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1.
Expert Rev Cardiovasc Ther ; 21(5): 357-364, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37024997

RESUMO

OBJECTIVES: Cardiac rehabilitation - programs comprehensively delivering outpatient secondary prevention - is under-available and under-studied in the resource-poor settings where it is needed most. This report summarizes the governance, participating sites, patient characteristics and outcomes, as well as knowledge translation activities during first year of operation of ICCPR's registry, namely the International Cardiac Rehab Registry. METHODS: A pilot study was undertaken with five centers, demonstrating feasibility, satisfaction with the on-boarding processes, as well as data quality. RESULTS: Fourteen centers have been engaged from all regions but Europe; Data have been entered on >1000 patients (18.1% female; mean age = 57.6), of whom 62.4% completed their programs and 19.9% dropped out for work or clinical reasons. Post-program, completers had significantly better work status, functional capacity, medication adherence, physical activity levels, diet, as well as lower tobacco use than non-completers (all p < 0.05). A site Certification program was developed and piloted, with five centers now recognized for their quality, given they met over 70% of the 13 internationally agreed standards based on Registry data and a virtual site assessment. CONCLUSION: Annual assessments have started. Quality improvement activities will soon be underway. We continue to invite new programs, supporting development in resource-poor settings to the benefit of patients served.


Assuntos
Reabilitação Cardíaca , Doenças Cardiovasculares , Humanos , Feminino , Pessoa de Meia-Idade , Masculino , Projetos Piloto , Europa (Continente) , Doenças Cardiovasculares/prevenção & controle , Sistema de Registros
2.
Phys Rev Lett ; 129(10): 102701, 2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36112434

RESUMO

Carbon burning is a key step in the evolution of massive stars, Type 1a supernovae and superbursts in x-ray binary systems. Determining the ^{12}C+^{12}C fusion cross section at relevant energies by extrapolation of direct measurements is challenging due to resonances at and below the Coulomb barrier. A study of the ^{24}Mg(α,α^{'})^{24}Mg reaction has identified several 0^{+} states in ^{24}Mg, close to the ^{12}C+^{12}C threshold, which predominantly decay to ^{20}Ne(ground state)+α. These states were not observed in ^{20}Ne(α,α_{0})^{20}Ne resonance scattering suggesting that they may have a dominant ^{12}C+^{12}C cluster structure. Given the very low angular momentum associated with sub-barrier fusion, these states may play a decisive role in ^{12}C+^{12}C fusion in analogy to the Hoyle state in helium burning. We present estimates of updated ^{12}C+^{12}C fusion reaction rates.

3.
Nature ; 590(7847): 566-570, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33627809

RESUMO

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning1; this phenomenon has been a mystery in nuclear physics for over 40 years2,3. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum4-12. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors13,14, for the study of the structure of neutron-rich isotopes15,16, and for the synthesis and stability of super-heavy elements17,18.

4.
Phys Rev Lett ; 124(19): 192701, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32469543

RESUMO

The ^{12}C+^{12}C fusion reaction plays a critical role in the evolution of massive stars and also strongly impacts various explosive astrophysical scenarios. The presence of resonances in this reaction at energies around and below the Coulomb barrier makes it impossible to carry out a simple extrapolation down to the Gamow window-the energy regime relevant to carbon burning in massive stars. The ^{12}C+^{12}C system forms a unique laboratory for challenging the contemporary picture of deep sub-barrier fusion (possible sub-barrier hindrance) and its interplay with nuclear structure (sub-barrier resonances). Here, we show that direct measurements of the ^{12}C+^{12}C fusion cross section may be made into the Gamow window using an advanced particle-gamma coincidence technique. The sensitivity of this technique effectively removes ambiguities in existing measurements made with gamma ray or charged-particle detection alone. The present cross-section data span over 8 orders of magnitude and support the fusion-hindrance model at deep sub-barrier energies.

5.
Hautarzt ; 71(3): 219-222, 2020 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-31659388

RESUMO

A 16-year-old female developed a satellite-like recurrence of a pyogenic granuloma on her thorax 2 weeks after complete excision. Treatment with a pulsed dye laser led to a complete resolution. BRAF and RAS mutations detected in the pyogenic granuloma are considered major driver mutations. Whether these findings are also of importance for the etiopathogenesis of satellitosis is unknown. In our patient, no BRAF or NRAS mutation could be detected.


Assuntos
Granuloma Piogênico/terapia , Lasers de Corante/uso terapêutico , Dermatopatias/patologia , Doenças Torácicas/patologia , Adolescente , Feminino , GTP Fosfo-Hidrolases , Granuloma Piogênico/diagnóstico , Granuloma Piogênico/genética , Humanos , Proteínas de Membrana , Mutação , Proteínas Proto-Oncogênicas B-raf , Recidiva , Doenças Torácicas/terapia , Resultado do Tratamento
6.
Sci Rep ; 9(1): 18818, 2019 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-31827157

RESUMO

The cellular membrane is very heterogenous and enriched with high-density regions forming microdomains, as revealed by single particle tracking experiments. However the organization of these regions remain unexplained. We determine here the biophysical properties of these regions, when described as a basin of attraction. We develop two methods to recover the dynamics and local potential wells (field of force and boundary). The first method is based on the local density of points distribution of trajectories, which differs inside and outside the wells. The second method focuses on recovering the drift field that is convergent inside wells and uses the transient field to determine the boundary. Finally, we apply these two methods to the distribution of trajectories recorded from voltage gated calcium channels and phospholipid anchored GFP in the cell membrane of hippocampal neurons and obtain the size and energy of high-density regions with a nanometer precision.

7.
Phys Rev Lett ; 120(15): 152504, 2018 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-29756867

RESUMO

The emission of neutron pairs from the neutron-rich N=12 isotones ^{18}C and ^{20}O has been studied by high-energy nucleon knockout from ^{19}N and ^{21}O secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n-n correlations shows that the decay ^{19}N(-1p)^{18}C^{*}→^{16}C+n+n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a ^{14}C core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay ^{21}O(-1n)^{20}O^{*}→^{18}O+n+n, attributed to its formation through the knockout of a deeply bound neutron that breaks the ^{16}O core and reduces the number of pairs.

8.
Phys Rev Lett ; 120(5): 052501, 2018 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-29481189

RESUMO

Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R^{3}B/LAND setup with incident beam energies in the range of 300-450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type ^{A}O(p,2p)^{A-1}N have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry.

9.
Nat Commun ; 5: 3377, 2014 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-24566714

RESUMO

Interest in many strongly spin-orbit-coupled 5d-transition metal oxide insulators stems from mapping their electronic structures to a J(eff)=1/2 Mott phase. One of the hopes is to establish their Mott parent states and explore these systems' potential of realizing novel electronic states upon carrier doping. However, once doped, little is understood regarding the role of their reduced Coulomb interaction U relative to their strongly correlated 3d-electron cousins. Here we show that, upon hole-doping a candidate J(eff)=1/2 Mott insulator, carriers remain localized within a nanoscale phase-separated ground state. A percolative metal-insulator transition occurs with interplay between localized and itinerant regions, stabilizing an antiferromagnetic metallic phase beyond the critical region. Our results demonstrate a surprising parallel between doped 5d- and 3d-electron Mott systems and suggest either through the near-degeneracy of nearby electronic phases or direct carrier localization that U is essential to the carrier response of this doped spin-orbit Mott insulator.

10.
Nat Commun ; 5: 3024, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24429796

RESUMO

Organization of signalling molecules in biological membranes is crucial for cellular communication. Many receptors, ion channels and cell adhesion molecules are associated with proteins important for their trafficking, surface localization or function. These complexes are embedded in a lipid environment of varying composition. Binding affinities and stoichiometry of such complexes were so far experimentally accessible only in isolated systems or monolayers of cell culture. Visualization of molecular dynamics within signalling complexes and their correlation to specialized membrane compartments demand high temporal and spatial resolution and has been difficult to demonstrate in complex tissue like brain slices. Here we demonstrate the feasibility of single-particle tracking (SPT) in organotypic brain slices to measure molecular dynamics of lipids and transmembrane proteins in correlation to synaptic membrane compartments. This method will provide important information about the dynamics and organization of surface molecules in the complex environment of neuronal networks within brain slices.


Assuntos
Membrana Celular/metabolismo , Hipocampo/metabolismo , Lipídeos de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Animais , Encéfalo/metabolismo , Células Cultivadas , Hipocampo/citologia , Metabolismo dos Lipídeos , Camundongos , Microscopia de Fluorescência , Simulação de Dinâmica Molecular , Estrutura Molecular , Pontos Quânticos , Ratos
12.
Hautarzt ; 63(1): 42-6, 2012 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-21706210

RESUMO

A 90-year-old woman presented with an extensive primary form of extramammary Paget disease localized in the anogenital region. An associated carcinoma could be excluded. Due to the age of the patient, the location and extent of the tumor as well as existing comorbidities, neither a surgical nor a radio-oncological treatment were advisable. A local treatment with imiquimod 5% cream applied 3 times weekly for 2 × 3 weeks led to a clinically and histopathologically complete remission. As also shown by other authors, imiquimod appears to be a treatment option for the primary form of extramammary Paget disease.


Assuntos
Aminoquinolinas/administração & dosagem , Neoplasias do Ânus/tratamento farmacológico , Doença de Paget Extramamária/tratamento farmacológico , Administração Tópica , Idoso de 80 Anos ou mais , Aminoquinolinas/química , Neoplasias do Ânus/diagnóstico , Fármacos Dermatológicos/administração & dosagem , Feminino , Humanos , Imiquimode , Doença de Paget Extramamária/diagnóstico
13.
Mol Psychiatry ; 16(5): 491-503, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-20308990

RESUMO

Attention-deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurodevelopmental syndrome characterized by hyperactivity, inattention and increased impulsivity. To detect micro-deletions and micro-duplications that may have a role in the pathogenesis of ADHD, we carried out a genome-wide screen for copy number variations (CNVs) in a cohort of 99 children and adolescents with severe ADHD. Using high-resolution array comparative genomic hybridization (aCGH), a total of 17 potentially syndrome-associated CNVs were identified. The aberrations comprise 4 deletions and 13 duplications with approximate sizes ranging from 110 kb to 3 Mb. Two CNVs occurred de novo and nine were inherited from a parent with ADHD, whereas five are transmitted by an unaffected parent. Candidates include genes expressing acetylcholine-metabolizing butyrylcholinesterase (BCHE), contained in a de novo chromosome 3q26.1 deletion, and a brain-specific pleckstrin homology domain-containing protein (PLEKHB1), with an established function in primary sensory neurons, in two siblings carrying a 11q13.4 duplication inherited from their affected mother. Other genes potentially influencing ADHD-related psychopathology and involved in aberrations inherited from affected parents are the genes for the mitochondrial NADH dehydrogenase 1 α subcomplex assembly factor 2 (NDUFAF2), the brain-specific phosphodiesterase 4D isoform 6 (PDE4D6) and the neuronal glucose transporter 3 (SLC2A3). The gene encoding neuropeptide Y (NPY) was included in a ∼3 Mb duplication on chromosome 7p15.2-15.3, and investigation of additional family members showed a nominally significant association of this 7p15 duplication with increased NPY plasma concentrations (empirical family-based association test, P=0.023). Lower activation of the left ventral striatum and left posterior insula during anticipation of large rewards or losses elicited by functional magnetic resonance imaging links gene dose-dependent increases in NPY to reward and emotion processing in duplication carriers. These findings implicate CNVs of behaviour-related genes in the pathogenesis of ADHD and are consistent with the notion that both frequent and rare variants influence the development of this common multifactorial syndrome.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Variações do Número de Cópias de DNA/genética , Dosagem de Genes/genética , Neuropeptídeo Y/genética , Linhagem , Adolescente , Transtorno do Deficit de Atenção com Hiperatividade/patologia , Encéfalo/irrigação sanguínea , Encéfalo/patologia , Criança , Mapeamento Cromossômico/métodos , Cromossomos Humanos Par 7/genética , Estudos de Coortes , Hibridização Genômica Comparativa/métodos , Saúde da Família , Feminino , Estudo de Associação Genômica Ampla/métodos , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética/métodos , Masculino , Neuropeptídeo Y/sangue , Oxigênio/sangue , Fenótipo
14.
Am J Med Genet B Neuropsychiatr Genet ; 153B(2): 512-523, 2010 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-19603419

RESUMO

Attention-deficit hyperactivity disorder (ADHD) is a multifactorial, neurodevelopmental disorder that often persists into adolescence and adulthood and is characterized by inattention, hyperactivity and impulsiveness. Before the advent of the first genome-wide association studies in ADHD, genetic research had mainly focused on candidate genes related to the dopaminergic and serotoninergic systems, although several other genes had also been assessed. Pharmacological data, analysis of animal models and association studies suggest that Brain-Derived Neurotrophic Factor (BDNF) is also a strong candidate gene for ADHD. Several polymorphisms in BDNF have been reported and studied in psychiatric disorders but the most frequent is the p.Val66Met (rs6265G > A) single nucleotide polymorphism (SNP), with functional effects on the intracellular trafficking and secretion of the protein. To deal with the inconsistency raised among different case-control and family-based association studies regarding the p.Val66Met contribution to ADHD, we performed a meta-analysis of published as well as unpublished data from four different centers that are part of the International Multicentre Persistent ADHD CollaboraTion (IMpACT). A total of 1,445 adulthood ADHD patients and 2,247 sex-matched controls were available for the study. No association between the p.Val66Met polymorphism and ADHD was found in any of the four populations or in the pooled sample. The meta-analysis also showed that the overall gene effect for ADHD was not statistically significant when gender or comorbidity with mood disorders were considered. Despite the potential role of BDNF in ADHD, our data do not support the involvement of p.Val66Met in the pathogenesis of this neuropsychiatric disorder.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Fator Neurotrófico Derivado do Encéfalo/genética , Metionina/genética , Valina/genética , Adulto , Estudos de Casos e Controles , Europa (Continente) , Feminino , Genética Populacional , Genótipo , Humanos , Masculino , Transtornos Mentais/genética , Modelos Genéticos , Modelos Neurológicos , Polimorfismo de Nucleotídeo Único , Estudos Retrospectivos , Fatores Sexuais
15.
J Neural Transm (Vienna) ; 116(2): 121-30, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18982239

RESUMO

Dopamine-beta-hydroxylase (DbetaH) catalyzes the conversion of dopamine to norepinephrine in central noradrenergic and adrenergic neurons and thus is critically involved in the biosynthesis of catecholamines. There are equivocal findings concerning the question whether or not DssH activity levels are altered in affective disorders or in subtypes of affective disorders. Moreover, information about the role of dopamine beta-hydroxylase (DBH) genotype, which explains a large part of the variance of enzymatic activity, in affective disorders and personality dimensions is limited. To resolve these inconsistencies, association tests were performed using four independent samples, healthy volunteers (N = 387), patients with affective disorders (N = 182), adult attention deficit hyperactivity disorder (ADHD) patients (N = 407), and patients with personality disorders (N = 637). In the latter two samples, the revised NEO personality inventory (NEO-PI-R) was administered. All participants were genotyped for a putatively functional single nucleotide polymorphism (C-1021T, rs1611115). No differences in DBH C-1021T genotype distribution were observed between patients with affective disorders and healthy control subjects. Also when the patient sample was divided into uni- and bipolar patients versus controls, no significant differences emerged. Furthermore, no clear-cut association was detected between the TT genotype and personality disorder clusters while there was a significant association with adult ADHD. However, personality disorder patients carrying the DBH TT genotype exhibited higher neuroticism and novelty seeking scores as compared to individuals with the CC or CT genotype. Analyses on the level of the neuroticism and novelty seeking subscales revealed that the DBH TT genotype was primarily associated with personality features related to impulsiveness and aggressive hostility. Also adult ADHD patients carrying the homozygous TT genotypes displayed by significantly increased neuroticism scores; when both personality disorder and adult ADHD patient were analyzed together, TT carriers also displayed by significantly lower conscientiousness levels. Our results thus do not implicate the DBH C-1021T polymorphism in the pathophysiology of depressive disorders or personality disorders, yet homozygosity at this locus appears to increase the risk towards personality traits related to impulsiveness, aggression and related disease states, namely adult ADHD. These data argue for a dimensional rather than categorical effect of genetic variance in DBH activity; accordingly, the inconsistency of previous findings concerning DbetaH levels in affective disorders might be caused by the underlying association of the TT genotype at DBH-1021 with impulsive personality traits.


Assuntos
Dopamina beta-Hidroxilase/genética , Transtornos do Humor/genética , Transtornos da Personalidade/genética , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas/genética , Transtorno do Deficit de Atenção com Hiperatividade/genética , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase
16.
J Neural Transm (Vienna) ; 116(1): 97-104, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19030776

RESUMO

This study examined EEG abnormalities in adults with attention deficit hyperactivity disorder (ADHD). We investigated EEG frequencies in 34 adults with ADHD and 34 control subjects. Two EEG readings were taken over 5 min intervals during an eyes-closed resting period with 21 electrodes placed in accordance with the international 10-20 system. Fourier transformation was performed to obtain absolute power density in delta, theta, alpha and beta frequency bands. The ADHD patients showed a significant increase of absolute power density in alpha and theta bands. No differences were found for beta activity. Our findings indicate that abnormalities in the EEG power spectrum of adults with ADHD are different than those described in children. Reliable discriminators between patients and healthy subjects in adulthood could be alpha and theta power density. Based on our results, we suggest further research involving longitudinal studies in ADHD patients to investigate the changes of EEG abnormalities with age.


Assuntos
Ritmo alfa , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Ritmo Teta , Adolescente , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/patologia , Encéfalo/fisiopatologia , Mapeamento Encefálico , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Estatística como Assunto , Fatores de Tempo , Adulto Jovem
17.
Mol Psychiatry ; 13(5): 522-30, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18301393

RESUMO

Previous genome-wide linkage studies applied the affected sib-pair design; one investigated extended pedigrees of a genetic isolate. Here, results of a genome-wide high-density linkage scan of attention-deficit/hyperactivity disorder (ADHD) using an array-based genotyping of approximately 50 K single nucleotide polymorphism (SNPs) markers are presented. We investigated eight extended pedigrees of German origin that were non-related, not part of a genetic isolate and ascertained on the basis of clinical referral. Two parametric analyses maximizing LOD scores (MOD) and a non-parametric analysis for both a broad and a narrow phenotype approach were conducted. Novel linkage loci across all families were detected at 2q35, 5q13.1, 6q22-23 and 14q12, within individual families at 18q11.2-12.3. Further linkage regions at 7q21.11, 9q22 and 16q24.1 in all families, and at 1q25.1, 1q25.3, 9q31.1-33.1, 9q33, 12p13.33, 15q11.2-13.3 and 16p12.3-12.2 in individual families replicate previous findings. High-resolution linkage mapping points to several novel candidate genes characterized by dense expression in the brain and potential impact on disorder-relevant synaptic transmission. Our study provides further evidence for common gene effects throughout different populations despite the complex multifactorial etiology of ADHD.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Cromossomos Humanos Par 14/genética , Cromossomos Humanos Par 5/genética , Polimorfismo de Nucleotídeo Único , Adolescente , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Criança , Feminino , Genótipo , Alemanha/epidemiologia , Humanos , Escore Lod , Masculino , Variações Dependentes do Observador , Análise de Sequência com Séries de Oligonucleotídeos , Linhagem , Índice de Gravidade de Doença , Estatísticas não Paramétricas
18.
Langmuir ; 23(19): 9882-90, 2007 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-17685639

RESUMO

Particle growth by Brownian coagulation at high concentration in the continuum regime is investigated by solving the Langevin dynamics (LD) equations for each particle trajectory of polydisperse suspensions. By monitoring the LD attainment of the self-preserving size distribution (SPSD), it is shown that the classic Smoluchowski collision frequency function is accurate for dilute particle volume fractions, phis, below 0.1%. At higher phis, coagulation is about 4 and 10 times faster than for the classic theory at phis = 10 and 20%, respectively. For complete particle coalescence upon collision, SPSDs develop even in highly concentrated suspensions (up to phis = 35%), as with dilute ones, but are broadened with increasing phis. At high particle concentration, an overall coagulation rate is proposed that reduces to the classic one at low concentration. Detailed collision frequency functions are also obtained at various phis values. Fractal-like agglomerates undergoing coagulation at constant fractal dimension attain an SPSD only temporarily because their effective volume fraction continuously increases, approaching gelation in the absence of restructuring or fragmentation.

19.
Langmuir ; 22(24): 10238-45, 2006 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-17107027

RESUMO

The dynamics of agglomerate aerosols are investigated at high solids concentrations that are typical in industrial scale manufacture of fine particles (precursor mole fraction larger than 10 mol %). In particular, formation and growth of fumed silica at such concentrations by chemical reaction, coagulation, and sintering is simulated at nonisothermal conditions and compared to limited experimental data and commercial product specifications. Using recent chemical kinetics for silica formation by SiCl4 hydrolysis and neglecting aerosol polydispersity, the evolution of the diameter of primary particles (specific surface area, SSA), hard- and soft-agglomerates, along with agglomerate effective volume fraction (volume occupied by agglomerate) is investigated. Classic Smoluchowski theory is fundamentally limited for description of soft-agglomerate Brownian coagulation at high solids concentrations. In fact, these high concentrations affect little the primary particle diameter (or SSA) but dominate the soft-agglomerate diameter, structure, and volume fraction, leading to gelation consistent with experimental data. This indicates that restructuring and fragmentation should affect product particle characteristics during high-temperature synthesis of nanostructured particles at high concentrations in aerosol flow reactors.

20.
Int J Artif Organs ; 26(3): 235-40, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12703890

RESUMO

BACKGROUND: We demonstrate a method that includes colocalization studies to analyze cell suspensions after isolation and to characterize 3-dimensional grafts consisting of cells and matrix in vitro and in vivo. MATERIALS AND METHODS: Neonatal rat cardiomyocytes were labelled by CFDA-SE after harvest. Cells in the isolated cell suspension, the embodied cells in the seeded scaffolds were characterized measuring features such as viability and distribution of the cell types. RESULTS: Selective cell count revealed high yields of viable cardiomyocytes. After seeding cells in collagen matrix, viability of the cells decreased gradually in the time process in vitro. Histology of implanted bioartificial myocardial tissue detected viable cardiomyocytes within the graft. CONCLUSION: Using colocalization histology we could label and track cells within the bioartificial myocardial tissue graft in vitro and post implant and assess viability and distribution.


Assuntos
Fluoresceínas/farmacologia , Corantes Fluorescentes/farmacologia , Coração Artificial , Miócitos Cardíacos/metabolismo , Succinimidas/farmacologia , Engenharia Tecidual/métodos , Animais , Animais Recém-Nascidos , Órgãos Bioartificiais , Movimento Celular/fisiologia , Sobrevivência Celular/fisiologia , Ratos , Ratos Wistar
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