RESUMO
PURPOSE: A deep learning artificial intelligence (AI) algorithm has been demonstrated to outperform embryologists in identifying euploid embryos destined to implant with an accuracy of 75.3% (1). Our aim was to evaluate the performance of highly trained embryologists in selecting top quality day 5 euploid blastocysts with and without the aid of a deep learning algorithm. MATERIALS AND METHODS: A non-overlapping series of 200 sets of day 5 euploid embryo images with known implantation outcomes was distributed to 17 highly trained embryologists. One embryo in each set was known to have implanted and one failed implantation. They were asked to select which embryo to transfer from each set. The same 200 sets of embryos, with indication of which embryo in each set had been identified by the algorithm as more likely to implant was then distributed. Chi-squared, t-test, and receiver operating curves were performed to compare the embryologist performeance with and without AI. RESULTS: Fourteen embryologists completed both assessments. Embryologists provided with AI results selected successfully implanted embryos in 73.6% of cases compared to 65.5% for those selected using visual assessments alone (p < 0.001). All embryologists improved in their ability to select embryos with the aid of the AI algorithm with a mean percent improvement of 11.1% (range 1.4% to 15.5%). There were no differences in degree of improvement by embryologist level of experience (junior, intermediate, senior). CONCLUSIONS: The incorporation of an AI framework for blastocyst selection enhanced the performance of trained embryologists in identifying PGT-A euploid embryos destined to implant.
Assuntos
Algoritmos , Inteligência Artificial , Blastocisto/classificação , Blastocisto/citologia , Técnicas de Apoio para a Decisão , Implantação do Embrião , Fertilização in vitro/métodos , Adulto , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Gravidez , Taxa de Gravidez , Estudos RetrospectivosRESUMO
This proceedings report presents the outcomes from an international Expert Meeting to establish a consensus on the recommended technical and operational requirements for air quality within modern assisted reproduction technology (ART) laboratories. Topics considered included design and construction of the facility, as well as its heating, ventilation and air conditioning system; control of particulates, micro-organisms (bacteria, fungi and viruses) and volatile organic compounds (VOCs) within critical areas; safe cleaning practices; operational practices to optimize air quality while minimizing physicochemical risks to gametes and embryos (temperature control versus air flow); and appropriate infection-control practices that minimize exposure to VOC. More than 50 consensus points were established under the general headings of assessing site suitability, basic design criteria for new construction, and laboratory commissioning and ongoing VOC management. These consensus points should be considered as aspirational benchmarks for existing ART laboratories, and as guidelines for the construction of new ART laboratories.
Assuntos
Poluição do Ar , Laboratórios/normas , Técnicas de Reprodução Assistida/normas , Poluição do Ar em Ambientes Fechados , Consenso , Monitoramento Ambiental , HumanosRESUMO
This is a selective review that provides the context for the study of perinatal affective disorder mechanisms and outlines directions for future research. We integrate existing literature along neural networks of interest for affective disorders and maternal caregiving: (i) the salience/fear network; (ii) the executive network; (iii) the reward/social attachment network; and (iv) the default mode network. Extant salience/fear network research reveals disparate responses and corticolimbic coupling to various stimuli based upon a predominantly depressive versus anxious (post-traumatic stress disorder) clinical phenotype. Executive network and default mode connectivity abnormalities have been described in postpartum depression (PPD), although studies are very limited in these domains. Reward/social attachment studies confirm a robust ventral striatal response to infant stimuli, including cry and happy infant faces, which is diminished in depressed, insecurely attached and substance-using mothers. The adverse parenting experiences received and the attachment insecurity of current mothers are factors that are associated with a diminution in infant stimulus-related neural activity similar to that in PPD, and raise the need for additional studies that integrate mood and attachment concepts in larger study samples. Several studies examining functional connectivity in resting state and emotional activation functional magnetic resonance imaging paradigms have revealed attenuated corticolimbic connectivity, which remains an important outcome that requires dissection with increasing precision to better define neural treatment targets. Methodological progress is expected in the coming years in terms of refining clinical phenotypes of interest and experimental paradigms, as well as enlarging samples to facilitate the examination of multiple constructs. Functional imaging promises to determine neural mechanisms underlying maternal psychopathology and impaired caregiving, such that earlier and more precise detection of abnormalities will be possible. Ultimately, the discovery of such mechanisms will promote the refinement of treatment approaches toward maternal affective disturbance, parenting behaviours and the augmentation of parenting resiliency.
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Cuidadores , Depressão Pós-Parto , Mães , Feminino , Humanos , Imageamento por Ressonância Magnética , Fenótipo , GravidezRESUMO
Brain networks that govern parental response to infant signals have been studied with imaging techniques over the last 15 years. The complex interaction of thoughts and behaviors required for sensitive parenting enables the formation of each individual's first social bonds and critically shapes development. This review concentrates on magnetic resonance imaging experiments which directly examine the brain systems involved in parental responses to infant cues. First, we introduce themes in the literature on parental brain circuits studied to date. Next, we present a thorough chronological review of state-of-the-art fMRI studies that probe the parental brain with a range of baby audio and visual stimuli. We also highlight the putative role of oxytocin and effects of psychopathology, as well as the most recent work on the paternal brain. Taken together, a new model emerges in which we propose that cortico-limbic networks interact to support parental brain responses to infants. These include circuitry for arousal/salience/motivation/reward, reflexive/instrumental caring, emotion response/regulation and integrative/complex cognitive processing. Maternal sensitivity and the quality of caregiving behavior are likely determined by the responsiveness of these circuits during early parent-infant experiences. The function of these circuits is modifiable by current and early-life experiences, hormonal and other factors. Severe deviation from the range of normal function in these systems is particularly associated with (maternal) mental illnesses - commonly, depression and anxiety, but also schizophrenia and bipolar disorder. Finally, we discuss the limits and extent to which brain imaging may broaden our understanding of the parental brain given our current model. Developments in the understanding of the parental brain may have profound implications for long-term outcomes in families across risk, resilience and possible interventions. This article is part of a Special Issue entitled Oxytocin and Social Behav.
Assuntos
Encéfalo/fisiologia , Relações Pai-Filho , Relações Mãe-Filho , Ocitocina/metabolismo , Feminino , Humanos , MasculinoRESUMO
With a secure foundation in basic research across mammalian species in which fathers participate in the raising of young, novel brain-imaging approaches are outlining a set of consistent brain circuits that regulate paternal thoughts and behaviors in humans. The newest experimental paradigms include increasingly realistic baby-stimuli to provoke paternal cognitions and behaviors with coordinated hormone measures to outline brain networks that regulate motivation, reflexive caring, emotion regulation, and social brain networks with differences and similarities to those found in mothers. In this article, on the father brain, we review all brain-imaging studies on PubMed to date on the human father brain and introduce the topic with a selection of theoretical models and foundational neurohormonal research on animal models in support of the human work. We discuss potentially translatable models for the identification and treatment of paternal mood and father-child relational problems, which could improve infant mental health and developmental trajectories with potentially broad public health importance.
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Encéfalo/fisiologia , Pai/psicologia , Saúde Mental , Modelos Animais , Animais , Emoções , Relações Pai-Filho , Feminino , Humanos , Masculino , Neuroimagem , Apoio SocialRESUMO
In Vitro Fertilization (IVF) laboratories often carry a penchant to resist change while in the pursuit of maintaining consistency in laboratory conditions. However, implementation of new technology is often critical to expand scientific discoveries and to improve upon prior successes to advance the field. Microfluidic platforms represent a technology that has the potential to revolutionize the fundamental processes of IVF. While the focus of microfluidic application in IVF has centered on embryo culture, the innovative platforms carry tremendous potential to improve other procedural steps and represents a possible paradigm shift in how we handle gametes and embryos. The following review will highlight application of various microfluidic platforms in IVF for use in maturation, manipulation, culture, cryopreservation and non-invasive quality assessment; pointing out new insights gained into functions of sperm, oocytes and embryos. Platform design and function will also be discussed, focusing on limitations, advancements and future refinements that can further aid in their clinical implementation.
Assuntos
Técnicas Analíticas Microfluídicas/métodos , Técnicas de Reprodução Assistida , Andrologia , Animais , Embriologia , HumanosRESUMO
BACKGROUND: Reducing environmental stress imposed upon gametes and embryos in the IVF laboratory is crucial in optimizing culture conditions and development. One environmental parameter of particular importance is external pH (pHe) of culture media. An optimal pHe has not been identified. METHODS: Electronic searches were performed using keywords focused on pH and the embryo using PUBMED through August 2011, with no limits placed on a beginning time. Examples of keywords include CO(2), bicarbonate and hydrogen ion. Relevant papers were then examined to obtain additional publications. RESULTS: Determining optimal pHe is problematic due to difficulty in isolating pHe from other variables, such as CO(2) and bicarbonate. Various commercial media companies recommend differing pHe ranges, most within the range of 7.2-7.4, with some companies recommending altering pHe based on the gamete or stage of the embryo. However, changing pHe during culture has not been experimentally shown to improve outcomes. Further complicating attempts to define an optimal pHe is that media components can impact intracellular pH (pHi). As a result, media with different concentrations of substances, such as lactate or amino acids, may have different pHi, despite being in the same pHe. CONCLUSIONS: Due to the plasticity of embryos, a range of pHe's can support development, and defining an optimal pHe is difficult. It is unclear whether there is any benefit in changing pHe at various steps during IVF. The ideal pHe will likely vary from media to media and, until comparative studies have been performed isolating pHe, adherence to manufacturer recommendations and maintenance of a small acceptable pHe range are advisable.
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Meios de Cultura/química , Fertilização in vitro , Concentração de Íons de Hidrogênio , Células Germinativas/fisiologia , HumanosRESUMO
Because media osmolality can impact embryo development, the effect of conditions during microdrop preparation on osmolality was examined. Various sizes of microdrops were prepared under different laboratory conditions. Drops were pipetted directly onto a dish and covered by oil (standard method) or pipetted on the dish, overlaid with oil before removing the underlying media and replaced with fresh media (wash-drop method). Drops were made at 23°C or on a heated stage (37°C) and with or without airflow. Osmolality was assessed at 5 min and 24h. The biological impact of osmolality change was demonstrated by culturing 1-cell mouse embryos in media with varying osmolality. Reduced drop volume, increased temperature and standard method were associated with a significant increase in osmolality at both 5 min and 24h (P-values <0.001, <0.0001 and <0.0001, respectively). There was a significant interaction between airflow, decreased volume, increased temperature and standard method that caused a significant increase in osmolality (40mOsm/kg) compared with controls (P<0.04). There was no significant change in osmolality over time. Mouse embryo development was significantly reduced in media with elevated osmolality (>310mOsm/kg; P<0.05). Procedures in the IVF laboratory can alter osmolality and impact embryo development.
Assuntos
Desenvolvimento Embrionário/fisiologia , Animais , Meios de Cultura , Desenvolvimento Embrionário/efeitos dos fármacos , Camundongos , Concentração Osmolar , TemperaturaRESUMO
This overview attempts to synthesise current understandings of the neuroendocrine basis of parenting. The parent-infant bond is central to the human condition, contributes to risks for mood and anxiety disorders, and provides the potential for resiliency and protection against the development of psychopathology. Animal models of parenting provide compelling evidence that biological mechanisms may be studied in humans. This has led to brain imaging and endocrine system studies of human parents using baby stimuli and concerted psychological and behavioural measures. Certain brain circuits and related hormonal systems, including subcortical regions for motivation (striatum, amygdala, hypothalamus and hippocampus) and cortical regions for social cognition (anterior cingulate, insula, medial frontal and orbitofrontal cortices), appear to be involved. These brain circuits work with a range of endocrine systems to manage stress and motivate appropriate parental caring behaviour with a flexibility appropriate to the environment. Work in this field promises to link evolving models of parental brain performance with resilience, risk and treatment toward mother-infant mental health.
Assuntos
Choro/fisiologia , Neuroendocrinologia , Pais/psicologia , Adulto , Humanos , Recém-NascidoRESUMO
BACKGROUND: The majority of research aimed at improving embryo development in vitro has focused on manipulation of the chemical environment, examining details such as energy substrate composition and impact of various growth factors or other supplements. In comparison, relatively little work has been done examining the physical requirements of preimplantation embryos and the role culture platforms or devices can play in influencing embryo development. METHODS: Electronic searches were performed using keywords centered on embryo culture techniques using PUBMED through June 2010 and references were searched for additional research articles. RESULTS: Various approaches to in vitro embryo culture that involve manipulations of the physical culture environment are emerging. Novel culture platforms being developed examine issues such as media volume and embryo spacing. Furthermore, methods to permit dynamic embryo culture with fluid flow and embryo movement are now available, and novel culture surfaces are being tested. CONCLUSIONS: Although several factors remain to be studied to optimize efficiency, manipulations of the embryo culture microenvironment through novel culture devices may offer a means to improve embryo development in vitro. Reduced volume systems that reduce embryo spacing, such as the well-of-the-well approach, appear beneficial, although more work is needed to verify the source of their true benefit in human embryos. Emerging microfluidic technology appears to be a promising approach. However, along with the work on specialized culture surfaces, more information is required to determine the impact on human embryo development.
Assuntos
Ectogênese , Técnicas de Cultura Embrionária , Animais , Técnicas de Cultura Embrionária/instrumentação , Humanos , Microfluídica/métodos , Propriedades de SuperfícieRESUMO
Microfluidics is a young but established field that holds significant potential for scientific discovery. The utility of microfluidics can improve our knowledge of basic biology as well as expand our understanding in specialized areas such as assisted reproduction and stem cell developmental biology. This review describes the technology of microfluidics and discusses applications within assisted reproduction technology and embryonic stem cell growth and directed differentiation. Development of an integrated microfluidic platform for assisted reproduction, which can manipulate gametes, embryos, embryonic stem cells, their culture environment, and incorporate biomarker analysis, could have a dramatic impact on the basic understanding of embryo/embryonic stem cell development, as well as provide significant improvements in current technologies used to treat infertility, preserve fertility, and derive therapeutic cells from stem cells.
Assuntos
Blastocisto , Células-Tronco Embrionárias , Microfluídica , Oócitos , Técnicas de Reprodução Assistida , Espermatozoides , Técnicas de Cultura de Células , Separação Celular/instrumentação , Separação Celular/métodos , Técnicas de Cultura Embrionária , Feminino , Fertilização in vitro/métodos , Humanos , Masculino , Microfluídica/instrumentação , Microfluídica/métodos , Nanotecnologia , Técnicas de Reprodução Assistida/tendências , Espermatozoides/citologiaRESUMO
The mammalian oocyte is notorious for high rates of chromosomal abnormalities. This results in subsequent embryonic aneuploidy, resulting in infertility and congenital defects. Therefore, understanding regulatory mechanisms involved in chromatin remodeling and chromosome segregation during oocyte meiotic maturation is imperative to fully understand the complex process and establish potential therapies. This review will focus on major events occurring during oocyte meiosis, critical to ensure proper cellular ploidy. Mechanistic and cellular events such as chromosome condensation, meiotic spindle formation, as well as cohesion of homologues and sister chromatids will be discussed, focusing on the role of reversible phosphorylation in control of these processes.
Assuntos
Montagem e Desmontagem da Cromatina , Segregação de Cromossomos , Mamíferos/fisiologia , Meiose/fisiologia , Oócitos/metabolismo , Animais , Feminino , Humanos , Oócitos/ultraestrutura , FosforilaçãoRESUMO
The importance of oocyte quality cannot be overstated, because it impacts all subsequent events during development of the embryo, the fetus and even the resulting offspring. Oocyte metabolism plays a critical role in supporting developmental competence via multiple mechanisms. It is beginning to be understood that metabolic pathways not only affect cytoplasmic maturation but may control nuclear maturation as well. A complete understanding of the precise roles that metabolism plays in determining oocyte quality is crucial for developing efficient in vitro maturation systems to support acquisition of oocyte competence. To date, this pursuit has not been entirely successful. Work in our laboratory on porcine oocyte metabolism has elucidated some of the intricate control mechanisms at work within the oocyte, not only for energy production, but also encompassing progression of nuclear maturation, mitochondrial activity and distribution, and oxidative and ionic stresses. We hypothesize that by utilizing oocyte metabolic data, we can develop more appropriate in vitro maturation systems that result in increased oocyte and embryo developmental competence.
Assuntos
Oócitos/fisiologia , Animais , Bovinos , Técnicas de Cultura de Células , Meios de Cultura , Metabolismo Energético , Meiose , Camundongos , Mitocôndrias/metabolismo , Oócitos/citologia , Oócitos/metabolismo , Especificidade da Espécie , SuínosRESUMO
Parental caregiving includes a set of highly conserved behaviors and mental states that may reflect both an individual's genetic endowment and the early experience of being cared for as a child. This review first examines the mental and behavioral elements of early parental caregiving in humans. Second, we consider what is known about the neurobiological substrates of maternal behaviors in mammalian species including some limited human data. Third, we briefly review the evidence that specific genes encode proteins that are crucial for the development of the neural substrates that underlie specific features of maternal behavior. Fourth, we review the emerging literature on the "programming" role of the intrauterine environment and postnatal caregiving environment in shaping subsequent maternal behavior. We conclude that there are critical developmental windows during which the genetically determined microcircuitry of key limbic-hypothalamic-midbrain structures are susceptible to early environmental influences and that these influences powerfully shape an individual's responsivity to psychosocial stressors and their resiliency or vulnerability to various forms of human psychopathology later in life.
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Meio Ambiente , Comportamento Materno/fisiologia , Rede Nervosa/fisiologia , Relações Pais-Filho , Desenvolvimento Humano/fisiologia , HumanosRESUMO
Glutathione (GSH) content in mature porcine oocytes is correlated with subsequent fertilization and developmental success. Adenosine triphosphate (ATP) is an important energy source for maintaining cellular activities and protein synthesis. The objective of this study was to compare GSH and ATP concentrations of in vivo and in vitro matured porcine oocytes. Ovulated, in vivo matured oocytes were frozen at -80 degrees C in groups of 10-20 (GSH) or 5-10 (ATP). In vitro oocytes were matured in either tissue culture medium-199 (TCM199) supplemented with polyvinyl alcohol (PVA) or hyaluronic acid (MAP5), or North Carolina State University-23 (NCSU23) supplemented with porcine follicular fluid (pFF) and frozen as described, or fertilized and cultured. GSH content was determined by the dithionitrobenzoic acid-glutathione disulfide (DTNB-GSSG) reductase recycling assay. ATP content was determined by using the Bioluminescent Somatic Cell Assay Kit. Oocytes matured in vitro in defined TCM199 with PVA or hyaluronic acid, or NCSU23 with pFF had significantly lower concentrations (P < 0.05) of GSH (n = 207, 9.82 +/- 0.71 pmol/oocyte; n = 104, 9.73 +/- 0.81 pmol/oocyte; n = 108, 7.89 +/- 0.66 pmol/oocyte, respectively) compared to in vivo matured oocytes (n = 217, 36.26 +/- 11.00 pmol/oocyte). Concentrations of ATP were not different between treatments (in vivo, n = 70, 0.97 +/- 0.07 pmol/oocyte; TCM-PVA, n = 117, 0.81 +/- 0.13 pmol/oocyte; TCM-MAP, n = 107, 1.02 +/- 0.18 pmol/oocyte; NCSU-pFF, n = 134, 0.71 +/- 0.08 pmol/oocyte). Intracellular ATP content does not appear to be related to developmental potential in porcine oocytes. Low intracellular GSH may be responsible, in part, for lower developmental competence observed in in vitro matured porcine oocytes.
Assuntos
Trifosfato de Adenosina/metabolismo , Glutationa/metabolismo , Oócitos/metabolismo , Suínos/metabolismo , Animais , Feminino , Técnicas In VitroRESUMO
The aim of in vitro embryo systems is to produce embryos of comparable quality to those derived in vivo. Comparison of embryo metabolism as an indicator of viability may be useful in optimization of culture conditions. The aim of the present study was to determine glucose, glutamine and pyruvate use by various stage pig embryos produced in vitro and in vivo. The results indicate that pig embryos use glucose via glycolysis in significant amounts at all stages examined, regardless of embryo origin. In vitro-derived embryos have significantly increased glycolytic activity after the eight-cell stage, whereas in vivo-derived embryos have increased glycolysis at the blastocyst stage. In vivo-derived embryos have higher rates of glycolysis compared with in vitro-derived embryos. Glucose usage through the Krebs cycle for in vitro- and in vivo-derived embryos increased significantly at the blastocyst stage. Pig embryos produced in vitro used constant amounts of glutamine throughout development, whereas in vivo-derived embryos increased glutamine usage after the eight-cell stage. Pyruvate use was minimal at all stages examined for both in vitro- and in vivo-derived pig embryos, showing significant increases at the blastocyst stage. Krebs cycle metabolism of pyruvate, glutamine and glucose by in vivo-derived embryos was higher than that by in vitro-derived embryos. Current in vitro culture conditions produce pig embryos with altered metabolic activity, which may compromise embryo viability.
Assuntos
Blastocisto/metabolismo , Ciclo do Ácido Cítrico , Fertilização in vitro , Glucose/metabolismo , Suínos/metabolismo , Análise de Variância , Animais , Sobrevivência Celular , Células Cultivadas , Feminino , Idade Gestacional , Glutamina/metabolismo , Gravidez , Ácido Pirúvico/metabolismo , Suínos/embriologiaRESUMO
Porcine embryo development in vitro is relatively inefficient compared to other domestic species. Currently, a single culture medium (NCSU23) is the standard for porcine in vitro systems. However, the G1.2/G2.2 sequential culture system has been beneficial for embryo development in other species. The objective of this study was to compare porcine preimplantation embryo development in vitro and subsequent blastocyst viability and metabolic activity using NCSU23 and G1.2/G2.2 culture media. Oocytes were matured in defined TCM199 base medium for 45 to 47 h and fertilized in mTBM for 4 h. Embryos were cultured in either NCSU23 for 146 h or G1.2 medium for 72 h followed by culture in G2.2 medium for an additional 74 h. Blastocyst substrate use was measured using a modification of the hanging drop technique. Culture in NCSU23 resulted in a higher percentage (P < 0.05) of embryo cleavage (74.0%) and blastocyst development (14.6%) than culture in G1.2/G2.2 (67.8% and 7.8%, respectively). Both NCSU23 and G1.2/G2.2 produced blastocysts with similar mean cell numbers (51.5 +/- 4.3 and 47.1 +/- 4.3, respectively), similar glucose use (10.81 +/- 1.39 and 10.12 +/- 1.72 pmol/embryo/3 h, respectively) and pyruvate use (1.08 +/- 0.056 and 0.88 +/- 0.048 pmol/embryo/3 h, respectively). These data indicate that a sequential culture system can support porcine embryo development in vitro without compromising embryo viability. However, the G1.2/G2.2 system was not as effective as NCSU23 in supporting blastocyst development. Sequential media should be formulated specifically for porcine embryos to improve embryonic cleavage and blastocyst development.
Assuntos
Blastocisto/fisiologia , Fertilização in vitro/veterinária , Suínos/embriologia , Animais , Blastocisto/metabolismo , Meios de Cultura/farmacologia , Feminino , Fertilização in vitro/métodos , Glucose/metabolismo , Masculino , Oócitos/metabolismo , Oócitos/fisiologia , Gravidez , Ácido Pirúvico/metabolismo , Distribuição Aleatória , Estatísticas não Paramétricas , Suínos/metabolismoRESUMO
We examined the role of phosphatases in synaptic transmission using the permeant phosphatase inhibitor okadaic acid (OA). In the crayfish neuromuscular junction (NMJ), postsynaptic effects including increases in input resistance occurred at doses greater than 5 microM OA. At lower doses (0.5-5 microM) the effects were solely presynaptic and transmitter release increased over three-fold despite small reductions in amplitude and duration of presynaptic action potentials. Potentiating effects of serotonin on transmitter release, which depend on phosphorylation, were increased by OA. Frequency facilitation was reduced but its decay was not affected. In frog NMJs, OA increased spontaneous and evoked release two-fold through presynaptic mechanisms. An inactive analog of OA, OA tetra-acetate, had no effect on transmitter release at frog and crayfish NMJ. Therefore, phosphatases have a strong modulating influence on synaptic transmission.
Assuntos
Éteres Cíclicos/farmacologia , Monoéster Fosfórico Hidrolases/fisiologia , Serotonina/metabolismo , Transmissão Sináptica/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Animais , Astacoidea , Placa Motora/efeitos dos fármacos , Ácido Okadáico , Monoéster Fosfórico Hidrolases/antagonistas & inibidores , Fosforilação , Rana pipiensRESUMO
Antireflective surfaces were produced on optical borosilicate glass by controlled corrosion in nearly neutral solutions. The surfaces have reflectivity below 0.1% and median threshold for laser-induced damage by 1-nsec 1.06-microm pulses of 12 J/cm(2); twice the median damage threshold of thin film antireflection coatings.
RESUMO
A series of 4-layer silica-tantala antireflection coatings was deposited under 18 different combinations of substrate temperature (175, 250, and 325 degrees C), oxygen pressure (0.5,1.0, and 2.0 x 10(-4) Torr), and rate of deposition (1.5 and 5 A/sec). Measurements of laser-damage threshold for 1064-nm, 1-nsec pulses, average absorption, net stress, and reflectivity were then made on these coatings. Coatings deposited at the lowest temperature had the highest damage thresholds. Damage thresholds were found not to be directly related to average absorption or net stress. Coatings deposited on fused silica substrates which had been polished by a bowl-feed process had generally higher damage thresholds than coatings deposited on conventionally polished fused silica or on BK-7 glass polished by either conventional or bowl-feed processes. Baking coatings in air for 4 h at 400 degrees C generally reduced average absorption and net stress, changed the net stress from compression to tension and, in some cases, increased the damage threshold.