Detachable immobilization of liposomes on polymer gel particles

Immobilization of liposomes on hydrophobized Sephacryl gel and controlled detachment of the liposomes from the gel were examined. The gel was chemically modified and bore octyl, hexadecyl or cholesteryl moiety via disulfide linkage as anchors to liposomal bilayer membrane. Upon interaction with the gel, egg phosphatidylcholine liposomes were successfully immobilized onto the gel. The gel with cholesteryl moiety showed 1.7 times higher liposome immobilization per anchor moiety than the gels with the alkyl moieties. The immobilization of liposomes on the gel was stable, and no significant spontaneous detachment of phospholipid or leakage of fluorescein isothiocyanate-conjugated dextran encapsulated in the immobilized liposomes was observed in 24h. Reductive cleavage of the disulfide linkage by dithiothreitol resulted in detachment of the liposomes from the gel. The majority of the detached liposomes were found encapsulating the dextran derivative, and these liposomes should have kept their structural integrity throughout the immobilization and the detachment processes. The release of the liposomes was insignificant until the ratio of the dithiothreitol to the hydrophobic anchor reached a threshold. The presence of the threshold suggests that the immobilization of liposomes should require a certain minimum number of the hydrophobic moieties anchored in the liposomal membrane. By applying the present immobilization-detachment system, preparation of liposomes encapsulating the dextran derivative without using costly gel filtration or ultracentrifugation procedure was successfully demonstrated.     

Localization of iris in gray scale images using intensity gradient

A new method of iris localization based on intensity value analysis is proposed in this paper. Iris recognition systems are mainly dependent on the performance of iris localization processing. Steps after localization involve normalization, feature extraction and matching. These steps are based on the accuracy and efficiency of localization of iris in human eye images. In the proposed scheme, the inner boundary of iris is calculated by finding the pupil center and radius using two methods. In the first method, selected region is adaptively binarized and centroid of the region utilized for obtaining pupil parameters. Edges are processed to detect radius and center of pupil during the second method. For outer iris boundary, a band is calculated within which iris outer boundary lies. Signals in one dimension are picked up along radial direction within determined band at different angles. Three points with maximum gradient are selected from each signal. Redundant points are deleted using Mahalanobis distance and remaining points are used to obtain the outer circle of the iris. Points for upper and lower eyelids are found in the same way as the iris outer boundary. Selected points are then statistically fitted to make parabolas and lastly eyelashes are removed from the image to completely localize the iris. Experimental results show that proposed method is very efficient and accurate.     

Microstructural studies of nanocrystalline α-alumina powder produced from Al13-cluster

Nanocrystalline alumina powder was produced from calcinations of Al₁₃-oxalate precipitates at 1100 °C. A nearly normal distribution of agglomerated alumina powder was obtained with an average particle size of about 1 μm. XRD measurement confirmed that the alumina produced was of high purity and crystalline α-phase. Microstructural features of both the precipitates and alumina obtained were studied using the small angle neutron scattering (SANS) technique. SANS examinations show the formation of microstructures in the alumina powder of mass fractals type with dimension of ∼2.8 indicative of low intra-granular porosity.     

Stainless steel supported NiS/CeS nanocomposite for significantly enhanced oxygen evolution reaction in alkaline media

Journal of Solid State Electrochemistry - The discovery of highly active and cost-effective materials capable of catalyzing the oxygen evolution reaction (OER) is essential for water splitting. In...     

An inimitable and ecological pleasant technique for the assessment of trace amount of copper (II) in tangible samples with new complexing reagent

A simple and rapid spectrophotometric technique has been designed for the trace copper analysis employing 1-(2-Thiazolylazo)-2-naphthol (TAN) reagent in aqueous micellar solution of cetyl trimethylammonium bromide (CTAB) as a surfactant. Copper complexed with 1-(2-Thiazolylazo)-2-naphthol to form bis[1-(2-Thiazolylazo)-2-naphthol]copper. The present spectrophotometric technique was very important since the micellar system was used in place of the toxic, high cost and time-consuming solvent extraction steps. The technique showed an enhanced detection efficiency, specificity, and molar absorptivity. It was found that the molar absorption coefficient and sensitivity of Sandel were ε 2.45 × 10⁴ L mol^?1cm^?1 and 2.6 ngcm^?2 at λ_max 578.4 nm. A linear calibration plot in the range 0.12–5.0 μg mL^?1 was obtained; a stoichiometric metal ligand ratio [M:L] of 1:2 was found for the formation of Cu-[TAN]₂. The complex was formed at pH 9.5 and was stable up to 24 h. The proposed technique has been employed to study copper from different alloys, biological, environmental and pharmaceutical samples.     

Assembly of long carbon nanotube bridges across transparent electrodes using novel thickness-controlled dielectrophoresis

The assembly of carbon nanotubes (CNTs) across planner electrodes using dielectrophoresis (DEP) is one of the standard methods used to fabricate CNT-based devices such as sensors. The medium drag velocity caused by electrokinetic phenomena such as electrothermal and electroosmotic might drive CNTs away from the deposition area. This problem becomes critical at large-scale electrode structures due to the high attenuation of the DEP force. Herein, we simulated and experimentally validated a novel DEP setup that uses a top glass cover to minimize the medium drag velocity. The simulation results showed that the drag velocity can be reduced by 2–3 orders of magnitude compared with the basic DEP setup. The simulation also showed that the optimum channel height to result in a significant drag velocity reduction was between 100 μm and 240 μm. We experimentally report, for the first time, the assembly and alignment of CNT bridges across indium tin oxide (ITO) electrodes with spacing up to 125 μm. We also derived an equation to optimize the CNT's concentration in suspensions based on the electrode gap width and channel height. The deposition of long CNTs across ITO electrodes has potential use in transparent electronics and microfluidic systems.     

Higher-order inertial Alfvén wave dressed solitons,quasiperiodic structures,and chaos in plasmas

The higher-order, low-amplitude inertial Alfvén wave (IAW) dressed soliton and chaos are investigated in a magnetized plasma. In the linear limit, the dispersion relation for propagation of IAWs in plasmas is also obtained in the presence of electron thermal effects and illustrated numerically. It is found that the electron inertial length plays an important role for wave dispersion effects and its phase speed is increased on including the electron temperature in the model. The reductive perturbation method is employed to obtain the first-order IAW Korteweg–de Vries (KdV) soliton and second-order dressed soliton solutions analytically, which gives electron density dip (or rarefactive) structure and moves with super Alfvénic speed in plasmas. The numerical illustrations of the KdV and dressed IAW solitons are also presented by using the laboratory and space plasma parameters given in the literature. Furthermore, a numerical study of quasi-periodicity and chaotic behaviour of IAWs in the presence of external periodic force is also discussed in detail. The effects of plasma beta (which depends on plasma density, electron temperature, and magnetic field intensity) and obliqueness of the wave propagation on the formation of nonlinear Alfvénic wave structures have also been presented.     

Plane mixing layers from parallel and non-parallel merging of two streams

Two types of mixing layers produced from two streams merging at 0° and 18° have been investigated. Each type of mixing layer was produced with velocity ratios 0.7, 0.8 and 0.9 and measurements were taken at six streamwise locations. The boundary layers were untripped and initially turbulent in all cases. Both types of mixing layers were found to attain a self-similar state for velocity ratios 0.7 and 0.8 but failed for 0.9 within the measurement domain. It appears that the mixing layer flow becomes self-similar earlier when merging at 18° than at 0°. With increasing velocity ratio, the development distance was increased and the splitter wake played a dominant role in the development of the mixing layers. The mixing layers from non-parallel merging streams (18°) were found to have higher growth in the near-field than those from parallel merging streams (0°). Both types of mixing layers were found to decrease in growth with increasing velocity ratio, though they spread more at the high-speed side. Published online: 23 November 2002     

Antibiofilm,Anti-Quorum Sensing Activities,and Molecular Docking Studies of Seriphidium quettense Essential Oil

Chemistry of Natural Compounds -