Effect of nano TiO_(2) and SiO_(2) on gelation performance of HPAM/PEI gels for high-temperature reservoir conformance improvement

Nanoparticles have been widely used in polymer gel systems in recent years to improve gelation performance under high-temperature reservoir conditions. However, different types of nanoparticles have different effects on their gelation performance, which has been little researched. In this study, the high-temperature gelation performance, chemical structure, and microstructure of polymer gels prepared from two nanomaterials (i.e., nano-SiO_(2) and nano-TiO_(2)) were measured. The conventional HPAM/PEI polymer gel system was employed as the control sample. Results showed that the addition of nano-TiO_(2) could significantly enhance the gel strength of HPAM/PEI gel at 80 ℃. The gel strength of the enhanced HPAM/PEI gel with 0.1 wt% nano-TiO_(2) could reach grade I. The system also had excellent high-temperature stability at 150 ℃. The enhanced HPAM/PEI gel with 0.02 wt% nano-TiO_(2) reached the maximum gel strength at 150 ℃ with a storage modulus (G′) of 15 Pa, which can meet the need for efficient plugging. However, the nano-SiO_(2) enhanced HPAM/PEI polymer gel system showed weaker gel strength than that with nano-TiO_(2) at both 80 and 150 ℃ with G′ lower than 5 Pa. Microstructures showed that the nano-TiO_(2) enhanced HPAM/PEI gel had denser three-dimensional (3D) mesh structures, which makes the nano-TiO_(2) enhanced HPAM/PEI gel more firmly bound to water. The FT-IR results also confirmed that the chemical structure of the nano-TiO_(2) enhanced HPAM/PEI gel was more thermally stable than nano-SiO_(2) since there was a large amount of –OH groups on the structure surface. Therefore, nano-TiO_(2) was more suitable as the reinforcing material for HPAM/PEI gels for high-temperature petroleum reservoir conformance improvement.

Pharmacologic mechanisms mining and prediction of Xiaoer Qixing Cha Formulae in the treatment of infantile functional dyspepsia based on chemical analysis by UPLC-QTOF/MS and interactive network pharmacology

Objective: To explore the main chemical compounds in Xiaoer Qixing Cha Formulae (XQCF), and investigate its mechanisms for the treatment of infantile functional dyspepsia (IFD). Methods: The chemical components were identified by UPLC-QTOF/MS analytic technique. Targets of the compounds were screened from TCMSP and SWISS database, and disease targets were screened from OMIM and TTD online database. Candidate targets of compounds were mapped to the disease targets as predict therapeutic targets for XQCF. Several networks were constructed and analyzed by Cytoscape ver. 3.2.1. Meanwhile, prescription compatibility in XQCF was interpreted from the network perspective based on distribution of the number of targets. Furthermore, Gene Ontology (GO) enrichment analysis and KEGG pathway analysis were operated via Clue Go to illustrate complex relationships between the potential targets and pharmacological mechanisms. Results: A total of fifty-three compounds were recognized or tentatively characterized belonging to XQCF based on MS data and online chemical database. Sixty-three therapeutic targets were screened. AKT1, FOS, SLC6A4, COMT and 5-HT receptors were focused as therapeutic targets of XQCF. Pathways including carbohydrate digestion and absorption, serotonergic synapse, calcium signaling pathway and cAMP signaling pathway were predicted as significant regulatory pathways. The results indicated that the predicted targets and pathways related in brain-gut axis to a great extent, which could be potential pharmacological mechanism of XQCF for the treatment of IFD. Conclusions: The findings in this study provided the experimental and theoretical basis for further research for XQCF. Those also illustrated a reasonable method worth intensive study on pharmacodynamic mechanisms of TCM Formulae.

Development of re-crosslinkable dispersed particle gels for conformance improvement in extremely high-temperature reservoirs

Micro-scale and nano-scale dispersed gel particles(DPG)are capable of deep migration in oil reservoirs due to their deformability,viscoelasticity,and suitable particle size.Therefore,it has been widely studied and applied in reservoir conformance control in recent years.However,for highly permeable channels,their plugging performance is still limited.In addition,conventional in situ cross-linked polymer gels(ISCPGs)have fast gelation time under extremely high-temperature conditions,which often causes problems such as difficulty in pumping.Therefore,a re-cross linkable dispersed particle gel(RDPG)system applied for conformance control in highly permeable channels of extremely high-temperature petroleum reservoirs was investigated.The particle size distribution,gelation time,gel strength,injection performance,and perfo rmance strength in po rous media were investigated using a laser particle size meter,the Sydansk bottle test method,rheometer,and core displacement experiments,respectively.Results show that the RDPG suspension can be stable for more than 6 months at room temperature with storage modulus G’much lower than 10 Pa.It can pass through the pore throat by elastic deformation effect and does not cause strong blockage.Moreover,it can undergo re-crosslinking reaction at 150℃to form a strong bulk gel.The gel strength G’of re-crosslinked RDPG can be as high as 69.3 Pa,which meets the strength requirement of conformance control.The RDPG suspension has the properties of easy injection,and it also has strong plugging,and high-temperature resistance after re-crosslinked in the core,which can be a very promising material for conformance improvement in extremely high-temperature reservoirs.

过渡金属催化炔类高分子合成进展

过渡金属催化反应的蓬勃发展有力地推动了结构多样、功能丰富的炔类高分子的合成和应用研究.从炔烃单体出发合成炔类高分子经典的策略包括:(1)炔基碳氢(卤)键活化,对应偶联聚合;(2)金属卡拜或卡宾对碳碳三键的活化,对应复分解聚合.最近,我们课题组的工作引入了第三种模式,即通过炔丙位化学键的活化,形成联烯基金属物种,进而介导累积烯烃的原位生成并链式聚合,得到炔烃主链.本专论围绕以上3种反应模式,论述近年来具有代表性的炔类高分子合成方法新发展,并从机理的角度重点讨论新兴的链式聚合方法.

A multi-fidelity prediction model for vertical bending moment and total longitudinal stress of a ship based on composite neural network

In ship engineering,the prediction of vertical bending moment(VBM)and total longitudinal stress(TLS)during ship navigation is of utmost importance.In this work,we propose a new prediction paradigm,the multi-fidelity regression model based on multi-fidelity data and artificial neural network(MF-ANN).Specifically,an ANN is used to learn the fundamental physical laws from low-fidelity data and construct an initial input-output model.The predicted values of this initial model are of low accuracy,and then the high-fidelity data are utilized to establish a correction model that can correct the low-fidelity prediction values.Hence,the overall accuracy of prediction can be improved significantly.The feasibility of the multi-fidelity regression model is demonstrated by predicting the VBM,and the robustness of the model is evaluated at the same time.The prediction of TLS on the deck indicates that just a small amount of high-fidelity data can make the prediction accuracy reach a high level,which further illustrates the validity of the proposed MF-ANN.

An Overview of Stretchable Supercapacitors Based on Carbon Nanotube and Graphene

The wearable demand of modern electronic devices makes flexible and stretchable energy storage device urgently needed.Stretchable and flexible supercapacitors(SCs)are energy storage devices that provide ultrahigh power density while having long-term durability,high security,and electrochemical stability.Among different SCs electrode materials,CNTs and graphene-based materials exhibit great potential in terms of stretchable SCs due to its ultrahigh electrical conductivity,large specific surface area and good mechanical properties.In this review,the state-of-the-art process and achievements in the field of stretchable SCs enabled by CNTs and graphene are presented,which include the novel design strategy,mechanical and electrochemical properties.The final section highlights current challenges and future perspectives on research in this thriving field.

Automated Testing of Web Applications Using Combinatorial Strategies

Recently, testing techniques based on dynamic exploration, which try to automatically exercise every possible user interface element, have been extensively used to facilitate fully testing web applications. Most of such testing tools are however not effective in reaching dynamic pages induced by form interactions due to their emphasis on handling client-side scripting. In this paper, we present a combinatorial strategy to achieve a full form test and build an automated test model. We propose an algorithm called pairwise testing with constraints （PTC） to iraplement the strategy. Our PTC algorithm uses pairwise coverage and handles the issues of semantic constraints and illegal values. We have implemented a prototype tool ComjaxTest and conducted an empirical study on five web applications. Experimental results indicate that our PTC algorithm generates less form test cases while achieving a higher coverage of dynamic pages than the general pairwise testing algorithm. Additionally, our ComjaxTest generates a relatively complete test model and then detects more faults in a reasonable amount of time, as compared with other existing tools based on dynamic exploration.

Organic Semiconducting Materials Based on BDOPV:Structures,Properties,and Applications

What are the major current research activities of your group?To develop high performance organic semiconducting and conducting materials and also to understand their structure-property relationships.We are also interested in the effect of the aggregation states of the con-jugated polymers on their electronic properties,the doping process and mechanism.What is the most important personality for scientific research?Curiosity and the desire to learn.Meanwhile,one should enjoy and be happy in the process of scientific exploration.

Embedding pyridine units in acceptors to construct donor-acceptor conjugated polymers

The development of donor-acceptor(D-A) conjugated polymers greatly promotes the device performance in organic electronics. Recently, the strategy of embedding pyridine units into D-A conjugated polymer backbones has attracted much attention due to the resulted lowered LUMO levels. In addition, the possible non-bonding interactions resulted from the nitrogen atoms also improve the coplanarity of the polymer backbones. All these factors have great contribution to enhance the device performance. In this review, we summarized the recent development of pyridine-embedded D-A conjugated polymers and their applications in organic field-effect transistors(OFETs).

Synergistically enhanced thermoelectric properties of Bi_(2)S_(3) bulk materials via Cu interstitial doping and BiCl_(3) alloying

Bi_(2)S_(3)is composed of inexpensive and environ-mental friendliness elements,which has received extensive interests and been investigated as a promising mid-tempera-ture thermoelectric material for years.Even pure Bi_(2)S_(3)pos-sesses a high Seebeck coefficient and low thermal conductivity,its low electrical conductivity leads to a lowfigure of merit(ZT)value.In this work,Bi_(2)S_(3)fabricated by solid-state melting combined with spark plasma sintering can significantly enhance the thermoelectric performance via introducing small amounts of Cu and BiCl_(3).Cu interstitial doping and Cl substitution on S site result in a large increase in electrical conductivity.Additionally,the enhanced phonon scattering is derived from the point defects caused by element doping,the grain boundaries,and the small amount of sec-ondary phase,which leads to the low thermal conductivity.Finally,a high ZT value of 0.7 is obtained at 773 K and reaches a large average ZT of 0.36 in the temperature range from room temperature(RT)to 773 K for the Cu-interstitial-doped and BiCl_(3)-alloyed(Cu_(0.01)Bi_(2)S_(3)+0.175 mol%BiCl_(3))sample.Furthermore,the mechanical properties of the Cu_(0.01)Bi_(2)S_(3)+0.175 mol%BiCl_(3)sample are lower than those of other Bi_(2)S_(3)samples,which stem from the weak chemical bonding strength.

High thermoelectric properties realized in earth abundant Bi_(2)S_(3) bulk materials via Se and Cl co-doping in solution synthesis process

Bi_(2)S_(3)-based alloys are considered promising thermoelectric materials due to their large Seebeck coefficient and low lattice thermal conductivity.However,low electrical conductivity usually leads to poor electrical transport properties,which seriously restricts their further application in thermoelectric refrigeration and/or power generation.In this work,Bi_(2)S_(3) with high electrical transport properties is synthesized hydrothermally via Se and Cl co-doping.The maximum electrical conductivity value of 483 S cm^(-1) was obtained for the Bi_(2)S_(2.4)Se_(0.4)Cl_(0.20) sample at room temperature.The significant improvement of electrical conductivity gives rise to a high average power factor of 411μW m^(-1) K^(-2) during the measuring temperature range and a peak value of 456μW m^(-1) K^(-2) at 673 K.Benefiting from the largely improved electrical transport properties,a superior ZT value of approximately 0.66 and ZTave.of 0.36 were obtained for Bi_(2)S_(2.4)Se_(0.4)Cl_(0.20),and the theoretically calculated conversion efficiency reached 5.7%.The results indicate that Bi_(2)S_(3) is a promising candidate for thermoelectric applications at medium temperatures.

Buildingcrystal structures ofconjugatedpolymersthrough X-ray diffraction and molecular modeling

Crystal structure of conjugated molecules and polymers is fundamentally critical to understand their multilevel microstructures,carrier transport,and diverse functions.However,to determine the crystal structure of conjugated polymers is a significant challenge,mainly due to the poor crystallinity,weak diffraction,and instability under high-energy radiation.Here,we build the possible crystal structures of eight typical conjugated polymers,covering several widely used molecular segments in organic optoelectronics.We model the packing structures of these seed polymers based on synchrotron X-ray diffractions and molecular simulations.These crystal structures provide a new platform to predict the packing structures of more related polymer systems,extending the molecular scope.Based on this polymer crystal structure database,the multiscale microstructures and charge transport properties of conjugated polymers can be predicted before experiments.This study sets up a polymer crystal structure database to eliminate the current trial-and-error approaches and accelerating the design of high-performance conjugated polymers.

Systematic Investigation of Solution-State Aggregation Effect on Electrical Conductivity in Doped Conjugated Polymers

The mesoscopic solution-state aggregation plays a dominant role in the multilevel self-assembly of conjugated polymers.However,its effect on solid-state microstructures and the electrical performance of conjugated polymers is still a puzzle due to the limitation of characterization techniques.Herein,we have developed four isoindigo-based conjugated polymers with varied alkyl chains to reveal the relationship between solution-state aggregation,molecular doping process,and charge transport properties.

CuPbBi_(5)S_(9) thermoelectric material with an intrinsic low thermal conductivity:Synthesis and properties

CuPbBi_(5)S_(9) compounds have been investigated as gladite for years.However,there have been no significant studies on their physical and chemical properties.This work demonstrates that upon alloying with moderate Cu,Pb,Bi,and S using an appropriate preparation method,quaternary CuPbBi_(5)S_(9) compounds can exhibit excellent figure of merit ZT within the temperature range 298-723 K.A low average velocity,low Young’s modulus and Debye temperature,and large Grüneisen parameter,determined experimentally,indicate strong lattice anharmonicity in CuPbBi_(5)S_(9) crystals.Furthermore,density functional theory calculations(local vibration of low-frequency acoustic phonons)justify the low lattice thermal conductivity of CuPbBi_(5)S_(9) compounds.Because of the low thermal conductivity(0.514 W m^(-1)K^(-1))and a relatively high power factor(293 μW m^(-1)K^(-2)),a maximum ZT of 0.42 was achieved at 723 K for CuPbBi_(5)S_(9) prepared by mechanical alloying combined with solid-state melting.Thus,CuPbBi_(5)S_(9) materials are promising candidates for use as high-performance thermoelectric materials in the intermediate-temperature range.