熏蒸处理对落叶松木材颜色和力学强度的影响

为研究熏蒸处理对木材颜色和力学性能的影响,采用氧硫化碳(COS)、溴甲烷(MB)和硫酰氟(SF)分别在3种不同质量浓度下对落叶松材进行熏蒸处理,用色差分析、力学性能测试、电子扫描电镜(SEM)、能谱分析(EDS)和红外光谱分析(FTIR)对熏蒸前后木材的物理力学性能和官能团变化进行表征。结果发现:1)使用3种熏蒸剂处理后,落叶松材的颜色均发生明显变化,其中COS熏蒸处理对试样的明度(L*)、红绿轴色度指数(a*)的影响最小;2)落叶松材经过COS熏蒸处理后,顺纹抗压强度、静曲强度、弹性模量均下降,其中顺纹抗压强度下降最明显,在熏蒸剂质量浓度为124.2 g/m3时,顺纹抗压强度下降幅度达13.09%,而静曲强度和弹性模量分别下降9.38%、8.66%;经MB、SF熏蒸处理后,试样的顺纹抗压强度、静曲强度、弹性模量均无明显变化;3)熏蒸后的落叶松材表面微观结构未发生明显变化,但COS熏蒸后木材表面的S元素和SF熏蒸后木材表面的F元素分布密度均有所增加;4)在落叶松红外光谱图中,经MB、SF熏蒸后,碳氧双键和碳氢键明显增多;COS熏蒸后,半纤维素上的碳氧双键伸缩振动减弱,芳香环骨架上的碳氧双键的伸缩振动加强,木质素相对含量增加。      

不同种植年限苏打盐碱型水稻土水溶性有机物三维荧光光谱特征分析

【目的】揭示不同种植年限苏打盐碱型水稻土水溶性有机物(WEOM)的变化规律,为苏打盐碱型水稻土固定有机碳提供理论基础。【方法】利用三维荧光光谱技术研究种植水稻0、1、3、5、15和20年对苏打盐碱地土壤中WEOM含量(w)及其三维荧光特性的影响。【结果】随种植年限的延长,土壤WEOM的含量先增加后逐渐降低,在种植3年时达最大(259.29 mg·kg-1),而在20年时最小(19.29 mg·kg-1);土壤中WEOM D254 nm随种植年限增加而增加;WEOM的三维荧光图谱形状和荧光线密度不同,荧光线密度随种植年限的增加而增强;随种植年限增加,水稻土中区域Ⅰ和区域Ⅱ的荧光峰的发射光波长发生了蓝移,而区域Ⅲ和区域Ⅴ发射光波长发生了红移;土壤积分值为区域Ⅴ区域Ⅲ区域Ⅳ区域Ⅱ区域Ⅰ;种植20年后,类腐殖物质占WEOM的百分比降低。【结论】苏打盐碱型水稻土中类富里酸、类腐殖物质以及含有不饱和双键的芳香族化合物含量随种植年限而增加。三维荧光技术适用于研究土壤中WEOM的结构和组分。     

基于红外特征光谱的初榨椰子油掺假检测技术研究

根据不同油脂的红外光谱特性,建立偏最小二乘法(PLS)和反向传递神经网络(BP-ANN)判别分析模型,进行初榨椰子油中大豆油、玉米油、葵花籽油的掺假检测分析。结果发现,PLS和BP-ANN模型均具有较好的掺假检测分析能力,其中BP-ANN模型的分析效果最佳,其对初榨椰子油中大豆油、玉米油、葵花籽油进行掺假检测的准确率均达到了99.67%以上,该方法可用来进行初榨椰子油的掺假分析,具有分辨率高、快速、简便等特点。     

Effect of acetylation on the chemical composition of hornbeam (Carpinus betulus L.) in relation with the physical and mechanical properties

Common hornbeam (Carpinus betulus L.) is a highly underused wood species despite its great hardness, strength, wear-resistance and toughness. It is mainly used as firewood in Hungary because of its wood defects, irregular shape and low-dimensional stability. These wood defects and small breast height diameter result in a low yield. It is non-durable outdoors as it tends to turn grey, crack and be attacked by wood-decaying organisms. Indoors it lasts for hundreds of years. One technology that could improve the stability and durability properties is acetylation. Hornbeam was acetylated with the Accoya® method under industrial conditions. The aim of this research was the assessment of acetylation affecting the chemical properties of hornbeam wood and how these are related to the change in physical and mechanical properties. Main wood constituents (cellulose, hemicellulose, Klason lignin, extractives and ash content) were determined and compared. Chemical parameters related to the degradation of structural polymers were also evaluated (total phenolic and soluble carbohydrate contents, pH and buffering capacity, furfural, levulinic acid, formic acid, acetic acid). Structural changes in acetylated wood and in the Klason lignin fraction were also assessed using FTIR spectroscopy.     

Leaf structure and chemical compositions are correlated with cotton boron efficiency

In this study, in order to investigate the boron (B) efficiency and response to changes in leaves structure and chemical compositions correlated with B efficiency, two different cotton genotypes including genotype 103 and genotype 122 were treated by B-deficiency (0 mg L^?1) or moderate B (0.2 mg L^?1). All the seedlings were grown in hydroponics situation with modified Hoagland and Arnon solution under greenhouse conditions for 6 weeks. The changes in chemical compositions and cell structure of leaves as a consequence of B deficiency were revealed by Fourier-transform infrared spectroscopy (FTIR), ¹³C nuclear magnetic resonance (¹³C-NMR) and transmission electron microscope (TEM). The results showed that the leaves of genotype 122 appeared crinkled and prolapsed having more obvious symptoms than genotype 103. Besides, the dry mass of every part was higher while B concentration was lower in genotype 103, indicating that genotype 103 was much tolerant to low B, which was related to higher B utilization efficiency of genotype 103 under B-deprived condition. In addition, B deficiency stunted the synthesis of proteins, carbohydrates, cellulose and lignin, which is noticed more seriously in leaves of genotype 122, and the structure and integrity of cells were significantly destroyed by B starvation. These results indicated that genotype 103 had higher B efficiency than genotype 122, and the changes in the chemical composition and cell structure might be either specific or adaptive responses to B efficiency.     

Droplet spectra and high-speed wind tunnel evaluation of air induction nozzles

A series of air induction nozzles were tested in a high-speed wind tunnel. Droplet size spectra were measured for four air induction nozzles (IDK-120-01, IDK-120-02, IDK-120-03 and IDK-120-04) each at three spray pressures (0.3, 0.4 and 0.5 MPa) and seven different air velocities (121.7, 153.4, 185.5, 218.4, 253.5, 277.5 and 305.5 km·h⁻¹). The measurement distance (0.15, 0.25 and 0.35 m) from the nozzle orifice was found to be important for the atomization of the droplets. The response surface method was used to analyze the experimental data. The results indicated that Dv_0.1 and Dv_0.5 of the droplets decreased quasi-linearly with increased wind speed, while Dv_0.9 was affected by the quadratic of wind speed. Dv_0.1, Dv_0.5 and Dv_0.9 of the droplets were all proportional to the orifice size, and were not markedly influenced by the spray pressure. The percentage of the spray volume consisting of droplets with a diameter below 100 mm (%<100 mm) was found to be quadratically related to wind speed, and was not markedly influenced by the spray pressure and orifice size. However, the effect of the orifice size on the %< 200 mm could not be ignored.     

Will the Conventional Soil-Plant Analysis Pass into Oblivion? Rapid and Low-Cost Determination Using Spectroscopy

Is it time for replacing the traditional soil-plant analysis methods by spectroscopy? Traditional analytical methods are subject to significant sources of errors that commonly result in compromise of soil characteristics and gross underestimation of chemical concentrations in soil-plant for a wide range of analyses. Given the magnitude of the decisions that are made based on these data, the technical and economic impacts of using traditional methods can be significant. Therefore, it is now time for soil-plant spectroscopy to enter an operational phase. Spectroscopy has opened a new era in which traditional analyses are being left behind. Spectroscopy can be used to accurately predict certain soil and plant properties, making it a valuable tool in precision farming. Soil spectra contain much information relevant to soil-plant properties. Multivariate regressions of spectra can accurately predict several soil properties. Spectroscopy requires only a few seconds to analyze a soil sample, but the relevant information needs to be mathematically extracted from the spectra so that it can be correlated with soil properties. Therefore, the successful application of spectroscopy to quantify and evaluate the relationships between soil reflectance and soil properties depends largely on the development of accurate and robust calibration models. These procedures appear to be sufficiently accurate and precise to enable their use in soil and plant analysis. There are many advantages to using this technique.     

两种光敏化合物光诱导稗草细胞产氧自由基电子自旋共振的检测与分析

采用电子自旋共振光谱仪,检测两种光敏化合物α-三连噻吩(α-T)和1-苯基-4-(3,4-亚甲基二氧)苯基-丁二炔(简称化合物5)处理的稗草愈伤组织后,经近紫外光光照与非光照处理,诱导细胞内产氧自由基的总量.试验结果表明:两种光敏化合物在1mg/L的浓度下,光照组与非光照组愈伤组织产氧自由基的总量存在显著差异,α-T处理的光照与非光照电子自旋共振图谱氧自由基积分面积与愈伤组织量的比值分别是54.58和46.78mm2/mg;化合物5的氧自由基积分面积与愈伤组织量的比值分别是68.62和53.98mm2/mg.而两种光敏化合物处理的非光照组与空白对照处理的光照组与非光照组所诱导的氧自由基总量不存在显著差异.表明两种光敏化合物对稗草生长的光活化抑制作用与光活化Ⅰ型机制有一定的关系.     

基于高光谱数据的高羊茅SPAD快速估测研究

以不同生存环境下抽穗期的高羊茅(Festuca arundinacea Schreb.)为材料,测定叶片的光谱反射率和SPAD(soil plant analysis development,土壤-植物分析模式)值,采用相关、回归等多元统计方法分析叶片的SPAD值与光谱数据之间的关系;从光谱数据中提取红边参数、植被指数和微分光谱分别与SPAD值进行分析。结果表明:红边位置、NDVI和695~715 nm之间的平均微分光谱数据与SPAD值均具有很好的相关性,相关系数分别为0.906,0.842和0.826,建立的一元线性回归模型确定系数分别为0.820,0.709和0.681。高羊茅叶片的光谱特征与叶片中色素含量和叶肉细胞的结构密切相关,与其生存的环境条件无关;红边位置、NDVI和微分光谱均可以较好的反演SPAD值。相比而言,红边位置预测高羊茅叶片的SPAD值最为精确,NDVI次之,微分光谱最差。试验结果为利用高光谱遥感信息反演高羊茅抽穗期的叶绿素含量,进而分析其光合作用能力、碳代谢能力提供了理论依据。     

应用紫外指纹图谱分析技术鉴别白僵蚕

基于为白僵蚕的质量控制提供依据,研究了紫外指纹图谱技术在白僵蚕鉴别上的应用。将不同品种、不同季节的白僵蚕及健蚕的水溶性提取液、脂溶性提取液和醇溶性提取液用紫外分光光度法在200~400 nm波长范围内扫描,用白僵蚕的各提取液对小白鼠进行抗惊厥试验。结果表明,白僵蚕的醇溶性提取液的紫外指纹图谱可以对白僵蚕进行鉴别。