CsF–Al<SUB>2</SUB>O<SUB>3</SUB> mediated rapid condensation of phenols with aryl halides: comparative study of conventional heating vs. microwave irradiation

Biaryl ethers and thio ethers are formed in high yields by the condensation of phenols and thiophenols with electron-deficient aryl halides using CsF supported on Al2O3 under microwave irradiation in solvent-free conditions

FORMULATION DESIGN AND IN VITRO EVALUATION OF BILAYER SUSTAINED RELEASE MATRIX TABLETS OF DOXOFYLLINE

Objective: To develop bilayer matrix tablet of Doxofylline by providing a loading dose followed by the maintenance dose that suppose to enhance the therapeutic efficacy the drug for acute and sustainable asthma.Methods: Both immediate release layer and sustained release layer were prepared by wet granulation methods. Different Pre compression and post compression characterization of the tablet were carried out. Swelling studies were carried out for all the formulation. To optimise the immediate release layer, similarity (f2) and difference factor (f1) were calculated and optimised IR formulation was used for all formulations of bilayer tablet. In-vitro release studies were carried out in USP II paddle type dissolution apparatus for different formulations and release kinetic studies were carried out different kinetic model. FTIR and DSC studies were carried out for pure drug Doxofylline, IR layer and SR layer of optimised formulation to know the physical and chemical compatibility of drug and excipients. Accelerated stability studies were carried out to confirm the stability of dosage forms.Results: Pre compression and post compression parameters satisfied with pharmacopeia specifications. The formulation that contained highest percent of HPMC had highest swelling index. Formulation DBMF6 showed an initial release of 44% of drug within one hour as the loading dose and remaining drug were sustained release up to 12 h. Release kinetic followed Hixon-Crowell kinetic model with drug release mechanism quasi-fickian diffusion. From accelerated stability studies no significant changes in physicochemical properties were noticed.Conclusion: Doxofylline bilayer matrix tablets were successfully developed and can be used as an alternative to the conventional dosage form because it can be therapeutically beneficial for management of asthma.Â

Experimental study of end-capped acceptors influencing the photo-physical, electrochemical and thermal parameters of A-D-π-D-A type small molecular electron donors

385-392We have designed A-D-π-D-A type three new small molecular donor materials denoted as FD-IND, FD-DCV and FD-NBR, which have been synthesised and their photo-physical, electrochemical and thermal properties explored. The synthesised materials have fluorene as “π-spacer,” dithieonopyrrole as “Donor” (D) and various “Acceptor” (A) units are 1,3-indanedione (IND), dicyanovinylene (DCV) and N-butyl rhodanine (NBR). All these three materials have good solubility (~30 mg/mL) in most common organic solvents and have relatively broad absorption in the visible region covering the range of 300-650 nm with two primary absorption bands. The absorption bands located at shorter wavelength region are ascribed to a localized aromatic π-π* transition of the A-D-π-D-A system, while the bands at longer wavelength are mainly attributed to an ICT transition. All the compounds exhibit excellent thermal stabilities in the range of 260-373°C. Cyclic voltammetry data provided HOMO values as −5.26, −5.32 and −5.32 eV for FD-NBR, FD-DCV and FD-IND respectively. LUMO values estimated from HOMO values and optical band gap are −3.27, −3.22 and −3.37 eV for FD-NBR, FD-DCV and FD-IND respectively. Therefore, these are potential molecules for organic solar cells

Fuzzy logic controller based DC-Link Voltage Self-Balance Method for Multilevel Converter with less Number of Voltage Sensors

In many inverters, Voltage balance of dc-link capacitors is very important for applications of a cascade multilevel converter or a modular multilevel converter. In this paper, a novel diode-clamped modular multilevel converter (DCM2 C) topology is proposed and a power feedback control method is developed with fuzzy logic controller. With the developed control strategy, the proposed diode-clamped circuit becomes controllable closed loop which enables the capacitor voltages to be clamped by low power rating clamping diodes. The proposed topology and control strategy has quicker response with transient state error reduction and requires much fewer voltage sensors than the normally used traditional method of multilevel inverters as diode clamped inverters; therefore, the system performance improvement and cost reduction are expected. Based on the proposed DCM2 C, a novel N +1-level cascade multilevel topology is proposed for a cascade active power filter (CS-APF). The Proposed fuzzy logic controller is implemented to get study state response at dc voltage capacitors, therefore to get balanced load outputs. The simulation results from the CS-APF have demonstrated and verified the effectiveness of the proposed novel topology and control method

Trace metals in vegetables and fruits cultivated around the surroundings of Tummalapalle uranium mining site, Andhra Pradesh, India

AbstractVegetables (Tomato – Solanum lycopersicum, green chilli – Capsicum annum and bitter gourd – Momordica charantia) and fruits (Banana – Musa acuminata colla, papaya – Carica papaya and mosambi – Citrus limetta) from the cultivated areas around the Tummalapalle uranium mining site were analyzed for trace metals (Al, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Be, V, Co, Cd and U) using inductively coupled plasma-mass spectrometer (ICP-MS). As per the estimated data, the concentrations of trace metals in vegetables and fruits are found in the range of 47.5–7.8 mg/kg for Al, 9.7–1.0 mg/kg for Cr, 3.8–1.0 mg/kg for Mn, 75.5–13.9 mg/kg for Fe, 1.4–0.2 mg/kg for Ni, 2.3–0.8 mg/kg for Cu, 9.2–3.1 mg/kg for Zn, 0.2–1.4 mg/kg for Pb, 19.2–1.9 μg/kg for Be, 96.1–15.8 μg/kg for V, 48.2–12.9 μg/kg for Co, 46.5–2.3 μg/kg for Cd and 16.4–2.7 μg/kg for U. The trace metals observed are compared to the literature reported values. Trace elemental data were subjected to statistical analysis to examine the interrelationship between the investigated trace elements and possible source identification of the trace metal contamination in vegetable and fruits. Daily intake of trace metals through ingestion of vegetables and fruits are also calculated

VSI fed IM drive employing look-up tables with 6&12 sectors

Since the IM drives play a vital role for variable speed applications from fractional horse power to multi Mega-watt power, the control and estimation of induction motor drives constitute a vast subject. Nowadays, vector control and direct torque control (DTC) are popular for high performance drives. Even though these methods give better performance, the vector control method needs reference frame transformations and direct torque control gives large steady state ripples. To overcome these problems in the above methods mentioned, this paper presents an advanced vector control method for voltage-source inverter fed induction motors using sophisticated look-up tables. This method uses a predetermined look-up table instead of a much more time consuming pulse width modulation (PWM) procedure in conventional vector control for generating inverter gate signals. This approach gives faster torque response like in vector control methods and it also reduces ripples as in DTC method. To validate the proposed method numerical simulations have been carried out and compared with the existing algorithms. The simulation results confirm the effectiveness of the proposed method