Towards sustainable commercial moss harvest in the Pacific Northwest of North America

The Pacific Northwest is the main source of commercially harvested forest moss in North America, but management guidelines have only included this nontimber forest product for ca. 15 years and research on sustainable harvest practices is barely a decade old. This review summarizes the results of recent research, identifies future research needs, and proposes guidelines for the sustainable management of tree moss (a mixture of mosses and liverworts). The epiphytic species most affected by harvest are Isothecium myosuroides, Neckera douglasii, and Porella navicularis, but dozens of taxa are thought to be impacted. Harvest impacts include reductions in biomass and cover and changes in relative species composition, but it is too early to tell if the species composition will return to pre-harvest conditions. Biomass recovery is slow and estimated rotation periods are 15-25 years. Inventory estimates are still lacking, but harvestable quantities of epiphytic moss are most abundant in low elevation and riparian areas and absent in stands that are very dark and/or lack hardwood tree and shrub species (e.g., <70-year-old Douglas-fir (Pseudotsuga menziesii) plantations). Future research should focus on locating unimpacted reference sites and evaluating the ecosystem functions provided by harvestable moss mats, including the provision of habitat and nutrient and water cycling. Management recommendations include prohibiting commercial moss harvest in forests managed toward old-growth condition, obtaining region-specific estimates of resource inventory and recovery rates, and rotating areas open for moss harvest to allow sufficient recovery between harvest entries.     

调速给水泵组机械密封的改进设计

对4^1／4″T8BID型机械密封频繁泄漏、使用寿命过短问题进行了故障分析，发现主要是动静环材质组合不当和冷却方式不合理造成。通过选择适合的动静环材料和改进机械密封，使问题得以解决。     

江汉平原麦后移栽棉适宜施氮量研究

为探寻江汉平原棉区麦后移栽棉模式最适宜施氮量，以中棉所63为研究对象，于2018—2019年连续2年进行不同施氮量（0、90、180、270、360、450 kg·hm-2）的田间小区试验，研究施氮量对麦后移栽棉的生长、产量及氮肥利用率的影响。研究表明：随着施氮量的增加,棉株倒4叶SPAD值呈增加趋势，花铃期倒4叶SPAD值与施氮量呈极显著一元二次关系。以施氮量在270~360 kg·hm-2之间籽棉占整株干物质量比例较大，且氮素向生殖器官转移速率最大。施氮量360 kg·hm-2处理的棉花产量、氮肥表观利用率、氮肥贡献率均最高。采用线性加平台模型拟合得出麦后移栽棉适宜施氮量为318.75 kg·hm-2（2018年）、310.64 kg·hm-2（2019年）,产量潜力可达到4 463.58 kg·hm-2(2018年)、4 662.53 kg·hm-2（2019年）。综合棉花生长、产量、氮素迁移及利用的结果，推荐江汉平原麦后移栽棉适宜施氮量为310.64～318.75 kg·hm-2。     

界面相容剂对LLDPE/木纤维复合材料力学性能的影响

采用三步法合成了4种烷基磷酸羟甲基脒基脲，合成产率高。研究了烷基磷酸羟甲基脒基脲、硅烷偶联剂、聚乙烯醇(PVA)、苯丙乳液和马莱酸酐接枝聚乙烯界面相容剂对LLDPE-木纤维复合材料的力学性能的影响。实验结果表明，与低分子偶联剂(硅烷偶联剂)相比，烷基磷酸羟甲基脒基脲，特别是异辛基磷酸酯羟甲基脒基脲(C8P)，有较好的改善作用，但其效果不如高分子型界面改性剂马莱酸酐接枝聚乙烯的作用。     

豫南引种檫木木材物理力学性质的试验研究

为了檫木的推广,我们对豫南引种檫木木材的物理力学性质进行了试验分析,并与原产地檫木木材进行比较。结果表明,豫南引种檫木的木材物理力学性质指标与中心产区差别不大,其木材强度适中,加工性能好,可广泛用于建筑、船舶、交通运输、胶合板等工业领域。     

HSK工具系统的力学模型及其应用

在对HSK工具系统的结构进行分析的基础上，建立了HSK工具系统的力学模型。利用该模型，计算了许用承载，分析了实验结果，讨论了影响HSK工具系统精度、刚度的关键制造技术以及使用中应该注意的问题，提出了以动刚度特性确定HSK工具系统许用承载的观点。理论分析与实验结果的一致性表明建立的力学模型是合理的。     

Effect of Time of Harvest and Storage Conditions on Germination of Nutmeg (Myristica fragrans Houtt)

Nutmeg ( Myristica fragrans ) is a valuable tropical spice crop, which is not easily propagated vegetatively. As the seeds of this species lose viability soon after harvest, storage for research causes problems, especially due to the seasonality of production. Thus, a study evaluated the characteristics of nutmeg seeds, and the relationship between time of harvest, drying temperature, and storage condition on germinability. Seeds were picked at full maturity, full ripeness or were collected within 2 hours after falling from the tree. Seed moisture contents, germination characters and germination indices were determined soon after harvest. The freshly fallen seeds were used for the drying and storage due to their better germination characters and higher germination index.
Seed moisture contents were high in the seeds. These values decreased and germinability increased with increasing seed maturity. Germination percentages were lost at higher moisture contents at a faster rate when dried at higher temperatures. All seeds lost germinability at moisture contents below 45 % (dry wt basis) when dried at the selected temperatures. Germination of stored seed were maintained for a longer period of time when stored at 5 °C in sealed transparent polythene packs, in contrast to when stored at room temperature. The results suggest the recalcitrant nature of nutmeg seeds and present possible methods of storage for short period of time while maintaining some degree of germinability.     

亚麻鲜茎雨露沤制技术的初步研究

雨露麻以其生产方式简单,成本低,不污染环境而被广泛应用,但传统的雨露麻采用人工收获,在多雨季节里原茎保存困难,常发生霉烂。给工农业均造成损失。鲜茎雨露沤麻技术的提出解决了这一问题,同时使沤麻时间提前10天左右,亚麻收获就开始沤制,充分利用了亚麻收获季节的高温和降雨。沤麻速度快,沤麻时间缩短,降低了生产成本,麻率相对提高0.5-1个百分点,纤维强度增加1.2—2.7kg。此项技术对我国雨露麻的发展具有一定的指导意义。