bluuebunny/crossref_metadata_2025 huggingface dataset:
La práctica pedagógica en educación superior: una mirada desde los actores de la carrera de Educación Inicial (UNAE- Ecuador)
Authors:   Universidad Nacional de Educación, Saldaña Gómez Diana , González González Lorena ,   Ministerio de Educación del Ecuador
Published: August 2022

La presente investigación da a conocer la percepción y valoración crítica del proceso de la práctica pedagógica en el nivel de educación superior, desde la mirada de diecinueve estudiantes, diez docentes de aula de centros educativos y seis tutores académicos universitarios. Este estudio de tipo cualitativo se basó en las técnicas de observación y Focus Group, la última organizada en cuatro grupos según su rol; la información obtenida en cada uno de los encuentros fue analizada, sistematizada y contrastada con los datos de la observación realizada durante el primer quimestre del año lectivo 2019-2020, en dos instituciones de la ciudad de Azogues, provincia del Cañar (Ecuador), realizada por estudiantes de último ciclo de la carrera de Educación Inicial de la Universidad Nacional de Educación (UNAE). Los resultados se presentan desde las diferentes perspectivas de los actores involucrados en este proceso, donde se evidencia la concepción de la práctica pedagógica, su valoración, interacciones, aprendizajes y aspectos tanto positivos como negativos. La investigación concluye que el proceso de práctica es una oportunidad para que el estudiante se involucre, conozca, prepare y experimente sobre la base de la reflexión y acción de las experiencias en el campo educativo, lo que le permite practicar la teoría mientras en las aulas de clase teoriza y planifica su práctica, de esta manera la formación académica se convierte en la base fundamental que germina y formula las ideas aplicables a una práctica que cumple con las expectativas de todos los actores de la comunidad educativa.
Applications of N-Halo Reagents in Multicomponent Reactions: A Still Underrated Approach for the Construction of Heterocyclic Scaffolds
Authors: de Andrade Vitor S.C. , de Mattos Marcio C.S.
Published: August 2022

Heterocyclic scaffolds are important from both academic and industrial points of view. Due to their biological and pharmacological activities, they are useful intermediates in organic synthesis and have great interest in medicinal and natural products chemistry. N-halo compounds bearing an electron-withdrawing group on nitrogen (e.g., carbonyl, sulfonyl) present the unique chemical properties of the N-X bond that give them broad synthetic utility for diverse organic transformation. In the past years, significant progress has been achieved in the synthesis of heterocyclic compounds with the intermediacy of N-halo compounds. Numerous strategies (e.g., electrophilic cyclizations, asymmetric halocyclizations, oxidative cyclizations, radical processes) were implemented featuring high atom- and step-economy, and more efficient procedures are continually being developed. An interesting approach consists of using Nhalo compounds to promote multicomponent reactions (MCRs), which rapidly became an emerging field in heterocyclic construction. MCRs are recognized for their mild conditions, high convergence, and efficiency. Thus, the present review will focus attention on the main topics and utilization of N-halo compounds (N-halosuccinimides, trihaloisocyanuric acids, N-halosulfonamides, etc.) as green and convenient reagents in heterocyclic construction via MCRs. Examples of the preparation of azoles, pyridines, 1,4-dihydropyridines, chromenes, and xanthenes, among other scaffolds are presented and discussed.
In Vitro Antioxidant, Anti-inflammatory, Antimicrobial, and Antidiabetic
Activities of Synthesized Chitosan-loaded p-Coumaric Acid Nanoparticles
Authors: Venkatesan Amalan , Samy Jose Vinoth Raja Antony , Balakrishnan Karthikeyan , Natesan Vijayakumar , Kim Sung-Jin
Published: August 2022

Background:

p-Coumaric acid is a phenolic compound widely distributed in fruits and
vegetables that displays an array of therapeutic properties, including antidiabetic effects. Prominent
application in diabetes is limited due to its suboptimal pharmacokinetics, poor aqueous solubility,
and poor bioavailability. Nanotechnology-based delivery methods have been developed to
address these limitations and improve the therapeutic uses of p-coumaric acid, and the nanoencapsulation
method is emerging as a feasible alternative.

Objective:

The objective of this study is to synthesize p-coumaric acid nanoparticles (PCNPs) and
to evaluate their in vitro activities.

Methods:

The PCNPs were synthesized by the nanoprecipitation method and characterized by
UV-visible spectroscopy, zeta potential, Fourier-transform infrared (FTIR) spectroscopy, and
scanning electron microscopy (SEM) with dispersive energy X-ray (EDX) analysis. In addition,
the PCNPs were analyzed for in vitro antioxidant activity using six different free radical scavenging
assays and were also analyzed for antimicrobial, anti-inflammatory, antithrombotic, and antidiabetic
effects.

Results:

The formation of PCNPs was confirmed by UV-visible spectra at 283 nm, and FTIR
analysis revealed the reduction and capping of the chitosan nanoparticles. SEM was used to assess
the size and shape of the PCNPs, and the high absorption property of the PCNPs was investigated
using EDX analysis. The PCNPs had significant antioxidant, hydrogen peroxide (H2O2), lipid peroxidation
(LPO), superoxide and nitric oxide (NO) radical scavenging power activities, and
showed potent antimicrobial, anti-inflammatory, antithrombotic, and antidiabetic activities.

Conclusion:

The present study suggests that PCNPs can be used as a potential medication delivery
approach to provide a greater nephroprotective effect in the treatment of diabetic nephropathy.
To the best of our knowledge, this is the first attempt at the synthesis of chitosan-loaded PCNPs.
Dynamic Changes of Carotid Atherosclerosis and Their Relation with
Stroke Recurrence in Patients with Stroke or Transient Ischemic Attack
Authors: Cho A-Hyun , Lim Eun-Ye
Published: August 2022

Background and purpose:

The purpose of this study was to show dynamic changes in
carotid and vertebral artery using carotid Doppler ultrasonography (DUS) through a long-term follow-
up exam, and determine their associations with stroke recurrence.

Methods:

We consecutively enrolled stroke or transient ischemic attack (TIA) patients who had
undergone DUS more than twice with intervals of three months or more. Stroke recurrence during
follow-up was also investigated by reviewing medical records. Progress or regress of plaque was
defined as more than 0.1 mm change from the initial scan with a semi-quantitative measurement.
The development of new plaque was also regarded as plaque progress. Increased intima-media
thickness and plaque presence were interpreted at the initial and follow-up scans. Factors related to
progression or regression were analyzed. The relationship between plaque change and stroke recurrence
was investigated.

Results:

A total of 201 patients were enrolled (186 ischemic stroke patients and 15 TIA patients).
There were 61 (30.3%) females. Their mean age was 64.2 ± 9.9 years. During a follow-up of 35.0 ±
22.6 (mean ± SD) months, plaque progress was observed in 92 (45.8%) and plaque regress in 13
(6.5%). Stroke recurred in 18 patients. Plaque progression showed no significant association with
age, risk factors, statin use, or subtype. After adjustment of age, sex, diabetes, and stroke subtype,
multiple logistic regression showed a significant association of plaque progression with stroke recurrence
(odds ratio: 3.8, 95% confidence interval: 1.1 to 13.1, p = 0.034). Patients with plaque regress
were significantly younger than those without plaque regress (57.8 years vs. 64.6 years, p = 0.041).

Conclusion:

Plaque progression occurred in 46% of stroke or TIA patients. Plaque progression was
significantly associated with clinical stroke recurrence. Plaque regressed in 6.5% of patients. Patients
with regression were younger than those without.
Comparing Medial Temporal Atrophy Between Early-Onset Semantic
Dementia and Early-Onset Alzheimer's Disease Using Voxel-Based Morphometry:
A Multicenter MRI Study
Authors: Kobayashi Ryota , Hayashi Hiroshi , Kawakatsu Shinobu , Shibuya Yuzuru , Morioka Daichi , Ohba Makoto , Yoshioka Masanori , Sakamoto Kazutaka , Kanoto Masafumi , Otani Koichi
Published: August 2022

Background:

Early-onset Semantic dementia (EOSD) and early-onset Alzheimer's disease (EOAD) are often difficult to clinically differentiate in the early stages of the diseases because of the overlaps of clinical symptoms such as language symptoms. We compared the degree of atrophy in medial temporal structures between the two types of dementia using the voxel-based specific regional analysis system for Alzheimer’s disease (VSRAD).

Methods:

The participants included 29 (age: 61.7±4.5 years) and 39 (age: 60.2±4.9 years) patients with EOSD and EOAD, respectively. The degree of atrophy in medial temporal structures was quantified using the VSRAD for magnetic resonance imaging data. Receiver operating characteristic (ROC) analysis was performed to distinguish patients with EOSD and EOAD using the mean Z score (Z-score) in bilateral medial temporal structures and the absolute value (laterality score) of the laterality of Z-score (| right–left |) for indicating the degree of asymmetrical atrophy in medial temporal structures.

Results:

The EOSD group had significantly higher Z and laterality scores than the EOAD group (Z-scores: mean ± standard deviation: 3.74±1.05 vs. 1.56±0.81, respectively; P<0.001; laterality score: mean ± standard deviation: 2.35±1.23 vs. 0.68±0.51, respectively; P<0.001). In ROC analysis, the sensitivity and specificity to differentiate EOSD from EOAD by a Z-score of 2.29 were 97% and 85%, respectively and by the laterality score of 1.05 were 93% and 85%, respectively.

Conclusions:

EOSD leads to more severe and asymmetrical atrophy in medial temporal structures than EOAD. The VSRAD may be useful to distinguish between these dementias that have several clinically similar symptoms.
Incorporation of Protecting Groups in Organic Chemistry: A Mini-Review
Authors: Kisla Mehmet Murat , Hassan Mohammed Al-Kassim , Osman Hind M. , Aydin Amine Sena , Sen Hasan Tahsin , Khazei Shan , Kul Pınar , Kuş Canan
Published: August 2022

The approach of utilizing protecting groups (PGs) in organic chemistry has led to the
successful syntheses of an array of useful organic compounds. This strategy has also addressed some
of the complexities associated with many organic reactions. These PGs find useful applications in
simple and complex reactions that involve the synthesis of large organic compounds such as peptides,
and oligosaccharides. The fundamental role of PGs is to prevent undesired reactions that could
hinder the progress or completion of such reactions. Ideal PGs must be utilized in this regard to
achieve the desired objectives. This review describes the diverse protecting groups found in the
literatures, the functional moieties for the protection, deprotection strategies, and their relevant applications
in organic synthesis.
Green Synthesis of Mono, Bis and Tris Aminobenzochromenes and Benzopyranochromenes
using Fe3O4@Sio2@ Vanillin/Vitamin B1 Nanoparticles:
A New, Mild, Simple and Effective Bronsted Acid Catalyst for the Synthesis
of Chromenes
Authors: Fekri Leila Zare , Kadivar-Kalmarzi Mohaddeseh , Hojjati-Zolpirani Zahra
Published: August 2022

Objective:

Vanillin/Vitamin B1 (Thiamine) supported Fe3O4@SiO2 nanoparticles (Fe3O4 @SP@VT) were synthesized and thoroughly analyzed, and was used for the green and efficient synthesis of chromenes using the multicomponent reaction of aldehyde, malononitrile and 4-hydroxy coumarin, as well as the multicomponent reaction of aldehyde, α-naphthol or β–naphthol and 4-hydroxy coumarin.

Methods:

The reaction was performed under grinding conditions and at the end of the reaction the catalyst was separated in the presence of a strong magnet and can be recovered 10 times.

Results:

The advantages of this method are high purity of products, short times, higher yield, easy separation and cheap raw materials.

Conclusion:

we have developed Fe3O4@SP@VT catalyzed multicomponent synthesis of aminobenzochromenes using the reaction of benzaldehyde, malononitrile and naphthol and multicomponent synthesis of benzopyranochromenes using benzaldehyde, 4-hydroxycoumarin and β-naphthol under grind technique.
Comprehensive Metabolomic Analysis of Lung Cancer Patients Treated
with Fu Zheng Fang
Authors: Ding Yongjuan , Lv Juan , Hua Yujiao
Published: August 2022

Background:

Lung cancer remains one of the leading cancers with increasing mortality rates in the world, the clinicians in our hospital summarized “Fu Zheng Fang (FZF)” as Chinese medicine prescription with good therapeutic effect and low adverse reactions to treat lung cancer.

Objective:

To give an in-depth study on the essence and internal rules of the effect of FZF.

Method:

Serums samples from twenty lung cancer patients and whom accepted FZF were subjected to metabolomic profiling using UPLC-Q-Exactive-MS combined with multivariate statistical analysis.

Result:

17 significantly differential metabolites were found in NC and FZF group, which were mainly participated in phenylalanine metabolism, apelin signaling pathway, sphingolipid signaling pathway, and others. Seven metabolites were increased in FZF group relative to NC group, while ten metabolites were decreased in FZF group, most of them were proved to be consistent with previous experiments. This indicated that FZF had a definite therapeutic effect on lung cancer by regulating the contents of metabolites through amino acid metabolism, metabolism of cofactors and vitamins, carbohydrate metabolism, and cancer.

Conclusion:

This study provides a deeper insight into the comprehensive understanding of molecular mechanisms of FZF treatment against lung cancer.
Cyclodextrin based Nanosponges for the Oral Delivery of Actarit:
Physicochemical Characterisation and Dissolution Studies
Authors: Madhavi M. , Kumar G.S.
Published: August 2022

Introduction:

The current research aims to formulate a controlled release formulation of
Actarit utilizing cyclodextrin based nanosponges as a nanocarriers. β-Cyclodextrin built nanosponges
were prepared by condensation reaction using diphenyl carbonate as crosslinking agent.

Method:

A 3-level, 3-factor Box-Behnken design was used to optimize the reaction conditions. The
particle size, zeta potential and solubilization efficiency of prepared nanosponges were determined.
Actarit was loaded into nanosponges by freeze drying method. Actarit loaded nanosponges were
further evaluated for particle size, zeta potential, surface morphology, FTIR, DSC, XRD and
Dissolution characteristics. The cyclodextrin nanosponges prepared under optimum conditions exhibited
a particle size range of 143.42 to 152.76 nm with low polydispersity indices. FTIR spectra confirmed
the formation of carbonyl bond between the β-Cyclodextrin molecules.

Results and Discussion:

Actarit loaded nanosponges exhibited a particle size range of 157.13 to
168.34 nm with minimum polydispersity index. The zeta potential value was sufficiently high to maintain
the stability of colloidal nanosponges. TEM image exposed the spherical structure of drug loaded
nanosponges that could be retained and released gradually over time. The FTIR, DSC and XRPD
studies inveterate the interaction between Actarit and nanosponges. The drug loaded nanosponges
displayed a significant progress in dissolution of drug when compared to plain Actarit. The initial rapid
release of Actarit from nanosponges formulations was observed. After 24 h of study, around 90 % of
the drug released from nanoformulation and only around 20 % of the drug from free drug suspension.

Conclusion:

Cyclodextrin based nanosponges displayed superior complexing capability with increased
solubility of poorly soluble Actarit.
SARS-CoV-2 Invasion: What Happens to Other Respiratory Viruses?
Authors: Kiseleva Irina , Musaeva Tamila , Ksenafontov Andrey
Published: August 2022

This letter briefly presents the relationships between respiratory viruses in the years prior to and during the COVID-19 pandemic. Viral common colds are self-limiting infections that typically resolve within a few days. However, when well-established epidemiological relationships are disrupted during a pandemic, they behave differently. For instance, during the 2009 influenza pandemic, while the majority of seasonal respiratory viruses lost ground under the pressure of a new pandemic strain, some others (for instance, human rhinoviruses) continued to circulate along with the pandemic pathogen and in some cases, even delayed its spread. With the arrival of the COVID-19 pandemic, the degree of circulation of many respiratory viruses has changed dramatically. Along with a significant reduction in the circulation of many seasonal respiratory pathogens, rhinoviruses, respiratory syncytial virus and non-COVID-19 coronaviruses—being the most frequently identified respiratory pathogens—have shown their unique capability to compete with SARS-CoV-2.
Applications of Bacteriocins of Lactic Acid Bacteria in Biotechnology and Food Preservation: A Bibliometric Review
Authors: Anumudu Christian K. , Omoregbe Osaze , Hart Abarasi , Miri Taghi , Eze Ukpai A. , Onyeaka Helen
Published: August 2022

Introduction:

Due to the growing prevalence of antibiotic resistance in microorganisms and the demand for safe food, there is increasing interest in using natural bioproducts such as the antimicrobial peptides bacteriocins to extend the shelf-life of foods. This is because of their spectrum of activity, ease of synthesis and applicability. This study reports on the global trends in lactic acid bacteria (LAB) bacteriocins based research publications in the Web of Science core collections within the last 20 years (2000-2019), with specific focus to their applications in biotechnology and food science.

Methods:

Data analysis was undertaken using VOSviewer and HistCite software to evaluate relationships between articles and visualise research linkages amongst authors, institutions and countries.

Results:

In the 20 years under review, a total of 1741 bacteriocin related articles were published, with the most cited publication examining the anti-infective activity of Lactobacillus salivarius. The highest research output was recorded by the United States, followed by Spain and China. However, Europe as a continent had the highest research output with a higher inter-institution collaboration network and stronger food safety legislations.

Discussion:

The bibliometric analysis gave insights into the research areas, cooperation network of authors, co-citation maps and co-occurrence of keywords utilized in the research field and indicates that bacteriocin-based research is highly multidisciplinary with a global reach.

Conclusion:

Key focus is on the control of foodborne disease pathogens, search for new producer organisms and approaches to improve bacteriocin yield and application. This class of antimicrobial peptides has the potential to replace chemical food preservatives in the future.
Substances of Milky Juice of Genus Lactarius Fungi: Chemical and Toxicological
Characteristics
Authors: Antonyuk Volodymyr O. , Panchak Lydia V. , Tsivinska Mariana V. , Stoika Rostyslav S.
Published: August 2022

Background:

Fungi of the genus Lactarius Pers. before the maturation of spores are not
damaged by microorganisms, insects, mollusks, and animals. Such resistance correlates with the period
when the basidiomes of these fungi are filled with milky juice, which contains substances of various
chemical nature that provide their protection.

Objective:

The aim of our work is to present the results of our recent and previously published studies
on the identification and toxicological characteristics of substances available in the milky juice of fungi
of the genus Lactarius Pers and used for protection against predator and parasite organisms. The possibility of using these substances to suppress tumor cells is also discussed.

Methods:

The biological effect of the juice of L. pergamenus, L. quietus, and L. volemus, as well as
methylene chloride, extracts obtained from fresh, frozen and dried basidiomes of L. pergamenus was
studied. Purification of individual fractions of hexane extract from the basidiomes was performed by
chromatography on a silica gel column and their analysis by done by thin layer chromatography and
gas chromatography mass spectrometry.

Results:

The sesquiterpene aldehydes were shown to be the main component of the chemical protection system of Lactarius. These agents are present in the milky juice of the Lactarius fungi, and they
are easily oxidized by oxygen in the air. The milky juice of these mushrooms is also rich in higher fatty
acids and phthalates. Phthalates possess an insecticidal effect, while higher fatty acids are capable of
forming adducts with sesquiterpenes that provide emulsion stability. Water-soluble substances, in particular, the polyphenol oxidase enzyme, whose activity correlates with the content of milky juice in
basidiomes, also play a protective role.

Conclusion:

Milky juice of mushrooms of Lactarius Pers. genus is a stable balanced emulsion containing a large number of substances. One part is responsible for the toxic effects on other organisms,
while the other part determines the chemical stability of the emulsion. Altogether, they create an effective system of protection of fungi of the Lactarius genus against microorganisms, insects, mollusks,
and animals.
Application of Fuzzy Neutrosophic Cone in Decision Making
Authors: Kumar De Sujit , Bhattacharya Kousik , Roy Biswajit
Published: August 2022

Aims:

This article deals with a new decision-making process under a neutrosophic fuzzy
environment. First of all, we develop various types of neutrosophic set by means of neutrosophic
cones. In fact, this set has been developed from the general equation of second degree in the field
of classical geometry. Considering the neutrosophic components “true membership”, the “falsity
membership” and the “indeterminacy” as the three variables of three-dimensional rectangular axes
we develop various types of cones like structures of the traditional neutrosophic set and hence a
new defuzzification method.

Background:

Fuzzy set has some limitations in its domain [0,1] to describe real-life decisionmaking
problems. The problem of difficulties lies in the variation of lower and upper bound and
also the single valued logic (membership function only) systems. In reality, three valued logics
(membership function, non-membership function and indeterminacy) have been established in the
name of Neutrosophic logic/sets, and two valued logics (membership and non-membership functions)
have developed in the name of Intuitionistic fuzzy logic/sets. In three valued logic system,
the concepts of negation are now a growing subject of any group decision making problems. However,
to draw a clear estimation of a neutrosophic decision has not yet been studied by modern researchers.

Objective:

Various kinds of new establishments of the Neutrosophic set have been studied from the
algebraic point of view, along with some polynomial structures. We have seen that; no finite geometric
structures have been developed yet to qualify the real-world problems.

Method:

We consider the three components of a neutrosophic set as the variables of threedimensional
geometry. Since, the decisions are compact and constructive, we may consider the
convex neutrosophic cone for analyzing single/ multiple group decision making problems.

Result:

Various definitions are made over the cone- fundamentals using non-standard neutrosophic
set in the domain [−1,1] × [−1,1] × [−1,1]. Then, we studied the constructions of several expressions/
functions of neutrosophic cones, such as reciprocal cone, and enveloping cone via a novel
thinking process. Then using some examples, we have developed a new ranking method along
with their geometric structures exclusively.

Conclusion:

In this changing world, the nature of decision-making behaviors is also changing rapidly.
So, the need of establishing new concepts is an emerging area of research. However, more attention
is required in discussing such vital issues in near future. The proposed approach may be applied
to the decision-making problems of global issues also.
From moral values to public health effectiveness
Authors: Eterović Igor
Published: August 2022

The COVID-19 pandemic has put every contemporary society in front of various challenges. While those are often reflected and explained through economic, political or medical lenses, it seems that thorough ethical and bioethical insights are too rarely exposed and made explicit. This article tries to contribute to the neglected sphere of interconnection and interrelatedness of basic moral values and general, primarily public health, challenges. Moreover, it will be argued that by deeply disrespectful behaviour of chief institutions and inappropriate communication to the overall community (citizens) the value of elementary trust and respectfulness has been eroded, betrayed, and consequently brings to the plethora of economic, political, medical, and other challenges and troubles. The key argument is that the effectiveness of the public health measures is primarily rooted in stable and publicly communicated basic values, such as life and health, but the stability and communication of those values lays mostly in moral values such as trust, respect, fairness etc. One of the most important lessons this pandemic could give the humanity is the almost self-evident, but often forgotten insight, that moral values are the necessary glue of all values needed for functional society (and generally functional global community on Earth). The examples will be taken from the Croatian example of social, political, and institutional confrontation to the COVID-19 pandemic.
Children’s “Best Interest” Locked up – On the Situation of Children’s Rights during the COVID-19 Responses
Authors: Spieker Michael
Published: August 2022

The constitution of the WHO as well as the UN Convention on the Rights of the Child both emphasise the unique position of children, the significance of healthy development and the obligation of public and private actors to always consider the best interest of the child. There is – at least in the case of Germany – no evidence that this obligation has been fulfilled in due manner during the COVID-19 reactions. On the other hand, there is clear evidence from different parts of the world that the closure of schools and all places of social encounter has deeply harmed the social, emotional and even intellectual development of many children. The children’s rights therefore have not been safeguarded during the corona-reaction-crisis. The article argues that this disregard of the position of children has its roots in public health’s utilitarian perspective on the health of peoples instead of individuals. In order to safeguard the rights of children in public health operations, the procedures already foreseen by the UN Convention and its implementing regulations to take into account the best interest of the child must be truly implemented in the future.
Нелинейная динамика индивидуальных полос деформации Портевена--Ле Шателье
Authors: Шибков А.А. , Золотов А.Е. , Гасанов М.Ф. , Денисов А.А. , Кольцов Р.Ю. , Кочегаров С.С.
Published: August 2022

Based on high-speed studies of the dynamics of Portevin-Le Chatelier ambryo bands with a temporal resolution of up to 20 and a spatial resolution of up to 10 , their classification is proposed, which includes four types of bands depending on the nature of interaction with other bands and the sample surface (using the example of a polycrystalline aluminum-magnesium alloy) . It has been found that all types of ambryo bands demonstrate nonlinear dynamics with a sharp acceleration of the band tip and the growth rate of its volume at the final stage before reaching the sample surface. A phenomenological model of the nonlinear growth of the ambryo band is proposed, which explains the exponential self-acceleration stage observed experimentally. The sharp absorption of acoustic noise at the stage of accelerated band growth is discussed.
Ab initio расчет зонной структуры и свойств модификаций соединения Ti-=SUB=-3-=/SUB=-Sb, допированного литием
Authors: Асадов М.М. , Маммадова С.О. , Гусейнова С.С. , Мустафаева С.Н. , Лукичев В.Ф.
Published: August 2022

Using the density functional theory (DFT) in the local electron spin density approximation (LSDA), 2×2×2 supercells based on the Ti3Sb compound have been studied. The supercells contained their own vacancies and doped lithium atoms replacing Ti and/or Sb. The DFT-LSDA method was used to calculate the structural, electronic, and magnetic properties, the enthalpy of formation, and the cohesion energy of supercells of two modifications of the Ti3Sb compound. We studied supercells with cubic system (A15 type structure; a = 5.217 Å) and tetragonal system (D8_m type structure; а = 10.457 Å, с = 5.258 Å). It has been established that the distribution of the density of states of the Ti3Sb cubic system has a more metallic character than for the D8_mTi3Sb modification. The enhancement of "metallicity" in the cubic modification A15 Ti3Sb is associated with an increase in the Ti–Sb interatomic distance in the crystal. Due to this, the degree of metallic bonding increases during the electronic interaction between Ti and Sb atoms near the Fermi level in Ti3Sb.
In DFT calculations, the spin-polarized density of states was taken into account. It has been established that in both modifications (A15 and D8_m) of Ti3Sb near the Fermi level for s, p, d-states with spin "up" and spin "down" there is a spin imbalance in the population of energy levels.
Defect-containing supercells based on Ti3Sb were studied by DFT-LSDA calculations. It is shown that Ti and/or Sb vacancies in the lattices of Ti3Sb crystals of both modifications (A15 and D8_m) increase the magnetic moment (M) as compared to the value of M (M_tot = 0.08 μ_B) of a “pure” Ti3Sb crystal.
Considering that Al5 Ti3Sb is also interesting as a material for Li-ion batteries, we studied Ti3Sb–Li supercells doped with lithium. Li-doping and the creation of own Ti and/or Sb vacancies changes the distance between atoms in Ti3Sb. Correspondingly, the resulting local magnetic moments near the Ti or Sb vacancies also change.
The enthalpy of formation and magnetic moment of Ti3Sb and Ti3Sb–Li based supercells are calculated. DFT calculations of the structural stability of binary compounds (phases) have been carried out, and the stability of conodes between phases in the Ti–Sb–Li system has been established. The isothermal section of the Ti–Sb–Li system was plotted at 298 K. It is shown that the introduction of various lithium concentrations (<6.25 at. % Li) into the Ti3Sb (Space group Pm3 ̅n; № 223; a = 5.217 Å) crystal lattice reduces the partial magnetic moment of Ti in the Ti3Sb–Li supercell.
Фазовые превращения в ниобате бария-стронция SBN-50 в интервале температур от 80 до 700 K по данным спектроскопии КРС
Authors: Матяш Я.Ю. , Анохин А.С. , Павленко А.В.
Published: August 2022

The dynamics lattice of the Sr0.5Ba0.5Nb2O6 (SBN-50) ceramic was studied using Raman spectroscopy in the temperature range of 80-700 K with a step of 10 K. The analysis of the Raman spectra in the range ν = 50-1000 cm-1 revealed features in the temperature dependence behavior of the optical modes frequencies associated with the displacement of Ba, Sr and Nb atoms from their average positions in the crystal lattice, which is associated with a macroscopic phase transition from the paraelectric to the ferroelectric phase in the vicinity of 390 K. It is shown that anomalies at T~ 565 K on the temperature dependences of the frequency and line half-width corresponding to the oscillations of the NbO6 octahedron can be caused by the presence of polar nanoregions in the paraelectric phase in SBN-50. When the sample was cooled to a temperature of 80 K, the behavior was recorded in the Raman spectra, indicating the occurrence of a structural phase transition in the ferroelectric phase in the vicinity of 190 K. The reasons for the revealed patterns are discussed.
Энергия относительного движения электрона и дырки в экситоне во внешнем электрическом поле в пластине GaAs
Authors: Логинов Д.К. , Донец А.В.
Published: August 2022

The dependence of the energy of the relative electron-hole motion in an exciton on the magnitude of applied electric field for various thicknesses of an ideal flat semiconductor plate is theoretically calculated. It is shown that the variation of the plate thickness significantly affects the dependence of the energy on the electric field. The effect should be observed in plates whose thickness exceeds the Bohr exciton radius by two orders of magnitude.
Структурные и фазовые особенности наночастиц селенида цинка, полученных лазерным испарением
Authors: Мурзакаев А.М. , Осипов В.В. , Платонов В.В.
Published: August 2022

The first production of weakly agglomerated zinc selenide nanopowders by evaporation of a target of the required chemical composition in argon using a fiber ytterbium laser is reported. Nanoparticles have the shape of polyhedrons and, more rarely, spheres with an average size of 18 nm. According to XRD data, the obtained nanopowders contain two phases: a stable cubic phase (sphalerite, 40 wt. %) and a metastable hexagonal phase (wurtzite, 60 wt. %). An analysis of HRTEM showed that most of the nanoparticles have structural defects. Due to superstoichiometry, defects in the crystal structure of the crystallographic shift type are formed in nanoparticles. Magneli phases, Wadsley defects and various kinds of heterogeneity inside the particles were found.
Эффекты гамма-наведенных дефектов на активаторное свечение в сцинтилляторных кристаллах Lu-=SUB=-2-=/SUB=-SiO-=SUB=-5-=/SUB=- : Ce
Authors: Исламов А.Х. , Ибрагимова Э.М. , Кудратов Х.Н. , Вильданов Р.Р.
Published: August 2022

Correlations were studied between the optical absorption (OA) spectra and the integral curves of thermal glow (TG) in 300-600 K after irradiation of Lu2SiO5:Ce scintillation crystals with 60Co gamma-quanta (1.17 and 1.33 MeV) at the dose rate 1.1 Gy/s in the dose range 70─5∙107 Gy at 310 K and their gamma-luminescence (GL). There are intrinsic defects caused by technological process, such as neutral VO5-centers with OA band at 193 nm and charged ≡Si–VO4 - 213 nm, Lu1– F+–Si - 238 nm, Ce3+/Ce4+- 263 nm, and Ce3+/F - 295 nm centers. Irradiation to the dose 5∙104 Gy resulted in decreasing in VO5 -center concentration, but did not influenced on others. While, after doses > 5∙104 Gy concentrations of all other mentioned defects grew. The observed recovery of OA at 193 nm and decrease in TG peak at 330 K with the ageing time (1, 3 and 10 hours) at 305 K, and also the correlated growth of OA at 238 nm and TG peak at 540 K after serial irradiations to doses from 70 to 2.3∙106 Gy are due to releasing electrons from these color centers followed by radiative recombination at Се1-centers. However Ce3+ GL yield decrease at 400 and 420 nm at doses >105 Gy is possible related with increasing concentrations of ≡Si –VO4 , Lu1–F+– Si and Ce3+/F centers, which compete with Ce1 ones in trapping electrons. Thus, the upper limit for stable Lu2SiO5:Ce gamma-scintillation is 105 Gy.
Твердые растворы CaMoO-=SUB=-4-=/SUB=--NaGd(MoO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=-: моделирование свойств и локальной структуры методом межатомных потенциалов
Authors: Дудникова В.Б. , Антонов Д.И. , Жариков Е.В. , Еремин Н.Н.
Published: August 2022

Проведено моделирование твердых растворов CaMoO4-NaGd(MoO4)2 методом межатомных потенциалов. Показано, что твердые растворы существуют во всем диапазоне составов и близки к идеальным. Получены зависимости от состава параметров и объема элементарной ячейки, плотности, модуля объемной упругости, энтальпии, колебательной энтропии и теплоемкости. Построены температурные зависимости теплоемкости и колебательной энтропии. Анализ локальной структуры и ее изменения в зависимости от состава твердого раствора Ca1-xNax/2Gdx/2MoO4 показал, что в твердом растворе межатомные расстояния Gd-O в среднем на 2.62% меньше, а Na-O на 3.15% больше расстояний Ca-O. В целом это приводит к увеличению параметров и объема элементарной ячейки при образовании твердых растворов Ca1-xNax/2Gdx/2MoO4 по сравнению с CaMoO4. Ключевые слова: моделирование, молибдаты, твердые растворы, локальная структура.
Влияние температуры на люминесцентные свойства кристаллов CaMoO-=SUB=-4-=/SUB=- и SrMoO-=SUB=-4-=/SUB=-, беспримесных и легированных Nd-=SUP=-3+-=/SUP=-
Authors: Федюнин Ф.Д. , Спасский Д.А. , Воронина И.С. , Ивлева Л.И.
Published: August 2022

Luminescence properties of calcium and strontium molybdates, undoped as well as doped with Nd3+ ions were studied. The influence of temperature on the energy transfer processes from the intrinsic emission centers to activator is shown on the basis of the analysis of the temperature dependencies of luminescence spectra and decay kinetics. It is concluded that the studied compounds are promising for non-contact luminescent thermometry in a wide temperature range.
Степень сверхструктурного упорядочения в наноразмерном ферромолибдате стронция по данным ферромагнитного резонанса
Authors: Демьянов С.Е. , Петров А.В.
Published: August 2022

Powders of strontium ferromolybdate (Sr2FeMoO6-δ) with various degrees of superstructural ordering of iron and molybdenum cations (P = 67%; 81%; 89%) were studied by the ferromagnetic resonance method. These investigations have been carried out taking into account the available information on the structural, magnetic and resistive characteristics of the samples under study. As a result of the analysis of the ferromagnetic resonance spectra, it was concluded that the amplitude of the corresponding signals strongly depends on the magnitude of the superstructural ordering, increasing with its growth. The presence of maxima in the ferromagnetic resonance spectrum in the temperature range 350–370 K, which shift slightly to low temperatures with increasing P, confirms the existence of ferrimagnetic and antiferromagnetic states competing with each other in the region close to the Curie temperature.
Влияние степени размытия фазового перехода на температуру деполяризации в релаксорах разного типа
Authors: Камзина Л.С.
Published: August 2022

The relationship between the temperatures of depolarization (Td) and morphotropic phase transition
(TF-R) in crystalline relaxor solid solutions of various types, such as PbMg1/3Nb2/3O3-29PbTiO3 (PMN-29PT), PbZn1/3Nb2/3O3-9PbTiO3 (PZN- 9PT) and NaBi1/2Ti1/2O3-xBaTiO3 (x=5.7.5%) (NBT-xBT) has been studied. For this purpose, dielectric measurements of polarized samples were carried out, and the process of induction of the ferroelectric phase in an electric field applied below the TF-R temperature was also studied. It was found that the structure of the low-temperature phases in these compounds is different, which leads to significant differences not only in the induction of the ferroelectric phase, but also to different relative positions of the temperatures Td and TF-R. In PMN-29PT, the formation of ferroelectric phases is preceded by some delay time, which is one of the hallmarks of a non-ergodic glassy phase, and in this case the temperatures Td and TF-R coincide. In PZN-9PT and NBT-5BT, the ferroelectric phase is induced immediately after the field is applied without a delay time, which indicates that below the TF-R temperature, the non-ergodic glassy phase does not appear, and the temperatures Td and TF-R do not coincide in them. The results obtained are discussed from the point of view of different degrees of diffuseness of the phase transition and different sizes of the polar regions. It is suggested that the coincidence of temperatures Td and TF-R is a consequence of the non-ergodic glassy phase and the small sizes of the polar regions.
Влияние водорода на механические свойства металлов в условиях высокоскоростной деформации
Authors: Малашенко В.В.
Published: August 2022

Теоретически проанализировано движение ансамбля краевых дислокаций в металлах с высоким содержанием водорода в условиях высокоскоростной деформации (high strain rate deformation). В рамках теории динамического взаимодействия дефектов (ДВД) (DID) получено аналитическое выражение для зависимости динамического предела текучести от концентрации атомов водорода. Ключевые слова: дислокации, водород, высокоскоростная деформация, металлы.
Полиморфные превращения в йодидном титане
Authors: Спивак Л.В. , Кирчанов В.С. , Щепина Н.Е.
Published: August 2022

Based on the analysis of differential scanning calorimetry data, the possibility of classifying the observed endothermic or exothermic transformations as phase transformations of the first oder is considered. Two approaches have been implemented. The first is based on the correspondence between the temperatures of the maximum conversion rate and the temperatures of the extrema on the second derivative of the differential scanning calorimetry signal with respect to temperature. In the second approach, the phase transformation is considered as a kind of kinetic reaction of a chemical process with the determination of some parameters included in the kinetic equations. In this case, the order parameter of such reaction n is obtained from the analysis of the differential scanning calorimetry signal shape in the region of phase transformation registration temperatures. Using the example of experiments carried out during thermal cycling of titanium iodide samples, it is shown that both the first and second approaches make it possible to fairly adequately attribute the processes that cause calorimetric effects on the dependences of differential scanning calorimetry to first-order phase transitions. In particular, the obtained results of differential scanning calorimetry during heating and cooling of iodide titanium show that polymorphic transformations in it are realized by various mechanisms depending on the rate of thermal cycling and the thermal history of the metal.
Perceived Unmet Needs in Patients Living With Advanced Bladder Cancer and Their Caregivers: Infodemiology Study Using Data From Social Media in the United States
Authors: Renner Simon , Loussikian Paul , Foulquié Pierre , Arnould Benoit , Marrel Alexia , Barbier Valentin , Mebarki Adel , Schück Stéphane , Bharmal Murtuza
Published: August 2022

Background

Locally advanced or metastatic bladder cancer (BC), which is generally termed advanced BC (aBC), has a very poor prognosis, and in addition to its physical symptoms, it is associated with emotional and social challenges. However, few studies have assessed the unmet needs and burden of aBC from patient and caregiver perspectives. Infodemiology, that is, epidemiology based on internet health-related content, can help obtain more insights on patients’ and caregivers’ experiences with aBC.

Objective

The study aimed to identify the main discussion themes and the unmet needs of patients with aBC and their caregivers through a mixed methods analysis of social media posts.

Methods

Social media posts were collected between January 2015 and April 2021 from US geolocalized sites using specific keywords for aBC. Automatic natural language processing (regular expressions and machine learning) methods were used to filter out irrelevant content and identify verbatim posts from patients and caregivers. The verbatim posts were analyzed to identify main discussion themes using biterm topic modeling. Difficulties or unmet needs were further explored using qualitative research methods by 2 independent annotators until saturation of concepts.

Results

A total of 688 posts from 262 patients and 1214 posts from 679 caregivers discussing aBC were identified. Analysis of 340 randomly selected patient posts and 423 randomly selected caregiver posts uncovered 33 unique unmet need categories among patients and 36 among caregivers. The main unmet patient needs were related to challenges regarding adverse events (AEs; 28/95, 29%) and the psychological impact of aBC (20/95, 21%). Other patient unmet needs identified were prognosis or diagnosis errors (9/95, 9%) and the need for better management of aBC symptoms (9/95, 9%). The main unmet caregiver needs were related to the psychological impacts of aBC (46/177, 26.0%), the need for support groups and to share experiences between peers (28/177, 15.8%), and the fear and management of patient AEs (22/177, 12.4%).

Conclusions

The combination of manual and automatic methods allowed the extraction and analysis of several hundreds of social media posts from patients with aBC and their caregivers. The results highlighted the emotional burden of cancer for both patients and caregivers. Additional studies on patients with aBC and their caregivers are required to quantitatively explore the impact of this disease on quality of life.
Health Information Sourcing and Health Knowledge Quality: Repeated Cross-sectional Survey
Authors: Korshakova Elena , Marsh Jessecae K , Kleinberg Samantha
Published: August 2022

Background

People’s health-related knowledge influences health outcomes, as this knowledge may influence whether individuals follow advice from their doctors or public health agencies. Yet, little attention has been paid to where people obtain health information and how these information sources relate to the quality of knowledge.

Objective

We aim to discover what information sources people use to learn about health conditions, how these sources relate to the quality of their health knowledge, and how both the number of information sources and health knowledge change over time.

Methods

We surveyed 200 different individuals at 12 time points from March through September 2020. At each time point, we elicited participants’ knowledge about causes, risk factors, and preventative interventions for 8 viral (Ebola, common cold, COVID-19, Zika) and nonviral (food allergies, amyotrophic lateral sclerosis [ALS], strep throat, stroke) illnesses. Participants were further asked how they learned about each illness and to rate how much they trust various sources of health information.

Results

We found that participants used different information sources to obtain health information about common illnesses (food allergies, strep throat, stroke) compared to emerging illnesses (Ebola, common cold, COVID-19, Zika). Participants relied mainly on news media, government agencies, and social media for information about emerging illnesses, while learning about common illnesses from family, friends, and medical professionals. Participants relied on social media for information about COVID-19, with their knowledge accuracy of COVID-19 declining over the course of the pandemic. The number of information sources participants used was positively correlated with health knowledge quality, though there was no relationship with the specific source types consulted.

Conclusions

Building on prior work on health information seeking and factors affecting health knowledge, we now find that people systematically consult different types of information sources by illness type and that the number of information sources people use affects the quality of individuals’ health knowledge. Interventions to disseminate health information may need to be targeted to where individuals are likely to seek out information, and these information sources differ systematically by illness type.