bluuebunny/crossref_metadata_2025 huggingface dataset:
Revisando un órgano olvidado: Evaluación del timo en PET-CT
Authors: Hasson Daniel , Schiappacasse Giancarlo , Alegría Julia , Silva Claudio
Published: April 2020

La pesquisa incidental de lesiones tímicas ha aumentado. Una adecuada aproximación a esas lesiones en la tomografía computada por emisión de positrones (PET-CT) es fundamental, pues se usa como parte de la mayoría de los procedimientos de planificación oncológica. Se han seleccionado casos representativos respecto de los aspectos más importantes de las imágenes de timo en PET-CT y cómo esa técnica puede contribuir a un diagnóstico preciso o a la planificación del tratamiento. Específicamente, presentamos una descripción general de las lesiones tímicas comunes y los imitadores de enfermedad, con énfasis en los hallazgos en PET-CT, incorporando también ejemplos de resonancia magnética (RM).
EFFECTIVENESS OF INTRA OPERATIVE HAND HOLDING ON ANXIETY AND PHYSIOLOGICAL PARAMETERS AMONG PATIENTS UNDERGOING CATARACT SURGERY
Authors: S. Anuja B. , Devi Elsa Sanatombi , Sequira Leena , Rao Lavanya , H. Vijaya Pai
Published: April 2020

Introduction: Patients who are undergoing cataract surgery under local anaesthesia may be more stressed than those having general anaesthesia as they are awake during the surgical procedure. Therefore, psychological comfort in the preoperative phase and compliance during operation are very important for postoperative prognosis. This study explored the pre operative anxiety level of patients undergoing cataract surgery and the effectiveness of intra operative hand holding on anxiety and its related physiological parameters.

Methods: A quasi experimental pre-test post-test control group design was used to collect data from a purposive sample of 54 patients who were underwent cataract surgery at Kasturba Hospital, Manipal.

Results: Most of the patients in the experimental group perceived intra operative hand holding as a measure to reduce their anxiety even though there was no significant statistical difference in the immediate post operative anxiety score between the groups. It was also found that hand holding was effective in reducing blood pressure and heart rate except the respiratory rate of patients undergoing cataract surgery.

Conclusion: The following conclusions were drawn on the basis of the findings of the present study that is, Intra operative hand holding was effective in reducing the physiological parameters such as heart rate, systolic blood pressure and diastolic blood pressure. Also most of the patients perceived intra operative hand holding as beneficial in relieving anxiety.
A STUDY ON OCCURRENCE OF SOCIAL ANXIETY AMONG NURSING STUDENTS AND ITS CORRELATION WITH PROFESSIONAL ADJUSTMENT IN SELECTED NURSING INSTITUTIONS AT MANGALORE
Authors: R. Reghuram , Mathias Jesveena
Published: April 2020

The concept of social fear dates back as early as 400 B.C. Anxiety is a normal human response to stress. This study, conducted in selected nursing institutions of Mangalore, assessed the Social Anxiety and correlated it with Professional adjustment among nursing students. The tools used in the study were Social anxiety scale and a rating scale measuring Professional adjustment. 1000 students were selected by purposive sampling. The study findings revealed that 274(27.4%) of subjects have moderate social anxiety and 768(76.8%) having average professional adjustment. There was no significant correlation between social anxiety and professional adjustment. But, there was significant association between social anxiety and selected variables like gender and year of study.
KNOWLEDGE AND PRACTICES OF POSTNATAL MOTHERS ON NEWBORN CARE IN TERTIARY CARE HOSPITAL OF UDUPI DISTRICT
Authors: F. Castalino , S. Nayak B. , A. D'Souza
Published: April 2020

A descriptive correlational survey to assess knowledge and practice of postnatal mothers on newborn care was carried out among 30 mothers using valid, reliable, structured knowledge and practice questionnaire. The collected data was analyzed using SPSS version 16. The findings of the study showed that most of the sample 24(80%) were in the age group 21-30 years, most of them 16(53.3%) were primipara, 15(50%) had normal vaginal delivery and 15 (50%) had LSCS. Majority of the sample 25 (83.3%) belonged to Hindu religion, most of them 19 (63.3%) belonged to joint family, most the samples 17 (56.7%) lived in a rural area, majority of the mothers 17 (56.7%) were housewives. Majority of the new- borns, 24 (80%) were above 37 weeks of gestation, most of the new born 21(70%) were below 6 days of age, majority of the new born 19(63.3%) were male, majority of newborn 16(53.3%) were above 3000 grams of birth weight. Majority 23 (76.7%) of mothers had good knowledge on new-born care. Most of 16 (53.33%) of mothers had excellent practice on newborn care. Relationship between knowledge and practice score of the mother was not statistically significant at 0.05 level (r=0.276, p=0.140). The education of the mothers (x2(df) =11.642(3), p=0.009) had significant association with the knowledge of the mother regarding new-born care. Keeping in mind the findings of the study it is recommended that an educational programme regarding newborn care can be organized to the antenatal and postnatal mothers
EFFECTIVENESS OF A LIFESTYLE MANAGEMENT PROGRAM ON KNOWLEDGE AND LIFESTYLE PRACTICES AMONG ADOLESCENTS
Authors: S. Elstin Mary , D'souza Anjalin , Roach Erna Judith
Published: April 2020

Increasing incidence of lifestyle disorders among Indians are largely attributed by unhealthy lifestyle practices like poor dietary pattern, inadequate physical activity, smoking, alcohol consumption and stress. Lifestyle modification programs are proved effective in behaviour modification and promotion of healthy lifestyle practices among adolescents. A school based interventional study was conducted among adolescents with the objective determine the effectiveness of the lifestyle management program in terms of gain in knowledge on lifestyle disorders and change in self-reported lifestyle practices. The study was conducted in two phases. Initially, a baseline data on the lifestyle practices and knowledge on lifestyle disorders was obtained from the adolescents, which was utilized to select the adolescents with poor and average knowledge and unhealthy practices for whom the intervention was implemented. Changes in lifestyle disorder related knowledge and lifestyle practices were tested using a structured knowledge questionnaire and lifestyle assessment scale. After two weeks of the intervention, a post-test was carried out and a significant improvement in knowledge (Z= 12.39, P = 0.001) and lifestyle practice (Z= 5.52, P = 0.001) were identified. The educational package for lifestyle modification was successful in improving the knowledge on lifestyle diseases and lifestyle practices among adolescents and thereby in prevention of lifestyle disorders.
Consecutive Use of the 52 mg Levonorgestrel-releasing Intrauterine System: Variations in Bleeding Patterns
Authors: Wittmann Barbara Zantut , Monteiro Ilza , Juliato Cássia , Fernandes Arlete
Published: April 2020

Objective Changes in bleeding patterns could influence the decisions of healthcare professionals to change the levonorgestrel-releasing intrauterine system (LNG-IUS) before 7 years of use, the recommended period of extended use. We evaluated changes in the bleeding patterns of users of the 52 mg LNG-IUS at the end of use of the first (IUS-1) and during the second device (IUS-2) use.

Methods We performed an audit of the medical records of all women who used two consecutive LNG-IUSs at the Family Planning clinic. We evaluated the sociodemographic/gynecological variables, the length of use, and the bleeding patterns reported in the reference periods of 90 days before removal of the IUS-1 and at the last return in use of IUS-2. We used the McNemar test to compare bleeding patterns. Statistical significance was established at p < 0.05.

Results We evaluated 301 women aged (mean ± SD) 32 (±6.1) years, with lengths of use of 68.9 (±16.8) and 20.3 (±16.7) months for the IUS-1 and IUS-2, respectively. No pregnancies were reported. Bleeding patterns varied significantly among women who used the IUS-2 for ≥ 7 months to 6 years when compared the bleeding patterns reported in IUS-1 use. Eighty-nine out of 221 (40%) women maintained amenorrhea and infrequent bleeding; 66 (30%) evolved to bleeding patterns with light flow, and 66 (30%) maintained or evolved to heavy flow patterns (p = 0.012). No differences were observed among the 80 women with ≤ 6 months of use.

Conclusion Changes in bleeding patterns occur during the use of LNG-IUS and should not be decisive for the early replacement of the device.
Effect of Tinnitus Habituation Therapy on Auditory Abilities
Authors: Burle Najlla Lopes de O. , Resende Luciana Macedo de , Alves Luciana Mendonça , Garcia Vinícius Soares , Mancini Patricia Cotta
Published: April 2020

Introduction Research with tinnitus patients presenting with hearing loss and normal hearing subjects have verified that tinnitus interferes with auditory processing. One treatment option for this symptom consists of tinnitus habituation therapy.

Objective To determine the influence of tinnitus habituation therapy on auditory abilities, on the self-perception of tinnitus regarding loudness and discomfort, and its impact on the quality of life.

Methods A quasi-experimental study was conducted with 19 individuals with tinnitus. Audiological tinnitus and auditory processing evaluations were performed. Subsequently, the volunteers underwent tinnitus habituation therapy for 6 months. Ultimately, all of the individuals were reevaluated.

Results A statistically significant reduction in tinnitus self-perception was observed in relation to loudness, discomfort, and its impact on the quality of life (p = 0.001, 0.001, 0.023, respectively). However, the influence of tinnitus habituation therapy on auditory abilities was not verified.

Conclusion Tinnitus habituation therapy was effective in reducing the self-perception of tinnitus loudness and discomfort, as well as the impact of the symptom on the quality of life. However, these factors did not improve the auditory processing skills in tinnitus patients.
Evaluation of Auditory Stream Segregation in Musicians and Nonmusicians
Authors: Johnson Naina , Shiju Annika Mariam , Parmar Adya , Prabhu Prashanth
Published: April 2020

Introduction One of the major cues that help in auditory stream segregation is spectral profiling. Musicians are trained to perceive a fine structural variation in the acoustic stimuli and have enhanced temporal perception and speech perception in noise.

Objective To analyze the differences in spectral profile thresholds in musicians and nonmusicians.

Methods The spectral profile analysis threshold was compared between 2 groups (musicians and nonmusicians) in the age range between 15 and 30 years old. The stimuli had 5 harmonics, all at the same amplitude (f0 = 330 Hz, mi4). The third (variable tone) has a similar harmonic structure; however, the amplitude of the third harmonic component was higher, producing a different timbre in comparison with the standards. The subject had to identify the odd timbre tone. The testing was performed at 60 dB HL in a sound-treated room.

Results The results of the study showed that the profile analysis thresholds were significantly better in musicians compared with nonmusicians. The result of the study also showed that the profile analysis thresholds were better with an increase in the duration of music training. Thus, improved auditory processing in musicians could have resulted in a better profile analysis threshold.

Conclusions Auditory stream segregation was found to be better in musicians compared with nonmusicians, and the performance improved with an increase in several years of training. However, further studies are essential on a larger group with more variables for validation of the results.
Pubic Arch Angle Measurement by Transperineal Ultrasonography: A Prospective Cross-Sectional Study
Authors: Carvalho Neto Raimundo Homero , Viana Junior Antonio Brazil , Moron Antonio Fernandes , Araujo Júnior Edward , Carvalho Francisco Herlânio Costa , Feitosa Helvécio Neves
Published: April 2020

Objective To evaluate the ability of the pubic arch angle (PAA) as measured by transperineal ultrasonography during labor to predict the delivery type and cephalic pole disengagement mode.

Methods The present prospective cross-sectional study included 221 women in singleton-gestational labor ≥ 37 weeks with cephalic fetuses who underwent PAA measurement using transperineal ultrasonography. These measurements were correlated with the delivery type, cephalic pole disengagement mode, and fetal and maternal characteristics.

Results Out of the subjects, 153 (69.2%) had spontaneous vaginal delivery, 7 (3.2%) gave birth by forceps, and 61 (27.6%) delivered by cesarean section. For the analysis, deliveries were divided into two groups: vaginal and surgical (forceps and cesarean). The mean PAA was 102 ± 7.5° (range, 79.3–117.7°). No statistically significant difference was observed in delivery type (102.6 ± 7.2° versus 100.8 ± 7.9°, p = 0.105). The occipitoanterior position was seen in 94.1% of the fetuses and the occipitoposterior position in 5.8%. A narrower PAA was found in the group of surgical deliveries (97.9 ± 9.6° versus 102.6 ± 7.3°, p = 0.049). Multivariate regression analysis showed that PAA was a predictive variable for the occurrence of head disengagement in occipital varieties after birth (odds ratio, 0.9; 95% confidence interval, 0.82–0.99; p = 0.026).

Conclusion Ultrasonographic measurement of the PAA was not a predictor of delivery type, but was associated with the persistence of occipital varieties after birth.
Bayesian statistics-based analysis of AC impedance spectra
Authors: Miyazaki Yu , Nakayama Ryo , Yasuo Nobuaki , Watanabe Yuki , Shimizu Ryota , Packwood Daniel M. , Nishio Kazunori , Ando Yasunobu , Sekijima Masakazu , Hitosugi Taro
Published: April 2020

AC impedance spectroscopy is an important method for evaluating ionic, electronic, and dielectric properties of materials. In conventional analysis of AC impedance spectra, the selection of an equivalent circuit model and its initial parameters are visually determined from a Nyquist plot; this visual determination can be both inefficient and inaccurate. Thus, analysis based on a rigorous mathematical method is highly desirable. Here, we demonstrate the analysis of AC impedance spectra using Bayesian statistics. We apply the method to artificial AC impedance spectra generated from resistance (R) and capacitance (C) circuits, obtaining a high accuracy ratio (>90%) in model selection when the ratio of the time constants of two RC parallel circuits exceeds 3. Furthermore, this method is applied to an actual electrical circuit comprising a resistance and two RC parallel circuits, yielding highly accurate model selection and parameter estimation. The results demonstrate the effectiveness of the proposed method for AC impedance spectra.
Influence of spatial arrangements of roughness elements on turbulent Rayleigh-Bénard convection
Authors: Dong Dao-Liang , Wang Bo-Fu , Dong Yu-Hong , Huang Yong-Xiang , Jiang Nan , Liu Yu-Lu , Lu Zhi-Ming , Qiu Xiang , Tang Zhan-Qi , Zhou Quan
Published: April 2020

Turbulent Rayleigh-Bénard convection in a square cavity with rough horizontal walls is investigated at a fixed Prandtl number Pr = 0.7 over the Rayleigh number range of 106 ≤ Ra ≤ 109. We have proposed five models with rough elements of the same height but different spatial distributions to evaluate their influences on the heat transport and flow structures of the system. It is found that the flow reversal can be promoted at a Rayleigh number around 107. In all the rough models, the heat transfer is impeded at a low Ra and enhanced at a Rayleigh number beyond a critical value. Interestingly, the heat transfer and flow structure can be clustered by the sparsity of the rough element distribution. Different scaling exponents for heat transfer are identified for sparsely distributed rough models and compactly distributed models. On the other hand, the spatial distribution of rough elements has little effect on the scaling of the Reynolds number.
Flexible engineering of light emission in monolayer MoS2 via direct laser writing for multimode optical recording
Authors: Qin Chengbing , Gao Yan , Zhang Lei , Liang Xilong , He Wenjun , Zhang Guofeng , Chen Ruiyun , Hu Jianyong , Xiao Liantuan , Jia Suotang
Published: April 2020

Direct laser writing has been proved to be capable for effective modulation of optical and electrical properties of various nanomaterials. In this work, we designed a flexible direct laser writing approach to engineer photoluminescence (PL) properties of monolayer MoS2 and present its potential application in optical recording. PL spectra evolution of monolayer MoS2 under continuous-wave laser writing has been explored, where its PL energy can be precisely controlled by changing the writing time. This feature enables a multimode optical recording with spectral contrast in monolayer limit materials for high-capacity data storage technologies. Here, we constructed a proof-of-principle multimode optical recording on monolayer MoS2 based on the PL wavelength division multiplexing scheme and discussed the relevant challenges for practical applications. Our flexible approach with a mask-free feature and high spatial resolution is promising for applications in two-dimensional material-based information storage and optoelectronic devices.
Newtonian and viscoelastic fluid flows through an abrupt 1:4 expansion with slip boundary conditions
Authors: Ferrás L. L. , Afonso A. M. , Alves M. A. , Nóbrega J. M. , Pinho F. T.
Published: April 2020

In this work, we present a systematic numerical investigation of the 1:4 planar expansion creeping flow under the influence of slip boundary conditions for Newtonian and viscoelastic fluids, the latter modeled by the simplified Phan–Thien–Tanner constitutive model. The linear and nonlinear Navier slip laws were considered with the dimensionless slip coefficient kl* varying in the range 0, 4500 and the slip exponents m = 0.5, 1, and 2. The simulations were carried out for a low Reynolds number, Re = 0.001, and for Deborah numbers (De) between 0 and 100. Convergence could not be achieved for higher values of the Deborah number and large values of the slip coefficient due to the large stress gradients near the singularity point (reentrant corner). The results obtained allow us to conclude that for all De, the increase in slip velocity leads to vortex suppression. The flow characteristics are described in detail for low values of the Deborah number, De ≤ 5, while for higher De the main features are only shown for specific values of the slip coefficient. These results find application in polymer processing, where the use of lubricants that migrate to the wall is common, which promotes slip.
Optically tunable single narrow band all-dielectric terahertz metamaterials absorber
Authors: Wang Yue , Yue Lisha , Cui Zijian , Zhang Xiaoju , Zhang Xiang , Zhu YongQiang , Zhang Kuang
Published: April 2020

In this work, we numerically demonstrated a single narrow band THz absorber based on cylindrically shaped periodical p-type doped silicon with excellent attributes, including polarization insensitivity and optical tunability. Good absorption characteristics were demonstrated at 0.57 THz with an absorption of nearly 99.75% and a quality factor of 11.278. Furthermore, its absorbance could be flexibly tuned from above 99% to less than 35% by changing the pump beam fluence from 0 µJ/cm2 to 3000 µJ/cm2. The demonstrated tunability may find potential applications in dynamic functional THz devices.
Marine and estuarine leeches (Hirudinida : Ozobranchidae and Piscicolidae) of Australia and New Zealand with a key to the species
Authors: Burreson Eugene M.
Published: April 2020

Marine leeches are sanguivorous parasites either on sea turtles (family Ozobranchidae) or on elasmobranch and teleost fishes (family Piscicolidae), with the exception of Mysidobdella, which may feed on mysid shrimp. The marine leeches of Australia and New Zealand are poorly known, especially those on teleost fishes. Collections of marine leeches from all major museums in Australia and New Zealand were examined, as well as many specimens sent to the author. Ozobranchus branchiatus and O. margoi were found on sea turtles in Australia. Seven genera and 14 species of fish leeches were found in Australia; 6 genera and 10 species of fish leeches were found in New Zealand. Two genera (Pontobdella and Branchellion) and four species (P. leucothela, P. moorei, B. australis and B. plicobranchus) occur in both Australia and New Zealand. No genus is endemic to Australia, but four species are endemic based on current records (Austrobdella bilobata, Austrobdella translucens, Trachelobdella leptocephali and Pterobdella platycephalus). Two genera (Bdellamaris and Leporinabdella) and three species (B. manteri, B. eptatreti, and L. digglesi) are endemic to New Zealand based on current records. The marine leeches of Australia and New Zealand are a mix of endemic species, those of tropical or subtropical origin, and those of subantarctic origin.
Sprache der Nähe vs. Sprache der
Distanz and the nineteenth century codification of
Modern Czech
Authors: Fidlerová Alena A.
Published: April 2020

The paper examines the conceptual clashes between two
approaches to the standardisation of modern Czech during the Czech
National Revival. It reconstructs conceptual differences between the
partially usage-based approach of František Jan Tomsa and the
historical approach of Josef Dobrovský and František Martin Pelcl.
By pointing out their explicit and implicit arguments and with the
help of the concept of Sprache der Nähe [language
of immediacy] and Sprache der Distanz [language of
distance] developed by Koch and Oesterreicher, it proposes an
explanation for these differences, for the rejection of the
usage-based model by the next generation and for its attractiveness
to future generations.
Coherence
Authors: Givón T.
Published: April 2020

Coherence, connectivity and the fitting together of smaller parts into larger structures and a coherent whole is the hallmark of complex biologically-based systems. As a structure-internal constraint, coherence makes it possible for the parts to work together as a whole. As an external constraint, it lets complex system evolve and adapt to novel contexts. As a constraint on information processing, it makes new knowledge accessible to the maturing, learning or evolving mind-brain. As a constraint on cultures, it enables members of social groups to be empathic and cooperative. As a constraint on language and communication, lastly, it allows the mind of speakers to be accessible to the mind of hearers.

Part I explores first the role of coherence in the evolution of complex biological design, from precellular to mono-cellular to multi-cellular to multi-organ sentient beings. The complex hierarchic design of the mind-brain is explored next, probing the coherent organization of major brain systems—perception, attention, motor control, memory and language. In surveying the coherence of cultures next, the first-evolved Society of Intimates is viewed as the model for social cohesion, empathy, trust and cooperation. Part II deals with language and communication, touching upon the coherent organization of semantic memory, event clauses and clause chains, and the central role of grammar in coherent communication. Part III deals with three general issues. First, the role of coherence in organized science. Second, the eternal seesaw of selfish vs. social motivation in coherently functioning cultures. And last, the frail balance between homogeneity and diversity in large-scale Societies of Strangers.
A multiscale-indentation study of deformation and fracture in 6H polycrystalline silicon carbide
Authors: Zhang D. , Zhao L. G. , Roy A.
Published: April 2020

The mechanical behaviour of a polycrystalline silicon carbide across length scales was studied using Vickers indentation, focusing on the hardness, fracture toughness and failure mechanism of the material. For macroscopic and microscopic indentations, the hardness decreased with an increase in load, which was associated with the well-known indentation size effect as well as the internal flaws. For nanoindentation, severe plastic deformation was discovered beneath the imprints on the basal plane (0001) which is the most favourable crystallographic plane for dislocation movement. Alternative sources of plastic deformation, including deformation twinning and stacking faults, were found for nanoindentations with an increased load. Also, cracking was observed for indents made at 100 mN and above, which was used to study the fracture toughness.
Exploring fabrication methods to highly sensitive and selective InP nanowire biosensors
Authors: Zavarize Mariana , Martins Murilo N. , von Zuben Antonio A.G. , Koledov Victor , Gratowski Svetlana von , Cotta Mônica A.
Published: April 2020

Fabrication methodologies for integration of nano-objects into microscale devices is still an active area of research. Here we analyze possible methods of incorporation of semiconductor nanowires into lithographically-defined electrode pads. Mechanically-transferred InP nanowires were metallized into Au and Pt pads using a electron-beam-induced Pt metallization. Atomic and Kelvin Probe Force Microscopies show that a contamination of Pt on the nanowire and the region around it can prevent application of this technique to biosensors in which surface functionalization protocols must be applied as part of the fabrication methodology. Other transfer methods with more controlled nanowire positioning, such as nanotweezers, may be necessary to overcome this problem.
Strong coupling of excitons in 2D MoSe2/hBN heterostructure with optical bound states in the continuum
Authors: Benimetskiy F. A. , Kravtsov V. , Khestanova E. , Mukhin I. S. , Sinev I. S. , Samusev A. K. , Shelykh I. A. , Krizhanovskii D. N. , Skolnick M. S. , Iorsh I. V.
Published: April 2020

We experimentally demonstrate strong exciton-photon coupling in a MoSe2/hBN heterostructure interfaced with an all-dielectric metasurface supporting high-Q bound states in the continuum. The resulting exciton-polaritons are probed by means of temperature- and angle-resolved reflectivity and photoluminescence. Our findings pave the way towards new-generation nonlinear planar polaritonic devices.
Immobilization and plasmon-enhanced fluorescence of EGFP on Al nanohole arrays
Authors: Bochenkov V E , Shakhov A M , Astafiev A A , Timoshenko V A
Published: April 2020

Enhanced Green Fluorescent Protein has been covalently immobilized on thin perforated Al films with short-order nanohole arrays using (3-Glycidyloxypropyl)trimethoxysilane and native aluminum oxide layer. The nanoholes’ diameter varied in range 60–120 nm, allowing to tune the surface plasmon resonance frequency. The fluorescence intensity enhancement up to factor 2.75 for the nanohole arrays with the largest overlap between EGFP fluorescence band and surface plasmon resonance.
Adaptive mesh for computation of electromagnetic wave propagation through high refractive index dielectric structures
Authors: Dombrovskaya Zh O , Belov A A , Govorukhin V A
Published: April 2020

We consider spatial step selection for finite-difference solution of Maxwell’s curl equations in presence of dielectric interfaces. If the contrast of the refractive indices is high, the wave number in optically thick medium decreases greatly and the fields oscillate fast. To improve accuracy, we propose a special quasi-uniform mesh which provides fine enough meshes in the vicinity of the interface and does not impose abundant computations in optically thin medium. The fundamental advantage of quasi-unform meshes in finite-difference is the possibility to obtain the solution simultaneously with its error value. We describe the corresponding procedure.
Electromagnetic crystal with half-wave vibrators sublattice
Authors: Fediy Alexander A , Anzulevich Anton P , Kalganov Dmitrii A , Bychkov Igor V
Published: April 2020

Volumetric metamaterials with a regular structure can have elemental structural cells that translation along coordinate axes simulates the entire structure of macroscopic sample. If there are elements in this metamaterial that are responsible for electrical and magnetic properties, then we can say that this is an electromagnetic crystal. Samples that electrical (effective permittivity) properties are determined by long conductors, and magnetic ones - by half-wave vibrators, were investigated. Measurements of transparency spectra and forbidden electromagnetic band gap were carried out in the frequency range of 8 - 12 GHz. Measurements of refractive index in the material were carried out on the angular deviation of microwave radiation passing through a prism. Measurements show that samples with the same structure (unit cell) can significantly change their characteristics even with a small change in one of the internal parameters of the cell.
Controllable antiphase domain density in dilute nitride GaPN/GaP heterostructures on silicon
Authors: Fedorov V.V. , Bolshakov A.D. , Koval O.Yu. , Sapunov G.A. , Sobolev M.S. , Pirogov E.V. , Kirilenko D.A. , Mozharov A.M. , Mukhin I.S.
Published: April 2020

Formation and propagation of the antiphase domains in dilute nitride GaPN/GaP epitaxial heterostructures grown on Si (001) by plasma assisted molecular beam epitaxy (PA-MBE) on silicon is studied. Role of the layer composition, substrate orientation and growth conditions are discussed. Composition of the dilute nitride film was studied by X-ray diffraction (XRD) while the effect of the antiphase disorder in GaP buffer layer on GaPN epilayer structural properties was studied by transmission electron (TEM) and scanning electron microscopy (SEM). Controllable transition between antiphase disordered and monodomain film depending on the concentration of incorporated nitrogen is demonstrated – transition to the monodomain film occurs in dilute nitride GaPN layers starting low with 0.4% of incorporated nitrogen. Control of the antiphase disorder allows to tune mean film polarity and second order nonlinear optical response of III-phosphide heterostructures.
Second harmonic generation driven by magnetic dipole moment in dielectric nanoparticles of different shapes.
Authors: Frizyuk Kristina , Petrov Mihail
Published: April 2020

In this work we suggest a technique helping to identify the selection rules in second harmonic generation from dielectric nanoparticles pumped at their magnetic dipole resonance. We present the identified mode content of the second harmonic field for nanostructures of cylindrical, cone, and prism shapes made of material with Td
and C
4v
symmetries. This method is applicable for finding the selection rules for arbitrary particle shapes and crystalline structures and can be expanded to other nonlinear processes.
Directing light with liquid crystal metasurfaces
Authors: Gorkunov M V , Kasyanova I V , Artemov V V , Mamonova A V , Ezhov A A , Palto S P
Published: April 2020

Liquid crystal metasurfaces self-assemble on polymer substrates regularly patterned by focused ion beam. Periodic deformations of nematic liquid crystal produce distinct colouring and strong diffraction. Applying AC voltage of 4 V across the liquid crystal layer straightens the nematic, suppresses diffraction and increases direct transmission within sub-millisecond switching times. Multi-parametric optimization of the metasurface design substantially enhances the efficiency of diffraction into a single particular channel.
Subwavelength vaterite spherulite scattering properties in optical region
Authors: Gurvitz Egor , Noskov Roman , Shalin Alexander
Published: April 2020

Vaterite is a very promising material for biological applications, but its electromagnetic properties have not been studied well enough. In this work we for the first time introduce multipole decompositions of subwavelength nanoparticles for dark field microscopy in optical range.
Volume metasolenoid-based coil for 23Na MRI at 7 Tesla
Authors: Solomakha G. , Hurshkainen A. , Glybovski S. , Andreychenko A.
Published: April 2020

In this work, we demonstrate a novel X-nuclei radiofrequency coil design aimed for ultra-high field magnetic resonance imaging. The proposed design is based on a set of coupled split-loop resonators, forming a so-called metasolenoid, fed via inductive coupling by a non-resonant loop. Due to the fundamental mode excitation in the metasolenoid the homogeneous RF magnetic field inside its inner volume is provided. 23Na RF coil for human wrist imaging at 7 Tesla based on the proposed approach is demonstrated and investigated numerically. The design is compared with a commercially available volume birdcage coil. The comparative study revealed 60% improvement of SAR efficiency of metasolenoid coil operating in the linearly-polarized mode over the birdcage coil driven in the circularly polarized mode.
Multifunctional Scaffolds Based on Piezoelectric Electrospun Fibers modified with Biocompatible Drug Carriers for Regenerative Medicine
Authors: Karpov Timofey E , Muslimov Albert R , Zyuzin Mikhail V , Peltek Oleksii O , Sergeev Igor S , Goncharenko Alexander A , Surmenev Roman A. , Timin Alexander S
Published: April 2020

The incorporation of bioactive compounds onto polymer fibrous scaffolds is essential to improve the functionality of scaffolds for personalized drug therapy and regenerative medicine. In this study, SiO2 microcapsules were prepared and used as drug carriers, which are further deposited onto polymer microfiber scaffolds [polycaprolactone (PCL), poly(3-hydroxybutyrate) (PHB), and PHB doping with the conductive polyaniline (PANi) of 2 wt % (PHB-PANi)]. The number of immobilized microcapsules decreased with the increase of their ζ-potential due to the electrostatic repulsion forces between capsule wall and the negatively charged fiber surface, given the nature of the polymer used for the scaffold’s fabrication. Additionally, the immobilization of the capsules in dynamic mechanical conditions resulted in an increased number of the capsules attached on the fibers with the increasing of the scaffold piezoelectric response (PCL < PHB < PHB-PANi). Osteogenic factor dexamethasone (DEXA) is chosen for the microcapsules loading in order to demonstrate the osteogenesis of the developed scaffolds. The immobilization of microcapsules provides a simple and convenient way to incorporate bioactive compounds onto polymer scaffolds, which makes these multimodal materials suitable for the personalized drug therapy and bone tissue engineering.
Light interaction with nanoresonators: mode volume and quasinormal mode expansion
Authors: Lalanne P , Yan W
Published: April 2020

The most general motion of a system is a superposition of its normal modes, or eigenstates. For Hermitian system, classical normal mode theory applies. For non-Hermitian systems, presently a lot of progress is done to describe the response of optical micro and nanoresonators in their quasinormal mode basis. We have developed a rigorous modal analysis of nanoresonators with unprecedented generality and report numerical results for the general case of 3D resonators, made of dispersive materials on substrate with guiding layers.
1H MRS as a novel quantitative method for osteoporosis detection
Authors: Menshchikov P E , Ivantsova A S , Akhadov T A , Ublinskiy M V , Manzhurtsev A V , Semenova N A
Published: April 2020

Bone mineral density is an important parameter that determines strength of the bone. Decrease in bone mineral density (BMD) leads to dangerous skeletal diseases like osteopenia, osteoporosis and an increased risk of fractures, for instance compression vertebral fracture (CVF). Dual-energy x-ray absorptiometry (DXA) and quantitative CT (QCT) are commonly accepted methods for assessing of the BMD. Previously FF was shown to increase in adult patients with osteoporosis as compared to healthy volunteers. The aim of the study was to explore the relationship between FF and BMD in children. Correlation analysis revealed significant inverse correlation link (p<0.05) between FF and BMD for all vertebrae of all patients (Fig.1C). The correlation suggests that the processes of increasing FF in the bone marrow and lowering the BMD are parallel in children. Therefore, 1H MRS could be good alternative to QCT and DXA without radiation dose in osteoporosis detection. Revealed significant negative correlation between FF and BMD in children without osteoporosis suggests that the processes of increasing FF in the bone marrow and lowering the BMD are parallel. Therefore, 1H MRS could be good alternative to QCT and DXA without radiation dose in osteoporosis detection.
Glia-neuronal transitions in development: significance in medical research and treatment of pathologies
Authors: Kamenev D , Kotsyuba E , Kalachev A , Milichko V , Dyachuk V
Published: April 2020

The questions of how autonomic neurons and their fibers select the target organs and whether parasympathetic innervation affects the development and growth of diverse organs are still open. We hypothesize that glia-neuronal transitions in development is crucial for correct development and homeostasis of innervated tissues in mice. The result of this preliminary experiment using genetic tracing showed that the mice mutants with lack autonomic ganglia indeed have a problem with development of target organs and support idea that autonomic nervous system directly involved in innervated organs morphogenesis.
Staining protocols for whole-body and fast tissue clearance for marine invertebrates
Authors: Kotsyuba E , Yurchenko O , Kamenev D , Savelieva A , Kalachev A , Milichko V , Dyachuk V
Published: April 2020

Marine invertebrates are the most morphologically varied group of animals with tough and smooth covers, external and internal organ structures and different body designs in general. Very often researchers cannot see internal deep structures without mechanical damage of animals. Here, we focus on “not damage” protocols of immunostaining and clearance of whole-body of invertebrates.
Application of metasurface-based low-pass filters for improving THz-TDS characteristics
Authors: Nikolaev N A , Rybak A A , Kuznetsov S A
Published: April 2020

We propose an approach to improve the technical characteristics of terahertz time-domain spectrometers at low-frequency measurements. The approach is based on applying low-pass THz filters to narrow the frequency band of the THz signal that allows increasing the sampling interval in accordance with the Nyquist–Shannon theorem. This concept was verified by studying the transmission spectra of low-frequency band-pass THz filters centered at 156 and 376 GHz. We confirm that the high-quality low-pass filters can improve accuracy of THz measurements and significantly reduce data acquisition time. The reduction up to 12 times was experimentally demonstrated in our case.
Examination of metamaterial solid immersion lenses for subwavelength optical manipulation
Authors: Novitsky Andrey , Repän T. , Malureanu R. , Takayama O. , Shkondin E. , Lavrinenko A.V.
Published: April 2020

We theoretically inspect, whether a recently proposed metamaterial solid immersion lens (a cluster of closely packed nanospheres) possesses super-resolving properties that could be used for subwavelength optical manipulation. Harnessing the multiple scattering theory for assembly of electric dipoles, we investigate the evanescent-wave and point-source-radiation transmission through the slab of nanospheres to establish the mechanism of super-resolution. Our calculations do not confirm resolution of subwavelength details using the metamaterial solid immersion lens.
Metasurfaces based on Functional Materials in THz and Optical Regions
Authors: Erfani-azad A. , Shahmirzadi N.V. , Pakizeh T. , Kolodev V. , von Gratoswki S.
Published: April 2020

In this paper we present the properties of metamaterials and metasurfaces composed of resonant micro/nano-structures in which their tunable electromagnetic (EM) properties can be achieved by employing the substrate or resonant structures consisting of functional materials such as polydimethylsiloxane (PDMS), Vanadium-dioxide (VO2), shape memory alloys (SMAs) or in general smart materials. Using a mechanical stretching PDMS substrate for a metasurface, reflectance and transmission of electromagnetic (EM) wave can be remarkably altered. Moreover, by employing resonators consists of Nitinol (NiTi) split ring resonators (SRR) which transforms to complete ring resonator (CRR) thermally, the resonance wavelength and its modal behaviour are affected. Furthermore, the chiroptical activity of planar optical metasurfaces composed of L-shape heterogeneous (Ag-VO2) dimer is studied as well. It is shown that by increasing temperature from room temperature to 81°C, the observed optical activity (OA) at 690 nm has been raised ∼ 50%, because of the occurred phase transition.
Ultrafast all-optical switching in the presence of Bloch surface waves
Authors: Popkova Anna A , Chezhegov Aleksandr A , Soboleva Irina V , Rybin Maxim G , Obraztsova Elena D , Bessonov Vladimir O , Fedyanin Andrey A
Published: April 2020

It is commonly known that Bloch surface waves (BSW) can be excited at the photonic crystal/dielectric boundary that leads to many features attractive for application these states as the basis of sensors and nanophotonic devices. The narrow spectral-angular resonance of BSW is very sensitive to properties of top layer and surrounding medium. There are few ways to enhance nonlinear optical response of a top layer without violation of BSW excitation conditions. In this work we choose graphene monolayer as a source of strong nonlinearity with tiny thickness. We study temporal nonlinear optical response of graphene in the case of Bloch surface waves excitation revealing subpicosecond switching time of probe dynamics.
Controlling Energy Spectra and Whispering Gallery Modes of Electrons in a Few Electrons Lateral QD
Authors: Ramezanpour S. , Mintairov A. M. , Bogdanov A.
Published: April 2020

In this work, we study energy spectra and Whispering Gallery Modes (WGMs) of electrons in Quantum Dot (QD). It is shown that the WGMs can exist between two lowest energy levels of a QD, s- and p-states by taking into account the Coulomb interaction between the electrons in the QD, since in a few electron QD, Coulomb Interaction plays a crucial role in its energy spectrum. In literature, lateral QDs are usually modeled by a 2D harmonic oscillator. However, our calculations reveal that some degenerate energy levels would be created due to the height of the QD. The effect of the dimension of the QD, and magnetic field are also investigated on the energy spectra.
Development of methods for safe MR-scanning of patients with implantable medical devices. Metal structures heating
Authors: Semenov D S , Vasilev Yu A , Akhmad E S
Published: April 2020

The paper presents the experience of experimental determination of implanted medical devices heating value during an MR-study. This work is a part of the development of a comprehensive methodology for ensuring the safety of patients with metal structures. Objects of various shapes and materials were placed in a gel phantom, scanning was performed on an MR scanner with a static magnetic field of 1.5 T. It is shown that the temperature change in close proximity to the surface of a metal object can be within the permissible normative documentation limits or be negligible. The existing in Russia indications for magnetic resonance imaging (MRI) for patients with various metal objects should be reviewed.
Simultaneous suppression of forward and backward light scattering by high-index nanoparticles based on Kerker-like effects
Authors: Shamkhi H. K. , Baryshnikova K. V. , Sayanskiy A. , Kapitanova P. , Terekhov P. D. , Belov P. , Karabchevsky A. , Evlyukhin A. B. , Kivshar Y. , Shalin A. S.
Published: April 2020

The ability of all-dielectric nanostructures to perform exotic photonics effects is with superior efficiency compared to their metallic counterparts. Free from joules losses, high-index dielectrics support comparable excitation of electric and magnetic resonances and pave a way to advanced technologies of light energy manipulation. One of the most important effects is directive light scattering provided by the Kerker and anti-Kerker effects giving the potential to realize Huygens source of light, transparent metasurfaces, router nanoantennas etc. Here we study an effect where most of the scattered power is redirected to the side directions rather than to the forward and/or backward directions. This kind of scattering on isotropic scatterer requires at least the presence of the first two orders of multipoles to enable simultaneous forward and back-scattering suppressions. Electric dipole Fano resonance profile and quadrupoles off-resonance characteristics provide the required phase and amplitude conditions to obtain such an optical signature. We find the individual scatterers sustain the transverse scattering conditions when assembled into a metasurface so exhibit invisibility effect. We investigate this phenomenon analytically and numerically in the visible and microwave domains and provide the proof-of-the-concept experiment in the gigahertz frequency and showing very good agreement with the theoretical predictions.
Formation of submicron- and micron-sized SiGe and Ge particles on Si substrates using dewetting
Authors: Shklyaev A. A.
Published: April 2020

The arrays formation of submicron- and micron-sized SiGe and Ge dielectric particles on the Si and SiO2 surfaces, which occur due to solid-state dewetting, is investigated. The shape of the particles and their spatial distribution turned out to be strongly dependent on the crystallographic Si surface orientation, the amount of deposited Ge and the Ge deposition rate, as well as on the presence of a SiO2 film on the Si surface. Possible applications of various surface morphologies with metasurface properties are discussed.
A new RF-coil for UHF MRI based on a slotted microstrip line
Authors: Solomakha G. , Svejda J. T. , Rennings A. , Erni D. , Glybovski S.
Published: April 2020

We propose to use an antenna based on a microstrip line with a slotted ground plane, as a transcieve RF-coil for ultra-high field (UHF) human body MRI at 7 Tesla. In this work we show by numerical simulations, that while being loaded with a homogeneous dielectric phantom, this slotted line supports fast-wave propagation and radiation of power into the phantom. As a result, it produces high RF magnetic field at a deeply located region of interest, which is the same as one produced by the well-known fractionated dipole.
A review of exact solutions for conversion of a surface wave into a propagating wave
Authors: Tcvetkova Svetlana N , Maci Stefano , Tretyakov Sergei A
Published: April 2020

In this paper, we summarize our recent theoretical and numerical studies of conversion of a surface wave to a propagating wave (and vice versa) with maximized conversion efficiency. We show that the exact solution for the homogeneous plane wave to surface wave conversion in a homogeneous medium by a point-wise lossless metasurface is restricted by Maxwell’s equations. Such performance is possible only with approximations and implies some limitations, including impossibility to fully avoid unwanted scatterings. Nevertheless, an inhomogeneous plane wave can be converted into a surface wave perfectly, and it is described by an exact solution formed by a superposition of only two modes of the Floquet expansion. The results of the studies are expected to be of fundamental importance for leaky-wave antennas efficiency improvement. Besides, they can lead to novel applications in various research areas.