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Degradation of polyacrylamide (PAM) and methane production by mesophilic and thermophilic anaerobic digestion: Effect of temperature and concentration

Mona Akbar, Muhammad Farooq Saleem Khan, Ling Qian, Hui Wang

《环境科学与工程前沿（英文）》 2020年第14卷第6期 doi: 10.1007/s11783-020-1277-2

摘要： Abstract • PAM degradation in thermophilic AD in comparison with mesophilic AD. • PAM degradation and its impact on thermophilic and mesophilic AD. • Enhanced methane yield in presence of PAM during thermophilic and mesophilic AD. • PAM degradation and microbial community analysis in thermophilic and mesophilic AD. Polyacrylamide (PAM) is generally employed in wastewater treatment processes such as sludge dewatering and therefore exists in the sludge. Furthermore, it degrades slowly and can deteriorate methane yield during anaerobic digestion (AD). The impact or fate of PAM in AD under thermophilic conditions is still unclear. This study mainly focuses on PAM degradation and enhanced methane production from PAM-added sludge during 15 days of thermophilic (55°C) AD compared to mesophilic (35°C) AD. Sludge and PAM dose from 10 to 50 g/kg TSS were used. The results showed that PAM degraded by 76% to 78% with acrylamide (AM) content of 0.2 to 3.3 mg/L in thermophilic AD. However, it degraded only 27% to 30% with AM content of 0.5 to 7.2 mg/L in mesophilic AD. The methane yield was almost 230 to 238.4 mL/g VSS on the 8th day in thermophilic AD but was 115.2 to 128.6 mL/g VSS in mesophilic AD. Mechanism investigation revealed that thermophilic AD with continuous stirring not only enhanced PAM degradation but also boosted the organics release from the sludge with added PAM and gave higher methane yield than mesophilic AD.

关键词： Polyacrylamide (PAM) degradation Acrylamide (AM) Mesophilic anaerobic digestion Thermophilic anaerobic digestion Methane production

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Additive manufacturing: technology, applications and research needs

Nannan GUO, Ming C. LEU

《机械工程前沿（英文）》 2013年第8卷第3期页码 215-243 doi: 10.1007/s11465-013-0248-8

摘要：

Additive manufacturing (AM) technology has been researched and developed for more than 20 years. Rather than removing materials, AM processes make three-dimensional parts directly from CAD models by adding materials layer by layer, offering the beneficial ability to build parts with geometric and material complexities that could not be produced by subtractive manufacturing processes. Through intensive research over the past two decades, significant progress has been made in the development and commercialization of new and innovative AM processes, as well as numerous practical applications in aerospace, automotive, biomedical, energy and other fields. This paper reviews the main processes, materials and applications of the current AM technology and presents future research needs for this technology.

关键词： additive manufacturing (AM) AM processes AM materials AM applications

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Nanosilver anchored alginate/poly(acrylic acid/acrylamide) double-network hydrogel composites for efficient

《化学科学与工程前沿（英文）》 2023年第17卷第7期页码 893-905 doi: 10.1007/s11705-022-2290-8

摘要： A novel alginate/poly(acrylic acid/acrylamide) double-network hydrogel composite with silver nanoparticles was successfully fabricated using the sol–gel method. The presence of carboxyl and amide groups in the network structure provided abundant active sites for complexing silver ions, facilitating the in situ reduction and confinement of silver nanoparticles. In batch experiments, the optimal silver loading was 20%, and 5 mmol·L^–1 of p-nitrophenol was completely degraded in 113 s with a rate constant value of 4.057 × 10⁻² s^–1. In the tap water system and simulated seawater system, the degradation time of p-nitrophenol at the same concentration was 261 and 276 s, respectively, with a conversion rate above 99%. In the fixed-bed experiment, the conversion rate remained above 74% after 3 h at a flowing rate of 7 mL·min^–1. After 8 cycling tests, the conversion rate remained at 98.7%. Moreover, the catalyst exhibited outstanding performance in the degradation experiment of four typical organic dyes.

关键词： double-network hydrogel dye degradation silver nanoparticles alginate

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反相微乳液聚合机理及模型化处理

李晓,张卫英,袁惠根

《中国工程科学》 2003年第5卷第1期页码 69-73

摘要：

在阐述反相微乳液聚合液滴成核及粒子增长机理的基础上，提出了丙烯酰胺反相微乳液聚合过程的物理模式，并对反相微乳液聚合模型化处理时的关键问题作了扼要讨论。

关键词：反相微乳液聚合机理模型丙烯酰胺

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typical dissolved black carbons and their influence on the formation of disinfection by-products in chlor(am

《环境科学与工程前沿（英文）》 2022年第16卷第12期 doi: 10.1007/s11783-022-1585-9

摘要：

● The physicochemical and structural properties of DBC were characterized.

关键词： Dissolved black carbon (DBC) Chlorine Chloramine Disinfection by-products (DBPs) Disinfection by-products formation potential (DBPFP)

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Solution properties and self-association of multi-blocks like copolymer P(AM/AA) prepared by template

ZHANG Yuxi, WU Feipeng, LI Miaozhen, WANG Erjian

《化学科学与工程前沿（英文）》 2007年第1卷第1期页码 68-71 doi: 10.1007/s11705-007-0014-8

摘要： The association and properties of multi-block like copolymers (TP) of acrylamide (AM) and acrylic acid (AA) prepared by template copolymerization in aqueous solution were studied. The results showed that the copolymers of this type exhibited a significant structure effect compared with that of similar random copolymers (CP) obtained by copolymerization in the absence of template. Decreasing the value of pH or adding Ca ion to the copolymer solution will make phase separation occur. The TEM images demonstrated that the phase separation caused by Ca ion was due to the formation of extensively intermolecular cross-linking. With the increase of the pH value of copolymer solution, the changes of the solution viscosity was similar with that of homopolyacrylic acid, which originally increased and then decreased. But the increase range of template copolymer was higher than that of homopolyacrylic acid. TEM images indicated that at the maximal viscosity the copolymer obtained in the presence of template formed coiled aggregates.

关键词： aqueous solution homopolyacrylic copolymer solution significant structure presence

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Crosslinking acrylamide with EDTA-intercalated layered double hydroxide for enhanced recovery of Cr(VI

Jing Li, Haiqin Yu, Xue Zhang, Rixin Zhu, Liangguo Yan

《环境科学与工程前沿（英文）》 2020年第14卷第3期 doi: 10.1007/s11783-020-1229-x

摘要： Functional groups of AM and EDTA in composite increased removal of Cr(VI) and CR. Removal process reached equilibrium within 30 min and was minimally affected by pH. Elimination of Cr(VI) was promoted by coexisting CR. Adsorption process of CR was less influenced by the presence of Cr(VI). Mechanisms were electrostatic attraction, surface complexation and anion exchange. We prepared ethylenediaminetetraacetic acid (EDTA)-intercalated MgAl-layered double hydroxide (LDH-EDTA), then grafted acrylamide (AM) to the LDH-EDTA by a cross-linking method to yield a LDH-EDTA-AM composite; we then evaluated its adsorptive ability for Congo red (CR) and hexavalent chromium (Cr(VI)) in single and binary adsorption systems. The adsorption process on LDH-EDTA-AM for CR and Cr(VI) achieved equilibrium quickly, and the removal efficiencies were minimally affected by initial pH. The maximum uptake quantities of CR and Cr(VI) on LDH-EDTA-AM were 632.9 and 48.47 mg/g, respectively. In mixed systems, chromate removal was stimulated by the presence of CR, while the adsorption efficiency of CR was almost not influenced by coexisting Cr(VI). The mechanisms involved electrostatic attraction, surface complexation, and anion exchange for the adsorption of both hazardous pollutants. In the Cr(VI) adsorption process, reduction also took place. The removal efficiencies in real contaminated water were all higher than those in the laboratory solutions.

关键词： Chromate Dye adsorption Simultaneous removal Cross-linking method Amino functionalization

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什么才是做出最佳基础设施投资的依据？经济因素？恢复力？或二者皆是？

David Singleton AM

《工程（英文）》 2018年第4卷第2期页码 180-181 doi: 10.1016/j.eng.2018.04.001

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Arbuscular mycorrhizal associations and the major regulators

Li XUE, Ertao WANG

《农业科学与工程前沿（英文）》 2020年第7卷第3期页码 296-306 doi: 10.15302/J-FASE-2020347

摘要：

Plants growing in natural soils encounter diverse biotic and abiotic stresses and have adapted with sophisticated strategies to deal with complex environments such as changing root system structure, evoking biochemical responses and recruiting microbial partners. Under selection pressure, plants and their associated microorganisms assemble into a functional entity known as a holobiont. The commonest cooperative interaction is between plant roots and arbuscular mycorrhizal (AM) fungi. About 80% of terrestrial plants can form AM symbiosis with the ancient phylum Glomeromycota. A very large network of extraradical and intraradical mycelium of AM fungi connects the underground biota and the nearby carbon and nutrient fluxes. Here, we discuss recent progress on the regulators of AM associations with plants, AM fungi and their surrounding environments, and explore further mechanistic insights.

关键词： AM symbiosis signal regulators nutrients phosphate microbiota

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Impact and inhibitory mechanism of phenolic compounds on the formation of toxic Maillard reaction products in food

Jing TENG, Xiaoqian HU, Ningping TAO, Mingfu WANG

《农业科学与工程前沿（英文）》 2018年第5卷第3期页码 321-329 doi: 10.15302/J-FASE-2017182

摘要：

As one of the dominant reactions occurring during thermal treatment of food, the Maillard reaction not only leads to the formation of aroma, browning color and taste compounds, but also contributes to the formation of some unpleasant toxic substances including acrylamide, heterocyclic amines and advanced glycation end products. Polyphenols, one of the most abundant antioxidants in the human diet, are contained in different kinds of foods. In this review, some recent studies on the impact of dietary polyphenols on the formation of acrylamide, heterocyclic amines and advanced glycation end products formed during the Maillard reaction are summarized, including the research work conducted with both chemical model systems and real food model systems; the possible inhibitory mechanisms of different polyphenols are also summarized and discussed in this review. Basically we found that some dietary polyphenols not only scavenge free radicals, but also react with reactive carbonyl species, thus lowering the formation of toxic Maillard reaction products. This review provides a useful theoretical foundation for the application of polyphenols in food safety, and suggests some directions for further study of natural products as inhibitors against the formation of toxic substances in thermally processed food.

关键词： advanced glycation end products acrylamide food safety heterocyclic amine Maillard reaction polyphenols

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Cement mortar with enhanced flexural strength and durability-related properties using

Qing LIU, Renjun LIU, Qiao WANG, Rui LIANG, Zongjin LI, Guoxing SUN

《结构与土木工程前沿（英文）》 2021年第15卷第1期页码 99-108 doi: 10.1007/s11709-021-0721-0

摘要： The low flexural strength and high brittleness of cementitious materials impair their service life in building structures. In this study, we developed a new polymer-modified mortar by polymerization of acrylamide (AM) monomers during the cement setting, which enhanced the flexural and durable performances of mortars. The mechanical properties, micro-and-pore structures, hydrated products, interactions between cement hydrates and polyacrylamide (PAM), and durability-related properties of the mortars were investigated comprehensively. Mortars with 5% PAM exhibited the best performance in terms of flexural strength among all the mixtures. The mechanical strength of cement pastes modified by polymerization of AM monomers was significantly superior to those modified by PAM. The chemical interactions between the polymer molecules and cement hydrates together with the formation of polymer films glued the cement hydrates and polymers and resulted in an interpenetrating network structure, which strengthened the flexural strength. Reductions in porosity and calcium hydroxide content and improvement in capillary water absorption were achieved with the addition of PAM. Finally, the chloride resistance was significantly enhanced with the incorporation of PAM.

关键词： acrylamide in situ polymerization interaction porosity durability

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Surface accuracy optimization of mechanical parts with multiple circular holes for additive manufacturing based on triangular fuzzy number

Jinghua XU, Hongsheng SHENG, Shuyou ZHANG, Jianrong TAN, Jinlian DENG

《机械工程前沿（英文）》 2021年第16卷第1期页码 133-150 doi: 10.1007/s11465-020-0610-6

摘要： Surface accuracy directly affects the surface quality and performance of mechanical parts. Circular hole, especially spatial non-planar hole set is the typical feature and working surface of mechanical parts. Compared with traditional machining methods, additive manufacturing (AM) technology can decrease the surface accuracy errors of circular holes during fabrication. However, an accuracy error may still exist on the surface of circular holes fabricated by AM due to the influence of staircase effect. This study proposes a surface accuracy optimization approach for mechanical parts with multiple circular holes for AM based on triangular fuzzy number (TFN). First, the feature lines on the manifold mesh are extracted using the dihedral angle method and normal tensor voting to detect the circular holes. Second, the optimal AM part build orientation is determined using the genetic algorithm to optimize the surface accuracy of the circular holes by minimizing the weighted volumetric error of the part. Third, the corresponding weights of the circular holes are calculated with the TFN analytic hierarchy process in accordance with the surface accuracy requirements. Lastly, an improved adaptive slicing algorithm is utilized to reduce the entire build time while maintaining the forming surface accuracy of the circular holes using digital twins via virtual printing. The effectiveness of the proposed approach is experimentally validated using two mechanical models.

关键词： surface accuracy optimization multiple circular holes additive manufacturing (AM) part build orientation triangular fuzzy number (TFN) digital twins

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标题作者时间类型操作

Degradation of polyacrylamide (PAM) and methane production by mesophilic and thermophilic anaerobic digestion: Effect of temperature and concentration

Mona Akbar, Muhammad Farooq Saleem Khan, Ling Qian, Hui Wang

期刊论文

Additive manufacturing: technology, applications and research needs

Nannan GUO, Ming C. LEU

期刊论文

Nanosilver anchored alginate/poly(acrylic acid/acrylamide) double-network hydrogel composites for efficient

期刊论文

反相微乳液聚合机理及模型化处理

李晓,张卫英,袁惠根

期刊论文

typical dissolved black carbons and their influence on the formation of disinfection by-products in chlor(am

期刊论文