Search results for "Bead"

Dilute solution rheology of flexible macromolecules (bead–rod model)

1974

The rheological behavior of dilute solutions of flexible macromolecules is studied by means of a freely jointed multiple bead–rod model. The solution of the equations describing the mechanics of the system is obtained by means of a numerical procedure, which applies to arbitrary flow conditions. The case of the transient stress in uniaxial elongational flow is developed in some detail. A comparison with bead–spring models shows both quantitative and qualitative differences which are briefly discussed.

Loading, release and stability of epirubicin-loaded drug-eluting beads.

2015

Purpose The aim of this study was to determine the loading efficiency, physico-chemical stability and release of epirubicin-loaded DC Bead™ (Biocompatibles UK Ltd, a BTG International group company) (bead size 70–150 µm (=DC Bead M1™) and 100–300 µm) after loading with epirubicin solution (2 mg/ml) or reconstituted powder formulation (25 mg/ml) and controlled storage. Methods DC Bead™ were loaded with 76 mg epirubicin solution (Epimedac™, Medac GmbH) or 75 mg epirubicin powder formulation (Farmorubicin™, Pharmacia Pfizer GmbH) per 2 ml of beads. Drug loading efficiency and stability were determined by measuring the epirubicin concentration in the excess solution after predetermined interval…

Effects of BRCA2 cis-regulation in normal breast and cancer risk amongst BRCA2 mutation carriers

2012

Introduction: Cis-acting regulatory single nucleotide polymorphisms (SNPs) at specific loci may modulate penetrance of germline mutations at the same loci by introducing different levels of expression of the wild-type allele. We have previously reported that BRCA2 shows differential allelic expression and we hypothesize that the known variable penetrance of BRCA2 mutations might be associated with this mechanism. Methods: We combined haplotype analysis and differential allelic expression of BRCA2 in breast tissue to identify expression haplotypes and candidate cis-regulatory variants. These candidate variants underwent selection based on in silico predictions for regulatory potential and di…

CRYOPRESERVATION OF PEACH SHOOT TIPS BY ENCAPSULATION DEHYDRATION

2011

Characterization of cell wall proteins of yeast and hydrophobic mycelial cells of Candida albicans

1991

Cell surface hydrophobicity (CSH) of blastoconidia and blastoconidia bearing germ tubes of Candida albicans ATCC 26555 was monitored by assessing attachment of polystyrene microspheres to the cell surface, and we found that mature hyphae were significantly hydrophobic. Treatment of intact cells with low concentrations of beta-glucanase (Zymolyase 20T) or proteases abolished or significantly reduced attachment of latex beads to hyphae. This effect paralleled an obvious reduction in CSH of the entire cell population, as measured by an aqueous-hydrocarbon biphasic partitioning assay. Analysis of the cell wall material released by Zymolyase and adsorbed on polystyrene microspheres indicated tha…

An aptamer-gated silica mesoporous material for thrombin detection.

2013

An aptamer-capped mesoporous material for the selective and sensitive detection of &-thrombin in human plasma and serum has been prepared and characterised.

Experimental design method to the weld bead geometry optimization for hybrid laser-MAG welding in a narrow chamfer configuration

2017

International audience; The work presented in this paper relates to the optimization of operating parameters of the welding by the experimental design approach. The welding process used is the hybrid laser-MAG welding, which consists in combining a laser beam with an MAG torch, to increase the productivity and reliability of the chamfer filling operation in several passes over the entire height of the chamfer. Each pass, providing 2 mm deposited metal and must provide sufficient lateral penetration of about 0.2 mm. The experimental design method has been used in order to estimate the operating parameters effects and their interactions on the lateral penetration on one hand, and to provide a…

Neutral solar photo-Fenton degradation of 4-nitrophenol on iron-enriched hybrid montmorillonite-alginate beads (Fe-MABs)

2014

Hybrid montmorillonite-alginate beads (MABs) were prepared by the ion-gelation method from alginate and montmorillonite clay suspension dropped in a calcium chloride solution. Similarly, iron-enriched beads (Fe-MABs) were prepared using iron-exchanged montmorillonite. All beads were characterized by atomic absorption and Fourier-transform infrared spectroscopy. The efficiency of Fe-MABs as catalysts for the solar photo-Fenton performed at initial pH = 7.0 was evaluated by varying the catalyst amount and hydrogen peroxide concentration, and monitoring the removal of 4-nitrophenol (4-NP) at initial concentration of 10 ppm. A kinetic analysis showed that the removal of 4-NP by Fe-MABs followed…

Escherichia coli inactivation by neutral solar heterogeneous photo-Fenton (HPF) over hybrid iron/montmorillonite/alginate beads

2015

Abstract Hybrid alginate montmorillonite iron enriched beads (Fe-MABs) were synthesized using ion gelation method and used as catalyst in Escherichia coli inactivation in neutral solar photo-Fenton conditions. A kinetic analysis showed that the E. coli inactivation by Fe-MABs followed a pseudo first-order kinetics model. Complete disinfection was achieved in 1 h of irradiation by using Fe-MABs in the presence of 10 ppm of H 2 O 2 . Preliminary studies on recyclability showed possible beads reused up to four times. Overall, Fe-MABs represent an environmental friendly material able to achieve bactericidal performance measured by E. coli inactivation under photooxidative conditions.

Colon-specific drug delivery: Influence of solution reticulation properties upon pectin beads performance.

2006

In this study, pectinate gel beads were produced by ionotropic gelation method with different solutions of cross-linking agents and ketoprofen was entrapped as model drug. The influence of these formulation parameters was investigated upon bead properties and upon their performance to target the colon. Zinc pectinate beads obtained with 10% of counter-ions solution at pH 1.6 exhibited the strongest gel network due to "egg-box" dimmer formation helped by hydrogen bonding. Furthermore the gel network formed at low pH was arranged in a compact three-fold conformation. Thus, this matrix structure in enteric capsules induced the lowest drug release in the upper gastro-intestinal tract (pH 1.2 fo…