Optical properties and structure characterization of sapphire after Ni ion implantation and annealing

Implantation of 64 keV64keV Ni ions to sapphire was conducted at room temperature to 1×1017 ions/cm21×1017ions∕cm2 with a current density of 55 or 10 μA/cm210μA∕cm2. Metallic Ni nanoparticles were formed with the 5 μA/cm25μA∕cm2 ion current and the NiAl2O4NiAl2O4 compound was formed with the 10 μA/cm210μA∕cm2 ion current. The crystals implanted with both current densities were annealed isochronally for 1 h1h at temperatures up to 1000 °C1000°C in steps of 100 °C100°C in an ambient atmosphere. Optical absorption spectroscopy, x-ray diffraction, transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy have been utilized to characterize the samples. The surface plasmon resonance (SPR) absorption band peaked at 400 nm400nm due to the Ni nanoparticles shifted toward the longer wavelength gradually with the annealing temperature increasing from 400 to 700 °C400to700°C. The SPR absorption band disappeared after the annealing temperature reached 800 °C800°C. NiO nanoparticles were formed at the expense of Ni nanoparticles with an increasing annealing temperature. The TEM analyses revealed that the nanoparticles grew to 6–20 nm6–20nm and migrated toward the surface after annealing at 900 °C900°C. The absorption band at 430 nm430nm from Ni2+Ni2+ cations in NiAl2O4NiAl2O4 did not shift with the increasing annealing temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87389/2/073524_1.pd

Photoluminescence of SnO2 nanoparticles embedded in Al2O3

"Tetragonal Sn nanoparticles of [?]15 nm diameter are produced in Al2O3 by direct Sn implantation at room temperature. After thermal annealing at 1000 degC in oxygen, the implantation-induced amorphous region recrystallized and the Sn nanoparticles turned into SnO2 nanoparticles with an average diameter of [?]30 nm as revealed by transmission electron microscopy. While no absorption and photoluminescence (PL) are observed from the metallic Sn nanoparticles, SnO2 nanoparticles exhibit an absorption edge at [?]280 nm and three emission bands at 410 nm, 520 nm and 700 nm, respectively. In addition to the previously reported blue and green emission from SnO2 nanostructures, a red PL band was observed due to the unique surface state of SnO2 nanoparticles embedded in Al2O3 substrate fabricated by ion implantation."http://deepblue.lib.umich.edu/bitstream/2027.42/64215/1/d8_22_225102.pd

Theoretical investigation of structural, energetic and electronic properties of titanate pyrochlores

Ab initio total energy calculations using the plane-wave pseudopotential method based on density functional theory were carried out to investigate the structural, energetic and electronic properties of A2Ti2O7 (A =  La, Gd and Yb) pyrochlores. It turned out that the formation energies of antisite defects are not linearly dependent on the ratio of the cation radii, and, for the three compositions, the cation antisite formation energy is largest for Gd2Ti2O7 pyrochlore. It was indicated that Gd2Ti2O7 compound is the least likely to form defect fluorite structure, which gives rise to the least resistance to radiation-induced amorphization. DOS analysis showed that stronger interaction exists in the Gd2Ti2O7 compound, and its electronic structure is very different from that of La2Ti2O7 and Yb2Ti2O7. Our calculations suggested that the electronic structure of the A cation and bond type should be taken into account when explaining the response behavior of A2Ti2O7 (A =  La, Gd, Yb) pyrochlores to ion irradiation-induced amorphization.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58124/2/cm7_34_346203.pd

Effect of electron irradiation on the transformation characteristics of narrow hysteresis TiNiCu shape memory alloys

TiNiCu shape memory alloy samples were irradiated by 1.7 MeV electrons below the martensite finish temperature Mf.Mf. The transformation temperatures and the latent heat of phase transformation were measured by differential scanning calorimeter. The damage accumulation was determined by positron annihilation technology. The results indicated that the austenite transformation temperatures were raised, and the hysteresis was increased by the irradiation. The electron irradiation had a slight effect on Mf,Mf, and no detectable effect on the martensitic transformation start temperature Ms.Ms. The second lifetime of positrons were increased by the electron irradiation indicating the increase in the size and amount of vacancy clusters, which contributed to the observed change of the transformation characteristics. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70937/2/APPLAB-80-1-31-1.pd

Fabrication and characterization of wire-like SnO2

Wire-like SnO2 is fabricated by the wet chemical method. X-ray diffraction measurements show that the obtained samples have rutile-type structure. Electron transmission microscopy experiments illustrate that the wire-like SnO2 ranged from 10 to 50 nm in width and several microns (µm) in length. The high-resolution TEM indicates that SnO2 wires are single crystals. The possible growth mechanism is proposed, and it is found that polyethylene glycol plays an important role in obtaining the wire-like and nano-rods morphology of SnO2. The band gap is determined to be 3.56 eV. Two photoluminescence peaks located at 389 and 470 nm are observed. Our fabrication method promises a simple way of synthesizing wire-like SnO2 at a low temperature of 350°C.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48911/2/d6_12_004.pd

Vertical jetting induced by shear horizontal leaky surface acoustic wave on 36°Y-X LiTaO3

Shear horizontal surface acoustic waves (SH-SAWs) have been regarded as a good candidate for liquid sensing applications, but being inefficient in fluid manipulation due to a minimal fluid coupling between the fluid and acoustic waves. However, in this letter, a vertical jetting function was realized using the SH-SAW generated from a 36°Y-X LiTaO3 SAW device. The jetting of the droplet induced by the SH-SAWs was observed nearly along vertical direction, and the aspect ratio of the liquid beam is proportional to the applied power before breaking up, which is dramatically different from those generated from the conventional Rayleigh SAWs. By conducting theoretical simulation and experimental investigation on the SH-SAWs systematically, we concluded that the wave/energy pressure dissipated into the sessile droplets causes this vertical ejection on the device surface

Assessment of the determinant of choice of ‘over the counter’ analgesics among students of a university in Abbottabad, Pakistan

Purpose: To ascertain the preference of COMSATS Institute of Information Technology, Abbottabad, Pakistan (CIIT) students for various ‘over the counter’ analgesics.Methods: This cross-sectional survey study on self-medication of ibuprofen in students of CIIT was conducted in July - August 2013 using a self-administered questionnaire. Five hundred students with an average age of 20 - 25 years cooperated in this inquisition. The questionnaire contained 18 questions including socio-demographic queries, economical status, perception of the frequency of pain, their locality, and behavior and knowledge of participants on the use of ibuprofen regarding its therapeutic and adverse effects, and interactions.Results: Out of the 500 participants in the study, 70.4 % were female. The response rate was 68.2 %. Ibuprofen (54 %) was the most used analgesic of all the NSAIDs among the respondents. Approximately, 11.2 % of the respondents reported that they suffer from pain almost every day. The younger and more educated respondents had better level of awareness about the ibuprofen’s indications as compared to those who had low level of education. Of the respondents, 29.6 % were not aware of any side effect caused by ibuprofen. Approximately, 22.4 % of the respondents had no knowledge of the interactions of ibuprofen while 61.2 % of the participants consult a physician about painkillers.Conclusion: Although many of the students undergo almost daily pain and favor ibuprofen over other NSAIDs analgesics among but they still lack information on its appropriate handling and safety. The overall result of the survey indicates very low level of information about the drug interaction.Keywords: Pain, OTC, analgesic, ibuprofen, questionnaire based survey, awarenes

ZnO nanoparticles embedded in sapphire fabricated by ion implantation and annealing

ZnO nanoparticles were fabricated in sapphire (α-Al2O3 single crystal) by Zn ion implantation (48 keV) at an ion fluence of 1 × 1017 cm−2 and subsequent thermal annealing in a flowing oxygen atmosphere. Transmission electron microscopy (TEM) analysis revealed that metallic Zn nanoparticles of 3–10 nm in dimensions formed in the as-implanted sample and that ZnO nanoparticles of 10–12 nm in dimensions formed after annealing at 600 °C. A broad absorption band, peaked at 280 nm, appeared in the as-implanted crystal, due to surface plasma resonance (SPR) absorption of metallic Zn nanoparticles. After annealing at 600 °C, ZnO nanoparticles resulted in an exciton absorption peak at 360 nm. The photoluminescence (PL) of the as-implanted sample was very weak when using a He–Cd 325 nm line as the excitation source. However, two emission peaks appeared in the PL spectrum of ZnO nanopraticles, i.e., one ultraviolet (UV) peak at 370 nm and the other a green peak at 500 nm. The emission at 500 nm is stronger and has potential applications in green/blue light-emitting devices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49223/2/nano6_10_032.pd