Search

The O(3P)-initiated conversion mechanism and dynamics of CH3CHCO were researched in atmosphere by executing density functional theory (DFT) computations. Optimizations of all the species and single-point energy computations were implemented at the B3LYP/6–311++G(d,p) and CCSD(T)/cc-pVTZ level, respectively. The explicit oxidation mechanism was introduced and discussed. The results state clearly that the O(3P) association was more energetically beneficial than the abstraction of H. The rate coefficients over the probable temperature range of 200–3000 K were forecasted by implementing Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Specifically, the total rate coefficient of O(3P) association reactions is 1.19 × 10−11 cm3 molecule−1 s−1 at 298 K, which is consistent with the experimental results (1.16 × 10−11 cm3 molecule−1 s−1). The rate coefficients for the O(3P) with CH2CO, CH3CHCO, and (CH3)2CCO suggest that rate coefficient of ketene derivatives increase with the increase of methylation degree. [ABSTRACT FROM AUTHOR]

Abstract Background There are still some patients who show poor response to ovarian stimulation prior to evidence of normal ovarian reserve in vitro fertilization. However, there are few studies about how to treat the unexpectedly ovarian poor responder in vitro fertilization. The main aim of this study evaluate the effect of prolonging administration follicle-stimulating hormone in woman with the unexpectedly ovarian poor responder in vitro fertilization on implantation rate, clinical pregnancy rate and live birth rate. Methods 922 patients subjected to IVF were divided into two groups according to the predicted criterion of ovarian poor response. 116 patients predicted poor response received the short protocol (group C). The others received the long protocol, among the latter, there were 149 patients undergoing unexpectedly ovarian poor response (group B) and 657 patients exhibited normal ovarian response (group A). The doses of gonadotropin, duration of administration, implantation rate, clinical pregnancy rate and live birth rate were recorded among three groups. Results The implantation rate of embryo, clinic pregnancy rate and delivery rate are similar between the group A and group B, while there are significant differences between the doses of gonadotropins (35.1 +/- 8.9 ampules vs.53.0 +/- 15.9 ampules) and the duration of administration (15.3 +/- 3.6D vs. 9.8 +/- 2.6D) of these two groups. There are no significant differences about clinical pregnancy rate and live birth rate between group B and group C. Conclusion Prolonging administration gonadotropin on the unexpectedly poor ovarian responders does not lower live birth rate in vitro fertilization.

Nitrous acid (HONO) can produce hydroxyl radicals (OH) by photolysis and plays an important role in atmospheric photochemistry. Over the years, high concentrations of HONO have been observed in the Pearl River Delta region (PRD) of China, which may be one reason for the elevated atmospheric oxidation capacity. A comprehensive atmospheric observation campaign was conducted at an urban site in Guangzhou from 27 September to 9 November 2018. During the period, HONO was measured from 0.02 to 4.43 ppbv with an average of 0.74 ± 0.70 ppbv. The emission ratios (HONO/NOx) of 0.9 ± 0.4 % were derived from 11 fresh plumes. The primary emission rates of HONO at night were calculated to be between 0.04 ± 0.02 ppbv h-1 and 0.30 ± 0.15 ppbv h-1 based on a high-resolution emission inventory. The HONO formation rate by the homogeneous reaction of OH + NO at night was 0.26 ± 0.08 ppbv h-1, which can be seen as secondary results from primary emission. They were both much higher than the increase rate of HONO (0.02 ppbv h-1) during night. Soil emission rate of HONO at night was calculated to be 0.019 ± 0.001 ppbv h-1. Assuming dry deposition as the dominant removal process of HONO at night, and a deposition velocity of at least -2.5 cm s-1 is required to balance the direct emissions and OH + NO reaction. Correlation analysis shows that NH3 and relative humidity (RH) may participate in the heterogeneous transformation from NO2 to HONO at night. In the daytime, the average primary emission Pemis was 0.12 ± 0.01 ppbv h-1, and the homogeneous reaction POH + NO was 0.79 ± 0.61 ppbv h-1, larger than the unknown sources PUnknown (0.65 ± 0.46 ppbv h-1). These results suggest primary emissions as a key factor affecting HONO at our site, both during daytime and nighttime. Similar to previous studies, the daytime unknown source of HONO, PUnknown, appeared to be related to the photo-enhanced conversion of NO2. The daytime average OH production rates by photolysis of HONO was 3.7 × 106 cm-3 s-1, lower than that from O1D + H2O at 4.9 × 106 cm-3 s-1. Simulations of OH and O3 with the Master Chemical Mechanism (MCM) box model suggested strong enhancement effect of HONO on OH and O3 by 59 % and 68.8 %, respectively, showing a remarkable contribution of HONO to the atmospheric oxidation in the fall season of Guangzhou. [ABSTRACT FROM AUTHOR]

Mn–Ce–VOx/TiO2 (MnCeVTi), Mn–CeOx/TiO2 (MnCeTi) and Mn–VOx/TiO2 (MnVTi) nanocomposites as SCR DeNOx catalysts were synthesized by a modified sol–gel method. All catalysts shows high NOx conversion of over 90% at low temperature between 125 and 200 °C with GHSV of 30,000 h−1. MnCeVTi catalyst demonstrates the highest NOx conversion and produces the least byproduct N2O at 110–310 °C. The co-presence of Ce, V and Mn inhibits the growth of rutile, decreases crystallinity of anatase TiO2 and manganese oxides, reduces grain size, increases BET specific surface area and pore volume. There are most chemisorbed oxygen, appropriate Mn3+/Mn4+ and the synergistic effect of Ce and V on MnCeVTi sample. The acid sites on MnCeVTi are most below 280 °C and in widest temperature range. Lewis acid sites play a leading role in SCR reaction on MnCeVTi catalyst. These helps to optimize the SCR catalytic performance of MnCeVTi, on which E-R and L–H mechanism may coexist in the reaction. [ABSTRACT FROM AUTHOR]

Commercial V2O5–WO3/TiO2 (abbreviated to VWTi) SCR catalysts are modified with Ce and different contents of Cu in wet impregnation method to improve their alkali metals resistance, which is beneficial for prolonging their service life. After K poisoning, NOx conversion of VWCeCuTi sample modified with 0.30% Ce and 0.05% Cu is 89% at 350 °C, which is obviously higher than that of VWTi with a 50% NOx conversion. A series of characterization tests were conducted and verified that the ratio of V5+ and the surface-active oxygen on VWCeCuTi sample increases due to the interaction between V, Ce and Cu. Additionally, with the addition of Ce and Cu, surface acid sites are increased and their stability is strengthened. The enhanced redox property and surface acidity contribute together to the excellent K resistance of VWCeCuTi catalyst. [ABSTRACT FROM AUTHOR]

• 21 of 127 oxidized lipid metabolites change in SA-AKI patients. • 9,10-DiHOME and 5,6-DiHETrE were potential biomarkers in detecting SA-AKI. • 5-isoPGF2VI is a potential biomarker to distinguish AKI III from AKI I-II. • Vascular smooth muscle contraction was overall downregulation in SA-AKI patients. Oxidized lipids are essential bioactive lipid mediators generated during infection that regulate oxidative stress and the inflammatory response, but their signatures in patients with sepsis-associated acute kidney injury (SA-AKI) are poorly understood. This study analyzed the oxidative lipidomics of plasma from patients with SA-AKI to reveal the underlying biomarkers and pathophysiological mechanisms involved in sepsis. A total of 67 patients with SA-AKI and 20 age- and sex-matched healthy controls (HCs) participated in this prospective cohort study. Among the patients with SA-AKI, 14 cases had stage I-II AKI and 53 cases had stage III AKI. Oxidative lipidomic analysis of plasma samples was conducted using ultra performance liquid chromatography coupled with tandem mass spectrometric (UPLC-MS /MS) detection. Among 21 kinds of differentially oxidized lipids, 5(S),12(S)-DiHETE, 5-isoPGF2VI, 5,6-DiHETrE, 11,12-EET and 9,10-DiHOME showed the best performance. The prediction model incorporating them has shown highly sensitive and specific in distinguishing different stages of SA-AKI from HCs. The annotation of Kyoto Encyclopedia of Genes and Genomes illustrated that the overall downregulation of vascular smooth muscle contraction was closely related to the pathophysiological mechanism of SA-AKI. This study revealed alterations in the characteristic oxidized lipids in the plasma of SA-AKI patients, and these lipids had high diagnostic efficiency and potential targeted intervention value for SA-AKI. [ABSTRACT FROM AUTHOR]

Summary: Vertebrate eye development and homoeostasis critically depend on the regulation of proliferation of cells forming the retinal pigment epithelium (RPE). Previous results indicated that the death‐associated protein like‐1 DAPL1 cell autonomously suppresses RPE proliferation in vivo and in vitro. Here, we show in human RPE cell lines that the pigment cell transcription factor MITF regulates RPE cell proliferation by upregulating DAPL1 expression. DAPL1 regulation by MITF is, however, mediated predominantly by (−) MITF, one of two alternative splice isoforms of MITF that lacks six residues located upstream of the DNA‐binding basic domain. Furthermore, we find that the regulation of DAPL1 by MITF is indirect in that (−) MITF stimulates the transcription of Musashi homolog‐2 (MSI2), which negatively regulates the processing of the anti‐DAPL1 microRNA miR‐7. Our results provide molecular insights into the regulation of RPE cell proliferation and quiescence and may help us understand the mechanisms of normal RPE maintenance and of eye diseases associated with either RPE hyperproliferation or the lack of regenerative proliferation. [ABSTRACT FROM AUTHOR]

Two-photon microscopy imaging has been widely applied in biological imaging, but the development of two-photon absorption probes is obviously lagging behind in the development of imaging technology. In this paper, a two-photon fluorescent probe (1) based on pyrimidine 2-isothiocyanate has been designed and synthesized through a simple method for two-photon biological imaging. Probe 1 was able to couple effectively with the amino groups on biomolecules. To verify the reactivity of the isothiocyanate group on probe 1 and the amine groups on the biomolecules, d-glucosamine was chosen as a model biomolecule to conjugate with probe 1. The result showed that probe 1 could effectively conjugate with d-glucosamine to synthesize probe 2, and the yield of probe 2 was 83%. After conjugating with d-glucosamine, linear absorption spectra, single-photon fluorescence spectra, and two-photon fluorescence spectra of probes 1 and 2 did not present significant changes. Probes 1 and 2 exhibited high fluorescence quantum yields (0.71–0.79) in toluene and chloroform. They also exhibited different photo-physical properties in solvents with different polarities. The two-photon absorption cross-section of probe 1 was 953 GM in toluene. In addition, probe 1 could be effectively conjugated with transferrin, and the conjugated probe (Tf–1) could be transported into Hep G2 cells through a receptor-mediated process for biological imaging. These results demonstrate that such probes are expected to have great potential applications in two-photon fluorescence bioimaging. [ABSTRACT FROM AUTHOR]