An Alternative Electrochemical Approach to Detect 4-Nitrophenylhydrazine With ZnO/SnO2 Nanoparticles Decorated Glassy Carbon Electrode

The 4-NPHyd (4-nitrophenylhydrazine) electrochemical sensor assembled using wet-chemically prepared ZnO/SnO2 nanoparticle (NPs) decorated a glassy carbon electrode (GCE) with conductive Nafion binder. The synthesized NPs characterized by XPS, ESEM, EDS, and XRD analysis. The calibration of the proposed sensor obtained from current versus concentration of 4-NPHyd found linear over a concentration (0.1nM~0.01mM) of 4-NPHyd, which denoted as the dynamic range (LDR) for detection of 4-NPHyd. The 4-NPHyd sensor sensitivity calculated using the LDR slope considering the active surface of GCE (0.0316 cm2), which is equal to be 7.6930 µAµM-1cm-2, an appreciable value. The detection limit (LOD) at signal/noise (S/N=3) estimated, and outstanding lower value at 94.63±4.73 pM perceived. The analytical parameters such as reproducibility, long-term performing ability and response time are found as appreciable. Finally, the projected sensor shows exceptional performances in the detection of 4-NPHyd in environmental samples.

Diversification versus concentration analysis in specific economic activities for assessing spatial differentiation within local markets

Diversification and concentration represent essential two opposite trends in many economic phenomena. Monopoly and monopsony are the natural limits in any market's analysis and describe together the range or the amplitude of offer and demand in economics. A lot of statistical indicators or coefficients, quantifying the diversification versus concentration phenomenon (D vs. C), can reveal a market, optimal or not, full or empty, etc. The paper sheds the light on the relatively little explored concept of economic evolution from concentration to diversification across local markets, providing novel evidence on underlining the dominance of diversification process within regions. This paper has applied statistical structure variable-based methods for assessing spatial differentiation degree within housing construction economic activity in macroregion Siberia for the sample period from 2000:Q1 to 2020:Q4. We present empirical elasticities using the multivariate OLS model that summarize the diversification economic response to the increasing processes of urbanization and localization across the Siberian regions. Some final remarks offer a distinct profile of this Russian macroregion under the influence of demographical variability.

A reliable electrochemical sensor developed based on ZnO/SnO₂ nanoparticles modified glassy carbon electrode

The 4-NPHyd (4-nitrophenylhydrazine) electrochemical sensor assembled using wet-chemically prepared ZnO/SnO2 nanoparticle (NPs) decorated a glassy carbon electrode (GCE) with conductive Nafion binder. The synthesized NPs characterized by XPS, ESEM, EDS, and XRD analysis. The calibration of the proposed sensor obtained from current versus concentration of 4-NPHyd found linear over a concentration (0.1 nM ~ 0.01 mM) of 4-NPHyd, which denoted as the dynamic range (LDR) for detection of 4-NPHyd. The 4-NPHyd sensor sensitivity calculated using the LDR slope considering the active surface of GCE (0.0316 cm2), which is equal to be 7.6930 µAµM/cm2, an appreciable value. The detection limit (LOD) at signal/noise (S/N = 3) estimated, and outstanding lower value at 94.63±4.73 pM perceived. The analytical parameters such as reproducibility, long-term performing ability and response time are found as appreciable. Finally, the projected sensor shows exceptional performances in the detection of 4-NPHyd in environmental samples.

DEVELOPMENT OF ANALYTICAL METHOD AND ITS VALIDATION FOR SILDENAFIL CITRATE BY UV-SPECTROPHOTOMETRY

bulk drugs and the drug formulations and its validation. Method: The ideal conditions were established for the investigation or analysis of the drug. Results: The λmax of 293.2nmwas found for the Sildenafil citrate. Within, 8 to 60μg/ml concentration range the method complied with Beer's Law and show exceptional sensitivity with linearity. Moreover, 1.012 and 3.036 were observed limit of detection and quantification, respectively. When the absorbance versus concentration graph was plotted on the calibration curves a linear relationship was observed with the coefficient correlation of 0.99. The observed regression coefficient (Y) of the calibration curves was found to be 0.0131x- 0.0191. The method was precise and accurate with the experiential value of 2.0325± 0.044. The stability of the test solution was up to 48 hours. Conclusion: The proposed analytical method is simple, economical and experimentally less time-consuming. Therefore, it will be appropriate for Sildenafil citrate analysis of pharmaceutical formulations in bulk.

The Equation for Rise in Superheat by Adding Electrolyte

For many liquids, the limit of superheat is 0.89 Tc, where Tc = temperature Kelvin at critical point. The rise in the limit of superheat by addition of polymer has a formula, B’, derived by Jennings, and this paper makes use of a pattern to predict the formula for rise in superheat by adding electrolyte, B. The equations for boiling point elevation by addition of electrolyte, A, and polymer, A’, are known, so we make use of a proportion and solve for the unknown, B, thus: B= (A/A’) x B’ to get the equation. A, A’ and B’ all have the phase change temperature squared at 1 atmosphere pressure in the numerator times the ratio of the molecular weight solvent divided by the product of the density of solvent times molecular weight solute in the expression that equals lim c--->0 (dT/dc) giving the limiting slope of rise in temperature versus concentration solute. The van’t Hoff factor is included. The proposed formula B for RISE IN SUPERHEAT BY ADDITION OF ELECTROLYTE is: lim c--->0 (dT/dc)s, electrolyte = (3 k MW1 Ts 2 i) / (ρ1 σ1 a MW2(e)).