Two approaches for purification of rosmarinic acid extracts, obtained from Lavandula vera MM cell biomass were investigated: adsorption on different Amberlite XAD resins and extraction with ethylacetate. Results showed that when ethylacetate extraction was used, 18.7 times higher level of purity compared to initial material was achieved. Similarly the obtained preparations from adsorption on Amberlite XAD-7 resin and elution with 80% ethanol contained 29.8% rosmarinic acid, which is 7.7 times higher purity compared to initial material. The precipitation of rosmarinic acid as Ca-rosmarinate was investigated as well. The obtained rosmarinic acid preparations were with low yield (34% of rosmarinic acid fell into sediment). 相似文献
Proof-of-concept studies towards recyclable nanoporous track-etched polymer membranes for template-synthesis of one-dimensional
colloidal gold rods indicate that surfactant-capped gold nanorods can be synthesised within and isolated from polyethylene
terephthalate (Lavsan) membranes using organic solvents with or without sonication. Thereafter, the same Lavsan membrance
can be re-used for at least one to two additional synthetic cycles.
An erratum to this article can be found at 相似文献
Two sets of emulsion particles have been synthesized. In the first set, surfactant free emulsion was used to directly synthesize PS‐PNIPAAM copolymer particles. In the second set, polystyrene particles with an ATRP initiator shell were first synthesized and subsequently grafted with PNIPAAM brushes. Swelling/deswelling behavior of both sets of particles was studied with respect to temperature and time. Monoliths with two different porosities were also formed by grafting and crosslinking of PNIPAAM chains on the aggregated particles and characterized. In all cases, swelling kinetics is sufficiently fast to use these supports for separation driven by temperature changes only. However, hindrance and cross‐linking is sensibly reducing the material performance.
Biomorphic TiC ceramics were covered with highly porous carbon, so-called carbide-derived carbon (CDC), by selective etching
of Ti with chlorine in a temperature range between 400° C and 1,200°C. Microporous carbon with narrow pore size distribution
was obtained at temperature ranging from 400°C to 800°C. Chlorination at higher temperatures leads to formation of mesopores
because of increased degree of order of the obtained CDC. A higher etching rate as well as higher degree of order at lower
reaction temperature was observed if a catalytically active metal like Fe or Ru was presented during the chlorination process.
This is associated with an increased amount of mesopores and with a decrease in specific surface area. Therefore, the CDC
processing in the presence of a catalyst offers another way to produce ordered carbon structures at lower temperatures. 相似文献
The dynamics of a 3D vibrated granular system is investigated. A new effect of resonant behaviour in the granular system is
reported. The resonant frequencies can cause vibro-induced segregation in a granular system. 相似文献
The three‐dimensional fabrication of optical waveguides has gained increasing interest in recent years to establish interconnections between electrical components on a very small scale where copper circuits encounter severe limitations. In this work the application of optically clear, organically modified porous silica monoliths and thin films as a host material for polymeric waveguides to be inscribed into the solid host structure by two‐photon‐induced photopolymerization is investigated. Porosity is generated using a lyotropic liquid crystalline surfactant/solvent system as a template for the solid silica material obtained by a sol–gel transition of a liquid precursor. In order to reduce the brittleness of the purely inorganic material, organic–inorganic co‐precursor molecules that contain poly(ethylene glycol) chains are synthesized and added to the mixture, which successfully suppresses macroscopic cracking and leads to flexible thin films. The structure of the thus‐obtained porous organic–inorganic hybrid material is investigated by atomic force microscopy. It is shown that the modified material is suitable for infiltration with photocurable monomers and functional polymeric waveguides can be inscribed by selective two‐photon‐induced photopolymerization. 相似文献
The concept of a steady state tokamak with plasma facing components (PFC) on the basis of liquid lithium circulation demands the decision of three tasks: lithium injection to the plasma, lithium ions collection before their deposition on the vacuum vessel and lithium returning to the injection zone. Main subject of paper is the investigations of Li collection by different types of limiters intersected the scrape-of-layer (SOL) in T-10 and T-11M tokamaks. For finding solution for this problem in T-11M and T-10, experiments have been applied with Li-, C-rail limiters and ring SS R-limiter-collector (T-11M). The efficiency of Li collection by limiters in T-11M and T-10 tokamaks was investigated by post mortem sample–witness analysis and (T-11M) by the use of the mobile graphite probe (limiter) as a recombination target in the stream of lithium ions. The characteristic depth of lithium penetration in the SOL area of T-11M is about 2 cm and 4 cm in SOL of T-10. The quantitative analysis of the sample–witnesses located on T-11M limiters showed that 60 ± 20% of the lithium injected during plasma operating of T-11M had been collected by limiters. It confirms an opportunity of the lithium ions collection by limiters in tokamak SOL. 相似文献
The aim of the work was to elucidate the nature of charge-selective properties of macroporous composite inorganic membranes modified with nanoparticles of hydrated zirconium dioxide. The membranes have been investigated using methods of standard contact porosimetry, potentiometry, electron microscopy and small-angle X-ray scattering. The ion exchanger has been found to deposit inside pores of ceramics. Differential curves of pore volume distribution have been resolved using Lorentz functions; each maximum has been related to structure elements of the matrix and ion exchanger by means of calculations according to homogeneous and heterogeneous geometrical models. It was found that the voids, the radius of which is 4 to 8 nm, are responsible for charge selectivity of the composite membranes. These pores are formed due to blocking of macropores of ceramics with aggregates of nanoparticles of the ion exchanger; the radius of these aggregates is 20 to 24 nm. The membranes were applied to desalination of the solution containing NaCl. The removal degree of the salt from the solution reached 95% and 9% for the composite and unmodified membranes, respectively. 相似文献
In the present article, we propose a ferroelectric‐based frequency mixer capable of reconfigurable functioning, a key trait in multi frequency band coverage, based on the nonlinear dielectric properties of BaSnxTi1?xO3 ceramics. According to the properties of BaSnxTi1?xO3 solid solutions, an optimum composition was selected to demonstrate the applicability as a discrete passive mixer with a simple coplanar geometry. A prototype device, with four coplanar capacitors, connected in a circular electric circuit was built on the surface of the selected ceramic. In this configuration, mixing products of the pumping and working signals were obtained and characterized. 相似文献