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Understanding long-term successional changes in old-growth forests affected by natural disturbance is particularly important in the context of contemporary climate changes. Quantitative descriptions of natural disturbance regimes require direct observations of tree populations over multiple decades, yet such studies are rare in the late-successional forest, particularly in the subalpine coniferous forest. Thus, we use four decades (1981–2022) monitoring of permanent plot in old-growth forest to reveal how tree species composition and structure changed. Results indicated that there was a significant decrease in the total density and basal area and standing volume, which was caused by the gradual decline of large Picea jezoensis var. komarovii. Meanwhile, Betula ermanii dominance increased over time. Analysis of spatial distribution patterns suggested that gap formation facilitated Betula ermanii adults and Picea jezoensis var. komarovii offspring naturally regenerate to coexist. Future canopy composition would mainly depend on a balance between Betula ermanii 's saplings probability of entering the canopy layer and the co-dominants’ survival there. Taken together, we concluded that the late-successional spruce-fir forest is dynamic and does not show quasi-equilibrial properties at a small scale, whereas, climax vegetation is a complex shifting mosaic that is comprised of patches in different successional stages. Natural disturbance is the main reason for maintaining the climax vegetation distribution pattern. In the absence of large catastrophic disturbances, we expect the mosaic pattern may persist for long under a certain climate regime.

This study aimed to investigate the proportion of surface activation markers on natural killer (NK) cells in children with infectious mononucleosis (IM) and to explore its clinical relevance. A total of 17 children hospitalized with IM were included in this study as the experimental group. Meanwhile, healthy children matched for age and gender served as controls. First, we isolated peripheral blood mononuclear cells from children with IM and healthy children. Then, NK cell surface markers were stained with monoclonal antibodies and analyzed by flow cytometry. The results showed that the percentage of CD3- CD16+ NK cells was higher in peripheral blood lymphocytes from children with IM than that from healthy children (t = -4.52, P

For the application of X80 pipelines in Northeast China, it is important to establish the correct cathodic protection (CP) potential. To achieve this, potentiodynamic polarization; electrochemical impedance spectroscopy (EIS); a slow strain rate test (SSRT); and a scanning electron microscopy (SEM) fracture morphology analysis were carried out for an X80 steel gas pipeline at several temperatures in Heilongjiang Province, China. The results show that the hydrogen evolution potential of X80 steel in soil at different temperatures was about −900 mV (vs. CSE). The generated hydrogen atoms can be adsorbed on the surface of the pipelines to reduce the surface energy, or they can be diffused into the substrate and accumulate to the critical concentration, inducing the decohesion between different structures and generating additional plastic deformation through dislocation motion. With the peak impedance potential as the minimum potential and the hydrogen embrittlement potential as the maximum potential, the CP potential of X80 steel in the soil at 30 °C, 45 °C, and 60 °C ranged from −900 mV to −1100 mV (vs. CSE), temperatures at which the X80 steel does not corrode or cause hydrogen embrittlement.

Strong thermal–mechanical coupling and rapid tool failure easily occur in the milling process of hardened steel with solid end mills. This work investigates the effectiveness of minimum quantity lubrication (MQL) during high-speed milling of hardened mold steel. Three kinds of spraying modes were designed in the experiment. They are namely the spraying ways to the flank face (MQL-F), to the rake face (MQL-R) and to the rake and flank faces (MQL-FR). The cutting forces, tool wear, and chips when using the MQL modes and compressed air cooling mode (CAIR-F) were compared, and the wear mechanism and lubrication mechanism were further analyzed. The results showed that the tool wear values and milling forces of several MQL modes were significantly lower than those with CAIR-F. The milling force and tool wear values were successively reduced using MQL-R, MQL-F, and MQL-FR, with better lubrication of the rake face resulting in a smaller curvature radius for the chip. Abrasion wear, adhesion/attrition wear, and flaking/chipping were the main wear mechanisms. The MQL-FR method was the optimal method of the MQL modes. It could effectively reduce the cutting contact stress and unit cutting energy, and obviously reduced wear phenomena such as adhesion and chipping.

The machining efficiency of hardened steel molds can be significantly improved through high-speed deep milling. However, under these circumstances, the temperature and milling force increase greatly, and the end mills are subjected to rapid wear. A feasibility study of the oil-on-water (OoW) method in the high-speed end milling of P20 hardened steel was conducted. The experimental results show that the tool life of OoW is significantly longer compared with that of dry cutting and compressed air cooling. Moreover, the OoW method promotes tool life under low- and high-speed milling conditions. Thermal wear phenomena (e.g., adhesion) are evidently suppressed, and the development of the milling force and tool wear is considerably slowed down in OoW processing. The main reason for the excellent cooling and lubrication performance of the OoW method is that a two-layer film (oil film + water film) is formed when the OoW droplets collide with the cutting interface. The evaporation of the water film removes much heat and prevents the high-temperature failure of the oil film. Moreover, the single use of oil mist and water mist leads only to a single-layer film, resulting in an evidently shorter tool life than that of the OoW method. In the OoW cutting process, the chipping belt of the flank face is discontinuous, and the wear of the adhesion/attrition is less severe compared with those of the other processing modes. In addition, the tool wear and chipping belt occur with a certain amount of material peeling, and the thermal fatigue and mechanical behavior of the tool substrate in a certain temperature range are the main reasons for the discontinuity of the chipping belt in the OoW process.

This study aimed to investigate the proportion of surface activation markers on natural killer (NK) cells in children with infectious mononucleosis (IM) and to explore its clinical relevance. A total of 17 children hospitalized with IM were included in this study as the experimental group. Meanwhile, healthy children matched for age and gender served as controls. First, we isolated peripheral blood mononuclear cells from children with IM and healthy children. Then, NK cell surface markers were stained with monoclonal antibodies and analyzed by flow cytometry. The results showed that the percentage of CD3

According to ISO 13357, the filterability of different turbine base oils is measured. It is found that the dry filterability of eight kinds of base oil is better than 100, but there are great diffe...

Hollow spherical corundum granules were introduced into a vitrified bond diamond grinding wheel as pore former. The influences of content and particle size of the hollow spherical corundum granules on porosity, flexural strength, and hardness of the vitrified bond diamond wheel samples were systematically investigated. The grinding performance of the designed vitrified bond diamond cup wheel on sapphire and 6H-silicon carbide (SiC) substrates was examined, and morphological properties of the ground surface were evaluated. Results showed that higher content and smaller size of hollow spherical corundum granules could lead to the increase of the porosity and the decrease of flexural strength and hardness. Sapphire and 6H-SiC substrates could be effectively ground by the vitrified bond diamond cup wheel containing 8% hollow spherical corundum granules. During the grinding, although a brittle mode dominated the material removal of two substrates, more ductile removals and lower surface roughness could be identified from 6H-SiC substrate than from sapphire.

The progressive cutting based on auxiliary paths is an effective machining method for the material accumulating region inside the mould pocket. But the method is commonly based on the radial depth of cut as the control parameter, further more there is no more appropriate adjustment and control approach. The end-users often fail to set the parameter correctly, which leads to excessive tool load in the process of actual machining. In order to make more reasonable control of the machining load and tool-path, an engagement angle modeling method for multiple-circle continuous machining is presented. The distribution mode of multiple circles, dynamic changing process of engagement angle, extreme and average value of engagement angle are carefully considered. Based on the engagement angle model, numerous application techniques for mould pocket machining are presented, involving the calculation of the milling force in multiple-circle continuous machining, and rough and finish machining path planning and load control for the material accumulating region inside the pocket, and other aspects. Simulation and actual machining experiments show that the engagement angle modeling method for multiple-circle continuous machining is correct and reliable, and the related numerous application techniques for pocket machining are feasible and effective. The proposed research contributes to the analysis and control tool load effectively and tool-path planning reasonably for the material accumulating region inside the mould pocket.

Brazed monolayer diamond grinding wheels have advantages of a high abrasive bonding strength, high protrusion, and a large chip disposal space. However, it is difficult to prepare ordered and fine-grained brazed diamond grinding wheels. This study presents a new method for grain-arranged, brazed diamond grinding wheels with microtextures with similar performance to ordered and fine-grained brazed diamond grinding wheels. First, coarse diamond grains (18/20 mesh) were orderly brazed to fabricate the end grinding wheels. Next, a series of microtextures were ablated on the diamond grains using a pulsed laser, and two types of textured end grinding wheels—TG-G (ablated microgrooves only) and TG-GH (ablated microgrooves and microholes)—were prepared. Then, an experiment involving the grinding of alumina ceramics was performed, and the grinding characteristics and grinding mechanism were analyzed. The results indicated that compared with untextured diamond end grinding wheels (TG), the textured diamond grinding wheels (TG-G and TG-GH) significantly reduced the grinding force and the roughness of the machined surface. The local stress concentration at the microtextures promoted the formation of microcracks in the diamond grains of TG-G and TG-GH, and the self-sharpness of the grinding wheel was significantly improved. The brittle fracture mode of ceramic materials in grinding included intergranular fracture and transgranular fracture. Ironing pressure action was a key material-removal mechanism. It had an important influence on the cutting force and plasticity characteristics of the TG machined surface. For the surfaces processed by TG-G and TG-GH, the effect of ironing was weakened, while shearing played a more important role. The TG-GH grinding wheel ablated with microgrooves and microholes was superior to the TG-G grinding wheel ablated with only microgrooves, with regard to the grinding force, roughness, and self-sharpening.

The toolpath for a sharp corner is important in pocket machining during high-speed machining with numerical control. When milling a sharp corner, a longer tool engagement length generates larger engagement angle and milling force, which reduces the machining precision. To reduce the milling force at a sharp corner and clear up uncut materials, the toolpath at corners must be optimized. In this paper, a new method of generating the toolpath with circular cycle transition at a sharp corner is put forward to provide a new numerically controlled toolpath pattern for pocket milling. On the basis of a common contour-parallel toolpath, minimum radius arcs and circular cycles are added in sequence at a sharp corner. When the cutter comes to the sharp corner, the corner material is removed step by step with a sequence of circular cycles. The validity of the proposed method is confirmed through simulation and tests. The proposed toolpath method is realized by employing the Institute of Manufacturing Technology (IMT) computer-aided manufacturing (CAM) system. The toolpaths at sharp corners generated through commercial software and IMT-CAM software are tested by comparing the corresponding milling forces. It is illustrated in the results that the proposed method reduces the milling force effectively and is of great significance when it is applied in high-speed machining.

The use of braze coating is proposed to obtain a layer of filler alloy on different types of diamond grits for improving diamond grit retention in resin-bonded diamond wheels. The effects of brazing on surface morphology and mechanical properties of diamond grits were evaluated. Resin-bonded diamond wheels with braze-coated diamond grits were prepared, and the grinding performances of cemented carbide wheels with different diamond grits were tested. Brazing could successfully cover most of the diamond grits with a layer of filler alloy. Pores and bumps of several microns in size were observed as well as the formation of titanium carbide (TiC) between the coating and diamond grit. Toughness indexes (TIs) of coated single-crystal diamond grits (RVD) decreased only slightly, but significantly increased for coated polycrystal diamond grits (PDGF1). The wheel containing coated PDGF1 diamond grits exhibited the lowest grinding forces and highest grinding ratio among the four wheels evaluated, whereas the wheel with coated RVD diamond grits produced the highest grinding force and a relatively low grinding ratio.

The auto-fluorescence of breast cancer cells, early malignant cells of cystic mazoplisis and simple mazoplisis cells is researched with a confocal laser scanning microscope. It is found that there is a correlation between the cell malignant degree and its auto-fluorescence intensity: the auto-fluorescence in the plasma of breast cancer cells is most intensive, in the plasma of early malignant cells of cystic mazoplisis is less and there is no auto-fluorescence observed in the plasma of simple mazoplisis cells. This auto-fluorescence characteristic may provide an important basis for early diagnosis of tumor.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new way of precise measurement of moving object is described in this paper. Using Laser-Fourier Transformation-CCD System and computer (for real-time processing) We realized the dynamic measurement of tungsten filament etc.under the real-time si- tuation, and measuring results have been achieved of linear-diameter range 1O-2OOm, the precision 0.5% and the velocity O-l5OmImin. Though the static precision measurement of fine wire diameter has been well re- solved in scientific research and industrial applications, the precision measuremeit of a moving fine wire is still a rather difficult problem. There are two kinds of dynamic measurement of fine wire now: One is the light spot scanning method, with a parallel beam scanning across a wire and a phototube receiving the light singnal op- posite, the diameter of wire from 5Opm to several millimeters can be measured; the other is to measure the shadow of fine wire with a CCD ( charge coupled device ), the measuring range is about 0.5-30mm. These two methods can measure fine wire dy- namically, but their accuracies are 1,ow and measuring ranges are limited. They are not suited to measure thinner wires for too big error. It is often necessary to measure dynamically wires thinner than 50 Itm with high precision in industry practice, such as tungsten filament using in bulb factories, which diameters are from 8 to 40 im. The above methods aren't suitable. Now in some factories the weight method is used to measure fine wire diameters but it can only obtain the mean value but not the real value of diameters, so it affects seriously the quality of bulbs. The new method of dynamic precision measurement we studied is to measure the power spectrum of a fine wire with a CCD, and process data with a micro-computer at real time. Satisfacory results have been achieved.