A 3-year field trial of sugarcane, comprising 11 treatment combinations of different organic manures with and without Gluconacetobacter diazotrophicus (Gd), NPK and an absolute control, on an inceptisol was conducted to assess the effect of these treatments on sugarcane total and economic yield, the benefit:cost ratio, nutrient balance and soil quality in a sugarcane plant-ratoon system. The highest cane yield (78.6 t ha À1 ) was recorded in the plant crop given vermicompost + Gd, whereas ratoon yields (first and second) were highest (80.8 and 74.9 t/ha À1 , respectively) with sulphitation press mud cake (SPMC) + Gd. In both plant and ratoon crops, a number of different organic manures produced the highest cane yield that was also statistically similar to those obtained with using the recommended NPK levels (76.1, 78.2 and 71.7 t/ha for plant crop and subsequent two ratoons, respectively). The highest benefit:cost (B:C) ratio in the plant and two ratoon crops (1.28, 2.36, 2.03 respectively) were obtained with the addition of SPMC + Gd. The nutrient balance for NPK in the soil was highest in the SPMC + Gd treatment. The highest increase in organic C (94%) and total N (87%), in comparison to the initial level, and soil microbial biomass C (113%) and soil microbial biomass N (229%), in comparison to the control treatment, was recorded with the addition of SPMC + Gd. The maximum decrease in soil bulk density (BD) (12%) with an increase in soil aggregate (17%) and water infiltration rate (35%) was obtained with the addition of SPMC. Overall, the sugarcane crop responded well to different organic manures in a multiple ratooning system with a better economic output and improved soil quality. Strategic planning in terms of an integrated application of these manures with inorganic chemicals will not only sustain our soils but will also be beneficial for our farmers in terms of reducing their dependence and expenditure on chemical fertilizers.
Specific heat ratio (γ), pseudo-Grüneisen parameter (Γ ), heat capacity (C p ) and effective Debye temperature (θ D ) for binary system of tetrahydrofuran with o-cresol and methanol respectively, were calculated using the experimentally measured densities, velocities and viscosities of the pure liquids and their mixtures over the whole composition range and at T = 293, 303, 313 K. The excess pseudo-Grüneisen parameter (Γ E ), excess molar isentropic compressibility (K E s ) and excess acoustic impedance (Z E ) were also calculated. The excess deviation functions have been correlated using Redlich-Kister polynomial equation. The observed values of the excess parameters plotted against the mole fraction of tetrahydrofuran have been explained on the basis of intermolecular interaction suggesting strong interaction in tetrahydrofuran + o-cresol than in tetrahydrofuran + methanol. Partial molar isentropic compressibility at infinite dilution and their excess values were calculated for each component. Sanchez theory, Goldsach-Sarvas volume fraction statistics, Sudgen's relation, Flory-Patterson-Rastogi and Brock and Bird model were used with the Aurebach relation to compute theoretically the values of ultrasonic velocities at varying temperatures. The velocity deviations were estimated in terms of average percentage deviations. Internal pressure for both the systems were calculated theoretically and discussed on the basis of relative applicability of the models in theoretical estimations. The isothermal compressibility (k T ), for these binary mixtures were theoretically evaluated by using the Flory statistical theory and five hard sphere models and compared with the experimental values.
Production of exemplary crowns and fixed partial dentures depends upon the usage of impression material and its technique of usage that accurately reproduces prepared teeth and their relationship to the adjacent oral structure.
Aim
To evaluate the linear dimensional accuracy of the elastomeric impressions using various impression techniques using different combinations of viscosities of impression materials.
Materials and methods
Crown preparation was done in a dentulous acrylic resin denture base model with six natural teeth embedded into it was made to represent the dentulous maxillary arch. A total of 55 impressions were obtained and poured in die stone using various impression techniques with different combinations of viscosities of impression materials.
Results
Among the six techniques used, the heavy body light body two-step technique using custom tray showed the least distortion which was closely followed by the putty wash two-step technique with 2 mm spacer using stock tray.
Conclusion
The study revealed that the heavy body light body two-step technique with custom tray provided the best results.
Clinical significance
Dimensional accuracy of impressions is very much required for precisely fitting of prosthesis. This study may be helpfull to select the technique and materials as per clinical requirement of accuracy of impressions.
How to cite this article
Singh K, Sahoo S, Prasad KD, Goel M, Singh A. Effect of Different Impression Techniques on the Dimensional Accuracy of Impressions using Various Elastomeric Impression Materials: An in vitro Study. J Contemp Dent Pract 2012;13(1):98-106.
The refractive indices, densities and ultrasonic velocities of binary liquid mixtures of tetrahydrofuran (THF) with methanol and o-cresol over the entire composition range have been measured at 293, 303 and 313 K. Refractive index, density and ultrasonic velocity data have been used to evaluate the molar refraction deviation ∆R m , deviation in ultrasonic velocity ∆u, excess internal pressure π These results suggest that specific strong interactions are taking place in THF + o-cresol mixture while dispersive forces seem to be responsible for behaviour of THF + methanol mixture. Further, experimental refractive index and density data of these mixtures were also used to test the validity of the empirical/semi-empirical relations and models for refractive index and density, respectively.
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