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排序方式: 共有238条查询结果,搜索用时 15 毫秒
21.
The energy and exergy analyses of the drying process of olive mill wastewater (OMW) using an indirect type natural convection solar dryer are presented. Olive mill wastewater gets sufficiently dried at temperatures between 34 °C and 52 °C. During the experimental process, air relative humidity did not exceed 58%, and solar radiation ranged from 227 W/m2 to 825 W/m2. Drying air mass flow was maintained within the interval 0.036–0.042 kg/s. Under these experimental conditions, 2 days were needed to reduce the moisture content to approximately one-third of the original value, in particular from 3.153 gwater/gdry matter down to 1.000 gwater/gdry matter.Using the first law of thermodynamics, energy analysis was carried out to estimate the amounts of energy gained from solar air heater and the ratio of energy utilization of the drying chamber. Also, applying the second law, exergy analysis was developed to determine the type and magnitude of exergy losses during the solar drying process. It was found that exergy losses took place mainly during the second day, when the available energy was less used. The exergy losses varied from 0 kJ/kg to 0.125 kJ/kg for the first day, and between 0 kJ/kg and 0.168 kJ/kg for the second. The exergetic efficiencies of the drying chamber decreased as inlet temperature was increased, provided that exergy losses became more significant. In particular, they ranged from 53.24% to 100% during the first day, and from 34.40% to 100% during the second. 相似文献
22.
E Tayama Y Niimi Y Takami Y Ohashi G Ohtsuka JA Glueck J Mueller Y Nosé 《Canadian Metallurgical Quarterly》1997,21(12):1284-1287
Centrifugal pumps are generally employed as nonpulsatile blood flow pumps; however, these pumps can produce pulsatile flow by periodically alternating the impeller rotation speed. This study investigates blood trauma due to the effect of pulse frequency and various ranges of pump speed. The hemolysis tests were conducted using the Gyro C1E3 pump. The study was divided into the following categories: Group 1 in a nonpulsatile mode; Group 2 operated at 40 bpm with 30% of speed variance; Group 3, 60 bpm with 30% of speed variance; Group 4, 40 bpm with 70% of speed variance; and Group 5, 60 bpm with 70% of speed variance. A flow rate of 3 L/min and a total pressure head of 200 mm Hg were employed in all groups to simulate a percutaneous cardiopulmonary support condition. There were no significant differences in the hemolysis levels among Groups 1, 2, and 3. However, Groups 4 and 5 exhibited a significantly higher hemolysis rate compared to the other groups. These results indicate that a high rate of speed variance increases hemolysis; however, a range of less than 30% does not affect hemolysis. The pulse rate has no significant effect on hemolysis. In conclusion, the higher speed variance increases the hemolysis level when a pulsatile mode is applied with a centrifugal pump at the given test conditions. However, a speed variance of less than 30% or a pulse rate of less than 60 bpm does not affect hemolysis. 相似文献
23.
Didac Vega Jordi Reina Ferran Martí Ramón Pavón ángel Rodríguez 《Nanoscale research letters》2014,9(1):473
In this paper, high-capacity energy storage devices based on macroporous silicon are demonstrated. Small footprint devices with large specific capacitances up to 100 nF/mm2, and an absolute capacitance above 15 μF, have been successfully fabricated using standard microelectronics and MEMS techniques. The fabricated devices are suitable for high-density system integration. The use of 3-D silicon structures allows achieving a large surface to volume ratio. The macroporous silicon structures are fabricated by electrochemical etching of silicon. This technique allows creating large structures of tubes with either straight or modulated radial profiles in depth. Furthermore, a very large aspect ratio is possible with this fabrication method. Macroporous silicon grown this way permits well-controlled structure definition with excellent repeatability and surface quality. Additionally, structure geometry can be accurately controlled to meet designer specifications. Macroporous silicon is used as one of the electrodes over which a silicon dioxide insulating layer is grown. Several insulator thicknesses have been tested. The second capacitor electrode is a solid nickel filling of the pores prepared by electroplating in a low-temperature industry standard process. The use of high-conductivity materials allows reaching small equivalent series resistance near 1 Ω. Thanks to these improvements, the presented devices are capable of operating up to 10 kHz.
PACS
84.32.Tt; 81.15.Pq; 81.05.Rm 相似文献24.
Edgar Cristbal‐Lecina Pablo Etayo San Doran Marc Revs Pablo Martín‐Gago Arnald Grabulosa Andrea R. Costantino Anton Vidal‐Ferran Antoni Riera Xavier Verdaguer 《Advanced Synthesis \u0026amp; Catalysis》2014,356(4):795-804
MaxPHOS is an active and robust P‐stereogenic ligand for asymmetric catalysis. The presence of an NH bridge between the two phosphine moieties allows the NH/PH tautomerism to take place. The neutral ligand, in which the NH form predominates, is an air‐sensitive compound. However, protonation of MaxPHOS leads to the stable PH form of the ligand, in which the overall positive charge is distributed on both P centers. This protonation turns the MaxPHOS⋅HBF4 salt 3 into an air‐stable compound both in the solid state and in solution. The salt 3 is also a convenient precursor for the preparation of rhodium(I) complexes by direct ligand exchange with the complex [Rh(acac)(cod)]. Finally, the corresponding rhodium(I)‐MaxPHOS complex was tested in the asymmetric hydrogenation of a wide range of substrates. The complex proved to be a highly selective and robust system in these reactions.
25.
Magnetization dynamics in nanomagnets has attracted broad interest since it was predicted that a dc current flowing through a thin magnetic layer can create spin-wave excitations. These excitations are due to spin momentum transfer, a transfer of spin angular momentum between conduction electrons and the background magnetization, that enables new types of information processing. Here we show how arrays of spin-torque nano-oscillators can create propagating spin-wave interference patterns of use for memory and computation. Memristic transponders distributed on the thin film respond to threshold tunnel magnetoresistance values, thereby allowing spin-wave detection and creating new excitation patterns. We show how groups of transponders create resonant (reverberating) spin-wave interference patterns that may be used for polychronous wave computation and information storage. 相似文献
26.
Monica Coll Anna Fernandez-Falgueras Anna Iglesias Bernat del Olmo Laia Nogue-Navarro Adria Simon Alexandra Perez Serra Marta Puigmule Laura Lopez Ferran Pico Monica Corona Marta Vallverdu-Prats Coloma Tiron Oscar Campuzano Josep Castella Ramon Brugada Mireia Alcalde 《International journal of molecular sciences》2022,23(20)
Molecular screening for pathogenic mutations in sudden cardiac death (SCD)-related genes is common practice for SCD cases. However, test results may lead to uncertainty because of the identification of variants of unknown significance (VUS) occurring in up to 70% of total identified variants due to a lack of experimental studies. Genetic variants affecting potential splice site variants are among the most difficult to interpret. The aim of this study was to examine rare intronic variants identified in the exonic flanking sequence to meet two main objectives: first, to validate that canonical intronic variants produce aberrant splicing; second, to determine whether rare intronic variants predicted as VUS may affect the splicing product. To achieve these objectives, 28 heart samples of cases of SCD carrying rare intronic variants were studied. Samples were analyzed using 85 SCD genes in custom panel sequencing. Our results showed that rare intronic variants affecting the most canonical splice sites displayed in 100% of cases that they would affect the splicing product, possibly causing aberrant isoforms. However, 25% of these cases (1/4) showed normal splicing, contradicting the in silico results. On the contrary, in silico results predicted an effect in 0% of cases, and experimental results showed >20% (3/14) unpredicted aberrant splicing. Thus, deep intron variants are likely predicted to not have an effect, which, based on our results, might be an underestimation of their effect and, therefore, of their pathogenicity classification and family members’ follow-up. 相似文献
27.
M Bustamante P Nos M Hoyos J Hinojosa JR Molés A García-Herola J Berenguer 《Canadian Metallurgical Quarterly》1998,90(12):833-840
The effects of smoking on the onset and clinical course of inflammatory bowel disease (IBD) have been widely debated. Although smoking appears to have a clearly unfavorable effect on the course in Crohn's Disease (CD), the relationship between smoking and localization of the disease is less clear. AIM: To evaluate, in our group of patients, the relationship between smoking and the development of ulcerative colitis (UC) or CD, and between smoking and the localization of CD in the large bowel or in other sites. PATIENTS AND METHODS: The smoking habits of 171 patients at the time of diagnosis were assessed with a questionnaire. Subjects were classified into three subgroups as smokers, nonsmokers and ex-smokers. Current smokers were grouped according to their level of consumption as those who smoked fewer than or more than 10 cigarettes per day. A total of 161 patients were studied (UC n = 69, CD n = 92). Patients with CD were divided into those with colonic disease and those with no colonic involvement. We evaluated the relationship between smoking and the form of IBD, localization (colonic or noncolonic) and the presence of perianal disease (PAD) in CD. The results were analyzed with the chi-squared test. RESULTS: Smoking was more frequent in patients with CD than in those with UC (72.8% vs 31.9%). Among patients with CD, more patients without colonic involvement were smokers (84.6% vs 64.2%). However, among patients with CD involving the colon, smoking was significantly more common (64.2%) than among patients who had UC (31.9%). CONCLUSIONS: Our findings confirm a relationship between smoking and CD. Smoking seems to be associated with some degree of protection of the colonic mucosa, especially in heavy smokers. 相似文献
28.
Y Takami G Otsuka J Mueller Y Sugita K Nakata E Tayama Y Ohashi H Schima H Schmallegger E Wolner Y Nosé 《Canadian Metallurgical Quarterly》1998,22(8):713-720
A method has been developed for the rapid molecular mass determination and structural elucidation of mixtures of oligosaccharides derived from plant cell walls. The oligosaccharides were fractionated using gel permeation chromatography and 'analytical' high-performance anion-exchange chromatography (HPAEC), neutralized, dried and the mixtures of eluent salt and oligosaccharides were per-O-acetylated directly. The derivatized oligosaccharides were isolated by dissolution in dichloromethane and the salts were removed by aqueous partitioning. The per-O-acetylated oligosaccharides were analysed using electrospray (ES) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MS). Exploiting the fact that acid-catalysed per-O-acetylation of oligosaccharides can be achieved even under the extremely salty conditions that are found in post-column neutralized HPAEC fractions, and combining this derivatization step with off-line ESMS, allow rapid screening for molecular mass and thus yield information on the composition of the various oligosaccharides in these complex mixtures. Subsequent per-O-methylation of the per-O-acetylated, salt-free fractions and collision-induced dissociation tandem mass spectrometric analysis was used for additional sequence and branching determination of the oligosaccharides. 相似文献
29.
Beatriz Marcotegui Ferran MarquÉs Joseph Ramon Morros Montse PardÀs Philippe Salembier 《电信纪事》1997,52(7-8):380-387
This paper deals with the relation between segmentation for coding and rate control. The efficiency of a segmentation-based coding scheme heavily relies on this step that defines how many and which regions have to be segmented. In this paper, we show that this problem can be formulated as a rate/distortion problem. The proposed solution not only controls the segmentation, but also defines the coding strategy to be used in each region. Together with the general approach, several simplified versions of the segmentation control are proposed and discussed. 相似文献
30.
Low-dose steroids reduce flu-like symptoms at the initiation of IFNbeta-1b in relapsing-remitting MS
To determine whether low-dose prednisone reduces flu-like symptoms at the initiation of interferon beta 1-b (IFNbeta-1b), we studied 71 patients with clinically definite, relapsing-remitting multiple sclerosis who were started on IFNbeta-1b. Patients were randomized to receive prednisone plus paracetamol or only paracetamol and were monitored for side effects. Systemic side effects were minimal in the steroid group compared with the nonsteroid group during the first 15 days of treatment (p=0.005). At 3 months, both groups showed a similar frequency of flu-like symptoms. No differences in local reaction between the two groups were observed throughout the study. 相似文献