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[en] Objective: To evaluate the predictive value of 18F-fluorodeoxyglucose (FDG) and 18F-fluorothymidine (FLT) PET in monitoring the metastatic potential of human colorectal cancer (CRC). Methods: Human CRC cell lines SW480 and SW620 were cultured and implanted into nude mice to create CRC models. Tumor growth, metastatic status and survival were assessed in CRC bearing mice. Uptake of 18F-FDG and 18F-FLT in SW480 and SW620 cells was detected In vitro at 0, 30, 60, 90, 120 min after incubation. PET images of both tracers were acquired for SW480 and SW620 tumor-bearing mice using the small animal PET at 60 min after tracer injection. Region of interest (ROI) was drawn using Image J software on reconstructed PET images. Immunocytochemistry and Western blot analysis of the tumor tissue were performed. The correlation between tracer uptake and tumor marker expression was evaluated using linear regression. Results: Compared with SW620 tumor-bearing mice, SW480 induced tumor grew much faster (t = - 3.332, P = 0.004), the tumor-bearing mice had more serious dyscrasias (t = 2.240, P = 0.038 ), shorter survival and higher metastatic rate. In vitro study, the uptake of both 18F-FDG and 18F-FLT in SW620 cells was lower than that in SW480 cells. 18F-FLT uptake was higher than 18F-FDG uptake in both SW480 and SW620 cells. After incubation for 60 min,the uptake of 18F-FDG in SW480 and SW620 cells was (1.76 ± 0.87)% and ( 1.14 ± 0.38 )%, respectively (t = -2.507, P = 0.021); while the uptake of 18F-FLT in SW480 and SW620 cells was (5.21 ± 1.60)% and (2.90 ± 1.82)%, respectively (t =3.497, P =0.002). In micro-PET study, the 18F-FDG radioactivity ratio of tumor to non-tumor (T/NT) in SW480 and SW620 tumors was 2.69 ± 0.98 and 3.09 ± 1.26 respectively (t =0.657, P =0.524); while T/NT of 18F-FLT in SW480 and SW620 tumors was 3.65 ±0.51 and 2.22 ±0.42 (t =6.491, P <0.001), respectively. In immunocytochemistry and western blot assay, heat shock protein(HSP) 27, Integrin β3, vascular endothelial growth factor receptor 2 (VEGFR2) and Ki67 were all over expressed in two kinds of tumor cells with different intensities. HSP27 and Integrin β3 expression was higher in SW480 cells than that in SW620 cells. While VEGFR and Ki67 expression was lower in SW480 cells than that in SW620 cells. The uptake of 18F-FLT closely correlated with the expression of HSP27 (r =0.924, P =0.004) and Integrin β3 (r=0.813, P =0.025). 18F-FDG uptake inversely correlated with the survival of tumor-bearing mice (r =0.500, P=0.017). Conclusions: The uptake of 18F-FDG and 18F-FLT may reflect different biological characteristics of CRC. High 18F-FLT uptake in CRC on PET scan may predict high metastatic tendency. (authors)
[en] Objective: To evaluate whether 18F-fluorothymidine (FLT) can be used to monitor early response to irradiation in colorectal cancer (CRC). Methods: SW480 cells were cultured and irradiated with 0, 10, and 20 Gy. Twenty-four hours later, morphological changes, apoptosis, necrosis, proliferation, and cell cycle phases were observed. Uptake of 18F-FLT was measured in these tumors in vitro from 24 h to 72 h after irradiation. The one-way analysis of variance was used to analyze the data. Results: Apoptotic and necrotic cells were detected 24 h after radiotherapy. SW480 cells proliferation was significantly delayed after irradiation in 3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenylte-trazolium bromide (MTT) assay. Cell cycle analysis showed that SW480 cells had a decreased fraction of cells in S phase (from 33.23% to 9.24%, then to 5.43%) and an arrested fraction in G0-G1. After SW480 cells were cultured for 60 min, the uptake of 18F-FLT was (5.21±1.60)%; and 24 h after irradiation of 10 Gy, the uptake decreased significantly to (4.27±0.48)% (F=8.253, P=0.009). And 72 h after irradiation, the uptake further decreased significantly to (3.39±0.59)% (F=36.715, P<0.001). In tumor tissue, the uptake of 18F-FLT reduced significantly 72 h after radiotherapy (10 Gy: F=12.388, P=0.007; 20 Gy: F=16.744, P=0.004) and the attenuation degree increased with the radiation dose. Conclusion: The uptake of 18F-FLT in SW480 cells or in CRC could reflect the changes of SW480 cells in proliferation, cell cycle re-distribution, cell apoptosis and necrosis. The results suggest that 18F-FLT may used for monitoring early response to irradiation of CRC. (authors)
[en] Under a large signal drive level, a frequency domain black box model of the nonlinear scattering function is introduced into power FETs and diodes. A time domain measurement system and a calibration method based on a digital oscilloscope are designed to extract the nonlinear scattering function of semiconductor devices. The extracted models can reflect the real electrical performance of semiconductor devices and propose a new large-signal model to the design of microwave semiconductor circuits.
[en] We report a photoluminescence (PL) energy red-shift of single quantum dots (QDs) by applying an in-plane compressive uniaxial stress along the  direction at a liquid nitrogen temperature. Uniaxial stress has an effect not only on the confinement potential in the growth direction which results in the PL shift, but also on the cylindrical symmetry of QDs which can be reflected by the change of the full width at half maximum of PL peak. This implies that uniaxial stress has an important role in tuning PL energy and fine structure splitting of QDs
[en] Integration of magnetic passive components into package has been attracting more interests recently, but efficient package-compatible magnetic materials are needed. We have developed a package-compatible granular material, CoFeHfO, on a printed circuit board by reactive sputtering and investigated the substrate dependence of its soft magnetic property. Atomic force microscopy and grazing incidence x-ray-scattering-diffraction spectra show that a rough substrate surface degrades the magnetic property of CoFeHfO thin films with almost the same crystal microstructure. With surface planarization by chemical-mechanical polishing, soft magnetic material CoFeHfO can be realized on the package substrate. This material is promising for future applications in package
[en] Rice-straw burning is a common post-harvest practice on rice paddy land, which results in the accumulation of rice-straw ash (RSA) in paddy soil. Because the occurrence of RSA in soil may affect the fate and transport of contaminants, this study investigated the sorption of 3-chlorophenol (3-CP) on RSA and RSA amended soils to evaluate the sorptive properties of RSA in soils. The results showed that the sorption of 3-CP to RSA proceeds through a surface reaction rather than through partitioning and that the neutral form of 3-CP is preferentially sorbed to the surface when compared to the deprotonated anionic form of 3-CP. The addition of RSA to the soils enhanced the overall 3-CP sorption, indicating that RSA amendment may be applied to retard the movement of 3-CP in contaminated soils. As the RSA content in the soils was increased from 0% to 2%, the Langmuir sorption maximum of the soils increased from 18-80 to 256-274 mg kg-1. Thus, RSA contributed more to the total sorption of the soils than other major components in the soils. Nonetheless, the 3-CP sorption of the soils containing RSA was less than the combination of pure RSA and the soils, thereby indicating that the 3-CP sorption of RSA was suppressed. This may be attributed to the competition of organic matter or other soil components for the surface binding sites of RSA.
[en] Optical observations of 100 nm metallic magnetic nanoparticles are used to study their magnetic field induced self assembly. Chains with lengths of tens of microns are observed to form within minutes at nanoparticle concentrations 1010/mL. Chain rotation and magnetophoresis are readily observed, and SEM reveals that long chains are not simple single particle filaments. Similar chains are detected for several 100 nm commercial bio-separation nanoparticles. We demonstrate the staged magnetic condensation of different types of nanoparticles into composite structures and show that magnetic chains bind to immuno-magnetically labeled cells, serving as temporary handles which allow novel magnetic cell manipulations.
[en] We present a device concept based on controlled micromagnetic configurations in a corner-shaped permalloy nanostructure terminated with two circular disks, specifically designed for the capture and detection of a small number of magnetic beads in suspension. A transverse head-to-head domain wall (TDW) placed at the corner of the structure plays the role of an attracting pole for magnetic beads. The TDW is annihilated in the terminating disks by applying an appropriate magnetic field, whose value is affected by the presence of beads chemically bound to the surface. In the case where the beads are not chemically bound to the surface, the annihilation of the TDW causes their release into the suspension. The variation of the voltage drop across the corner, due to the anisotropic magnetoresistance (AMR) while sweeping the magnetic field, is used to detect the presence of a chemically bound bead. The device response has been characterized by using both synthetic antiferromagnetic nanoparticles (disks of 70 nm diameter and 20 nm height) and magnetic nanobeads, for different thicknesses of the protective capping layer. We demonstrate the detection down to a single nanoparticle, therefore the device holds the potential for the localization and detection of small numbers of molecules immobilized on the particle's functionalized surface.
[en] In this study, the removal mechanism of Cr(VI) from water by coconut coir (CC) was investigated using X-ray photoelectron spectroscopy (XPS), Cr K-edge X-ray absorption near edge structure (XANES) and FTIR spectroscopy. The results showed that, upon reaction with CC at pH 3, Cr(VI) was reduced to Cr(III), which was either bound to CC or released back into solution. As revealed by the FTIR spectra of CC before and after reacting with Cr(VI), the phenolic methoxyl and hydroxyl groups of lignin in CC are the dominant drivers of Cr(VI) reduction, giving rise to carbonyl and carboxyl groups on CC. These functional groups can subsequently provide binding sites for Cr(III) resulting from Cr(VI) reduction. In conjunction with forming complexes with carbonyl and carboxyl groups, the formation of Cr(III) hydroxide precipitate could also readily occur as revealed by the linear combination fitting of the Cr K-edge XANES spectrum using a set of reference compounds. The phenolic groups in lignin are responsible for initiating Cr(VI) reduction, so lignocellulosic materials containing a higher amount of phenolic groups are expected to be more effective scavengers for removal of Cr(VI) from the environment.
[en] A microfabricated magnetic sifter has been designed and fabricated for applications in biological sample preparation. The device enables high-throughput, high-gradient magnetic separation of magnetic nanoparticles by utilizing columnar fluid flow through a dense array (∼5000/mm2) of micropatterned slots in a magnetically soft membrane. The potential of the sifter for separation of magnetic nanoparticles conjugated with capture antibodies is demonstrated through quantitative separation experiments with CD138-labeled MACS nanoparticles. Capture efficiencies ranging from 28% to 37% and elution efficiencies greater than 73% were measured for a single pass through the sifter.