Potential of the crude glycerol and citric acid mixture as a binder in medium-density fiberboard manufacturing

European Journal of Wood and Wood Products - Urea–formaldehyde (UF) resin is the main commercial adhesive used for medium-density fiberboard (MDF) manufacturing. UF resin is used to produce...     

Investigation of the interrelations between defibration conditions,fiber size and medium-density fiberboard (MDF) properties

Defibration conditions and raw material properties affect wood fiber characteristics, and thereby the properties of fiber-based panels such as high-density fiberboard (HDF), medium-density fiberboard (MDF) and wood fiber insulation board. This study investigates the influence of steaming conditions (time and temperature), grinding disc distance, wood species (pine, beech, birch and poplar), method of refiner discharging (radial and tangential stock outlet) and wood chip size on fiber length and fiber length distribution, and further the influence of fiber size on MDF properties. Fiber lengths were determined applying the recently developed image analysis-based fiber size measuring system FibreCube. This system enables an automated and nearly complete mechanical separation of woolly-felted fiber samples prior to image acquisition, software-supported post-separation of overlapped-lying fibers at the beginning of image analysis, and flow line tracing-based length measurement. It was found that grinding disc distance and wood species are the most influential parameters on fiber length characteristics. Especially the content of undefibrated fiber bundles (shives) was found to strongly correlate with the grinding disc distance. Wood anatomical differences between hardwood and softwood were reflected clearly by the fiber length characteristics. Fiber size was found to be one of the parameters influencing panel properties. However, other fiber characteristics—in particular the chemical nature of the fiber, which is responsible for its wettability with water (thickness swelling) and glue (mechanical properties)—have to be considered as important influencing parameters on panel properties.     

樟芝口服液的解酒护肝效果研究

本研究拟通过动物实验,探讨实验室自制樟芝口服液的解酒护肝效果。实验对比了不同组小鼠摄入樟芝口服液后,其醉酒耐受时间与醉酒时间,血清中谷丙转氨酶、谷草转氨酶水平及肝组织匀浆中乙醇脱氢酶、乙醛脱氢酶水平。结果表明,高剂量樟芝口服液能显著延长小鼠醉酒耐受时间,从14.1±5.2 min延长到27.9±7.9 min,缩短了醉酒时间,从230.0±22.3 min缩短至161.7±38.0 min,能显著降低因酒精损伤而导致血清中谷丙转氨酶和谷草转氨酶水平的升高,分别从56.34±9.60 U/L、69.57±11.88 U/L降低到42.35±12.29 U/L和51.86±15.04 U/L;同时提高了乙醇脱氢酶和乙醛脱氢酶活性,分别从6.21±1.91 U/mg prot、454.15±119.18 U/mg升高到9.82±3.36 U/mg prot和454.15±119.18 U/mg。说明实验室自制樟芝口服液具有一定的解酒护肝功效。     

Effects of recycled fiber content on the properties of medium density fiberboard

The large global production quantity of medium-density fiberboard (MDF) creates equal quantities of waste MDF, which consequently requires research on the recycling of MDF. This work was conducted to study the effect of recycled fiber (RF) content on the recycling properties of MDF. After pretreating waste MDF, a refiner and hammer were used to isolate refiner RFs (RRFs) and hammer mill RFs (HRFs) from two softwood species. This work also characterized the physical, chemical, and morphological features of RFs and virgin fibers (VFs). RRF and HRF contents of 0, 5, 10, 20, 30, 50, and 100% were used to fabricate recycled MDF (rMDF) panels. All RFs had shorter fiber lengths and higher fines contents than VFs had. The presence of N from urea–formaldehyde resins was confirmed by multiple analyses; more N was distributed in RFs than in VFs. The highest internal bonding (IB) strength of the rMDF occurred at 10% RF, regardless of isolation method and wood species; IB strength decreased afterward. The mechanical properties, including modulus of rupture, modulus of elasticity, and screw withdrawal resistance of rMDF, showed behaviors similar to the IB strength with increasing RF content. However, the thickness swelling, water absorption, and formaldehyde emission of rMDF samples decreased with increasing RF content. Statistical analysis indicates that the minimum of 10% RFs can be used to replace VFs without diminishing the properties of rMDF. The improved properties of rMDF were ascribed to the reinforcing effects of RFs covered with cured resins.     

不同发酵方式对樟芝真菌多糖产量的影响研究

通过深层发酵法,对比研究了连续、分批、补料分批3种培养方式对樟芝真菌菌体,胞内外多糖产量的影响,研究表明,补料分批相对于连续培养,菌体最大产量提高5.51%,胞内多糖最大产量提高11.25%。胞外多糖最大产量提高21.70%,补料分批培养优于连续培养和分批培养。     

低频交变磁场对樟芝液态发酵的影响

使用实验室自主研制的磁场设备,以樟芝为研究对象,以菌丝体生物量提高率为指标,通过单因素和正交优化试验,研究低频交变磁场对樟芝液态发酵的影响,确定最优磁场参数,并借助扫描电镜,对比常规液态发酵和磁场辅助液态发酵所得菌丝体的微观形态的差异。结果显示,当磁感应强度为80 Gs,磁处理初次介入时间为接种3 d后,每天磁处理时长为4 h时,磁场对樟芝菌丝体的生长促进作用最强。在此条件下,菌丝体生物量提高率为15.87%,多糖增长率为24.26%,总三萜增长率为26.85%。扫描电镜结果显示,磁场辅助樟芝液态发酵所得菌丝体比常规液态发酵菌丝体表面更加粗糙,结构更加松散,褶皱更为明显。实验结果表明,低频交变磁场辅助樟芝液态发酵可以提高其菌丝体生物量、多糖和三萜产量。     

pH和无机盐对樟芝液体发酵的影响

为探讨pH和无机盐对樟芝液体发酵的影响,设置了添加KH2PO4和不加KH2PO4条件下不同起始pH、不同无机盐对樟芝液体发酵的影响。结果表明,樟芝在中性偏酸性条件下生长较好,而在中性和碱性的条件下生长缓慢;在KH2PO4存在的条件下,樟芝生长较好。另外,樟芝对不同的无机盐离子有不同的需求:对钾盐需求量大,对钠盐、铁盐、镁盐和铜盐需求量少。所以,pH和无机盐对樟芝液体发酵有一定的影响。     

不同碳氮源对樟芝液体发酵的影响

研究了以不同碳氮源配制合成的液体培养基对樟芝(Antrodia camphorata)发酵的影响,通过单因素和正交试验并对培养基的参数进行了比较,确立了最佳的培养基条件。樟芝对碳源利用较广,其中以玉米粉效果最好,而对山芋粉和乳糖的利用较差;樟芝对氮源的利用具有差异性,其中对有机氮源的利用较无机氮源好,以硫酸铵 麸皮复合培养效果最佳,而对碳酸铵几乎不利用。结果表明,采用玉米粉4%、硫酸铵 麸皮1.5%、硫酸镁0.02%、磷酸二氢钾0.2%时,菌体发酵最好。     

Effects of weight average molecular mass of phenol-formaldehyde adhesives on medium density fiberboard performance

) of phenol-formaldehyde (PF) adhesives on the performance of medium density fiberboard (MDF). To obtain different PF resins, a series of PF resoles were prepared by blending low (LMW) and high (HMW) resins in different proportions. Six blending ratios of LMW:HMW were chosen: 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100. The prepared resins were characterized with size exclusion chromatography (SEC) for their determination and differential scanning calorimetery (DSC) for thermal cure kinetics. As the proportion of HMW was increased, and hence the viscosity of adhesives increased. The thermal curing kinetics of the blended resins obtained by DSC showed that total thermal energy (ΔH) and activation energy (Ea) of cure decreased with increasing resin as determined by SEC. Test result for a series of fiberboards prepared with the blended resins showed that the LMW:HMW blending ratio of 40:60 gave the highest internal bond (IB) strength. The optimum viscosity of PF resin was approximately 300 mPa.s. The maximum values of MOR and MOE were found at a blending ratio of 80:20 (LMW:HMW). The density profile indicated that MOR and MOE were influenced by the maximum density of the board surfaces while the IB correlated to the minimum density in the core regions of the board.

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牛樟芝对四氯化碳致大鼠慢性肝损伤的保护作用

本文研究了牛樟芝对四氯化碳(CCl_4)致大鼠慢性肝损伤的保护作用。将雄性SD大鼠随机分为6组:正常组、模型组、牛樟芝低(30 mg/kg)、中(60 mg/kg)、高(120 mg/kg)剂量组及秋水仙碱阳性对照组(0.1 mg/kg)。除正常组外,均腹腔注射50%CCl_4橄榄油溶液,1 mL/kg,2次/周,连续9周,建立慢性肝损伤模型,造模的同时,牛樟芝组及阳性组灌胃给相应药物,正常组和模型组灌胃给蒸馏水,每日1次,连续9周。处死大鼠,检测血清中ALT、AST活性;肝组织中SOD、MDA、GSH-Px及GSH;计算脏器指数;HE染色观察肝组织的病理变化。结果表明,与模型组相比,牛樟芝可明显改善肝脏病理变化,可显著降低CCl_4所致慢性肝损伤大鼠血清中ALT、AST活性(p0.01),同时高剂量组显著升高肝脏组织匀浆上清中SOD、GSH-Px活性、GSH含量,并显著降低MDA含量(p0.05,p0.01)。因此牛樟芝对CCl_4所致大鼠慢性肝损伤有明显的保护作用。     

嗜酸乳杆菌生物抗性的研究

选择一株嗜酸乳杆菌优良菌株为研究对象,用平板菌落计数法测定嗜酸乳杆菌在各因素的作用下的存活率来研究其耐酸、耐渗透压、耐胆盐能力以及模拟人体肠胃环境研究胃酸、食盐、胆盐对嗜酸乳杆菌的综合影响;从实验结果得出嗜酸乳杆菌具有一定的抗性能力。     

樟芝发酵产品的研究进展

樟芝是我国台湾地区特有的食药两用真菌,具有极高的研究和商业价值。然而目前对樟芝发酵产品特征代谢产物的研究不够,且缺乏规范的检测和质量评价标准,这对樟芝产品的开发及应用都极为不利。分析了樟芝人工培养方式的研究现状及产品开发存在的问题,提出了进一步的解决方法,并介绍了本课题组在相关方面取得的研究进展。     

Effects of steam explosion on the characteristics of windmill palm fiber and its application to fiberboard

Windmill palm fiber (WPF) obtained from the leaf sheath was treated by steam explosion under the pressure of 2.0 MPa for 120 s to modify and improve the properties of the panels manufactured with it. For comparison, an alkali treatment and acid treatment have also been used to treat WPF. Fiber analysis, scanning electron microscopy (SEM) observation, Fourier transform infrared spectroscopy (FTIR) and chemical composition analysis showed that after the steam explosion treatment: (1) the length, width and fine elements of the windmill palm fibrils were more influenced by the steam explosion treatment than by the other two treatments. (2) A great number of spinulose spherical silica bodies and waxy layers were observed on the surfaces of all the fibers except for the steam explosion treated windmill palm fiber (SEWPF) surfaces, and (3) the cellulose fraction correspondingly increased with the decrease of the hemicelluloses and lignin contents. Finally, the SEWPFs were used to produce fiberboards, and the modulus of rupture (MOR), internal bond (IB), water absorption (WA) and thickness swell (TS) of the fiberboards were measured. The results showed that the WA and TS of the fiberboards made of SEWPF decreased 22 and 32%, respectively, in relation to those made of WPF, whereas the IB increased 46%. It is suggested that steam explosion can be a feasible approach to modify WPF and expand its uses.     

乙醇提取樟芝菌粉三萜类化合物的动力学研究

以Fick扩散第二定律为基础,建立樟芝菌粉三萜提取过程的动力学方程,并由此推算出提取的速率常数、活化能、相对萃余率、半衰期,以及内扩散系数等动力学函数值.结果表明:所得提取模型能较好地描述樟芝菌粉三萜类化合物提取的动态过程.樟芝菌粉三萜类化合物提取过程的动力学符合一级动力学方程,为内扩散控制动力学.本研究可为樟芝三萜类化合物提取的工艺设计及操作条件的选择提供有价值的理论依据.     

樟芝深层液体发酵条件的试验研究

目的 研究提高樟芝菌丝体干重和胞内外多糖产量的方法 .方法 用二次通用旋转组合设计法,研究樟芝液体发酵条件中的温度、转速和接种量对菌丝体干重和胞内外多糖产量的影响.结果 与结论 胞内多糖总产量的最优参数组合为温度27℃、转速113 r/min、接种量21%;胞外多糖产量的最优参数组合为温度27℃、转速120 r/min,接种量22%,并通过试验验证了最优组合.     

樟芝多糖的超滤分离及其免疫活性研究

利用醇沉法和超滤法分离提取经发酵后的樟芝胞内胞外多糖,通过小鼠脾淋巴细胞转化增殖实验检测分离得到的各组分多糖的免疫活性。结果显示,经超滤分级处理后,樟芝胞内胞外多糖的总得率达18.18%,相对于乙醇沉淀法多糖得率提高了56.99%,显著的提高了樟芝胞内胞外多糖的得率;小鼠实验显示,利用超滤法获得的分子量大于1000 kD、100~1000 kD以及小于100 kD的六个樟芝多糖胞内胞外组分均能显著地促进小鼠脾淋巴细胞的转化增殖作用,表明,超滤法能显著提高发酵后樟芝胞内胞外多糖提取产量,其操作简单、易行,不损害多糖活性。     

经培养基优化所得牛樟芝及其功能饮料的护肝和降血糖作用

本文研究了经培养基优化所得牛樟芝微粉及其功能饮料对乙醇诱导的急性酒精肝损伤小鼠和链脲佐菌素(STZ)诱导的糖尿病小鼠的预防保护作用。结果表明:该牛樟芝微粉能有效降低急性酒精肝损伤小鼠血清中ALT、AST和MDA水平(p0.01),显著提高SOD、CAT和GSH-Px活性(p0.05或p0.01),发挥抗氧化作用而减轻肝脏损伤;同时该牛樟芝微粉及其功能饮料均能明显降低糖尿病小鼠的空腹血糖值、糖耐量以及血清中TG、TC和LDL含量,提高HDL含量(p0.05或p0.01)。进一步分析能量代谢信号通路,发现该牛樟芝微粉及其功能饮料可能通过下调肝脏中AMPKα和AKT磷酸化水平,进而发挥降血糖和改善血脂代谢的功效。因此,该经培养基优化所得牛樟芝微粉对小鼠酒精性肝损伤和糖尿病均有明显的预防保护作用,这可能是通过抗氧化应激、调控机体能量代谢相关因子的表达来实现,具备开发为解酒护肝降血糖功能饮料的前景。     

中密度纤维板砂光粉的粒径分布研究

应用光散射法测量MDF砂光粉的粒径分布.结果表明,MDF砂光粉粒径分布范围较广,但多数粉尘为粒径小于50μm的细微粉尘,其中粒径小于10μm的悬浮颗粒比重为16.10％,这对砂光除尘系统的除尘器清灰和吸口效率都提出了较高的要求.粗砂和精砂粉尘大小的显著差异可能是砂光粉粒径分布曲线上出现峰肩的原因.     

中纤板生产线后期堆垛自动立体仓库探讨

介绍分析了一种中密度纤维板生产线后期堆垛自动化立体仓库 (Lukki) 的结构组成、工作原理、自动控制系统和通讯系统的功能特征等,为全面自主设计开发中密度纤维板堆垛自动化立体仓库提供技术支持.