Vertical graphene nanowalls supported hybrid W2C/WOx composite material as an efficient non-noble metal electrocatalyst for hydrogen evolution.

Research for the development of noble metal-free electrodes for hydrogen evolution has blossomed in recent years. Transition metal carbides compounds, such as W2C, have been considered as a promising alternative to replace Pt-family metals as electrocatalysts towards hydrogen evolution reaction (HER). Moreover, hybridization of TMCs with graphene nanostructures has emerged as a reliable strategy for the preparation of compounds with high surface to volume ratio and abundant active sites. The present study focuses in the preparation of tungsten carbide/oxide compounds deposited in a three-dimensional vertical graphene nanowalls (VGNW) substrate via chemical vapor deposition, magnetron sputtering and thermal annealing processes. Structural and chemical characterization reveals the partial carburization and oxidation of the W film sputtered on the VGNWs, due to C and O migration from VGNWs towards W during the high temperature annealing process. Electrochemical characterization shows the enhanced performance of the nanostructured hybrid W2C/WOx on VGNW compound towards HER, when compared with planar W2C/WOx films. The W2C/WOx nanoparticles on VGNWs require an overpotential of -252 mV for the generation of 10 mA cm-2. Chronoamperometry tests in high overpotentials reveal the compounds stability while sustaining high currents, in the order of hundreds of mA. Post-chronoamperometry test XPS characterization unveils the formation of a W hydroxide layer which favours hydrogen evolution in acidic electrolytes. We aspire that the presented insights can be valuable for those working on the preparation of hybrid electrodes for electrochemical processes.

Processing and Functionalization of Vertical Graphene Nanowalls by Laser Irradiation.

The processing of vertical graphene nanowalls (VGNWs) via laser irradiation is proposed as a means to modulate their physicochemical properties. The effects of the number of applied pulses and fluence of each pulse are examined. Raman spectroscopy studies the effect of irradiation on the chemical structure of the VGNWs. Results show a decrease in density of defects and number of layers, which points toward a mechanism including evaporation of amorphous or loosely bonded C from defective points and recrystallization of graphene. Moreover, the effect of laser irradiation parameters on the morphology of Mo thin films deposited on VGNWs is investigated. The received thermal dosage results in the formation of particles. In this case, the number of pulses and pulse fluence are found to affect the size and distribution of these particles. The study provides a novel approach for the functionalization of VGNWs via laser irradiation, which can be extended to other graphene-based nanostructures.

Advancements in Plasma-Enhanced Chemical Vapor Deposition for Producing Vertical Graphene Nanowalls.

In recent years, vertical graphene nanowalls (VGNWs) have gained significant attention due to their exceptional properties, including their high specific surface area, excellent electrical conductivity, scalability, and compatibility with transition metal compounds. These attributes position VGNWs as a compelling choice for various applications, such as energy storage, catalysis, and sensing, driving interest in their integration into next-generation commercial graphene-based devices. Among the diverse graphene synthesis methods, plasma-enhanced chemical vapor deposition (PECVD) stands out for its ability to create large-scale graphene films and VGNWs on diverse substrates. However, despite progress in optimizing the growth conditions to achieve micrometer-sized graphene nanowalls, a comprehensive understanding of the underlying physicochemical mechanisms that govern nanostructure formation remains elusive. Specifically, a deeper exploration of nanometric-level phenomena like nucleation, carbon precursor adsorption, and adatom surface diffusion is crucial for gaining precise control over the growth process. Hydrogen's dual role as a co-catalyst and etchant in VGNW growth requires further investigation. This review aims to fill the knowledge gaps by investigating VGNW nucleation and growth using PECVD, with a focus on the impact of the temperature on the growth ratio and nucleation density across a broad temperature range. By providing insights into the PECVD process, this review aims to optimize the growth conditions for tailoring VGNW properties, facilitating applications in the fields of energy storage, catalysis, and sensing.

Hybrid Nanostructured Compounds of Mo2C on Vertical Graphene Nanoflakes for a Highly Efficient Hydrogen Evolution Reaction.

Organizing a post-fossil fuel economy requires the development of sustainable energy carriers. Hydrogen is expected to play a significant role as an alternative fuel as it is among the most efficient energy carriers. Therefore, nowadays, the demand for hydrogen production is increasing. Green hydrogen produced by water splitting produces zero carbon emissions but requires the use of expensive catalysts. Therefore, the demand for efficient and economical catalysts is constantly growing. Transition-metal carbides, and especially Mo2C, have attracted great attention from the scientific community since they are abundantly available and hold great promises for efficient performance toward the hydrogen evolution reaction (HER). This study presents a bottom-up approach for depositing Mo carbide nanostructures on vertical graphene nanowall templates via chemical vapor deposition, magnetron sputtering, and thermal annealing processes. Electrochemical results highlight the importance of adequate loading of graphene templates with the optimum amount of Mo carbides, controlled by both deposition and annealing time, to enrich the available active sites. The resulting compounds exhibit exceptional activities toward the HER in acidic media, requiring overpotentials of 82 mV at -10 mA/cm2 and demonstrating a Tafel slope of 56 mV/dec. The high double-layer capacitance and low charge transfer resistance of these Mo2C on GNW hybrid compounds are the main causes of the enhanced HER activity. This study is expected to pave the way for the design of hybrid nanostructures based on nanocatalyst deposition on three-dimensional graphene templates.

Boost of Charge Storage Performance of Graphene Nanowall Electrodes by Laser-Induced Crystallization of Metal Oxide Nanostructures.

Major research efforts are being carried out for the technological advancement to an energetically sustainable society. However, for the full commercial integration of electrochemical energy storage devices, not only materials with higher performance should be designed and manufactured but also more competitive production techniques need to be developed. The laser processing technology is well extended at the industrial sector for the versatile and high throughput modification of a wide range of materials. In this work, a method based on laser processing is presented for the fabrication of hybrid electrodes composed of graphene nanowalls (GNWs) coated with different transition-metal oxide nanostructures for electrochemical capacitor (EC) applications. GNW/stainless steel electrodes grown by plasma enhanced chemical vapor deposition were decorated with metal oxide nanostructures by means of their laser surface processing while immersed in aqueous organometallic solutions. The pseudocapacitive nature of the laser-induced crystallized oxide materials prompted an increase of the GNW electrodes' capacitance by 3 orders of magnitude, up to ca. 28 F/cm3 at 10 mV/s, at both the positive and negative voltages. Finally, asymmetric aqueous and solid-state ECs revealed excellent stability upon tens of thousands of charge-discharge cycles.

Homogeneous Fe2O3 coatings on carbon nanotube structures for supercapacitors.

The combination of carbon nanotubes with transition metal oxides can exhibit complementary charge storage properties for use as electrode materials for next generation energy storage devices. One of the biggest challenges so far is to synthesize homogeneous oxide coatings on carbon nanotube structures preserving their integrity. Here we present the formation of conformal coatings of Fe2O3 on vertically aligned carbon nanotubes obtained by atomic layer deposition. We investigate the effect of pristine, nitrogen plasma and water plasma treated carbon nanotube surfaces on the ALD-growth of Fe2O3 using ferrocene and ozone precursors. The surface morphology, coating thickness, microstructure and surface chemistry of iron oxide-carbon nanotube composites and their ultimate influence on the electrochemical behavior of the composites are evaluated. The most effective surface functionalization is that achieved by H2O plasma treatment, whereas untreated carbon nanotubes, despite the lack of active sites in the starting pristine surface, can be coated with an inhomogeneous Fe2O3 film.

Super-Capacitive Performance of Manganese Dioxide/Graphene Nano-Walls Electrodes Deposited on Stainless Steel Current Collectors.

Graphene nano-walls (GNWs) are promising materials that can be used as an electrode in electrochemical devices. We have grown GNWs by inductively-coupled plasma-enhanced chemical vapor deposition on stainless steel (AISI304) substrate. In order to enhance the super-capacitive properties of the electrodes, we have deposited a thin layer of MnO2 by electrodeposition method. We studied the effect of annealing temperature on the electrochemical properties of the samples between 70 °C and 600 °C. Best performance for supercapacitor applications was obtained after annealing at 70 °C with a specific capacitance of 104 F g-1 at 150 mV s-1 and a cycling stability of more than 14k cycles with excellent coulombic efficiency and 73% capacitance retention. Electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements reveal fast proton diffusion (1.3 × 10-13 cm²·s-1) and surface redox reaction after annealing at 70 °C.

The Fanconi anemia DNA damage repair pathway in the spotlight for germline predisposition to colorectal cancer.

Colorectal cancer (CRC) is one of the most common neoplasms in the world. Fanconi anemia (FA) is a very rare genetic disease causing bone marrow failure, congenital growth abnormalities and cancer predisposition. The comprehensive FA DNA damage repair pathway requires the collaboration of 53 proteins and it is necessary to restore genome integrity by efficiently repairing damaged DNA. A link between FA genes in breast and ovarian cancer germline predisposition has been previously suggested. We selected 74 CRC patients from 40 unrelated Spanish families with strong CRC aggregation compatible with an autosomal dominant pattern of inheritance and without mutations in known hereditary CRC genes and performed germline DNA whole-exome sequencing with the aim of finding new candidate germline predisposition variants. After sequencing and data analysis, variant prioritization selected only those very rare alterations, producing a putative loss of function and located in genes with a role compatible with cancer. We detected an enrichment for variants in FA DNA damage repair pathway genes in our familial CRC cohort as 6 families carried heterozygous, rare, potentially pathogenic variants located in BRCA2/FANCD1, BRIP1/FANCJ, FANCC, FANCE and REV3L/POLZ. In conclusion, the FA DNA damage repair pathway may play an important role in the inherited predisposition to CRC.

Diagnóstico y manejo del paciente adulto con diabetes tipo 1A al inicio de la enfermedad / Diagnosis and management of an adult patient with type 1A diabetes at disease onset

La diabetes tipo1 (DM1) es una enfermedad autoinmune crónica en la que se produce una destrucción progresiva de las células β pancreáticas que conduce a una deficiencia absoluta de insulina.El manejo al principio incluye educación diabetológica básica (administración de insulina, determinación de glucemia capilar y cetonuria, prevención y manejo de la hipoglicemia...). Mediante la instauración de un tratamiento intensivo con insulina se persigue el objetivo de mantener los niveles de glucemia lo más próximos a la normalidad de forma segura, evitando la aparición de hipoglucemias. Se recomienda el cribado de la enfermedad tiroidea y celíaca al inicio, pero no la determinación de los anticuerpos antipancreáticos. La prueba de la tolerancia oral a la comida mixta es la de elección para valorar la función pancreática, pero no se utiliza de forma rutinaria en la práctica clínica habitual y suele reservarse para estudios de intervención al inicio de la DM1

Type 1 diabetes mellitus is a chronic, autoimmune disease, where specific pancreatic β-cell destruction leads to complete insulin deficiency.Management of the patient at diagnosis includes patient education (training in insulin self-injection, self-monitoring of glucose and ketone levels, prevention and management of hypoglycaemia…) and intensive insulin treatment, aimed at achieving glucose concentrations as close to normal as safely possible and avoiding hypoglycaemia. Screening for associated thyroid and coeliac diseases is recommended at the onset of type1 diabetes. Pancreatic auto-antibody measurement, however, is only recommended in case of diagnostic uncertainly. The measurement of stimulated C-peptide after a mixed meal is the reference method to assess endogenous insulin production, although its use is currently limited to intervention trials

Pregnancy-associated plasma protein-A is related to gender and to adipocytokine levels: results of the Health Survey of Catalonia.

OBJECTIVE: Pregnancy-associated plasma protein-A (PAPP-A) is a protease promoting IGF1 tissue availability and considered as a new biomarker of cardiovascular disease. AIM: To evaluate the relationship between PAPP-A concentrations and anthropometric variables, physical activity, smoking status, glucose homoeostasis and adipocytokines in healthy adults. DESIGN AND METHODS: One hundred and forty-nine subjects (77 women; mean age 39·7 ± 14 years; mean BMI 23·7 ± 1·9 kg/m(2) ) were randomly selected from 8000 adults of The Health Survey of Catalonia. Possible effects of gender, age, body composition, smoking status, physical activity, glucose homoeostasis and adipocytokines on PAPP-A concentrations were assessed. RESULTS: Pregnancy-associated plasma protein-A was significantly higher in men than in women [1·04 (0·61-0·44) vs 0·61 (0·41-0·90) µIU/ml; P < 0·0001]; there were no differences in relation to physical activity or smoking status. PAPP-A showed a negative correlation with leptin in men (P = 0·01) and women (P = 0·05), and a positive correlation with adiponectin (P = 0·006) in women and a trend (P = 0·073) in men. Homoeostasis model assessment of insulin resistance (HOMA-IR) showed a negative correlation with PAPP-A only in women (P = 0·019). No association was found with blood pressure, IGF1, lipids or glucose in either gender. When a multiple regression analysis was performed including gender, age, BMI, waist-hip ratio, HOMA-IR, adiponectin and leptin as confounders, PAPP-A was independently correlated with adiponectin (ß = 0·23; P = 0·02) and leptin (ß = -0·33; P = 0·04). CONCLUSIONS: Our study shows a sexual dimorphism of PAPP-A, and a possible influence of leptin and adiponectin on its concentrations in healthy subjects. The mechanisms responsible for this relationship remain to be determined.

Long-term (72 hours) preservation of rat lungs.

OBJECTIVE: We sought to investigate whether the addition of ethanol to a preservation solution (as an antifreeze agent) might allow a reduction of the storage temperature to 0 degrees C without causing freezing damage and improve lung function after prolonged (72 hours) ischemia. METHODS: Lungs from Sprague-Dawley rats were ventilated and perfused ex vivo at 37 degrees C for 60 minutes in the following experimental groups: (1) the no ischemia and reperfusion (no I-R) group (n = 7), in which lungs were studied immediately after harvesting; (2) the LPD24 (n = 7) and (3) LPD72 (n = 8) groups, in which, after harvesting, lungs were flushed and immersed in low-potassium dextran solution and stored deflated at 10 degrees C for 24 and 72 hours, respectively, until reperfusion; and (4) the TEST72 group (n = 9), in which lungs were flushed and immersed in Krebs-Henseleit buffer with added ethanol (10 mL/L) after harvesting and stored deflated at 0 degrees C for 72 hours until reperfusion. RESULTS: Compared with the no I-R group, the other 3 groups had worse lung function, higher lung water content, and evidence of cell injury at reperfusion (P <.01). However, lung function at reperfusion (assessed on the basis of either effluent Po(2), peak airway pressure, or mean arterial pulmonary pressure) was better (P <.01) in the TEST72 group than in the LPD24 or LPD72 groups. Paradoxically, lung cell structure was better preserved in the LPD24 group than in the TEST72 group (or the LPD72 group). CONCLUSIONS: In this experimental model of rat lung ischemia-reperfusion injury, a low preservation temperature (0 degrees C) combined with the addition of ethanol to the preservation solution improves lung function at reperfusion after 72 hours of ischemia but fails to maintain lung cell structure.