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The chemical constituents of plants in the genus Ferula (Umbelliferea) have been studied by many groups. The compounds commonly found in this genus are sesquiterpenes 1,2) and sesquiterpene coumarins. 1,3) There were reports about sesquiterpene coumarins found in the roots of F. teterrima, 4,5) and in previous chemical investigations on F. sinkiangensis, polysulfanes were identified by GC-MS. 6) F. sinkiangensis and F. teterrima mainly grow in Xinjiang Uygur Autonomous Region of China, and have been used in traditional medicine for treatment of rheumatoid arthritis and stomach disease. As part of our studies of the genus Ferula, we investigated on the constituents of the roots of F. sinkiangensis and F. teterrima. These studies have led to the isolation of four natural sesquiterpene coumarins, isofeterin (1), lehmannolone (2), lehmannolol (3), and sinkianone (4). In this report, the isolation and structure elucidation of compounds 1-4 are presented. Results and DiscussionThe roots of F. sinkiangensis were extracted with 95% ethanol, and the extract was separated by solvent partitions to give petroleum ether-, EtOAc-, n-BuOH-, and water-soluble fractions. The EtOAc fraction was subjected to repeated column chromatography to afford compounds 2-4. The roots of F. teterrima were treated in the same way, and the EtOAc fraction was subjected to repeated column chromatography to afford compound 1.Compound 1 was obtained as a white amorphous powder. Its HR-EI-MS spectrum exhibited the [M] ϩ at m/z 440.2193, corresponding to the molecular formula C 26 H 32 O 6 . The IR spectrum indicated the presence of carbonyl and hydroxyl groups (1712, 1728, 3433 cm Ϫ1 ). The 13 C-NMR spectrum of 1 displayed 26 carbon signals ( Table 2). Nine of which were typical for an umbelliferone skeleton and the other 17 carbons were associated to an acetyl group and a sesquiterpene unit. This suggested that 1 was derived from sesquiterpene and umbelliferone structures.7) The carbon signals were classified referring to the DEPT together with HSQC and 1 H-NMR spectra as four methyl groups at d C 31.3, 22.6, 16.9, and 21.9, three aliphatic methylene units at d C 31.9, 25. (Fig. 2). Thus the structure of 1 was determined to be as shown in Fig. 1.Compound 2 was obtained as colorless crystals. Its HR-EI-MS spectrum exhibited the [M] ϩ at m/z 382.2124, corre- Three new natural sesquiterpene coumarins, isofeterin (1), lehmannolol (3), sinkianone (4), and one known compound, lehmannolone (2), were isolated from the roots of Ferula teterrima and Ferula sinkiangensis. Their chemical structures were established on the basis of spectroscopic analysis, including X-ray crystallography and CD spectrum measurements for determining the absolute configuration of compound 2.

Vibratory stress relief (VSR) is a highly efficient and low-energy consumption method to relieve and homogenize residual stresses in materials. Thus, the effect of VSR on the fatigue life should be determined. Standard fatigue specimens are fabricated to investigate the fatigue life of Ti-6Al-4V titanium alloy treated by VSR. The dynamic stresses generated under different VSR amplitudes are measured, and then the relationship between the dynamic stress and vibration amplitude is obtained. Different specimen groups are subjected to VSRs with different amplitudes and annealing treatment with typical process parameters. Residual stresses are measured to evaluate the stress relieving effects. Finally, the fatigue behavior under different states is determined by uniaxial tension-compression fatigue experiments. Results show that VSR and annealing treatment have negative effects on the fatigue life of Ti-6Al-4V. The fatigue life is decreased with the increase in VSR amplitude. When the VSR amplitude is less than 0.1 mm, the decrease in fatigue limit is less than 2%. Compared with specimens without VSR or annealing treatment, the fatigue limit of the specimens treated by VSR with 0.2 mm amplitude and annealing treatment decreases by 10.60% and 8.52%, respectively. Although the stress relieving effect is better, high amplitude VSR will lead to the decrease of Ti-6Al-4V fatigue life due to the defects generated during vibration. Low amplitude VSR can effectively relieve the stress with little decrease in fatigue life.

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Vibratory stress relief is a green and efficient aging technology compared with traditional natural stress relief and thermal stress relief. The research aimed to determine whether vibratory stress relief is feasible to improve the fatigue life of aluminum alloy 7075-T651 or not. Under the same resonance frequency, analyses and comparisons of the residual stress distributions before and after vibratory stress relief are presented with X-ray method. Experimental results indicate that vibratory stress relief is effective in reducing and equilibrating residual stresses. Through uniaxial tension–compression fatigue tests, we obtained the S–N curves for specimens under states of original and varying exciting forces. Findings led to the conclusion that vibratory stress relief can improve the fatigue life of aluminum alloy 7075-T651 when dynamic stress does not exceed 8% of the yield strength.

This paper presents a distributed nodal method (DNM) for compact modeling of the package-device interaction of microelectromechanical systems (MEMS). MEMS devices have movable structures that are sensitive to structural stresses and easily influenced by package structures and environmental parameters. Hence, it is necessary to include the packaged behavior of MEMS into a compact simulation tool with acceptable precision. The conventional nodal method is therefore modified to achieve this purpose. A node with distributed nodal quantities is defined to describe the distributed interactions among the device, package, and environmental temperature. Based on the definition, the related processes of element partition, nodal matrix formation, and element assembly have been demonstrated. The case of a die-bonded microbridge has been used as an example, since the microbridge is not only a typical MEMS structure but also is influenced easily by structural stresses. The DNM model is validated first by a finite-element method (FEM) simulation, then by two individual experiments, including the measurement of die warpage using a digital image correlation system and the detection of shifted natural frequencies of surface-micromachined bridges using a laser Doppler vibrometer system, both after die bonding. The FEM and test results agree with those evaluated by the model with a relative error of less than 10%. Stress alleviation of the test structure has been unintentionally achieved by die bonding, leading to relative shifts of 12%-26% and 19%-26% of the first and third natural frequencies of the microbridges. The packaged behavior also exhibits an evident distributed feature along the die surface as expected. Although, at current stage, the application of the DNM is still limited to static domain, it shows potential in developing hierarchical models of MEMS devices including the package.[ 2007-0256]Index Terms-Die bonding, modeling, nodal analysis, package effect.

The use of Newmark permanent displacement to preliminarily evaluate the seismic performance of earth slopes has been well accepted in geotechnical community. Essentially, the seismic displacement would cause slope soil shear strength to reduce, thus causing the slope yield acceleration to degrade during the earthquake shaking. This phenomenon is known as degrading effect of yield acceleration, which has not been fully addressed in the literature. In this study, the degrading effect is investigated on the basis of various Newmark's displacement calculation frameworks for infinite slopes. Specifically, the flexible‐deformation‐recoverable soil columns as well as the nonlinear soil dynamic properties including the damping and shear modulus are taken into account to derive the coupled Newmark model. Detailed discussions are made to the possible influence of the degrading effect of yield acceleration in different schemes of Newmark displacement calculation frameworks. The parametric studies show that the seismic displacement calculated by the proposed method reaches peak value at small period ratio, and dramatically drops to zero when the period ratio increases. Furthermore, the possible influence of shear rate on soil shear strength is also discussed.

Earthquake-induced permanent displacements of slopes are generally evaluated through the simplified sliding block analyses of a singular coherent mass on a predefined failure plane. However, coseismic landslides may exhibit multiple slip surfaces as a result of earthquake shaking. This study presents a generalized seismic sliding analysis using a column of sliding blocks to model seismic slope failures with multiple slip surfaces. The formulation of the sliding mode equations of the block system is obtained by a rigorous theoretical derivation.Both a rigid soil column associated with an acceleration-time series that is constant with depth, and a flexible soil column considering an acceleration-time series that varies throughout the sliding mass is presented. The conditional yield accelerations and the equivalent seismic accelerations are defined to characterize the complex interplay of the sliding block assemblies. The approach is applied to model the seismic sliding behavior of layered slopes in which failures would likely occur at the interfaces between soil layers with different shear strengths.The effects of input ground motions and soil deposits on the sliding patterns of slopes are investigated. The developed generalized model provides a promising means for evaluating the seismic slope stability by combining a number of seismic failure locations within slopes.