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排序方式: 共有1265条查询结果,搜索用时 15 毫秒
121.
Luis A. Puente Claudia A. Pinto-MuñozEduardo S. Castro Misael Cortés 《Food research international (Ottawa, Ont.)》2011,44(7):1733-1740
The main objective of this work is to spread the physicochemical and nutritional characteristics of the Physalis peruviana L. fruit and the relation of their physiologically active components with beneficial effects on human health, through scientifically proven information. It also describes their optical and mechanical properties and presents micrographs of the complex microstructure of P. peruviana L. fruit and studies on the antioxidant capacity of polyphenols present in this fruit. 相似文献
122.
Bercovici M Kaigala GV Mach KE Han CM Liao JC Santiago JG 《Analytical chemistry》2011,83(11):4110-4117
We present a novel assay for rapid detection and identification of bacterial urinary tract infections using isotachophoresis (ITP) and molecular beacons. We applied on-chip ITP to extract and focus 16S rRNA directly from bacterial lysate and used molecular beacons to achieve detection of bacteria specific sequences. We demonstrated detection of E. coli in bacteria cultures as well as in patient urine samples in the clinically relevant range 1E6-1E8 cfu/mL. For bacterial cultures we further demonstrate quantification in this range. The assay requires minimal sample preparation (a single centrifugation and dilution), and can be completed, from beginning of lysing to detection, in under 15 min. We believe that the principles presented here can be used for design of other rapid diagnostics or detection methods for pathogenic diseases. 相似文献
123.
124.
Yolanda MorenoLorena Ballesteros Jorge García-HernándezPaula Santiago Ana GonzálezM. Antonia Ferrús 《Water research》2011,45(15):4634-4640
Listeria monocytogenes detection in wastewater can be difficult because of the large amount of background microbiota and the presence of viable but non-culturable forms in this environment. The aim of this study was to evaluate a Fluorescent In Situ Hybridization (FISH) assay combined with Direct Viable Count (DVC) method for detecting viable L. monocytogenes in wastewater samples, as an alternative to conventional culture methods. 16S rRNA sequence data were used to design a specific oligonucleotide probe. In order to assess the suitability of the method, the assays were performed on naturally (n = 87) and artificially (n = 14) contaminated samples and results were compared to those obtained with the isolation of cells on selective media and with a PCR method. The detection limit of FISH and PCR assays was 104 cells/mL without enrichment and 10 cells/mL after enrichment. A total of 47 samples, including 3 samples from effluent sites, yielded FISH positive results for L. monocytogenes. Using DVC-FISH technique, the presence of viable L. monocytogenes cells was detected in 23 out of these 47 FISH positive wastewater samples. PCR and culture methods yielded 27 and 23 positive results, respectively. According to these results, FISH technique has the potential to be used as a sensitive method for the detection and enumeration of L. monocytogenes in environmental wastewater samples. 相似文献
125.
A. García Santiago A. M. Testa X. X. Zhang D. Fiorani J. Tejada 《Journal of Superconductivity and Novel Magnetism》1998,11(2):297-303
The temperature and magnetic field dependence of the magnetic relaxation rate has been investigated at low temperatures (1.8 < T < 10 K) on two Tl2Ba2Ca2Cu3O10+δ samples (epitaxial thin film and sintered pellet). The temperature dependence gives evidence of a crossover in the mechanism of vortex motion, from classical thermal activation to quantum tunneling as temperature decreases. The field dependence of the relaxation rate indicates a crossover in the dimensionality of vortices, from three-dimensional flux lines to two-dimensional pancake vortices as field increases. For the thin film, the temperature dependence of the rate has been fitted to the theoretically predicted expressions for finite-temperature enhancement of the quantum rate in different regimes of dissipation. In spite of the similarity of the fits, the estimate of the ratio of Hall to viscous drag terms in the equation of motion indicates that quantum tunneling in this system occurs in an intermediate dissipative regime, where both terms contribute to the motion of vortices. 相似文献
126.
127.
Ryan O’Hayre Tibor Fabian Shawn Litster Fritz B. Prinz Juan G. Santiago 《Journal of power sources》2007
The behavior of an air breathing fuel cell (ABFC) operated on dry-hydrogen in dead-ended mode is studied using theoretical analysis. A one-dimensional, non-isothermal, combined heat and mass transport model is developed that captures the coupling between water generation, oxygen consumption, self-heating and natural convection at the air breathing cathode. The model is validated against planar ABFC experimental measurements over a range of ambient temperatures. The model confirms the strong effect of self-heating on the water balance within passive ABFCs. Model analysis provides several conclusions: (1) thermal runaway caused by inadequate heat rejection predominantly limits ABFC performance. (2) The natural convection boundary layer represents a significant barrier to cathode mass and heat transfer. (3) Because the mass and heat transport numbers associated with natural convection are small, even slight forced convection dramatically affects cell behavior. (4) Performance optimization requires maximizing heat rejection while minimizing flooding. Decoupling the latter two phenomena is challenging due to the exponential relationship between water vapor saturation and temperature. 相似文献
128.
Francesc Carreras Josep Freixas María Albina Puente 《Reliability Engineering & System Safety》2004,83(3):323-332
The index introduced here provides a normalized measure of the effectiveness of any semicoherent structure. We study the mathematical properties of the index and derive different axiomatic characterizations for it. Moreover, close relationships are shown to reliability functions and also to the Birnbaum structural importance measure—for which twice the performance index plays the role of potential function—that give rise to computational procedures. Some numerical examples illustrate the application of the index. 相似文献
129.
C Kiatboonsri SC Resnick KM Chan RG Barbers CC Marboe A Khonsary SM Santiago OP Sharma 《Canadian Metallurgical Quarterly》1998,168(2):130-132
PURPOSE: While advanced cardiac life support (ACLS) training is widely available, it is not mandatory for all anaesthetists. We hypothesised that adherence to ACLS guidelines during resuscitation of ventricular fibrillation (VFib) as assessed in a simulator environment would be poor by anaesthetists not trained in ACLS compared with those who had received training. METHODS: With approval by the ethics review board, 89 subjects participated in the study. The simulation system consisted of a computer controlled mannequin with lifelike qualities set in a mock operating room. Each subject was given a test scenario that contained several standard anaesthetic problems. A VFib cardiac arrest occurred after approximately one hour into the simulation. A perfect score (score = A) defined complete compliance with the ACLS guidelines, whereas minor deviations (score = B) included changes in energy levels, drug doses or treatment order. The failure to discontinue the anaesthetic, defibrillate or administer epinephrine were considered major deviations (score = C). RESULTS: Eight subjects followed the ACLS guidelines (9%, score = A), while 27 subjects showed minor (30%, score = B) and 54 subjects major deviations (61%, score = C). Sixty-two of the 89 participants (70%) had taken the ACLS course and achieved higher scores than did anaesthetists without such training (P < 0.05). Forty-two participants (47%) did not discontinue the anaesthetic, 10 (11%) never gave epinephrine and 5 (6%) never used the defibrillator. CONCLUSION: Adherence to ACLS guidelines was poor. A greater proportion of subjects without previous ACLS training had deviations from protocol than did subjects who had received training. We need to consider ways to ensure that anaesthetists obtain and retain resuscitation skills according to ACLS guidelines. 相似文献
130.
Ultra-microindentation was used to measure the microhardness and modulus of silk (Bombyx mori) membranes, cast from 20 to 80 °C. The microhardness and modulus were determined from the loading/unloading curves. The membranes exhibit microhardness of about 400 MPa which is larger than the values for most common synthetic polymers (50-300 MPa) implying a greater scratch resistance. The moduli are of the order of those measured by the other means for B. mori silk membranes (5 GPa), and fibers (7-11 GPa). There is some correlation between microhardness and the dimensions of the grains/nanofibrils, but none with surface roughness. The results extend the range of an empirical correlation between microhardness and modulus. The present data together with previous data from other polymers fit the equation, H=0.55E0.74, with a correlation coefficient of 0.94. Finally, it is shown that elastic recovery of the silk membranes is an increasing function of the maximum load applied. 相似文献