PTFE基复合材料的土壤粘附与磨料磨损的研究

研究了Al₂O₃颗粒填充PTFE和PTFE+50％(wt)PPS基复合材料表面上水的润湿及土壤粘附和磨料磨损特性。加入适当含量和一定尺寸的Al₂O₃粒子可提高水的前进接触角θ_a并使减粘性能保持在较高水平。PTFE(+PPS)—Al₂O₃复合材料表面在憎水性和非光滑性方面与某些土壤动物体表有相似特性。适量Al₂O₃粒子的弥散可明显提高复合材料的耐磨料磨损性能,且PPS可进一步改进复合材料的耐磨性。     

金属材料的功能表面与水的润湿性

本文对研制的减粘功能表面与水的润湿性进行了探讨。结果表明,表面复合材料和表面涂层材料与水的接触角较常用的金属材料显著提高;各种材料的接触角与粗糙度的关系并不完全符合cosθ_γ=γcosθ的规律,当粗糙度提高到一定程度,将使表观接触角增大,其机制与粗糙表面润湿模型和表达式相吻合。     

土壤中水合氧化物型表面的化学区分——Ⅱ.电荷零点

本文研究了氧化物对红壤、高岭土和合成无定形铝硅酸盐的电荷零点的影响,并讨论了土壤中水合氧化物型表面的区分。结果表明,水合氧化物型表面可进一步区分为电荷性质完全不同的两类亚表面。在所研究的土壤和粘土样本中,有高ZPC的氧化铁(Fe-OH)和氧化铝(Al-OH)表面,是带可变正电荷的亚表面,使样本的ZPC趋于上升;而有低ZPC的氧化硅(Si-OH)表面,是带可变负电荷的亚表面,使样本的ZPC趋于下降。合成无定形铝硅酸盐的电荷零点与样本的Al₂O₃/Si₂,摩尔比呈显著的正相关。     

江西九江地区第四纪红粘土上的“黄帽子”

A thin layer of yellow-brown-colored earth was generally found on Quaternary red clay in Jiujiang, Jiangxi Province. A typical profile was established. Both particle size distribution and REE (rare earth elements) characteristics of the yellow-brown-colored earth of the profile fully suggested its aeolian origin and close similarity to Nanjing Xiashu loess. The study also implied aeolian origin of the underlying Quaternary red clay. Compared with the red clay, the yellow-brown-colored earth was less weathered because of its lower content of free iron and higher mole ratios of SiO₂/Al₂O₃ and SiO₂/(Fe₂O₃+Al₂O₃) as well as its less developed chemical microtextures of quartz grains. In order to study the ages of the two deposits comparatively, the thermoluminescent dating method was used. As a result, the bottom of the yellow-brown-colored earth was dated to 60±5 ka B. P. and the upper part of the red clay 388±54 ka B. P. It was suggested that the yellow-brown-colored earth was formed in the Late Pleistocene and was probably the aeolian deposit of the Last Glacial, which corresponded with the Malan loess in the Loess Plateau of the northwestern part of China; while the underlying red clay was formed in the Middle Pleistocene. A "yellow cap" on Quaternary red clay in Jiujiang implied a great climatic and environmental variation in the beginning of the Late Pleistocene in the southern part of China, especially in the middle and lower reaches of the Yangtze River. The event not only halted the rubification, once dominating the region, but also produced a widespread covering of aeolian deposit, as only occurred in the cold and dry environment.     

不同气体成分贮藏对大久保桃果实品质的影响

该文研究了大久保桃在不同气体成分下贮藏60 d以及出库后在20℃下货架期3 d后果实硬度、褐变指数、可溶性固形物含量、pH值、膜透性、出汁率和感官品质的变化。结果表明,1%的O₂对桃果实产生伤害,表现为表面色泽非正常变化、桃固有风味丧失并产生严重异味;(5～10)%O₂、(5～10)%CO₂气体成分能够在60 d的贮藏期内保持桃果实的品质,尤其是10%O₂＋10%CO₂处理较好地保持了果实的风味、质地和色泽,出库后果肉不褐变。与冷藏对照相比,气调贮藏能有效地延缓果实软化,抑制pH值和出汁率的升高,但对可溶性固形物的影响不大;在相同O₂浓度下,随CO₂浓度升高(<10%),果实在货架期期间的软化程度、褐变指数下降幅度、pH值上升程度和膜透性增加幅度均增大,表明果实能够进行正常后熟。本研究推荐的大久保桃果实气调贮藏的适宜气体指标是10%O₂＋10%CO₂。     

CrCl3预处理和表面活性剂对杨木酶解效率的影响

为了探究预处理和表面活性剂对纤维素酶水解效率的影响,该研究以杨木为研究对象,探究了温度对CrCl₃预处理的影响,同时从表面活性剂种类、用量和酶添加量3个方面分析表面活性剂对CrCl₃预处理后样品酶解的促进作用。结果表明：CrCl₃预处理对杨木组分分离有良好的促进效果,经160 ℃预处理后葡萄糖得率达到65.9%。通过结构表征发现预处理后杨木结构完整度降低,提高了纤维素的可接触面,进而提高了酶解效率。在酶解段加入木质素磺酸钙可显著缩短酶解时间,提高酶解效率,同时有效降低纤维素酶用量,最终酶解72h后葡萄糖得率达85.5%,当酶用量为该研究为提升木质纤维原料预处理效率和降低酶解成本提供了一定的理论支持。     

二氧化氯对苹果表面和鲜榨苹果汁中酿酒酵母1450的杀灭效果

利用二氧化氯(ClO₂)对水、苹果汁中和苹果表面的酿酒酵母1450(Saccharomyces cerevisiae)进行杀菌处理。结果表明：6、12 mg/L的ClO₂处理15 min使水中酵母分别减少(5.81±0.12)和(6.20±0.05)lg cfu/mL;100 mg/L的ClO₂对苹果汁中酵母的杀菌作用不明显,200 mg/L的ClO₂处理1 h可将果汁中(3.79±0.04)lg cfu/mL的酵母完全杀死,使果汁中(6.48±0.03)lg cfu/mL的酵母减少(3.67±0.05)lg cfu/mL,300 mg/L的ClO₂可将苹果汁中(6.52±0.06)lg cfu/mL的酵母完全杀死;10、20、30和40 mg/L的ClO₂处理1 h使苹果表面接种量为(4.95±0.02)lg cfu/mL的酵母数分别减少(3.41±0.02)、(3.64±0.08)、(3.80±0.04)、(4.47±0.09)lg cfu/mL,50 mg/L的ClO₂处理1 h,可将接种于苹果表面的酵母全部杀死,接种量进一步增加,ClO₂对苹果表面酵母的杀灭效果将会减弱;ClO₂处理对苹果汁的理化指标影响较小。     

氩弧熔覆原位合成Ni基耐磨层在犁铧上的应用

利用氩弧熔覆技术,在廉价的碳钢表面原位合成了TiC/Ni基复合材料涂层。结果表明,熔覆层成形良好,与基体呈冶金结合,无裂纹、气孔等缺陷;熔覆层的组织为γ-Ni奥氏体枝晶、CrB、TiB₂、M₂₃C₆及原位合成的弥散分布于熔覆层中的球状TiC陶瓷颗粒。熔覆层显微硬度高达HV_0.21000,且呈梯度分布。磨损试验表明,熔覆层具有较好的耐磨性。模拟田间试验表明,熔覆层可用于农机耐磨件的制造与再制造并具有较好的经济效益。     

堆肥反应器中表面活性剂APG对牛粪堆肥酶活性的影响

利用堆肥反应器严格控制堆肥条件, 以牛粪为主要原料进行好氧堆肥, 在堆肥过程中加入表面活性剂烷基多糖苷(APG), 研究其对堆肥中微生物数量以及酶活性变化的影响。结果表明: 在好氧堆肥中添加表面活性剂APG对堆肥中的微生物无显著抑制作用, 微生物数量无显著变化(P>0.05); 但可以促进堆肥升温, 延长高温期。加入APG对堆肥中的过氧化氢酶活性几乎无影响, 最终APG处理和CK处理的酶活性值均达到1.17 mmol·g^-1左右; 加入APG后脲酶活性略有提高, 第2 d APG处理和CK处理的脲酶活性均达到峰值, 分别为32.15 mg(NH₃-N)·g^-1·24h^-1和30.17 mg(NH₃-N)·g^-1·24h^-1, 差异不显著(P>0.05), 第7 d达到最低值, 分别为0.81 mg(NH₃-N)·g^-1·24h^-1和0.38 mg(NH₃-N)·g^-1·24h^-1, 差异显著(P<0.05); APG处理对转化酶和纤维素酶活性均有明显的提高作用, 其中转化酶在第3 d加APG处理和CK处理峰值分别为18.15 mg(葡萄糖)·g^-1·24h^-1和11.77 mg(葡萄糖)·g^-1·24h^-1, 第21 d两处理峰值分别为24.09 mg(葡萄糖)·g^-1·24h^-1和20.71 mg(葡萄糖)·g^-1·24h^-1, 差异显著(P<0.05); 纤维素酶在第3 d加APG处理和CK处理峰值分别为58.77 mg·min^-1和30.62 mg·min^-1, 差异显著(P<0.05)。本试验结果表明, 添加表面活性剂APG可以提高堆肥中转化酶和纤维素酶活性, 促进堆肥中有机物质的转化, 一定程度上加快好氧堆肥进程。     

磁化水复合保氮剂对堆肥过程中氮素损失和微生物群落的影响

为了研究不同保氮剂对快速堆肥过程中氮素损失及微生物群落的影响,该研究以牛粪和秸秆为原料,进行了25 d的好氧堆肥试验。试验中设置了磁化水（T1）、磁化水复合生物炭（T2）、磁化水复合硫酸亚铁（T3）、磁化水复合巨大芽孢杆菌（T4）,不添加磁化水和保氮剂作为对照组（CK）。试验结果表明：与对照组相比,T1、T2、T3、T4均延长了堆肥的高温期,延长了4、5、2、4 d。T1、T2、T4的最高温较CK分别提高了3.5、8、0.5 ℃。从温度上来看,T1未进行二次腐熟,缩短了堆肥周期;各处理组的总氮含量较堆肥初始时提高了14.04%、18.89%、37.56%、36.27%、28.47%,总氨气排放量分别为8.12、4.37、6.60、7.32、3.95 g/d。与对照组相比,T1、T2、T3、T4均提高了堆肥的总氮含量,降低了总氨气排放量。T2总氮含量高于其他处理,T1总氨气排放量低于其他处理;与CK相比,T2促进了氮循环基因gdhA的绝对丰度,抑制了拟杆菌门的相对丰度,促进了氮素循环、堆肥进程。与CK相比T3促进了固氮基因nifH、氮循环基因gdhA的绝对丰度,促进了变形菌门的相对丰度,有利于氮素的循环;此外,结构方程显示,T2与NH₃ emission呈显著负效应,NH₃ emission与TN_loss呈显著正效应,解释了生物炭通过吸附NH₃,减少氮素损失。T3与pH呈显著负效应,pH与NH₃ emission呈显著正效应,NH₃ emission与TN_loss呈显著正效应,FeSO₄的加入降低了堆体的pH值,减少氨气的排放,进而减少氮素损失;综合堆肥过程中的温度、总氮含量、总氨气排放量、氮功能基因的绝对丰度、微生物的相对丰度以及结构方程模型分析,磁化水复合生物炭在快速堆肥过程中表现出最佳的保氮效果和理想的腐熟程度。     

Determination of Surface Tension Properties of Wheat Endosperms,Wheat Flours,and Wheat Glutens

During wheat dough processing, a large part of the interactions with water are governed by wettability properties of flour. The wettability properties of wheat materials (flat slices of wheat endosperm, flour‐based pellets, and gluten‐based pellets) were assessed by the measurement of contact angles of a sessile drop of three reference liquids (water, diiodomethane, and formamide) and estimated by equilibrium properties (contact angles and surface tension properties) and drop penetration rates. The surface tension (γ_s) of wheat materials was measured between 49.6 and 55.3 mJ/m^‐2. The present work permitted the evaluation of specific wheat types (hard wheat vs. soft wheat) and evaluation of the influence of material structure (flat slices of endosperm vs. flour‐based pellets), and material nature (flour‐based pellets vs. gluten‐based pellets) on the wettability properties. The surface tension properties were considered with regard to the nonideal structure of sample surfaces by considering surface roughness and material porosity.     

Superhydrophobic surfaces: a model approach to predict contact angle and surface energy of soil particles

Wettability of soil affects a wide variety of processes including infiltration, preferential flow and surface runoff. The problem of determining contact angles and surface energy of powders, such as soil particles, remains unsolved. So far, several theories and approaches have been proposed, but formulation of surface and interfacial free energy, as regards its components, is still a very debatable issue. In the present study, the general problem of the interpretation of contact angles and surface free energy on chemically heterogeneous and rough soil particle surfaces is evaluated by a reformulation of the Cassie‐Baxter equation, assuming that the particles are attached on to a plane and rigid surface. Compared with common approaches, our model considers a roughness factor that depends on the Young’s Law contact angle determined by the surface chemistry. Results of the model are discussed and compared with independent contact angle measurements using the Sessile Drop and the Wilhelmy Plate methods. Based on contact angle data, the critical surface tension of the grains were determined by the method proposed by Zisman. Experiments were made with glass beads and three soil materials ranging from sand to clay. Soil particles were coated with different loadings of dichlorodimethylsilane (DCDMS) to vary the wettability. Varying the solid surface tension using DCDMS treatments provided pure water‐wetting behaviours ranging from wettable to extremely hydrophobic, with contact angles > 150°. Results showed that the critical surface energy measured on grains with the highest DCDMS loadings was similar to the surface energy measured independently on ideal DCDMS‐coated smooth glass plates, except for the clay soil. Contact angles measured on plane surfaces were related to contact angles measured on rough grain surfaces using the new model based on the combined Cassie‐Baxter Wenzel equation, which takes into account the particle packing density on the sample surface.     

仿生柔性非光滑表面的结构优化设计

根据土壤动物柔性非光滑的特征规律和仿生类比的结果,采用数值优化和ＣＡＤ几何造型技术,通过计算机模拟,构造了圆柱形、半圆柱形、布型和链型仿生柔性非光滑面,为柔性仿生减粘技术的开发创造了条件。     

土壤和润湿研究中的分形现象

分形几何学的理论与方法已被用于土壤表面不规则性、旋耕土块轮廓及表面裂纹形状和分布、土壤值的空间分布及固体表面润湿性的研究中,利用分形维数定量探讨它们的规律性。本文综合评述了土壤表面、土块轮廓与裂纹、土壤值及润湿研究中的分形特性。     

Inhibition of acidification of kaolinite and an Alfisol by aluminum oxides through electrical double‐layer interaction and coating

Soil chemical properties are affected significantly by surface charge characteristics of the soil. Interaction between oppositely charged particles in variable‐charge soils plays an important role in variation of soil electrochemical properties. In this study, the effects of Al oxides on surface charge and acidity properties of kaolinite and an Alfisol during electrodialysis were investigated. The results indicated that Al oxides, when mixed into kaolinite or the Alfisol, decreased the effective cation exchange capacity (ECEC) and exchangeable acidity and inhibited the decrease in pH. Gibbsite had less effect than γ‐Al₂O₃ and amorphous Al(OH)₃ in reducing the ECEC and acidity of kaolinite and the Alfisol; γ‐Al₂O₃ and amorphous Al(OH)₃ displayed comparable effects. However, this effect is inconsistent with the order of the surface positive charge per unit mass that the Al oxides carried. Their effect on the ECEC of kaolinite and Alfisol varied irreversibly with ionic strength of the bathing solutions. X‐ray diffraction spectra indicated that amorphous Al(OH)₃ and γ‐Al₂O₃ were more effective than gibbsite in decreasing peak intensity of electro‐dialyzed kaolinite when mixed with these Al oxides at the same rate. The results demonstrated that Al oxides could decrease the effective negative charge and inhibit acidification of kaolinite and an Alfisol through diffuse‐double‐layer overlapping between oppositely charged particles and coating of Al oxides on these materials. Both mechanisms intensified with increasing rate of added Al oxides, which can therefore act as anti‐acidification agents in variable‐charge soils.     

Droplet infiltration and organic matter composition of intact crack and biopore surfaces from clay‐illuvial horizons

The organic matter (OM) in biopore walls and aggregate coatings may be important for sorption of reactive solutes and water as well as for solute mass exchange between the soil matrix and the preferential flow (PF) domains in structured soil. Structural surfaces are coated by illuvial clay‐organic material and by OM of different origin, e.g., earthworm casts and root residues. The objectives were to verify the effect of OM on wettability and infiltration of intact structural surfaces in clay‐illuvial horizons (Bt) of Luvisols and to investigate the relevance of the mm‐scale distribution of OM composition on the water and solute transfer. Intact aggregate surfaces and biopore walls were prepared from Bt horizons of Luvisols developed from Loess and glacial till. The mm‐scale spatial distribution of OM composition was scanned using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The ratio between alkyl and carboxyl functional groups in OM was used as potential wettability index (PWI) of the OM. The infiltration dynamics of water and ethanol droplets were determined measuring contact angles (CA) and water drop penetration times (WDPT). At intact surfaces of earthworm burrows and coated cracks of the Loess‐Bt, the potential wettability of the OM was significantly reduced compared to the uncoated matrix. These data corresponded to increased WDPT, indicating a mm‐scaled sub‐critical water repellency. The relation was highly linear for earthworm burrows and crack coatings from the Loess‐Bt with WDPT > 2.5 s. Other surfaces of the Loess‐Bt and most surfaces of the till‐derived Bt were not found to be repellent. At these surfaces, no relations between the potential wettability of the OM and the actual wettability of the surface were found. The results suggest that water absorption at intact surface structures, i.e., mass exchange between PF paths and soil matrix, can be locally affected by a mm‐scale OM distribution if OM is of increased content and is enriched in alkyl functional groups. For such surfaces, the relation between potential and actual wettability provides the possibility to evaluate the mm‐scale spatial distribution of wettability and sorption and mass exchange from DRIFT spectroscopic scanning.     

Calcium accumulation alleviates soil acidification in Japanese cedar (Cryptomeria japonica) stands

Based on chemical and mechanical compositions and quartz content of red and/or yellow colored soil materials in the southwestern part of Japan, lithology index (LI) and weathering index (WI) were derived using a multivariate statistical method (factor analysis). The variables used for factor analysis are Fe₂O₃/Al₂O₃, TiO₂/Al₂O₃, Fe₂O₃+Al₂O₃+Quartz, Si(non-quartz)/(Fe₂O₃ + Al₂O₃), CaO + MgO + K₂O₃, MgO/K₂O₃ and Quartz/Sand, all of which represent certain different aspects of weathering and/or Iithological characteristics. Since LI and WI are mutually independent, it is possible to evaluate the effect of the degree of weathering on the characteristics of red and/or yellow colored soil materials independently from that of lithology.     

Universality of a surface tension—contact‐angle relation for hydrophobic soils of different texture

Wettability of soil affects a wide variety of processes in soils like infiltration, percolation, preferential flow, and surface runoff. Even though efforts have been made to determine contact angles and surface tension or energy of smooth surfaces, the determination on granular materials like soil particles remains unsolved. One objective of this study was to test the consistency of contact angles (CA) measured with the newly modified and easy‐to‐apply Wilhelmy plate method by using solid particles and liquids with defined variations of surface tension. A second objective was to derive basic physical surface properties for the irregularly shaped and chemically heterogeneous soil particles. Advancing contact angles were determined by using model soils varying in texture from clay to coarse sand to check the impact of grain size on the CA measurements. Varying the solid‐surface tension with dichlorodimethlylsilane treatments provided for pure‐water wetting stages ranging from wettable to extremely hydrophobic. The surface tensions of the liquids were varied from 72 mN m^–1 to 25 mN m^–1 by using water or water‐ethanol mixtures. The surface tensions of the model soils were determined with the zero degree–contact angle method following Zisman's critical–surface tension concept. Results show that the measured CA varied continuously with the variations of the surface tension of the liquid and the solid phase, respectively. A general interpretation of the results is possible by using the concept of the Equation of State Approach.     

THE RESIDUA SYSTEM OF CHEMICAL WEATHERING: A MODEL FOR THE CHEMICAL BREAKDOWN OF SILICATE ROCKS AT THE SURFACE OF THE EARTH

The residua system of chemical weathering is here defined as the chemical sink towards which the bulk of earth's surface materials (i.e. the silicate rocks) trend during weathering. Chemically the system is defined in terms of four major components, SiO₂–Al₂O₃–Fe₂O₃–H₂O, evidence being derived from relative solubilities of components under earth-surface conditions; from experiments in which weathering environments have been simulated in the laboratory; and from field studies of rocks and their weathered mantle. The residua system can be used as a framework to construct mineral facies diagrams showing assemblages of the commonest earth-surface minerals that occur within it: quartz, gibbsite, goethite, kaolinite, halloysite. In a qualitative manner the facies diagrams can then be interpreted in terms of the partial pressure of water (PH₄O) and the temperature, T. The usefulness of this approach in systematizing studies of soil genesis is illustrated with reference to the weathering of granite.