bluuebunny/crossref_metadata_2025 huggingface dataset:
Successful Management of Recurrent Subacute Thyroiditis by Adding Colchicine to Glucocorticoid Treatment: A Case Series Study
Authors: Tian Zhenhua , Su Yu , Zhang Meijie , Zhang Xiujuan , Guan Qingbo
Published: May 2020

Although subacute thyroiditis (SAT) is thought to be a self-limited inflammatory
thyroid disease, the recurrence rate of SAT is approximately
10–20%. It is difficult for these patients to stop
glucocorticoid treatment, and they are usually bothered with recurrent pain and
the side effects of glucocorticoids for more than several months. We describe
three cases who were diagnosed with recurrent subacute thyroiditis after a
reduction in prednisolone (PSL) dose, either immediately upon the cessation of
PSL or shortly thereafter. Their symptoms, including the adverse effects of PSL,
severely impacted their quality of life. After a complete assessment, we
administered colchicine at 1 mg per day for 1–2 months to control the
recurrence of SAT and monitored their routine blood parameters every two weeks.
All 3 patients were successfully tapered off of PSL treatment and were free of
frequently recurrent SAT. Colchicine may be therapeutic in patients with
prednisolone-refractory, recurrent SAT. However, a large-scale, double-blind,
controlled, prospective multicenter study is required to provide a solid body of
evidence.
Trifluoperazine an Antipsychotic Drug and Inhibitor of Mitochondrial
Permeability Transition Protects Cytarabine and Ifosfamide-Induced
Neurotoxicity
Authors: Kiani Amir , Nik Shadi Heydari , Khodadoost Adineh , Salimi Ahmad , Pourahmad Jalal
Published: May 2020

The link between Ca2+ dysregulation, mitochondria damages,
oxidative stress and cellular derangement is particularly evident in
neurotoxicity induced by chemotherapeutic agents. In the current study, we
investigated effects of trifluoperazine (TFP) as an inhibitor of calmodulin
against the cytotoxicity induced by cytarabine (Ara-C) and Ifosfamide (IFOS) on
isolated rat neurons and also the mechanisms involved in this toxicity. Isolated
rat neurons were pretreated with TFP (100 µM) for 5 min
at 37°C, then Ara-C (226 µM) and IFOS
(290 µM) were added in separate experiments. After 3 h,
the cytotoxicity, reactive oxygen species (ROS), lysosomal membrane
destabilization, mitochondrial membrane potential (MMP), lipid peroxidation
(LP), glutathione (GSH) and glutathione disulfide (GSSG) levels were measured.
Ara-C and IFOS treatments caused a significant decrease in cellular viability,
which was accompanied by ROS generation, GSSG/GSH ratio, lipid
peroxidation and lysosomal and mitochondrial damages. On the other hand, TFP
(100 µM) pre-treatment attenuated Ara-C and IFOS -induced
decrease in cell viability. In addition, TFP (100 µM)
pre-treatment significantly protected against Ara-C and IFOS -induced increase
in ROS generation, lysosomal and mitochondrial damages, lipid peroxidation
levels and decrease in GSH/GSSG ratio. Our data provided insights into
the mechanism of protection by TFP against Ara-C and IFOS neurotoxicity, which
is related, to neuronal ROS formation and mitochondrial damages.
Effects of Short Term Metformin Treatment on Brown Adipose Tissue Activity and Plasma Irisin Levels in Women with Polycystic Ovary Syndrome: A Randomized Controlled Trial
Authors: Oliveira Flávia R. , Mamede Marcelo , Bizzi Mariana F. , Rocha Ana Luiza L. , Ferreira Cláudia N. , Gomes Karina B. , Cândido Ana L. , Reis Fernando M.
Published: May 2020

Polycystic ovary syndrome (PCOS) is a chronic dysfunction associated with obesity and metabolic disorders that can be ameliorated by treatment with metformin. Brown adipose tissue (BAT) has been recently identified in adult humans, and irisin is a myokine that induces BAT formation. The aim of this randomized controlled trial was to evaluate whether a short term treatment with metformin alters BAT activity and plasma irisin levels in women with PCOS. The participants were randomly assigned to receive metformin (1500 mg/day, n=21) or placebo (n=24) during 60 days. BAT activity was assessed by 18F-FDG positron emission tomography-computed tomography (PET-CT) and plasma irisin levels were measured by enzyme immunoassay. The groups were similar in age, body measures, metabolic profile and PCOS phenotypes. BAT activity did not change significantly in the women treated with metformin (median Δ SUVmax=–0.06 g/ml, interquartile interval –2.81 to 0.24 g/ml, p=0.484, Wilcoxon’s test) or placebo (median Δ SUVmax=0.98 g/ml, interquartile interval –2.94 to 4.60 g/ml, p=0.386). In addition, plasma irisin levels remained unchanged in the groups treated with metformin (median Δ=–98 ng/ml, interquartile interval –366 to 60 ng/ml, p=0.310) and placebo (median Δ=28 ng/ml, interquartile interval –1260 to 215 ng/ml, p=0.650). These results suggest that in PCOS women BAT activity and plasma irisin levels may not change after a brief treatment with metformin.
Composition and Antibacterial Effect of Mint Flavorings in Candies and Food Supplements
Authors: Kapp Karmen , Orav Anne , Roasto Mati , Raal Ain , Püssa Tõnu , Vuorela Heikki , Tammela Päivi , Vuorela Pia
Published: May 2020

Mint flavorings are widely used in confections, beverages, and dairy products. For the first time, mint flavoring composition of mint candies and food supplements (n = 45), originating from 16 countries, as well as their antibacterial properties, was analyzed. The flavorings were isolated by Marcussonʼs type micro-apparatus and analyzed by GC-MS. The total content of the mint flavoring hydrodistilled extracts was in the range of 0.01 – 0.9%. The most abundant compounds identified in the extracts were limonene, 1,8-cineole, menthone, menthofuran, isomenthone, menthol and its isomers, menthyl acetate. The antimicrobial activity of 13 reference substances and 10 selected mint flavoring hydrodistilled extracts was tested on Escherichia coli and Staphylococcus aureus by broth dilution method. Linalool acetate and (−)-carvone, as most active against both bacteria, had the lowest MIC90 values. (+)-Menthyl acetate, (−)-menthyl acetate, and limonene showed no antimicrobial activity. Three of the tested extracts had antimicrobial activity against E. coli and 8 extracts against S. aureus. Their summary antimicrobial activity was not always in concordance with the activities of respective reference substances.
Essential Oils as a Potential Treatment Option for Pediculosis
Authors: Candy Kerdalidec , Akhoundi Mohammad , Andriantsoanirina Valérie , Durand Rémy , Bruel Christiane , Izri Arezki
Published: May 2020

Pediculosis is a prevalent ectoparasite infestation caused by lice. The head louse (Pediculus humanus capitis) and body louse (Pediculus humanus humanus) are obligatory parasites whose only known hosts are humans. Pediculosis is probably the most common ectoparasitic infestation, affecting up to 80% of the population in several countries, and particularly prevalent in the infant population worldwide. Several treatment options, including shampoos and creams containing insecticides, have been introduced for the treatment of pediculosis. Recently, the use of synthetic chemicals to control human lice has raised concerns pertaining to human health and the environment. Therefore, increasing efforts have been undertaken to develop effective pediculicides with low environmental toxicity and minimal environmental residual activity. In this study, we focus on the essential oils derived from 22 plant genera, their constituents, and the major factors that play important roles in the effectiveness of these oils in the treatment of pediculosis. Furthermore, we discuss the advantages and limitations of the mentioned essential oils, and ultimately suggest those demonstrating the most effective in vitro pediculicidal activities. The genera such as Aloysia, Cinnamomum, Eucalyptus, Eugenia, Lavandula, Melaleuca, Mentha, Myrcianthes, Origanum, Pimpinella, and Thymus appear to be more efficient against lice. These genera are rich in anethole, 1,8-cineole, cinnamaldehyde, p-cymene, eugenol, linalool, limonene, pulegone, terpinen-4-ol, and thymol compounds.
COMMUNICATION BETWEEN THE MUSCULOCUTANEOUS AND MEDIAN NERVE: OCCURRENCE ON BOTH SIDES
Authors: K. Remya , Krishnamurthy Ashwin , K. Kavitha
Published: May 2020

Communications between musculocutaneous nerve and median nerve may be of considerable significance to neurologists and orthopaedicians when dealing with patients of nerve entrapment syndromes of the upper limb. Many authors have mentioned about an occurrence of such a variation previously, but the presence of a communication between the two nerves in both the arms has not been cited to the best of our knowledge. During routine dissection on a 72 year old male cadaver for the under graduate students in the Department of Anatomy at K.S. Hegde Medical Academy, we encountered an anomalous communication between musculocutaneous and median nerve in both the upper limbs. The communicating branch arose from the musculocutaneous nerve at a distance of 12.6 cm and 12.5 cm from the tip of coracoid process on right and left side and joined the median nerve 16.2 cm from the same bony point. Communications between nerves like this may explain abnormal debilities in certain cases of trauma of the upper arm. Lack of awareness of such variations with different patterns of communications between musculocutaneous and median nerve might complicate surgical repair of the nerves.
A STUDY ON MORPHOLOGY OF THE BICEPS BRACHII MUSCLE
Authors: Avadhani Ramakrishna , Chakravarthi K. Kalyan
Published: May 2020

The anatomical variations and abnormalities of the muscles of the upper limb have become significant because of new imaging techniques, such as computed tomography and magnetic resonance imaging. Among the three muscles of the anterior compartment of the arm, a very uncommon anomaly of the biceps is having three or more heads. Knowledge of the existence of the three headed or four headed biceps brachii may become significant in preoperative diagnosis and during surgery of the upper limb. The present study was undertaken to observe the anomalous origin, insertion and the incidence of three or more heads biceps brachii in the adult human cadavers. This study was carried out on 24 human cadavers at Dr. Pinnamaneni Siddhartha institute of medical sciences & research foundation (Dr. PSIMS & R.F) Gannavaram; Krishna Dist; A.P. Variant biceps brachii may cause compression of neurovascular structures because of their close relationship to brachial artery and median nerve. The surgeons and traumatologists have to keep such muscular variations in mind.
ADULT BASIC LIFE SUPPORT (BLS) AWARENESS AND KNOWLEDGE AMONG MEDICAL AND DENTAL INTERNS COMPLETING INTERNSHIP FROM DEEMED UNIVERSITY
Authors: Sharma Raghava , Attar Nazir R.
Published: May 2020

The present study was aimed to assess the awareness, knowledge, and attitude towards basic life support (BLS) among the interns completing their internship from both medical and dental streams of the Nitte university (a deemed university at Mangalore, Karnataka) and also to identify the areas to be addressed for improving the standards of BLS among the interns at their crucial juncture of moving out to the community, society as health care providers.

A descriptive study was conducted by using a Questionnaire comprising of 19 questions to collect the data pertaining to demographic details, awareness and knowledge of BLS, attitude towards BLS among all the medical and dental interns completing their internship during March 2012. The study was conducted in the last week of their one year internship programme.

After excluding the incomplete response sheets which were none in the present study, the data from 162 interns were subjected to the analysis. The Main outcome measure was the over all score in the BLS knowledge. Knowledge of BLS was assessed as per the data contained in the Basic life support manual from American Heart Association.

The results were drawn based on the comparisons between Medical and Dental streams and also with in each stream. Out of 162 interns, 84 were medical interns and 78 were dental interns. All of them (100%) were aware of the BLS and its usefulness. 16 (19%) medical interns had complete knowledge of BLS while none (0%) among dental interns had complete knowledge of BLS. A score of less than 50% was evident in 37(44%) of medical interns and 69(88%) of dental interns thus indicating a poor knowledge of BLS among both medical and dental interns who were completing their internship. However medical interns scored better in comparison to dental interns. Resuscitation experience (performing BLS) and Training (attending BLS work shop) resulted in better BLS knowledge and better scoring pattern among the medical interns thus boosting the confidence among interns. (Statistically significant with P < 0.05).

Present study highlights the need for a structured training of BLS and inclusion of BLS in the Medical and Dental academic curriculum.
Dupuytren’s Contracture with Secondary Ulnar Neuropathy
Authors: Ng Chen Fei
Published: May 2020

Dupuytren’s disease is a progressive fibrotic condition of the hand. The underlying pathomechanism is not fully known. Dupuytren’s contracture can be seen in patients with diabetes mellitus, chronic alcoholism, smoking, or hand trauma. It is uncommon to affect the neurovascular supply causing clinical symptoms. We describe a patient with idiopathic Dupuytren’s disease complicated with bilateral ulnar neuropathies and highlight the importance of such rare treatable complication.
Maternal Health after Stillbirth: Postpartum Hospital Readmission in California
Authors: Wall-Wieler Elizabeth , Butwick Alexander J. , Gibbs Ronald S. , Lyell Deirdre J. , Girsen Anna I. , El-Sayed Yasser Y. , Carmichael Suzan L.
Published: May 2020

Objective The aim of this study is to assess whether the risk of postpartum readmission within 6 weeks of giving birth differs for women who had stillbirths compared with live births.

Study Design Using data from the Office of Statewide Health Planning and Development in California, we performed a population-based cohort study of 7,398,640 births between 1999 and 2011. We identified diagnoses and procedures associated with the first postpartum hospital readmission that occurred within 6 weeks after giving birth. We used log-binomial models to estimate relative risk (RR) of postpartum readmission for women who had stillbirth compared with live birth deliveries, adjusting for maternal demographic, prepregnancy, pregnancy, and delivery characteristics.

Results The rate of postpartum readmission was higher among women who had stillbirths compared with women who had live births (206 and 96 per 10,000 births, respectively). After adjusting for maternal demographic and medical characteristics, the risk of postpartum readmission for women who had stillbirths was nearly 1.5 times greater (adjusted RR = 1.47, 95% confidence interval: 1.35–1.60) compared with live births. Among women with stillbirths, the most common indications at readmission were uterine infection or pelvic inflammatory disease, psychiatric conditions, hypertensive disorder, and urinary tract infection.

Conclusion Based on our findings, women who have stillbirths are at higher risk of postpartum readmissions within 6 weeks of giving birth than women who have live births. Women who have stillbirths may benefit from additional monitoring and counseling after hospital discharge for potential postpartum medical and psychiatric complications.

Key Points
A QUALITATIVE STUDY ON THE LIVED EXPERIENCES OF EXPECTANT FATHERS IN MANGALORE
Authors: Joy Riya , Paul Shynee
Published: May 2020

The study was conducted to explore the unique experiences of expectant fathers. The research approach used in this study was Phenomenology. Six expectant fathers who met the inclusion criteria were selected using purposive sampling technique from the OPD unit of the Fr. Muller Medical College Hospital, Mangalore and a private antenatal clinic, Saurabh clinic in Mangalore.In depth interviews were conducted in a selected room in the antenatal clinic with all privacy Colaizzi's data analysisframework was used to analyze the transcripts in this study From the analysis of the data, five themes emerged from the experiences of expectant fathers and they were as follows:Theme 1: Happiness and satisfaction - the response to pregnancy, Theme 2: Relationship with wife- Physically and emotionally, Theme 3: A change in social life, Theme 4: Coping with Pregnancy, Theme 5: Expectations about the baby
To Evaluate Shear Bond Strength of Resin Composite to Theracal Lc, Biodentine, and Resin–Modified Glass Ionomer Cement and Mode of Fracture: An In Vitro Study
Authors: Mehra Salil , Gupta Ashu K. , Singh Bhanu Pratap , Kaur Mandeep , Kumar Ashwath
Published: May 2020

Introduction The aim of the current study was to evaluate shear bond strength of resin composite bonded to Theracal LC, Biodentine, and resin-modified glass ionomer cement (RMGIC) using universal adhesive and mode of fracture.

Materials and Methods A total of 50 caries-free maxillary and mandibular molars extracted were taken; occlusal cavities were prepared, mounted in acrylic blocks, and divided into five groups based on the liner used. Group 1: Biodentine liner placed into the cavity and bonding agent and resin composite applied after 12 minutes. Group 2: Biodentine liner placed into the cavity and bonding agent and resin composite applied after 14 days. Group 3: RMGIC liner placed into the cavity and bonding agent and resin composite applied immediately. Group 4: RMGIC liner placed into the cavity and bonding agent and resin composite applied after 7 days. Group 5: Theracal LC liner placed into the cavity and bonding agent and resin composite applied immediately. Each sample was bonded to resin composite using universal adhesive. Shear bond strength analysis was performed at a cross-head speed of 0.1 mm/min.

Statistical Analysis  Statistical analysis was performed with one-way analysis of variance and posthoc Bonferroni test using SPSS version 22.0.

Results and Conclusion Biodentine liner when bonded immediately to resin composite showed minimum shear bond strength. RMGIC when bonded to resin composite after 7 days showed maximum shear bond strength. Mode of fracture was predominantly cohesive in groups having Biodentine and Theracal LC as liner.
An electrostatic interpretation of the zeros of sieved ultraspherical polynomials
Authors: Castillo K. , de Jesus M. N. , Petronilho J.
Published: May 2020

In an earlier work [Castillo et al., J. Math. Anal. Appl. 455, 1801–1821 (2017)], it was proved that the semiclassical class of orthogonal polynomials is stable under polynomial transformations. In this work, we use this fact to derive in a unified way old and new properties concerning the sieved ultraspherical polynomials of the first and second kind. In particular, we derive ordinary differential equations for these polynomials. As an application, we use the differential equation for sieved ultraspherical polynomials of the first kind to deduce that the zeros of these polynomials mark the locations of a set of particles that are in electrostatic equilibrium with respect to a particular external field.
Discontinuous spirals of stability in an optically injected semiconductor laser
Authors: Chávez C. Abraham T. , Curilef Sergio
Published: May 2020

We report a new kind of discontinuous spiral with stable periodic orbits in the parameter space of an optically injected semiconductor laser model, which is a combination of the intercalation of fish-like and cuspidal-like structures (the two normal forms of complex cubic dynamics). The spiral has a tridimensional structure that rolls up in at least three directions. A turn of approximately 2π radians along the spiral and toward the center increases the number of peaks in the laser intensity by one, which does not occur when traversing the discontinuities. We show that as we vary the linewidth enhancement factor (α), discontinuities are created (destroyed) through disaggregation (collapses) from (into) the so-called shrimp-like structures. Future experimental verification and applications, as well as theoretical studies to explain its origin and relation with homoclinic spirals that exist in its neighborhood, are needed.
Design and implementation of a J-coupled spectrometer for multidimensional structure and relaxation detection at low magnetic fields
Authors: Kaseman Derrick C. , Magnelind Per E. , Widgeon Paisner Scarlett , Yoder Jacob L. , Alvarez Marc , Urbaitis Algis V. , Janicke Michael T. , Nath Pulak , Espy Michelle A. , Williams Robert F.
Published: May 2020

In recent years, it has been realized that low and ultra-low field (mT–nT magnetic field range) nuclear magnetic resonance spectroscopy can be used for molecular structural analysis. However, spectra are often hindered by lengthy acquisition times or require large sample volumes and high concentrations. Here, we report a low field (50 μT) instrument that employs a linear actuator to shuttle samples between a 1 T prepolarization field and a solenoid detector in a laboratory setting. The current experimental setup is benchmarked using water and 13C-methanol with a single scan detection limit of 2 × 1020 spins (3 µl, 55M H2O) and detection limit of 2.9 × 1019 (200 µl, 617 mM 13C-methanol) spins with signal averaging. The system has a dynamic range of >3 orders of magnitude. Investigations of room-temperature relaxation dynamics of 13C-methanol show that sample dilution can be used in lieu of sample heating to acquire spectra with linewidths comparable to high-temperature spectra. These results indicate that the T1 and T2 mechanisms are governed by both the proton exchange rate and the dissolved oxygen in the sample. Finally, a 2D correlation spectroscopy experiment is reported, performed in the strong coupling regime that resolves the multiple resonances associated with the heteronuclear J-coupling. The spectrum was collected using 10 times less sample and in less than half the time from previous reports in the strong coupling limit.
Electrocaloric effects in monolayer germanium sulfide: A study by molecular dynamics simulations and thermodynamic analyses
Authors: Zhang Jin
Published: May 2020

In this paper, molecular dynamics (MD) simulations and thermodynamics analyses are performed to investigate the electrocaloric (EC) effect in monolayer germanium sulfide (GeS). Our MD simulations show a large EC effect in the armchair direction of monolayer GeS at room temperature, since monolayer GeS only has polarization in the armchair direction due to its anisotropic structure. Moreover, an enhancement in the EC effect is observed in monolayer GeS by increasing the ambient temperature. A thermodynamic model is proposed to explain this impact of temperature on the EC effect, which originates from the thermally enhanced thermal expansion property of monolayer GeS. Moreover, the thermodynamic model incorporated with the material parameters extracted from MD simulations is able to predict the EC coefficient. The predicted value is found to be identical to the value obtained from MD simulations, which further proves the EC effect observed in monolayer GeS. The observation of the EC effect in monolayer GeS (a typical two-dimensional material) is expected to open a new direction in searching EC materials and, meanwhile, provide opportunities for the innovative design of novel solid-state nanoscale cooling devices.
Role of tungsten dopants in indium oxide thin-film transistor on radiation hardness technology
Authors: Ruan Dun-Bao , Liu Po-Tsun , Gan Kai-Jhih , Chiu Yu-Chuan , Hsu Chih-Chieh , Sze Simon M.
Published: May 2020

The effects of radiation on tungsten doped indium oxide (IWO) thin-film transistors (TFTs) have been well investigated in this Letter. In order to achieve high stability and excellent electrical performance simultaneously even in high ionizing radiation damage ambient, different concentrations of tungsten dopant have been introduced for the TFT device fabrication. It is interesting that the high energy ionizing radiation may significantly increase the conductivity and influence the total concentration of oxygen vacancy in the transparent amorphous oxide semiconductor material, which may be completely different from the traditional radiation damage effect for silicon based CMOS devices. However, that abnormal phenomenon will be effectively suppressed by the powerful carrier suppressor, tungsten, which may have a high oxygen bond dissociation energy. Therefore, IWO devices with a 4% tungsten oxide dopant might be the optimized result even after high dosage ionizing radiation exposure. Hence, it may provide a promising radiation hardness approach to improve both the electrical characteristics and reliability for next generation displays, which can be used in the control system of nuclear power generation or space technology.
Instabilities, bifurcations, and transition to chaos in electrophoresis of charge-selective microparticle
Authors: Ganchenko G. S. , Frants E. A. , Amiroudine S. , Demekhin E. A.
Published: May 2020

Electro-hydrodynamic instabilities near a cation-exchange microgranule in an electrolyte solution under an external electric field are studied numerically. Despite the smallness of the particle and practically zero Reynolds numbers, in the vicinity of the particle, several sophisticated flow regimes can be realized, including chaotic ones. The obtained results are analyzed from the viewpoint of hydrodynamic stability and bifurcation theory. It is shown that a steady-state uniform solution is a non-unique one; an extra solution with a characteristic microvortex, caused by non-linear coupling of the hydrodynamics and electrostatics, in the region of incoming ions is found. Implementation of one of these solutions is subject to the initial conditions. For sufficiently strong fields, the steady-state solutions lose their stability via the Hopf bifurcation and limit cycles are born: a system of waves grows and propagates from the left pole, θ = 180°, toward the angle θ = θ0 ≈ 60°. Further bifurcations for these solutions are different. With the increase in the amplitude of the external field, the first cycle undergoes multiple period doubling bifurcation, which leads to the chaotic behavior. The second cycle transforms into a homoclinic orbit with the eventual chaotic mode via Shilnikov’s bifurcation. Santiago’s instability [Chen et al., “Convective and absolute electrokinetic instability with conductivity gradients,” J. Fluid Mech. 524, 263 (2005)], the third kind of instability, was then highlighted: an electroneutral extended jet of high salt concentration is formed at the right pole (region of outgoing ions, θ = 0°). For a large enough electric field, this jet becomes unstable; the perturbations are regular for a small supercriticality, and they acquire a chaotic character for a large supercriticality. The loss of stability of the concentration jet significantly affects the hydrodynamics in this area. In particular, the Dukhin–Mishchuk vortex, anchored to the microgranule at θ ≈ 60°, under the influence of the jet oscillations loses its stationarity and separates from the microgranule, forming a chain of vortices moving off the granule. This phenomenon strongly reminds the Kármán vortices behind a sphere but has another physical mechanism to implement. Besides the fundamental importance of the results, the instabilities found in the present work can be a key factor limiting the robust performance of complex electrokinetic bio-analytical systems. On the other hand, these instabilities can be exploited for rapid mixing and flow control of nanoscale and microscale devices.
Dynamic analysis of SH wave by a three-layer inclusion near interface in bi-material half space
Authors: Jang Paeksan , Paek Unyong , Jong Kunchol , Yun Duhon , Kim Cholyong , Ri Songchol
Published: May 2020

In this paper, the scattering of SH waves by a three-layer inclusion near the bi-material interface has been studied. A complex function method is employed to solve a two-dimensional wave propagation problem. The displacement fields in the bi-material half space and inside the linings of the inclusion are constructed, satisfying the governing equation, and unknown coefficients are solved from boundary conditions. The bi-material half space is separated into two quarter spaces, and the region matching method is used to determine the extra-forces on the interface. With the aid of the Green function method, the displacement fields owing to the forces are obtained. Then, the dynamic stress concentration factors (DSCFs) around the inner and outer surfaces of the inclusion are presented graphically, considering different medium parameters. Results are compared with those of earlier investigations, and the effect of parameters on the DSCF is discussed.
Mid-IR photothermal beam deflection technique for fast measurement of thermal diffusivity and highly sensitive subsurface imaging
Authors: Younes J. , Harajli Z. , Soueidan M. , Fabrègue D. , Zaatar Y. , Kazan M.
Published: May 2020

The resonances of phonon and plasmon modes make the absorbance coefficient of materials tremendously high in the mid-infrared spectral range, which allows for a mid-infrared excitation laser to heat the surface layers of these materials with high efficiency. Furthermore, phonon scattering by defects and defect-induced localized vibrational modes affect the local infrared dielectric function and, hence, the local infrared absorption coefficient. In this paper, we present a mid-infrared photothermal beam deflection technique that takes advantage of the strong interaction between infrared optical excitations and vibrational modes to measure the thermal diffusivity of materials without any sample preparation and takes advantage of the strong dependence of the infrared complex dielectric function on defects to detect subsurface defects with high sensitivity. We demonstrate the importance of the developed technique by measuring the thermal properties of highly transparent and reflective samples and detecting defects undetectable with any of the existing optical methods. Namely, using the developed technique, we find that the thermal diffusivities of high-quality Si, crystalline AlN, and crystalline α-SiO2 substrates are 1.00 ± 0.05, 0.67 ± 0.02, and 0.09 ± 0.01, respectively, and we record highly resolved images of structural subsurface defects as well as defects produced by ion-implantations at a depth of 62 μm under the surfaces of 4H-SiC substrates.
A physics-based machine learning study of the behavior of interstitial helium in single crystal W–Mo binary alloys
Authors: Samin Adib J.
Published: May 2020

In this work, the behavior of dilute interstitial helium in W–Mo binary alloys was explored through the application of a first principles-informed neural network (NN) in order to study the early stages of helium-induced damage and inform the design of next generation materials for fusion reactors. The neural network (NN) was trained using a database of 120 density functional theory (DFT) calculations on the alloy. The DFT database of computed solution energies showed a linear dependence on the composition of the first nearest neighbor metallic shell. This NN was then employed in a kinetic Monte Carlo simulation, which took into account two pathways for helium migration, the T-T pathway (T: Tetreahedral) and the T-O-T pathway (a second order saddle in both W and Mo) (O: Octahedral). It was determined that the diffusivity of interstitial helium in W–Mo alloys can vary by several orders of magnitude depending on the composition. Moreover, T-O-T pathways were found to dominate the T-T pathways for all alloy compositions for temperatures over about 450 K. Heterogeneous structures were also examined to account for radiation-induced segregation. It was observed that diffusion was fast when W segregated to the grain interior region and Mo to the grain outer region and was slow for the reverse situation. This behavior was explained by studying the energy landscape. Finally, thermodynamic simulations indicated that Mo-rich regions of the alloy were most favorable for binding the interstitial helium and may be the sites for the nucleation of helium bubbles.
Phase-field simulations of electromigration-induced defects in interconnects with non-columnar grain microstructure
Authors: Farmer William , Ankit Kumar
Published: May 2020

In this work, we utilize a phase-field model to investigate electromigration-mediated defects in non-columnar polycrystalline interconnects. We find that the misalignment of the grain boundary with respect to an externally applied electric field governs the non-linear kinetics of electromigration-induced slit evolution. We explore the mechanisms by which electromigration-induced defects propagate in interconnects comprising equiaxed and randomly distributed grains. We deduce that when atomic mobility in grain boundaries (Mgb) is two orders of magnitude larger than along the surface (Ms), the defect manifests as grain boundary slits, while a smaller Mgb/Ms promotes surface drift. By the aid of an extensive parametric study, the presence of a mixed mode at intermittent values of Mgb/Ms is established. Our simulations of slit formation in a network of randomly distributed grains validate our hypothesis that grain boundary alignment and the grain size distribution determine failure rates. Finally, we found that the failure rates in 3D are several times faster than in 2D, which indicates the importance of accounting the physics of three-dimensional capillarity in the present modeling approach.
Object surveillance with radio-frequency atomic magnetometers
Authors: Bevington P. , Gartman R. , Botelho D. J. , Crawford R. , Packer M. , Fromhold T. M. , Chalupczak W.
Published: May 2020

The capabilities of a radio-frequency atomic magnetometer for object detection based on magnetic induction tomography are explored. The determination of object orientation is demonstrated by utilizing the measurement geometry. The self-compensation configuration of the atomic magnetometer is implemented to address the issue of saturation of the sensor response by the radio-frequency primary field that generates the object signature. Three methods of “covert” detection are investigated as a testbed for exploring the functionalities of this sensor, where (1) the operational frequency of the sensor is continuously changed, (2) the primary field has non-monochromatic frequency distribution, and (3) the sensor operates in the so-called spin maser mode. The results of the measurements are also discussed in terms of possible magnetic field communication.
Ternary oxyfluoride shows promise for fluoride-ion batteries
Authors: Kim Meeri
Published: May 2020

Results suggest the possibility of using a ternary oxyfluoride (Bi0.7Fe1.3O1.5F1.7) as a cathode for fluoride-ion batteries, a candidate for the next-generation technology to replace lithium-ion batteries.
Theoretical investigation of optical intersubband transitions and infrared photodetection in β-(AlxGa1 − x)2O3/Ga2O3 quantum well structures
Authors: Lyman Joseph E. , Krishnamoorthy Sriram
Published: May 2020

We provide theoretical consideration of intersubband transitions designed in the ultra-wide bandgap aluminum gallium oxide [(AlxGa1 − x)2O3]/gallium oxide (Ga2O3) quantum well system. Conventional material systems have matured into successful intersubband device applications such as large-area quantum well infrared photodetector (QWIP) focal plane arrays for reproducible imaging systems but are fundamentally limited via maximum conduction band offsets to mid- and long-wavelength infrared applications. Short- and near-infrared devices are technologically important to optical communication systems and biomedical imaging applications but are difficult to realize in intersubband designs for this reason. In this work, we use a first-principles approach to estimate the expansive design space of monoclinic β-(AlxGa1 − x)2O3/Ga2O3 material system, which reaches from short-wavelength infrared (1–3 μm) to far infrared (>30 μm) transition wavelengths. We estimate the performance metrics of two QWIPs operating in the long- and short-wavelength regimes, including an estimation of high room temperature detectivity (∼1011 Jones) at the optical communication wavelength λp = 1.55 μm. Our findings demonstrate the potential of the rapidly maturing (AlxGa1 − x)2O3/Ga2O3 material system to open the door for intersubband device applications.
Spatiotemporal sampling of growing nanoparticles in an acetylene plasma
Authors: Marvi Z. , von Wahl E. , Trottenberg T. , Kersten H.
Published: May 2020

The dynamics of carbonaceous nanoparticle (NP) evolution in its cyclic growth process in a capacitively coupled RF plasma is studied using multiple diagnostic methods. We designed a simple method using biased substrates for spatiotemporal collection of growing NPs at different positions inside the particle cloud and at different time steps during the growth cycle. In addition, self-bias voltage and laser light scattering are in situ measured to monitor the nanoparticle growth. Subsequently, the collected nanoparticles are characterized by scanning electron microscopy (SEM). Correlations between the self-bias voltage and SEM results are presented. We show that different threshold potentials are needed to overcome the confinement of the NPs for collection. This is explained with the spatial and temporal variation of the plasma potential, the NP size, and the ion drag inside the particle cloud. Moreover, the arrangement of the locally collected NPs on the substrate is found to depend on the bias voltage applied to it. Finally, we demonstrate the possibility to control the self-organization and deposition patterns of the nanoparticles by changing the substrate orientation.
A facile combustion process for the preparation of magnetic MnFe2O4 nanorods and their adsorption mechanism of methyl blue
Authors: Lv Zhixiang , Wang Zhou
Published: May 2020

Magnetic MnFe2O4 nanorods were fabricated via the alcohol-solution combustion and calcination process. The morphology, microstructure, and composition of the as-prepared MnFe2O4 nanorods were characterized by x-ray diffraction, energy dispersive spectroscopy, and transmission electron microscopy and using a vibrating sample magnetometer. In addition, the magnetic MnFe2O4 nanorods were employed to remove methyl blue (MB) from aqueous solutions; the experimental results showed that the pseudo-second-order kinetic model was fitted well for the adsorption of MB onto MnFe2O4 nanorods in the initial MB concentration range of 100–400 mg l−1, while the isotherm data of MB onto MnFe2O4 nanorods could conform to the Langmuir model owing to the value of the square deviation (R2 > 0.99), and the maximum adsorption capacity of MB was 102.2 mg g−1, which suggested that the adsorption mechanism of MB onto MnFe2O4 nanorods at room temperature was the monolayer and multilayer adsorption. The effects of the solution pH and the recycle on the MB adsorption were evaluated. The adsorption capacity of MB onto MnFe2O4 nanorods could keep a high level at pH greater than 5. More than 78% of the removal efficiency of MB onto MnFe2O4 nanorods could be maintained after 10 cycles.
Dynamic behaviors of spiral waves in cardiac tissue under electromagnetic radiation
Authors: Luo Haibo , Ma Jile
Published: May 2020

A new modified Fitzhugh–Nagumo model is proposed to study the dynamic behaviors of spiral waves in cardiac tissue under fixed or periodic electromagnetic radiation. The effects of fixed electromagnetic radiation and the amplitude and frequency of periodic electromagnetic radiation on the pattern transitions of the spiral waves are investigated, respectively. Our numerical results show that although spiral waves can normally propagate with slight deformation under weaker fixed or periodic electromagnetic radiation, stronger fixed or periodic electromagnetic radiation can terminate the spiral waves, cause the drift of the spirals and turbulence, and magnetize the spiral waves to the homogeneous state. Extensive comparative analysis results confirm that fixed electromagnetic radiation is more helpful to modify and magnetize the spiral waves to the homogeneous state, but the spiral waves more easily change to the chaotic state under periodic electromagnetic radiation. The simulation results also show that both increasing the amplitude and decreasing the frequency can block the rotating spiral waves and cause turbulence, but our considerable numerical results find that lower frequency more easily develops spatiotemporal chaos from the media.
Control of dissipative rogue waves in nonlinear cavity optics: Optical injection and time-delayed feedback
Authors: Panajotov Krassimir , Tlidi Mustapha , Song Yufeng , Zhang Han
Published: May 2020

We investigate and review the formation of two-dimensional dissipative rogue waves in cavity nonlinear optics with transverse effects. Two spatially extended systems are considered for this purpose: the driven Kerr optical cavities subjected to optical injection and the broad-area surface-emitting lasers with a saturable absorber. We also consider a quasi-two-dimensional system (the two dimensions being space and time) of a fiber laser describing the complex cubic–quintic Ginzburg–Landau equation. We show that rogue waves are controllable by means of time-delayed feedback and optical injection. We show that without delayed feedback, transverse structures are stationary or oscillating. However, when the strength of the delayed feedback is increased, all the systems generate giant two-dimensional pulses that appear with low probability and suddenly appear and disappear. We characterize their formation by computing the probability distribution, which shows a long tail. Besides, we have computed the significant wave height, which measures the mean wave height of the highest third of the waves. We show that for all systems, the distribution tails expand beyond two times the significant wave height. Furthermore, we also show that optical injection may suppress the rogue wave formation in a semiconductor laser with a saturable absorber.
The emergence of inertial waves from coherent vortex source in strongly coupled dusty plasma
Authors: Gupta Akanksha , Ganesh Rajaraman
Published: May 2020

The evolution of isotropic, nondispersive, inertial waves emerging from an unsteady initial coherent vortex source is studied for strongly correlated dusty plasma using two-dimensional molecular dynamics simulation. In this study, the effects of azimuthal speed of a vortex source, strong correlation, large screening, and the compressibility of the medium on the propagation of generated inertial waves have been presented. It has been observed that these inertial waves only exist when the angular speed or azimuthal speed of the vortex source (U0) is larger than the transverse sound speed (Ct) of the system. The estimated speed of the nonlinear wave (CNLW) is found to be always larger and close to longitudinal sound speed (Cl) of the system for the range of coupling and screening parameters studied. We find that spontaneously generated inertial wave speed in dusty plasma is suppressed by the compressibility and dust-neutral drag of the system and is less sensitive to coupling strength. We also report a transition from “incompressible to compressible” flow. This transition is found to depend on the screening parameter and azimuthal speed of the vortex source. The existence of a critical Mach number Mc≈0.35 is found (where Mc=U0/Cl), above which inertial waves are found to exist, indicating the compressible nature of the wave.
QMCPACK: Advances in the development, efficiency, and application of auxiliary field and real-space variational and diffusion quantum Monte Carlo
Authors: Kent P. R. C. , Annaberdiyev Abdulgani , Benali Anouar , Bennett M. Chandler , Landinez Borda Edgar Josué , Doak Peter , Hao Hongxia , Jordan Kenneth D. , Krogel Jaron T. , Kylänpää Ilkka , Lee Joonho , Luo Ye , Malone Fionn D. , Melton Cody A. , Mitas Lubos , Morales Miguel A. , Neuscamman Eric , Reboredo Fernando A. , Rubenstein Brenda , Saritas Kayahan , Upadhyay Shiv , Wang Guangming , Zhang Shuai , Zhao Luning
Published: May 2020

We review recent advances in the capabilities of the open source ab initio Quantum Monte Carlo (QMC) package QMCPACK and the workflow tool Nexus used for greater efficiency and reproducibility. The auxiliary field QMC (AFQMC) implementation has been greatly expanded to include k-point symmetries, tensor-hypercontraction, and accelerated graphical processing unit (GPU) support. These scaling and memory reductions greatly increase the number of orbitals that can practically be included in AFQMC calculations, increasing the accuracy. Advances in real space methods include techniques for accurate computation of bandgaps and for systematically improving the nodal surface of ground state wavefunctions. Results of these calculations can be used to validate application of more approximate electronic structure methods, including GW and density functional based techniques. To provide an improved foundation for these calculations, we utilize a new set of correlation-consistent effective core potentials (pseudopotentials) that are more accurate than previous sets; these can also be applied in quantum-chemical and other many-body applications, not only QMC. These advances increase the efficiency, accuracy, and range of properties that can be studied in both molecules and materials with QMC and QMCPACK.
Feedback control of calcium driven alternans in cardiac myocytes
Authors: Nguyen Melodie , Shiferaw Yohannes
Published: May 2020

Cardiac alternans is a beat-to-beat alternation of the action potential duration (APD), which has been implicated as a possible cause of ventricular fibrillation. Previous studies have shown that alternans can originate via a period doubling bifurcation caused by the nonlinear dependence of the APD on the previous diastolic interval. In this case, it has been demonstrated that alternans can be eliminated by applying feedback control on the pacing cycle length. However, studies have shown that alternans can also originate due to unstable calcium (Ca) cycling in cardiac myocytes. In this study, we explore the effectiveness of APD feedback control to suppress alternans when the underlying instability is due to unstable Ca cycling. In particular, we explore the role of the bi-directional coupling between Ca and voltage and determine the effectiveness of feedback control under a wide range of conditions. We also analyze the applicability of feedback control on a coupled two cell system and show that APD control induces spatially out-of-phase alternans. We analyze the onset and the necessary conditions for the emergence of these out-of-phase patterns and assess the effectiveness of feedback control to suppress Ca driven alternans in a multi-cellular system.