刨花蒸汽处理提高刨花板的尺寸稳定性

本研究探索用高压饱和蒸汽处理刨花来提高刨花板的尺寸稳定性。分别对云杉(Picea spp。)和桦木(Betula spp。)找出了不同的蒸汽压力和处理时间与刨花板的弹性模量、静曲强度、平面抗拉强度和线性膨胀率之间的关系,并得出结论:蒸汽处理刨花时较适宜的工艺条件为:蒸汽压力1.3N/mm~2左右,蒸汽处理时间5～6min;经蒸汽处理后桦木刨花板尺寸稳定性的改善程度优于云杉刨花板。     

用红外光谱分析刨花蒸汽处理后成分的变化

用红外光谱法分析了云杉和白桦刨化蒸汽处埋后成分的变化。红外谱图不出了蒸汽处埋后刨花中的半纤维素和羟基比未处理的减少了,这是蒸汽处理改善刨花板尺寸稳定性的主要原因。红外谱图还示出了在同样的蒸汽处理条件下,白桦中半纤维素和羟基的减少程度大于云杉的减少程度,因此蒸汽处理后白桦刨花板尺寸稳定性的改善程度大于云杉刨花板的改善程度。     

微波处理对稻草表面特性的影响

利用FEIXG型电子自旋共振波谱仪和Nicolet Nexus 670型傅立叶变换红外光谱仪(FTIR)研究了微波处理对稻草表面特性的影响。研究结果表明,经微波处理后的稻草表面自由基浓度显著增加,最高可以达到处理前自由基浓度的7倍左右。且随着处理时间的延长和微波强度的增加,稻草表面自由基浓度的增加幅度有所上升。经微波处理后,稻草外表面的化学成分(包括SiO2、羟基、木素和纤维素)变化都不明显,而稻草内表面SiO2略有减少,羟基显著增加,木素和纤维素也有一定变化。微波处理可以改善稻草内表面的特性,使之比外表面更具活性,有利于稻草与胶黏剂之间的交联。     

刨花和纤维蒸汽预处理对其模压制品性能的影响

用１．５５ＭＰａ的饱和蒸汽分别对刨花处理４分钟,对纤维处理２．５分钟后模压凸型刨花板和纤维板。试验表明,采用蒸汽预处理的刨花和纤维压制的凸型板,其尺寸稳定性大大提高,当酚醛树脂用量在２．５％￣７．５％之间时,随着树脂用量增加,凸型刨花板经冷水浸泡后的吸水厚度膨胀率降低,而线性膨胀率基本与树脂用量无关。     

预热处理对麦秆纤维板性能的影响

研究了麦秆在不同预热处理条件下，其纤维化学性质以及制得的中密度纤维板的性能，同时结合施胶量对不同预热处理麦秆纤维板性能的影响，探讨了在麦秆纤维/脲醛树脂胶中密度纤维板生产中施胶量对板性能影响的重要性。结果表明，采用预热温度为160℃左右、预热时间5～7min的处理条件获得的麦秆纤维在16%左右的施胶量时，可获得满足GB/T 11718-1999标准的麦秆纤维/脲醛树脂胶中密度纤维板。     

热处理和蒸汽处理对压缩杉木性能的影响北大核心

以压缩杉木为研究对象,采用热处理和蒸汽处理两种方法,在不同温度条件下(160、180℃和200℃)对其进行压缩变形固定处理,分析不同处理工艺条件对压缩杉木回复率、残余应力和力学性能的影响,并探究压缩杉木变形固定机理。结果表明:热处理和蒸汽处理都可以降低压缩杉木的回复率和残余应力。随着处理温度的升高、处理时间的延长,压缩杉木的水煮回复率和吸湿回复率均减小。与热处理相比,各温度条件下蒸汽处理的压缩杉木水煮回复率和吸湿回复率均较小。随着处理温度的升高和处理时间的延长,热处理和蒸汽处理均可减少残余应力。在相同处理温度和处理时间条件下,蒸汽处理对压缩杉木的残余应力有更好的消除效果。热处理和蒸汽处理对压缩杉木力学性能都有一定的削弱作用,特别当处理温度达到200℃时,力学性能下降幅度较大。热处理和蒸汽处理改变了压缩杉木中C元素和O元素含量,O/C值分别降低了5.88%和7.84%;不改变压缩杉木纤维素结晶区的晶胞构造,但相对结晶度分别减小了5%和3%。综合考量,对压缩杉木采用蒸汽处理(180℃)进行变形固定是较好的选择。     

生活垃圾高压蒸汽催化水解处理方法

目前，城市生活垃圾产量大、密度高，含水量高达40％～60％，且未实行分类收集。国外的垃圾处理设备对垃圾的特征有特殊的要求，不适于我国城市生活垃圾的处理。传统的填埋与焚烧技术，都会引起二次污染。比如：填埋方式，占用大量土地、破坏土壤结构、造成垃圾围城的现象；焚烧方式，投资大、技术不成熟。另外，堆肥处理只能降解有机物，无法处理塑料制品。     

蒸汽爆破处理对竹纤维的影响

以小径级毛竹为研究对象,研究了蒸汽爆破处理对制备竹纤维的影响.利用傅里叶红外光谱和扫描电镜对爆破处理前后竹纤维化学成分和纤维形态进行分析.结果表明:蒸汽爆破对竹纤维分离效果好,纤维直径减小,保压时间越长,纤维分散效果越好,柔软性越好.爆破处理能够有效促进纤维中半纤维素降解和木质素的分离,使溶出物颗粒覆盖在纤维表面.蒸汽爆破处理使得竹纤维比表面积增大,改善了竹纤维的形态结构.     

CHEMICAL AND PHYSICAL CHANGES OF STEAM TREATED WOOD CHIP

High dimensional stable particlcboards could be produced by usisng saturatedsteam treated wood chip at elevated pressures.Sample Particleboards were made from woodchip of Birch(Platyphylla).The component changes of steam treated wood chip were analysedby infrared.Infrared spectra demonstrated that the hemicelluloses in steam treated chip wereless than those in untreated chip.This is one of the main reasons why steam treatment could im-prove particlcboard stability.The free radical concentration of steam treated chip surfaces wasanalysed by ESR spectroscopy.The results showed that free radical concentration of treatedchip surface was higher than that of untreated chip surface.The glueyness of chip increased andparticlcboard resin content decreased.     

Impact of anthocyanin from Malva sylvestris on plasma lipids and free radical

The effects of anthocyanin fromMalva sylvestris on plasma lipids and free radical were investigated by Reagent Kit method and in vitro assay. High fat model was set up with albino rats that were fed with different dosages of anthocyanin fromMalva sylvestris (0.03 g·d⁻¹, 0.04 g·d⁻¹ and 0.05 g·d⁻¹). The results showed that the total cholesterol was decreased by 19.7% at an anthocyanin of 0.04 g·d⁻¹ and triglyceride was decreased by 34.4% at an anthocyanin of 0.05 g·d⁻¹. In vitro assay, some indexes of anthocyanin were measured including the capability of scavenging free radical, reducing force and the capability of anti-lipid peroxidation by orthophenanthroline Fe⁺² oxidation-reduction method. The results indicated that the clearance rate of free radical reached to 43.46% when the content of anthocyanin was 0.20 mg·mL⁻¹ and the inhibition ratio of lipid peroxidation reached 18.82% when the content was 0.5 mg·mL⁻¹. Therefore anthocyanin is a kind of natural and effective free radical remover and antioxidant and can prevent from the formation of the thrombus and reduced the emergence of the cardiovascular disease. Biography: Wang Zhen-yu (1957-), male, Prof. in Forestry College, Northeast Forestry University and Food Science Academy, Harbin Institute of Technology, Harbin, P.R. China. Responsible editor: Zhu Hong     

大花葵花色苷对血脂及自由基的影响

用大白鼠建立高脂模型,喂食不同剂量的大花葵花色苷(0.03 g-d-1, 0.04 g-d-1, 0.05 g-d-1)。结果表明:0.04 g-d-1 花色苷剂量可以使大白鼠总胆固醇下降19.7%,0.05 g-d-1的花色苷剂量可以使甘油三酯下降34.4%。通过体外试验,用邻二氮菲Fe2+氧化还原法进行自由基清除能力的测定,抗脂质过氧化的测定。发现当大花葵花色苷浓度为0.2 mg-mL-1时,对自由基的清除率可达43.46%;当浓度为0.5 mg-mL-1时,对脂质氧化的抑制率达18.82%。由此看出,花色苷是一种天然有效的自由基清除剂和抗氧化剂,可预防血栓的形成,有助于减少心脑血管疾病的发生。表3 图5 参16。     

Antioxidant and free radical scavenging activities of five moss species

Total phenolic content, reducing power, antioxidant and free radical scavenging activities of ethanol extracts of five mosses were determined in vitro. No correlation between the total phenolic content and antioxidant or scavenging activities was found.     

Antimicrobial and free radical scavenging activities of Teucrium montanum

The antimicrobial and free radical scavenging activities of petroleum ether, chloroform, ethyl acetate, n-butanol and water extracts of Teucrium montanum were investigated. Ethyl acetate, chloroform and n-butanol extracts expressed a wide range of inhibiting activity against both Gram (+) and Gram (-) bacteria. n-Butanol extract possessed potent DPPH free radical scavenging activity.     

Isolation and free radical scavenging activities of a novel biflavonoid from the shells of Camellia oleifera Abel.

Oil production from the seeds of Camellia oleifera Abel. causes a great waste of shells which contain a lot of bioactive components. The aim of this research was to isolate flavonoid from the shells of C. oleifera Abel. and evaluate its uses. The shells were extracted by 70% methanol, hydrolyzed by 2 M hydrochloric acid, and further crystallized in acetone, the corresponding yield of flavonoid was up to 2.1% (purity: 93.8%). The procedure is concise, quick and proper for industrial utilization of the shells. Flavonoid was identified as bimolecular kaempferol structure by UV, MS, ¹H NMR and ¹³C NMR spectra, which is a new biflavonoid and first found in C. oleifera Abel. It showed stronger scavenging activity of DPPH and ABTS radicals than kaempferol. MDA decreased, and SOD and GSH-Px activities increased significantly in serum (P < 0.01) and brain tissue (P < 0.05) of mice after intragastric administration of biflavonoid at 200 mg/kg/d for 30 d. Its effects in vivo are superior to vitamin C and similar to kaempferol. Thus biflavonoid can be used as a prospective antioxidant to protect brain cells against damage from free radicals.     

Manufacture of oriented board using mild steam treatment of plant fiber bundles

This study investigated the effects of mild steam treatment (0.1 MPa for 2 h) of natural bio-based fibers and orientation (0° and 90°) of those fibers in various fiberboards. Ramie bast, pineapple leaf, and sansevieria fiber bundles were used as materials. The composite fiberboards were prepared using phenol-formaldehyde (PF) resin. To investigate the effect of mild steam treatment on wettability, contact angles of PF resin to the fiber were measured. The mechanical properties of the boards were examined as well as their dimensional stability. The contact angle data showed that mild steam treatment was effective in improving the wettability of fibers. Unioriented steam-treated boards showed better performance of internal bond (IB), moduli of rupture (MOR) and elasticity (MOE), thickness swelling (TS), and water absorption (WA) than other boards. Unioriented steam-treated sansevieria board with longitudinal fiber direction showed higher average values of MOR (403 MPa), MOE (39.2 GPa), and IB (1.33 MPa) and lower values of TS (5.15%) and WA (8.68%) than other boards. The differences in the mechanical properties and dimensional stability of boards were found mainly due to the differences in the ratios of fiber fraction of the boards to the density of the fiber bundles.