漫话古代书信的别称

我国古代诗文中,书信有诸多别称,若不明其意,读古典诗文,会引起困惑。书:在古代,书指信函,信指送信使者。《左传·昭公六年》:“叔向使诒子产书”,“书”即是信。

Analysis of Test Methods for Parts to Follow Relative Requirements

Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products’ quality, market competitiveness and manufacturers’ maximum economical benefits from these products. One of the latest subjects of study in the area of precision measurement is the testing of parts to follow the relative requirements, viz. design requirements for the size tolerance of size features and related geometrical tolerances of the central feature, including the envelope requirement, maximum material requirement and least material requirement. The article analyzes test methods for parts to follow the envelope requirement or maximum material requirement, as well as further requirements of geometrical tolerances for its central feature. The method is effective in improving product quality and rejecting unqualified parts.

Lysozyme refolding at high concentration by dilution and size—exclusion chromatography

This study of renaturation by dilution and size exclusion chromatogra phy (SEC) addition of urea to improve yield as well as the initial and final pro tein concentrations showed that although urea decreased the rate of lysozyme ref o lding, it could suppress protein aggregation to sustain the pathway of correct r efolding at high protein concentration; and that there existed an optimum urea c oncentration in renaturation buffer. Under the above conditions, lysozyme was su ccessfully refolded from initial concentration of up to 40 mg/mL by dilution and 100 mg/mL by SEC, with the yield of the former being more than 40% and that of the latter being 34.8%. Especially, under the condition of 30 min interval time, i.e. τ>2(t_R2 -t_R1 ), the efficiency was increased by 25% and the renaturation buffe r could be recycled for SEC refolding in continuous operation of downstream proc ess.

Effect of Cr content on microstructure and properties of aged Cu−Cr−P alloys

The role of Cr in affecting the precipitates and the properties of aged Cu−Cr−P alloys was investigated and discussed.The results show that there are mainly three sizes of Cr phase in aged Cu−Cr−P alloys,among them,the nano-sized Cr phase plays an important role in the strength of Cu−Cr−P alloys.The strengthening effect of Cr phase(less than 5 nm)with FCC structure completely coherent with the matrix is calculated to be about 200 MPa on the basis of dislocation cut-through mechanism.The strengthening effect of Cr phase(10−20 nm)with BCC structure incoherent with the matrix is calculated to be about 100 MPa on the basis of the Orowan dislocation bypass mechanism.The increase of Cr content changes the number and size of nano-sized Cr phase,which causes the mechanical properties of the Cu−Cr−P alloys to increase first and then decrease.The tensile strength of Cu−0.36Cr−0.01P alloy is 572 MPa and its electrical conductivity is 80%IACS after solid solution treatment at 980°C for 2 h followed by 95%cold rolling and then aging treatment at 450°C for 1 h.

Size effect on compressive strength of reactive powder concrete

In this paper the coefficient and law of the size effect of RPC were studied through experiments and theoretical analysis. The size-effect coefficients for the compressive strength of RPC are deduced through experiments.They indicate that RPC without fiber behaves quite the same as normal or high strength concrete.The size effect on compressive strength is more prominent in RPC containing fiber.Bazant's size effect formula of compressive strength applies to RPC.A formula is given to predict the compressive strength of cubic RPC specimens 100 mm on a side where the fiber dosage ranges from 0-2%.

The Energy-orthogonal Tetrahedral Finite Element for Fourth Order Elliptic Equations

In this paper,the 16-parameter nonconforming tetrahedral element which has an energy-orthogonal shape function space is presented for the discretization of fourth order elliptic partial differential operators in three spatial dimensions.The newly constructed element is proved to be convergent for a model biharmonic equation.

Enzymatic Hydrolysis of Cellulose with Different Crystallinities Studied by Means of SEC-MALLS

The reactions of exo-cellulase （cellobiohydrolase, CBH） and endo-cellulase （endoglucanase, EG） were investigated by analyzing the insoluble residues of microcrystalline cellulose （MCC） and filter paper cellulose （FPC） during enzymatic hydrolysis. Molecular parameters including molecular weight and its distribution, degree of polymerization, and radii of gyration were measured by size exclusion chromatography coupled with multi-angle laser light scattering. No significant change in MCC chains was found during the whole reaction period, indicating that CBH digestion follows a layer-by-layer solubilization manner. This reaction mode might be the major reason for slow enzymatic hydrolysis of cellulose. On the other hand, the degree of polymerization of FPC chains decreases rapidly in the initial reaction, indicating that EG digestion follows a random scission manner, which may create new ends for CBH easily. The slopes of the conformation plots for MCC and FPC increase gradually, indicating stronger chain stiffness of cellulose during hvdrolvsis

Rutting influencing factors and prediction model for asphalt pavements based on the factor analysis method

To clarify the importance of various influencing factors on asphalt pavement rutting deformation and determine a screening method of model indicators,the data of the RIOHTrack full-scale track were examined using the factor analysis method(FAM).Taking the standard test pavement structure of RIOHTrack as an example,four rutting influencing factors from different aspects were determined through statistical analysis.Furthermore,the common influencing factors among the rutting influencing factors were studied based on FAM.Results show that the common factor can well characterize accumulative ESALs,center-point deflection,and temperature,besides humidity,which indicates that these three influencing factors can have an important impact on rutting.Moreover,an empirical rutting prediction model was established based on the selected influencing factors,which proved to exhibit high prediction accuracy.These analysis results demonstrate that the FAM is an effective screening method for rutting prediction model indicators,which provides a reference for the selection of independent model indicators in other rutting prediction model research when used in other areas and is of great significance for the prediction and control of rutting distress.

Intimate Partner Violence in Papua New Guinea

The aim of the study was to determine the prevalence, associated risk factors, consequences and preventive measures oflPV （intimate partner violence） within the selected population in Goroka, Papua New Guinea. Questions derived from the prevalidated scales were used to measure the IPV. Questionnaires were distributed to both men and women aged from 18 to 60. The participants were staff and students of University of Goroka, staff of the Goroka Secondary school and North Goroka Primary school, Teachers in-charges of the elementary schools in the Eastern Highlands Province and the villagers from Asaroufa and Kotuni villages. Of the 95 respondents, 78.95% were victims of IPV. Among the victims 37.33% were males and 62.67% females. The physical, sexual and psychological abuses were experienced by both men and women. The significant risk factors found to be associated with violence were young age, low education, low socioeconomic status, marital conflicts, history of abuse during childhood, and male patriarchal values. The interpersonal relationship tends to be an important factor for prevailing violence free environment within the intimate partners. Intimate partner violence is prevalent in PNG. The strongest independent predictors were the excessive drinking of alcohol and marital conflict. Preventive measures such as compulsory and free technical education for all children less than 14 years old and life skills training and violence awareness campaign for both men and women must be provided to reduce the intimate partner violence.

Finite Size Effect in Path Integral Monte Carlo Simulations of ~4He Systems

Path integral Monte Carlo （PIMC） simulations are a powerful computational method to study interacting quantum systems at finite temperatures. In this work, PIMC has been applied to study the finite size effect of the simulated systems of ^4He. We determine the energy as a function of temperature at saturated-vapor-pressure （SVP） conditions in the temperature range of T ∈ [1.0 K,4.0 K], and the equation of state （EOS） in the grmmd state For systems consisted of 32, 64 and 128 ^4He atoms, respectively, We find that the energy at SVP is influenced significantly by the size of the simulated system in the temperature range of T ∈ [2.1 K, 3.0 K] and the larger the system is, the better results are obtained in comparison with the experimental values; while the EOS appeared to be unrelated to it.

Both the 5th and 6th Editions of TNM Staging System Fail to Independently Predict Long-term Prognosis after Radical Hepatectomy in Hepatocellular Carcinoma Sized > or = 5cm

Objective To validate the predictive power of the 5th and 6th editions of TNM staging system(TNM-5,TNM-6) in a Chinese patient cohort with hepatocellular carcinoma(HCC) sized > or = 5 cm after radical hepatectomy.Methods Consecutive 121 patients with HCC sized > or = 5 cm undergoing radical hepatectomy between January 1995 and December 2002 were included.The impact of clinicopathological variables on prognosis was determined by univariate and multivariate analyses,after excluding 2 perioperative deaths.Results In univariate analysis,TNM-5 stage did not show prognostic significance for overall or disease-free survival,as opposed to TNM-6 stage,Edmondson-Steiner grade,portal vein tumor thrombosis(PVTT),vascular invasion,satellite nodule,Child-Pugh grade,and hepatitis B surface antigen(HBsAg) positivity.When these significant variables were entered in multivariate analysis,Edmondson-Steiner grade was the sole independent prognosticator for both overall and disease-free survival,whereas Child-Pugh grade independently influenced disease-free survival.However,TNM-6 stage lost its predictive potential in multivariate analysis.Conclusions Neither TNM-5 nor TNM-6 staging system is revealed to be independently prognostic in patients with HCC sized > or = 5 cm after radical hepatectomy.Therefore,TNM-6 calls for more support in many subsets of HCC patients.

Crystallization characteristics of Ni-W-P composite coatings reinforced by CeO_2 and SiO_2 nano-particles

Ni-W-P composite coatings reinforced by Ce O2 and Si O2 nano-particles on the surface of common carbon steels, were prepared by double pulse electrodeposition. The crystallization course was characterized by phase structures, crystallinity, grain sizes and microstructures. The results indicate that as-deposited composite coating is amorphous. Whereas it turns into the crystalline structure with 98.25% crystallinity, and Ni3 P, Ni2 P and Ni5P2 alloy phases precipitate from structures at 400 °C. Thereafter, Ni2 P and Ni5P2 metastable alloy phases turn into Ni3 P stable alloy phase at 500 °C. The crystallization course of the composite coating has finished when being heat-treated at 700 °C. The average sizes of Ni grains increase with the rise of heat treatment temperature from400 °C to 700 °C. Ce O2 and Si O2 nano-particles deposited into Ni-W-P alloys can delay the crystallization course and habit the growth of alloy phases.

High resolution records of flood deposition in the mud area off the Changjiang River mouth during the past century

This paper presents a paleoflood study to determine the flood frequency of the Changjiang River, based on core cj0702, taken from the Changjiang River subaqueous delta. We identified flood deposits by means of high-resolution grain-size variation, sensitive population, geochemical indexes and magnetic susceptibility. The core covers a time span of 120 years by 21~pb dating and was sampled at 1-2 cm intervals. Grain size, geochemical elements, and physical parameters were analyzed. The results indicate that the sediment of the core is mainly composed of silt and clay, as well as groups of interbedded silt, clay silt, and clay. Vertically, the grain size pattern was controlled by seasonal variations in water discharge and by the sediment input in winter from the abandoned Huanghe River delta. River flooding caused extreme values in all our measured parameters. We identified more than 20 flood events that occurred since 1887 using the physical parameter analysis method. The environmentally sensitive component of sediment grain size （14.32-96.39 gm） contribution〉30%, Zr/Rb ratio〉l.5, and magnetic susceptibility〉16 were selected as the criteria for flood identification generally. We also found that floods that had taken place in the upstream, midstream, or downstream parts of the river were clearly identified by these indexes while the large-scale floods that covered the whole drainage area did not leave clear indications in the sediment record. This study for identification of flood events is of great significance for understanding hyperpycnal current sedimentation as well as for forecasting of floods.

Watershed segmentation based on hierarchical multi-scale modification of morphological gradient

Watershed segmentation is sensitive to noises and irregular details within the image,which frequently leads to a serious over-segmentation Linear filtering before watershed segmentation can reduce over-segmentation to some extent,however,it often causes the position offset of object contours.For the purpose of reducing over-segmentation to preserve the location of object contours,the watershed segmentation based on the hierarchical multi-scale modification of morphological gradient is proposed.Firstly,multi-scale morphological filtering was employed to smooth the original image.Then,the gradient image was divided into multi-levels by the volume of three-dimension topographic relief,where the lower gradient layers were further modifiedby morphological closing with larger-sized structuring-elements,and the higher layers with the smaller one.In this way,most local minimums caused by irregular details and noises can be removed,while region contour positions corresponding to the target area were largely preserved.Finally,morphological watershed algorithm was employed to implement segmentation on the modified gradient image.The experimental results show that the proposed method can greatly reduce the over-segmentation of the watershed and avoid the position offset of the object contours.

Potential aspect of rice husk biomass in Australia for nanocrystalline cellulose production

Nanocrystalline cellulose(NCC) was produced from rice husk biomass(Oryza sativa) by a chemical extraction process to explore the potential aspect of agro-waste biomass in Australia. In this work, the delignified rice husk pulp(D-RHP) was produced by alkaline delignification of raw rice husk biomass(R-RHB) using 4 mol·L^(-1) alkali solutions(Na OH) in a jacketed glass reactor under specific experimental conditions. D-RHP was bleached using 15% sodium hypochlorite, and the bleached rice husk pulp was coded as B-RHP. Finally,raw suspension of NCC was produced by the acid hydrolysis of B-RHP using 4 mol·L^(-1) sulphuric acid. The raw suspension of NCC was neutralized by a buffer solution and analyzed by TAPPI, FT-IR, XRD, SEM, AFM, and TEM. FT-IR spectra of NCC are different to R-RHB but similar with B-RHP and D-RHP. From XRD results, the crystallinity of NCC was found to be approximately 65%. In AFM analysis particle thicknesses have been confirmed to be in the range of(25 ± 15.14) nm or(27 ± 15.14) nm which is almost the same. From TEM analysis particle dimensions have been confirmed to be in the range of(50 ± 29.38) nm width and(550 ± 302.75) nm length with the aspect ratio ~ 11:1(length/diameter) at a 500 nm scale bar. On the other hand, at a 200 nm scale bar the particle dimensions have been confirmed to be in the range of(35 ± 17) nm width and(275 ± 151.38)nm length with the aspect ratio ~ 8:1. The aspect ratio of individual crystalline domain was determined in TEM analysis which is 10:1(100/10). Therefore the aspect ratios and dimensions of nanoparticles in NCC suspension are almost the same and in nano-meter scale, as confirmed from both AFM and TEM results. The yield of NCC from B-RHP was found to be approximately 95%, and the recovery of cellulose from R-RHB is about 90%.

Effects of RE and Sr additions on dendrite growth and phase precipitation in AZ91D magnesium alloy

To develop AZ91D alloys with fine microstructure, effects of the addition of rare earth (RE), Sr and RE + Sr on the dendrite growth and phase precipitation in AZ91D magnesium alloy were studied, respectively. The results show that the microstructure is refined and the morphology of β-Mg17A112 phase is modified with RE or Sr addition, especially with the RE+Sr composite addition which can reduce the average grain size of AZ91D alloy obviously to 141 μm. The needle-like or block-like new phases adhering to β-Mg17A112 phase form at interdendrites during solidification. The enrichment of RE or/and Sr elements in front of the solidification interface, especially at the tips of α-Mg dendrite, which restricts the growth of α-Mg dendrite, changes the preferential growth of α-Mg and finally results in the grain refinement and the blunting of α-Mg dendrite.

Microstructures and mechanical properties of Mg-2%Zn-0.4%RE alloys

The solidification microstructures and hardness of Mg-2%Zn (mass fraction) based alloys with addition of 0.4%Ce, 0.4%Gd, 0.4%Y or 0.4%Nd (mass fraction) were investigated, and the effects of the rare earth elements on the microstructures and mechanical properties of these alloys extruded at 310℃ were also compared. The results indicate that the trace rare earth Ce, Gd, Y or Nd in the Mg-2%Zn alloy has obviously different grain refinement effects on its solidification microstructures, and the as-cast and hot-extruded alloy with 0.4%Ce has the smallest average grain size and the highest strength. However, the extruded alloys containing 0.4%Nd or 0.4%Y with the elongation of 26.6% and 30%, respectively, show higher plasticity in spite of lower strength as compared with the alloy containing 0.4%Ce.

Reciprocal Effects of Plant-Soil Relationships at Two Spatial Scales in a Semiarid Land of Central Mexico

We studied the influence of soil heterogeneity on plant community structure in a semiarid region of Central Mexico using Bray-Curtis Ordination. The results showed that some edaphic factors, such as soil depth, organic matter, and potassium and calcium content, explained 80% of the total variation in structure of the studied communities. We found that soil resources were heterogeneously distributed in the study area, indicating that the edaphic variables considered in this study explain the existing plant community variability, moreover the presence of some shrubs as Krameria cytisoides influences the soil properties, suggesting that there is a reciprocal effect between plant and soil.

基于感知模式纹理的人脸识别

稀疏表示分类法和局部二值模式是目前广泛运用的人脸表示方法.虽然稀疏表示分类法通过重构算法能很好的稀疏表示人脸,但在人脸的局部特征表示上不够理想.局部二值模式是基于局部纹理特征表示人脸,其提取的局部纹理简单、不连续、不光滑,造成纹理损失严重.提出局部纹理特征的感知模式纹理的概念,克服了稀疏表示分类法在局部特征表现不佳的缺点,同时又比局部二值模式纹理光滑、鲁棒.利用感知模式纹理特征在Yale和ORL数据库取得了较好的识别效果.

Quantum confinement effect of two-dimensional all-inorganic halide perovskites

Quantum confinement effect（QCE）, an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimensional materials from their bulk counterparts and can be exploited to enhance the device performance in various optoelectronic applications. Here, taking Cs Pb Br3 as an example, we reported QCE in all-inorganic halide perovskite in two-dimensional（2D） nanoplates. Blue shifts in optical absorption and photoluminescence spectra were found to be stronger in thinner nanoplates than that in thicker nanoplates, whose thickness lowered below -7 nm. The exciton binding energy results showed similar trend as that obtained for the optical absorption and photoluminescence. Meanwile, the function of integrated intensity and full width at half maximum and temperature also showed similar results, further supporting our conclusions. The results displayed the QCE in all-inorganic halide perovskite nanoplates and helped to design the all-inorganic halide perovskites with desired optical properties.