Comparative evaluation of in vitro efficacy of colesevelam hydrochloride tablets

Context: Colesevelam hydrochloride is used as an adjunct to diet and exercise to reduce elevated low-density lipoprotein (LDL) cholesterol in patients with primary hyperlipidemia as well as to improve glycemic control in patients with type 2 diabetes. This is likely to result in submission of abbreviated new drug applications (ANDA).

Objective: This study was conducted to compare the efficacy of two tablet products of colesevelam hydrochloride based on the in vitro binding of bile acid sodium salts of glycocholic acid (GC), glycochenodeoxycholic acid (GCDA) and taurodeoxycholic acid (TDCA).

Methods: Kinetic binding study was carried out with constant initial bile salt concentrations as a function of time. Equilibrium binding studies were conducted under conditions of constant incubation time and varying initial concentrations of bile acid sodium salts. The unbound concentration of bile salts was determined in the samples of these studies. Langmuir equation was utilized to calculate the binding constants k₁ and k₂.

Results: The amount of the three bile salts bound to both the products reached equilibrium at 3?h. The similarity factor (f₂) was 99.5 based on the binding profile of total bile salts to the test and reference colesevelam tablets as a function of time. The 90% confidence interval for the test to reference ratio of k₂ values were 96.06–112.07 which is within the acceptance criteria of 80–120%.

Conclusion: It is concluded from the results that the test and reference tablets of colesevelam hydrochloride showed a similar in vitro binding profile and capacity to bile salts.     

Friction Stir Welding of Low-Carbon AISI 1006 Steel: Room and High-Temperature Mechanical Properties

Friction stir welding (FSW) is an ecologically benign solid-state joining process. In this work, FSW of low-carbon AISI 1006 steel was carried out to study the microstructure and mechanical properties of the resulting joints at both room temperature (RT) and 200 °C. In the parameter space investigated here, a rotational tool speed and translation feed combination of 1200 rpm and 60 mm/min produced a defect-free weld with balanced mechanical properties and a superior Vickers microhardness profile compared to all other conditions and to base metal (BM). At faster translation feeds (100 and 150 mm/min), wormhole defects were observed in the weld microstructure and were attributed to higher strain rate experienced by the weld zone. Under tensile loading, welded material exhibited yield strength that was up to 86 and 91% of the BM at RT and 200 °C, respectively. On the other hand, tensile strength of welded material was nearly similar to that of the base metal at both RT and 200 °C. However, at both temperatures the tensile ductility of the welded joints was observed to be significantly lower than the BM. Annealing of the 1200 rpm and 60 mm/min FSW specimen resulted in tensile strength of 102% compared to base material and 47% increase in the strain at failure compared to the as-welded specimen. The Charpy impact values revealed up to 62 and 53% increase in the specific impact energy for the 1200 rpm and 60 mm/min welded joints as compared with the BM.     

Synchronous control of indirect matrix converter for three-phase power conditioner

This paper describes an average model of indirect matrix converter (IMC) with an output LC filter in stationary and rotating reference frames. The developed model is non-linear and should be linearized in order to design linear controllers. Transient performance of the IMC is compared with that of conventional inverter in classic AC/DC/AC system. In order to make the IMC applicable for power conditioner applications a synchronous controller is designed. A power conditioner acts in one or more ways to deliver a voltage of the proper level and characteristics to enable load equipment to function properly. In order to afford the power conditioner requirements the controller has two segments. One segment controls the IMC with balanced input supply voltage and the other controls the system with unbalanced input supply voltage. The system can provide balanced output voltages with slight distortion of line side currents. Theory analyses, the model validation and simulation results are presented to verify the effectiveness of this control method.     

A nanoporous adsorbent for removal of furfural from aqueous solutions

The adsorption of furfural by a surfactant-containing nanoporous material is investigated in the present study. We used cetyltrimethylammonium bromide (CTAB) as the cationic surfactant for synthesis of MCM-48. Batch adsorption studies demonstrate that the surfactant-containing MCM-48 has a significant capacity for adsorption of furfural from aqueous solution. The parameters investigated in this study included pH, contact time, agitation speed and initial furfural concentration. The adsorption process of furfural is tested with Langmuir and Freundlich isotherm models. Application of the Langmuir isotherm to the systems yielded maximum adsorption capacity of 196.1 mg/g.     

The Modeling of CO2 Removal From a Gas Mixture by 2-amino-2-methyl-1-propanol (AMP) Using the Modified Kent Eisenberg Model

In this paper, the solubility of CO₂ in AMP solution has been measured at temperature range of 293, 303, 313, and 323 K. The amine concentration ranges studied are 2.0, 2.8, and 3.4 M. A solubility apparatus was used to measure the solubility of CO₂ in AMP solution on samples of flue gases from thermal and central power plants of Esfahan Steel Company. The modified Kent Eisenberg model was used to correlate and predict the vapor-liquid equilibria of the (CO₂ + AMP + H₂O) system. The model predicted results are in good agreement with the experimental vapor-liquid equilibrium measurements.     

Bioavailability assessment of oral coenzyme Q10 formulations in dogs

The purpose of this investigation was to compare the bioavailability of three coenzyme Q10 (CoQ10) formulations in dogs using an open, randomized, multiple-dose crossover design. The formulations included a powder-filled capsule (A, control) and two soft gelatin formulations (Q-Gel as the water-miscible form of CoQ10, B and Q-Nol as the water-miscible form of ubiquinol, the reduced form of CoQ10, C). Formulations were evaluated in pairs, allowing a washout period of 14 days prior to crossing over. Blood samples were collected from each animal prior to dosing to determine the endogenous plasma CoQ10 concentrations. Serial blood samples were collected for 72 hr and plasma CoQ10 concentrations were determined by high-performance liquid chromatography. Plasma concentration-time profiles were corrected for endogenous CoQ10 concentrations. Results showed that the relative bioavailabilities of formulations B and C were approximately 3.6 and 6.2-fold higher than that of control formulation A. The AUC(microgram.hr/mL) +/- SD, Cmax(microgram/mL) +/- SD, and Tmax(hr) +/- SD for formulations A, B, and C were 1.695 +/- 0.06, 6.097 +/- 0.08, and 10.510 +/- 0.10; 0.096 +/- 0.035, 0.169 +/- 0.038, and 0.402 +/- 0.102; and 4.2 +/- 1.48, 4.1 +/- 1.57, and 4.5 +/- 0.58, respectively. While no significant differences were observed between Tmax values of the three formulations, the AUC and Cmax values for formulations B and C were significantly higher than those of the control (p < 0.05). The present investigation demonstrates that soft gelatin capsules containing water-miscible CoQ10 formulations B (Q-Gel) and C (Q-Nol) are superior to powder-filled formulations with regard to their biopharmaceutical characteristics.     

Synthesis of carbon nanotube,graphene, CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript>, and NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript> polypyrrole nanocomposites and study their microwave absorption

In this experimental work, different conductive polymer nanocomposites were synthesized using polypyrrole as conductive polymer and CoFe₂O₄, NiFe₂O₄, CNT and graphene as fillers. X-ray diffraction pattern was used to study the crystallinity of the products and it was found CoFe₂O₄, NiFe₂O₄, CNT, and graphene were successfully embedded in the polymer matrix. To further approve the synthesis of the nanocomposites, energy dispersive X-ray spectroscopy was served. Surface groups of the synthesized nanocomposites were studied by Fourier transform infrared and Raman spectroscopy. The morphology of the products was examined by scanning electron microscopy and transmission electron microscopy. It was found the fillers were successfully embedded in the polymer matrix and they were in nanometer scales. To investigate the magnetic properties and conductivity of the polymer nanocomposites, alternating gradient force magnetometer and four-point probe were used, respectively. Finally, the microwave absorption properties of the polymer nanocomposites were studied and it was found the fillers have different effects on the polymer microwave absorption value.     

Placental Growth Factor Levels in Populations with High Versus Low Risk for Cardiovascular Disease and Stressful Physiological Environments such as Microgravity: A Pilot Study

This pilot study compared placental growth factor (PIGF) levels in populations with high versus low risk for cardiovascular disease. Previous experiments from our laboratory (Sundaresan et al. 2005, 2009) revealed that the angiogenic factor PIGF was up regulated in modeled microgravity conditions in human lymphocytes leading to possible atherogenesis and pathogenesis in microgravity. Since the findings came from microgravity analog experiments, there is a strong link to its usefulness in the microgravity field as a biomarker. It is important to understand, that these findings came from both studies on expression levels of this cardiovascular marker in human lymphocytes in microgravity (in vitro microgravity analog), and a follow up gene expression study in hind limb suspended mice (in vivo microgravity analog). The relevance is enhanced because in life on earth, PIGF is an inflammatory biomarker for cardiovascular disease. Studies on the levels of PIGF would help to reduce the risk and prevention of heart failures in astronauts. If we can use this marker to predict and reduce the risk of cardiac events in astronauts and pilots, it would significantly help aerospace medicine operations. The investigations here confirmed that in a cardiovascular stressed population such as coronary artery disease (CAD) and acute coronary syndrome (ACS) patients, PIGF could be overexpressed. We desired to re-evaluate this marker in patients with cardiovascular disease in our own study. PIGF is a marker of inflammation and a predictor of short-term and long-term adverse outcome in ACS. In addition, elevated PIGF levels may be associated with increased risk for CAD.PIGF levels were determined in thirty-one patients undergoing cardiovascular catheterization for reasons other than ACS and in thirty-three low-risk asymptomatic subjects. Additional data on traditional cardiovascular risk factors for both populations were also compiled and compared. We found that PIGF levels were significantly higher in the high-risk population as compared to low-risk population. Also we were able to ascertain that PIGF levels were inversely correlated with HDL-cholesterol but directly correlated with the triglyceride levels. With further validation, PIGF may prove a useful addition to the armamentarium of noninvasive biomarkers for cardiovascular disease including a new area of stressful physiological conditions such as microgravity.     

Lanczos based preconditioner for discrete ill-posed problems

In this paper we use the Lanczos process for preconditioning discrete ill-posed problems. We show that by few steps of this process one can obtain a well qualified and efficient preconditioner. This is a general method in the sense that it is not limited only to special structured matrices and the matrix–vector multiplications can be carried out in O(n) operations. Also even in problems with structured matrices this preconditioner performs more efficiently than the circulant and Kronecker product approximate preconditioners.