Range Of Energy Levels Research Articles

High-resolution phantom of a nephron for radiation nephrotoxicity evaluation in biophysical simulations

<abstract> <p>Computer simulation plays an important role in medical physics. The aim of this study was to generate an accurate model to calculate the absorbed dose at the cell level in a voxelized phantom of nephrons. In order to implement a model of kidney microdosimetry, a 3D mesh phantom of a human kidney nephron, representing a cortical nephron, was digitized to create a 3D voxelized phantom of a nephron for use in Monte Carlo simulations. The phantom was fed to GATE Monte Carlo toolkits, and simulations were performed to calculate the absorbed dose/energy from alpha and electron sources over a range of energy levels. The results were compared to the results published in literature that were derived by using a stylized phantom. The dose estimated in subunits of the voxelized and stylized phantoms showed a considerable bias (average of relative differences). The maximum difference for self-absorption was 12.5%, and up to 20% for cross-absorption. The digital phantom showed very significant differences in dose distribution among the cells in different subunits of the nephron. The results demonstrated that a small dissimilarity in the size and shape of subunits can lead to a considerable difference in the microdosimetry results. The model presented in this study offers a phantom that not only presents the realistic geometry of a nephron, which has been neglected in previous stylized models, but also one that has the capability of plotting the spatial distribution of the absorbed dose for any distribution of radiopharmaceuticals in nephron cells.</p> </abstract>

The time independent fractional Schrödinger equation with position-dependent mass

In this paper, we present a fractional form of Schrödinger equation using the Kallil’s derivative method. Then we investigate the capability of this equation to obtain the wave functions and its energy levels for a particle trapped in infinite potential well (IPW) for the range1<α≤2. We also, present the fractional form of the Schrödinger equation for a particle with position-dependent mass (PDM) and by using it, we obtain wave functions and its energy levels in range 0 <α≤1 and in different amounts of η and μ in which μ + η = 1/2. It seems that our method is very useful to solve the problems in PDM case.

On the Origin of Dark Current in Organic Photodiodes

AbstractMinimizing the reverse bias dark current while retaining external quantum efficiency is crucial if the light detection sensitivity of organic photodiodes (OPDs) is to compete with inorganic photodetectors. However, a quantitative relationship between the magnitude of the dark current density under reverse bias ( Jd) and the properties of the bulk heterojunction (BHJ) active layer has so far not been established. Here, a systematic analysis of Jd in state‐of‐the‐art BHJ OPDs using five polymers with a range of energy levels and charge transport characteristics is presented. The magnitude and activation energy of Jd are explained using a model that assumes charge injection from the metal contacts into an energetically disordered semiconductor. By relating Jd to material parameters, insights into the origin of Jd are obtained that enable the future selection of successful OPD materials.

A dose-response study of a novel method of selective tissue modification of cellular structures in the skin with nanosecond pulsed electric fields.

Background and ObjectivesThis study describes the effects of nanosecond pulsed electric fields (nsPEF) on the epidermis and dermis of normal skin scheduled for excision in a subsequent abdominoplasty. NsPEF therapy applies nanosecond pulses of electrical energy to induce regulated cell death (RCD) in cellular structures, with negligible thermal effects. Prior pre‐clinical studies using nsPEF technology have demonstrated the ability to stimulate a lasting immune response in animal tumor models, including melanoma. This first‐in‐human‐use of nsPEF treatment in a controlled study to evaluate the dose‐response effects on normal skin and subcutaneous structures is intended to establish a safe dose range of energies prior to use in clinical applications using nsPEF for non‐thermal tissue modification.Study Design/Materials and MethodsSeven subjects with healthy tissue planned for abdominoplasty excision were enrolled. Five subjects were evaluated in a longitudinal, 60‐day study of effects with doses of six nsPEF energy levels. A total of 30 squares of spot sizes 25mm2 or less within the planned excision area were treated and then evaluated at 1 day, 5 days, 15 days, 30 days, and 60 days prior to surgery. Photographs were taken over time of each treated area and assessed by three independent and blinded dermatologists for erythema, flaking and crusting using a 5‐point scale (0 = low, 4 = high). Punch biopsies of surgically removed tissue were processed and evaluated for tissue changes using hematoxylin and eosin, trichome, caspase‐3, microphthalmia transcription factor, and elastin stains and evaluated by a dermatopathologist. The skin of two subjects received additional treatments at 2 and 4 hours post‐nsPEF and was evaluated in a similar manner.ResultsMost energy settings exhibited delayed epidermal loss followed by re‐epithelization by day 15 and a normal course of healing. Histologic analysis identified the appearance of activated caspase‐3 at two and four hours after nsPEF treatment, but not at later time points. At the 1‐day time point, a nucleolysis effect was observed in epidermal cells, as evidenced by the lack of nuclear staining while the epidermal plasma membranes were still intact. Cellular structures within the treatment zone such as melanocytes, sebaceous glands, and hair follicles were damaged while acellular structures such as elastic fibers and collagen were largely unaffected except for TL6 which showed signs of dermal damage. Melanocytes reappeared at levels comparable with untreated controls within 1 month of nsPEF treatment.ConclusionsThe selective effect of nsPEF treatment on cellular structures in the epidermal and dermal layers suggests that this non‐thermal mechanism for targeting cellular structures does not affect the integrity of dermal tissue within a range of energy levels. The specificity of effects and a favorable healing response makes nsPEF ideal for treating cellular targets in the epidermal or dermal layers of the skin, including treatment of benign and malignant lesions. NsPEF skin treatments provide a promising, non‐thermal method for treating skin conditions and removing epidermal lesions. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Near-Infrared Photoresponse in Photon-Triggered Nanowire Transistors

We investigated a photon-triggered nanowire transistor with near-infrared spectral photoresponse. To understand the mechanism of operation of the nanowire transistor consisting of crystalline Si and porous Si segments, we performed a qualitative analysis of trapped carriers in the porous Si and modeling of a transistor operated by photon gating. We then fabricated a photon-triggered transistor device with a nanowire diameter of 200 nm and a porous Si length of 400 nm. Systematic measurements and analyses demonstrate that the wavelength dependence of the photon-triggered current generation is caused by a broad range of energy levels for the localized trap states of the porous Si segment. We believe that these results pave the way for simplification of the fabrication and operation of ultracompact nanoprocessors and development of efficient nanoscale photodetectors for high-resolution imaging.

4-quinolin-8-yloxy Linked Triphenylamine Based Polyimides: Blue Light Emissive and Potential Hole-Transport Materials.

A series of fluorescent donor- acceptor (D-A) alternating copolyimides (P1, P2, P3 and P4) with 4-quinolin-8-yloxy linked triphenylamine main polymer chain have been synthesized by conventional polycondensation. All the synthesized co-polyimides were characterized by elemental, gel permeation chromatography and FTIR spectral analysis. These newly prepared PIs possess HOMO energy levels in range of - 4.74 to - 4.78eV and have medium optical band gaps. The photoluminescence spectral analysis revealed blue to violet emission with appreciable efficiency with lower onset oxidation potentials suitable for the facile hole injection materials. All the photophysical and electrochemical properties were also explored in context of effect of the pendant 4- quinolin-8-yloxy, indicating suitable combination of donor (TPA) on one hand and imide and pendant as acceptor on both ends.Graphical Abstract.

Probing Interface Defects in Top-Gated MoS2 Transistors with Impedance Spectroscopy.

The electronic properties of the HfO2/MoS2 interface were investigated using multifrequency capacitance-voltage (C-V) and current-voltage characterization of top-gated MoS2 metal-oxide-semiconductor field effect transistors (MOSFETs). The analysis was performed on few layer (5-10) MoS2 MOSFETs fabricated using photolithographic patterning with 13 and 8 nm HfO2 gate oxide layers formed by atomic layer deposition after in-situ UV-O3 surface functionalization. The impedance response of the HfO2/MoS2 gate stack indicates the existence of specific defects at the interface, which exhibited either a frequency-dependent distortion similar to conventional Si MOSFETs with unpassivated silicon dangling bonds or a frequency dispersion over the entire voltage range corresponding to depletion of the HfO2/MoS2 surface, consistent with interface traps distributed over a range of energy levels. The interface defects density (Dit) was extracted from the C-V responses by the high-low frequency and the multiple-frequency extraction methods, where a Dit peak value of 1.2 × 1013 cm-2 eV-1 was extracted for a device (7-layer MoS2 and 13 nm HfO2) exhibiting a behavior approximating to a single trap response. The MoS2 MOSFET with 4-layer MoS2 and 8 nm HfO2 gave Dit values ranging from 2 × 1011 to 2 × 1013 cm-2 eV-1 across the energy range corresponding to depletion near the HfO2/MoS2 interface. The gate current was below 10-7 A/cm2 across the full bias sweep for both samples indicating continuous HfO2 films resulting from the combined UV ozone and HfO2 deposition process. The results demonstrated that impedance spectroscopy applied to relatively simple top-gated transistor test structures provides an approach to investigate electrically active defects at the HfO2/MoS2 interface and should be applicable to alternative TMD materials, surface treatments, and gate oxides as an interface defect metrology tool in the development of TMD-based MOSFETs.

A general method for the generation and extension of collinear libration point orbits

This paper is devoted to the study on applying numerical techniques to accurately compute and robustly extend the libration point orbits (LPOs). A new methodology is proposed exploiting the hyperbolic dynamics of the collinear libration points. Numerical tools are developed to facilitate the efficient computation process, which are applicable to realistic force models and inherently parallelizable. Extensive numerical explorations in the Earth–Moon system are carried out, revealing the delicate structures of nested island chains and bounded chaotic motions on the center manifold. Numerical results confirm that the proposed approach can handle the computations of various types of LPOs in a unified manner and is operational over a wide range of energy levels. LPOs obtained with this approach offer a broad range of future mission possibilities in an extended vicinity of the collinear libration points.

Dependence of overcurrent failure modes of IGBT modules on interconnect technologies

Insulated gate bipolar transistor (IGBT) modules which can fail to short circuit mode have great of applications in electricity network related fields. Single IGBT samples have been constructed with the standard Al wire bonding, flexible printed circuit board (PCB) interconnect and sandwich structure technologies. The overcurrent failure modes of the constructed IGBT samples have been tested under a range of energy levels, and the structures of the tested samples have been characterized with scanning electronic microscopy and three-dimensional X-ray computed tomography imaging. The results obtained indicate that the IGBT samples constructed with the three interconnect technologies can fail to both open circuit mode and short circuit mode. The sandwich structure IGBT sample can fail to short circuit mode under an energy level of 750J which can meet realistic industrial applications. The networked conductive phases within the solidification structure and the Sn-3.5Ag filled in the cracks within the residual Si IGBT are responsible for forming the conducting paths in the tested samples. Both liquid phase and gas phase can be formed and the highest temperature can reach the boiling point of Si even if the sandwich structure IGBT sample is tested with short circuit failure mode.

Coal breakage characterisation – Part 1: Breakage testing with the JKFBC

An improved method for coal breakage characterisation has been developed at the Julius Kruttschnitt Mineral Research Centre (JKMRC). Part 1 of this paper presents the breakage testing method and results, Part 2 gives a breakage model that determines the energy-size reduction relationship for multi-components of particle size and coal density, and Part 3 demonstrates the applications of the model for HGI predictions and coal breakage simulations.The new method incorporates hardware for a fine particle breakage characterisation test, the JKFBC (JK Fine-particle Breakage Characteriser), a device modified from the standard HGI mill, which has a precision torquemeter installed to record energy utilisation during the experiments. Distinguished from the traditional HGI test, which is based on a single particle size with a single energy, the new characterisation test offers the flexibility to grind coal particles at various sizes, or various densities, or indeed (various components) with a range of energy levels. Energy consumption during the grinding was recorded. Using an Australian and a Chinese coal sample collected from power stations, this paper demonstrates the effects of particle size and density on coal breakage, and elucidates the deficiencies associated with the traditional HGI test.

Temperature Dependence of Electrical Characterization in n+ - CdS/ p - CdTe Thin Film Solar Cells – Study of Shallow/Deep Defects

ABSTRACTFor CdTe there is no real distinction between defects and impurities exists when non-shallow dopants are used. These dopants act as beneficial impurities or detrimental carrier trapping centers. Unlike Si, the common assumption that the trap energy level Et is around the middle of the band-gap Ei, is not valid for thin film CdTe. Trap energy levels in CdTe band-gap can distributed with wide range of energy levels above EF. To identify the real role of traps and dopants that limit the solar cell efficiency, a series of samples were investigated in thin film n+-CdS/p-CdTe solar cell, made with evaporated Cu as a primary back contact. It is well known that process temperatures and defect distribution are highly related. This work investigates these shallow level impurities by using temperature dependent current-voltage (I-V-T) and temperature dependent capacitance-voltage (C-V-T) measurements. I-V-T and C-V-T measurements indicate that a large concentration of defects is located in the depletion region. It further suggests that while modest amounts of Cu enhance the cell performance by improving the back contact to CdTe, the high temperature (greater than ∼100°C) process condition degrade device quality and reduce the solar cell efficiency. This is possibly because of the well-established Cu diffusion from the back contact into CdTe. Hence, measurements were performed at lower temperatures (T = 150K to 350K). The observed traps are due to the thermal ionization of impurity centers located in the depletion region of p-CdTe/n+-CdS junction. For our n+-CdS/p-CdTe thin film solar cells, hole traps were observed that are verified by both the measurement techniques. These levels are identical to the observed trap levels by other characterization techniques.

Friction stir welding of aluminium 7136-T76511 extrusions

This research programme evaluates the as welded properties of Al 7136-T76511 extrusions joined through friction stir welding (FSW). Microstructural characterisation and mechanical testing were performed on the baseline material and on panels friction stir welded at 250 and 350 rev min–1 (all other weld parameters held constant). Transmission electron microscopy revealed the microstructural features in each of the unique weld regions and demonstrated that the precipitate density and morphology in these regions correlates with the temperature profile produced by the FSW process. A thermal model of FSW is developed that utilises an energy based scaling factor to account for tool slip. The slip factor is derived from an empirical relationship between the ratio of the maximum welding temperature to the solidus temperature and energy per unit length of weld. The thermal model successfully predicts the maximum welding temperatures and profiles over a range of energy levels. The mechanical behaviour after welding is correlated to the temperature distribution predicted by the model and to the observed microstructural characteristics. As welded mechanical properties of the alloy trended positively with the energy per unit length of weld, i.e. the highest joint efficiency was achieved at the highest welding temperature.

Índice de desagregação do solo baseado em energia ultra-sônica

A estabilidade de agregados tem sido determinada por meio de peneiramento úmido, impacto de gotas e, mais recentemente, sonificação. O objetivo deste trabalho foi propor um índice baseado em níveis de energia ultra-sônica para expressar a estabilidade de agregados, utilizando material de horizontes A e B de Latossolo Roxo e Terra Roxa Estruturada. Agregados de 4,76 a 7,93 mm foram submetidos a níveis crescentes de energia ultra-sônica. O índice de dispersão (massa de agregados secos e, ou, partículas &lt; 0,053 mm/massa inicial de agregados) foi plotado em função da energia correspondente para dispersão de cada amostra. As curvas de dispersão foram linearizadas, dividindo-se a energia pelo índice de dispersão, obtendo-se uma equação do tipo EA/ID = a + bEA. O índice de desagregação foi obtido, dividindo-se os termos b/a da equação, tendo como unidade mL J-1. Quanto menor o índice de desagregação, maior a estabilidade de agregados, principalmente para amostras dos horizontes A de ambos os solos. A vantagem desse índice sobre um único nível de energia ou mesmo o diâmetro médio geométrico se deve ao fato de ele considerar toda a faixa de energia empregada na curva de dispersão.

Electrical Properties Of Undoped Polycrystalline Diamond Thin Films On Silicon

ABSTRACTWe have investigated the electrical properties of undoped polycrystalline diamond thin films deposited on (100)-oriented n-type and p-type silicon substrates. The films, intended for electronic applications, were manufactured using hot filament chemical vapour deposition (HFCVD). To a large extent the capacitance-voltage characteristics are influenced by traps located close to the interface between the diamond layer and the silicon substrate. These traps play an important role for voltage sharing between the diamond layer and the silicon space charge region. The DC current density through the diamond film has the same functional dependence on the electric field for films deposited on both n- and p-Si. The field dependency agrees with a Frenkel-Poole transport model. Further, although the DC current transport is thermally activated, it does not follow an Arrhenius relation. A possible reason is that traps within a broad range of energy levels are involved in the charge transport. Finally, current transients resulting from stepwise changes in the applied voltage follow a power law time dependence where the kinetics depend only weakly on temperature.

Response of Growing Turkeys to Dietary Energy Levels

Two consecutive trials were conducted with male Large White turkeys grown from day-old to 20 weeks of age on diets formulated to contain 0, 2, 4, 6, and 8% fat with constant amino acid:energy ratios. The addition of 2 and 4% fat significantly improved body weight gain; higher levels gave no further improvement.Feed conversion efficiency was improved by the addition of fat to the diet, but caloric efficiency remained relatively constant over the range of energy levels, indicating that there was no “extracaloric” effect of fat observed in this study. Possible contributions of methods of feed formulation toward the possibility of the occurence of this phenomenom are discussed.

Association of Lithologies and Sedimentary Structures in Marine Deltaic Paleoenvironments

ABSTRACT Rock types and sedimentary structures in the New York Devonian nearshore marine Catskill Delta provide inter-relationships that can be used to identify other deltaic paleoenvironments. Triangular prisms with four rock types as end members were constructed in order to display the range in lithology existing in outcrops where a given sedimentary structure was identified. The structural prisms were then arranged according to the similarities and differences of their patterns. This arrangement resulted in a structural ranking: low rank-flute casts to high rank-oscillation ripples. A low rank signifies an environment of low energy and hydrodynamic unsteadiness (variability) whereas high rank indicates higher energy and a more hydrodynamically steady state. Siltstones, shales and mudstones end to be associated with the former, sandstones and rudites with the latter. Lithologic and structural data have been reorganized according to an earlier field-based paleoenvironmental classification. Higher ranked structures and coarser sediments were significantly abundant in the delta front and distributary bar environments but significantly rare in the open shelf and prodelta environments. Just the opposite is true for the finer-grained sediments and low-ranked structures. The platform, estuarine and lagoonal paleoenvironments provide less well-defined patterns attributable to the greater range of energy levels operating there. These associations provide criteria that can help to distinguish the paleoenvironments in other marine deltaic settings.

CXXIV. Statistics of the occupation of dislocation acceptor centres

Abstract This paper is a sequel to a previous one (Read 1954) dealing with the acceptor centres associated with dislocations in germanium. The previous paper developed two approximations for the statistics of occupation of dislocation acceptors. This paper presents some further approximations that take account of the non-uniform spacing of accepted electrons along the dislocation. It also treats the case where the dislocation acceptors have a range of energy levels (rather than a single level). The several approximations are compared by plotting the fraction of acceptors that are full vs. temperature for a particular example.