temperature conductivity of organometallic perovskite films with the introduction of graphene oxide particles into them
Authors: Ovezov M. K.  , Aleshin P. A.  , Aleshin A. N.
Published: January 2023

The influence of the introduction of graphene oxide (GO) particles on the low-temperature conductivity of composite films based on organometallic perovskites CH3NH3PbBr3 with GO particles with a concentration of 0-5 wt.% has been studied. It has been established that the introduction of GO particles into ITO/CH3NH3PbBr3 : GO/ITO/glass films manifests itself in a decrease in the activation energy of the temperature dependence of the conductance. A sharp increase by 5-6 orders of magnitude of the resistance of the films at temperatures below 150 K was found. It is assumed that in the studied CH3NH3PbBr3 : GO systems at T>150 K, the hopping mechanism of transport predominates, associated with the capture and accumulation of charge carriers in GO particles, and the increase in resistance at T<150 K may be due to the structural phase transition characteristic of organometallic perovskites in this temperature range. Keywords: organometallic perovskites, graphene oxide, electrical conductivity, low-temperature transport.
The Effect of phonon focusing on the mutual drag of electrons and phonons and the electrical resistance of potassium
Authors: Kuleyev I. G.  , Kuleyev I. I.
Published: January 2023

The effect influence of elastic energy anisotropy on the mutual drag of electrons and phonons and the electrical resistance of potassium crystals at low temperatures have investigated. We have analyzed the momentum exchange between the electron and three phonon flows corresponding to three branches of the vibrational spectrum in the hydrodynamic approximation. The actual mechanisms of phonon momentum relaxation have taken into account: scattering at sample boundaries, dislocations, and in the processes of phonon-phonon transfer. It have shown that in the limiting case of strong mutual drag of electrons and phonons, the electrical resistance will be much lower than that given by the Bloch--Gruneisen theory, and the phonon and electron drift velocities are close and they are determined by the total phonon relaxation rate in resistive scattering processes. In the opposite case, when resistive scattering processes dominate for phonons and the phonon system remains in equilibrium, then the electrical resistance follows the Bloch--Gruneisen theory. In this case, the drift velocities of all modes are different and much less than the electron drift velocity. Keywords: electrical resistance, elastic anisotropy, electron-phonon relaxation.