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51.
Structural and micro structural studies of PbO-doped SnO2 sensor for detection of methanol,propanol and acetone 下载免费PDF全文
In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer (XRD) and scanning electron microscope (SEM). Initially, SnO2 powder was derived using sol-gel process and was subsequently doped with PbO and ground up to nanosized particles. A suitable gas sensor structure was fabricated on 1′′×1′′ alumina substrate using thick film technology. The necessary paste for screen printing was also developed. SEM results showed sol-gel derived powder gets more agglomerated in the thick film form. The sensitivity of the sensor has been investigated at different temperatures (150 ?C?350 ?C) upon exposure to methanol, propanol and acetone, yielding a maximum at 250 ?C for acetone with 1 wt% PbO-doping while at 350 ?C for propanol with 3 wt% PbO-doping of the sensor. The reduction of particle size to nanometers (validated through XRD) leads to a dramatic improvement in sensitivity of sensors for the chosen organic vapors. The results also correlate well with the microstructural properties of the material and the dopant. 相似文献
52.
53.
A two-parametric nonstandard (Jordanian) deformation of the Lie algebra gl(2) is constructed and then, exploited to obtain a new, triangular R-matrix solution of the coloured Yang–Baxter equation. The corresponding coloured quantum group is presented explicitly. 相似文献
54.
The accumulation of plastic strain over a number of cycles of heating and cooling of the outer surface of a loaded thick-walled circular cylinder is computed. Two types of loadings are considered, viz. pure axial torsion and a combination of torsion and tension. The cylinder material is taken to be isotropic and linear strain-hardening; its yield stress reduces with temperature and with the number of thermal cycles completed. This cyclic softening is shown to produce an incremental collapse or ratcheting behaviour in contrast to the alternating plasticity which occurs when the yield stress on first loading is maintained. 相似文献
55.
Sagar E. Shirsath B.G. Toksha S.M. Patange Ganesh S. Jangam 《Journal of Physics and Chemistry of Solids》2010,71(12):1669-1675
The ferrite samples of a chemical formula Ni0.5−xMnxZn0.5Fe2O4 (where x=0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were synthesized by sol-gel auto-combustion method. The synthesized samples were annealed at 600 °C for 4 h. An analysis of X-ray diffraction patterns reveals the formation of single phase cubic spinel structure. The lattice parameter increases linearly with increase in Mn content x. An initial increase followed by a subsequent decrease in saturation magnetization with increase in Mn content is observed showing inverse trend of coercivity (Hc). Curie temperature decreases with increase in Mn content x. The initial permeability is observed to increase with increase in Mn content up to x=0.3 followed by a decrease, the maximum value being 362. Possible explanation for the observed structural, magnetic, and changes of permeability behavior with various Mn content are discussed. 相似文献
56.
Preeti S. Mishra Jignasa N. Solanki Z. V. P. Murthy 《Crystal Research and Technology》2013,48(11):969-976
In the present paper, suitable TiO2 nanoparticles are successfully synthesized by sol‐gel method, in order to utilize the freshly prepared TiO2 nanoparticles for proton exchange membrane (PEM) preparation. Titanium tetrachloride (TiCl4) is used as precursor and ethanol as a solvent. The optimum and suitable TiO2 nanoparticles were obtained by varying gelatinisation time (4–120 h), concentration of precursor (TiCl4) in ethanol (2–15 vol%), and reaction temperature (15–35 °C). The morphology, size and purity of the nanoparticles are investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and X‐ray diffraction (XRD). Optimum results were found at 4 h of gelatinisation time, 10% precursor concentration and 25 °C temperature for preparation of TiO2 nanoparticles. Thus prepared nanoparticles are found to be suitable for preparation of nanocomposite PEM, and consequently the prepared PEM indicates enhanced properties, such as, higher thermal stability (high glass transition temperature of 184.1 °C), excellent proton conductivity (0.0822 S cm−1 at room temperature) and low methanol permeability (1.11 × 10−9 cm2 s−1). 相似文献
57.
Preeti Mohindru 《代数通讯》2013,41(9):3818-3841
Drew, Johnson, and Loewy conjectured that for n ≥ 4, the CP-rank of every n × n completely positive real matrix is at most [n2/4]. While this conjecture has recently been disproved for completely positive real matrices, we show that this conjecture is true for n × n completely positive matrices over certain special types of inclines. In addition, we prove an incline version of Markham's theorems which gives sufficient conditions for completely positive matrices over special inclines to have triangular factorizations. 相似文献
58.
ABSTRACTNanocrystalline Ni0.4Cu0.3Zn0.3Fe2O4 ferrites doped with TiO2 (0–10?wt %) were prepared by the sol-gel method. Elastic properties of synthesized samples were studied with the help of ultrasonic pulse transmission method. The elastic constants initially increase with an increase in TiO2 up to 1?wt % and then decline. LCR-Q meter was used to study the dielectric properties within 50?Hz to 5?MHz range of the frequency. The dielectric constant (?′) and dielectric loss tangents were decreased continuously with increased frequency for all the selected samples at room temperature revealing normal dielectric behavior of ferrites. Also, the AC conductivity was increased with an increase in the frequency for all the selected samples. Cole-Cole plots were obtained for all investigated samples and showed single semicircle which indicates that the electrical conduction process appears only due to grain boundaries. 相似文献
59.
Retraction: Gairola, SP, Gairola, P, Shah, SK, Gupta, R. EMI shielding effectiveness of expanded graphite and reduced graphene oxide. J. Chin. Chem. Soc. 2018. https://doi.org/10.1002/jccs.201800189 . The above article, published online on 1 October 2018 in Wiley Online Library ( https://onlinelibrary.wiley.com ), has been retracted by agreement between the corresponding author, the journal's Editor‐in‐Chief, Dr. Yu‐Tai Tao, the Chemical Society Located in Taipei, and Wiley‐VCH Verlag GmbH & Co. KGaA. The retraction has been agreed due to several images across Figures 1, 2 and 3 within the article having been duplicated from other publications. The corresponding author apologizes for the inconvenience caused. 相似文献
60.
One‐pot Synthesis of Fully Substituted Pyrimidines Using Amidine and Ketene Dithioacetals as Synthons and Their Antimicrobial Activity 下载免费PDF全文
Sagar P. Gami Haresh G. Kathrotiya Yogesh T. Naliapara 《Journal of heterocyclic chemistry》2015,52(3):751-755
A simple, convenient, and efficient one‐pot synthesis of fully substituted pyrimidines was developed by cyclocondensation of α‐oxo ketene dithioacetals with amidine in the presence of potassium carbonate in good yield. Structures of all the newly synthesized compounds were elucidated by elemental analysis and spectral analysis. All the newly synthesized compounds are tested toward different microorganisms. 相似文献