Modelling of the hysteresis effect of target voltage in reactive magnetron sputtering process by using neural networks

Reactive sputtering process is very non-linear and usually exhibits hysteresis behaviour with respect to the reactive gas flow. Most of the problems encountered in the preparation of non-stoichiometric compound films by reactive sputtering are due to the hysteresis effect. Therefore, a considerable amount of effort has been devoted to find means for its elimination or ensuring a stable sputtering in the transition mode. This paper presents a new approach based on Artificial Neural Networks (ANNs) for modelling of the hysteresis effect of target voltage at different target power levels and reactive gas flow rates in reactive sputtering. Based on this model, it is possible to predict the target voltage in reactive magnetron sputtering processes, when the target power level, reactive gas flow rate and its direction are used as inputs to the artificial neural network (ANN). The proposed ANN is trained in different structures with the use of learning algorithms to obtain better performance and faster error convergence. Broyden–Fletcher–Goldfarb Shanno (BFGS) algorithm gives the best result among other learning algorithms used in the analysis. The training and test data required to develop the ANN model are obtained from the experimental studies. Both the training and the test results are in very good agreement with the experimental results obtained in this work.     

Three-dimensional self-assembly of spherical block copolymer domains into V-shaped grooves

The self-assembly of a spherical-morphology block copolymer into V-shaped grooves has been investigated. Although spherical morphology block copolymers typically form a bcc sphere array in bulk, the V groove promotes the formation of a well-ordered fcc close-packed sphere array with the (111) planes of the array parallel to the groove walls. The sphere size in the block copolymer adjusts depending on the commensurability between the periodicity of the block copolymer and the film thickness within the V groove. The top surface of the close-packed array, parallel to the substrate, shows a square symmetry, unlike the hexagonal symmetry seen in monolayers of spherical domains, which may provide a useful geometry for block copolymer lithography.     

Effects of squeeze casting on the properties of Zn-Bi monotectic alloy

In composite production, the shortest route is via an in situ composite in which a melt dissociates simultaneously into two rather different solid phases. The monotectic alloys can be included in this group. The present work was aimed at extending our recent squeeze casting experience on the Zn-Bi monotectic alloy in order to increase its cast quality and mechanical properties. A squeeze casting unit was built, and its die and punch were machined. The molten monotectic alloy was squeezed in this unit under pressures up to 120 MPa in its freezing range until it solidified completely. It was found that an increase in squeeze casting pressure provided increases in density, tensile strength, and Vickers hardness, which resulted in decreases in chip length and electrical resistivity. Before the squeeze casting practice, the freezing characteristics of this monotectic were estimated using basic solidification principles.     

Interferon-induced vitiligo in a patient with chronic viral hepatitis C infection

Recurrent abdominal pain (RAP) syndrome is described by Apley 40 years ago. The definition of condition, still generally accepted, is at least three episodes of abdominal pain over a period of three months, with pain of intensity which affects the behaviour of the child. The prevalence of condition among school children is 10-15%. Apley's classic studies demonstrated organic disease in only 10% of the children. Apley's conclusions have dominated pediatric writing through present era. In recent years, however, a number of reports have appeared in the medical literature that have suggested that careful investigation of children with RAP may reveal previously unsuspected functional or morphologic abnormalities of the gastrointestinal tract. These have included reports of peptic disease and Helicobacter Pylori infection, abnormal antro-duodenal motility, lactase malabsorption, gastro-esophageal reflux. Nevertheless these abnormalities cannot be correlated always with specific complaints. Therefore pathogenetic background is not clarified. Despite greater understanding of these disorders the enigme remains. There is a need for controlled studies in non selected patients.     

SpyDetector: An approach for detecting side-channel attacks at runtime

International Journal of Information Security - In this work, we first present a low-cost, anomaly-based semi-supervised approach, which is instrumental in detecting the presence of ongoing...     

Side chain functional carbazole-fluorene electroactive polymers: Optical,electrochemical properties,antimicrobial activity and thin film morphologies

A new electroactive polymer based on fluorene and carbazole moieties with double bond side chain (MP25) was synthesized and then double bond at the side chain was functionalized with  COOH and  Si(OEt)₃ as ITO/glass compatible groups. Electrochemical and optical properties of the polymers were elucidated with cyclic voltammetry (CV), ultraviolet–visible absorption (UV–Vis), and photoluminescence (PL) spectroscopy. It was observed that all polymers absorbed only the UV region and emitted blue light. By using CV, HOMO values were found as approximately 5.45 eV. According to AFM results, when the rough MP25 polymer thin film was modified with ITO/glass compatible groups, more uniform and smoother polymer thin films were obtained. Thermogravimetry analyses (TGA) shown that the MP25-Si and MP25-COOH were stable against thermo-oxidative decomposition. The weight loss of MP-25-Si was found to be only %23 at 700°C. Additionally, antimicrobial activity of MP25 polymers was also investigated. According to test results, all polymers were found to have antimicrobial activity against C.albicans.     

Coreless Fiber‐Based Whispering‐Gallery‐Mode Assisted Lasing from Colloidal Quantum Well Solids

Whispering gallery mode (WGM) resonators are shown to hold great promise to achieve high‐performance lasing using colloidal semiconductor nanocrystals (NCs) in solution phase. However, the low packing density of such colloidal gain media in the solution phase results in increased lasing thresholds and poor lasing stability in these WGM lasers. To address these issues, here optical gain in colloidal quantum wells (CQWs) is proposed and shown in the form of high‐density close‐packed solid films constructed around a coreless fiber incorporating the resulting whispering gallery modes to induce gain and waveguiding modes of the fiber to funnel and collect light. In this work, a practical method is presented to produce the first CQW‐WGM laser using an optical fiber as the WGM cavity platform operating at low thresholds of ≈188 µJ cm^?2 and ≈1.39 mJ cm^?2 under one‐ and two‐photon absorption pumped, respectively, accompanied with a record low waveguide loss coefficient of ≈7 cm^?1 and a high net modal gain coefficient of ≈485 cm^?1. The spectral characteristics of the proposed CQW‐WGM resonator are supported with a numerical model of full electromagnetic solution. This unique CQW‐WGM cavity architecture offers new opportunities to achieve simple high‐performance optical resonators for colloidal lasers.     

In-source and post-irradiation polymerization of acenaphthylene in the solid state

Radiation-induced solid state polymerization of acenaphthylene was studied by using ⁶⁰Co γ-rays. The extent of polymerization at room temperature reached 68% when acenaphthylene was irradiated with a dose of 2–5 MGy. Prolonged exposure to the radiation decreased the molecular weight of the polymers. The post-polymerization of acenaphthylene was found to occur at relatively high temperatures close to the melting point of acenaphthylene. Absence of an effective termination step allows the enhancement of post-polymerization at higher temperatures after a limiting conversion is accomplished.