基于LC-MS/MS成分分析结合高效液相色谱法评价泻白散基准样品质量

目的：建立泻白散基准样品特征图谱方法,以LC-MS/MS指认各特征峰并对其进行归属,建立基准样品各组成药味质控指标的含量测定方法综合评价其质量。方法：以色谱柱Hypersil ODS²(250 mm×4.6 mm,5μm)、乙腈-0.1%磷酸/甲酸梯度洗脱、检测波长280nm、流速1.0 ml/min、柱温25℃、进样量10μl进行指纹图谱研究,以同一色谱条件使用LC-MS/MS联用进行峰归属并进行化学成分分析,以指认的各药味专属性峰建立基准样品质控指标含量测定方法。结果：泻白散基准样品特征图谱重复性良好,供试品溶液48 h内稳定,多批次检测显示泻白散指纹图谱共有峰14个,相似度均＞0.9;峰归属确认其中5个归属于炒桑白皮,5个归属于炙甘草,3个归属于地骨皮;并通过LC-MS/MS指认出其中11个色谱峰;选取桑皮苷A、甘草酸、枸杞素B分别建立含量测定方法,结果显示方法均具有专属性,重复性良好,加样回收率分别为94.9%、93.5%、95.2%。结论：该指纹图谱方法经验证可行,可有效鉴别泻白散三味饮片;结合LC-MS/MS成分分析可有效选取基准样品各药味的质控成分;建立的检测桑皮苷A、甘草酸、枸杞素B含量测定方法经方法学考察确认可行。     

Effect of causal and acausal filters on elastic and inelastic response spectra

With increasing interest in displacement spectra and long‐period motions, it is important to check the sensitivity of both elastic and inelastic response spectra to the filtering that is often necessary to remove long period artifacts, even from many modern digital recordings. Using two records of very different character from the M=7.1, 1999 Hector Mine, California, earthquake, we find that the response spectra can be sensitive to the corner periods used in causal filtering, even for oscillator periods much less than the filter corner periods. The effect is most pronounced for inelastic response spectra, where the ratio of response spectra computed from accelerations filtered at 25 and 200 sec can be close to a factor of 2 for oscillator periods less than 5 sec. Published in 2003 by John Wiley Sons, Ltd.     

Strategies for Successful ANAMMOX Enrichment at Laboratory Scale

Studies on anaerobic ammonium oxidation (ANAMMOX) have been increasing due to its advantages over traditional nitrification–denitrification systems. However, long and difficult start‐up periods of ANAMMOX reactors may sometimes be frustrating for researchers dealing with them first time in the lab. Therefore, a guide for starting up ANAMMOX reactors will greatly help them and enhance the use of this technology. Three trials, each has three reactors, have been carried out to reach successful start up in this study. An expected ANAMMOX enrichment could not be achieved in the first and second trials. Under the light of the experiences gained from the unsuccessful ones, the third trial resulted in >95% ammonium removals within 20–50 days. It is possible to startup or to enrich ANAMMOX reactors within 50 days by presented strategy guide.     

The effect of the relative humidity and the specific humidity on the determination of the climate regions in Turkey

All elements of climate that affect climatic events must be taken into account such that the climate regions are determined with exactitude. To this end, data on maximum temperature (Tx), minimum temperature (Tn), mean temperature (Tm), and precipitation (Pt) as well as local pressure (Ps), mean wind (WN), relative humidity (RH), and specific humidity (SH) have been investigated statistically and graphically. The specific humidity data calculated using Tm, Ps, and RH data and statistical comparisons have shown that there are no drawbacks to using SH in climatologic studies. According to principal component analysis, it was concluded that RH and SH should be used together with Tx, Tm, Tn, and Pt for the determination of the climate regions. Two cluster analysis methods, Ward's method and Kohonen neural network technique, were used to show the effect of RH and SH. A comparison of the cluster's stability between the limited and high number of stations shows that Ward's method and Kohonen neural network are very stable in both cases. It was also determined that RH does not change the outline of climate regions but that it affects the zones of climate transition. It was observed that clusters determined by using Tm, Pt, and RH provide relatively more distinctive clusters in the data space than clusters determined by using Tm, Pt, and SH.     

The interaction of elasticity and rocking in flexible structures allowed to uplift

Numerous structures uplift under the influence of strong ground motion. Although many researchers have investigated the effects of base uplift on very stiff (ideally rigid) structures, the rocking response of flexible structures has received less attention. Related practical analysis methods treat these structures with simplified ‘equivalent’ oscillators without directly addressing the interaction between elasticity and rocking. This paper addresses the fundamental dynamics of flexible rocking structures. The nonlinear equations of motion, derived using a Lagrangian formulation for large rotations, are presented for an idealized structural model. Particular attention is devoted to the transition between successive phases; a physically consistent classical impact framework is utilized alongside an energy approach. The fundamental dynamic properties of the flexible rocking system are compared with those of similar linear elastic oscillators and rigid rocking structures, revealing the distinct characteristics of flexible rocking structures. In particular, parametric analysis is performed to quantify the effect of elasticity on uplift, overturning instability, and harmonic response, from which an uplifted resonance emerges. The contribution of stability and strength to the collapse of flexible rocking structures is discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Analytical modelling of multi‐mass flexible rocking structures

This paper presents a new analytical model for describing the large rocking response of an elastic multi‐mass structure resting on ideally rigid ground. Using the experimental results from a rocking steel column, the ability of the proposed analytical model to estimate the rocking and translational acceleration response under free vibration, pulse and earthquake excitations is evaluated. It is observed that the classical treatment of impact may result in an unrealistically large transfer of energy to vibrations. Therefore a new Dirac‐delta type impact model that spreads the effects of impact over time and space is proposed. The use of a Dirac‐delta model and accurate restitution factors play a pivotal role in prediction of rocking and acceleration responses. In order to characterize the nonlinear response better, a modal analysis of the linearized system is proposed. With this approach, the vibration mode frequencies and shapes during rocking action were determined. A comparison of analytical and experimental modal estimations suggests good agreement. The results emphasize that the vibration characteristics of several vibration modes are affected by rocking action, and these modes may be excited at impact. Copyright © 2016 John Wiley & Sons, Ltd.     

The rocking response of large flexible structures to earthquakes

The rocking response of structures subjected to strong ground motions is a problem of ‘several scales’. While small structures are sensitive to acceleration pulses acting successively, large structures are more significantly affected by coherent low frequency components of ground motion. As a result, the rocking response of large structures is more stable and orderly, allowing effective isolation from the ground without imminent danger of overturning. This paper aims to characterize and predict the maximum rocking response of large and flexible structures to earthquakes using an idealized structural model. To achieve this, the maximum rocking demand caused by different earthquake records was evaluated using several ground motion intensity measures. Pulse-type records which typically have high peak ground velocity and lower frequency content caused large rocking amplitudes, whereas non-pulse type records caused random rocking motion confined to small rocking amplitudes. Coherent velocity pulses were therefore identified as the primary cause of significant rocking motion. Using a suite of pulse-type ground motions, it was observed that idealized wavelets fitted to velocity pulses can adequately describe the rocking response of large structures. Further, a parametric analysis demonstrates that pulse shape parameters affect the maximum rocking response significantly. Based on these two findings, a probabilistic analysis method is proposed for estimating the maximum rocking demand to pulse-type earthquakes. The dimensionless demand maps, produced using these methods, have predictive power in the near-field provided that pulse period and amplitude can be estimated a priori. Use of this method within a probabilistic seismic demand analysis framework is briefly discussed.     

北半球绕极涡的变异及其与我国气候异常的关系

本文利用近50 a大气再分析资料和中国站点观测资料,通过定义绕极涡的总体面积指数,分析了北半球绕极涡的变异特征及其与我国气候异常的关系,通过考虑绕极涡的局地变异和利用SVD分析方法揭示了绕极涡的局地变异与我国气候变异的关系。结果表明:北半球绕极涡的总体面积变异表现为一致性的扩张或收缩变化特征,近50 a来其总体面积具有收缩的趋势,这与全球增暖尤其是极区增暖有密切关系;叠加在这种趋势之上的既有年际变化又有年代际变化,主要周期大约是3~5 a和8~12 a。因此,研究绕极涡与我国气候的相关时分时间尺度来考虑更合理。北半球绕极涡的总体面积变异与我国气候异常的关系主要体现在年代际时间尺度上,当北半球绕极涡总体一致性收缩时,冬季我国大部分地区的气温都会随之变高,而降水偏多;夏季东北、华北、西南和华南地区气温偏高,降水偏少,而江淮流域气温偏低,降水偏多。反之亦然。北半球绕极涡的局地变异主要体现在西风带长波振幅的变异上,而其与我国气候异常的联系主要表现在年际时间尺度上,当东亚大槽减弱时,冬季我国中、东部大部分地区气温偏高,降水偏多;夏季江淮流域和四川盆地气温偏低,其它地区气温偏高,降水变化不明显。反之亦然。