Structural Defects on Graphene Generated by Deposition of CoO: Effect of Electronic Coupling of Graphene.

Understanding the interactions in hybrid systems based on graphene and functional oxides is crucial to the applicability of graphene in real devices. Here, we present a study of the structural defects occurring on graphene during the early stages of the growth of CoO, tailored by the electronic coupling between graphene and the substrate in which it is supported: as received pristine graphene on polycrystalline copper (coupled), cleaned in ultra-high vacuum conditions to remove oxygen contamination, and graphene transferred to SiO2/Si substrates (decoupled). The CoO growth was performed at room temperature by thermal evaporation of metallic Co under a molecular oxygen atmosphere, and the early stages of the growth were investigated. On the decoupled G/SiO2/Si samples, with an initial low crystalline quality of graphene, the formation of a CoO wetting layer is observed, identifying the Stranski-Krastanov growth mode. In contrast, on coupled G/Cu samples, the Volmer-Weber growth mechanism is observed. In both sets of samples, the oxidation of graphene is low during the early stages of growth, increasing for the larger coverages. Furthermore, structural defects are developed in the graphene lattice on both substrates during the growth of CoO, which is significantly higher on decoupled G/SiO2/Si samples mainly for higher CoO coverages. When approaching the full coverage on both substrates, the CoO islands coalesce to form a continuous CoO layer with strip-like structures with diameters ranging between 70 and 150 nm.

Exploring plastic biofilm formation and Escherichia coli colonisation in marine environments.

Microorganisms, including potential pathogens, can colonise plastic surfaces in aquatic environments. This study investigates the colonisation of plastic pellets by Escherichia coli (E. coli) as a proxy for faecal pathogens in aquatic environments. Plastic pellets from a polluted beach were placed in seawater aquaria spiked with E. coli. Diverse bacteria, primarily from the Proteobacteria phylum, rapidly colonised the pellets within 24 h, with notable species known for plastic or hydrocarbon degradation. Over 26 days, biofilms formed on the plastic surfaces, reaching bacterial populations of up to 6.8·105 gene copies (gc) of the 16S rRNA mm-2. E. coli, was detected in the pellets for up to 7 days using culture methods, exhibiting varying attachment densities regardless of source or environmental factors. The study highlights plastic biofilms as reservoirs for E. coli, contributing to the survival and persistence of faecal bacteria in aquatic systems. These findings deepen our understanding of the risks associated with plastic pollution in marine settings, offering insights into the behaviour of faecal indicators and their implications for water quality assessments, while providing valuable information on potential pathogen dissemination within plastic-associated microbial communities.

Numerical Simulation of an Inverted Perovskite Solar Cell Using a SiOx Layer as Down-Conversion Energy Material to Improve Efficiency and Stability.

Inverted perovskite solar cells (PSCs) have gained much attention due to their low hysteresis effect, easy fabrication, and good stability. In this research, an inverted perovskite solar cell ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Ag structure was simulated and optimized using SCAPS-1D version 3.3.10 software. The influence on the device of parameters, including perovskite thickness, total defect density, series and shunt resistances, and operating temperature, are discussed and analyzed. With optimized parameters, the efficiency increased from 13.47% to 18.33%. Then, a new SiOx/ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Ag device was proposed which includes a silicon-rich oxide (SiOx) layer. This material was used as the down-conversion energy material, which converts high-energy photons (ultraviolet UV light) into low-energy photons (visible light), improving the stability and absorption of the device. Finally, with SiOx, we obtained an efficiency of 22.46% in the simulation. Therefore, the device with the SiOx layer is the most suitable as it has better values for current density-voltage output and quantum efficiency than the device without SiOx.

Performance of bacterial and mitochondrial qPCR source tracking methods: A European multi-center study.

With the advent of molecular biology diagnostics, different quantitative PCR assays have been developed for use in Source Tracking (ST), with none of them showing 100% specificity and sensitivity. Most studies have been conducted at a regional level and mainly in fecal slurry rather than in animal wastewater. The use of a single molecular assay has most often proven to fall short in discriminating with precision the sources of fecal contamination. This work is a multicenter European ST study to compare bacterial and mitochondrial molecular assays and was set to evaluate the efficiency of nine previously described qPCR assays targeting human-, cow/ruminant-, pig-, and poultry-associated fecal contamination. The study was conducted in five European countries with seven fecal indicators and nine ST assays being evaluated in a total of 77 samples. Animal fecal slurry samples and human and non-human wastewater samples were analyzed. Fecal indicators measured by culture and qPCR were generally ubiquitous in the samples. The ST qPCR markers performed at high levels in terms of quantitative sensitivity and specificity demonstrating large geographical application. Sensitivity varied between 73% (PLBif) and 100% for the majority of the tested markers. On the other hand, specificity ranged from 53% (CWMit) and 97% (BacR). Animal-associated ST qPCR markers were generally detected in concentrations greater than those found for the respective human-associated qPCR markers, with mean concentration for the Bacteroides qPCR markers varying between 8.74 and 7.22 log10 GC/10 mL for the pig and human markers, respectively. Bacteroides spp. and mitochondrial DNA qPCR markers generally presented higher Spearman's rank coefficient in the pooled fecal samples tested, particularly the human fecal markers with a coefficient of 0.79. The evaluation of the performance of Bacteroides spp., mitochondrial DNA and Bifidobacterium spp. ST qPCR markers support advanced pollution monitoring of impaired aquatic environments, aiming to elaborate strategies for target-oriented water quality management.

Semiempirical Two-Dimensional Model of the Bipolar Resistive Switching Process in Si-NCs/SiO2 Multilayers.

In this work, the SET and RESET processes of bipolar resistive switching memories with silicon nanocrystals (Si-NCs) embedded in an oxide matrix is simulated by a stochastic model. This model is based on the estimation of two-dimensional oxygen vacancy configurations and their relationship with the resistive state. The simulation data are compared with the experimental current-voltage data of Si-NCs/SiO2 multilayer-based memristor devices. Devices with 1 and 3 Si-NCs/SiO2 bilayers were analyzed. The Si-NCs are assumed as agglomerates of fixed oxygen vacancies, which promote the formation of conductive filaments (CFs) through the multilayer according to the simulations. In fact, an intermediate resistive state was observed in the forming process (experimental and simulated) of the 3-BL device, which is explained by the preferential generation of oxygen vacancies in the sites that form the complete CFs, through Si-NCs.

microRNA sequencing for biomarker detection in the diagnosis, classification and prognosis of Diffuse Large B Cell Lymphoma.

Despite being considered a single disease, Diffuse Large B Cell Lymphoma (DLBCL) presents with variable backgrounds, which results in heterogeneous outcomes among patients, with 40% of them still having primary refractory disease or relapse. Thus, novel biomarkers are needed. In addition, multiple factors regarding its pathogenesis remain unclear. In this context, recent investigations point to the relevance of microRNAs (miRNAs) in cancer. However, regarding DLBCL, there is inconsistency in the data reported. Therefore, in this work, the main goals were to determine a miRNA set with utility as biomarkers for DLBCL diagnosis, classification, prognosis and treatment response, as well as to decipher the mechanism of action of deregulated miRNAs in the origin of the disease. We analyzed miRNA expression in a cohort of 78 DLBCL patients and 17 controls using small RNA sequencing and performed a miRNA-mRNA interaction network analysis. This way, we were able to define new miRNA expression signatures for diagnosis, classification, treatment response and prognosis, and we identified plausible mechanisms of action by which deregulated miRNAs could be involved in DLBCL pathogenesis. In summary, our study remarks that miRNAs could play an important role in DLBCL.

Two-Dimensional Self-Assembly Driven by Intermolecular Hydrogen Bonding in Benzodi-7-azaindole Molecules on Au(111).

The control of molecular structures at the nanoscale plays a critical role in the development of materials and applications. The adsorption of a polyheteroaromatic molecule with hydrogen bond donor and acceptor sites integrated in the conjugated structure itself, namely, benzodi-7-azaindole (BDAI), has been studied on Au(111). Intermolecular hydrogen bonding determines the formation of highly organized linear structures where surface chirality, resulting from the 2D confinement of the centrosymmetric molecules, is observed. Moreover, the structural features of the BDAI molecule lead to the formation of two differentiated arrangements with extended brick-wall and herringbone packing. A comprehensive experimental study that combines scanning tunneling microscopy, high-resolution X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and density functional theory theoretical calculations has been performed to fully characterize the 2D hydrogen-bonded domains and the on-surface thermal stability of the physisorbed material.

Nanocomposites of Silicon Oxides and Carbon: Its Study as Luminescent Nanomaterials.

In this work, hybrid structures formed by nanostructured layers, which contain materials, such as porous silicon (PSi), carbon nanotubes (CNTs), graphene oxide (GO), and silicon-rich oxide (SRO), were studied. The PSi layers were obtained by electrochemical etching over which CNTs and GO were deposited by spin coating. In addition, SRO layers, in which silicon nanocrystals are embedded, were obtained by hot filament chemical vapor deposition (HFCVD) technique. Photoluminescence (PL) spectra were obtained from the hybrid structures with which a comparative analysis was completed among different PL ones. The SRO layers were used to confine the CNTs and GO. The main purpose of making these hybrid structures is to modulate their PL response and obtain different emission energy regions in the PL response. It was found that the PL spectra of the CNTs/SRO and GO/SRO structures exhibit a shift towards high energies compared to those obtained from the PSi layers; likewise, the PSi/CNTs/SRO and PSi/GO/SRO structures show a similar behavior. To identify the different emission mechanisms originated by PSi, GO, CNTs, and SRO, the PL spectra were deconvolved. It was found that the Psi/CNTs/SRO and Psi/GO/SRO structures exhibit a PL shift in respect to the PSi layers, for this reason, the modulation of the PL emission of the structures makes these hybrid structures promising candidates to be applied in the field of photonic and electroluminescent devices.

Detection of faecal bacteria and antibiotic resistance genes in biofilms attached to plastics from human-impacted coastal areas.

Plastics have been proposed as vectors of bacteria as they act as a substrate for biofilms. In this study, we evaluated the abundance of faecal and marine bacteria and antibiotic resistance genes (ARGs) from biofilms adhered to marine plastics. Floating plastics and plastics from sediments were collected in coastal areas impacted by human faecal pollution in the northwestern Mediterranean Sea. Culture and/or molecular methods were used to quantify faecal indicators (E. coli, Enterococci and crAssphage), and the ARGs sulI, tetW and blaTEM and the 16S rRNA were detected by qPCR assays. Pseudomonas and Vibrio species and heterotrophic marine bacteria were also analysed via culture-based methods. Results showed that, plastic particles covered by bacterial biofilms, primarily consisted of marine bacteria including Vibrio spp. Some floating plastics had a low concentration of viable E. coli and Enterococci (42% and 67% of the plastics respectively). Considering the median area of the plastics, we detected an average of 68 cfu E. coli per item, while a higher concentration of E. coli was detected on individual plastic items, when compared with 100 ml of the surrounding water. Using qPCR, we quantified higher values of faecal indicators which included inactive and dead microorganisms, detecting up to 2.6 × 102 gc mm-2. The ARGs were detected in 67-88% of the floating plastics and in 29-57% of the sediment plastics with a concentration of up to 6.7 × 102 gc mm-2. Furthermore, enrichment of these genes was observed in biofilms compared with the surrounding water. These results show that floating plastics act as a conduit for both the attachment and transport of faecal microorganisms. In contrast, low presence of faecal indicators was detected in plastic from seafloor sediments. Therefore, although in low concentrations, faecal bacteria, and potential pathogens, were identified in marine plastics, further suggesting plastics act as a reservoir of pathogens and ARGs.

Acceso a internet en tiempos de pandemia / Internet access in times of pandemic

OBJETIVO: determinar el acceso a internet por parte de estudiantes de la Carrera de Tecnología Médica durante la Pandemia del SARS-COV-2 MÉTODO: estudio descriptivo de corte transversal, realizado en la Carrera de Tecnología Médica de la Universidad Mayor de San Andrés, de cuya institución se tomó en cuenta a 683 estudiantes a quienes se aplicó el Cuestionario de Tecnologías de Información y Comunicación (TIC) de la República de Chile. Una vez obtenidos los datos, los mismos fueron trasladados en el programa estadístico SPSS 24v, para posteriormente realizar dos tipos de análisis: 1) análisis de tipo descriptivo donde se obtuvo las frecuencias y porcentajes de las categorías de estudio y 2) análisis inferencial mediante la obtención del Chi2 (para el cual se estableció la existencia de relación ante un valor p <0,05) y medidas de riesgo como el Odds Ratio (OR). RESULTADOS: el estudio ha determinado que del total de estudiantes encuestados (n=683), 585 (85,7%) acceden a internet, teniendo el mayor número de ellos una red domiciliaria (n=371). Al realizar la relación entre las variables sociodemográficas y el acceso a internet, resulto significativa la variable residencia durante el tiempo de la pandemia del SARS-COV-2, obteniéndose un valor p=0,001. CONCLUSIÓN: la mayor parte de los estudiantes tienen acceso a internet sea por una red domiciliaria o por medio de un teléfono celular; sin embargo, se evidencian limitaciones en cuanto al acceso según el área de residencia actual.

OBJECTIVE: to determine access to the Internet by students of the Medical Technology Career during the SARS-COV-2 Pandemic. METHOD: descriptive cross-sectional study, carried out in the Medical Technology Career at the Universidad Mayor de San Andrés, from which 683 students were taken into account to whom the Questionnaire on Information and Communication Technologies (ICT) of the Republic of Chile was applied. Once the data was obtained, they were transferred in the SPSS 24v statistical program, to subsequently carry out two types of analysis: 1) descriptive analysis where the frequencies and percentages of the study categories were obtained and 2) inferential analysis using the obtaining Chi2 (for which the existence of a relationship was established before a p value <0.05) and risk measures such as the Odds Ratio (OR). RESULTS: The study has determined that of the total number of students surveyed (n = 683), 585 (85.7%) access the internet, the largest number of them having a home network (n = 371). When making the relationship between sociodemographic variables and internet access, the residence variable was significant during the time of the SARS-VOC-2 pandemic, obtaining a p value = 0.001. CONCLUSION: Most students have access to the internet either through a home network or through a cell phone; however, limitations are evident regarding access according to the current area of residence.

Single-Step Protocol for Isolating the Recombinant Extracellular Domain of the Luteinizing Hormone Receptor from the Ovis aries Testis.

The luteinizing hormone receptor (LHR) is a glycoprotein member of the G protein-coupled receptors superfamily. It participates in corpus luteum formation and ovulation in females and acts in testosterone synthesis and spermatogenesis in males. In this study, we extracted RNA from sheep testicles and synthetized the cDNA to amplify the gene lhr-bed. This gene consists of 762 bp and encodes 273 amino acids of the extracellular domain of LHR. The lhr-bed was cloned into pJET1.2/blunt, then subcloned into pCOLD II, and finally, transformed in E. coli BL21 (DE3) cells. Because the induced rLHR-Bed protein was found in the insoluble fraction, we followed a modified purification protocol involving induction at 25 °C, subjection to denaturing conditions, and on-column refolding to increase solubility. We confirmed rLHR-Bed expression by means of Western blot and mass spectrometry analysis. It is currently known that the structure stem-loop 5'UTR on pCOLD II vector is stable at 15 °C. We predicted and obtained RNAfold stability at 25 °C. We successfully obtained the recombinant LHR extracellular domain, with protein yields of 0.2 mg/L, and purity levels of approximately 90%, by means of a single chromatographic purification step. The method described here may be used to obtain large quantities of rLHR-Bed in the future.

Development of Heterojunction c-Si/a-Si1-xCx:H PIN Light-Emitting Diodes.

In this work, we explored the feasibility of the fabrication of PIN light-emitting diodes (LEDs) consisting of heterojunctions of amorphous silicon-carbide (a-Si1-xCx:H) thin films and crystalline silicon wafers (c-Si). The objective is the future development of electro-photonic systems in the same c-Si wafer, containing transistors, sensors, LEDs and waveguides. Two different heterojunction LEDs were fabricated consisting of PIN and PIN+N structures, where a-Si1-xCx:H thin films were used as P-type and I-type layers, while an N-type c-Si substrate was used as an active part of the device. The amorphous layers were deposited by the plasma-enhanced chemical vapor deposition (PECVD) technique at a substrate temperature of 200 °C. The PIN device presented electroluminescence (EL) only in the forward bias, while the PIN+N device presented in both the forward and reverse biases. The EL in reverse bias was possible due to the addition of an N+-type a-Si:H layer between the c-Si substrate and the I-type a-Si1-xCx:H active layer. Likewise, the EL intensity of the PIN+N structure was higher than that of the PIN device in forward bias, indicating that the addition of the N-type a-Si:H layer makes electrons flow more efficiently to the I layer. In addition, both devices presented red EL in the full area, which is observed with the naked eye.

Single versus tandem autologous stem-cell transplantation in patients with newly diagnosed multiple myeloma and high-risk cytogenetics. A retrospective, open-label study of the PETHEMA/Spanish Myeloma Group (GEM).

Tandem ASCT has been suggested as a valid approach to improve the prognosis of patients with MM and HR cytogenetic. In this observational, retrospective study, 213 patients with newly diagnosed MM and HR cytogenetic in 35 hospitals from the Spanish Myeloma Group underwent single or tandem ASCT between January 2015 and December 2019 after induction with VTD/VRD. HR cytogenetic was defined as having ≥1 of the following: del17p, t(4;14), t(14;16) or gain 1q21. More patients in the tandem group had R-ISS 3 and >1 cytogenetic abnormality at diagnosis. With a median follow-up of 31 months (range, 10-82), PFS after single ASCT was 41 months versus 48 months with tandem ASCT (p = 0.33). PFS in patients with del17p undergoing single ASCT was 41 months, while 52% of patients undergoing tandem ASCT were alive and disease free at 48 months. In conclusion, tandem ASCT partly overcomes the bad prognosis of HR cytogenetic.