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排序方式: 共有191条查询结果,搜索用时 328 毫秒
1.
Anastasiia Panfilova Sarah E. Shelton Cristina Caresio Ruud J.G. van Sloun Filippo Molinari Hessel Wijkstra Paul A. Dayton Massimo Mischi 《Ultrasound in medicine & biology》2019,45(2):539-548
Dynamic contrast-enhanced ultrasound (DCE-US) has been proposed as a powerful tool for cancer diagnosis by estimation of perfusion and dispersion parameters reflecting angiogenic vascular changes. This work was aimed at identifying which vascular features are reflected by the estimated perfusion and dispersion parameters through comparison with acoustic angiography (AA). AA is a high-resolution technique that allows quantification of vascular morphology. Three-dimensional AA and 2-D DCE-US bolus acquisitions were used to monitor the growth of fibrosarcoma tumors in nine rats. AA-derived vascular properties were analyzed along with DCE-US perfusion and dispersion to investigate the differences between tumor and control and their evolution in time. AA-derived microvascular density and DCE-US perfusion exhibited good agreement, confirmed by their spatial distributions. No vascular feature was correlated with dispersion. Yet, dispersion provided better cancer classification than perfusion. We therefore hypothesize that dispersion characterizes vessels that are smaller than those visible with AA. 相似文献
2.
Over the last five years, many activities have focused on the unexploited field of carrying out reactions on small scales. Due to the rapid development of new components, this paper deals with recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous difference in size between the microchannels and the fluid periphera of possible components this is not just a technical question. It touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development are questions that are addressed here with respect to the big industrial interest in microreactors. 相似文献
3.
4.
Hessel EA 《Perfusion》1992,7(3):161-194
Monitoring has been extensively reviewed in most textbooks of cardiothoracic surgery and anaesthesia, particularly in the recent textbooks on monitoring edited by Carol L Lake 1 and Casey D Blitt 2 and in the Journal of Clinical Monitoring. Although monitoring properly includes both pre- and postoperative periods, this review will concentrate exclusively on the operative period. I will also concentrate on new approaches or information which relate to more traditional approaches to monitoring. The emphasis in this review will not be on what we can monitor, but rather on what we should monitor. In this regard, I will analyse accuracy and identify sources of error and try to answer the following questions. Does the device or parameter measure (monitor) what we want to know? Does it improve patient outcome and safety? Is it cost-effective? Unfortunately, data are not always available to answer all these questions at present, but hopefully the discussions will make us aware of what we do and do not know, and what we should look for in the near future. 相似文献
5.
Frank F Eichenlaub M Hessel S Wondrazek F 《Journal of clinical laser medicine & surgery》1990,8(5):51-55
For laser-induced shockwave lithotripsy, the electromagnetic energy of a laser light pulse is converted intracorporeally into the acoustic energy of a shockwave. The lithotriptor is based on a specially developed, Q-switched Nd:YAG laser whose high power light pulses (70 mJ, 25 nsec) are coupled into a flexible quartz fiber with a core diameter of 600 mum. Using focusing elements, energy densities higher than 6 x 10 5 J m -2 can be achieved, resulting in an optical breakdown in water followed by a shockwave. As a result of different absorption mechanisms, the breakdown threshold can be decreased by placing a metallic target into the laser beam. The different shockwave formations of such optomechanical transducers have been measured. First clinical applications have been performed. 相似文献
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7.
Ma'moun Al‐Rawashdeh Xander Nijhuis Evgeny V. Rebrov Volker Hessel Jaap C. Schouten 《American Institute of Chemical Engineers》2012,58(11):3482-3493
The barrier‐based distributor is a multiphase flow distributor for a multichannel microreactor which assures flow uniformity and prevents channeling between the two phases. For N number of reaction channels, the barrier‐based distributor consists of a gas manifold, a liquid manifold, N barrier channels for the gas, N barrier channels for the liquid, and N mixers for mixing the phases before the reaction channels. The flow distribution is studied numerically using a method based on the hydraulic resistive networks (RN). The single phase hydraulic RN model (Commenge et al., 2002;48:345–358) is extended for two phases gas‐liquid Taylor flow. For ReGL <30, the accuracy for the model was above 90%. The developed‐model was used to study the effects of fabrication tolerance and barrier channel dimensions. A design methodology has been proposed as an algorithm to determine the required hydraulic resistance in the barrier channels and their dimensions. This methodology is demonstrated using a numerical example. © 2012 American Institute of Chemical Engineers AIChE J, 2012 相似文献
8.
Robert Wilson Emily Jarvis Mickael Montembault J. Nicole Hamblin Edith M. Hessel Anthony Cahn 《Clinical therapeutics》2018,40(8):1410-1417
Purpose
Novel therapies to treat chronic obstructive pulmonary disease are highly desirable. The safety, tolerability, and pharmacokinetic (PK) parameters of nemiralisib, a phosphoinositide 3-kinase δ inhibitor, administered via the Ellipta dry powder inhaler (GlaxoSmithKline, Research Triangle Park, North Carolina) was evaluated, including an assessment of oral bioavailability.Methods
This single-center, 3-part, placebo-controlled trial in 22 healthy subjects evaluated single (100 and 200 μg) and repeat (200 μg for 10 days) doses of inhaled nemiralisib in parts A (n?=?12) and B (n?=?12) (double-blind) and single doses of inhaled nemiralisib (200 µg) with and without charcoal block in Part C (n?=?6) (open-label, 2-period, crossover). There was a minimum 14-day washout period between dosing days.Findings
21 subjects completed the study, mean age was similar in the three parts (A: 49 years; B: 44 years; C: 55 years). After single doses of nemiralisib, observed plasma Cmax dropped rapidly, followed by a slower elimination phase. Near-dose proportionality was observed: mean (95% CI) plasma Cmax and AUC0–24 values were 174.3 pg/mL (96.9–313.3) and 694.6 pg·h/mL (503.5–958.2) for 100 μg and 398.9 pg/mL (318.3–500.1) and 1699.6 pg·h/mL (1273.3–2268.7) for 200 μg, respectively. Repeat dosing for 10 days showed exposures ~2- to 4-fold higher than on the single dose (peak, trough, and AUC0–24 levels), achieving steady-state by day 6. Mean AUC0–24 was 2193.6 pg·h/mL and 1645.3 pg·h/mL in the absence/presence of charcoal. Two non–drug-related adverse events were observed; neither was serious or resulted in withdrawal.Implications
Inhalation of nemiralisib was well tolerated in these healthy subjects. Plasma pharmacokinetic variables were well defined, and charcoal block data indicate that ~23% of the total systemic exposure after inhalation from Ellipta was attributable to orally absorbed drug. ClinicalTrials.gov identifier: NCT02691325. 相似文献9.
A compact photomicroreactor design for kinetic studies of gas‐liquid photocatalytic transformations 下载免费PDF全文
Yuanhai Su Volker Hessel Timothy Noël 《American Institute of Chemical Engineers》2015,61(7):2215-2227
A compact photomicroreactor assembly consisting of a capillary microreactor and small‐scale light emitting diodes was developed for the study of reaction kinetics in the gas‐liquid photocatalytic oxidation of thiophenol to phenyl disulfide within Taylor flow. The importance of photons was convincingly shown by a suction phenomenon due to the fast consumption of oxygen. Mass transfer limitations were evaluated and an operational zone without mass transfer effects was chosen to study reaction kinetics. Effects of photocatalyst loading and light sources on the reaction performance were investigated. Reaction kinetic analysis was performed to obtain reaction orders with respect to both thiophenol and oxygen based on heterogeneous and homogeneous experimental results, respectively. The Hatta number further indicated elimination of mass transfer limitations. Reaction rate constants at different photocatalyst loadings and different photon flux were calculated. Furthermore, the advantages of this photomicroreactor assembly for studying gas‐liquid photocatalytic reaction kinetics were demonstrated as compared with batch reactors. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2215–2227, 2015 相似文献