PbTiO(3) (PTO) ferroelectric films on Pt(111) bottom electrode layers covering Ta/glass were prepared using pulsed laser deposition. X-ray diffraction patterns revealed that the PTO films were preferentially (111)-oriented. The films were highly crystalline and had a smooth surface with root mean square (RMS) roughness of 1.5 nm. Ferroelectric properties of the PTO films were characterized using piezoresponse force microscopy (PFM). PFM techniques achieved ferroelectric polarization bits with a minimum width of 22 nm, which corresponds to a potential recording density of 1.3 Tbit/in(2) in ferroelectric storage devices. 相似文献
The extraction of medicinal or functional compounds from herbal plants is an important unit operation in food and bio-industries. The target compounds are generally present inter- or intra-cellularly in an intricate microstructure formed by cells, intercellular spaces, capillaries, and pores. The major resistance of molecular diffusion in materials of plant origin always comes from the intact cell walls and adhering membranes. Therefore, increasing the permeability of cell walls and membranes plays a very important role to increase extraction yield and/or extraction rate.
Important pretreatment methods to modify the cellular structures and increase the permeability of cell walls or membranes are discussed in this paper. They include physical, biologic, and chemical treatments. In physical methods, mechanical disruption, high-pressure (HP) process, pulsed electric field (PEF) application, ultrasonic treatment, and freeze–thaw, and so on were applied. In biologic methods, different cell wall-degrading enzymes were applied to break-down cell walls or membranes and to diminish the overall internal resistance for transporting bioactive compounds from internal matrix to the external solution. In chemical methods, various chemicals for increasing the inner- or outer-membrane permeabilization were introduced. The principles of the technologies, examples of improvements, and advantages and disadvantages of the pretreatment methods are critically reviewed in this paper. 相似文献
In this study, the effect of perovskite (Ca,Co)-doped LaCrO3 (LCCC) coating on a commercial ferritic stainless steel (SS430) as metallic interconnector in intermediate-temperature solid oxide fuel cell has been investigated in terms of oxidation kinetics and area specific resistance (ASR) at 800 °C in air environment. The LCCC coating was deposited on SS430 by atmospheric plasma spraying from a spray-dried (La0.8Ca0.2)(Cr0.9Co0.1)O3 powder of 10–30 um. The plasma-sprayed LCCC coating had a low porosity of ~1.0 area% and a good electrical conductivity of 33 S/cm at 800 °C. The protective LCCC coating significantly lowered the growth rate of thermally grown oxide scale of SS430 by inhibiting oxygen inward diffusion. The oxidation of the LCCC coated SS430 for 1200 h led to the formation of duplex Cr2O3-LaCrO3 scale layer of ~1 um in thickness. A high conductive LaCrO3 phase in the oxide scale was formed by the chemical interactions between the Cr2O3 scale and the LCCC coating. The ASR for the LCCC coated sample was limited to 9.2 mΩ·cm2 after oxidation for 1200 h at 800 °C, which was much lower than ASR for the uncoated sample. 相似文献
Video summarization is a method to reduce redundancy and generate succinct representation of the video data. One of the mechanisms to generate video summaries is to extract key frames which represent the most important content of the video. In this paper, a new technique for key frame extraction is presented. The scheme uses an aggregation mechanism to combine the visual features extracted from the correlation of RGB color channels, color histogram, and moments of inertia to extract key frames from the video. An adaptive formula is then used to combine the results of the current iteration with those from the previous. The use of the adaptive formula generates a smooth output function and also reduces redundancy. The results are compared to some of the other techniques based on objective criteria. The experimental results show that the proposed technique generates summaries that are closer to the summaries created by humans. 相似文献
The quantification of choline-containing compounds (Cho) in breast tumors by proton MR spectroscopy (1H-MRS) has been of great interest because such compounds have been linked to malignancy. In this study, an internal reference method for the absolute quantification of Cho metabolite in malignant breast tumors was presented using a clinical 1.5 T scanner. We performed in vitro measurements to examine the accuracy of absolute quantification using four phantoms of known choline chloride concentrations. There was a high correlation between the calculated concentrations by MRS and the known concentrations (r2 > 0.98). We applied the technique to in vivo breast study conducted on 45 patients with biopsy-confirmed breast cancer. After T1 and T2 relaxation times were corrected, the Cho levels in this work had a range of 0.76 – 21.20 mmol/kg from 34 MR spectra of 32 patients with malignant breast lesions. This result was rather consistent with the previously published value (i.e., 1.38 – 10 mmol/kg, Bolan et al. in Magn Reson Med 50:1134–1143, 2003). Therefore, we conclude that the internal method using the fully relaxed water as a reference could be used for quantifying Cho metabolite accurately in breast cancer patients using a clinical 1.5 T scanner. 相似文献
Recombinant amylosucrase (200 U/mL) from Neisseria polysaccharea was used to produce digestion‐resistant starch (RS) using 1–3% (w/v) corn starches and 0.1–0.5 M sucrose incubated at 35°C for 24 h. Characterization of the obtained enzyme‐modified starches was investigated. Results show that the yields of the enzyme‐modified starches were inversely proportional to the original amylose contents of corn starches. After enzymatic reaction, insoluble RS contents increased by 22.3 and 20.7% from 6.9% of waxy and 7.7% of normal corn starches, respectively, using 3.0% starch as acceptor and 0.3 M sucrose as donor, while amylomaize VII showed the lowest increase (8.5%) in RS content. The crystalline polymorph of these enzyme‐modified starches resulted in the B‐type immediately after enzymatic reaction. The enzyme‐modified starches displayed higher melting peak temperatures (85.6–100.6°C) compared to their native starch counterparts (70.1–78.4°C). After enzymatic reaction, pasting temperature increased in waxy (71.9 → 77.6°C) and normal corn starches (75.3 → 80.6°C), and the peak viscosity of waxy corn starches increased from 264 to 349 RVU, whereas that of normal corn starches decreased from 235 to 66 RVU. 相似文献
Mesoporous nickel (30 wt%)–iron (5 wt%)–alumina (denoted as NiFeAl–X) catalysts were prepared by a coprecipitation method with a variation of precipitation agent (X = (NH4)2CO3, Na2CO3, NH4OH, and NaOH), and they were applied to the methane production from CO2 and H2. Metal particle size of reduced NiFeAl–X catalysts decreased in the order of NiFeAl–NaOH > NiFeAl–NH4OH > NiFeAl–Na2CO3 > NiFeAl–(NH4)2CO3. In the methanation of CO2, yield for CH4 increased in the order of NiFeAl–NaOH < NiFeAl–NH4OH < NiFeAl–Na2CO3 < NiFeAl–(NH4)2CO3. This indicates that the catalytic performance in the methanation of CO2 was strongly influenced by the identity of precipitation agent. 相似文献
Ultra high pressure (UHP) processing is an attractive non-thermal technique for food treatment and preservation at room temperature, with the potential to achieve interesting functional effects. The majority of UHP process applications in food systems have focused on shelf-life extension associated with non-thermal sterilization and a reduction or increase in enzymatic activity. Only a few studies have investigated modifications of structural characteristics and/or protein functionalities. Despite the rapid expansion of UHP applications in food systems, limited information is available on the effects of UHP on the structural and physicochemical properties of starch and/or its chemical derivatives included in most processed foods as major ingredients or minor additives. Starch and its chemical derivatives are responsible for textural and physical properties of food systems, impacting their end-use quality and/or shelf-life. This article reviews UHP processes for native (unmodified) starch granules and their effects on the physicochemical properties of UHP-treated starch. Furthermore, functional roles of UHP in acid-hydrolysis, hydroxypropylation, acetylation, and cross-linking reactions of starch granules, as well as the physicochemical properties of UHP-assisted starch chemical derivatives, are discussed. 相似文献