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Chemical Vapour Deposition of Tantalum Silicide Thin Film from Difluorosilylene and Tantalum Halides
Get PDF[[abstract]]Thin films of TaSix have been grown on Si(111), SiO2 and graphite by LPCVD using SiF2 and TaX(5) (X = F, Cl) as the precursors. Thin films prepared at 190-300 degrees C contained polycrystalline TaSi2; 190 degrees C is the lowest temperature reported for the CVD preparation of TaSi2. The compositions of the thin films were found to be 50% TaSi2 and 50% amorphous silicon (a-Si).[[fileno]]2010311010058[[department]]化學
Deposition of Iridium Thin Films Using New Ir(I) CVD Precursors
No full text[[abstract]]The syntheses of three volatile Ir-1 cyclooctadiene precursors is described. The anionic ligand was carefully selected to produce a structure (see Figure) with physical properties suitable for CVD requirements. Films grown using oxygen as carrier gas produced iridium thin films with a purity higher than 98 % and a measured resistivity in the range of 8.4 to 10.2 muOmega cm.[[fileno]]2010311010068[[department]]化學
Characterization of Prenylcysteines That Interact with P-glycoprotein and Inhibit Drug Transport in Tumor Cells
No full text[[abstract]]Prenylcysteine methyl esters that represent the C-terminal structures of prenylated proteins demonstrate specific substrate-like interactions with P-glycoprotein (Zhang, L., Sachs, C. W., Fine, R. L., and Casey, P. J.(1994) J. Biol. Chem. 269, 15973-15976). The simplicity of these compounds provides a unique system for probing the structural specificity of P-glycoprotein substrates. We have further assessed the structural elements of prenylcysteines involved in the interaction with P-glycoprotein. Carboxyl group methylation, a modification in many prenylated proteins, plays an essential role of blocking the negative charge at the free carboxylate. Substitution of the methyl ester with a methyl amide or simple amide does not change the ability of the molecule to stimulate P-glycoprotein ATPase activity, but substitution with a glycine is not tolerated unless the carboxyl group of glycine is methylated. The presence of a nitrogen atom, which is found in many P-glycoprotein substrates and modifiers, is also essential for prenylcysteines to interact with P-glycoprotein. The structure at the nitrogen atom can, however, influence the type of interaction. Acetylation of the free amino group of prenylcysteine results in a significant loss in the ability of prenylcysteines to stimulate P-glycoprotein ATPase activity. Instead, certain acetylated prenylcysteines behave as inhibitors of this activity. In studies using MDR1-transfected human breast cancer cells, the acetylated prenylcysteine analogs inhibit P-glycoprotein-mediated drug transport and enhance the steady-state accumulation of [GraphicH]vinblastine, [GraphicH]colchicine, and [GraphicH]taxol. These inhibitors do not, however, affect drug accumulation in parental cells. These studies provide a novel approach for designing P-glycoprotein inhibitors that could prove effective in reversing the phenotype of multidrug resistance in tumor cells.[[fileno]]2050119010009[[department]]生科
Longan Seed Extract Reduces Hyperuricemia via Modulating Urate Transporters and Suppressing Xanthine Oxidase Activity
No full text[[abstract]]Hyperuricemia causes gouty arthritis, kidney disease, heart disease, and other diseases. Xanthine oxidase (XOD) and urate transporters play important roles in urate homeostasis. Numerous plants have been identified as XOD inhibitors. Longan seeds are known to contain high levels of polyphenols such as corilagin, gallic acid and ellagic acid. We examined the effect of longan seed extract on XOD inhibition and urate transporters GLUT1 and GLUT9 using both in vitro and in vivo assays. The results showed that dried longan seed extract (LSE) and its active components inhibited XOD dose-dependently in vitro. LSE inhibited uric acid production and XOD activity in normal liver cells (clone-9 cells) and was not cytotoxic under the concentration of 200 μg/ml. For the in vivo study, Sprague-Dawley (SD) rats were given intraperitoneally for thirty minutes with or without allopurinol (a XOD inhibitor, 3.5 mg/kg) or LSE (80 mg/kg) and then injected intraperitioneally with 250 mg/kg of oxonic acid and 300 mg/kg of hypoxanthine intragastrically. LSE was able to reduce serum uric acid level and XOD activity in hyperuricemic rats. However, LSE or allopurinol did not inhibit the liver XOD activities. On the other hand, GLUT1 protein was suppressed in kidney and GLUT9 was induced in liver from experimental rats and LSE or allopurinol decreased GLUT9 but increased GLUT1 protein level in the liver and kidney, respectively. These results confirmed the claimed effect of longan seeds on gout and other complications and suggested that its urate reducing effect might be due to modulation of urate transporters and inhibition of circulating xanthine oxidase.[[fileno]]2050119010015[[department]]生科
Heterotypic Gap Junctions between Two Neurons in the Drosophila Brain Are Critical for Memory
No full text[[abstract]]Gap junctions play an important role in the regulation of neuronal metabolism and homeostasis by serving as connections that enable small molecules to pass between cells and synchronize activity between cells [1, 2 and 3]. Although recent studies have linked gap junctions to memory formation [4 and 5], it remains unclear how they contribute to this process [1 and 5]. Gap junctions are hexameric hemichannels formed from the connexin and pannexin gene families in chordates and the innexin (inx) gene family in invertebrates [ 6 and 7]. Here we show that two modulatory neurons, the anterior paired lateral (APL) neuron and the dorsal paired medial (DPM) neuron, form heterotypic gap junctions within the mushroom body (MB), a learning and memory center in the Drosophila brain. Using RNA interference-mediated knockdowns of inx7 and inx6 in the APL and DPM neurons, respectively, we found that flies showed normal olfactory associative learning and intact anesthesia-resistant memory (ARM) but failed to form anesthesia-sensitive memory (ASM). Our results reveal that the heterotypic gap junctions between the APL and DPM neurons are an essential part of the MB circuitry for memory formation, potentially constituting a recurrent neural network to stabilize ASM.[[fileno]]2050132010020[[department]]生命科學
Special Issue on Parallel Processing: Guest Editors' Introduction
No full text[[fileno]]2030201010089[[department]]資訊工程學
An Efficient Downlink Radio Resource Allocation with Carrier Aggregation in LTE-Advanced Networks
No full text[[abstract]]In Long Term Evolution-Advanced (LTE-A) networks, the Carrier Aggregation technique is incorporated for user equipments (UEs) to simultaneously aggregate multiple component carriers (CCs) for achieving higher transmission rate. Many research works for LTE-A systems with Carrier Aggregation configuration have concentrated on the radio resource management problem for downlink transmission, including mainly CC assignment and packet scheduling. Most previous studies have not considered that the assigned CCs in each UE can be changed. Furthermore, they also have not considered the modulation and coding scheme constraint, as specified in LTE-A standards. Therefore, their proposed schemes may limit the radio resource usage and are not compatible with LTE-A systems. In this paper, we assume that the scheduler can reassign CCs to each UE at each transmission time interval and formulate the downlink radio resource scheduling problem under the modulation and coding scheme constraint, which is proved to be NP-hard. Then, a novel greedy-based scheme is proposed to maximize the system throughput while maintaining proportional fairness of radio resource allocation among all UEs. We show that this scheme can guarantee at least half of the performance of the optimal solution. Simulation results show that our proposed scheme outperforms the schemes in previous studies.[[fileno]]2030201010094[[department]]資訊工程學
Design of a File Server in a Local Area Network
No full text[[fileno]]2032021030077[[department]]資訊工程學