微生物回复突变试验检测药品的体会

我所自1981年建立微生物回复突变试验以来,已经检测60多种中西药品,其中有的已作了报道。近两年来,由于我国新药大量涌现,我们在用微生物回复突变试验对种类不同的各类新药进行检定中,发现由于药品(特别是成品药)本身的特点。

用紫露草微核试验检测大厂锡矿环境诱变物的研究

广西大厂锡矿是我国肺癌高发点之一,肺癌发病率有逐年上升的趋势。为了探讨职工肺癌高发与生产环境的关系,本文采用紫露草微核试验(Tradescantia MicronucleusTest),在该矿区的井下和地面作业区以及职工生活区,共检测了9个空气点,同时,在上述空气检测点和其它生产作业区,采集和分析了18份矿尘,结果有两点发现:

试论分析化学中成品分析方法的发展

随着时代进步,科学技术和计算机技术迅猛发展,分析化学中的案例剖析(即成品分析)应用越来越广泛,涉及行业也越来越多。本文对其特点、手段、程序、应用进行了阐述,对其发展历程进行了介绍,以期为将来成品分析方法的改善提供充足的理论依据和重要参考。

速测技术在蔬菜农药残留检测中的应用

就目前主要应用于蔬菜农药残留的检测方法,以16种512个蔬菜样品的试验结果为依据,分析快速检测技术在蔬菜农药残留中应用的可行性以及尚需解决的问题,并对该检测技术的开发研究提出了建议。

Joint member angle limits of composite beams and CFT square columns

This work aims to understand the relationship between the member angle limit and the energy ratio for 24 test samples of composite beams and CFT square steel tube columns. This work also compares the formula applicability for member angle limit with the previous test result to provide the basic data for the design of composite beam-CFT column. The evaluation of the member angle limit was performed with concrete compressive strength (fC =22.16 MPa, 30.49 MPa), breadth-to-thickness ratio (B/t=25.0, 33.3, 43.5), and axial capacity ratio (N/N0=0, 0.3, 0.4, 0.5) as the main variables of the test samples. For the relationship between the member angle limit (Ru) and the energy ratio (ES/EC ), the test result shows that the energy ratio becomes lower as the axial capacity ratio and the breadth-to-thickness ratio increase. The energy ratio is lower for the Type B test sample compared with that of Types A and C. For the formula suggested by SATO, the test samples are distributed evenly for comparison between test values and the member angle limit; however, other formulas indicate a deviation. Specifically, for the comparison between R u,cal and R u (Test), Maeda's formula shows severe deviation.

Mechanical behavior and failure analysis of brittle sandstone specimens containing combined flaws under uniaxial compression

Based on the axial stress-axial strain curves,the effect of fissure angle on the strength and deformation behavior of sandstone specimens containing combined flaws is analyzed.The mechanical parameters of sandstone specimens containing combined flaws are all lower than that of intact specimen,but the reduction extent is distinctly related to the fissure angle.The results of sandstone specimens containing combined flaws are obtained by the acoustic emission,which can be used to monitor the crack initiation and propagation.The ultimate failure mode and crack coalescence behavior are evaluated for brittle sandstone specimens containing combined flaws.Nine different crack types are identified on the basis of their geometry and crack coalescence mechanism(tensile crack,hole collapse,far-field crack and surface spalling)for combined flaws.The photographic monitoring was also adopted for uniaxial compression test in order to confirm the sequence of crack coalescence in brittle sandstone specimens containing combined flaws,which recorded the real-time crack coalescence process during entire deformation.According to the monitored results,the effect of crack coalescence process on the strength and deformation behavior is investigated based on a detailed analysis for brittle sandstone specimens containing combined flaws by using digital photogrammetry.

Colorectal cancer screening: Comparison of transferrin and immuno fecal occult blood test

AIM: To evaluate the sensitivity and specificity of transfesrrin dipstick test (Tf) in colorectal cancer (CRC) screening and precancerous lesions screening. METHODS: Eight hundreds and sixty-one individuals at high-risk for CRC were recruited. Six hundreds and eleven subsequently received the three fecal occult blood tests and colonoscopy with biopsy performed as needed. Fecal samples were obtained on the day before colonoscopy. Tf, immuno fecal occult blood test (IFOBT) and guaiac fecal occult blood test (g-FOBT) were performed simultaneously on the same stool. To minimize false-negative cases, all subjects with negative samples were asked to provide an additional stool specimen for a second test even a third test. If the results were all negative after testing three repeated samples, the subject was considered a true negative. The performance characteristics of Tf for detecting CRC and precancerous lesions were examined and compared to those of IFOBT and the combination of Tf, IFOBT and g-FOBT. RESULTS: A total of six hundreds and eleven subjects met the study criteria including 25 with CRC and 60 with precancerous lesions. Sensitivity for detecting CRC was 92% for Tf and 96% for IFOBT, specificities of Tf and IFOBT were both 72.0% (95% CI: 68.2%-75.5%; χ2 = 0.4, P > 0.05); positive likelihood ratios of those were 3.3 (95% CI: 2.8-3.9) and 3.4 (95% CI: 2.9-4.0), respectively. In precancerous lesions, sensitivities for Tf and IFOBT were 50% and 58%, respectively (χ 2 = 0.8, P > 0.05); specificities of Tf and IFOBT were 71.5% (95% CI: 67.6%-75.1%) and 72.2% (95% CI: 68.4%-75.8%); positive likelihood ratios of those were 1.8 (95% CI: 1.3-2.3) and 2.1 (95% CI: 1.6-2.7), respectively; compared to IFOBT, g-FOBT+ Tf+ IFOBT had a significantly higher positive rate for precancerous lesions (83% vs 58%, respectively; χ 2 = 9.1, P < 0.05). In patients with CRC and precancerous lesions, the sensitivities of Tf and IFOBT were 62% and 69% (χ 2 = 0.9, P > 0.05); specificities of those were 74.5% (95% CI: 70.6%-78.1%) and 75.5% (95% CI: 71.6%-79.0%); positive likelihood ratios of those were 2.5 (95% CI: 2.0-3.1) and 2.8 (95% CI: 2.3-3.5). Compared to IF-OBT alone, combining g-FOBT, IFOBT and Tf led to significantly increased sensitivity for detecting CRC and cancerous lesions (69% vs 88%, respectively; χ 2 = 9.0, P < 0.05). CONCLUSION: Tf dipstick test might be used as an ad- ditional tool for CRC and precancerous lesions screening in a high-risk cohort.

Study on Complete Analysis of LRE Test Samples Based on PCA

Incomplete data samples have a serious impact on the effectiveness of data mining.Aiming at the LRE historical test samples,based on correlation analysis of condition parameter,this paper introduced principle component analysis(PCA)and proposed a complete analysis method based on PCA for incomplete samples.At first,the covariance matrix of complete data set was calculated;Then,according to corresponding eigenvalues which were in descending,a principle matrix composed of eigen-vectors of covariance matrix was made;Finally,the vacant data was estimated based on the principle matrix and the known data.Compared with traditional method validated the method proposed in this paper has a better effect on complete test samples.An application example shows that the method suggested in this paper can update the value in use of historical test data.

Creep failure mode and criterion of Xiangjiaba sandstone

Based on the results of conventional triaxial compression tests and triaxial compression creep tests on Xiangjiaba sandstone,the failure modes in short-term tests and creep tests,fractography of sandstone after creep failure,short-term and creep failure criterion are analyzed.In the short-term tests and creep tests,the sandstone samples fail in a mix mode consisting of shear failure in a single main plane and tensile failure.Confining pressure can restrict brittle failure and enhance the ductility of sandstone.In the creep tests,brittle fracture is reduced and plastic deformation can fully be developed compared to the condition of short-term tests.And the shear fracture surfaces are flat and they are covered by small particles as a result of friction.When confining pressure increases,particle size decreases while the degree of friction on shear plane increases.On the tensile failure plane,the tensile trace and direction of tearing could be clearly observed.There are obvious tearing steps on the tensile failure plane and tearing laminated structure on the front edge of tearing fracture.The same criterion can be used for the short-term and creep behavior,and the fitting effect using the MOGI criterion is better than the DRUCKER PRAGER criterion.The cohesion and friction angle calculated by the MOGI criterion are in good accordance with those calculated by the MOHR COULOMB criterion.

Potential-Decomposition Strategy in Markov Chain Monte Carlo Sampling Algorithms

We introduce the potential-decomposition strategy （PDS）, which can be used in Markov chain Monte Carlo sampling algorithms. PDS can be designed to make particles move in a modified potential that favors diffusion in phase space, then, by rejecting some trial samples, the target distributions can be sampled in an unbiased manner. Furthermore, if the accepted trial samples are insumcient, they can be recycled as initial states to form more unbiased samples. This strategy can greatly improve efficiency when the original potential has multiple metastable states separated by large barriers. We apply PDS to the 2d Ising model and a double-well potential model with a large barrier, demonstrating in these two representative examples that convergence is accelerated by orders of magnitude.

Comparison of RFFIT Tests with Different Standard Sera and Testing Procedures

The World Health Organization （WHO） standard assay for determining antibody level is the rapid fluorescent focus inhibition test （RFFIT） and is used to determine the degree of immunity after vaccination against rabies. To compare the difference in RFFIT results between the laboratories of The National Institute of Infectious Disease in Japan （NIID） and the Chinese Centre for Disease Control （CCDC） as well the influence of the choice of standard serum （STD） for the detection, the two laboratories detection methods were simultaneously manipulated by RFFIT. The reference serums used in NIID and the WHO standard serum used in CCDC were compared in the same RFFIT detection to determine the titer of four sera samples C1, Sl, S2 and S4 in parallel, and the titers of the detected sera samples were calculated using the standard formula for neutralizing antibody titer. No significant difference was found in RFFIT methods from the two laboratories and the RFFIT testing procedures of the two laboratories have good consistency. However, different titers were obtained with the tentative internal standard serum （TI-STD） produced by adjusting to 2.0 IU of WHO standard serum in NIID and the WHO STD. The titer determined with the TI-STD was higher than that determined with WHO STD, This difference appears to be significant and requires further investigation

Experimental study on complete stress-deformation curves of larger-size concrete specimens subjected to uniaxial tension

In order to provide parameters for numerical analyses of the huge Three-Gorge concrete dam (2309 m long by 175 m height), complete tensile stress-deformation curves for large-size plain concrete specimens were measured and studied by per-forming uniaxial tensile tests on large-size unnotched specimens (250 mm×250 mm×1400 mm). The specimens were prepared with the three-graded-aggregate materials provided by the client of the Three-Gorge project. To prevent a failure occurring near the ends of the unnotched specimens, both the ends of each specimen (450 mm in length) were cast using a higher-strength concrete than the middle part (i.e., active part). Tensile tests were completed on a specially-designed tensile testing machine, which can be easily re-assembled to accommodate different-size specimens. To make the specimens fail stably, a cyclic loading scheme was adopted after the peak strength was reached. Four of five tests in this study were successful, and four complete tensile stress-deformation curves were obtained. It was found that the post-peak curve of the large-size specimens used in this study is more gradual than those for the small-size specimens reported in the literature.

Current State of High 120 m Concrete Dam Bratsk Hydroelectric Power Plant

The research object was high 120 m concrete gravity dam of the Angara Bratsk hydroelectric power plant. The state of the concrete dam is estimated based on the results of continuous supervision performed by site personnel as well as periodic monitoring. According to the classification of the interrelations in the system ＂concrete-environment＂, there were selected some important parts of dams and a comprehensive analysis of concrete was executed on these parts. Concerning the complex research of concrete, a combination of full-scale tests with core-sampling has been proposed. Core samples tests had an object to study the deep concrete layers and to determine the specific indicators such as strength, density, porosity, comparative diameter of capillary pores, CaO content in cement stone and others. Obtained findings and recommended criteria can be applied when selecting technologies for constructing dams that guarantee their durability in the north.

Experimental study on dynamic elastic parameters of coal samples

Dynamic elastic parameters of coal are closely linked to crack characteristics and are lithology indicators in seismic exploration. This experimental study measured ultrasonic wave velocity of coal samples considering both parallel(90°) and perpendicular(0°) to bedding planes, and then calculated the dynamic elastic parameters(Edand ld) and their anisotropy values(AEdand Ald). The variations of Edand ld,as well as AEdand Aldwere analyzed under various confining stresses. The results show that: Firstly, a critical confining pressure exists, and significant variation in the parameters can be seen below this point and weak variation appears above it. Secondly, a positive correlation exists between Edand the square of P-wave velocity(VP2), and between AEdand the P-wave velocity anisotropy(AEP) as well; however, there is no clear correlation between ldand P-wave velocity(VP). Thirdly, according to the major controlling factors of anisotropy, the coal samples with different Edand ldas well as AEdand Aldcan be divided into two types: one is mainly controlled by bedding and cracks and the other one is mainly controlled by differences of mineral compositions in directions. Consequently, this study can provide theoretical basis for future research on the dynamic elastic parameters and anisotropy of coal.

Experimental study on simulation test instrument and its penetration performance of soil infiltration clogging

The three-dimensional seepage simulation test device for siltation dam foundation soil is a multifunctional penetration instrument which is designed for the simulation of infiltration clogging,seepage damage,and dam seepage and so on. This device is different from the traditional instruments for the rock and soil permeability. In order to verify the practicability of the device,the authors collected the soil samples for laboratory penetration test,observed the seepage damage phenomenon,and obtained the dynamic change curve of permeability coefficient and isopotential map of water pressure. At the same time,the Geostudio finite element software is used to simulate the steady seepage of the test device. By contrast of the isopotential maps between simulation and actual water pressures,it is found that they are approximately the same. It is proved that the test data of the device is scientific and reliable,reaching the results of the test and design purposes. The instrument can be used in many aspects of experimental study on soil seepage.

Influence of Hydrostatic Pressure on Compressive Strength of Self-consolidating Concrete

The design of unique chamber, in which the SCUWC （self-consolidating underwater concrete） can be tested under the impact of the hydrostatic pressure from 0.1 MPa to 0.5 MPa, is presented in the paper. The results of the preliminary tests of the effect of the hydrostatic pressure on the compressive strength of SCUWC were shown. The impact of the hydrostatic pressure on the compressive strength values of test specimens has been confirmed. There has been an increase in the strength of the specimens taken from the upper parts of the concrete samples. As it can be seen from the preliminary research, the differences in compressive strength are related to the differences that occur in the size and distribution of air voids in the samples taken from upper and lower parts of the test specimens. On the basis of the carried out investigations of the compressive strength, it can be concluded that the hydrostatic pressure has a favorable effect on the compressive strength of the tested specimens of SCUWC. Increase of the compressive strength is observed mostly in the upper layers of the samples. Preliminary analysis of the quantity and distribution of air pores in the samples of concrete subjected to pressure 0.5 MPa confirms the positive impact of the hydrostatic pressure on the layers close to the surface indicated by the absence of large air voids above 1,500μm and by reducing the quantity of air pores of size above 300μm.

Triaxial mechanical creep behavior of sandstone

Based on laboratory results of time-dependent mechanical behavior tests,we investigated short-term and mechanical creep behavior of sandstone,observed in conventional triaxial compression experiments at room temperature,using a servo-controlled rheology testing machine.Given our short-term experimental test results,we confirmed deviatoric creep stress levels of sandstone.Multiple deviatoric stress levels were applied in steps to each sample.Each deviatoric stress level before the final failed deviatoric stress was maintained for 48 h or longer.Time-dependent variations of axial strains of sandstone samples are discussed and evaluated.During the creep tests,complete tertiary creep curves of sandstone were observed under failed deviatoric stress levels with different confining pressures.Slices of coal in sandstone samples can lead to distinct tertiary creep deformation failure.

Damage Analysis of Circulating Soaked Rock Sample Based on Sonic-test Trials

Circulating soaked sandstone and mudstone samples sonic parameters were tested and analyzed, using RSM-SY5 sonic instrument, the variation between soaked times and the velocity of longitudinal wave and shear wave was studied, calculation and analysis of the damage variable of circulating soaked rock samples were taken, with sonic measurement results and the empirical formula, the damage variable formulas associated with cycle times was established. The results showed that： the attenuation of sonic velocity basically in line with the exponential relationship, with cycle times increasing; The results of the critical calculation of damage variables and the strength test are well matched, which further confirms that the occurrence and expansion of new crack inside the rock mass resulted from circulating soaked lead to the decrease of the rock strength; The trend of sonic parameters attenuation and damage variable growth are good correspondence.

Characteristics and Causes of the Preconsolidation Stress of Soils in the Yellow River Delta

Preconsolidation stress （ σP） is the maximum effective stress that a soil has suffered throughout its life. From a geotech- nical point of view, pre-consolidation stress has great importance because it separates elastic and reversible deformations from inelastic and only partially irreversible deformations and marks the starting point of high compressibility. In this study we calculated the preconsolidation stress for 72 undisturbed soil samples from the Yellow River Delta, using the oedometer test and applying the method proposed by Casagrande. The results showed that the over-consolidation ratio （OCR-the ratio of pre-consolidation stress to current natural overburden stress） values of the soil from soil surface to 6m depth varied from 1.72 to 15.34 and the maximum pre- consolidation stress was above 200 kPa. In consequence, the soils of the Yellow River Delta are highly over-consolidated within the upper 6m, the OCR decreasing gradually with depth from 6 to 12m. For samples from deeper than 12m the soils were found to be under-consolidated, which was proved by standard penetration tests （SPTs）. The main causes of this type of consolidation are the mineral composition and the designability of the soil body.

Experimental study on influence of coal structural anisotropy to gas permeation

Based on ＂true triaxial coal rock permeability of coal sample test system , the permeability under different gas pressure to coal specimen in bedding plane and the vertical bedding directions are tested. The results show that coal structural anisotropy has a greater impact on gas permeability properties, differences in experimental coal permeability are roughly one order of magnitude. In view of the differences of the gas flow characteristics in the coal bedding plane and vertical bedding, established series and parallel choked flow model of coal sample gas seepage, and made a theoretical analysis to the influences of the bedding structure to gas permeability properties.