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91.
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93.
A new bifunctional chain transfer agent (CTA) containing alkyne end groups was designed, synthesized and used for direct synthesis of clickable telechelic polymers. Good control of reversible addition-fragmentation chain transfer (RAFT) polymerization of N-(2-hydroxypropyl)methacrylamide (HPMA) was achieved by using the new CTA, as indicated by a linear increase of number average molecular weight (Mn) with conversion and low polydispersity (PDI) (<1.1). In particular, enzymatically degradable multiblock HPMA polymers were readily prepared by subsequent reaction with αω, -diazido oligopeptide (GFLG) sequence via Cu(I) catalyzed alkyne-azide cycloaddition. Upon exposure of high molecular weight fractions of multiblock polyHPMA to papain or cathepsin B, the polymer was degraded into segments of molecular weight and narrow polydispersity similar to those of the initial telechelic polyHPMA. 相似文献
94.
Dragica M. Mini? Dušan M. Mini?Tomáš ?ák Pavla RoupcováBohumil David 《Journal of magnetism and magnetic materials》2011,323(5):400-404
Thermal stability and crystallization of the Fe81B12Si4C2 alloy were investigated in the temperature range 25-700 °C by the XRD and Mössbauer analysis. It was shown that on heating the as-prepared amorphous Fe81B12Si4C2 alloy undergoes thermal stabilization through a series of structural transformations involving the process of stress-relieving (temperature range 200-400 °C), followed by a loss of ferromagnetic properties (Curie temperature at 420 °C) and finally crystallization (temperature range 450-530 °C). The process of crystallization begins by formation of two crystal phases: Fe3B and subsequently Fe2B, as well as a solid solution α-Fe(Si). With increase in annealing temperature, the completely crystallized alloy involved only two phases, Fe2B and solid solution α-Fe(Si).XRD patterns established a difference in phase composition and size of the formed crystallites during crystallization depending on the side (fishy or shiny) of the ribbon. The first nuclei of the phase α-Fe3Si were found on the shiny side by XRD after heat treatment even at 200 °C but the same phase on the fishy side of ribbon was noticed after heat treatment at 450 °C. The largest difference between the contact and free surface was found for the Fe2B phase crystallized by heating at 700 °C, showing the largest size of crystallites of about 130 nm at 700 °C on the free (shiny) surface. 相似文献
95.
Andrea F. G. Gargano Michal Kohout Pavla Macíková Michael Lämmerhofer Wolfgang Lindner 《Analytical and bioanalytical chemistry》2013,405(25):8027-8038
We report a chiral high-performance liquid chromatographic enantioseparation method for free α-aminophosphonic, β-aminophosphonic, and γ-aminophosphonic acids, aminohydroxyphosphonic acids, and aromatic aminophosphinic acids with different substitution patterns. Enantioseparation of these synthons was achieved by means of high-performance liquid chromatography on CHIRALPAK ZWIX(+) and ZWIX(-) (cinchona-based chiral zwitterionic ion exchangers) under polar organic chromatographic elution conditions. Mobile phase characteristics such as acid-to-base ratio, type of counterion, and solvent composition were systematically varied in order to investigate their effect on the separation performance and to achieve optimal separation conditions for the set of analytes. Under the optimized conditions, 32 of 37 racemic aminophosphonic acids studied reached baseline separation when we employed a single generic mass-spectrometry-compatible mobile phase, with reversal of the elution order when we used (+) and (-) versions of the chiral stationary phase. Figure
New zwitterionic ion-exchangers can separate free amino phosphonic acids and a change from Chiralpak ZWIX(+) to ZWIX(-) allows reversal of enantiomer elution order 相似文献
96.
Radim Pilař Pavla Honcová Petr Koštál Galina Sádovská Ladislav Svoboda 《Journal of Thermal Analysis and Calorimetry》2014,118(1):485-491
The methods of heat capacity data determination from differential scanning calorimetry measurements are described. The negative effects increasing uncertainty of heat capacity determination are mentioned. Modified stepwise method was described and verified using molybdenum, copper, and gold standards. Modified stepwise method provides better accuracy of C p values compared to continuous and stepwise method. 相似文献
97.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
98.
Pavla Križman Lavrič Brigita Tomšič Barbara Simončič Marijn M. C. G. Warmoeskerken Dragan Jocic 《Cellulose (London, England)》2012,19(1):273-287
An innovative strategy for functional finishing of cotton involves application of stimuli-responsive surface modifying system
based on temperature- and pH-responsive poly-NiPAAm/chitosan microgel. The stimuli-responsiveness implied to cotton is the
consequence of swelling/collapse of the microgel particles incorporated to the fibre surface, which produces an active liquid
management system. The performance of functionalized cotton fabric in terms of liquid management properties was assessed by
choosing appropriate techniques (water uptake; thin-layer wicking; water retention capacity; and drying capability) and discussion
of the results was based on the types of water that are expected to be present in hydrated cotton and stimuli-responsive microgel. 相似文献
99.
Synytsya A Král V Matejka P Poucková P Volka K Sessler JL 《Photochemistry and photobiology》2004,79(5):453-460
The use of near-infrared (NIR)-excited Fourier-transform (FT) Raman spectroscopy as a technique for evaluating the extent of photosensitizer localization in tumor (human pancreatic adenocarcinomas)-bearing mice has been tested using lutetium(III) texaphyrin analogue Lu-T2B2Tex. The complex was injected subcutaneously in the form of three injections given during the course of 3 days. The kinetics of biodistribution were then followed over a time scale of 1-6 days. The NIR-FT-Raman spectra of tissue samples obtained from the xenographic tumor, muscle, heart, brain, liver, spleen, kidney and blood were recorded and used to identify the presence of Lu-T2B2Tex in these tissues. Five Raman sensitizer markers were used to estimate the relative content of Lu-T2B2Tex in tumor at various postinjection times. UV-Visible (Vis) absorption spectroscopic detection of this sensitizer in tissue extracts was applied as a conventional method. Both spectroscopic methods were in good agreement with each other and confirm that Lu-T2B2Tex localizes well in tumor tissue. Maximal drug content was observed 3 days after the final injection. This time delay seems to be optimal for tumor irradiation in photodynamic therapy. 相似文献
100.
This contribution is aimed at providing a survey of the limitations of the peak-height technique. It is shown that the shape and the slope of calibration curves give a precise insight into the separation mechanism and can warn the analyst against improper selection of background electrolyte or sample dilution. This work investigates three typical situations where the sample contains (i) the minor analyte only, (ii) the minor analyte and a nonstacking bulk component, (iii) the minor analyte and a stacking bulk component, and various modes of measurement of the calibration curves differing in the medium used for the dilution of the original sample (water, background electrolyte, solution of the bulk component). Based on simple theoretical models, the shapes of the calibration curves are derived and elucidated for all modes, clearly demonstrating that only a few modes can provide useful results while most of them seem useless for quantitation. The knowledge of regularities affecting the character of calibration curves can be used for optimization of the analysis so that reliable results and highest attainable sensitivity can be reached. The outcome of this study brings a clear instruction how to successfully quantitate trace analytes even in samples with a complex and variable matrix*. 相似文献