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1.
Subst Abuse Treat Prev Policy ; 19(1): 22, 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38610049

RESUMO

INTRODUCTION: Research has established natural recovery (NR) as an important pathway to substance use recovery. Studies investigating correlates of NR have mainly focused on demographic and substance use variables rather than life circumstances. This study seeks to better understand the phenomenon of natural recovery by (i) validating the international scientific literature concerning demographic and substance use indicators of NR in Flanders and (ii) assessing the additional explanatory power of recovery strengths and barriers during active addiction, controlling for demographic and substance use covariates. METHODS: A total of 343 persons in recovery from alcohol or drug use problems (≥ 3 months) completed an online cross-sectional survey in Flanders. Participants in NR and in recovery after following treatment were compared using multivariate linear regression models. Reasons for not following treatment were analyzed using inductive thematic analysis. RESULTS: Higher education level, lower severity of dependence, and cannabis use as the main problem substance (vs. alcohol) were statistically significant (p < 0.05) correlates of NR. When scores for the number of barriers and strengths associated with active addiction were added, barriers (but not strengths) were significantly associated with NR. When barrier items were individually tested, having untreated emotional or mental health problems, having a driver's license revoked and damaging property were statistically significant correlates. The most reported reason for not entering treatment was not experiencing any need to do so. CONCLUSION: The results highlight the importance of a holistic approach to recovery support across multiple life domains. Limitations and opportunities for further research are discussed.


Assuntos
Comportamento Aditivo , Cannabis , Transtornos Relacionados ao Uso de Substâncias , Humanos , Estudos Transversais , Etanol , Transtornos Relacionados ao Uso de Substâncias/epidemiologia
2.
Sci Rep ; 14(1): 8081, 2024 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-38582923

RESUMO

Astaxanthin, a versatile C40 carotenoid prized for its applications in food, cosmetics, and health, is a bright red pigment with powerful antioxidant properties. To enhance astaxanthin production in Corynebacterium glutamicum, we employed rational pathway engineering strategies, focused on improving precursor availability and optimizing terminal oxy-functionalized C40 carotenoid biosynthesis. Our efforts resulted in an increased astaxanthin precursor supply with 1.5-fold higher ß-carotene production with strain BETA6 (18 mg g-1 CDW). Further advancements in astaxanthin production were made by fine-tuning the expression of the ß-carotene hydroxylase gene crtZ and ß-carotene ketolase gene crtW, yielding a nearly fivefold increase in astaxanthin (strain ASTA**), with astaxanthin constituting 72% of total carotenoids. ASTA** was successfully transferred to a 2 L fed-batch fermentation with an enhanced titer of 103 mg L-1 astaxanthin with a volumetric productivity of 1.5 mg L-1 h-1. Based on this strain a pathway expansion was achieved towards glycosylated C40 carotenoids under heterologous expression of the glycosyltransferase gene crtX. To the best of our knowledge, this is the first time astaxanthin-ß-D-diglucoside was produced with C. glutamicum achieving high titers of microbial C40 glucosides of 39 mg L-1. This study showcases the potential of pathway engineering to unlock novel C40 carotenoid variants for diverse industrial applications.


Assuntos
Carotenoides , Corynebacterium glutamicum , Carotenoides/metabolismo , Corynebacterium glutamicum/genética , Corynebacterium glutamicum/metabolismo , Xantofilas/metabolismo , beta Caroteno/metabolismo , Engenharia Metabólica/métodos
3.
Drug Alcohol Rev ; 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38501257

RESUMO

ISSUES: Self-change from alcohol and drug use problems is increasingly acknowledged in research. Despite the growing number of published studies, the most recent broad review of this dispersed field dates back to 2010. The present review narratively synthesises key findings from empirical studies and critically identifies research gaps and directions for further research. APPROACH: Following the PRISMA guidelines for scoping reviews, a systematic search was conducted in multiple scientific databases, resulting in the identification of 56 relevant articles with explicit empirical results on self-change. KEY FINDINGS: The scoping review presents findings related to: (i) methods and definitions used; (ii) the prevalence of self-change; (iii) indicators of self-change; (iv) the process of self-change; and (v) population views on self-change. CONCLUSION: The review highlights the significant growth in research on self-change considering key themes as well as the need for a relational and time-bound approach to self-change in research and practice.

4.
Commun Biol ; 7(1): 286, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38454140

RESUMO

Through its involvement in gene transcription and heterochromatin formation, DNA methylation regulates how cells interact with their environment. Nevertheless, the extracellular signaling cues that modulate the distribution of this central chromatin modification are largely unclear. DNA methylation is highly abundant at repetitive elements, but its investigation in live cells has been complicated by methodological challenges. Utilizing a CRISPR/dCas9 biosensor that reads DNA methylation of human α-satellite repeats in live cells, we here uncover a signaling pathway linking the chromatin and transcriptional state of repetitive elements to epithelial adherens junction integrity. Specifically, we find that in confluent breast epithelial cell monolayers, α-satellite repeat methylation is reduced by comparison to low density cultures. This is coupled with increased transcriptional activity at repeats. Through comprehensive perturbation experiments, we identify the junctional protein E-cadherin, which links to the actin cytoskeleton, as a central molecular player for signal relay into the nucleus. Furthermore, we find that this pathway is impaired in cancer cells that lack E-cadherin and are not contact-inhibited. This suggests that the molecular connection between cell density and repetitive element methylation could play a role in the maintenance of epithelial tissue homeostasis.


Assuntos
Junções Aderentes , Metilação de DNA , Humanos , Junções Aderentes/genética , Junções Aderentes/metabolismo , Caderinas/genética , Caderinas/metabolismo , Transdução de Sinais , Cromatina/metabolismo
5.
ArXiv ; 2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38344226

RESUMO

The inference of multicellular self-assembly is the central quest of understanding morphogenesis, including embryos, organoids, tumors, and many others. However, it has been tremendously difficult to identify structural features that can indicate multicellular dynamics. Here we propose to harness the predictive power of graph-based deep neural networks (GNN) to discover important graph features that can predict dynamics. To demonstrate, we apply a physically informed GNN (piGNN) to predict the motility of multi-cellular collectives from a snapshot of their positions both in experiments and simulations. We demonstrate that piGNN is capable of navigating through complex graph features of multicellular living systems, which otherwise can not be achieved by classical mechanistic models. With increasing amounts of multicellular data, we propose that collaborative efforts can be made to create a multicellular data bank (MDB) from which it is possible to construct a large multicellular graph model (LMGM) for general-purposed predictions of multicellular organization.

6.
Chembiochem ; 25(2): e202300608, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-37987374

RESUMO

Glutamylation yields N-functionalized amino acids in several natural pathways. γ-Glutamylated amino acids may exhibit improved properties for their industrial application, e. g., as taste enhancers or in peptide drugs. γ-Glutamyl-isopropylamide (GIPA) can be synthesized from isopropylamine (IPA) and l-glutamate. In Pseudomonas sp. strain KIE171, GIPA is an intermediate in the biosynthesis of l-alaninol (2-amino-1-propanol), a precursor of the fluorochinolone antibiotic levofloxacin and of the chloroacetanilide herbicide metolachlor. In this study, fermentative production of GIPA with metabolically engineered Pseudomonas putida KT2440 using γ-glutamylmethylamide synthetase (GMAS) from Methylorubrum extorquens was established. Upon addition of IPA during growth with glycerol as carbon source in shake flasks, the recombinant strain produced up to 21.8 mM GIPA. In fed-batch bioreactor cultivations, GIPA accumulated to a titer of 11 g L-1 with a product yield of 0.11 g g-1 glycerol and a volumetric productivity of 0.24 g L-1 h-1 . To the best of our knowledge, this is the first fermentative production of GIPA.


Assuntos
Glicerol , Engenharia Metabólica , Propilaminas , Fermentação , Glicerol/metabolismo , Ácido Glutâmico/metabolismo
7.
Eur J Med Chem ; 264: 116023, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38071794

RESUMO

Nitrobenzothiazinones (BTZs) are potent active substances against Mycobacterium tuberculosis with currently two investigational drugs in clinical development for the treatment of tuberculosis. BTZs are the first examples for which a metabolic pathway towards transient hydride Meisenheimer complexes (HMC) has been shown in mammals, including humans. In this study, lead optimization efforts on BTZs are guided by the systematic evaluation of the HMC formation propensity combined with multiparameter assessment. For this purpose, a novel cell-based assay was specifically developed and fully implemented, and a library of 5- and 7-substituted BTZs was prepared to study substituent effects on the HMC formation. The multiparameter optimization revealed 5-methylated BTZs as the most preferred scaffolds, demonstrating a reduced HMC formation propensity combined with potent activity and good microsomal stability in vitro. In vivo experiments showed good systemic exposure upon oral administration and efficacy in a murine M. tuberculosis infection model. This study reports a qualified in vitro HMC assay, which not only enabled the selection of next-generation BTZs with improved pharmacokinetic properties but also allowed forecasting their in vivo metabolism.


Assuntos
Mycobacterium tuberculosis , Tuberculose , Humanos , Animais , Camundongos , Antituberculosos/farmacologia , Antituberculosos/uso terapêutico , Tuberculose/tratamento farmacológico , Biotransformação , Testes de Sensibilidade Microbiana , Mamíferos
8.
J Acoust Soc Am ; 154(4): 2579-2593, 2023 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-37874222

RESUMO

Passive acoustic monitoring is widely used for detection and localization of marine mammals. Typically, pressure sensors are used, although several studies utilized acoustic vector sensors (AVSs), that measure acoustic pressure and particle velocity and can estimate azimuths to acoustic sources. The AVSs can localize sources using a reduced number of sensors and do not require precise time synchronization between sensors. However, when multiple animals are calling concurrently, automated tracking of individual sources still poses a challenge, and manual methods are typically employed to link together sequences of measurements from a given source. This paper extends the method previously reported by Tenorio-Hallé, Thode, Lammers, Conrad, and Kim [J. Acoust. Soc. Am. 151(1), 126-137 (2022)] by employing and comparing two fully-automated approaches for azimuthal tracking based on the AVS data. One approach is based on random finite set statistics and the other on message passing algorithms, but both approaches utilize the underlying Bayesian statistical framework. The proposed methods are tested on several days of AVS data obtained off the coast of Maui and results show that both approaches successfully and efficiently track multiple singing humpback whales. The proposed methods thus made it possible to develop a fully-automated AVS tracking approach applicable to all species of baleen whales.


Assuntos
Jubarte , Animais , Teorema de Bayes , Acústica , Algoritmos , Cetáceos
9.
J Acoust Soc Am ; 153(5): 2690, 2023 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-37129673

RESUMO

Localization and tracking of marine animals can reveal key insights into their behaviors underwater that would otherwise remain unexplored. A promising nonintrusive approach to obtaining location information of marine animals is to process their bioacoustic signals, which are passively recorded using multiple hydrophones. In this paper, a data processing chain that automatically detects and tracks multiple odontocetes (toothed whales) in three dimensions (3-D) from their echolocation clicks recorded with volumetric hydrophone arrays is proposed. First, the time-difference-of-arrival (TDOA) measurements are extracted with a generalized cross-correlation that whitens the received acoustic signals based on the instrument noise statistics. Subsequently, odontocetes are tracked in the TDOA domain using a graph-based multi-target tracking (MTT) method to reject false TDOA measurements and close gaps of missed detections. The resulting TDOA estimates are then used by another graph-based MTT stage that estimates odontocete tracks in 3-D. The tracking capability of the proposed data processing chain is demonstrated on real acoustic data provided by two volumetric hydrophone arrays that recorded echolocation clicks from Cuvier's beaked whales (Ziphius cavirostris). Simulation results show that the presented MTT method using 3-D can outperform an existing approach that relies on manual annotation.


Assuntos
Ecolocação , Animais , Vocalização Animal , Teorema de Bayes , Espectrografia do Som , Baleias
10.
J Acoust Soc Am ; 153(1): 723, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36732218

RESUMO

This paper presents a Bayesian estimation method for sequential direction finding. The proposed method estimates the number of directions of arrivals (DOAs) and their DOAs performing operations on the factor graph. The graph represents a statistical model for sequential beamforming. At each time step, belief propagation predicts the number of DOAs and their DOAs using posterior probability density functions (pdfs) from the previous time and a different Bernoulli-von Mises state transition model. Variational Bayesian inference then updates the number of DOAs and their DOAs. The method promotes sparse solutions through a Bernoulli-Gaussian amplitude model, is gridless, and provides marginal posterior pdfs from which DOA estimates and their uncertainties can be extracted. Compared to nonsequential approaches, the method can reduce DOA estimation errors in scenarios involving multiple time steps and time-varying DOAs. Simulation results demonstrate performance improvements compared to state-of-the-art methods. The proposed method is evaluated using ocean acoustic experimental data.

11.
ACS Synth Biol ; 12(3): 820-831, 2023 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-36821819

RESUMO

Astaxanthin is a valuable ketocarotenoid with various pharmaceutical and nutraceutical applications. Green microalgae harbor natural capacities for pigment accumulation due to their 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway. Recently, a redesigned ß-carotene ketolase (BKT) was found to enable ketocarotenoid accumulation in the model microalga Chlamydomonas reinhardtii, and transformants exhibited reduced photoinhibition under high-light. Here, a systematic screening by synthetic transgene design of carotenoid pathway enzymes and overexpression from the nuclear genome identified phytoene synthase (PSY/crtB) as a bottleneck for carotenoid accumulation in C. reinhardtii. Increased ß-carotene hydroxylase (CHYB) activity was found to be essential for engineered astaxanthin accumulation. A combined BKT, crtB, and CHYB expression strategy resulted in a volumetric astaxanthin production of 9.5 ± 0.3 mg L-1 (4.5 ± 0.1 mg g-1 CDW) in mixotrophic and 23.5 mg L-1 (1.09 mg L-1 h-1) in high cell density conditions, a 4-fold increase compared to previous reports in C. reinhardtii. This work presents a systematic investigation of bottlenecks in astaxanthin accumulation in C. reinhardtii and the phototrophic green cell factory design for competitive use in industrial biotechnology.


Assuntos
Chlamydomonas reinhardtii , Microalgas , Engenharia Metabólica/métodos , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/metabolismo , Microalgas/genética , Microalgas/metabolismo , Oxigenases/genética , Oxigenases/metabolismo , Carotenoides/metabolismo
12.
Molecules ; 28(4)2023 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-36838984

RESUMO

Circular economy holds great potential to minimize the use of finite resources, and reduce waste formation by the creation of closed-loop systems. This also pertains to the utilization of sidestreams in large-scale biotechnological processes. A flexible feedstock concept has been established for the industrially relevant Corynebacterium glutamicum, which naturally synthesizes the yellow C50 carotenoid decaprenoxanthin. In this study, we aimed to use a preprocessed aquaculture sidestream for production of carotenoids, including the fish feed ingredient astaxanthin by C. glutamicum. The addition of a preprocessed aquaculture sidestream to the culture medium did not inhibit growth, obviated the need for addition of several components of the mineral salt's medium, and notably enhanced production of astaxanthin by an engineered C. glutamicum producer strain. Improved astaxanthin production was scaled to 2 L bioreactor fermentations. This strategy to improve astaxanthin production was shown to be transferable to production of several native and non-native carotenoids. Thus, this study provides a proof-of-principle for improving carotenoid production by C. glutamicum upon supplementation of a preprocessed aquaculture sidestream. Moreover, in the case of astaxanthin production it may be a potential component of a circular economy in aquaculture.


Assuntos
Corynebacterium glutamicum , Animais , Corynebacterium glutamicum/genética , Engenharia Metabólica , Carotenoides , Aquicultura
13.
Traffic ; 24(4): 162-176, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36562184

RESUMO

The control of intracellular membrane trafficking by Rho GTPases is central to cellular homeostasis. How specific guanine nucleotide exchange factors and GTPase-activating proteins locally balance GTPase activation in this process is nevertheless largely unclear. By performing a microscopy-based RNAi screen, we here identify the RhoGEF protein Solo as a functional counterplayer of DLC3, a RhoGAP protein with established roles in membrane trafficking. Biochemical, imaging and optogenetics assays further uncover Solo as a novel regulator of endosomal RhoB. Remarkably, we find that Solo and DLC3 control not only the activity, but also total protein levels of RhoB in an antagonistic manner. Together, the results of our study uncover the first functionally connected RhoGAP-RhoGEF pair at endomembranes, placing Solo and DLC3 at the core of endocytic trafficking.


Assuntos
Proteínas rho de Ligação ao GTP , Proteína rhoB de Ligação ao GTP , Fatores de Troca de Nucleotídeo Guanina Rho/genética , Fatores de Troca de Nucleotídeo Guanina Rho/metabolismo , Proteína rhoB de Ligação ao GTP/metabolismo , Proteínas rho de Ligação ao GTP/metabolismo , Complexo de Golgi/metabolismo , Endossomos/metabolismo
14.
Eng Life Sci ; 22(12): 811-817, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36514532

RESUMO

Cyclic lipopeptides are substances with a high potential to act as antimicrobial agents. Jagaricin, produced by Janthinobacterium agaricidamnosum DSM 9628 and discovered in 2012, is a new member of this class with promising antifungal properties. However, further experiments to investigate future applications and/or conduct chemical derivatization to change properties and toxicity are impossible due to the limited access to jagaricin. Besides a high jagaricin concentration at the end of the fermentation process, a suitable downstream process is essential to generate appropriate amounts with the desired purity. In contrast to other amphiphilic molecules, jagaricin cannot be separated by foam fractionation since it is mainly attached to the surface of the microbial biomass. This technical report presents an overall process chain consisting of 11 individual steps to generate jagaricin in gram scale with a purity of over 95%.

15.
Front Psychiatry ; 13: 1022490, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36590630

RESUMO

Introduction: De-institutionalization of psychiatric care has greatly increased the role of family members in the recovery pathways of Persons labeled as Not Criminally Responsible (PNCR). However, the role of family members in supporting PNCR in forensic psychiatric care remains understudied. Scarce evidence indicates that PNCR have to deal with stigma and endure specific burdens (i.e., symptom-specific, financial, social, and emotional). Recovery-focused research showed that recovery in both persons with a severe mental illness and family members develop in parallel with each other and are characterized by similar helpful principles (e.g., hope and coping skills). As such, the recovery pathways of PNCR often goes hand in hand with the recovery pathway of their family members. During the family recovery process, family members often experience not being listened to or being empowered by professionals or not being involved in the decision-making process in the care trajectory of their relative. Therefore, the aim of this study is to capture how family members experience the care trajectories of their relatives, more specifically by looking at family recovery aspects and personal advocacy of family members. Methods: Semi-structured interviews were conducted with 21 family members of PNCR from 14 families. A thematic analysis confirms that family members suffer from stigma and worry significantly about the future of their relative. Results: Regarding the care trajectory of PNCR, family members experienced barriers in multiple domains while trying to support their relative: involvement in care and information sharing, visiting procedures, transitions between wards, and the psychiatric and judicial reporting by professionals. In addition, family members emphasized the importance of (social) support for themselves during the forensic psychiatric care trajectories and of a shared partnership. Discussion: These findings tie in with procedural justice theory as a precondition for family support and family recovery within forensic psychiatric care.

16.
J Acoust Soc Am ; 150(2): 1057, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34470313

RESUMO

Localizing and tracking an underwater acoustic source is a key task for maritime situational awareness. This paper presents a sequential Bayesian estimation method for passive acoustic source localization in shallow water. The proposed probabilistic focalization approach associates detected directions of arrival (DOAs) to modeled DOAs and jointly estimates the time-varying source location. Embedded ray tracing makes it possible to incorporate environmental parameters that characterize the acoustic waveguide. Due to its statistical model, the proposed method can provide robustness in scenarios with severe environmental uncertainty. We demonstrate performance advantages compared to matched field processing using data collected during the SWellEx-96 experiment.

17.
J Biotechnol ; 336: 1-9, 2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34118330

RESUMO

In today's, society multi-resistant pathogens have become an emerging threat, which makes the search for novel anti-infectives more urgent than ever. A promising class of substances are cyclic lipopeptides like the antifungal jagaricin. Jagaricin is formed by the bacterial mushroom pathogen Janthinobacterium agaricidamnosum. It has shown antifungal activity against human pathogenic fungi like Candida albicans and Aspergillus fumigatus. In addition, jagaricin is nearly non-toxic for plants, which makes it a promising agent for agricultural applications. Cyclic lipopeptides formed by microorganisms originate from their secondary metabolism. This makes it very challenging to determine the inducing factor for product formation, especially for unknown microbial systems like J. agaricidamnosum. In the presented study, a biotechnological process for jagaricin formation was developed, investigating impact factors like the medium, oxygen availability, and phosphate. For this reason, experiments were conducted on microtiter plate, shake flask, and stirred tank bioreactor level. Ultimately, a final maximum jagaricin concentration of 251 mg L-1 (15.5 mgJagaricin∙gCDW-1) could be achieved, which is an increase of approximately 458 % in comparison to previous results in standard glucose medium. This concentration allows the production of significantly higher amounts of jagaricin and enables further experiments to investigate the potential of this substance.


Assuntos
Antifúngicos , Peptídeos Cíclicos , Antifúngicos/farmacologia , Candida albicans , Lipopeptídeos , Testes de Sensibilidade Microbiana , Oxalobacteraceae , Peptídeos Cíclicos/biossíntese
18.
J Acoust Soc Am ; 149(3): 2089, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33810770

RESUMO

This paper presents methods for the estimation of the time-varying directions of arrival (DOAs) of signals emitted by moving sources. Following the sparse Bayesian learning (SBL) framework, prior information of unknown source amplitudes is modeled as a multi-variate Gaussian distribution with zero-mean and time-varying variance parameters. For sequential estimation of the unknown variance, we present two sequential SBL-based methods that propagate statistical information across time to improve DOA estimation performance. The first method heuristically calculates the parameters of an inverse-gamma hyperprior based on the source signal estimate from the previous time step. In addition, a second sequential SBL method is proposed, which performs a prediction step to calculate the prior distribution of the current variance parameter from the variance parameter estimated at the previous time step. The SBL-based sequential processing provides high-resolution DOA tracking capabilities. Performance improvements are demonstrated by using simulated data as well as real data from the SWellEx-96 experiment.

19.
Med Mycol ; 59(5): 505-509, 2021 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-33336238

RESUMO

Activation of mucosal-associated invariant T cells (MAIT cells) by certain bacteria, viruses, and yeast is well studied, but the activation potential of filamentous moulds from the order Mucorales is not known. Here, we show a rapid response of human MAIT cells against the Mucorales species Mucor circinelloides, Rhizopus arrhizus, and Rhizopus microsporus. This activation included upregulation of CD69 and degranulation marked by increased CD107a expression, while intracellular perforin and granzyme A expression were reduced. Furthermore, blocking of the antigen-presenting molecule major histocompatibility complex class I-related abrogated MAIT cell activation demonstrating a T cell receptor-dependent stimulation by Mucorales.


Assuntos
Antígenos de Histocompatibilidade Classe I/metabolismo , Antígenos de Histocompatibilidade Menor/metabolismo , Mucorales/imunologia , Mucormicose/imunologia , Mucormicose/metabolismo , Células T Invariantes Associadas à Mucosa/imunologia , Células T Invariantes Associadas à Mucosa/metabolismo , Riboflavina/metabolismo , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/metabolismo , Granzimas/metabolismo , Interações entre Hospedeiro e Microrganismos , Humanos , Lectinas Tipo C/metabolismo , Ativação Linfocitária , Proteína 1 de Membrana Associada ao Lisossomo/metabolismo , Mucor/imunologia , Mucormicose/microbiologia , Perforina/metabolismo , Rhizopus/imunologia , Rhizopus oryzae/imunologia , Regulação para Cima
20.
Rev Sci Instrum ; 91(10): 105110, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33138574

RESUMO

To investigate the fundamentals of liquid oxygen droplet combustion in hydrogen under microgravity conditions, a drop tower apparatus has been developed. In a cryogenic combustion chamber cooled with liquid nitrogen, single oxygen droplets with a diameter of 1 mm are suspended at the tip of a thin suspender. Ignition is accomplished after microgravity conditions are reached by a near-infrared laser, which generates a plasma spark positioned in the immediate vicinity of the oxygen droplet. The subsequent combustion is investigated with various optical diagnostics. Shadowgraph imaging is used to determine the initial droplet size and the droplet diameter regression with high temporal resolution. In addition, the position and diameter of the flame are determined by OH chemiluminescence imaging. The oxygen/hydrogen combustion at two different pressure levels is reported. At a pressure of 0.1 MPa, irregular structures appear to form on the droplet surface during the combustion process, which lasts 137 ms before the droplet is completely consumed. The formation of these irregular structures is consistent with the condensation and freezing of water vapor in the cold-temperature region near the droplet surface. At a higher pressure of 4 MPa (reduced pressure pr,O2 =0.79), the water ice formation is significantly reduced due to the shorter burning time of 66 ms and the closer proximity of the flame to the droplet surface. The measured burning constant is k0.1 = 5.5 mm2/s at 0.1 MPa and k4 = 7.1 mm2/s at 4 MPa, respectively. This increase with increasing pressure is consistent with the smaller flame standoff distance.

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