木质纤维生物量一步法(SSF)转化成乙醇的研究(Ι)——木质纤维原料蒸汽爆破预处理的研究

该研究采用蒸汽爆破法 ,以速生毛白杨为原料 ,在爆破时间都为 4min ,爆破压力分别为 1.5 ,2 .0 ,2 .5 ,2 .7MPa的压力条件下 ,研究比较了不同爆破压力对原料得率、产酶活力和纤维素酶解糖化的影响 .研究结果表明 :①在相同条件下 ,随着爆破压力由 1.5MPa升至 2 .7MPa ,原料得率由 84%逐渐降低至 5 1% ;②以不同爆破压力获取的毛白杨原料配合麦麸作为纤维素酶产酶培养基 ,随着爆破压力的增加 ,酶活性也随之增加 ,但也与爆破后原料的纤维素含量有关 .只有爆破后毛白杨原料的纤维素含量高时 ,酶活性才大 .每克干曲酶活力高达 139.3U/ g ;③将经过不同爆破条件预处理的毛白杨木粉进行酶解实验 ,随着爆破压力的增加 ,酶解糖化率也随之增加 ,最高爆破压力 (2 .7MPa)处理过的木粉可使酶解糖化率高达 6 5 .0 % ,比对照提高了 4.0倍 .     

A common explosion mechanism for type Ia supernovae

Type Ia supernovae, the thermonuclear explosions of white dwarf stars composed of carbon and oxygen, were instrumental as distance indicators in establishing the acceleration of the universe's expansion. However, the physics of the explosion are debated. Here we report a systematic spectral analysis of a large sample of well-observed type Ia supernovae. Mapping the velocity distribution of the main products of nuclear burning, we constrain theoretical scenarios. We find that all supernovae have low-velocity cores of stable iron-group elements. Outside this core, nickel-56 dominates the supernova ejecta. The outer extent of the iron-group material depends on the amount of nickel-56 and coincides with the inner extent of silicon, the principal product of incomplete burning. The outer extent of the bulk of silicon is similar in all supernovae, having an expansion velocity of approximately 11,000 kilometers per second and corresponding to a mass of slightly over one solar mass. This indicates that all the supernovae considered here burned similar masses and suggests that their progenitors had the same mass. Synthetic light-curve parameters and three-dimensional explosion simulations support this interpretation. A single explosion scenario, possibly a delayed detonation, may thus explain most type Ia supernovae.     

高压二氧化碳技术的杀菌研究进展

高压二氧化碳（high pressure carbon dioxide, HPCD）具有亚临界和超临界二氧化碳的性质,其溶解性和扩散性较好,在处理食品过程中会产生高压、酸化、爆炸和厌氧等效应,具有很好的杀菌作用。近年来,该技术作为一种食品非热杀菌技术,越来越受到研究者的关注。综述了该技术对微生物营养体和芽胞的杀菌研究现状,并分析了目前国内外有关HPCD杀菌机制的研究进展,以期为HPCD技术的进一步研究和应用提供参考。     

大庆油田天然气管道泄漏事故后果模拟

为防止天然气管道泄漏造成灾难性后果,采用蒸气云爆炸模型对天然气管道泄漏的火灾爆炸行为进行了模拟,计算出天然气管道泄漏后的死亡半径、重伤半径等,其结果可以为大庆油田天然气分公司应急救援提供技术支持。     

Radio studies of extragalactic supernovae

Some exploding stars (supernovae) are powerful emitters of centimeter radio radiation. Detailed observations have shown that these supernovae quickly become detectable in the radio range, first at shorter wavelengths (higher frequencies) and later at progressively longer and longer wavelengths (lower frequencies). This part of the phenomenon appears to be well explained by a monotonic decrease in the amount of ionized material surrounding the radio-emitting regions as the shock from the explosion travels outward. The radio emission itself is of a nonthermal, synchrotron origin, as is the case in most bright cosmic radio sources. Once the absorption effects become negligible, the radio intensity declines with time until reaching the detection limit of the telescope. Models suggest that the absorbing material originates in a dense wind of matter lost by the supernova progenitor star, or by its companion if it is in a binary system, in the last stages of evolution before the explosion. The synchrotron radio emission can be generated either externally by the shock wave from the explosion propagating through this same high density stellar wind or internally by a rapidly rotating neutron star, which is the collapsed core of the exploded star. Present results appear to favor the former model for at least the first several years after the supernova explosion, although the latter model remains viable.     

原油管道油气爆炸实验与数值模拟

为研究油气体积分数对爆炸的影响,采用实验研究与数值模拟相结合的方法,对输油管道油气爆炸发展机理进行研究。结果表明:油气体积分数是影响油气爆炸强烈程度的重要因素,原油油气爆炸的最大压力与初始体积分数有关。当油气体积分数为5.51%～7.06%时,体积分数越大,爆炸压力越大;当油气体积分数为7.06%时,爆炸压力达到最大值;当油气体积分数超过7.06%时,随着油气体积分数增大,爆炸最大压力反而变小。研究结果对揭示原油管道油气爆炸传播规律,减少管道爆炸事故具有指导意义。     

Electrical activity during the 2006 Mount St. Augustine volcanic eruptions

By using a combination of radio frequency time-of-arrival and interferometer measurements, we observed a sequence of lightning and electrical activity during one of Mount St. Augustine's eruptions. The observations indicate that the electrical activity had two modes or phases. First, there was an explosive phase in which the ejecta from the explosion appeared to be highly charged upon exiting the volcano, resulting in numerous apparently disorganized discharges and some simple lightning. The net charge exiting the volcano appears to have been positive. The second phase, which followed the most energetic explosion, produced conventional-type discharges that occurred within plume. Although the plume cloud was undoubtedly charged as a result of the explosion itself, the fact that the lightning onset was delayed and continued after and well downwind of the eruption indicates that in situ charging of some kind was occurring, presumably similar in some respects to that which occurs in normal thunderstorms.     

液化石油气火灾爆炸事故类型分析

对液化石油气储运过程中的各种爆炸类型及成因进行了探讨，运用事故树方法分析了引起火灾爆炸的概率和原因。指出在液化石油气爆炸事故类型中，泄漏型火灾爆炸发生的概率最大，也最危险。提出了液化石油气火灾爆炸事故的预防措施。     

毛竹蒸汽爆破法高得率浆的研究

对毛竹蒸汽爆破法制浆进行了研究 .试验结果表明 ,采用适当预处理和爆破工艺 ,可以制得得率 80 %以上 ,裂断长大于 330 0 m的毛竹爆破浆 .采用 H2 O2 用量 4%的单段过氧化氢漂白 ,毛竹爆破浆漂后白度能达到 61 % (ISO)     

油库安全问题及其预防措施

针对油库生产环境、设备设施、作业过程以及作业人员等方面存在的不安全因素,分析了油库火灾和爆炸的成因,探索了雷电对油库的危害性以及油料静电火灾的规律,制定了油库预防雷电及静电着火的措施。     

蒸汽爆破预处理油菜籽的多酚得率及抗氧化活性

油菜籽经0.4、0.7、1.0 MPa等3种压力及维压1、3 min的蒸汽爆破预处理后,采用低温压榨法分离菜籽饼及油,分别测定其多酚得率、组成及抗氧化活性,探究蒸汽爆破预处理对其的影响。结果表明：相同维压时间下提高爆破压力或相同的压力下延长维压时间,制备的菜籽油颜色逐渐加深;经蒸汽爆破处理后菜籽饼多酚得率为7.12~8.42 g/(100 g),菜籽油多酚得率显著提高,1.0 MPa下维压3 min时,菜籽油多酚得率最高,为0.56 g/(100 g);菜籽饼中生成了2,6–二甲氧基–4–乙烯基苯酚(canolol)、儿茶素、咖啡酸等物质,其中canolol的转化生成量最大,且一部分迁移到菜籽油中,0.7 MPa下维压3 min时,菜籽饼和油中canolol含量达到最大,分别为12 120.00、4680.00 mg/kg;DPPH、ABTS和FRAP法测定的菜籽油提取物的抗氧化能力显著提升,但菜籽饼的抗氧化能力变化幅度较小;多酚得率与提取物的抗氧化能力之间存在显著或极显著的正相关。可见,蒸汽爆破可作为提高菜籽油中多酚含量及抗氧化活性的一种有效预处理技术,蒸汽压力0.7 MPa、维压3 min可作为一个较优的汽爆条件用于油菜籽的加工处理。     

秸秆膨化技术的研究现状及发展展望

秸秆是一种重要的可再生资源,有着多种用途,将秸秆膨化加工成家畜饲料是目前最具有发展前景的秸秆利用技术。论述了挤压膨化和汽爆膨化加工技术的发展历史及研究成果,重点分析了目前国内外秸秆膨化饲料加工技术的研究现状,并在此基础上提出了优化汽爆工艺参数、重视原料的预处理和后处理以及降低汽爆加工的能耗等未来的主要发展方向。     

石油储罐防火防爆常见问题的分析

随着国内石油储罐类型和设计构造的不断改进,容量趋于大型化,相应安全技术条件不断完善,但在实际生产过程中, 还存在着许多影响油罐安全运行的问题。从加速 油罐防火防爆问题出发,对生产实践中遇到的一些实际问题进行分析,并提出了预防油罐发生火灾爆炸事故的具体措施。     

蒸汽爆破开启落叶松木材细胞通道

采用5种蒸汽爆破处理（压力0.2MPa,爆破重复10次;压力0.3MPa,爆破分别重复5次、10次和15次;压力0.4MPa,爆破重复10次）,结果表明：压力0.4MPa、爆破10次处理的木材细胞闭塞纹孔开启程度最大,开启率为38.5％;压力0.3MPa、爆破15次处理的开启率为31.2％;压力0.3MPa、爆破10次处理的开启率为28.5％;压力0.3MPa、爆破5次处理的开启率为18.3％;压力0.2MPa、爆破10次处理的开启率仅为13.9％.落叶松木材具缘纹孔膜塞缘出现不同程度的断裂,闭塞纹孔变成非闭塞纹孔,开启了落叶松木材细胞液体流动通道.     

油库爆炸危险性分析

从物理性爆炸和化学性爆炸两个方面分析了油库火灾爆炸的危险，提出了预防油库火灾爆炸事故发生的技术措施和管理措施，可为油库安全运营提供参考。     

含泥岩夹层盐穴储气库的爆炸动力响应数值模拟

为了探讨含泥岩夹层盐穴储气库在可燃气体爆炸作用下的稳定性,利用有限差分软件FLAC^3D,建立盐穴储气库的数值模型,分析爆炸载荷作用下含泥岩夹层盐穴储气库的动态响应,包括储气库围岩的应力状态变化、地震动幅值及稳定性等。结果表明:在可燃气体爆炸载荷作用下,泥岩夹层与盐岩中应力变化基本一致,不存在明显的薄弱部位;人工拟合爆炸波对洞室围岩的冲击作用比三角形爆炸波作用强;可燃气体爆炸作用对洞室围岩破坏的影响有限,随洞室深度的增大迅速衰减;深埋盐穴储气库比浅埋洞室抵抗爆炸作用的能力更强,有利于储气库洞室的稳定性。     

汽爆预处理对废弃烤后烟叶产甲烷潜力的影响

为资源化利用涉烟有机废弃物,以废弃烤后烟叶为底物进行了中温厌氧发酵实验,通过对比研究蒸汽爆破预处理及5种汽爆条件对烤后烟叶产甲烷潜力的影响,探讨汽爆在烤后烟叶厌氧发酵中应用的可行性。结果表明:未处理烤后烟叶L0的生化产甲烷潜力值高于绝大多数木质纤维素类废弃物,达到了252.7 mL·g~(-1)VS,且产气周期短,是优良的发酵原料;烤后烟叶在汽爆过程中发生固液组分分离,液体糖难以完全回收进而影响产气。与L0相比,汽爆后烟叶的生化产甲烷潜力均有下降,L1～L5分别降低了11.6%、23.0%、24.0%、22.4%及26.3%。对于烤后烟叶,尽管汽爆预处理能打开物料结构,但也会导致液体糖分大量流失,甲烷产量下降。综合考虑产品价值和处理能耗等因素,在实际应用中直接将烤后烟叶进行厌氧发酵是更优的选择。     

大连大孤山海区水下爆破对海洋环境及浮游生物的影响

为了解大连湾大孤山海区水下爆破活动对其所在海区水质及浮游生物的影响,于2007年的9—12月对爆破后2 h和1 000 m范围内的爆破区域进行了监测,内容包括透明度、盐度、溶氧、pH、悬浮物、油、氨态氮、硝酸氮、亚硝酸氮、活性磷10项水质指标和叶绿素a、浮游植物生物量、浮游动物生物量3个生物指标。结果表明：爆破对海区透明度和悬浮物的影响显著,对其它指标影响不显著。整体上,本次爆破不会对该海区水质及浮游生物量产生明显的影响。     

液化石油气蒸气爆炸过程研究进展

液化石油气蒸气爆炸是其储运过程中较易发生且危害极大的一种热力过程。探讨了液化石油气沸腾液体膨胀蒸气爆炸和沸腾液体压缩气泡爆炸的发生机理,介绍了国内外对储罐破裂前的热力响应过程和储罐破裂后的压力瞬变过程两个阶段的研究进展和取得的成果,并提出了若干尚待进一步研究的领域。     

Soft X-rays from the Cygnus Loop: Interpretation

Two possible interpretations of the recent soft x-ray observation of the Cygnus Loop are discussed. A synchrotron model requires a magnetic field less than 10(-6) gauss and electron energies in excess of 10(14) electron volts. These electrons must either have been reaccelerated or continuously injected into the source for about 50,000 years. The observations are also consistent with the radiation from a hot plasma having the cosmic abundances of the elements. A likely origin for the hot plasma is a blast wave produced by the explosion of a supernova in the interstellar medium. Fitting such a model to the observations implies a kinetic energy release in the explosion of 6x 10(50) ergs for an assumed distance of 770 parsec.