Analysis of Wellbore Flow in Shale Gas Horizontal Wells

Theflow behavior of shale gas horizontal wells is relatively complex,and this should be regarded as the main reason for which conventional pipeflow models are not suitable to describe the related dynamics.In this study,numerical simulations have been conducted to determine the gas-liquid distribution in these wells.In particular,using the measuredflow pressure data related to 97 groups of shale gas wells as a basis,9 distinct pipeflow models have been assessed,and the models displaying a high calculation accuracy for different water-gas ratio(WGR)ranges have been identified.The results show that:(1)The variation law of WGR in gas well satisfies a power function relation.(2)The well structure is the main factor affecting the gas-liquid distribution in the wellbore.(3)The Beggs&Brill,Hagedorn&Brown and Gray models exhibit a high calculation accuracy.

Advanced heterostructure of Pd nanosheets@Pt nanoparticles boosts methanol electrooxidation

Heterostructures have emerged as elaborate structures to improve catalytic activity owing to their combined surface and distinct inverse interface.However,fabricating advanced nanocatalysts with facetdependent interface remains an unexploited and promising area.Herein,we render the controlled growth of Pt nanoparticles(NPs)on Pd nanosheets(NSs)by regulating the reduction kinetics of Pt^(2+)with solvents.Specifically,the fast reduction kinetic makes the Pt NPs uniformly deposited on the Pd NSs(U-Pd@Pt HS),while the slow reduction kinetic leads to the preferential growth of Pt NPs on the edge of the Pd NSs(E-Pd@Pt HS).Density functional theory calculations demonstrate that Pd(111)-Pt interface in U-Pd@Pt HS induces the electron-deficient status of Pd substrates,triggering the d-band center downshift and amplifying the Pd-Pt intermetallic interaction.The synergy between the electronic effect and interfacial effect facilitates the removal of poisonous intermediates on U-Pd@Pt HS.By virtue of the Pd NSs@Pt NPs interface,the heterostructure achieves exceptional methanol oxidation reaction activity as well as improved durability.This study innovatively proposes heterostructure engineering with facetdependent interfacial modulation,offering instructive guidelines for the rational design of versatile heterocatalysts.

Effectiveness and Influencing Factors of Comprehensive Rehabilitation Therapy in Patients with Aneurysmal Subarachnoid Hemorrhage

This study aimed to determine the effectiveness of comprehensive rehabilitation for patients with aneurysmal subarachnoid hemorrhage (aSAH) and to explore the factors influencing the prognosis of rehabilitation. This was a retrospective study. Twenty-five patients with aSAH were treated with physical therapy, occupational therapy, speech therapy, cognitive therapy, music therapy, Chinese acupuncture, hyperbaric oxygen, and transcranial magnetic stimulation. The general data of all patients were collected, and the functional scores at admission were compared with those at discharge. The Mini Mental State Examination, Fugl-Meyer Assessment Scale (FMAS) for motor and balance assessment, Holden Functional Ambulation Classification (FAC), modified Rankin Scale, National Institute of Health Stroke Scale, Modified Barthel Index for activities of daily living (ADL), and Glasgow Outcome Scale were significantly improved among 25 patients with aSAH after 1 month of comprehensive rehabilitation training. Hydrocephalus was an independent factor of the ability to perform ADLs (odds ratio, 0.29;95% confidence interval, 2.03. 3.15;p = 0.000). The improvement of ADLs in aSAH patients was not related to sex, surgical method, aneurysm location, age, or smoking status. Comprehensive and professional rehabilitation is effective for the cognition, movement, walking, ADLs, and functional prognosis of patients with aSAH, while early hydrocephalus may be a risk factor for poor ADLs.

A Generation Method of Dithering Signal Based on DFT

This paper proposes a generation method of dithering signal based on Discrete Fourier Transform (DFT), which is not only independent with the input signal but also can decrease the quantization error of the Analog-to-Digital Converter (ADC). A detailed investigation of three typical dithering effects on the quantization error in ADC has been also presented in this paper, to highlight the advantages of the proposed reconstructed dithering signal. The simulation experiment and theoretical analysis illustrate that the reconstructed dithering signal based on DFT can improve the performance of ADC in comparison with traditional typical dithering signal.

Recent advances in photoelectrochemistry-coupled dual-modal biosensors:From constructions to biosensing applications

Precise and sensitive bioanalysis has been the major and urgent pursuit in pathologic diagnosis,food safety,environment monitoring,and drug evaluation.Photoelectrochemical(PEC)bioanalysis,as one of the most promising detection technologies,has rapidly expanded within the field of analysis.However,most of reported PEC analysis approaches still suffer from weak external anti-interference ability,high background,and the risk of false positive or negative errors due to their inherent single-signal readout.To overcome these shortcomings,new PEC-coupled dual-modal analysis approaches have been developed,where a dual-response signal can be derived through two completely different mechanisms and independent signal transduction pathways.This review introduces the basic principles of PEC biosensing and enumerates and classifies the substrate or probe selections,constructions,and applications of PEC-coupled dual-modal biosensors.Furthermore,the challenges and developmental prospects of PEC-coupled dual-mode sensing technologies are evaluated and discussed.We hope that this review will provide valuable insights into the latest advancements and practical applications of dual-mode PEC bioanalysis,which will be of great interest to those seeking to stay informed in this field.

Emerging interactively stretchable electronics with optical and electrical dual-signal feedbacks based on structural color materials

The booming development of wearable devices has aroused increasing interests in flexible and stretchable devices.With mechanosensory functionality,these devices are highly desirable on account of their wide range of applications in electronic skin,personal healthcare,human–machine interfaces and beyond.However,they are mostly limited by single electrical signal feedback,restricting their diverse applications in visualized mechanical sensing.Inspired by the mechanochromism of structural color materials,interactively stretchable electronics with optical and electrical dual-signal feedbacks are recently emerged as novel sensory platforms,by combining both of their sensing mechanisms and characteristics.Herein,recent studies on interactively stretchable electronics based on structural color materials are reviewed.Following a brief introduction of their basic components(i.e.,stretchable electronics and mechanochromic structural color materials),two types of interactively stretchable electronics with respect to the nanostructures of mechanochromic materials are outlined,focusing primarily on their design considerations and fabrication strategies.Finally,the main challenges and future perspectives of these emerging devices are discussed.

Atomic-scale strain analysis for advanced Si/SiGe heterostructure by using transmission electron microscopy

Three-dimensional stacked transistors based on Si/SiGe heterojunction are a potential candidate for future low-power and high-performance computing in integrated circuits.Observing and accurately measuring strain in Si/SiGe heterojunctions is critical to increasing carrier mobility and improving device performance.Transmission electron microscopy(TEM)with high spatial resolution and analytical capabilities provides technical support for atomic-scale strain measurement and promotes significant progress in strain mapping technology.This paper reviews atomic-scale strain analysis for advanced Si/SiGe heterostructure based on TEM techniques.Convergent-beam electron diffraction,nano-beam electron diffraction,dark-field electron holography,and high-resolution TEM with geometrical phase analysis,are comprehensively discussed in terms of spatial resolution,strain precision,field of view,reference position,and data processing.Also,the advantages and critical issues of these strain analysis methods based on the TEM technique are sum-marized,and the future direction of TEM techniques in the related areas is prospected.

Biomimetic asymmetric catalysis

Enzymes are the core for biological transformations in nature.Their structures and functions have drawn enormous attention from biologists as well as chemists since last century.The large demand of bioactive molecules and the pursuit of efficiency and greenness of synthesis have spurred the rapid development of biomimetic chemistry in the past several decades.Biomimetic asymmetric catalysis,mimicking the structures and functions of enzymes,has been recognized as one of the most promising synthetic strategies for the synthesis of valuable chiral compounds.This review summarizes the evolution of asymmetric catalysis inspired by aldolases,vitamin B_(1)/B_(6)-dependent enzymes,NAD(P)H,flavin,hydrogenases,heme oxygenases,nonheme oxygenases,and dinuclear/multinuclear metalloenzymes in aspects of biomimetic design,catalyst development and related catalytic transformations.Those well-established synthetic approaches originating from biological reactions have demonstrated the unique prowess of biomimetic asymmetric catalysis in bridging the gap between bio-catalysis and chemical synthesis.

A vivid Au-porous anodic alumina composite film with the inverted taper structure for label-free detection

Localized surface plasmon resonance(LSPR)has been widely used in medical detection because of its time effectiveness,noninvasiveness,high sensitivity,and relatively simple fabrication process.Porous anodic alumina(PAA)can be regarded as a plasma substrate for label-free detection due to its unique two-dimensional structure.In this work,a vivid Au-PAA composite film with the inverted taper structure was developed by multi-step anodic oxidation and pore-widening processes followed by magnetron sputtering with Au nanoparticles(AuNPs).The highly saturated and bright structural color was generated by the synergistic effect of photonic and plasmonic modes.Interestingly,various Au-PAA composite films with structural colors altering from purple to red were obtained via adjusting the height/diameter ratio of PAA.Benefiting from the inverted taper structure,light trap characteristics were effectively enhanced by increasing the incident light and reducing the diffuse light.In addition,a finite difference time domain(FDTD)model was proposed to predict the relationship between the reflectance peak and the height of the composite film,and the simulated data were in good agreement with the experimental results.As a proof of concept,labelfree detections of various reagents(water,ethanol,glycol,glycerol,and glucose),the concentration of glucose(refractive index sensitivity of 376 nm/RIU,RIU:refractive index unit),and thrombin(detection limit of 0.1×10^(-7)mol/L)were realized by the Au-PAA composite film.This vivid Au-PAA composite film provides a very powerful tool for in-situ label-free bio-detection.

A Fluorescein Derivative Chemosensor Combined with Triplet-Triplet Annihilation Upconversion System for Ratiometric Sensing of Cysteine

A derivative of fluorescein,fluorescein O,O-diacrylate(FODA),was utilized in a triplet-triplet annihilation upconversion(TTA-UC)system to develop a composite ratiometric chemosensor capable of detecting cysteine(Cys).FODA acted as both the probe for Cys and the energy acceptor for upconversion(UC)emission,thereby making UC a responsive signal to Cys.In addition,the phosphorescence signal of the sensitizer in the TTA-UC system remained constant and did not respond to Cys,making it an ideal internal reference signal for constructing a ratiometric sensor.Through this simple strategy,traditional fluorescent probes can be combined with TTA-UC system to establish a ratiometric sensing platform,which can be applied in more scenarios due to the longer wavelength excitation.

Homogenization with the Quasistatic Tresca Friction Law:Qualitative and Quantitative Results

Modeling of frictional contacts is crucial for investigating mechanical performances of composite materials under varying service environments.The paper considers a linear elasticity system with strongly heterogeneous coefficients and quasistatic Tresca friction law,and studies the homogenization theories under the frameworks of H-convergence and small ε-periodicity.The qualitative result is based on H-convergence,which shows the original oscillating solutions will converge weakly to the homogenized solution,while the author’s quantitative result provides an estimate of asymptotic errors in H^(1)-norm for the periodic homogenization.This paper also designs several numerical experiments to validate the convergence rates in the quantitative analysis.

基于三维多物理场强耦合模型的超导磁悬浮振动特性

高温超导磁悬浮具有无源自稳定、节能、环保等优点,是未来轨道交通(如真空管道交通)发展的主要技术模式之一.针对目前关于高温超导磁悬浮振动特性理论建模研究的不足,本文基于三维电磁-热-力多物理场强耦合模型提出了高温超导磁悬浮振动特性模拟方法,建立了相关的理论模型.该理论模型可预测任意结构的高温超导磁悬浮系统在典型外界激励(如横风、地震、轨道不平顺等)作用下的振动响应特性,研究各种典型外界激励下系统的振动行为特征、失稳发生的临界条件及其对系统悬浮稳定性的影响规律,为高温超导磁悬浮技术在轨道交通、电磁发射等领域应用的可行性及安全性提供一定的科学判据.

Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation

A submerged internal circulating membrane coagulation reactor （MCR） was used to treat surface water to produce drinking water. Polyaluminum chloride （PAC1） was used as coagulant, and a hydrophilic polyvinylidene fluoride （PVDF） submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure （TMP）, zeta potential （ZP） of the suspended particles in raw water, and KMnO4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China （GB B749-2006）, as evaluated by turbidity （〈1 NTU） and total organic carbon （TOC） （〈5 mE/L） measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon （DOC） in the raw water also increased with increasing TMP in the range of 0.01-0.05 MPa. High ZP induced by PAC1, such as 5-9 mY, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2 mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes.

高原心血管疾病的防治及相关标志物研究进展

目的综述高原心血管疾病的防治及相关标志物研究进展。资料来源与选择国内外该领域的相关文献。资料引用以"高原""心血管疾病"等为关键词,从PubMed、维普、中国知网、万方医学网等相关数据库遴选近年来相关文献63篇。资料综合肺动脉高压、长期缺氧为部分常见高原疾病的发生发展机制。高原心血管疾病常见的预防和治疗策略包括早期筛查、缓解缺氧、治疗水肿。基因、血清和影像是高原心血管疾病预防、诊断和治疗的标志物。结论研究高原心血管疾病的发生发展机制、相关标志物和防治策略,对推进该疾病防治的理论研究和实际应用,降低其发病率和死亡率具有重要意义。

Colloidal Virus Particles with Hierarchical Nanomorphology and Facile Biosurface Modification

Aiming to the enormous requirement for the epidemic defense researches,we designed and constructed a spherical colloidal virus particle(CVP)to mimic nature virus in morphology,physical,chemical and biological characteristics,via coating spiky protein on col-loidal nanoparticles(CNPs)core with bulge hierarchical nanomorphology.The novel virus-like surface nanoparticles can easily be synthesized.The physical,chemical nature and the formation mechanism of the prepared CVPs were characterized and discussed.The synthesized CVPs are similar in size and envelope thickness to common natural viruses.It was demonstrated that the diameter of CVPs is about 238±12 nm,including an 8 nm thickness protein crown with bulges of 33 nm in average width.The CVPs with an isoelectric point of 4.5,meets the native virus property of negative charge under neutral condition.The protein crown enhances the roughness remarkably from 10 nm(CNPs)to 22 nm(CVPs)determined by atomic force microscopy.Thanks to the biomimetic rough morphology,the CVPs show greatly superior cellular uptake performance compared to CNPs,ovalbumin(OVA)and smoothed col-loidal particles(SCPs).The formation mechanism of protein crown with specific thickness can be attributed to the electrostatic in-teraction,protein's flexible structure and specific wettability.These results indicate that the as-prepared artificial virions mimic na-ture viruses in multi-dimension,in terms of size,surface rough morphology,surface negative charge and glycoprotein envelope composition.The synthetic colloidal virus particles pave a facile way toward engineering virus particles substitute for virus-related diseases prevention,diagnostics and cellular delivery vectors.