Search

We report a patient with recurrent discharging sinus over the nasal bridge which was finally diagnosed as pilonidal sinus over the nasal bridge. Nasal pilonidal sinus is a rare condition that presents as a chronic and recurrent inflammation of the hair follicles and surrounding tissues of the nose, leading to the formation of abscesses and sinus tracts. The following report deals the dilemma of diagnosing and management of the patient. Though rare, nasal pilonidal sinus should be included as a differential diagnosis to aid in management as well as to improve awareness and inclusion of this condition. This report provides an overview of the clinical presentation, diagnosis and management of nasal pilonidal sinus. [ABSTRACT FROM AUTHOR]

Erbium doped single crystals of lithium niobate were grown within the bulk of 0.075 Er 2 O 3 – 37 Li 2 O – 37 Nb 2 O 5 – 26 SiO 2 glass using a femtosecond pulsed laser. Combined excitation emission spectroscopy was used to show incorporation of erbium into the laser written crystal lattice. Laser power and scanning speed were held constant at optimized values, while bulk sample temperature was systematically varied to study the impact on the crystal growth. Using electron backscatter diffraction to study the transverse cross-sections of grown crystals, control over the lattice rotation rates and crystal size were realized. Unlike changing other parameters, a range of temperatures were found to have substantial impacts on crystal growth, without inhibiting the ability to maintain single crystal formation over long distances. • Using a femtosecond laser, erbium doped single crystal LiNbO 3 was formed within a glass. • Controlling sample temperature enabled manipulation of the single crystal lattice. • Erbium was shown to incorporate into the crystal lattice under femtosecond laser processing. [ABSTRACT FROM AUTHOR]

Photosensitivity of thermally evaporated chalcogenide amorphous films of xGe45Se55-(1-x)As45Se55 (x = 0, 0.25, 0.5, 0.75, 1) composition is investigated when exposed to the laser light of 660 nm wavelength. The photo-induced effects transition from photodarkening (PD) to photobleaching (PB) as Ge45Se55 x increases from 0 to 1. The degree of PB correlates with the concentration of Ge-Ge homopolar bonds. The kinetics of PD and PB can be well described by a stretched exponential function. The dynamic response of PB is much faster than that of PD films in the present glass system. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate SmearOFF, 7% maleic acid (MA) and two different preparations of ethylenediaminetetraacetic acid (EDTA) in smear layer removal.Materials and methods: Fifty single-rooted teeth were separated into five groups, instrumented and irrigated as follows: (1) SmearOFF, (2) 7% MA, (3) 18% EDTA (pH 11.4), (4) 17% EDTA (pH 8.5) and (5) 0.9% saline. Teeth samples were blinded and examined by scanning electron microscopy with Image J software.Results: Eighteen percent EDTA was less efficient when compared to SmearOFF and MA at all thirds of the root canal system. There was no difference between SmearOFF and MA in the coronal and middle thirds. In the apical third, MA removed more smear layer. Seventeen percent EDTA was as efficient as SmearOFF and MA in coronal and middle third but not in the apical third. Eighteen percent EDTA removed smear layer less efficiently in the coronal and middle thirds than 17% EDTA; in the apical third, there was no difference observed. In the saline group, all specimens were heavily smeared. There was no significant difference between 18% EDTA and saline at all canal thirds.Conclusions: SmearOFF and 17% EDTA (pH 8.5) had better smear layer removal capability in the coronal and middle thirds of the root canal system. In the apical third, 7% MA was superior. 18% EDTA (pH 11.4) and saline had poor smear layer removal ability. [ABSTRACT FROM AUTHOR]

Female Anopheles mosquitoes are the primary vectors responsible for malaria transmission. The control of malaria is essential for humankind. In this study, we introduce a nonlinear deterministic model to control malaria disease by deploying Wolbachia bacteria into the Anopheles mosquitoes. Further, we study the effect of Wolbachia on temperature variation in tropical and subtropical regions of the world. We analyze the model for its positivity and boundedness with an initial condition in a specific set so that the model is well-defined mathematically and meaningful epidemiologically. We find the malaria-free equilibrium points of the model and analyze the local stability of all the equilibrium points. We calculate the basic reproduction number by the next-generation matrix method, which shows the stability of malaria-free equilibrium. Then we explore malaria present endemic equilibrium in both cases: Wolbachia-infected and Wolbachia-free possibilities. We observe that the number of infections is less in the Wolbachia-infected equilibrium case, and we find that Wolbachia can reduce malaria transmission in all temperature conditions. The sensitivity analysis of all different parameters is also calculated. We demonstrate the optimum temperature (from 22 °C to 28 °C) by numerical simulation where the malaria exposure and transmission rate is high. We can apply the work in all subtropical and tropical regions to control malaria transmission worldwide. [ABSTRACT FROM AUTHOR]

We have investigated photoinduced effects in as-deposited Ge 40−x Sb x Se 60 (x = 8, 15, and 20) films via in situ measurements of transmission spectra for wavelengths λ = 500 to 950 nm. The absorption coefficient increases initially, indicating the photodarkening (PD) effect, which rapidly saturates in tens of seconds. Then the absorption coefficient starts decreasing representing photobleaching (PB). The evolution of PD and PB can be described by stretched exponential function, yielding the time constants for the changes in absorption coefficients. The kinetics of PD is faster than that of PB. The coexistence of PB and PD suggests that the Sb and Ge based structural units of Ge-Sb-Se films respond to bandgap radiation independently. The structural origins of the observed opposing photoinduced effects are discussed. [ABSTRACT FROM AUTHOR]

Osteonecrosis is thought to result from the temporary or permanent loss of the blood supply to the bones. The most common symptom is pain which is localized to the affected condyle. The medial femoral condyle is typically affected, the lateral femoral condyle, medial tibial plateau and patella may also be involved. The purpose of this case report is to highlight the importance of osteonecrosis as a cause of post-partum hip, knee and other joint pain and to review the literature in regards to pregnancy as a possible etiological factor. We presented a case of a 25 year old female who presented to us on 20th December 2015 with pain in the right thigh of 10 days duration at the distal half extending up to mid-calf. [ABSTRACT FROM AUTHOR]

Introduction: Diabetes mellitus is a leading public health care problem in developing and developed world, with increasing incidence and long term complications. It is the most common endocrine disorder in the world today. Objective: To study the anthropometric parameter in the children whose parents are diabetic and nondiabetic. Material and methods: 250 medical students of S.N Medical College, Agra, of age group 18–25 years were included in study from year 2015 to 2017. Their anthropometric measurements which included weight, height, BMI were taken. This study was done in physiology department of S.N.M.C. Agra. Subjects were divided into 2 Groups .Children of diabetics parents (Group-1) and Children of non-diabetic parents (Group-2). Results: Out of total 250 students, 15.2% students were overweight and 2.4% were obese according to WHO classification of BMI. In group 1, out of 64 students, 18.75% were found to be overweight and 3.1% were obese. In group 2, out of 186 students, 13.9% were overweight and 2.15% were obese. The mean BMI of Group-1 and Group-2 was 22.21 ± 3.50 and 22.15 ± 3.19 respectively. P value =0.73 and t=0.33. Conclusion: Higher percentage of overweight and obese are found in the children of diabetic parents as compare to non-diabetic parents and Mean BMI is slightly higher in group 1 i.e. in the children of diabetic parents but this difference in Mean BMI of both groups is considered to be not significant. [ABSTRACT FROM AUTHOR]

Background: Hip fractures in older patients are associated with impaired mobility, excess morbidity and mortality, and loss of independence. Objectives: To determine whether total hip arthroplasty is associated with lower reoperation rates, mortality, and complications, and better function and quality of life than hemiarthroplasty for displaced fractures of the femoral neck in older patients. Materials and methods: We prospectively as well as retrospectively studied 46 patients treated with total hip replacement or hemiarthroplasty. Pain, range of motion, hip function, haris hip score and complications were assessed clinically while hip stability, femoral anteversion, acetabular cup inclination and acetabular erosions were assessed radiographically. Results: In our study according to Harris hip score, group A (hemiarthroplasty group) showed 58.33% excellent to good result whereas 33.34% shows fair to poor result. In group B (total hip replacement group) 90.91% showed excellent to good result and 9.08% showed fair to poor result. In this study, the overall Harris hip score was 76.33 with SD±19.091 in hemiarthroplasty group and 86.45 with SD±6.363 in Total hip replacement group with p-value 0.0224(<0.05). Conclusion: So we concluded in our one year of study that total hip replacement had better functional outcome in fracture neck of femur in elderly treated by either hemiarthroplasty or total hip replacement and total hip replacement is less painful than hemiarthroplasty. [ABSTRACT FROM AUTHOR]

Majority of osteoporotic vertebral compression fracture present with back pain and some of them with spinal deformity. Percutaneous vertebroplasty not only addresses pain relief but also the correction of spinal deformity with least post-operative morbidity. 72 patients with osteoporotic compression fracture and spinal deformity with chronic invalidating pain treated with percutaneous vertebroplasty were followed for 2.8 years with an average of 1.3 years.47% showed excellent,13% showed good and 40% showed fair result on vas score. There was good improvement in stature in 43%, fair in 40% and 17% showed no improvement. [ABSTRACT FROM AUTHOR]

This paper presents an alternative approach to power system computations, Graph Trace Analysis (GTA), and applies this approach to solving the power flow problem. GTA is derived from the Generic Programming Paradigm of computer science, and uses topology iterators to move through components in a model and perform calculations. The implementation of KVL and KCL in GTA is described. The GTA based power flow algorithm is shown to solve IEEE standard transmission models, IEEE standard distribution models, and integrated transmission and distribution models (hybrid models) constructed from modifying IEEE standard models. Comparisons with widely used, primarily matrix based, power flow algorithms are provided. Two advantages that GTA brings are the separation of system equations from component equations and the ability to distribute calculations across processors. [ABSTRACT FROM AUTHOR]

This paper presents a new method for studying electromechanical transients in power systems using three phase, combined transmission and distribution models (hybrid models). The methodology models individual phases of an electric network and associated unbalance in load and generation. Therefore, the impacts of load unbalance, single phase distributed generation and line impedance unbalance on electromechanical transients can be studied without using electromagnetic transient simulation (EMTP) programs. The implementation of this methodology in software is called the Three Phase Dynamics Analyzer (TPDA). Case studies included in the paper demonstrate the accuracy of TPDA and its ability to simulate electromechanical transients in hybrid models. TPDA has the potential for providing electric utilities and power system planners with more accurate assessment of system stability than traditional dynamic simulation software that assume balanced network topology. [ABSTRACT FROM PUBLISHER]

System identification is becoming a relevant research area for numerous applications in power grids due to the increasing complexity of the system. A paradigm shift in power system infrastructure driven by renewable energy resources, controllable loads, and new power electronics technologies have given rise to new challenges in power systems operation and control. This increased complexity of power systems and unavailability of physics-based models of most inverter-based resources requires that traditional modeling of power systems approaches be complemented by system identification-based black or grey box modeling techniques. In light of the importance of system identification and little attention paid to the applications of these techniques in transforming power systems, this paper provides a comprehensive review of active probing-based system identification methods in the context of power system applications. It reviews applications of both linear and nonlinear system identification with discussion on their potential and key takeaways. To motivate a further practical use in power systems, the paper provides an example of system identification, to develop a state space model of an unknown plant with step-by-step details. The paper highlights the advantages of using modern power electronics-based sources in the identification process and discusses the emerging research directions for future. [Display omitted] • System identification has high potential in power systems applications. • System identification can overcome limits of traditional system modeling approaches. • Distributed energy resources in power grids incur challenges and opportunities. • Power electronics-based resources offer flexibility and cost effectiveness in power system identification. [ABSTRACT FROM AUTHOR]

Low-Energy Ion-Scattering ( LEIS) spectroscopy is a technique with a unique sensitivity to the elemental composition of the top atomic layer of a solid surface. LEIS measurements of ternary silicate glasses modified with Na2O, Cs2O, CaO, and BaO show that the compositions of the as-cast (melt) surface and the in-vacuum fracture surface often differ. While the as-cast surface is usually depleted of alkali ions (Na+ or Cs+) compared to the nominal (batch) glass composition, there is often strong accumulation of the same mobile cations on the fresh fracture surface. Depth profiles obtained by sputter etching reveal elemental concentration gradients normal to the glass surface. The final concentrations often fail to reach the nominal glass composition, suggesting the likely presence of preferential sputtering effects and thereby the distortion of the measured concentration gradient. At present, the lack of reliable standards and preferential sputtering effects in the LEIS of multicomponent glasses limit somewhat the absolute chemical composition and structural information that can be obtained with this otherwise unique and powerful method of surface analysis. [ABSTRACT FROM AUTHOR]

We present a photothermoelastic model for studying the photothermal effect in chalcogenide glasses. The temperature rise and thermoelastic expansion for a model material As2S3 glass are calculated. Our result indicates that significant expansion (e.g. >1 µm) on the free surface of glass can be induced with only moderate temperature rise (e.g. <30 K). This occurs because of the Poisson effect of the large compressive forces generated on the interface between the irradiated and unirradiated areas in the material. We argue that photoexpansion in chalcogenide glasses arise from the concurrent effect of photothermoelastic expansion and photofluidity. The temperature dependence of photoexpansion is also discussed. The present model provides an explanation for the generality of photoexpansion in these materials. [ABSTRACT FROM AUTHOR]

A key requirement for the use of bio scaffold is that its degradation rate matches the growth rate of target tissue. Therefore, the degradation of recently developed tailored amorphous multiporous ( TAMP) scaffold of 70 SiO2·30 CaO (mol%) in simulated body fluid ( SBF) was studied under both static and quasi-dynamic conditions. The degradation was assessed through the dissolution of silica from the glass into SBF, while the in-vitro bioactivity was characterized by precipitation of calcium phosphate ( CaP) on and inside the scaffold. Under static conditions, the degradation stopped due to the saturation of solution with silica in 3 days, whereas the precipitation of CaP continued. Rapid degradation and better in-vitro bioactivity was found under quasi-dynamic conditions, where the concentration gradient across the sample was maintained. The degradation followed exponential dependence on time with a half-life of 15.4 days and initial degradation rate 4.5% day−1. The remaining samples maintained their integrity and pore structure during degradation. The degradation occurred in three distinct stages: (a) wetting stage, (b) initial degradation stage when CaP precipitation dominates, and (c) intensive degradation stage when the nanopores rupture and network dissolves. By varying the sintering parameters the nanopore structure, and hence the degradation rate, can be tailored to suit the anticipated tissue regeneration rate. With demonstrated rapid and controllable degradation and good in-vitro bioactivity, the TAMP scaffold shows promise as candidate for bone regeneration application under various conditions in the body. [ABSTRACT FROM AUTHOR]

Formation of sufficiently large three-dimensional (3D) nanomacroporosity in bone scaffolds remains a challenge in spite of several methods reported in literature. It is required for tissue ingrowth and for the concurrent degradation of implanted structure. We report a new technique for fabricating superior high surface area, nanomacroporous bioactive glass scaffold, which combines the sol-gel process and polymer sponge replication method. The formation of 3D structure is demonstrated in 70 mol% SiO2-30 mol% CaO glass composition as an example, which is uniform across the sample. It consists of open, interconnected macropores with size from 300 to 600 μm, as desired for tissue ingrowth. At the same time, coexisting nanopores provide high-specific surface area (∼184 m2/g), which is needed for enhancing the structure's degradation rate. These bioscaffolds hold promise for applications in hard tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract: The dielectric properties of ternary silver vanadium tellurite and titanium vanadium tellurite glasses of the form [0.5[xAg2O-(1−x)V2O5]–0.5TeO2, x=0.1–0.8mol] and [0.5[xTiO2-(1−x)V2O5]–0.5TeO2, x=0.1–0.6mol] are investigated as a function of frequency (10Hz–1MHz) and temperature (70–425K). Electrical relaxation is analyzed in terms of dielectric modulus and Kohlrausch–Williams–Watts (KWW) stretched exponential distribution function. The composition dependence of the stretched exponential parameter (β) is explained according to the variation of activation energy for dc conductivity and inter-charge separation in the two glass series. From the transition of polaronic to ionic conduction in silver vanadium tellurite glass series, it is established that ion–ion correlations are more effective in slowing down the electrical relaxation than the interactions between electronic charge carriers. [ABSTRACT FROM AUTHOR]

Abstract: The mixed electronic–ionic conduction in 0.5[xAg2O–(1−x)V2O5]–0.5TeO2 glasses with x=0.1–0.8 has been investigated over a wide temperature range (70–425K). The mechanism of dc conductivity changes from predominantly electronic to ionic within the 30⩽mol% Ag2O⩽40 range; it is correlated with the underlying change in glass structure. The temperature dependence of electronic conductivity has been analyzed quantitatively to determine the applicability of various models of conduction in amorphous semiconducting glasses. At high temperature, T>θ D/2 (where θ D is the Debye temperature) the electronic dc conductivity is due to non-adiabatic small polaron hopping of electrons for 0.1⩽x⩽0.5. The density of states at Fermi level is estimated to be N(E F)≈1019–1020 eV−1 cm−3. The carrier density is of the order of 1019 cm−3, with mobility ≈2.3×10−7–8.6×10−9 cm2 V−1 s−1 at 300K. The electronic dc conductivity within the whole range of temperature is best described in terms of Triberis–Friedman percolation model. For 0.6⩽x⩽0.8, the predominantly ionic dc conductivity is described well by the Anderson–Stuart model. [Copyright &y& Elsevier]

As a first step, most model checkers used in the hardware industry convert a high-level register-transfer-level (RTL) design into a netlist. However, algorithms that operate at the netlist level are unable to exploit the structure of the higher abstraction levels and, thus, are less scalable. The RTL of a hardware description language such as Verilog is similar to a software program with special features for hardware design such as bit-vector arithmetic and concurrency. This paper uses predicate abstraction, a software verification technique, for verifying RTL Verilog. There are two challenges when applying predicate abstraction to circuits: 1) the computation of the abstract model in presence of a large number of predicates and 2) the discovery of suitable word-level predicates for abstraction refinement. We address the first problem using a technique called predicate clustering. We address the second problem by computing the weakest preconditions of Verilog statements in order to obtain new word-level predicates during abstraction refinement. We compare the performance of our technique with localization reduction, a netlist-level abstraction technique, and report improvements on a set of benchmarks. [ABSTRACT FROM AUTHOR]

Using a novel, selective heating by Nd:YAG laser, a single-crystal architecture is created in a model glass system, Sm0.5La0.5BGeO5, which devitrifies congruently into a ferroelectric phase of the same composition as the parent glass. The Sm3+ ions in glass absorb the light and heat the matrix locally resulting in devitrification. Initially, a polycrystalline spot is formed. However, with optimum laser power, scanning speed, and the depth of focus, one of the grains acts as the seed for further growth as a single crystal. By programming the relative displacement of the glass with respect to laser spot, desired single ferroelectric crystal architecture is created. The optical functionalities (guiding of light and second harmonic generation) of the architectures are shown, which demonstrate the viability of this method for constructing active elements in optical integrated circuits. The single-crystal nature of the architecture is confirmed from the electron backscattered diffraction results. [ABSTRACT FROM AUTHOR]

Abstract: X-ray induced structural changes at the Ag/As2S3 interface are investigated using X-ray photoelectron spectroscopy on the samples prepared within the spectrometer. The as-prepared film consists of stable heteropolar As–S bonds as well as ∼16% S (and As) atoms in lower (higher) electron density configurations such as the –S–S– (–As–As–) segments with ‘wrong’ homopolar bonds. Two distinct stages of the X-ray induced diffusion are revealed. At first, silver reacts with atoms within –S–S– like segments to form Ag–S bonds. In the second stage, the Ag–S bonds decompose due to the reaction of S with As atoms within the –As–As– ‘wrong’ segments to form As–S heteropolar bonds, and silver diffuses away from the interface into the film. The results provide guideline for enhancing silver photodiffusion in chalcogenide glass. The irradiation of the (Ag–Te)/As2S3 sample with X-rays shows that not only Ag, but Te also diffuses away from the surface. [Copyright &y& Elsevier]

Abstract: Electronic transport in the high temperature paramagnetic regime of the colossal magnetoresistive oxides, La1−x A x MnO3, A=Ca, Sr, Ba, x≃0.1–0.3, has been investigated using resistivity measurements. The main motivation for this work is to relook into the actual magnitude of the activation energy for transport in a number of manganites and study its variation as a function of hole doping (x), average A-site cation radius (〈r A〉), cationic disorder (σ 2) and strain (ε zz ). We show that contrary to current practice, the description of a single activation energy in this phase is not entirely accurate. Our results clearly reveal a strong dependence of the activation energy on the hole doping as well as disorder. Comparing the results across different substituent species with different 〈r A〉 reveals the importance of σ 2 as a metric to qualify any analysis based on 〈r A〉. [Copyright &y& Elsevier]

The short-range atomic order around all three constituent atoms in a prototypical bulk metallic glass (BMG) system was probed in a complementary way, using extended X-ray absorption fine structure for neighborhood of the higher atomic number elements, and extended energy loss fine structure (EXELFS) for the lower atomic number ones. The PdxNi(80−x)P(20) system is a prototype for a whole class of BMG formers which are 80% transition metal and 20% metalloid. We find that the structure of these BMGs could be explained in terms of those of glasses at the end of the BMG range, namely, Pd60Ni20P20 and Pd30Ni50P20. The binary phosphide crystals near x=0 and 80 are found to be simulate very well the local atomic structure of Pd30Ni50P20 and Pd60Ni20P20 glasses, respectively. The best glass former in this series, Pd40Ni40P20, is best described by a weighted average of Pd30Ni50P20 and Pd60Ni20P20 structures. [Copyright &y& Elsevier]

The reaction of soda-lime-silicate glassware with model cleaning solutions gives rise to a systematic pattern of inhomogeneous corrosion. This corrosion is not uniform on the entire surface, but is localized only to certain regions of the glassware. The surface composition, as determined by X-ray photoelectron spectroscopy, and the microstructure, as characterized by optical and scanning electron microscopy, vary considerably in different regions of the glassware. The visibly heterogeneous corrosion pattern, which correlates with the compositional and structural inhomogeneities, is explained in terms of surface conditions that exist during different stages of glass manufacturing. The role of sodium disilicate in solution is also explored for promoting inhomogeneous glass corrosion. [ABSTRACT FROM AUTHOR]

Atomic arrangements systemically deviating from the classic definition of single crystal lattice have been known in spherulites for over a century. However, their unusual curved lattice could not be exploited for useful applications due to their uncontrolled orientations and lattice curvatures. Heating of glass with focused laser, electron, or X‐ray beam has yielded well‐defined conditions for forming single crystal architectures. Furthermore, by controlling the conditions of irradiation and confinement by glass matrix for a given system, desired lattice curvature (rotations and twists) can be reproducibly introduced into these crystals. Here, we review several examples of laser‐fabricated crystals with curved lattices in glass using a common coordinate system, which helps to establish correlations between processing parameters and lattice curvature. The mechanisms of lattice deformations are discussed along with potential methods to control the orientation of the initially formed seeds that determine the lattice orientations of the end product. The recent developments of laser‐fabrication of single crystal architectures in glass with controlled heating profile appear promising for engineering the curvature of their lattices. [ABSTRACT FROM AUTHOR]

We describe a family in which parents had consanguinity, being children of real sisters. They had given birth to five children. In their family, children remained healthy from birth to pre-school age and then started having symptoms around the age of 5 years and two of them succumbed to this illness. Polyglandular autoimmune syndrome Type-1 is a rare sporadic autosomal recessive disease. It is characterized by the existence of two or more endocrinal disorders. Patients may require lifelong hormone replacement therapy for survival. [ABSTRACT FROM AUTHOR]

Integrated transmission-and-distribution (T&D) modeling is a new and developing method for simulating power systems. Interest in integrated T&D modeling is driven by the changes taking place in power systems worldwide that are resulting in more decentralized power systems with increasingly high levels of distributed energy resources. Additionally, the increasing role of the hitherto passive energy consumer in the management and operation of power systems requires more capable and detailed integrated T&D modeling to understand the interactions between T&D systems. Although integrated T&D modeling has not yet found widespread commercial application, its potential for changing the decades-old power system modeling approaches has led to several research efforts in the last few years that tried to (i) develop algorithms and software for steady-state and dynamic modeling of power systems and (ii) demonstrate the advantages of this modeling approach compared with traditional, separated T&D system modeling. In this paper, we provide a review of integrated T&D modeling research efforts and the methods employed for steady-state and dynamic modeling of power systems. We also discuss our current research in integrated T&D modeling and the potential directions for future research. This paper should be useful for power systems researchers and industry members because it will provide them with a critical summary of current research efforts and the potential topics where research efforts are needed to further advance and demonstrate the utility of integrated T&D modeling. [ABSTRACT FROM AUTHOR]

We show that strong nonlinear electron transport in the ferromagnetic insulating (FMI) state of manganites, responsible for phenomena such as colossal electroresistance and current induced resistance switching, can occur due to a hot electron effect. In the FMI state, which we show is an insulator with a Coulomb gap, the temperature of the electron and lattice baths can decouple at high input power levels, leading to heating of the electron bath. Parameters of the hot electron effect model were independently determined via time dependence experiments and are in good agreement with the experimental values. [ABSTRACT FROM AUTHOR]

Abstract: Based on electroresistance (ER) measurements founded on a current induced resistivity switching (CIRS) phenomena, we establish the presence of a ‘colossal’ ER in the low temperature ferromagnetic insulating (FMI) phase exhibited by certain hole doped manganites. Notably, concomitant with the build-up of ER, is a sharp drop in the magnetoresistance (MR). This intelligibly demonstrates an effective decoupling of the mechanisms underlying ER and MR in the FMI phase. ER (CIRS) and MR were measured on single crystals of two widely different FMI manganites: and . The samples have Curie temperatures, and 150K, and the FMI state is realized for temperatures, and 130K, respectively. The ER, arising from a strong nonlinear dependence of resistivity () on current density , attains a value in the FMI state. The severity of the nonlinear behavior of resistivity at high current densities is progressively enhanced with decreasing temperature. The MR, however, collapses even in magnetic field, . Comparison with magnetotransport data on charge ordered insulating (COI) manganites reveal discernible differences in response to applied current and magnetic field. This is credible proof that the nature of the insulating state, in the FMI and COI phases, is different. [Copyright &y& Elsevier]

We demonstrate that suitable thermal treatment of biocompatible CaO–Na2O–P2O5–SiO2 glasses prepared by the usual melt-quench results in spinodal phase separation and crystallization of phases at very different length scales. Selective chemical leaching of these phases allows the formation of interconnected multi-modal porosity, with pore size ranging from several nanometers to tens of micrometers. Such novel nano–macroporous glasses have potential applications as superior bioscaffolds. [ABSTRACT FROM AUTHOR]

Colossal electroresistance and current induced resistivity switching have been measured in the ferromagnetic insulating (FMI) state of single crystal manganite La0.82Ca0.18MnO3. The sample has a Curie transition temperature TC=165 K and the FMI state is realized for temperatures T<100 K. The electroresistance (ER), arising from a strong nonlinear resistivity, attains a large value (≈100%) in the FMI state. However, this is accompanied by a collapse of the magnetoresistance (MR) to a small value even in magnetic field (H) of 10 T. This demonstrates that the mechanisms that give rise to ER and MR are effectively decoupled. [ABSTRACT FROM AUTHOR]

The atomistic origin of photoinduced vector (polarization-dependent) phenomena in As-Se films is determined by extended x-ray absorption fine structure with in situ exposure to polarized laser light. A vector structural change is observed directly for any material: there is an expansion of the nearest-neighbor distance around the Se atoms, the magnitude of which depends on the direction of light polarization; the effect around As atoms is relatively smaller. The results point to the origin of scalar as well as vector changes in properties, which either persist after the light is removed, or exist only when light is incident on the sample. [ABSTRACT FROM AUTHOR]

Glass‐to‐crystal transformation of lithium disilicate is studied using molecular dynamics simulations using an effective partial charge potential. The structural evolution of the interface between glassy and crystalline lithium disilicate is analyzed to simulate crystallization of glass on pre‐existing crystal seeds. Besides previously used atomic number density, the distribution of Qn species (Si tetrahedra with n bridging oxygen) is shown to be an effective parameter for following this transformation quantitatively. The early stages of crystal growth are significantly affected by the orientation and termination of the surface of adjacent crystal, as indicated by calculated atomic density, partial ordering, atomic segregation, and an increase in Q3 concentration. In particular, under‐coordinated Si within the outer crystal layer is found to be most effective in transforming the amorphous structure toward crystallinity. The increase in Q3 in the glass close to interface region most clearly shows the initial stage of lithium disilicate crystal growth. [ABSTRACT FROM AUTHOR]

Introduction: The need for intensive care, the complications associated with severe disease, and the vulnerability of older adults and individuals with underlying medical conditions are highlighted. The significance of prevention and the absence of a precise treatment for COVID-19 are emphasized. The introduction also mentions the objective of studying the latest clinical profile of admitted patients at a specific hospital. Material and Methods: This section describes the study conducted at R.D G.M.C. Tertiary Care Hospital in Ujjain, M.P. The procedure involved obtaining approval from the institutional review board and enrolling patients aged 25 years and above who met the specified criteria. Information was collected through a preformed proforma, and the enrolled patients underwent detailed history and clinical examination. Results: The study included 274 patients with a mean age of 48.8 years. The majority of cases were male. The prevalence of comorbidities such as diabetes, hypertension, COPD, asthma, and tuberculosis was documented. Disease severity was categorized as mild, moderate, or severe, and pneumonia and complications were noted. The duration of hospital stay varied among the patients. Associations between comorbidities, disease severity, and outcomes were analyzed. The results showed significant associations between certain comorbidities and disease severity and between chest X-ray findings, complications, and disease severity. Age and symptoms such as fever, cough, breathlessness, loss of smell, loss of taste, and weakness were found to be significantly associated with patient outcomes. Conclusion: The mortality rate among the patients was determined, and the distribution of disease severity was highlighted. The importance of urgent public health interventions for susceptible groups and the need for regular follow-up for early stratification of cases is emphasized. The abstract acknowledges the ongoing research and studies aimed at addressing the knowledge gaps related to COVID-19. [ABSTRACT FROM AUTHOR]

Direct three-dimensional laser writing of amorphous waveguides inside glass has been studied intensely as an attractive route for fabricating photonic integrated circuits. However, achieving essential nonlinear-optic functionality in such devices will also require the ability to create high-quality single-crystal waveguides. Femtosecond laser irradiation is capable of crystallizing glass in 3D, but producing optical-quality single-crystal structures suitable for waveguiding poses unique challenges that are unprecedented in the field of crystal growth. In this work, we use a high angular-resolution electron diffraction method to obtain the first conclusive confirmation that uniform single crystals can be grown inside glass by femtosecond laser writing under optimized conditions. We confirm waveguiding capability and present the first quantitative measurement of power transmission through a laser-written crystal-in-glass waveguide, yielding loss of 2.64 dB/cm at 1530 nm. We demonstrate uniformity of the crystal cross-section down the length of the waveguide and quantify its birefringence. Finally, as a proof-of-concept for patterning more complex device geometries, we demonstrate the use of dynamic phase modulation to grow symmetric crystal junctions with single-pass writing. [ABSTRACT FROM AUTHOR]

Very few studies have been directed at the compositional dependence of the intrinsic photostability of the Ge x Se1− x binary ChG films especially for the Ge-rich films with the mean coordination number ( MCN) larger than 2.67. Here, by measuring the in-situ transmission changes, it shows that the photosensitivity (e.g., photobleaching, PB) of the Ge-rich films (as compared to the GeSe2 film) is attenuated, in fact almost completely eliminated in the film with the largest MCN. A straightforward technique, in-situ Raman spectroscopy, is used to record the time-resolved intrinsic structural changes during the irradiation of the films. The result indicates a transition from PB towards photostability occurs at the critical composition of GeSe2 corresponding to the structural phase transition. The stressed rigid structures of the Ge-rich films inhibit any significant photo-structural changes. [ABSTRACT FROM AUTHOR]

We report a detailed investigation of the charge carrier transport in polycrystalline n-type impurity-doped zinc oxide (ZnO) thin films grown by spray pyrolysis over a wide range of carrier concentrations. Particular attention is devoted to a study of the composition-dependent metal-insulator transition (MIT) in this transparent conducting oxide (TCO). In order to describe the flow of electrons in these impurity-doped thin films over this full range of conditions, it is necessary to consider multiple electronic conduction processes. The first conduction process arises from current carriers thermally excited from impurity states into the (host) ZnO conduction band. The second involves thermally-activated, quantum-mechanical tunnelling within an impurity band located close to the host conduction band. The latter conduction process predominates at low temperatures whilst the former dominates at high temperatures. We find that a MIT occurs at a critical carrier concentration between 2 and 6 × 1019 cm-3. At higher concentrations in this metallic regime, the impurity band merges with the ZnO conduction band. The location of the MIT was determined from low temperature resistivity data and the results are discussed in terms of the Mott and Ioffe-Regel models. In addition, the overriding importance of grain boundaries is highlighted for these polycrystalline thin films; this is a key factor in determining and limiting electronic conduction in these samples, particularly at high temperatures. These results highlight the practical importance of understanding both the MIT and also grain boundary effects in determining the electrical performance of polycrystalline TCO films. [ABSTRACT FROM AUTHOR]

Abstract: Low-Energy Ion Scattering (LEIS) spectroscopy is a technique with a unique sensitivity to the elemental composition of the surface top atomic layers of a solid. LEIS measurements of simple binary silicate glasses (with Na2O, Cs2O or BaO) have shown differences in composition between the as-cast glass surface and the vacuum-fracture surface. The as-cast surface is usually depleted of modifier ions compared to the nominal (batch) bulk glass composition, while the fracture surface is typically enriched with the monovalent modifier species, but not the divalent barium. While the melt surface depletion can probably be attributed to evaporation from the hot melt surface, the origin of the strong accumulation on the fracture surfaces is less clear. It is certainly possible that the fracture may have been preferentially guided by regions already alkali-enriched within the bulk of the glass. But considering the extreme surface sensitivity of this method, a surface-monolayer localized enrichment with alkali due to the stress gradient created by the fracture or the electric field created by dangling bonds on the vacuum-fractured surface is also possible. The Si/O ratio shows usually little deviation from the nominal glass batch value, falling within the estimated errors. [Copyright &y& Elsevier]

The dynamics and reversibility of Ag nanoparticle photodissolution into As2S3 chalcogenide thin films have uniquely been directly measured by continuous AFM imaging during patterned optical illumination. The surface morphology, roughness and particle size distribution have thus been spatially and statistically monitored as a function of time, both during and following optical exposure. Photodissolution was observed to proceed via two mechanisms. In one case, nanoparticles abruptly and nearly completely disappeared along a sharp dissolution front traveling laterally at ~0.19 μm s-1. Following illumination, similarly sized nanoparticles uniformly reformed on the surface. A more inhomogeneous photodissolution process was separately recorded, clearing irregular ~1-2 μm patches that grew with time until most of the surface was free of nanoparticles. Post-illumination, surface nanoparticle development and coverage were similarly inhomogeneous, with larger but 50% fewer particles in the final distribution. In every experiment, an initial roughening was detected before the nanoparticle surface coverage visually diminished, indicating the onset of photodissolution at widely distributed energetically and kinetically favored sites which temporarily enhances nanoscale roughness. Such direct studies of surface dynamics are crucial to understanding and ultimately optimizing chalcogenide film applications such as photomasks, optoelectronics media and bio-chemical sensors. [ABSTRACT FROM AUTHOR]

Abstract: A previews study of germanium selenide glass films by scanning electron microscopy and atomic force microscopy revealed a heterogeneous surface morphology consisting of granular regions ∼15–50nm in size, which cause high optical losses. The present work was performed in order to further characterize such materials using spectroscopic ellipsometry, infrared (IR) and Raman spectroscopies. Chalcogenide glass films with GeSe2, Ge28Sb12Se60 and GeSe compositions have been deposited on single crystal silicon and silica glass substrates by vacuum thermal evaporation. The film thickness and the optical constants were obtained from spectroscopic ellipsometry using the Tauc-Lorenz dispersion formula. A model was derived for the film structure, which included a roughness layer at the surface. This top layer was found to have a thickness of ∼5–15nm, of the order of the size of the granular regions previously reported. The optical bandgap of the samples increased with increasing selenium content, while the refractive index decreased. Despite a previous report of large scale phase separation in bulk Ge26Sb14Se60 glass, the fundamental IR and Raman spectra obtained in the present work did not provide any clear evidence for such phase separation which could be associated with the heterogeneous nanostructure observed at the surface of the films. [Copyright &y& Elsevier]

Abstract: Investigations of light-induced volume expansion and surface pattern recording in amorphous chalcogenide layers and nano-layered structures (NLS) were extended to direct electron-beam recording on Se/As2S3 and Sb/As2S3 NLS. Light as well as e-beam induced bleaching occurs in all NLS, while volume expansion occurs only in chalcogenide–chalcogenide NLS and in homogeneous Se or As2S3 layers. Comparison of these two phenomena revealed the possible role of purely electronic and thermal processes in the interdiffusion and relief formation. The latter is supposed to be connected with radiation-induced defect creation, free volume increase under the increased fluidity conditions as well as with the possible additional influence of electrostatic forces and stress. [Copyright &y& Elsevier]

• Cooling rate strongly affects lithium local structure, density, and diffusivities. • Lithium ions form clusters but only at low cooling rate. • Cooling rate dependence of simulated ionic conductivity agrees with experiments. The effects of cooling rate on the structure and properties of lithium disilicate (LS2) glass are investigated using molecular dynamics (MD) computer simulations. The evolution of structural features such as pair distribution function, bond angle distribution, and Li coordination distribution are determined, and correlated with dynamic and static properties to elucidate the effects of cooling rate. The density, elastic moduli, and diffusion coefficient are found to be highly sensitive to cooling rate, whereas the Si pair distribution function and bond angle distribution are weakly affected by the cooling rate. Additionally, the changes of Si-O-Si bond angle and Li coordination number suggest the formation of Li cluster at lower cooling rates. Furthermore, by comparing results from other simulations and reported experiments, we confirm that the increase of cooling rate leads to an increase of conductivity and a decrease of density. At very high cooling rates, we find that all the atoms in LS2-glass do not relax simultaneously, but do so in two distinct configurations. [ABSTRACT FROM AUTHOR]

High-resolution X-ray photoelectron spectroscopy is used to identify the mechanism of X-ray-induced Ag diffusion into Ge30Se70 chalcogenide glass thin films, which are prepared in situ to avoid oxygen contamination. From the analysis of Ge 3d, Se 3d, and Ag 3d core levels, and valence band spectra, changes in the electronic structure are determined as Ag diffuses gradually with increasing irradiation. The ternary phase based on Ge2Se6 units, which contains homopolar Ge–Ge bonds, forms when diffusion approaches equilibrium where Ag content ∼30 at.%. The formation of a Se-rich composition is indicated in the near-surface region at the initial stage of the process, but the previously assumed Ag2Se phase is not detected. [ABSTRACT FROM AUTHOR]

To understand the unique physical properties of GaSbSe glasses, high‐resolution X‐ray photoelectron spectroscopy (XPS) studies are performed on representative compositions within the glass‐forming region. The observed peaks in the valence band as well as in Ga, Sb, and Se core‐level XPS spectra are related to the main structural building blocks of the covalent network. On the basis of disproportionality equations and quantitative XPS analysis, the SeSeSe fragments are shown to exist in the glasses with 65 and 68 at% of Se, whereas the samples with lower Se content are shown to contain a significant concentration of SeSe bonds instead. Although the majority of Ga atoms are deemed to form fourfold coordinated units, the existence of Ga atoms in threefold coordination, those bonded to other metal, and forming Ga clusters of undissolved Ga are also plausible on the basis of Ga 3d XPS spectrum analysis. Partial or full destruction of antimony selenide pyramids is found in glasses with low Se content. [ABSTRACT FROM AUTHOR]

Thermal poling is a widely used method for creating glass surfaces with modified structure and altered properties by application of DC voltage. The mechanism of structural change has remained controversial, especially as poling is performed well below the glass transition temperature. Specifically, the role of Joule heating in facilitating structural transformation has remained an open question, conceivably through local heating to temperatures approaching Tg. Here, we investigate this possibility directly by in situ measurements of the local glass temperature during poling using infrared imaging. Examination near the anode region reveals only a slight temperature increase (~10°C) above the furnace temperature at the start of poling, and remains a few hundred degrees below Tg throughout. SIMS analysis revealed a ~1‐µm thick alkali depletion layer next to the anode. XPS analysis of the anode, cathode, and unpoled regions shows complex changes in structure and composition including migration of alkali ions, injection of hydrogen at the anode interface, removal of non‐bridging oxygen, and polymerization of the network via electrolysis. All these changes arise as a result of high electric field (~106 V/cm) produced across the highly resistive depletion layer, and refutes any significant increase in the temperature by Joule heating as the cause of their creation. [ABSTRACT FROM AUTHOR]