The international joint project HYCREF (Contract No. G6RD-CT-2002-00854), funded by the European Commission in the 5th Framework programme, aimed to develop methods to prepare homogeneous and stable reference materials of water, soil, and waste contaminated with mineral oil hydrocarbons and to certify the mineral oil content by gas chromatographic methods. The results of a feasibility study for the preparation of three soil reference materials are discussed in this paper, and for the preparation of three waste reference materials in the second part (Koch et al., Accred Qual Assur submitted for publication). The soil materials were selected to represent different soil types and contamination levels. The project plan set three requirements for these reference materials: uncertainty in the mineral oil content resulting from the certification exercise <5%, a sample inhomogeneity of <3% and a minimum long-term stability of 5 years. For the most part, these requirements were met within this project. 相似文献
REALISIS is a software system for reagent selection, library design, and profiling, developed to fit the workflow of bench chemists and medicinal chemists. Designed to be portable, the software offers a comprehensive graphical user interface and rapid, integrated functionalities required for reagent retrieval and filtering, product enumeration, and library profiling. REALISIS is component-based, consisting of four main modules: reagent searching; reagent filtering; library enumeration; and library profiling. Each module allows the chemist to access specific functionalities and diverse filtering and profiling mechanisms. By implementing the entire process of reagent selection, library design, and profiling and by integrating all the necessary functionalities for this process, REALISIS cuts the time required to design combinatorial and noncombinatorial libraries from several days to a few hours. 相似文献
In every aseptic filling application, the sterile transfer of goods into the aseptic area is a challenge, and there are many different ways to do it.
With isolator technology a higher sterility assurance level (SAL) is achieved. This SAL is only as good as the weakest segment in the chain of manufacturing. The transfer of goods into and out of the isolator is one of these critical segments.
Today different techniques, some already well established, others still very new, are available on the market like: dry heat tunnel, autoclave, pulsed light, rapid transfer systems (RTP), H2O2 tunnel, UV light, etc. all these systems are either not applicable for continuous transfer, only good for heat-compatible materials like glass, or do not guarantee a 6 log spore reduction.
E-Beam opens new perspectives in this field. With E-beam technology it is possible to transfer heat-sensitive (plastic), pre-sterilised materials at high speed, continuously into an aseptic area.
E-Beam unifies three different technologies, that result in a very efficient and high-speed decontamination machine designed for the pharmaceutical industry. First, there is the electron beam that decontaminates the goods and an accurate shielding that protects the surrounding from this beam. Second, there is the conveyor system that guarantees the output and the correct exposure time underneath the beam. And third, there is the isolator interface to provide correct differential pressure and clean air inside the tunnel as well as the decontamination of the tunnel with H2O2 prior to production.
The E-beam is a low-energy electron beam, capable of decontaminating any kind of surface. It penetrates only a few micrometers into the material and therefore does not deform the packaging media.
Currently, machines are being built to transfer pre-sterilised syringes, packed in plastic tubs with a Tyvek cover into an aseptic filling isolator with the following data: decontamination efficiency of 106 (6 log spore reduction), decontamination speed of 6 tubs (600 syringes) per minute.
This is just one of many applications for this new technology. 相似文献
Upper and lower bounds are given for the behaviour of the Poisson-Boltzmann potential of a highly charged, cylindrical polyelectrolyte in excess salt solution as the salt correntration or cylinder radius tends to zero. The exact singular behaviour of the potential very close to the cylinder is given in terms of a delta function. 相似文献
Spherical molecularly imprinted polymer particles obtained via precipitation polymerization, were introduced as a pseudostationary phase in capillary electrophoresis (CE) to study molecular recognition. Analyses were performed via a partial filling technique using (+)-ephedrine-imprinted microspheres (100-200 nm) which were polymerized from methacrylic acid and 1,1,1-Tris(hydroxymethyl)propanetrimethacrylate using acetonitrile as the solvent. The influence of pH and the modifier content on the separation was investigated. A 0.1% w/v suspension in an aqueous 10 mM phosphate buffer (pH 2.5 with 40% acetonitrile) was hydrodynamically injected into the CE system (80% of the effective capillary length) and led to full baseline separation of racemic ephedrine within 10 min. 相似文献
Fluorescent pyrido[2,1-i]purines can in principle be obtained via Michael-addition of a suitable anion of a purine derivative to an acetylenic ester, followed by based-catalyzed cyclization, as depicted in Scheme II. 6-Substituted purine-derivatives are obtained via nucleophilic substitution of 6-chloro- and 6-methylsulfonylpurine ( and ). In the presence of methyl propiolate and sodium methoxide, before cyclization, two consecutive Michael-additions take place, leading to and . With substituted acetylenic esters, cyclization occurs after one Michael-addition. Michael-additions with ethylenic esters did not lead to expected cyclization products, except in cases where oxidation took place. -For the conversion of the pyrido[2,1-i]purines into the corresponding ribosides protection against nucleophilic attack was necessary. 相似文献
The complexes (RN=CH-CH=NR)Co(NO)(CO) with R = isopropyl, 2,6-diisopropylphenyl, or p-tolyl are chemically and electrochemically reducible to radical anions at potentials which strongly depend on R. The DFT calculated structure for the neutral compound with R = iPr agrees with the experiment, and the computed structure of the anion radical reveals changes according to a reduction of the R-DAB ligand. EPR results confirm an (R-DAB)-based singly occupied molecular orbital in [(RNCHCHNR)Co(NO)(CO)](.-), with minor but detectable contributions from NO as supported by IR spectroelectrochemistry and as quantified by DFT spin density calculations. The calculations indicate increasingly stabilized CO, NO, and RNCHCHNR pi* acceptor orbitals, in that order. On the basis of TD-DFT (time-dependent density functional theory) calculations, the lowest-lying excited states are assigned to metal-to-(R-DAB) charge transfer transitions while bands due to the metal-to-nitrosyl charge transfer occur at higher energies but still in the visible region. Resonance Raman studies were used to probe these assignments. 相似文献
Infrared and Raman spectroscopy have been used to characterise synthetic hydrotalcites of formula Cu(x)Zn(6 - x)Al2(OH)16(CO3) x 4H2O. The spectra have been used to assess the molecular assembly of the cations in the hydrotalcite structure. The spectra may be conveniently subdivided into spectral features based (a) upon the carbonate anion (b) the hydroxyl units (c) water units. The Raman spectra of the hydroxyl-stretching region enable bands to be assigned to the CuOH, ZnOH and AlOH units. It is proposed that in the hydrotalcites with minimal cationic replacement that the cations are arranged in a regular array. For the Cu(x)Zn(6 - x)Al2(OH)16(CO3) x 4H2O hydrotalcites, spectroscopic evidence suggests that 'islands' of cations are formed in the structure. In a similar fashion, the bands assigned to the interlayer water suggest that the water molecules are also in a regular well-structured arrangement. Bands are assigned to the hydroxyl stretching vibrations of water. Three types of water are identified (a) water hydrogen bonded to the interlayer carbonate ion (b) water hydrogen bonded to the hydrotalcite hydroxyl surface and (c) interlamellar water. It is proposed that the water is highly structured in the hydrotalcite as it is hydrogen bonded to both the carbonate anion and the hydroxyl surface. 相似文献