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排序方式: 共有158条查询结果,搜索用时 15 毫秒
41.
Lee SH Lee WH Lee S Goto H Baba T Cho MW Yao T Lee HJ Yasukawa T Matsue T Ko H 《Journal of nanoscience and nanotechnology》2006,6(11):3351-3354
Vertically-aligned zinc oxide (ZnO) nano-needles have been selectively grown on the Si (100) substrates using chemical vapor transport and condensation method without metal catalyst. The selective nucleation of nano-needles was achieved by the controlled treatment of substrate surface using zinc acetate aqueous solution. The nano-needles were selectively grown on the zinc acetate treated area, while the nano-tetrapod structures were formed on the non-treated area. The nano-needles have uniform tip-diameter and length, about 10 nm and 2-3 microm, respectively. The angle of the ZnO nano-needles from the substrate was 90 +/- 0.2 degrees. The structural and optical properties of nano-needles and nanotetrapod structures were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL). The results showed that ZnO nano-needles grow along the c-axis of the crystal plane due to the c-oriented ZnO nanoseeds formed by zinc acetate treatment. The nano-needles have strong ultraviolet emission peak of 3.29 eV with green emission of 2.3 eV at room temperature. This selective growth technique of vertical nano-needles using aqueous solution method has potential applications in the field emission devices or optoelectronic devices hybridized with silicon based electronic devices. 相似文献
42.
Thyago Celso C. Nepomuceno Victor Diogho H. de Carvalho Késsia Thais C. Nepomuceno Ana Paula C. S. Costa 《Expert Systems》2023,40(1):e12967
For strategic reasons, benchmarking best practices from efficient competitors is not usual in many data envelopment analysis (DEA) applications. Even for industries composed of multiple branches, providing information about efficient practices for their peers can jeopardize results for those branches if they compete for market, resources or recognition by the central administration. In this work, a time-series adaptation for the DEA directional model is proposed as an alternative for coping with this problem. The methodological approach has three stages for this benchmarking to occur: Data, Information and Knowledge Extraction. In the first stage, we compare the same unit in different moments to identify efficient periods instead of efficient competitors. As a result, successful performance strategies are investigated using the bibliometric coupling of employees' relevant statements in the second and third stages. The application in a branch of the Brazilian Federal Savings Bank allowed an internal benchmarking of efficient periods when specific performance incentives, innovative processes, competitive strategies, and human resource changes were adopted for improving the unit's performance. 相似文献
43.
A combined theoretical and experimental approach was undertaken to quantitatively determine the influence of a variable solute distribution coefficient, k, on impurity distribution in multipass purification by zone refining. Axial impurity profiles have been experimentally determined for a number of zone passes. It has been shown that the adoption of a variable-k approach in the simulation of impurity profiles during different zone passes is generally much closer to the experimental profiles than the usual adoption of a constant k. An artificial intelligence technique interacts with the numerical model to determine the best molten zone size in each pass in order to provide maximum purification. 相似文献
44.
A picoliter-volume electrochemical analytical chamber has been developed for detecting the metabolic flux resulting from the stress responses of a single plant cell. Electrochemical cells, with volumes as small as 100 pL, were fabricated by controlled electrochemical dissolution of a gold wire sealed in glass (the back-etching of the metal realizing an ultralow-volume titer chamber). In the first instance, the electrode contained within the chamber was characterized by the microinjection of standard aliquots of either ascorbic acid or hydrogen peroxide. In all cases, experimental currents obtained correlated well with theoretical calculations. Subsequently, single plant cells were micromanipulated into the chambers and were exposed to amounts of the detergent SDS (which permeabilized the cell membrane and released the intracellular contents). The flux of metabolite released from a single cell was estimated by using electrochemical-linked assays based upon the enzymes catalase, ascorbate oxidase, and horseradish peroxidase (in each case), in the presence of a mediator. In so doing, we investigated the activity of the cellular protection mechanisms through the determination of peroxides, while the individual cell was "stressed". The technique was found to provide a reliable and reproducible method for making single-cell measurements, using fabrication procedures that are both simple and do not require photolithographic methods. 相似文献
45.
Alamelu Sundaresan Satish K. Mehta Todd. T Schlegel Thais Russomano Duane L. Pierson Vivek Mann Elvedina Mansoor Loretta Olamigoke Elvis Okoro 《Microgravity science and technology》2017,29(1-2):145-149
This pilot study compared placental growth factor (PIGF) levels in populations with high versus low risk for cardiovascular disease. Previous experiments from our laboratory (Sundaresan et al. 2005, 2009) revealed that the angiogenic factor PIGF was up regulated in modeled microgravity conditions in human lymphocytes leading to possible atherogenesis and pathogenesis in microgravity. Since the findings came from microgravity analog experiments, there is a strong link to its usefulness in the microgravity field as a biomarker. It is important to understand, that these findings came from both studies on expression levels of this cardiovascular marker in human lymphocytes in microgravity (in vitro microgravity analog), and a follow up gene expression study in hind limb suspended mice (in vivo microgravity analog). The relevance is enhanced because in life on earth, PIGF is an inflammatory biomarker for cardiovascular disease. Studies on the levels of PIGF would help to reduce the risk and prevention of heart failures in astronauts. If we can use this marker to predict and reduce the risk of cardiac events in astronauts and pilots, it would significantly help aerospace medicine operations. The investigations here confirmed that in a cardiovascular stressed population such as coronary artery disease (CAD) and acute coronary syndrome (ACS) patients, PIGF could be overexpressed. We desired to re-evaluate this marker in patients with cardiovascular disease in our own study. PIGF is a marker of inflammation and a predictor of short-term and long-term adverse outcome in ACS. In addition, elevated PIGF levels may be associated with increased risk for CAD.PIGF levels were determined in thirty-one patients undergoing cardiovascular catheterization for reasons other than ACS and in thirty-three low-risk asymptomatic subjects. Additional data on traditional cardiovascular risk factors for both populations were also compiled and compared. We found that PIGF levels were significantly higher in the high-risk population as compared to low-risk population. Also we were able to ascertain that PIGF levels were inversely correlated with HDL-cholesterol but directly correlated with the triglyceride levels. With further validation, PIGF may prove a useful addition to the armamentarium of noninvasive biomarkers for cardiovascular disease including a new area of stressful physiological conditions such as microgravity. 相似文献
46.
Yuka Muranaka Asuka Mizutani Masato Kobayashi Koya Nakamoto Miki Matsue Kodai Nishi Kana Yamazaki Ryuichi Nishii Naoto Shikano Shigefumi Okamoto Keiichi Kawai 《International journal of molecular sciences》2022,23(5)
The effectiveness of L- and D-amino acids for detecting the early stage of infection in bacterial imaging was compared. We evaluated the accumulation of 3H-L-methionine (Met), 3H-D-Met, 3H-L-alanine (Ala), and 3H-D-Ala in E. coli EC-14 and HaCaT cells. Biological distribution was assessed in control and lung-infection-model mice with EC-14 using 3H-L- and D-Met, and 18F-FDG. A maximum accumulation of 3H-L- and D-Met, and 3H-L- and D-Ala occurred in the growth phase of EC-14 in vitro. The accumulation of 3H-L-Met and L-Ala was greater than that of 3H-D-Met and D-Ala in both EC-14 and HaCaT cells. For all radiotracers, the accumulation was greater in EC-14 than in HaCaT cells at early time points. The accumulation was identified at 5 min after injection in EC-14, whereas the accumulation gradually increased in HaCaT cells over time. There was little difference in biodistribution between 3H-L-and D-Met except in the brain. 3H-L- and D-Met were sensitive for detecting areas of infection after the spread of bacteria throughout the body, whereas 18F-FDG mainly detected primary infection areas. Therefore, 11C-L- and D-Met, radioisotopes that differ only in terms of 3H labeling, could be superior to 18F-FDG for detecting bacterial infection in lung-infection-model mice. 相似文献
47.
Adriano Costa de Camargo Thais Maria Ferreira de Souza Vieira Marisa Aparecida Bismara Regitano-d��Arce Severino Matias de Alencar Maria Antonia Calori-Domingues Marta Helena Fillet Spoto Solange Guidolin Canniatti-Brazaca 《International journal of molecular sciences》2012,13(9):10935-10958
Peanut samples were irradiated (0.0, 5.2, 7.2 or 10.0 kGy), stored for a year (room temperature) and examined every three months. Mycotoxic fungi (MF) were detected in non-irradiated blanched peanuts. A dose of 5.2 kGy was found suitable to prevent MF growth in blanched samples. No MF was detected in in-shell peanuts, with or without irradiation. The colors of the control in-shell and blanched samples were, respectively, 44.72 and 60.21 (L *); 25.20 and 20.38 (Chroma); 53.05 and 86.46 (°Hue). The water activities (Aw) were 0.673 and 0.425. The corresponding fatty acids were 13.33% and 12.14% (C16:0), 44.94% and 44.92% (C18:1, ω9) and 37.10% and 37.63% (C18:2, ω6). The total phenolics (TP) were 4.62 and 2.52 mg GAE/g, with antioxidant activities (AA) of 16.97 and 10.36 μmol TEAC/g. Storage time negatively correlated with Aw (in-shell peanuts) or L *, linoleic acid, TP and AA (in-shell and blanched peanuts) but positively correlated with Aw (blanched peanuts), and with oleic acid (in-shell and blanched peanuts). Irradiation positively correlated with antioxidant activity (blanched peanuts). No correlation was found between irradiation and AA (in-shell samples) or fatty acids and TP (in-shell and blanched peanuts). Irradiation protected against MF and retained both the polyunsaturated fatty acids and polyphenols in the samples. 相似文献
48.
Nagamine K Onodera S Torisawa YS Yasukawa T Shiku H Matsue T 《Analytical chemistry》2005,77(13):4278-4281
On-chip transformation of Escherichia coli cells was accomplished for the first time using a microbial array chip. The continuous E. coli transformation procedures were performed on a chip in which the microcompartment was composed of PDMS microfluidic channels and a silicon substrate predeposited with different plasmid DNAs. The PDMS microfluidic device enabled the parallel transformation of E. coli cells with various plasmid DNAs by separating each transformation area. The phenotypic differences reflecting different plasmid DNAs were identified by various approaches such as colorimetry, fluorometry, and electrochemical methods. This microbial array chip could become a versatile tool for many cell biological applications. 相似文献
49.
Kasai S Yokota A Zhou H Nishizawa M Niwa K Onouchi T Matsue T 《Analytical chemistry》2000,72(23):5761-5765
Scanning electrochemical microscopy (SECM) was applied to the immunoassay of leukocidin, which is a toxic protein produced by methicillin-resistant Staphylococcus aureus (MRSA), with the intention of developing and early diagnostic for MRSA infection. An antibody-chip for leukocidin was prepared by self-assembling of anti-leukocidin on a protein A-coated glass substrate. A sample solution containing leukocidin was spotted onto the antibody-chip, followed by labeling with horseradish peroxidase (HRP) via a sandwich method. The reduction current of the oxidized form of ferrocenylmethanol generated by the HRP reaction was monitored to view SECM images of the spot of captured leukocidin. The amplitude of reduction current depended on the concentrations of sample solutions used for making spots. This SECM-based immunoassay detects as low as 5.25 pg mL(-1) leukocidin. 相似文献
50.
Accorsi-Mendonça T Zambuzzi WF Bramante CM Cestari TM Taga R Sader M de Almeida Soares GD Granjeiro JM 《Journal of materials science. Materials in medicine》2011,22(4):997-1004
Our purpose was to evaluate the osteoconduction potential of mixed bovine bone (MBB) xenografts as an alternative for bone
grafting of critical-size defects in the calvaria of rats. After surgery, in the time intervals of 1, 3, 6, and 9 months,
rats were killed and their skulls collected, radiographed and histologically prepared for analysis. The data obtained from
histological analysis reported that the particles of MBB did not promote an intense immunological response, evidencing its
biocompatibility in rats. Our results clearly showed the interesting evidence that MBB was not completely reabsorbed at 9 months
while a small amount of newly formed bone was deposited by osteoprogenitor cells bordering the defect. However, this discrete
bone-forming stimulation was unable to regenerate the bone defect. Overall, our results suggest that the properties of MBB
are not suitable for stimulating intense bone regeneration in critical bone defects in rats. 相似文献