Analyzing UV/Vis/NIR spectra with the single-layer model—Sputtered SnS thin films I: Space-time dependencies

Exact, contact-free and non-destructive, optical analysis of semiconducting layers, are advantageous for thin film solar cell applications. A non-numerical theoretical model has been developed to extract approximation-free optical and electrical data from UV/Vis/NIR spectra. Special focus has been set on single layers; an adequate single-layer model is provided. Complex parameter evaluation is possible.This exact data acquisition model provides deeper insights in the process-parameter dependencies of pulsed direct current and radio frequency sputtered, opaque tin-sulphide thin films upon glass substrates. They have been analysed with respect to space-time dependencies of the sputter process. Therefore, sputter-depositions have been examined, referring to positions upon the substrate, r, target-substrate distances, d_TarSub, and sputter durations, t_Sp. Theoretical sputter-concepts were proved and enhanced. Results were compared with those of the well-known Keradec/Swanepoel model. The necessity of taking both spectra—transmission and reflection spectra—into account has been shown.A non-contact, optical conductivity measurement possibility by use of UV/Vis/NIR spectroscopy has been provided. Optically evaluated conductivities, σ_L, were compared with electrically taken values, by use of a four-tip measurement system.     

Full-wave analysis of a nonradiative dielectric waveguide with apseudochiral Ω-slab

This paper presents a new microwave device - a non-radiative dielectric (NRD) waveguide with a dielectric pseudochiral Ω-slab - the Ω-NRD waveguide. A rigorous full-wave analysis is presented and the modal equations for the longitudinal-section magnetic (LSM) and longitudinal-section electric (LSE) modes are derived. The dispersion curves and operational diagrams for the first hybrid LSM modes are presented. The effect of the pseudochiral Ω-medium is discussed. New interesting modal features are revealed, showing that the propagation characteristics may differ considerably from the common isotropic case     

Tumors of the papilla of Vater--diagnostic and therapeutic dilemmas

Benign and malignant tumors of papilla Vateri are rare diagnoses in the endoscopic practice. Sixteen patients with benign and 22 cases of malignant tumors are presented. In all of them endoscopic cholangiopancreatography with or without papillotomy followed by biopsy and operation in 13 cases was performed. Biopsy confirmed the endoscopy in 71%. Adenomyosis, supposed by endoscopy was proved by repeated histology in only 2/9 cases although invasive component of the tumor was found in 3/9 patients at operation underlying precancerous nature of this entity. Among 5 cases of villous adenoma one developed malignant alterations during 4 years of follow-up. Biopsy was not more effective after papillotomy than without it, and 5-7 days of delay for recovery of thermic lesion did not ameliorate success rate of histology. For malignant diseases surgical therapy should be considered if staging of tumor and general condition of the patient permits. In unresectable cases endoscopic palliation (papillotomy or polypectomy with or without drainage) can increase survival. In patients with benign tumors operative endoscopy followed by regular ultra-sonography and endoscopy seems to be necessary.     

Effects of Osthole on Inflammatory Gene Expression and Cytokine Secretion in Histamine-Induced Inflammation in the Caco-2 Cell Line

Hyperactivity of the immune system in the gastrointestinal tract leads to the development of chronic, inflammation-associated disorders. Such diseases, including inflammatory bowel disease, are not completely curable, but the specific line of treatment may reduce its symptoms. However, the response to treatment varies among patients, creating a necessity to uncover the pathophysiological basis of immune-mediated diseases and apply novel therapeutic strategies. The present study describes the anti-inflammatory properties of osthole during histamine-induced inflammation in the intestinal Caco-2 cell line. Osthole reduced the secretion of cytokines (CKs) and the expression level of inflammation-associated genes, which were increased after a histamine treatment. We have shown that the secretion of pro-inflammatory CKs (IL-1β, IL-6, IL-8, and TNF-α) during inflammation may be mediated by NFκB, and, after osthole treatment, this signaling pathway was disrupted. Our results suggest a possible role for osthole in the protection against inflammation in the gastrointestinal tract; thus, osthole may be considered as an anti-inflammatory modulator.     

Combustion characteristics and kinetics of diesel and canola oil samples

In this study, combustion and pyrolysis behavior of diesel and canola oil is investigated using thermal analysis techniques known as thermogravimetry (TG–DTG) and differential scanning calorimetry (DSC) at different heating rates. Reaction regions, peak temperatures, mass loss, heat flow rates, ignition temperatures, and specific heat of diesel and canola oil samples are determined using TG–DTG and DSC data. It was observed that as the heating rate of the reactions increased, peak temperatures of the reactions shift higher; implying that as the heating rate of the reactions increases the reactions lose their sensitivity. Five different kinetic methods were applied to determine combustion reaction parameters of the reactions. It was observed that averages of the activation energies of the samples are in the order of canola oil and diesel for different heating rates.     

Special Issue of Bianisotropics 2000: Guest Editorial

An introduction to this special issue devoted to Bianisotropics 2000 – 8th International Conference on Electromagnetics of Complex Media, is provided.     

Least Squares Boundary Residual Method for the Analysis of Step Discontinuities in Open Chiral Waveguides

We analyse the reflection, transmission and radiation characteristics of a step discontinuity in a grounded chiral slab and we show that the step radiation can be enhanced due to the effect of the chirality. The analysis is performed using a mode matching technique. The fields are expressed in terms of the discrete modes and the continuous spectrum using two subsets of hybrid radiation modes: incident transverse electric (ITE) and incident transverse magnetic (ITM) modes. The scattering matrix of the step is determined by minimizing the boundary residual error in the sense of the least squares. The influence of chirality on the characterization of the step is demonstrated and we show that control of the radiation pattern is achieved, including angle and width of the radiation beam.     

Sulfosalts — A new class of compound semiconductors for photovoltaic applications

A short historical outline of sulfosalts with respect to their mineralogical origin and their possible technical applications is given. The high number of more than 200 species results from their chemical and structural definition. The modular crystal structures of sulfosalt compounds base on superstructures of diverse construction units. Physical properties of mineral samples as well as deposited thin films show promising results with respect to photovoltaic application. As a proof of concept, first sulfosalt thin film solar cells were prepared. The efficiency of this cell is reported to be 1%. Further efforts will be done to improve efficiency.     

Modeling asymmetric dependences among multivariate soil data for the geotechnical analysis – The asymmetric copula approach

Multivariate information of soil parameters is quite important for the design and risk assessment of geotechnical engineering problems. It is necessary to have an accurate and realistic statistical multivariate model for representing the soil properties and thus evaluating the soil conditions. Thus, advanced multivariate modeling of soil parameters could help to improve the geotechnical engineering practice. In this paper, the asymmetric copulas are introduced to model the geotechnical soil data. Compared to extensive previous research on the use of symmetric copulas on the modeling of engineering data, this study is focusing on capturing asymmetric dependencies among the natural soil parameters, which are critical for engineering design. A copula-based multivariate probabilistic model is built based on a set of collected samples from a granite residual soil from Portugal. Several asymmetric copula functions, capable of capturing nonlinear asymmetric dependence structures, are tested and analyzed. The fundamental information on tail dependencies and measures of asymmetric dependencies are also exploited. To demonstrate the advantages of asymmetric copulas, its concept is compared with the traditional copula approaches for modeling site soil data. The performance of these asymmetric copulas is discussed and compared based on data fitting and extreme value characterizations.     

Fatigue failure prediction of a rear axle housing prototype by using finite element analysis

A premature failure that occurs prior to the expected load cycles during the vertical fatigue tests of a rear axle housing prototype is studied. In these tests, crack mainly originated from the same region on test samples. To determine the reason of the failure, a detailed CAD model of the housing was developed. Mechanical properties of the housing material were determined via tensile tests. Using these data, stress and fatigue analyses were performed by finite element method. Fatigue crack initiation locations and minimum number of load cycles before failure initiation were determined. Results provided from tests were compared with the analyses. Design enhancement solutions were proposed to increase the fatigue life of the housing.