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Undetected leakage of fluid hydrocarbons from pipelines or underground storage tanks into the subsurface environment are environmental and public health hazards. It is evident that there is a need for efficient, effective and accurate technology to detect these leaks rapidly and non-destructively, so as to make the process safe, to make quantitative risk assessment, and to provide effective preventive measures. There are unsurmountable limitations in many existing leak detection techniques. Moreover, early detection of leakage would allow rapid remediation at source to significantly reduce the remediation costs, and more importantly the environmental impact. The results of an experimental investigation for the technical feasibility and practicality of a technique for detection and location of fluid hydrocarbon leaks in underground pipelines and storage tanks based on the principles of time-domain reflectometry (TDR) are presented in this paper. The measurement sensitivity of the technique was evaluated for 3 different types of cables, 2 cable configurations (parallel-wires or coaxial), 2 leaking fluids (tap water or petrol), a single leak or double leaks, and 2 backfill materials (fine sand or gravel) by a series of field-scale model tests. The testing parameters were varied systematically. The experimental results indicate that TDR is a technically feasible technique for the detection of fluid hydrocarbon leaks from pipelines and underground storage tanks when the setup configuration is appropriate. [ABSTRACT FROM AUTHOR]

SH and Love waves have certain advantages over P-SV and Rayleigh waves when inverting shear-wave velocity (V S) profiles. They can also supplement Rayleigh waves to provide better model constraints on characterizing anisotropic media. Since the true 3D forward solution of full SH waves requires intensive computation, we propose, in this paper, a simple 2D wavefield solution and further modify it as an efficient pseudo-3D solution. This is achieved by applying an empirical amplitude correction function for geometric attenuation. In the transformed domain, this newly proposed pseudo-3D solution yields a dispersion image (frequency-velocity spectrum, FVS) practically equivalent to that of the true 3D solution which is also developed by the authors. Furthermore, this pseudo-3D solution is significantly more accurate than the modal summation method. Thanks to its fast computation speed and accuracy, the pseudo-3D algorithm is demonstrated to be an excellent surrogate for full wavefield inversion based on FVS. The FVS of SH waves is shown to be much more sensitive to embedded thin weak layers than that of P-SV waves. The superiority of FVS inversion over fundamental mode inversion is further demonstrated by examining their corresponding error functions, showing that FVS provides a much stronger constraint on the possible V S models. Examples demonstrate that the FVS inversion based on the pseudo-3D model outperforms the modal summation approach in both accuracy and generalization. The proposed pseudo-3D solution is quite general. It takes into account the source-to-receiver geometry and deals with special layer profiles where Love-type wave does not exist. • An efficient 2D model is developed and modified to approximate the true 3D dynamic response to a finite shear load. • Full waveform inversion based on the proposed pseudo-3D model in the transformed domain is presented. • The new model considers receiver locations and special conditions where the Love-wave dispersion curve does not exist. • Unique and advantageous characteristics of the transverse-loaded dynamic response are revealed. [ABSTRACT FROM AUTHOR]

Ixeris chinensis (Thunb.) Nakai (Taiwan) is a traditional herbal medicine used for treating various ailments, such as stomach ache, common cold and diarrhoea. The objective of the present study was to evaluate the antioxidative, anti-inflammatory and anti-adhesive effect of I. chinensis on Helicobacter pylori ( H. pylori )-induced gastric adenocarcinoma in an AGS cell model. Three types of I. chinensis extract were used: boiling water extract (BWE), ethanol extract (EE) and chloroform extract (CE) to check anti- H. pylori activity on the AGS cell line. Phytochemical and HPLC analysis were performed. In vitro antioxidant activity, including TEAC, DPPH and H 2 O 2 scavenging abilities, was evaluated. In addition, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined, and an MTT assay determined survival rate. Furthermore, interleukin-8 (IL-8), tumor necrosis factor (TNF-α) and nitric oxide (NO) levels were measured. The BWE showed better antioxidative activity than the EE and CE. The lag time of human low-density lipoprotein (LDL) oxidation was significantly increased by BWE, EE and CE. However, CE showed maximum antibacterial (MIC, MBC), anti-adhesive (urease test) and anti-inflammatory (IL-8, NO, TNF-α) activities. Based on the above findings, I. chinensis extract (BWE and CE) clearly shows antioxidative, anti-inflammatory and anti-adhesive effects on H. pylori -induced gastric adenocarcinoma in the AGS cell model. Hence, I. chinensis might be used to combat against H. pylori- induced gastric cancer with standard chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

The data reduction method for dispersion relation in surface wave testing is conventionally associated with the certain method of data acquisition, for example, phase shift analysis in the two-station SASW method and 2-D multi-station wavefield transformation of surface wave in the MASW method. The fundamental difference in dispersion analysis between the 2-station and multi-station approach was clarified in this study. Limited to the two channel data, conventional dispersion analysis of SASW suffers from possible phase un-wrapping errors, inefficient data filtering and synthesis, and inability to distinguish multiple modes. The MASW approach, on the other hand, can avoid these problems and provide visualization of dispersion relation through 2D wavefield transformation. As opposed to multiple shots in the SASW testing, the MASW testing typically uses only single shot, limiting the obtainable wavelengths due to near field and far field effects. Combining the merits of these two methods, a multi-shot common receiver configuration survey is proposed to acquire multi-station wavefield for 2D wavefield transformation using as few as two receivers. An additional benefit of the multi-shot common receiver configuration is shown to be better control and higher lateral resolution of the measurement range. [ABSTRACT FROM AUTHOR]

Surface wave testing is considered a promising method for assessing average property and actual area replacement ratio of ground modification with improvement columns, owing to its non-destructive nature and large sampling range. However, the surface wave method is essentially a 1-D method assuming horizontally-layered medium. What it measures in highly heterogeneous improved ground remains to be investigated. This study aimed at evaluating the feasibility of surface wave method in the heterogeneous ground with improved columns, and investigating the homogenization of shear wave velocity and the lateral sampling range. Field tests on a jet grouted construction site showed that the surface wave method worked well in such heterogeneous grounds and yielded a site-representative shear wave velocity profile regardless of the survey location. This is attributed to the survey condition where the wavelength is greater than the spacing of grout columns. 1-D analytical models and 2-D numerical simulations were conducted to investigate the quantitative relation between construction parameters and the percentage increase of shear wave velocity after ground improvement. A quantitative approach to estimate the area replacement ratio and overall quality of improvement columns by surface wave testing is proposed. [ABSTRACT FROM AUTHOR]

Inversion of subsurface shear-wave velocity profile based on effective dispersion curve or full wavefield is still rare due to the lack of efficient forward computation kernel for the full wavefield in a layered medium. To facilitate exploiting the complete signal content in seismic testing, an efficient new computational framework for modeling synthetic full wavefields in horizontally layered systems is proposed. Dynamic response of an isotropic elastic layered system subjected to vertical loading is implemented and thoroughly validated. The new procedure is based the Fourier-Bessel series expansion (not the traditional Fourier-Bessel transform), and it is at least two-orders faster than the current full wavefield computation method based on integral transformation. It considers survey parameters and models all wave phenomena, including near-field effect and leaky waves, which cannot be captured by the modal summation method. Examples of full wavefield simulation are presented to demonstrate different levels of information provided by the experimentally available fundamental mode, broadband effective dispersion curve, and the full velocity spectrum. Different earth models may have similar fundamental modes or even effective dispersion curves; however, their difference manifests in different higher-mode contributions and can only be exploited by utilizing the entire velocity spectra including the vertical and radial components. The coupling between the vertical and radial components in terms of their spectral ratio and phase difference can provide additional constraints (data) in seismic testing. • Loading within a circle, instead of a point force, is used for better mimicking the surface testing load. • The computationally efficient finite Fourier-Bessel summation, instead of Hankel integral, is proposed. • Solution for vertical load using the stiffness matrix is presented, which can be easily extended to other loading conditions. • The full-wavefield solution reveals the important effects of near field, leaky and lateral waves, and radial-to-vertical characteristics. [ABSTRACT FROM AUTHOR]

Abstract: The surface wave (S-wave) method has gained popularity in engineering practice for determining S-wave velocity depth profiles. A growing trend is towards the application of S-wave testing for spatially 2-D S-wave velocity tomography, ignoring the assumption of horizontally layered medium. A fourth-order velocity-stress finite difference method is used to perform numerical simulations of S-wave testing in earth models with lateral variation. Results show that the lateral heterogeneity induces a non-stationary property in the space domain, resulting in false depth-related dispersion or higher modes if conventional approach based on stationary assumption is used for the dispersion analysis. Artifacts maybe introduced in spatially 2-D S-wave velocity imaging if the effect of lateral heterogeneity is not accounted for. As a potential countermeasure, a high-lateral-resolution S-wave method is proposed to reduce the effect of lateral heterogeneity while maintaining the resolution and depth range of dispersion analysis. It consists of a walk-away survey and a phase-seaming procedure when synthesizing seismograms with different nearest source-to-receiver offset, allowing wide-wavelength dispersion analysis within a small spatial range. The proof of concept is given with several numerical examples. They show that the high-resolution S-wave method can greatly alleviate the effect of lateral heterogeneity and increase spatial resolution. [Copyright &y& Elsevier]

Methods based on multi-station recordings are presented for constructing the experimental dispersion curve of Rayleigh waves. Multi-station recording permits a single survey of a broad depth range, high levels of redundancy with a single field configuration, and the ability to adjust the offset, effectively reducing near field and far field effects. A method based on the linear regression of phase angles measured at multiple stations is introduced for determining data quality and filtering criteria. This method becomes a powerful tool for on site quality control in real time. The effects of multiple modes and survey line parameters, such as near offset, receiver spacing, and offset range, are investigated. Parametric studies result in general guidelines for the field data acquisition. A case study demonstrates how to easily deploy commonplace seismic refraction equipment to simultaneously record data for P-wave tomographic interpretation and multi-station analysis of surface wave. [Copyright &y& Elsevier]

The multi-channel analysis of surface wave (MASW) method is a non-invasive method recently developed to estimate shear wave velocity profile from surface wave energy. Unlike conventional SASW method, multi-station recording permits a single survey of a broad depth range and high levels of redundancy with a single field configuration. An efficient and unified wavefield transform technique is introduced for dispersion analysis and on site data quality control. The technique was demonstrated in the assessment of soil liquefaction potential at a site in Yuan Lin, Taiwan. The shear wave velocity and liquefaction potential assessments based on MASW method compares favorable to that based on SCPT shear wave measurements. Two-dimensional shear wave velocity profiles were estimated by occupying successive geophone spreads at several sites in central western Taiwan, at some of which sand boils or ground cracks occurred during 1999 Chi Chi earthquake. Liquefaction potential analysis based on MASW imaging was shown to be effective for estimating the extent of potential liquefaction hazard. [Copyright &y& Elsevier]

• Verify the feasibility of a new measurement system for broadband complex dielectric permittivity with a single probe that integrates LCR meter (20 Hz–2 MHz) and time domain reflectometry (1 MHz–1 GHz). • The selected electrode materials and the conductivity of the materials under testing are critical factors regarding the electrode polarization in low-frequency measurements. • The reflection decoupled ratio (RDR) method is robust to process time domain reflectometry data and provide spectra in varying dispersion ranges within 1 MHz–1 GHz. A pragmatic approach to probe setup is desired for broadband dielectric measurement and monitoring. We propose and validate the utilization of a single probe that integrates two different convenient instruments for measuring the complex dielectric permittivity across complementary frequency ranges. The aim is to acquire a broad-spectrum complex dielectric permittivity, thereby providing more information about the tested materials. We deploy an LCR meter with a two-electrode configuration (impedance spectroscopy) to span 20 Hz–2 MHz ranges and time domain reflectometry (TDR) with the reflection decoupled ratio (RDR) method to achieve a spectrum around 1 MHz–1 GHz. The results suggest: 1) the selected electrode materials and the conductivity of the materials under testing are critical factors regarding the electrode polarization in low-frequency measurements, 2) the reflection decoupled ratio (RDR) method can provide spectra in varying dispersion ranges, 3) the feasibility of the measurement system for a broadband complex dielectric permittivity is verified. [ABSTRACT FROM AUTHOR]

• Fourier-Bessel series system of vector functions is used to decouple the equations. • Dual-variable and position method is employed for multilayered system. • Poroelastic Green's function due to vertical ring load is derived. • Indentation problem is solved via the least-square formulation. • Discrete Love numbers are used to reduce the calculation time. Poroelastic materials are common in nature and have applications in many engineering fields. In this paper, we derive a general solution of indentation over a multilayered half-space consisting of transversely isotropic and poroelastic materials. The rigid disc-shaped indenter is subjected to a vertical force of Heaviside time-variation. The solution is expressed in terms of the recently introduced powerful Fourier-Bessel series (FBS) system of vector functions combined with the unconditionally stable dual-variable and position method for dealing with layering. Since the problem is a mixed boundary-value one, the Green's functions due to a vertical ring-load are first derived which are then utilized in the integral least-square formulation to derive the solution. In terms of the FBS method, the expansion coefficients, which are further called Love numbers, are discrete, and therefore can be pre-calculated and used repeatedly for different field points on the surface. As such, the solution based on the new FBS method is more efficient and accurate than previous integral-transform methods. This new FBS method is particularly attractive when dealing with mixed boundary-value problems where time-variation is further involved. Numerical examples are conducted to validate the accuracy of the proposed solution and to demonstrate the effects of material layering, geometry, and hydraulic boundary conditions on the contact performance of the material system. [ABSTRACT FROM AUTHOR]

Nd-substituted bismuth titanate (Bi3.5Nd0.5Ti3O12, BNdT) films were prepared on Pt electrodes using chemical solution deposition. Enhanced a-axis-oriented crystal growth occurred when the crystallization was performed on every spin-coated layer with sufficiently thin thickness (∼20 nm). The remnant polarization (2Pr∼38 μC/cm2) of the film derived by such a layer-by-layer crystallization method was significantly higher than that of the film derived with the conventional process (2Pr∼10 μC/cm2). Examination of structural evolution has indicated that, owing to the geometrical effect, the growth of (1 1 7)-oriented crystals was restricted by the layer thickness, while the growth of a-axis-oriented crystals was not. As a result, BNdT films prepared by layer-by-layer crystallization are dominated by a-axis-oriented crystals and show high remnant polarization. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to investigate the anticancer effect of aloe-emodin, an anthraquinone compound present in the leaves of Aloe vera, on two distinct human gastric carcinoma cell lines, AGS and NCI-N87. We demonstrate that aloe-emodin induced cell death in a dose- and time-dependent manner. Noteworthy is that the AGS cells were generally more sensitive than the NCI-N87 cells. Aloe-emodin caused the release of apoptosis-inducing factor and cytochrome c from mitochondria, followed by the activation of caspase-3, leading to nuclear shrinkage and apoptosis. In addition, exposure to aloe-emodin suppressed the casein kinase II activity in a time-dependent manner and was accompanied by a reduced phosphorylation of Bid, a downstream substrate of casein kinase II and a pro-apoptotic molecule. These preclinical studies suggest that aloe-emodin represents a suitable and novel chemotherapeutic drug candidate for the treatment of human gastric carcinoma. [Copyright &y& Elsevier]