Synthesis of armchair graphene nanoribbons from the 10,10'-dibromo-9,9'-bianthracene molecules on Ag(111): the role of organometallic intermediates.

We investigate the bottom-up growth of N = 7 armchair graphene nanoribbons (7-AGNRs) from the 10,10'-dibromo-9,9'-bianthracene (DBBA) molecules on Ag(111) with the focus on the role of the organometallic (OM) intermediates. It is demonstrated that DBBA molecules on Ag(111) are partially debrominated at room temperature and lose all bromine atoms at elevated temperatures. Similar to DBBA on Cu(111), debrominated molecules form OM chains on Ag(111). Nevertheless, in contrast with the Cu(111) substrate, formation of polyanthracene chains from OM intermediates via an Ullmann-type reaction is feasible on Ag(111). Cleavage of C-Ag bonds occurs before the thermal threshold for the surface-catalyzed activation of C-H bonds on Ag(111) is reached, while on Cu(111) activation of C-H bonds occurs in parallel with the cleavage of the stronger C-Cu bonds. Consequently, while OM intermediates obstruct the Ullmann reaction between DBBA molecules on the Cu(111) substrate, they are required for the formation of polyanthracene chains on Ag(111). If the Ullmann-type reaction on Ag(111) is inhibited, heating of the OM chains produces nanographenes instead. Heating of the polyanthracene chains produces 7-AGNRs, while heating of nanographenes causes the formation of the disordered structures with the possible admixture of short GNRs.

Excess cost associated with primary hip and knee joint arthroplasty surgical site infections: a driver to support investment in quality improvement strategies to reduce infection rates.

AIM: To determine the excess costs attributable to surgical site infections (SSI) following primary hip and knee joint arthroplasty at Auckland City Hospital. METHODS: A retrospective case-control study. Cases were patients who developed a SSI following primary hip (THA) and knee arthroplasty (TKA) surgery within 90 days of the procedure. Cases were matched 1:2 with controls; patients whose primary hip and knee arthroplasty procedures were not complicated by infection. Controls were matched for age, gender, date of surgery, type of surgery, and ASA category. The length of stay (LOS) and hospital costs for the initial admission and subsequent readmission for infection were calculated from the clinical costing system at Auckland District Health Board. RESULTS: Eleven cases were identified; 3 following TKA, 7 following THA, and 1 following hemiarthroplasty of the hip. Infections were classified as superficial, 1, joint space, 1, and deep incisional, 9. Five SSI were identified during the initial admission for joint arthroplasty and 6 patients were readmitted with an SSI. Compared to the control patients, SSIs were associated with an excess mean cost of $40,121 and an excess mean LOS of 42 days. CONCLUSIONS: There is a significant increase in LOS and cost associated with SSI following primary THA and TKA at Auckland City Hospital. In addition to the excess cost associated with SSI, there are also opportunity costs resulting from their impact on elective surgical waiting lists. This reinforces the significant positive economic impact a successful strategy to reduce SSIs associated with primary joint arthroplasty procedures will have.

The reliability and validity of a child and adolescent participation in decision-making questionnaire.

BACKGROUND: There is a growing impetus across the research, policy and practice communities for children and young people to participate in decisions that affect their lives. Furthermore, there is a dearth of general instruments that measure children and young people's views on their participation in decision-making. This paper presents the reliability and validity of the Child and Adolescent Participation in Decision-Making Questionnaire (CAP-DMQ) and specifically looks at a population of looked-after children, where a lack of participation in decision-making is an acute issue. METHODS: The participants were 151 looked after children and adolescents between 10-23 years of age who completed the 10 item CAP-DMQ. Of the participants 113 were in receipt of an advocacy service that had an aim of increasing participation in decision-making with the remaining participants not having received this service. RESULTS: The results showed that the CAP-DMQ had good reliability (Cronbach's alpha = 0.94) and showed promising uni-dimensional construct validity through an exploratory factor analysis. The items in the CAP-DMQ also demonstrated good content validity by overlapping with prominent models of child and adolescent participation (Lundy 2007) and decision-making (Halpern 2014). A regression analysis showed that age and gender were not significant predictors of CAP-DMQ scores but receipt of advocacy was a significant predictor of scores (effect size d = 0.88), thus showing appropriate discriminant criterion validity. CONCLUSION: Overall, the CAP-DMQ showed good reliability and validity. Therefore, the measure has excellent promise for theoretical investigation in the area of child and adolescent participation in decision-making and equally shows empirical promise for use as a measure in evaluating services, which have increasing the participation of children and adolescents in decision-making as an intended outcome.

Dosimetric Comparison Between 3-Dimensional Conformal and Robotic SBRT Treatment Plans for Accelerated Partial Breast Radiotherapy.

Accelerated partial breast irradiation is an attractive alternative to conventional whole breast radiotherapy for selected patients. Recently, CyberKnife has emerged as a possible alternative to conventional techniques for accelerated partial breast irradiation. In this retrospective study, we present a dosimetric comparison between 3-dimensional conformal radiotherapy plans and CyberKnife plans using circular (Iris) and multi-leaf collimators. Nine patients who had undergone breast-conserving surgery followed by whole breast radiation were included in this retrospective study. The CyberKnife planning target volume (PTV) was defined as the lumpectomy cavity + 10 mm + 2 mm with prescription dose of 30 Gy in 5 fractions. Two sets of 3-dimensional conformal radiotherapy plans were created, one used the same definitions as described for CyberKnife and the second used the RTOG-0413 definition of the PTV: lumpectomy cavity + 15 mm + 10 mm with prescription dose of 38.5 Gy in 10 fractions. Using both PTV definitions allowed us to compare the dose delivery capabilities of each technology and to evaluate the advantage of CyberKnife tracking. For the dosimetric comparison using the same PTV margins, CyberKnife and 3-dimensional plans resulted in similar tumor coverage and dose to critical structures, with the exception of the lung V5%, which was significantly smaller for 3-dimensional conformal radiotherapy, 6.2% when compared to 39.4% for CyberKnife-Iris and 17.9% for CyberKnife-multi-leaf collimator. When the inability of 3-dimensional conformal radiotherapy to track motion is considered, the result increased to 25.6%. Both CyberKnife-Iris and CyberKnife-multi-leaf collimator plans demonstrated significantly lower average ipsilateral breast V50% (25.5% and 24.2%, respectively) than 3-dimensional conformal radiotherapy (56.2%). The CyberKnife plans were more conformal but less homogeneous than the 3-dimensional conformal radiotherapy plans. Approximately 50% shorter treatment times and 50% lower number of delivered monitor units (MU) were achievable with CyberKnife-multi-leaf collimator than with CyberKnife-Iris. The CyberKnife-multi-leaf collimator treatment times were comparable to 3-dimensional conformal radiotherapy, however, the number of MU delivered was approximately 2.5 times larger. The suitability of 10 + 2 mm margins warrants further investigation.

Real-time polymerase chain reaction and culture in the diagnosis of invasive group B streptococcal disease in infants: a retrospective study.

Group B streptococcus (GBS) is a leading cause of invasive disease in infants. Accurate and rapid diagnosis is crucial to reduce morbidity and mortality. Real-time polymerase chain reaction (PCR) targeting the dltR gene was utilised for the direct detection of GBS DNA in blood and cerebrospinal fluid (CSF) from infants at an Irish maternity hospital. A retrospective review of laboratory and patient records during the period 2011-2013 was performed in order to evaluate PCR and culture for the diagnosis of invasive GBS disease. A total of 3570 blood and 189 CSF samples from 3510 infants had corresponding culture and PCR results. Culture and PCR exhibited concordance in 3526 GBS-negative samples and 13 (25%) GBS-positive samples (n = 53). Six (11%) and 34 (64%) GBS-positive samples were positive only in culture or PCR, respectively. Culture and PCR identified more GBS-positive infants (n = 47) than PCR (n = 43) or culture (n = 16) alone. Using culture as the reference standard, the sensitivity, specificity, and positive and negative predictive values for PCR on blood samples were 71.4%, 99.2%, 25% and 99.9%, and for CSF samples, they were 60%, 97.8%, 42.9% and 98.9%, respectively. The sensitivity and positive predictive values were improved (blood: 84.6% and 55%; CSF: 77.8% and 100%, respectively) when maternal risk factors and other laboratory test results were considered. The findings in this study recommend the use of direct GBS real-time PCR for the diagnosis of GBS infection in infants with a clinical suspicion of invasive disease and as a complement to culture, but should be interpreted in the light of other laboratory and clinical findings.

Demonstration of electron acceleration in a laser-driven dielectric microstructure.

The enormous size and cost of current state-of-the-art accelerators based on conventional radio-frequency technology has spawned great interest in the development of new acceleration concepts that are more compact and economical. Micro-fabricated dielectric laser accelerators (DLAs) are an attractive approach, because such dielectric microstructures can support accelerating fields one to two orders of magnitude higher than can radio-frequency cavity-based accelerators. DLAs use commercial lasers as a power source, which are smaller and less expensive than the radio-frequency klystrons that power today's accelerators. In addition, DLAs are fabricated via low-cost, lithographic techniques that can be used for mass production. However, despite several DLA structures having been proposed recently, no successful demonstration of acceleration in these structures has so far been shown. Here we report high-gradient (beyond 250 MeV m(-1)) acceleration of electrons in a DLA. Relativistic (60-MeV) electrons are energy-modulated over 563 ± 104 optical periods of a fused silica grating structure, powered by a 800-nm-wavelength mode-locked Ti:sapphire laser. The observed results are in agreement with analytical models and electrodynamic simulations. By comparison, conventional modern linear accelerators operate at gradients of 10-30 MeV m(-1), and the first linear radio-frequency cavity accelerator was ten radio-frequency periods (one metre) long with a gradient of approximately 1.6 MeV m(-1) (ref. 5). Our results set the stage for the development of future multi-staged DLA devices composed of integrated on-chip systems. This would enable compact table-top accelerators on the MeV-GeV (10(6)-10(9) eV) scale for security scanners and medical therapy, university-scale X-ray light sources for biological and materials research, and portable medical imaging devices, and would substantially reduce the size and cost of a future collider on the multi-TeV (10(12) eV) scale.

Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations.

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq(3)) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq(3), and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.

Electronic and optical properties of magnesium phthalocyanine (MgPc) solid films studied by soft X-ray excited optical luminescence and X-ray absorption spectroscopies.

In a study to link the optical and structural properties of solid films of magnesium Phthalocyanine (MgPc), a range of synchrotron based spectroscopic methods have been used. These include X-ray excited optical luminescence (XEOL) together with X-ray absorption spectroscopy (XAS) measured both by total electron yield methods (TEY) and by using the optically detected photoluminescence yield method (PLY). XEOL spectra below K shell threshold show a broad emission peak at approximately 860 nm which can be attributed to the optical Q-band of these organic systems, which is then suppressed above the threshold. The shift to higher wavelength compared to optical emission spectra from MgPc in solution is consistent with intermolecular coupling of the excited states in the loosely intermolecular bonded phthalocyanine crystal structure. Zero order total PLY spectra at both C and N K edges are compared to TEY spectra where at the C K edge an inversion of intensity ratios between features is observed. Wavelength-specific PLY absorption spectra taken at 860 nm at the N K edge show a role for sigma* states participating in the luminescence process possibly through the sigma-like lone pair of bridging nitrogen atom, denoted the n --> pi* transition.

Minimally invasive technique for ligation and stripping of the small saphenous vein guided by intra-operative duplex ultrasound.

BACKGROUND: Small saphenous vein (SSV) disconnection and removal are challenging and considered by some authors to have too high a morbidity and failure rate to justify their routine use. Our audited results are at variance with these views. METHODS: We describe a reliable, ultrasound guided, minimally invasive technique for ligation and stripping of the SSV with an incision usually <1 cm. From our total series, 50 random patients attended for ultrasound review. The sapheno-popliteal junction (SPJ), strip track and signs of recurrence were assessed and recorded. RESULTS: Since 1999, 627 patients (679 limbs) have undergone surgery for ultrasound proven SSV reflux. Fifty-two limbs (50 patients) were ultrasound assessed post-operatively. Fifty-one had flush ligation of the SPJ with one showing a 'stump' <1 cm. All showed successful SSV removal. Three limbs had minor strip track revascularisation but none had obvious clinical recurrence. Of the whole series, 11/627 (1.8%) developed proven deep vein thrombosis (DVT). There were six superficial wound infections and one strip track abscess. Sural nerve neurapraxia occurred in 13/627 (2.1%); one showing no sign of recovery at four weeks post-operatively. CONCLUSIONS: Ultrasound guided SSV is a safe, minimally invasive technique with high success and low recurrence and complication rates

The modernisation of the surgical house officer.

INTRODUCTION: There have been considerable changes in the junior doctors' hours and working patterns over the last 4 years. The aim of this study was to assess the effect of these changes on the house officers' surgical experience and to obtain their opinions on the 'Hospital at Night' system, which has recently been introduced at our large teaching hospital. METHODS: A questionnaire was filled out by surgical house officers at the end of their surgical posts in 2001. The same questionnaire was then repeated for house officers completing the same posts in 2005. RESULTS: Pre-registration house officers now see less acute surgical admissions (mean 5 patients in 3 months in 2005 compared with 35 in 2001; P < 0.0001) and spend less time attending theatre than four years ago (mean 12 sessions in 3 months in 2001 compared with 6 in 2005). Despite the reduction in hours, they are still managing to attend educational sessions. Nine out of ten house officers felt that the 'Hospital at Night' system was unsatisfactory. They were unable to see and clerk acute surgical admissions or go to theatre because they were providing cross cover for other specialties. CONCLUSIONS: The full shift system and the introduction of the 'Hospital at Night' team have led to a reduction in acute surgical experience for surgical house officers. The General Medical Council recommendations for reducing non-educational tasks have not been fulfilled despite the evolving role of nurse practitioners.

Quasiparticle spectra, charge-density waves, superconductivity, and electron-phonon coupling in 2H-NbSe2.

High-resolution photoemission has been used to study the electronic structure of the charge-density wave (CDW) and superconducting dichalcogenide, 2H-NbSe2. From the extracted self-energies, important components of the quasiparticle interactions have been identified. In contrast to previously studied TaSe2, the CDW transition does not affect the electronic properties significantly. The electron-phonon coupling is identified as a dominant contribution to the quasiparticle self-energy and is shown to be very anisotropic (k dependent) and much stronger than in TaSe2.

Randomized clinical trial of three-layer paste and four-layer bandages for venous leg ulcers.

BACKGROUND: Both four-layer and three-layer paste bandages are widely used in the treatment of venous leg ulcers. The aim of this study was to compare the efficacy of these two bandaging regimens. METHODS: The study was a prospective, randomized, open comparison of a consecutive cohort of 133 patients with venous ulcers. Participants were stratified by ulcer size into one of three groups and were randomized within each group to receive either three-layer paste or four-layer bandages. All patients were followed for 1 year. The time taken to complete ulcer healing was the primary endpoint. The time taken to apply the bandages, comfort, tolerability and cost were also assessed. Analysis was performed on the basis of intention to treat. RESULTS: Ulcers healed completely in 51 (80 per cent) of 64 patients treated with three-layer paste bandages compared with 45 (65 per cent) of 69 patients treated with the four-layer regimen (P = 0.031). This difference developed only after 20 weeks of treatment. The median times to complete healing were 12 weeks for three-layer and 16 weeks for four-layer treatment (P = 0.040). Results of venous function tests, including half-refilling times, were similar in the two groups. CONCLUSION: Three-layer paste bandages were significantly more effective at healing venous ulcers than the four-layer regimen in this study.

Incidence and pattern of long saphenous vein duplication and its possible implications for recurrence after varicose vein surgery.

BACKGROUND: The incidence of long saphenous vein (LSV) duplication has not been clearly established. This anomaly could have implications for recurrence after varicose vein surgery. METHODS: Some 103 saphenograms obtained in 85 patients being considered for peripheral arterial bypass surgery were reviewed. Non-ionic contrast medium was injected directly into the vein or its tributaries at the ankle. Duplications of the LSV and their relation to thigh and calf perforator veins were assessed and recorded by two independent observers. RESULTS: There was evidence of duplication of the LSV in 50 (49 per cent) of the 103 saphenograms. Most duplications were present in the thigh (88 per cent) and the most common pattern was a closed loop (54 per cent). Perforator veins were connected to one branch of the duplication in 42 per cent of the legs (20 per cent of all 103 legs); in half the perforator vein was connected to the non-dominant branch of the duplication. Only ten of the 18 patients who had bilateral saphenograms had duplications in both legs, and only one patient had the same pattern of duplication on both sides. CONCLUSION: The incidence of LSV duplications is higher than previously reported.

Value of isotope lymphography in the diagnosis of lymphoedema of the leg.

BACKGROUND: Isotope lymphography has largely replaced contrast lymphography in the diagnosis of lymphoedema. Its accuracy has only been assessed in small studies and it is not known if it can identify patients with a proximal lymphatic obstruction who may be suitable for lymphatic bypass surgery. METHODS: Three hundred and ninety-five patients suspected to have lymphoedema were investigated by isotope lymphography between 1985 and 1995. Contrast lymphography was also carried out in 29 of these patients because the isotope results were thought to be misleading, or because lymphatic bypass surgery was being considered. RESULTS: In the 29 patients who had both investigations isotope lymphography detected 20 of 24 abnormal lymphatic systems. Four legs with obstructed groin lymphatics were reported as normal. Two legs with normal contrast lymphograms were erroneously diagnosed as having lymphoedema in the isotope study. Detectable groin nodes on the scintigrams were indicative of either normal lymphatics or proximal lymphatic obstruction. An increase in isotope uptake over 30-60 min of less than 50 per cent, or a total absence of isotope within groin nodes, was a sensitive indicator that patients were unsuitable for lymphatic bypass surgery. CONCLUSION: Isotope lymphography is a moderately sensitive test for lymphoedema, which will mistakenly classify some normal legs as lymphoedematous. It will usually correctly identify patients who are suitable for lymphatic bypass surgery.

Recruitment of labelled monocytes by experimental venous thrombi.

OBJECTIVE: Infusing monocytes that have been stimulated to produce fibrinolytic activators and factors that regulate cell proliferation, migration and maturation, might enhance venous thrombus resolution. The aim of this study was to determine the time course of infused monocyte recruitment into venous thrombus in an appropriate model of this disease. DESIGN AND METHODS: Thrombus was induced in the inferior vena cava of male Wistar rats using reduced flow (80-90% stenosis). The vessel wall was examined at 1hr by scanning electron microscopy. Resolving thrombi with surrounding vena cava were obtained at 1, 7, 14 and 21 days after induction (n = 8). Sections, taken at 0.5 mm intervals (10-15 sections per thrombus), were stained using haematoxylin, Martius Scarlet Blue and antibodies against monocytes, platelets and fibrin. Sections from human venous thrombi (n = 4) were similarly stained. The area occupied by monocytes (in relative pixel units, RPU) was determined using computer aided image analysis. Peripheral rat blood monocytes were extracted, fluorescently labelled and injected intravenously into 7 rats prior to thrombus induction, Vena cava with thrombus was harvested 1 h, 2, 3, 4, 7, 14 and 25 days after induction and their fluorescence measured. The fluorescent content of the caval wall and thrombus was analysed in greater detail at 2 and 25 days after thrombus induction (n = 4 at each time interval). RESULTS: Experimental thrombi were structurally similar to human thrombus and resolved within 14-21 days. Scanning electron microscopy showed minimal endothelial damage at 1 h with signs of early thrombus formation (platelet, red cell leukocyte and fibrin deposition). Neutrophils were the predominant leukocyte in the thrombus at 1 day, with monocytes making up only 0.3% (0.04% sem) of the area of the thrombus. There was a steady increase in thrombus monocyte content and by 21 days the percentage area of thrombus covered by monocytes had increased by over 35 fold to 11.5% (2.3% sem) (p <0.001). Initially, monocytes appeared around the edge of the thrombus and became more evenly distributed through the thrombus as resolution progressed. Labelled monocytes could be found in the circulation up to 1 week after infusion. The fluorescent content (RPU) of the thrombus increased over 25 days (mean RPU At 2 days 0.012, sem 0.005; mean RPU at 25 days 1.062, sem 0.252, p = 0.008). The number of labelled monocytes in the vessel wall peaked at 2 days and decreased thereafter. CONCLUSION: The structure of thrombi produced by this model was comparable to that of human venous thrombi. Endogenous and injected monocytes migrated into the thrombus during natural resolution, possibly via the vein wall. Monocyte targeting could therefore be used to develop novel treatments for venous thrombosis, with the aim of reducing post-thrombotic complications.

Thoracic aortic stent grafts--early experience from two centres using commercially available devices.

OBJECTIVES: open surgical intervention for aneurysms of the distal arch and descending thoracic aorta is associated with high morbidity and mortality. Stent grafts offer an attractive alternative treatment for these aneurysms. The aim of this study was to assess the morbidity and mortality of endovascular treatment for these aneurysms with stent grafts. DESIGN, PATIENTS AND METHODS: a prospective observational study was performed of 37 consecutive patients treated from July 1997 to October 2000 (30 at Guy's and St. Thomas' and 7 at Sheffield). Indications included degenerative aneurysms (n=18), false aneurysm (5), acute dissection (4), aortic transection (4), aneurysm related to previous surgery for coarctation (3), chronic dissection (2) and traumatic dissection (1). Nineteen were performed as elective and 18 as non-elective procedures. RESULTS: three non-elective patients died in hospital (in-hospital and 30-day mortality 8%) and one suffered a stroke with spontaneous full recovery. No elective patient died. One patient with a persistent proximal endoleak required conversion to open repair at 6 weeks. Two patients with persistent flow into the sac at 24 h spontaneously thrombosed at subsequent 3 month follow-up. Two further patients developed new distal endoleaks at 3 months and required distal extension cuffs. One patient died at 28 months of aortic rupture. Serial CT scans had shown prolapse of the stent graft into the aneurysm sac and the patient died just before planned endovascular repair. No patient suffered paraplegia or renal failure. Intensive care facilities were only required for patients who needed them preoperatively. CONCLUSIONS: thoracic stent grafts can be performed with low morbidity and mortality. They offer a realistic alternative to open surgery. Long term follow up is required to assess their durability.

Multiple aneurysms associated with congenital rubella.

We describe the case of a woman with congenital rubella who presented with backache. Plain abdominal X-ray revealed calcification of a superior mesenteric artery aneurysm. Intra-arterial digital subtraction angiography demonstrated multiple aneurysms of the arteries to the upper and lower limbs and the viscera. We have not found another report in the literature of the association of congenital rubella with multiple aneurysms.

Value of intraoperative duplex imaging during supervised carotid endarterectomy.

BACKGROUND: For overall benefit, carotid endarterectomy requires low perioperative morbidity and mortality rates. Carotid thrombosis is usually secondary to technical error, which may be related to the experience of the operator. In this retrospective study the clinical and technical outcome of carotid endarterectomies performed by one consultant and five trainees were compared. METHODS: Some 149 patients underwent carotid endarterectomy; 89 were operated on by the consultant and 60 by trainees. Intraoperative duplex imaging of the carotid repair was performed before wound closure, and re-exploration was carried out when there was a residual severe stenosis associated with an intimal flap. RESULTS: There was no significant difference in clinical outcome between operations done by consultant or trainees. There was a significant increase in the number of stenoses, kinks and flaps in carotid endarterectomies performed by trainees compared with those of the consultant both before (chi2 = 12.0, 1 d.f., P < 0.001) and after (chi2 = 10.1, 1 d.f., P < 0.001) correction. CONCLUSION: Intraoperative duplex imaging may facilitate training by providing an objective assessment of the quality of the operation.