Influence of thallium doping on structural,electrical, and optical properties of ZnO nanorods for TCO applications

Journal of Materials Science: Materials in Electronics - Thallium (Tl)-doped ZnO nanorods were prepared (the doping ratios were between 0 and 5 mol %) in two stages. Combined sol–gel...     

Room-Temperature-Formed PEDOT:PSS Hydrogels Enable Injectable,Soft, and Healable Organic Bioelectronics

There is an increasing need to develop conducting hydrogels for bioelectronic applications. In particular, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hydrogels have become a research hotspot due to their excellent biocompatibility and stability. However, injectable PEDOT:PSS hydrogels have been rarely reported. Such syringe-injectable hydrogels are highly desirable for minimally invasive biomedical therapeutics. Here, an approach is demonstrated to develop injectable PEDOT:PSS hydrogels by taking advantage of the room-temperature gelation property of PEDOT:PSS. These PEDOT:PSS hydrogels form spontaneously after syringe injection of the PEDOT:PSS suspension into the desired location, without the need of any additional treatments. A facile strategy is also presented for large-scale production of injectable PEDOT:PSS hydrogel fibers at room temperature. Finally, it is demonstrated that these room-temperature-formed PEDOT:PSS hydrogels (RT-PEDOT:PSS hydrogel) and hydrogel fibers can be used for the development of soft and self-healable hydrogel bioelectronic devices.     

Microscopic design and optimization of hydrodynamically lubricated dissipative interfaces

A homogenization-based topology optimization framework is developed, which can endow hydrodynamically lubricated interfaces with a micro-texture, to achieve optimal macroscopic responses by addressing both dissipative and nondissipative physics at the interface. With respect to the homogenization aspects of the problem, the thermodynamic consistency of the two-scale formulation is explicitly analyzed and verified. With respect to the topology optimization aspects, a variational approach to sensitivity analysis is pursued. Subsequently, these are employed in micro-texture design studies, which address microscopic and macroscopic objectives. The influence of dissipation on the optimization results is demonstrated through extensive numerical investigations, which also highlight the importance of working in a sufficiently flexible design space that can deliver nearly optimal micro-texture geometries.     

An Effective Classifier Model for Imbalanced Network Attack Data

Recently, machine learning algorithms have been used in the detection and classification of network attacks. The performance of the algorithms has been evaluated by using benchmark network intrusion datasets such as DARPA98, KDD’99, NSL-KDD, UNSW-NB15, and Caida DDoS. However, these datasets have two major challenges: imbalanced data and high-dimensional data. Obtaining high accuracy for all attack types in the dataset allows for high accuracy in imbalanced datasets. On the other hand, having a large number of features increases the runtime load on the algorithms. A novel model is proposed in this paper to overcome these two concerns. The number of features in the model, which has been tested at CICIDS2017, is initially optimized by using genetic algorithms. This optimum feature set has been used to classify network attacks with six well-known classifiers according to high f1-score and g-mean value in minimum time. Afterwards, a multi-layer perceptron based ensemble learning approach has been applied to improve the models’ overall performance. The experimental results show that the suggested model is acceptable for feature selection as well as classifying network attacks in an imbalanced dataset, with a high f1-score (0.91) and g-mean (0.99) value. Furthermore, it has outperformed base classifier models and voting procedures.     

Design and Realization of a Microcontroller Based E-Test Strip Application Device

Abstract

In this study, a device that supplies a microcontroller controlled E-test strip application was developed. It was aimed to gather two devices which are needed for E-test strip application's stages, i.e., inoculation onto agar plate and placement of E-test strip, into a device to thus reduce the cost and time required for this application. A PIC16F877A microcontroller was used in the system and it was programmed in Microcode Studio Plus Editor by using the PIC Basic Programming Language. The circuit whose design was realized was tested under circumstances in the laboratory and real medium. The designed system is in a state that can be used in hospitals as it is.     

Electrochemical synthesis and characterization of poly (o-amino benzyl alcohol) and poly (o-amino benzyl alcohol-co-o-anisidine)

In this study; poly (o-amino benzyl alcohol) and poly (o-amino benzyl alcohol-co-o-anisidine) copolymer films were electrochemically synthesized by cyclic voltammetry technique on the platinum electrode. The synthesis of copolymer films was achieved in various monomers feed ratio (o-amino benzyl alcohol: o-anisidine; 8:2, 1:1, 2:8) of o-amino benzyl alcohol and o-anisidine. Different solution types were tested in aqueous and non-aqueous media, especially during the synthesis process, as the electrolyte medium. As a result of the experiments, it was determined that sulfuric acid solution was the most suitable solution for both homopolymer and copolymer film growth. Homopolymer and copolymer samples were characterized by FT-IR, cyclic voltammetry (CV), SEM, digital images and TGA/DTA techniques. The CV, SEM and digital images results indicated that the solution which has high ratio of monomer is more effective in copolymer film synthesis mechanism. TGA results showed that the 1:1 copolymer film had higher thermal stability than the films at other monomer ratios. Also, electrochemical studies exhibited that the copolymer film in 1:1 ratio is partially more electrochemically stable than other copolymer films.     

An experimental investigation of oblique cutting mechanics

In this study, an experimental investigation of oblique cutting process is presented for titanium alloy Ti-6Al-4V, AISI 4340, and Al 7075. Important process parameters such as shear angle, friction angle, shear stress, and chip flow angle are analyzed. Transformation of the data from the orthogonal cutting test results to oblique cutting process is applied, and the results are compared with actual oblique cutting tests. Effects of hone radius on cutting forces and flank contact length are also investigated. It is observed that the shear angle, friction angle, and shear stress in oblique cutting have the same trend with the ones obtained from the orthogonal cutting tests. The transformed oblique force coefficients from orthogonal tests have about 10% discrepancy in the feed and tangential directions. For the chip flow angle, the predictions based on kinematic and force balance results yield better results than Stabler's chip flow law. Finally, it is shown that the method of oblique transformation applied on the orthogonal cutting data yields more accurate results using the predicted chip flow angles compared to the ones obtained by the Stabler's rule.     

Squeezing flow of nanofluids of Cu–water and kerosene between two parallel plates by Gegenbauer Wavelet Collocation method

Operational matrices of Gegenbauer wavelets have significant role for approximate solution of differential equations. In the present study, approximate solutions of the squeezing nanofluids of Cu–kerosene and Cu–water between parallel plates with magnetic field are obtained by GW Collocation Method. The governing nonlinear PDEs may be turned into the nonlinear ODEs by similarity transformation. These nonlinear equations are turned into the set of linear ODEs by quasilinearization technique. The effective thermal conductivity and the effective dynamic viscosity of nanofluids have been taken as models of Maxwell–Garnetts and Brinkman. The effects of physical parameters have been displayed by graphs and tables.

     

Thermally Stable Phosphonium Organoclay-Reinforced Polyimide Nanocomposites

To prepare clay containing high-temperature processable polymer nanocomposites, new cation exchangeable agents with high thermal stability are required. In this work, we investigated the effect of a thermally stable phosphonium-modified organoclay on the properties of polyimides prepared from the reaction of 4,4′-oxydianiline with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride. The organoclay was prepared from the reaction of pristine clay with octyltriphenylphosphonium bromide. Phosphonium-modified clay displayed a negligible weight loss (<5%) below 300°C. The thermal stability of the composites enhanced with the increasing amount of phosphonium-modified clay.     

Enhanced removal of nickel(II) ions from aqueous solutions by SDS-functionalized graphene oxide

In this paper, a one-pot and easy-to-handle method at room temperature without additional chemicals for the modification of graphene oxide (GO) with surfactant is found. Removal of nickel (II) ions from aqueous solutions by GO and surfactant (sodium dodecyl sulphate) modified graphene oxide (SDS-GO) was studied spectrophotometrically at room temperature as a function of time, initial concentration and pH. Adsorption capacity of the adsorbent was increased dramatically (from 20.19 to 55.16 mg/g found by Langmuir model) due to the functionalization of the surface by SDS. The driving force of the adsorption of Ni(II) ions is electrostatic attraction and Ni(II) ions adsorbed on the GO surface chemically besides ion exchange.