872 research outputs found
Microcontroller based Bidirectional Energy Metering for Domestic User
The present energy scenario is greatly alarming the energy consumers to conserve as fossil fuels are going to deplete shortly. In this regard the renewable energy systems are really gaining momentum. Solar and wind roof top fittings are becoming popular choice for the domestic user based on their financial affordability. Solar panels generate energy to power a buildingâs electrical systems. In most cases, builders acknowledge that the solar panels installed on the roof will not always be sufficient for the buildingâs electrical needs, so the building is also connected to the main utility grid. However, sometimes during clear days the solar panels generate surplus power beyond the needs of the building. At these times, the surplus power is exported into the main utility grid. Most utility companies offer credits to buildings that export power in this manner. âBi-directional Meterâ means a consumer meter for measuring, indicating and recording quanta of electricity flowing in opposite directions (export to the licenseeâs distribution system and import by the consumer from distribution system) in Kwh including any other quantity as per the requirement. Net metering / bidirectional metering record both import and export energy values giving prime focus on utilizing self produced electricity by renewable energy sources and excess or surplus to be  sold to utilities or grid. It results into reduction of electricity bills. Solar photovoltaic system is used significantly in net metering. The design of microcontroller based bidirectional energy meter is low cost, affordable to consumer for domestic application and efficient. The current work focusses on the development of one of the type of bidirectional metering which accounts the net usage, export and the monetory exchange. The intelligent controller makes use of the measuring setup and controls all the major activities of the proposed work
Thermotropic and structural effects of poly(malic acid) on fully hydrated multilamellar DPPCâwater systems
The thermotropic and structural effects of low molecular weight poly(malic acid) (PMLA) on fully hydrated multilamellar dipalmitoylphosphatidylcholine (DPPC)-water systems were investigated using differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and freeze-fracture transmission electron microscopy (FFTEM). Systems of 20 wt% DPPC concentration and 1 and 5 wt% PMLA to lipid ratios were studied. The PMLA derivatives changed the thermal behavior of DPPC significantly and caused a drastic loss in correlation between lamellae in the three characteristic thermotropic states (i.e., in the gel, rippled gel and liquid crystalline phases). In the presence of PBS or NaCl, the perturbation was more moderate. The structural behavior on the atomic level was revealed by FTIR spectroscopy. The molecular interactions between DPPC and PMLA were simulated via modeling its measured infrared spectra, and their peculiar spectral features were interpreted. Through this interpretation, the poly(malic acid) is inferred to attach to the headgroups of the phospholipids through hydrogen bonds between the free hydroxil groups of PMLA and the phosphodiester groups of DPPC
Encapsulation of Naproxen in Lipid-Based Matrix Microspheres: Characterization and Release Kinetics
The objective of this study was to microencapsulate the anti-inflammatory drug (naproxen) to provide controlled release and minimizing or eliminating local side effect by avoiding the drug release in the upper gastrointestinal track. Naproxen was microencapsulated with lipid-like carnauba wax, hydrogenated castor oil using modified melt dispersion (modified congealable disperse phase encapsulation) technique. Effect of various formulation and process variables such as drug-lipid ratio, concentration of modifier, concentration of dispersant, stirring speed, stirring time, temperature of external phase, on evaluatory parameters such as size, entrapment efficiency, and in vitro release of naproxen were studied. The microspheres were characterized for particle size, scanning electron microscopy (SEM), FT-IR spectroscopy, drug entrapment efficiency, in vitro release studies, for in vitro release kinetics. The shape of microspheres was found to be spherical by SEM. The drug entrapment efficiency of various batches of microspheres was found to be ranging from 60 to 90 %w/w. In vitro drug release studies were carried out up to 24 h in pH 7.4 phosphate buffer showing 50-65% drug release. In vitro drug release from all the batches showed better fitting with the Korsmeyer-Peppas model, indicating the possible mechanism of drug release to be by diffusion and erosion of the lipid matrix
Uptake and transport of novel amphiphilic polyelectrolyte-insulin nanocomplexes by caco-2 cells - towards oral insulin
âThe original publication is available at www.springerlink.comâ. Copyright SpringerPurpose: The influence of polymer architecture on cellular uptake and transport across Caco-2 cells of novel amphiphilic polyelectrolyte-insulin nanocomplexes was investigated. Method: Polyallylamine (PAA) (15 kDa) was grafted with palmitoyl chains (Pa) and subsequently modified with quaternary ammonium moieties (QPa). These two amphiphilic polyelectrolytes (APs) were tagged with rhodamine and their uptake by Caco-2 cells or their polyelectrolyte complexes (PECs) with fluorescein isothiocyanate-insulin (FITC-insulin) uptake were investigated using fluorescence microscopy. The integrity of the monolayer was determined by measurement of transepithelial electrical resistance (TEER). Insulin transport through Caco-2 monolayers was determined during TEER experiments. Result: Pa and insulin were co-localised in the cell membranes while QPa complexes were found within the cytoplasm. QPa complex uptake was not affected by calcium, cytochalasin D or nocodazole. Uptake was reduced by co-incubation with sodium azide, an active transport inhibitor. Both polymers opened tight junctions reversibly where the TEER values fell by up to 35 % within 30 minutes incubation with Caco-2 cells. Insulin transport through monolayers increased when QPa was used (0.27 ngmL-1 of insulin in basal compartment) compared to Pa (0.14 ngmL-1 of insulin in basal compartment) after 2 hours. Conclusion: These APs have been shown to be taken up by Caco-2 cells and reversibly open tight cell junctions. Further work is required to optimise these formulations with a view to maximising their potential to facilitate oral delivery of insulin.Peer reviewe
In vitro Evaluation of Novel Sustained Release Microspheres of Glipizide Prepared by the Emulsion Solvent Diffusion-Evaporation Method
The objective of the current investigation is to reduce dosing frequency and improve patient compliance by designing and systematically evaluating sustained release microspheres of Glipizide. An anti-diabetic drug, Glipizide, is delivered through the microparticulate system using ethyl cellulose as the controlled release polymer. Microspheres were developed by the emulsion solvent diffusion-evaporation technique by using the modified ethanol,-dichloromethane co-solvent system. The polymer mixture of ethyl cellulose and EudragitÂź S100 was used in different ratios (1:0, 1:1, 2:3, 1:4 and 0:1) to formulate batches F1 to F5. The resulting microspheres were evaluated for particle size, densities, flow properties, morphology, recovery yield, drug content, and in vitro drug release behavior. The formulated microspheres were discrete, spherical with relatively smooth surface, and with good flow properties. Among different formulations, the fabricated microspheres of batch F3 had shown the optimum percent drug encapsulation of microspheres and the sustained release of the Glipizide for about 12 h. Release pattern of Glipizide from microspheres of batch F3 followed Korsmeyers-peppas model and zero-order release kinetic model. The value of ânâ was found to be 0.960, which indicates that the drug release was followed by anomalous (non-fickian) diffusion. The data obtained thus suggest that a microparticulate system can be successfully designed for sustained delivery of Glipizide and to improve dosage form characteristics for easy formulation
Chitosan coated alginate beads containing poly(N-isopropylacrylamide) for dual-stimuli-responsive drug release
Chitosan coated alginate beads containing poly(N-isopropylacrylamide) (PNIPAAM),
were prepared to be used as a controlled pH/temperature sensitive drug delivery
system with improved encapsulation efficiency and delayed release rate. The studied beads
were characterized by differential scanning calorimetry, scanning electron microscopy, and
Fourier transform infrared spectroscopy. Water uptake and release studies using indomethacin
as a model drug were also performed. The drug loading efficiency of the beads with the
polyelectrolyte complex coating is significantly higher (84%) than that of the uncoated ones
(74%). The equilibrium swelling of the developed materials was found to be pH- and thermoresponsive.
For all the conditions it was found that the release profile was slower for the coated
beads, indicating that the polyelectrolyte complex coating could slow down the release rate
effectively. These results suggest that the studied smart system has potential to be used as an effective pH/temperature sustainable delivery system for biomedical applications
Pressure responsive nanogel base on AlginateâCyclodextrin with enhanced apoptosis mechanism for colon cancer delivery
5âFluorouracil (5âFu) commonly use in the treatment of different kinds of cancer, but limited cellular uptake and death is still a problem. Herein, we report a simple process for the synthesis of pressureâsensitive nanogels that indicate to be appropriate in the delivery of 5âFu. The hydrogels (AlâCD) prepare by crosslinking of alginate (Al) with modified beta Cyclodextrin (ÎČâCD) as Crosslinker. Next, nanoparticles obtaine by an emulsification method. 5âFu as model drug loades into the AlâCD nanogels easily by mixing it in aqueous solution with the nanoparticles. The results revealed that the AlâCD nanogels are cytocompatible. They have also a noticeable drug encapsulation (82.1 ±5.7%) while they can release (in vitro controlled) 5âFu in conditions that imitate the intravascular pressure conditions. These nanogels can rapidly be taken up by HTâ29 cells (a colon cell line). In addition, a higher 5âFu intracellular accumulation and a significant cell death extension by apoptosis mechanism is notice when compare with free 5âFu. Accordingly, the developed nanogels can be employe as an excellent candidate to overcome the inefficiency of 5âFu in anticancer treatments and possibly can employe for further evaluation as a chemotherapical agent in applications beyond cancer. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 349â359, 2018.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143710/1/jbma36242.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143710/2/jbma36242_am.pd
Floating Drug Delivery of Nevirapine as a Gastroretentive System
A multiple-unit floating drug delivery system based on gas formation technique was developed, in order to prolong the gastric residence time and to increase the overall bioavailability of the dosage form. The floating bead formulations were prepared by dispersing nevirapine together with calcium carbonate in a mixture of sodium alginate and hydroxypropyl methylcellulose solution and then dripping the dispersion into an acidified solution of calcium chloride. Calcium alginate beads were formed, as the alginate underwent ionotropic gelation by calcium ions, and carbon dioxide developed from the reaction of carbonate salts with acid. The obtained beads were able to float due to CO2-gas formation and the gas entrapment by the polymeric membrane. The prepared beads were evaluated for percent drug loading, drug entrapment efficiency, morphology, surface topography, buoyancy, in-vitro release, and release kinetics. The formulations were optimized for different weight ratios of the gas-forming agent and sodium alginate. The beads containing higher amounts of calcium carbonate demonstrated an instantaneous, complete, and excellent floating ability over a period of 24 hours. The increased amount of the gas forming agent did not affect the time to float, but increased the drug release from the floating beads, while increasing the coating level of the gas-entrapped membrane, increased the time to float, and slightly retarded the drug release. Good floating properties and sustained drug release were achieved. Finally, these floating beads seemed to be a promising gastroretentive drug delivery system
Electrospray synthesis and properties of hierarchically structured PLGA TI PS microspheres for use as controlled release technologies
Microsphere-based controlled release technologies have been utilized for the long-term delivery of proteins, peptides and antibiotics, although their synthesis poses substantial challenges owing to formulation complexities, lack of scalability, and cost. To address these shortcomings, we used the electrospray process as a reproducible, synthesis technique to manufacture highly porous (>94%) microspheres while maintaining control over particle structure and size. Here we report a successful formulation recipe used to generate spherical poly(lactic-co-glycolic) acid (PLGA) microspheres using the electrospray (ES) coupled with a novel thermally induced phase separation (TIPS) process with a tailored Liquid Nitrogen (LN2) collection scheme. We show how size, shape and porosity of resulting microspheres can be controlled by judiciously varying electrospray processing parameters and we demonstrate examples in which the particle size (and porosity) affect release kinetics. The effect of electrospray treatment on the particles and their physicochemical properties are characterized by scanning electron microscopy, confocal Raman microscopy, thermogravimetric analysis and mercury intrusion porosimetry. The microspheres manufactured here have successfully demonstrated long-term delivery (i.e. 1 week) of an active agent, enabling sustained release of a dye with minimal physical degradation and have verified the potential of scalable electrospray technologies for an innovative TIPS-based microsphere production protocol
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