bluuebunny/crossref_metadata_2025 huggingface dataset:
Design, Synthesis and Biological Evaluation of a Novel Series of Thiadiazole- Based Anticancer Agents as Potent Angiogenesis Inhibitors
Authors: Altuğ-Tasa Burcugül , Kaya-Çavuşoğlu Betül , Koparal Ayşe T. , Turan Gülhan , Koparal Ali S. , Kaplancıklı Zafer A.
Published: January 2021

Background:

Thiadiazole has attracted a great deal of interest as a versatile heterocycle for the discovery
and development of potent anticancer agents. Thiadiazole derivatives exert potent antitumor activity
against a variety of human cancer cell lines through various mechanisms.

Objective:

The goal of this work was to design and synthesize thiadiazole-based anticancer agents with anti-angiogenic activity.

Methods:

N-aryl-2-[(5-(aryl)amino-1,3,4-thiadiazol-2-yl)thio]acetamides (4a-r) were synthesized via the reaction
of 5-(aryl)amino-1,3,4-thiadiazole-2(3H)-thiones with N-(aryl)-2-chloroacetamides in the presence of potassium
carbonate. The compounds were investigated for their cytotoxic effects on three cancer (A549, HepG2,
SH-SY5Y), two normal (HUVEC and 3T3-L1) cell lines using MTT and WST-1 assays. In order to examine
whether the compounds have anti-angiogenic effects or not, HUVECs were cultured on matrigel matrix to create
a vascular-like tube formation.

Results:

Compounds 4d, 4m and 4n were more effective on A549 human lung adenocarcinoma cells than cisplatin.
The IC50 values of compounds 4d, 4m and 4n for A549 cell line were found to be 7.82 ± 0.4, 12.5 ±
0.22, 10.1 ± 0.52 μM, respectively when compared with cisplatin (IC50= 20 ± 0.51 μM), whilst their IC50 values
for HUVEC cell line were determined as 138.7 ± 0.84, 78 ± 0.44, 177.6 ± 0.2 μM, respectively after 48 h of the
treatment. The concentrations (10-20-50 μM) of compounds 4d, 4e, 4l, 4m, 4n, 4q and 4r were found to inhibit
vascular like tube formation.

Conclusion:

According to their anticancer and anti-angiogenic effects, compounds 4d, 4m and 4n may be potential
anticancer agents for further in vivo studies.
Therapeutic Potential of Polyphenols and their Nanoformulations in the Treatment of Colorectal Cancer
Authors: Khan Shaheer H. , Alhumaydhi Fahad A. , Khan Masood A. , Younus Hina
Published: January 2021

Background:

Colorectal Cancer (CRC) ranks third among all cancer-related deaths around the
globe. Chemotherapy may prolong the survival of CRC patients to some extent, but its clinical use is associated
with grave side effects on overall health. Contrary to chemotherapy, the use of plant-derived therapeutic
molecules offered advantages because of their reduced toxicity. Polyphenol is a group of phytochemicals that
impart many therapeutic benefits in the treatment of diabetes, cardiovascular disease and cancer. Various signaling
pathways, including Wnt/β-catenin, MAPK/PI3K and TGF-β/Smad, play very important roles in the development
and progression of CRC. Polyphenols inhibit CRC progressions by modulating these signaling pathways
e.g. curcumin and resveratrol impede cancer cell proliferation by inhibiting Wnt signaling. Because of
their lower aqueous solubility, the therapeutic efficacy of polyphenols is not fully exploited. In order to increase
their bioavailability and efficacy, the nanoformulations of polyphenols have been formulated and investigated
against various CRC test models. The main objective of this review is to explore the potential roles of polyphenols
and their nanoformulations in the treatment of colorectal cancer.

Methods:

We used PubMed, Web of Science, ScienceDirect, Google Scholar and Scopus electronic databases
by searching the keywords: nanoparticles, polyphenols, colorectal cancer, cell signaling pathways. Mostly, the
articles were retrieved directly from the journals licensed to the library of Qassim University, Saudi Arabia.

Results:

Literature analysis has shown that the polyphenols contain several important bioactive compounds,
which showed potential effectiveness against CRC. Incorporating polyphenols into nanoparticles further enhanced
their bioavailability and efficacy. The findings from various studies demonstrated that polyphenol-nanoformulations
accelerated the apoptosis in CRC cells by upregulating the levels of caspases and Bax, whereas inhibiting
the CRC cell proliferation by downregulating the expression of Bcl-2 and ERK1/2.

Conclusions:

This review provides a valuable resource on the important anti-CRC role of polyphenols and their
nanoformulations. This review will expand our knowledge about the anti-CRC roles of polyphenols and their
mechanisms of action through the multiple cell signaling pathways.
Carvacrol Exhibits Chemopreventive Potential against Cervical Cancer Cells via Caspase-Dependent Apoptosis and Abrogation of Cell Cycle Progression
Authors: Ahmad Afza , Ansari Irfan A.
Published: January 2021

Background:

The carcinogenesis of the uterine cervix is predominantly initiated with the consistent
infection of the Human Papilloma Virus (HPV). Owing to the side effects of standard chemotherapeutics in the
treatment of recurrent and metastatic cervical cancer, there is a need for a better and effective treatment modality.
In this lieu of concern, natural compounds have proven their worthwhile potential against the treatment of
various carcinomas. Carvacrol is a phenolic monoterpenoid and several reports have suggested its different biological
properties including antioxidant, anti-inflammatory and anticancer activity.

Objective:

The objective of our present study was to investigate the effect of carvacrol on HPV18+ HeLa cervical
cancer cells.

Methods:

HeLa cervical cancer cells were cultured and subsequently treated with various doses of carvacrol.
Cell viability was assessed via MTT assay. DAPI and Hoechst3342 staining were used to qualitatively analyzed
the induced apoptosis. Reactive Oxygen Species (ROS) was estimated by DCFDA staining protocol and quantitatively
estimated by flow cytometry. The cell cycle distribution and apoptosis (FITC-Annexin V assay) were
analyzed by flow cytometry.

Results:

The results of the present study have established that carvacrol strongly suppresses the proliferation of
cervical cancer cells via caspase-dependent apoptosis and abrogation of cell cycle progression. Furthermore,
our preliminary study also demonstrated that carvacrol exhibits a synergistic effect with chemotherapeutic
drugs (5-FU and carboplatin). These initial findings implicated that natural compounds could reduce the toxic
effects of chemotherapeutic drugs.

Conclusion:

Therefore, this investigation affirms the anti-cancer potential of carvacrol against cervical cancer
cells, which could be an appendage in the prevention and treatment of cervical cancer.
Different Methods for Cell Viability and Proliferation Assay: Essential Tools in
Pharmaceutical Studies
Authors: Nozhat Zahra , Khalaji Mina S. , Hedayati Mehdi , Kia Sima Kheradmand
Published: January 2021

Background and Objective:

The ratio of live cells to total cells in a sample is a definition for cell viability or cell toxicity. The assessment of the viable cells plays a critical role in all processes of the cell culture workflows. Overall, they are used to evaluate the survival of cells and also to optimize culture or experimental conditions following treatment with different agents or compounds, like during a drug screen. In most cases, the measurement of cell viability is the primary purpose of the experiments, for example, in pharmaceutical studies to evaluate agents' toxicity.

Methods:

A literature research was conducted on cell viability assays in MEDLINE (PubMed), Web of Science and Scopus.

Results:

There is a wide range of cell viability assays and different parameters such as cost, speed, and complexity of a test effect to determine the choosing method. However each method has some advantages and disadvantages and none of them is not 100% perfect method.

Conclusion:

Accordingly, it seems that the simultaneous utility of at least two assays will cover each other disadvantages to demonstrate the effects of different agents on different cell types. For instance, when one assay measures cell metabolic health, the other one checks cells permeability. Therefore by this strategy a researcher can report with more confidence the effective doses of the examined therapeutic agents.
Sodium-Glucose Cotransporter Inhibitors in Non- Diabetic Heart Failure: A Narrative Review
Authors: Dahal Ranjan , Acharya Yogesh , Mukherjee Debabrata
Published: January 2021

Background::

Heart failure (HF) is one of the leading public health problems with a substantial
burden in the global healthcare system. Although significant efforts are based on prevention,
early recognition, and proper management of HF, the worldwide surge of risk factors like hypertension,
diabetes, and obesity has further complicated the existing problem.

Objective::

To define the role of the sodium-glucose cotransporter 2 (SGLT2) inhibitors in non-diabetic HF.

Methods::

We performed a comprehensive literature review to examine the available evidence in
the clinical implications of SGLT2 inhibitors in non-diabetic HF using the online databases
(PubMed and Embase).

Results::

We identified two RCTs-DAPA-HF and DEFINE-HF, which were conducted to analyze
the net clinical benefit of dapagliflozin in non-diabetic HF patients. Although we could not study
the composite effects of these studies due to the difference in outcome measures, the individual outcomes
look promising. The number needed to treat (NNT) to prevent one primary event was 21
(95% CI: 15 to 38) in the DAPA study. In DEFINE HF study, responder analysis showed a significant
proportion of patients in the treatment arm experienced improvements in the functional status
with clinically meaningful improvement in KCCQ-OS by 3.7 points and KCCQ-CS by 4.6 points
with NNT of 10 and 7, respectively, at 12 weeks. Both studies also showed low safety concerns in
patients without T2D.

Conclusions::

The outcomes of the two RCTs, DAPA-HF and DEFINE-HF, that studied the effects
of SGLT2 inhibitors in non-diabetic HF showed promising clinical outcomes. Although we are
waiting for other prospective RCTs to reflect similar results and safety profiles, it seems the
SGLT2 inhibitors can have broader clinical implications in managing non-diabetic HF with improved
cardiovascular outcomes.
Prevalence of Congenital Heart Disease among Children in Khorramabad (West of Iran)
Authors: Nezami Alireza , Heidari Ghobad , Tarhani Fariba , Kariminia Masoumeh
Published: January 2021

Aims::

Congenital heart disease is among the most common congenital anomalies in pediatrics.
The aim of this study was to evaluate the prevalence of congenital heart disease in children
in Khorramabad, Iran.

Methods::

This is a descriptive-cross sectional study where all the children diagnosed with congenital
heart disease by echocardiography were enrolled to the Shahid Madani Hospital. Patient information
was collected by means of a questionnaire. Of 1600 children who underwent cardiac
counseling, 9.75% presented congenital heart disease. These were most prevalent among the children
of 0-28 days of the age (14.7%) and least in children aged 1 month-1 year. According to this
study, atrial (20.3%) and ventricular septal defect (10.5%) were the most common heart defects, respectively.
Among signs and symptoms of cardiac disease, 49.1% of children had cyanosis, 89.7%
with increased CT (cardiothoracic)-ratio, and 82.7% of had heart murmur. Congenital heart disease
was more prevalent in male infants (58%) and 6.6% patients had heart failure and 1.4% had other
congenital conditions, such as Down syndrome.

Results::

According to our findings, atrial and ventricular septal defects are the most common congenital
heart anomalies, respectively, in pediatric patients in Khorramabad.
Gastrointestinal Bleeding Associated With Warfarin and Rivaroxaban Therapy in Atrial Fibrillation Cases with Concomitant Coagulopathy
Authors: Sedaghat Meghdad , Lima Behnam Safarpour , Bouzari Reihanesadat , Shadlou Sarvenaz
Published: January 2021

Background:

There is inadequate information on the risk of gastrointestinal (GI) bleeding
in patients who are under rivaroxaban and warfarin therapy in Iran. Determining the risk of GI
bleeding in patients receiving these two drugs can help to select a more appropriate anti-coagulation
prophylaxis in high-risk patients.

Objective:

The aim of this study was to compare the incidence of GI bleeding in patients with atrial
fibrillation (AF) and concomitant bleeding risk factors receiving either warfarin or rivaroxaban.

Methods:

In this observational study, 200 patients with AF and bleeding risk factors who referred
to Imam Hossein Hospital (Tehran, Iran) were included. The patients were under treatment with either
warfarin or rivaroxaban. The incidence of GI bleeding was compared between the two groups
monthly for one year.

Results:

GI bleedings were observed in 61% and 34% of patients treated with warfarin and rivaroxaban,
respectively (P = 0.001).Melena was the most common type of GI bleeding in both groups.
History of hypertension, history of stroke, consumption of anti-platelet drugs, NSAID consumption,
and history of alcohol consumption were associated with more frequent GI bleeding only in
warfarin group.

Conclusion:

The incidence of GI bleeding was lower in AF patients who received rivaroxaban
compared to those treated with warfarin. Also, GI bleeding risk does not change according to the
consumption of other anti-coagulant drugs and underlying history of hypertension or stroke in patients
received rivaroxaban. Therefore, rivaroxaban is suggested as the choice of prophylaxisin patients
with AF and concomitant coagulopathy.
Hypotensive Effects of the Triterpene Oleanolic Acid for Cardiovascular Prevention
Authors: Sureda Antonio , Monserrat-Mesquida Magalida , Pinya Samuel , Ferriol Pere , Tejada Silvia
Published: January 2021

Background::

Hypertension is a high prevalent chronic disease worldwide and a major cardiovascular risk factor.
Oleanolic acid (3β-hydroxy-olea-12-en-28-oic acid) is a wide distributed bioactive pentacyclic triterpenoid with diverse
biological activities such as anti-inflammatory, hepaprotective anti-diabetic or anti-hypertensive.

Objective::

The aim of this study was to review and highlight the available data about antihypertensive activity of oleanolic
acid and the described mechanisms of action.

Method::

Extensive searches were made in the available literature on oleanolic acid and the data investigating its
antihypertensive effects were analysed.

Results::

Most of research has been performed on animal models of hypertension, ex vivo studies with aortic ring and some in
vitro tests with cell cultures, whereas clinical trials are still lacking. Treatment of hypertensive animals with oleanolic acid
significantly ameliorated the rise in the systolic blood pressure. In addition, the hypotensive effects of oleanolic acid are also
related to a potent diuretic-natriuretic activity and nephroprotection. In vitro studies have characterized the participation of
various signalling pathways that modulate the release of vasodilation mediators.

Conclusion::

In vitro and in vivo studies suggest that oleanolic acid effectively reduce blood pressure and could be an
interesting co-adjuvant to conventional treatment of hypertension.
AtreMorine Treatment Regulates DNA Methylation in Neurodegenerative Disorders: Epigenetic and Pharmacogenetic Studies
Authors: Martínez-Iglesias Olaia , Naidoo Vinogran , Carril Juan Carlos , Carrera Iván , Corzo Lola , Rodriguez Susana , Alejo Ramón , Cacabelos Natalia , Cacabelos Ramón
Published: January 2021

Background:

Neurodegenerative disorders are one of the major health problems
in Western countries. Genetic and epigenetic mechanisms play crucial roles in the
origin and progression of these disorders. DNA methylation is the most widely studied epigenetic
mark and is an important regulator of gene expression.

Objective:

Little is known about the influence of bioactive dietary components on epigenetic
mechanisms in neurodegenerative diseases. In this study, we investigated the effects
of E-PodoFavalin-15999 (AtreMorine®), a bioproduct with potent neuroprotective and dopamine
enhancing capabilities, on DNA methylation patterns in Alzheimer’s (AD) and
Parkinson’s Disease (PD). We also aimed to assess, in patients with PD, the effects that
genetic variation across candidate pharmacogenes may have on dopamine synthesis and
release in response to treatment with AtreMorine.

Methods:

We analyzed global DNA methylation and de novo DNA methyltransferase
(DNMT) expression in a transgenic (3xTg) mouse model of AD, and further examined
global DNA methylation in blood samples from patients with PD.

Results:

AtreMorine treatment increased global DNA methylation in 3xTg mice and in
patients with Parkinson´s disease, and produced high DNMT3a expression in AD mice.
We observed varied responses to AtreMorine across the following pharmacogenetic genophenotypes
analyzed, cytochrome P450 oxidases (CYP2D6, CYP2C19, CYP2C9,
CYP3A4, CYP3A5, CYP1A2), human arylamine N-acetyltransferase 2 (NAT2), the vitamin
K epoxide reductase complex subunit 1 (VKORC1), ATP-binding cassette subfamily B
member 1 (ABCB1), and solute carrier organic anion transporter family member 1B1
(SLCOB1).

Conclusion:

Our results suggest that AtreMorine regulates DNA methylation in neurodegenerative
disorders and may constitute a new therapeutic option for the treatment of
these pathologies.
COVID-19 Related Publications Focusing on Cancer: Systematic Review of a Delicate Balance
Authors: Naimi Mahdi F. , Khan Maira , Mahler Mary , Emmenegger Urban
Published: January 2021

Background::

The ongoing COVID-19 pandemic has forced oncologists to alter their daily
practice, despite the lack of substantial evidence, in order to reduce the risk of transmission
among patients with underlying malignant and other concurrent medical conditions.

Objective::

This systematic review compares the characteristics of oncology-focused COVID-19
manuscripts published from January 1st to April 30th, 2020, and from September 1st to September
30th, 2020, to identify the variation of publications between the start of the pandemic and our current
state.

Methods::

The PubMed database was searched on two different occasions using the search string
“Cancer OR Tumor” AND “COVID-19 OR SARS-CoV-2”. All manuscripts pertaining to
COVID-19 and oncological topics were included in this review.

Results::

The search from January 1st to April 30th, 2020 and from September 1st to September 30th,
2020, resulted in 299 and 249 articles pertaining to our objective, respectively. Comparing the earlier
with later publication period, the proportion of articles containing original data increased from
22.4% to 44.2%, whereas the proportion of Editorials/Correspondences decreased from 43.5% to
20.5%. Cancer patient management guidelines accounted for the majority of publications during
both periods (59.2% versus 43.4%, respectively).

Conclusion::

The study revealed a rapidly increasing number of COVID-19 and oncological-focused
publications throughout the pandemic thus far. Given the unprecedented nature of the
COVID-19 pandemic, future analyses are expected to reveal rapidly evolving publication patterns.
Load Spectrum Compiling and Fatigue Life Estimation of the Automobile Wheel Hub
Authors: Liu Xintian , Qu Yang , Yang Xiaobing , Shen Yongfeng
Published: January 2021

Background:

In the process of high-speed driving, the wheel hub is constantly subjected to
the impact load from the ground. Therefore, it is important to estimate the fatigue life of the hub in
the design and production process.

Objective:

This paper introduces a method to study the fatigue life of car hub based on the road load collected from test site.

Methods:

Based on interval analysis, the distribution characteristics of the load spectrum are analyzed.
The fatigue life estimation of one-dimensional and two- dimensional load spectra is compared
by compiling load spectra.

Results:

According to the S-N curve cluster and the one-dimensional program load spectrum, the
estimated range fatigue life of the hub is 397, 100km to 529,700km. For unsymmetrical cyclic loading,
each level means and amplitude of load were obtained through the Goodman fatigue empirical
formula, and then according to S-N curve clusters in the upper and lower curves and two-dimensional
program load spectrum, estimate of the fatigue life of wheel hub of the interval was 329900km to
435200km, and then one-dimensional load spectrum fatigue life was reduced by 16.9% - 17.8%.

Conclusion:

This paper lays a foundation for the prediction of fatigue life and the bench test of fatigue
durability of autoparts subjected to complex and variable random loads. At the same time, the
research method can also be used to estimate the fatigue life of other bearing parts or high-speed
moving parts and assemblies.
The Effect of Novel Microwave-Convective Drying on the Functional Properties of Dried-Pears (Pyrus communis)
Authors: Yildiz Gulcin
Published: January 2021

Aims:

The objective of this study was to investigate the impacts of combined microwave-
convective drying on the quality of dried-pears. Color, bioactive compounds (total
phenolics (TP) and antioxidant capacity (AC)) and textural (hardness) properties of convective (50
and 60 °C), microwave (100 and 200 W), and combined microwave-convective (100-50 °C,
200W-50 °C, 100 W-60 °C and 200 W-60 °C) dried pears were compared with the untreated pears.

Results and Methods:

A Konica Minolta CR-400 Chroma Meter was used to examine the color
changes in dried pears. TP was measured using the Folin-Ciocalteu reagent. The free radical scavenging
activity of the extract was analyzed using 1,1-dipheyl-2-picylhydrazyl (DPPH). The hardness
of dried pear slices with different drying methods was obtained by a texture analyzer. The microwave-
convective dried pear slices (especially at the condition of 200 W - 60 °C) showed higher
preservation of bioactive compounds in addition to improved textural properties and color compared
to other dried pear samples.

Conclusion:

Overall, combined microwave-convective drying is a promising process, as demonstrated
in current research by its capability to better retain dried pear quality in terms of functional
and textural properties.
3-Amino-2-methylquinazolin-4-(3H)-one Schiff Bases Synthesis - A Green Chemistry Approach - A Comparison of Microwave and Ultrasound Promoted Synthesis with Mechanosynthesis
Authors: Komar Mario , Prašnikar Fran , Kraljević Tatjana Gazivoda , Aladić Krunoslav , Molnar Maja
Published: January 2021

Green chemistry methods are important modern synthetic chemistry pathways with main
advantages such as milder reaction conditions, shorter time, and higher yields. A series of quinazolinone
based Schiff bases (1-27) have been successfully synthesized by using green synthetic
methods, including microwave-assisted, ultrasound-assisted and mechanochemical synthesis, respectively.
Desired compounds were prepared from 3-amino-2-methylquinazolin-4(3H)-one and
substituted benzaldehydes with moderate to high yields (11-90%). Benzoxazinone and 3-amino-2-
methylquinazolin-4(3H)-one, the precursors of Schiff bases, were prepared by microwave-induced
synthesis. The structures of all Schiff bases are confirmed by 1H and 13C NMR spectroscopy and
mass spectrometry as well. A novelty of this research is the application and comparison of green
chemistry methods in the synthesis of desired compounds which are listed above. The simplicity of
synthesis includes ethanol as a solvent and no need for further purification.
Green Organic Transformations: Novelty of Graphene Oxide (GO) and Sulfonated Graphene Oxide (SGO)
Authors: Basak Puja , Ghosh Pranab
Published: January 2021

Nowadays, the use of carbocatalyst has attracted much attention due to its sustainability
and affordability. Graphene oxide (GO) and sulfonated graphene oxide (SGO) have emerged as
environmental friendly, metal free, inexpensive carbocatalyst for the synthesis of organic compounds.
Herein, the profound role of GO and SGO in different organic transformation has been
established. The GO and SGO being heterogeneous in nature, have high thermal stability over homogeneous
catalyst in successive runs and can easily be recovered. The presence of oxygen containing
acidic groups in GO and SGO mainly catalyzes the organic reactions. This mini review is emphasized
on the catalytic role of GO and SGO as green and reusable solid acid catalyst in different
organic syntheses.
Improving Students’ Writing Participation and Achievement in an Edpuzzle-Assisted Flipped Classroom
Authors: Emiliya Hidayat Luki , Dzulfiqar Praseno Muhammad
Published: January 2021

Writing is often considered as a dull but challenging skill to be learned. Hence, a learning innovation aside the conventional methods is needed to improve students’ participation and achievement. Flipped Classroom, a reverse teaching strategy was selected to overcome this problem because it involves the use of technology as a learning media that fits the characteristics of millennial students. This strategy was combined with Edpuzzle, a learning media which provides content from renowned education channels that can be customized and used freely by teachers. The combination of Flipped Classroom strategy and Edpuzzle has proven to be successful in improving students’ participation in learning activities (30.5%) as well as their achievement in writing (17%). Therefore, teachers are suggested to implement and adapt this practice in their class while considering the competence to be mastered, as well as students’ needs and characteristics.
Inquiry-based teaching to develop EFL students’ Critical thinking in reading comprehension
Authors: Oktaviah Rahmaniah , Mawarda Rokhman Nissa , Reza Maulana Andi
Published: January 2021

The technology advancement in this era of globalization promotes the innovation and transformation in English language teaching and learning especially for EFL students. The innovations in English Language teaching and learning have fostered the variations of teaching strategy and method. One of the recent strategies proposed in pedagogical context is inquiry-based teaching strategy. Since the recent issues of active learning have been discussed in some school of thoughts, it is closely related to the importance of critical thinking students should have. In order to achieve English language learning goals, which is to enhance the students’ skill, competence, and also critical thinking, the teaching and learning process has to be designed more innovatively and effectively. Nevertheless, the implementation of this strategy should be adjusted in accordance to the students’ capability in learning English in class. Therefore, teachers have to understand well the characteristics of inquiry-based teaching before implementing it in class. This paper attempts to explore the use of inquiry-based teaching in promoting students’ critical thinking, especially in reading comprehension. This paper discusses the issues of this strategy based on theoretical frameworks and provides the example of an activity using 5E that can be applied in class. The reading activity through inquiry-based teaching can be constructed by the teacher by considering the students’ condition and environment.
Природа тонкой структуры вращательных уровней основного X-=SUP=-2-=/SUP=-Sigma-=SUP=-+-=/SUP=--состояния радикала CN
Authors: Терашкевич В.А. , Пазюк Е.А.
Published: January 2021

By means of ab initio high-level quantum-chemical calculations of non-diagonal matrix elements of spin-orbital and electron-rotational coupling between the ground X2Σ+ and excited (1--4)2Π states the observed regular effect of γ-doubling of the rotational levels of the X2Σ+ state was shown to be mainly determined by intramolecular interactions of the mentioned state with remote states (2--4)2Π. In terms of the nonadiabatic model of the effective radial Hamiltonian of the isolated electronic state, it was possible to create the analytical potential of the X2Σ+ state and the corresponding function γ (R) reproducing the frequencies of rotational and vibrational-rotational transitions (for the lowest vibrational levels ν≤3) of the CN molecule at the experimental (spectroscopic) level of accuracy.
Структурные особенности твердых растворов Nd-=SUB=-x-=/SUB=-Gd-=SUB=-1-x-=/SUB=-Cr-=SUB=-3-=/SUB=-(BO-=SUB=-3-=/SUB=-)-=SUB=-4-=/SUB=-
Authors: Болдырев К.Н. , Кузьмин Н.Н. , Добрецова Е.А.
Published: January 2021

Optical studies of NdxGd1-xCr3(BO3)4 0.01≤x≤1 crystals have been carried out. A significant concentration effect of the Nd3+ ion on the crystal structure of these solid solutions was identified. It was found from the absorption spectra of neodymium ions in the 4I9/2→11F3/2 transition region that at a concentration x>0.6 two nonequivalent Nd3+ centers appear, which is explained by the formation of two polytype modifications with space groups R32 and C2/c. At a concentration x<0.6, only one modification with the space group R32 is observed.
ИК-активные фононы ионного кристалла LiNiPO-=SUB=-4-=/SUB=-
Authors: Климин С.А. , Радионов М.С. , Яковлев В.А. , Новикова Н.Н. , Песчанский А.В.
Published: January 2021

The results of an experimental study of the phonon spectrum of a LiNiPO4 single crystal by IR reflection spectroscopy are presented. The spectroscopic parameters of IR phonons are obtained. The observed number of phonons is mainly in agreement with the performed group-theoretical analysis, and the reasons for small discrepancies are discussed. With decreasing temperature, a hardening of phonon frequencies is observed, associated with temperature changes in the parameters of the crystal lattice.
Оптическая спектроскопия крамерсовских дублетов иона Er-=SUP=-3+-=/SUP=- в двумерном фрустированном магнетике Cu-=SUB=-3-=/SUB=-Er(SeO-=SUB=-3-=/SUB=-)-=SUB=-2-=/SUB=-O-=SUB=-2-=/SUB=-Cl
Authors: Климин С.А. , Бердоносов П.С. , Кузнецова Е.С.
Published: January 2021

Francisites Cu3M(YO3)2O2X (M = Bi or rare earth, Y = Se, Te, X = Br, Cl, I) attract grate attention due to their interesting magnetic properties, such as metamagnetic transitions in relatively weak magnetic fields, magnetic phase transitions including spin reorientation, as well as model systems for studying two-dimensional and frustrated magnetism. In this work, a low-temperature optical spectroscopic study is presented of erbium francisite Cu3Er(SeO3)2O2Cl. The observed splittings of the spectral lines corresponding to the f f transitions in the Kramers Er3+ ion unambiguously indicates the magnetic ordering of the crystal at a temperature TN = 37.5 K. The temperature dependence of the splitting of the main doublet of the erbium ion is determined. The contribution of erbium to the heat capacity and magnetic susceptibility of Cu3Er(SeO3)2O2Cl is calculated.
О теории плоской линзы из материала с отрицательным преломлением
Authors: Петрин А.Б.
Published: January 2021

A rigorous theory of propagation of an electromagnetic wave from a point elementary current source is considered when it is focused by a plane layer filled with a material with a negative refractive index (Veselago lens). The distributions of the electromagnetic field in the focal region are investigated and its dimensions are determined. Key theoretical questions are discussed in detail.
Наведенное двулучепреломление в квантовых точках CdSe в матрице фосфатного стекла
Authors: Красовский В.И. , Расмагин С.И.
Published: January 2021

In this paper, we report on the experimental observation of light-induced anisotropy (the optical Kerr effect) due to third-order nonlinear dielectric susceptibility (3) in a nanocomposite material consisting of CdSe quantum dots in a phosphate glass matrix. The signs and values of the off-diagonal components of the tensor (3) are determined using z-scanning techniques and nonlinear ellipsometry. It was shown that the nonlinear response contains three time components, the fastest of which does not exceed 20 ps, the average has an exponential form and amounted to 90 11 and 38530 ps for different samples, and the longest nonexponential and amounts to times of the order of a few nanoseconds. The switching of an optical signal with a time not exceeding 20 ps is demonstrated.
Генерация третьей гармоники терагерцовых волн нелинейной графеновой многослойной метаповерхностью
Authors: Лерер А.М. , Макеева Г.С. , Черепанов В.В.
Published: January 2021

The nonlinear diffraction of an electromagnetic wave by multilayer nonlinear metasurfaces consisting of rectangular graphene finite length ribbons array located on dielectric layers is studied at terahertz (THz) frequencies. It is shown that the third harmonic generation efficiency increases by several orders of magnitude at surface plasmon-polariton resonance frequencies, which can be controlled by dynamic tuning the chemical potential without changing the geometry and dimensions of the nonlinear graphene metasurface.
Предельно короткие оптические импульсы в фотонном кристалле из углеродных нанотрубок под действием внешнего поля накачки
Authors: Двужилов И.С. , Двужилова Ю.В. , Белоненко М.Б.
Published: January 2021

In this work, we considered the evolution of extremely short optical pulses in a photonic crystal of semiconductor carbon nanotubes placed in an external pumping field. The possibility of stable propagation of electromagnetic pulses under conditions of a pumping and damping field, due to the balance of dissipative forces and an external field, is shown. The stability of the shape of an extremely short optical pulse at long times is demonstrated with a change in various parameters of the medium, such as the period of inhomogeneity of carbon nanotubes in a photonic crystal and the modulation depth of the refractive index.
Определение констант скоростей и механизма фотопревращений металлопорфиринов методом решения обратной фотокинетической задачи
Authors: Станишевский И.В. , Арабей С.М.
Published: January 2021

The fluorescence kinetics of some substituted Zn- and Mg-porphyrins in solid polymer films upon excitation by two-step-wise rectangular laser pulses and 293 K were investigated by the inverse kinetic problem methods. The experimental non-monotonic kinetic curves were approximated by the simulated ones within the framework of a six-level energy scheme describing the reversible interconversions between the two complexes. The best fit between the experimental and simulated curves was obtained by iterative optimization using the Nelder-Mead algorithm. Based on the statistically estimated values ​​of the rate constants and parameters of the considered models, an interpretation of the observed kinetics was given and the conclusion drawn that the interconversions are caused by the process of reversible extra-liganding of the central metal ion, which occurs in the excited triplet T1 state.
Электрооптический отклик ячеек с разной толщиной гомеопланарных слоев нематического жидкого кристалла при наклонном падении света на слой
Authors: Каретников А.А. , Ковшик А.П. , Каретников Н.А. , Рюмцев Е.И. , Аксенова Е.В. , Сванидзе А.В.
Published: January 2021

Исследована электроуправляемая рефракция света в ячейках с различной толщиной слоя гомеопланарно ориентированного нематического жидкого кристалла (ЖК) для углов падения света на слой, превышающих угол полного внутреннего отражения обыкновенного луча deltao. Для ячеек с толщиной слоев жидкого кристалла d=7,14 и 22 μm получены зависимости времени нарастания и спада оптического отклика tauon и tauoff от напряженности электрического поля и углов падения света delta на слой ЖК. Ключевые слова: нематический жидкий кристалл, электрическое поле, рефракция.
Особенности формирования локализованных состояний вблизи плоского дефекта в средах со скачкообразно меняющимся дефокусирующим нелинейным откликом
Authors: Савотченко С.Е.
Published: January 2021

A theoretical study of the features of the localization of fields (light beam) near a plane defect in media with a stepwise defocusing nonlinearity of the Kerr type is carried out. A one-dimensional model is used based on a generalization of the nonlinear Schrödinger equation with a point potential that simulates the interaction of excitations with a plane defect, and a nonlinear term in which the coefficients of the linear and nonlinear responses abruptly change in depending on the field amplitude in the medium. It is found two types of symmetric localized stationary states in different energy ranges. The influence of the intensity of the interaction of excitations with a defect on the profile of localization of states and the conditions for their existence is studied.
Резонансное рассеяние плоских электромагнитных волн ГГЦ диапазона кольцевыми диэлектрическими линейными структурами
Authors: Шварцбург А.Б. , Василяк Л.М. , Ветчинин С.П. , Алыбин К.В. , Вольпян О.Д. , Обод Ю.А. , Печеркин В.Я. , Привалов П.А. , Чуриков Д.В.
Published: January 2021

Reverse resonance scattering on the main magnetic mode and wave properties of linear structures consisting of subwavelength dielectric elements in the form of flat thin rings excited by displacement currents of an incident plane electromagnetic wave in the microwave range are studied. It is shown that for a single ring, the magnetic field at the main resonant frequency is concentrated inside the ring and in the near zone, and for structures consisting of two or more rings, the magnetic field is also registered in the far zone. The measured main magnetic resonances in the spectrum of electromagnetic fields of one and two flat rings coincide with the calculated resonant frequencies.
Исследование особенностей формирования пленок воды на поверхности монтмориллонита и каолинита методом инфракрасной спектроскопии
Authors: Наздрачева Т.Ф. , Кухарский А.В. , Каспржицкий А.С. , Лазоренко Г.И. , Явна В.А. , Кочур А.Г.
Published: January 2021

Kaolinite (KGa-1b) and montmorillonite (STx-1b) reference samples were studied by infrared spectroscopy at various water contents. The spectral features reflecting the formation of water layers on the basal surfaces of individual minerals have been studied. Experimental studies were carried out by the Attenuated Total Reflection (ATR) Fourier Transform Infrared (FTIR) spectroscopy. The analysis of the composition of the wet samples was carried out by decomposing the experimental spectra into the spectrum of H2O and minerals in the air-dry condition. The obtained dependences of the participation coefficients of the basic spectra on humidity are compared with the results of measurements in the microwave range and make it possible to investigate the integral features of the formation of a water layer on mineral particles and to predict the plasticity of clays. The anomalous position of the maximum and the half-width of the stretching vibrational modes of water molecules at low water content have been established.
Спектральные характеристики наклонного отражательного интерферометра как сенсора показателя преломления
Authors: Терентьев В.С. , Симонов В.А.
Published: January 2021

The paper presents simulation of the refractive index sensor of the analyzed liquid in the Kretschmann configuration based on an oblique reflective interferometer (RI) and its spectral properties for the first time. The principle of operation of this sensor is based on the effect of inverted surface plasmon resonance (ISPR). The sensitive structure is the metal-dielectric multilayer coating based on a nickel thin film in combination with non-quartewavelength dielectric layers. Modeling of the RI manufacturing process under oblique light incidence is described. Formulas for estimating the sensitivity and spectral width of the reflection maximum of ISPR are given, as well as the figure of merit. It is shown that due to the high quality factor, this type of sensor can have very large figure of merit (>10^3).
Концентрация паров кадмия и время жизни верхнего рабочего уровня He-Cd-лазера с ядерной накачкой на переходе 5s-=SUP=-2-=/SUP=- -=SUP=-2-=/SUP=-D-=SUB=-5/2-=/SUB=--5p-=SUP=-2-=/SUP=-P-=SUB=-3/2-=/SUB=- Cd II
Authors: Денежкин И.А. , Дьяченко П.П. , Мешакин В.И. , Степанов С.П.
Published: January 2021

Experimental method is described and results of measurement of the cadmium vapor concentration in a nuclear pumped He-Cd laser on the cadmium ion transition with wave length 0.441 μm are presented . It is shown that observed concentration is about ten times less then saturated one for given temperature of laser cuvette. On the base of obtained data the conclusion is made that life time of the upper level for CdII 5s2 2D5/2 -5p2P3/2 transition in a optimum condition of He-Cd laser operation equals about 0.5 μs.
Эмиссионные спектры тяжелых инертных газов Kr, Xe в диапазоне 3-20 nm при импульсном лазерном возбуждении с использованием различных газовых струй в качестве мишеней
Authors: Нечай А.Н. , Перекалов А.А. , Салащенко Н.Н. , Чхало Н.И.
Published: January 2021

The article considers the results of studies of the emission spectra of Kr, Xe upon excitation by pulsed laser radiation. We used Nd: YAG laser, λ = 1064 nm, τ = 5 ns, and Epulse = 0.8 J. The spectral range of 30-200A was studied. We used capillary with d = 500 μm and supersonic conical nozzles with dcr = 145 μm, 2α = 12o, L = 5 mm, and dcrit = 450 μm, 2α = 11o, L = 5 mm to form a gas jet. The emission spectra for various gas targets were obtained, the obtained spectra were deciphered, and the ions emitting in this spectral range were determined. We observed that with increasing particle concentration in the zone of laser spark, the radiation intensity increases. In this case, the intensity of ion lines with high degrees of ionization increases faster.
Взаимосвязь между молекулярной динамикой полистирола и его модификаций и параметрами терагерцового поглощения в ИК спектрах
Authors: Рыжов В.А.
Published: January 2021

The IR spectra of polystyrene (PS) and its modifications obtained by replacing hydrogen atoms in the benzene ring with methyl groups and / or chlorine and bromine atoms have been measured and analyzed. All these spectra have an anomalously wide asymmetric absorption band with a maximum in the terahertz range from 40 to 80 cm – 1, depending on the nature of the substituent. It can be attributed to absorption associated with libration (rotational vibrations) of phenolic rings of monomer units, i.e., to absorption by the Poly mechanism. The relationship between the spectral parameters of this absorption and the molecular characteristics of the studied polymers makes it possible to directly analyze the role of the molecular structure and intermolecular forces in the dynamics of their macromolecules. It was found that the heights of potential barriers to libration of monomeric units of PS and its modifications, estimated from the analysis of Poly absorption, are close to the activation energies of low-temperature delta-relaxation in these glassy polymers. Comparison of the barriers to libration of monomeric units of macromolecules of PS and its modifications with the activation barriers of local segmental mobility in the same PS confirms that the beta process as an elementary act of segmental dynamics is caused by correlated librational movement of the chain section, which is statistically independent of neighboring regions. In this sense, the universal delta process is a high-frequency precursor of the beta process in polymers like PS.
Наблюдение когерентных осцилляций населенности NV-центров в алмазе в микроволновом диапазоне
Authors: Ахмеджанов Р.А. , Гущин Л.А. , Зеленский И.В. , Низов В.А. , Низов Н.А. , Собгайда Д.А.
Published: January 2021

We demonstrate experimental results showing narrow features in room temperature optically detected magnetic resonance spectra that appear when the ground state transitions are driven by bichromatic or amplitude modulated microwave radiation. We study the dependence of the feature parameters on the intensity of optical radiation and microwave radiation power.
Оптимизация параметров и характеристик широкополосных терагерцовых поглотителей на основе 2d-решеток графеновых лент на многослойных подложках
Authors: Лерер А.М. , Иванова И.Н. , Макеева Г.С. , Черепанов В.В.
Published: January 2021

A multilayer two-dimensional periodic arrays of graphene micro-ribbons, which absorbs almost 100% of the energy of incident wave at the resonance of the surface plasmon-polariton, has been theoretically investigated. To increase the bandwidth of the absorbers, it is proposed to place 2-3 parallel graphene ribbons with close lengths in the unit cell of the 2d array.
Калибровка температуры по нормированным спектрам АП-конверсионной флуоресценции германатных стекол и стеклокерамик, активированных ионами эрбия и иттербия
Authors: Асеев В.А. , Борисевич Д.А. , Ходасевич М.А. , Кузьменко Н.К. , Федоров Ю.К.
Published: January 2021

To select erbium and ytterbium doped germanate glasses and glass ceramics, which are most suitable as sensitive elements of fluorescent temperature sensors, a multivariate model of temperature calibration has been developed based on principal component analysis, cluster analysis and interval projection to latent structures of up-conversion green fluorescence spectra. The calibration model used 95 spectral variables for the GeO2-Na2O-Yb2O3-MgO-La2O3-Er2O3 glass-ceramic is characterized by the best quality parameters: the root-mean-square error is 0.37 K, the residual prediction deviation for the test subset is greater than 102, and the relative error does not exceed 0.20%.
Спектры электролюминесценции и структура анодного оксида алюминия при его формировании в химически чистой воде и спиртах
Authors: Овеченко Д.С. , Бойченко А.П.
Published: January 2021

For a film of aluminum oxide (Al2O3) formed in distilled water (H2O), a linear growth was revealed during the high-voltage anodization time of 2000 s, and it was found that its electroluminescence (EL) is reliably recorded at an Al2O3 thickness of about 120 nm. It is shown that in DV and its deuterium-containing analogue, deuterium water (D2O), the electrolysis formation of Al2O3 is possible.
cellular-nanoporous structure, identical to that formed in aqueous solutions of electrolytes. It was found that the presence of such a structure in the oxide is not a prerequisite for the generation of its EL. The EL spectrum of Al2O3 in H2O and D2O, as well as in “water-like” electrolytes: ethylene glycol, N, N-dimethylethanolamine, and isopentanol, was recorded for the first time. In the investigated range of 400–700 nm, significant differences in the luminescence in water and the above alcohols are revealed. For EL, the short-wavelength component with a wavelength of the order of 440 nm dominates in water, and in alcohols, the long-wavelength component with a maximum at 625 nm. In this case, nonstationarity of luminescence is observed both in the spectral composition and in the intensity of individual parts of the spectrum for the entire time of aluminum anodization.
La conciencia de la presencia como clave para la renovación de la experiencia espiritual hoy:
Authors: Solano Pinzón Orlando , Navarro Sánchez Rosana , Gómez Díaz Jairo , Peña Esquivel William Augusto , Jaramillo Vargas Gabriel Alberto
Published: January 2021

Due to the crisis of traditional mediations of religious experience, we are witnessing a more and more generalized spiritual search, derived from the tendency to ultra-individualism, with the aim of self-realization. In response to such a situation, this writing collects the results of an investigation that, with the background of the intuition of the mystical future of humanity, approaches the experience of six spiritual witnesses of yesterday and today: Gregory of Nyssa, Ignatius of Loyola, Teresa of Jesus, Etty Hillesum, Laura Montoya, and Benjamín González Buelta. The approach investigated the characteristics of the mystical experience, understood as awareness of presence, to identify keys capable of contributing to the renewal of spiritual experience today.