An investigation on dry sliding wear behavior of aluminum based metal matrix composites using grey relational analysis coupled with principle component analysis

 The current study reports on wear properties of aluminum 6061-T6 reinforced with titanium carbide and graphite hybrid metal matrix composite using principal component analysis based grey relational analysis. Experiments were carried out using Taguchi's L9 orthogonal array. The dry sliding wear properties of composite samples are evaluated using a Pin-on-Disc apparatus. The effects of wear parameter input variables such as load, sliding speed, and sliding distance on different output responses, namely wear rate, friction force, and coefficient of friction, were investigated in this work. Using grey relational analysis in conjunction with principal component analysis, three output responses from each experiment were normalized into a weighted grey relational grade. According to the analysis of variance, the most influential parameter is sliding velocity (45.51%), followed by load (26.75%) and sliding distance (2.94%), all of which contribute to the quality characteristics. Additional experiments have confirmed optimal results. Finally, a scanning electron microscopic analysis was performed to investigate the wear mechanism

Molecular and morphological characters: An appurtenance for antagonism in Trichoderma spp.

Biocontrol agent Trichoderma has attained importance for substitute of chemical pesticides and hence an attempt was intended to corroborate the positive relatedness of molecular and morphological characters with antagonistic ability. Twelve isolates belonging to Trichoderma harzianum and Trichoderma viride were assessed for their mycoparasitic effect on phytopathogens Pythium aphanidermatum and Sclerotinia sclerotiorum. Though T. harzianum isolates were more aggressive than T. viride isolates, the percent inhibitory effect among T. harzianum isolates did not vary much (80 to 86%). The inhibitory effect of T.viride isolates ranged from 50 to 80%; however, TvChen, Tv4, and TvNir were distinguishable from other T. viride isolates in exhibiting higher degree of antagonism. The dataset generated through morphological characters and molecular markers (RAPD and ISSR) showed a comparable output grouping the isolates Tv4, TvChen and TvNir in one cluster and all T. harzianum isolates in another cluster. Multiple nucleotide alignment of ITS 1 and ITS 2 region produced 100% homology among T. harzianum isolates whilst the nucleotide substitution at 62nd and 150th position of ITS 1 region and 27th and 40th position of ITS 2 region differentiated Tv4, TvChen and TvNir from other T. viride isolates. Genetic assessment could not establish substantial disparity among T. harzianum isolates which was comparable with its antagonism. The genetic distinctness of Tv4, TvChen and TvNir isolates authenticated their higher degree of antagonism. It is obvious from the present study that genetic diversity analysis had a positive correlation with the antagonistic ability of Trichoderma isolates. Thus an integrated approach of morphological and molecular markers can be employed to identify a superior strain of Trichoderma for its commercial exploitation.Key words: Trichoderma, antagonism, morphological and molecular characters, RAPD, ISSR, ITS

Study of A Delayed SIVA Within-Host Model of Dengue Virus Transmission

During the process of immune response to the infection caused by dengue virus, antibodies are generated by plasma cells which are produced by B-cells. In some cases, it is observed that there is a delay in the production of plasma cells from B-cells which causes a delay in the immune response. We propose a SIVA within-host model of the virus transmission with delayed immune response to articulate the dynamics of the cell and virus population. The stability analysis of different equilibrium states is also studied. The basic reproduction number (BRN) of the model is computed using next generation matrix (NGM) method. The local stability analysis is discussed using the method of linearisation. The stability conditions of the equilibrium states are validated using the Li´enard - Chipart criterion. Hopf bifurcation analysis is carried out as the system has time lag in the immune response. Three equilibrium states, namely, virus free equilibrium state, endemic equilibrium state with and without immune response, have been observed. It has been found that the virus free equilibrium state is locally asymptotically stable if BRN is less than or equal to 1. Additionally, the conditions for the stability of the endemic equilibrium points are derived and elaborated. Numerical simulations for different values of time delay parameter τ are presented and illustrated using graphs. A Hopf bifurcation is observed if the delay parameter τ crosses a threshold value and then the system becomes unstable with periodic solution. To determine the relative importance of the model parameters to the virus transmission and prevalence, sensitivity analysis of the parameters is illustrated using graphs. Due to the time lag in the immune response, an increase in the virus growth is observed in large quantity. As a result, the infection spreads more quickly within the host

Implementation of security module to protect programme theft in microcontroller-based applications

Source code plagiarism has become a serious threat for the development of small scale embedded industries and also the violations of intellectual property right are a threat for the development of hardware system. There are many software solutions for comparing source codes, but they are often not realistic in the present scenario. Digital watermarking scheme is one of the possible solutions for this problem. A novel watermarking technique is employed so that it can be easily and reliably detected by special techniques. In this paper, verification methods are presented to detect software plagiarism in the embedded application software without the implemented source code. All the approaches use side-channel information obtained during the execution of the suspicious code. The primary method is passive, i.e. no previous modification of the original code is required. It determines that the Hamming weights of the executed instructions of the suspicious device are used and uses string matching algorithms for comparisons with a reference implementation. The other method inserts additional code fragments as a watermark that can be identified in the power consumption of the executed source code. Proposed approaches are robust against code-transformation attacks

Metallic monoclinic phase in VO2_2 induced by electrochemical gating: in-situ Raman study

We report in-situ Raman scattering studies of electrochemically top gated VO$_2$ thin film to address metal-insulator transition (MIT) under gating. The room temperature monoclinic insulating phase goes to metallic state at a gate voltage of 2.6 V. However, the number of Raman modes do not change with electrolyte gating showing that the metallic phase is still monoclinic. The high frequency Raman mode A$_g$(7) near 616 cm$^{-1}$ ascribed to V-O vibration of bond length 2.06 \AA~ in VO$_6$ octahedra hardens with increasing gate voltage and the B$_g$(3) mode near 654 cm$^{-1}$ softens. This shows that the distortion of the VO$_6$ octahedra in the monoclinic phase decreases with gating. The time dependent Raman data at fixed gate voltages of 1 V (for 50 minute, showing enhancement of conductivity by a factor of 50) and 2 V (for 130 minute, showing further increase in conductivity by a factor of 5) show similar changes in high frequency Raman modes A$_g$(7) and B$_g$(3) as observed in gating. This slow change in conductance together with Raman frequency changes show that the governing mechanism for metalization is more likely to the diffusion controlled oxygen vacancy formation due to the applied electric field.Comment: 5 pages, 6 figure

Hydrostatic pressure effect on Tc of new BiS2 based Bi4O4S3 and NdO0.5F0.5BiS2 layered superconductors

We investigate the external hydrostatic pressure effect on the superconducting transition temperature (Tc) of new layered superconductors Bi4O4S3 and NdO0.5F0.5BiS2. Though the Tc is found to have moderate decrease from 4.8 K to 4.3 K (dTconset/dP = -0.28 K/GPa) for Bi4O4S3 superconductor, the same increases from 4.6 K to 5 K (dTconset/dP = 0.44 K/GPa) upto 1.31 GPa followed by a sudden decrease from 5 K to 4.7 K upto 1.75 GPa for NdO0.5F0.5BiS2 superconductor. The variation of Tc in these systems may be correlated to increase or decrease of the charge carriers in the density of states under externally applied pressure.Comment: 3 pages text +Fig

On the chromosomes of a bivalve, Anadara rhombea

Study of chromosomes of bivalves is technically difficult. Spermatogonia and spermatocytes, oocytes, and cleavage stages of the fertilized eggs are more favourable than the somatic tissues of the adultss for the study of chromosomes. Hypotonic treatment, prior to fixation, is an essential pretreatment for obtaining well-spread chromosomes. 1he study of the chromosomes of a bivalve, Anadara rhombea, from the Porto Novo waters, has been the first of its kind in an Indian bivalve. Oiakinet'C and first metaphase stages from 'squash' preparations of testis show that in male 2n •= 28 in this species; the sex chromosomes, if any, are not distinguishable