Exciton dynamics of C60-based single-photon emitters explored by Hanbury Brown-Twiss scanning tunnelling microscopy

Exciton creation and annihilation by charges are crucial processes for technologies relying on charge-exciton-photon conversion. Improvement of organic light sources or dye-sensitized solar cells requires methods to address exciton dynamics at the molecular scale. Near-field techniques have been instrumental for this purpose; however, characterizing exciton recombination with molecular resolution remained a challenge. Here, we study exciton dynamics by using scanning tunnelling microscopy to inject current with sub-molecular precision and Hanbury Brown–Twiss interferometry to measure photon correlations in the far-field electroluminescence. Controlled injection allows us to generate excitons in solid C₆₀ and let them interact with charges during their lifetime. We demonstrate electrically driven single-photon emission from localized structural defects and determine exciton lifetimes in the picosecond range. Monitoring lifetime shortening and luminescence saturation for increasing carrier injection rates provides access to charge-exciton annihilation dynamics. Our approach introduces a unique way to study single quasi-particle dynamics on the ultimate molecular scale.

Electrons and holes trapped in a molecular crystal couple to form excitons. Here, the authors use scanning tunnelling microscopy to inject current with submolecular precision into structural defects in solid C₆₀ and demonstrate single photon emission from the excitons trapped there.

Acortamiento cubital. Contribución del sistema guiado para osteotomía y síntesis

Objetivos: El acortamiento cubital es la técnica quirúrgica empleada más habitualmente para casos de impactación y dolor cubitocarpiano. Tradicionalmente el cúbito ha sido cortado sin guía y la osteosíntesis realizada con una placa no diseñada para esta intervención, pero han surgido sistemas que pretenden facilitar el trabajo al cirujano utilizando guías para la osteotomía y placas de compresión específicas, e intentar mejorar la evolución de los pacientes. El propósito de este estudio es determinar si con el uso de los sistemas guiados se consiguen mejorar los resultados de la técnica previa.

Material y método: Entre 2004 y 2008 el acortamiento cubital se realizó en nuestro Centro sin utilizar una técnica guiada, a partir del 2008 se utilizó un sistema guiado. Se ha realizado un estudio descriptivo en 37 casos, 19 no guiados, 18 guiados, revisando el tiempo de duración de la cirugía, el rango de movimiento, el tiempo de consolidación y la retirada del material de osteosíntesis.

Resultados: Tras realizar un análisis estadístico de los datos, se ha visto que hay una diferencia estadísticamente significativa en relación con la variable duración de la cirugía, siendo la cirugía guiada veinte minutos más corta que la no guiada. No se han visto diferencias estadísticamente significativas en los otros parámetros.

Conclusión: En el acortamiento cubital el uso de los sistemas guiados para corte y osteosíntesis, consigue reducir el tiempo de la cirugía, sin ocasionar detrimento en los resultados en comparación con la técnica sin guía.

Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation

Polycyclic aromatic hydrocarbons as well as other organic molecules appear among the most abundant observed species in interstellar space and are key molecules to understanding the prebiotic roots of life. However, their existence and abundance in space remain a puzzle. Here we present a new top-down route to form polycyclic aromatic hydrocarbons in large quantities in space. We show that aromatic species can be efficiently formed on the graphitized surface of the abundant silicon carbide stardust on exposure to atomic hydrogen under pressure and temperature conditions analogous to those of the interstellar medium. To this aim, we mimic the circumstellar environment using ultra-high vacuum chambers and investigate the SiC surface by in situ advanced characterization techniques combined with first-principles molecular dynamics calculations. These results suggest that top-down routes are crucial to astrochemistry to explain the abundance of organic species and to uncover the origin of unidentified infrared emission features from advanced observations.

Epidemiology and outcome of candidaemia in patients with oncological and haematological malignancies: results from a population-based surveillance in Spain

A prospective, population-based surveillance on candidaemia was implemented in five metropolitan areas of Spain from May 2010 to April 2011. We aimed to describe the distribution and susceptibility pattern of Candida species, and to evaluate risk factors for mortality in patients with oncological (solid tumours) and haematological malignancies. Adults (≥ 16 years) with cancer were included in the present report. Impact of therapeutic strategies on 7- and 30-day mortality were analysed by logistic regression, adjusting for propensity score by inverse weighting probability of receiving early antifungal treatment and catheter removal. We included 238 (32.6%) patients (195 oncological, 43 haematological). Compared with oncological patients, haematological patients were more likely to have received chemotherapy (53.5% versus 17.4%, p < 0.001) or corticosteroids (41.9% versus 21%, p < 0.001), and have neutropenia (44.2% versus 1.5%, p < 0.001). Overall, 14.8% of patients developed breakthrough candidaemia. Non-albicans Candida species (71.1% versus 55.6%, p 0.056) and Candida tropicalis (22.2% versus 7.6%, p 0.011) were more frequent in haematological patients. Based on EUCAST breakpoints, 27.6% of Candida isolates were non-susceptible to fluconazole. Resistance to echinocandins was negligible. Mortality at 7 and 30 days was 12.2% and 31.5%, respectively, and did not differ significantly between the patient groups. Prompt antifungal therapy together with catheter removal (≤ 48 hours) was associated with lower mortality at 7 days (adjusted OR 0.05; 95% CI 0.01-0.42) and 30 days (adjusted OR 0.27; 95% CI 0.16-0.46). In conclusion, non-albicans species are emerging as the predominant isolates, particularly in haematological patients. Prompt, adequate antifungal treatment plus catheter removal may lead to a reduction in mortality.

Ortho and para hydrogen dimers on G/SiC(0001): combined STM and DFT study

The hydrogen (H) dimer structures formed upon room-temperature H adsorption on single layer graphene (SLG) grown on SiC(0001) are addressed using a combined theoretical-experimental approach. Our study includes density functional theory (DFT) calculations for the full (6√3 × 6√3)R30° unit cell of the SLG/SiC(0001) substrate and atomically resolved scanning tunneling microscopy images determining simultaneously the graphene lattice and the internal structure of the H adsorbates. We show that H atoms normally group in chemisorbed coupled structures of different sizes and orientations. We make an atomic scale determination of the most stable experimental geometries, the small dimers and ellipsoid-shaped features, and we assign them to hydrogen adsorbed in para dimers and ortho dimers configuration, respectively, through comparison with the theory.

[Spasm of the near reflex. Treatment with botulinum toxin]

CLINICAL CASE

A 38-year old female with diplopia and esotropia, with limitation of ocular abduction in both eyes, with full abduction after doll's head rotation also being observed. She was diagnosed with spasm of the near reflex. Treatment with injections of botulinum toxin in both medial rectus has temporally resolved the convergence spasm.

DISCUSSION

Near reflex spasm is characterized as miosis, pseudomyopia, and convergent strabismus that lead to diplopia, blurred vision, headache, and variable, progressive, and intermittent esotropia. As the spasm worsens there will be limited ocular versions and ductions simulating a sixth nerve palsy. Botulinum toxin may be effective in some cases.

Immunoglobulins IgG1, IgM and IgA: a synergistic team influencing survival in sepsis

OBJECTIVE

The impact of endogenous immunoglobulin isotypes on the prognosis of patients with severe sepsis has not been sufficiently explored. The aim of this study was to evaluate the association between immunoglobulin levels in plasma and survival in patients with this condition.

DESIGN AND PATIENTS

A prospective multicentre cohort study was conducted. A total of 172 adult patients admitted to the intensive care unit (ICU) with severe sepsis or septic shock were recruited. Patients were classified based on deciles of immunoglobulin concentrations at diagnosis of sepsis. Categorical variables were created and tested for their association with survival during hospitalization in the ICU.

RESULTS

Overall, 42 patients died in the ICU during the study. Kaplan-Meier analysis showed that immunoglobulin concentrations below 300 mg dL(-1) for IgG1, 35 mg dL(-1) for IgM and 150 mg dL(-1) for IgA were associated with shorter survival times. Multivariate regression analysis showed that IgG1 < 300 mg dL(-1) was a risk factor for mortality [odds ratio (OR) 2.50, 95% confidence interval (CI) 1.04-6.03; P = 0.042]. The combined presence of IgG1, IgM and IgA levels below the described thresholds had a synergistic impact on mortality risk (OR 5.27, 95% CI 1.41-19.69; P = 0.013). A similar effect was observed for combined low levels of IgG1 and IgA (OR 4.10, 95% CI 1.28-13.12; P = 0.018) and also of IgG1 and IgM (OR 3.10. 95% CI 1.13-8.49; P = 0.028).

CONCLUSIONS

The combined presence of low levels of the endogenous immunoglobulins IgG1, IgM and IgA in plasma is associated with reduced survival in patients with severe sepsis or septic shock. Assessment of the concentrations of these immunoglobulins could improve the results of treatment with exogenous immunoglobulins in patients with sepsis.

Patient safety certification in a Department of Intensive Care Medicine: our experience with standard UNE 179003:2013

Systematic and structured methods must be used to ensure that healthcare risks are effectively managed. Spanish standard UNE 179003:2013 provides healthcare organizations with a framework and a systematic protocol for managing patient safety from a clinical and organizational perspective. Furthermore, it is useful in securing an efficient balance among health risk, health outcomes and costs. The UNE 179003:2013 certifies that a clinical service complies with rules and operating procedures aimed at reducing the incidence of adverse events. It also requires mandatory continuous improvement, given that the standard entails frequent monitoring of the risk management system through periodic audits. The aims of this paper are to describe the UNE 179003:2013 certification process in an Intensive Care Unit, propose a risk management program for critical patients, and offer some recommendations regarding its implementation.

[Duane vertical surgical treatment]

CASE REPORT

We report 3 cases with a vertical incomitance in upgaze, narrowing of palpebral fissure, and pseudo-overaction of both inferior oblique muscles. Surgery consisted of an elevation of both lateral rectus muscles with an asymmetrical weakening. A satisfactory result was achieved in 2 cases, whereas a Lambda syndrome appeared in the other case.

DISCUSSION

The surgical technique of upper-insertion with a recession of both lateral rectus muscles improved vertical incomitance in 2 of the 3 patients; however, a residual deviation remains in the majority of cases.

[Medication errors in Spanish intensive care units]

OBJECTIVE

To estimate the incidence of medication errors in Spanish intensive care units.

DESIGN

Post hoc study of the SYREC trial. A longitudinal observational study carried out during 24 hours in patients admitted to the ICU.

SETTING

Spanish intensive care units.

PATIENTS

Patients admitted to the intensive care unit participating in the SYREC during the period of study.

MAIN VARIABLES OF INTEREST

Risk, individual risk, and rate of medication errors.

RESULTS

The final study sample consisted of 1017 patients from 79 intensive care units; 591 (58%) were affected by one or more incidents. Of these, 253 (43%) had at least one medication-related incident. The total number of incidents reported was 1424, of which 350 (25%) were medication errors. The risk of suffering at least one incident was 22% (IQR: 8-50%) while the individual risk was 21% (IQR: 8-42%). The medication error rate was 1.13 medication errors per 100 patient-days of stay. Most incidents occurred in the prescription (34%) and administration (28%) phases, 16% resulted in patient harm, and 82% were considered "totally avoidable".

CONCLUSIONS

Medication errors are among the most frequent types of incidents in critically ill patients, and are more common in the prescription and administration stages. Although most such incidents have no clinical consequences, a significant percentage prove harmful for the patient, and a large proportion are avoidable.

[Horizontal sensory strabismus: characteristics and treatment results]

PURPOSE

To study the types of horizontal sensory strabismus, their causes, and treatment outcomes.

METHODS

A retrospective analysis of 44 patients with horizontal sensory strabismus who were treated from 2002 to 2007. Patients whose worse eye vision was inferior or equal to 0.2 were included. The deviation angle in primary position, causes, type of treatment, and pre-operative or post-operative diplopia were studied. A good result was considered if the final deviation was less than 10 prism diopters (pd).

RESULTS

Of the patients studied, 63.6% had exotropia and the 36.4% had esotropia. The visual acuity was between 0.1 and no light perception in 75% of patients. The causes responsible for low vision were congenital in 28, and acquired in 16 cases. The mean deviation was 46.7 pd. Diplopia was present in 5 cases, which were resolved with surgical treatment in 3 of them. The eye with reduced vision was operated on in 37 patients, both eyes in 6 cases, and botulinum toxin was injected in 1 case. The final outcome was successful in 90.6% of the cases which were surgically treated. The mean follow up was 31.84 months.

CONCLUSIONS

There were twice as many exotropias as esotropias. Strabismus surgery of the amblyopic eye shows excellent results without the need of new operations. There were no new diplopia cases.

Klebsiella pneumoniae: development of a mixed population of carbapenem and tigecycline resistance during antimicrobial therapy in a kidney transplant patient

Nine isolates of Klebsiella pneumoniae were isolated from a renal transplant patient suffering from recurrent urosepsis over a period of 4 months. Imipenem resistance was detected after imipenem-ertapenem therapy. When treatment was switched to tigecycline the K. pneumoniae developed resistance to tigecycline (MIC = 8 mg/L). The nine isolates were tested by determination of agar dilution MICs, phenotypic carbapenemase, extended-spectrum beta-lactamases and metallo-beta-lactamase (MBL) testing and pulsed-field gel electrophoresis. Polymerase chain reaction and sequencing analysis were employed for identification of bla genes and mapping of the integron carrying the MBL gene. The nine isolates were clonally related and all produced the SHV-12 enzyme. Five MBL-producing isolates showed imipenem MICs ranging from 2 to 64 mg/L and all were detected by testing with imipenem and EDTA. The five isolates harboured the bla(VIM-1) gene. Three isolates showed increased tigecycline MICs (4-8 mg/L). Serial blood cultures obtained on the same day resulted in a VIM-positive/tigecycline-susceptible and a VIM-negative/tigecycline-resistant K. pneumoniae isolate. No isolate developed concurrent imipenem and tigecycline resistance. The patient had a persistent urinary tract infection and recurrent bacteraemia caused by a mixed population of Klebesiella pneumoniae isolates adapting to the selective pressure of antimicrobial therapy at the time. The present study is a worrisome example of what could happen when an immunocompromised host is subjected to the pressures of antimicrobial therapy. In addition, we report the first treatment-emergent MIC increase of tigecycline from 0.5 to 8 mg/L in K. pneumoniae.

[Superior oblique sharpening surgery in the treatment of Brown syndrome plus]

PURPOSE

To describe superior oblique sharpening in congenital Brown syndrome plus.

MATERIAL AND METHODS

A retrospective study of 17 Brown syndrome cases that were treated with oblique superior sharpening from 1997 to 2007. Vertical deviation in primary position was classified as + to +++, head tilt as: mild (< 10°), moderate (10-20°) and severe (≥ 20°); elevation in adduction from -1 to -4. A good postoperative result was considered if last elevation limitation in adduction was zero or -1, without head tilt and vertical deviation in primary position.

RESULTS

Mean age was 4.9 years. Limitation elevation in adduction which was -3 in 8 cases (47.1%) and -4 in 9 (52.9%), which improved completely after surgery in 6, -1 in 9 and -3 in 2 patients. Preoperative hypotropia in 15 cases (13 mild, 1 moderate and one severe) was resolved in 13 after surgery. Of 14 patients with torticollis (3 mild, 10 moderate and one severe) it was surgically corrected in 11. Success was achieved in 14 (82.4%), 2 were under corrected (11.8%) and one was overcorrected (5.88%). Mean follow-up was 60.71 months.

CONCLUSIONS

Oblique superior sharpening as treatment for Brown syndrome plus is an effective procedure. The incidence of secondary oblique palsies has been very low.