Radiocapitellar and Ulnotrochlear Pressures Increase in a Radial Head Fracture Model: A Cadaveric Biomechanical Analysis.

BACKGROUND: Changes in intra-articular pressure have not been previously described in relation to the management of radial head fractures. We hypothesized that pressure within the radiocapitellar and ulnotrochlear joints would increase with progressive radial head resection, mimicking a displaced radial head fracture, in a cadaveric model. METHODS: Ten cadaveric specimens were tested. Intra-articular pressure sensors were used to measure pressure within the radiocapitellar and ulnotrochlear joints with the forearm in full supination. The elbow was loaded to 100 N in extension, 45° of flexion, and 90° of flexion under the following conditions: (1) intact radial head, (2) 20% radial head resection, (3) 40% radial head resection, and (4) 100% radial head resection. RESULTS: The distribution of pressure between the radiocapitellar and ulnotrochlear joints did not change with sequential, partial resection of the radial head (radiocapitellar joint, between 48.92% and 53.79%; ulnotrochlear joint, between 46.21% and 51.08%). After 20% resection, radiocapitellar peak contact pressure (PCP) increased by 22% (from 1,410 to 1,721.5 kPa) and ulnotrochlear PCP increased by 36% (from 1,319 to 1,797.5 kPa). After 40% resection, radiocapitellar PCP increased by 123% (from 1,410 to 3,145 kPa; p = 0.0003) and ulnotrochlear PCP increased by 105% (from 1,319 to 2,702 kPa; p = 0.007). Ulnotrochlear PCP increased by a total of 159% after complete radial head resection (from 1,319 to 3,415.5 kPa; p = 0.003). CONCLUSIONS: Pressures in the radiocapitellar and ulnotrochlear joints were equally distributed with an intact radial head and after partial resection. Radiocapitellar and ulnotrochlear pressures increased with increasing radial head resection, significantly exceeding 100% of normal after radial head resection of 40% of the anterolateral diameter. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

[Application of gas chromatography-high resolution quadrupole time of flight mass spectrometry to the analysis of benzaldehyde, benzyl alcohol acetophenone and phenylacetaldehyde in complex aromatic samples].

The study focuses on the quantitative analytical characterization of benzaldehyde, benzyl alcohol, acetophenone and phenylacetaldehyde in complex aromatic samples by gas chromatography-high resolution quadrupole time of flight mass spectrometry (GC-QTOF MS). The four compounds in real sample were accurately qualified and quantified through a comprehensive analysis of the GC retention times and the accurate masses of the ion fragments obtained by the high resolution MS. The new method therefore effectively avoids the interference of the real sample substrate, which reduces the accuracy of the analysis results. The peak area of the characteristic ion fragment for each compound was used for quantitation calculation. The MS signal responses of the four compounds showed good linear relationships with the corresponding mass concentrations and the linear regression coefficients were greater than 0. 99. The method recoveries were 87. 97% - 103.01%. The limits of detection (LODs) were 0. 01, 0. 03, 0. 02 and 0. 01 mg/L for benzaldehyde, benzyl alcohol, acetophenone and phenylacetaldehyde respectively. The contents of the four compounds in three real samples were analyzed. The study provided a new strategy for oxygenate analysis in complex aromatic samples using GC-QTOF MS. By measuring the accurate masses, the new method reduces the reliance on chromatographic separation ability and makes up the shortcomings of the traditional GC-MS methods.

A nanodiamond/CNT-SiC monolith as a novel metal free catalyst for ethylbenzene direct dehydrogenation to styrene.

A novel nanodiamond/CNT-SiC monolith catalyst has been prepared by a facile two-step approach. The as-synthesized monolith afforded high activity and stability for ethylbenzene direct dehydrogenation to styrene, showing its potential application as a metal free catalyst in gaseous catalytic reactions.

[Determination of oxygenates in syngas-to-olefin products by solid phase extraction combined with gas chromatography-mass spectrometry].

The syngas-to-olefin (SGTO) products mainly consist of hydrocarbons along with small amounts of oxygenates as the byproducts. A C18 solid-phase extraction (SPE) column was used for oxygenates enrichment in SGTO products. As the hydrophobic compounds, the hydrocarbons had stronger interaction with a C18 SPE column than oxygenates. Under the optimized elution conditions, the oxygenates were first eluted from the C18 SPE column with 60% (v/v) methanol solution. The fraction of oxygenates was then analyzed with gas chromatography-mass spectrometry (GC-MS) for qualification and gas chromatography-hydrogen flame ionization detection (GC-FID) for quantification. The FID response factors of n-alkanol and n-ketone were used for alkanols and ketones quantitative calculation and the method recoveries were 88%-98% and 64%-87% respectively. In the range of 197-4,785 mg/L, good linear relationships of the FID responses with the corresponding mass concentrations of the standard samples were obtained with the linear regression coefficients greater than 0.99. Sixty-seven oxygenates were analyzed qualitatively and quantitatively. The results showed that the fraction of the oxygenates mainly consists of alkanols and ketones. The total content of the oxygenates in SGTO products was 6.2%. The enrichment method only requires a very small amount of sample and the total process can be completed within 10 min. The analysis results of SGTO product studies can provide the necessary basic data for SGTO catalysts and dynamics studies.