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61.
We show the results of an experimental campaign to study the pressure drop during the restart of a core-annular flow from a stratified configuration. In normal core annular flow operations, due to fouling or pump failures, a core flow may not be sustained anymore and hence it stratifies. Since the pressure drops connected to the stratified flow regime are much larger than the ones of core annular, the flow suddenly stops. To restart it there are two possibilities: one is to try to provide a higher pressure gradient trying to restore the flow of water and oil, the other is to clean the pipe using water only: in both cases an attachment of a thin layer of oil on the pipe internal wall occurs and the pressure drop for water only or oil–water are higher than the previous ones with clean pipe wall. We focused our attention on the cleaning by water only and we provide experimental data on the evolution of the pressure drop as function of time in order to find when the pipe could be considered as perfectly cleaned or, at least, when the pressure drop are low enough to restart the oil flow. The experimental results are finally compared with a two-fluid model available in literature. 相似文献
62.
Michelle Feeney Maria Antonietta Casadei Pietro Matricardi 《Journal of materials science. Materials in medicine》2009,20(5):1081-1087
A carboxymethyl derivative of scleroglucan (Scl-CM) with a derivatization degree of 65 ± 5% was synthesized. The rheological
behaviour of this novel polymer was studied and compared with that of the starting polymer. We observed that the charged moieties
carried on the chains could prevent the triple helix formation of Scl. Scl-CM aqueous solutions behave like true polymer solutions
up to 1% w/v, whereas above this concentration a weak gel behaviour was observed. CaCl2 addition to aqueous Scl-CM solutions led to a physical gel formation; the hydrogel strength was related to polymer and CaCl2 concentrations. Temperature sweeps, registered at 1 Hz on hydrogels differing in CaCl2 concentration, evidenced a gel → sol transition in the range of 30–40°C, depending on the molar ratio between carboxylic
groups and Ca+2. In order to verify a possible use of these hydrogels as drug delivery systems, acyclovir was loaded into the network. Rheological
analysis evidenced that the loaded drug can affect the hydrogel elastic modulus. The release of acyclovir in phosphate buffer
was evaluated at different temperatures in order to assess the suitability of this novel drug delivery system in topical applications. 相似文献
63.
Optical coatings offer a solution to the problem of damage to paintings, caused by ultraviolet and infrared radiation, by cutting radiation wavelengths outside the visible range. Simultaneously, these coatings can enhance an observer's viewing of the paintings by reducing the reflections from ordinary glass panes. All these functions should be performed by the same coating. The design of such a coating, as well as the evaluation of existing products, requires the definition of an appropriate merit function in which coating absorption, high transparency, and color rendering are combined. 相似文献
64.
The reflecting grating interferometer (RGI) is a folded and reversal wave-front interferometer sensitive only to asymmetrical aberrations such as third-order coma. The RGI can isolate and evaluate coma both in nearly collimated and in noncollimated beams. We propose a RGI with a different optical configuration that includes a lateral shearing in addition to folding and reversal operations. With lateral shear, the RGI also becomes sensitive to other terms of third-order aberrations such as defocusing, astigmatism, and spherical aberration. Optical path difference equations for interpreting interferograms and numerical simulations are presented to show how the interferometer works in the shearing configuration. Its potential applications are described and discussed. 相似文献
65.
66.
Pietro Cenciarelli Alessandro Tiberi 《Electronic Notes in Theoretical Computer Science》2005,127(5):3
We present a case study where Synchronising Graphs, a system of parallel graph transformation, are used to solve the syntactic unification problem for first order rational terms (with possibly infinite unifier). The solution we offer is efficient, that is quasi-linear, and simple: a program of 28 characters. 相似文献
67.
Reviews the literature on predictable and unpredictable shock conditions relative to physiological measures of stressfulness and considers the possible role of stress-induced analgesia in both physiological and behavioral effects. Findings suggest that unpredictable conditions are physiologically more stressful than predictable conditions when Ss are exposed to them for one or a few sessions and when parameters of stress are relatively severe. However, predictable conditions may be more stressful than unpredictable conditions when sessions are long and extend over days and when parameters of stress are less severe. The effect of extended stress appears to depend on the physiological measure used. These findings are discussed in terms of the phasic vs chronic nature of predictable vs unpredictable stress and the organism's ability to adapt physiologically to these conditions. Data on stress-induced analgesia are also reviewed. It is concluded that stress-induced analgesia does not significantly contribute to either preference for predictable over unpredictable stress or to their differential physiological effects. (88 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
68.
Furey-Kurkjian Maura L.; Pietrini Pietro; Graff-Radford Neill R.; Alexander Gene E.; Freo Ulderico; Szczepanik Joanna; Schapiro Mark B. 《Canadian Metallurgical Quarterly》1996,10(2):294
A subgroup of patients with probable Alzheimer disease (AD) reported a history of isolated visual disturbances (VS) early in the course of disease, without the characteristic memory complaints. Brain imaging and neuropathologic studies indicated that this subgroup had larger involvement of visual cortical areas and relative sparing of temporal. frontal, and limbic structures compared with classic AD. Consistent with these findings, the authors hypothesized that the cognitive deficits in this subgroup would be distinctly different from those seen in more typical AD patients. The authors studied 10 probable AD patients with VS (AD&±&|S), 22 patients without VS (AD–), and 25 healthy controls with a neuropsychological test battery. Compared with AD–, AD&±&|S patients performed significantly better on tests of verbal memory and had greater impairment on tests of visuospatial skills, suggesting a distinct pattern of cognitive dysfunction consistent with metabolic and neuropathologic reports. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
69.
A Ceriello N Bortolotti E Motz A Crescentini S Lizzio A Russo L Tonutti C Taboga 《Canadian Metallurgical Quarterly》1998,21(9):1529-1533
OBJECTIVE: Free radical production has been reported to be increased in diabetic patients and to be involved in the pathogenesis of diabetic complications. In this study, a standardized meal was administered to 10 type 2 diabetic patients and 10 healthy matched normal subjects to evaluate its effects on plasma oxidative stress generation. RESEARCH DESIGN AND METHODS: In diabetic patients, at baseline and after the meal, plasma malondialdehyde (MDA), vitamin C, protein SH groups, uric acid, vitamin E, and total plasma radical-trapping parameter, which evaluates plasma antioxidant capacity due to known and unknown antioxidants present in the plasma as well as their mutual cooperation, were measured. RESULTS: After the meal, plasma MDA and vitamin C increased, while protein SH groups, uric acid, vitamin E, and total plasma radical-trapping parameter decreased more significantly in the diabetic subjects than in control subjects. CONCLUSIONS: This finding shows that in the absorptive phase, free radicals are produced in diabetic patients. Since plasma glucose, but not insulin, rose significantly more in diabetic subjects than in control subjects, hyperglycemia may play an important role in the generation of postprandial oxidative stress in diabetic patients. 相似文献
70.