Search Results

You are looking at 1 - 10 of 139 items for

  • Author or Editor: Y. Chen x
  • Refine by Access: All Content x
Clear All Modify Search

Both melatonin and leptin show a circadian variation in circulating levels and participate in energy metabolism. An interrelationship between these two hormones has thus been proposed. In addition, melatonin has been shown to be capable of influencing circulating leptin concentration. However, whether melatonin will increase or decrease leptin production is still uncertain. This study was undertaken to examine the effect of melatonin on leptin production using male C57BL/6 adult mice treated with or without daily melatonin supplements (10 μg/mL) in drinking water for 1 month. In addition, in vitro experiments using adipose tissue fragments derived from epididymal fat pads of adult mice incubated with or without melatonin (1 nM) administration were also conducted. The results showed that melatonin-supplemented mice had significantly higher plasma leptin levels than control mice. However, melatonin incubation did not cause any marked changes in the amount of leptin secreted from adipose tissue fragments. Our findings from this study indicate that melatonin does not affect leptin secretion via mouse adipose tissue. Nevertheless, melatonin could still influence leptinemia indirectly via regulatory effects in intact animals.

Restricted access

Abstract  

The class
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{bbm} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathcal{P}\mathcal{C}$$ \end{document}
of projectively condensed semigroups is a quasivariety of unary semigroups, the class of projective orthomonoids is a subquasivariety of
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{bbm} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathcal{P}\mathcal{C}$$ \end{document}
. Some well-known classes of generalized completely regular semigroups will be regarded as subquasivarieties of
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{bbm} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathcal{P}\mathcal{C}$$ \end{document}
. We give the structure semilattice composition and the standard representation of projective orthomonoids, and then obtain the structure theorems of various generalized orthogroups.
Restricted access

Rapid and accurate diagnosis of influenza is important for patient management and infection control. We determined the performance of the cobas® Influenza A/B assay, a rapid automated nucleic acid assay performed on the cobas® Liat System for qualitative detection of influenza A and influenza B from nasopharyngeal (NP) swab specimens. Retrospective frozen and prospectively collected NP swabs from patients with signs and symptoms of influenza collected in universal transport medium (UTM) were tested at multiple sites including CLIA-waived sites using the cobas® Influenza A/B assay. Results were compared to the Prodesse ProFlu+ assay and to viral culture. Compared to the Prodesse ProFlu+ Assay, sensitivities of the cobas® Influenza A/B assay for influenza A and B were 97.7 and 98.6%, respectively; specificity was 99.2 and 99.4%. Compared to viral culture, the cobas® Influenza A/B assay showed sensitivities of 97.5 and 96.9% for influenza virus A and B, respectively; specificities were 97.9% for both viruses. Polymerase chain reaction (PCR)/sequencing showed that the majority of viral culture negative but cobas® Influenza A/B positive results were true positive results, indicating that the cobas® Influenza A/B assay has higher sensitivity compared to viral culture.

In conclusion, the excellent accuracy, rapid time to result, and remarkable ease of use make the cobas® Influenza A/B nucleic acid assay for use on the cobas® Liat System a highly suitable point-of-care solution for the management of patients with suspected influenza A and B infection.

Open access

Abstract  

Organic peroxides (OPs) are very susceptible to thermal sources, chemical pollutants or even mechanical shock. Over the years, they have caused many serious explosions. Cumene hydroperoxide (CHP) is widely employed to produce phenol and dicumyl peroxide (DCPO) in the manufacturing process. Differential scanning calorimetry (DSC) and thermal activity monitor (TAM) were employed to determine the potential thermal hazards and thermokinetic parameters (such as exothermic onset temperature (T 0), maximum temperature (T max), and enthalpy (ΔH)) of CHP mixed with sodium hydroxide (NaOH) and sulfuric acid (H2SO4). High performance liquid chromatography (HPLC) was used to analyze the concentration vs. time of CHP.When CHP is mixed with NaOH, the T 0 is induced earlier and reactions become more intricate than the pure CHP solution. CHP added to NaOH or H2SO4 is more dangerous than pure CHP alone. Depending on the operating conditions, NaOH and H2SO4 are the incompatible chemicals for CHP.

Restricted access

Abstract  

New solid complex of nitrilotriacetic acid and bismuth trichloride was synthesized by a solid phase reaction of nitrilotriacetic acid and bismuth trichloride at room temperature. The composition of the sample is BiCl3[N(CH2COOH)3]2.5. The crystal structure of the complex belongs to triclinic system with the lattice parameters: α=0.7849 nm, β=0.9821 nm, χ=2.0021 nm, α=96.50, β=98.76 and γ=90.49. The far-infrared spectra show the bonding between the Bi ion and N atom of nitrilotriacetic acid. The thermal analysis also demonstrates the complex formation between the bismuth ion and nitrilotriacetic acid. The gaseous pyrolysis product and the final residue in the thermal decomposition process are determined to check the thermal decomposition reaction.

Restricted access

Abstact  

The reduction process of silica supported cobalt catalyst was studied by thermal analysis technique. The reduction of the catalyst proceeds in two steps:

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$Co_3 O_4 + H_2 \to 3CoO + H_2 O, 3CoO + 3H_2 \to 3Co + 3H_2 O$$ \end{document}
which was validated by the TPR and in-situ XRD experiments. The kinetic parameters of the reduction process were obtained with a comparative method. For the first step, the activation energy, E a, and the pre-exponential factor, A, were found to be 104.35 kJ mol−1 and 1.18�106∼2.45�109 s−1 respectively. The kinetic model was random nucleation and growth and the most probable mechanism function was found to be f(α)=3/2(1−α)[−ln(1−α)]1/3 or in the integral form: g(α)=[−ln(1−α)]2/3. For the second step, the activation energy, E a, and the pre-exponential factor, A, were found to be 118.20 kJ mol−1 and 1.75�107∼2.45 � 109s−1 respectively. The kinetic model was a second order reaction and the probable mechanism function was f(α)=(1−α)2 or in the integral form: g(α)=[1−α]−1−1.

Restricted access

Alkaline fading of bromophenol blue was chosen for the investigation of the effect of heating rate on the activation energies derived from the dynamic kinetic method. Freeman and Carroll's treatment was adopted to compute the activation energies from experimental data taken with three heating rates: namely 1°, 0.5° and 0.25°/min. It was found that the activation energy increases as the heating rate decreases. This is attributed to the non-equilibrium conditions. By extrapolating to zero heating rate, the activation energy obtained is comparable to that obtained via classical isothermal kinetics.

Restricted access

Abstract  

A series of Zn–Al hydrotalcites with Zn/Al molar ratios of 1, 2, 3 and 6 were prepared by co-precipitation method. TG-DTG results showed that the hydrotalcites decompose in two stages, corresponding to the two endothermic peaks around 180 and 220°C. After calcination at 400°C, the samples were converted into Zn–Al mixed oxides with the only XRD pattern of ZnO, except for the sample with the ratio of 6. The Zn–Al mixed oxides possess similar surface acidity revealed by microcalorimetric adsorption of NH3. The basicity of the samples increases with the order: ZnO>6Zn/Al>1Zn/Al>Al2O3.

Restricted access