Commutability assessment of new standard reference materials (SRMs) for determining serum total 25-hydroxyvitamin D using ligand binding and liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays.

Commutability is where the measurement response for a reference material (RM) is the same as for an individual patient sample with the same concentration of analyte measured using two or more measurement systems. Assessment of commutability is essential when the RM is used in a calibration hierarchy or to ensure that clinical measurements are comparable across different measurement procedures and at different times. The commutability of three new Standard Reference Materials (SRMs) for determining serum total 25-hydroxyvitamin D [25(OH)D], defined as the sum of 25-hydroxyvitamin D [25(OH)D] and 25-hydroxyvitamin D [25(OH)D], was assessed through an interlaboratory study.

An additively manufactured locking fixation system for potential application in patient-specific implants.

This study introduces a novel technique to implement a locking hole system into AM patient-specific implants without the need of additional post-processing steps such as mechanical machining. This has the potential to decrease the time and cost of manufacturing these implants, providing surgeons with an additional option, that is better suited in cases where the underlying bone is already weakened or bone porosis is an inherent risk. A commercially available locking system was chosen and replicated using high-resolution X-ray CT.

Interlaboratory comparison of 25-hydroxyvitamin D assays: Vitamin D Standardization Program (VDSP) Intercomparison Study 2 - Part 1 liquid chromatography - tandem mass spectrometry (LC-MS/MS) assays - impact of 3-epi-25-hydroxyvitamin D on assay performance.

An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of liquid chromatography - tandem mass spectrometry (LC-MS/MS) assays used for the determination of serum total 25-hydroxyvitamin D (25(OH)D), which is the sum of 25-hydroxyvitamin D (25(OH)D) and 25-hydroxyvitamin D (25(OH)D). A set of 50 single-donor samples was assigned target values for concentrations of 25(OH)D, 25(OH)D, 3-epi-25-hydroxyvitamin D (3-epi-25(OH)D), and 24R,25-dihydroxyvitamin D (24R,25(OH)D) using isotope dilution liquid chromatography - tandem mass spectrometry (ID LC-MS/MS). VDSP Intercomparison Study 2 Part 1 includes results from 14 laboratories using 14 custom LC-MS/MS assays.

Low catalytic activity is insufficient to induce disease pathology in triosephosphate isomerase deficiency.

Triosephosphate isomerase (TPI) deficiency is a fatal genetic disorder characterized by hemolytic anemia and neurological dysfunction. Although the enzyme defect in TPI was discovered in the 1960s, the exact etiology of the disease is still debated. Some aspects indicate the disease could be caused by insufficient enzyme activity, whereas other observations indicate it could be a protein misfolding disease with tissue-specific differences in TPI activity.

Publisher Correction: Ballistic geometric resistance resonances in a single surface of a topological insulator.

In the original version of this Article, the second and third sentences of the first paragraph of the "Gate voltage and antidot period dependencies" section of the Results originally incorrectly read "The characteristic evolution of the sheet resistance ρ=ρ (B=0) with V shown for three antidot samples and an unpatterned reference sample in Fig. 3a. The maxima of ρ, located between V~0.

Ballistic geometric resistance resonances in a single surface of a topological insulator.

Transport in topological matter has shown a variety of novel phenomena over the past decade. Although numerous transport studies have been conducted on three-dimensional topological insulators (TIs), study of ballistic motion and thus exploration of potential landscapes on a hundred nanometer scale is for the prevalent TI materials almost impossible due to their low carrier mobility. Therefore, it is unknown whether helical Dirac electrons in TIs, bound to interfaces between topologically distinct materials, can be manipulated on the nanometer scale by local gates or locally etched regions.

Chemodiversity of exudate flavonoids in Cassinia and Ozothamnus (Asteraceae, Gnaphalieae).

The lipophilic exudates deposited on aerial parts of four species of Cassinia and twelve species of Ozothamnus (Asteraceae, Gnaphalieae) have been analyzed for the presence of flavonoid aglycones and some other phenolics. A total of 55 flavonoids were identified, including several rare flavonols. Flavonols are prevailing over flavones, and 8-O-substitution is dominant in both groups.

Levels and pattern of volatile organic nitrates and halocarbons in the air at Neumayer Station (70 degrees S), Antarctic.

Levels and patterns of C1-C4/C9 organic nitrates were measured for the first time in Antarctica. The sampling was done by adsorptive enrichment on Tenax TA followed by thermodesorption cold-trap high resolution capillary gas chromatography with electron capture detection. 2-70 1 air on-column have been analyzed this way.