隐晶质玄武岩破裂演化及破坏特征试验研究

隐晶质玄武岩是白鹤滩水电站超大规模地下厂房洞室群中广泛揭露出的主要围岩类别之一,且普遍赋存隐微裂隙,开挖过程中展现出特殊的力学响应特征。综合采用CT扫描、高速摄像、声发射、扫描电镜等手段,分析了隐晶质玄武岩的变形破坏特征、裂纹扩展及声发射演化规律等,并探讨了其细观破坏机制。结果表明:完整试样应力-应变曲线光滑,加载至峰值强度时瞬间爆裂,声发射信号异常集中,碎裂破坏;含隐微裂隙试样应力-应变曲线呈锯齿状,出现多次表面剥落,整个过程声发射信号非常活跃,以劈裂破坏为主;含宏观裂隙试样应力-应变曲线呈双峰或多峰状,峰前原生裂隙局部滑移,第1次峰值时宏观破裂面形成,声发射信号集中于峰值应力跌落瞬间,以剪切破坏为主。隐晶质玄武岩细观破坏机制主要为矿物颗粒沿晶断裂和穿晶断裂。研究成果为准确认识并科学掌握白鹤滩地下厂房洞室群围岩的力学响应及其破裂演化特征奠定了坚实基础,也可为硬脆岩体高应力破坏的认识和灾害控制提供参考和借鉴。

不同形状饲料对种鸽采食行为的影响

试验旨在探讨不同形状饲料对种鸽采食行为的影响。试验以健康、体重接近的美国白羽王鸽为研究对象,分为3个试验。试验1:挑选40对具有完整生产记录的种鸽,分为挑食型和非挑食型,比较两者1月—4月的生产性能。试验2:选用非哺育期种鸽10对,进行玉米胚形、圆球形、卵椭圆形和圆柱形4种饲料混合饲喂,观察分析种鸽的采食行为规律,试验期12 d。试验3:选用非哺育期种鸽32对,随机分为4组,每组8对,分别饲喂以上4种形状饲料,观察分析种鸽的采食行为规律,试验期14 d。结果显示:与非挑食型种鸽比较,挑食型种鸽在1月—4月所哺育的乳鸽成活率显著降低(P<0.05)。0~10 min,种鸽采食偏向于玉米胚形或圆柱形饲料;10~15 min,种鸽采食玉米胚形饲料极显著多于圆球形饲料(P<0.01);20 min内,种鸽采食玉米胚形或圆柱形饲料极显著多于圆球形或卵椭圆形饲料(P<0.01)。玉米胚形饲料的浪费量极显著高于其他形状饲料(P<0.01);卵椭圆形饲料的采食时间极显著多于其他形状饲料(P<0.01)。研究表明,实际生产中可以饲喂圆柱形饲料以提高种鸽采食量,降低饲料浪费量,且尽量降低种鸽的挑食行为所带来的负面影响。

Molecular identification of bloom-forming species Phaeocystis globosa(Prymnesiophyta)and its dispersal based on rDNA ITS sequence analysis

The colony-forming Phaeocystis species are causative agents of dense bloom occurrences incoastal waters worldwide. It is difficult to separate them because of the different morphologies associated with their colonial stages. In this study we applied molecular approaches to analyze the genetic variation of Phaeocystis globosa and Phaeocystis pouchetii from several geographic regions, and to assist in tracing the dispersal of bloom-forming Phaeocystis species in coastal waters of China. The sequences of the internal transcribed spacers (ITS1 and ITS2) of rDNA and the 5. 8S ribosomal RNA gene of Phaeocystis strains were determined. Sequence comparison shows that P.globosa was the most divergent to P. pouchetii, exhibiting sequence divergence higher than 0.08. However, lower genetic divergences existed between strains of P. globosa. The sequence comparison of the Phaeocystis rDNA ITS clearly shows that the species isolated from the southeast coast of China is identified as P. globosa rather than P. cf. pouchetii or other species. Furthermore, the significance of rDNA variation in distinct global populations of P. globosa suggested it might have had sufficient time to accumulate detectable mutations at the rDNA locus, supporting the hypothesis of ancient dispersal of P .globosa to many areas, meaning that P. globosa blooms in the coastal waters of China are endemic rather than a newly introduced species or a foreign source. Finally, based on the high divergent region of rDNA ITS, a pair of species-specific primers for P. globosa were designed, they could be useful to detect the presence of this species in mixed plankton assemblages or flagellate stages that are recognized with diffculties by means of conventional microscopy.

Molecular Chirality and Chiral Superlattice in Crystal of Tetrakis[(pyrrol-1-yl)methyl]methane

The crystal structure of tetrakis[(pyrrol-1-yl)methyl]methane was determined by X-ray diffraction measurement, and the result shows that it belongs to monoclinic crystal system, space group is P2 1/n, with a=0.9284(3) nm, b=1.0950(6) nm, c=1.8749(8) nm; α=γ= 90.00(4)°, β=103.63(3)°, V=1.8523(14) nm 3, Z=4, ρ calcd. =1.192 kg/m 3, μ=0.072 nm -1 , F(000)=712, R 1=0.0854, wR 2=0.1884. It has been found that the molecules exist in two enantiomeric states. Enantioselective self-assemblies such as one-dimensional molecular stacks in a single handedness, homochiral monolayers and a chiral superlattice are specified in this racemic crystal. In addition, a simple technique is advocated to distinguish chiral states from tetrahedral molecules in the solid state. The present R/S nomenclature of the tetracooradinated carbon centers is used solely for its convenience to distinguish the two enantiomeric states, but not used to determine the absolute configurations.

Positioning Error of Optoelectronic Telescope Compensated by Bipolar PWM Driving Mode

The optoelectronic telescope has two sets of control systems: azimuth one and elevation one, and both are driven by PWM power amplifier with high efficiency and wide speed regulation range. The diagram of the azimuth control system is demonstrated, the nonlinear factors is analyzed at low speed, and some related experiments are carried out. The results show that the positioning error with unipolar is 86 codes(106.21″), while 18 codes (22.23″) is with bipolar PWM driver.

Formate and acetate as recorded in a mid-latitude glacier in west China

Formate and acetate are ubiquitous in the troposphere. Their occurrence is closely related to processes in the biosphere and contributes to an understanding of carbon biogeochemical cycles. A 43-year record of formate and acetate in an ice core from Glacier 1 (43?6′N, 86?9′E) at Urumqi river head, Tianshan, west China was investigated. Fluctuating between 22.7 ng·g-1 and 2830.7 ng·g-1, acetate concentration averages 373.2 ?376.1 ng·g-1 (mean ?1s, N = 541) and is the highest anion in the record. Next to acetate, the concentration for formate varies between 2.1 ng·g-1 and 795.5 ng·g-1 and averages 61.1 ?89.0 ng·g-1 (N = 541). The formate to acetate ratio averages 0.22 ?0.25 (N = 541), indicating that the chief source is from fossil fuel combustion, coal burning in particular. The two species co-varied in the past four decades and exhibited periods of high concentration from the early 1960s to the middle of 1970s and from the early 1980s to the middle of 1990s, separated by a time of the lower concentration between 1975—1980. These variations may reflect the local/regional anthropogenic pollution to the atmosphere as well as the economic development of northwestern China.