The present paper deals with the induced orientational order of the probe molecules dissolved in the uniaxially strained rubbers measured by using deuterium NMR. The distinctive dependence of the quadrupolar splitting...The present paper deals with the induced orientational order of the probe molecules dissolved in the uniaxially strained rubbers measured by using deuterium NMR. The distinctive dependence of the quadrupolar splitting on the swelling, elongation and crosslinking density was observed. The orientational order arising from the correlation between chain segments decreases with the increase of the numbers of both links between junctions and solvent molecules around segments.展开更多
MgO nanosheets with exposed（111） facets were obtained through the preparation of Mg（OH）2 precursor by a hydrothermal method in the presence of oleylamine and subsequent calcination in air. The different preferred ...MgO nanosheets with exposed（111） facets were obtained through the preparation of Mg（OH）2 precursor by a hydrothermal method in the presence of oleylamine and subsequent calcination in air. The different preferred orientational assemblies of Mg O nanosheets, achieved by adjusting the polarity of dispersing solvents（ethanol and cyclohexane） during the sample preparation, show different structural and spectral features.展开更多
As a part of our systematic study of the physical properties of the compounds of symmetric liquid crystal dimer homologous series, α,ω-bis-(4-n-alkylaniline benzylidene-4’-oxy) alkanes (m.OnO.m), we report here an ...As a part of our systematic study of the physical properties of the compounds of symmetric liquid crystal dimer homologous series, α,ω-bis-(4-n-alkylaniline benzylidene-4’-oxy) alkanes (m.OnO.m), we report here an optical study of two nematogenic compounds of this series viz., 6.O12O.6 and 7.O12O.7 by carrying out the measurement of extraordinary and ordinary refractive indices using modified spectrometer. The molecular polarizability anisotropies are evaluated using Lippincott δ-function model, the molecular vibration method, Haller’s extrapolation method and scaling factor method. The molecular polrizabilities, αe and αo are calculated using Vuks’ isotropic field model and Neugebauer’s anisotropic field model. The orientational order parameter, S, is estimated by using the molecular polarizability values calculated from refractive index and denstity data as well as polarizability anisotropy values calculated as a function of temperature in the nematic phase of both of the dimers. These values are discussed with reference to the order parameter values obtained directly from the optical birefringence, Δn, data without assuming any internal field. A comparison of the order parameter values from all of these methods was carried out in the light of available literature data.展开更多
The orientational order is an important concept of the materials composed of large molecules or clusters. Using high-resolution scanning tunneling microscopy, we have studied the orientational order of two kinds of ty...The orientational order is an important concept of the materials composed of large molecules or clusters. Using high-resolution scanning tunneling microscopy, we have studied the orientational order of two kinds of typical low-dimensional C60 lattices: two-dimensional molecules array and C60(111) multi-layer film surface. Due to the change of the crystal field, their orientational orders are distinctly different from those in bulk system, and some unique phenomena appear.展开更多
Due to the important role ofδphase's quantity and morphology in the mechanical and fatigue properties of Inconel 718 alloy and its components,it is necessary to renew insights into the effect of cold deformation ...Due to the important role ofδphase's quantity and morphology in the mechanical and fatigue properties of Inconel 718 alloy and its components,it is necessary to renew insights into the effect of cold deformation on theδphase precipitation,especially on the morphology evolution.Therefore,the nucleation and growth behavior ofδphase in cold-rolled Inconel 718 alloy during aging were investigated.The results show that the precipitation rate and volume fraction ofδphase increase with increasing the cold rolling reduction from 10%to 50%.The volume fraction ofδphase reaches equilibrium after 5 h,remaining at 5.98%,6.52%,and 6.79%under different rolling reductions(10%,30%,and 50%),respectively.The nucleation ofδphase mainly occurs on different sites(grain boundaries,new twin boundaries and old twin boundaries)under 10%rolling reduction,whileδphase mainly nucleates on the new grain boundaries of static recrystallization due to 50%rolling reduction.And the growth ofδphase undergoes a process of alternate orientation growth from spherical(nucleation)→short rod(longitudinal orientation growth)→short rod(radial orientation growth)→dynamic equilib-rium.Under 10%rolling reduction,δphase tends to grow into the matrix,while under 50%rolling reduction,the orientation grows faster and is easily affected by the grain boundary curvature.展开更多
New concepts such as intramolecular orientational order parameter and corresponding model as well as theory were proposed to describe the intramolecular orientation of mesogenic units in the liquid crystalline polymer...New concepts such as intramolecular orientational order parameter and corresponding model as well as theory were proposed to describe the intramolecular orientation of mesogenic units in the liquid crystalline polymer chains. The relationship between the intramolecular orientational order parameter and the molecular geometrical parameters such as the bond angle, the bond rotational angle and the rotational potential energy of chemical bonds was deduced. A significant even-odd oscillation of the intramolecular orientational order parameter of LCPs with different length of flexible spacer was found and rationally related to even-odd zig-zag manner of transition properties The verification and application of the theory are also discussed. The isotropic transition temperature predicted by the theory is shown to be in favourable agreement with the experiments.展开更多
Re-innervation of sensory and motor neurons on a defined area of the body wall was studied in two species of leeches, Whitmania pigra and Hirudo medicinalis, as a model of segmental animals. Following isolation and ro...Re-innervation of sensory and motor neurons on a defined area of the body wall was studied in two species of leeches, Whitmania pigra and Hirudo medicinalis, as a model of segmental animals. Following isolation and rotation of a tube of body wall, the mechanical sensory and annular erection (AE) motor neurons re-innervated the body wall, at a rate of approximately 3. 8 -8. 4 μm/h. The patterns of re-innerva-tion by pairs of neurons on each side of a ganglion were bilaterally symmetric. The repairs are synchronous for the sensory and motor neurons which are of different functions but in a same ganglion. The gap junctions are widely spread in leech between neurons and glia cells, as well as among the neurons and glia cells themselves. Therefore, it is proposed that the nervous system repair is regulated by a low-resistance pathway. In the xenotransplantation experiments, neurons recognized target tissues before the immuno-recognition and rejection.展开更多
To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the...To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.展开更多
Copolymers of N-pentafluorophenyl maleimide (PFPMI) with methyl methacrylate (MMA) were synthesized by a free radical initiator, such as AIBN. The refractive indexes of the copolymers remained nearly constant (1.4970 ...Copolymers of N-pentafluorophenyl maleimide (PFPMI) with methyl methacrylate (MMA) were synthesized by a free radical initiator, such as AIBN. The refractive indexes of the copolymers remained nearly constant (1.4970 at 532 nm) regardless of the polymer composition. These copolymers also showed high thermal stability. The orientational and photoelastic birefringence of the copolymers obtained were measured. Since both of the orientational and photoelastic birefringences of PMMA are negative whereas poly(PFPMI) exhibits positive, thus we have obtained nearly zero orientational and photoelastic birefringence polymers when the ratios of MMA/PFPMI were 91.8/8.2 and 97.0/3.0 mol%, respectively. Based on the experimental data, the ratios of MMA/PFPMI for zero birefringence were determined to be 88.9/11.1 and 93.8/6.2 mol% for orientational and photoelastic birefringence, respectively. The Tgs of corresponding copolymers were estimated to be 128 and 122 ℃.展开更多
In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-qualit...In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-quality urban development and continuously meet people’s growing aspirations for a better life.Wuhu,in central China’s Anhui Province,has consistently enhanced its urban functions and services to build a modern,people-oriented city that is innovative,livable,beautiful,resilient,and smart.展开更多
Electromagnetic interference(EMI)shielding materials principally attain shielding by reflecting electromagnetic waves through impedance mismatch caused by high conductivity,which inevitably leads to secondary electrom...Electromagnetic interference(EMI)shielding materials principally attain shielding by reflecting electromagnetic waves through impedance mismatch caused by high conductivity,which inevitably leads to secondary electromagnetic wave pollution.Consequently,the development of multifunctional,low-reflection electromagnetic shielding materials remains a significant challenge.Materials that are lightweight,possess high mechanical strength,exhibit excellent electromagnetic shielding absorption,and demonstrate low reflectivity have historically been the focus of significant interest.Natural silk,lightweight and strong,is an ideal composite matrix.Regenerated silk fibroin(RSF)synthesized via a bottom-up approach and cross-linked with polyvinyl alcohol(PVA)forms an aerogel matrix with remarkable compressive strength.In accordance with the principle of integrating functional design with structural design,spherical NiFe_(2)O_(4)particles were grown on the MXene surface via electrostatic self-assembly and combined with RSF/PVA as the aerogel absorptive layer,while RSF/PVA/MXene served as the reflective layer.A vertically oriented structure of Janus aerogel was prepared through sequential directed freezing.The resulting aerogel with 0.058 g/cm^(3) reveals the high compression strength(3.52 MPa).Reasonable functional and structural design enables aerogel to effectively dissipate incident electromagnetic waves through absorption,reflection,and reabsorption processes,achieving an average SET value of 48.05±1.75 dB and reaching a minimum reflection coefficient of 0.19.Furthermore,the aerogel displays remarkable infrared stealth capabilities.This lightweight,rigid,multifunctional aerogel is poised to play a significant role in the field of next-generation electronic devices.展开更多
Single nanoparticle tracking(SPT)is a unique and powerful tool to investigate the interaction between nanoparticles and cells,which is of considerable importance for nanotechnology applications in biomedical fields an...Single nanoparticle tracking(SPT)is a unique and powerful tool to investigate the interaction between nanoparticles and cells,which is of considerable importance for nanotechnology applications in biomedical fields and in-depth understanding of biological activities.However,previous work typically focused on translations of single nanoparticles while they undergo both translational and rotational motions.In this study,we obtained both the translational and rotational dynamics of single gold nanorods during their cellular internalization process using dual-channel polarization microscopy.In particular,the azimuth and polar angles were integrated into a polar coordinate systemto obtain three general orientation distribution patterns,found to have a close relationship with the nanoparticle cellular internalization process and time-dependent alterations.Moreover,the patterns accompanied by trajectories,translational and rotational coefficients,the azimuth and polar angles,and other parameters provided a wealth of knowledge on the nanoparticle cellular internalization dynamics with unprecedented details.We observed that the gold nanorods could initially assume a tip-first quick rotation state with partially restricted orientations,then change to a strongly confined near-vertical insertion state with slight angular fluctuations,and eventually transform into a random and fast rotation state.Our methodology opens up a new avenue for a detailed understanding of biological processes.展开更多
Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior coll...Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.展开更多
Across four studies,we explore the impact of solitude on consumers’reliance on feelings versus reasons in decision making,along with the underlying mechanism and boundary conditions.The results indicate that solitude...Across four studies,we explore the impact of solitude on consumers’reliance on feelings versus reasons in decision making,along with the underlying mechanism and boundary conditions.The results indicate that solitude individuals(vs.non-solitude)would prefer feeling-based strategy in decision-making,resulting in a higher intention of choosing the affectively superior option over the cognitively superior option(Study 1).Self-focus plays the underlying mechanism in the solitude effect(Study 2).Moreover,we also examine two boundary conditions:motivation(Study 3)and temporal orientation(Study 4),which indicates that involuntary motivation and future orientation can mitigate the solitude effect on affective processing.These findings provide insights into consumers’judgments of product attributes and selection of decision-making strategies according to their situations.展开更多
Although magnesium-aluminum alloys,such as AZ80 and AZ91 have promising application potential in automotive,high-speed train and aerospace fields,their age-hardening response is generally not very appreciable.In this ...Although magnesium-aluminum alloys,such as AZ80 and AZ91 have promising application potential in automotive,high-speed train and aerospace fields,their age-hardening response is generally not very appreciable.In this work,the aging-hardening response of AZ80 alloy was effectively enhanced by applying cold-rolling deformation before conducting conventional aging treatment at 200°C.Compared to the directly aged sample,the yield strength of the pre-rolling and aged sample was increased by 35 MPa.Electron microscope examination confirmed that profuse{10¯11}and{10¯11}-{10¯12}twins,consisting of high density of dislocations and stacking faults,were generated by cold rolling.Blocky or ellipsoidal Mg_(17)Al_(12)precipitates formed at the twin boundaries(TBs)during subsequent aging treatment.Crystallographic analysis indicated that the precipitates at{10¯11}TBs always held an identical Potter OR with both the matrix and twin,while the precipitates at{10¯11}-{10¯12}TBs exhibited three different ORs:Burgers OR,Potter OR and P-S OR with either the matrix or the twin.Moreover,recrystallized grains were found inside{10¯11}-{10¯12}double twins after peak-aging at 200°C,implying that precipitation and recrystallization might occur concurrently along TBs at a relatively low temperature.It was speculated that the highly stored energy inside twins and the high elastic energy between the precipitates and twins were driving factors for the occurrence of recrystallization.展开更多
Determining the orientation of in-situ stresses is crucial for various geoscience and engineering appli-cations.Conventional methods for estimating these stress orientations often depend on focal mechanism solutions(F...Determining the orientation of in-situ stresses is crucial for various geoscience and engineering appli-cations.Conventional methods for estimating these stress orientations often depend on focal mechanism solutions(FMSs)derived from earthquake data and formation micro-imager(FMI)data from well logs.However,these techniques can be costly,depth-inaccurate,and may lack spatial coverage.To address this issue,we introduce the use of three-dimensional(3D)seismic data(active sources)as a lateral constraint to approximate the 3D stress orientation field.Recognizing that both stress and fracture patterns are closely related to seismic velocity anisotropy,we derive the orientation of azimuthal anisotropy from multi-azimuth 3D seismic data to compensate for the lack of spatial stress orientation information.We apply our proposed workflow to a case study in the Weiyuan area of the Sichuan Basin,China,a region targeted for shale gas production.By integrating diverse datasets,including 3D seismic,earthquakes,and well logs,we develop a comprehensive 3D model of in-situ stress(orientations and magnitudes).Our results demonstrate that the estimated anisotropy orientations from 3D seismic data are consistent with the direction of maximum horizontal principal stress(SHmax)obtained from FMIs.We analyzed 12 earthquakes(magnitude>3)recorded between 2016 and 2020 for their FMSs and compressional axis(P-axis)orientations.The derived SHmax direction from our 3D stress model is 110°ES(East-South),which shows excellent agreement with the FMSs(within 3.96°).This close alignment validates the reliability and precision of our integrated method for predicting 3D SHmax orientations.展开更多
Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation pr...Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation process under two different orientations of σ_(2),i.e.σ_(2) parallel to the fracture plane(Scheme 2)and σ_(2) cutting through the fracture plane(Scheme 3),under varying σ_(3) from 10 MPa to 40 MPa.The peak or fracture reactivation strength,deformation,failure mode,and post-peak mechanical behavior of intact(Scheme 1)and pre-fractured(Schemes 2 and 3)specimens were also compared.Results show that for intact specimens,the stress remains nearly constant in the residual sliding stage with no stick-slip,and the newly formed fracture surface only propagates along the σ_(2) direction when σ_(3) ranges from 10 MPa to 30 MPa,while it extends along both σ_(2) and σ_(3) directions when σ_(3) increases to 40 MPa;for the pre-fractured specimens,the fractures are usually reactivated under all the σ_(3) levels in Scheme 2,but fracture reactivation only occurs when σ_(3) is greater than 25 MPa in Scheme 3,below which new faulting traversing the original macro fracture occurs.In all the test schemes,both ε_(2) and ε_(3) experience an accumulative process of elongation,after which an abrupt change occurs at the point of the final failure;the degree of this change is dependent on the orientation of the new faulting or the slip direction of the original fracture,and it is generally more than 10 times larger in the slip direction of the original fracture than in the non-slip direction.Besides,the differential stress(peak stress)required for reactivation and the post-peak stress drop increase with increasing σ_(3).Post-peak stress drop and residual strength in Scheme 3 are generally greater than those in Scheme 2 at the same σ_(3) value.Our study clearly shows that intermediate principal stress orientation not only affects the fracture reactivation strength but also influences the slip deformation and failure modes.These new findings facilitate the mitigation of dynamic geological hazards associated with fracture and fault slip.展开更多
Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the...Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically calculated.The effect of precipitate ripening on the Goss texture and magnetic property was investigated.Data indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate increased.Secondary recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}<227>oriented grains growing abnormally and a magnetic induction intensity of 1.90T.Furthermore,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture.However,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 T.At a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this study.The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties.展开更多
Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We ...Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We report the preparation of novel aerogel materials with a much better per-formance.Using the driving force of graphene oxide(GO)self-assembly andπ-πinteractions,carbon nanotubes(CNTs)were attached to the GO sheets,and an oriented composite carbon skeleton was constructed using“hydro-plastic foam-ing”.The introduction of CNTs significantly increased the strength of the skeleton and gave the aerogel an excellent re-versible compressibility.The innovative use of cold pressing greatly improved the thermal conductivity and flexibility of the aerogel,providing new ideas for the development of high-performance aerogels.Tests show that the obtained graphene composite aerogel has a reversible compressive strain of over 90%and can withstand 500 compression cycles along the direc-tion of pore accumulation.It can endure more than 10000 bending cycles perpendicular to the direction of composite carbon layer stacking,and its in-plane thermal conductivity reaches 64.5 W·m^(-1)·K^(-1).When filled with phase change materials,the high porosity of the carbon skeleton enables the material to have a high phase change filling rate,and its phase change enthalpy is greater than 150 J/g.Thanks to the exceptional flexibility of the carbon skeleton,the macrostructure of phase change materials can be bent as needed to adapt to thermal management scenarios and conform to device shapes.This significantly enhances practical application compatibility,providing flexible support for temperature control and thermal management across diverse device forms.展开更多
A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing.The necessity for its sophistication arises from the availability of multi-dimensional s...A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing.The necessity for its sophistication arises from the availability of multi-dimensional sensing signals.Simultaneous monitoring of the redox current and color change synchronized with the oxidation state change significantly enhances sen-sitivity and selectivity.This study aimed to elucidate the modification of an indium tin oxide(ITO)electrode with a viologen monolayer with an ordered orientation.Novel methods were developed to immobilize a viologen molecule bearing a car-boxyl group to form assembled monolayers through a condensation reaction using 1-ethyl-3-(3-dimethylaminopropyl)-car-bodiimide with N-hydroxy-succinimide(EDC/NHS).In the two methods of immobilization,one utilizes a two-step process to firstly form an aromatic siloxane base layer and subsequently attach the viologen derivative through an amide linkage by post-amidation.The other employs a direct ester linkage between the hydroxyl groups of the ITO surface and the car-boxyl group of the viologen derivative.The latter method was also applied to immobilize a ferrocenyl group at a very short distance from the ITO surface.Potential-modulated UV-visible transmission absorption spectral measurement techniques with oblique incidence of plane-polarized light were employed to determine the orientation of the longitudinal axis of the reduced form of the viologen.The frequency dependence data of the potential-modulated transmission absorption signals were utilized to analyze the electron transfer kinetics.The performance of the two viologen-modified electrodes was com-pared to that of an ITO modified by post-amidation to the most commonly used base layer prepared with 3-aminopropyl triethoxysilane.展开更多
基金Supported by the National Natural Science Foundation of China
文摘The present paper deals with the induced orientational order of the probe molecules dissolved in the uniaxially strained rubbers measured by using deuterium NMR. The distinctive dependence of the quadrupolar splitting on the swelling, elongation and crosslinking density was observed. The orientational order arising from the correlation between chain segments decreases with the increase of the numbers of both links between junctions and solvent molecules around segments.
基金supported by the National Natural Science Foundation of China (Nos. 21673046, 21473036, 21371035, 91645201)
文摘MgO nanosheets with exposed（111） facets were obtained through the preparation of Mg（OH）2 precursor by a hydrothermal method in the presence of oleylamine and subsequent calcination in air. The different preferred orientational assemblies of Mg O nanosheets, achieved by adjusting the polarity of dispersing solvents（ethanol and cyclohexane） during the sample preparation, show different structural and spectral features.
文摘As a part of our systematic study of the physical properties of the compounds of symmetric liquid crystal dimer homologous series, α,ω-bis-(4-n-alkylaniline benzylidene-4’-oxy) alkanes (m.OnO.m), we report here an optical study of two nematogenic compounds of this series viz., 6.O12O.6 and 7.O12O.7 by carrying out the measurement of extraordinary and ordinary refractive indices using modified spectrometer. The molecular polarizability anisotropies are evaluated using Lippincott δ-function model, the molecular vibration method, Haller’s extrapolation method and scaling factor method. The molecular polrizabilities, αe and αo are calculated using Vuks’ isotropic field model and Neugebauer’s anisotropic field model. The orientational order parameter, S, is estimated by using the molecular polarizability values calculated from refractive index and denstity data as well as polarizability anisotropy values calculated as a function of temperature in the nematic phase of both of the dimers. These values are discussed with reference to the order parameter values obtained directly from the optical birefringence, Δn, data without assuming any internal field. A comparison of the order parameter values from all of these methods was carried out in the light of available literature data.
文摘The orientational order is an important concept of the materials composed of large molecules or clusters. Using high-resolution scanning tunneling microscopy, we have studied the orientational order of two kinds of typical low-dimensional C60 lattices: two-dimensional molecules array and C60(111) multi-layer film surface. Due to the change of the crystal field, their orientational orders are distinctly different from those in bulk system, and some unique phenomena appear.
基金The authors are grateful to the Province Natural Science Foundation of Zhejiang(Grant No.LQ19E050004)for financial support.The authors also graciously thank China Airlines Shenyang Liming Aeroengine Co.,Ltd.for aiding in providing the experimental Inconel 718 alloys.
文摘Due to the important role ofδphase's quantity and morphology in the mechanical and fatigue properties of Inconel 718 alloy and its components,it is necessary to renew insights into the effect of cold deformation on theδphase precipitation,especially on the morphology evolution.Therefore,the nucleation and growth behavior ofδphase in cold-rolled Inconel 718 alloy during aging were investigated.The results show that the precipitation rate and volume fraction ofδphase increase with increasing the cold rolling reduction from 10%to 50%.The volume fraction ofδphase reaches equilibrium after 5 h,remaining at 5.98%,6.52%,and 6.79%under different rolling reductions(10%,30%,and 50%),respectively.The nucleation ofδphase mainly occurs on different sites(grain boundaries,new twin boundaries and old twin boundaries)under 10%rolling reduction,whileδphase mainly nucleates on the new grain boundaries of static recrystallization due to 50%rolling reduction.And the growth ofδphase undergoes a process of alternate orientation growth from spherical(nucleation)→short rod(longitudinal orientation growth)→short rod(radial orientation growth)→dynamic equilib-rium.Under 10%rolling reduction,δphase tends to grow into the matrix,while under 50%rolling reduction,the orientation grows faster and is easily affected by the grain boundary curvature.
文摘New concepts such as intramolecular orientational order parameter and corresponding model as well as theory were proposed to describe the intramolecular orientation of mesogenic units in the liquid crystalline polymer chains. The relationship between the intramolecular orientational order parameter and the molecular geometrical parameters such as the bond angle, the bond rotational angle and the rotational potential energy of chemical bonds was deduced. A significant even-odd oscillation of the intramolecular orientational order parameter of LCPs with different length of flexible spacer was found and rationally related to even-odd zig-zag manner of transition properties The verification and application of the theory are also discussed. The isotropic transition temperature predicted by the theory is shown to be in favourable agreement with the experiments.
基金Supported by the State Commission of Science and Technology, the National Natural Science Foundation and the State Education Commission of China.
文摘Re-innervation of sensory and motor neurons on a defined area of the body wall was studied in two species of leeches, Whitmania pigra and Hirudo medicinalis, as a model of segmental animals. Following isolation and rotation of a tube of body wall, the mechanical sensory and annular erection (AE) motor neurons re-innervated the body wall, at a rate of approximately 3. 8 -8. 4 μm/h. The patterns of re-innerva-tion by pairs of neurons on each side of a ganglion were bilaterally symmetric. The repairs are synchronous for the sensory and motor neurons which are of different functions but in a same ganglion. The gap junctions are widely spread in leech between neurons and glia cells, as well as among the neurons and glia cells themselves. Therefore, it is proposed that the nervous system repair is regulated by a low-resistance pathway. In the xenotransplantation experiments, neurons recognized target tissues before the immuno-recognition and rejection.
基金National Natural Science Foundation of China(51504138,51674118,52271177)Hunan Provincial Natural Science Foundation of China(2023JJ50181)Supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2024-022)。
文摘To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.
基金supported by the Japan Society for the Promotion of Science (JSPS) through its "Funding Program for World Leading Innovative R&D on Science and Technology (FIRST Program)"
文摘Copolymers of N-pentafluorophenyl maleimide (PFPMI) with methyl methacrylate (MMA) were synthesized by a free radical initiator, such as AIBN. The refractive indexes of the copolymers remained nearly constant (1.4970 at 532 nm) regardless of the polymer composition. These copolymers also showed high thermal stability. The orientational and photoelastic birefringence of the copolymers obtained were measured. Since both of the orientational and photoelastic birefringences of PMMA are negative whereas poly(PFPMI) exhibits positive, thus we have obtained nearly zero orientational and photoelastic birefringence polymers when the ratios of MMA/PFPMI were 91.8/8.2 and 97.0/3.0 mol%, respectively. Based on the experimental data, the ratios of MMA/PFPMI for zero birefringence were determined to be 88.9/11.1 and 93.8/6.2 mol% for orientational and photoelastic birefringence, respectively. The Tgs of corresponding copolymers were estimated to be 128 and 122 ℃.
文摘In Wuhu,urban renewal has not only transformed the development process,but improved people’s lives.DURING the 14th Five-Year Plan period(2021-2025),urban renewal has served as a crucial measure to promote high-quality urban development and continuously meet people’s growing aspirations for a better life.Wuhu,in central China’s Anhui Province,has consistently enhanced its urban functions and services to build a modern,people-oriented city that is innovative,livable,beautiful,resilient,and smart.
基金supported by Key R&D Program of Shandong Province,China(No.2025CXGC010407).
文摘Electromagnetic interference(EMI)shielding materials principally attain shielding by reflecting electromagnetic waves through impedance mismatch caused by high conductivity,which inevitably leads to secondary electromagnetic wave pollution.Consequently,the development of multifunctional,low-reflection electromagnetic shielding materials remains a significant challenge.Materials that are lightweight,possess high mechanical strength,exhibit excellent electromagnetic shielding absorption,and demonstrate low reflectivity have historically been the focus of significant interest.Natural silk,lightweight and strong,is an ideal composite matrix.Regenerated silk fibroin(RSF)synthesized via a bottom-up approach and cross-linked with polyvinyl alcohol(PVA)forms an aerogel matrix with remarkable compressive strength.In accordance with the principle of integrating functional design with structural design,spherical NiFe_(2)O_(4)particles were grown on the MXene surface via electrostatic self-assembly and combined with RSF/PVA as the aerogel absorptive layer,while RSF/PVA/MXene served as the reflective layer.A vertically oriented structure of Janus aerogel was prepared through sequential directed freezing.The resulting aerogel with 0.058 g/cm^(3) reveals the high compression strength(3.52 MPa).Reasonable functional and structural design enables aerogel to effectively dissipate incident electromagnetic waves through absorption,reflection,and reabsorption processes,achieving an average SET value of 48.05±1.75 dB and reaching a minimum reflection coefficient of 0.19.Furthermore,the aerogel displays remarkable infrared stealth capabilities.This lightweight,rigid,multifunctional aerogel is poised to play a significant role in the field of next-generation electronic devices.
基金supported by the National Natural Science Foundation of China(grant nos.21127009,21221003,and 21425519)the Training Program for Excellent Young Innovators of Changsha(grant no.kq1905061)the Natural Science Foundation of Hunan Province,China(grant no.020RC3042).
文摘Single nanoparticle tracking(SPT)is a unique and powerful tool to investigate the interaction between nanoparticles and cells,which is of considerable importance for nanotechnology applications in biomedical fields and in-depth understanding of biological activities.However,previous work typically focused on translations of single nanoparticles while they undergo both translational and rotational motions.In this study,we obtained both the translational and rotational dynamics of single gold nanorods during their cellular internalization process using dual-channel polarization microscopy.In particular,the azimuth and polar angles were integrated into a polar coordinate systemto obtain three general orientation distribution patterns,found to have a close relationship with the nanoparticle cellular internalization process and time-dependent alterations.Moreover,the patterns accompanied by trajectories,translational and rotational coefficients,the azimuth and polar angles,and other parameters provided a wealth of knowledge on the nanoparticle cellular internalization dynamics with unprecedented details.We observed that the gold nanorods could initially assume a tip-first quick rotation state with partially restricted orientations,then change to a strongly confined near-vertical insertion state with slight angular fluctuations,and eventually transform into a random and fast rotation state.Our methodology opens up a new avenue for a detailed understanding of biological processes.
基金Project supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences.
文摘Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.
文摘Across four studies,we explore the impact of solitude on consumers’reliance on feelings versus reasons in decision making,along with the underlying mechanism and boundary conditions.The results indicate that solitude individuals(vs.non-solitude)would prefer feeling-based strategy in decision-making,resulting in a higher intention of choosing the affectively superior option over the cognitively superior option(Study 1).Self-focus plays the underlying mechanism in the solitude effect(Study 2).Moreover,we also examine two boundary conditions:motivation(Study 3)and temporal orientation(Study 4),which indicates that involuntary motivation and future orientation can mitigate the solitude effect on affective processing.These findings provide insights into consumers’judgments of product attributes and selection of decision-making strategies according to their situations.
基金financially supported by the National Natural Science Foundation of China(No.52071040 and 51871036)Natural Science Foundation of Shandong Province,China(No.ZR2022QE008)China Postdoctoral Science Foundation(No.2022M712984)。
文摘Although magnesium-aluminum alloys,such as AZ80 and AZ91 have promising application potential in automotive,high-speed train and aerospace fields,their age-hardening response is generally not very appreciable.In this work,the aging-hardening response of AZ80 alloy was effectively enhanced by applying cold-rolling deformation before conducting conventional aging treatment at 200°C.Compared to the directly aged sample,the yield strength of the pre-rolling and aged sample was increased by 35 MPa.Electron microscope examination confirmed that profuse{10¯11}and{10¯11}-{10¯12}twins,consisting of high density of dislocations and stacking faults,were generated by cold rolling.Blocky or ellipsoidal Mg_(17)Al_(12)precipitates formed at the twin boundaries(TBs)during subsequent aging treatment.Crystallographic analysis indicated that the precipitates at{10¯11}TBs always held an identical Potter OR with both the matrix and twin,while the precipitates at{10¯11}-{10¯12}TBs exhibited three different ORs:Burgers OR,Potter OR and P-S OR with either the matrix or the twin.Moreover,recrystallized grains were found inside{10¯11}-{10¯12}double twins after peak-aging at 200°C,implying that precipitation and recrystallization might occur concurrently along TBs at a relatively low temperature.It was speculated that the highly stored energy inside twins and the high elastic energy between the precipitates and twins were driving factors for the occurrence of recrystallization.
基金supported by the National Key R&D Program of China(Grant No.2020YFA0710604)NSFC(Grant No.42374064).
文摘Determining the orientation of in-situ stresses is crucial for various geoscience and engineering appli-cations.Conventional methods for estimating these stress orientations often depend on focal mechanism solutions(FMSs)derived from earthquake data and formation micro-imager(FMI)data from well logs.However,these techniques can be costly,depth-inaccurate,and may lack spatial coverage.To address this issue,we introduce the use of three-dimensional(3D)seismic data(active sources)as a lateral constraint to approximate the 3D stress orientation field.Recognizing that both stress and fracture patterns are closely related to seismic velocity anisotropy,we derive the orientation of azimuthal anisotropy from multi-azimuth 3D seismic data to compensate for the lack of spatial stress orientation information.We apply our proposed workflow to a case study in the Weiyuan area of the Sichuan Basin,China,a region targeted for shale gas production.By integrating diverse datasets,including 3D seismic,earthquakes,and well logs,we develop a comprehensive 3D model of in-situ stress(orientations and magnitudes).Our results demonstrate that the estimated anisotropy orientations from 3D seismic data are consistent with the direction of maximum horizontal principal stress(SHmax)obtained from FMIs.We analyzed 12 earthquakes(magnitude>3)recorded between 2016 and 2020 for their FMSs and compressional axis(P-axis)orientations.The derived SHmax direction from our 3D stress model is 110°ES(East-South),which shows excellent agreement with the FMSs(within 3.96°).This close alignment validates the reliability and precision of our integrated method for predicting 3D SHmax orientations.
基金funding support from the National Nature Science Foundation of China(Grant No.42272334)the National Key Research and Development Program of China(Grant No.2022YFE0137200)the Taishan Scholars Program(Grant No.2019RKB01083).
文摘Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation process under two different orientations of σ_(2),i.e.σ_(2) parallel to the fracture plane(Scheme 2)and σ_(2) cutting through the fracture plane(Scheme 3),under varying σ_(3) from 10 MPa to 40 MPa.The peak or fracture reactivation strength,deformation,failure mode,and post-peak mechanical behavior of intact(Scheme 1)and pre-fractured(Schemes 2 and 3)specimens were also compared.Results show that for intact specimens,the stress remains nearly constant in the residual sliding stage with no stick-slip,and the newly formed fracture surface only propagates along the σ_(2) direction when σ_(3) ranges from 10 MPa to 30 MPa,while it extends along both σ_(2) and σ_(3) directions when σ_(3) increases to 40 MPa;for the pre-fractured specimens,the fractures are usually reactivated under all the σ_(3) levels in Scheme 2,but fracture reactivation only occurs when σ_(3) is greater than 25 MPa in Scheme 3,below which new faulting traversing the original macro fracture occurs.In all the test schemes,both ε_(2) and ε_(3) experience an accumulative process of elongation,after which an abrupt change occurs at the point of the final failure;the degree of this change is dependent on the orientation of the new faulting or the slip direction of the original fracture,and it is generally more than 10 times larger in the slip direction of the original fracture than in the non-slip direction.Besides,the differential stress(peak stress)required for reactivation and the post-peak stress drop increase with increasing σ_(3).Post-peak stress drop and residual strength in Scheme 3 are generally greater than those in Scheme 2 at the same σ_(3) value.Our study clearly shows that intermediate principal stress orientation not only affects the fracture reactivation strength but also influences the slip deformation and failure modes.These new findings facilitate the mitigation of dynamic geological hazards associated with fracture and fault slip.
文摘Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically calculated.The effect of precipitate ripening on the Goss texture and magnetic property was investigated.Data indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate increased.Secondary recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}<227>oriented grains growing abnormally and a magnetic induction intensity of 1.90T.Furthermore,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture.However,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 T.At a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this study.The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties.
文摘Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We report the preparation of novel aerogel materials with a much better per-formance.Using the driving force of graphene oxide(GO)self-assembly andπ-πinteractions,carbon nanotubes(CNTs)were attached to the GO sheets,and an oriented composite carbon skeleton was constructed using“hydro-plastic foam-ing”.The introduction of CNTs significantly increased the strength of the skeleton and gave the aerogel an excellent re-versible compressibility.The innovative use of cold pressing greatly improved the thermal conductivity and flexibility of the aerogel,providing new ideas for the development of high-performance aerogels.Tests show that the obtained graphene composite aerogel has a reversible compressive strain of over 90%and can withstand 500 compression cycles along the direc-tion of pore accumulation.It can endure more than 10000 bending cycles perpendicular to the direction of composite carbon layer stacking,and its in-plane thermal conductivity reaches 64.5 W·m^(-1)·K^(-1).When filled with phase change materials,the high porosity of the carbon skeleton enables the material to have a high phase change filling rate,and its phase change enthalpy is greater than 150 J/g.Thanks to the exceptional flexibility of the carbon skeleton,the macrostructure of phase change materials can be bent as needed to adapt to thermal management scenarios and conform to device shapes.This significantly enhances practical application compatibility,providing flexible support for temperature control and thermal management across diverse device forms.
基金supports by the Grant-in-Aid of Scientific Research of Challenging Research(Exploratory)(JP23K17738)to TS from MEXT of Japanthe 41st grant of research from Nippon Sheet Glass Foundation for Materials Science and Engineering to TS.
文摘A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing.The necessity for its sophistication arises from the availability of multi-dimensional sensing signals.Simultaneous monitoring of the redox current and color change synchronized with the oxidation state change significantly enhances sen-sitivity and selectivity.This study aimed to elucidate the modification of an indium tin oxide(ITO)electrode with a viologen monolayer with an ordered orientation.Novel methods were developed to immobilize a viologen molecule bearing a car-boxyl group to form assembled monolayers through a condensation reaction using 1-ethyl-3-(3-dimethylaminopropyl)-car-bodiimide with N-hydroxy-succinimide(EDC/NHS).In the two methods of immobilization,one utilizes a two-step process to firstly form an aromatic siloxane base layer and subsequently attach the viologen derivative through an amide linkage by post-amidation.The other employs a direct ester linkage between the hydroxyl groups of the ITO surface and the car-boxyl group of the viologen derivative.The latter method was also applied to immobilize a ferrocenyl group at a very short distance from the ITO surface.Potential-modulated UV-visible transmission absorption spectral measurement techniques with oblique incidence of plane-polarized light were employed to determine the orientation of the longitudinal axis of the reduced form of the viologen.The frequency dependence data of the potential-modulated transmission absorption signals were utilized to analyze the electron transfer kinetics.The performance of the two viologen-modified electrodes was com-pared to that of an ITO modified by post-amidation to the most commonly used base layer prepared with 3-aminopropyl triethoxysilane.
