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1.
为了探索三维石墨烯-碳纳米管(G-CNTs)/水泥净浆的压敏性能,采用四电极法研究了荷载作用下GCNTs/水泥净浆的电阻率变化,并分析不同G-CNTs掺量、加载幅度、加载速度以及恒定荷载对电阻率变化的影响。研究表明:随着G-CNTs掺量的增加,电阻率呈先减小后稳定的变化趋势,在G-CNTs掺量由0.2wt%增加至1.6wt%时,电阻率下降51.8%;电阻率与温度呈负相关;G-CNTs掺量高于0.8wt%时可以显著提高水泥净浆的压敏性能,且电阻率变化率与应力应变有明显的对应关系,1.2wt%G-CNTs掺量下试件的应力灵敏系数和应变灵敏系数分别为2.3%/MPa和291;G-CNTs/水泥净浆电阻率变化率幅值随着加载幅度增大而相应增加,其电阻率变化率曲线在不同加载速度以及恒定荷载作用下均与应力-应变曲线一一对应,具有良好的压敏特性。 相似文献
2.
Ryszard Żywica Monika Modzelewska-Kapituła Katarzyna Tkacz 《International Journal of Food Properties》2018,21(1):1386-1394
The aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (Ii) and ultimate (Iu) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R2 = 0.416, α ≤ 0.001) between Iu and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values. 相似文献
3.
4.
Biosolids reduction model by return activated sludge ozonation was validated by simulating nitrification data compiled from our pilot-scale and the literature studies. Then, a global sensitivity analysis (GSA) was performed to identify influential and non-influential parameters for biosolids reduction efficiency, change in specific nitrification activity (SNA), and alteration to expected nitrification stability. In general, the model outputs were sensitive to operational and ozone reaction parameters, but not to biochemical parameters. For operational parameters, mainly temperature and initial solids retention time (SRT) influenced all model outputs. For biosolids reduction, increase in the degradability of the influent COD decreased the reduction efficiency. For SNA, the changes were highly dependent on the influent TKN/COD ratio. Our findings also imply that the stability of the nitrification process in ozonated systems should be enhanced at constant MLVSS for warm temperatures, but could be reduced at temperatures below 12 °C and aerated SRTs below 10 days. 相似文献
5.
ABSTRACT This study investigates the effects of strain, strain rates, and forming directions (RD-rolling direction, TD-transverse direction, and ND-normal direction) on adiabatic shear, via dynamic impact compression tests using the Split Hopkinson Pressure Bar (SHPB) apparatus. A modified Johnson-Cook (J-C) constitutive model is proposed, which used to analyse the influence of the constitutive parameters on the sensitivity of adiabatic shear, employing a finite element software. The different sensitivities of adiabatic shear under different directions are explained by combining microscopic analysis and results from mechanical responses. The results show that the sensitivity of adiabatic shear can be related to the time of stress collapse in the following trend: ND?>?TD?>?RD; the sensitivities of these constitutive parameters on adiabatic shear are calculated and compared. 相似文献
6.
Mineralization of Para-Chlorobenzoic Acid in Water by Cobalt-Incorporated MCM-41 Catalyzed Ozonation
Cobalt-incorporated MCM-41(Co-MCM-41) was used as a heterogeneous catalyst for the ozonation of para-chlorobenzoic acid (p-CBA) in aqueous solution. Cobalt oxide supported on MCM-41(Co/MCM-41) was synthesized for comparison. Their textural properties were elucidated by various characterization techniques to understand the relationship between surface texture and catalytic activity. TOC removal at 60 min reached 91% with Co-MCM-41, 83% with Co/MCM-41 and only 52% with ozone alone, respectively. Observations from diffuse reflection spectroscopy demonstrated that different metal phases were formed in these cobalt-modified molecular sieves samples. Radical scavenger experiments indicated the formation of hydroxyl radicals that were responsible for the effective degradation of p-CBA. An integrated approach to the catalytic mechanism was proposed by considering the variation of pH in the course of ozonation as well as its subsequent influence on the dissociation of targeted compounds and surface charge of the catalyst. In the reusability experiments, the reused Co-MCM-41 was able to regain the same catalytic capability as the fresh one within 5 cycles. X-ray photoelectron spectroscopy results indicated that a part of Co2+ was oxidized to Co3+ after oxidation reaction. 相似文献
7.
Nicolas Dolder Prof. Dr. Christoph von Ballmoos 《Chembiochem : a European journal of chemical biology》2020,21(15):2219-2224
Enzyme-mediated proton transport across biological membranes is critical for many vital cellular processes. pH-sensitive fluorescent dyes are an indispensable tool for investigating the molecular mechanism of proton-translocating enzymes. Here, we present a novel strategy to entrap pH-sensitive probes in the lumen of liposomes that has several advantages over the use of soluble or lipid-coupled probes. In our approach, the pH sensor is linked to a DNA oligomer with a sequence complementary to a second oligomer modified with a lipophilic moiety that anchors the DNA conjugate to the inner and outer leaflets of the lipid bilayer. The use of DNA as a scaffold allows subsequent selective enzymatic removal of the probe in the outer bilayer leaflet. The method shows a high yield of insertion and is compatible with reconstitution of membrane proteins by different methods. The usefulness of the conjugate for time-resolved proton pumping measurements was demonstrated by using two large membrane protein complexes. 相似文献
8.
How to improve the sensitivity of the temperature-sensing luminescent materials is one of the most important objects currently. In this work, to obtain high sensitivity and learn the corresponding mechanism, the rare earth (RE) ions doped Y4.67Si3O13 (YS) phosphors were developed by solid-state reaction. The phase purity, structure, morphology and luminescence characteristics were evaluated by XRD, TEM, emission spectra, etc. The change of the optical bandgaps between the host and RE-doped phosphors was found, agreeing with the calculation results based on density-functional theory. The temperature-dependence of the upconversion (UC) luminescence revealed that a linear relationship exists between the fluorescence intensity ratio of Ho3+ and temperature. The theoretical resolution was evaluated. High absolute (0.083 K−1) and relative (3.53% K−1 at 293 K) sensitivities have been gained in the YS:1%Ho3+, 10%Yb3+. The effect of the Yb3+ doping concentration and pump power on the sensitivities was discussed. The pump-power–dependence of the UC luminescence indicated the main mechanism for high sensitivities in the YS:1%Ho3+, 10%Yb3+. Moreover, the decay-lifetime based temperature sensing was also evaluated. The above results imply that the present phosphors could be promising candidates for temperature sensors, and the proposed strategies are instructive in exploring other new temperature sensing luminescent materials. 相似文献
9.
针对气藏型储气库注采井注采过程中储层物性参数影响因素不明确、注采能力不对称的问题。基于相国寺储气库井下连续油管试井测试结果,提出储气库注气期“温降效应”、“变表皮效应”的概念,分析了储气库注采过程中温降效应、变表皮效应以及储层应力敏感对注采的影响。通过气藏型储气库注气期试井分析技术,研究各因素在试井曲线上的响应特征以及对试井解释参数的影响。结果表明:①相对于采气期试井测试,注气期测试得到的储层物性参数具有同样的参考价值;②储气库温降效应对于试井解释结果的影响可忽略不计,而在不同注采运行周期内,变表皮效应以及应力敏感效应影响差异较大;③编制储气库注采运行方案时应充分考虑变表皮效应与应力敏感的影响,在不同注采运行周期内开展试井测试获取准确的储层参数值。研究成果为储气库试井测试与解释提供了重要的研究依据和理论指导。 相似文献
10.
Chitosan microspheres containing bromocresol green, cresol red, and phenolphthalein for corrosion detection, through pH change, are synthesized in order to be used in protective coatings for aluminium alloys. Microspheres containing corrosion detection species are characterized morphologically (SEM) and physico‐chemically (FTIR, TGA). Release studies (UV–vis) are performed in corrosion‐promoting conditions (pH, NaCl), and detection studies by immersion in media associated with corrosion activity while microspheres' sensing activity is evaluated visually. Electrochemical characterization of AA2024 substrates in the presence of chitosan spheres is performed to understand material performance, and a color change is observed as a result of local pH increase in cathodic areas when corrosion takes place. These findings can be correlated with the results from release studies and seem a promising approach for corrosion sensing purposes, not only because pH increase is possible to detect due to corrosion, but also because chitosan is considered an environmentally friendly material. 相似文献