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Events and reaction mechanisms during the synthesis of an Al

M. ABDELLAHI, M. ZAKERI, H. BAHMANPOUR

《化学科学与工程前沿（英文）》 2013年第7卷第2期页码 123-129 doi: 10.1007/s11705-013-1325-6

摘要： An Al O -TiB nanocomposite was successfully synthesized by the high energy ball milling of Al, B O and TiO . The structures of the powdered particles formed at different milling times were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thermodynamic calculations showed that the composite formed in two steps via highly exothermic mechanically induced self-sustaining reactions (MSRs). The composite started to form at milling times of 9–10 h but the reaction was not complete. The remaining starting materials were consumed by increasing the milling time to 15 h. The XRD patterns of the annealed powders showed that aluminum borate is one of the intermediate products and that it is consumed at higher temperatures. Heat treatment of the 6-h milled sample at 1100 C led to a complete formation of the composite. Increasing the milling time to 15 h led to a refining of the crystallite sizes. A nanocomposite powder with a mean crystallite size of 35–40 nm was obtained after milling for 15 h.

关键词： ball milling nanocomposite Al₂O₃ TiB₂

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Effects of support acidity on the reaction mechanisms of selective catalytic reduction of NO by CH

Shicheng XU, Junhua LI, Dong YANG, Jiming HAO

《环境科学与工程前沿（英文）》 2009年第3卷第2期页码 186-193 doi: 10.1007/s11783-009-0016-5

摘要： The reaction mechanisms of selective catalytic reduction (SCR) of nitric oxide (NO) by methane (CH ) over solid superacid-based catalysts were proposed and testified by DRIFTS studies on transient reaction as well as by kinetic models. Catalysts derived from different supports would lead to different reaction pathways, and the acidity of solid superacid played an important role in determining the reaction mechanisms and the catalytic activities. Higher ratios of Br?nsted acid sites to Lewis acid sites would lead to stronger oxidation of methane and then could facilitate the step of methane activation. Strong Br?nsted acid sites would not necessarily lead to better catalytic performance, however, since the active surface NO species and the corresponding reaction routes were determined by the overall acidity strength of the support. The reaction routes where NO moiety was engaged as an important intermediate involved moderate oxidation of methane, the rate of which could determine the overall activity. The reaction involving NO moiety was likely to be determined by the step of reduction of NO. Therefore, to enhance the SCR activity of solid superacid catalysts, reactions between appropriate couples of active NO species and activated hydrocarbon intermediates should be realized by modification of the support acidity.

关键词： selective catalytic reduction (SCR) nitric oxide (NO) methane support acidity Br?nsted acid sites NO_y species

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Ozonation of the 5-fluorouracil anticancer drug and its prodrug capecitabine: Reaction kinetics, oxidationmechanisms, and residual toxicity

Siyu Chen, Lee Blaney, Ping Chen, Shanshan Deng, Mamatha Hopanna, Yixiang Bao, Gang Yu

《环境科学与工程前沿（英文）》 2019年第13卷第4期 doi: 10.1007/s11783-019-1143-2

摘要：

Specific second-order rate constants were determined for 5-FU and CAP with ozone.

Reaction sites were confirmed by kinetics, Fukui analysis, and products.

The olefin moiety was the main ozone reaction site for 5-FU and CAP.

Carboxylic acids comprised most of the residual TOC for 5-FU.

Ozonation removed the toxicity associated with 5-FU and products but not CAP.

关键词： Ozone 5-fluorouracil Capecitabine Hydroxyl radicals Chemotherapy agents Toxicity

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Redox reactions of iron and manganese oxides in complex systems

Jianzhi Huang, Huichun Zhang

《环境科学与工程前沿（英文）》 2020年第14卷第5期 doi: 10.1007/s11783-020-1255-8

摘要： • Mechanisms of redox reactions of Fe- and Mn-oxides were discussed. • Oxidative reactions of Mn- and Fe-oxides in complex systems were reviewed. • Reductive reaction of Fe(II)/iron oxides in complex systems was examined. • Future research on examining the redox reactivity in complex systems was suggested. Conspectus Redox reactions of Fe- and Mn-oxides play important roles in the fate and transformation of many contaminants in natural environments. Due to experimental and analytical challenges associated with complex environments, there has been a limited understanding of the reaction kinetics and mechanisms in actual environmental systems, and most of the studies so far have only focused on simple model systems. To bridge the gap between simple model systems and complex environmental systems, it is necessary to increase the complexity of model systems and examine both the involved interaction mechanisms and how the interactions affected contaminant transformation. In this Account, we primarily focused on (1) the oxidative reactivity of Mn- and Fe-oxides and (2) the reductive reactivity of Fe(II)/iron oxides in complex model systems toward contaminant degradation. The effects of common metal ions such as Mn2+ , Ca2+, Ni2+, Cr3+ and Cu2+, ligands such as small anionic ligands and natural organic matter (NOM), and second metal oxides such as Al, Si and Ti oxides on the redox reactivity of the systems are briefly summarized.

关键词： Iron oxides manganese oxides reduction oxidation complex systems reaction kinetics and mechanisms

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Product identification and toxicity change during oxidation of methotrexate by ferrate and permanganate in water

《环境科学与工程前沿（英文）》 2022年第16卷第7期 doi: 10.1007/s11783-021-1501-8

摘要：

• Oxidation of methotrexate by high-valent metal-oxo species was first explored.

关键词： Anticancer drugs High-valent metal-oxo species Oxidation kinetics Reaction mechanisms Multi-endpoint toxicity

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Catalytic activity of noble metal nanoparticles toward hydrodechlorination: influence of catalyst electronic structure and nature of adsorption

Man ZHANG,Feng HE,Dongye ZHAO

《环境科学与工程前沿（英文）》 2015年第9卷第5期页码 888-896 doi: 10.1007/s11783-015-0774-1

摘要： In this study, stabilized Pd, Pt and Au nanoparticles were successfully prepared in aqueous phase using sodium carboxymethyl cellulose (CMC) as a capping agent. These metal nanoparticles were then tested for catalytic hydrodechlorination toward two classes of organochlorinated compounds (vinyl polychlorides including trichloroethylene (TCE), tetrachloroethylene (PCE), and alkyl polychlorides including 1,1,1-trichloroethane (1,1,1-TCA), and 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA)) to determine the rate-limiting steps and to explore the reaction mechanisms. The surface area normalized reaction rate constant, , showed a systematic dependence on the electronic structure (the density of states at the Fermi level) of the metals, suggesting that adsorption of organochlorinated reactants on the metal catalyst surfaces is the rate-limiting step for catalytic hydrodechlorination. Hydrodechlorination rates of 1,1,1-TCA and 1,1,1,2-TeCA agreed with the bond strength of the first (weakest) dissociated C-Cl bond, suggesting that C-Cl bond cleavage, which is the first step for dissociative adsorption of the alkyl polychlorides, controlled the catalytic hydrodechlorination rate. However, hydrodechlorination rates of TCE and PCE correlated with the adsorption energies of their molecular (non-dissociative) adsorption on the noble metals rather than with the first C-Cl bond strength, suggesting that molecular adsorption governs the reaction rate for hydrodechlorination of the vinyl polychlorides.

关键词： catalytic hydrodechlorination electronic structure metal nanoparticles reaction mechanisms

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FOOD SYSTEMS TRANSFORMATION: CONCEPTS, MECHANISMS AND PRACTICES

《农业科学与工程前沿（英文）》 2023年第10卷第1期页码 1-3 doi: 10.15302/J-FASE-2023491

摘要： FOOD SYSTEMS TRANSFORMATION: CONCEPTS, MECHANISMS AND PRACTICES

关键词： TRANSFORMATION SYSTEMS FOOD CONCEPTS MECHANISMS

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Gripping mechanisms in current wood harvesting machines

D. GOUBET, J. C. FAUROUX, G. GOGU

《机械工程前沿（英文）》 2013年第8卷第1期页码 42-61 doi: 10.1007/s11465-013-0358-3

摘要：

This paper focuses on the structural synthesis of gripping mechanisms used in the mechanization of the harvesting process. The importance of the gripping function in current devices like harvesting heads is underlined. This function is performed with several typical mechanisms which are listed and described in this article. This study distinguishes two kinds of planar gripping mechanisms mainly used in opening and closing the rollers: five concentric and two lateral ones. Both kinds have advantages and drawbacks. So a third kind of hybrid mechanism has been designed in order to orientate the axis of the rollers during gripping motion in order to combine concentric and lateral gripping advantages. Two planar and one spatial existing mechanisms are described. The last part of this paper presents a structural synthesis of such a spatial parallel mechanism by using the structural parameters and the general formulae established by the third author. Nine kinematic diagrams of spatial parallel mechanisms are provided.

关键词： structural synthesis parallel mechanisms gripping mechanisms wood harvesting harvesting head

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Recent development on innovation design of reconfigurable mechanisms in China

Wuxiang ZHANG, Shengnan LU, Xilun DING

《机械工程前沿（英文）》 2019年第14卷第1期页码 15-20 doi: 10.1007/s11465-018-0517-7

摘要： Reconfigurable mechanisms can deliberately reconfigure themselves by rearranging the connectivity of components to meet the different requirements of tasks. Metamorphic and origami-derived mechanisms are two kinds of typical reconfigurable mechanisms, which have attracted increasing attention in the field of mechanisms since they were proposed. Improving the independent design level, innovation, and international competitive powers of reconfigurable mechanical products is important. Summarizing related significant innovation research and application achievements periodically will shed light on research directions and promote academic exchanges. This paper presents an overview of recent developments in innovation design of reconfigurable mechanisms in China, including metamorphic and origami mechanisms and their typical applications. The future development trends are analyzed and forecasted.

关键词： innovation design reconfigurable mechanisms metamorphic mechanisms origami-derived mechanisms development trends

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CROP DIVERSITY AND SUSTAINABLE AGRICULTURE: MECHANISMS, DESIGNS AND APPLICATIONS

《农业科学与工程前沿（英文）》 2021年第8卷第3期页码 359-361 doi: 10.15302/J-FASE -2021417

摘要：

Intensive monoculture agriculture has contributed greatly to global food supply over many decades, but the excessive use of agricultural chemicals (fertilizers, herbicides and pesticides) and intensive cultivation systems has resulted in negative side effects, such as soil erosion, soil degradation, and non-point source pollution^{^[1]}. To many observers, agriculture looms as a major global threat to nature conservation and biodiversity. As noted in the Global Biodiversity Outlook 4^{^[2]}, the drivers associated with food systems and agriculture account for around 70% and 50% of the projected losses by 2050 of terrestrial and freshwater biodiversity, respectively^{^[3]}.

In addition, agricultural development and modernization of agriculture has led to a decline in the total number of plant species upon which humans depend for food^{^[4]}. Currently, fewer than 200 of some 6000 plant species grown for food contribute substantially to global food output, and only nine species account for 67% of total crop production^{^[3]}. The global crop diversity has declined in past decades.

Crop species diversity at a national scale was identified as one of the most important factors that stabilize grain production at a national level^{^[5]}. A group of long-term field experiments demonstrated that crop diversity also stabilizes temporal grain productivity at field level^{^[6]}. Therefore, maintaining crop diversity at both national and field levels is of considerable importance for food security at national and global scales.

Crop diversity includes temporal (crop rotation) and spatial diversity (e.g., intercropping, agroforestry, cultivar mixtures and cover crops) at field scale. Compared to intensive monocultures, diversified cropping systems provide additional options to support multiple ecosystem functions. For instance, crop diversity may increase above- and belowground biodiversity, improve yield stability, reduce pest and disease damage, reduce uses of chemicals, increase the efficiency of the use land, light water and nutrient resources, and enhance stress resilience in agricultural systems.

To highlight advances in research and use of crop diversity, from developing and developed countries, we have prepared this special issue on “Crop Diversity and Sustainable Agriculture” for Frontiers of Agricultural Sciences and Engineering, mainly focusing on intercropping.

Intercropping, growing at least two crops at the same time as a mixture, for example, in alternate rows or strips, is one effective pathway for increasing crop diversity at the field scale. Over recent decades, there have been substantial advances in terms of understanding of processes between intercropped species and applications in practice. There are 10 articles in this special issue including letters, opinions, review and research articles with contributions from Belgium, China, Denmark, France, Germany, Greece, Italy, the Netherlands, Spain, Switzerlands, UK, and Mexico etc.

The contributors are internationally-active scientists and agronomists contributing to intercropping research and extension. For example, Antoine Messean is coordinator of the EU H2020 Research project DiverIMPACTS “Diversification through rotation, intercropping, multiple cropping, promoted with actors and value chains towards sustainability”. Eric Justes is coordinator of the EU H2020 Research project ReMIX “Redesigning European cropping systems based on species mixtures”. Maria Finckh has worked on crop cultivar mixture and organic agriculture over many years. Henrik Hauggaard-Nielsen has outstanding expertise in intercropping research and applications, moving from detailed studies on species interactions in intercropping to working with farmers and other stakeholders to make intercropping work in practical farming. In addition to these established scientists, young scientists who have taken an interest in intercropping also contribute to the special issue, including Wen-Feng Cong, Yixiang Liu, Qi Wang, Hao Yang and others.

The first contribution to this special issue addresses how to design cropping systems to reach crop diversification, with Wen-Feng Cong and coworkers ( https://doi.org/10.15302/J-FASE-2021392) considering that it is necessary to optimize existing and/or design novel cropping systems based on farming practices and ecological principles, and to strengthen targeted ecosystem services to achieve identified objectives. In addition, the design should consider regional characteristics with the concurrent objectives of safe, nutritious food production and environmental protection.

The benefits of crop diversification have been demonstrated in many studies. Wen-Feng Cong and coworkers describe the benefits of crop diversification at three scales: field, farm, and landscape. Hao Yang and coauthors reviewed the multiple functions of intercropping. Intercropping enhances crop productivity and its stability, it promotes efficient use of resources and saves mineral fertilizer, controls pests and diseases of crops and reduces the use of pesticides. It mitigates climate change by sequestering carbon in soil, reduces non-point source pollution, and increases above- and belowground biodiversity of other taxa at field scale ( https://doi.org/10.15302/J-FASE-2021398).

Eric Justes and coworkers proposed the “4C” framework to help understand the role of species interactions in intercropping ( https://doi.org/10.15302/J-FASE-2021414). The four components are competition, complementary, cooperation (facilitation) and compensation, which work often simultaneously in intercropping. Hao Yang and coworkers used the concept of diversity effect from ecology to understand the contribution of complementarity and selection effects to enhanced productivity in intercropping. The complementarity effect consists of interspecific facilitation and niche differentiation between crop species, whereas the selection effect is mainly derived from competitive processes between species such that one species dominates the other ( https://doi.org/10.15302/J-FASE-2021398). Also, Luis Garcia-Barrios and Yanus A. Dechnik-Vazquez dissected the ecological concept of the complementarity and selection effects to develop a relative multicrop resistance index to analyze the relation between higher multicrop yield and land use efficiency and the different ecological causes of overyielding under two contrasting water stress regimes ( https://doi.org/10.15302/J-FASE-2021412).

Odette Denise Weedon and Maria Renate Finckh found that composite cross populations, with different disease susceptibilities of three winter wheat cultivars, were moderately resistant to brown rust and even to the newly emerged stripe rust races prevalent in Europe since 2011, but performance varied between standard and organic management contexts ( https://doi.org/10.15302/J-FASE-2021394).

Comparing the performance of intercrops and sole crops is critical to make a sound evaluation of the benefits of intercropping and assess interactions between species choice, intercrop design, intercrop management and factors related to the production situation and pedoclimatic context. Wopke van der Werf and coworkers review some of the metrics that could be used in the quantitative synthesis of literature data on intercropping ( https://doi.org/10.15302/J-FASE-2021413).

Interspecific interactions provide some of the advantages of intercropping, and can be divided into above- and belowground interactions. Aboveground interactions can include light and space competition, which is influenced by crop species traits. Root exudates are also important in interspecific interactions between intercropped or rotated species. Qi Wang and coworkers estimated the light interception of growth stage of maize-peanut intercropping and corresponding monocultures, and found that intercropping has higher light interception than monoculture, and increasing plant density did not further increase light interception of intercropping ( https://doi.org/10.15302/J-FASE-2021403). Yuxin Yang and coworkers reported that the root exudates of fennel (Foeniculum vulgare) can reduce infection of tobacco by Phytophthora nicotianae via inhibiting the motility and germination of the spores of the pathogen ( https://doi.org/10.15302/J-FASE-2021399).

Focusing on the application of intercropping, Wen-Feng Cong and coworkers formulated species recommendations for different regions of China for different crop diversity patterns and crop species combinations. These authors also suggested three steps for implementing crop diversification on the North China Plain. Although there are multiple benefits of crop diversification, its extension and application are hindered by various technical, organizational, and institutional barriers along value chains, especially in Europe. Based on the findings of the European Crop Diversification Cluster projects, Antoine Messéan and coworkers suggested that there needs to be more coordination and cooperation between agrifood system stakeholders, and establish multiactor networks, toward an agroecological transition of European agriculture ( https://doi.org/10.15302/J-FASE-2021406). In addition, Henrik Hauggaard-Nielsen and coworkers report the outcomes of a workshop for participatory research to overcome the barriers to enhanced coordination and networking between stakeholders ( https://doi.org/10.15302/J-FASE-2021416).

Intercropping, though highly effective in labor-intensive agriculture, may be difficult to implement in machine-intensive, large-scale modern agriculture because appropriate large equipment is not commercially available for planting and harvesting various crop mixtures grown with strip intercropping^{^[6]}. Thus, the appropriate machinery will need to be developed for further practical application in large-scale agriculture.

As the guest editors, we thank all the authors and reviewers for their great contributions to this special issue on “Crop Diversity and Sustainable Agriculture”. We also thank the FASE editorial team for their kind supports.

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Mass transport mechanisms within pervaporation membranes

Yimeng Song, Fusheng Pan, Ying Li, Kaidong Quan, Zhongyi Jiang

《化学科学与工程前沿（英文）》 2019年第13卷第3期页码 458-474 doi: 10.1007/s11705-018-1780-1

摘要： Pervaporation is an energy-efficient membrane technology for separating liquid molecules of similar physical properties, which may compete or combine with distillation separation technology in a number of applications. With the rapid development of new membrane materials, the pervaporation performance was significantly improved. Fundamental understanding of the mass transport mechanisms is crucial for the rational design of membrane materials and efficient intensification of pervaporation process. Based on the interactions between permeate molecules and membranes, this review focuses on two categories of mass transport mechanisms within pervaporation membranes: physical mechanism (solution-diffusion mechanism, molecular sieving mechanism) and chemical mechanism (facilitated transport mechanism). Furthermore, the optimal integration and evolution of different mass transport mechanisms are briefly introduced. Material selection and relevant applications are highlighted under the guidance of mass transport mechanisms. Finally, the current challenges and future perspectives are tentatively identified.

关键词： pervaporation membrane mass transport mechanisms physical mechanism chemical mechanism

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Special issue: Mechanisms and robotics

Jingjun YU

《机械工程前沿（英文）》 2016年第11卷第2期页码 117-118 doi: 10.1007/s11465-016-0399-5

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Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

《化学科学与工程前沿（英文）》 2022年第16卷第12期页码 1700-1712 doi: 10.1007/s11705-022-2207-6

摘要： The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha. Herein, for a better catalyst design and operation parameters optimization, the reaction pathways and equilibrium yields for the catalytic pyrolysis of C_5–8 n/iso/cyclo-paraffins were analyzed thermodynamically. The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways, respectively. However, the formation of light paraffin severely limits the maximum selectivity toward light olefins. The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins. The results are thus useful as a direction for future catalyst improvements, facilitating superior reaction pathways to enhance light olefins. In addition, the equilibrium yield of light olefins increased with increasing the chain length, and the introduction of cyclo-paraffin inhibits the formation of light olefins. High temperatures and low pressures favor the formation of ethylene, and moderate temperatures and low pressures favor the formation of propylene. n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90% and 55.77%, respectively. This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C_5–8 n/iso/cyclo-paraffins from a thermodynamic point of view.

关键词： naphtha catalytic pyrolysis reaction pathway equilibrium yield

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Effects and mechanisms of acupuncture on women related health

《医学前沿（英文）》 doi: 10.1007/s11684-023-1051-5

摘要： Globally, public health interventions have resulted in a 30-year increase in women’s life expectancy. However, women’s health has not increased when socioeconomic status is ignored. Women’s health has become a major public health concern, for those women from developing countries are still struggling with infectious and labor-related diseases, and their counterparts in developed countries are suffering from physical and psychological disorders. In recent years, complementary and alternative medicine has attracted wide attentions with regards to maintaining women’s health. Acupuncture, a crucial component of traditional Chinese medicine, has been used to treat many obstetric and gynecological diseases for thousands of years due to its analgesic and anti-inflammatory effects and its effects on stimulating the sympathetic/parasympathetic nervous system. To fully understand the mechanism through which acupuncture exerts its effects in these diseases would significantly extend the list of available interventions and would allow for more reasonable advice to be given to general practitioners. Therefore, by searching PubMed and CNKI regarding the use of acupuncture in treating obstetric and gynecological diseases, we aimed to summarize the proven evidence of using acupuncture in maintaining women’s health by considering both its effectiveness and the underlying mechanisms behind its effects.

关键词： acupuncture women health clinical efficacy mechanism

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Molecular mechanisms of fatty liver in obesity

null

《医学前沿（英文）》 2015年第9卷第3期页码 275-287 doi: 10.1007/s11684-015-0410-2

摘要：

Nonalcoholic fatty liver disease (NAFLD) covers a spectrum of liver disorders ranging from simple steatosis to advanced pathologies, including nonalcoholic steatohepatitis and cirrhosis. NAFLD significantly contributes to morbidity and mortality in developed societies. Insulin resistance associated with central obesity is the major cause of hepatic steatosis, which is characterized by excessive accumulation of triglyceride-rich lipid droplets in the liver. Accumulating evidence supports that dysregulation of adipose lipolysis and liver de novo lipogenesis (DNL) plays a key role in driving hepatic steatosis. In this work, we reviewed the molecular mechanisms responsible for enhanced adipose lipolysis and increased hepatic DNL that lead to hepatic lipid accumulation in the context of obesity. Delineation of these mechanisms holds promise for developing novel avenues against NAFLD.

关键词： nonalcoholic fatty liver disease insulin resistance obesity