Review on calcium silicate-based bioceramics in bone tissue engineering

Calcium (Ca) and silica (Si) ions have attracted intense interest in biomedical applications. The two ions are directly involved in many biological processes; for instance, Ca plays a key role in regulating cellular responses to bioceramics, promoting cell growth, and differentiation into osteoblasts. Si plays a significant role in bone calcification and is helpful for bone density improvement and inhibiting osteoporosis. Calcium silicate ceramics including a large group of trace metal containing calcium silicate-based compounds are involved in biomedical applications such as repairing hard tissue texture, bone scaffolds, bone cements, or implant coatings. The aim of the study is to provide a comprehensive overview of developments in research on calcium silicate-based ceramics, such as wollastonite (CaSiO₃), diopside (CaMgSi₂O₆), akermanite (Ca₂MgSi₂O₇), bredigite (Ca₇Mg(SiO₄)₄), merwinite (Ca₃MgSi₂O₈), monticellite (CaMgSiO₄), hardystonite (Ca₂Zn(Si₂O₇), and baghdadite (Ca₃ZrSi₂O₉), including degradation, apatite mineralization, and mechanical properties. Finally, the biological in vitro and in vivo presentation for bone tissue repair are summarized, which show promise with regard to application of calcium silicate-based ceramics as bone repair and replacement materials.     

Simulation of anomalous transport in tokamaks using the FACETS code

The development of a new parallel framework for integrated modeling of tokamak plasmas is a primary objective of the SciDAC Framework Architecture for Core-Edge Transport Simulations (FACETS) project. The FACETS code will be used to predict the performance of tokamak discharges and to optimize tokamak discharge scenarios. Novel parallel numerical algorithms and solvers have been developed in the FACETS project in order to simulate the multi-scale dynamics of tokamak plasmas. The status of development of modules for anomalous transport in the FACETS code is described in this paper. Mechanisms that are used for coupling 1D anomalous transport in the plasma core together with 2D transport in the plasma edge (in near separatrix and scrape-off-layer regions) are considered. Results of the first verification studies based on predictive modeling of several analytical and experimental equilibria are presented.     

Phase Formation and Melt Processing of Yb-123

The formation of Yb-123 has been studied at different temperatures in air and in reduced oxygen partial pressure. It is found that the stability and/or the formation kinetics of Yb-123 phase is a major hurdle in manufacturing phase-pure Yb-123 in air. However, under reduced oxygen partial pressure, Yb-123 forms rapidly and more than 90% phase-pure Yb-123 is achieved within three sintering steps. Rods made from this powder were melt-processed in air and showed a T _c of 90 K. Kinetic studies performed by interrupting the growth during the directional solidification of these rods revealed a growth mechanism similar to that of Y-123 and a maximum growth rate of 7.2 mm/h for a stable planar interface. EPMA of the interface showed the liquid to be rich in barium cuprates with a Ba:Cu ratio of 1:3.     

Recognition in the near infrared spectrum for face,gender and facial expressions

Visible face recognition systems are subjected to failure when recognizing the faces in unconstrained scenarios. So, recognizing faces under variable and low illumination conditions are more important since most of the security breaches happen during night time. Near Infrared (NIR) spectrum enables to acquire high quality images, even without any external source of light and hence it is a good method for solving the problem of illumination. Further, the soft biometric trait, gender classification and non verbal communication, facial expression recognition has also been addressed in the NIR spectrum. In this paper, a method has been proposed to recognize the face along with gender classification and facial expression recognition in NIR spectrum. The proposed method is based on transfer learning and it consists of three core components, i) training with small scale NIR images ii) matching NIR-NIR images (homogeneous) and iii) classification. Training on NIR images produce features using transfer learning which has been pre-trained on large scale VIS face images. Next, matching is performed between NIR-NIR spectrum of both training and testing faces. Then it is classified using three, separate SVM classifiers, one for face recognition, the second one for gender classification and the third one for facial expression recognition. It has been observed that the method gives state-of-the-art accuracy on the publicly available, challenging, benchmark datasets CASIA NIR-VIS 2.0, Oulu-CASIA NIR-VIS, PolyU, CBSR, IIT Kh and HITSZ for face recognition. Further, for gender classification the Oulu-CASIA NIR-VIS, PolyU,and IIT Kh has been analyzed and for facial expression the Oulu-CASIA NIR-VIS dataset has been analyzed.

     

Corrosion and Nano-mechanical Behaviors of Magnetron Sputtered Al-Mo Gradient Coated Steel

A gradient three-layer Al-Mo coating was deposited on steel using magnetron sputtering method. The corrosion and nano-mechanical properties of the coating were examined by electrochemical impedance spectroscopy and nano-indentation tests and compared with the conventional electroplated cadmium and IVD aluminum coatings. Electrochemical impedance spectroscopy was performed by immersing the coated specimens in 3.5% NaCl solution, and the impedance behavior was recorded as a function of immersion time. The mechanical properties (hardness and elastic modulus) were obtained from each indentation as a function of the penetration depth across the coating cross section. The adhesion resistance of the coatings was evaluated by scratch tests on the coated surface using nano-indentation method. The results show that the gradient Al-Mo coating exhibits better corrosion resistance than the other coatings in view of the better microstructure. The impedance results were modeled using appropriate electrical equivalent circuits for all the coated systems. The uniform, smooth and dense Al-Mo coating obtained by magnetron sputtering exhibits good adhesion with the steel substrate as per scratch test method. The poor corrosion resistance of the later coatings was shown to be due to the defects/cracks as well as the lesser adhesion of the coatings with steel. The hardness and elastic modulus of the Al-Mo coating are found to be high when compared to the other coatings.     

Collaborative case-based estimating and design

Information Technology (IT) solutions to problems in construction design need to consider the perspectives of all the participants in the process; only then can IT provide a platform for integration. The research described examines issues involved in the integration of construction disciplines by using Case-Based Reasoning (CBR). It describes a hierarchical case memory structure and a context-based indexing method for retrieval and reuse of previous designs and their costs. Estimating and design cases selected for reuse are adapted with the use of sub-cases and domain specific adaptation rules. A prototype system, NIRMANI, was successfully implemented to support collaborative design.     

Effect of acceleration stresses on the yielding of rotating disks

The influence of shearing stresses arising due to angular acceleration in a rotating disk on yielding has been examined using von Mises yield criterion. Yield loci are plotted for both uniform and non-uniform thickness disks. The values of angular velocity and angular acceleration are reported and compared with the values given by Reid,⁴ which is based on Tresca's yield criterion.     

Target Tracking Over Fading Channels

The problem of tracking a target in a multitarget environment when the observations are received over a fading channel is considered. The optimal Bayes solution to the tracking problem in such cases involves growing memory and hence is not feasible. A particularly effective suboptimal scheme uses a probabilistic judgment at each stage of the observations to overcome this problem. This concise paper presents an evaluation of the scheme in terms of mean-square error performance when the observations are received over fading channels.     

A Visually Weighted Quantization Scheme for Image Bandwidth Compression at Low Data Rates

Source encoding of images for bandwidth compression has become attractive in recent years because of decreasing hardware costs. By combining the source encoding approach with transform coding techniques, it is possible to obtain good image quality at low data rates. The general aspects of such a system are presented. The design of the quantizer for transform coefficients, which is the major source of error associated with the compression process, is considered using a visual fidelity criterion and subject to the constraint that the entropy of the quantizer be a prespecified quantity. A visually weighted suboptimal quantization scheme is developed to take into account the relative importance of different transform coefficients to the human visual system.     

Widespread natural perchlorate in unsaturated zones of the southwest United States

A substantial reservoir (up to 1 kg ha(-1)) of natural perchlorate is present in diverse unsaturated zones of the arid and semi-arid southwestern United States. The perchlorate co-occurs with meteoric chloride that has accumulated in these soils throughout the Holocene [0 to 10-15 ka (thousand years ago)] and possibly longer periods. Previously, natural perchlorate widely believed to be limited to the Atacama Desert, now appears widespread in steppe-to-desert ecoregions. The perchlorate reservoir becomes sufficiently large to affect groundwater when recharge from irrigation or climate change flushes accumulated salts from the unsaturated zone. This new source may help explain increasing reports of perchlorate in dry region agricultural products and should be considered when evaluating overall source contributions.