A comparative study on in vitro behavior of calcium silicate ceramics synthesized from biowaste resources

Calcium silicate ceramics have received significant attention for biomedical applications for their excellent bioactivity and osteoconduction properties. Sol-gel process is extensively used for the fabrication of calcium silicates. In sol-gel process, calcium nitrate tetra hydrate (Ca(NO₃)₂·4H₂O) and tetraethylorthosilicate (TEOS) are used as precursors. However, these precursors are expensive. The objective of this work was to compare in vitro behavior of calcium silicate (CaSiO₃) produced using biowaste such as rice husk ash (RHA) and eggshells (coded; NCS) with CaSiO₃ prepared using TEOS and Ca(NO₃)₂·4H₂O (coded; CCS). Thermal investigation results revealed that the crystallization temperature for NCS is relatively lower (772°C) than for CCS (870°C). Bioactivity was studied in vitro using simulated body fluid (SBF) with respect to mineralization rate of hydroxyapatite. Mineralization of a greater hydroxyapatite was observed on NCS ceramics than CCS ceramics after incubation for 3, 7, 14 days in SBF solution, which was confirmed using X-ray diffractometer, Fourier transform infrared spectroscopy, scanning electron microscopy-energy dispersive spectroscopy. Degradation studies were conducted in Tris-HCl solution and the test results revealed that NCS ceramics has lower dissolution rate than CCS ceramics. The antimicrobial assay has shown that NCS samples exhibit significant zone of inhibition against Escherichia coli and Staphylococcus aureus which confirmed that the CaSiO₃ prepared from RHA and eggshell can prevent bacteria from adhering to the surface. In addition cell culture studies revealed that NCS ceramics possess good cytocompatibility with MG-63 cells and significantly promoted cell proliferation.     

Effect of organoclay addition on the two-body abrasive wear characteristics of polyamide 6 nanocomposites

Polymer clay nanocomposites (PCN) exhibit improved mechanical properties due to nanolevel dispersion of clay in the polymer matrix. They also exhibit good tribological performance under dry sliding conditions. Abrasive wear behaviour of these materials would be different from dry sliding behaviour as the mechanisms of the both are entirely different. Hence the abrasive wear behaviour of these materials needs to be investigated. The abrasive wear characteristics of polyamide 6 nanocomposites, with 1, 3 and 5% (wt.) clay prepared by melt intercalation technique, under two-body abrasive wear conditions have been reported. Abrasive wear tests were conducted using a pin-on-disc tribometer containing an abrasive counterface. All the polyamide nanocomposites investigated exhibited a low abrasive wear resistance compared with pristine Nylon. The wear performance of the nanocomposites was correlated with the mechanical properties. Dominant ploughing and cutting wear were observed in polymer clay nanocomposites. The amount of clay present alters the wear mechanism.     

A fuzzy logic system for channel equalization

We present a new method for channel equalization using fuzzy logic. The membership functions are derived from the training data set, and a method to estimate the delay of the communication channel is proposed. The performance of the fuzzy equalizer is compared with that of a transversal filter equalizer. It is shown using simulations that the transversal filter requires a much larger training set to achieve the same error rate. It is also shown, using simulations, that the fuzzy equalizer performs better in the presence of channel nonlinearities     

Using solidification parameters to predict porosity distributions in alloy castings

Quality criteria used in the computer-aided design and analysis of casting processes typically relate geometric, thermal, or solidification parameters to structural features such as centerline shrinkage and microporosity. Quality criteria for the prediction of porosity in castings have been used successfully in steel, but the application of criteria functions to nonferrous alloys has been less successful. Recent work suggests that the dominating mechanism that determines the amount and distribution of porosity in castings is strongly dependent on the solidification mode of the alloy and the solidification conditions. Accordingly, casting processes and alloy types are divided into four groups, and a different set of criteria functions are obtained for each group.     

Concept-based evidential reasoning for multimodal fusion in human–computer interaction

Considerable research has been done on using information from multiple modalities, like hands, facial gestures or speech, for better interaction between humans and computers, and many promising human–computer interfaces (HCI) have been developed in recent years. However, most of the current HCI systems have a few drawbacks: firstly, they are highly dependent on the performance of individual sensors. S econdly, the information fusion process from these sensors tends to ignore the semantic nature of the modalities, which may reinforce or clarify each other over time. Finally, they are not robust enough at representing the imprecise nature of human gestures, since individual gestures are highly ambiguous in themselves. In this paper, we propose an approach for the semantic fusion of different input modalities, based on transferable belief models. We show that this approach allows for a better representation of the ambiguity involved in recognizing gestures. Ambiguity is resolved by combining the beliefs of the individual sensors on the input information, to form new extended concepts, based on a pre-defined domain specific knowledge base, represented by conceptual graphs. We apply this technique to a multimodal system consisting of a hand gesture recognition sensor and a brain computing interface. It is shown that the technique can successfully combine individual gestures obtained from the two sensors, to form meaningful concepts and resolve ambiguity. The advantage of this approach is that it is robust even if one of the sensors is inefficient or has no input. Another important feature is its scalability, wherein more input modalities, like speech or facial gestures, can be easily integrated into the system at minimal cost, to form a comprehensive HCI interface.     

Effect of substrate flexibility on dynamic wetting: a finite element model

Dynamic wetting plays an important role in coating processes. In this paper, we present a new finite element formulation that can predict the effect of substrate deformation on the location of the dynamic contact line. Our model solves for the fluid-structural interactions between an elastic solid and a viscous liquid with a dynamic contact line that can move across the deformable solid surface. Surface tension forces acting at the dynamic contact line pull outwards on the substrate and cause the formation of capillary ridge. To predict the shape of the capillary ridge and motion of dynamic contact line, our model uses arbitrary Lagrangian Eulerian (ALE) mesh motion in both fluid and solid phases, because ALE decouples the motion of solid and mesh points. In dynamic wetting of rigid solids it is known that a singularity arises at the dynamic wetting line due to a double-valued velocity. The singularity is often relieved by allowing a slip in a small contact region near the dynamic contact line. Dynamic wetting on flexible substrates involves a second singularity, which arises in the solid domain due to a line force acting at the contact line. The line force singularity is relieved by distributing the force over a finite contact region. Two ALE methods of mesh motion are implemented and compared. The variation of dynamic contact line position with respect to various parameters such as downstream pressure, contact angle, capillary number and elasticity number are presented for the finite element model and compared with an analytical model.     

Invariant character recognition with Zernike and orthogonal Fourier-Mellin moments

In this paper, we consider the use of orthogonal moments for invariant classification of alphanumeric characters of different size. In addition to the Zernike and pseudo-Zernike moments (ZMs and PZMs) which have been previously proposed for invariant character recognition, a new method of combining Orthogonal Fourier-Mellin moments (OFMMs) with centroid bounding circle scaling is introduced, which is shown to be useful in characterizing images with large variability. Through extensive experimentation using ZMs and OFMMs as features, different scaling methodologies and classifiers, it is shown that OFMMs give the best overall performance in terms of both image reconstruction and classification accuracy.     

Preparation and pharmacodynamic evaluation of liposomes of indomethacin

The side effects of indomethacin, such as ulceration of the kidney and central nervous system (CNS) toxicity, limit its use as a drug for rheumatoid arthritis. Encapsulation of this drug in liposomes may reduce the toxic effects. The aim of this study was to determine the factors influencing encapsulation of indomethacin in liposomes and to determine anti-inflammatory potential of liposomal indomethacin. A series of liposomal formulations of indomethacin were prepared using various phospholipids. The effects of method of preparation, lipid composition, charge, and cholesterol (CH) on encapsulation of indomethacin in liposomes were investigated. A significant variation in encapsulation of the drug in liposomes was observed when prepared by different methods. With all the methods of preparation tried, the favorable lipid composition for high encapsulation of this drug was egg phosphatidyl choline:CH: stearlyamine (PC:CH:SA) at a 1:0.5:0.1 molar ratio. Inclusion of cholesterol did not affect the encapsulation efficiency of the drug in liposomes. The drug release profile from the liposomes was biphasic, and the highest percentage drug release was observed with large unilamellar vesicles (LUVs) (100 nm). Inclusion of stearylamine (PC:CH:SA 1:0.5:0.1) and phosphatidyl glycerol (PG) (PC:CH:PG 1:0.5:0.2) in the liposomes reduced the release of the drug in comparison to the neutral liposomes (PC:CH 1:1). The slow release of the drug from stearylamine-containing liposomes may be explained by the electrostatic interaction between the acid moiety of the drug and the amine moiety of the lipid. It is assumed that the possible hydrogen bonding between--OH groups of phosphatidyl glycerol and the--COOH group of the drug might be the reason for the slow release of the drug from PC:CH:PG (1:0.5:0.2) containing liposomes. Pharmacodynamic evaluation of the liposomes was performed by carrageenan-induced rat paw edema (acute) and adjuvant arthritis (chronic) models. The anti-inflammatory activity was increased from the first to fifth hour PC:CH:PG (1:0.5:0.2) and PC:CH:SA (1:0.5:0.1) liposomes showed the highest percentage inhibition of edema. In both these models, anti-inflammatory activity of liposomal indomethacin was significantly higher than that of free indomethacin (p < .01). The ulcer index of the free drug was about three times more than the encapsulated drug when administered at the same dose intraperitoneally to arthritic rats consecutively for 21 days.     

Validating for Liveness in Hidden Adversary Systems

Multi-stream interactive systems can be seen as “hidden adversary” systems (HAS), where the observable behaviour on any interaction channel is affected by interactions happening on other channels. One way of modelling HAS is in the form of a multi-process I/O automata, where each interacting process appears as a token in a shared state space. Constraints in the state space specify how the dynamics of one process affects other processes. We define the “liveness criterion” of each process as the end objective to be achieved by the process. The problem now for each process is to achieve this objective in the face of unforeseen interferences from other processes. In an earlier paper, it was proposed that this uncertainty can be mitigated by collaboration among the disparate processes. Two types of collaboration philosophies were also suggested: altruistic collaboration and pragmatic collaboration. This paper addresses the HAS validation problem where processes collaborate altruistically.