In Vitro Comparative Degradation Study Between Two Brands Of Amytriptyline Hydrochloride Tablet Using UV Spectrophotometer

Abstract The objective of this study was to develop the degradation studies of different brands of amytriptyline hydrochloride in market. Forced degradation is a process that involves degradation of drug products and drug substances at conditions more severe than accelerated conditions and thus generates degradation products that can be studied to determine the stability of the molecule. Amitriptyline (AMT) belongs to tricyclic dibenzocycloheptadiene derivatives. It acts primarily as a serotonin-norepinephrine reuptake inhibitor, used for the treatment of several psychiatric disorders. This drug was subjected to different stress conditions as per International Conference on Harmonization guidelines (ICH). An ultraviolet UV spectroscopic method was developed for analysis of the drug in the presence of the degradation products. Distilled water was used as a solvents. The amount of degraded drugs was calculated by taking the absorbance at 222 nm. According to the assay limit of USP specified that the content should not be less than 95% and not more than 105% of labelled amount. All brands were degraded on basic pH and on acidic pH. In addition to heat exposure all brands were also degraded. It was concluded that all brands degraded from ranges for all the stresses applied for degradation studies

Predictive model of blood transfusion during CABG surgery in Pakistan

OBJECTIVE: To determine predictors of need for transfusion of blood and blood products and create a clinical predictive model to reduce indiscriminate use of blood products during surgery. METHOD: We conducted a retrospective chart review of 485 patients who underwent coronary artery bypass surgery from January 2004 to December 2004 at a Tertiary Care Hospital in Karachi, Pakistan. Independent predictors associated with transfusion were identified and a clinical prediction model developed. RESULTS: The transfusion rate was 37.1%. A predictive model was created based on the presence of pulmonary disease, diabetes mellitus, low ejection fraction and recent/ongoing myocardial infarction. CONCLUSION: The study identifies some predictors of need for blood transfusion in patients undergoing Coronary Artery Bypass Grafting. However, prospective studies with a larger sample of patients are needed to determine other predictors and their applicability in patient selection across institutions

Second order wave generation technique in the laboratory

Correct generation of the primary waves and the reproduction of the group-induced second order low and high frequency waves have been considered essential for physical model test in the laboratory to understand the effects of the wave-action phenomena on, for instance, offshore structures, mooring system, LNG, other floating vessels, harbor resonance, etc.. When natural waves are reproduced, the primary waves and their locked bounded waves are generated along with some unwanted free waves. Those free waves are evidently generated and propagate towards the test model and reflect from the boundaries. The free waves, having the same frequency of the bounded wave are reproduced due to mismatch of the boundary conditions at the wave paddle. Another two types of free waves are due to the wave paddle displacement and the local disturbances. These unwanted free waves can be eliminated by means of compensating free waves imposed on the system by second-order paddle motion. The control signal for this motion has to be introduced along with the primary waves. An extensive experimental works are carried out in the Offshore Engineering wave Basin (OEB) at the Institute of Ocean Technology (IOT), NRC to investigate the quality and the characteristics of the generated primary waves and their locked bounded waves after when the unwanted free waves are eliminated. Two different water depths are used within the shallow water limit. The obtained results are also compared with the numerical predictions.Peer reviewed: YesNRC publication: Ye

Deformation of the Wave Field Interacting With Offshore Platforms: Comparison Between the Corresponding Results From a Numerical Model and a Wave Tank

In the present research, a 3D dispersive numerical model has been developed and utilized to study the modification of the wave field in the presence of offshore structure. The Alternating Direction Implicit (ADI) algorithm has been employed for the solution of the governing equations. Relevant experiments are carried out in the Offshore Engineering Basin (OEB) of National Research Council (NRC) Canada. OEB is a 3D heavy duty 75m 7 32m 7 2.8m test facility equipped with modern data acquisition and tracking devices to record experimental data. Total 10 wave probes are deployed to measure the data at different locations in the Basin. Later the numerical results are compared with the experimental results. The comparisons of the numerical results show great agreement with the experimental results.Peer reviewed: YesNRC publication: Ye

Second Order Wave Generation in the OEB II

When first-order natural waves are reproduced in the laboratory using the first order wave generation technique, the primary waves and their locked bounded waves are generated along with some unwanted free waves. Those free waves are evidently generated and propagate towards the test model and reflect from the boundaries. The free waves, having the same frequency of the bounded wave are reproduced, as the boundary conditions of the wave paddle are not properly satisfied up to second-order. The other two types of free waves are due to the wave paddle displacement and local disturbances. These so-called free waves cause an amplification of low frequency and/or high frequency wave phenomena, such as harbour resonance and oscillations of moored ships and, propagation and breaking of waves on floating or fixed structures that may exert huge hydrodynamic loads. The so-called second order wave generation technique could eliminate these alleged free waves. In this experiment second order wave generation technique is successfully used to reproduce the correct bounded waves along with elimination of the unwanted free waves from the wave profiles. This experiment is implemented by means of compensating free waves imposed on the system by second-order paddle motion. The control signal for this motion has to be introduced along with the primary waves.NRC publication: Ye

Transformation of mono- and multi-chromatic water waves propagating from a Quasi-deepwater to a shallow water region.

A vertically integrated 3D numerical model that uses the concept of depth average velocity distribution with enhanced dispersion characteristics investigates the propagation and transformation of mono- and multi-chromatic waves from a quasi-deep region to shallow water region. A finite difference method has been employed for the numerical computation that follows ADI (Alternating Direction Implicit) algorithm. The local sea bottom is uneven and turns into a moderately shallow water due to presence of a ridge-like bottom near the coast. The bottom configuration is from a location off Nova Scotia coast in Canada. Detail results and discussions are presented.Peer reviewed: NoNRC publication: Ye

OMAE2009-80104 TRANSFORMATION OF MONO-AND MULTI-CHROMATIC WATER WAVES PROPAGATING FROM A QUASI-DEEPWATER TO A SHALLOW WATER REGION

ABSTRACT A vertically integrated 3D numerical model that uses the concept of depth average velocity distribution with enhanced dispersion characteristics investigates the propagation and transformation of mono-and multi-chromatic waves from a quasi-deep region to shallow water region. A finite difference method has been employed for the numerical computation that follows ADI (Alternating Direction Implicit) algorithm. The local sea bottom is uneven and turns into a moderately shallow water due to presence of a ridge-like bottom near the coast. The bottom configuration is from a location off Nova Scotia coast in Canada. Detail results and discussions are presented

Effects or Bottom Configurations on Ware-Current Field

An attempt is taken to apprehend the coexistence phenomenon of wave, current and submerged structures numerically. The governing equations of this model are derived by vertical integration of continuity equation and the equation of motion for gradually varying impermeable sea bottom and discretized with a semi-implicit technique, such that, at every time step, the resulted tridiagonal matrix can be solved by the method of double sweep. As an application, this model is applied to study the characteristics of the interacted waves and currents over submerged mounds of parabolic and trapezoidal cross sections. Results show that the change of wave characteristics for both cases are significant over the mounds

Loading due to interaction of waves with colinear and oblique currents

A study on the loading of an oblique surface wave and a surface current field on a fixed vertical slender cylinder in a 3D flow frame is illustrated in the present paper. The three dimensional expressions describing the characteristics of the combined wave-current field in terms of mass, momentum and energy flux conservation equations are formulated. The parameters before the interaction of the oblique wave-free uniform current and current-free wave are used to formulate the kinematics of the flow field. These expressions are also employed to formulate and calculate the loads imparted by the wave-current combined flow on a bottom mounted slender vertical cylinder. In the present study two different situations are assumed where current is uniform over depth and also acting over a layer of fluid that extends from the free surface to a specified finite depth. In this paper we extend the approach considered in Zaman and Baddour (2004) for the wave-current analysis. Morison et al. (1950) equation is deployed for the load computations in all cases. The above models are utilized to compute the loads and moments on a slender cylinder for a wave with varying range of incidence current field.Peer reviewed: YesNRC publication: Ye