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Two new lupane-type triterpenes, 24β-hydroxylupenone (1) and 3β-hydroxy-lup-20(29)-en-24-al (2), and two new ursane-type triterpenes, 28-formyloxy-3β-hydroxy-urs-12-ene (3) and 28-formyloxy-3β-acetoxy-urs-12-ene (4), together with 26 known triterpenes (5-30) were isolated from the leaves and trunk of Ilex cornuta Lindl. The structures of the new compounds were determined by spectroscopic methods, including 1D, 2D NMR (COSY, HMQC, HMBC, and NOESY), and HRMS data. Key words: Ilex cornuta, Aquifoliaceae, triterpene. Resume : L'extraction des feuilles et du tronc de Ilex cornuta Lindl. a permis d'isoler deux nouveaux triterpenes de la famille du lupane, la 24p-hydroxylupenone (1)etleβp-hydroxylup-20(29)-en-24-al (2), deux nouveaux triterpenes de la famille de l'ursane, le 28-formyloxy-3-β-hydroxyurs-12-ene (3) et le 28-formyloxy-3-β-acetoxyurs-12-ene (4) ainsi que vingt-six triterperenes connus (5-30). Les structures des nouveaux composes ont ete determinees par des methodes spectroscopiques, dont des donnees de RMN 1D et 2D [spectroscopie de correlation ('COSY'); correlation de liens multiples heteronucleaires ('HMBC'); correlation multiquantique heteronucleaire ('HMQC'); spectroscopie de l'effet Overhauser nucleaire ('NOESY')] et des donnees de spectrometrie de masse a haute resolution (SM-HR). [Traduit par la Redaction] Mots-cles: Ilex cornuta, Aquifoliacee, triterpene., Introduction Ilex cornuta Lindl. (Aquifoliaceae) is an evergreen shrub widely distributed in Korea and China, and is known as Chinese holly. (1) This indigenous plant has been used in Chinese [...]

Two new cyclopropanoic fatty acid glycosides, named parisveroside A (1) and parisveroside B (2), were isolated from a MeOH extract of the roots of Paris verticillata (Liliaceae) together with three other known compounds, salicin (3), 3-(β-D-glucopyranosyloxymethyl)-2-(4-hydroxy-3-methoxyphenyl)-5- (3-hydroxypropyl)-7-methoxy-(2R,3S)-dihydrobenzofuran (4), and allantoin (5). Their structures were elucidated on the basis of spectroscopic data, including 1D and 2D NMR, HR-FAB-MS, and chemical evidence. To investigate the antineuroinflammatory effects of the isolated compounds (1-5), nitric oxide (NO) production was evaluated in the lipopolysaccharide-activated microglia cell line, BV-2. Compounds 2 and 4 significantly inhibited NO production with [IC.sub.50] values of 74.8 and 60.5 µmol/L, respectively. Key words: Paris verticillata, Liliaceae, fatty acid glycosides, parisveroside A, parisveroside B, neuroinflammation. Utilisant comme produit de depart le melange obtenu par extraction des racines de Paris verticillata (Liliaceee) a l'aide de methanol, on a isole; deux nouveaux glycosides deriveis de l'acide gras cyclopropanoique, soit le parisveroside A (1) et le parisveiroside B (2), ainsi que trois autres produits connus, la salicine (3), le (β-D-glucopyranosyloxymeithyl)-2(4-hydroxy-3-methoxypheenyl)-5- (3-hydroxypropyl)-7- meithoxy-(2R,3S)-dihydrobenzofurane (4) et l'allantoine (5). On a elucide les structures en se basant sur des preuves chimiques et des donnees spectroscopiques, dont celles des RMN 1D et 2D et de la spectrometrie de masse a haute resolution avec bombardement avec des atomes rapides (SM-HR-BAR). Pour etudier les effets anti-neuroinflammatoires des composes isoles, on a evaluee la production d'oxyde d'azote (NO) dans des cellules BV-2 de la lignee cellulaire de microglie activeie par un lipopolysaccharide. Les composes 2 et 4 inhibent d'une facon significative la production de NO avec des valeurs de [IC.sub.50] de 74,8 et 60,5 µmol/L respectivement. Mots-cles : Paris verticillata, Liliaceie, glycosides d'acides gras, parisveroside A, parisveroside B, neuroinflammation., Introduction The genus Paris consists of less than two dozen herbaceous plants that have 4- to 11-merous flowers. (1) Some Paris species are used in traditional Chinese medicine for their [...]

We report the measurement results of signal and noise characteristics induced by the direct x-rays in an indirect-conversion CMOS photodiode array detector. In order to isolate the signal and noise due to the direct x-rays from those due to the optical photons, we inserted a light-absorbing blackout material between a phosphor screen and the photodiode array. From the images irradiated with and without the blackout paper, the signal and noise characteristics due to the optical photons emitted from a phosphor screen were estimated. For the analysis of the measurements, we have developed a model describing the signal and noise transfers based on the cascaded linear-systems approach. The measured results show the direct x-ray is very harmful to the detector performances, such noise power spectrum (NPS) and signal-to-noise ratio (SNR). However, from the theoretical estimation, the degradation of NPS and SNR would not be due to the directly absorbed x-ray photons, but we believe that other sources, such as Compton and photoelectric scattered rays from a scintillator, a photodiode passivation layer or bulk substrate, are main causes. Index Terms--Cascaded system analysis, image quality, noise power spectrum, radiography.

We report the observation of performance degradation in a detector consisting of a phosphor screen and a CMOS (complementary metal-oxide-semiconductor) photodiode array under the continuous irradiation of 45-kVp x-rays. The performance was assessed in terms of dark pixel signal, dynamic range, modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). From the measurement results, it has been observed that the increase of dark pixel signal and the related noise gradually reduces the dynamic range as the cumulative input exposure to the detector increases. Severe degradation in NPS was observed, which gives rise to reduction in DQE as the cumulative input exposure increases. With carefully updated offset and gain correction, however, we can overcome the detrimental effects of increased dark current on NPS and DQE. Index Terms--CMOS detector, CMOS devices, detective quantum efficiency, digital radiography, fiat-field correction, image evaluation, image sensors, noise-power spectrum, radiation effects, X-ray imaging.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chb.2008.11.001 Byline: Ho-Kyung Kim, Keith E. Davis Keywords: Anxiety; Flow; Problematic Internet use; Self-esteem; Sensation-seeking; Theory Abstract: Problematic Internet use (PIU) has long been a matter of public concern. Study 1 examined the correlates of a well-validated measure of Internet addiction [Young, K. S. (1998). Caught in the net. New York: John Wiley and Sons] with 315 students (39% male). Hierarchical regression analyses indicated that low self-esteem, unrealistic optimism, and the importance of 7-positive activities (I7PA) all contributed to the prediction of PIU. The inclusion of controls for aspects of Internet uses and demographic characters showed a clear distinction between PIU and frequent Internet use. Subjects who anticipated that negative outcomes were more likely to happen to them than to peers were none-the-less more likely to engage in PIU. The more important positive activities were, the greater the PIU. SEM model suggested that unrealistic optimism was best treated as part of PIU and that low self-esteem and the I7PA were the powerful predictors of PIU. Study 2 tested SEM models of psychosocial characteristics with 279 students (48% male). Anxiety and flow were added as predictors and the felt safety for social contacts was added to Global PIU following Caplan [Caplan, S. E. (2002). Problematic Internet use and psychosocial well-being: Development of a theory-based cognitive-behavioral measurement instrument. Computers in Human Behavior, 18, 553-575]. The more complex model provided excellent fit and showed that low self-esteem, anxiety, and the I7PA were positively related to PIU. The relationship both of flow and sensation-seeking was mediated by the 17PA. Research on the topic has been relatively atheoretical. We propose a theoretical template to guide future research on PIU. Author Affiliation: School of Journalism and Mass Communications, University of South Carolina, Columbia, SC 29208, USA

We have modeled the signal and noise propagation in a pixelated scintillator detector by using the cascaded linear-systems transfer theory. The main difference from the conventional homogeneous scintillator detector is the additional x-ray quantum sampling process at the beginning stage of the cascaded model. The additional sampling stage is expressed as a multiplication of the fill factor of the pixelated scintillator both in signal and noise. The numerical simulation shows that, while the detective quantum efficiency (DOE) degrades in the low spatial-frequency band due to the x-ray quantum sampling, the DQE maintains high values in the high-frequency band, which is due to the band-limited modulation-transfer function (MTF) property of the pixelated scintillator. The pixelated scintillator design is relatively insensitive to additive electronic noise in the DQE performance compared to the conventional design. As a potential solution to overcome the reduction of DQE in the low-frequency band with the pixelated scintillator design, we propose a partially pixelated scintillator design, which utilizes the concept of pre-filtering before the sampling process of the incident x-ray quanta. Index Terms--cascade model, detective quantum efficiency, linear-systems transfer theory, pixelated scintillator.

For [Gd.sub.2][O.sub.2]S:Tb granular phosphor screens having a wide range of mass thicknesses, we have investigated the fundamental imaging performance in terms of modulation-transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE). As an optical photon readout device, a CMOS photodiode array with a pitch of 48 [micro]m was used. Under the representative radiation quality, RQA 5, recommended by the IEC (International Electrotechnical Commission, Report 1267), the MTF was measured using a slanted-slit method to avoid aliasing and the NPS was determined by two-dimensional (2D) Fourier analysis of white images. The DQE was assessed from the measured MTF, NPS and the estimated photon fluence. Figure-of-merit (FOM) curves are presented to describe the tradeoff between the X-ray sensitivity and spatial resolution of screens as a function of mass thickness. This study will be useful for the selection guidance of [Gd.sub.2][O.sub.2]S:Tb phosphors for the relevant imaging tasks of digital radiography. Index Terms--Detective quantum efficiency, digital radiography, granular phosphor, modulation-transfer function, noise-power spectrum.

We have applied a flat-panel detector to an X-ray cone-beam micro computed tomography (micro-CT) for small-animal imaging. The flat-panel detector consists of an active matrix of transistors and photodiodes with a pixel pitch of 50 [micro]m and a thallium-doped cesium iodide (CsI:TI) scintillator as an X-ray-to-light conversion layer. The detector was fabricated with a complementary metal-oxide-semiconductor (CMOS) technology capable of a submicrometer design line width, hence, it has a pixel fill-factor as high as ~80%. In addition, the detector has a very fast response characteristic with an image lag less than 0.3% in the frame integration time of 5 s. The CMOS flat-panel detector has been tested in terms of modulation transfer function, noise power spectrum, and detective quantum efficiency. Tomographic imaging performances of the micro-CT system, such as voxel noise, contrast-to-noise ratio, and spatial resolution, have also been evaluated by using various quantitative phantoms. Experimental results of euthanized laboratory rat imaging suggest that the micro-CT system employing a CMOS flat-panel detector can be greatly used in small-animal imaging. Index Terms--Flat-panel detector, microtomography, small-animal imaging.

A geometrically nonlinear buffeting analysis of a cable-stayed bridge in the time domain is described. The bridge structure is modeled with three-dimensional thin-walled beam elements and three-dimensional elastic catenary cable elements. Spatially correlated wind velocity fluctuations are modeled and simulated using an algorithm for generating sample functions of a stationary, multivariate stochastic process according to its prescribed cross-spectral density matrix. Aerodynamic damping and aerodynamic stiffness are formulated based on experimentally determined flutter derivatives. The focus of this paper is on the effect of fluctuating components of the spatially correlated wind velocity on the geometrically nonlinear buffeting response for an 870 m cable-stayed bridge. CE Database subject headings: Buffeting; Bridges, cable-stayed; Wind velocity; Simulation; Geometric nonlinearity.

This study examines the fragility curves of a bridge by two different analytical approaches; one utilizes the time-history analysis and the other uses the capacity spectrum method. The latter approach is one of the simplified nonlinear static procedures recently developed for buildings. In this respect, a sample of 10 nominally identical but statistically different bridges and 80 ground-motion time histories are considered to account for the uncertainties related to the structural capacity and ground motion, respectively. The comparison of fragility curves by the nonlinear static procedure with those by time-history analysis indicates that the agreement is excellent for the state of at least minor damage, but not as good for the state of major damage where nonlinear effects clearly play a crucial role. Overall, however, the agreement is adequate even in the state of major damage considering the large number of typical assumptions under which the analyses of fragility characteristics are performed.

A cost-effective digital radiographic system with a large field-of-view (FOV) of 17' x 17' has been developed. The cascaded imaging system mainly consists of three parts: 1) a phosphor screen to convert incident X-rays into visible photons; 2) a matrix of 8 x 8 array of lens assembly to efficiently collect visible photons emitted by the phosphor screen; and 3) 8 x 8 complementary metal-oxide-semiconductor (CMOS) image sensors, aligned to the corresponding lens assembly. Although low in cost due to economical CMOS image sensors, the overall performance features are comparable with other commercial digital radiographic systems. From the analysis of signal and noise propagation, the system is not an 'X-ray quantum-limited' system, rather the system has secondary quantum sink at the light collecting stage. The system resolution is about 2 line pairs per millimeter from both of measured from X-ray images of a line-pair test pattern and the calculation of the modulation-transfer function. Detailed experimental and theoretical analysis of performance will be discussed. Index Terms--Complementary metal-oxide-semiconductor (CMOS), digital radiography (DR), parallel-hardware architecture, X-ray imaging.

High-resolution and three-dimensional X-ray imaging is becoming more and more popular. An X-ray microtomographic system with a CMOS image sensor has been developed. We have developed a novel area X-ray detector with a cost-effective CMOS image sensor. The sensing area of the detector is 55 x 55 [mm.sup.2] and the light from the phosphor screen is collected to the CMOS image sensor by a carefully designed optical system. Six lenses are assembled to reduce the radiation damage effect and increase the resolution and sensitivity. A microfocus X-ray tube that can reach up to 5 [micro]m of focal spot size and microprecision motor system that can move in x-y-z directions for both alignment and magnification and rotate the object have been adopted. A conventional three-dimensional cone-beam Feldkamp reconstruction algorithm was used and a human cancellous bone has been imaged with this system. Currently, the resolution of this system is about 40 [micro]m but the application in microtomography seems very promising using this CMOS X-ray detector. Index Terms--CMOS, cone-beam CT, micro-CT, microtomography, X-ray detector.

The Bremsstrahlung spectrum from a 6-MV linear accelerator (LINAC) was obtained and used as an input X-ray source in the simulation to estimate several important physical quantities of the detector in a therapeutic X-ray portal imaging system, such as quantum and energy absorption efficiencies, Swank factor, and detective quantum efficiency (DQE). In addition, we have obtained a spatial distribution of energy deposit within the detector, resulting in a spatial-frequency-dependent DQE. From the simulation results, it is found that the use of metal plate largely enhances the energy absorption, leading to a large output signal. However, considering the noise properties, the presence of a metal plate degrades the DQE at nonzero spatial frequencies because the detector absorption noise is dominated by the quantum absorption. We have verified our simulation results by comparison with experimental measurements and results from other works.