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991.
Kumar S Hundal MS Kaur N Singh R Singh H Hundal Nee Sood G Ripoll MM Aparicio JS 《The Journal of organic chemistry》1996,61(22):7819-7825
The N(Py).HN(amide) hydrogen bonding within the macrocyclic cavities in 9, 10, and 13 invokes their symmetrical electron-deficient structures ((1)H NMR) and consequently bind with water. This results in their poor ionophore characters. The steric requirement of methyl/benzyl substituents on amide N in 11 and 12 takes the substituents out of the cavity and thus positions the amide O toward the cavity ((1)H, (13)C NMR and X-ray analysis). This arrangement of two pyridine N and two amide O ((13)C NMR, IR) binding sites provides an appropriate environment for selective binding toward Ag(+) over Pb(2+), Tl(+), alkali, and alkaline earth cations. The increased spacer length in 14 leads to a lop-sided twist of pyridine rings (X-ray) and disturbs the above arrangement and leads to its poor binding character. 相似文献
992.
In this paper the effect of temperature on the mechanoluminescence of Au doped phosphors of(Zn,Cd)S is described.It is found that the ML disappears beyond a particular temperature.The temperature dependence of ML intensity follows the relation I =I_T~O(1-TIT_C)~n,where I_T~O is a constant,n is the slop of log I_T versus log(1- TIT_C) plot which lies between 0.9 and 1.10,T_C is the temperature at which ML disappear.It is found that the ML intensity in(Zn,Cd)S:Au disappear at 600 K. 相似文献
993.
S.K. Mehta Gurpreet Kaur Ruchi Mutneja K.K. Bhasin 《Journal of colloid and interface science》2009,338(2):542-549
A U-type microemulsion of Brij 96 has been characterized with respect to the change in cosurfactant, oil chain length on dilution, water solubility, and water solubilization capacity. The phase behavior of the systems has been mapped with different oils. Several techniques, viz., conductivity, optical microscopy, dilution method, absorption, and FT-IR spectroscopy, have been used for microemulsion analysis. The equilibrium within the microemulsion droplets and liquid crystals has been visualized using optical microscopy. The microemulsions have evidenced volume-induced conductance percolation in all the cosurfactants (n2–n6 alcohols). The energetics of transfer of alcohol from the bulk oil to the interface has been determined through dilution method. To gain insight into the microenvironment of microemulsion, two optical probes, hydrophilic (Methyl orange) and hydrophobic (Nile red), have been utilized in absorption spectroscopy. Lastly, FT-IR has been explored to observe the state and dissolution behavior of water with increasing weight fraction. 相似文献
994.
Navneet Kaur Martine Lacasse Alexandra Fürtös Karen C. Waldron André Morin 《Journal of chromatography. A》2009,1216(23):4703-4712
Chlorogenic acid is the most abundant polyphenol found in the tobacco plant. The biological effects of its combustion products remain largely unknown. In this study, chlorogenic acid was burned at 640 °C for 2 min and the particulate matter of the smoke was collected onto Cambridge filter pads followed by selective extraction in five different solvents. Various fractions of the chlorogenic acid combustion products were tested for induction of micronuclei in V79 Chinese hamster fibroblast cells. Over 40 compounds were identified in the dimethyl sulfoxide (DMSO) extract by high-performance liquid chromatography coupled to electrospray time-of-flight mass spectrometry (HPLC/TOF-MS). The DMSO extract was then fractionated into three major fractions by preparative LC. The fraction inducing the highest degree of toxicity was further separated into four sub-fractions. The sub-fraction responsible for the most toxic response was determined to contain catechol as its major component. The overall reproducibility of the combustion, the extraction procedure and the chemical characterization of the compounds responsible for the toxicity in the chlorogenic acid smoke were evaluated by LC/TOF-MS. 相似文献
995.
Nanocrystalline TiN/NiTi thin films have been grown on silicon substrate by dc magnetron sputtering to improve the corrosion and mechanical properties of NiTi based shape memory alloys without sacrificing the phase transformation effect. Interestingly, the preferential orientation of the TiN films was observed to change from (1 1 1) to (2 0 0) with change in nature of sputtering gas from 70% Ar + 30% N2 to 100% N2. In present study the influence of crystallographic orientation of TiN on mechanical and corrosion properties of TiN/NiTi thin films was investigated. TiN (2 0 0)/NiTi films were found to exhibit high hardness, high elastic modulus, and thereby better wear resistance as compared to pure NiTi and TiN (1 1 1)/NiTi films. Electrochemical test revealed that TiN coated NiTi film exhibits better corrosion resistance in 1 M NaCl solution as compared to uncoated NiTi film. The application of TiN/NiTi films in the electrochemical sensing of dopamine, which has a critical physiological importance in Parkinson's disease, has been demonstrated. A comparison of voltammetric response of dopamine at silicon based electrodes modified with different nanocrystalline coatings indicated that these films catalyze the oxidation of dopamine. 相似文献
996.
Swift heavy ions interact predominantly through inelastic scattering while traversing any polymer medium and produce excited/ionized
atoms. Here samples of the polycarbonate Makrofol of approximate thickness 20 μm, spin coated on GaAs substrate were irradiated
with 50 MeV Li ion (+3 charge state). Build-in modifications due to irradiation were studied using FTIR and XRD characterizations.
Considerable changes have been observed in the polymer while varying the fluence from 1E11 ion/cm2 to 1E13 ion/cm2 Li ions. AFM images of the surface modifications caused by ion irradiation on the polymer are also presented.
相似文献
997.
Narinder Singh Ray C. Mulrooney Navneet Kaur John F. Callan 《Journal of fluorescence》2009,19(5):777-782
Schiff base receptor 1a has been synthesised and attached to the surface of preformed CdSe/ZnS Quantum Dots (QDs) to form QD-conjugate 2a. While 1a was determined to be selective for Mg2+, 2a demonstrated selectivity for both K+ and Ca2+ when tested against a range of physiologically and environmentally relevant cations by changes in the fluorescence spectra. Thus, the nanoparticle surface functions as a scaffold for the organisation of receptors enabling semi-selective binding. The fluorescence response was shown to be linear between 15–50?μM for K+ and 2–35?μM for Ca2+. It was also demonstrated that 2a could measure both K+ and / or Ca2+ in solutions containing both ions. 相似文献
998.
Mohan Singh Bikram Singh Navjeet Kaur Lakhwant Singh 《Indian Journal of Physics》2009,83(8):1099-1107
A comparative study of various stopping power tables and codes for heavy ions in gases has been made through comparison of
computed values and the corresponding experimental data. Ten gaseous media: five monatomic rare gases (He to Xe), two diatomic
gases (H2, N2) and three polyatomic gaseous compounds (CH4, CF4 and CO2) have been chosen to study the stopping power investigations of heavy ions (8 ≤ Z ≤ 92) having energy ranges of ∼0.10–10.00
MeV/n and ∼20.00–57.00 MeV/n. We compare the experimental data of stopping power to values calculated using various tables
and computer codes by ICRU-73, Ziegler et al (SRIM2003.26), Grande and Schiwietz (CasP3.1), Paul and Schinner (MSTAR3.12), and Bazin and Tarasov (LISE ++:2-ATIMA1.2).
On the basis of statistical analysis, we estimate the reliability of these tables and codes. It has been observed that the
MSTAR3.12 code shows the best agreement with the experimental data for projectile ions (8 ≤ Z ≤ 18) in the entire energy range. The SRIM2003.26 code provides good results except for some heavy projectiles (Xe, Pb and
U). The values tabulated by CasP3.1 code underestimate especially at low energy region. No significant trend is observed in
case of LISE++:2-ATIMA1.2 code and ICRU-73 report. 相似文献
999.
Amanpreet Kaur Sandhu Surinder Singh Om Prakash Pandey 《Indian Journal of Physics》2009,83(7):985-991
Silica based glasses are used as nuclear shielding materials. The effect of radiation on these glasses varies as per the constituents
used in these glasses. Glasses of different composition of SiO2-Na2OMgO-Al2O3 were made by melt casting techniques. These glasses were irradiated with neutrons of different fluences. Optical absorption
measurements of neutron-irradiated silica based glasses were performed at room temperature (RT) to detect and characterize
the induced radiation damage in these materials. The absorption band found for neutron-irradiated glasses are induced by hole
type color centers related to non-bridging oxygen ions (NBO) located in different surroundings of glass matrix. Decrease in
the transmittance indicates the formation of color-center defects. Values for band gap energy and the width of the energy
tail above the mobility gap have been measured before and after irradiation. The band gap energy has been found to decrease
with increasing fluence while the Urbach energy shows an increase. The effects of the composition of the glasses on these
parameters have been discussed in detail in this paper.
相似文献
1000.
Rishu Chaujar Ravneet Kaur Manoj Saxena Mridula Gupta R.S. Gupta 《Superlattices and Microstructures》2009
Part I of this paper dealt with the hot carrier reliability evaluation of Gate Electrode Workfunction Engineered Recessed Channel (GEWE-RC) MOSFET involving channel recession and gate electrode workfunction engineering integration onto the conventional MOSFET, using an ATLAS device simulator. It was demonstrated that with the gate stack architecture incorporated onto the GEWE-RC MOSFET and tuning of various structural design parameters such as gate length (LG), negative junction depth (NJD), substrate doping (NA), gate metal workfunction, substrate bias (VSUB), drain bias (VDS) and gate oxide permittivity (εox2), excellent hot carrier immunity can be achieved in terms of conduction band offset, reduced electron velocity, electron temperature, hot electron injected gate current and impact ionization substrate current. This paper focuses on the analog and large signal performance metrics in terms of linearity, intermodulation distortion, device efficiency and speed-to-power dissipation design parameters. Moreover, the paper also discusses the effect of gate stack architecture and various design parameters such as LG, NJD, NA, gate metal workfunction and εox2 for different substrate (VSUB) and drain to source (VDS) voltages. The work, thus, proves the effectiveness of GEWE-RC for RFICs with a higher efficiency, better linearity performance; and designing and modeling of power amplifiers. 相似文献