Search results for "SIZE"
showing 10 items of 2718 documents
Continuous spin fractionation and characterization by size-exclusion chromatography for styrene-butadiene block copolymers.
2005
Abstract Linear and star-shaped styrene–butadiene block copolymers synthesized by anionic polymerization of butadiene and styrene were fractionated by applying a newly developed large-scale fractionation technique, named continuous spin fractionation (CSF). Their molecular weight and polydispersity index ( d = M w / M n ) were measured with size-exclusion chromatography and static light scattering. For the linear triblock copolymer a fractionation via temperature variation turned out to be better suited than the usual isothermal procedure. The star-shaped polymer with the d value of 1.33 was fractionated in two CSF steps to get the targeted sample, which has a considerably more uniform st…
Hydrogels for potential colon drug release by thiol-ene conjugate addition of a new inulin derivative.
2008
Inulin was chosen as a starting polymer for biocompatible, pH-sensitive and biodegradable hydrogels. Three INUDVSA-TT hydrogels were obtained by crosslinking inulin derivatives with trimethylolpropane tris(3-mercaptopropionate) under varying conditions. The resulting hydrogels were cell compatible, as demonstrated by MTS and trypan blue exclusion assays acting on Caco-2 cells, and were biodegraded by inulinase and esterase, thus suggesting their use as colonic drug delivery systems. 2-Methoxyestradiol, an anti-cancer drug, was soaked in INUDVSA-TT hydrogels and its in vitro release and apoptotic effect on Caco-2 cells were evaluated.
Spatial analysis of plant metabolism: Sucrose imaging within Vicia faba cotyledons reveals specific developmental patterns
2002
During legume embryogenesis the differentiation of the cotyledons proceeds gradually in a wave-like manner. The process is metabolically and genetically controlled and regulated by sugars. In order to perform a spatial and temporal analysis of the sugar distribution pattern a new method was developed to specifically measure sucrose directly in tissues via bioluminescence and single photon counting. This enabled a quantitative sucrose imaging with a resolution close to the single cell level. The procedure was applied on sections of Vicia faba cotyledons covering the main stages of histodifferentiation. Young embryos before the storage phase contained moderate levels of sucrose, which were ev…
Exopolysaccharide produced by Weissella confusa: Chemical characterisation, rheology and bioactivity
2019
Abstract The purpose of this study was to characterise the production of exopolysaccharide (EPS) by indigenous lactic acid bacteria (LAB) isolated from traditional Algerian dairy products and to evaluate their possible use in agri-foods. Among the collection of isolated strains, the strain Weissella confusa (W4) was selected for its ability to produce EPS once exposed to a sucrose culture medium. EPS produced were first isolated with a standardised method and further characterised in terms of molecular size, antioxidant activity, and rheological properties. Its direct implication in the texture and syneresis of acid milk gel was evaluated offering interesting industrial applications for its…
La Valle dei Templi in epoca medioevale. Caratterizzazione antropologica e paleopatologica delle sepolture antistanti in Tempio della Concordia
2021
Riassunto ― Il lavoro presenta i risultati delle analisi bio-archeologiche effettuate su resti scheletrici umani rinvenuti in quattordici sepolture di epoca medioevale rinvenute nel Parco Archeologico della Valle dei Templi di Agrigento (Sicilia). L’obiettivo è stato l’acquisizione delle informazioni necessarie per la ricostruzione del profilo biologico di ciascun individuo, al fine di determinarne il sesso, la stima dell’età biologica alla morte, la stima della statura e la valutazione delle patologie e degli indicatori di stress occupazionale mediante le correnti metodologie e tecniche diagnostiche di tipo antropologico. Sebbene il cattivo stato di conservazione di alcuni individui non ne…
Size dependence of the Josephson critical behavior in pyrolytic graphite TEM lamellae
2014
We have studied the transport characteristics of TEM lamellae of different widths obtained from a graphite sample with electrical contacts at the edges of the embedded interfaces. The temperature dependence of the resistance, as well as the current-voltage characteristics, are compatible with the existence of Josephson-coupled superconducting regions. The transition temperature at which the Josephson behavior sets in decreases with a decreasing interface width and vanishes for widths below 200 nm. This interface-size dependence provides an explanation for differences observed in the transport behavior of graphite-based samples with interfaces, and it appears to be related to the influence o…
Quantum phase slips in superconducting Nb nanowire networks deposited on self-assembled Si templates
2012
Robust porous silicon substrates were employed for generating interconnected networks of superconducting ultrathin Nb nanowires. Scanning electron microscopy analysis was performed to investigate the morphology of the samples, which constitute of polycrystalline single wires with grain size of about 10 nm. The samples exhibit nonzero resistance over a broad temperature range below the critical temperature, fingerprint of phase slippage processes. The transport data are satisfactory reproduced by models describing both thermal and quantum fluctuations of the superconducting order parameter in thin homogeneous superconducting wires.
Field dependence of the vortex core size probed by scanning tunneling microscopy
2016
We study the spatial distribution of the density of states (DOS) at zero bias N(r) in the mixed state of single and multigap superconductors. We provide an analytic expression for N(r) based on deGennes' relationship between DOS and the order parameter that reproduces well scanning tunneling microscopy (STM) data in several superconducting materials. In the single gap superconductor β-Bi2Pd, we find that N(r) is governed by a length scale ξH=φ0/2πH, which decreases in rising fields. The vortex core size C, defined via the slope of the order parameter at the vortex center, C (dΔ/dr|r→0)-1, differs from ξH by a material dependent numerical factor. The new data on the tunneling conductance and…
Size-dependent enhancement of superconductivity in Al and Sn nanowires: shape-resonance effect
2006
A shape-dependent superconducting resonance can be expected when an energy level associated with the transverse motion in a wire passes through the Fermi surface. We show that the recently observed width-dependent increase of ${T}_{c}$ in Al and Sn nanowires is a consequence of this shape-resonance effect.
In vitro performances and cellular uptake of clarithromycin nanocrystals produced by media milling technique
2018
Abstract Nanocrystal technology is one of a promising approach used to improve the solubility of poorly soluble drugs. In this study, media milling technique was used to produce clarithromycin nanocrystals via a bead milling machine. Various sizes of clarithromycin nanocrystals (250 nm–1 μm) were prepared using different milling times. The polymorphism and crystallinity of nanocrystals were characterized by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) techniques. The results indicated no polymorphic change after the milling process. However, the crystallinity of the obtained nanocrystals slightly decreased upon the milling time. The kinetic saturation solubili…