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1.
Artigo em Inglês | MEDLINE | ID: mdl-28544085

RESUMO

e-TC is an online intervention designed to address common psychosocial concerns of testicular cancer survivors. It aims to reduce anxiety, depression and fear of cancer recurrence by providing evidence-based information and psychological intervention. This paper details the development and pilot testing of e-TC. During pilot testing, 25 men (with varying psychological profiles) who had completed treatment for testicular cancer, 6 months to 5 years ago (which had not recurred), used e-TC over a 10-week period and provided quantitative and qualitative feedback on the feasibility and acceptability of the programme. Six men also completed a qualitative interview to provide detailed feedback on their experiences using e-TC. Fourteen men (56%) completed at least 80% of the programme. Participants reported a high level of satisfaction with the programme. Men's limited time was a barrier to programme use and completion, and participants suggested that men with a more recent diagnosis and a higher level of distress may be more likely to engage with the programme. e-TC appears to be a feasible and acceptable online intervention for survivors of testicular cancer. Findings from this study are currently being used to refine e-TC and guide the design of a larger efficacy study.


Assuntos
Ansiedade/terapia , Sobreviventes de Câncer/psicologia , Terapia Cognitivo-Comportamental/métodos , Depressão/terapia , Estresse Psicológico/terapia , Neoplasias Testiculares/psicologia , Adulto , Ansiedade/psicologia , Depressão/psicologia , Estudos de Viabilidade , Humanos , Internet , Masculino , Pessoa de Meia-Idade , Aceitação pelo Paciente de Cuidados de Saúde , Projetos Piloto , Estresse Psicológico/psicologia , Terapia Assistida por Computador/métodos
2.
Psychol Med ; 45(5): 965-76, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25229248

RESUMO

BACKGROUND: Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are two common childhood disorders that exhibit genetic and behavioural overlap and have abnormalities in similar brain systems, in particular in frontal and cerebellar regions. This study compared the two neurodevelopmental disorders to investigate shared and disorder-specific structural brain abnormalities. METHOD: Forty-four predominantly medication-naïve male adolescents with ADHD, 19 medication-naïve male adolescents with ASD and 33 age-matched healthy male controls were scanned using high-resolution T1-weighted volumetric imaging in a 3-T magnetic resonance imaging (MRI) scanner. Voxel-based morphometry (VBM) was used to test for group-level differences in structural grey matter (GM) and white matter (WM) volumes. RESULTS: There was a significant group difference in the GM of the right posterior cerebellum and left middle/superior temporal gyrus (MTG/STG). Post-hoc analyses revealed that this was due to ADHD boys having a significantly smaller right posterior cerebellar GM volume compared to healthy controls and ASD boys, who did not differ from each other. ASD boys had a larger left MTG/STG GM volume relative to healthy controls and at a more lenient threshold relative to ADHD boys. CONCLUSIONS: The study shows for the first time that the GM reduction in the cerebellum in ADHD is disorder specific relative to ASD whereas GM enlargement in the MTG/STG in ASD may be disorder specific relative to ADHD. This study is a first step towards elucidating disorder-specific structural biomarkers for these two related childhood disorders.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/patologia , Transtorno do Espectro Autista/patologia , Cerebelo/patologia , Substância Cinzenta/patologia , Lobo Temporal/patologia , Substância Branca/patologia , Adolescente , Estudos de Casos e Controles , Criança , Humanos , Masculino , Tamanho do Órgão
3.
Br J Cancer ; 111(1): 1-7, 2014 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-24892447

RESUMO

BACKGROUND: Decision aids may improve informed consent in clinical trial recruitment, but have not been evaluated in this context. This study investigated whether decision aids (DAs) can reduce decisional difficulties among women considering participation in the International Breast Cancer Intervention Study-II (IBIS-II) trial. METHODS: The IBIS-II trial investigated breast cancer prevention with anastrazole in two cohorts: women with increased risk (Prevention), and women treated for ductal carcinoma in situ (DCIS). Australia, New Zealand and United Kingdom participants were randomised to receive a DA (DA group) or standard trial consent materials (control group). Questionnaires were completed after deciding about participation in IBIS-II (post decision) and 3 months later (follow-up). RESULTS: Data from 112 Prevention and 34 DCIS participants were analysed post decision (73 DA; 73 control); 95 Prevention and 24 DCIS participants were analysed at follow-up (58 DA; 61 control). There was no effect on the primary outcome of decisional conflict. The DCIS-DA group had higher knowledge post decision, and the Prevention-DA group had lower decisional regret at follow-up. CONCLUSIONS: This was the first study to evaluate a DA in the clinical trial setting. The results suggest DAs can potentially increase knowledge and reduce decisional regret about clinical trial participation.


Assuntos
Neoplasias da Mama/prevenção & controle , Tomada de Decisões , Técnicas de Apoio para a Decisão , Participação do Paciente/psicologia , Ensaios Clínicos Controlados Aleatórios como Assunto/métodos , Ensaios Clínicos Controlados Aleatórios como Assunto/psicologia , Feminino , Humanos , Pessoa de Meia-Idade , Satisfação do Paciente , Inquéritos e Questionários , Resultado do Tratamento
4.
Psychol Med ; 44(3): 633-46, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23597077

RESUMO

BACKGROUND: The catecholamine reuptake inhibitors methylphenidate (MPH) and atomoxetine (ATX) are the most common treatments for attention deficit hyperactivity disorder (ADHD). This study compares the neurofunctional modulation and normalization effects of acute doses of MPH and ATX within medication-naive ADHD boys during working memory (WM). METHOD: A total of 20 medication-naive ADHD boys underwent functional magnetic resonance imaging during a parametric WM n-back task three times, under a single clinical dose of either MPH, ATX or placebo in a randomized, double-blind, placebo-controlled, cross-over design. To test for normalization effects, brain activations in ADHD under each drug condition were compared with that of 20 age-matched healthy control boys. RESULTS: Relative to healthy boys, ADHD boys under placebo showed impaired performance only under high WM load together with significant underactivation in the bilateral dorsolateral prefrontal cortex (DLPFC). Both drugs normalized the performance deficits relative to controls. ATX significantly enhanced right DLPFC activation relative to MPH within patients, and significantly normalized its underactivation relative to controls. MPH, by contrast, both relative to placebo and ATX, as well as relative to controls, upregulated the left inferior frontal cortex (IFC), but only during 2-back. Both drugs enhanced fronto-temporo-striatal activation in ADHD relative to control boys and deactivated the default-mode network, which were negatively associated with the reduced DLPFC activation and performance deficits, suggesting compensation effects. CONCLUSIONS: The study shows both shared and drug-specific effects. ATX upregulated and normalized right DLPFC underactivation, while MPH upregulated left IFC activation, suggesting drug-specific laterality effects on prefrontal regions mediating WM.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/tratamento farmacológico , Lobo Frontal/efeitos dos fármacos , Memória de Curto Prazo/efeitos dos fármacos , Metilfenidato/farmacologia , Inibidores da Captação de Neurotransmissores/farmacologia , Propilaminas/farmacologia , Adolescente , Análise de Variância , Cloridrato de Atomoxetina , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Gânglios da Base/efeitos dos fármacos , Gânglios da Base/fisiopatologia , Mapeamento Encefálico , Criança , Estudos Cross-Over , Método Duplo-Cego , Lobo Frontal/fisiopatologia , Lateralidade Funcional , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Metilfenidato/administração & dosagem , Metilfenidato/uso terapêutico , Testes Neuropsicológicos , Inibidores da Captação de Neurotransmissores/administração & dosagem , Inibidores da Captação de Neurotransmissores/uso terapêutico , Placebos , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/fisiopatologia , Propilaminas/administração & dosagem , Propilaminas/uso terapêutico
5.
Mol Psychiatry ; 18(2): 236-44, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22290121

RESUMO

Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are often comorbid and share behavioural-cognitive abnormalities in sustained attention. A key question is whether this shared cognitive phenotype is based on common or different underlying pathophysiologies. To elucidate this question, we compared 20 boys with ADHD to 20 age and IQ matched ASD and 20 healthy boys using functional magnetic resonance imaging (fMRI) during a parametrically modulated vigilance task with a progressively increasing load of sustained attention. ADHD and ASD boys had significantly reduced activation relative to controls in bilateral striato-thalamic regions, left dorsolateral prefrontal cortex (DLPFC) and superior parietal cortex. Both groups also displayed significantly increased precuneus activation relative to controls. Precuneus was negatively correlated with the DLPFC activation, and progressively more deactivated with increasing attention load in controls, but not patients, suggesting problems with deactivation of a task-related default mode network in both disorders. However, left DLPFC underactivation was significantly more pronounced in ADHD relative to ASD boys, which furthermore was associated with sustained performance measures that were only impaired in ADHD patients. ASD boys, on the other hand, had disorder-specific enhanced cerebellar activation relative to both ADHD and control boys, presumably reflecting compensation. The findings show that ADHD and ASD boys have both shared and disorder-specific abnormalities in brain function during sustained attention. Shared deficits were in fronto-striato-parietal activation and default mode suppression. Differences were a more severe DLPFC dysfunction in ADHD and a disorder-specific fronto-striato-cerebellar dysregulation in ASD.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/patologia , Atenção/fisiologia , Transtorno Autístico/patologia , Córtex Cerebral/patologia , Análise de Variância , Mapeamento Encefálico , Estudos de Casos e Controles , Córtex Cerebral/irrigação sanguínea , Criança , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Movimento/fisiologia , Testes Neuropsicológicos , Oxigênio/sangue , Estimulação Luminosa , Desempenho Psicomotor , Tempo de Reação/fisiologia , Inquéritos e Questionários
6.
J Med Econ ; 26(1): 430-440, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36892952

RESUMO

AIMS: To generate utility decrements for three attributes associated with catheterization for individuals with a spinal cord injury (SCI): the process of catheterization, the physical impact of urinary tract infections (UTIs) and worry associated with hospitalization. MATERIALS AND METHODS: Health state vignettes comprising various levels of the three attributes were developed. Two cohorts of respondents, corresponding to people with SCIs and a sample broadly representative of the UK population, were presented with nine vignettes (three vignettes for the mild, moderate and severe health states in addition to a random set of six vignettes). It was assumed no or a nominal decrement was associated with the mild health state. Utility decrements were derived from analysing the data obtained from the online time trade-off (TTO). A proportion of the SCI cohort (n = 57) also completed the EQ-5D-5L questionnaire. RESULTS: Utility decrements were generated using statistical models for the general population (n = 358), the SCI population (n = 48) and the two populations combined (merged model, n = 406). Results from the two cohorts showed minimal differences. For the merged model, SCI status was not statistically significant. All interaction terms, excluding SCI and the severe level of the physical attribute, were not statistically significant. Compared to the mild level, the greatest utility decrement calculated was the severe level of the emotional (worry) attribute (0.09, p < .001) for the SCI population. A significant decrement of 0.02 (p < .001) was calculated for the moderate level of the emotional attribute for all models. The mean utility score for those with SCI having completed the EQ-5D-5L was 0.371. LIMITATIONS: Modest sample size of respondents from the SCI population (n = 48). CONCLUSIONS: Worry associated with hospitalization had the greatest impact on patients' health-related quality of life (HRQoL). The catheterization process, such as the lubrication and repositioning of the catheter, also impacted on patients' HRQoL.


Assuntos
Traumatismos da Medula Espinal , Infecções Urinárias , Humanos , Qualidade de Vida/psicologia , Inquéritos e Questionários , Traumatismos da Medula Espinal/complicações , Cateterismo , Nível de Saúde
7.
Proc Biol Sci ; 279(1727): 293-8, 2012 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-21653588

RESUMO

Feeding arms carrying coelomic extensions of the theca are thought to be unique to crinoids among stemmed echinoderms. However, a new two-armed echinoderm from the earliest Middle Cambrian of Spain displays a highly unexpected morphology. X-ray microtomographic analysis of its arms shows they are polyplated in their proximal part with a dorsal series of uniserial elements enclosing a large coelomic lumen. Distally, the arm transforms into the more standard biserial structure of a blastozoan brachiole. Phylogenetic analysis demonstrates that this taxon lies basal to rhombiferans as sister-group to pleurocystitid and glyptocystitid blastozoans, drawing those clades deep into the Cambrian. We demonstrate that Cambrian echinoderms show surprising variability in the way their appendages are constructed, and that the appendages of at least some blastozoans arose as direct outgrowths of the body in much the same way as the arms of crinoids.


Assuntos
Equinodermos/anatomia & histologia , Animais , Evolução Biológica , Equinodermos/classificação , Equinodermos/fisiologia , Comportamento Alimentar , Filogenia
8.
Oper Dent ; 36(5): 460-6, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21859318

RESUMO

This randomized clinical study assessed efficacy in terms of color change and production of sensitivity after home whitening alone and home whitening supplemented with in-office bleaching. Thirty-six subjects (aged 19 to 58 years) were randomly assigned to one of three different treatment groups: (A) home whitening for two weeks, with 16% carbamide peroxide in custom-made trays; (B) home whitening for two weeks, with 16% carbamide peroxide in custom-made trays supplemented with in-office bleaching with 9% hydrogen peroxide (in the same trays); or (C) home whitening for two weeks, with 16% carbamide peroxide in custom-made trays supplemented with in-office bleaching with 27% hydrogen peroxide (in the same trays). The efficacy of tooth whitening was assessed by determining the color change associated with the six upper anterior teeth using a value-ordered shade guide. Sensitivity was self-assessed with the use of a visual analog scale (VAS). Tooth shade and sensitivity were assessed at the following points: pretreatment; immediately after the home whitening phase; immediately after the in-office phase (groups B and C); and one week post active treatment. At the one week follow-up visit, subjects in group A had a mean (SD) color change of 5.9 (1.83) (teeth were lighter) immediately after cessation of treatment (p<0.01). Subjects in groups B and C experienced a greater change in mean (SD) shade immediately following their respective in-office treatments of 5.1 (1.53) and 5.4 (1.55). However, within one week, the shade of these teeth regressed to a similar degree to that achieved by subjects treated in group A. Overall, no significant difference in shade change or sensitivity was produced between the three groups. Investigators concluded that the in-office element of combined whitening produced no significant difference in tooth color or sensitivity when compared with home whitening alone.


Assuntos
Consultórios Odontológicos , Sensibilidade da Dentina/etiologia , Autocuidado , Clareamento Dental/métodos , Adulto , Peróxido de Carbamida , Cor , Dente Canino/patologia , Sensibilidade da Dentina/classificação , Seguimentos , Humanos , Peróxido de Hidrogênio/administração & dosagem , Peróxido de Hidrogênio/uso terapêutico , Incisivo/patologia , Pessoa de Meia-Idade , Medição da Dor , Peróxidos/administração & dosagem , Peróxidos/uso terapêutico , Fatores de Tempo , Clareamento Dental/instrumentação , Clareadores Dentários/administração & dosagem , Clareadores Dentários/uso terapêutico , Resultado do Tratamento , Ureia/administração & dosagem , Ureia/análogos & derivados , Ureia/uso terapêutico , Adulto Jovem
9.
Ulster Med J ; 90(2): 70-76, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34276083

RESUMO

BACKGROUND: Dupilumab, a monoclonal antibody against interleukin (IL)-4 receptor alpha that inhibits IL-4/IL-13 signalling is indicated in dermatology for the treatment of moderate-to-severe atopic dermatitis (AD) in adult and adolescent patients 12 years and older and severe AD in children 6-11 years, who are candidates for systemic therapy. Dupilumab received Early Access to Medicines Scheme (EAMS) approval for adults in March 2017. OBJECTIVES: The purpose of this study was to assess the efficacy outcomes of treatment with dupilumab in EAMS. METHODS: A retrospective analysis of adult patients enrolled in the dupilumab EAMS in the UK. Scores were assessed at baseline and follow up, including the Eczema Area and Severity Index (EASI), Investigator's Global Assessment Score (IGA) and Dermatology Life Quality Index (DLQI). RESULTS: Data were available for 57 adult patients treated with dupilumab for at least 12 weeks; 73.6% of patients had received prior treatment with 3 or 4 immunosuppressants. Baseline scores for the EASI and DLQI were 27.93 (standard deviation, SD 13.09) and 18.26 (SD 6.18) respectively. AD severity scores showed statistically significant improvement at week 16±4 weeks (p <0.001 for all). The mean change in EASI was 14.13 points with 66.7% and 36.7% achieving a 50% (EASI-50) and 75% (EASI-75) improvement in EASI, respectively at 16+/- 4 weeks. IGA scores improved by at least two categories for 75% patients. DLQI scores decreased by a mean of 9.0 points, with 80% patients demonstrating a MCID 4-point improvement. For 85% patients, clinicians rated the treatment response as being either 'better' (19%) or 'much better' (65%). CONCLUSIONS: Dupilumab is associated with a significant and clinically relevant improvements in AD as measured by patient- and physician-reported outcome measures. Importantly, the clinical efficacy, despite the refractory disease of this EAMS cohort, is comparable to that previously reported in clinical trials.


Assuntos
Dermatite Atópica , Eczema , Adolescente , Adulto , Anticorpos Monoclonais Humanizados , Criança , Dermatite Atópica/tratamento farmacológico , Método Duplo-Cego , Acessibilidade aos Serviços de Saúde , Humanos , Injeções Subcutâneas , Estudos Retrospectivos , Índice de Gravidade de Doença , Resultado do Tratamento , Reino Unido
10.
Genome ; 53(11): 992-1001, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21076515

RESUMO

In this paper multiplicative mixed models have been used for the analysis of multi-environment trial (MET) data for canola oil and grain yield. Information on pedigrees has been included to allow for the modelling of additive and nonadditive genetic effects. The MET data set included a total of 19 trials (synonymous with sites or environments), which were sown across southern Australia in 2007 and 2008. Each trial was designed as a p-rep design using DiGGeR with the default prespecified spatial model. Lines in their first year of testing were unreplicated, whereas there were two or three replications of advanced lines or varieties. Pedigree information on a total of 578 entries was available, and there were 69 entries that had unknown pedigrees. The degree of inbreeding varied from 0 (55 entries) to nearly fully inbred (337 entries). Subsamples of 2 g harvested grain were taken from each plot for determination of seed oil percentage by near infrared reflectance spectroscopy. The MET analysis for both yield and oil modelled genetic effects in different trials using factor analytic models and the residual plot effects for each trial were modelled using spatial techniques. Models in which pedigree information was included provided significantly better fits to both yield and oil data.


Assuntos
Cruzamento , Ácidos Graxos Monoinsaturados/análise , Modelos Genéticos , Óleos de Plantas/análise , Cruzamentos Genéticos , Ácidos Graxos Monoinsaturados/química , Genótipo , Modelos Estatísticos , Óleos de Plantas/química , Óleo de Brassica napus , Sementes/química
11.
Genome ; 53(11): 1002-16, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21076516

RESUMO

Exploring and exploiting variety by environment (V × E) interaction is one of the major challenges facing plant breeders. In paper I of this series, we presented an approach to modelling V × E interaction in the analysis of complex multi-environment trials using factor analytic models. In this paper, we develop a range of statistical tools which explore V × E interaction in this context. These tools include graphical displays such as heat-maps of genetic correlation matrices as well as so-called E-scaled uniplots that are a more informative alternative to the classical biplot for large plant breeding multi-environment trials. We also present a new approach to prediction for multi-environment trials that include pedigree information. This approach allows meaningful selection indices to be formed either for potential new varieties or potential parents.


Assuntos
Cruzamento , Meio Ambiente , Ácidos Graxos Monoinsaturados/análise , Óleos de Plantas/análise , Plantas/genética , Análise Fatorial , Modelos Genéticos , Modelos Estatísticos , Óleo de Brassica napus
12.
Science ; 268(5208): 284-6, 1995 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-7716520

RESUMO

African trypanosomes cause disease in humans and animals. Trypanosoma brucei brucei affects cattle but not humans because of its sensitivity to a subclass of human high density lipoproteins (HDLs) called trypanosome lytic factor (TLF). TLF contains two apolipoproteins that are sufficient to cause lysis of T. b. brucei in vitro. These proteins were identified as the human haptoglobin-related protein and paraoxonase-arylesterase. An antibody to haptoglobin inhibited TLF activity. TLF was shown to exhibit peroxidase activity and to be inhibited by catalase. These results suggest that TLF kills trypanosomes by oxidative damage initiated by its peroxidase activity.


Assuntos
Antígenos de Neoplasias , Proteínas Sanguíneas/fisiologia , Haptoglobinas , Peroxidases/metabolismo , Trypanosoma brucei brucei/fisiologia , Sequência de Aminoácidos , Animais , Arildialquilfosfatase , Proteínas Sanguíneas/química , Hidrolases de Éster Carboxílico/química , Catalase/metabolismo , Endocitose , Esterases/química , Hemoglobinas/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Membranas Intracelulares , Peroxidação de Lipídeos , Lipoproteínas LDL/química , Lisossomos/metabolismo , Dados de Sequência Molecular , Oxirredução , Trypanosoma brucei brucei/metabolismo
13.
Science ; 228(4696): 175-7, 1985 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-3975636

RESUMO

Computerized pattern recognition techniques can be applied to the study of complex chemical communication systems. Analysis of high resolution gas chromatographic concentration patterns of the major volatile components of the scent marks of a South American primate, Saguinus fuscicollis, demonstrates that the concentration patterns can be used to predict the gender and subspecies of unknown donors.


Assuntos
Computadores , Reconhecimento Automatizado de Padrão , Feromônios/fisiologia , Atrativos Sexuais/fisiologia , Animais , Fenômenos Químicos , Química , Cromatografia Gasosa , Feminino , Masculino , Saguinus/fisiologia , Glândulas Odoríferas/fisiologia , Relação Estrutura-Atividade
14.
Science ; 260(5106): 323-6, 1993 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-17838247

RESUMO

Monolayer Langmuir-Blodgett films of a discotic mesogen have been studied with atomic force microscopy (AFM). These measurements confirm the "edge on" arrangement for the disk-shaped molecules suggested by surface pressure-area isotherms and show that the molecules form columns that are separated by 17.7 angstroms +/- 10 percent. Column alignment is found to be predominantly along the film deposition direction, with an angular spread of 35 degrees . The AFM images also show that the mean disk separation within the columns is 5.1 +/- 1.3 angstroms, in good agreement with x-ray diffraction (XRD) results. Roomtemperature XRD measurements on bulk samples of the same material indicate a disordered-hexagonal liquid crystalline mesophase, with a column-to-column spacing of 19.9 +/- 0.2 angstroms.

15.
Science ; 264(5155): 77-9, 1994 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-17778138

RESUMO

Thin films of disk-shaped molecules are expected to display anisotropic optical and transport properties, leading to applications in optical display or sensor technologies. Bilayer Langmuir-Blodgett films of monomeric triphenylene mesogens have been studied by atomic force microscopy. The triphenylene cores of the constituent molecules tend to promote the formation of columnar structures in the plane of the substrate and along the direction of deposition of the film. Atomic force microscopy images of bilayer Langmuir-Blodgett films revealed two types of structure, one corresponding to an aligned columnar structure and the other to an unusual square lattice, which may result from the superposition of columnar structures in adjacent layers that intersect at near right angles. Annealing such bilayers near the melting point of the bulk compound improved the structural ordering by reducing the angular spread of orientations associated with the well-developed columnar structure in some areas and by producing a more distinct square lattice in other areas of the sample.

16.
Science ; 254(5031): 545-8, 1991 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-17806970

RESUMO

Powder x-ray diffraction at 300 K on equilibrated samples of several nominal compositions chi in Rb(chi)C(60) is reported. In addition to the face-centered cubic (fcc) (chi = 3, superconducting), body-centered tetragonal (chi = 4), and body-centered cubic (bcc) (chi = 6) stoichiometric phases, direct evidence for a dilute fcc doped phase, 0 x c

17.
Science ; 252(5010): 1288-90, 1991 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-17842953

RESUMO

Room-temperature powder x-ray diffraction profiles have been obtained at hydrostatic pressures P = 0 and 1.2 gigapascals on the solid phase of cubic C(60) ("fullerite"). Within experimental error, the linear compressibility d(ln a)/dP is the same as the interlayer compressibility d(ln c)/dP of hexagonal graphite, consistent with van der Waals intermolecular bonding. The volume compressibility -d(ln V)/dP is 7.0 +/- 1 x 10(-12) square centimeter per dyne, 3 and 40 times the values for graphite and diamond, respectively.

18.
Science ; 265(5169): 234-7, 1994 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-8023141

RESUMO

Monoclonal antibodies, induced with a phosphonate diester hapten, catalyzed the coupling of p-nitrophenyl esters of N-acetyl valine, leucine, and phenylalanine with tryptophan amide to form the corresponding dipeptides. All possible stereoisomeric combinations of the ester and amide substrates were coupled at comparable rates. The antibodies did not catalyze the hydrolysis of the dipeptide product nor hydrolysis or racemization of the activated esters. The yields of the dipeptides ranged from 44 to 94 percent. The antibodies were capable of multiple turnovers at rates that exceeded the rate of spontaneous ester hydrolysis. This achievement suggests routes toward creating a small number of antibody catalysts for polypeptide syntheses.


Assuntos
Anticorpos Catalíticos/metabolismo , Anticorpos Monoclonais/metabolismo , Dipeptídeos/biossíntese , Sítios de Ligação de Anticorpos , Ésteres , Haptenos , Cinética , Leucina/análogos & derivados , Leucina/metabolismo , Conformação Molecular , Fenilalanina/análogos & derivados , Fenilalanina/metabolismo , Estereoisomerismo , Triptofano/análogos & derivados , Triptofano/metabolismo , Valina/análogos & derivados , Valina/metabolismo
19.
Science ; 255(5046): 833-5, 1992 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-17756430

RESUMO

X-ray diffraction and diamond anvil techniques were used to measure the isothermal compressibility of K(3)C(60) and Rb(3)C(60), the superconducting, binary alkali-metal intercalation compounds of solid buckminsterfullerene. These results, combined with the pressure dependence of the superconducting onset temperature T(c) measured by other groups, establish a universal first-order relation between T(c) and the lattice parameter a over a broad range, between 13.9 and 14.5 angstroms. A small secondorder intercalate-specific effect was observed that appears to rule out the participation of intercalate-fullerene optic modes in the pairing interaction.

20.
Science ; 254(5036): 1350-3, 1991 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-17773604

RESUMO

The high-temperature structure of solvent-free C(70) has been determined with high-resolution x-ray powder difraction and electron microscopy. Samples crystallized from solution form hexagonal close-packed crystals that retain an appreciable amount of residual toluene, even after prolonged heating. Samples prepared by sublimation, which contain no detectable solvent, are primarily face-centered cubic with some admixture of a hexagonal phase. The relative volume of the hexagonal phase can be further reduced by annealing. The structures of both phases are described by a model of complete orientational disorder. The cubic phase contains an appreciable density of stacking faults along the [111] direction.

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