标准号: LY/T 2568.1-2015

摘要： 本部分规定了以汽油机为动力的手持式单筒双腔吹吸机的术语和定义、型号编制方 法、基本参数、技术要求及试验方法、检验规则、标志、使用说明书、包装、运输和贮存。 本部分适用于以汽油机为动力的手持式单筒双腔吹吸机(以下简称为吹吸机。

标准号: LY/T 2570-2015

摘要： 本标准规定了以汽油机为动力的随进式松土机（以下简称松土机)的术语和定义、型号编制方法、基本参数、技术要求及试验方法、检验规则、标志、使用说明书、包装、运输和贮运。 附录A列出了本标准涉及的应消除或降低危害程度的一些严重危险。 本标准适用于以功率不大于5 kW的小型通用汽油机为动力的松土机。

摘要： Rupture of biological cell membrane under mechanical stresses is critical for cell viability. It is triggered by local rearrangements of membrane molecules. We investigated the effects of stretching speed on mechanical rupture of phospholipid/cholesterol bilayers using unsteady molecular dynamics simulations. We focused on pore formation, the trigger of rupture, in a 40 mol% cholesterol-including bilayer. The unsteady stretching was modeled by proportional and temporal scaling of atom positions at stretching speeds from 0.025 to 30 m/s. The effects of the stretching speed on the critical areal strain, where the pore forms, is composed of two regimes. At low speeds (<1.0 m/s), the critical areal strain is insensitive to speed, whereas it significantly increases at higher speeds. Also, the strain is larger than that of a pure bilayer, regardless of the stretching speeds, which qualitatively agrees with available experimental data. Transient recovery of the cholesterol and phospholipid molecular orientations was evident at lower speeds, suggesting the formation of a stretch-induced interdigitated gel-like phase. However, this recovery was not confirmed at higher speeds or for the pure bilayer. The different responses of the molecular orientations may help explain the two regimes for the effect of stretching speed on pore formation.

关键词： Photosynthesis   Shoot density   Shoot composition   Maintenance layer   Photo-assimilates  

摘要： High labour costs and shortages and the cost of production has resulted in tea (Camellia sinensis (L) O. Kuntze) industries in central and southern Africa becoming unprofitable. This has led to the full mechanization of shoot harvesting, however, a reduction in yield has been observed with mechanical harvesting. It was hypothesized that the decline in yield as a result of mechanical harvesting is a result of the indiscriminate harvesting of shoots which leads to a change in sink/source and radiation interception dynamics within the canopy. As a result whole plant photosynthesis is impacted;which ultimately impacts tea bush productivity. Studies conducted at Tingamira estate, Chipinge, Zimbabwe showed significant yield differences between hand plucking and machine harvesting treatments, with higher yields under hand plucking across all seasons (43 945 kg green leaf ha(-1)) as compared to hand-held (35 114 kg green leaf ha(-1)) and ride-on machines (36 268 kg green leaf ha(-1)) (p <0.05). This reduction in yield was associated with a decrease in both the number and mass of desirable shoots over each season. The cause of this change was largely attributed to the indiscriminate removal of foliage by the machines which resulted in the proliferation of immature shoots, with an associated increase in sink strength and competition for available photo-assimilates. In addition, the depletion of the maintenance layer in mechanically harvested bushes, as indicated by reduced fractional interception of photosynthetically active radiation in the top 10 cm in these bushes and reduced photosynthetic rates in these bushes, suggests that these bushes were also source limited, as compared to hand plucked bushes. Therefore the changes in tea bush architecture, as a result of mechanical harvesting, resulted in changes in sink/source dynamics which led to a proliferation of immature shoots which competed for limited photo-assimilates. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Cardanol   Benzoxazine   Thermal polymerization   Curing kinetics   Cross link density  

摘要： To improve the crosslink density of bio-polybenzoxazines a series of cardanol-based benzoxazine monomers with different amine compounds (aniline, furfurylamine and 4,4'-methylenedianiline) were synthesized, cured and characterized. The epoxidation of aniline-cardanol-based benzoxazine was another approach to achieve a higher crosslink density of the resulting thermoset. The nuclear magnetic resonance and Fourier transform infrared spectroscopy were used to analyze the chemical structure and purity of synthesized benzoxazine monomers. The influence of different functionalization on the curing, thermal and viscoelastic properties of cardanol-based benzoxazines was studied systematically. The curing kinetics was studied by differential scanning calorimetry and by applying Kissinger, Flynn-Wall-Ozawa and Crane methods. Thermal and mechanical properties were investigated by differential scanning calorimetry and dynamic mechanical analysis. The introduction of additional polymerizable groups (oxazine, epoxy or furan ring) into benzoxazine molecule increased the activation energy and reaction enthalpy of curing. After curing, the crosslink density, glass transition temperature and storage modulus of functionalized thermosets were considerably enhanced, especially those of epoxidized cardanolaniline-based benzoxazine. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Chitosan   Gelling agents   Injectable hydrogel   Rheological properties   Mechanical resistance   Compression strength  

摘要： The use of injectable hydrogels is presently limited by the difficulty to achieve rapid gelation, high mechanical resistance and excellent cytocompatibility. In our study, high-strength injectable thermosensitive hydrogels of unmodified chitosan (CH) were obtained by combining sodium hydrogen carbonate (SHC) with phosphate buffer (PB) or beta-glycerophosphate (BGP) as gelling agents. A synergic effect led to the acceleration of gelation and a remarkable improvement of the storage modulus (G') of the hydrogels. Furthermore, the new hydrogels exhibited drastically enhanced Young moduli and resistance in compression as compared to conventional hydrogels prepared with BGP, PB or their combination. This was achieved while reducing the total salt concentration in the hydrogels. The gelation was rapid and the hydrogels presented porous structures and physiological pH, and did not show any cytotoxicity to L929 fibroblast cells in vitro. Overall, these new hydrogels provide interesting alternatives for use as blood vessel embolizing agents or as injectable scaffolds for drug delivery and/or cell seeding in tissue engineering strategies. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Dynamical systems   Hopf bifurcation   Biological networks   Spiking neuron models   Synaptic drives   Mean field models   Syncrhonization   Equipartition   Consciousness   General anesthesia  

摘要： With the advances in biochemistry, molecular biology, and neurochemistry there has been impressive progress in understanding the molecular properties of anesthetic agents. However, there has been little focus on how the molecular properties of anesthetic agents lead to the observed macroscopic property that defines the anesthetic state, that is, lack of responsiveness to noxious stimuli. In this paper, we use dynamical system theory to develop a mechanistic mean field model for neural activity to study the abrupt transition from consciousness to unconsciousness as the concentration of the anesthetic agent increases. The proposed synaptic drive firing-rate model predicts the conscious-unconscious transition as the applied anesthetic concentration increases, where excitatory neural activity is characterized by a Poincare-Andronov-Hopf bifurcation with the awake state transitioning to a stable limit cycle and then subsequently to an asymptotically stable unconscious equilibrium state. Furthermore, we address the more general question of synchronization and partial state equipartitioning of neural activity without mean field assumptions. This is done by focusing on a postulated subset of inhibitory neurons that are not themselves connected to other inhibitory neurons. Finally, several numerical experiments are presented to illustrate the different aspects of the proposed theory.

关键词： 舒芬太尼   瑞芬太尼   芬太尼   机械通气   血流动力学   镇痛   镇静  

摘要： 目的：比较芬太尼、舒芬太尼、瑞芬太尼对老年术后机械通气患者血流动力学的影响。方法采用前瞻性随机对照研究方法。选择2012年3月至2014年12月天津市第五中心医院重症医学科收治的外科术后老年患者60例，所有患者术后均给予机械通气和镇痛、镇静治疗，且因病情需要进行脉搏指示连续心排血量（PiCCO）监测。按随机数字表法将患者分为芬太尼组、舒芬太尼组和瑞芬太尼组，每组20例；分别持续静脉泵入芬太尼2μg·kg-1·min-1、舒芬太尼0.2μg·kg-1·min-1或瑞芬太尼2μg·kg-1·min-1维持镇痛治疗，并联合咪唑安定镇静治疗，维持各组患者Richmond躁动-镇静评分（RASS）-2～-3分；疼痛评估采用面部表情评分（FPS），以2分为最佳状态，根据患者评分情况调整镇痛、镇静药物泵入速度。观察3组患者用药前及用药后4、8、12、24、48 h时心率（HR）、平均动脉压（MAP）、心排血指数（CI）及胸腔内血容量指数（ITBVI）的变化。结果①3组患者用药后RASS、FPS均较用药前明显降低，且3组间差异均无统计学意义（均P＞0.05），说明3组均可达到满意的镇痛、镇静目标。②3组患者用药后HR、MAP、CI均较用药前明显降低；瑞芬太尼组用药后12、24、48 h HR（次/min）均较芬太尼组及舒芬太尼组减慢（12 h：70.6±4.8比73.9±6.8、74.5±7.2，24 h：69.2±7.0比75.2±6.6、75.7±5.8，48 h：68.9±5.4比74.5±6.3、76.5±5.7，均P＜0.05）；舒芬太尼组用药后各时间点MAP（mmHg，1 mmHg＝0.133 kPa）、 CI（mL·s-1·m-2）均明显高于芬太尼组和瑞芬太尼组（MAP 4 h：74.8±7.5比70.8±6.5、71.4±6.8，8 h：75.9±6.7比71.2±5.7、70.9±6.9，12 h：76.9±6.8比69.9±6.4、71.9±5.6，24 h：75.6±6.6比70.2±6.2、69.2±6.4，48 h：77.5±6.3比71.5±5.8、71.1±5.9；CI 4 h：73.0±8.8比67.5±6.5、63.5±5.5，8 h：72.2±7.8比63.4±4.8、64.2±5.7，12 h：71.5±7.3比65.5±5.2、67.0±6.0，24 h：72.7±7.3比64.8±6.2、66.2±6.8，48 h：72.4±7.0比65.8±6.3、65.0±6.5，均P＜0.05）。③3组患者各时间点ITBVI比较差异均无统计学意义（P＞0.05），且均在正常范围，可以排除因患者血容量不足导致低血压或HR过快。结论与芬太尼和瑞芬太尼比较，舒芬太尼对MAP及CI的影响更小，患者血流动力学更稳定，更适合术后老年机械通气患者的镇痛治疗。

关键词： 农业动力机械   节油   环保  

摘要： 随着我国能源问题日趋严重,各产业都要倡导环保节能,农业动力机械作为农业产业中主要的能源消耗物也应当提倡环保节能。目前,我国使用的许多农业机械存在着耗油量大、功率低等问题;同时,产生大量没有完全燃烧的有害气体,违背了环保、节能的新型农业标准。因此,就农业动力机械如何节省油耗、达到环保节能标准进行了分析探讨。

关键词： 电动机   柴油机   使用   维护  

摘要： 随着农业机械现代化的飞速发展,农业机械已经成为农民进行农业生产不能替代的生产工具,尤其是以一些小型的农业动力机械更为多见,然而对于小型农业动力机械的使用与维护在农民的思想意识还不是很熟悉,这关系到农民的生命和财产安全,更关系到我国农业健康发展。由此,在农民日常的生产安全的管理工作当中,使农民懂得这方面的知识显得尤其重要。下面就谈一下电动机和柴油机的日常使用与维护。