Investigation of cytochrome P450 mediated benzo(a)pyrene hydroxylation in Aspergillus fumigatus

Microsomal fractions of Aspergillus fumigatus exhibited a reduced carbon monoxide difference spectrum with a maximum at 448 nm and a substrate-induced Type I spectrum on addition of benzo(a)pyrene. Metabolism of benzo(a)pyrene, as measured using the aryl hydrocarbon hydroxylase assay, was found to be P450-dependent and activity was observed to have a K_m of 82 μM and V_max of 33·3 pmol min⁻¹ mg⁻¹ protein. P450 productivity was investigated during growth from spore inocula and observed to be constant until the stationary phase, where the specific content declined to undetectable levels. The specific content of P450 was found to increase in higher concentrations of glucose.     

ADAPTIVE FUZZY MODEL BASED PREDICTIVE CONTROL OF AN EXOTHERMIC BATCH CHEMICAL REACTOR*

An adaptive fuzzy model based predictive control (AFMBPC) approach is presented to track the desired temperature trajectories in an exothermic batch chemical reactor. The AFMBPC incorporates an adaptive fuzzy modeling framework into a model based predictive control scheme to derive analytical controller output. This approach has the flexibility to cope with different fuzzy model structures whose choice also lead to improve the controller performance. In this approach, adaptation of fuzzy models using dynamic process information is carried out to build a predictive controller, thus eliminating the determination of a predefined fixed fuzzy model based on various sets of known input-output relations. The performance of the AFMBPC is evaluated by comparing to a fixed fuzzy model based predictive controller (FFMBPC) and a conventional PID controller. The results show the better suitability of AFMBPC for the control of highly nonlinear and time varying batch chemical reactors.     

Tensile Behavior of Ultrafine-Grained Al-4Zn-2Mg Alloy Produced by Cryorolling

An Al-4Zn-2Mg alloy was subjected to cryorolling (CR) followed by short annealing. An average grain size of ~100 nm was achieved. Cryorolled samples showed large reduction in grain size due to suppression of dynamic recovery and absence of annihilation of dislocations, as compared to room temperature rolled samples. Further, the ultrafine-grained (UFG) Al-4Zn-2Mg alloy when subjected to natural aging showed an improved strength of ~413 MPa with ductility of ~25%, as compared to ~360 MPa and 22% ductility in peak aged condition of coarse-grained alloy. However, UFG alloy in peak aging condition, exhibited a relatively strength (~375 MPa) and 24% ductility combinations than the natural aging condition. The latter is attributed to dynamic precipitation and stored energy. In the present study, it is demonstrated that simultaneous improvement in strength as well as ductility can be achieved for the Al-4Zn-2Mg alloy through CR and controlled heat treatment combinations.     

Estimation of dispenser cathode surface temperature of a practicalpotted heater cathode assembly

The heat transfer through the porous and/or infiltrated potted heater-cathode structure is simulated by a numerical model. The model includes heat conduction through a porous potting having isometric pore shape and uniform size (310 μm in alumina potting and 20 μm in tungsten cathode pellet), imperfect interface heat transfer effect and radiative boundaries. In addition to the transient study, a steady-state analysis, using the numerical model has also been done for a commercial Spectra-Mat cathode. The predicted results have been compared with the experimental measurements and are found to be in good agreement     

FUZZY MODELING AND CONTROL OF BATCH BEER FERMENTATION+

Fuzzy reasoning based modeling of heuristic control rules are employed for control of batch beer fermentation. The effect of different types of membership functions, viz., line, triangular and phi membership functions is evaluated for the fuzzy subset. Various fuzzy model based controllers are presented using two approaches, namely simple fuzzy controller of few rules (FCFR) and rigorous fuzzy controller of many rules (FCM R), and also applied for the temperature control of fermenter. Zadeh's logic and Lukasiewicz's logic are adopted for computing the compositional rule of fuzzy logic inference. The results demonstrate that the proposed fuzzy controllers show better performance than the conventional controllers. FCFR approach provides better control performance, but needs optimum tuning or selection of gains for the fuzzy input and output variables, whereas FCMR approach is preferred due to flexibility in the operation of many control rules. Further, FCMR approach is free from optimum tuning or selection of gains for the fuzzy input and output variables.     

Tailoring structure-function and pharmacokinetic properties of single-chain Fv proteins by site-specific PEGylation

The utility of single-chain Fv proteins as therapeutic agentswould be realized if the circulating lives of these minimalantigen-binding polypeptides could be both prolonged and adjustable.We have developed a general strategy for creating tailored monoPEGylatedsingle-chain antibodies. Free cysteine residues were engineeredin an anti-TNF-     

Static and Dynamic Wall Pressures in Experimental Mass Flow Hoppers

Though there are several theoretical studies on the wall pressures produced in storage hoppers, very few experimental investigations on the dynamic wall pressures are reported in the literature. Mass flow hoppers have the decisive advantage over the conventional funnel flow hoppers in that the wall pressures produced are consistent. In this paper, static and dynamic wall pressures measured by a small pressure-sensitive radiopill, in axial-symmetrical and plane-strain experimental perspex mass flow hoppers, are reported. The experimental results suggest the existence of the radial stress fields in the convergent section of the hoppers and agree with the theoretical results of Janseen, Jenike and Walker. Stop/start operation is found to have no effect on the dynamic wall pressures. Some suggestions are made which are useful for the structural design of mass flow hoppers.     

Development of nitrendipine controlled release formulations based on SLN and NLC for topical delivery: in vitro and ex vivo characterization

The aim of the investigation is to develop solid lipid nanoparticles (SLN) and nano-structured lipid carrier (NLC) as carriers for topical delivery of nitrendipine (NDP). NDP-loaded SLN and NLC were prepared by hot homogenization technique followed by sonication, and they were characterized for particle size, zeta potential, entrapment efficiency, stability, and in vitro release profiles. Also the percutaneous permeation of NDPSLN A, NDPSLN B, and NDPNLC were investigated in abdominal rat skin using modified Franz diffusion cells. The steady state flux, permeation coefficient, and lag time of NDP were estimated over 24 h and compared with that of control (NDP solution). The particle size was analyzed by photon correlation spectroscopy (PCS) using Malvern zeta sizer, which shows that the NDPSLN A, NDPSLN B, and NDPNLC were in the range of 124-300 nm during 90 days of storage at room temperature. For all the tested formulations (NDPSLN A, NDPSLN B, and NDPNLC), the entrapment efficiency was higher than 75% after 90 days of storage. The cumulative percentage of drug release at 24 h was found to be 26.21, 30.81, and 37.52 for NDPSLN A, NDPSLN B, and NDPNLC, respectively. The results obtained from in vitro release profiles also indicated the use of these lipid nanoparticles as modified release formulations for lipophilic drug over a period of 24 h. The data obtained from in vitro release from NDPSLN A, NDPSLN B, and NDPNLC were fitted to various kinetic models. High correlation was obtained in Higuchi and Weibull model. The release pattern of drug is analyzed and found to follow Weibull and Higuchi equations. The permeation profiles were obtained for all formulations: NDPSLN A, NDPSLN B, and NDPNLC. Of all the three formulations, NDPNLC provided the greatest enhancement for NDP flux (21.485 +/- 2.82 microg/h/cm(2)), which was fourfold over control (4.881 +/- 0.96 microg/h/cm(2)). The flux obtained with NDPSLN B (16.983 +/- 2.91 microg/h/cm(2)) and NDPNLC (21.485 +/- 2.82 microg/h/cm(2)) meets the required flux (16.85 microg/h/cm(2)).     

Effect of a grain refiner cum modifier on mechanical properties of Al-7Si and Al-11Si alloys

This study evaluates the influence of grain refiners/modifiers on the mechanical properties of the Al-7Si and Al-11Si alloys with an experiment of quantitative and qualitative correlations with the microstructure. Modification of Al-Si alloys with strontium additions and grain refinement with Al-Ti, Al-B and Al-T-B master alloy additions are demonstrated to be efficient on Al-Si alloys. A single master alloy with combined additions of Sr and Ti and/or B was prepared and the microstructure and mechanical properties were studied. The results show that boron rich (Al-3B-Sr and Al-1Ti-3B-Sr) master alloys are more efficient than Ti rich (Al-3Ti-Sr and Al-5Ti-1B-Sr) master alloys considering their combined grain refinement and modification effect on Al-7Si and Al-11Si alloys. However, the presence of Sr does not influence the grain refinement. Similarly, presence of grain refiner does not influence the modification of eutectic Si.