Showing papers by "Gaurav Sharma published in 2010"

On the complexity of scheduling in wireless networks

Abstract: We consider the problem of throughput-optimal scheduling in wireless networks subject to interference constraints. We model the interference using a family of K-hop interference models, under which no two links within a K-hop distance can successfully transmit at the same time. For a given K, we can obtain a throughput-optimal scheduling policy by solving the well-known maximum weighted matching problem. We show that for K > 1, the resulting problems are NP-Hard that cannot be approximated within a factor that grows polynomially with the number of nodes. Interestingly, for geometric unit-disk graphs that can be used to describe a wide range of wireless networks, the problems admit polynomial time approximation schemes within a factor arbitrarily close to 1. In these network settings, we also show that a simple greedy algorithm can provide a 49-approximation, and the maximal matching scheduling policy, which can be easily implemented in a distributed fashion, achieves a guaranteed fraction of the capacity region for "all K." The geometric constraints are crucial to obtain these throughput guarantees. These results are encouraging as they suggest that one can develop low-complexity distributed algorithms to achieve near-optimal throughput for a wide range of wireless networks.

Joint congestion control and distributed scheduling for throughput guarantees in wireless networks

Abstract: We consider the problem of throughput-optimal cross-layer design of wireless networks. We propose a joint congestion control and scheduling algorithm that achieves a fraction 1/dI(G) of the capacity region, where dI(G) depends on certain structural properties of the underlying connectivity graph G of the wireless network, and also on the type of interference constraints. For a wide range of wireless networks, dI(G) can be upper bounded by a constant, independent of the number of nodes in the network. The scheduling element of our algorithm is the maximal scheduling policy. Although this scheduling policy has been considered in several previous works, the challenges underlying its practical implementation in a fully distributed manner while accounting for necessary message exchanges have not been addressed in the literature. In this article, we propose two algorithms for the distributed implementation of the maximal scheduling policy accounting for message exchanges, and analytically show that they still can achieve the performance guarantee under the 1-hop and 2-hop interference models. We also evaluate the performance of our cross-layer solutions in more realistic network settings with imperfect synchronization under the Signal-to-Interference-Plus-Noise Ratio (SINR) interference model, and compare with the standard layered approaches such as TCP over IEEE 802.11b DCF networks.

Detecting Content Adaptive Scaling of Images for Forensic Applications

Abstract: Content-aware resizing methods have recently been developed, among which, seam-carving has achieved the most widespread use. Seam-carving's versatility enables deliberate object removal and benign image resizing, in which perceptually important content is preserved. Both types of modifications compromise the utility and validity of the modified images as evidence in legal and journalistic applications. It is therefore desirable that image forensic techniques detect the presence of seam-carving. In this paper we address detection of seam-carving for forensic purposes. As in other forensic applications, we pose the problem of seam-carving detection as the problem of classifying a test image in either of two classes: a) seam-carved or b) non-seam-carved. We adopt a pattern recognition approach in which a set of features is extracted from the test image and then a Support Vector Machine based classifier, trained over a set of images, is utilized to estimate which of the two classes the test image lies in. Based on our study of the seam-carving algorithm, we propose a set of intuitively motivated features for the detection of seam-carving. Our methodology for detection of seam-carving is then evaluated over a test database of images. We demonstrate that the proposed method provides the capability for detecting seam-carving with high accuracy. For images which have been reduced 30% by benign seam-carving, our method provides a classification accuracy of 91%.

Orientation Modulation for Data Hiding in Clustered-Dot Halftone Prints

Abstract: We present a new framework for data hiding in images printed with clustered dot halftones. Our application scenario, like other hardcopy embedding methods, encounters fundamental challenges due to extreme bilevel quantization inherent in halftoning, the stringent requirements of image fidelity, and other unavoidable printing and scanning distortions. To overcome these challenges, while still allowing for automated extraction of the embedded data and a high embedding capacity, we propose a number of innovations. First, we perform the embedding jointly with the halftoning by employing an analytical halftone threshold function that allows steering of the halftone spot orientation within each halftone cell based upon embedded data. In this process, image fidelity is emphasized and, if necessary, the capability to recover individual data values is sacrificed resulting in unavoidable erasures and errors. To overcome these and other sources of errors, we propose a suitable data detection and error control methodology based upon a statistical representation for the print-scan channel that effectively models the channel dependence upon the cover image gray-level. To combat the geometric distortion inherent in the print-scan process, we exploit the periodic halftone structure to recover from global scaling and rotation and propose a novel decision directed synchronization technique that counters locally varying printing distortion. Experimental results demonstrate the power of the proposed framework: we achieve high operational rates while preserving halftone image quality.

Recent trends in pulsatile drug delivery systems - A review

Abstract: The purpose of writing this review on pulsatile drug delivery systems (PDDS) is to compile the recent literatures with special focus on the different types and approaches involved in the development of the formulation PDDS are gaining importance in the field of pharmaceutical technology as these systems deliver the right dose at specific time at a specific site Some of the disease conditions wherein PDDS are promising include duodenal ulcer, cardiovascular diseases, arthritis, asthma, diabetes, neurological disorder, cancer, hypertension and hypercholesterolemia PDDS can be classified into time controlled systems wherein the drug release is controlled primarily by the delivery system, stimuli induced PDDS in which release is controlled by the stimuli, such as the pH or enzymes present in the intestinal tract or enzymes present in the drug delivery system and externally regulated system where release is programmed by external stimuli like magnetism, ultrasound, electrical effect and irradiation This review also summarizes some current PDDS already available in the market These systems are useful to several problems encountered during the development of a pharmaceutical dosage form Keywords: Pulsatile drug delivery systems; Circadian rhythm; Single unit, Multiple units, Pulsatile release pulsincap

Camera Scheduling and Energy Allocation for Lifetime Maximization in User-Centric Visual Sensor Networks

Abstract: We explore camera scheduling and energy allocation strategies for lifetime optimization in image sensor networks. For the application scenarios that we consider, visual coverage over a monitored region is obtained by deploying wireless, battery-powered image sensors. Each sensor camera provides coverage over a part of the monitored region and a central processor coordinates the sensors in order to gather required visual data. For the purpose of maximizing the network operational lifetime, we consider two problems in this setting: a) camera scheduling, i.e., the selection, among available possibilities, of a set of cameras providing the desired coverage at each time instance, and b) energy allocation, i.e., the distribution of total available energy between the camera sensor nodes. We model the network lifetime as a stochastic random variable that depends upon the coverage geometry for the sensors and the distribution of data requests over the monitored region, two key characteristics that distinguish our problem from other wireless sensor network applications. By suitably abstracting this model of network lifetime and utilizing asymptotic analysis, we propose lifetime-maximizing camera scheduling and energy allocation strategies. The effectiveness of the proposed camera scheduling and energy allocation strategies is validated by simulations.

Some Anti-Diabetic Plants of Southern Assam

Abstract: Survey to explore anti-diabetes plants of Southern Assam was undertaken during the period of 2006-2008 and altogether 58 anti-diabetes plants have been recorded on the basis of information collected from medicine man. Of the collected plants dicotyledons showed higher percentage of use as compared to monocot and pteridophytes . Among the plant parts used, leaf is highly used followed by bark, root, whole plant, fruit, seeds, roots, flowers, rhizome, sap and nuts.

Novel Low Band Gap Phenylenevinylene Copolymer with BF2−Azopyrrole Complex Units: Synthesis and Use for Efficient Bulk Heterojunction Solar Cells

Abstract: An alternating phenylenevinylene copolymer (P) was synthesized by Heck coupling of 2,5-bis[2-(4-bromophenyl)diazeny]-1H-pyrrole with 1,4-divinyl-2,5-bis(hexyloxy)-benzene. The subsequent reaction of P with boron trifluoride diethyl etherate afforded the corresponding BF2−azopyrrole complex (PB) which was used for bulk heterojunction solar cells. A thin film of PB showed a broad absorption band with a long-wave absorption maximum at 511 nm and an optical band gap of 1.63 eV. We have used a solvent mixture consisting of THF with various contents of acetone, in order to prepare the PB:PCBM blend films for polymer bulk heterojunction (BHJ) photovoltaic (PV) devices. Since the vapor pressure of the solvent mixture is lower compared to neat THF, the blend films dried slowly and nanoparticles of PB are formed, as indicated by the XRD pattern. The correlation of PB nanoparticles with PV properties of the PB:PCBM BHJ devices was investigated. It was found that the optical absorption and hole transport in the resul...

Swift: Scalable weighted iterative sampling for flow cytometry clustering

Abstract: Flow cytometry (FC) is a powerful technology for rapid multivariate analysis and functional discrimination of cells. Current FC platforms generate large, high-dimensional datasets which pose a significant challenge for traditional manual bivariate analysis. Automated multivariate clustering, though highly desirable, is also stymied by the critical requirement of identifying rare populations that form rather small clusters, in addition to the computational challenges posed by the large size and dimensionality of the datasets. In this paper, we address these twin challenges by developing a two-stage scalable multivariate parametric clustering algorithm. In the first stage, we model the data as a mixture of Gaussians and use an iterative weighted sampling technique to estimate the mixture components successively in order of decreasing size. In the second stage, we apply a graph-based hierarchical merging technique to combine Gaussian components with significant overlaps into the final number of desired clusters. The resulting algorithm offers a reduction in complexity over conventional mixture modeling while simultaneously allowing for better detection of small populations. We demonstrate the effectiveness of our method both on simulated data and actual flow cytometry datasets.

In - Vivo Assessment of Enhanced Bioavailability of Metronidazole with Piperine in Rabbits

Abstract: Piperine was established as being able to increase the bioavailability of a large number of drugs. So an attempt has been taken to study changes in bioavailability of metronidazole in presence of piperine in rabbits. Male New Zealand white rabbits (2.0-2.5 kg body weight) used for pharmacokinetic and bioavailability study. Three groups of rabbits were formed from which one group was considered as control and received only vehicle (distilled water) orally. Remaining two groups were treated with metronidazole and combination of metronidazole and piperine respectively. About one ml of blood sample was collected at the different time intervals and analyzed spectrophotometrically by HPLC. A Cmax value of 3,805.89 ± 233.8 ng/ml was obtained with metronidazole alone (20 mg/ kg) and 6,007.07 ± 348.8 ng/ml was obtained with a combination of metronidazole (20 mg/kg) and piperine (10 mg/kg). This represents an increase of 57% in peak plasma levels of metronidazole. Reduction in total clearance from 0.06 ± 0.02 to 0.04 ± 0.02 ml/h, and a volume of distribution from 2.69 ± 0.23 to 1.48 ± 0.65 L resulted in a net increase of 88.53% in AUC (45,073.75 ± 713.7 to 84,980.98 ± 345.6 ng * h/ml). So we can conclude that bioavailability of metronidazole was significantly enhance in the

Synthesis of a Low-Band-Gap Small Molecule Based on Acenaphthoquinoxaline for Efficient Bulk Heterojunction Solar Cells

Abstract: A novel small molecule (SM) with a low-band-gap based on acenaphthoquinoxaline was synthesized and characterized It was soluble in polar solvents such as N,N-dimethylformamide and dimethylacetamide SM showed broad absorption curves in both solution and thin films with a long-wavelength maximum at 642 nm The thin film absorption onset was located at 783 nm, which corresponds to an optical band gap of 159 eV SM was blended with PCBM to study the donor-acceptor interactions in the blended film morphology and the photovoltaic response of the bulkheterojunction(BHJ) devicesThecyclicvoltammetrymeasurementsofthematerialsrevealedthattheHOMOand LUMO levels of SM are well aligned with those of PCBM, allowing efficient photoinduced charge transfer and suitable open circuit voltage, leading to overall power conversion efficiencies (PCEs) of approximately 221 and 323% for devices with the as-cast and thermally annealed blended layer, respectively The increase in the PCE with the thermally annealed blendis mainly attributed tothe improvement inincident photon to current efficiency(IPCE) and short circuit photocurrent (J sc) Thermal annealing leads to an increase in both the crystallinity of the blend and hole mobility, which improves the PCE

Per-separation clustered-dot color halftone watermarks: separation estimation based on spatial frequency content

Abstract: A framework for clustered-dot color halftone watermarking is considered, wherein watermark patterns are embedded in individ- ual colorant halftones prior to printing and embedded watermarks are detected from scans of the printed images after obtaining esti- mates of the individual halftone separations. The principal challenge in this methodology arises in the watermark detection phase. Typical three-channel RGB scanner systems do not directly provide good es- timates of the four CMYK colorant halftones that are commonly used in color printing systems. To address this challenge, we propose an estimation method that, when used with suitably selected halftone periodicities, jointly exploits the differences in the spatial periodicities and the color (spectra) of the halftone separations to obtain good estimates of the individual halftones from conventional RGB scans. We demonstrate the efficacy of this methodology experimentally us- ing continuous phase modulation for the embedding of independent visual watermark patterns in the individual halftone separations. Wa- termarks detected from the estimates of halftone separations ob- tained using the proposed estimation method have a much higher contrast than those detected directly. We also evaluate the accuracy of the estimated halftones through simulations and demonstrate that the proposed estimation method offers high accuracy. © 2010 SPIE

Security in Wireless Sensor Networks using Frequency Hopping

Abstract: Sensor Network (WSN) is a collection of thousands of tiny sensor nodes having the capability of wireless communication, limited computation and sensing. These networks are vulnerable to internal and external attacks due to the lack of tamper-resistant packaging and the insecure nature of wireless communication channels. Since most of the existing routing protocols are application specific and hence do not satisfy the security constraints of wireless sensor networks. Whenever any device comes within the frequency range can get the access to the transmitting data and may affect the transmission. In this paper, we simulated the concept of frequency hopping and proved it a better approach to provide security in WSN..

Blast Disease of Rice Caused by Magnaporthe grisea : A review

Abstract: Rice is one of the major field crops raised in Assam. At present’ rice occupies about 25.30 lakh hactares or 80% of the total cropped area of the state .It plays a significant role in the state economy. Rice is traditionally grown throughout the year. Assam occupies a special place in the rainfed rice production system in the eastern India by covering about 9%n of the total rice area and contributes 8% to the food production. At the national level, the state contributes over 5% of rice area and 4% of rice production. Though rice is subjected to many fungal diseases but Magnaporthe grisea is one most destructive one. So, controlling this disease is very important. This paper present review on rice blast disease of rice with an emphasis on M. grisea.

In Vitro Propagation and Phytochemical Screening of Papilionanthe teres (Roxb.) Schltr.

Abstract: Papilionanthe teres (Roxb.) Schltr. is a medicinal orchid found in all reserve forests of Southern Assam, India. Mature pods of Papilionanthe teres were collected from natural plants and seeds were inoculated in Murashige and Skoog (MS), Knudson C (KnC), Commercial Orchid Maintenance(OMM) and Commercial Orchid Maintenance Replate (OMR) medium(HiMedia). Best germination and growth were observed in commercial orchid maintenance replate medium supplemented with 2mg\L IAA and 5mg\L KN. Growth of root, shoot were measured after three months of germination. Shoot tip and nodal explant of the plant were tried in different medium viz. MS, White, B5, KnC, Commercial Orchid Maintenance medium etc. containing different growth regulators modification for micro propagation. For phytochemical screening qualitative tests were performed from the dried powder of the plants. From the qualitative test it was observed that the plant extracts contain alkaloid, flavonoid and tannin in petroleum ether extract and alkaloid, tannin and saponin were found in ethyl acetate extract. Steroid was found present in methanol and benzene extract. Flavonoid was found only in acetone extract.

Multiplexed clustered-dot halftone watermarks using bi-directional phase modulation and detection

Abstract: We present a method for embedding and detection of visual watermark patterns in printed images that use clustered-dot halftones in the printing process. The method allows two independent watermark patterns to be multiplexed, i.e. embedded in the same region of the printed image, thereby offering an improvement over prior techniques. The watermark patterns are embedded via phase modulation along the two periodicity directions of the halftone. Each embedded pattern can be visually detected, without interference from the other watermark, when the printed image, or a scan thereof, is overlaid with a decoder mask consisting of periodic lines oriented along the corresponding halftone periodicity direction. We experimentally demonstrate that our proposed multiplexing technique is effective. We also present analysis that demonstrates that the embedding has minimal visual impact and explains the pattern observed in the watermark detection process.

Adaptive Sensing and Optimal Power Allocation for Wireless Video Sensors With Sigma-Delta Imager

Abstract: We consider optimal power allocation for wireless video sensors (WVSs), including the image sensor subsystem in the system analysis. By assigning a power-rate-distortion (P-R-D) characteristic for the image sensor, we build a comprehensive P-R-D optimization framework for WVSs. For a WVS node operating under a power budget, we propose power allocation among the image sensor, compression, and transmission modules, in order to minimize the distortion of the video reconstructed at the receiver. To demonstrate the proposed optimization method, we establish a P-R-D model for an image sensor based upon a pixel level sigma-delta ( ) image sensor design that allows investigation of the tradeoff between the bit depth of the captured images and spatio-temporal characteristics of the video sequence under the power constraint. The optimization results obtained in this setting confirm that including the image sensor in the system optimization procedure can improve the overall video quality under power constraint and prolong the lifetime of the WVSs. In particular, when the available power budget for a WVS node falls below a threshold, adaptive sensing becomes necessary to ensure that the node communicates useful information about the video content while meeting its power budget.

Bulk Heterojunction Photovoltaics Using Broadly Absorbing Small Molecules Based on 2-Styryl-5-phenylazo-pyrrole

Abstract: Three new soluble small molecules (B, B6, and A) with a low band gap based on 2-styryl-5-phenylazo-pyrrole were synthesized. Molecules B and B6 contained pyrrole and N-hexylpyrrole, respectively, as the central unit, which was connected to N,N-dimethylphenyl-4-azo on one side of the pyrrole molecule. Molecule A contained N-hexylpyrrole as the central unit, which was connected to anthracenyl-9-azo on one side of the pyrrole molecule. The other side of the pyrrole molecule was connected to cyanovinylene 4-nitrophenyl for all molecules. The long-wavelength absorption maximum of the molecules was located at 601−637 nm, and their optical band gap was 1.62−1.67 eV. The photovoltaic properties have been investigated using blends of B, B6, or A with PCBM, and it was found that the device based on A:PCBM had a higher power conversion efficiency (PCE) (2.06%) than the devices based on B:PCBM (1.33%) and B6:PCBM (1.36%). This has been attributed to the higher hole mobility, the lower band gap of A relative to that o...

Taste masking of Promethazine Hydrochloride using Eudragit E100via solid dispersion technique to develop fast disintegrating tablets

Abstract: The purpose of present study was to mask the intensely bitter taste of promethazine HCl and to formulate fast disintegrating tablets (FDTs) of the taste masked drug. The taste masking was done via solid dispersion (SD) technique using Eudragit E100 (amino-alkyl methacrylate copolymer) in different ratios. The drug-polymer compatibility and their compatibility with process condition were evaluated on the basis of FTIR spectroscopy and there was no sign of any interaction between drug and polymer and within the prepared system. The SD prepared with different ratio of drug and polymer was evaluated for drug release in phosphate buffer (pH 6.2), and for in vivo taste. The SD with drug polymer ratio of 1:4 did not give any taste and shows minimum release in phosphate buffer (pH 6.2); therefore that ratio was selected as best candidate for development of FDTs. The nine batches were prepared using crospovidone and croscarmellose to find out effect of both the polymers on in vitro and in vivo disintegration time. The prepared batches were also evaluated for different parameters such as hardness, friability, wetting time, in vitro dispersion time, and for in vivo taste. Crospovidone 20% w/w gave the minimum disintegration time. The tablets of the final formulation containing 38.16 % mannitol and 9.14 % of microcrystalline cellulose showed the minimum disintegration time of 23 sec. The taste evaluation of the tablets in comparison to quinine sulfate in human volunteers revealed a considerable taste masking. Thus results conclusively demonstrated successful masking of taste and fast disintegration of the developed formulation in the oral cavity.

Clustered-dot color halftone watermarks using spatial frequency and color separability

Abstract: A framework for clustered-dot color halftone watermarking is proposed. Watermark patterns are embedded in the color halftone on per-separation basis. For typical CMYK printing systems, common desktop RGB color scanners are unable to provide the individual colorant halftone separations, which confounds per-separation detection methods. Not only does the K colorant consistently appear in the scanner channels as it absorbs uniformly across the spectrum, but cross-couplings between CMY separations are also observed in the scanner color channels due to unwanted absorptions. We demonstrate that by exploiting spatial frequency and color separability of clustered-dot color halftones, estimates of the individual colorant halftone separations can be obtained from scanned RGB images. These estimates, though not perfect, allow per-separation detection to operate efficiently. The efficacy of this methodology is demonstrated using continuous phase modulation for the embedding of per-separation watermarks.

Checklist of insects associated with Jamun (Syzygium cuminii Skeels) from India

Abstract: common, large evergreen tree of Indian subcontinent. The synonyms of S. cumini L. are : Eugenia cumini (L.) Druce, Eugenia jambolana Lam., Myrtus cumini L., Syzygium jambolanum DC. Common names are java plum, black plum, jambul and Indian blackberry. Its distribution range starts from Myanmar and extends up to Afghanistan. It grows naturally in tropical as well as in sub-tropical zones. It is generally cultivated in India. It tends to grow an umbrella like crown having dense foliage, thus gives pleasant cool shade during summer. Jamun is used as a carminative, against diarrhea, stomachache, astringent and also utilized in enlargement of the spleen and as a diuretic. The leaves have antibacterial properties and the bark is utilized against inflammations, while the seeds have antidiabetic properties. There are lot of major and minor pests which infest leaves, flowers, fruits, seeds and barks, but the perusal of literature reveals that there is no consolidated account available on the insects associated with jamun in India except a major contribution was made by Butani (1979). In this paper, an attempt has been made to provide the current status, nature of damage, pest status, hosts, updated classification of insects associated with jamun in India. MATERIALS AND METHODS Insects were collected in the field with aspirator, manually and aerial sweep net and at night with the help of light trap. The insects were killed by using tetrachloro ethane or ethyl acetate or benzene. These were stretched, pinned, labeled, identified, preserved in the wooden collection boxes and deposited in the National Pusa Collection, Division of Entomology, Indian Agricultural Research Institute, New Delhi. The collected / reference specimens preserved in the National Pusa Collection were also examined and incorporated in the checklist.

Thermal modeling and simulation of a package-on-package embedded micro wafer level package (EMWLP) structure at the package and system-level

Abstract: In the embedded wafer-level packaging field, the embedded micro wafer level package (EMWLP) technology leverages on fan-out redistribution connections, keeping the reliance on wire-bonding and flip-chip bump connections to a minimum, thus streamlining the packaging process. As the embedded micro wafer level packaging (EMWLP) technology evolves to capitalize on package-on-package (POP) technology, this study's parametric thermal modeling focuses on analyzing the thermal impact of increased density in a low thermal conductivity packaging material. The package design in this work has the following specifications: the memory EMWLP (die size: 7×7×0.2mm) on logic EMWLP structure (die size : 8×8×0.2mm), sized 12×12×0.9mm in total. The POP structure, furthermore, incorporates through-mold-interconnects (TMI) in the bottom logic package to provide short electrical connection from the top package to the board level. The impact on multi-package thermal resistance is then studied as the following parameters vary: power dissipation (in both packages); mold conductivity; number of TMIs; number of solder ball connections; inclusion and size of an interpackage heatslug; inclusion and thermal conductivity of a top heatspreader. The thermal management of the dies are also studied based on the above measures and was found to accommodate under 4W of total POP power. Finally, simulation results for a general system-level thermal modeling of the EMWLP POP in a cellphone scenario are also conducted with passive thermal management solutions proposed.

Efficient classification of scanned media using spatial statistics

Abstract: Photography, lithography, xerography, and inkjet printing are the dominant technologies for color printing. Images produced on these "different media" are often scanned either for the purpose of copying or creating an electronic representation. For an improved color calibration during scanning, a media identification from the scanned image data is desirable. In this paper, we propose an efficient algorithm for automated classification of input media into four major classes corresponding to photographic, lithographic, xerographic and inkjet. Our technique exploits the strong correlation between the type of input media and the spatial statistics of corresponding images, which are observed in the scanned images. We adopt ideas from spatial statistics literature, and design two spatial statistical measures of dispersion and periodicity, which are computed over spatial point patterns generated from blocks of the scanned image, and whose distributions provide the features for making a decision. We utilize extensive training data and determined well separated decision regions to classify the input media. We validate and tested our classification technique results over an independent extensive data set. The results demonstrate that the proposed method is able to distinguish between the different media with high reliability.

Ecology and Biodiversity Analysis of Cyanobacteria

Abstract: Cyanobacteria are a group of extraordinarily diverse Gram-negative prokaryotes that originated 3.5 billion years ago. Their diversity ranges from unicellular to multicellular, coccoid to branched filaments, nearly colourless to intensely pigmented, autotrophic to heterotrophic, psychrophilic to thermophilic, acidophilic to alkalophilic, planktonic to barophilic, freshwater to marine including hyper saline. They are found both free living and as endosymbionts. They are considered to be one of the potential organisms which can be useful to mankind in various ways. A number of important advances have occurred in cyanobacterial biotechnology in the recent years. World wide attention is drawn towards cyanobacteria for their possible use in food, feed, fuel, fertilizer, colourant, production of various secondary metabolites including vitamins, toxins, enzymes, pharmaceuticals, pharmacological probes and the pollution abatement. Only a few cyanobacterial strains (including Spirulina) have been well characterized or exploited commercially. Basic research is needed to identify new cyanobacterial strains of high value products, strain improvement using molecular tools for rapid growth rate, ability to withstand varied environment conditions and the enhancement synthesis of high value products. This review is intended to focus on the biodiversity of cyanobacteria in various environments, recent application and the new development they are diversifying the directions or commercial exploitation.

Development of directly compressible co-processed excipients forsolid dosage forms

Abstract: The tablets manufactured by direct compression method using co-processed excipient showed relatively better disintegration time and in vitro drug release, with omission of number of laborious steps as compared to tablets manufactured by conventional wet granulation method. Melt granulation technique is a potential alternative for the development of directly compressible adjuvants. Lactose and mannitol blend (1:1, 1:2, 2:1, 1:3, 3:1; 90, 80 or 70 %) along with meltable binders PVP K – 30 and PEG 4000 (1:9, 1:1 or 9:1) were used in the formulation. The effect of addition of co-processed excipient in a formulation containing poorly compressible drug (paracetamol) was also studied. The micromeritic studies and bulk powder properties of the co-processed agglomerates were studied. It was observed that co-processed agglomerates exhibited much better flow properties as compared to individual excipients. The optimized formulation shows that the tensile strength was found to be inversely related with the percentage of acetaminophen. It might be due to the poor compressibility and elastic recovery of acetaminophen. Lower value of disintegration time may be attributed to decreased tensile strength. No capping and lamination of tablet was observed as usually associated with acetaminophen compression.