Nitrogen-doped graphene: effect of graphite oxide precursors and nitrogen content on the electrochemical sensing properties.

Graphene, produced via chemical methods, has been widely applied for electrochemical sensing due to its structural and electrochemical properties as well as its ease of production in large quantity. While nitrogen-doped graphenes are widely studied materials, the literature showing an effect of graphene oxide preparation methods on nitrogen quantity and chemical states as well as on defects and, in turn, on electrochemical sensing is non-existent. In this study, the properties of nitrogen-doped graphene materials, prepared via hydrothermal synthesis using graphite oxide produced by various classical methods using permanganate or chlorate oxidants Staudenmaier, Hummers, Hofmann and Brodie oxidation methods, were studied; the resulting nitrogen-doped graphene oxides were labeled as ST-GO, HU-GO, HO-GO and BR-GO, respectively. The electrochemical oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine, nicotinamide adenine nucleotide and DNA free bases, was carried out using cyclic voltammetry and differential pulse voltammetry techniques. The nitrogen content in doped graphene oxides increased in the order ST-GO < BR-GO < HO-GO < HU-GO. In the same way, the pyridinic form of nitrogen increased and the electrocatalytic effect of N-doped graphene followed this trend, as shown in the cyclic voltammograms. This is a very important finding that provides insight into the electrocatalytic effect of N-doped graphene. The nitrogen-doped graphene materials exhibited improved sensitivity over bare glassy carbon for ascorbic acid, uric acid and dopamine detection. These studies will enhance our understanding of the effects of graphite oxide precursors on the electrochemical sensing properties of nitrogen-doped graphene materials.

Microwave Exfoliation of Graphite Oxides in H2S Plasma for the Synthesis of Sulfur-Doped Graphenes as Oxygen Reduction Catalysts.

Tuning the electronic and chemical properties of graphene can be carried out through heteroatomic doping, enabling its use as an electrocatalyst. Sulfur-doped graphene has been suggested to be a viable alternative to traditional Pt-based catalysts for oxygen reduction under alkaline conditions. Herein we present a fast and efficient route to synthesize S-doped graphenes through the microwave-assisted exfoliation and reduction of three different graphite oxides in the presence of hydrogen sulfide. The materials obtained were characterized using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, combustion elemental analysis, and voltammetry. These S-doped graphenes were found to have good electrochemical performance and were active in the catalysis of the oxygen reduction reaction.

Simple Synthesis of Fluorinated Graphene: Thermal Exfoliation of Fluorographite.

Fluorinated graphene can be prepared directly by thermal exfoliation of fluorographite. The exfoliation was performed in a dynamic nitrogen atmosphere at various temperatures and the exfoliation products were analysed in detail by GC-MS. The structure and properties of all prepared fluorinated graphenes with various contents of fluorine were characterized by a number of analytical techniques. The results show both the dependence of fluorine concentration on exfoliation temperature and the suitability of this method for the synthesis of graphene with controlled concentration of fluorine. The high-temperature exfoliated fluorographite exhibits a high heterogeneous electron transfer rate and excellent catalytic properties towards the oxygen reduction reaction. These synthetic procedures can open a simple way for the synthesis of fluorinated graphene-based devices with tailored properties.

Epidemiology of bacterial infections in patients with liver cirrhosis. Experience in a Spanish tertiary health center.

INTRODUCTION: Bacterial infections represent a serious complication of liver cirrhosis. Traditionally, Gram negative bacteria have been described as the microorganisms responsible for the majority of the infections. However, in the past few years, changes in the microbiological spectrum have been described, and multiresistant bacteria are observed more frequently.  OBJECTIVE: To assess the proportion of patients with infections caused by multiresistant bacteria admitted to our hospital, and to obtain information about their epidemiology, risk factors and clinical impact.  MATERIALS AND METHODS: We performed a retrospective evaluation of 294 cirrhotic patients admitted to our unit due to infection between June, 2011, and June, 2013.  RESULTS: We isolated 310 microorganisms from 294 patients; 109 (35.2%) were Gram positive, 167 (53.9%), Gram negative, and 34, fungi (11%). As for the microbiological agents, the most frequent was Escherichia coli (98 isolations). The infection was community-acquired in 22.9% of cases, healthcareassociated in 38.1% and nosocomial in 39%. Worse liver infections and septic shock were more frequent among patients with multiresistant isolates (p=0.05); and intrahospital mortality was also higher among them (p=0.017). Previous hospital admission, antibiotic treatment 60 days before, nosocomial or healthcare-associated acquisition and bacterial isolation in control cultures were identified as possible risk factors for the development of multiresistant infection.  DISCUSSION: The results of our study confirm that important changes have ocurred in the microbiological spectrum of bacterial infections in patients with liver cirrhosis. Multiresistant bacteria are associated with high morbidity and mortality, as well as failure of traditional antibiotic treatment. Successfull control of the infection requires an early identification of patients at risk.

Epidemiología de las infecciones bacterianas en pacientes con cirrosis hepática, experiencia de un centro español de atención terciaria / Epidemiology of bacterial infections in patients with liver cirrhosis. Experience in a Spanish tertiary health center

Introducción. Las infecciones bacterianas representan una complicación grave de la cirrosis. En los últimos años se han observado cambios en el espectro microbiológico de estas infecciones, fundamentalmente, el aumento de infecciones por gérmenes multirresistentes. Objetivo. Establecer la proporción de infecciones por microorganismos multirresistentes en pacientes cirróticos ingresados en un centro de atención de Madrid, y analizar su epidemiología, factores de riesgo e impacto clínico. Materiales y métodos. Se hizo un estudio retrospectivo en el cual se evaluaron 294 pacientes hospitalizados por infección bacteriana en el Hospital General Universitario Gregorio Marañón de Madrid, entre junio de 2011 y junio de 2013. Resultados. Se aislaron 310 microorganismos de 223 pacientes; 109 (35,2 %) eran Gram positivos, 167 (53,9 %), Gram negativos, y 34 (11 %), hongos. El agente etiológico más frecuente fue Escherichia coli (98 aislamientos). Las infecciones se habían adquirido en la comunidad en 22,9 % de los casos, se asociaron con la atención de salud en 38,1 % y se adquirieron durante la estancia hospitalaria en 39 %. Los pacientes con aislamientos multirresistentes desarrollaron con más frecuencia choque séptico (p=0,05), y presentaron peor función hepática y alta mortalidad durante la estancia hospitalaria (p=0,017). El ingreso previo, el uso de antibióticos en los 60 días anteriores, la adquisición de la infección en el hospital o asociada a un ingreso reciente y el aislamiento de bacterias en los cultivos de control, se determinaron como posibles factores de riesgo para el desarrollo de la infección multirresistente. Discusión. Los resultados del estudio confirmaron que el espectro microbiológico de las infecciones bacterianas en pacientes con cirrosis ha sufrido importantes cambios. Las infecciones por gérmenes multirresistentes causan infecciones con gran morbimortalidad y el fracaso del tratamiento antibiótico habitual. Para controlarlas de forma eficaz, es imprescindible detectar precozmente a aquellos pacientes con factores de riesgo.

Introduction: Bacterial infections represent a serious complication of liver cirrhosis. Traditionally, Gram negative bacteria have been described as the microorganisms responsible for the majority of the infections. However, in the past few years, changes in the microbiological spectrum have been described, and multiresistant bacteria are observed more frequently. Objective: To assess the proportion of patients with infections caused by multiresistant bacteria admitted to our hospital, and to obtain information about their epidemiology, risk factors and clinical impact. Materials and methods: We performed a retrospective evaluation of 294 cirrhotic patients admitted to our unit due to infection between June, 2011, and June, 2013. Results: We isolated 310 microorganisms from 294 patients; 109 (35.2%) were Gram positive, 167 (53.9%), Gram negative, and 34, fungi (11%). As for the microbiological agents, the most frequent was Escherichia coli (98 isolations). The infection was community-acquired in 22.9% of cases, healthcare-associated in 38.1% and nosocomial in 39%. Worse liver infections and septic shock were more frequent among patients with multiresistant isolates (p=0.05); and intrahospital mortality was also higher among them (p=0.017). Previous hospital admission, antibiotic treatment 60 days before, nosocomial or healthcare-associated acquisition and bacterial isolation in control cultures were identified as possible risk factors for the development of multiresistant infection. Discussion: The results of our study confirm that important changes have ocurred in the microbiological spectrum of bacterial infections in patients with liver cirrhosis. Multiresistant bacteria are associated with high morbidity and mortality, as well as failure of traditional antibiotic treatment. Successfull control of the infection requires an early identification of patients at risk.

Separation of thorium ions from wolframite and scandium concentrates using graphene oxide.

The separation of rare metals from the ores and commercially available compounds is an important issue due to the need of their high purity in advanced materials and devices. Important examples of two highly important elements that co-exist in the ores are scandium and thorium. Scandium containing ores and consequently also commercially available scandium compounds often contain traces of thorium which is very difficult to separate. We used graphene oxide for the selective sorption of thorium ions from scandium and thorium mixtures originating from the mined ores as well as from commercially available scandium salts. Our results showed that graphene oxide has an extreme affinity towards thorium ions. After the sorption process the graphene oxide contained over 20 wt% of thorium while the amount of scandium sorbed on GO was very low. This phenomenon of high sorption selectivity of graphene oxide can be applied in industry for the purification of various chemicals containing scandium and for separation of thorium containing mixtures. Alternatively, this methodology can be used for preconcentration of thorium from low-grade ores and its further use in the new generation of nuclear reactors.

Synthesis of strongly fluorescent graphene quantum dots by cage-opening buckminsterfullerene.

Graphene quantum dots is a class of graphene nanomaterials with exceptional luminescence properties. Precise dimension control of graphene quantum dots produced by chemical synthesis methods is currently difficult to achieve and usually provides a range of sizes from 3 to 25 nm. In this work, fullerene C60 is used as starting material, due to its well-defined dimension, to produce very small graphene quantum dots (∼2-3 nm). Treatment of fullerene C60 with a mixture of strong acid and chemical oxidant induced the oxidation, cage-opening, and fragmentation processes of fullerene C60. The synthesized quantum dots were characterized and supported by LDI-TOF MS, TEM, XRD, XPS, AFM, STM, FTIR, DLS, Raman spectroscopy, and luminescence analyses. The quantum dots remained fully dispersed in aqueous suspension and exhibited strong luminescence properties, with the highest intensity at 460 nm under a 340 nm excitation wavelength. Further chemical treatments with hydrazine hydrate and hydroxylamine resulted in red- and blue-shift of the luminescence, respectively.

Octreotide long-active release in the treatment of gastrointestinal bleeding due to vascular malformations: Cost-effectiveness study.

INTRODUCTION: Gastrointestinal hemorrhage due to vascular malformations has a negative impact on patients´ quality of life and consumes an important quantity of resources. OBJECTIVE: Analyze the cost-effectiveness of long-active releasing octreotide (OCT-LAR) in the treatment of gastrointestinal haemorrhage secondary to vascular malformations. MATERIAL AND METHODS: Retrospective study, including 19 pacients that were treated with mensual injections of OCTLAR between 2008-2013. The number of blood transfusions, hemoglobin levels, hospital admissions and possible side effects during the year before treatment and the year after the start of the treatment were assessed, and cost-effectiveness was analyzed. RESULTS: After the beginning of the treatment with OCTLAR, complete response was observed in 7 patients (36.8 %), partial response in 7 patients (36.8 %) and 5 patients (26.3 %) continued to require admissions, blood transfusions and/or endoscopic treatment. We observed significant reduction in the length of admission per year (in days) before and after the start of the treatment (22.79 versus 2.01 days, p < 0.0001) as well as in the number of blood transfusions administered (11.19 versus 2.55 blood transfusions per year, p = 0.002). The mean haemoglobin levels increased from 6.9 g/dl to 10.62 g/dl (p < 0.0001). We observed reduction of costs of 61.5 % between the two periods (from 36,072.35 € to 13,867.57 € per patient and year, p = 0.01). No side effects related to treatment were described. CONCLUSION: In conclusion, OCT-LAR seems to be a costefficient and safe pharmacological treatment of gastrointestinal haemorrhage secondary to vascular malformations, mainly in patients in whom endoscopic or surgical treatment is contraindicated.

Octreótido de acción prolongada (LAR) en el tratamiento de hemorragia digestiva por lesiones vasculares: estudio de coste-eficiencia / Octreotide long-active release in the treatment of gastrointestinal bleeding due to vascular malformations: cost-effectiveness study

INTRODUCCIÓN: la hemorragia digestiva por lesiones vasculares (HDLV) deteriora la calidad de vida de los pacientes y requiere el consumo de una importante cantidad de recursos. OBJETIVO: analizar la coste-eficiencia de octreótido de depósito (OCT-LAR) en el tratamiento de hemorragia gastrointestinal por lesiones vasculares. MATERIAL Y MÉTODOS: estudio retrospectivo, incluyendo a 19 pacientes que fueron tratados con inyecciones mensuales de OCTLAR entre los años 2008-2013. Se revisaron los requerimientos transfusionales, niveles de hemoglobina, necesidad de ingreso hospitalario y posibles efectos secundarios en el año previo y posterior al inicio del tratamiento, se analizó la coste-eficiencia. RESULTADOS: tras el inicio de OCT-LAR observamos respuesta completa en 7 pacientes (36,8 %), parcial en otros 7 pacientes (36,8 %) y 5 pacientes (26,3 %) siguieron precisando ingresos, trasfusiones de hemoderivados y/o tratamiento endoscópico. Observamos disminución significativa de los días de ingreso al año, antes y después de tratamiento (22,79 vs. 2,01 días, p < 0,0001) y del número de concentrados de hematíes transfundidos (11,19 vs. 2,55 concentrados de hematíes por paciente/año, p = 0,002). La media de hemoglobina mejoró de 6,95 a 10,62 g/dl (p < 0,0001). Observamos una reducción del 61,5 % del coste entre los dos periodos (de 36.072,35 Euros a 13.867,57 Euros por paciente/ año, p = 0,01). No se observaron efectos secundarios asociados al tratamiento. CONCLUSIÓN: en conclusión, OCT-LAR parecer ser un tratamiento farmacológico coste-eficiente y seguro para la hemorragia digestiva secundaria a malformaciones vasculares, especialmente en pacientes no subsidiaros de tratamiento endoscópico o quirúrgico

INTRODUCTION: Gastrointestinal hemorrhage due to vascular malformations has a negative impact on patients' quality of life and consumes an important quantity of resources. OBJECTIVE: Analyze the cost-effectiveness of long-active releasing octreotide (OCT-LAR) in the treatment of gastrointestinal haemorrhage secondary to vascular malformations. MATERIAL AND METHODS: Retrospective study, including 19 pacients that were treated with mensual injections of OCTLAR between 2008-2013. The number of blood transfusions, hemoglobin levels, hospital admissions and possible side effects during the year before treatment and the year after the start of the treatment were assessed, and cost-effectiveness was analyzed. RESULTS: After the beginning of the treatment with OCTLAR, complete response was observed in 7 patients (36.8 %), partial response in 7 patients (36.8 %) and 5 patients (26.3 %) continued to require admissions, blood transfusions and/or endoscopic treatment. We observed significant reduction in the length of admission per year (in days) before and after the start of the treatment (22.79 versus 2.01 days, p < 0.0001) as well as in the number of blood transfusions administered (11.19 versus 2.55 blood transfusions per year, p = 0.002). The mean haemoglobin levels increased from 6.9 g/dl to 10.62 g/dl (p < 0.0001). We observed reduction of costs of 61.5 % between the two periods (from 36,072.35 Euros to 13,867.57 Euros per patient and year, p = 0.01). No side effects related to treatment were described. CONCLUSION: In conclusion, OCT-LAR seems to be a costefficient and safe pharmacological treatment of gastrointestinal haemorrhage secondary to vascular malformations, mainly in patients in whom endoscopic or surgical treatment is contraindicated

Towards graphene iodide: iodination of graphite oxide.

Halogenated graphene derivatives are interesting owing to their outstanding physical and chemical properties. In this paper, we present various methods for the synthesis of iodinated graphene derivatives by the iodination of graphite oxides prepared according to either the Hummers or Hofmann method. Both graphite oxides were iodinated by iodine or hydroiodic acid under reflux or in an autoclave at elevated temperatures (240 °C) and pressures (over 100 bar). The influence of both graphite oxide precursors on the properties of resulting iodinated graphenes was investigated by various techniques, including SEM, SEM-EDS, high-resolution XPS, FTIR, STA, and Raman spectroscopy. Electrical resistivity was measured by a standard four point technique. In addition, the electrochemical properties were investigated by cyclic voltammetry. Although the iodinated graphenes were structurally similar, they had remarkably different concentrations of iodine. The most highly iodinated graphenes (iodine concentration above 30 wt%) exhibited relatively high C/O ratios, confirming high degrees of reduction. Iodine is incorporated in the form of covalent bonds to carbon atoms or as polyiodide anions non-covalently bonded through the charge transfer reaction with the graphene framework. Iodinated graphenes with such properties could be used as the starting material for further chemical modifications or as flame-retardant additives.

Mucormicosis cutánea como complicación poco frecuente de trasplante hepático / Cutaneous mucormycosis as a rare complication of a liver transplantation

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Uranium- and thorium-doped graphene for efficient oxygen and hydrogen peroxide reduction.

Oxygen reduction and hydrogen peroxide reduction are technologically important reactions in the fields of energy generation and sensing. Metal-doped graphenes, where metal serves as the catalytic center and graphene as the high area conductor, have been used as electrocatalysts for such applications. In this paper, we investigated the use of uranium-graphene and thorium-graphene hybrids prepared by a simple and scalable method. The hybrids were synthesized by the thermal exfoliation of either uranium- or thorium-doped graphene oxide in various atmospheres. The synthesized graphene hybrids were characterized by high-resolution XPS, SEM, SEM-EDS, combustible elemental analysis, and Raman spectroscopy. The influence of dopant and exfoliation atmosphere on electrocatalytic activity was determined by electrochemical measurements. Both hybrids exhibited excellent electrocatalytic properties toward oxygen and hydrogen peroxide reduction, suggesting that actinide-based graphene hybrids have enormous potential for use in energy conversion and sensing devices.