An Effective Stability Indicating RP-HPLC Method for Simultaneous Estimation of Lamivudine and Raltegravir in Bulk and Their Tablet Dosage Form

Background: In the current study, asimple and specific stability indicating RP-HPLC method was developed and validated for the determination of Lamivudine and Raltegravir in bulk drug and it tablet dosage form using an UV-detector. Good separation was achieved by isocratic ally on a Zorbax SB-Phenyl (150 × 4.6 mm, 3.5 μ, 80 A°) column, using a mobile phase composition of buffer (0.1% v/v Phosporic acid in water): Acetonitrile (40:60 v/v) at a flow rate of 1.0 mL/min. The eluted analytes detected at 260 nm wavelength. Results: Lamivudine and Raltegravir were eluted at 3.1 and 5.4 min respectively with run time 7 min. Linearity in the method was measured in the concentration range of 30 – 70 μg/mL and 60 – 140 μg/mL for Lamivudine and Raltegravirrespectively. The percentage recoveries of Lamivudine and Raltegravirwere determined to be 100.30% and 100.53%, respectively. The validation of the developed method is carried as per USFDA and ICH guidelines, and the degradants were well resolved from Raltegravir and Lamivudine peaks. The developed RP-HPLC method was highly precise, specific, sensitive, and stability indicating. Conclusion: The results of the analysis prove that thedeveloped RP-HPLC method is simple, economical and widely acceptable, which can be used in routine quality control tests in the industry.

Effective stability enhancement in ZnO-based perovskite solar cells by MACl modification

Low-temperature solution-processed ZnO has decided advantages in flexible and tandem solar cells, while its application encountered difficulties in perovskite optoelectronic devices due to the chemical instability at ZnO-perovskite interface. It...

Vertical Modes and Effective Stability of Quasi-2-Day Waves

A quasi-2-day wave is known as a convectively coupled westward inertia–gravity (WIG) wave with a shallower equivalent depth (or slower phase speed) than the dry counterpart. This study investigates the relationship between the phase speed of quasi-2-day waves and effective static stability in terms of a vertical mode perspective. By using WIG filters with different equivalent depths, different phases of the 2-day wave are identified by filtering brightness temperature data obtained from geostationary satellites. The composite time series and the vertical modes in the tropical atmosphere are calculated from reanalysis data. The large-scale dynamical fields of the composite WIG waves are explained by the superposition of the first four baroclinic modes. Phase speed of the moist vertical mode is computed by applying the Radon transform to the mode transform coefficient. Different vertical modes share a common phase speed, which is slower than its dry counterpart, implying that the wave is not dispersive. To address the question of what slows the vertical modes, the effective static stability is evaluated by defining the degree of cancellation between diabatic heating and adiabatic cooling due to the ascent. This cancellation is confirmed to be almost complete for the first baroclinic mode as expected theoretically. The effective static stability is found to be higher for a higher vertical mode, but this change over different vertical modes is not as rapid as predicted from nondispersiveness. Possible reasons for this disagreement are discussed herein.

AN INNOVATIVE METHOD DEVELOPMENT AND FORCED DEGRADATION STUDIES FOR SIMULTANEOUS ESTIMATION OF SOFOSBUVIR AND LEDIPASVIR BY RP HPLC

Objective: To develop an innovative, rapid, simple, cost effective, stability indicating reverse phase-high performance liquid chromatography (RP-HPLC) method for simultaneous estimation of ledipasvir (LP) and sofosbuvir (SB) in combination pill dosage form. Methods: The method was developed using C8 column, 250 mm x 4.6 mm, 5mm using mobile section comprising of 0.1% (v/v) orthophosphoric acid buffer at pH 2.2 and acetonitrile in the ratio of 45:55 that was pumped through the column at a flow rate of 0.8 ml/min. Temperature was maintained at 30 °C, the effluents were monitored at 260 nm with the help of usage of PDA detector. Results: The retention time of LP and SB were found to be 2.246 min and 3.502 min. The approach was found to be linear with the variety of 9-36 µg/ml and 40-240 μg/ml for LP and SB respectively, the assay of estimated compounds were found to be 99.65% and 99.73% w/v for LP and SB respectively. Conclusion: The pressured samples changed into analyzed and this proposed a technique turned into determined to be particular and stability indicating as no interfering peaks of decay compound and excipients were observed. Hence, the approach was easy and economical that may be efficiently applied for simultaneous estimation of both LP and SB in bulk and combination tablet system.

Structural stability enhancement by nonlinear geometry design and piezoelectric layers

Vibration and stability analysis of nonlinearly tapered cone beams coupled with a piezoelectric layer under compressive axial load is conducted using a new semi-theoretical model based on the Adomian decomposition method and a modified mathematical procedure. The method is applied to tapered structures with perfectly surface-bonded piezoelectric layers and general boundary conditions to analytically derive the natural frequencies and mode shape functions for flutter and buckling analysis. Furthermore, from the optimum structural design perspective, the effects of follower force, geometrical tapering ratio, boundary condition, and applied voltage on piezoelectric layers on the structural stability are thoroughly studied and presented. Simulation results show that the stability of the beam can be noticeably enhanced by the external voltage because of a pair of tensile loads locally induced by the piezoelectric effect. Moreover, for certain boundary conditions and applied voltages, the nonlinear tapered design has much greater buckling and flutter capacities than does the uniform beam. Consequently, the ideal structural design for effective stability enhancement can be reached efficiently.