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Cerebral oxygenation in health and disease

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194537 Year: Pages: 144 DOI: 10.3389/978-2-88919-453-7 Language: English
Publisher: Frontiers Media SA
Subject: Physiology --- Science (General)
Added to DOAB on : 2016-02-05 17:24:33
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Scientists and clinicians interested in cerebrovascular physiology in humans now have numerous possibilities to monitor, invasively or non-invasively, the oxygenation status of cerebral tissue. Monitoring cerebral oxygenation has several utilities; to improve patient outcome, to better understand the mechanisms underlying orthostatic hypotension; to provide insight into functional neurovascular coupling; to evaluate the influence of vasopressors on cerebral oxygen levels in patients under anesthesia; and to study the limitations of exercise tolerance. This themed research topic, through theoretical and experimental papers, covers new and exciting issues related to the study of cerebral oxygenation in health and disease. This e-book includes manuscripts inclusive of original research, methodologies and reviews in the field of integrative physiology, cognitive testing, orthostatic stress, exercise physiology and anesthesia.

Design and Engineering of Microreactor and Smart-Scaled Flow Processes

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ISBN: 9783038420385 9783038420392 Year: Pages: 252 DOI: 10.3390/books978-3-03842-039-2 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2015-10-22 07:00:06
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Microreactors are small devices with sub-millimeter internals which have superb mass and heat transfer. Initially, they were used for reactions with very high demands on the latter, e.g. very exothermic reactions, gas-liquid reactions with interfacial transport issues, reactions with very fast kinetics which demands even faster mixing, and more. In this way, the processing window was opened widely and, also due to the minute volumes only present in the reaction zone, safe processing under otherwise hazardous conditions was enabled. This includes processing of reactions which are prone to thermal runaway and in the explosive regime. Scale-up of promising reactions and products which was hindered with conventional technology is now possible using the new equipment. This has widened the process development possibilities in chemical industry.In the last years, micro process technology was not only used for the very problematic synthetic issues which formerly had a dead-end position in industry’s process development. Rather, the scope of chemical reactions to be processed in microreactors was considerably widened by exploring new process conditions with regard to temperature, pressure, concentration, solvents, and more. This is commonly referred to as flow chemistry. This allowed to reduce the processing time-scale for many reactions to the minute range or even below which fits well to the residence times of microreactors. In addition, the process integration of several reactions in one flow to a multi-step synthesis has opened a new door in molecular diversity as well as system and process complexity. The same holds for the combination of reactions and separations in micro-flow. To achieve throughputs relevant for industrial production, smart scale-out to milli-flow units has established and supplemented the num­bering-up concept (parallelization of microchannels/-reactors operated under equal conditions).New innovations and enabling technologies need anyhow evaluation and benchmarking with conventional technology on the full-system level. Yet, microreactor technology has in the last years deepened so much into process intensification on a holistic scale that the focus increasingly is given towards the process dimension—to process design and automation, real-case applications, cost analysis, life-cycle assessment, and more. The impact on cost competitiveness and sustainability becomes well assessed.Facing this very recent scientific achievement, the special issue “Design and Engineering of Microreactor and Smart-Scaled Flow Processes” of the journal Processes aims to cover recent advances in the development of microreactor and smart-scaled flow processes towards the process level — in the sense as given above.

Bridging the gap before and after birth: Methods and technologies to explore the functional neural development in humans

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196876 Year: Pages: 114 DOI: 10.3389/978-2-88919-687-6 Language: English
Publisher: Frontiers Media SA
Subject: Neurology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
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Infant brain damage is a serious condition that affects millions of babies each year. The period from late gestation to the first year of life is the most critical one for the development of central and autonomous nervous systems. Medical conditions such as preterm birth may compromise brain function and the end result usually is that the baby may experience long-term neurological problems related to a wide range of psychological, physical and functional complications, with consequent life-long burdens for the individuals and their families, and a high socio-economic impact for the health care system and the whole of society. During the last years, several techniques have been employed to monitor the brain functional development in utero and after birth. As well, various analytical methods have been used to understand the functional maturation of the brain and the autonomous nervous system. However, in spite of the rapid improvement of diagnostic methods and procedures, there is still a widely recognized, severe shortage of clinically viable means for the high quality monitoring of the brain function in early life with a direct relevance to acute neurological illness and future neurocognitive outcomes. The studies collected in this e-book document the most recent advancements in monitoring systems, analytical methods and clinical diagnostic procedures that contribute to increase our knowledge of the functional development of the human brain and autonomous nervous system during pregnancy and after birth, with the ultimate goal of reducing fetal impairment and improving healthcare in the neonatal and infant period.

The Ischemic Penumbra: Still the Target for Stroke Therapies?

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196357 Year: Pages: 69 DOI: 10.3389/978-2-88919-635-7 Language: English
Publisher: Frontiers Media SA
Subject: Medicine (General) --- Neurology
Added to DOAB on : 2016-08-16 10:34:25
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The ischemic penumbra was initially defined by Symon, Lassen and colleagues in the 1970s as an area of brain tissue with inadequate blood flow to maintain electric activity of neurons but adequate blood flow to preserve the function of the ion channels. This area of tissue, receiving enough blood to survive but not enough to function, often surrounds or abuts the irreversibly damaged core in ischemic stroke. It was shown that if blood flow could be restored to this area of marginal perfusion, the tissue could survive and function again, and growth of the core could be prevented. Based on seminal PET studies, penumbra or "penumbral tissue" eventually took on a subtly different meaning - the area of brain that is destined to progress to infarct unless blood flow is restored within a particular time window. The penumbra thus became the target for all acute stroke interventions - to preserve viability of the tissue and restore function. New imaging techniques, including diffusion and perfusion MRI and CT perfusion, were developed to rapidly identify individuals with penumbra, who were thought to be the best candidates for aggressive interventions to restore blood flow, particularly beyond the licensed time-window for IV thrombolysis. However, most clinical trials have failed to establish the usefulness of identifying candidates for treatment in this way using pre-specified protocols and primary endpoints. These trials have used different and sometimes unvalidated thresholds of hypoperfusion as well as irreversible infarct and various definitions of significant penumbra (or mismatch between irreversible infarct and hypoperfused, but salvageable tissue), and reanalysis of their data using more refined image processing showed post-hoc positivity. They have also evaluated outcome in a variety of ways, with few studies measuring the direct effect of restoring blood flow on the function of the penumbral tissue. Therefore, important remaining questions include how to define, characterize, and image the penumbra in acute stroke to achieve the greatest reliability and validity for what we want to measure, and whether this concept, so defined, provides an optimal target for stroke therapy using state-of-the-art trial design.

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2015 (6)