Pyrolytic characteristics of burning residue of fire-retardant wood

In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood, a multifunctional fire-resistance test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood. Samples at different distances from the combustion surface were obtained and a thermogravimetric analysis (TG) was applied to test the prrolytic process of the burning residue in an atmosphere of nitrogen. The results showed that: 1) there was little difference between fire-retardant wood and its residue in the initial temperature of thermal degradation. The initial temperature of thermal degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample; 2) the temperature of the flame retardant in fire-retardant wood was 200°C in the differential thermogravimetry (DTG). The peak belonging to the flame retardant tended to dissipate during the time of burning; 3) for the burning residue of fire-retardant wood, the peak belonging to hemicellulose near 230°C in the DTG disappeared and there was a gentle shoulder from 210 to 240°C; 4) the temperature of the main peaks of the fire-retardant wood and its burning residue in DTG was 100°C lower than that of the untreated wood and its burning residue. The rate of weight loss also decreased sharply; 5) the residual weight of fire-retardant wood at 600°C clearly increased compared with that of untreated wood. Residual weight of the burning residue increased markedly as the heating temperature increased when burning; 6) there was a considerable difference with respect to the thermal degradation temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 133–138 [译自: 北京林业大学学报]     

不同乳酸菌亚油酸异构酶酶学性质的比较

对不同乳酸菌菌种中提取出的亚油酸异构酶进行了酶学性质的比较。结果表明,嗜酸乳杆菌CGMCC1.1854亚油酸异构酶的最适p H为6.5,最适温度为30℃,以亚油酸为底物时酶的米氏常数Km为18.99mmo L·L-1,Vmax为1.58μg·m L-1·min-1;植物乳杆菌CGMCC 1.557亚油酸异构酶的最适p H为6.5,最适温度为45℃,以亚油酸为底物时酶的米氏常数Km为14.83 mmo L·L-1,Vmax为1.75μg·m L-1·min-1;植物乳杆菌3-9亚油酸异构酶的最适p H为6.5,最适温度为45℃,以亚油酸为底物时酶的米氏常数Km为14.26 mmo L·L-1,Vmax为1.94μg·m L-1·min-1。     

Properties of Compound Systems of Paraffin Wax Emulsion and Copper Azole and Treated Wood

[目的]木材的防腐与防水,是木材保护的重要方面,它对延长木材的使用寿命、拓宽其应用范围具有重要的意义。[方法]本研究以环保型防腐剂铜唑（CA）与石蜡乳液防水剂复合处理木材,并对复配体系的基本性能,包括稳定性（储存稳定性和离心稳定性）、粒径和pH值等,以及复配处理材的防水性（吸水性、干缩性及湿胀性）进行了考察。[结果及结论]研究发现：（1）CA与石蜡防水剂进行复配具有良好的混容性及稳定性,不同配比的复配体系其储存稳定性与离心稳定性均可达到1级水平,可存放较长时间不致出现破乳现象。（2） CA不能改善处理材的防水效果。但是,经 CA与石蜡防水剂复配体系处理的试材,其吸水性和尺寸稳定性均得到明显改善。     

An astronomical 2175 angstrom feature in interplanetary dust particles

The 2175 angstrom extinction feature is the strongest (visible-ultraviolet) spectral signature of dust in the interstellar medium. Forty years after its discovery, the origin of the feature and the nature of the carrier(s) remain controversial. Using a transmission electron microscope, we detected a 5.7-electron volt (2175 angstrom) feature in interstellar grains embedded within interplanetary dust particles (IDPs). The carriers are organic carbon and amorphous silicates that are abundant in IDPs and in the interstellar medium. These multiple carriers may explain the enigmatic invariant central wavelength and variable bandwidth of the astronomical 2175 angstrom feature.     

A Promising Potential of Brown Algae Sargassum polycystum as Irreversible Hydrocolloid Impression Material

This study aimed to investigate the potential use of brown algae Sargassum polycystum as irreversible hydrocolloid (alginate) impression material. Potassium alginate extracted from Sargassum polycystum was prepared in three different compositions (14%, 15%, and 16%) and mixed with other standard components to form an alginate impression material. Prior to that, the purity of potassium alginate was quantified with Fourier Transform Infrared Spectroscopy (FTIR) analysis. As a control material, the alginate impression material from a commercially available product was used. All alginate impression materials were then applied to a die stone model. Dimensional accuracy was measured by calculating the mesiodistal width of incisors in the generated dental cast using a digital caliper 0.01 accuracy (five replications). In addition, to evaluate the dimensional stability, the impression results were poured at four different periods (immediately, 5 min, 10 min, and 15 min). An independent t-test was performed to compare the measurement results with p < 0.05 considered significant. Analytical results confirm that the impression material containing 15% potassium alginate gives the best dimensional accuracy similar to control (p > 0.05). Meanwhile, the optimal dimensional stability was produced in the impression material containing 16% potassium alginate. Our study suggested that brown algae Sargassum polycystum has a promising potential to be used as an alginate impression material in clinical application.     

碱木质素与超支化聚丙烯酸酯乳液复配改性速生青杨的尺寸稳定性研究

【目的】为提升木质素对人工林速生材的尺寸稳定性,本研究提出利用碱木质素与超支化聚丙烯酸酯乳液(HBPA)对速生青杨复合改性的方法。【方法】通过在碱木质素中引入HBPA乳液,配制了质量分数1.31%的碱木质素与质量分数4.00%、8.00%的HBPA乳液的复配乳液(4HL、8HL组),然后分别将碱木质素、HBPA乳液和复配乳液浸渍处理速生青杨,基于改性材的质量增加率、增容率和扫描电镜探究浸渍效果;利用傅里叶变换衰减全反射红外光谱分析HBPA乳液的聚合情况以及改性材化学组分的变化;通过吸水、吸湿性试验对试材的尺寸稳定性进行评价;并对试材的顺纹抗压强度进行测试。【结果】微观上,随着乳液质量分数的增大,固化后黏附在细胞腔内的乳液越多,整体被改性剂填充的导管和木纤维的数量也相应增多。宏观上,随着乳液质量分数的增大,改性材的质量增加率和增容率也相应提高,复配乳液改性材的4HL组质量增加率和增容率分别为8.14%和3.14%,8HL组质量增加率和增容率为15.05%和3.36%,且复配乳液改性材的质量增加率大于碱木质素和HBPA乳液改性材的质量增加率之和;相对于未改性材,复配乳液改性材4HL组和8H...     

CA-B/新型石蜡乳液复配处理材的防霉性能研究

[目的]该研究基于天然表面活性剂开发出了石蜡防水剂与铜唑（CA-B型）防腐剂的复配体系,考察了复配体系处理材的防霉防蓝变性能。[方法]采用0.3%和0.5%2种浓度的CA-B和0.5%、1.0%、2.0%3种浓度的石蜡乳液制备复配体系,利用满细胞法浸注处理50 mm（L）×20 mm×5 mm的南方松（Pinus spp.）试材,根据国标GB/T18261-2000针对蓝变菌可可球二孢（Botryodiplodia theobromae Pat.）和霉菌黑曲霉（Aspergillus niger V.Tiegh）、绿色木霉（Trichoderma viride Pers.ex Fr.）对复配处理材进行抗蓝变和抗霉变试验。[结果]石蜡乳液和CA-B均能改善木材的抗霉变和抗蓝变效果,但在一定范围内,石蜡乳液浓度增加对抗霉变和抗蓝变效果略有负面影响。[结论]以期促进木质生物质资源的高附加值利用,推动行业向更高效、更环保的方向发展。     

吸湿过程中木材的含水率及温度变化

为了探讨木材在水分吸着过程中的含水率、温度的变化,以尺寸20 mm(T)×20 mm(R)×2 mm(L)的杨木(Populus euramericana Cv.)为试材,利用自行研制的恒温箱、配合红外热像仪,考察了在30℃,从绝干→22%、47%和75% RH 3种相对湿度条件下吸湿过程中试材的含水率、温度变化及其顺纹方向上的温度梯度分布情况。结果表明：在吸湿初期,试材含水率迅速上升,其整体平均温度也明显升高2~5.5℃;随着吸湿过程的进行,木材含水率和整体平均温度逐渐趋向平衡;在顺纹方向上,试材的温度呈现出表面温度高、中间温度低的分布形态,表层与芯层之间的温度差在吸湿过程初期90 s内达到最大值,约为0.8℃,当达到吸湿平衡时二者之间的温差约降至0.02℃。     

吸湿过程中脱化学成分木材的水分及尺寸变化

为了考察脱化学成分木材的水分吸着和变形行为,本研究以尺寸20mm(T)×20mm(R)×4mm(L)的杉木（Cunninghamia lanceolata Hook.）为试材,将未处理材及脱抽提物材、脱木质素材先后置于25℃、45%→60%→75%相对湿度的环境中达到吸湿平衡,在该过程中测量了试材含水率及弦、径向尺寸的变化情况。主要结论如下：各种试材的含水率和横向尺寸变化在吸湿初期快速增加,随着吸湿过程的进行,变化速率逐步降低并最终达到平衡状态;其中,脱木质素材的吸湿性最强,脱抽提物材次之,而未处理材的吸湿性最低;相比较于未处理材,杉木脱除抽提物后,弦、径向尺寸变化率有微小的上升,但对其横纹方向上变形各向异性的影响不大,而脱木质素材的弦、径向尺寸变化率明显增大,且横纹变形各向异性有所下降;各种试材无论在连续吸湿过程中还是达到吸湿平衡状态下,其含水率与弦、径向尺寸变化率均成近似线性关系;脱木质素材的水分吸着系数和湿度膨胀系数最大,脱抽提物材次之,未处理材最低。     

Impacts of Sletr1-1 and Sletr1-2 mutations on the hybrid seed quality of tomatoes

Shelf life is an important breeding trait in tomato, especially for the tomato production in subtropical and tropical regions. Previously we have isolated and characterized ethylene receptor mutants, Sletr1-1 and Sletr1-2 from mutant population based on Micro-Tom cultivar. Sletr1-1 showed insensitivity to ethylene while Sletr1-2 showed reduced sensitivity to ethylene. We also have demonstrated that the traits are useful for extending fruit shelf life of the hybrid tomato cultivars. For commercializing the hybrid cultivars, the seed quality is another important trait. In this study, we evaluated the effects of the Sletr1-1 and Sletr1-2 mutations on the seed quality characteristics of F_1 hybrid lines generated by crossing Sletr1-1 and Sletr1-2 with three commercial tomato cultivars, Intan, Mutiara and Ratna. Sletr1-1 mutation conferred insensitivity to ethylene in the F_1 hybrid seedlings, resulting in negative effects including reduced germination rate, vigor index and emergence speed index. Interestingly Sletr1-2 mutation had almost no effect on the seed quality characteristics of the F_1 hybrid lines, suggesting that Sletr1-2 was suitable for producing high quality of hybrid seeds.