Tunable absorber embedded with GST mediums and trilayer graphene strip microheaters.

Investigation was made of the optical response of metal-dielectric stacks-based cavity structures embedded with graphene microheaters for the purpose of perfect absorption. The absorber configuration exploits the Ge2Sb2Te5 (GST) phase changing medium, and the effects of different parametric and operational conditions on the absorption spectra were explored. The refractive indices of GST layers can be manipulated by the external electrical pulses applied to microheaters. The amplitude and duration of electrical pulses define the crystallinity ratio of the used GST mediums. The results revealed achieving perfect absorption (> 99%) in the visible and infrared (IR) regimes of the electromagnetic spectrum upon incorporating two thin GST layers of different thicknesses (in the stack) in the amorphous state. The proposed configuration showed the capability of introducing independent transition state (amorphous and/or crystalline) for each GST layer-the visible regime could be extended to the IR regime, and the perfect absorption peak in the IR regime could be broadened and red-shifted. It is expected that the structure would find potential applications in active photonic devices, infrared imaging, detectors and tunable absorbers.

Bioactive Loaded Lipid-based Nanostructures: A Novel Insight for Age-related Neurodegeneration.

Substantial affirmation suggested that oxidative stress remains an impelling target, contributing to initiate and exacerbate the multiple neurological complications in age-related neurodegeneration (ARN). Factors including gene and environmental toxins are now becoming the most threatening cause of oxidative stress, which leads to mitochondrial dysfunction of the neurons that ultimately causes permanent loss of their functionality. Clinical trials on antioxidants are still in the pipeline to access them as a potential therapeutic class. But this raised the generosity for not only to investigate the module of the antioxidant mechanism but also to justify the drug delivery and dose regimen. Biological barriers, predominantly, Blood-brain barrier (BBB) and rapid firstpass metabolism, are some of the potential obstacles for the effective targeting of the therapeutic agent. Bioactive drugs with antioxidant capacity, loaded with lipid-based Nano career system have revealed to be a novel therapeutic intervention for ARN. The review will deal with the comprehensive state-of-art methodology for the delivery of bioactive loaded lipid Nanocarriers to treat neurodegeneration. A systematic analysis of published reports will help the researchers to understand the role of natural compound loaded Nanoengineered system in the field of ARN as a potential Nano therapeutic intervention.

Elliptical metallic rings-shaped fractal metamaterial absorber in the visible regime.

Achieving the broadband response of metamaterial absorbers has been quite challenging due to the inherent bandwidth limitations. Herein, the investigation was made of a unique kind of visible light metamaterial absorber comprising elliptical rings-shaped fractal metasurface using tungsten metal. It was found that the proposed absorber exhibits average absorption of over 90% in the visible wavelength span of 400-750 nm. The features of perfect absorption could be observed because of the localized surface plasmon resonance that causes impedance matching. Moreover, in the context of optoelectronic applications, the absorber yields absorbance up to ~ 70% even with the incidence obliquity in the range of 0°-60° for transverse electric polarization. The theory of multiple reflections was employed to further verify the performance of the absorber. The obtained theoretical results were found to be in close agreement with the simulation results. In order to optimize the results, the performance was analyzed in terms of the figure of merit and operating bandwidth. Significant amount of absorption in the entire visible span, wide-angle stability, and utilization of low-cost metal make the proposed absorber suitable in varieties of photonics applications, in particular photovoltaics, thermal emitters and sensors.

On the Core-Shell Nanoparticle in Fractional Dimensional Space.

The investigation of core-shell nanoparticles has been greatly exciting in biomedical applications, as this remains of prime importance in targeted drug delivery, sensing, etc. In the present work, the polarizability and scattering features of nanoparticles comprised of nano-sized dielectric/metallic core-shell structures were investigated in the fractional dimensional (FD) space, which essentially relates to the confinement of charged particles. For this purpose, three different kinds of metals-namely aluminum, gold and silver-were considered to form the shell, having a common silicon dioxide (SiO2) nanoparticle as the core. It is noteworthy that the use of noble metal-SiO2 mediums interface remains ideal to realize surface plasmon resonance. The core-shell nanoparticles were considered to have dimensions smaller than the operating wavelength. Under such conditions, the analyses of polarizability and the scattering and absorption cross-sections, and also, the extinction coefficients were taken up under Rayleigh scattering mechanism, emphasizing the effects of a varying FD parameter. Apart from these, the tuning of resonance peaks and the magnitude of surface plasmons due to FD space parameter were also analyzed. It was found that the increase of FD space parameter generally results in blue-shifts in the resonance peaks. Apart from this, the usage of gold and silver shells brings in fairly large shifts in the peak positions of wavelengths, which allows them to be more suitable for a biosensing purpose.

Antimicrobial, anti-inflammatory and wound healing activity of polyherbal formulation.

According to Ayurveda, individual herbs are insufficient to achieve a desired therapeutic effect. When it is optimized as multiple herbs composition in a particular ratio it will give a therapeutic effect in a better way with reduced toxicity. In order to develop such an intervention, the present study was intended to develop a polyherbal drug from methanolic extracts of Plumbago zeylanica Linn, Datura stramonium Linn and Argemone mexicana Linn. The study also aimed to evaluate the impact of polyherbalism on antimicrobial and antioxidant effect, thereafter the ratio of individual plant extracts was optimized accordingly to treat the wound. The poyherbal drug was put on preclinical trial to access the anti-inflammatory and wound healing activity as 2% and 5% polyherbal carbopol-940 gels. The antimicrobial activity was assessed by agar well diffusion and broth dilution method while wound healing activity was evaluated by excision and incision wound models. Topical anti-inflammatory activity was assessed by carrageenan induced paw oedema. The findings of the study revealed the synergistic antimicrobial potential of Polyherbal drug against gram-positive and negative strains. Polyherbal carbopol- 940 gels (2% and 5%w/w) promoted the wound healing and anti-inflammatory effect. The high rate of wound contraction (<0.0001), early epithelialization period (<0.0001) and increased wound breaking strength (<0.0001) were observed in 2% and 5% polyherbal gel treated group when compared to the normal control and negative control group. The antimicrobial and anti-inflammatory effect of Polyherbal drug provoked and promoted the wound healing process through accelerated remodelling of damaged tissue.

HPLC method for estimation of metformin hydrochloride in formulated microspheres and tablet dosage form.

A simple, accurate, economical and reproducible HPLC method has been developed for quantitative estimation of metformin hydrochloride from tablet dosage form and formulated microspheres. The developed HPLC method is a reverse phase chromatographic method using phenomenex C(18) column and acetonitrile:phosphate buffer (65:35) pH adjusted to 5.75 with o-phosphoric acid as mobile phase and glipizide as internal standard. The linearity was observed in concentration range of 0-25 mug/ml for metformin hydrochloride. Results of analysis were validated statistically and by recovery studies.

Formulation and evaluation of ethyl cellulose microspheres prepared by the multiple emulsion technique.

The aim of this study was to formulate and evaluate microencapsulated controlled release preparations of metformin hydrochloride using ethyl cellulose as the retardant material with high entrapment efficiency and extended release. Microspheres were prepared by the double emulsion solvent diffusion method. A mixed solvent system consisting of acetonitrile and dichloromethane in 1:1 ratio and light liquid paraffin were chosen as the primary and secondary oil phases, respectively. Span 80 was used as the surfactant for stabilizing the secondary oil phase. The prepared microspheres were characterized by drug loading, optical microscopy and scanning electron microscopy (SEM). The in vitro release studies were performed in a series of buffer solutions with variable pH. The drug loaded microspheres showed 55-85% of entrapment and the release was extended for up to 12 h. SEM studies revealed that the microspheres were spherical and porous in nature. Data obtained from in vitro release studies were fitted to various kinetic models and high correlation was obtained with the Higuchi model. The drug release was found to be diffusion controlled. Oral administration of the microspheres to the albino mice provided decreased plasma glucose for more than 10 h.

Controlled porosity osmotic pump for the delivery of flurbiprofen.

Controlled porosity osmotic pump contains water-soluble additives in the coating membrane, which in contact with aqueous environment dissolves and results in formation of micro porous membrane. The resulting membrane is substantially permeable to both water and dissolved drug. The drug release from this type of system is independent of pH and follows zero order kinetics. In the present investigation, effort has been made to study release mechanism of drug having low water solubility by means of controlled porosity osmotic pump. The capsule membrane was prepared by phase inversion technique. The phase inversion was carried by dipping the stainless steel mould in a 15% solution of cellulose acetate containing varying amounts of pore-forming agent, glycerol (50% to 70% w/w), followed by quenching in an aqueous solution (10% w/v glycerol), which resulted in the formation of the asymmetric membrane. The delivery orifices so formed were confirmed by release of an encapsulated dye from the capsule and scanning electron microscope (SEM). The drug selected for this study, Flurbiprofen, has low water solubility and hence is unable to create osmotic pressure to cause drug release. To enhance the solubility and its osmotic pressure, this study was conducted with a solubility enhancer sodium lauryl sulfate (SLS). The quantity of SLS was predetermined by conducting a solubility study of flurbiprofen with SLS. Release rate studies revealed that less than 10% of drug was released from the system without SLS, while about 75% release was observed from systems containing SLS. The release rate increased as the concentration of pore forming agent increased.

Preparation of Alginate Gel Beads Containing Metformin Hydrochloride Using Emulsion- Gelation Method

A new emulsion gelation method was used to prepare gel beads for a highly water-soluble drug metformin hydrochloride using sodium alginate as the polymer. The gel beads containing oil was prepared by gently mixing or homogenizing oil and water phase containing sodium alginate which was then extruded into calcium chloride solution to produce gel beads. The effects of factors like type of oil and percentage of oil on the morphology and release characteristics were investigated. A variety of oils were used to study the effect on the sustaining property of the formed beads. The oil entrapped calcium alginate gel beads showed good sustained release. Scanning electron photomicrographs demonstrated minute oil globules on the beads and also through the inner surface of the beads. The beads also showed floating behavior depending on the type of the oil that have been used for the preparation

Identification of a vibrational frequency corresponding to H-atom translocation in hypericin.

Using time-resolved infrared spectroscopy, ab initio quantum mechanical calculations and synthetic organic chemistry a region in the infrared spectrum of triplet hypericin has been found between 1400 and 1500 cm-1 corresponding to the translocation of the hydrogen atom between the enol and the keto oxygens, O...H...O. This result is discussed in the context of the photophysics of hypericin and of eventual measurements to observe directly the excited-state H-atom transfer.

Cytologic diagnosis of neurilemomas of male breast by fine needle aspiration.

Among 217 cases of male breast lesions subjected to fine needle aspiration cytology(FNAC) over a period of nine years, three cases were found to be having neurilemomas, The review of literature reveals the first case of neurilemoma of male breast diagnosed by FNAC was reported in 1992. Very scanty literature is available on this rare tumour of male breast. The aspirates yielded cellular smears composed of clusters of spindle shaped cells and Verocay bodies. Histopathological examination of the excised masses confirmed the cytological diagnosis.