Thermal Decomposition of 2,3,3,3- and <i>trans</i>-1,3,3,3-Tetrafluoropropenes

The thermal decomposition reactions of 2,3,3,3- and <i>trans</i>-1,3,3,3-tetrafluoropropenes (TFPs) have been studied both experimentally and computationally to elucidate their kinetics and mechanism. The experiments were performed by observing the temporal profiles of HF produced in the decomposition of the tetrafluoropropenes behind shock waves at temperatures of 1540–1952 K (for 2,3,3,3-TFP) or 1525–1823 K (for <i>trans</i>-1,3,3,3-TFP) and pressure of 100–200 kPa in Ar bath. The reaction pathways responsible for the profiles were explored based on quantum chemical calculations. The decomposition of 2,3,3,3-TFP was predicted to proceed predominantly via direct 1,2-HF elimination to yield CHCCF₃, while <i>trans</i>-1,3,3,3-TFP was found to decompose to HF and a variety of isomeric C₃HF₃ products including CHCCF₃, CF₂CCHF, CCHCF₃, and CF₂CHCF. The C₃HF₃ isomers can subsequently decompose to either CF₂ + CHCF or CF₂CC + HF products. Multichannel RRKM/master equation calculations were performed for the identified decomposition channels. The observed formation rates and apparent yields of HF are shown to be consistent with the computational predictions

Time-Resolved Broadband Cavity-Enhanced Absorption Spectroscopy behind Shock Waves

A fast and sensitive broadband absorption technique for measurements of high-temperature chemical kinetics and spectroscopy has been developed by applying broadband cavity-enhanced absorption spectroscopy (BBCEAS) in a shock tube. The developed method has effective absorption path lengths of 60–200 cm, or cavity enhancement factors of 12–40, over a wavelength range of 280–420 nm, and is capable of simultaneously recording absorption time profiles over an ∼32 nm spectral bandpass in a single experiment with temporal and spectral resolutions of 5 μs and 2 nm, respectively. The accuracy of the kinetic and spectroscopic measurements was examined by investigating high-temperature reactions and absorption spectra of formaldehyde behind reflected shock waves using 1,3,5-trioxane as a precursor. The rate constants obtained for the thermal decomposition reactions of 1,3,5-trioxane (to three formaldehyde molecules) and formaldehyde (to HCO + H) agreed well with the literature data. High-temperature absorption cross sections of formaldehyde between 280 and 410 nm have been determined at the post-reflected-shock temperatures of 955, 1265, and 1708 K. The results demonstrate the applicability of the BBCEAS technique to time- and wavelength-resolved sensitive absorption measurements at high temperatures

Additional file 1: of Relationship between history of coronary heart disease at dialysis initiation and onset of events associated with heart disease: a propensity-matched analysis of a prospective cohort study

The dataset included the patient profiles, comorbidities, medications, and laboratory data at dialysis initiation. (XLSX 202 kb

Can Wound Exudate from Venous Leg Ulcers Measure Wound Pain Status?: A Pilot Study

<div><p>We investigated the associations between the self-evaluated pain status and two pain biomarker candidates, nerve growth factor and S100A8/A9, in exudate from venous leg ulcer to finally develop an objective pain evaluation method. Patients with venous leg ulcer participated in this cross-sectional observational study conducted between April and October 2014 at two medical facilities. During routine wound care, each participant self-evaluated their pain status at each examination using the 10-point numerical rating scale (present pain intensity) and the short-form McGill Pain Questionnaire 2 (continuous pain, intermittent pain, neuropathic pain, affective descriptors, and total score). Venous leg ulcer exudate sample was collected after wound cleansing. The nerve growth factor and S100A8/A9 concentrations in the venous leg ulcer exudate were measured by enzyme-linked immunosorbent assay and standardized according to the wound area. The association between each pain status and the two standardized protein concentrations was evaluated using Spearman’s correlation coefficient. In 30 sample collected from 13 participants, the standardized nerve growth factor concentration was negatively correlated with continuous pain (<i>ρ</i> = -0.47, <i>P</i> = 0.01), intermittent pain (<i>ρ</i> = -0.48, <i>P</i> = 0.01), neuropathic pain (<i>ρ</i> = -0.51, <i>P</i> = 0.01), and total score (<i>ρ</i> = -0.46, <i>P</i> = 0.01). The standardized S100A8/A9 concentration was positively correlated with present pain intensity (<i>ρ</i> = 0.46, <i>P</i> = 0.03) and continuous pain (<i>ρ</i> = 0.48, <i>P</i> = 0.03). Thus, these two proteins may be useful for objective evaluation of wound pain in venous leg ulcer patients.</p></div

Naturally Occurring Structural Isomers in Serum IgA1 <i>O</i>-Glycosylation

IgA is the most abundantly produced antibody and plays an important role in the mucosal immune system. Human IgA is represented by two isotypes, IgA1 and IgA2. The major structural difference between these two subclasses is the presence of nine potential sites of <i>O</i>-glycosylation in the hinge region between the first and second constant region domains of the heavy chain. Thr²²⁵, Thr²²⁸, Ser²³⁰, Ser²³² and Thr²³⁶ have been identified as the predominant sites of <i>O</i>-glycan attachment. The range and distribution of <i>O</i>-glycan chains at each site within the context of adjacent sites in this clustered region create a complex heterogeneity of surface epitopes that is incompletely defined. We previously described the analysis of IgA1 <i>O</i>-glycan heterogeneity by use of high resolution LC–MS and electron capture dissociation tandem MS to unambiguously localize all amino acid attachment sites in IgA1 (Ale) myeloma protein. Here, we report the identification and elucidation of IgA1 <i>O</i>-glycopeptide structural isomers that occur based on amino acid position of the attached glycans (positional isomers) and the structure of the <i>O</i>-glycan chains at individual sites (glycan isomers). These isomers are present in a model IgA1 (Mce1) myeloma protein and occur naturally in normal human serum IgA1. Variable <i>O</i>-glycan chains attached to Ser²³⁰, Thr²³³ or Thr²³⁶ produce the predominant positional isomers, including <i>O</i>-glycans composed of a single GalNAc residue. These findings represent the first definitive identification of structural isomeric IgA1 <i>O</i>-glycoforms, define the single-site heterogeneity for all <i>O</i>-glycan sites in a single sample, and have implications for defining epitopes based on clustered <i>O</i>-glycan variability

Changes in continuous pain intensity and standardized protein concentrations in ID “G”.

<p>The protein concentrations were standardized according to the wound area, and then the standardized S100A8/A9 concentration was multiplied 10-fold for clarity. The horizontal axis indicates the duration in weeks from the first examination. Numbers of NGF data were 9, and of S100A8/A9 were 7 in spite of 10 time points because NGF was not detected in one sample from observation number 8, and S100A8/A9 was not detected in samples from observation numbers 10, 12, and 16. NGF = nerve growth factor.</p

Participant characteristics (n = 13).

<p>Participant characteristics (n = 13).</p

Wound and pain characteristics during each examination.

<p>Wound and pain characteristics during each examination.</p

Associations between pain intensity and standardized NGF and S100A8/A9 concentrations.

<p>Associations between pain intensity and standardized NGF and S100A8/A9 concentrations.</p

Self-evaluated pain intensity (N = 30).

<p>Self-evaluated pain intensity (N = 30).</p