Protective effects of a synthetic soybean isoflavone against oxidative damage in chick skeletal muscle cells

The antioxidant and protective properties of a synthetic soybean isoflavone (SI) were investigated using chick skeletal (leg) muscle cells (SMC) isolated from 20-day-old Linnan yellow broiler chick embryo. Skeletal muscle cells were cultured in Dulbecco’s modified Eagle’s medium treated with 0, 12.5, 25, 50, 75 and 100 μM SI, respectively, under 80 μM H₂O₂/FeSO₄ conditions. After 24 h of incubation, SI reduced the loss of SMC under oxidative stress by H₂O₂/FeSO₄. The addition of SI significantly promoted SMC proliferation (P < 0.01). Upon treatment with 25, 50, 75 and 100 μM SI, the activity of total superoxide dismutase in the supernatant of the media was enhanced by 17.0%, 13.0%, 13.3% and 11.9%, respectively (P < 0.05). Compared to the control, the activity of glutathione peroxidase was significantly increased only at 25 μM concentration of SI (P < 0.05), and the increment was 90.7%. The activity of catalase was increased by 49.2% and 49.1%, respectively, at 75 and 100 μM SI (P < 0.01). The concentration of creatine kinase in the media was decreased by 61.6% and 60.6%, respectively, at 75 and 100 μM SI (P < 0.01). The addition of SI did not affect the activity of lactate dehydrogenase in the media. In conclusion, the SI protected skeletal muscle cells from oxidative damage, attributed to its antioxidant activity.     

Control of one kind of nonlinear parabolic distributed parameter system with moving boundary

 This paper presents the modeling of one kind of nonlinear parabolic distributed parameter control system. By transforming the system to that in the fixed domain, or into the lumped parameter system, this paper provides an insight into the basic features of the control system, as well as the critical conditions for the control variable. The equations for one-dimensional systems of planar, cylindrical and spherical cases are formulated as a unified form, and the dynamic characteristics of the open-loop control system and close-cycle feedback control system have been investigated. Numerical results agree well with theoretical results. The simulation results indicate that the system is well posed, stable, measurable and controllable. Received 16 May 2000     

工程项目投资决策可行性研究的探讨

本文通过分析我国工程项目投资决策可行性研究的重要性,就如何做好投资决策可行性研究提出了对策建议,认为农村可行性报告的要求是客观、全面、真实、科学与公正。     

First-principles supercell studies of the substitutional carbon in c-BN

The effects of hydrostatic pressure on the formation enthalpy and electronic level positions of C_N and C_B in c-BN are investigated by means of ab initio plane-wave pseudopotential method using a supercell approach in the range of 0–60 GPa. The formation enthalpy decreases with pressure for C_B, suggesting that C_B becomes much more stable and has a larger concentration with pressure increase. In contrast to C_B, the C_N impurity exhibits positive dependence of the formation enthalpy on pressure, so the concentration of C_N reduces with pressure. With pressure increase, the defect energy levels of C_B^+ 1 and C_N^– 1 move into the conduction band and the valence band, respectively, while the defect energy levels of C_B and C_N in other charge states all move toward the center of band gap. These results suggest that pressure may make electron transfer between the impurity band and the conduction band or the valence band difficult and weaken its conductivity when a C atom substitutes at a B site or at a N site in c-BN.     

Irreducible decompositions of physical tensors of high orders

In this paper we use the term 'physical tensor' to stand for a tensor that belongs to a tensor subspace. Based on the relationship among the characters of rotation representation, some techniques are developed in order to give the numbers of independent deviatoric tensors contained in the irreducible decompositions of physical tensors, even prior to the constructions of the irreducible decompositions. A number of examples are shown and many of them are new results.     

降低烧结生产成本的几点作法

指出了冶金企业在市场竞争中要降低成本，烧吉应首先优化原、燃料结构、提高科技含量，节能降耗，生产高品位，高碱度的烧结矿。     

The monitoring and early detection of Internet worms

After many Internet-scale worm incidents in recent years, it is clear that a simple self-propagating worm can quickly spread across the Internet and cause severe damage to our society. Facing this great security threat, we need to build an early detection system that can detect the presence of a worm in the Internet as quickly as possible in order to give people accurate early warning information and possible reaction time for counteractions. This paper first presents an Internet worm monitoring system. Then, based on the idea of "detecting the trend, not the burst" of monitored illegitimate traffic, we present a "trend detection" methodology to detect a worm at its early propagation stage by using Kalman filter estimation, which is robust to background noise in the monitored data. In addition, for uniform-scan worms such as Code Red, we can effectively predict the overall vulnerable population size, and estimate accurately how many computers are really infected in the global Internet based on the biased monitored data. For monitoring a nonuniform scan worm, especially a sequential-scan worm such as Blaster, we show that it is crucial for the address space covered by the worm monitoring system to be as distributed as possible.     

某难选冶金矿石压热氧化预处理工艺的碱性介质研究

系统地研究了压热氧化预处理贵州某难选冶金矿石工艺条件中碱性介质选取及用量对金浸出率的影响。研究结果表明：NaOH与Ca(OH)2配合使用作为碱性介质，预处理效果较好。在NaOH初始浓度为0.1-0.2mol/L(10-20kg/t矿石）、矿石粒度98％－200目、矿浆浓度为25％、木质素磺酸钙用量0.1kg/t、温度220℃、操作压力3.2MPa、氧化预处理2h条件下，金的氰化浸出率能稳定在90％以上。     

POLYMER DIODES MADE OF ION IMPLANTED POLYACETYLENE FILMS

Polyacetylene films were doped with FeCl3 and implanted with 30 k'eV K+ ions. Physical changes to the films were examined by a series of measurements, which include the four-probe test, infrared ray absorption and 2 MeV He+ particle elastic recoil dettection and Rutherford backscattering. The chemical dopants (Fe+++ and Cl-) were redistributed after the implantation and the different species (K+. Fe+++ and Cl-ions) formed p - n junctions at the implantation depths. The implanted films exhibited desirable Ⅰ-Ⅴ characteristics, with current densities as high as 600 mA/cm- at 3V and back - to - forward ratio of current over 300. The polymer diodes kept their behavior for over 60 days. Discussions on the results were given in detail.     

共析相变时Fe3C／α相界系统的内能和熵

讨论了珠光体形核时Fe3C/α相界系统的内能和妨，推导并建立了相应的内能与熵公式。