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1.
Artigo em Inglês | MEDLINE | ID: mdl-34148778

RESUMO

The awareness that cervical intra-epithelial neoplasia (CIN) treatment increases the risk of preterm birth has led to major changes in clinical practice. Women with CIN have a higher baseline risk of prematurity but local treatment further increases this risk. The risk further increases with increasing cone length and multiplies for repeat excisions; it is unclear whether small cones confer any additional risk to CIN alone. There is no evidence to suggest that fertility is affected by local treatment, although this increases the risk of mid-trimester loss. Caution should prevail when deciding to treat women with CIN of reproductive age. If treatment is offered, this should be conducted effectively to optimise the clearance of disease and minimise the risk of recurrence. Colposcopists should alert women undergoing treatment that this may increase the risk of preterm birth and that they may be offered interventions when pregnant. The cone length should be clearly documented and used as a risk stratifier.


Assuntos
Nascimento Prematuro , Displasia do Colo do Útero , Neoplasias do Colo do Útero , Feminino , Humanos , Recém-Nascido , Morbidade , Recidiva Local de Neoplasia , Gravidez , Neoplasias do Colo do Útero/cirurgia , Displasia do Colo do Útero/cirurgia
2.
Eur J Obstet Gynecol Reprod Biol ; 256: 57-62, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33171418

RESUMO

This European consensus statement on essential colposcopy provides standards for the general colposcopist seeing women referred for colposcopy with an abnormal cervical screening test (including cytology and HPV tests) or with a clinically suspicious cervix. The article gives guidance regarding the aims and conduct of colposcopy. Recommendations are provided on colposcopy technique, the management of common colposcopy issues, treatment and follow-up of after treatment of CIN or early stage cervical. Colposcopists should make an informed decision on the management of each individual that is referred and organize appropriate follow-up. Cervical cancer is still a major health issue and the quality of care can only improve if there is a structured guidance for women with an abnormal smear or suspicious cervix.


Assuntos
Infecções por Papillomavirus , Displasia do Colo do Útero , Neoplasias do Colo do Útero , Colposcopia , Consenso , Detecção Precoce de Câncer , Feminino , Humanos , Papillomaviridae , Infecções por Papillomavirus/diagnóstico , Gravidez , Neoplasias do Colo do Útero/diagnóstico , Esfregaço Vaginal , Displasia do Colo do Útero/diagnóstico
3.
Sci Rep ; 10(1): 7521, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32372006

RESUMO

Plant growth promoting rhizobacteria can improve plant health by providing enhanced nutrition, disease suppression and abiotic stress resistance, and have potential to contribute to sustainable agriculture. We have developed a sphagnum peat-based compost platform for investigating plant-microbe interactions. The chemical, physical and biological status of the system can be manipulated to understand the relative importance of these factors for plant health, demonstrated using three case studies: 1. Nutrient depleted compost retained its structure, but plants grown in this medium were severely stunted in growth due to removal of essential soluble nutrients - particularly, nitrogen, phosphorus and potassium. Compost nutrient status was replenished with the addition of selected soluble nutrients, validated by plant biomass; 2. When comparing milled and unmilled compost, we found nutrient status to be more important than matrix structure for plant growth; 3. In compost deficient in soluble P, supplemented with an insoluble inorganic form of P (Ca3(PO4)2), application of a phosphate solubilising Pseudomonas strain to plant roots provides a significant growth boost when compared with a Pseudomonas strain incapable of solubilising Ca3(PO4)2. Our findings show that the compost system can be manipulated to impose biotic and abiotic stresses for testing how microbial inoculants influence plant growth.


Assuntos
Nitrogênio/análise , Fósforo/análise , Plantas/microbiologia , Potássio/análise , Pseudomonas/fisiologia , Agricultura , Biodegradação Ambiental , Biomassa , Fosfatos de Cálcio/química , Compostagem , Produtos Agrícolas/microbiologia , Concentração de Íons de Hidrogênio , Fosfatos , Desenvolvimento Vegetal , Raízes de Plantas/crescimento & desenvolvimento , RNA Ribossômico 16S/metabolismo , Solo/química , Microbiologia do Solo , Triticum
4.
Best Pract Res Clin Obstet Gynaecol ; 65: 109-124, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32284298

RESUMO

Prophylactic vaccines have been found to be highly effective in preventing infection and pre-invasive and invasive cervical, vulvovaginal and anal disease caused by the vaccine types. HPV vaccines contain virus-like particles that lack the viral genome and produce high titres of neutralising antibodies. Although the vaccines are highly effective in preventing infections, they do not enhance clearance of existing infections. Vaccination programmes target prepubertal girls and boys prior to sexual debut as efficacy is highest in HPV naïve individuals. School-based programmes achieve higher coverage, although implementation is country specific. Vaccination of older women may offer some protection and acceleration of impact, although this may not be cost-effective. HPV-based screening will continue for vaccinated cohorts, although intervals may increase.


Assuntos
Programas de Rastreamento/métodos , Infecções por Papillomavirus/prevenção & controle , Vacinas contra Papillomavirus/administração & dosagem , Neoplasias do Colo do Útero/prevenção & controle , Vacinação , Idoso , Análise Custo-Benefício , Feminino , Humanos , Masculino , Papillomaviridae/imunologia , Infecções por Papillomavirus/complicações , Neoplasias do Colo do Útero/virologia
5.
Equine Vet J ; 52(1): 46-51, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30900769

RESUMO

BACKGROUND: Reliable and validated biomarkers for osteoarthritis (OA) are currently lacking. OBJECTIVES: To develop an accurate and minimally invasive method to assess OA-affected horses and provide potential spectral markers indicative of disease. STUDY DESIGN: Observational, cross-sectional study. METHODS: Our cohort consisted of 15 horses with OA and 48 without clinical signs of the disease, which were used as controls. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy was used to investigate serum samples (50 µL) collected from these horses. Spectral processing and multivariate analysis revealed differences and similarities, allowing for detection of spectral biomarkers that discriminated between the two cohorts. A supervised classification algorithm, namely principal component analysis coupled with quadratic discriminant analysis (PCA-QDA), was applied to evaluate the diagnostic accuracy. RESULTS: Segregation between the two different cohorts, OA-affected and controls, was achieved with 100% sensitivity and specificity. The six most discriminatory peaks were attributed to proteins and lipids. Four of the spectral peaks were elevated in OA horses, which could be potentially due to an increase in lipids, protein expression levels and collagen, all of which have been previously reported in OA. Two peaks were found decreased and were tentatively assigned to the reduction of proteoglycan content that is observed during OA. MAIN LIMITATIONS: The control group had a wide range of ages and breeds. Presymptomatic OA cases were not included. Therefore, it remains unknown whether this test could also be used as an early diagnostic tool. CONCLUSIONS: This spectrochemical approach could provide an accurate and cost-effective blood test, facilitating point-of-care diagnosis of equine OA.


Assuntos
Doenças dos Cavalos/diagnóstico , Osteoartrite/veterinária , Espectroscopia de Infravermelho com Transformada de Fourier/veterinária , Animais , Estudos Transversais , Doenças dos Cavalos/sangue , Cavalos , Osteoartrite/sangue , Osteoartrite/diagnóstico , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
7.
Eur J Oncol Nurs ; 34: 61-67, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29784140

RESUMO

PURPOSE: Endometrial cancer is the sixth most common female cancer worldwide. There is little evidence that routine hospital surveillance increases survival or decreases morbidity following treatment. Gynaecology Oncology clinical nurse specialists (CNSs) are ideally placed to provide the care, information and support to enable women with a gynaecological cancer to self-manage and live well. A multi-centre randomised controlled trial (RCT) compared hospital follow-up (HFU) with telephone follow-up (TFU) by CNSs. The structured telephone intervention focused on information provision to meet patients psychosocial and information needs. This study aimed to explore the views of women who had received TFU and the CNS's who had delivered the service. METHOD: A qualitative study to complement the RCT using semi-structured interviews was conducted. Twenty-five patients were randomly selected from participants in the TFU arm stratified by study site. Seven CNSs were interviewed. RESULTS: Patient and CNS regarded TFU positively; Three themes emerged from the patient interviews; Convenient Care, Discrete Personalised Care, Confidence and Reassurance. Themes arising from the CNS interviews were Patient Centred Care, Holistic Care and, Confidence and Skills. Patients found that TFU with CNS's was convenient and enabled discussion of issues and information provision at time-points relevant to them. The CNS's found the structured format of TFU enabled them to utilise their skills and knowledge to identify and meet patients holistic needs. CONCLUSIONS: Alternative models of care such as TFU provided by CNSs provides the care, information and support to enable women treated for endometrial cancer to self-manage and live well.


Assuntos
Neoplasias do Endométrio/terapia , Seguimentos , Neoplasias dos Genitais Femininos/terapia , Enfermeiros Clínicos/psicologia , Satisfação do Paciente/estatística & dados numéricos , Telemedicina/métodos , Telefone , Idoso , Idoso de 80 Anos ou mais , Atitude do Pessoal de Saúde , Feminino , Humanos , Pessoa de Meia-Idade , Pesquisa Qualitativa , Reino Unido
8.
Lett Appl Microbiol ; 66(1): 14-18, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29117429

RESUMO

Metagenomics and metatranscriptomics provide insights into biological processes in complex substrates such as soil, but linking the presence and expression of genes with functions can be difficult. Here, we obtain traditional most probable number estimates (MPN) of Rhizobium abundance in soil as a form of sample validation. Our work shows that in the Highfield experiment at Rothamsted, which has three contrasting conditions (>50 years continual bare fallow, wheat and grassland), MPN based on host plant nodulation assays corroborate metagenomic and metatranscriptomic estimates for Rhizobium leguminosarum sv. trifolii abundance. This validation is important to legitimize soil metagenomics and metatranscriptomics for the study of complex relationships between gene function and phylogeny. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has demonstrated for the first time a functional assay validation of metagenomic and metatranscriptomic datasets by utilizing the clover and Rhizobium leguminosarum sv. trifolii mutualism. The results show that the Most Probable Number results corroborate the results of the 'omics approaches and gives confidence to the study of other biological systems where such a cross-check is not available.


Assuntos
Bactérias/isolamento & purificação , Metagenômica/métodos , Rhizobium leguminosarum/genética , Microbiologia do Solo , Bactérias/classificação , Bactérias/genética , Medicago/crescimento & desenvolvimento , Medicago/microbiologia , Filogenia , Rhizobium/genética , Rhizobium/crescimento & desenvolvimento , Rhizobium/isolamento & purificação , Rhizobium leguminosarum/crescimento & desenvolvimento , Rhizobium leguminosarum/isolamento & purificação
10.
Eur J Obstet Gynecol Reprod Biol ; 210: 376-380, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28157644

RESUMO

After completing treatment, most patients follow a pre-determined schedule of regular hospital outpatient appointments, which includes clinical examinations, consultations and routine tests. After several years of surveillance, patients are transferred back to primary care. However, there is limited evidence to support the effectiveness and efficiency of this approach. This paper examines the current rationale and evidence base for hospital-based follow-up after treatment for gynaecological cancer. We investigate what alternative models of care have been formally evaluated and what research is currently in progress in Europe, in order to make tentative recommendations for a model of follow-up. The evidence base for traditional hospital based follow-up is limited. Alternative models have been reported for other cancer types but there are few evaluations of alternative approaches for gynaecological cancers. We identified five ongoing European studies; four were focused on endometrial cancer patients and one feasibility study included all gynaecological cancers. Only one study had reached the reporting stage. Alternative models included nurse-led telephone follow-up and comparisons of more intensive versus less intensive regimes. Outcomes included survival, quality of life, psychological morbidity, patient satisfaction and cost effectiveness of service. More work is needed on alternative strategies for all gynaecological cancer types. New models will be likely to include risk stratification with early discharge from secondary care for early stage disease with fast track access to specialist services for suspected cancer recurrence or other problems.


Assuntos
Assistência ao Convalescente/normas , Neoplasias dos Genitais Femininos , Oncologia/normas , Assistência ao Convalescente/economia , Feminino , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto
11.
BJOG ; 124(1): 150-160, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27062690

RESUMO

OBJECTIVE: To evaluate the effectiveness of nurse-led telephone follow-up (TFU) for patients with stage-I endometrial cancer. DESIGN: Multicentre, randomised, non-inferiority trial. SETTING: Five centres in the North West of England. SAMPLE: A cohort of 259 women treated for stage-I endometrial cancer attending hospital outpatient clinics for routine follow-up. METHODS: Participants were randomly allocated to receive traditional hospital based follow-up (HFU) or nurse-led TFU. MAIN OUTCOME MEASURES: Primary outcomes were psychological morbidity (State Trait Anxiety Inventory, STAI-S) and patient satisfaction with the information provided. Secondary outcomes included patient satisfaction with service, quality of life, and time to detection of recurrence. RESULTS: The STAI-S scores post-randomisation were similar between groups [mean (SD): TFU 33.0 (11.0); HFU 35.5 (13.0)]. The estimated between-group difference in STAI-S was 0.7 (95% confidence interval, 95% CI -1.9 to 3.3); the confidence interval lies above the non-inferiority limit (-3.5), indicating the non-inferiority of TFU. There was no significant difference between groups in reported satisfaction with information (odds ratio, OR 0.9; 95% CI 0.4-2.1; P = 0.83). Women in the HFU group were more likely to report being kept waiting for their appointment (P = 0.001), that they did not need any information (P = 0.003), and were less likely to report that the nurse knew about their particular case and situation (P = 0.005). CONCLUSIONS: The TFU provides an effective alternative to HFU for patients with stage-I endometrial cancer, with no reported physical or psychological detriment. Patient satisfaction with information was high, with similar levels between groups. TWEETABLE ABSTRACT: ENDCAT trial shows effectiveness of nurse-led telephone follow-up for patients with stage-I endometrial cancer.


Assuntos
Neoplasias do Endométrio/enfermagem , Papel do Profissional de Enfermagem , Ambulatório Hospitalar , Pacientes Ambulatoriais , Satisfação do Paciente , Qualidade de Vida , Telefone , Neoplasias do Endométrio/epidemiologia , Inglaterra/epidemiologia , Feminino , Seguimentos , Humanos , Estadiamento de Neoplasias , Pacientes Ambulatoriais/estatística & dados numéricos , Telefone/estatística & dados numéricos , Recursos Humanos
12.
Mol Ecol ; 25(9): 1925-43, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26928748

RESUMO

Colonization events, range expansions and species invasions leave genetic signatures in the genomes of invasive organisms and produce intricate special patterns. Predictions have been made as to how those patterns arise, but only very rarely, genetic processes can be monitored in real time during range expansions. In an attempt to change that, we track a very recently established invasive population of a fish species, the bighead goby Ponticola kessleri, with high temporal and spatial resolution through 2 years to identify patterns over time. We then compare Swiss and German samples of bighead goby along the river Rhine using microsatellites, mitochondrial D-loop sequences and geometric morphometrics to investigate geographic patterns. We detect weak temporal and strong geographic patterns in the data, which are inconsistent with isolation by distance and indicate long range transport. In search of an explanation for our observations, we analyse the vector properties and travel patterns of commercial vessels on the river Rhine. We present evidence that freshwater cargo ships and tankers are plausible vectors for larvae of invasive goby species. We also present indications that cargo ships and tankers act as differential vectors for this species. In summary, we present genetic data at unique temporal resolution from a vertebrate invasion front and substantiate the paramount role of commercial shipping in freshwater fish translocations.


Assuntos
Genética Populacional , Espécies Introduzidas , Perciformes/genética , Navios , Distribuição Animal , Animais , DNA Mitocondrial/genética , Alemanha , Haplótipos , Repetições de Microssatélites , Fenótipo , Rios , Análise de Sequência de DNA , Suíça
13.
Br J Cancer ; 114(6): 688-96, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26930451

RESUMO

BACKGROUND: Endometrial cancer (EC) is a hormone-driven disease, and androgen receptor (AR) expression in high-grade EC (HGEC) and metastatic EC has not yet been described. METHODS: The expression pattern and prognostic value of AR in relation to oestrogen (ERα and ERß) and progesterone (PR) receptors, and the proliferation marker Ki67 in all EC subtypes (n = 85) were compared with that of healthy and hyperplastic endometrium, using immunohistochemisty and qPCR. RESULTS: Compared with proliferative endometrium, postmenopausal endometrtial epithelium showed significantly higher expression of AR (P < 0.001) and ERα (P = 0.035), which persisted in hyperplastic epithelium and in low-grade EC (LGEC). High-grade EC showed a significant loss of AR (P < 0.0001), PR (P < 0.0001) and ERß (P < 0.035) compared with LGEC, whilst maintaining weak to moderate ERα. Unlike PR, AR expression in metastatic lesions was significantly (P = 0.039) higher than that in primary tumours. Androgen receptor expression correlated with favourable clinicopathological features and a lower proliferation index. Loss of AR, with/without the loss of PR was associated with a significantly lower disease-free survival (P < 0.0001, P < 0.0001, respectively). CONCLUSIONS: Postmenopausal endometrial epithelium acquires AR whilst preserving other steroid hormone receptors. Loss of AR, PR with retention of ERα and ERß may promote the unrestrained growth of HGEC. Androgen receptor may therefore be a clinically relevant prognostic indicator and a potential therapeutic target in EC.


Assuntos
Neoplasias do Endométrio/metabolismo , Endométrio/metabolismo , Receptores Androgênicos/biossíntese , Adulto , Idoso , Estudos de Casos e Controles , Neoplasias do Endométrio/patologia , Endométrio/patologia , Epitélio/metabolismo , Epitélio/patologia , Receptor alfa de Estrogênio/biossíntese , Receptor beta de Estrogênio/biossíntese , Feminino , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Pós-Menopausa/metabolismo , Receptores de Progesterona/biossíntese
16.
Environ Microbiol ; 17(11): 4764-78, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26337499

RESUMO

Manipulation of the soil microbiota associated with crop plants has huge promise for the control of crop pathogens. However, to fully realize this potential we need a better understanding of the relationship between the soil environment and the genes and phenotypes that enable microbes to colonize plants and contribute to biocontrol. A recent 2 years of investigation into the effect of wheat variety on second year crop yield in the context of take-all fungal infection presented the opportunity to examine soil microbiomes under closely defined field conditions. Amplicon sequencing of second year soil samples showed that Pseudomonas spp. were particularly affected by the wheat cultivar grown in year one. Consequently, 318 rhizosphere-associated Pseudomonas fluorescens strains were isolated and characterized across a variety of genetic and phenotypic traits. Again, the wheat variety grown in the first year of the study was shown to exert considerable selective pressure on both the extent and nature of Pseudomonas genomic diversity. Furthermore, multiple significant correlations were identified within the phenotypic/genetic structure of the Pseudomonas population, and between individual genotypes and the external wheat field environment. The approach outlined here has considerable future potential for our understanding of plant-microbe interactions, and for the broader analysis of complex microbial communities.


Assuntos
Variação Genética/genética , Microbiota/genética , Raízes de Plantas/microbiologia , Pseudomonas fluorescens/genética , Microbiologia do Solo , Triticum/microbiologia , Sequência de Bases , Produtos Agrícolas/microbiologia , DNA Bacteriano/genética , Genômica , Genótipo , Doenças das Plantas/microbiologia , Pseudomonas fluorescens/classificação , Pseudomonas fluorescens/isolamento & purificação , Rizosfera , Análise de Sequência de DNA , Triticum/classificação
17.
Soil Biol Biochem ; 88: 257-267, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26339106

RESUMO

An emerging paradigm in soil science suggests microbes can perform 'N mining' from recalcitrant soil organic matter (SOM) in conditions of low N availability. However, this requires the production of extracellular structures rich in N (including enzymes and structural components) and thus defies stoichiometric expectation. We set out to extract newly synthesised peptides from the extracellular matrix in soil and compare the amino acid (AA) profiles, N incorporation and AA dynamics in response to labile inputs of contrasting C/N ratio. Glycerol was added both with and without an inorganic source of N (10% 15N labelled NH4NO3) to a soil already containing a large pool of refractory SOM and incubated for 10 days. The resulting total soil peptide (TSP) and extracellular pools were compared using colorimetric methods, gas chromatography, and isotope ratio mass spectrometry. N isotope compositions showed that the extracellular polymeric substance (EPS) contained a greater proportion of products formed de novo than did TSP, with hydrophobic EPS-AAs (leucine, isoleucine, phenylalanine, hydroxyproline and tyrosine) deriving substantially more N from the inorganic source provided. Quantitative comparison between extracts showed that the EPS contained greater relative proportions of alanine, glycine, proline, phenylalanine and tyrosine. The greatest increases in EPS-peptide and EPS-polysaccharide concentrations occurred at the highest C/N ratios. All EPS-AAs responded similarly to treatment whereas the responses of TSP were more complex. The results suggest that extracellular investment of N (as EPS peptides) is a microbial survival mechanism in conditions of low N/high C which, from an evolutionary perspective, must ultimately lead to the tendency for increased N returns to the microbial biomass. A conceptual model is proposed that describes the dynamics of the extracellular matrix in response to the C/N ratio of labile inputs.

18.
Am J Infect Control ; 43(10): 1053-60, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26138999

RESUMO

BACKGROUND: Exposure to patients with varicella or herpes zoster causes considerable disruption to a health care facility's operations and has a significant health and economic impact. However, practices related to screening for immunity and immunization of health care personnel (HCP) for varicella vary widely. METHODS: A decision tree model was built to evaluate the cost-effectiveness of 8 different strategies of screening and vaccinating HCP for varicella. The outcomes are presented as probability of acquiring varicella, economic impact of varicella per employee per year, and cost to prevent additional cases of varicella. Monte Carlo simulations and 1-way sensitivity analyses were performed to address the uncertainties inherent to the model. Alternative epidemiologic and technologic scenarios were also analyzed. RESULTS: Performing a clinical screening followed by serologic testing of HCP with negative history diminished the cost impact of varicella by >99% compared with not having a program. Vaccinating HCP with negative screen cost approximately $50,000 per case of varicella prevented at the current level of U.S. population immunity, but was projected to be cost-saving at 92% or lower immunity prevalence. Improving vaccine acceptance rates and using highly sensitive assays also optimize cost-effectiveness. CONCLUSION: Strategies relying on screening and vaccinating HCP for varicella on employment were shown to be cost-effective for health care facilities and are consistent with current national guidelines for varicella prevention.


Assuntos
Anticorpos Antivirais/sangue , Vacina contra Varicela/economia , Varicela/imunologia , Pessoal de Saúde , Programas de Rastreamento/economia , Programas de Rastreamento/métodos , Vacinação/economia , Vacina contra Varicela/administração & dosagem , Análise Custo-Benefício , Infecção Hospitalar/prevenção & controle , Humanos , Modelos Estatísticos , Doenças Profissionais/prevenção & controle , Vacinação/métodos
19.
Nat Commun ; 6: 7266, 2015 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-26041257

RESUMO

Screw dislocations play an important role in materials' mechanical, electrical and optical properties. However, imaging the atomic displacements in screw dislocations remains challenging. Although advanced electron microscopy techniques have allowed atomic-scale characterization of edge dislocations from the conventional end-on view, for screw dislocations, the atoms are predominantly displaced parallel to the dislocation line, and therefore the screw displacements are parallel to the electron beam and become invisible when viewed end-on. Here we show that screw displacements can be imaged directly with the dislocation lying in a plane transverse to the electron beam by optical sectioning using annular dark field imaging in a scanning transmission electron microscope. Applying this technique to a mixed [a+c] dislocation in GaN allows direct imaging of a screw dissociation with a 1.65-nm dissociation distance, thereby demonstrating a new method for characterizing dislocation core structures.

20.
Phys Rev Lett ; 113(13): 135503, 2014 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-25302902

RESUMO

We demonstrate that the aberration-corrected scanning transmission electron microscope has a sufficiently small depth of field to observe depth-dependent atomic displacements in a crystal. The depth-dependent displacements associated with the Eshelby twist of dislocations in GaN normal to the foil with a screw component of the Burgers vector are directly imaged. We show that these displacements are observed as a rotation of the lattice between images taken in a focal series. From the sense of the rotation, the sign of the screw component can be determined.

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