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1.
BMC Neurol ; 22(1): 269, 2022 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-35854226

RESUMEN

BACKGROUND: Myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) is a common, long-term condition characterised by post-exertional malaise, often with fatigue that is not significantly relieved by rest. ME/CFS has no confirmed diagnostic test or effective treatment and we lack knowledge of its causes. Identification of genes and cellular processes whose disruption adds to ME/CFS risk is a necessary first step towards development of effective therapy. METHODS: Here we describe DecodeME, an ongoing study co-produced by people with lived experience of ME/CFS and scientists. Together we designed the study and obtained funding and are now recruiting up to 25,000 people in the UK with a clinical diagnosis of ME/CFS. Those eligible for the study are at least 16 years old, pass international study criteria, and lack any alternative diagnoses that can result in chronic fatigue. These will include 5,000 people whose ME/CFS diagnosis was a consequence of SARS-CoV-2 infection. Questionnaires are completed online or on paper. Participants' saliva DNA samples are acquired by post, which improves participation by more severely-affected individuals. Digital marketing and social media approaches resulted in 29,000 people with ME/CFS in the UK pre-registering their interest in participating. We will perform a genome-wide association study, comparing participants' genotypes with those from UK Biobank as controls. This should generate hypotheses regarding the genes, mechanisms and cell types contributing to ME/CFS disease aetiology. DISCUSSION: The DecodeME study has been reviewed and given a favourable opinion by the North West - Liverpool Central Research Ethics Committee (21/NW/0169). Relevant documents will be available online ( www.decodeme.org.uk ). Genetic data will be disseminated as associated variants and genomic intervals, and as summary statistics. Results will be reported on the DecodeME website and via open access publications.


Asunto(s)
COVID-19 , Síndrome de Fatiga Crónica , Adolescente , Síndrome de Fatiga Crónica/genética , Estudio de Asociación del Genoma Completo , Humanos , Estudios Longitudinales , SARS-CoV-2
2.
Arthroplasty ; 5(1): 63, 2023 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-38049889

RESUMEN

BACKGROUND: The aim of this study was to report on the validity of the Naviswiss handheld image-free navigation device for accurate intraoperative measurement of THA component positioning, in comparison with the three-dimensional (3D) reconstruction of computed tomography (CT) images as the gold standard. METHODS: A series of patients presenting to a single-surgeon clinic with end-stage hip osteoarthritis received primary hip arthroplasty with the anterolateral muscle-sparing surgical approach in the supine position. Imageless navigation was applied during the procedure with bone-mounted trackers applied to the greater trochanter and ASIS. Patients underwent routine CT scans before and after surgery and these were analyzed by using three-dimensional reconstruction to generate cup orientation, offset and leg length changes, which were compared to the intraoperative measurements provided by the navigation system. Estimates of agreement between the intraoperative and image-derived measurements were assessed with and without correction for bias and declared cases with potential measurement issues. RESULTS: The mean difference between intraoperative and postoperative CT measurements was within 2° for angular measurements and 2 mm for leg length. Absolute differences for the two indices were between 5° and 4 mm. Mean bias was 1.9°-3.6° underestimation for cup orientation and up to 2 mm overestimation for leg length change, but absolute thresholds of 10° and 10 mm were not exceeded by 95% limits of agreement (LOA), especially after correction for bias. Four cases (12%) were declared intraoperatively for issues with fixation on the greater trochanter. Inclusion of these cases generated acceptable accuracy overall and their omission failed to improve between-case variability in accuracy or LOA for both offset and leg length. CONCLUSIONS: The accuracy of the Naviswiss system applied during primary THA in a supine position and anterolateral surgical approach falls within clinically acceptable recommendations for acetabular cup placement, femoral offset, and length. With refinements to surgical technique to adapt to the navigation hardware, the system could be further improved with regression-based bias correction. TRIAL REGISTRATION: Registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618000317291).

3.
NIHR Open Res ; 3: 20, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37881452

RESUMEN

Background: People with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) experience core symptoms of post-exertional malaise, unrefreshing sleep, and cognitive impairment. Despite numbering 0.2-0.4% of the population, no laboratory test is available for their diagnosis, no effective therapy exists for their treatment, and no scientific breakthrough regarding pathogenesis has been made. It remains unknown, despite decades of small-scale studies, whether individuals experience different types of ME/CFS separated by onset-type, sex or age. Methods: DecodeME is a large population-based study of ME/CFS that recruited 17,074 participants in the first 3 months following full launch. Detailed questionnaire responses from UK-based participants who all reported being diagnosed with ME/CFS by a health professional provided an unparalleled opportunity to investigate, using logistic regression, whether ME/CFS severity or onset type is significantly associated with sex, age, illness duration, comorbid conditions or symptoms. Results: The well-established sex-bias among ME/CFS patients is evident in the initial DecodeME cohort: 83.5% of participants were females. What was not known previously was that females tend to have more comorbidities than males. Moreover, being female, being older and being over 10 years from ME/CFS onset are significantly associated with greater severity. Five different ME/CFS onset types were examined in the self-reported data: those with ME/CFS onset (i) after glandular fever (infectious mononucleosis); (ii) after COVID-19 infection; (iii) after other infections; (iv) without an infection at onset; and, (v) where the occurrence of an infection at or preceding onset is not known. Among other findings, ME/CFS onset with unknown infection status was significantly associated with active fibromyalgia. Conclusions: DecodeME participants differ in symptoms, comorbid conditions and/or illness severity when stratified by their sex-at-birth and/or infection around the time of ME/CFS onset.


Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) is a chronic disease that affects an estimated 250,000 people in the UK. Its defining symptom is post-exertional malaise, an excessive delayed worsening of symptoms following even minor physical or mental exertion. For those with it, ME/CFS means disability and poor quality of life. DecodeME is a research study which is looking for DNA differences between people with ME/CFS and people without any health problems. People with ME/CFS who take part in DecodeME complete a questionnaire that assesses their symptoms and whether they will then be invited to donate a DNA sample. This paper analyses the answers to this questionnaire; we will publish results of the DNA analysis separately. So far, more than 17 thousand people with ME/CFS have completed the DecodeME questionnaire. Their answers help us to address the question: "Are there different types of ME/CFS linked to different causes and how severe it becomes?" Results show that people with ME/CFS do not form a single group reporting similar symptoms and additional medical conditions. Instead, participants who had an infection at the start of their ME/CFS reported a different pattern of symptoms and conditions compared to those without an infection. It is well known that most people with ME/CFS are females. What was not clear previously was that females tend to have more additional health conditions. Also, being female, being older and being over 10 years from ME/CFS onset all make it more likely that someone is more severely affected by their ME/CFS. These findings could indicate that by studying people with different ME/CFS onset-types separately ­ rather than analysing all people with ME/CFS together ­ it will be easier to understand what is going wrong.

4.
BMJ Open Sport Exerc Med ; 8(3): e001410, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36157129

RESUMEN

Rupture of the anterior cruciate ligament of the knee is a common injury occurring mostly in young athletic individuals taking part in pivoting, cutting and jumping sports. It is demonstrated by anterolateral rotatory instability on clinical testing. As yet there are no clear guidelines as to whom will benefit from surgical reconstruction as opposed to rehabilitation alone, apart from elite athletes (defined as varsity players or those participating in sport at national or international level). Also, some adolescent knees and those with combined injuries, usually meniscal tears, may benefit from surgery. Even after surgery there is an increased incidence of rerupture and the development of degenerative changes in the operated knee, particularly in the young athlete who has returned to a high level of sporting activity. Early diagnosis is essential to provide a focused care pathway and to avoid the consequences of chronic cruciate insufficiency. Currently, it seems that too many anterior cruciate ligament reconstructions may be undertaken where rehabilitation alone would have sufficed. Better preoperative clinical testing including improved arthrometric assessment, muscle and neurological testing and imaging including radiology and MRI may help refine the diagnosis, thus enabling a better decision on further management. There is also a requirement for better designed clinical studies reporting on the outcomes of treatment be it either surgical or conservative.

5.
Environ Sci Technol ; 44(21): 8343-9, 2010 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-20886845

RESUMEN

The impacts of biodiesel and a continuously regenerated (catalyzed) diesel particle filter (DPF) on the emissions of volatile unburned hydrocarbons, carbonyls, and particle associated polycyclic aromatic hydrocarbons (PAH) and nitro-PAH, were investigated. Experiments were conducted on a 5.9 L Cummins ISB, heavy-duty diesel engine using certification ultra-low-sulfur diesel (ULSD, S ≤ 15 ppm), soy biodiesel (B100), and a 20% blend thereof (B20). Against the ULSD baseline, B20 and B100 reduced engine-out emissions of measured unburned volatile hydrocarbons and PM associated PAH and nitro-PAH by significant percentages (40% or more for B20 and higher percentage for B100). However, emissions of benzene were unaffected by the presence of biodiesel and emissions of naphthalene actually increased for B100. This suggests that the unsaturated FAME in soy-biodiesel can react to form aromatic rings in the diesel combustion environment. Methyl acrylate and methyl 3-butanoate were observed as significant species in the exhaust for B20 and B100 and may serve as markers of the presence of biodiesel in the fuel. The DPF was highly effective at converting gaseous hydrocarbons and PM associated PAH and total nitro-PAH. However, conversion of 1-nitropyrene by the DPF was less than 50% for all fuels. Blending of biodiesel caused a slight reduction in engine-out emissions of acrolein, but otherwise had little effect on carbonyl emissions. The DPF was highly effective for conversion of carbonyls, with the exception of formaldehyde. Formaldehyde emissions were increased by the DPF for ULSD and B20.


Asunto(s)
Contaminantes Atmosféricos/análisis , Contaminación del Aire/prevención & control , Filtración , Emisiones de Vehículos/prevención & control , Aldehídos/análisis , Biocombustibles , Hidrocarburos/análisis , Cetonas/análisis , Material Particulado/análisis , Hidrocarburos Policíclicos Aromáticos/análisis , Pirenos/análisis , Emisiones de Vehículos/análisis
6.
J Knee Surg ; 33(5): 513-524, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-30836393

RESUMEN

There is a lack of clinical outcomes reported for the rotating bearing knee (RBK) total knee arthroplasty (TKA), which is a second-generation rotating platform knee, with purported benefits over earlier versions. The purpose of the study was to report the complications, short-term (minimum 1 year) patient-reported outcomes and long-term (up to 15 years) procedure survival in a consecutive series of patients receiving a rotating platform TKA (RBK) from an independent clinic. A retrospective analysis of a single-surgeon, private/public practice, with prospectively collected data in a subset of patients were performed. A total of 1,130 procedures (primary, revision from unicompartmental knee arthroplasty (UKA) to TKA) were crossmatched with manufacturer records. Clinical outcomes (complications, reoperations) were summarized and linked to patient-reported outcome measures (Eq. 5D, KSS-function, Oxford knee score [OKS]). OKS results were classified using minimally clinical important difference (MCID) and patient acceptable symptom state (PASS). PROMs were summarized and regression models used to determine relationships between patient factors and outcomes in this cohort. Cumulative percent revision was reported by the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) and compared between the senior author and national data using Kaplan-Meier survival analysis. We report a complication rate of 19.7% with the majority (> 60%) being thromboembolic events and complaints of stiffness. Significant improvements were observed in general health, knee pain, and function with > 89% exceeding the MCID for the OKS and > 65% exceeding the PASS for the OKS at an average follow-up of 3.2 years. We report a cumulative revision rate of 4.3% at 5 years and 4.8% at 14 years, with significantly lower revision rates in females and patients aged 55 to 64 years compared with AOANJRR data for fixed bearing designs. The RBK rotating platform TKA provides good functional outcomes, with relatively low revision and complications rates at up to 14 years follow-up. This design in conjunction with a gap balancing technique may be advantageous in certain patient subgroups.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/instrumentación , Prótesis de la Rodilla , Osteoartritis de la Rodilla/cirugía , Anciano , Artroplastia de Reemplazo de Rodilla/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Medición de Resultados Informados por el Paciente , Rango del Movimiento Articular , Sistema de Registros , Reoperación , Estudios Retrospectivos , Tibia/cirugía , Resultado del Tratamiento
7.
BMJ Open ; 10(10): e037126, 2020 10 05.
Artículo en Inglés | MEDLINE | ID: mdl-33020091

RESUMEN

INTRODUCTION: Optimal outcomes in total hip arthroplasty (THA) are dependent on appropriate placement of femoral and acetabular components, with technological advances providing a platform for guiding component placement to reduce the risk of malpositioned components during surgery. This study will validate the intraoperative data captured using a handheld imageless THA navigation system against postoperative measurements of acetabular inclination, acetabular version, leg length and femoral offset on CT radiographs. METHODS AND ANALYSIS: This is a prospective observational cohort study conducted within a single-centre, single-surgeon private practice. Data will be collected for 35 consecutive patients (>18 years) undergoing elective THA surgery, from the research registry established at the surgeon's practice. The primary outcome is the agreement between intraoperative component positioning data captured by the navigation system compared with postoperative measurements using CT. A total of ten CT scans will be reassessed for interobserver and intraobserver reliability. The influence of patient and surgical factors on the accuracy of component position will also be examined with multivariable linear regression. ETHICS AND DISSEMINATION: Ethics approval for this study was provided through a certified ethics committee (Bellberry HREC approval number 2017-07-499). The results of this study will be disseminated through peer-reviewed journals and conference presentations. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry (ANZCTR) Trial ID: ACTRN12620000089932.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Prótesis de Cadera , Cirujanos , Cirugía Asistida por Computador , Acetábulo/cirugía , Australia , Humanos , Estudios Observacionales como Asunto , Estudios Prospectivos , Reproducibilidad de los Resultados , Resultado del Tratamiento
8.
J Knee Surg ; 22(3): 278-80, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19634737

RESUMEN

This article reports a case of primary total knee arthroplasty for osteoarthritis in a patient who underwent treatment 20 years previously for a large giant cell tumor presenting with an intraarticular knee fracture. The arthroplasty was made technically challenging by the abnormal shape of the distal femur. The reconstruction was facilitated by the use of stemmed components and autogenous bone graft. The medium-term results are encouraging. This case suggests a good outcome can be achieved in the presence of distorted distal femoral anatomy.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Neoplasias Óseas/cirugía , Fémur/cirugía , Tumor Óseo de Células Gigantes/cirugía , Femenino , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/cirugía , Persona de Mediana Edad , Osteoartritis de la Rodilla/cirugía , Radiografía , Factores de Tiempo
9.
Knee ; 12(3): 191-3, 2005 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15911291

RESUMEN

Three cases are reported in which clinical presentation was with arthritic symptoms and inability to straighten the knee. An unusually prominent anterior tibial osteophyte, whose shape is remarkably suggestive of a blacksmith's anvil, appeared to be a contributory factor through its apparent impingement with the femoral trochlea at the limit of extension. The osteophyte was radically removed arthroscopically in each case as an isolated gesture, and the patients were followed up with particular emphasis on fixed flexion deformity. At clinical review, after a mean follow-up period of 5.3 years, it was concluded that there had not been a convincing or sustained improvement in knee function, although the fixed flexion deformities had not increased significantly. Our conclusion is that the 'anvil' osteophyte may simply be a part of a more diffuse degenerative process and that it was probably not, in itself, the primary cause of fixed flexion deformity in these cases.


Asunto(s)
Neoplasias Óseas/diagnóstico , Deformidades Adquiridas de la Articulación/etiología , Rodilla/cirugía , Osteocondroma/diagnóstico , Adulto , Artroscopía , Neoplasias Óseas/cirugía , Humanos , Deformidades Adquiridas de la Articulación/cirugía , Rodilla/diagnóstico por imagen , Masculino , Osteocondroma/cirugía , Radiografía
10.
Knee ; 12(3): 245-7, 2005 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15911302

RESUMEN

Ganglion formation within the posterior septum of the knee has not been reported in the literature. The anatomy of the posterior septum makes it inaccessible to routine arthroscopic examination because it is formed by the reflections of the synovium from the posterior cruciate ligament. We describe a technique whereby a ganglion within the posterior septum of the knee was excised successfully.


Asunto(s)
Artroscopía/métodos , Ganglión/cirugía , Articulación de la Rodilla/cirugía , Adulto , Ganglión/diagnóstico , Humanos , Masculino
11.
Proc Biol Sci ; 271(1545): 1263-9, 2004 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-15306350

RESUMEN

The presence of top predators can affect prey behaviour, morphology and life history, and thereby can produce indirect population consequences greater and further reaching than direct depredation would have alone. Raptor species in the Americas are recovering since restrictions on the use of dichlorodiphenyltrichloroethane (DDT) and the implementation of conservation measures, in effect constituting a hemisphere-wide predator-reintroduction experiment, and profound effects on populations of their prey are to be expected. Here, we document changes in the behaviour of western sandpipers (Calidris mauri) at migratory stopover sites over two decades. Since 1985, migratory body mass and stopover durations of western sandpipers have fallen steadily at some stopovers in the Strait of Georgia, British Columbia. Comparisons between years, sites and seasons strongly implicate increasing danger from the recovery of peregrine falcons (Falco peregrinus) as a causal factor. A decade-long ongoing steep decline in sandpiper numbers censused on our study site is explained entirely by the shortening stopover duration, rather than fewer individuals using the site. Such behavioural changes are probably general among migratory shorebird species, and may be contributing to the widespread census declines reported in North America.


Asunto(s)
Migración Animal , Aves/fisiología , Conducta Alimentaria/fisiología , Animales , Pesos y Medidas Corporales , Colombia Británica , Observación , Dinámica Poblacional , Conducta Predatoria , Rapaces/fisiología , Factores de Tiempo
12.
Knee ; 11(2): 129-31, 2004 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15066625

RESUMEN

Double patella following a 'sleeve fracture' in the lower pole of the patellar is rare and even more so after surgical treatment to the original injury. We report such a case in a boy injured at the age of 10, and presenting 3 years later with weakness and effusion. The management is described, including the technique of excision of the accessory patella and the lowering of the larger patella to a normal level. We believe that this is the first such case to be reported after surgical treatment of the primary fracture.


Asunto(s)
Fracturas Óseas/cirugía , Osificación Heterotópica/etiología , Rótula/lesiones , Niño , Humanos , Masculino , Osificación Heterotópica/diagnóstico por imagen , Rótula/diagnóstico por imagen , Rótula/cirugía , Radiografía
13.
Knee ; 11(1): 25-8, 2004 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-14967324

RESUMEN

Clinical assessment of post traumatic ligament laxity is subjective. Stress radiographs provide an objective and permanent record of the laxity. We describe a simple method of stress radiography to help evaluate and to document valgus knee injuries. In this study we have correlated the X-ray findings with those at arthroscopy. No specialised equipment is required and radiation exposure to the patient and the surgeon is minimal. With the patient under general anaesthesia the injured and the normal knee are firmly bound together. A valgus stress is applied to both the knees simultaneously and a radiograph is taken. The opening of the medial joint space is measured as in the figure 1, i.e. the perpendicular distance between the tangent drawn to the subchondral bone of the femoral condyles, and the most medial point of the tibial plateau. The opening of the medial joint space provides a direct measure of valgus laxity. The ratio of the medial joint opening to the normal knee is calculated. A ratio of two or more is indicative of an associated anterior or posterior cruciate ligament rupture in addition to medial collateral ligament injury.


Asunto(s)
Artrografía/métodos , Inestabilidad de la Articulación/diagnóstico por imagen , Luxación de la Rodilla/diagnóstico por imagen , Traumatismos de la Rodilla/diagnóstico por imagen , Ligamento Colateral Medial de la Rodilla/lesiones , Adolescente , Adulto , Artroscopía , Femenino , Humanos , Inestabilidad de la Articulación/fisiopatología , Luxación de la Rodilla/fisiopatología , Traumatismos de la Rodilla/fisiopatología , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Estrés Mecánico
14.
Knee ; 11(6): 445-9, 2004 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-15581762

RESUMEN

Seven patients presenting between 1992 and 1999 with osteoarthritic knee symptoms in consequence of old malunited femoral shaft fractures, were treated by open femoral shaft osteotomy. The osteotomies were sited at the apex of the deformity and were fixed by locked intramedullary nailing. The patients were followed up until osteotomy union and reviewed clinically and radiologically with particular emphasis on symptoms and function. The mean age at presentation was 48 years and the mean time from fracture was 28 years. The mean time to osteotomy union was 28 months. Five of the seven patients reported excellent pain relief and functional improvement. These patients presented a difficult management problem at an age that would be worryingly young for total knee replacement. Arthroplasty has been avoided in all but one of this cohort, and is still far from imminent in the remainder, after a mean follow-up period of 5 years.


Asunto(s)
Fracturas del Fémur/cirugía , Fracturas Mal Unidas/cirugía , Osteoartritis de la Rodilla/cirugía , Osteotomía/métodos , Adulto , Anciano , Femenino , Fracturas del Fémur/fisiopatología , Fijación Intramedular de Fracturas , Curación de Fractura/fisiología , Fracturas Mal Unidas/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/fisiopatología , Dolor/fisiopatología , Dolor/cirugía , Rango del Movimiento Articular/fisiología , Resultado del Tratamiento
15.
Ann R Coll Surg Engl ; 91(5): 410-3, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19344550

RESUMEN

INTRODUCTION: The effect of primary total knee replacement on the employment status of 56 patients under 60 years of age was examined at a mean follow-up of 64 months. PATIENTS AND METHODS: A total of 56 primary total knee replacements performed on patients under the age of 60 years by two surgeons between 1996 and 2003 were retrospectively assessed by postal questionnaire. Patients were selected from databases held at Holly House and Newham Hospital NHS Trust. RESULTS: Overall, 97.5% of patients who were employed before their operation, returned to their previous work. However, in patients not working prior to total knee replacement none were employed after their operation. CONCLUSIONS: Total knee replacement may be a valuable tool to help some patients to continue working but may not affect patients who are already unemployed.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/estadística & datos numéricos , Empleo/estadística & datos numéricos , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Satisfacción del Paciente , Calidad de Vida
16.
Langmuir ; 24(17): 9784-9, 2008 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-18646876

RESUMEN

A method for noncovalent functionalization of DNA-wrapped single-walled carbon nanotubes (SWNTs) using platinum-based DNA cross-linkers is investigated. In particular, cisplatin and potassium tetrachloroplatinate are shown to bind to DNA that encapsulates SWNTs in aqueous solution. The bound platinum salt can then be reduced to decorate the DNA-encapsulated SWNTs with platinum nanoparticles. The resulting SWNT/DNA/Pt hybrids are investigated by optical absorption spectroscopy, circular dichroism spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, and atomic force microscopy. The unique combination of catalytic activity of nanoscale platinum, biological functionality of DNA, and optoelectronic properties of SWNTs suggests a myriad of applications including fuel cells, catalysts, biosensors, and electrochemical devices.


Asunto(s)
ADN/química , Nanopartículas del Metal/química , Nanotecnología/métodos , Nanotubos de Carbono/química , Platino (Metal)/química , Catálisis , Cloruros/farmacología , Dicroismo Circular , Cisplatino/farmacología , Reactivos de Enlaces Cruzados/química , Electroquímica , Microscopía de Fuerza Atómica , Microscopía Electrónica de Transmisión , Compuestos de Platino/farmacología , Espectrometría Raman , Difracción de Rayos X
17.
Inorg Chem ; 47(10): 4368-74, 2008 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-18433097

RESUMEN

Single crystal and bulk powder samples of the quaternary lanthanum copper oxysulfides La5Cu6.33O4S7 and La5Cu6O4S7 have been prepared by means of high-temperature sealed-tube reactions and spark plasma sintering, respectively. In the structure of La 5Cu6.33O4S7, Cu atoms tie together the fluorite-like (2)infinity[La5O4S(5+)] and antifluorite-like (2) infinity[Cu6S6(5-)] layers of La5Cu6O4S7. The optical band gap, E g, of 2.0 eV was deduced from both diffuse reflectance spectra on a bulk sample of La5Cu6O4S7 and for the (010) crystal face of a La 5Cu6.33O4S7 single crystal. Transport measurements at 298 K on a bulk sample of La 5Cu 6O 4S 7 indicated p-type metallic electrical conduction with sigma electrical =2.18 S cm(-1), whereas measurements on a La 5Cu6.33O4S7 single crystal led to sigma electrical =4.5 10(-3) S cm(-1) along [100] and to semiconducting behavior. In going from La 5Cu6O4S7 to La5Cu6.33O4S7, the disruption of the (2)infinity[Cu6S6(5-)] layer and the decrease in the overall Cu(2+)(3d(9)) concentration lead to a significant decrease in the electrical conductivity.

18.
Inorg Chem ; 45(20): 8264-72, 2006 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-16999426

RESUMEN

Black single crystals of the two nonstoichiometric cerium coinage-metal oxysulfide compounds CeCu(x)OS and CeAg(x)OS (x approximately 0.8) have been prepared by the reactions of Ce2S3 and CuO or Ag2O at 1223 or 1173 K, respectively. A black powder sample of CeAgOS has been prepared by the stoichiometric reaction of Ce2S3, CeO2, Ag2S, and Ag at 1073 K. These isostructural materials crystallize in the ZrSiCuAs structure type with two formula units in the tetragonal space group P4/nmm. Refined crystal structure results and chemical analyses provide evidence that the previously known anomalously small unit-cell volume of LnCuOS for Ln = Ce (Ln = rare-earth metal) is the result of Cu vacancies and the concomitant presence of both Ce3+ and Ce4+. Both CeCu(0.8)OS and CeAgOS are paramagnetic with mu(eff) values of 2.13(6) and 2.10(1) mu(B), respectively. CeCu(0.8)OS is a p-type semiconductor with a thermal activation energy Ea = 0.22 eV, sigma(electrical) = 9.8(1) 10(-3) S/cm at 298 K, and an optical band gap Eg < 0.73 eV. CeAgOS has conductivity sigma(conductivity) = 0.16(4) S/cm and an optical band gap Eg = 0.71 eV at 298 K. Theoretical calculations with an on-site Coulomb repulsion parameter indicate that the Ce 4f states are fully spin-polarized and are not localized in CeCuOS, CeCu(0.75)OS, or CeAgOS. Calculated band gaps for CeCu(0.75)OS and CeAgOS are 0.6 and 0.8 eV, respectively.

19.
Inorg Chem ; 44(17): 6071-6, 2005 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-16097827

RESUMEN

Mg- and Sn-doped In2O3 (MgIn(x)Sn(y)O(z), 6.0 < x < 16.0; 3.0 < y < 8.0) thin films were grown by low-pressure metal-organic chemical vapor deposition using the volatile metal-organic precursors tris(2,2,6,6-tetramethyl-3,5-heptanedionato)indium(III) [In(dpm)3], bis(2,4-pentanedionato)tin(II) [Sn(acac)2], and bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(N,N,N',N'-tetramethylethylenediamine)magnesium(II) [Mg(dpm)2(TMEDA)]. Films in this compositional range retain the cubic In2O3 bixbyite crystal structure. The highest conductivity is found to be approximately 1000 S/cm for an as-grown film with a nominal composition MgIn14.3Sn6.93O(z). Annealing of such films in a vacuum raises the conductivity to approximately 2000 S/cm. The optical transmission window of the present films is significantly wider than that of typical indium tin oxide (ITO) films from 300 to 3300 nm, and the transmittance is also greater than or comparable to that of commercial ITO films.

20.
J Am Chem Soc ; 127(24): 8796-804, 2005 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-15954786

RESUMEN

A series of yttrium-doped CdO (CYO) thin films have been grown on both amorphous glass and single-crystal MgO(100) substrates at 410 degrees C by metal-organic chemical vapor deposition (MOCVD), and their phase structure, microstructure, electrical, and optical properties have been investigated. XRD data reveal that all as-deposited CYO thin films are phase-pure and polycrystalline, with features assignable to a cubic CdO-type crystal structure. Epitaxial films grown on single-crystal MgO(100) exhibit biaxial, highly textured microstructures. These as-deposited CYO thin films exhibit excellent optical transparency, with an average transmittance of >80% in the visible range. Y doping widens the optical band gap from 2.86 to 3.27 eV via a Burstein-Moss shift. Room temperature thin film conductivities of 8,540 and 17,800 S/cm on glass and MgO(100), respectively, are obtained at an optimum Y doping level of 1.2-1.3%. Finally, electronic band structure calculations are carried out to systematically compare the structural, electronic, and optical properties of the In-, Sc-, and Y-doped CdO systems. Both experimental and theoretical results reveal that dopant ionic radius and electronic structure have a significant influence on the CdO-based TCO crystal and band structure: (1) lattice parameters contract as a function of dopant ionic radii in the order Y (1.09 A) < In (0.94 A) < Sc (0.89 A); (2) the carrier mobilities and doping efficiencies decrease in the order In > Y > Sc; (3) the dopant d state has substantial influence on the position and width of the s-based conduction band, which ultimately determines the intrinsic charge transport characteristics.

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