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1
Persson, Jonas, Cindy Lustig, James K. Nelson e Patricia A. Reuter-Lorenz. "Age Differences in Deactivation: A Link to Cognitive Control?" Journal of Cognitive Neuroscience 19, n. 6 (giugno 2007): 1021–32. http://dx.doi.org/10.1162/jocn.2007.19.6.1021.
Testo completoAbstract (sommario):
The network of regions shown by functional imaging studies to be deactivated by experimental tasks relative to nominally more passive baselines (task < baseline) may reflect processes engaged during the resting state or “default mode.” Deactivation may result when attention and resources are diverted from default-mode processes toward task processes. Aging is associated with altered patterns of deactivation which may be related to declining resources, difficulties with resource allocation, or both. These possibilities predict that greater task demand, which increases deactivation levels in younger adults, should exacerbate age-related declines in allocating resources away from the default mode. The present study investigated the magnitude and temporal properties of deactivations in young and older adults during tasks that varied in their demand for cognitive control. Two versions of a verb generation task that varied in their demand for selection among competing alternatives were compared to word reading and a fixation baseline condition. Consistent with our hypothesis, greater deactivations were found with increasing demand. Young and older adults showed equivalent deactivations in the minimal selection condition. By contrast, age differences in both the magnitude and time course of deactivation increased with selection demand: Compared to young adults', older adults' deactivation response showed less sensitivity to demand. Demand-related changes in deactivation magnitude correlated with performance changes, suggesting that individual and group differences in deactivation have functional significance.
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Serdyukov, D. V., O. V. Kanunnikov, V. A. Akselrod e N. G. Loyko. "Antimicrobial Properties of a Biocide Based on Quaternary Ammonium Compounds plus Polyhexamethylene Guanidine and Possible Methods of Its Deactivation". Biotekhnologiya 36, n. 6 (2020): 115–26. http://dx.doi.org/10.21519/0234-2758-2020-36-6-115-126.
Testo completoAbstract (sommario):
Biocidal agents (BA) are widely used in environmentally safe toilet complexes (ESTC) of passenger railcars to suppress microbial activity in fаecal sludge (FS). Subsequent disposal of BA-containing FS at municipal sewage treatment facilities adversely affects their work due to the loss of activated sludge. The antimicrobial properties of BA, based on quaternary ammonium compounds (QAC) and polyhexamethylene guanidine (PHMG), as well as methods for its neutralization, have been studied. It was confirmed that BA based on QAC and PHMG has an antimicrobial effect on various groups of bacteria, reducing their number by 10-100 or more times. It was found that FS contains two groups of microorganisms with different sensitivity to BA. Methods for deactivation of the BA antimicrobial action in FS were tested using: (1), a deactivating agent; (2), incubation with thermophilically digested wastewater sludge as a source of the microbial methanogenic community; and (3), chemical deactivation by acidification or alkalization. The highest efficiency was shown by the method of deactivation of BA via thermophilic anaerobic digestion with pretreatment of FS with a strong acid biocide, fаecal sludge of ESTC of passenger railcars, antimicrobial activity, quaternary ammonium compounds, polyhexamethylene guanidine, deactivator, methanogenic microbial community This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation.
3
Garner, Daniel, Matthew Blackburn, David J. Wright e Archana Rao. "Improving guideline-mandated care of patients with implantable cardiac defibrillators". British Journal of Hospital Medicine 81, n. 8 (2 agosto 2020): 1–10. http://dx.doi.org/10.12968/hmed.2020.0259.
Testo completoAbstract (sommario):
Background/Aims Implantable cardiac defibrillators reduce the risk of sudden cardiac death in selected patients. The value of an implantable cardiac defibrillator declines as the patient's disease progresses. Guidelines suggest that the appropriateness of maintaining implantable cardiac defibrillator therapy be regularly reviewed as part of monitoring of the patient's disease trajectory. It is recommended that implantable cardiac defibrillators are deactivated as patients approach the end of life. Patients with a better understanding of their current state of health and the role that the implantable cardiac defibrillator plays within it are more likely to make informed decisions about the timing of deactivation. Methods: A quality improvement project was undertaken on appropriate deactivation of implantable cardiac defibrillators within a large tertiary cardiac centre. This was driven by audit data showing inadequate patient communication and documentation around deactivation. Drivers for change included the introduction of electronic data records, clinical review of comorbid patients approaching elective battery change and an ongoing forum for patient and carer education. Measured outcomes included the number of deactivations performed, evidence of patient discussion and consent, and timing of deactivation of the implantable cardiac defibrillator. Results There were increased numbers of timely device deactivations undertaken following the interventions with improved documented evidence of patient discussion and consent. The educational forum was received favourably. Conclusions Focused multidisciplinary interventions can impact favourably on appropriate implantable cardiac defibrillator deactivation and improve patient engagement.
4
Malhotra, Shveta, e Stephen G. Lomber. "Sound Localization During Homotopic and Heterotopic Bilateral Cooling Deactivation of Primary and Nonprimary Auditory Cortical Areas in the Cat". Journal of Neurophysiology 97, n. 1 (gennaio 2007): 26–43. http://dx.doi.org/10.1152/jn.00720.2006.
Testo completoAbstract (sommario):
Although the contributions of primary auditory cortex (AI) to sound localization have been extensively studied in a large number of mammals, little is known of the contributions of nonprimary auditory cortex to sound localization. Therefore the purpose of this study was to examine the contributions of both primary and all the recognized regions of acoustically responsive nonprimary auditory cortex to sound localization during both bilateral and unilateral reversible deactivation. The cats learned to make an orienting response (head movement and approach) to a 100-ms broad-band noise stimulus emitted from a central speaker or one of 12 peripheral sites (located in front of the animal, from left 90° to right 90°, at 15° intervals) along the horizontal plane after attending to a central visual stimulus. Twenty-one cats had one or two bilateral pairs of cryoloops chronically implanted over one of ten regions of auditory cortex. We examined AI [which included the dorsal zone (DZ)], the three other tonotopic fields [anterior auditory field (AAF), posterior auditory field (PAF), ventral posterior auditory field (VPAF)], as well as six nontonotopic regions that included second auditory cortex (AII), the anterior ectosylvian sulcus (AES), the insular (IN) region, the temporal (T) region [which included the ventral auditory field (VAF)], the dorsal posterior ectosylvian (dPE) gyrus [which included the intermediate posterior ectosylvian (iPE) gyrus], and the ventral posterior ectosylvian (vPE) gyrus. In accord with earlier studies, unilateral deactivation of AI/DZ caused sound localization deficits in the contralateral field. Bilateral deactivation of AI/DZ resulted in bilateral sound localization deficits throughout the 180° field examined. Of the three other tonotopically organized fields, only deactivation of PAF resulted in sound localization deficits. These deficits were virtually identical to the unilateral and bilateral deactivation results obtained during AI/DZ deactivation. Of the six nontonotopic regions examined, only deactivation of AES resulted in sound localization deficits in the contralateral hemifield during unilateral deactivation. Although bilateral deactivation of AI/DZ, PAF, or AES resulted in profound sound localization deficits throughout the entire field, the cats were generally able to orient toward the hemifield that contained the acoustic stimulus, but not accurately identify the location of the stimulus. Neither unilateral nor bilateral deactivation of areas AAF, VPAF, AII, IN, T, dPE, nor vPE had any effect on the sound localization task. Finally, bilateral heterotopic deactivations of AI/DZ, PAF, or AES yielded deficits that were as profound as bilateral homotopic cooling of any of these sites. The fact that deactivation of any one region (AI/DZ, PAF, or AES) was sufficient to produce a deficit indicated that normal function of all three regions was necessary for normal sound localization. Neither unilateral nor bilateral deactivation of AI/DZ, PAF, or AES affected the accurate localization of a visual target. The results suggest that hemispheric deactivations contribute independently to sound localization deficits.
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Jaklová, Karolína Dlasková, Lucie Šindelářová, Jan Kohout, Ivana Hradecká, Nikita Sharkov e Aleš Vráblík. "Comparison of the Accelerated and Spontaneous Deactivation of the HDS Catalyst". Processes 9, n. 12 (14 dicembre 2021): 2258. http://dx.doi.org/10.3390/pr9122258.
Testo completoAbstract (sommario):
Owing to the increased use of secondary materials for diesel production, refineries must confront bad quality parameters. Therefore, catalysts with certain capabilities (to remove heteroatoms and improve quality parameters at low hydrogen consumption) and their lifetimes are required. An important parameter that influences the quality of the products and the economy of the unit is the activity of the catalyst. Prior to industrial use, the catalyst is typically tested in a pilot unit. This is necessary to obtain a considerable amount of data on the lifetime of the catalyst in the shortest feasible time. Here, deactivation steps were used to test the catalyst. Two experiments were performed to evaluate the effect of two types of accelerated deactivations on the catalyst activity and product properties. The first type of deactivation proceeded for 6 h and comprised a tripling of the amount of incoming feedstock, and the second type proceeded for 18 h without an increase in the amount of feedstock. For both cases, the pressure and hydrogen flow were minimised. Both types of accelerated deactivations had similar effects on the quality of the final products and catalyst. The only difference was in the duration of catalyst recovery after deactivation. The results were compared with those of a test in which the spontaneous deactivation of the catalyst was studied.
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Madre, M., E. Pomarol-Clotet, P. McKenna, J. Radua, J. Ortiz-Gil, F. Panicali, J. M. Goikolea et al. "Brain functional abnormality in schizo-affective disorder: an fMRI study". Psychological Medicine 43, n. 1 (15 maggio 2012): 143–53. http://dx.doi.org/10.1017/s0033291712000943.
Testo completoAbstract (sommario):
BackgroundSchizo-affective disorder has not been studied to any significant extent using functional imaging. The aim of this study was to examine patterns of brain activation and deactivation in patients meeting strict diagnostic criteria for the disorder.MethodThirty-two patients meeting Research Diagnostic Criteria (RDC) for schizo-affective disorder (16 schizomanic and 16 schizodepressive) and 32 matched healthy controls underwent functional magnetic resonance imaging (fMRI) during performance of the n-back task. Linear models were used to obtain maps of activations and deactivations in the groups.ResultsControls showed activation in a network of frontal and other areas and also deactivation in the medial frontal cortex, the precuneus and the parietal cortex. Schizo-affective patients activated significantly less in prefrontal, parietal and temporal regions than the controls, and also showed failure of deactivation in the medial frontal cortex. When task performance was controlled for, the reduced activation in the dorsolateral prefrontal cortex (DLPFC) and the failure of deactivation of the medial frontal cortex remained significant.ConclusionsSchizo-affective disorder shows a similar pattern of reduced frontal activation to schizophrenia. The disorder is also characterized by failure of deactivation suggestive of default mode network dysfunction.
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Wöhrl, Katharina, Yash Kotak, Christian Geisbauer, Sönke Barra, Gudrun Wilhelm, Gerhard Schneider e Hans-Georg Schweiger. "Analysis of Deactivation of 18,650 Lithium-Ion Cells in CaCl2, Tap Water and Demineralized Water for Different Insertion Times". Sensors 23, n. 8 (11 aprile 2023): 3901. http://dx.doi.org/10.3390/s23083901.
Testo completoAbstract (sommario):
The deployment of battery-powered electric vehicles in the market has created a naturally increasing need for the safe deactivation and recycling of batteries. Various deactivating methods for lithium-ion cells include electrical discharging or deactivation with liquids. Such methods are also useful for cases where the cell tabs are not accessible. In the literature analyses, different deactivation media are used, but none include the use of calcium chloride (CaCl2) salt. As compared to other media, the major advantage of this salt is that it can capture the highly reactive and hazardous molecules of Hydrofluoric acid. To analyse the actual performance of this salt in terms of practicability and safety, this experimental research aims to compare it against regular Tap Water and Demineralized Water. This will be accomplished by performing nail penetration tests on deactivated cells and comparing their residual energy against each other. Moreover, these three different media and respective cells are analysed after deactivation, i.e., based on conductivity measurements, cell mass, flame photometry, fluoride content, computer tomography and pH value. It was found that the cells deactivated in the CaCl2 solution did not show any signs of Fluoride ions, whereas cells deactivated in TW showed the emergence of Fluoride ions in the 10th week of the insertion. However, with the addition of CaCl2 in TW, the deactivation process > 48 h for TW declines to 0.5–2 h, which could be an optimal solution for real-world situations where deactivating cells at a high pace is essential.
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Barker, Virgil M. "Deactivation of Pacemakers at the End of Life". Ethics & Medics 44, n. 9 (2019): 1–2. http://dx.doi.org/10.5840/em201944912.
Testo completoAbstract (sommario):
The liceity of deactivating pacemakers and implantable cardio-defibrillators at the end of life has been considered only recently. The current discussion divides into two main camps: those who view deactivation as the moral equivalent of the withdrawal of other life-sustaining interventions, and those who hold deactivation as the equivalent of physician-assisted suicide. Some authors contend that similar to a transplanted organ, the pacemaker establishes an organic unity with the human body. Hence, its deactivation is equivalent to the removal or disabling of an organ. On the contrary, the relationship of a pacemaker to the human body is similar to other supportive mechanical devices. There are burdens associated with the presence of these devices. In the face of a terminal diagnosis, the deactivation of a cardio-pacemaker is morally similar to the withdrawal of other extraordinary measures currently accepted within the Catholic moral teachings.
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Broering, J. M., e A. S. Bommarius. "Cation and strong co-solute effects on protein kinetic stability". Biochemical Society Transactions 35, n. 6 (23 novembre 2007): 1602–5. http://dx.doi.org/10.1042/bst0351602.
Testo completoAbstract (sommario):
Degradation of proteins is important for the operating life of biocatalysts and the shelf life of protein pharmaceuticals. We have previously found that the deactivating effects of salts on proteins can be correlated to an indicator of ion hydration, the B-viscosity coefficient of the anion in solution. Here, we test the influence of cations on protein kinetic stability by observing deactivation of mRFP (monomeric red fluorescent protein) in ammonium, caesium and chloride salt solutions, and we find that mRFP deactivation does not depend on cation hydration. We also measure mRFP deactivation in solutions containing denaturants (guanidinium chloride or urea) or stabilizing co-solutes (glycerol or sucrose) frequently encountered in many protein formulations to test whether hydration of these co-solutes can be used to indicate their relative effects on protein kinetic stability. We find that mRFP deactivation in solutions containing kosmotropic salts or stabilizers reaches a limiting rate and that hydration of denaturants is not an indicator of their denaturing strength.
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Harrisson, Simon. "The Chain Length Distribution of an Ideal Reversible Deactivation Radical Polymerization". Polymers 10, n. 8 (8 agosto 2018): 887. http://dx.doi.org/10.3390/polym10080887.
Testo completoAbstract (sommario):
The chain length distribution (CLD) of a reversible deactivation radical polymerization at full conversion is shown to be a negative binomial distribution with parameters that are simple functions of the number-average degree of polymerization and either the chain transfer constant (in the case of polymerizations that incorporate a reversible chain transfer step) or the concentrations of dormant polymer chains and deactivating agent and the rate constants of propagation and deactivation (other types of RDRP). Expressions for the CLD at intermediate conversions are also derived, and shown to be consistent with known expressions for the number-average degree of polymerization and dispersity. It is further demonstrated that these CLDs are well-approximated by negative binomial distributions with appropriate choice of parameters. The negative binomial distribution is thus a useful model for CLDs of reversible deactivation radical polymerizations.
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Vidal, Ana Cristina, Paula Banca, Augusto Gil Pascoal, Gustavo Cordeiro, João Sargento-Freitas e Miguel Castelo-Branco. "Modulation of Cortical Interhemispheric Interactions by Motor Facilitation or Restraint". Neural Plasticity 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/210396.
Testo completoAbstract (sommario):
Cortical interhemispheric interactions in motor control are still poorly understood and it is important to clarify how these depend on inhibitory/facilitatory limb movements and motor expertise, as reflected by limb dominance. Here we addressed this problem using functional magnetic resonance imaging (fMRI) and a task involving dominant/nondominant limb mobilization in the presence/absence of contralateral limb restraint. In this way we could modulate excitation/deactivation of the contralateral hemisphere. Blocks of arm elevation were alternated with absent/present restraint of the contralateral limb in 17 participants. We found the expected activation of contralateral sensorimotor cortex and ipsilateral cerebellum during arm elevation. In addition, only the dominant arm elevation (hold period) was accompanied by deactivation of ipsilateral sensorimotor cortex, irrespective of presence/absence of contralateral restraint, although the latter increased deactivation. In contrast, the nondominant limb yielded absent deactivation and reduced area of contralateral activation upon restriction. Our results provide evidence for a difference in cortical communication during motor control (action facilitation/inhibition), depending on the “expertise” of the hemisphere that controls action (dominant versus nondominant). These results have relevant implications for the development of facilitation/inhibition strategies in neurorehabilitation, namely, in stroke, given that fMRI deactivations have recently been shown to reflect decreases in neural responses.
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Hernandez-Ojeda, Jaime, e Pablo Requena. "Deactivating permanent pacemakers in pacemakerdependent patients with terminal illness: an ethical perspective". Medicina e Morale 72, n. 3 (27 ottobre 2023): 313–27. http://dx.doi.org/10.4081/mem.2023.1245.
Testo completoAbstract (sommario):
Medical guidelines state that both implantable cardioverter defibrillator (ICD) and pacemaker deactivation may be ethically permissible when the patient requests their withdrawal based on the respect for the patient’s autonomy. However, they also state that most physicians make an ethical distinction between deactivating ICDs and deactivating permanent pacemakers in pacemaker-dependent patients, being reasonably uncomfortable when confronted with a petition for pacing deactivation in these patients. If a difference between both actions exists, what principles explain this ethical distinction? We analyze this question from the perspective of the bioethical principles and the standpoint of the distinction between substitution and replacement therapies for ethical decisions. Even if we recognize appropriate insights in these proposals, they are insufficient to provide an adequate ethical justification in case of pacemaker deactivation in pacemaker-dependent patients. We propose the burden of therapy and the configuration of the moral act as determinant factors in arriving at a solid answer. In these cases, it is necessary to arrive at a description as precise as possible of the moral action that is performed and to ask what is the basic intentionality that moves such action. Furthermore, we propose the communication virtues as an important aspect to practice in cases of request of a pacemaker withdrawal.
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Šima, Jozef. "(Non)luminescent properties of iron compounds". Acta Chimica Slovaca 8, n. 2 (1 ottobre 2015): 126–32. http://dx.doi.org/10.1515/acs-2015-0022.
Testo completoAbstract (sommario):
Abstract This mini-review evaluates deactivation processes of iron-containing species and substances in solutions and the solid state with the focus on radiation deactivations from their electronically excited states. Theoretical and practical aspects of luminescence are assessed and conclusions based on up-to-date experimental data are formulated.
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Landin-Romero, R., P. J. McKenna, P. Salgado-Pineda, S. Sarró, C. Aguirre, C. Sarri, A. Compte et al. "Failure of deactivation in the default mode network: a trait marker for schizophrenia?" Psychological Medicine 45, n. 6 (21 ottobre 2014): 1315–25. http://dx.doi.org/10.1017/s0033291714002426.
Testo completoAbstract (sommario):
Background.Functional imaging studies in relatives of schizophrenic patients have had inconsistent findings, particularly with respect to altered dorsolateral prefrontal cortex activation. Some recent studies have also suggested that failure of deactivation may be seen.Method.A total of 28 patients with schizophrenia, 28 of their siblings and 56 healthy controls underwent functional magnetic resonance imaging during performance of the n-back working memory task. An analysis of variance was fitted to individual whole-brain maps from each set of patient–relative–matched pair of controls. Clusters of significant difference among the groups were then used as regions of interest to compare mean activations and deactivations among the groups.Results.In all, five clusters of significant differences were found. The schizophrenic patients, but not the relatives, showed reduced activation compared with the controls in the lateral frontal cortex bilaterally, the left basal ganglia and the cerebellum. In contrast, both the patients and the relatives showed significant failure of deactivation compared with the healthy controls in the medial frontal cortex, with the relatives also showing less failure than the patients. Failure of deactivation was not associated with schizotypy scores or presence of psychotic-like experiences in the relatives.Conclusions.Both schizophrenic patients and their relatives show altered task-related deactivation in the medial frontal cortex. This in turn suggests that default mode network dysfunction may function as a trait marker for schizophrenia.
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Guerrero-Pedraza, A., P. J. McKenna, J. J. Gomar, S. Sarró, R. Salvador, B. Amann, M. I. Carrión, R. Landin-Romero, J. Blanch e E. Pomarol-Clotet. "First-episode psychosis is characterized by failure of deactivation but not by hypo- or hyperfrontality". Psychological Medicine 42, n. 1 (7 luglio 2011): 73–84. http://dx.doi.org/10.1017/s0033291711001073.
Testo completoAbstract (sommario):
BackgroundIt is not known whether first-episode psychosis is characterized by the same prefrontal cortex functional imaging abnormalities as chronic schizophrenia.MethodThirty patients with a first episode of non-affective functional psychosis and 28 healthy controls underwent functional magnetic resonance imaging (fMRI) during performance of the n-back working memory task. Voxel-based analyses of brain activations and deactivations were carried out and compared between groups. The connectivity of regions of significant difference between the patients and controls was also examined.ResultsThe first-episode patients did not show significant prefrontal hypo- or hyperactivation compared to controls. However, they showed failure of deactivation in the medial frontal cortex. This area showed high levels of connectivity with the posterior cingulate gyrus/precuneus and parts of the parietal cortex bilaterally. Failure of deactivation was significantly greater in first-episode patients who had or went on to acquire a DSM-IV diagnosis of schizophrenia than in those who did not, and in those who met RDC criteria for schizophrenia compared to those who did not.ConclusionsFirst-episode psychosis is not characterized by hypo- or hyperfrontality but instead by a failure of deactivation in the medial frontal cortex. The location and connectivity of this area suggest that it is part of the default mode network. The failure of deactivation seems to be particularly marked in first-episode patients who have, or progress to, schizophrenia.
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P, Kudryavtsev. "Development of decontamination and detergents for the nuclear industry". International Journal of Hydrology 5, n. 4 (6 agosto 2021): 192–200. http://dx.doi.org/10.15406/ijh.2021.05.00280.
Testo completoAbstract (sommario):
At the enterprises of the radiochemical industry in the world, the task is to clean the technological and research equipment, overalls, and personnel from contamination with radioactive products. This task is especially relevant in case of emergencies, for example, such as an accident at a nuclear power plant in Fukushima, Japan. A review of the deactivation methods currently used is reviewed. It has been shown that the most typical pollutants are mixtures of radionuclides 137Cs, 144Ce, 144Pr, 90Sr, and 239Pu. All these elements are prone to the formation of chelate complexes. Therefore, complexing substances should be an essential component of deactivation solutions that form stable, water-soluble complex compounds with these radionuclides. When creating the recipe, we chose those complexing agents with the most persistent complex compounds with the expected pollutants. For research and testing in real conditions, we have prepared three types of technical detergents of various compositions with the code name MDS for decontaminating various surfaces, equipment, and workwear. The composition of these preparations consists mainly of an optimized mixture of surfactants, complexing agents, corrosion inhibitors, and processing aids. The studies were conducted to evaluate the possibility of using these funds for deactivation of premises, equipment, washing clothes in the Federal Unitary Enterprise "Mayak" and at its branch NIKIET in town Zarechny at Beloyarskyaya Nuclear Power Station in Russia. The effectiveness of deactivation was judged by the amount of residual contamination of the surface of the samples. The deactivating ability of MDS preparations for stainless, carbon steel, and plastic contaminated with β- and α-emitting nuclides was tested. The possibility of using MDS detergents for the deactivation of platinum ampoules stored as radioactive waste was assessed. The possibility of using MDS detergents for the deactivation of fabric materials, including underwear and work clothes, was also evaluated. The tests showed the high efficiency of the developed detergent MDS compared to the existing and currently used deactivation agents.
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Anuwongnukroh, Niwat, Surachai Dechkunakorn, Nathaphon Tangit e Subongkoch Tongkoom. "Effect of Temperature on Deactivation Force of Three Commercial NiTi Orthodontic Archwires". Advanced Materials Research 1025-1026 (settembre 2014): 325–29. http://dx.doi.org/10.4028/www.scientific.net/amr.1025-1026.325.
Testo completoAbstract (sommario):
Objective: The purpose of this study was to investigate the transition temperature range (TTR) and the effect of temperatures at 10, 20, 30, 40, 50 and 60 °C on the deactivation force of three commercially available NiTi archwires. Materials and methods: Three different brands of NiTi archwires, NiTi OR (Ormco), NiTi GH (G&H) and NiTi H (Highland), with a cross sectional area of 0.016 x 0.022 inch2 were analysed for transformation temperature range (TTR) by using differential scanning calorimeter and load-deflection characteristics using a three-point bending test at temperatures of 10, 20, 30, 37, 40, 50 and 60 °C. Statistical Analysis: Descriptive analysis was used to calculate each variable and Kruskal Wallis test was performed to assess the difference in measurements among the three NiTi wires. P<0.05 was considered as statistical significant. Results: TTR showed austenitic temperature finish (Af) at 24.45 °C for NiTi OR, 27.55 °C for NiTi GH and 51.5 °C for NiTi H. The highest deactivation force was found in NiTi H followed by NiTi OR and NiTi GH at the temperatures below and higher than 37°C. There were siginificant differences (p<0.05) in the deactivation force of NiTi OR - NiTi H and NiTi GH - NiTi H at 10 °C and 20 oC, and NiTi GH – NiTi H and NiTi GH – NiTi OR at 30 °C and 37 °C. However, no significant difference was found among all NiTi wires at 40, 50 and 60 oC, except NiTi GH – NiTi H at 60 oC. A close relationship was found between temperature and unloading curves (deactivaton force); increase in the temperature led to an increase in the plateau of delivery deactivation force and decrease in temperature led to a decrease in the plateau of delivery deactivation force. Conclusion: The TTRs of commercial NiTi archwires are variable, expecially the austenitic finish temperature. The deactivation force increases in higher temperature and decreases in lower temperature.
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Al Emam, Abdel R., David Barton, John Um e Gregory Pavlides. "Valve in Valve Trans-Catheter Aortic Valve Replacement Followed by LVAD Deactivation in the Setting of Recovered Systolic Function". Current Cardiology Reviews 16, n. 1 (28 gennaio 2020): 77–80. http://dx.doi.org/10.2174/1573403x15666190509082833.
Testo completoAbstract (sommario):
Background: Advanced heart failure has an extremely high mortality withoAdvanced heart failure has extremely high mortality without advanced therapies (left ventricular assist device (LVAD) implantation or cardiac transplant). LVAD patients with bioprosthetic aortic valve are more prone to leaflet fusion resulting in valvular stenosis and regurgitation.ut advanced therapies like Left ventricular assist devices or cardiac transplant. LVAD patients with bioprosthetic aortic valve are more prone to leaflet fusion resulting in valvular stenosis and regurgitation. We present a 46 year old patient who had LV systolic function recovery while on LVAD. However, he had a severely stenotic aortic valve bioprosthesis with leaflet fusion that had to be corrected before deactivating his LVAD. Due to high surgical risk, we performed valve-in-valve TAVR with an Evolut CoreValve , however, the patient had significant aortic regurgitation secondary to deployment above the bioprosthetic valve ring. We successfully deployed a second Evolut CoreValve inside the ring with excellent results. This was followed by a successful LVAD deactivation next day. His LV systolic function continued to recover and he had no heart failure symptoms at 3 month follow up. In the right settings, TAVR in recovered LVAD patients with aortic stenosis as bridge to LVAD deactivation is viable option, especially for patients who fall in the high risk group. To the best of our knowledge, this is the first reported case of a valve-in-valve TAVR followed by successful LVAD deactivation in the setting of recovered LV systolic function. Case Presentation: We present a 46-year-old patient who had LV systolic function recovery while on LVAD. However, he had a severely stenotic aortic valve bioprosthesis with leaflet fusion that had to be replaced before deactivating his LVAD. Due to high surgical risk, we performed valve-invalve Trans-Catheter Aortic Valve Replacement (TAVR) with an Evolut self-expanding valve, however, the patient had significant aortic regurgitation secondary to deployment above the bioprosthetic valve ring. We successfully deployed a second Evolut Self-expanding valve inside the ring with excellent results. This was followed by a successful LVAD deactivation next day. His LV systolic function continued to recover and he had no heart failure symptoms at 3 month follow up. In the right settings, TAVR in recovered LVAD patients with aortic stenosis as a bridge to LVAD deactivation is a viable option, especially for patients who fall in the high-risk group. Conclusion: To the best of our knowledge, this is the first reported case of a valve-in-valve TAVR followed by successful LVAD deactivation in the setting of recovered LV systolic function.
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Vicini, Stefano, Jian Feng Wang, Jin Hong Li, Wei Jian Zhu, Yue Hua Wang, Jian Hong Luo, Barry B. Wolfe e Dennis R. Grayson. "Functional and Pharmacological Differences Between RecombinantN-Methyl-d-Aspartate Receptors". Journal of Neurophysiology 79, n. 2 (1 febbraio 1998): 555–66. http://dx.doi.org/10.1152/jn.1998.79.2.555.
Testo completoAbstract (sommario):
Vicini, Stefano, Jian Feng Wang, Jin Hong Li, Wei Jian Zhu, Yue Hua Wang, Jian Hong Luo, Barry B. Wolfe, and Dennis R. Grayson. Functional and pharmacological differences between recombinant N-methyl-d-aspartate receptors. J. Neurophysiol. 79: 555–566, 1998. N-methyl-d-aspartic acid (NMDA) receptors transiently transfected into mammalian HEK-293 cells were characterized with subunit-specific antibodies and electrophysiological recordings. Deactivation time course recorded in response to fastl-glutamate pulses were studied in isolated and lifted cells, as well as in outside-out membrane patches excised from cells expressing recombinant NR1 subunits in combination with the NR2A, NR2B, NR2C, or NR2D NMDA receptor subunits. Transfected cells were preidentified by the fluorescence emitted from the coexpressed Aequorea victoria jellyfish Green Lantern protein. Currents generated by NR1/NR2A channels displayed double exponential deactivation time course being faster than that in NR1/NR2B or NR1/NR2C channels. However, a large decay variability was observed within each cotransfection, suggesting that mechanisms additional to subunit composition may also regulate deactivation time course. NR1/NR2D channels displayed slowly deactivating currents. Channel deactivation was fast and comparable among receptors obtained by cotransfecting five distinct spliced variants of the NR1 subunit, each with the NR2A subunit. Additionally, recovery from desensitization was slower for NR1/NR2B than for NR1/NR2A channels. The average deactivation time course of responses to brief l-glutamate applications in cells where NR1/NR2A/NR2B cDNAs were cotransfected at variable ratio was intermediate between those of the NR1/NR2A and NR1/NR2B channels. Although immunocytochemical evidence indicates that the majority of cells are cotransfected by all plasmids in triple transfection, our experimental condition did not allow for a tight control of the expression of NMDA receptor subunits. This produced the result that many cells were characterized by deactivation time course and haloperidol sensitivities of separate NR1/NR2A and NR1/NR2B subunit heteromers. We also speculate on the possible formation of channels resulting from the coassembly in the same receptor of NR1/NR2A/NR2B subunits from a minority of cells that gave responses to brief application of l-glutamate characterized by slow deactivation time course and decreased haloperidol sensitivity.
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Thanavaro, Joanne L. "ICD Deactivation". Clinical Nursing Research 22, n. 1 (28 maggio 2012): 36–50. http://dx.doi.org/10.1177/1054773812443893.
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Forzatti, P. "Catalyst deactivation". Catalysis Today 52, n. 2-3 (14 settembre 1999): 165–81. http://dx.doi.org/10.1016/s0920-5861(99)00074-7.
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Hansen, N. R., e H. L. Schreyer. "Damage Deactivation". Journal of Applied Mechanics 62, n. 2 (1 giugno 1995): 450–58. http://dx.doi.org/10.1115/1.2895951.
Testo completoAbstract (sommario):
A phenomenological algorithm, motivated by the “mode I” microcrack opening and closing mechanism, is developed for the deactivation and reactivation of the damage effects as modeled by certain continuum damage mechanics theories. One-dimensional formulations with and without coupled plasticity are used to elucidate concepts associated with damage deactivation and to suggest multidimensional deactivation formulations applicable to continuum damage theories that employ a second-order tensor as the damage measure. Strain-based projection operators are used to deactivate the damage effects in the damage tensor. Motivated by observations from one-dimensional coupled formulations, both the total and elastic strains must be compressive for the damage to be rendered inactive. By introducing smooth functions to represent the transition from the active to the inactive state, discontinuities in the response are avoided. To illustrate the aspects associated with deactivation, a consistent set of examples using a strain-controlled one-cycle uniaxial stress loading is given for each formulation.
23
Sadana, Ajit. "Enzyme deactivation". Biotechnology Advances 6, n. 3 (gennaio 1988): 349—IN2. http://dx.doi.org/10.1016/0734-9750(88)91890-3.
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Henley, James P., e Ajit Sadana. "Deactivation theory". Biotechnology and Bioengineering 28, n. 8 (agosto 1986): 1277–85. http://dx.doi.org/10.1002/bit.260280821.
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25
Bond, G. C. "Catalyst deactivation". Applied Catalysis 37 (gennaio 1988): 359. http://dx.doi.org/10.1016/s0166-9834(00)80790-3.
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26
Layus, G. "The Event of Deactivation and Deactivation of Event". Versus 3, n. 2 (27 novembre 2023): 114–50. http://dx.doi.org/10.58186/2782-3660-2023-3-2-114-150.
Testo completoAbstract (sommario):
The paper addresses the notion of the messianic event in the philosophical project of Giorgio Agamben. The central reference for this paper is the book The Time that Remains: A Commentary on the Letter to the Romans, in which the Italian philosopher proposes his conception of messianism. The central event that lies at the foundation of this conception is the event of deactivation of the apparatus of law, which introduces the time of anomia. Based on a close reading of The Time that Remains, the author singles out three key features of the messianic event: 1) This event has already taken place in the past. 2) The event, as conceptualized by Agamben, is deprived of its capturing power and is deactivated and decomposed into parts. 3) The messianic event cannot be a foundation of any positive historical power, which constitutes an important aspect of the critical component of Agamben’s project. As the fifth section of the paper demonstrates, such understanding of the messianic event leads to an abolishment of the horizon of the future itself, which poses obstacles to the political potential of messianism and introduces serious limitations to Agamben’s philosophical strategy: if we abolish the possibility of the future event itself, we have nothing to do but to overlook and neglect the future.
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Lee, Nankyu, Jinil Park, Jonghwa Lee, Kyoungseok Park, Myoungsik Choi e Wongyu Kim. "Estimation of Fuel Economy Improvement in Gasoline Vehicle Using Cylinder Deactivation". Energies 11, n. 11 (8 novembre 2018): 3084. http://dx.doi.org/10.3390/en11113084.
Testo completoAbstract (sommario):
Cylinder deactivation is a fuel economy improvement technology that has attracted particular attention recently. The currently produced cylinder deactivation engines utilize fixed-type cylinder deactivation in which only a fixed number of cylinders are deactivated. As fixed-type cylinder deactivation has some shortcomings, variable-type cylinder deactivation with no limit on the number of deactivated cylinders is under research. For variable-type cylinder deactivation, control is more complicated and production cost is higher than fixed-type cylinder deactivation. Therefore, it is necessary to select the cylinder deactivation control method considering both advantages and disadvantages of the two control methods. In this study, a fuel economy prediction simulation model was created using the measurement data of various vehicles with engine displacements of 1.0–5.0 L. The fuel economy improvement of fixed-type cylinder deactivation was compared with that of variable-type cylinder deactivation using the created simulation. As a result of examining the fuel economy improvement of the test vehicle in the FTP-75 driving cycle, the improvement was 2.2–10.0% for fixed-type cylinder deactivation and 2.2–12.8% for variable-type cylinder deactivation. Furthermore, the effect of the engine load on fuel economy improvement under cylinder deactivation and the effect of changes in engine control were examined via a simulation.
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Pasqualotto, C. V., C. M. Bastiani, I. Zoldan, A. C. Motta, M. M. Costa, L. R. Santos, L. B. Rodrigues, G. Facco e F. Pilotto. "Deoxinivalenol deactivation in wheat grains treated with ammonia gas and its effect on Rattus norvegicus diet". Arquivo Brasileiro de Medicina Veterinária e Zootecnia 75, n. 6 (2023): 1165–70. http://dx.doi.org/10.1590/1678-4162-12962.
Testo completoAbstract (sommario):
ABSTRACT Fusarium head blight, also known as fusariosis, is caused by a fungus called Fusarium graminearum that produces the mycotoxin deoxynivalenol (DON). This toxin causes problems to human and animal health. Ammonia gas has been shown to be effective in deactivating mycotoxins. The objectives of this study were to evaluate the effectiveness of ammonia gas in the deactivation of DON in wheat grains, the effect of this treatment on its protein composition and the toxicity in rats fed with ammoniated wheat grains. Wheat samples were exposed to ammonia gas at concentrations of 0% (Control), 0.5%, 1% and 1.5%. It was observed that ammonia gas was effective in deactivating DON at concentrations of 1% and 1.5%. There was no difference in crude protein observed in the bromatological analysis of treated wheat grains in relation to the control. Regarding the toxicity of wheat grains treated with ammonia in the feeding of Wistar rats (Rattus norvegicus), no histopathological alterations were observed in the liver, kidneys, intestine and in the hematological profile. The results of this study demonstrated that the treatment of wheat with ammonia gas can contribute to the deactivation of DON without compromising its protein composition and animal health.
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Gromotka, Zoë, Gregory Yablonsky, Nickolay Ostrovskii e Denis Constales. "Three-Factor Kinetic Equation of Catalyst Deactivation". Entropy 23, n. 7 (27 giugno 2021): 818. http://dx.doi.org/10.3390/e23070818.
Testo completoAbstract (sommario):
The three-factor kinetic equation of catalyst deactivation was obtained in terms of apparent kinetic parameters. The three factors correspond to the main cycle with a linear, detailed mechanism regarding the catalytic intermediates, a cycle of reversible deactivation, and a stage of irreversible deactivation (aging), respectively. The rate of the main cycle is obtained for the fresh catalyst under a quasi-steady-state assumption. The phenomena of reversible and irreversible deactivation are presented as special separate factors (hierarchical separation). In this case, the reversible deactivation factor is a function of the kinetic apparent parameters of the reversible deactivation and of those of the main cycle. The irreversible deactivation factor is a function of the apparent kinetic parameters of the main cycle, of the reversible deactivation, and of the irreversible deactivation. The conditions of such separability are found. The obtained equation is applied successfully to describe the literature data on the reversible catalyst deactivation processes in the dehydration of acetaldehyde over TiO2 anatase and in crotonaldehyde hydrogenation on supported metal catalysts.
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Garoma, T., e J. Kocher. "Investigation of surfactant-modified activated carbon for recycled water disinfection". Water Science and Technology 62, n. 8 (1 agosto 2010): 1755–66. http://dx.doi.org/10.2166/wst.2010.458.
Testo completoAbstract (sommario):
This study investigated the effectiveness of surfactant-loaded granular activated carbon (GAC) to deactivate total coliform, E. coli, and enterococci found in tertiary effluent under various experimental conditions, i.e. varying surfactant dose, GAC dose, and contact time. The results indicate that GAC loaded with 100 mg/g of hexadecyltrimethylammonium bromide (CTAB) and didodecyldimethylammonium bromide (DDAB), achieved log reductions as high as 1.02 and 1.86 of total coliform, respectively. At varying GAC doses and contact times, 200 mg/g of DDAB dose achieved 99.9 to 100% reduction in total coliform at initial concentrations as high as 38,000 MPN/100 mL. Complete deactivation of E. coli and enterococci were observed for CTAB and DDAB at 200 mg/g dose for varying GAC doses and contact times used in this study. DDAB was more effective than CTAB at deactivating total coliform and E. coli, both Gram-negative bacteria, while both surfactants were shown to have similar disinfection capabilities against enterococci. Surfactant dose and GAC dose were shown to enhance bacteria deactivation; however, surfactant dose was found to be the most important parameter. For contact times evaluated in this research, bacterial deactivation remained the same or slightly decreased with contact time. In conclusion, surfactant-modified GAC can be used as an effective disinfection technique for recycled water.
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Kahana, Alon, Phyllis R. Robinson, Laura J. Lewis, Ete Z. Szuts e John E. Lisman. "ATP-independent deactivation of squid rhodopsin". Visual Neuroscience 9, n. 6 (dicembre 1992): 595–602. http://dx.doi.org/10.1017/s0952523800001838.
Testo completoAbstract (sommario):
AbstractDeactivation of light-activated squid rhodopsin was studied in vitro using GTPγS binding by G-protein as a direct measure of rhodopsin activity. Deactivation was inhibited by dilution of the retinal suspension or by removal of soluble components. Deactivation could be restored by addition of soluble material to washed membranes. These results indicate that the deactivation is not due entirely to a conformational transition within rhodopsin itself, but depends on the interaction with other molecules. The possibility that phosphorylation is involved in the deactivation was studied. Deactivation occurred in the presence and absence of added ATP. Deactivation also occurred in the presence of kinase inhibitors and after addition of apyrase, which reduced residual ATP levels to below 1μM. These results indicate that light-induced phosphorylation is not required for deactivation of squid rhodopsin. In this regard deactivation of squid rhodopsin is different from that of vertebrate rhodopsin, which requires phosphorylation.
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Roshanaei, Abbas, e Mehdi Alavi. "Kinetic study of propane aromatization over Zn/HZSM-5 zeolite under conditions of catalyst deactivation using genetic algorithm". Journal of the Serbian Chemical Society 83, n. 4 (2018): 473–88. http://dx.doi.org/10.2298/jsc170621007r.
Testo completoAbstract (sommario):
The kinetic studies of propane aromatization reaction over Zn/ /HZSM-5 catalyst at temperature of 500?560?C and space velocity of 500?2500 cm3 gcat -1 h-1, in a plug flow reactor, under catalyst deactivating conditions were performed. A lumped kinetic model consisting of six lumped components and six reaction steps was proposed to describe the aromatization of propane. The kinetic model involves 18 kinetic parameters and one catalyst deactivation constant. The reaction steps orders were obtained by the power law model. Frequency factors and the apparent activation energies of the reaction steps were calculated based on the Arrhenius equation. An exponential function depending on the time-on-stream was applied for the catalyst deactivation model and the kinetic parameters were calculated via a genetic algorithm. The kinetic results indicated that the lumped kinetic model can well estimate the product yields of propane aromatization.
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McGhee, Michael, Ziman Wang, Alexander Bech, Paul J. Shayler e Dennis Witt. "The effects of cylinder deactivation on the thermal behaviour and fuel economy of a three-cylinder direct injection spark ignition gasoline engine". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, n. 11 (25 ottobre 2018): 2838–49. http://dx.doi.org/10.1177/0954407018806744.
Testo completoAbstract (sommario):
The changes in thermal state, emissions and fuel economy of a 1.0-L, three-cylinder direct injection spark ignition engine when a cylinder is deactivated have been explored experimentally. Cylinder deactivation improved engine fuel economy by up to 15% at light engine loads by reducing pumping work, raising indicated thermal efficiency and raising combustion efficiency. Penalties included an increase in NOx emissions and small increases in rubbing friction and gas work losses of the deactivated cylinder. The cyclic pressure variation in the deactivated cylinder falls rapidly after deactivation through blow-by and heat transfer losses. After around seven cycles, the motoring loss is ~2 J/cycle. Engine structural temperatures settle within an 8- to 13-s interval after a switch between two- and three-cylinder operation. Engine heat rejection to coolant is reduced by ~13% by deactivating a cylinder, extending coolant warm-up time to thermostat-opening by 102 s.
34
Fardin, J. Igor. "The Politics of Play: Ugo La Pietra's Design Without Ends". Design Issues 39, n. 3 (2023): 19–29. http://dx.doi.org/10.1162/desi_a_00723.
Testo completoAbstract (sommario):
Abstract This article investigates the potential of play for design practice and theory. First, drawing on the works of linguist Emile Benveniste and philosopher Giorgio Agamben, I propose a theoretical understanding of play as an act capable of suspending and deactivating means-end relations. Second, I articulate what this deactivating potential of play entails for the field of design through close readings of a series of works by Italian architect, artist, and designer Ugo La Pietra. In doing so, I uncover the politics that this deactivation within design seems to point towards—a politics of play.
35
Standing, Holly, Richard G. Thomson, Darren Flynn, Julian Hughes, Kerry Joyce, Trudie Lobban, Stephen Lord et al. "‘You can’t start a car when there’s no petrol left’: a qualitative study of patient, family and clinician perspectives on implantable cardioverter defibrillator deactivation". BMJ Open 11, n. 7 (luglio 2021): e048024. http://dx.doi.org/10.1136/bmjopen-2020-048024.
Testo completoAbstract (sommario):
ObjectiveTo explore the attitudes towards implantable cardioverter defibrillator (ICD) deactivation and initiation of deactivation discussions among patients, relatives and clinicians.DesignA multiphase qualitative study consisting of in situ hospital ICD clinic observations, and semistructured interviews of clinicians, patients and relatives. Data were analysed using a constant comparative approach.SettingOne tertiary and two district general hospitals in England.ParticipantsWe completed 38 observations of hospital consultations prior to ICD implantation, and 80 interviews with patients, family members and clinicians between 2013 and 2015. Patients were recruited from preimplantation to postdeactivation. Clinicians included cardiologists, cardiac physiologists, heart failure nurses and palliative care professionals.ResultsFour key themes were identified from the data: the current status of deactivation discussions; patients’ perceptions of deactivation; who should take responsibility for deactivation discussions and decisions; and timing of deactivation discussions. We found that although patients and doctors recognised the importance of advance care planning, including ICD deactivation at an early stage in the patient journey, this was often not reflected in practice. The most appropriate clinician to take the lead was thought to be dependent on the context, but could include any appropriately trained member of the healthcare team. It was suggested that deactivation should be raised preimplantation and regularly reviewed. Identification of trigger points postimplantation for deactivation discussions may help ensure that these are timely and inappropriate shocks are avoided.ConclusionsThere is a need for early, ongoing and evolving discussion between ICD recipients and clinicians regarding the eventual need for ICD deactivation. The most appropriate clinician to instigate deactivation discussions is likely to vary between patients and models of care. Reminders at key trigger points, and routine discussion of deactivation at implantation and during advance care planning could prevent distressing experiences for both the patient and their family at the end of life.
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Pomarol-Clotet, E., R. Salvador, S. Sarró, J. Gomar, F. Vila, Á. Martínez, A. Guerrero et al. "Failure to deactivate in the prefrontal cortex in schizophrenia: dysfunction of the default mode network?" Psychological Medicine 38, n. 8 (29 maggio 2008): 1185–93. http://dx.doi.org/10.1017/s0033291708003565.
Testo completoAbstract (sommario):
BackgroundFunctional imaging studies using working memory tasks have documented both prefrontal cortex (PFC) hypo- and hyperactivation in schizophrenia. However, these studies have often failed to consider the potential role of task-related deactivation.MethodThirty-two patients with chronic schizophrenia and 32 age- and sex-matched normal controls underwent functional magnetic resonance imaging (fMRI) scanning while performing baseline, 1-back and 2-back versions of the n-back task. Linear models were used to obtain maps of activations and deactivations in the groups.ResultsThe controls showed activation in the expected frontal regions. There were also clusters of deactivation, particularly in the anterior cingulate/ventromedial PFC and the posterior cingulate cortex/precuneus. Compared to the controls, the schizophrenic patients showed reduced activation in the right dorsolateral prefrontal cortex (DLPFC) and other frontal areas. There was also an area in the anterior cingulate/ventromedial PFC where the patients showed apparently greater activation than the controls. This represented a failure of deactivation in the schizophrenic patients. Failure to activate was a function of the patients' impaired performance on the n-back task, whereas the failure to deactivate was less performance dependent.ConclusionsPatients with schizophrenia show both failure to activate and failure to deactivate during performance of a working memory task. The area of failure of deactivation is in the anterior prefrontal/anterior cingulate cortex and corresponds to one of the two midline components of the ‘default mode network’ implicated in functions related to maintaining one's sense of self.
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Lomber, Stephen G., Shveta Malhotra e James M. Sprague. "Restoration of Acoustic Orienting Into a Cortically Deaf Hemifield by Reversible Deactivation of the Contralesional Superior Colliculus: The Acoustic “Sprague Effect”". Journal of Neurophysiology 97, n. 2 (febbraio 2007): 979–93. http://dx.doi.org/10.1152/jn.00767.2006.
Testo completoAbstract (sommario):
Removal of all contiguous visual cortical areas of one hemisphere results in a contralateral hemianopia. Subsequent deactivation of the contralesional superior colliculus (SC) nullifies the effects of the visual cortex ablation and restores visual orienting responses into the cortically blind hemifield. This deficit nullification has become known as the “Sprague Effect.” Similarly, in the auditory system, unilateral ablation of auditory cortex results in severe sound localization deficits, as assessed by acoustic orienting, to stimuli in the contralateral hemifield. The purpose of this study was to examine whether auditory orienting responses can be restored into the impaired hemifield during deactivation of the contralesional SC. Three mature cats were trained to orient toward and approach an acoustic stimulus (broadband, white noise burst) that was presented centrally, or at one of 12 peripheral loci, spaced at 15° intervals. After training, a cryoloop was chronically implanted over the dorsal surface of the right SC. During cooling of the cooling loop to temperatures sufficient to deactivate the superficial and intermediate layers (SZ, SGS, SO, SGI), auditory orienting responses were eliminated into the left (contracooled) hemifield while leaving acoustic orienting into the right (ipsicooled) hemifield unimpaired. This deficit was temperature-dependently graded from periphery to center. After the effectiveness of the SC cooling loop was verified, auditory cortex of the middle and posterior ectosylvian and anterior and posterior sylvian gyri was removed from the left hemisphere. As expected, the auditory cortex ablation resulted in a profound deficit in orienting to acoustic stimuli presented at any position in the right (contralesional) hemifield, while leaving acoustic orienting into the left (ipsilesional) hemifield unimpaired. The ablations of auditory cortex did not have any impact on a visual detection and orienting task. The additional deactivation of the contralesional SC to temperatures sufficient to cool the superficial and intermediate layers nullified the deficit caused by the auditory cortex ablation and acoustic orienting responses were restored into the right hemifield. This restoration was temperature-dependently graded from center to periphery. The deactivations were localized and confirmed with reduced uptake of radiolabeled 2-deoxyglucose. Therefore deactivation of the right superior colliculus after the ablation of the left auditory cortex yields a fundamentally different result from that identified during deactivation of the right superior colliculus before the removal of left auditory cortex in the same animal. Thus the “Sprague Effect” is not unique to a particular sensory system and deactivation of the contralesional SC can restore either visual or acoustic orienting responses into an impaired hemifield after cortical damage.
38
Davey, Stephen G. "Deciphering digoxin deactivation". Nature Reviews Chemistry 2, n. 7 (19 giugno 2018): 98. http://dx.doi.org/10.1038/s41570-018-0017-7.
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Guardiola, J., M. Proctor, H. Li, R. Punnakkattu, S. Lin e J. Yu. "Airway mechanoreceptor deactivation". Journal of Applied Physiology 103, n. 2 (agosto 2007): 600–607. http://dx.doi.org/10.1152/japplphysiol.01286.2006.
Testo completoAbstract (sommario):
Airway sensors play an important role in control of breathing. Recently, it was found that pulmonary slowly adapting stretch receptors (SARs) cease after a brief excitation following sodium pump blockade by ouabain. This deactivation can be explained by overexcitation. If this is true, mechanical stimulation of the SARs should also lead to a deactivation. In this study, we recorded unit activity of the SARs in anesthetized, open-chest, and mechanically ventilated rabbits and examined their responses to lung inflation at different constant pressures. Forty-seven of 137 units had a clear deactivation during the lung inflation. The deactivation threshold varied from unit to unit. For a given unit, the higher the inflation pressure, the sooner the deactivation occurs. For example, the SARs deactivated at 3.0 ± 0.3 and 4.8 ± 0.4 s when the lungs were inflated to constant pressures of 30 and 20 cmH2O, respectively ( n = 25, P < 0.0001). The units usually ceased after a brief intense discharge. In some units, their activity shifted to a lower level, indicating a pacemaker switching. Our results support the notion that SARs deactivate due to overexcitation.
40
Roncolatto, Rodolfo Eugênio, Mauri J. B. Cardoso, Yiu Lau Lam e M. Schmal. "FCC SOxAdditives Deactivation". Industrial & Engineering Chemistry Research 45, n. 8 (aprile 2006): 2646–50. http://dx.doi.org/10.1021/ie0511985.
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Hetem, M., G. Rutten, B. Vermeer, J. Rijks, L. van de Ven, J. de Haan e C. Cramers. "Deactivation with polymethylhydrosiloxane". Journal of Chromatography A 477, n. 1 (agosto 1989): 3–24. http://dx.doi.org/10.1016/s0021-9673(01)89614-x.
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Sadana, Ajit, e James P. Henley. "Deactivation-disguised kinetics". Journal of Biotechnology 5, n. 1 (febbraio 1987): 67–76. http://dx.doi.org/10.1016/0168-1656(87)90071-x.
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Paimon, Ahmad Solehin, Wira Jazair e Srithar Rajoo. "Parametric Study of Cylinder Deactivation and Valve Deactivation for Unthrottled Operation". Advanced Materials Research 614-615 (dicembre 2012): 525–28. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.525.
Testo completoAbstract (sommario):
Cylinder deactivation (CDA) as well as valve deactivation (VDA) technologies provides big potentials to decrease fuel consumption and emission at part load operation for SI engine. In real driving situation, an internal combustion engine operates in transient operation where the load and speed varies continuously. This part load operation leads the engine to have poor fuel consumption and emission due to throttle pumping losses. This paper will investigate the further potential of both induction strategy, cylinder deactivation and valve deactivation in extending the fuel economy at part load.
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Gustina, Ahleah S., e Matthew C. Trudeau. "hERG potassium channel gating is mediated by N- and C-terminal region interactions". Journal of General Physiology 137, n. 3 (28 febbraio 2011): 315–25. http://dx.doi.org/10.1085/jgp.201010582.
Testo completoAbstract (sommario):
Human ether-á-go-go–related gene (hERG) potassium channels have voltage-dependent closing (deactivation) kinetics that are unusually slow. A Per-Arnt-Sim (PAS) domain in the cytoplasmic N-terminal region of hERG regulates slow deactivation by making a direct interaction with another part of the hERG channel. The mechanism for slow deactivation is unclear, however, because the other regions of the channel that participate in regulation of deactivation are not known. To identify other functional determinants of slow deactivation, we generated hERG channels with deletions of the cytoplasmic C-terminal regions. We report that hERG channels with deletions of the cyclic nucleotide–binding domain (CNBD) had accelerated deactivation kinetics that were similar to those seen in hERG channels lacking the PAS domain. Channels with dual deletions of the PAS domain and the CNBD did not show further acceleration in deactivation, indicating that the PAS domain and the CNBD regulate deactivation by a convergent mechanism. A recombinant PAS domain that we previously showed could directly regulate PAS domain–deleted channels did not regulate channels with dual deletions of the PAS domain and CNBD, suggesting that the PAS domain did not interact with CNBD-deleted channels. Biochemical protein interaction assays showed that glutathione S-transferase (GST)–PAS (but not GST) bound to a CNBD-containing fusion protein. Coexpression of PAS domain–deleted subunits (with intact C-terminal regions) and CNBD-deleted subunits (with intact N-terminal regions) resulted in channels with partially restored slow deactivation kinetics, suggesting regulatory intersubunit interactions between PAS domains and CNBDs. Together, these data suggest that the mechanism for regulation of slow deactivation in hERG channels is an interaction between the N-terminal PAS domain and the C-terminal CNBD.
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Al-Shafei, Mansour A., Ahmed K. Al-Asseel, Abdulhadi M. Adab, Hasan A. Al-Jama, Amer A. Al-Tuwailib e Shouwen X. Shen. "Deactivation Mechanism of Titania Catalyst". Journal of Materials Science Research 5, n. 4 (27 agosto 2016): 22. http://dx.doi.org/10.5539/jmsr.v5n4p22.
Testo completoAbstract (sommario):
<p class="1Body">Catalyst deactivation is a well-recognized phenomenon in the petroleum and chemical processing industries. Identifying the root causes of this phenomenon is an important factor for enhancing catalyst efficiency and preventing undesirable failures. In this study, state-of-the-art instruments were utilized to investigate the causes of catalyst deactivation that led to the replacement of the catalyst bed in one of the sulfur recovery units at a Saudi Aramco gas plant. Titania catalysts have been examined to determine the inherent deactivation mechanism and also to find out the possibilities of its curement. Understanding the root cause of the deactivation is mandatory for field engineers to minimize future catalyst deactivation. The collected analysis data revealed that the deactivation mechanism occurred for the Ti catalyst due to irreversible chemical phase transformation of the catalyst caused by a temperature runway in the catalytic converter.</p>
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Zsiga, Norbert, Johannes Ritzmann e Patrik Soltic. "Practical Aspects of Cylinder Deactivation and Reactivation". Energies 14, n. 9 (28 aprile 2021): 2540. http://dx.doi.org/10.3390/en14092540.
Testo completoAbstract (sommario):
Cylinder deactivation is an effective measure to reduce the fuel consumption of internal combustion engines. This paper deals with several practical aspects of switching from conventional operation to operation with deactivated cylinders, i.e., gas spring operation with closed intake and exhaust valves. The focus of this paper lies on one particular quantity-controlled stoichiometrically-operated engine where the load is controlled using the valve timing. Nevertheless, the main results are transferable to other engines and engine types, including quality-controlled engines. The first aspect of this paper is an analysis of the transition from fired to gas spring operation, and vice versa, as well as the gas spring operation itself. This is essential for mode changes, such as cylinder deactivation or skip-firing operation. Simulation results show that optimizing the valve timing in the last cycle before deactivating/first cycle after reactivating a cylinder, respectively, is advantageous. We further show that steady-state gas spring operation is reached after approximately 6 s regardless of the initial conditions and the engine speed. The second aspect of this paper experimentally verifies the advantage of optimized valve timings. Furthermore, we show measurements that demonstrate the occurrence of an unavoidable torque ripple, especially when the transition to and from the deactivated cylinder operation is performed too quickly. We also confirm with our experiments that a more gradual mode transition reduces the torque drop.
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Ostrovski, Nikolaj, Svetlana Rovenskaja e Genadij Echevski. "Aromatization of light naphtha fractions on zeolites: 2. Model of catalyst deactivation". Chemical Industry 58, n. 3 (2004): 104–8. http://dx.doi.org/10.2298/hemind0403104o.
Testo completoAbstract (sommario):
A model of catalyst deactivation in the "Zeoforming" process was developed. The deactivation rate constants and activation energies were estimated. The role of adsorbed oligomers in the reaction and the deactivation kinetics were examined. The model is intended for further modeling and optimization of the process.
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Shi, Yu Patrick, Samrat Thouta, Yen May Cheng e Tom W. Claydon. "Extracellular protons accelerate hERG channel deactivation by destabilizing voltage sensor relaxation". Journal of General Physiology 151, n. 2 (7 dicembre 2018): 231–46. http://dx.doi.org/10.1085/jgp.201812137.
Testo completoAbstract (sommario):
hERG channels underlie the delayed-rectifier K+ channel current (IKr), which is crucial for membrane repolarization and therefore termination of the cardiac action potential. hERG channels display unusually slow deactivation gating, which contributes to a resurgent current upon repolarization and may protect against post-depolarization–induced arrhythmias. hERG channels also exhibit robust mode shift behavior, which reflects the energetic separation of activation and deactivation pathways due to voltage sensor relaxation into a stable activated state. The mechanism of relaxation is unknown and likely contributes to slow hERG channel deactivation. Here, we use extracellular acidification to probe the structural determinants of voltage sensor relaxation and its influence on the deactivation gating pathway. Using gating current recordings and voltage clamp fluorimetry measurements of voltage sensor domain dynamics, we show that voltage sensor relaxation is destabilized at pH 6.5, causing an ∼20-mV shift in the voltage dependence of deactivation. We show that the pH dependence of the resultant loss of mode shift behavior is similar to that of the deactivation kinetics acceleration, suggesting that voltage sensor relaxation correlates with slower pore gate closure. Neutralization of D509 in S3 also destabilizes the relaxed state of the voltage sensor, mimicking the effect of protons, suggesting that acidic residues on S3, which act as countercharges to S4 basic residues, are involved in stabilizing the relaxed state and slowing deactivation kinetics. Our findings identify the mechanistic determinants of voltage sensor relaxation and define the long-sought mechanism by which protons accelerate hERG deactivation.
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Saffari, Sara, Tiam M. Saffari e Jeffrey E. Janis. "Secondary Trigger Point Deactivation Surgery for Nerve Compression Headaches: A Scoping Review". Plastic and Reconstructive Surgery - Global Open 12, n. 2 (febbraio 2024): e5620. http://dx.doi.org/10.1097/gox.0000000000005620.
Testo completoAbstract (sommario):
Background: Primary trigger point deactivation surgery has been successful in reducing or eliminating nerve compression headaches between 79% and 90% of the time. The aim of this review article was to discuss the factors that contribute to index trigger point deactivation surgery failure, the importance of reevaluating trigger points following failure, and the options for secondary surgery. Methods: A literature search was performed using a combination of keywords involving “chronic headache” and “nerve deactivation surgery,” in databases until February 2023. Results: Data of 1071 patients were evaluated and included (11 articles). The failure rate after index trigger point deactivation surgery occurs is approximately 12%, primarily due to incomplete primary trigger point deactivation. Secondary trigger points may not appear until the primary trigger is eliminated, which occurs in 17.8% of patients. Reevaluation of previously diagnosed trigger points as well as uncovered trigger points and additional preoperative testing is indicated to help determine candidacy for further surgical deactivation. To address scarring that could contribute to failure, corticosteroid injection, acellular dermal matrix, adipofascial fat, or expanded polytetrafluoroethylene sleeves have been described with beneficial effects. For neuroma management, regenerative peripheral nerve interface, targeted muscle reinnervation, a combination of both, relocation nerve grafting, or nerve capping have also been described. Neurectomy can be performed when patients prefer anesthesia and/or paresthesia over current pain symptoms. Conclusion: Secondary trigger point deactivation surgery is indicated when there is suspicion of incomplete deactivation, internal scarring, neuroma, or newly-diagnosed trigger points.
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Malhotra, Shveta, G. Christopher Stecker, John C. Middlebrooks e Stephen G. Lomber. "Sound Localization Deficits During Reversible Deactivation of Primary Auditory Cortex and/or the Dorsal Zone". Journal of Neurophysiology 99, n. 4 (aprile 2008): 1628–42. http://dx.doi.org/10.1152/jn.01228.2007.
Testo completoAbstract (sommario):
We examined the contributions of primary auditory cortex (A1) and the dorsal zone of auditory cortex (DZ) to sound localization behavior during separate and combined unilateral and bilateral deactivation. From a central visual fixation point, cats learned to make an orienting response (head movement and approach) to a 100-ms broadband noise burst emitted from a central speaker or one of 12 peripheral sites (located in front of the animal, from left 90° to right 90°, at 15° intervals) along the horizontal plane. Following training, each cat was implanted with separate cryoloops over A1 and DZ bilaterally. Unilateral deactivation of A1 or DZ or simultaneous unilateral deactivation of A1 and DZ (A1/DZ) resulted in spatial localization deficits confined to the contralateral hemifield, whereas sound localization to positions in the ipsilateral hemifield remained unaffected. Simultaneous bilateral deactivation of both A1 and DZ resulted in sound localization performance dropping from near-perfect to chance (7.7% correct) across the entire field. Errors made during bilateral deactivation of A1/DZ tended to be confined to the same hemifield as the target. However, unlike the profound sound localization deficit that occurs when A1 and DZ are deactivated together, deactivation of either A1 or DZ alone produced partial and field-specific deficits. For A1, bilateral deactivation resulted in higher error rates (performance dropping to ∼45%) but relatively small errors (mostly within 30° of the target). In contrast, bilateral deactivation of DZ produced somewhat fewer errors (performance dropping to only ∼60% correct), but the errors tended to be larger, often into the incorrect hemifield. Therefore individual deactivation of either A1 or DZ produced specific and unique sound localization deficits. The results of the present study reveal that DZ plays a role in sound localization. Along with previous anatomical and physiological data, these behavioral data support the view that A1 and DZ are distinct cortical areas. Finally, the findings that deactivation of either A1 or DZ alone produces partial sound localization deficits, whereas deactivation of either posterior auditory field (PAF) or anterior ectosylvian sulcus (AES) produces profound sound localization deficits, suggests that PAF and AES make more significant contributions to sound localization than either A1 or DZ.