北京市停车产业化分析研究

分析了北京市机动车现状、停车设施供应现状和停车产业化现状,深入剖析制约停车产业化发展的各种原因,通过回顾国内外城市停车产业化的相关研究,总结经验,展望北京市停车产业化的发展前景。

Comprehensive Understanding of Immune Cells in The Pathogenesis of Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease(NAFLD)is the most common chronic liver disease,defined by several phases,ranging from benign fat accumulation to non-alcoholic steatohepatitis(NASH),which can lead to liver cancer and cirrhosis.Although NAFLD is a disease of disordered metabolism,it also involves several immune cell-mediated inflammatory processes,either promoting and/or suppressing hepatocyte inflammation through the secretion of pro-inflammatory and/or anti-inflammatory factors to influence the NAFLD process.However,the underlying disease mechanism and the role of immune cells in NAFLD are still under investigation,leaving many open-ended questions.In this review,we presented the recent concepts about the interplay of immune cells in the onset and pathogenesis of NAFLD.We also highlighted the specific non-immune cells exhibiting immunological properties of therapeutic significance in NAFLD.We hope that this review will help guide the development of future NAFLD therapeutics.

Cation effects in electrocatalytic reduction reactions:Recent advances

Electrocatalytic reduction reactions,powered by clean energy sources such as solar energy and wind,offer a sustainable method for converting inexpensive feedstocks(e.g.,CO_(2),N_(2)/NO_(x),organics,and O_(2))into high-value-added chemicals or fuels.The design and modification of electrocatalysts have been widely implemented to improve their performance in these reactions.However,bottle-necks are encountered,making it challenging to further improve performance through catalyst development alone.Recently,cations in the electrolyte have emerged as critical factors for tuning both the activity and product selectivity of reduction reactions.This review summarizes recent advances in understanding the role of cation effects in electrocatalytic reduction reactions.First,we introduce the mechanisms underlying cation effects.We then provide a comprehensive overview of their application in electroreduction reactions.Characterization techniques and theoretical calcula-tion methods for studying cation effects are also discussed.Finally,we address remaining challeng-es and future perspectives in this field.We hope that this review offers fundamental insights and design guidance for utilizing cation effects,thereby advancing their development.

Study on the effect of four kinds of raw materials in hypertonic dehydration cell model

It aims to investigate the protective effects of sodium hyaluronate,panthenol,Portulaca oleracea L.and Calendula officinalis L.on hyperosmotic dehydration-induced injury of human immortalized keratinocytes(HaCaT).The safety mass concentrations of four raw materials were screened by detecting cell viability,and the secretion of hyaluronic acid(HA)was determined using the ELISA method.The expression of HaCaT barrier function related genes(OVOL1,EREG,TGM1,TGM2,IVL,IRF6,THBS1,CASP14)was detected at the mRNA level to explore the regulatory effect of four raw materials on these genes.The results demonstrate that pretreatment with the four kinds of raw materials could increase the cell viability after hyperosmotic dehydration,promote the secretion of HA,and improve the expression of barrier function related genes after hyperosmotic dehydration,among which panthenol and Calendula officinalis L.are better.The results show that the four raw materials have a certain protective effect on the hyperosmotic dehydration cell model,which provides data support for its application in cosmetics.

The preparation and properties of N-doped carbon materials and their use for sodium storage

Defect engineering by heteroatom doping gives carbon materials some new characteristics such as a different electronic structure and a high electrochemical activity,making them suitable for high-performance applications.N-doping has been widely investigated because of its similar atom radius to carbon,high electronegativity as well as many different configurations.We summarize the preparation methods and properties of N-doped carbon materials,and discuss their possible use in sodium ion storage.The relationships between N content/configuration and crystallinity,electronic conductivity,wettability,chemical reactivity as well as sodium ion storage performance are discussed.

Formation of mesophase microbeads from bulk mesophase pitch induced by fullerene

A transformation of naphthalene-based coalescenced mesophase pitch(NMP)to mesophase microbeads was achieved by heating a mixture of NMP and fullerene(C_(60)).This is different from the conventional process of the liquid-phase carbonization of isotropic pitch to the emergence of carbon microbeads in the matrix and finally their growth to form a 100%anisotropic bulk meso-phase,but rather a reverse transformation.The effects of C_(60) loading and reaction temperature on the morphological transformation of mesophase were investigated by polarizing optical and scanning electron microscopies.The physical changes in the NMP induced by C_(60) were characterized by thermogravimetric analysis,Fourier transform infrared spectroscopy,X-ray diffractometry and Raman spectroscopy.The results show that the coalesced NMP can be converted to a spherical type at 300-320℃ with the addition of 5%C_(60),and the size of the mesophase microbeads increases with increasing temperature.Furthermore,a model is established to ex-plain the unique induction effect of C_(60) in the transformation process.This work makes the morphological transformation of MP con-trollable,and provides a new idea for the understanding and research of mesophase pitch.

Investigation on p-type doping of PBn unipolar barrier InAsSb photodetectors

The lattice-matched XBn structures of InAsSb,grown on GaSb substrates,exhibit high crystal quali⁃ty,and can achieve extremely low dark currents at high operating temperatures(HOT).Its superior performance is attributed to the unipolar barrier,which blocks the majority carriers while allowing unhindered hole transport.To further explore the energy band and carrier transport mechanisms of the XBn unipolar barrier structure,this pa⁃per systematically investigates the influence of doping on the dark current,photocurrent,and tunneling character⁃istics of InAsSb photodetectors in the PBn structure.Three high-quality InAsSb samples with unintentionally doped absorption layers(AL)were prepared,with varying p-type doping concentrations in the GaSb contact layer(CL)and the AlAsSb barrier layer(BL).As the p-type doping concentration in the CL increased,the device’s turn-on bias voltage also increased,and p-type doping in the BL led to tunneling occurring at lower bias voltages.For the sample with UID BL,which exhibited an extremely low dark current of 5×10^(-6) A/cm^(2).The photocurrent characteristics were well-fitted using the back-to-back diode model,revealing the presence of two opposing space charge regions on either side of the BL.

Overview on Soil Compaction and Sugar Beet Growth

With the advancement of agricultural mechanization,soil compaction has become a serious environmental problem.Soil compaction can increase soil bulk density and firmness,reduce porosity and permeability,and deteriorate soil structure,ultimately inhibit sugar beet growth and reduce both root yield and sugar content.However,few farmers recognize the link between soil compaction and these adverse effects.Soil compaction has a cumulative effect,with significant differences observed in the vertical range of compaction accumulation.The most significant soil compaction occurs in the topsoil of 0-10 cm,and the influence depth can reach 70 cm,but it is small in deep soil,and the inflection point is at a soil depth of 10 cm.The degree of soil compaction is related to soil type,water content,tractor shaft load,tyre type,tyre pressure and operation speed,etc.Therefore,in the production process of sugar beet,it is advisable to avoid high-humidity operations,use low pressure tyres,reduce the number of tractor-units passes over the farmland,and implement agricultural and agronomic measures to minimize soil compaction.These practices will help protect the soil environment and ensure sustainable production of sugar beets.

Why the abnormal phenomena of D-band center theory exist?A new BASED theory for surface catalysis and chemistry

Since the D-band center theory was proposed,it has been widely used in the fields of surface chemistry by almost all researchers,due to its easy understanding,convenient operation and relative accuracy.However,with the continuous development of material systems and modification strategies,researchers have gradually found that D-band center theory is usually effective for large metal particle systems,but for small metal particle systems or semiconductors,such as single atom systems,the opposite conclusion to the D-band center theory is often obtained.To solve the issue above,here we propose a bonding and anti-bonding orbitals stable electron intensity difference(BASED)theory for surface chemistry.The newly-proposed BASED theory can not only successfully explain the abnormal phenomena of D-band center theory,but also exhibits a higher accuracy for prediction of adsorption energy and bond length of intermediates on active sites.Importantly,a new phenomenon of the spin transition state in the adsorption process is observed based on the BASED theory,where the active center atom usually yields an unstable high spin transition state to enhance its adsorption capability in the adsorption process of intermediates when their distance is about 2.5Å.In short,the BASED theory can be considered as a general principle to understand catalytic mechanism of intermediates on surfaces.

A review of the catalytic preparation of mesophase pitch

Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic polycondensation at low temperat-ures is more favorable for synthesizing mesophase pitch, because it circumvents the high-temperature free radical reaction of other thermal polycondensation approaches. The reaction is gentle and can be easily controlled. It has the potential to significantly im-prove the yield of mesophase pitch and easily introduce naphthenic characteristics into the molecules, catalytic polycondensation is therefore a preferred method of synthesizing highly spinnable mesophase pitch. This review provides a synopsis of the selective pre-treatment of the raw materials to prepare different mesophase pitches, and explains the reaction mechanism and associated research advances for different catalytic systems in recent years. Finally, how to manufacture high-quality mesophase pitch by using a cata-lyst-promoter system is summarized and proposed, which may provide a theoretical basis for the future design of high-quality pitch molecules.

A Hybrid Dung Beetle Optimization Algorithm with Simulated Annealing for the Numerical Modeling of Asymmetric Wave Equations

In the generalized continuum mechanics(GCM)theory framework,asymmetric wave equations encompass the characteristic scale parameters of the medium,accounting for microstructure interactions.This study integrates two theoretical branches of the GCM,the modified couple stress theory(M-CST)and the one-parameter second-strain-gradient theory,to form a novel asymmetric wave equation in a unified framework.Numerical modeling of the asymmetric wave equation in a unified framework accurately describes subsurface structures with vital implications for subsequent seismic wave inversion and imaging endeavors.However,employing finite-difference(FD)methods for numerical modeling may introduce numerical dispersion,adversely affecting the accuracy of numerical modeling.The design of an optimal FD operator is crucial for enhancing the accuracy of numerical modeling and emphasizing the scale effects.Therefore,this study devises a hybrid scheme called the dung beetle optimization(DBO)algorithm with a simulated annealing(SA)algorithm,denoted as the SA-based hybrid DBO(SDBO)algorithm.An FD operator optimization method under the SDBO algorithm was developed and applied to the numerical modeling of asymmetric wave equations in a unified framework.Integrating the DBO and SA algorithms mitigates the risk of convergence to a local extreme.The numerical dispersion outcomes underscore that the proposed SDBO algorithm yields FD operators with precision errors constrained to 0.5‱while encompassing a broader spectrum coverage.This result confirms the efficacy of the SDBO algorithm.Ultimately,the numerical modeling results demonstrate that the new FD method based on the SDBO algorithm effectively suppresses numerical dispersion and enhances the accuracy of elastic wave numerical modeling,thereby accentuating scale effects.This result is significant for extracting wavefield perturbations induced by complex microstructures in the medium and the analysis of scale effects.

Two novel Cu(Ⅰ)complexes based on diimide and bisphosphine ligands:synthesis,crystal structure and spectroscopic properties

Two Cu(Ⅰ)complexes[Cu(Bphen)(dppBz)]ClO_(4)·2CH_(3)OH(1)and[Cu_(2)(Bphen)_(2)(dpppda)]BF_(4)(2){Bphen=4,7-diphenyl-1,10-phenanthroline,dppBz=1,2-Bis(diphenylphosphino)benzene,dpppda=N1,N1,N4,N4-tetrakis[(diphenylphosphino)methyl]-1,4-benzenediamin}were synthesized using a one-pot method.X-ray crystallography was used to elucidate their crystal structures and photophysical properties.A series of characterization tests including elemental analysis,NMR,FT-IR,UV-Vis absorption spectroscopy,fluorescence spectroscopy,thermal gravimetric analysis and terahertz time-domain spectroscopy(THz-TDS)were used to further investigate their properties.The results show that complex 1 structure is mononuclear containing two solvent molecules per unit cell,while complex 2 structure is binuclear containing two metal centers per unit cell.According to photophysical properties and density functional theory(DFT)calculations,their luminescence properties can be attributed to metal-to-ligand charge transfer(MLCT).Both complexes have a unique stability,which is confirmed by thermal gravimetric analysis.

Highly Sensitive Photodetectors Based on WS_(2) Quantum Dots/GaAs Heterostructures

The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum dot(QDs)materials in a simple and convenient way to form a heterogeneous structure.Various performance enhancements have been realized through the formation of typeⅡenergy bands in heterostructures,opening up new research directions for the future development of photodetector devices.This work successfully fabricated a high-sensitivity photodetector based on WS_(2)QDs/GaAs NWs heterostructure.Under 660 nm laser excitation,the photodetector exhibits a responsivity of 368.07 A/W,a detectivity of 2.7×10^(12)Jones,an external quantum efficiency of 6.47×10^(2)%,a low-noise equivalent power of 2.27×10^(-17)W·Hz^(-1/2),a response time of 0.3 s,and a recovery time of 2.12 s.This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.

热虹吸管换热器的换热性能测试与分析

为探讨空气-空气整体式热虹吸管换热器的换热性能,利用换热器效能计算公式对其进行计算,并在焓差试验室对空气-空气整体式热虹吸管换热器的迎面风速和换热器管排数进行了测试和研究。结果表明,换热器的计算方法与试验数据最大误差在15%以内,且最大误差出现在温度效率较高时。因此,计算方法适用于工程设计计算。

基于MapGIS的中小区域地下综合管网信息系统的建立

以MapGIS作为地理信息基本工作的平台,以组件式为开发方式,采用Visual Basic6.0为开发工具,以北京雁栖开发区为例,建立了适用于中小区域的地下综合管网管理信息系统。根据系统设计的原则和管网数据的特点,说明了系统总体结构,合理组织管网数据与工作底图数据并实现了系统各项功能,为中小区域的基础设施管理部门提供了一种经济、灵活的高技术管理工具。

在普通数控铣床上用连续展成法加工螺旋锥齿轮

将普通数控铣床增加一套简易的附加铣齿装置 ,使之成为简易的数控铣齿机床 ,实现一机多用 ,为了验证理论推导和数值计算结果 ,在XK50 40数控铣床进行了数控加工实验。

在普通数控铣床上加工连续展成法螺旋锥齿轮

本文将普通数控铣床增加一套简易的附加铣齿装置,使之成为简易的数控铣齿机床,实现一机多用。为了验证理论推导和数值计算结果,本文在 XK5040数控铣床进行了数控加工实验。

中学初级体育老师继续教育教学内容及形式的分析与研究

一、问题继续教育担负着传授新知识、新技术、新技能,培养各级各类在职专业技术人员的业务能力、工作能力、职业思想等任务,继续教育的对象与继续教育的内容,办班形式、教学方法、教材选编等方面有着密切关系。自1978年以来,全国各教育学院对广大中学教师进行了学历培训,大部分中学教师逐步达到现阶段国家所规定的合格学历。为适应时代的要求。

Microstructural evolution of new type Al-Zn-Mg-Cu alloy with Er and Zr additions during homogenization

A comprehensive study on the microstructural evolution of a new type Al-Zn-Mg-Cu-Er-Zr alloy duringhomogenization was conducted by optical microscope,scanning electron microscope,transmission electron microscopy and X-raydiffraction analysis.The results show that serious segregation exists in as-cast alloy,and the primary phases are T(AlZnMgCu),S(Al2CuMg)and Al8Cu4Er,which preferentially locate in the grain boundary regions.The soluble T(AlZnMgCu)and S(Al2CuMg)phases dissolve into the matrix gradually during single-stage homogenized at465°C with prolonging holding time,but the residualAl8Cu4Er phase cannot dissolve completely.Compared with the single-stage homogenization,both a finer particle size and a highervolume fraction of L12-structured Al3(Er,Zr)dispersoids can be obtained in the two-stage homogenization process.A suitablehomogenization scheme for the present alloy is(400°C,10h)+(465°C,24h),which is consistent with the results of homogenizationkinetic analysis.

Mechanical properties and corrosion behaviors of Mg-4Zn-0.2Mn-0.2Ca alloy after long term in vitro degradation

An extruded Mg-4Zn-0.2Mn-0.2Ca alloy was developed as potential biodegradable bone-plate due to its excellent biocompatibility.Long term in vitro immersion in Hank’s solution and bending test were used to evaluate the degradability and the mechanical integrity of the alloy.The results revealed that the degradation rate of the bone-plate increased in the first 7 days and then decreased with the prolonged immersion time before it finally reached a steady stage(about 0.84 mm/a)after immersion for 90 days.The bending strength after immersion for 60 days was 67.6 MPa,indicating that the bone-plate could support certain mechanical load after long term degradation.The formation of corrosion pits after degradation stemmed from the separation of the continuously distributed second phases from Mg matrix under the action of micro-galvanic couples.As a result,the mechanical performance of Mg-4Zn-0.2Mn-0.2Ca alloy was aggravated owing to the corrosion holes on its surface.