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Nine organic compounds were utilized as model lubricants to investigate the impact of functional groups on tribological performances. Nonanoic Acid with carboxyl showed the best lubrication properties, and fluid film and tribofilm were coexistent in its friction test, bringing a low friction coefficient and wear rate. In addition, the lubricant with low friction coefficient corresponded to high adsorption energy in density functional theory (DFT) calculations. And the lubricant forming adsorption film with large surface energy displayed small wear rate in friction test. Moreover, adsorption energies positively correlated surface energies. Based on the experimental results, the action mechanism of functional groups on tribological properties of lubricants was proposed. Various functional groups make lubricant molecules show different adsorption energies and surface energies. Lubricant molecules with high adsorption energy are more likely to adsorb on substrates and form a vertical monolayer, which can maintain a regular molecular brush structure during friction and bring a low friction coefficient. And lubricant molecules with high surface energy may be more prone having tribochemical reactions during friction and forming protective tribofilm, which leads to a low wear rate.

Introdução e Objectivos: O desenvolvimento de fibrose cardíaca (FC) e hipertrofia (CH) pode levar à insuficiência cardíaca. As células estaminais mesenquimais (MSCs) têm-se mostrado promissoras no tratamento de doenças cardíacas. No entanto, a relação entre as MSCs e a SFRS3 permanece pouco clara. Neste estudo, os nossos objetivos são investigar o efeito das MSCs na expressão de SFRS3 e o seu impacto na fibrose e hipertrofia cardíacas. Além disso, pretendemos explorar a função do excesso de SFRS3 em fibroblastos cardíacos (CFBs) e miócitos cardíacos (CMCs) tratados com angiotensina II (Ang II).

Trace levels of Hg, As, Sb, and Bi in coastal seawater have been simultaneously detected by a laboratory-built multichannel chemical vapor generation coupled to an atomic fluorescence spectrometer. The system was configured with a built-in electrochemical H2generator as the fuel supplier to replace chemical H2produced by the oxidation of potassium borohydride under acidic conditions in traditional instruments. The electrochemical H2generator not only isolated the atomization process from the chemical vapor injection process but also improved the stability of atomization, excitation, and fluorescence emission in the hydrogen flame, making it easier to optimize conditions for CVG while introducing evaporating multielement vapors. Calibrations were obtained using a mixed standard solution of Hg(II), As(III), Sb(III), and Bi(III). The addition of KBr to a 3% (v/v) HCl solution was selected as the preservative to ensure the stability of 0.10 μg/L Hg(II) in a multielement standard solution for at least 15 days while also preserving μg/L levels of As(III), Sb(III), and Bi(III) stable. The method detection limits (LOD, 3σ) were 0.001, 0.015, 0.010, and 0.005 μg/L for Hg, As, Sb, and Bi, respectively. The relative standard deviations (RSD, n= 7) of the standard spiked seawater samples were 3.2% (0.020 μg/L Hg), 1.2% (0.50 μg/L As), 1.0% (0.50 μg/L Sb), and 3.5% (0.050 μg/L Bi), respectively. The recoveries of seawater samples spiked with different salinities were in the range of 84.5%(Sb)–114%(Hg). The system has been successfully applied to the simultaneous analysis of the four elements in the seawater samples collected from Xiamen Bay, Southeast China.

Fluorine-incorporated hydrogenated fullerene-like nanostructure amorphous carbon films (F-FLC) were synthesized by employing the direct current plasma enhanced chemical vapor deposition (dc-PECVD) technique using a mixture of methane (CH4), tetra-fluoromethane (CF4), and hydrogen (H2) as the working gases. The effect of the fluorine content on the bonding structure, surface roughness, hydrophobic, mechanical, and tribological properties of the films was systematically investigated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman analysis, atomic force microscope (AFM), contact angle goniometer, nano-indenter, and reciprocating ball-on-disc tester, respectively. The fluorine content in the films increased from 0 to 2.1 at.% as the CF4gas flow ratio increased from 0 to 3 sccm, and incorporated fluorine atoms existed in the form of C-FX(X= 1, 2, 3) bonds in the film. The fullerene nanostructure embedded in the hydrogenated amorphous carbon films was confirmed by Raman analysis. The water contact angle was significantly increased because of fluorine doping, which indicates that the hydrophobicity of the carbon films could be adjusted to some extent by the fluorine doping. The hardness and elastic modulus of the films remained relatively high (22 GPa) as the fluorine content increased. Furthermore, the friction coefficient of the carbon films was significantly reduced and the wear resistance was enhanced by fluorine doping.

The matrix effects on analyte vaporization and ICP excitation conditions in direct sample insertion–inductively coupled plasma atomic emission spectrometry were studied. Zn was used as a test element and NaCl as the matrix. A slow insertion speed of the sample probe was used to allow partial separation in time of the vaporization of the volatile Zn species and the NaCl matrix. Temporal studies of the Zn emission intensity indicate that ZnCl2starts to vaporize during sample probe insertion in the presence of the NaCl matrix. The Zn intensity is reduced because the plume of Zn vapor is not concentrated in the central channel of the ICP. Temporal profiles of the intensity ratio of ZnII/ZnI also shows that introduction of a large quantity of NaCl into the ICP has little effect on the ICP excitation conditions. The ICP is, however, significantly cooled due to heat loss to the sample probe.