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Abrasive waterjet machining of Ti/CFRP/Ti laminate and multi-objective optimization of the process parameters using response surface methodology
No full textIn present work, abrasive waterjet machining has been used to machine adhesively bonded titanium-carbon fiber-reinforced plastics-titanium hybrid laminate with varying traverse speed, jet pressure, and stand-off distance. The effect of varying abrasive waterjet machining parameters on cut quality has been quantified by material removal rate, metal composite interface damage factor, taper ratio (T-r), and surface roughness (R-a). Response surface methodology along with central composite design has been used to analyze the influence of process parameters on output responses. Additionally, analysis of variance was performed to identify the significant parameters on the output responses. For better abrasive waterjet cut quality, the optimal values of process parameters obtained were 200 MPa jet pressure, 237.693 mm/min traverse speed, and 1 mm stand-off distance. The corresponding material removal rate, metal composite interface damage factor, taper ratio, and surface roughness are 5.388 mm(3)/s, 1.41, 1.16, and 3.827 mu m, respectively. Furthermore, validation tests have been performed with obtained optimal parameters that deliver satisfactory outcomes with an error of 5.35%, 3.07%, 2.29%, and 0.39% for material removal rate, metal composite interface damage factor, taper ratio, and surface roughness, respectively
Pseudorapidity distributions of charged hadrons in xenon-xenon collisions at root S-NN=5.44 TeV
No full textMeasurements of the pseudorapidity distributions of charged hadrons produced in xenon-xenon collisions at a nucleon-nucleon centre-of-mass energy of root S-NN = 5.44 TeV are presented. The measurements are based on data collected by the CMS experiment at the LHC. The yield of primary charged hadrons produced in xenon-xenon collisions in the pseudorapidity range vertical bar eta vertical bar < 3.2 is determined using the silicon pixel detector in the CMS tracking system. For the 5% most central collisions, the chargedhadron pseudorapidity density in the midrapidity region vertical bar eta vertical bar < 0.5 is found to be 1 187 +/- 36 (syst), with a negligible statistical uncertainty. The rapidity distribution of charged hadrons is also presented in the range vertical bar y vertical bar < 3.2 and is found to be independent of rapidity around y = 0. Existing Monte-Carlo event generators are unable to simultaneously describe both results. Comparisons of charged-hadron multiplicities between xenon-xenon and lead-lead collisions at similar collision energies show that particle production at midrapidity is strongly dependent on the collision geometry in addition to the system size and collision energy
A Novel Technique to Investigate the Role of Traps in the Off-State Performance of AlGaN/GaN High Electron Mobility Transistor on Si Using Substrate Bias
No full textLeakage mediated by GaN buffer traps is identified and studied using a novel characterization technique. Through back-gating measurement, the effect of buffer trap states on the lateral leakage is determined by probing mesa-isolated Ohmic pads. Time-dependent leakage measurements are carried out to study the extent of the increase in buffer leakage due to the traps. It is observed that the mesa leakage is more prominent at very slow sweep rates and high substrate bias. The temperature-dependent measurements show that the mesa leakage and the substrate leakage are characterized by thermionic emission from the traps with an activation barrier of 0.34 and 0.2 eV, respectively
Magnetoelectric 0.2(CoFe2O4)-0.8(Ba0.85Ca0.15 Zr0.1Ti0.9O3) lead free composite for spintronic applications
No full textLead free (0.2) CoFe2O4 (CFO)-(0.8) Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) composite is prepared by mechanical mixing of CFO and BCZT phases. The constituent phases, CFO and BCZT are prepared by sol-gel technique. XRD data shows characteristic peaks of both magnetic and piezoelectric phases without any secondary phases confirming the formation of the composite. Polarization (P) versus Electric field (E) measurements show a proper ferroelectric loop for BCZT with P max � 4.3 μC/cm2 whereas composite shows a leaky behaviour. Room temperature M-H loops show a decrease of magnetization from � 80 emu/g for pure CFO to 17 emu/g for composite. Thus, 0.2 CFO-0.8 BCZT composite shows both electric and magnetic properties at room temperature
Halogen Bonding in Biomimetic Deiodination of Thyroid Hormones and their Metabolites and Dehalogenation of Halogenated Nucleosides
No full textThyroid hormones (THs) are key players in the endocrine system and play pivotal roles in carbohydrate and fat metabolism, protein synthesis, overall growth, and brain development. The thyroid gland predominantly produces thyroxine or 3,5,3â�²,5â�²-tetraiodothyronine (T4) as a prohormone; three isoforms of a mammalian selenoenzymeâ��iodothyronine deiodinase (DIO1, DIO2 and DIO3)â��catalyze the regioselective deiodination of T4 to produce biologically active and inactive metabolites. Whereas DIO1 catalyzes both 5- and 5â�²-deiodination of T4, DIO2 and DIO3 selectively mediate 5- and 5â�²-deiodination, respectively. In this review we discuss the regioselective deiodination of THs in the presence of organochalcogen compounds. Naphthalene-based compounds containing sulfur and/or selenium at the peri positions mediate regioselective 5-deiodination of THs, detailed mechanistic studies having revealed that the heterolytic cleavage of the Câ��I bond is facilitated by the formation of cooperative Se/Sâ� â� â� I halogen bonds and Se/Sâ� â� â� Se chalcogen bonds. We also discuss the biomimetic deiodination of several TH metabolites, including sulfated THs, iodothyronamines, and iodotyrosines. A brief discussion on the dehalogenation of halogenated nucleosides and nucleobases in the presence of organochalcogen compounds is also included. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei
Nucleosynthesis in advective accretion disc and outflow: possible explanation for overabundances in winds from X-ray binaries
No full textMultiple spectroscopic lines of different elements observed in winds from X-ray binaries (XRBs), based on one-zone model, indicate super-solar abundance of elements, e.g. Mg, Si, S, Ar, Ca, Cr, Mn, and Co. The one-zone model considers similar hydrodynamics of underlying winds. In order to find a possible origin of these overabundances, we explore nucleosynthesis in advective, geometrically thick, sub-Keplerian, accretion disc in XRBs and active galactic nuclei (AGNs), and further in outflows launched from the disc. Based on flow hydrodynamics and solving nuclear network code therein by semi-implicit Euler method, we obtain abundance evolution of the elements. Although the density is very low, due to very high temperature of advective disc than Keplerian Shakura-Sunyaev disc (SSD), it is quite evident that significant nucleosynthesis occurs in the former. As the temperature at the base of the outflow is constrained by the temperature of disc, nucleosynthesis also occurs in the outflow contingent upon its launching temperature. Till now, the outer region of XRB and AGN discs is understood to be colder SSD and inner region to be advective disc, together forming a disc-wind system. Hence, newly evolved abundances after processing through outflow can change the abundances of different elements present in the environment of the whole disc-wind system. We find two to six times overabundant Mg, Si, Ar, and Cr with respect to the respective solar abundances, which is consistent observationally. Thus, for most XRBs, when only iron lines are present, inclusion of these evolved abundances is expected to change the observational analysis drastically
SN 2016B a.k.a. ASASSN-16ab: a transitional Type II supernova
No full textWe present photometry, polarimetry, and spectroscopy of the Type II supernova ASASSN-16ab/SN 2016B in PGC 037392. The photometric and spectroscopic follow-up commenced about 2 weeks after shock breakout and continued until nearly 6 months. The light curve of SN 2016B exhibits intermediate properties between those of Type IIP and IIL. The early decline is steep (1.68 +/- 0.10 mag 100 d(-1)), followed by a shallower plateau phase (0.47 +/- 0.24 mag 100 d(-1)). The optically thick phase lasts for 118 d, similar to Type IIP. The Ni-56 mass estimated from the radioactive tail of the bolometric light curve is 0.082 +/- 0.019 M-circle dot. High-velocity component contributing to the absorption trough of H alpha and H beta in the photospheric spectra are identified from the spectral modelling from about 57-97 d after the outburst, suggesting a possible SN ejecta and circumstellar material interaction. Such high-velocity features are common in the spectra of Type IIL supernovae. By modelling the true bolometric light curve of SN 2016B, we estimated a total ejected mass of similar to 15 M-circle dot, kinetic energy of similar to 1.4 foe, and an initial radius of similar to 400 R-circle dot
Association of mitochondria with microtubules inhibits mitochondrial fission by precluding assembly of the fission protein Dnm1
No full textMitochondria are organized as tubular networks in the cell and undergo fission and fusion. Although several of the molecular players involved in mediating mitochondrial dynamics have been identified, the precise cellular cues that initiate mitochondrial fission or fusion remain largely unknown. In fission yeast (Schizosaccharomyces pombe), mitochondria are organized along microtubule bundles. Here, we employed deletions of kinesin-like proteins to perturb microtubule dynamics and used high-resolution and time-lapse fluorescence microscopy, revealing that mitochondrial lengths mimic microtubule lengths. Furthermore, we determined that compared with WT cells, mutant cells with long microtubules exhibit fewer mitochondria, and mutant cells with short microtubules have an increased number of mitochondria because of reduced mitochondrial fission in the former and elevated fission in the latter. Correspondingly, upon onset of closed mitosis in fission yeast, wherein interphase microtubules assemble to form the spindle within the nucleus, we observed increased mitochondrial fission. We found that the consequent rise in the mitochondrial copy number is necessary to reduce partitioning errors during independent segregation of mitochondria between daughter cells. We also discovered that the association of mitochondria with microtubules physically impedes the assembly of the fission protein Dnm1 around mitochondria, resulting in inhibition of mitochondrial fission. Taken together, we demonstrate a mechanism for the regulation of mitochondrial fission that is dictated by the interaction between mitochondria and the microtubule cytoskeleton. © 2019 Mehta et al
Evidence of adaptive modulation and magnetic field induced reorientation of variants in epitaxially grown Ni-Mn-Ga thin film on Al 2 O 3 (112¯0) substrate
No full textEpitaxial Ni-Mn-Ga thin films with a room temperature martensite phase were fabricated on single crystal Al 2 O 3 (112¯0) substrate using direct current (DC) magnetron sputtering. The X-ray pole figure measurements confirm the epitaxial relationship of Ni-Mn-Ga (101) 7M || Al 2 O 3 (112¯0) and Ni-Mn-Ga 101¯ 7M || Al 2 O 3 11¯01 between the film and substrate. Transmission electron microscopy reveals the presence of (220) micro-twins at an angle of 62.5° and 56.3° with respect to (202) growth plane. Coexistence of non-modulated martensite phase (a NM = 5.45 à and c NM = 6.56 à ) and seven modulated martensite phases (a 14M =6.26à ,b 14M =5.89à andc 14M =5.56à ) has been observed in the film. The in-situ high-temperature X-ray diffraction indicates reversible thermal phase transformation in the film with a very low thermal hysteresis. The magnetic field induced reorientation (MIR) effect is displayed by the film. © 201