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Machine vision assessment methodology has become increasingly appealing for manufacturing automation due to innovations in noninvasive technologies such as eddy current and ultrasonic testing, which have enhanced the circumstances for bearing defect identification. At this point, manual detection results in low lifespans and reliability. So, we present an innovative rider optimization-driven mutated convolutional neural network (RO-MCNN) technique for surface defect detection of bearings based on machine vision. To evaluate the effectiveness of the suggested approach, samples of the bearing surface with various defects were gathered. The raw data specimens are denoised using a Gaussian filter, and the defect-oriented surface patterns are then extracted using a local binary pattern (LBP) technique. Subsequently, the MCNN model is designed to identify and categorize the various sorts of defects. Experimental results obtained high accuracy (99.0%), F1-score (98.7%), recall (98.6%) and precision (98.5%), which validate the greater of RO-MCNN over existing methods, demonstrating its capability in robustly detecting and classifying bearing defects with high precision and reliability, thereby advancing the efficacy of machine vision in industrial defect assessment. The MCNN model’s performance is improved and the loss function is decreased by using the RO method. The results of the experiments showed that the suggested RO-MCNN technique outperforms current strategies in terms of bearing defect type detection and classification.

A critical evaluation of high-power electronics switching in semiconductor materials is made from the standpoint of performance, reliability, and commercial viability. This study takes into account recent experimental results obtained from the field-reliability study of silicon power MOSFETs in high-density power supplies where residual material defects present in the space charge region of the device were found to generate local micro plasma that eventually caused power MOSFETs to fail. Based on these results and commercial progress made to date in wide bandgap semiconductor technologies, it is suggested that silicon carbide (SiC) promises to be the preferred material for high-power electronics switching from cost, performance and reliability considerations — this assessment is further strengthened by the near-term potential for developing large-area, low-cost, and defect-free SiC bulk substrates and epitaxial layers. This conclusion is also supported by the feasibility and the need for vertical, MOS-controlled, bipolar power switches in compact and efficient megaWatt-level power converters in order to make transformational changes in the 21st century electrical transmission and distribution infrastructure.

The recovery behavior of 20% plastically deformed AlSi_11.35Mg_0.23 in various stages of isochronal annealing is investigated by positron lifetime (LT). Experimental results show that the positron mean lifetime is a function of annealing temperature. The lifetime of the positron annihilating in a perfect lattice is 187.3 ps. It is 229.8 ps in a 20% deformed one. There are two regions in the isochronal annealing, one of them is related to the point defect and the other to the dislocation. The activation enthalpy for the dislocation is calculated from the isothermal study in the dislocation region from 575–675 K by slow and fast cooling and it is 0.16 ± 0.02 and 0.53 ± 0.06 eV, respectively.

The Fe–C–H interaction near defects in iron structures was studied using qualitative structure calculations in the framework of the atom superposition and electron delocalization molecular orbital. Calculations were performed using three Fe clusters to simulate an edge dislocation, a divacancy; both in bcc iron and a stacking fault in an fcc iron structure. In all cases, the most stable location for C atom inside the clusters was determined. Therefore, H atom was approximated to a minimum energy region where the C atom resides. The total energy of the cluster decreases when the C atom is located near the defects zone. In addition, the presence of C in the defects zone makes no favorable H accumulation. The C acts as an expeller of H in a way that reduces the hydrogen Fe–Fe bonds weakening.

The defects induced by a spike rapid thermal annealing (RTA) process in crystalline silicon (c-Si) solar cells were investigated by the photoluminescence (PL) technique and the transmission electron microscopy (TEM), respectively. Dislocation defects were found to form in the near-surface junction region of the monocrystalline Si solar cell after a spike RTA process was performed at 1100${}^{\circ }$C. Photo J–V characteristics were measured on the Si solar cell before and after the spike RTA treatments to reveal the effects of defects on the Si cell performances. In addition, the Silvaco device simulation program was used to study the effects of defects density on the cell performances by fitting the experimental data of RTA-treated cells. The results demonstrate that there was an obvious degradation in the Si solar cell performances when the defect density after the spike RTA treatment was above $1\times 10^{13}$cm${}^{-3}$.

Owing to the advancement in the field of materials, different range of grades have been developed. The machinability examination of these newer grades must be carried out for future applications. One such newer grade of magnesium with AZ31 is deemed for study during the drilling process. The independent parameters considered are spindle speed (SS), feed rate (FR) and drill bit diameter (DBD). The dependent parameters considered are burr height (BH), burr thickness (BT), drilling time (DT) and surface roughness (SR). Improving hole accuracy is essential for manufacturing superior products, which is discussed in this work. At the same time, the machining time has also to be minimized to increase the production rate. With these objectives, the experimental investigation is made. Further, an analytical model for predicting the responses is developed; later, optimization is carried out to obtain the desired responses through the desirability function approach. The multi-objective optimization suggests the SS of 1100rpm, the FR of 0.198mm/rev., and the DBD of 6mm for reducing the entire dependent is reckoned.

To improve the corrosion resistance of X70 pipeline steel in seawater, nickel coating was prepared on the surface of X70 steel by electroplating method. The corrosion properties of the samples in simulated seawater were studied by macroscopic electrochemical experiment and micro-scanning electrochemical experiment. The systematic characterization of the samples was conducted using a scanning electron microscope (SEM), energy disperse spectroscopy (EDS), and X-ray diffractometer (XRD) techniques. The time-dependent model was established to simulate the localized corrosion by COMSOL Multiphysics. The characterization results show that the nickel coating prepared at 0.045 A is compact and thickest. In the macroscopic electrochemical results, the impedance value of the nickel layer prepared at 0.045 A is 34% and 36% higher than that of the other two coatings, and the current density is 25% and 66% lower than that of the other two coatings. In the micro-scanning electrochemical results, the impedance value of the nickel layer prepared at 0.045 A is 5% and 40% higher than that of the other two coatings, and the current density is 14% and 26% lower than that of the other two coatings. Therefore, 0.045 A is the best electroplating current for preparing nickel coating. The simulation results show that the micropores on the surface of nickel-plated X70 are easy to induce localized corrosion, and the degree of localized corrosion decreases with the increase of micropore diameter.

Exploring the Role of Glutathione in the Regulation of Immune Cell Function.

Does Oxidative Damage Cause Poor Healing?

Pathogenesis of Atopic Dermatitis in Singapore.

Proteomics and Colorectal Cancer Metastasis: Bird's-Eye View on Current Scenario and Our Contribution.

Zebrafish: A Small Fish Model for a Big Human Disease.

The Reign of a New Dictator: Circulating MicroRNA in Diabetes.

Engineering Artificial Vascularized Bone Grafts for the Repair of Large Bone Defects.

A 'Nano' Era for Blood Glucose Sensing.

Ancient Medicine with Newer Roles: Potential Role of Celastrol in the Treatment of Multiple Myeloma.

Proteins, Proteome and Proteomics.

A Novel Promising Biomarker and Therapy Target of Liver Cancer.

The European Commission 6th Framework Project COCOMAT was a four-and-a-half-year project (2004 to mid-2008) aimed at exploiting the large reserve of strength in composite structures through more accurate prediction of collapse. In the experimental work packages, significant statistical variations in buckling behaviour and ultimate loading were encountered. During the experiments for the COCOMAT project, it was recognised that there was a gap in knowledge about the effect of initial defects and variations in the input variables of both the experimental and simulated panels. The effect of the defects and variations in the experimental panel resulted in some failure modes that were not predicted with the finite element modelling. This led to the development of stochastic algorithms to relate variations in boundary conditions, material properties and geometries to the variation in buckling modes and compression loads up to the first failure. This paper shows the development of a stochastic methodology to identify the impact of variation in input parameters on the response of stiffened composite panels and the development of a robust index to support the evaluation of panel designs. The stochastic analysis included the generation of metamodels that allow quantification of the impact that the inputs have on the response using two first order variables, influence and sensitivity. These variables were then used to derive the robust indices to quantify the response of two COCOMAT panels that were experimentally tested, including the response of the panels to simulated damage. The robust indices that are shown in this paper are functions of the robustness parameter which has been recommended in the final Design Guidelines for the COCOMAT project to measure the effects of scatter found in postbuckling loads.

A torsional buckling model of cylindrical shells with asymmetric local thickness defect is established based on the Hamiltonian system. The critical load and torsional buckling mode of cylindrical shells with defects are obtained by the symplectic eigensolution expansion method, which overcomes the difficulty of constructing the deflection function of the traditional semi-inverse method. Local buckling modes can be captured by this new analytical model with the superposition of symplectic eigensolutions. To ensure accuracy and validity of the symplectic method, the analytical solution with torsional buckling of a cylindrical shell is compared with the classical solution and the finite element method (FEM) solution. The results show that the most detrimental position of the defect is only related to the width of the defect, not to the depth. The local defect changes the circumferential buckling wave number of the cylindrical shell and concentrates the torsional corrugation on the side containing the defect. Torque symmetry is broken due to the asymmetric defect, and the most detrimental defect direction for buckling is the same as the direction of torsional buckling wavelet.

We summarize recent results on the impact of defects on the electronic properties of single-wall carbon nanotubes. We probe the influence of defects on electron transport in CNFETs by combined scanning gate microscopy (SGM) and scanning impedance microscopy (SIM). Depletion surface potential of individual defects is quantified from the SGM-imaged defect radius as a function of tip bias voltage. This provides a measure of the Fermi level at the defect with zero tip voltage. In the "off" state, transport is first dominated by barriers at depleted defects. It becomes diffusive as the CNFET is turned on, and finally is quasi-ballistic in the regime of "degenerate electrostatic doping". Metallic nanotubes with good contacts show a metal-to-insulator crossover as the gate voltage is varied. In the metallic state we see quantitative agreement with the "twiston" scattering picture.

The capability of graphitic networks to reorganize their structures under irradiation of energetic particles provides the tool for nano-engineering of carbon nanotubes (CNTs). We have studied the effect of 30 keV N⁺ ion irradiation with three different fluences 10¹², 10¹³, and 10¹⁴ ions/cm² on the structural and spectroscopic properties of single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs). Irradiation-induced structural defects and coalescence of the nanotubes are studied using high-resolution transmission electron microscopy (HRTEM). Upon irradiation, some of the radial breathing modes in Raman spectra disappear due to conversion from single-walled to multiwalled structure. We observed a systematic change in intensity of the intermediate frequency mode (IFM) with increasing dose of ion-irradiation and these IFM modes are attributed to structural defects of SWNTs. Dramatic improvement in the intensity ratio G-band to D-band (at ~1335 cm^-1) for ion fluence of 10¹³ ions/cm² indicates improved graphitic structure as a result of reconstruction. Similarly, X-ray Photoelectron spectroscopy studies show improvement in the amount of sp² carbon upon 10¹³ ions/cm²N⁺ ion irradiation dose. At a higher dose (10¹⁴N⁺ions/cm²), vacancy and bent structures having Stone–Wales defects were observed in HRTEM, whereas MWNTs show formation of surface hillock like protrusions leading to formation of fullerene-like structures.

The broad visible photoluminescence (PL) observed in ZnO nanocrystals (NCs) is widely attributed to multiple low lying surface-defects. We have performed steady state and time-resolved PL measurements on size-selected ZnO NCs in the strong confinement regimes. Our results show that radiative relaxation rates and coupling between excitons and surface defect states vary dramatically for sizes between 2 nm and 3 nm. Energy dependent PL lifetimes reveal that relaxation dynamics of these defect states in the blue- and red-edge of the emission are very different from each other.

In this paper we report on the preparation of nanobrushes of ZnO on quartz substrate by a direct atmosphere evaporation method using Zn metal flakes. Activated charcoal was used as a catalyst that facilitated the formation of nanobrushes in which the brush stem was about 15–20 μm in length and the bristles (100–200 nm thick) were made up of nanofibrous ZnO whose tips were 10–15 nm in width and were angled in some cases. These aligned nanobrushes can find potential applications as nanopower generators and high aspect ratio AFM probes by virtue of the piezoelectric property of ZnO. This technique is simple for realizing aligned ZnO nanobrushes with metallic Zn as the source material.

This research demonstrates the capability of controlled, focused ion beam (FIB)–assisted tailoring of morphologies in both multiwall carbon nanotubes (CNTs) and Y junction nonlinear CNT systems through defect engineering. We have shown that a 30 keV FIB Ga⁺ ion beam at low ion milling currents of 1 pA can be used to partially reduce the CNT diameter, to provide electrical conduction bottleneck morphologies for linear CNTs, and to introduce both additive and subractive defects at Y junction locations of Y-CNT samples. Our aim is for this work to provide motivation for additional research to determine the effects of ion-beam-induced changes in modulating the physical and chemical properties of nanotubes.

Nanocrystalline ZnO particles substituted with different concentrations (0–30%) of Mn were synthesized by using a modified ceramic route and characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and energy dispersive X-ray analysis methods. Positron lifetime and coincidence Doppler broadening measurements were used as probes to identify the vacancy-type defects present in them and monitor the changes while doping. The predominant positron trapping center in the undoped ZnO is identified as the trivacancy-type cluster V_Zn+O+Zn, which is negatively charged, and it transformed to the neutral divacancy V_Zn+O on doping with Mn²⁺ ions. The intensity of the defect-specific positron lifetime component got reduced initially indicating partial occupancy of the vacancies by the doped cations but then recovered on further doping due to the additional Zn vacancies created as a result of the increasing strain introduced by the Mn ions of larger radius. The creation of a new phase ZnMn₂O₄ thereafter changed the course of variation of the annihilation parameters, as the positrons got increasingly trapped in the vacancies at the tetrahedral and octahedral sites of the spinel nanomanganite.

We report room temperature ferromagnetism (RTFM) in nanocrystalline Zn_1-xCu_xO(0.03 ≤ x ≤ 0.07) materials synthesized by autocombustion technique. The average particle sizes are in the range of 60 nm. The saturation magnetization and coercivity of 7% Cu-doped ZnO is enhanced significantly in comparison to 3% and 5% Cu-doped ZnO. There is not much variation in the optical band gap due to Cu doping, thus suggesting the uniform distribution of Cu in the ZnO matrix. Micro-Raman and photoluminescence analysis predict the presence of clusters of oxygen vacancies in Cu-doped system which improves with the increase in Cu concentration. This study provides further evidence that oxygen vacancies play an important role in the enhancement of room temperature ferromagnetic property in Cu-doped ZnO.

Spherical Bi₂S₃ nanoparticles (NPs) were prepared by a facile in situ thermal sulfuration method. Different Bi₂S₃ samples were obtained by controlling the sulfuration time. The products were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), Raman and Fourier-transform infrared (FT-IR) methods. The optical properties were examined by UV-visible-near-infrared (UV-Vis–NIR) and photoluminescence (PL) techniques. The results show that the phase of the products after sulfuration is pure and the spherical shape of Bi NPs has been successfully transmitted to Bi₂S₃ samples. The light absorption edges exhibit red shift to 1060 nm while the light emission displays blue shift to 868 nm, compared with the energy bandgap of bulk Bi₂S₃. The reason for the special optical properties of Bi₂S₃ NPs by this in situ sulfuration route is considered to associate with the defects and quantum size effect of NPs.

Molecular dynamics (MD) is a technique of atomistic simulation which has facilitated scientific discovery of interactions among particles since its advent in the late 1950s. Its merit lies in incorporating statistical mechanics to allow for examination of varying atomic configurations at finite temperatures. Its contributions to materials science from modeling pure metal properties to designing nanowires is also remarkable. This review paper focuses on the progress of MD in understanding the behavior of iron — in pure metal form, in alloys, and in composite nanomaterials. It also discusses the interatomic potentials and the integration algorithms used for simulating iron in the literature. Furthermore, it reveals the current progress of MD in simulating iron by exhibiting some results in the literature. Finally, the review paper briefly mentions the development of the hardware and software tools for such large-scale computations.

A novel lead zinc titanate tungsten oxide (PbZn${}_{1∕3}$Ti${}_{1∕3}$W${}_{1∕3}$O${}_3)$ single perovskite was synthesized employing a cost-effective solid-state reaction technique. A phase transition occurs from tetragonal (P4mm) to monoclinic (C2/m) after substituting zinc (Zn) and tungsten (W) into the B-site of the pure lead titanate. The average crystallite size and micro-lattice strain are 66.2nm and 0.159%, respectively, calculated by the Williamson–Hall method. The grains are uniformly distributed through well-defined grain boundaries and the average grain size is about 17.8$\mu$m analyzed from the SEM micrograph. Raman spectrum suggests the presence of all constituent elements in the sample. The UV–Visible study suggests that the sample is suitable for photovoltaic applications because of high bandgap energy $E_g=4.17$eV. The dielectric study confirms the negative temperature coefficient resistance (NTCR) behavior of the sample. The activation energy increases from 13.9meV to 142meV with a rise of temperature suggesting that ac conductivity is thermally activated. The thermally activated relaxation process was managed by immobile charge carriers at low temperatures while defects and oxygen vacancies at higher temperatures. The presence of the asymmetrical curves in modulus plots confirms the non-Debye-type behavior. Both Nyquist and Cole–Cole semi-circular arcs confirm the semiconductor nature of the sample.