骨刺成了年轻人的病

"骨刺"是个俗称,是骨质增生的一种表现,随着年龄的增长,骨头与软组织接壤处因长期承受压力、磨损等,出现退行性改变,从而导致骨质增生,形成骨刺。骨刺一般好发于活动频繁的关节,如颈椎、腰椎、膝关节、脚跟、手指、手肘等部位。骨刺压迫到附近的神经或脊髓时,就会出现身体     

手持式桉树幼苗种植器动杆疲劳分析

手持式桉树幼苗种植器是一种简易的苗木种植辅助工具,在林地面积较小、林地为山地时,由于常常不适宜使用大型机械化作业,此时有广泛实用价值。本研究针对自行设计的手持式桉树幼苗种植器动杆部分使用SolidWorks软件进行三维实体建模并导入Ansys-Workbench软件开展有限元静力学分析,在此基础上进行疲劳分析,找出其薄弱区域和寿命曲线,通过分析得出最大破坏应力为3.677 2×108Pa,最小安全因子仅为0.260 47,100%载荷条件下循环寿命约为5 000次,各指标的限制因素均出现在焊接部位。     

应拉木胶质层解剖结构及化学主成分结构特征

树木为了保持树干笔直或使树枝恢复到正常位置而产生生长应力,树木中具有这种应力的部位被称之为应力木。在天然阔叶林中,树木发生倾斜、弯曲和偏冠时,树干和枝条的上方受拉伸应力,受拉部位的木质部即为应拉木。然而在人工林速生树种的垂直树干中,也大量存在应拉木,但其结构、性质与正常材差异很大,给木材加工利用带来了一系列问题。与正常木相比,应拉木纤维细胞壁结构差异很大,特别是其纤维腔壁内表面常具有特殊形态和化学组成的壁层——胶质层,该壁层具有纤维素含量高、结晶度大、木质素含量低、微纤丝角小和纳米孔隙丰富等特征。因胶质层出现与应拉木中高拉伸应力的产生直接相关,当胶质纤维集中时,木材在干燥和加工利用过程中易产生扭曲、开裂、夹锯和板面起毛等一系列问题,严重制约优质人工林的培育和木材的合理加工利用,造成了大量经济损失。因此,深入了解应拉木与正常木在结构和功能上的差异,特别是应拉木胶质层的特殊结构、化学成分与其生物学功能间的内在联系是深入探究应拉木高拉伸应力产生机制的关键所在,同时也是木材学、植物学、树木生理学和材料学等学科领域研究的交叉前沿问题,对于减少因应拉木缺陷造成的损失、提高木材品质和利用率具有重要的理论意义和实际价值。本文对应拉木胶质层解剖结构及化学主成分结构领域的主要研究现状进行归纳,尤其对胶质纤维在应拉木中的分布特征、胶质层的解剖结构、孔隙结构和化学主成分等方面的最新研究做了详细介绍,旨在剖析应拉木胶质层的结构和特性及其在应拉木形成过程中的作用,为探究应拉木高拉伸应力形成机制提供基础数据。针对我国人工林普遍存在的应力木比例高、材质不均匀等特点,当前学术界和工业界亟需解决的是主要人工林树种中易形成应拉木的树种比率、应拉木中具有胶质纤维的树种比率及应拉木的形成原因等科学问题,今后可从应拉木形成和发育的调控机制、胶质层结构和性质的动态变化、胶质层的多尺度结构表征及对缺失胶质层应拉木的分析等方面开展进一步研究,最终为高效高值利用我国现有人工林资源提供理论依据。     

以玉米为例探究单子叶植物重力响应及维管结构的变化

【目的】重力对植物生长发育、形态建成、生理代谢等生物学过程发挥着重大作用,重力条件改变会诱导植物发生一系列生长与定向的变化。大部分木本植物在响应重力条件改变时,形成层活动会不均衡增加从而形成偏心生长的应力木,木质部结构和细胞壁成分发生明显变化。单子叶植物一般没有形成层,不能进行径向次生生长,且维管束多为散生。为了探究单子叶植物对重力的响应过程和结构变化,本文以玉米为研究对象,分析其响应重力的动态过程和形态结构变化;并通过与木本植物进行比较,揭示它们重力响应的差异。为进一步研究单子叶植物(如竹子等)及其他林木的重力反应提供一定借鉴。【方法】以玉米B73自交系为试验材料,待幼苗发育至10叶期,将试验植株水平放倒,对照植株保持直立。利用延时拍摄记录玉米重力响应过程的动态变化及变化的时间节点。通过组织切片观察和特异染色,分析发生重力响应的茎节产生的结构及细胞壁成分的变化。【结果】以第1片旗叶着生的节作为第1茎节,从下往上依次标记茎节。重力改变后玉米的响应过程及变化如下:1)响应过程:玉米从顶端向下依次感应重力作用。植株放倒10 h后开始响应重力,在之后的20 h内,植株从顶端到第4茎节先后向上弯起,直至植株与水平面呈90°角到达终止状态。2)形态变化:多次重复试验显示只有第4、5、6茎节发生明显的形态变化,在靠近节的近地侧部位出现不同程度的组织膨大。通过纵切观察,3个茎节膨大部位的组织和内部导管呈向上弯曲的状态。对照植株相应茎节并未发生改变。3)维管束结构变化:与对照相比,近地侧维管束的细胞数量增多并呈纺锤形,细胞壁极显著变薄且没有明显的导管组织;远地侧维管束的细胞数量和细胞壁厚度因生长状态不同而变化不一。第4茎节变化最显著。4)维管束细胞壁成分变化:分别用木质素特异染料间苯三酚和纤维素染料卡尔科弗卢尔荧光增白剂(calcofluor white)对试验组和对照组的横切切片进行染色,结果显示:近地侧维管束细胞壁的木质素含量较少,而纤维素含量比对照增多;远地侧维管束细胞壁成分与对照相比没有明显变化。【结论】玉米在重力条件改变后迅速调整茎节延伸方向,与对照相比茎节近地侧维管束细胞数量显著增多、细胞壁变薄、木质素减少而纤维素增多。由此推测玉米受重力影响后,通过调整居间分生组织活动,产生类似应拉木、压缩木的组织,但又与二者有所区别。这可为研究重力响应下木本植物维管组织分化(木材形成)的调控提供一定基础。     

绣球花扦插水培研究

【目的】为探讨水培条件对绣球花外植体生根的影响,丰富和发展绣球花的繁育技术。【方法】以当年生的绣球花枝条为材料,通过测定平均生根率、平均每株根长、平均生根时间、平均每株生根数等指标系统研究了激素种类、激素浓度和插条部位对绣球花水培生根的影响。【结果】在水培条件下,绣球花插条15 d左右开始生根。无菌水和NAA处理的插条的平均每株生根数量和平均每株根长优于IBA处理的插条。低NAA浓度可以促进插条生根,但差异不显著,但当NAA浓度超过15 mg·L~(-1)时,浸水部分的外植体表皮颜色明显变红,插条的平均每株生根数量和平均每株根长显著下降。插条类型对生根率、生根数量和根长具有显著影响,低浓度时(0和5 mg·L~(-1)),插条的平均生根率由高到低排序为上段插条中段插条下段插条,插条的平均生根率高达98.0%以上;当浓度为10 mg·L~(-1)时,中段插条的平均生根率和平均每株根长都显著高于上段和下段插条,适当提高激素浓度可以显著提高木质化插条的平均生根率。对比绣球花插条的生根部位发现,绣球花水培的生根方式为皮生根,上段插条浸入溶液中的部分均可以生根,而中段和下段插条的生根部位主要集中在节间附近,可能是由于上段插条木质化程度低,插条的分生组织活跃,而中段和下段插条木质化程度高,节间周围的分生组织活跃。【结论】激素种类、激素浓度和插条类型对绣球花水培苗的繁育具有显著影响,低浓度可以促进插条生根,但高浓度具有抑制作用。以中段插条为材料,在NAA浓度为10 mg·L~(-1)条件下,插条不但生根率高,而且根系发达,可以繁育出高质量的绣球花水培苗。     

A biomechanical analysis of industrial forest plantation workers in East Kalimantan

The objectives of this study are to clarify physiological work loads and physical loads acting on the lumbar region of workers and to propose a safe work environment in tropical forestry operations. The research was conducted in the industrial forest plantations of East Kalimantan, Indonesia, in 1996. In this study, heart rates and the physical lumbar burden of industrial forest plantation workers were measured for three types of work, that is, weeding, planting and path clearing. In addition, the load moment at the L₅/S₁ and the disc compression force were calculated using low-back biomechanical models. As a result, compression forces at the L₅/S₁ disc during weeding, planting and path clearing were estimated and found to be below the Action Limit (AL) by National Institute for Occupational Safety and Health (NIOSH). However, it was also found that some work posture types during path clearing by chain saw were sometimes above the AL. A part of this paper was orally presented at the 108th Annual Meeting of the Japanese Forestry Society (1997).     

Antifungal potential of Indian medicinal plants

Fourteen Indian plants, selected based on their use in respiratory and other disorders in traditional systems of medicine, were analyzed for their potential activity against fungi. The antifungal activity was investigated by disc diffusion, microbroth dilution and percent spore germination inhibition tests against pathogenic Aspergilli. Methanolic extracts of Solanum xanthocarpum and Datura metel inhibited the growth of Aspergillus fumigatus, A. flavus and A. niger and their in vitro MICs were found to be 1.25-2.50 mg/ml by both microbroth dilution and percent spore germination assays. In disc diffusion assay, a concentration of 0.062 mg/disc of methanol extract of D. metel showed significant activity against Aspergilli. S. xanthocarpum exhibited similar activity at 0.125 mg/disc.     

Indications that site preparation increases forest ecosystem carbon stocks in the long term

Mechanical site preparation (MSP) causes a mixing disturbance of the soil, which may increase decomposition of soil organic matter and subsequent carbon (C) dioxide emissions to the atmosphere. MSP also promotes the establishment and growth of tree seedlings, and hence ecosystem C fixation. However, there are uncertainties regarding the net effects of MSP on C stocks at the ecosystem scale. To assess decennial effects of MSP on ecosystem C stocks, C stocks in soil, ground vegetation and trees at three experimental forest sites with Pinus contorta, Pinus sylvestris and Picea abies in Sweden were sampled and measured for ca. 25 years in a control and after three MSP treatments: disc trenching, mounding and ploughing. After 25 years, all of the MSP treatments resulted in larger ecosystem C stocks than the control treatment due to positive effects on the tree biomass C stock. The tree C stock was highest after ploughing, intermediate after mounding or disc trenching and lowest in untreated control plots at all experimental sites. The MSP treatments did not affect the soil C stocks down to 30?cm. We recommend mounding or disc trenching to promote C sequestration as they disturb sites’ ecological, aesthetic and recreational values less than ploughing.     

Antibacterial activity of Bergenia ciliata rhizome.

The methanol extract of Bergenia ciliata (tested at 200--1000 microg/disc) showed a wide spectrum of concentration-dependent antibacterial activity.     

微米木纤维腰椎靠背的模压试验

试验给出了腰椎靠背的数学模型，设计了微米木纤维腰椎靠背模具，描述了腰椎靠背制造的关键工艺流程，并对模压腰椎靠背的密度和强度进行了试验分析，为其在生产实际中的进一步推广奠定了基础。     

Evaluation of antitumor activity of some medicinal plants of Bangladesh by potato disk bioassay.

The antitumor activity of the ethanolic extracts of 12 medicinal plants of Bangladesh, including the vincristine-vinblastine producing Catharanthus roseus was studied using the potato disk bioassay technique. Among these, 10 plant extracts at 25.0-microgram/disc exhibited significant inhibition of crown gall tumors caused by Agrobacterium tumefaciens.     

Modelling dead wood islands in European beech forests: how much and how reliably would they provide dead wood?

Dead wood is an important element of forests both for biodiversity and ecosystem functions. Due to intensive silviculture, however, dead wood usually is strongly underrepresented in European forests. Forest reserves cannot fully compensate for this because they comprise only a small proportion of forested areas and are often isolated. Retaining a certain number of dead trees in managed forests is important, but may cause safety problems for lumbermen and visitors and still does not necessarily lead to an amount and incidence (i.e., probability of occurrence) of dead wood that might be required for many species and certain ecosystem functions. Our studies concentrate on a third and complimentary dead wood management strategy: dead wood islands, i.e. small unmanaged islands distributed throughout managed forests. As an example, we focus on European beech forests (Fagus sylvatica). An important question related to this strategy is: how do amount, quality, and incidence of dead wood depend on the island’s size? To provide an answer, we use the spatially explicit, rule-based simulation model BEFORE-CWD that was developed to analyse dead wood dynamics in natural beech forests. This model and its predecessor, BEFORE, are well-verified and validated. They reproduce a suite of observed patterns and generate valid secondary and independent predictions. We found that islands that are too small, i.e. smaller than 0.33 and 0.08 ha for standing and lying dead wood, respectively, can fail to provide dead wood for several decades. The shape of the islands has only a minor effect. Extreme storm events temporarily increase and then decrease the amount of standing dead wood. In terms of the amount and incidence of dead wood, it makes no difference if one big or several small islands are set aside from management, unless the islands are not too small. We conclude that even relatively small unmanaged islands within managed forests can reliably provide dead wood and therefore should be considered as a management option. Our results can be used, for example by using metapopulation models of species of interest, to develop management plans for creating networks of dead wood islands.     

Behavioural responses of Frankliniella occidentalis Pergande larvae to methyl jasmonate and cis-jasmone

The larval stages of Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) cause more direct feeding damage to plants than the adults. We, therefore, investigated the behaviour-modifying effects on second instar larvae of two jasmonic acid derivatives. The artificial application of methyl jasmonate and cis-jasmone, both at 1 % concentration, deterred the larvae from settling in a dual choice bean leaf disc assay. We observed a dose-dependent feeding deterrence of both jasmonates and calculated the concentration required to reduce the feeding damage by 50 % relative to the control treatment (FDC₅₀) for each jasmonate. The feeding damage was reduced by the application of cis-jasmone at 1 % concentration, but not by the jasmonates at the respective FDC₅₀ in no-choice leaf disc bioassays. However, significantly more larvae left jasmonate-treated whole potted bean plants by migrating to the soil compared with control plants. Our results may be exploited extending behavioural manipulation by using plant compounds in thrips control programmes to the full lifecycle of the pest. Plant compounds could be used in integrated and biological pest management strategies against F. occidentalis in combination with the application of various above and below ground control measures.     

杉木地膜覆盖除萌技术研究

杉木根际萌蘖条是影响杉木高生长的关键.采用简便易行的地膜覆盖除萌法,抑制了萌蘖条的蔓延,促进了杉木生长.     

木材密度曲线的分形分析

本文对银杏（Ｇｉｎｋｇｏ ｂｉｌｏｂａ Ｌ．）ｘ射线木材密度曲线分形分析,结果表明,银杏木材密度的分形维数约在１．４４３０。分形维数直观地反映了木材密度年轮内和年轮间的变化规律,与年轮宽度有一定的联系,与木材密度本身关系不大。木材密度的分形维数一般由遗传因素控制,不同树种木材分形维数是相对固定的。木质材料的分形研究,是揭示其内在规律的有效方法。