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1.
Comput Sci Eng ; 24(1): 78-85, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35582691

RESUMEN

In March of 2020, recognizing the potential of High Performance Computing (HPC) to accelerate understanding and the pace of scientific discovery in the fight to stop COVID-19, the HPC community assembled the largest collection of worldwide HPC resources to enable COVID-19 researchers worldwide to advance their critical efforts. Amazingly, the COVID-19 HPC Consortium was formed within one week through the joint effort of the Office of Science and Technology Policy (OSTP), the U.S. Department of Energy (DOE), the National Science Foundation (NSF), and IBM to create a unique public-private partnership between government, industry, and academic leaders. This article is the Consortium's story-how the Consortium was created, its founding members, what it provides, how it works, and its accomplishments. We will reflect on the lessons learned from the creation and operation of the Consortium and describe how the features of the Consortium could be sustained as a National Strategic Computing Reserve to ensure the nation is prepared for future crises.

2.
Nat Med ; 28(4): 844-851, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35411074

RESUMEN

Psilocybin therapy shows antidepressant potential, but its therapeutic actions are not well understood. We assessed the subacute impact of psilocybin on brain function in two clinical trials of depression. The first was an open-label trial of orally administered psilocybin (10 mg and 25 mg, 7 d apart) in patients with treatment-resistant depression. Functional magnetic resonance imaging (fMRI) was recorded at baseline and 1 d after the 25-mg dose. Beck's depression inventory was the primary outcome measure ( MR/J00460X/1 ). The second trial was a double-blind phase II randomized controlled trial comparing psilocybin therapy with escitalopram. Patients with major depressive disorder received either 2 × 25 mg oral psilocybin, 3 weeks apart, plus 6 weeks of daily placebo ('psilocybin arm') or 2 × 1 mg oral psilocybin, 3 weeks apart, plus 6 weeks of daily escitalopram (10-20 mg) ('escitalopram arm'). fMRI was recorded at baseline and 3 weeks after the second psilocybin dose ( NCT03429075 ). In both trials, the antidepressant response to psilocybin was rapid, sustained and correlated with decreases in fMRI brain network modularity, implying that psilocybin's antidepressant action may depend on a global increase in brain network integration. Network cartography analyses indicated that 5-HT2A receptor-rich higher-order functional networks became more functionally interconnected and flexible after psilocybin treatment. The antidepressant response to escitalopram was milder and no changes in brain network organization were observed. Consistent efficacy-related brain changes, correlating with robust antidepressant effects across two studies, suggest an antidepressant mechanism for psilocybin therapy: global increases in brain network integration.


Asunto(s)
Trastorno Depresivo Mayor , Alucinógenos , Antidepresivos/farmacología , Antidepresivos/uso terapéutico , Encéfalo/diagnóstico por imagen , Depresión/diagnóstico por imagen , Depresión/tratamiento farmacológico , Trastorno Depresivo Mayor/diagnóstico por imagen , Trastorno Depresivo Mayor/tratamiento farmacológico , Método Doble Ciego , Escitalopram , Alucinógenos/uso terapéutico , Humanos , Psilocibina/farmacología , Psilocibina/uso terapéutico
3.
J Psychopharmacol ; 35(4): 447-452, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33719688

RESUMEN

BACKGROUND: In recent years, there has been significant research on the mental health effects of classic psychedelic use, but there is very little evidence on how classic psychedelics might influence physical health. AIMS: The purpose of the present study was to investigate the associations between lifetime classic psychedelic use and markers of physical health. METHODS: Using data from the National Survey on Drug Use and Health (2015-2018) with 171,766 (unweighted) adults aged 18 or above in the United States, the current study examined the associations between lifetime classic psychedelic use and three markers of physical health (self-reported overall health, body mass index, and heart condition and/or cancer in the past 12 months) while controlling for a range of covariates. RESULTS: Respondents who reported having tried a classic psychedelic at least once in their lifetime had significantly higher odds of greater self-reported overall health and significantly lower odds of being overweight or obese versus having a normal weight. The association between lifetime classic psychedelic use and having a heart condition and/or cancer in the past 12 months approached conventional levels of significance, with lower odds of having a heart condition and/or cancer in the past 12 months for respondents who had tried a classic psychedelic at least once. CONCLUSION: The results of the present study suggest that classic psychedelics may be beneficial to physical health. Future research should investigate the causal effects of classic psychedelics on physical health and evaluate possible mechanisms.


Asunto(s)
Consumidores de Drogas , Estado de Salud , Dietilamida del Ácido Lisérgico , Psilocibina , Trastornos Relacionados con Sustancias , Adulto , Índice de Masa Corporal , Consumidores de Drogas/psicología , Consumidores de Drogas/estadística & datos numéricos , Femenino , Alucinógenos/administración & dosificación , Alucinógenos/efectos adversos , Cardiopatías/diagnóstico , Humanos , Dietilamida del Ácido Lisérgico/administración & dosificación , Dietilamida del Ácido Lisérgico/efectos adversos , Masculino , Salud Mental , Neoplasias/diagnóstico , Psilocibina/administración & dosificación , Psilocibina/efectos adversos , Autoinforme/estadística & datos numéricos , Trastornos Relacionados con Sustancias/epidemiología , Trastornos Relacionados con Sustancias/fisiopatología , Trastornos Relacionados con Sustancias/psicología , Encuestas y Cuestionarios , Estados Unidos/epidemiología
4.
Sci Technol Adv Mater ; 20(1): 568-579, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31231447

RESUMEN

Freestanding (suspended) graphene films, with high electron mobility (up to ~200,000 cm2V-1s-1), good mechanical and electronic properties, could resolve many of the current issues that are hampering the upscaling of graphene technology. Thus far, attempts at reliably fabricating suspended graphene devices comprising metal contacts, have often been hampered by difficulties in exceeding sizes of 1 µm in diameter, if using UV lithography. In this work, area of suspended graphene large enough to be utilized in microelectronic devices, have been obtained by suspending a CVD graphene film over cavities, with top contacts defined through UV lithography with both wet and dry etching. An area of up to 160 µm2 can be fabricated as backgated devices. The suspended areas exhibit rippling of the surfaces which simultaneously introduces both tensile and compressive strain on the graphene film. Finally, the variations of the Fermi level in the suspended graphene areas can be modulated by applying a potential difference between the top contacts and the backgate. Having achieved large area suspended graphene, in a manner compatible with CMOS fabrication processes, together with enabling the modulation of the Fermi level, are substantial steps forward in demonstrating the potential of suspended graphene-based electronic devices and sensors.

5.
J Pers Assess ; 101(4): 367-373, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30907636

RESUMEN

The Alternative Model for Personality Disorders (AMPD) construes personality disorder diagnosis in terms of levels of personality functioning (LPF) as well as dimensions of pathological personality traits. The Hierarchical Taxonomy of Psychopathology (HiTOP), which offers a comprehensive framework for conceptualizing psychopathology, integrates pathological personality traits into a model for understanding different disorders, deficits, and personality problems. Widiger et al. ( 2018 ) placed LPF within the HiTOP model, suggesting that LPF might already be subsumed by trait dimensions and other spectra representing severity of psychopathology. This commentary raises a number of questions about their underlying assumptions, and advocates for an expanded role for LPF to more fully capture the complexity and instability inherent in personality disorder pathology.


Asunto(s)
Trastornos de la Personalidad , Psicopatología , Manual Diagnóstico y Estadístico de los Trastornos Mentales , Humanos , Personalidad , Inventario de Personalidad
6.
J Psychopharmacol ; 33(9): 1058-1067, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-30816808

RESUMEN

BACKGROUND: Novel psychedelics approximate classic psychedelics, but unlike classic psychedelics, novel psychedelics have been used by humans for a shorter period of time, with fewer data available on these substances. AIMS: The purpose of this study was to determine the prevalence of novel psychedelic use and the associations of novel psychedelic use with mental health outcomes. METHODS: We estimated the prevalence of self-reported, write-in lifetime novel psychedelic use and evaluated the associations of novel psychedelic use with psychosocial characteristics, past month psychological distress, and past year suicidality among adult respondents pooled from years 2008-2016 of the National Survey on Drug Use and Health (weighted n=234,914,788). RESULTS: A fraction (weighted n=273,720; 0.12%) reported lifetime novel psychedelic use. This cohort tended to be younger, male, and White, have greater educational attainment but less income, be more likely to have never been married, engage in self-reported risky behavior, and report lifetime illicit use of other drugs, particularly classic psychedelics (96.9%). (2-(4-Bromo-2,5-dimethoxyphenyl)ethanamine) (2C-B) (30.01%), (2,5-dimethoxy-4-iodophenethylamine) (2C-I) (23.9%), and (1-(2,5-dimethoxy-4-ethylphenyl)-2-aminoethane) (2C-E) (14.8%) accounted for the majority of lifetime novel psychedelic use. Although lifetime novel psychedelic use was not associated with psychological distress or suicidality compared to no lifetime novel psychedelic use or classic psychedelic use, relative to lifetime use of classic psychedelics but not novel psychedelics, lifetime novel psychedelic use was associated with a greater likelihood of past year suicidal thinking (adjusted Odds Ratio (aOR)=1.4 (1.1-1.9)) and past year suicidal planning (aOR=1.6 (1.1-2.4)). CONCLUSION: Novel psychedelics may differ from classic psychedelics in meaningful ways, though additional, directed research is needed.


Asunto(s)
Alucinógenos/uso terapéutico , Adolescente , Adulto , Anciano , Estudios de Cohortes , Femenino , Humanos , Masculino , Salud Mental , Persona de Mediana Edad , Prevalencia , Factores de Riesgo , Autoinforme , Ideación Suicida , Intento de Suicidio/prevención & control , Estados Unidos , Adulto Joven
7.
Front Psychiatry ; 10: 896, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-32116806

RESUMEN

INTRODUCTION: The majority of contemporary psychedelic research has focused on ayahuasca, lysergic acid diethylamide, and psilocybin, though there are hundreds of novel psychedelic compounds that may have clinical utility. The purpose of the present study was to evaluate the therapeutic potential of classic and novel phenethylamine, tryptamine, and lysergamide psychedelics via a large, nationally representative population-based survey. METHODS: We tested the unique associations of lifetime classic and novel phenethylamine, tryptamine, and lysergamide psychedelics with past month psychological distress and past year suicidality among respondents pooled from years 2008-2017 of the National Survey on Drug Use and Health (weighted N = 260,964,827). RESULTS: Lifetime classic tryptamine use was associated with a decreased odds of past month psychological distress [aOR = 0.76; (0.69-0.83)] and past year suicidal thinking [aOR = 0.79; (0.72-0.87)]. Lifetime novel phenethylamine use, on the other hand, was associated with an increased odds of past year suicidal thinking [aOR = 1.44; (1.06-1.95)] and past year suicidal planning [aOR = 1.60; (1.06-2.41)]. No other significant associations were found. DISCUSSION AND CONCLUSIONS: These findings, which may be driven by differences in pharmacodynamics, suggest that classic tryptamines may hold the greatest therapeutic potential of the psychedelics, whereas novel phenethylamines may pose risk for harm. The present findings thus support continued research on the clinical application of classic tryptamines. Though the current results caution against the clinical utility of novel phenethylamines, further study of these and other novel psychedelic substances is nonetheless warranted to better understand their potential application.

8.
J Am Psychoanal Assoc ; 67(6): 1047-1055, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-32043393

RESUMEN

A current trend emphasizes simplified models of traits and personality functioning that would reduce individuals to as few as five potential traits and one dimension of personality functioning. However, the evidence behind those models is based on linear methods of analysis that authors from Cattell to Kernberg (2016) believe do not capture the potential moderating interaction effects of personality. Using models of traits and functioning from the DSM-5, this study demonstrates not only that traits and functioning interact, but that they do so in a rich and meaningful way that points up the dangers of collapsing these concepts. Without taking the interaction into account, satisfaction in romantic or work relationships often could not be predicted or understood. If we cannot predict satisfaction in these relationships with precision, honest confusion arises over how to guide others toward these goals. Low Detachment depends on high levels of Self-Definition, just as low Antagonism relies on high levels of Empathy to be successful. Most interestingly, negative traits and low functioning can actually lead to individual satisfaction, suggesting not only that interaction is key but that nonlinear effects may also be present.


Asunto(s)
Trastornos de la Personalidad , Personalidad , Manual Diagnóstico y Estadístico de los Trastornos Mentales , Humanos , Satisfacción Personal , Inventario de Personalidad
9.
Cureus ; 10(5): e2571, 2018 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-29974026

RESUMEN

Foreign body aspiration occurs in all age groups, especially in children and the elderly. The aspiration of an organic foreign body such as iron sulfate can cause significant bronchial destruction via oxidizing necrosis. When iron comes into contact with bronchial mucosa, it gets oxidized from ferrous ions into a ferric form which is highly toxic to the mucosa causing severe inflammation, mucosal damage, and fibrosis. Physicians should be very prudent with prescribing iron sulfate or any other pills in individuals who are at high risk of aspiration. Diagnosis is based on the history of iron aspiration, intense airway inflammation or necrosis on bronchoscopic examination, and iron particles observed on pathology. Prompt diagnosis and management should take place to prevent further morbidities. We report a case of 61-year-old female who was admitted to the hospital with a four-week history of aspirating iron pill. Computed tomography (CT) of the thorax showed ground glass infiltrates in the right lower lobe. She underwent flexible bronchoscopy which showed distal right bronchus intermedius (RBI) necrosis and stenosis with near-complete obstruction of distal RBI. She underwent multiple advanced bronchoscopic interventions with minimal improvement of the obliterated bronchus.

10.
Personal Disord ; 9(6): 553-563, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-29215901

RESUMEN

With the introduction in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) of a hybrid system of personality disorder assessment, the ability to assess patients' traits, as well as their level of personality functioning, has become increasingly important. To assess this criterion, the DSM-5 Levels of Personality Functioning Questionnaire (DLOPFQ) was developed. The DLOPFQ assesses individuals' self-impairments and other impairments in several domains (self-direction, identity, empathy, and intimacy) and across 2 contexts (work/school and relationships). A sample of 140 psychiatric and medical outpatients was administered the DLOPFQ and several other measures to assess its reliability and construct, incremental, and discriminant validity. The internal consistency and convergence with validation measures yielded generally meaningful and expected results. Several DLOPFQ scales and subscales were significantly correlated with measures of DSM-5 trait domains and levels of personality functioning. DLOPFQ scales also correlated with self-reported ratings of overdependence, detachment, healthy dependency, and overall mental health and well-being. The DLOPFQ also predicted interpersonal and general functioning beyond DSM-5 trait domains. These results support the reliability and validity of the DLOPFQ, which appears to be suitable for clinical use and warrants ongoing study. (PsycINFO Database Record (c) 2018 APA, all rights reserved).


Asunto(s)
Manual Diagnóstico y Estadístico de los Trastornos Mentales , Trastornos de la Personalidad/diagnóstico , Personalidad , Encuestas y Cuestionarios , Adolescente , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Determinación de la Personalidad , Psicometría , Reproducibilidad de los Resultados , Adulto Joven
11.
J Pers Assess ; 100(6): 671-679, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30907714

RESUMEN

The ability to evaluate patients' level of personality functioning in assessing personality disorders has become increasingly important since the DSM-5 Section III hybrid system of personality disorder assessment was released. One measure developed to assess this criterion is the DSM-5 Levels of Personality Functioning Questionnaire (DLOPFQ; Huprich et al., 2017 ), which assesses individuals' self and other representations in four domains-self-direction, identity, empathy, and intimacy-across two contexts-work or school and relationships. A sample of 140 psychiatric and internal medicine outpatients were administered several questionnaires, including the DLOPFQ. Provider ratings also were obtained for level of functioning and DSM-5 pathological personality traits. Several of the DLOPFQ scales were significantly correlated with self-reported and provider-reported measures of DSM-5 trait domains and levels of functioning, along with self-reported measures of effortful control, overall physical and mental health, and well-being. Certain DLOPFQ scales and subscales were associated with provider ratings of likeability and patient contact with the providers. However, relatively modest validity coefficients, as well as poor discriminant validity of domain scales, indicate further research and measure refinement might be needed. It is concluded that, although further research is necessary, the DLOPFQ could be useful for understanding patients' personality pathology in clinical settings.


Asunto(s)
Personal de Salud , Pacientes Ambulatorios/estadística & datos numéricos , Determinación de la Personalidad/normas , Trastornos de la Personalidad/diagnóstico , Personalidad , Adulto , Manual Diagnóstico y Estadístico de los Trastornos Mentales , Femenino , Humanos , Masculino , Trastornos de la Personalidad/psicología , Autoinforme
12.
Sci Rep ; 7(1): 17879, 2017 12 19.
Artículo en Inglés | MEDLINE | ID: mdl-29259286

RESUMEN

Random number generation is crucial in many aspects of everyday life, as online security and privacy depend ultimately on the quality of random numbers. Many current implementations are based on pseudo-random number generators, but information security requires true random numbers for sensitive applications like key generation in banking, defence or even social media. True random number generators are systems whose outputs cannot be determined, even if their internal structure and response history are known. Sources of quantum noise are thus ideal for this application due to their intrinsic uncertainty. In this work, we propose using resonant tunnelling diodes as practical true random number generators based on a quantum mechanical effect. The output of the proposed devices can be directly used as a random stream of bits or can be further distilled using randomness extraction algorithms, depending on the application.

13.
Behav Sci Law ; 30(6): 749-63, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-23001717

RESUMEN

The Gudjonsson Suggestibility Scales (GSS) is a valuable test to use as part of a comprehensive assessment of psychological and interrogative factors relevant to a defendant's vulnerability to giving a false or involuntary confession. One limitation of the test is that the manual only provides information for samples from Iceland and Great Britain. This report describes the results of 334 individuals in the United States, who were administered the tests as part of an evaluation to assess confession-related issues in a forensic context (i.e., capacity to waive Miranda rights or vulnerability in providing a false or involuntary confession). This forensic sample includes both juveniles and adults. Results are consistent with Gudjonsson's British and Icelandic samples, in which the Yield 1 score is more affected by intellectual and cognitive variables, but Shift and, to a lesser extent, Yield 2 scores are more related to emotional and personality characteristics.


Asunto(s)
Coerción , Criminales/psicología , Inventario de Personalidad , Autorrevelación , Adolescente , Adulto , Intervalos de Confianza , Femenino , Florida , Psiquiatría Forense , Humanos , Masculino , Psicometría , Encuestas y Cuestionarios , Estados Unidos , Adulto Joven
14.
Behav Sci Law ; 30(6): 673-92, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22736529

RESUMEN

The Instruments for Assessing Understanding and Appreciation of Miranda Rights, hereafter referred to as the Grisso tests, are widely used and recommended psychological tests designed to help assess ability to understand and appreciate Miranda warnings. This article describes the results of these tests administered to 439 individuals who participated in an evaluation to assess knowing and intelligent waiver of Miranda warnings during police questioning. This study is the first of its kind using a large sample of defendants who were referred for an assessment of capacity to waive Miranda rights. This forensic sample includes both juveniles (176) and adults (263), and the results are quite similar to the original Grisso norms. There are strong correlations between performance on these tests and IQ as well as between performance and age. This sample provides a broader foundation for users of the Grisso tests and answers some of the initial criticism of the instruments.


Asunto(s)
Derechos Civiles/legislación & jurisprudencia , Comprensión , Criminales/psicología , Encuestas y Cuestionarios , Adolescente , Adulto , Anciano , Femenino , Florida , Psiquiatría Forense/instrumentación , Humanos , Aplicación de la Ley , Masculino , Persona de Mediana Edad , Análisis de Regresión , Adulto Joven
16.
Clin Psychol Psychother ; 18(6): 464-85, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-20941796

RESUMEN

The present study examined the relationship between the Rorschach Ego Impairment Index (EII) and psychiatric severity. Search procedures yielded 13 independent samples (total N = 1402, average n = 108, standard deviation = 90) for inclusion in the meta-analysis. Inter-rater reliability analyses demonstrated that coding of effect sizes and moderator variables was completed with good to excellent reliability. Results indicated that higher EII scores were associated with greater psychiatric severity, with an overall weighted effect size of r = 0.29, p = 0.000002 (95% confidence interval = 0.17-0.40), supporting the EII's validity as a measure of psychological impairment. Publication bias analyses did not indicate any significant cause for concern regarding the results. The data were demonstrably heterogeneous (Q = 56.82, p = 0.0000001), and results of post-hoc tests indicated that effect sizes with dependent variables obtained via researcher ratings were significantly larger than any of the following: effect sizes with dependent variables obtained via clinician ratings, informant ratings, information about level of treatment or placement status or self-report ratings (p's = 0.0005, 0.003, <0.001, <0.001, respectively). In addition, there was a trend for effect sizes based on performance-based measures to be larger than those based on information about level of treatment or placement status (p = 0.098) as well as those based on self-report measures (p = 0.076). Other moderator analyses were non-significant (p 's > 0.10). Copyright © 2010 John Wiley & Sons, Ltd. Key Practitioner Message: • The Rorschach Ego Impairment Index (EII) demonstrated validity in measuring psychiatric severity across a range of normative, outpatient, residential, and inpatient samples. • The degree of the EII's validity in assessing psychiatric severity compared favorably to the overall validity of the Rorschach and the MMPI. • The EII appears to be most valid in capturing psychiatric severity as measured by researcher ratings of social competency or estimated ego impairment.


Asunto(s)
Trastornos Mentales/psicología , Prueba de Rorschach/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Ego , Humanos , Trastornos Mentales/diagnóstico , Persona de Mediana Edad , Variaciones Dependientes del Observador , Psicometría , Trastornos Psicóticos/diagnóstico , Trastornos Psicóticos/psicología , Reproducibilidad de los Resultados , Índice de Severidad de la Enfermedad , Adulto Joven
17.
AAPS PharmSciTech ; 5(2): e31, 2004 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-15760089

RESUMEN

The purpose of this research was to further investigate the hydrodynamics of the United States Pharmacopeia (USP) paddle dissolution apparatus using a previously generated computational fluid dynamics (CFD) model. The influence of paddle rotational speed on the hydrodynamics in the dissolution vessel was simulated. The maximum velocity magnitude for axial and tangential velocities at different locations in the vessel was found to increase linearly with the paddle rotational speed. Path-lines of fluid mixing, which were examined from a central region at the base of the vessel, did not reveal a region of poor mixing between the upper cylindrical and lower hemispherical volumes, as previously speculated. Considerable differences in the resulting flow patterns were observed for paddle rotational speeds between 25 and 150 rpm. The approximate time required to achieve complete mixing varied between 2 to 5 seconds at 150 rpm and 40 to 60 seconds at 25 rpm, although complete mixing was achievable for each speed examined. An analysis of CFD-generated velocities above the top surface of a cylindrical compact positioned at the base of the vessel, below the center of the rotating paddle, revealed that the fluid in this region was undergoing solid body rotation. An examination of the velocity boundary layers adjacent to the curved surface of the compact revealed large peaks in the shear rates for a region within ~3 mm from the base of the compact, consistent with a "grooving" effect, which had been previously seen on the surface of compacts following dissolution, associated with a higher dissolution rate in this region.


Asunto(s)
Modelos Químicos , Tecnología Farmacéutica/instrumentación , Fenómenos Físicos , Física , Solubilidad
18.
AAPS PharmSciTech ; 4(2): E22, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12916904

RESUMEN

The objective of this work was to examine the feasibility of developing a high-performance computing software system to simulate the United States Pharmacopeia (USP) dissolution apparatus 2 (paddle apparatus) and thus aid in characterizing the fluid hydrodynamics in the method. The USP apparatus was modeled using the hydrodynamic package Fluent. The Gambit program was used to create a "wireframe" of the apparatus and generate the 3-dimensional grids for the computational fluid dynamics solver. The Fluent solver was run on an IBM RS/6000 SP distributed memory parallel processor system, using 8 processors. Configurations with and without a tablet present were developed and examined. Simulations for a liquid-filled vessel at a paddle speed of 50 rpm were generated. Large variations in fluid velocity magnitudes with position in the vessel were evident. Fluid velocity predictions were in good agreement with those previously published, using laser Doppler velocity measurements. A low-velocity domain was evident directly below the center of the rotating paddle. The model was extended to simulate the impact of the presence of a cylindrical tablet in the base of the dissolution vessel. The presence of the tablet complicated the local fluid flow, and large fluid shear rates were evident at the base of the compact. Fluid shear rates varied depending on the tablet surface and the location on the surface and were consistent with the reported asymmetrical dissolution of model tablets. The approach has the potential to explain the variable dissolution results reported and to aid in the design/prediction of optimal dissolution conditions for in vitro--in vivo correlations.


Asunto(s)
Química Farmacéutica , Modelos Químicos , Farmacopeas como Asunto , Estados Unidos
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