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Structural Refinement of Titanium-Aluminum-Niobium Alloy for Biomedical Applications
Get PDFIn this work, a modification of the microstructure of a commercial Ti-6Al-7Nb alloy was accomplished by high-pressure torsion (HPT) at room temperature, to produce a bulk nanostructure on discs of 10 mm diameter and ~0.8 mm thickness. The metallographic analyses of the discs were performed by optical microscopy and scanning electron microscopy with energy dispersive spectroscopy. The results confirmed the presence of aluminum (Al) and niobium (Nb) as the sole alloying elements, promoting a duplex (α + β) titanium (Ti) microstructure prior to HPT processing. After HPT processing, nanostructure refinement was attained, reflected in the X-ray diffraction profiles as broadening of the α-Ti and β-Ti peaks and the appearance of the ω-Ti phase. Transmission electron microscopy confirmed a grain size < 100 nm after HPT processing for N = 5 revolutions. Microhardness increased significantly with straining by HPT, which can be attributed both to the grain refinement and the formation of the ω-Ti phase
Effect of Sepiolite Content on Hydrophilicity and Thermal Stability of Poly(butyl lactate methacrylate)
Get PDFIn the present work, the hydrophilicity and thermal behavior of nanocomposites of poly(butyl lactate methacrylate) were investigated using different weight percent of sepiolite. These nanocomposites were prepared by solution casting method. X-ray diffraction (XRD) studies indicated that the increase in sepiolite content decreased the average molecular interchain spacing () values from 7.18 to 6.23 Å in nanocomposites. Apart from the amorphous halo peak of nanocomposites, the appearance of crystalline peak at 7.41° was due to the d110 plane of sepiolite. Surface morphology of nanocomposites was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques and the uniform dispersion of nanofiller was observed up to 1% (w/w). Depending upon the sepiolite content, relative humidity and time, the hydrophilicity of nanocomposites can be tuned to a wide range from 5.7 to 23.6% (w/w) and it follows Fickian absorption. Glass transition temperature of nanocomposites increased from 72.1 to 80.3 °C with an increase in sepiolite content. The thermal stability of nanocomposites increased with an increase in sepiolite content, which were thermally stable up to 200 °C and thereafter exhibited two-step thermal degradation in nitrogen atmosphere
Method of Receive a Nanoparticles of Noble Metals with Average Size Less Than 3 nm for LSPR Research
Get PDFThe paper presents a simple although effective method of obtaining gold and silver nanoparticles of average size of less than 3 nm. The nanoparticles were obtained by the Bredig’s electric arc method. Then colloidal preparations were centrifuged with acceleration equals to 29000 xg. It has been showed that subjecting the colloid to the hour centrifugation process repeated four times allows to obtain nanoparticles whose size does not exceed 5 nm. The nanoparticles prepared using this method were characterized by a high purity that depended only on the water and the cleanliness of the noble metal wire which have been used. Furthermore, it was observed that the absence of conglomerates and joins of the particles is typical for transmission electron microscopy methods
Condition Monitoring of Roller Bearing by K-Star Classifier and <i>K</i>-Nearest Neighborhood Classifier Using Sound Signal.
No full textMost of the machineries in small or large scale industry have rotating element supported by bearings for rigid support and accurate movement. For proper functioning of machinery, condition monitoring of the bearing is very important. In present study sound signal is used to continuously monitor bearing health as sound signals of rotating machineries carry dynamic information of components. There are numerous studies in literature that are reporting superiority of vibration signal of bearing fault diagnosis. However, there are very few studies done using sound signal. The cost associated with condition monitoring using sound signal (Microphone) is less than the cost of transducer
used to acquire vibration signal (Accelerometer). This paper employs sound signal for condition monitoring of roller bearing by K-star classifier and k-nearest neighborhood classifier. The statistical feature extraction is performed from acquired sound signals. Then two layer feature selection is done using J48 decision tree algorithm and random tree algorithm. These selected features were classified using K-star classifier and k-nearest neighborhood classifier and parametric optimization is performed to achieve the maximum classification accuracy. The classification results for both K-star classifier and k-nearest neighborhood classifier for condition monitoring of roller bearing using sound signals were compared
Research on SFLA-Based Bidirectional Coordinated Control Strategy for EV Battery Swapping Station
Get PDFAs a good measure to tackle the challenges from energy shortages and environmental pollution, Electric Vehicles (EVs) have entered a period of rapid growth. Battery swapping station is a very important way of energy supply to EVs, and it is urgently needed to explore a coordinated control strategy to effectively smooth the load fluctuation in order to adopt the large-scale EVs. Considering bidirectional power flow between the station and power grid, this paper proposed a SFLA-based control strategy to smooth the load profile. Finally, compared simulations were performed according to the related data. Compared to particle swarm optimization (PSO) method, the presented SFLA-based strategy can effectively lower the peak-valley difference with the faster convergence rate and higher convergence precision. It is important for the swapping station that energy exchanging mode can supply energy for large-scale EVs with a smoother load profile than one-way charging mode
Fingerprint Liveness Detection from Different Fingerprint Materials Using Convolutional Neural Network and Principal Component Analysis
Get PDFFingerprint-spoofing attack often occurs when imposters gain access illegally by using artificial fingerprints, which are made of common fingerprint materials, such as silicon, latex, etc. Thus, to protect our privacy, many fingerprint liveness detection methods are put forward to discriminate fake or true fingerprint. Current work on liveness detection for fingerprint images is focused on the construction of complex handcrafted features, but these methods normally destroy or lose spatial information between pixels. Different from existing methods, convolutional neural network (CNN) can generate high-level semantic representations by learning and concatenating low-level edge and shape features from a large amount of labeled data. Thus, CNN is explored to solve the above problem and discriminate true fingerprints from fake ones in this paper. To reduce the redundant information and extract the most distinct features, ROI and PCA operations are performed for learned features of convolutional layer or pooling layer. After that, the extracted features are fed into SVM classifier. Experimental results based on the LivDet 2013 and the LivDet 2011 datasets, which are captured by using different fingerprint materials, indicate that the classification performance of our proposed method is both efficient and convenient compared with the other previous methods
Optimum En-Masse Retraction of Six Maxillary Anterior Teeth in Lingual Orthodontics: a Numerical Investigation with 3-Dimensional Finite Element Analysis
Get PDFThe objective of this study was to devise an optimum force system to achieve en-masse retraction of six maxillary anterior teeth in lingual orthodontics (LiO). First, the set of equations was developed based on the mathematical computation to estimate optimum parameters of force system. Then, the computer software based on this mathematical computation was developed for the ease of estimation of force system. The verification of force system obtained with computer software was accomplished by three-dimensional finite element analysis (FEA). In FEA, it was clear that the desired en-masse retraction of six maxillary anterior teeth in LiO was achieved as observed from the vectors of nodal displacements as well as positions of undeformed and deformed models. In this way, mathematically computed optimum force system was verified with FEA. For orthodontists, the developed computer software accurately estimates the required force system according to mathematical computation. It simplifies the task of computation for orthodontists. The orthodontists can easily operate this computer software as it is user-friendly. Further, in-vivo validation of this study is required in future before clinical application
Simvastatin Inhibits the Proliferation and Apoptosis of Macrophages Induced by Mechanical and/or Oxidized Low-Density Lipoprotein
No full textThis study was designed to investigate the effects of mechanical (MS) and/or oxidized low-density lipoprotein on proliferation and apoptosis of RAW264.7 macrophages and the underlying mechanisms. The cultured quiescent RAW264.7 macrophages were subject to stimulation with MS and/or in the presence or absence of simvastatin and then harvested for Western blot, and immunoflourecence. Either MS or alone could cause increase in cell proliferation and apoptosis, while their combination led to an additive effect. In terms of mechanisms, MS and/or significantly increased phosphorylation levels of MAPKs (ERKs, JNKs and p38MAPK), promoted the reactive oxygen species (ROS) and up-regulated DNA methylation in RAW264.7 macrophages. The increased DNA methylation was associated with proliferation but not apoptosis. In contrast, simvastatin could remarkably inhibit all the effects mentioned above. MS and can simultaneously promote both proliferation and apoptosis of macrophages through activating MAPKs, ROS, and DNA methylation signaling, which can be directly inhibited by the simvastatin treatment. The study results can provide novel information for the pathogenesis and prevention of hypertensive mechanical related vascular diseases
Renewable Additives that Improve Water Resistance of Cellulose Composite Materials
Get PDFWaste cardboard is an underutilized resource that can be redirected for the creation of safer and higher quality building materials for low-income housing in the developing world, as well as to produce better materials for indoor environments in developed-world contexts. Using a renewable biobased binder and benign additives, we have improved the water resistance of a cardboard-based composite material, overcoming one of the major barriers to scaling and adoption of this class of materials. Resistance to water uptake was significantly increased with several additives and was increased over 900-fold in the best case. Strength and water uptake over time are reported for a range of fatty acid-based additives and multiple cardboard feedstocks
Effects of Cold Plasma on Surface, Thermal and Antimicrobial Release Properties of Chitosan Film
Get PDFThis work aims to analyze the effects of cold atmospheric air plasma treatment of antimicrobial chitosan film with different levels of thymol. Optical characterization of the dielectric barrier discharge showed the generation of reactive nitrogen and oxygen species by the system. A significant increase (p 0.05) was observed in the thermal profile of the plasma-treated films. A significant increase (p < 0.05) in the thymol diffusion coefficient was observed after the plasma treatment for all the active films