MICROSTRUCTURE ANALYSIS FOR WEAR PROPERTIES OF Al 6061 ALLOY REINFORCED WITH SiC,Al2O3 USED IN AUTOMOBILE COMPONENTS

The Aluminum 6061 was used as a matrix material for its good mechanical properties with its good formability. The Numerous technological challenges are present in the casting methods for requiring a proper split of reinforcements in the matrix. In this work Al6061alloy acted as a matrix material and Al2O3, SiC, are used as reinforcement one. Composites were produced by liquid metallurgy technique (stir casting) for minimizing the castings fault and to increase the proper mixing of reinforcement and matrix. Al 6061 alloy is melted at 695°C and then preheated reinforcements are added with the stirrer speed around 150 RPM. The minimum level of magnesium is added for increasing the usability and then molten metal is transferred into the mold cavity for machining composite as per the ASTM standards to conduct a tribological test in Pin on Disc apparatus. The Sliding wear tests are conducted at various loads, Speeds, Sliding distances. Experimental results tells the minimum wear is found in Al2O3 and SiC 6%wt compared with Al 6061alloy.These minimum wear property of the material is used in various automobile components such as Gear teeth, Steering box, Propeller shaft

Unoccupied electronic states of icosahedral Al-Pd-Mn quasicrystals: Evidence of image potential resonance and pseudogap

We study the unoccupied region of the electronic structure of the fivefold symmetric surface of an icosahedral (i) Al-Pd-Mn quasicrystal. A feature that exhibits parabolic dispersion with an effective mass of (1.15±0.1)me and tracks the change in the work function is assigned to an image potential resonance because our density functional calculation shows an absence of band gap in the respective energy region. We show that Sn grows pseudomorphically on i−Al−Pd−Mn as predicted by density functional theory calculations, and the energy of the image potential resonance tracks the change in the work function with Sn coverage. The image potential resonance appears much weaker in the spectrum from the related crystalline Al-Pd-Mn surface, demonstrating that its strength is related to the compatibility of the quasiperiodic wave functions in i−Al−Pd−Mn with the free-electron-like image potential states. Our investigation of the energy region immediately above EF provides unambiguous evidence for the presence of a pseudogap, in agreement with our density functional theory calculations

Modulation on Ni2MnGa(001) surface

We report periodic modulation on (001) surface of Ni2MnGa ferromagnetic shape memory alloy. For the stoichiometric surface, analysis of the low energy electron diffraction (LEED) spot profiles shows that the modulation is incommensurate. The modulation appears at 200 K, concomitant with the first order structural transition to the martensitic phase

A longitudinal cline characterizes the genetic structure of human populations in the Tibetan plateau

Indigenous populations of the Tibetan plateau have attracted much attention for their good performance at extreme high altitude. Most genetic studies of Tibetan adaptations have used genetic variation data at the genome scale, while genetic inferences about their demography and population structure are largely based on uniparental markers. To provide genome-wide information on population structure, we analyzed new and published data of 338 individuals from indigenous populations across the plateau in conjunction with worldwide genetic variation data. We found a clear signal of genetic stratification across the east-west axis within Tibetan samples. Samples from more eastern locations tend to have higher genetic affinity with lowland East Asians, which can be explained by more gene flow from lowland East Asia onto the plateau. Our findings corroborate a previous report of admixture signals in Tibetans, which were based on a subset of the samples analyzed here, but add evidence for isolation by distance in a broader geospatial context

Heterologous Expression of Serine Hydroxymethyltransferase-3 From Rice Confers Tolerance to Salinity Stress in E. coli and Arabidopsis

Among abiotic stresses, salt stress adversely affects growth and development in rice. Contrasting salt tolerant (CSR27), and salt sensitive (MI48) rice varieties provided information on an array of genes that may contribute for salt tolerance of rice. Earlier studies on transcriptome and proteome profiling led to the identification of salt stress-induced serine hydroxymethyltransferase-3 (SHMT3) gene. In the present study, the SHMT3 gene was isolated from salt-tolerant (CSR27) rice. OsSHMT3 exhibited salinity-stress induced accentuated and differential expression levels in different tissues of rice. OsSHMT3 was overexpressed in Escherichia coli and assayed for enzymatic activity and modeling protein structure. Further, Arabidopsis transgenic plants overexpressing OsSHMT3 exhibited tolerance toward salt stress. Comparative analyses of OsSHMT3 vis a vis wild type by ionomic, transcriptomic, and metabolic profiling, protein expression and analysis of various traits revealed a pivotal role of OsSHMT3 in conferring tolerance toward salt stress. The gene can further be used in developing gene-based markers for salt stress to be employed in marker assisted breeding programs.HIGHLIGHTS- The study provides information on mechanistic details of serine hydroxymethyl transferase gene for its salt tolerance in rice

Characterization of CaF₂/acetone bandpass photon detector with Kr filter gas

A modified design of a CaF2/acetone bandpass photon detector that uses Kr as a filter gas to tune the energy resolution is presented. Our design combines two standard single window detector tubes to build the Kr filter gas chamber. Synchrotron radiation has been used to determine the energy resolution of the detector, as a function of Kr pressure. The improvement in the detector energy resolution by 250 meV compared to the CaF2/acetone detector is better than that reported earlier. Substantial variation in the shape of the CaF2/acetone detector response functions is observed for different acetone pressure (≤3 mbar), and anode voltage (≤800 V). Our analysis reveals that the changes in the shape of the detector response function are associated to different regions of the detector operation

Electronic structure of single crystal and highly oriented pyrolytic graphite from ARPES and KRIPES

We present a comparative study of the near fermi-level electronic structure of single crystal and highly oriented pyrolytic graphite (HOPG). Angle resolved photoelectron spectroscopy and angle resolved inverse photoelectron spectroscopy have been used to probe the occupied and unoccupied electronic states, respectively. The band dispersions showed by single crystal graphite along its ΓK and ΓM symmetry directions were found to be in agreement with calculated band structure of graphite. The p bands of single crystal graphite were found to have a splitting of ~0.5eV at the K-point. We also observe the presence of a quasiparticle peak below EF at the K point at low temperature which indicates a strong electron-phonon coupling in graphite. In HOPG, the M and K points like features were found to be present in the same radial direction due to the superposition of the ΓM and ΓK directions. Results from our angle resolved inverse photoemission spectroscopy present the dispersion of the conduction band states, particularly the lower Π1 band. We have also found the presence of some non-dispersive features in both the valence and the conduction bands