Characterization of Pr6O11-Ag2o-B2O3 Glasses

Silver borate glasses doped with Praseodymium of different concentration has been prepared by melt quench technique. X-ray diffraction pattern shows that there is no sharp peak it confirms the amorphous nature of the present glasses. The glass transition temperature (Tg) of this glass system have been studied using the Matac MBS-8000 Digital Signal Processing and Conventional Thermal Analysis (DTA) method. The Tg of these glasses increases with increase in concentration of Pr6O11 except at 0.2 mol%Tg value is lower. We investigate the network structure of Pr6O11-Ag2O-B2O3 glass by 11B magic angle spinning (MAS)-nuclear magnetic resonance (NMR) which shows the presence of sharp peak at around 18 ppm. Formation of B4 units is assumed to be occurring initially through the formation of oxygen bridges between [BO3/2]0 units in B2O3

Moisture susceptibility of high and low compaction dry process crumb rubber modified asphalt mixtures

The field performance of dry process crumb rubber-modified (CRM) asphalt mixtures has been reported to be inconsistent with stripping and premature cracking on the surfacing. One of the concerns is that, because achieving field compaction of CRM material is difficult due to the inherent resilient nature of the rubber particle, nonuniform field compaction may lead to a deficient bond between rubber and bitumen. To assess the influence of compaction, a series of CRM and control mixtures was produced and compacted at two levels: 4% (low, optimum laboratory compaction) and 8% (high, field experience) air void content. The long-term durability, in regard to moisture susceptibility of the mixtures, was assessed by conducting repeated moisture conditioning cycles. Mechanical properties (stiffness, fatigue, and resistance to permanent deformation) were determined in the Nottingham Asphalt Tester. Results indicated that compared with conventional mixtures, the CRM mixtures, regardless of compaction effort, are more susceptible to moisture with the degree of susceptibility primarily depending on the amount of rubber in the mixture, rather than the difference in compaction. This behavior is different from that of conventional mixtures in which, as expected, poorly compacted mixtures were found to be more susceptible to moisture than were well-compacted mixtures

Synthesis and structural studies of praseodymium doped silver borate glasses

Praseodymium doped silver borate glasses with nominal composition xPr 6O11-(25-x)Ag2O-75B2O3 (x=0, 1, 2, 3, 4, 5) were prepared by melt quench technique. XRD pattern shows that there is no sharp peak it confirms the amorphous nature of the present glasses. The glass transition temperature (Tg) of this glass system have been studied using the Matac MBS-8000 Digital Signal Processing and Conventional Thermal Analysis (DTA) method. The Tg of these glasses increases with increase in concentration of Pr6O11 except at 0.2 mol, Tg value is lower. 11B MAS-NMR shows the presence of sharp peak around 0.306 ppm. Chemical shift of these glasses decreases with mol of rare earth oxide. FTIR spectra recorded in the region of 400 to 4000 cm-1. This studies revealed that the progressive addition Ag2O and Pr6O11 leads to modification of B2O3 into BO4 groups. Raman measurements of these glasses support the proposed interpretations of the experimental results. © 2013 American Institute of Physics

Ionic conductivity of praseodymium doped silver-borate glasses

Glasses of the composition xPr6O11–(35 − x) Ag2O–65B2O3 (x = 0, 0.1–0.5 mol%) have been prepared using the melt quenching method. The ac and dc conductivity and dielectric properties of glass have been measured over a wide range of frequencies and temperatures. Experimental results indicate that the ac conductivity and the dielectric constants depend on temperature, frequency and praseodymium content. The conductivity as a function of frequency exhibited two components: dc conductivity (σdc), and ac conductivity (σac). The activation energies are estimated and discussed. The impedance plot at each temperature appeared as a semicircle passes through the origin. In all the samples, only one semicircle has been observed over the entire range of temperature studied indicating only one type of conduction mechanism

Electrical properties of praseodymium oxide doped Boro-Tellurite glasses

Glasses of the composition xPr6O11- (35-x)TeO2-65B2O3 (x=0, 0.1 to 0.5 mol %) have been prepared using the melt quenching method. The ac and dc conductivity of glass have been measured over a wide range of frequencies and temperatures. Experimental results indicate that the ac conductivity depend on temperature, frequency and Praseodymium content. The conductivity as a function of frequency exhibited two components: dc conductivity (σdc), and ac conductivity (σ ac ). The activation energies are estimated and found to be decreases with composition. The impedance plot at each temperature appeared as a semicircle passes through the origin

Host plant resistance and insect pest management in chickpea

The major pest problems in chickpea, i.e. pod borers (Helicoverpa armigera and H. punctigera), leafminer Liriomyza cicerina, black cutworm Agrotis ipsilon, aphids (Aphis craccivora), semilooper Autographa nigrisigna and bruchids (Callosobruchus spp.), and their management options (cultural, biological and chemical controls) are discussed. Low to moderate levels of resistance have been identified in the germplasm, and a few improved cultivars with resistance to pod borer and high grain yield have been developed. Germplasm accessions of the wild relatives of chickpea (Cicer bijugum, C. judaicum and C. reticulatum) can be used to increase the levels and diversify the bases of resistance to H. armigera. Efforts are also underway to utilize molecular techniques to increase the levels of resistance to pod borer. Synthetic insecticides, agronomic practices, nuclear polyhedrosis virus, entomopathogenic fungi, bacteria and natural plant products have been evaluated as components of pest management in chickpea

Thermal and radiation shielding characteristics of erbium ions doped zinc tellurite glasses

Tellurium, zinc, and erbium oxides glasses are made using the melt-quenching technique. The XRD results show that the glass samples are naturally amorphous. The TeO4 units' extended vibration are performed using FTIR. On the other hand, the TeO3 as well as Er2O3 are detected using deconvolution. When the concentration of erbium ions increases, the density and molar volume will also increase. The high value of thermal diffusivity at 0.02 and 0.03 M fractions, a large value of glass stability (greater than 100 °C), and strong thermal stability are excellent for fibre drawing. As a result, the highest linear attenuation coefficient (LAC) values are found for the sample with 5 mol% Er2O3 content, where the values drop suddenly from 0.95744 to 0.21065 cm−1 over the tested energy which ranges between 0.284 and 2.51 MeV. Among the TZEr samples, TZEr5 has the lowest half-value layer (HVL) values ranging from 0.00243 to 0.08252 cm. Thus, both LAC and HVL are considered as suitable options for radiation shielding materials