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Mobile CRISPR-Cas9 based anti-phage system in E. coli

《化学科学与工程前沿（英文）》 2022年第16卷第8期页码 1281-1289 doi: 10.1007/s11705-022-2141-7

摘要： Escherichia coli is one of the most important microbial cell factories, but infection by bacteriophages in the environment may have a huge impact on its application in industrial production. Here, we developed a mobile CRISPR-Cas9 based anti-phage system for bacteriophages defense in E. coli. Two conjugative plasmids pGM1 (phosphoglucomutase 1) and pGM2 carrying one and two guide RNAs, respectively, were designed to defend against a filamentous phage. The results showed that the pGM1 and pGM2 could decrease the phage infection rate to 1.6% and 0.2% respectively in infected cells. For preventing phage infection in E. coli, the pGM2 decreased the phage infection rate to 0.1%, while pGM1 failed to block phage infection. Sequence verification revealed that point mutations in protospacer or protospacer adjacent motif sequences of the phage genome caused loss of the defense function. These results support the potential application of MCBAS in E. coli cell factories to defend against phage infections.

关键词： phage infections anti-phage CRISPR-Cas9 conjugative transfer synthetic biology

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Transport of bacterial cell (

Wei Fan, Qi Li, Mingxin Huo, Xiaoyu Wang, Shanshan Lin

《环境科学与工程前沿（英文）》 2020年第14卷第4期 doi: 10.1007/s11783-020-1242-0

摘要： Abstract • The recharge pond dwelling process induced changes in cell properties. • Cell properties and solution chemistry exerted confounding effect on cell transport. • E. coli cells within different recharge water displayed different spreading risks. Commonly used recharge water resources for artificial groundwater recharge (AGR) such as secondary effluent (SE), river water and rainfall, are all oligotrophic, with low ionic strengths and different cationic compositions. The dwelling process in recharge pond imposed physiologic stress on Escherichia coli (E. coli) cells, in all three types of investigated recharge water resources and the cultivation of E. coli under varying recharge water conditions, induced changes in cell properties. During adaptation to the recharge water environment, the zeta potential of cells became more negative, the hydrodynamic diameters, extracellular polymeric substances content and surface hydrophobicity decreased, while the cellular outer membrane protein profiles became more diverse. The mobility of cells altered in accordance with changes in these cell properties. The E. coli cells in rainfall recharge water displayed the highest mobility (least retention), followed by cells in river water and finally SE cells, which had the lowest mobility. Simulated column experiments and quantitative modeling confirmed that the cellular properties, driven by the physiologic state of cells in different recharge water matrices and the solution chemistry, exerted synergistic effects on cell transport behavior. The findings of this study contribute to an improved understanding of E. coli transport in actual AGR scenarios and prediction of spreading risk in different recharge water sources.

关键词： Artificial groundwater recharge E. coli Transport Simulated column experiments Modeling

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Molecular dynamics modeling of a single diamond abrasive grain in grinding

SAVVOPOULOS,Nikolaos E. KARKALOS,Dimitrios E. MANOLAKOS

《机械工程前沿（英文）》 2015年第10卷第2期页码 168-175 doi: 10.1007/s11465-015-0337-y

摘要：

In this paper the nano-metric simulation of grinding of copper with diamond abrasive grains, using the molecular dynamics (MD) method, is considered. An MD model of nano-scale grinding, where a single diamond abrasive grain performs cutting of a copper workpiece, is presented. The Morse potential function is used to simulate the interactions between the atoms involved in the procedure. In the proposed model, the abrasive grain follows a curved path with decreasing depth of cut within the workpiece to simulate the actual material removal process. Three different initial depths of cut, namely 4 ?, 8 ? and 12 ?, are tested, and the influence of the depth of cut on chip formation, cutting forces and workpiece temperatures are thoroughly investigated. The simulation results indicate that with the increase of the initial depth of cut, average cutting forces also increase and therefore the temperatures on the machined surface and within the workpiece increase as well. Furthermore, the effects of the different values of the simulation variables on the chip formation mechanism are studied and discussed. With the appropriate modifications, the proposed model can be used for the simulation of various nano-machining processes and operations, in which continuum mechanics cannot be applied or experimental techniques are subjected to limitations.

关键词： molecular dynamics abrasive process chip formation cutting force temperature

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Policy options for Agriculture Green Development by farmers in China

Laurence E. D. SMITH

《农业科学与工程前沿（英文）》 2020年第7卷第1期页码 90-97 doi: 10.15302/J-FASE-2019290

摘要：

Farmers are the key agents who manage land and water. Agriculture Green Development (AGD) requires a transformation in farming from high resource consumption and environmental cost to sustainable intensification with high productivity, high resource use efficiency and low environmental risk. This paper analyzes the public policy challenge of AGD and makes the case for a location-sensitive policy mix made up of regulation, advice provision, voluntarism and targeted incentives. The public agricultural extension service in China is a key resource, but one that requires reorientation and reform with the aim of better balancing high farm productivity with environmental protection.

关键词： agriculture environment development incentives policy regulation

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Deposition of copper nanoparticles on multiwalled carbon nanotubes modified with poly (acrylic acid) and their antimicrobial application in water treatment

Li SHENG,Shuhang HUANG,Minghao SUI,Lingdian ZHANG,Lei SHE,Yong CHEN

《环境科学与工程前沿（英文）》 2015年第9卷第4期页码 625-633 doi: 10.1007/s11783-014-0711-8

摘要： A novel hybrid material, Cu-PAA/MWCNTs (copper nanoparticles deposited multiwalled carbon nanotubes with poly (acrylic acid) as dispersant, was prepared and expected to obtain a more effective and well-dispersed disinfection material for water treatment. X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), the X-ray fluorescence (XRF), X-ray photoelectron spectra (XPS), Fourier transform infrared spectra (FT-IR), Raman spectroscopy, and thermal gravimetric analyzer (TGA) were used to characterize the Cu-PAA/MWCNTs. ( ) was employed as the target bacteria. The cell viability determination and fluorescence imaging results demonstrated that Cu-PAA/MWCNTs possessed strong antimicrobial ability on . The deposited Cu was suggested to play an important role in the antimicrobial action of Cu-PAA/MWCNTs.

关键词： multiwalled carbon nanotubes copper nanoparticles antimicrobial activity Escherichia coli (E. coil)

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Association between heavy metals and antibiotic-resistant human pathogens in environmental reservoirs: A review

Christine C. Nguyen, Cody N. Hugie, Molly L. Kile, Tala Navab-Daneshmand

《环境科学与工程前沿（英文）》 2019年第13卷第3期 doi: 10.1007/s11783-019-1129-0

摘要：

Heavy metals can act as co-selecting agents and promote antibiotic resistance.

Most frequent resistances to heavy metals are observed for zinc and cadmium.

P. aeruginosa and E. coli are commonly resistant to heavy metals and antibiotics.

Heavy metals proliferate antibiotic resistance through co- and cross-resistance.

Heavy metal and antibiotic resistances are common near anthropogenic activities.

关键词： Zinc Cadmium Copper Lead E. coli P. aeruginosa

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Behavior of materials for earth and rockfill dams: Perspective from unsaturated soil mechanics

Eduardo E. ALONSO, Rafaela CARDOSO,

《结构与土木工程前沿（英文）》 2010年第4卷第1期页码 1-39 doi: 10.1007/s11709-010-0013-6

摘要： The basis of the design of earth and rockfill dams is focused on ensuring the stability of the structure under a set of conditions expected to occur during its life. Combined mechanical and hydraulic conditions must be considered since pore pressures develop during construction, after impoundment and in drawdown. Other instability phenomena caused by transient flow and internal erosion must be considered. The prediction of the hydro-mechanical behavior of traditional and non-traditional materials used in the construction of dams is therefore fundamental. The materials used for dam’s construction cover a wide range from clayey materials to rockfill. In a broad sense they are compacted materials and therefore unsaturated materials. A summary of the current level of knowledge on the behavior of traditional materials used in the construction of dams is presented in the paper. Regular compacted materials (with a significant clay fraction), rockfill and compacted soft rocks are studied with more detail. The latter are non-traditional materials. They are analysed because their use, as well as the use of mixtures of soil and rock, is becoming more necessary for sustainability reasons.

关键词： dams unsaturated soil mechanics suction rockfill clayey soil mixture

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Sustainable intensification of agriculture in Africa

SCHUT, Ken E. GILLER

《农业科学与工程前沿（英文）》 2020年第7卷第4期页码 371-375 doi: 10.15302/J-FASE-2020357

摘要： Sustainable intensification is a key component of agricultural development in Africa, urgently needed to wean the continent off foreign food supply and to limit agricultural farmland expansion. It is expected that a relatively small fraction of farmers will adopt fertilizer technology, as profits in current economic settings are relatively small while risks are considerable with varying prices and uncertain yield responses. Many smallholders depend on off-farm income and local markets for food supply. Structural adjustments are therefore needed to allow management of larger units of land by trained farmers willing to take this opportunity, while recognizing land right sensitivities. There are large opportunities for African commodity crops to improve food security, including cassava and East African highland banana that strongly respond to fertilizer with limited environmental risks under good management. This requires investments in better functioning markets, local fertilizer production facilities that can produce regional crop blends and cost-efficient distribution networks, providing balanced fertilizers for African farmers.

关键词： Green Revolution Manihot esculenta Musa acuminata sub-Saharan Africa

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表面驱动高压工艺 Perspective

Keith E. Gubbins, Kai Gu, Liangliang Huang, Yun Long, J. Matthew Mansell, Erik E.

《工程（英文）》 2018年第4卷第3期页码 311-320 doi: 10.1016/j.eng.2018.05.004

摘要：

许多化学过程都要在高压下进行，因为高压状态能提高产率，加快化学反应的速率，分离过程中提高溶剂功率，并通过增加分子能量和分子碰撞率来克服活化作用的障碍。通过金刚石砧室压力能高达数百万巴，实验室就能达到这种效果，因此为利用热力学、输运和电子性质来进行化学合成以及合成新材料提供了新的途径。然而，在工业规模上，高压工艺目前正受到压缩成本和有限材料的约束，因此很少有工业过程能够在在压力超过25 MPa的情况下进行。本文提出了一种高压工艺的替代方法，即利用来自固体底物的表面驱动的相互作用产生非常高的局部压力。近期的实验和分子模拟表明，这种相互作用可以产生高达数万巴的局部压力，某些情况下甚至可以达到数百万巴。由于活跃的高压区域分布不均匀，压力在不同方向上存在差异。在许多情况下，增强最多的是平行于底物表面的压力（切向压力）。这种压力是施加在要加工的分子上的，而不是施加在固体底物或容器上。本文综述了现阶段对这种增压的认识，并讨论了一种基于表面驱动力的可行方法来达到高压处理的效果。这种表面驱动高压处理的优点在于，相比传统的整体相位处理，它能达到更高的压力，因为它不需要机械压缩。此外，过程中没有对容器施加更大的压力，因此不用担心材料受损。

关键词：限制高压高压相高压反应高压制造高压化学工艺

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Pore structure of cementitious material enhanced by graphitic nanomaterial: a critical review

GHAHARI, E. GHAFARI, L. ASSI

《结构与土木工程前沿（英文）》 2018年第12卷第1期页码 137-147 doi: 10.1007/s11709-017-0431-9

摘要： Carbon nano tubes (CNT) has been introduced as an efficient nanomaterial in order to improve the mechanical and durability properties of concrete. The effect of CNT on the microstructures of cementitious materials has been widely reported. This paper combines a critical review on the effect of CNT on the pore and microstructure of cement composite with a discussion on the porosity measurement of pastes containing CNT using mercury intrusion porosimetry techniques (MIP). It was found that, surface treatment by H SO and HNO solution forms carboxyl acid groups on CNTs’ surfaces that lead to the improvement of reinforcement. In this scope, this review paper involves analyzing the effect of CNT on the microstructure and the pore structure of cementitious materials. The existing methods of measuring the porosity of cementitious material are reviewed, in particular, the contact angle measurement is discussed in detail in which the most effective parameters and possible errors of calculation is presented.

关键词： carbon nano tubes microstructure porosity mercury intrusion porosimetry cement composite

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A decomposition approach to the design of a multiferroic memory bit

CARMAN, Abdon E. SEPULVEDA

《机械工程前沿（英文）》 2017年第12卷第2期页码 215-223 doi: 10.1007/s11465-017-0446-x

摘要：

The objective of this paper is to present a methodology for the design of a memory bit to minimize the energy required to write data at the bit level. By straining a ferromagnetic nickel nano-dot by means of a piezoelectric substrate, its magnetization vector rotates between two stable states defined as a 1 and 0 for digital memory. The memory bit geometry, actuation mechanism and voltage control law were used as design variables. The approach used was to decompose the overall design process into simpler sub-problems whose structure can be exploited for a more efficient solution. This method minimizes the number of fully dynamic coupled finite element analyses required to converge to a near optimal design, thus decreasing the computational time for the design process. An in-plane sample design problem is presented to illustrate the advantages and flexibility of the procedure.

关键词： multiferroics nano memory piezoelectric optimization

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Product decomposition strategy for optimization of supply chain planning

Braulio BRUNAUD, Maria Paz OCHOA, Ignacio E. GROSSMANN

《工程管理前沿（英文）》 2018年第5卷第4期页码 466-478 doi: 10.15302/J-FEM-2018059

摘要：

Optimization of large-scale supply chain planning models requires the application of decomposition strategies to reduce the computational expense. Two major options are to use either spatial or temporal Lagrangean decomposition. In this paper, to further reduce the computational expense a novel decomposition scheme by products is presented. The decomposition is based on a reformulation of knapsack constraints in the problem. The new approach allows for simultaneous decomposition by products and by time periods, enabling the generation of a large number of subproblems, that can be solved by using parallel computing. The case study shows that the proposed product decomposition exhibits similar performance as the temporal decomposition, and that selecting different orders of products and aggregating the linking constraints can improve the efficiency of the algorithm.

关键词： supply chain planning Lagrangean decomposition mixed-integer programming

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Perspectives in multilevel decision-making in the process industry

Braulio BRUNAUD, Ignacio E. GROSSMANN

《工程管理前沿（英文）》 2017年第4卷第3期页码 256-270 doi: 10.15302/J-FEM-2017049

摘要： Decisions in supply chains are hierarchically organized. Strategic decisions involve the long-term planning of the structure of the supply chain network. Tactical decisions are mid-term plans to allocate the production and distribution of materials, while operational decisions are related to the daily planning of the execution of manufacturing operations. These planning processes are conducted independently with minimal exchange of information between them. Achieving a better coordination between these processes allows companies to capture benefits that are currently out of their reach and improve the communication among their functional areas. We propose a network representation for the multilevel decision structure and analyze the components that are involved in finding integrated solutions that maximize the sum of the benefits of all nodes of the decision network. Although such task is very challenging, significant research progress has been made in each component of this structure. An overview of strategic models, mid-term planning models, and scheduling models is presented to address the solution of each node in the decision network. Coordination mechanisms for converging the integrated solutions are also analyzed, including solving large-scale models, multiobjective optimization, bi-level programming, and decomposition. We conclude by summarizing the challenges that hinder the full integration of multilevel decision making in supply chain management.

关键词： supply chain optimization enterprise-wide optimization multilevel optimization planning scheduling

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DNA alkylation promoted by an electron-rich quinone methide intermediate

Chengyun Huang,Steven E. Rokita

《化学科学与工程前沿（英文）》 2016年第10卷第2期页码 213-221 doi: 10.1007/s11705-015-1541-3

摘要： Biological application of conjugates derived from oligonucleotides and quinone methides have previously been limited by the slow exchange of their covalent self-adducts and subsequent alkylation of target nucleic acids. To enhance the rates of these processes, a new quinone methide precursor with an electron donating substituent has been prepared. Additionally, this substituent has been placed to the nascent -methylene group of the quinone methide for maximum effect. A conjugate made from this precursor and a 5'-aminohexyloligonucleotide accelerates formation of its reversible self-adduct and alkylation of its complementary DNA as predicted from prior model studies.

关键词： quione methide DNA alkylation reversible covalent reaction bioconjugation target-directed modification of nucleic acids

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包容性工程——借助工程技术发明为身体或精神障碍人士赋能

Stassun, Zachary E. Warren, Karl E. Zelik

《工程（英文）》 2021年第7卷第2期页码 141-143 doi: 10.1016/j.eng.2020.06.020

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标题作者时间类型操作

Mobile CRISPR-Cas9 based anti-phage system in E. coli

期刊论文

Transport of bacterial cell (

Wei Fan, Qi Li, Mingxin Huo, Xiaoyu Wang, Shanshan Lin

期刊论文

Molecular dynamics modeling of a single diamond abrasive grain in grinding

SAVVOPOULOS,Nikolaos E. KARKALOS,Dimitrios E. MANOLAKOS

期刊论文

Policy options for Agriculture Green Development by farmers in China

Laurence E. D. SMITH

期刊论文

Deposition of copper nanoparticles on multiwalled carbon nanotubes modified with poly (acrylic acid) and their antimicrobial application in water treatment

Li SHENG,Shuhang HUANG,Minghao SUI,Lingdian ZHANG,Lei SHE,Yong CHEN

期刊论文

Association between heavy metals and antibiotic-resistant human pathogens in environmental reservoirs: A review

Christine C. Nguyen, Cody N. Hugie, Molly L. Kile, Tala Navab-Daneshmand

期刊论文

Behavior of materials for earth and rockfill dams: Perspective from unsaturated soil mechanics

Eduardo E. ALONSO, Rafaela CARDOSO,

期刊论文

Sustainable intensification of agriculture in Africa

SCHUT, Ken E. GILLER

期刊论文

表面驱动高压工艺