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排序方式: 共有485条查询结果,搜索用时 31 毫秒
51.
Bogdan Bucur Gabriel Lucian Radu Constantin Nicolae Toader 《European Food Research and Technology》2008,226(6):1335-1342
A portable bienzymatic analytical system was developed for the chronoamperometric analysis of methanol–ethanol mixtures. The
system consists of two biosensors, one based on alcohol dehydrogenase (ADH) that responds only to the ethanol and the second
one based on alcohol oxidase (AOX) that responds to both methanol and ethanol. The transducers were screen-printed electrodes
(SPEs) modified with mediators: Meldola blue for ADH and Co-phthalocyanine for AOX. The calibration graph of the ADH biosensor
is linear between 0.3 and 8 mmol/L ethanol. The AOX biosensor is able to quantify both analytes in mixtures that contain methanol
between 3 and 70 mmol/L and ethanol ranging from 15 to 110 mmol/L. Interferences due to non-specific oxidations from common
oxidizable compounds like gallic acid and ascorbic acid were smaller in the case of transducer based on Meldola blue. The
analytical system was successfully tested on real samples: non-alcoholised beer (NAB) spiked with ethanol or methanol and
a falsified rose wine (FRW). 相似文献
52.
Placement of Substrate Contacts to Minimize Substrate Noise in Mixed-Signal Integrated Circuits 总被引:1,自引:0,他引:1
Radu M. Secareanu Scott Warner Scott Seabridge Cathie Burke Thomas E. Watrobski Christopher Morton William Staub Thomas Tellier Eby G. Friedman 《Analog Integrated Circuits and Signal Processing》2001,28(3):253-264
The placement of substrate contacts in epi and non-epi technologies is analyzed in order to control and reduce the substrate noise amplitude and spreading. The choice of small or large substrate contacts or rings for each of the two major technologies is highlighted. Design guidelines for placing substrate contacts so as to improve the noise immunity of digital circuits in mixed-signal smart-power systems are also presented. 相似文献
53.
Prevalence and resistance to antibiotics for Aeromonas species from retail fish in Malaysia 总被引:1,自引:0,他引:1
A total of 87 market fish samples representing five types of fish were evaluated for the presence of Aeromonas spp. Of the samples examined, 69%, 55%, 11.5% and 2.3% harbored Aeromonas spp., A. veronii biovar sobria, A. hydrophila and A. caviae, respectively. The 60 isolated Aeromonas spp. strains were further examined for hemolytic activity, resistance to antimicrobial agents and presence of plasmids. Hemolytic activity varied widely among the isolated strains. Though all the isolates demonstrated resistance to three or more of the antibiotics tested, all were susceptible to ceptazidime. Thirty-four (56.7%) of the sixty isolates harbored plasmids, with sizes ranging from 2.3 to 15.7 kb. These results indicate that hemolytic, multiple antibiotic resistant and genetically diverse aeromonads are easily recovered from fish in this region. 相似文献
54.
This paper focuses on the development of an optimized photovoltaic tracking system involving low-cost, relative simple mechanisms, with linear actuators able to insure strokes comparable with those resulted when using gear rotary actuators. Starting with a rhombus linkage, with a linear actuator on the diagonal used for the elevation motion till 90°, a new performance solution is generated. This new linkage allows large angular strokes by using an asymmetric rhombus and an eccentrically positioned linear ac... 相似文献
55.
Robert Ianoş Radu Lazău Ioan Lazău Cornelia Păcurariu 《Journal of the European Ceramic Society》2012,32(8):1605-1611
The removal of carbon residue from ZnAl2O4 nanopowders by annealing at 500–800 °C leads to a decrease of specific surface area from 228.1 m2/g to 47.6 m2/g. At the same time, the average crystallite size increased from 5.1 nm to 14.9 nm. In order to overcome these drawbacks, a new solution for removing the carbon residue has been suggested: chemical oxidation using hydrogen peroxide. In terms of carbon removal, a H2O2 treatment for 8 h at 107 °C proved to be equivalent to a heat treatment of 1 h at 600 °C. The benefits of chemical oxidation over thermal oxidation were obvious. The specific surface area was much larger (188.1 m2/g) in the case of the powder treated with H2O2. The average crystallite size (5.8 nm) of ZnAl2O4 powder treated with H2O2 was smaller than the crystallite size (8.2 nm) of the ZnAl2O4 powder annealed at 600 °C. 相似文献
56.
Ana M. López Antonio Lozano Juan A. García Luis Valiño Radu Mustata 《Journal of power sources》2009,192(1):94-99
This experimental research studies some aspects of water formation and management in polymer electrolyte membrane fuel cells (PEMFCs). To this end, two different single cells of 49 cm2 active area have been tested, the first one with a serpentine-parallel geometry and the second with a cascade-type flow-field topology. In order to visualize the processes, flow-field channels have been machined on transparent plastic. Experiments have consisted in both image acquisition using a CCD camera, and simultaneous measurements of pressure drop in both hydrogen and oxygen gas flow paths. It has been observed that with the cascade-type flow-field geometry, water produced in the cathode does not flood the gas flow channels and, consequently, can be drained in an easy way. On the other hand, it has also been verified that saturated condition for the hydrogen gas flow at the anode side produces water condensation and channel flooding for the serpentine-parallel flow-field topology. Time fluctuations in the pressure drop of the gas flow have been detected and are associated to some transient process inherent to water formation and management. 相似文献
57.
The electrochemical behaviour of tocopherols on solid platinum electrodes, using cyclic voltammetry, linear sweep voltammetry
and differential pulse voltammetry, in non-aqueous media, was studied. D-α-, D-γ-, and D-δ-tocopherol (E vitamins) provided
well-defined voltammograms, each of them exhibiting a characteristic peak (respectively 0.550 V, 0.700 V and 0.750 V vs. a
silver, silver chloride/chloride reference electrode). The differential pulse voltammograms were suitable for the electroanaytical
determination, in the respective concentration ranges of (2 ×10−8÷1×10−5) mol l−1, (2.2×10−8÷1.4×10−6) mol l−1 and (2.2×10−8÷3.31×10−5) mol l−1, of α-, γ-, δ- tocopherol. An electrochemical estimation of the tocopherols' antioxidative properties, related to the free
radical 2,2′diphenyl-1-pycrilhydrazil was made. The maximum value of the characteristic peak of tocopherol decreased with
DPPH concentration.
Received: 26 July 1999 / Revised version: 1 October 1999 相似文献
58.
Radu Bălan Joshua Cooper Kuo-Ming Chao Sergiu Stan Radu Donca 《Energy and Buildings》2011,43(2-3):748-758
HVAC (Heating, Ventilation and Air Conditioning) systems used for heating or cooling buildings, consume a considerable amount of energy. To optimize the energy consumption, the behavior of occupants must be changed. This can be achieved by providing information and suggestions to occupants. A first step is developing of a less expensive and non-invasive measurement system and metering of the electricity and heat consumed. Based on collected experimental data, it can identify the parameters of a thermal model of the house. The model obtained will be used to simulate different aspects that can help to reduce the energy consumption. This paper presents a simple solution for thermal modeling of a house which includes experimental identification of the model's parameters. Such data are used to simulate the thermal behavior of the house and to obtain solutions to reduce energy consumption. In simulation, the control of the thermal system is performed using a model based predictive control algorithm. 相似文献
59.
Radu A. Florescu 《Quality and Reliability Engineering International》1986,2(2):101-106
This paper starts from the main objections regarding MIL-HDBK-217 and the BELLCORE method for reliability prediction, objections asserting that these methods are approximate, complicated and unconvincing. To support these assertions, and by applying techniques specific to reliability theory, the author has developed a reliability model which is plausible for certain elements of technical systems. The existence of such a model, which in practice is useless because the failure rate expression is too complicated, proves clearly the inefficiency of classical methods. 相似文献
60.
Bactenecin 5 (Bac 5), a cationic antibacterial peptide, contains a repeating region of Arg-Pro-Pro-X (X = hydrophobic residue). To investigate the structure and property of a Pro/Arg-rich region, we synthesized a series of repeating peptides, Ac-(Arg-Pro-Pro-Phe)n-NHCH3 (n = 2, 4, 6, 8 and 10) (PR2, PR4, PR6, PR8 and PR10) as models. The circular dichroism (CD) study suggested that the peptides with longer repeats, PR6, PR8 and PR10, formed a conformation similar to poly(proline)-II in aqueous solution. The CD spectra did not change in the presence of dipalmitoyl-DL-alpha-phosphatidylcholine (DPPC), but they changed in the presence of DPPC/ dipalmitoyl-DL-3-phosphatidylglycerol (DPPG). The gamma-helix, which is very similar in conformation to the poly(proline)-II helix, had the lowest energy conformation for the peptides by energy calculations. Peptides PR6, PR8 and PR10 caused slight leakage of fluorescent dye entrapped in DPPC vesicles, and in the presence of DPPC/DPPG, these peptides showed a considerable level of dye-leakage activity. In contrast, the shorter peptides PR2 and PR4 showed no activity. The same tendency was found in measurements of membrane-fusion activity. Judging from these results, the repeating region of Bac 5 may make a framework to hold a conformation resembling the poly(proline)-II structure in aqueous solution. In addition, this region may interact with acidic lipids, resulting in a change in conformation of the peptide. 相似文献