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21.
HM Chaung CH Hong CP Chiang SK Lin YS Kuo WH Lan CC Hsieh 《Canadian Metallurgical Quarterly》1996,95(7):545-550
This review reports the different genetic factors that have been identified either as risk factor for Alzheimer's disease (AD) or directly causing the disease. First are reviewed epidemiological data and biological mechanisms about the apoplipoprotein E gene allele epsilon 4 that is a major risk factor for Alzheimer's disease. The second part describes the mutations responsible for early-onset autosomal dominant AD found in three different genes. The gene located on chromosome 21 encodes the amyloid precusor protein (APP). The presenilin 1 and presenilin 2 genes, located on chromosome 14 and 1 respectively, encode not yet known membrane proteins. 相似文献
22.
Rheological Property and Stress Development during Drying of Tape-Cast Ceramic Layers 总被引:1,自引:0,他引:1
Jennifer A. Lewis Kimberly A. Blackman rea L. Ogden James A. Payne Lorraine F. Francis 《Journal of the American Ceramic Society》1996,79(12):3225-3234
Rheological property and stress development of tape-cast ceramic layers derived from nonaqueous alumina (A12 O3 )-poly(vinyl butyral) (PVB) suspensions were observed during drying. Casting suspensions exhibited strong shear-thinning behavior, with a low shear Newtonian plateau apparent viscosity >102 Pa. s. The apparent suspension viscosity displayed a power-law dependence on the A12 O3 volume fraction during the initial stage of drying (<30% solvent loss). Stress development, measured by a cantilever deflection method, and parallel weight loss measurements were performed during the drying of tape-cast layers and pure binder coatings. Maximum drying stresses (σmax ) of 1.37-0.77 MPa were observed for plasticized tapes cast at gap heights of 150-400 μm. In contrast, nonplasticized tapes of similar thickness displayed a more gradual stress increase, with σmax values approximately an order of magnitude higher than their plasticized counterparts. The stress histories of the corresponding binder coatings were quite similar to the tape-cast layers, albeit slightly lower σ max values were observed. Stresses decayed beyond σmax with a logarithmic time dependence to an almost constant value of 0.2-0.4 MPa for the plasticized tapes. Based on these observations, process methodologies have been offered to minimize stress development and retention in tape-cast ceramic layers 相似文献
23.
The oxidation behavior of a Cu60Hf25Ti15 bulk metallic glass was studied over the temperature range of 375–520 °C in dry air. The oxidation kinetics of the amorphous
alloy generally followed the parabolic law at all temperatures, with an oxidation rate increasing with temperature. The oxidation
rates of the amorphous alloy were much higher than those of polycrystalline pure-Cu, implying that the additions of Hf and
Ti accelerated the oxidation reaction. The composition of the scales formed on the amorphous alloy was strongly temperature-dependent,
since they consisted mostly of Cu4O3 and CuO with minor amounts of HfO2 at T ≤ 450 °C, while mostly CuO with minor amounts of HfO2 and Cu2TiO3 were detected at higher temperatures. In addition, nanocrystalline Cu51Hf14 and Cu3Ti2 phases were detected on the substrate after oxidation at T ≥ 450 °C, indicating the occurrence of phase transformation. 相似文献
24.
The dynamic capacity theorem characterizes the reliable communication rates of a quantum channel when combined with the noiseless resources of classical communication, quantum communication, and entanglement. In prior work, we proved the converse part of this theorem by making contact with many previous results in the quantum Shannon theory literature. In this work, we prove the theorem with an ??ab initio?? approach, using only the most basic tools in the quantum information theorist??s toolkit: the Alicki-Fannes?? inequality, the chain rule for quantum mutual information, elementary properties of quantum entropy, and the quantum data processing inequality. The result is a simplified proof of the theorem that should be more accessible to those unfamiliar with the quantum Shannon theory literature. We also demonstrate that the ??quantum dynamic capacity formula?? characterizes the Pareto optimal trade-off surface for the full dynamic capacity region. Additivity of this formula reduces the computation of the trade-off surface to a tractable, textbook problem in Pareto trade-off analysis, and we prove that its additivity holds for the quantum Hadamard channels and the quantum erasure channel. We then determine exact expressions for and plot the dynamic capacity region of the quantum dephasing channel, an example from the Hadamard class, and the quantum erasure channel. 相似文献
25.
26.
Patricia A. Miguez Stephen A. Tuin Adam G. Robinson Joyce Belcher Prapaporn Jongwattanapisan Kimberly Perley Vinicius de Paiva Gon«alves Arash Hanifi Nancy Pleshko Elisabeth R. Barton 《International journal of molecular sciences》2021,22(6)
This study evaluated the direct effect of a phytochemical, hesperidin, on pre-osteoblast cell function as well as osteogenesis and collagen matrix quality, as there is little known about hesperidin’s influence in mineralized tissue formation and regeneration. Hesperidin was added to a culture of MC3T3-E1 cells at various concentrations. Cell proliferation, viability, osteogenic gene expression and deposited collagen matrix analyses were performed. Treatment with hesperidin showed significant upregulation of osteogenic markers, particularly with lower doses. Mature and compact collagen fibrils in hesperidin-treated cultures were observed by picrosirius red staining (PSR), although a thinner matrix layer was present for the higher dose of hesperidin compared to osteogenic media alone. Fourier-transform infrared spectroscopy indicated a better mineral-to-matrix ratio and matrix distribution in cultures exposed to hesperidin and confirmed less collagen deposited with the 100-µM dose of hesperidin. In vivo, hesperidin combined with a suboptimal dose of bone morphogenetic protein 2 (BMP2) (dose unable to promote healing of a rat mandible critical-sized bone defect) in a collagenous scaffold promoted a well-controlled (not ectopic) pattern of bone formation as compared to a large dose of BMP2 (previously defined as optimal in healing the critical-sized defect, although of ectopic nature). PSR staining of newly formed bone demonstrated that hesperidin can promote maturation of bone organic matrix. Our findings show, for the first time, that hesperidin has a modulatory role in mineralized tissue formation via not only osteoblast cell differentiation but also matrix organization and matrix-to-mineral ratio and could be a potential adjunct in regenerative bone therapies. 相似文献
27.
Chun-Yuan Cheng Lassina Barro Shang-Ting Tsai Tai-Wei Feng Xiao-Yu Wu Che-Wei Chao Ruei-Siang Yu Ting-Yu Chin Ming Fa Hsieh 《International journal of molecular sciences》2021,22(6)
Microglia-mediated neuroinflammation is recognized to mainly contribute to the progression of neurodegenerative diseases. Epigallocatechin-3-gallate (EGCG), known as a natural antioxidant in green tea, can inhibit microglia-mediated inflammation and protect neurons but has disadvantages such as high instability and low bioavailability. We developed an EGCG liposomal formulation to improve its bioavailability and evaluated the neuroprotective activity in in vitro and in vivo neuroinflammation models. EGCG-loaded liposomes have been prepared from phosphatidylcholine (PC) or phosphatidylserine (PS) coated with or without vitamin E (VE) by hydration and membrane extrusion method. The anti-inflammatory effect has been evaluated against lipopolysaccharide (LPS)-induced BV-2 microglial cells activation and the inflammation in the substantia nigra of Sprague Dawley rats. In the cellular inflammation model, murine BV-2 microglial cells changed their morphology from normal spheroid to activated spindle shape after 24 h of induction of LPS. In the in vitro free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, EGCG scavenged 80% of DPPH within 3 min. EGCG-loaded liposomes could be phagocytized by BV-2 cells after 1 h of cell culture from cell uptake experiments. EGCG-loaded liposomes improved the production of BV-2 microglia-derived nitric oxide and TNF-α following LPS. In the in vivo Parkinsonian syndrome rat model, simultaneous intra-nigral injection of EGCG-loaded liposomes attenuated LPS-induced pro-inflammatory cytokines and restored motor impairment. We demonstrated that EGCG-loaded liposomes exert a neuroprotective effect by modulating microglia activation. EGCG extracted from green tea and loaded liposomes could be a valuable candidate for disease-modifying therapy for Parkinson’s disease (PD). 相似文献
28.
Reverse osmosis separations of eight polyethylene glycol (PEG) solutes in the average molecular weight range of 200 to 6750 in single-solute dilute aqueous solutions have been studied using porous cellulose acetate membranes at the operating pressures of 50, 75, and 100 psig. Diffusivity data for the above PEG solutes have also been obtained from experimental data on intrinsic viscosities. From an analysis of all experimental data, numerical values for the parameters representing the polar (?ΔΔG/RT), steric (δ*ΣEs), and nonpolar (ω*Σs*) forces governing reverse osmosis separations of PEG solutes have been generated. These numerical values are useful for precise characterization of cellulose acetate membranes for whose specifications sodium chloride is not the appropriate reference solute because of its low or practically negligible separation under reverse osmosis operating conditions. This work also illustrates that solute separation in reverse osmosis can predictably increase or decrease with increase in operating pressure depending on experimental conditions. 相似文献
29.
Hemanshu Bhatt Kimberly Y. Donaldson D. P. II. Hasselman Ramakrishna T. Bhatt 《Journal of the American Ceramic Society》1992,75(2):334-340
The role of an interfacial carbon coating in the heat conduction behavior of a uniaxial silicon carbide nitride was investigated. For such a composite without an interfacial carbon coating the values for the thermal conductivity transverse to the fiber direction agreed very well with the values calculated from composite theory using experimental data parallel to the fiber direction, regardless of the ambient atmosphere. However, for a composite made with carbon-coated fibers the experimental values for the thermal conductivity transverse to the fiber direction under vacuum at room temperature were about a factor of 2 lower than those calculated from composite theory assuming perfect interfacial thermal contact. This discrepancy was attributed to the formation of an interfacial gap, resulting from the thermal expansion mismatch between the fibers and the matrix in combination with the low adhesive strength of the carbon coating. In nitrogen or helium the thermal conductivity was found to be higher because of the contribution of gaseous conduction across the interfacial gap. On switching from vacuum to nitrogen a transient effect in the thermal diffusivity was observed, attributed to the diffusion-limited entry of the gas phase into the interfacial gap. These effects decreased with increasing temperature, due to gap closure, to be virtually absent at 1000°C. 相似文献
30.
S. J. Liao D. Y. Chang H. J. Chen L. S. Tsou J. R. Ho H. T. Yau W. H. Hsieh James T. Wang Y. C. Su 《Polymer Engineering and Science》2004,44(5):917-928
Optimal process conditions of thin‐wall injection molding of a cellular phone cover were investigated with the consideration of interaction effects between process parameters. L27 experimental tests based on Taguchi's method were performed, and then Cyclone Scanner, PolyCAD and PolyWorks were used to measure the shrinkage and warpage of the thin‐wall injected parts to determine the optimal process conditions. Based on the results of the analysis of variables and the F‐test, interaction effects for each observed factor were determined. The results indicated that the packing pressure was the most important process parameter affecting the shrinkage and warpage of the thin‐wall part. The optimal process conditions were different for the shrinkage and the warpage. This was because during the injection process, the mechanisms affecting shrinkage or warpage were different. Compared with the results obtained with simplified thin‐wall parts in the literature, it was found that the geometry of a real commercial part did affect the optimal process conditions and the order of influence of process parameters. The optimal process conditions determined by Taguchi's method for reducing the shrinkage and warpage were verified experimentally in this work. Polym. Eng. Sci. 44:917–928, 2004. © 2004 Society of Plastics Engineers. 相似文献