An evaluation of the Advanced micro-osmometer is presented. This instrument has been shown to have an excellent analytical precision (within-run CV = 0.59%, between-day CV = 0.58%). It is accurate over an analytical range of 0-2000 mmol/kg of osmolality shown by linearity studies and split sample correlations against vapour pressure osmometry, freezing point osmometry and an external quality assurance programme. Analytical errors due to operator technique are almost eliminated because of good instrument design. Preliminary results on whole-blood osmolality are included. The required sample size of 20 mul permits osmolality measurements on most clinical samples. It is concluded that the Advanced micro-osmometer satisfies laboratory requirements.
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http://dx.doi.org/10.1155/S1463924689000167 | DOI Listing |
J Phys Chem A
January 2025
Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
We report a new NMR method for treating two-site chemical exchange involving half-integer quadrupolar nuclei in a solution. The new method was experimentally verified with extensive Na ( = 3/2), K ( = 3/2), and Rb ( = 3/2) NMR results from alkali metal ions (Na, K, and Rb) in a solution over a wide range of molecular tumbling conditions. In the fast-motion limit, all allowed single-quantum NMR transitions for a particular quadrupolar nucleus are degenerate giving rise to one Lorentzian signal.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Institute of Organic Chemistry, University Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany.
In ion-pair catalysis, the last intermediate structures prior to the stereoselective transition states are of special importance for predictive models due to the high isomerization barrier between - and -substrate double bonds connecting ground and transition state energies. However, in prior experimental investigations of chiral phosphoric acids (CPA) solely the early intermediates could be investigated while the key intermediate remained elusive. In this study, the first experimental structural and conformational insights into ternary complexes with CPAs are presented using a special combination of low temperature and relaxation optimized N HSQC-NOESY NMR spectroscopy to enhance sensitivity.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
The strategy of designing efficient room-temperature phosphorescence (RTP) emitters based on hydrogen bond interactions has attracted great attention in recent years. However, the regulation mechanism of the hydrogen bond on the RTP property remains unclear, and corresponding theoretical investigations are highly desired. Herein, the structure-property relationship and the internal mechanism of the hydrogen bond effect in regulating the RTP property are studied through the combination of quantum mechanics and molecular mechanics methods (QM/MM) coupled with the thermal vibration correlation function method.
View Article and Find Full Text PDFAdv Mater
January 2025
Key Laboratory of Advanced Materials Technologies, International (HongKong Macao and Taiwan) Joint Laboratory on Advanced Materials Technologies, College of Materials Science and Engineering, Fuzhou University, Fuzhou, Fujian, 350108, China.
Hydrogels have received great attention due to their molecular designability and wide application range. However, they are prone to freeze at low temperatures due to the existence of mass water molecules, which can damage their flexibility and transparency, greatly limiting their use in cold environments. Although adding cryoprotectants can reduce the freezing point of hydrogels, it may also deteriorate the mechanical properties and face the risk of cryoprotectant leakage.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
Searching for single-molecule magnets (SMM) with large effective blocking barriers, long relaxation times, and high magnetic blocking temperatures is vitally important not only for the fundamental research of magnetism at the molecular level but also for the realization of new-generation magnetic memory unit. Actinides (An) atoms possess extremely strong spin-orbit coupling (SOC) due to their 5 orbitals, and their ground multiplets are largely split into several sublevels because of the strong interplay between the SOC of An atoms and the crystal field (CF) formed by ligand atoms. Compared to TM-based SMMs, more dispersed energy level widths of An-based SMMs will give a larger total zero field splitting (ZFS) and thus provide a necessary condition to derive a higher .
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