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211.
Surface free energy of two different samples of solidified sulfur (yellow and orange) was investigated, using several approaches for its determination. It was found that values determined about two decades ago for surface free energy of sulfur were overestimated. From current studies the apparent value of this energy ranges between 30 and 60 mJ/m(2), depending on the kind and age of the sulfur samples (up to 1 year old) and/or the probe liquid used for the advancing and receding contact angle measurements. The energy has been calculated from van Oss et al.'s approach (Lifshitz-van der Walls, electron-donor, and electron-acceptor components), the contact angle hysteresis approach proposed by Chibowski, the equation of Owens and Wendt (dispersion and polar components), and Neumann et al.'s equation of state, as well as from equilibrium contact angle using Tadmor's procedure. The lowest values of the energy for 3-day- and 3-month-old samples of sulfur were calculated from the equation of state; they were below the range mentioned above. 相似文献
212.
Jan Leipert Philipp T. Kaulich Max K. Steinbach Britta Steer Konrad Winkels Christine Blurton Dr. Matthias Leippe Dr. Andreas Tholey 《Angewandte Chemie (International ed. in English)》2023,62(28):e202301969
While most nanoproteomics approaches for the analysis of low-input samples are based on bottom-up proteomics workflows, top-down approaches enabling proteoform characterization are still underrepresented. Using mammalian cell proteomes, we established a facile one-pot sample preparation protocol based on protein aggregation on magnetic beads and intact proteoform elution using 40 % formic acid. Performed on a digital microfluidics device, the workflow enabled sensitive analyses of single Caenorhabditis elegans nematodes, thereby increasing the number of proteoform identifications compared to in-tube sample preparation by 46 %. Label-free quantification of single nematodes grown under different conditions allowed to identify changes in the abundance of proteoforms not distinguishable by bottom-up proteomics. The presented workflow will facilitate proteoform-directed analysis on samples of limited availability. 相似文献
213.
A proper evaluation of the uncertainty associated to the quantification of micropollutants in the environment, like Polycyclic Aromatic Hydrocarbons (PAHs), is crucial for the reliability of the measurement results. The present work describes a comparison between the uncertainty evaluation carried out according to the GUM uncertainty framework and the Monte Carlo (MC) method. This comparison was carried out starting from real data sets obtained from the quantification of benzo[a]pyrene (BaP), spiked on filters commonly used for airborne particulate matter sampling. BaP was chosen as target analyte as it is listed in the current European legislation as marker of the carcinogenic risk for the whole class of PAHs. 相似文献
214.
215.
Rameshwar Adhikari Matthias Buschnakowski Sven Henning Sylvia Goerlitz Trinh An Huy Werner Lebek Reinhold Godehardt Georg Hannes Michler Ralf Lach Kalman Geiger Konrad Knoll 《Macromolecular rapid communications》2004,25(5):653-658
Summary: The morphology and tensile deformation behaviour of a highly asymmetric styrene/butadiene star block copolymer (polystyrene (PS) content = 74%) containing random PS‐co‐PB (polybutadiene) copolymer as a rubbery phase were investigated. The existence of double yielding, similar to that observed in some semicrystalline polymers, was detected in this nanostructured amorphous polymer. The observed phenomenon may be correlated with two different micromechanical processes taking place at the initial stage of deformation.
216.
Konrad Schmüdgen 《Journal of Geometry and Physics》1999,31(4):963-264
Let (Γ, d) be the 3D-calculus or the 4D±-calculus on the quantum group SUq (2). We describe all pairs (π, F) of a *-representation π of
(SUq(2)) and of a symmetric operator F on the representation space satisfying a technical condition concerning its domain such that there exist a homomorphism of first order differential calculi which maps dx into the commutator [iF, π(x)] for x ε
(SUq (2)). As an application commutator representations of the two-dimensional left-covariant calculus on Podles quantum 2-sphere Sqc2 with c = 0 are given. 相似文献
217.
Nitrosyl fluoride and nitrosyl chloride are crystallized from the melt. The crystal structures are made up by ON–F and ON–Cl molecules with only weak intermolecular interactions. ON–F: a = 411.0(2), b = 439.1(2), c = 1020.2(4) pm, space group P212121. ON–Cl: a = 1084.0(2), b = 543.5(1), c = 409.3(1) pm, space group Pnma. Both molecules have considerable longer nitrogen‐halogen bonds and shorter nitrogen‐oxygen bonds in the solid than in the gaseous state. These differences between gas and solid state structure are expressed much stronger in ON–Cl than in ON–F. ON–F functions as a solvate molecule in the cation of NO+(NOF)2IF8–. Here the ON–F molecule has a drastically shortened NO and lengthened NF bond. NO+(NOF)2IF8–: a = 618.9(1), b = 1039.4(1), c = 2842.1(1) pm, space group P212121. 相似文献
218.
219.
Beat Grolimund Emanuele Boselli Konrad Grob Renato Amad Giovanni Lercker 《Journal of separation science》1998,21(7):378-382
Solvent trapping reconcentrates volatile components after injection or on-line transfer of large volumes. When an early vapor exit is used, typically after a 5–10 m × 0.53 mm i.d. uncoated precolumn, the solvent trapping process differs from that described previously. The visual experiments and the conclusions drawn therefrom, as described in a previous paper, are supplemented with chromatographic results. They show that even hexane can be quantitatively analyzed in 250 μl of a pentane solution. Injection of a volume of 250 μl by vaporizer/precolumn solvent splitting was used in the analysis of gasoline in drinking water. Conditions for the transfer of a 1000 μl volume can easily be adjusted through detection of the front end of the flooded zone by a thermocouple mounted on the outer wall of the precolumn. 相似文献
220.