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51.
Liedert R Amundsen LK Hokkanen A Mäki M Aittakorpi A Pakanen M Scherer JR Mathies RA Kurkinen M Uusitalo S Hakalahti L Nevanen TK Siitari H Söderlund H 《Lab on a chip》2012,12(2):333-339
We present a high-throughput roll-to-roll (R2R) manufacturing process for foil-based polymethyl methacrylate (PMMA) chips of excellent optical quality. These disposable, R2R hot embossed microfluidic chips are used for the identification of the antibiotic resistance gene mecA in Staphylococcus epidermidis. R2R hot embossing is an emerging manufacturing technology for polymer microfluidic devices. It is based on continuous feeding of a thermoplastic foil through a pressurized area between a heated embossing cylinder and a blank counter cylinder. Although mass fabrication of foil-based microfluidic chips and their use for biological applications were foreseen already some years ago, no such studies have been published previously. 相似文献
52.
ABSTRACT Let R be an infinite semilocal ring. Then R is not finitely generated, neither the additive group R(+), nor the multiplicative group R? (of invertible elements) is minimax and at least one of these groups has infinite Prüfer rank. 相似文献
53.
We apply the coherent-mode expansion to correlation functions used to describe the coherence properties of supercontinuum generated in nonlinear ?bers. We show that the leading term of the expansion represents the quasi-coherent part of the ?eld while the quasi-stationary part is embedded into the higher-order modes. The evolution of the modal expansion and the number of modes needed to describe the supercontinuum ?eld are also discussed. 相似文献
54.
55.
Räisänen MT Runeberg N Klinga M Nieger M Bolte M Pyykkö P Leskelä M Repo T 《Inorganic chemistry》2007,46(23):9954-9960
High-yield synthesis of gold(I) thionato complexes, bis(pyridine-2-thionato)gold(I) chloride (1) and bis(pyridine-4-thionato)gold(I) chloride (2), are described. According to their solid-state structures, a linear coordination of Au(I), equiplanar coordination of the ligands and two weak gamma-agostic interactions are found in both of these complexes despite of different relative positions of N and S atoms in the pyridinethionato ligands. Density functional theory calculations on 1 and 2 reproduce the observed X-ray structures. Even though the C-H...Au interactions of Au(I) and two pyridine moieties (2.83 and 2.88 A in 1 and 2.86 A in 2) are relatively weak, according to calculations they seem to provide further stabilization for the coordination and orientation of the ligands. In 1 the shortest Au...Au distances of 3.50 A indicate that aurophilic interactions, even though weak, are present in the solid state, whereas in 2 these interactions are absent. 相似文献
56.
Dielectric elastomers are materials well known for their superior actuation behavior under applied electric field. The simplicity of material fabrication and clear working principle of dielectric elastomer actuators (DEAs) can offer various applications of dielectric elastomers. In this work, we have compared a number of different types of commercially available elastomers in terms of actuation performance. It was found that well‐known commercial rubbers like acrylonitrile‐butadiene rubbers (NBR) can offer higher actuation performance in DEAs than the frequently used dielectric elastomers, such as acrylic rubber and silicone. The acrylonitrile content of the NBR was found to play an important role in the dielectric and consequently actuation properties. More interestingly, we observed that addition of organic oil, such as dioctyl adipate, can greatly enhance the actuation performance. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
57.
Ngong K. Beyeh Domonkos Fehér Minna Luostarinen Christoph A. Schalley Kari Rissanen 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(3-4):381-394
The syntheses and characterization of new chiral tetrabenzoxazine and tetrakis-(dialkylaminomethyl) resorcinarenes can be
achieved through the reaction of resorcinarene with chiral amines and formaldehyde. In order to examine their host–guest chemistry,
chiral quaternary ammonium guests were synthesized by methylation of different amines and amino acid methyl esters through
a reductive methylation followed by addition of methyl iodide. Subsequent anion exchange of the iodide against tetraphenylborate
helps to improve solubility of the salts in organic solvents. After characterization in solution, mass spectrometry is used
to examine the resorcinarenes’ chemistry in the gas phase. Interesting implications of the fragmentation behavior for their
solution phase chemistry arise, for which a first example is presented. Ammonium ion binding is indicated by mass spectrometry.
Nevertheless, chiral recognition between the chiral hosts and pseudoracemic 1:1 mixtures of appropriately deuterium-labeled
chiral guest cations is however not observed. 相似文献
58.
制备了仲钨酸钠Na(10)H2W(12)O(42)·27H2O,用X射线衍射、Raman光谱及化学分析进行了表征.热分析的研究表明:该化合物热分解过程包括六个步骤.其中前四步为脱水步骤,温度分别为331,353,403及588K左右,而失水数分别为10H2O,9H2O,5H2O及4H2O;第五步可能为中间产物的相转变,温度为691K左右,第六步生成Na2W2O7和Na2W4O(13)的混合物,温度为733K左右.前五步中每一步的产物在标题化合物馆和溶液的气相中平衡处理之后,又都能得到标题化合物. 相似文献
59.
AB_2型星形杂臂偶氮液晶聚合物的合成及表征 总被引:1,自引:1,他引:1
通过原子转移自由基聚合(ATRP)与ATRP衍生物化学修饰结合的方法,合成了一系列AB2型星形杂臂偶氮液晶聚合物.其中,A为聚苯乙烯,B为聚6-[4-(4′-甲氧基苯基)偶氮苯氧基己酯](PMMAZO).合成分三步进行.首先,以ATRP方法得到ω-溴聚苯乙烯活性链PS(Br).然后对PS(Br)进行化学改性,得到带两个末端溴原子的聚苯乙烯活性链PS(Br)2·最后,以PS(Br)2作为双官能团大分子引发剂,引发6-[4-(4′-甲氧基苯基)偶氮苯氧基]己酯(MMAZO)发生ATRP聚合,得到星形杂臂PS(PMMAZO)2聚合物.进一步对聚合产物进行了GPC和1H-NMR分析.结果表明合成产物是预期的星形杂臂聚合物,产物分子量可控且分子量分布狭窄.同时,以DSC和POM表征了星形杂臂聚合物的液晶性. 相似文献
60.
Pulkkinen M Palmgrén JJ Auriola S Malin M Seppälä J Järvinen K 《Rapid communications in mass spectrometry : RCM》2008,22(2):121-129
This paper describes a straightforward and rapid on-line characterization using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS(n)) of the enzymatic degradation products of 2,2'-bis(2-oxazoline)-linked poly-epsilon-caprolactone (PCL-O). These new PCL-O polymers are expected to be used in a variety of pharmaceutical and biomedical applications since they are degraded enzymatically by surface erosion. PCL-O was polymerized in a three-step reaction and characterized by (1)H-NMR and size-exclusion chromatography (SEC). Solvent cast polymer films were exposed to enzymatic degradation in phosphate buffer (pH 7.5, 1% pancreatin). The enzymatic degradation of the polymer produced a wide variety of water-soluble oligomers which were separated and identified by HPLC/ESI-MS(n). Optimization of the gradient HPLC method resulted in effective separation of the oligomers. Furthermore, specific structures of the oligomers were clearly identified by tandem mass spectrometry. According to these results, ester bonds seem to be most sensitive to enzymatic degradation and, correspondingly, pancreatic lipase seems to be mainly responsible for the enzymatic erosion of the PCL-O films. This novel mass spectrometric method provides important knowledge about the enzymatic degradation process and structure of the polymer which is difficult to ascertain by other conventional methods. 相似文献