CFRP-木材复合材界面的湿热效应研究

研究了CFRP与木材间界面随环境湿热状态的影响。结果表明：温度为40℃时,界面等温湿应变随湿度变化影响较小,木材材面受影响显著;湿度为95％时,界面等湿热应变表现为热胀冷缩,应变与温度变化趋势一致;湿热处理易使复合材及界面老化,严重削弱CFRP的增强效果,CFRP在湿热环境使用时应做防护处理;干热处理对复合材抗弯性能影响较小,复合材界面结合可靠。     

Zinc adsorption effects on arsenite oxidation kinetics at the birnessite-water interface

Arsenite is more toxic and mobile than As(V) in soil and sediment environments, and thus it is advantageous to explore factors that enhance oxidation of As(III) to As(V). Previous studies showed that manganese oxides, such as birnessite (delta-MnO2), directly oxidized As(III). However, these studies did not explore the role that cation adsorption has on As(III) oxidation. Accordingly, the effects of adsorbed and nonadsorbed Zn on arsenite (As(III)) oxidation kinetics at the birnessite-water interface were investigated using batch adsorption experiments (0.1 g L(-1); pH 4.5 and 6.0; I= 0.01 M NaCl). Divalent Zn adsorption on synthetic delta-MnO2 in the absence of As(II) increased with increasing pH and caused positive shifts in electrophoretic mobility values at pH 4-6, indirectly suggesting inner-sphere Zn adsorption mechanisms. Arsenite was readily oxidized on birnessite in the absence of Zn. The initial As(III) oxidation rate constant decreased with increasing pH from 4.5 to 6.0 and initial As(III) concentrations from 100 to 300 microM. Similar pH and initial As(III) concentration effects were observed in systems when Zn was present (i.e., presorbed Zn prior to As(III) addition and simultaneously added Zn-As(III) systems), but As(III) oxidation reactions were suppressed compared to the respective control systems. The suppression was more pronounced when Zn was presorbed on the delta-MnO2 surfaces as opposed to added simultaneously with As(III). This study provides further understanding of As(III) oxidation reactions on manganese oxide surfaces under environmentally applicable conditions where metals compete for reactive sites.     

木材树脂组分之间的相互作用及其对体系稳定性的影响

首先研究了在钙离子存在条件下,三种模型物乳液(树脂酸R、脂肪酸O,甘油三酯TG)的稳定性,结果发现,中性的甘油三酯TG乳液的稳定性最差.接着,研究了树脂模型物各组分之间的相互作用对体系稳定性的影响.结果发现,乳液的制备方法不同,三者在体系中的相互作用也不同.     

蛋白质和多糖在界面处的相互作用研究进展

蛋白质和多糖两种生物大分子在界面处的相互作用对于乳状液和泡沫体系有显著影响。蛋白质和多糖混合后的协同效应可构建新的、功能性的纳、微或宏观结构,改变食品的力学和流动特性,对改良食品,降低生产成本具有重要意义。本文对近年来蛋白质的界面行为,多糖的界面行为以及蛋白质-多糖复合物的界面行为所做的一些研究进行综述。      

Effect of excessive pretreatment of pine timber with CCA wood preservatives on the bond quality of PRF and TRF wood adhesives

The phenol-resorcinol-formaldehyde adhesive is suitable for use at all levels of CCA retention that were tested. Due to changes in retention during treatment, best results are obtained if the glue-spread rate is kept above the standard of 200 g/m², or control measures are taken to prevent the glue-spread from dropping below this level. The tannin-resorcinol-formaldehyde adhesive, without modification, unlike its performance in the manufacture of plywood, appears from these tests to be less suitable for use on treated timber from the view point of lowered percentage of wood failure.     

A sensory system at the interface between urban stormwater runoff and salmon survival

Motor vehicles are a major source of toxic contaminants such as copper, a metal that originates from vehicle exhaust and brake pad wear. Copper and other pollutants are deposited on roads and other impervious surfaces and then transported to aquatic habitats via stormwater runoff. In the western United States, exposure to non-point source pollutants such as copper is an emerging concern for many populations of threatened and endangered Pacific salmon (Oncorhynchus spp.) that spawn and rear in coastal watersheds and estuaries. To address this concern, we used conventional neurophysiological recordings to investigate the impact of ecologically relevant copper exposures (0-20 microg/L for 3 h) on the olfactory system of juvenile coho salmon (O. kisutch). These recordings were combined with computer-assisted video analyses of behavior to evaluate the sensitivity and responsiveness of copper-exposed coho to a chemical predation cue (conspecific alarm pheromone). The sensory physiology and predator avoidance behaviors of juvenile coho were both significantly impaired by copper at concentrations as low as 2 microg/L. Therefore, copper-containing stormwater runoff from urban landscapes has the potential to cause chemosensory deprivation and increased predation mortality in exposed salmon.     

Hexamine hardener behaviour: effects on wood glueing, tannin and other wood adhesives

13 C NMR evidence is presented confirming that the main decomposition (and recomposition) mechanism of hexamine is not directly due to formaldehyde but rather proceeds through now-identified intermediates, i.e. mainly through the formation of reactive imines rather than methylene bases, possibly also forming a very slight amount of iminomethylene bases. This also confirms that any species with strong real or nominal negative charge under alkaline conditions, be it a tannin, resorcinol or other highly reactive phenols, be it melamine or another highly reactive amine or amide, or an organic or inorganic anion, it is capable of reacting with the intermediate species formed by decomposition (or recomposition) of hexamine far more readily than formaldehyde explaining the capability of wood adhesives formulations based on hexamine to give bonded panels of extremely low formaldehyde emission. If no highly reactive species with strong real or nominal negative charge is present, then decomposition of hexamine proceeds rapidly to formaldehyde formation as reported in previous literature. The elucidation of the hexamine decomposition mechanism, which is presented, and a scanning electron microscopy (SEM) investigation also allowed to advance a reason for the without-curing-formation of ambient temperature stiff gels in tannin/hexamine glue mixes and to propose chemical structures for the ionic coordination linear polymers formed.

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13 C NMR-Spektren machten deutlich, da? der haupts?chliche Zersetzungs- und Wiederaufbaumechanismus des Hexamins nicht unmittelbar über Formaldehyd, sondern über jetzt identifizierte Zwischenverbindungen verl?uft, d.h. überwiegend über die Bildung von reaktiven Iminen anstatt über Methylenbasen; nur ein sehr geringer Anteil an Iminomethylenbasen kann dabei ebenfalls entstehen. Die Untersuchungen zeigten auch, da? jede Komponente mit starker realer oder nomineller negativer Ladung unter alkalischen Bedingungen in der Lage ist, mit den Zwischenprodukten beim Abbau und Wiederaufbau des Hexamins viel schneller zu reagieren als Formaldehyd. Das gilt sowohl für Tanrin, Resorcin oder andere hochreaktive Phenole, als auch für Melanin oder andere hochreaktive Amine oder Amide, und allgemein für organische oder anorganische Anionen. Dies erkl?rt die Besonderheit, da? mit Holzklebern unter Hexaminzusatz Platten mit extrem niedriger Formaldehydemission hergestellt werden k?nnen. Wenn keine Komponente mit starker negativer Ladung im Harzgemisch vorhanden ist, dann führt der Hexaminabbau rasch zu Formaldehyd wie es bisher in der Literatur beschrieben wurde. Die Aufkl?rung des Mechanismus des Hexaminabbaus sowie Rasterelektronenmikroskopische Untersuchungen lieferten zudem eine Begründung für die Bildung fester Gele (ohne Aush?rtung) bei Umgebungstemperatur. Daraufhin konnte auch eine chemische Struktur für die gebildeten ionischen linearen Polymere vorschlagen werden.

     

Comparison between two- and three-dimensional diffusion models to describe wood drying at low temperature

An experiment on convective drying of lumber was performed at a temperature of 40 °C. A two-dimensional numerical solution of the diffusion equation with boundary condition of the third kind and variable effective mass diffusivity (model 1) was proposed to describe drying. The solution was coupled with an optimizer to determine the process parameters. The results were compared with those obtained by a typical three-dimensional numerical solution (model 2). The analyses of the results indicated that the parameters (and the simulation) obtained using model 1 are very close to the results obtained with model 2. However, the optimization time for model 1 is about 20 times less than the optimization time for model 2.     

纹理方向对木材与橡胶带间摩擦系数的影响

通过实验分别测定了杨木、红松和水曲柳顺纹、横纹和斜纹试件与6种不同型号橡胶带之间的摩擦系数.结果表明:横纹的摩擦系数最大,斜纹次之,顺纹最小；除了纹理方向对摩擦系数的影响之外,木材的材种、橡胶带的花纹形式及硬度也会对摩擦系数产生一定的影响.     

Arsenate adsorption mechanisms at the allophane-water interface

We investigated arsenate (As(V)) reactivity and surface speciation on amorphous aluminosilicate mineral (synthetic allophane) surfaces using batch adsorption experiments, powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The adsorption isotherm experiments indicated that As(V) uptake increased with increasing [As-(V)]0 from 50 to 1000 microM (i.e., Langmuir type adsorption isotherm) and that the total As adsorption slightly decreased with increasing NaCl concentrations from 0.01 to 0.1 M. Arsenate adsorption was initially (0-10 h) rapid followed by a slow continuum uptake, and the adsorption processes reached the steady state after 720 h. X-ray absorption spectroscopic analyses suggest that As(V) predominantly forms bidentate binuclear surface species on aluminum octahedral structures, and these species are stable up to 11 months. Solubility calculations and powder XRD analyses indicate no evidence of crystalline Al-As(V) precipitates in the experimental systems. Overall, macroscopic and spectroscopic evidence suggest that the As(V) adsorption mechanisms at the allophane-water interface are attributable to ligand exchange reactions between As-(V) and surface-coordinated water molecules and hydroxyl and silicate ions. The research findings imply that dissolved tetrahedral oxyanions (e.g., H2PO42- and H2AsO4(2-)) are readily retained on amorphous aluminosilicate minerals in aquifer and soils at near neutral pH. The inner-sphere adsorption mechanisms might be important in controlling dissolved arsenate and phosphate in amorphous aluminosilicate-rich low-temperature geochemical environments.     

芳纶纤维与浆粕材料界面结构的TEM表征

采用透射电镜（TEM）对芳纶纤维/浆粕界面特征进行表征,探讨了界面微观结构与芳纶纸基材料综合性能的相关性。TEM观察结果表明,不同制造工艺的纤维,其微细纤维的精细程度有较大差异;热压过程并没有使得芳纶微纤维间熔融为一体,而是在纤维与基体间形成一个相互交叉的过渡区界面。界面的结构也不尽相同,纤维与浆粕间界面结构或形成镶嵌的＂钉扎型＂,或形成＂间隙型＂界面。这些结构对纤维与浆粕间的结合性能造成明显差异,因而对纸张物理性能也有明显的影响。     

On the friction between steel and some common swedish wood species

During cutting of wood, friction plays an important role. The coefficient of friction between steel and some common Swedish wood species was studied. The effects of moisture content, sliding speed, smoothness of steel surface, wood species and direction of the grain on the coefficient were determined and the changes in friction with duration of rubbing, the softness of wood surface, and the surface adhesion and deformation were discussed.     

Interaction between soy protein isolate and surfactant at the interface of antibacterial nanoemulsions loaded with riboflavin tetra butyrate

Riboflavin tetra butyrate (RTB) is an effective antimicrobial photosensitiser that poses a challenge for long-term preservation and application due to its hydrophobicity and instability. To overcome this problem, a series of nanoemulsions loaded with photosensitiser RTB was prepared in this study by using soy protein isolate (SPI) as an emulsifier and small molecule surfactant (X) as co-emulsifier. The interaction mechanism of SPI+X co-emulsifier and its influence on the stability of emulsion and photosensitiser were explored, and the photodynamic bactericidal effect of the prepared RTB emulsion on S. aureus was studied. SPI and four types of surfactants were present in the form of synergistic (Tween 80, T80) or competition (Span 80, S80 and lecithin, LEC) adsorption or formation of Pickering emulsion (Sodium dodecyl sulphate, SDS) at the oil–water interface. The experimental results revealed that the stable encapsulation ability of RTB emulsions for photosensitisers and their preservation ability can be drastically improved. This work verified that all RTB emulsions could inactive S. aureus under blue light, with an antibacterial ratio of more than 70%. Therefore, the emulsion-based delivery system effectively improved the water dispersibility and chemical stability of RTB. These results demonstrate that RTB emulsion has the potential to be used as a food-grade antibacterial emulsion.     

定向培育三个材种及低质材改良的综述

通过对三种材质树木的定向培育和材性的改良,总结出改变其材性的方法和理论依据。     

Formation of metal-arsenate precipitates at the goethite-water interface

Little information is available concerning cosorbing oxyanion and metal contaminants in the environment, yet in most metal-contaminated areas, cocontamination by arsenate [AsO4, As(V)] is common. This study investigated the cosorption of As(V) and Zn on goethite at pH 4 and 7 as a function of final solution concentration. Complimentary extended X-ray absorption fine structure (EXAFS) spectroscopic data were collected at the As and Zn K-edges in order to glean information about the coordination environment of As and Zn at the goethite-water interface. Macroscopic sorption studies revealed that As(V) and Zn sorption on goethite increased in cosorption experiments beyond that suggested by single sorption isotherms. At pH 4 and 7, As(V) surface saturation was 3.2 and 2.2 micromol m(-2), respectively, and Zn surface saturation was absent at pH 4 and approximately 1.0 micromol m(-2) at pH 7. Arsenate sorption on goethite increased in the presence of Zn by 29% and by more than 500% at pH 4 and 7, respectively. In the presence of As(V), Zn sorption on goethite increased by 800 and 1300% at pH 4 and 7, respectively. More As(V) than Zn sorbed on goethite below surface saturation at pH 7. Above surface saturation, the Zn:As surface density ratio (SDR) remained constant at 0.91 +/- 0.03. At pH 4, the Zn:As SDR was less than 1 throughout the concentration range. Below As(V) surface saturation on goethite, As(V) formed bidentate binuclear bridging complexes on Fe and/or Zn octahedra, while Zn mainly formed edge-sharing complexes with Fe at the goethite surface. Above surface saturation, Zn was increasingly complexed by AsO4, gradually forming an adamite-like [Zn2(AsO4)OH] surface precipitate on goethite. Precipitated contaminants are more stable due to the limited dissolution kinetics of their solid phase. This study may therefore prove useful in remediation strategies of sites knowingly contaminated with oxyanions and metals.