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ObjectiveTo establish a combined high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） and gas chromatography-mass spectrometry （GC-MS） method to detect the synthetic cannabinoid CUMYL-PEGACLONE in e-cigarette oil and hair.MethodsHPLC-MS/MS and GC-MS were used to establish the detection method of CUMYL-PEGACLONE, and the hair of drug-involved persons and the seized e-cigarette oil were detected.ResultsThe main mass spectrometry characteristic ions m/z of CUMYL-PEGACLONE measured by GC-MS were 91， 179， 197， 254 and 372. CUMYL-PEGACLONE had a good linear relationship in the mass concentration range of 2-50 ng/mL， and the linear correlation coefficient （r） was greater than 0.99. The limit of detection （LOD） of CUMYL-PEGACLONE in hair was 0.01 ng/mg， and the limit of quantitation （LOQ） was 0.02 ng/mg. The LOD of CUMYL-PEGACLONE in e-cigarette oil was 1 ng/mg， and the LOQ was 2 ng/mg. The average recoveries of CUMYL-PEGACLONE under the attempt at high, intermediate and low levels in blank human hair and e-cigarette oil matrix were 98.2%-132.4% and 93.5%-110.6%， and the intraday and intraday precision were 1.2%-12.9% and 0.7%-2.9%. CUMYL-PEGACLONE was detected in the hair of 15 drug-involved persons. Except for 1 person who was lower than LOQ, the concentration of CUMYL-PEGACLONE in the hair of other 14 persons was 0.035-0.563 ng/mg. The mass fraction of CUMYL-PEGACLONE in 2 e-cigarette oil were 0.17% and 0.21%, respectively.ConclusionThe established HPLC-MS/MS and GC-MS methods are applied to the detection of HPLC-MS/MS in drug-related cases， which provides strong evidence support for the handling authority to quickly investigate these cases， and also provides a reference for the identification of such substances in future.

Electromagnetic time-reversal imaging is addressed for a target situated in a cluttered background. We first investigate the theory of electromagnetic time-reversal imaging, followed by an experimental demonstration. A transmitter-receiver antenna array is connected to a network analyzer and applied to transmit wideband waveforms for detecting a target within a cluttered environment. We assume the cluttered background is fixed, thus the target signature is extracted by observing changes manifested by the introduction of a target. A numerical algorithm is required for computation of the Green's function employed within the time-reversal imager, with this implemented here via ray tracing. Example time-reversal images of different cluttered backgrounds and different targets are presented using measured data, with comparisons to a traditional radar imaging technique. Results show that the time-reversal imagery yields good focusing at the target, significantly better than when the background is not accounted for. Index Terms--Imaging, phase conjugation, scattering.

A 2-mm-thick plastic shell with 5-10-mm-thick tapered plastic spacer in the shape of a 'pinna'-specific anthropomorphic mannequin (SAM) head model is being used for determination of the specific absorption rate (SAR) of cellular telephones for compliance testing against IEEE and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) Safety Guidelines used in the U.S. and Europe, respectively. We have used three-dimensional computer-aided design files of the SAM Model with 1-mm resolution to calculate peak 1- and 10-g SAR for 'cheek' and '15[degrees]-tilted' positions of some typical telephones for comparison with those for three anatomic models of the head to show that the SAR obtained for SAM is up to two or more times smaller than for anatomic models. This is due to the shift of the high SAR locations to a low radiated fields region away from the antenna, particularly at 835 MHz, and a substantial physical separation from the absorptive phantom at 1900 MHz. Due to the use of lossless plastic for the 'pinna,' another handicap of the SAM model is the total lack of knowledge of 1- or 10-g SAR in the pinna tissues required by all safety guidelines (current or proposed). To remedy this situation, we propose a modified SAM with a lossy 'pinna,' for which 1- and 10-g SARs are relatively close to those for anatomic models provided we use a fluid of higher conductivity than that currently used for compliance testing at 835 MHz. Lastly, we compare the implications of the current IEEE and ICNIRP guidelines and the newly proposed IEEE guidelines with a relaxed limit of 4.0 W/kg for any 10-g of tissue of the pinna for maximum allowable powers for cellular telephones at 835 and 1900 MHz to show that the newly proposed relaxed IEEE limits will allow radiated powers that may be 8-16 times those permitted by the current IEEE Standard and up to two times higher than those permitted under ICNIRP guidelines used in over 30 countries. Index Terms--Comparison of specific absorption rate (SAR obtained for specific anthropomorphic mannequin (SAM) and anatomic models, considerably lower SAR for SAM, accurate SAR obtained with a proposed modified SAM.

Compliance with 1- or 10-g specific absorption rate (SAR) safety guidelines is required in various countries for all newly-introduced personal wireless devices such as Wi-Fi PCs. Even though the dielectric properties of the human tissues are known to he nonuniform and highly variable, relatively rigid adherence to prescribed dielectric properties ([[epsilon].sub.r], [sigma]) is required for compliance testing of such devices. Using some typical near-field radiators, we have examined the effect of dielectric properties for SAR measurement fluids with conductivities varying by 2 : 1 to show that both 1- and 10-g SARs vary by less than [+ or -] 2%-4% for the 802.11a band 5.15 to 5.825 GHz and only slightly more at the lower 802.11 big frequency of 2.45 GHz. This is due to higher surface SAR but shallower depth of penetration of EM fields for the higher conductivity media resulting in nearly identical SARs for cubical volumes associated with 1- or 10-g of tissue, respectively. Also studied, is the effect of lower [[epsilon].sub.r] fluids recommended in some standards which results in slightly higher and, thus, a conservative assessment of SAR. Index Terms--2 : 1 variation of conductivity, compliance testing, near constancy of specific absorption rate (SAR), wireless PCs.

The paper uses the two methods suggested in both the ICNIRP and proposed IEEE safety guidelines for compliance testing of security systems based on time-varying magnetic fields being introduced for electronic article surveillance (EAS), radio-frequency identification, and other applications. For nonsinusoidal pulses that are often used, the two procedures are to treat the exposure as a multifrequency exposure with various frequency components or to calculate the peak induced current densities or electric fields treating the highest of the pulses of duration [t.sub.p] as a single frequency, half sinusoid of the same duration and frequency 1/(2[t.sub.p]). Using either of the procedures, the induced current densities (J) or electric fields (E) are compared to the basic restrictions on J or E for compliance testing. Using a heterogeneous, tissue-classified anatomic model of the human body, we calculate the induced J and E for the various tissues for a realistic, EAS system for two typical nonsinusoidal pulses to show that the two methods give substantially different results. While the approximate but simpler method of treating the pulse as a half sinusoid results in peak induced J or E that may be compliant with safety guidelines, the rigorous method of treating such exposures as multifrequency exposures gives induced current densities or electric fields that may be up to twice as large, thus making such systems potentially noncompliant with the safety guidelines. Since it is more accurate, it is suggested that safety assessment based on the Fourier analysis leading to multifrequency components be used for compliance testing of such devices. Index Terms--Compliance, EAS systems, induced currents, pulsed exposures, safety guidelines.

The bioheat equation is solved for an anatomically based model of the human head with a resolution of 3 x 3 x 3 mm to study the thermal implications of exposure to electromagnetic (EM) fields typical of cellular telephones both at 835 and 1900 MHz. It is shown that similar to the measured data, up to 4.5 [degrees] C temperature elevation may be caused for locations of the pinna by a cellular telephone warmed by electronic circuitry to temperatures as high as 39 [degrees] C, with temperature increases for the internal tissues such as the brain and eye that are no more than 0.1 [degrees] C-0.2 [degrees] C higher than the basal values. Similar to previous studies by other authors, additional temperature increases due to EM fields of cellular telephones are fairly small and typically less than 0.1 [degrees] C. Another objective was to study the thermal implications of the SAR limits for the occupational exposures of 8 W/kg for any 1 g, or 10 W/kg for any 10 g of tissue suggested in the commonly used safety guidelines. Such specific absorption rates (SARs) would lead to temperature elevations for the electro-magnetically exposed parts of the brain up to 0.5 [degrees] C with 10 W/kg for any 10 g of tissue resulting in somewhat higher temperatures and for larger volumes. Similar temperature increases are also calculated by increasing the arterial blood temperature, except that the temperature increases due to the SAR are for the more limited volume rather than the entire brain. Index Terms--Anatomic model of the head, cellular telephones, safety standards, temperature increase.

A set of novel, grid-robust, higher order vector basis functions is proposed for the method-of-moments (MoM) solution of integral equations for three-dimensional (3-D) electromagnetic (EM) problems. These basis functions are defined over curvilinear triangular patches and represent the unknown electric current density within each patch using the Lagrange interpolation polynomials. The highlight of these basis functions is that the Lagrange interpolation points are chosen to be the same as the nodes of the well-developed Gaussian quadratures. As a result, the evaluation of the integrals in the MoM is greatly simplified. Additionally, the surface of an object to be analyzed can be easily meshed because the new basis functions do not require the side of a triangular patch to be entirely shared by another triangular patch, which is a very stringent requirement for traditional vector basis functions. The proposed basis functions are implemented with point matching for the MoM solution of the electric-field integral equation, the magnetic-field integral equation, and the combined-field integral equation. Numerical examples are presented to demonstrate the higher order convergence and the grid robustness for defective meshes using the new basis functions. Index Terms--Higher order methods, method of moments, point matching, vector basis functions.

A new approach is proposed to reduce the memory requirements of the multilevel fast multipole algorithm (MLFMA) when applied to the higher order Galerkin's method. This approach represents higher order basis functions by a set of point sources such that a matrix-vector multiply is equivalent to calculating the fields at a number of points from given current sources at these points. The MLFMA is then applied to calculate the point-to-point interactions. This permits the use of more levels in MLFMA than applying MLFMA to basis-to-basis interactions directly and, thus, reduces the memory requirements significantly. Index Terms--Fast solvers, Galerkin's method.