油水混相泡沫的稳定化研究进展

油水混相泡沫是一种特殊的泡沫体系,由于其在化工、食品、药品等领域的广泛应用,因此对其稳定化机制的研究变得越来越重要。基于最新研究进展,研究了影响油水混相泡沫稳定性的因素,包括表面活性物质、油相以及一些其他因素,以探究其对泡沫的发泡性能和稳定性的作用机制,并着重论述了油相的种类、含量对泡沫稳定化的影响,最后探究了温度、矿化度以及不同表面活性剂和颗粒或者油相的耦合对泡沫稳定性的影响。文章还提出了一些未来的研究方向以及利用新型材料和纳米颗粒技术开发更有效的泡沫稳定化方法,对于深入理解油水混相泡沫的稳定化机制、优化泡沫性能、开发新的应用和解决相关领域的问题具有重要意义。

Insights into the size effect of ZnCr_(2)O_(4)spinel oxide in composite catalysts for conversion of syngas to aromatics

Direct conversion of syngas to aromatics(STA)over oxide-zeolite composite catalysts is promising as an alternative method for aromatics production.However,the structural effect of the oxide component in composite catalysts is still ambiguous.Herein,we investigate the size effect by selecting ZnCr_(2)O_(4)spinel,as a probe oxide,mixing with H-ZSM-5 zeolite as a composite catalyst for STA reaction.The CO conversion,aromatics selectivity and space-time yield(STY)of aromatics are all significantly improved with the crystal size of ZnCr_(2)O_(4)oxide decreases,which can mainly attribute to the higher oxygen vacancy concentration and thus the rapid generation of more C1oxygenated intermediate species.Based on the understanding of the size-performance relationship,ZnCr_(2)O_(4)-400 with a smaller size mixing with H-ZSM-5 can achieve32.6%CO conversion with 76%aromatics selectivity.The STY of aromatics reaches as high as 4.79 mmol g_(cat)^(-1)h^(-1),which outperforms the previously reported some typical catalysts.This study elucidates the importance of regulating the size of oxide to design more efficient oxidezeolite composite catalysts for conversion of syngas to value-added chemicals.

Smart Manufacturing and Intelligent Manufacturing:A Comparative Review

The application of intelligence to manufacturing has emerged as a compelling topic for researchers and industries around the world.However,different terminologies,namely smart manufacturing(SM)and intelligent manufacturing(IM),have been applied to what may be broadly characterized as a similar paradigm by some researchers and practitioners.While SM and IM are similar,they are not identical.From an evolutionary perspective,there has been little consideration on whether the definition,thought,connotation,and technical development of the concepts of SM or IM are consistent in the literature.To address this gap,the work performs a qualitative and quantitative investigation of research literature to systematically compare inherent differences of SM and IM and clarify the relationship between SM and IM.A bibliometric analysis of publication sources,annual publication numbers,keyword frequency,and top regions of research and development establishes the scope and trends of the currently presented research.Critical topics discussed include origin,definitions,evolutionary path,and key technologies of SM and IM.The implementation architecture,standards,and national focus are also discussed.In this work,a basis to understand SM and IM is provided,which is increasingly important because the trend to merge both terminologies rises in Industry 4.0 as intelligence is being rapidly applied to modern manufacturing and human–cyber–physical systems.

Catalytic activity of Cu/ZnO catalysts mediated by MgO promoter in hydrogenation of methyl acetate to ethanol

Hydrogenation of methyl acetate is a key step in ethanol synthesis from dimethyl ether carbonylation and Cu-based catalysts are widely studied.We report here that the hydrogenation activity of Cu/ZnO catalysts can be enhanced by the addition of MgO promoter.The evolution of crystal phases during coprecipitation and the physicochemical properties of calcined and reduced catalysts by X-ray diffraction(XRD),thermogravimetric(TG)-mass spectrometry(MS),Brunauer-Emmett-Teller(BET),transmission electron microscopy(TEM),N_(2)O titration,in situ CO-Fourier transform infrared spectroscopy(FTIR)and H_(2)-temperature programmed reduction(H_(2)-TPR)reveal that the promoter effect likely lies in the presence of Mg^(2+).A proper amount of Mg^(2+)mediates the precipitation process of Cu and Zn,leading to preferable formation of aurichalcite(Cu_(x)Zn_(1-x))5(CO_(3))_(2)(OH)_(6) crystal phase and a small amount of basic carbonates such as hydrozincite Zn_(5)(CO_(3))_(2)(OH)_(6) and malachite Cu_(2) CO_(3)(OH)_(2).The presence of aurichalcite strengthens the interaction between Cu and Zn species,and thus enhances the dispersity of CuO species and helps generation of Cu^(+)species on reduced catalysts.Furthermore,the performance of Cu/ZnO catalysts exhibits an optimal dependence on the Mg loading,i.e.,17.5%.However,too much Mg^(2+)in the precipitation liquid prohibits formation of aurichalcite but enhances formation of basic nitrates,leading to a dramatically reduced hydrogenation activity.These findings may find applications for optimization of other Cu-based catalysts in a wider range of hydrogenation reactions.

Insights into effects of ZrO_(2) crystal phase on syngas‐to‐olefin conversion over ZnO/ZrO_(2) and SAPO‐34 composite catalysts

The utilization of metal oxide‐zeolite catalysts in the syngas‐to‐olefin reaction is a promising strategy for producing C_(2)–C_(4) olefins from non‐petroleum resources.However,the effect of the crystal phase of metal oxides on the catalytic activity of these oxides is still ambiguous.Herein,typical metal oxides(ZnO/ZrO_(2))with different crystal phases(monoclinic(m‐ZrO_(2))and tetragonal(t‐ZrO_(2)))were employed for syngas conversion.The(ZnO/m‐ZrO_(2)+SAPO‐34)composite catalyst exhibited 80.5%selectivity for C_(2)–C_(4) olefins at a CO conversion of 27.9%,where the results are superior to those(CO conversion of 16.4%and C_(2)–C_(4) olefin selectivity of 76.1%)obtained over(ZnO/t‐ZrO_(2)+SAPO‐34).The distinct differences are ascribed to the larger number of hydroxyl groups,Lewis acid sites,and oxygen defects in ZnO/m‐ZrO_(2) compared to ZnO/t‐ZrO_(2).These features result in the formation of more formate and methoxy intermediate species on the ZnO/m‐ZrO_(2) oxides during syngas conversion,followed by the formation of more light olefins over SAPO‐34.The present findings provide useful information for the design of highly efficient ZrO_(2)‐based catalysts for syngas conversion.

Highly converting syngas to lower olefins over a dual-bed catalyst

Light olefins (C2–C4olefins) are the most important basic carbon-based building blocks, which are mainly produced from the catalytic cracking of naphtha [1–3]. With the rapid depletion of oil reserves and the growing demand for lower olefins, there is an urgent need to develop an alternative technique for producing them from non-petroleum resources such as coal, natural gas, or biomass. Currently, coal has been successfully transformed to olefins in China via the combination of the processes of coal-tosyngas, syngas-to-methanol and methanol-to-olefins [4–6]. In order to further improve efficiency and reduce investment, the direct conversion of syngas to olefins has received extensive attention in recent years [7].

Exploring the nonlinear piezoresistive effect of 4HSiC and developing MEMS pressure sensors for extreme environments

Microelectromechanical system(MEMS)pressure sensors based on silicon are widely used and offer the benefits of miniaturization and high precision.However,they cannot easily withstand high temperatures exceeding 150 ℃ because of intrinsic material limits.Herein,we proposed and executed a systematic and full-process study of Sic-based MEMS pressure sensors that operate stably from-50 to 300 ℃.First,to explore the nonlinear piezoresistive effect,the temperature coefficient of resistance(TCR)values of 4H-SiC piezoresistors were obtained from-50 to 500 ℃.A conductivity variation model based on scattering theory was established to reveal the nonlinear variation mechanism.Then,a piezoresistive pressure sensor based on 4H-SiC was designed and fabricated.The sensor shows good output sensitivity(3.38 mVN/MPa),accuracy(0.56%FS)and low temperature coefficient of sensitivity(TCS)(-0.067%FS/℃)in the range of-50 to 300 ℃.In addition,the survivability of the sensor chip in extreme environments was demonstrated by its anti-corrosion capability in H_(2)SO_(4) and NaOH solutions and its radiation tolerance under 5 W X-rays.Accordingly,the sensor developed in this work has high potential to measure pressure in high-temperature and extreme environments such as are faced in geothermal energy extraction,deep well dilling,aeroengines and gas turbines.

Relief generation from 3D scenes guided by geometric texture richness

Typically, relief generation from an input 3D scene is limited to either bas-relief or high-relief modeling. This paper presents a novel unified scheme for synthesizing reliefs guided by the geometric texture richness of 3D scenes; it can generate both bas- and high-reliefs. The type of relief and compression coefficient can be specified according to the user＇s artistic needs. We use an energy minimization function to obtain the surface reliefs, which contains a geometry preservation term and an edge constraint term. An edge relief measure determined by geometric texture richness and edge z-depth is utilized to achieve a balance between these two terms. During relief generation, the geometry preserwtion term keeps local surface detail in the original scenes, while the edge constraint term maintains regions of the original models with rich geometric texture. Elsewhere, in high- reliefs, the edge constraint term also preserves depth discontinuities in the higher parts of the original scenes. The energy function can be discretized to obtain a sparse linear system. The reliefs are obtained by solving it by an iterative process. Finally, we apply non-linear compression to the relief to meet the user＇s artistic needs. Experimental results show the method＇s effectiveness for generating both bas- and high-reliefs for complex 3D scenes in a unified manner.

An ultrasensitive and stretchable strain sensor based on a microcrack structure for motion monitoring

Flexible strain sensors are promising candidates for intelligent wearable devices.Among previous studies,although crack-based sensors have attracted a lot of attention due to their ultrahigh sensitivity,large strain usually causes fractures in the conductive paths.Because of the unstable crack structure,the tradeoff between sensitivity and workable strain range is still a challenge.As carbon nanotubes(CNTs)and silver nanowires(AgNWs)can form a strong interface with the thermoplastic substrate and strengthen the conductive network by capillary force during water evaporation,CNTs and AgNWs were deposited on electrospun TPU fiber mats via vacuum-assisted filtration in this work.The prestretching treatment constructed a microcrack structure that endowed the sensor with the combined characteristics of a wide working range(0~171%strain),ultrahigh sensitivity(a gauge factor of 691 within 0~102%strain,~2×10^(4) within 102~135%strain,and>11×10^(4) within 135~171%strain),a fast response time(~65 ms),small hysteresis,and superior durability(>2000 cycles).Subsequently,the sensing mechanism of the sensor was studied.Distributed microcrack propagation based on the“island-bridge”structure was explained in detail,and its influence on the strain-sensing behavior of the sensor was analyzed.Finally,the sensor was assembled to monitor various vibration signals and human motions,demonstrating its potential applications in the fields of electronic skin and human health monitoring.