Possible mechanism of oil formation in a flow of supercritical fluid (using carbon dioxide as an example)

An experimental study of the supercritical fluid extraction of the organic substance with carbon dioxide from rock and soil showed that a supercritical (SC) fluid can dissolve, transfer, and accumulate petroleum-like hydrocarbons including relict ones. It was hypothesized that during the supercritical extraction, the dissolution of organic substances is accompanied by their mechanochemical transformation in the micropores and microcracks of the solid. The resulting changes in the composition, structure, and distribution of the individual hydrocarbons are similar to those in petroleum-mother rocks. We can therefore assume that fast mechanochemical transformation of the dispersed organic matter of sedimentary rocks takes place in a flow of a deep supercritical fluid. This, in turn, would allow one to revise the time scale of oil accumulation from millions to possibly hundreds of years.     

荧光光谱技术的交趾黄檀和奥氏黄檀树种识别新方法

自然界植物物种中存在小分子有机化合物的荧光特征信息用于识别其身份具有潜在的应用价值。目前,基于木材解剖学特征的交趾黄檀和奥氏黄檀木材树种鉴定存在一定的局限性。该研究从荧光特征出发探索两个红木树种的识别新方法。分别对5组交趾黄檀和5组奥氏黄檀木材样品中的荧光物质进行完整提取,通过荧光照片、二维荧光谱图、三维荧光谱图对两个红木样品存在的荧光物质种类和数量进行了确认。荧光照片结果显示交趾黄檀和奥氏黄檀均呈现明显的荧光特征且随着存贮时间的变化荧光物质能够稳定存在;二维荧光谱图和三维荧光谱图更加详细地展示了两个树种各自的荧光特征,结果显示交趾黄檀提取液含有一种荧光物质,该物质的最大激发波长为297 nm,最大荧光发射波长为327 nm;奥氏黄檀提取液的荧光谱图呈现两个最大激发和两个最大发射,最大激发波长分别为317和333 nm,最大荧光发射波长分别为342和358 nm,表明奥氏黄檀提取液中包含两种荧光物质或者存在一种含两种荧光团的荧光物质。另外,不同来源的两个红木试样存在的荧光物质数量和特征各自具有明显的一致性,且两种树种之间存在明显的区别,表明荧光特征能够用于它们身份的识别。此外,该研究构建了交趾黄檀和奥氏黄檀两个红木树种的荧光物质提取方法,交趾黄檀荧光物质的最佳提取试剂为乙腈,体积比为10∶1的乙酸乙酯和乙腈混合试剂更加适用于奥氏黄檀,且两种荧光物质的提取均在12 h内达到稳定。研究结果表明荧光光谱技术能够用于交趾黄檀和奥氏黄檀的识别与鉴定,该方法在红木树种的鉴定具有十分重要的应用价值。     

真空热处理人工林落叶松木材吸湿性变化机理研究

热处理是一种环境友好型的木材改性方法,可提高木材的耐腐性和尺寸稳定性。研究以落叶松木材为试验材料,在处理温度200 ℃的条件下,对其进行了不同时间的真空热处理。利用动态水蒸气吸附(DVS)对热处理前后木材吸湿性的变化进行了表征,通过傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和X射线衍射(XRD)分析了热处理前后木材化学组分和结构变化,通过化学变化分析阐明了热处理木材吸湿性变化的作用机制。结果表明：真空热处理落叶松木材的平衡含水率降低,热处理木材的平衡含水率随热处理时间的延长呈逐渐下降的趋势。结合红外光谱和光电子能谱发现,热处理后木材纤维素和半纤维素等化学成分发生降解,木质素发生交联缩合反应,使得吸湿性基团含量减少,碳元素与氧元素含量发生变化,氧碳比降低,从C原子的结合形式来看,热处理材的C1含量增加,C2和C3含量降低,这些化学变化使得热处理材的吸湿性降低。此外,真空热处理未破坏木材的结晶结构,木材的相对结晶度随真空热处理时间的延长而增大,结晶度的增大减少了纤维素分子链上吸水性基团的数量,从而降低了木材的吸湿性。     

Optimization of ultrasound extraction of phenolic compounds from coconut (Cocos nucifera) shell powder by response surface methodology

Coconut is a tropical fruit largely consumed in many countries. In some areas of the Brazilian coast, coconut shell represents more than 60% of the domestic waste volume. The coconut shell is composed mainly of lignin and cellulose, having a chemical composition very similar to wood and suitable for phenolic extraction. In this work, the use of ultrasound to extract phenolic compounds from coconut shell was evaluated. The effect of temperature, solution to solid ratio, pH and extraction time were evaluated through a 2(4) experimental planning. The extraction process was also optimized using surface response methodology. At the optimum operating condition (30 degrees C, solution to solid ratio of 50, 15 min of extraction and pH 6.5) the process yielded 22.44 mg of phenolic compounds per gram of coconut shell.     

Effect of extractives on the flexural properties of wood/plastic composites

This study investigated the effect of extractives in wood flour on the mechanical properties of wood-polypropylene (PP) composites. Three different solvents, acetone/water, dioxane/water and benzene/ethanol, were used to remove extractives in both pine and Douglas fir wood flour. X-ray photoelectron spectroscopy (XPS) confirmed that extraction resulted in a change in the surface composition of the wood flour. Differential scanning calorimetry showed no changes in the percent crystallinity of the PP matrix in the wood-PP composites and optical microscopy showed no detectable changes in PP spherulite size or shape between filled PP containing extracted and unextracted wood flour. A large increase in the strength of pine flour-PP composites was observed upon removal of extractives from pine flour. The Douglas fir flour-PP composites showed a smaller, but statistically significant, increase in strength upon removal of extractives, with the exception of the dioxane/water extracted Douglas fir. Significant differences were also observed in stiffness between extracted wood-PP and unextracted wood-PP composites with the exception of the dioxane/water extracted Douglas fir, which was not significantly different from the control.     

原位聚合制备木材/羟甲基脲复合材料及其表征

以杨木生材为原料,采用原位聚合方法制备木材/羟甲基脲复合材料.羟甲基脲在脉冲式压力的作用下浸渍到木材内,在热压干燥过程中,经过原位聚合制备木基复合材料.根据国标对改性前后的木材化学成分进行了分析,并利用X射线光电子能谱(XPS)、核磁共振分析(3C-NMR)、EDXA对改性前后木材中碳和氮元素含量、分布以及官能团变化进...     

Fatty Acid Composition and Biological Activity of Supercritical Extracts from Arctic Brown Algae <Emphasis Type="Italic">Fucus vesiculosus</Emphasis>

The fatty acid composition of arctic brown algae was studied using supercritical (SC) fluid extraction. A method for fractionating the SC extract based on the differences in the solubility of its components (fatty acids, polyphenols) was proposed. The composition and biological activity of the fractions were studied.     

The radioprotective and prophylactic properties of biologically active substances prepared by supercritical fluid extraction from pine shoots

The radioprotective properties of a substance from pine shoots prepared by supercritical fluid extraction with carbon dioxide were studied for a model of an experimental bone-marrow radiation sickness form. Experiments were performed for white nonlinear mice. The CO₂ extract of pine shoots was shown to possess radioprotective properties. The extract was subjected to pre-clinical tests for Wistar line male rats with respect to its antiatherogenic and antioxidative action in the creation of experimental hyperlipemia.     

Extraction of linear furocoumarins from Ammi Majus seeds by means of supercritical fluid extraction and supercritical fluid chromatography

A method of supercritical fluid extraction of the main furocoumarins (bergapten, xanthotoxin, and isopimpinellin, compounds used as photosensitizers in PUVA therapy) from seeds of apiaceous plant Ammi Majus was developed. A technique for analyzing the composition of extracts and for isolating individual furocoumarins with the help of supercritical fluid chromatography was proposed.     

Fabrication of superhydrophobic wood surface by a sol-gel process

The superhydrophobic wood surface was fabricated via a sol-gel process followed by a fluorination treatment of 1H, 1H, 2H, 2H- perfluoroalkyltriethoxysilanes (POTS) reagent. The crystallization type of silica nanoparticles on wood surface was characterized using X-ray diffraction (XRD), the microstructure and chemical composition of the superhydrophobic wood surface were described by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), the bonding force between the silica nanoparticles and POTS reagent was analyzed by Fourier transform infrared spectroscopy (FT-IR) and the superhydrophobic property of the treated sample was measured by contact angle (CA) measurements. An analytical characterization revealed that nanoscale silica spheres stacked uniformly over the wood surface, and with the combination of the high surface roughness of silica nanoparticles and the low surface free energy film of POTS on wood surface, the wood surface has turned its wetting property from hydrophilic into superhydrophobic with a water contact angle of 164° and sliding angle less than 3°.     

基于TG-FTIR的落叶松木材热失重与热解气相演变规律研究

采用热重红外光谱联用分析法考察了落叶松木材在不同升温速率下的热失重特性及气相演变规律,并与其组分模混物的热解特性进行了对比分析。结果表明,落叶松的主要失重区域相对于模混物较宽,落叶松残炭率(18.97%)相对于模混物(29.83%)较低;在低温段,模混物的活化能高于落叶松木材,而在高温段二者差别不大;落叶松木材热解过程经历了水分析出、主成分热分解、后期炭化等阶段,气体析出主要集中在375℃左右;落叶松在热解反应过程中,主要气体产物生成量顺序为CO2>H2O>CH4>CO,随着升温速率的增加,上述气体产物的生成量明显增多;模混物与落叶松木材热解生成气体规律基本相似,但模混物中各气体析出强度均相对较高。     

An ultrasound assisted extraction of the available humic substance from marine sediments

In this paper an ultrasound assisted procedure for the extraction of the bio-available fraction of humic substance in marine sediments is described. The proposed method is based on a preliminary 24 h 8 M HCl treatment already proposed in a previous paper [M. Mecozzi, E. Pietrantonio, M. Amici, Fres. Environ. Bull. 7 (1998) 605], followed by consecutive extractions by 0.5 M NaOH coupling to an ultrasonic treatment. The main advantages of the ultrasound procedure are the reduced times of extraction which take 30 min in contrast to the 24 h required by shaking method and the possibility to perform also the quantitative estimation of the extractable fraction of humic substance present in marine samples.     

Imaging of wood tissue by ToF-SIMS: Critical evaluation and development of sample preparation techniques

Tissue of Norway spruce wood was investigated by time-of-flight secondary-ion mass spectrometry (ToF-SIMS) and field-emission scanning electron microscopy (FE-SEM). Different sample preparation techniques (including sectioning and drying) traditionally used for SEM analysis were compared and critically evaluated. A high contamination of wood surfaces by polytetrafluoroethylene (PTFE) introduced onto the sample during sectioning was detected by ToF-SIMS. A new protocol was developed and images of wood sections dried in different ways were compared. Main location of Mg, Na, K and Ca, but no lignin in membranes of bordered pits in spruce section surfaces was detected by ToF-SIMS imaging if critical point drying (CPD) or acetone extraction followed by drying under nitrogen flow (AEND) was applied. No specific locations of wood components as well as low signals from metal ions (Mg and Na) were observed on the wood surfaces of freeze-dried (FD) or air-dried (AD) sections. It was found that extractive substances, presenting on surfaces of FD and AD wood section, were evenly distributed on the surfaces and interfered with ToF-SIMS analysis. Our results indicated that ToF-SIMS imaging was critically sensitive to the sample preparation technique and a strict protocol for characterization of metals, lignin and polysaccharides in wood was suggested.     

Fabrication of superhydrophobic wood surfaces via a solution-immersion process

Superhydrophobic wood surfaces were fabricated from potassium methyl siliconate (PMS) through a convenient solution-immersion method. The reaction involves a hydrogen bond assembly and a polycondensation process. The silanol was formed by reacting PMS aqueous solution with CO₂, which was assembled on the wood surface via hydrogen bonds with the wood surface -OH groups. The polymethylsilsesquioxane coating was obtained through the polycondensation reaction of the hydroxyl between wood and silanol. The morphology of products were characterized using a scanning electron microscope (SEM), the surface chemical composition was determined using energy dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TGA) and contact angle measurement. Analytical results revealed that rough protuberances uniformly covered the wood surface, thus transforming the wood surface from hydrophilic to superhydrophobic. The water contact angle of the superhydrophobic wood surface was about 153° and a sliding angle was 4.6°.     

色谱－质谱联用分析大气颗粒中多环芳烃

采用毛细管气相色谱－质谱联用技术（ＧＣ／ＭＳ）．结合溶剂提取和柱色层分离方法，分析了抚顺市采暖期与非采暖期大气颗粒物样品中多环芳烃的化学组成，结果表明，采暧期多环芳烃种类明显多于非采暖期，其中具有致癌活性的物质约１０种，占总组成的２５％。     

Study on the surface properties of wood/polyethylene composites treated under plasma

Wood/polyethylene (PE) composites are widely used in many fields for its excellent properties, but they are hard to adhere for the surface lacking of polarity. So low-pressure glow discharge of air plasma was used to improve the adhesion properties of wood/PE composites. The composites were treated by plasma under different discharge power. And the changes on the surface properties of the treated and untreated composites were studied by contact angle, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) analysis. The measurement showed that the contact angle decreased after plasma treatment, and the contact angle decreased gradually with the increasing of discharge power. The FTIR analysis results showed that the polar groups such as hydroxyl, carbonyl and carboxyl were formed on the surface of the composites treated under plasma. SEM and AFM results showed that the roughness of plasma treated samples increased. XPS analysis results indicated that the content of carbon element decreased while the content of oxygen element in the composition of wood/PE composites surface element increased and it reached a balance in a higher power, meanwhile a lot of carboxyl groups were formed. The newly formed polar groups are benefit for the adhesion of composites. The shear bonding strength test showed that the adhesion properties of wood/PE composites improved effectively after plasma treatment.     

Moisture Absorption Behavior of Wood/Plastic Composites Made with Ultrasound-Assisted Alkali-Treated Wood Particulates

The combined effects of alkali and ultrasound treatment of wood flour on the moisture absorption behavior of polypropylene-based wood/plastic composites (WPCs) were examined. FT-IR measurements confirmed that the alkali treatment removed both hemicellulose and lignin from the wood, and there was an increase in the number of hydroxyl groups on the cellulose surface. This process was promoted by ultrasound treatment. Particle size analysis of treated wood fibers revealed that alkali treatment reduced the particle size slightly, and the particle size was further reduced by the assistance of ultrasound. Moisture absorption measurements revealed the interplay between the presence of relative amounts of cellulose, hemicellulose and lignin in the wood and the amount of coupling agent added. It was found that appropriate alkali treatment and an optimum amount of added coupling agent could simultaneously improve composite mechanical properties and reduce both the rate and the maximum amount of moisture absorbed. Further improvements require preferential removal of hemicellulose from the wood and conditions that promote covalent bonding between the coupling agent and the wood reinforcement.     

Microstructural features assessment of different waterlogged wood species by NMR diffusion validated with complementary techniques

Wood is a hygroscopic, multi-scale and anisotropic natural material composed of pores with different size and differently oriented. In particular, archaeologically excavated wood generally is waterlogged wood with very high moisture content (400%–800%) that need to have a rapid investigation at the microstructural level to obtain the best treatment with preservative agents. Time-dependent diffusion coefficient D(t) quantified by Pulse Field Gradient (PFG) Nuclear Magnetic Resonance (NMR) techniques provides useful information about complex porous media, such as the tortuosity (τ) describing pore connectivity and fluid transport through media, the average-pore size, the anisotropic degree (a_n). However, diffusion NMR is intrinsically limited since it is an indirect measure of medium microstructure and relies on inferences from models and estimation of relevant diffusion parameters. Therefore, it is necessary to validate the information obtained from NMR diffusion parameters through complementary investigations. In this work, the structures of five waterlogged wood species were studied by PFG of absorbed water. D(t) and τ of water diffusing along and perpendicular to vessels/tracheids main axes together with relaxation times and a_n were quantified. From these parameters, the pore sizes distribution and the wood microstructure characterization were obtained. Results among wood species were compared, validated and integrated by micro-imaging NMR (μ-MRI), environmental-scanning electron-microscope (ESEM) images, wood dry density and imbibition times measurement of all woods. The work suggests that a_n vs τ rather than the estimated pore size diversifies and characterize the different wood species. As a consequence diffusion-anisotropy vs tortuosity could be an alternative method to characterize and differentiate wood species of waterlogged wood when high resolution images (μ-MRI and ESEM) are not available. Moreover, the combined use of D(t) and micro-MRI expands the scale of dimensions observable by NMR covering all the interesting length scales of wood.     

采用特征融合的紫檀属内相似树种识别方法研究

紫檀属中的木材有很多属于名贵木材,不同树种之间十分相似。传统的木材识别方法多以木材解剖学为主,通过观察木材的切片结构特征对木材的树种进行判断,这类方法虽有较高的识别精度,但是其识别工艺较为复杂而且技术难度也相对较高。与木材解剖学相对应的是利用图像信息或光谱信息的木材树种识别方法,该类方法虽具有较为简单的识别工艺,但是在对同属相似木材树种进行识别时,往往不能够取得较好的识别效果。提出了一种基于木材切面光谱特征和纹理特征相融合的木材树种识别方法,该方法不仅识别工艺简单、自动化程度高,而且具有较高的识别精度。首先通过数码相机和光谱仪采集木材切面的图像信息和光谱信息,然后分别使用纹理特征提取方法和光谱特征提取方法提取两类特征的特征向量,接下来使用基于典型相关分析的特征级融合方法将这两个特征向量进行融合,最后使用支持向量机对融合后的特征向量进行分类识别。为了验证方法的有效性,以市场中常见的5种紫檀属树种的三个切面为研究对象,对这些木材树种进行了识别。实验结果显示,单独使用纹理特征的识别正确率最高为80.00%,单独使用光谱特征的识别正确率最高为94.40%,使用融合的特征最高的识别正确率可达99...     

Ultrasound-Assisted Surface-Modification of Wood Particulates for Improved Wood/Plastic Composites

The combined effects of alkali and ultrasound treatment of wood flour on the mechanical properties of polypropylene-based wood/plastic composites (WPCs) were examined. FT-IR measurements confirmed that the alkali treatment removed both hemicellulose and lignin from the wood, and there was an increase in the number of hydroxyl groups on the cellulose surface. This process was promoted by ultrasound treatment. Mechanical testing of injection-molded WPC samples revealed that alkali treatment improved both composite strength and modulus when polypropylene grafted with maleic acid was used as a coupling agent. The strength increase is due to improved adhesion between the fiber and matrix, while improved modulus is due to the removal of lignin and hemicellulose that are not as stiff as cellulose. Polarized optical microscopy showed the presence of well-defined polymer crystals on the surface of the modified wood, and this is also responsible for the improved mechanical properties. It is conclusively demonstrated that the combination of chemical treatment of wood and ultrasound assistance is more effective in improving the mechanical properties of the composites than the use of chemical treatment alone.