Low-Temperature Synthesis of Bi2S3 Hierarchical Microstructures via Co-Precipitation and Digestive Process in Aqueous Medium.

Bismuth sulfide (Bi2S3) nanostructures have gained significant attention in the fields of catalysis, optoelectronics, and biomedicine due to their unique physicochemical properties. This paper introduces a simple and cost-effective method for producing Bi2S3 microstructures at low temperatures (25 and 70 °C). These microstructures are formed by the hierarchical self-assembly of Bi2S3 nanoparticles, which are typically 15-40 nm in size. The nanoparticles are synthesized by the co-precipitation of thioglycolic acid, thioacetamide, and bismuth nitrate in water. The study delves into the phase composition and morphological evolution of the microstructures, concerning the chemical composition of the solution and the synthesis temperature. X-ray analysis has confirmed the formation of single-phase bismuthinite Bi2S3. The synthesis process generates primary building blocks in the form of 15-40 nm Bi2S3 nanocrystals, which then go through a hierarchical self-assembly process to produce a range of micrometer-sized structures. A scanning electron microscopy examination revealed that the primary nanoparticles self-assemble into quasi-1D worm-like nanostructures, which then self-assemble to create sponge-shaped microstructures. These structures subsequently self-organize and refine into either flower- or dandelion-like microstructures, mostly depending on the synthesis temperature and the chemistry of the digestion medium.

Nanostructured PbSe Films Deposited by Spray Pyrolysis Using PbSe Colloidal Solutions.

This work describes the spray pyrolysis deposition of PbSe films, using as-prepared PbSe colloids as the starting solution. The PbSe colloids were prepared by using the alkahest approach, where Pb and Se precursors were made to react with the following green polyols: glycerin, ethylene glycol, and propylene glycol, to subsequently spray them onto glass substrates. The results of the characterization indicated that amine or thiol groups-free and single-phase rock-salt cubic PbSe powder was obtained, producing nanocrystals 16-30 nm in size. X-ray diffraction also showed that the PbSe films containing PbSeO3 and PbO·xH2O as impurity phases were produced during the deposition. The morphology of the powders and films was developed by a self-assembly process, in which the primary PbSe nanoparticles self-assemble to produce peanut-like microstructures. Additionally, a non-continuous and porous feature was formed in the thick films. Certain films revealed optical structures characterized by broad- and low-intensity bands resembling an exciton-like behavior. This could be attributed to the presence of nanocrystals with a size less than the Bohr radius, indicating reminiscent quantum effects. The results suggest that the usage of colloidal dispersions as spray solutions represents an effective approach to forming PbSe films, as well as that the synthesis method allows for the elimination of thiol and amine groups before deposition, significantly simplifying the process.

Principales factores relacionados con las infecciones asociadas a la atención en salud en población neonatal entre 2014 a 2020. Revisión sistemática / Main factors related with the acquisition of health care associated infections in the neonatal population between 2014 to 2020. Systematic review

Introducción. Las infecciones asociadas a la atención en salud son un efecto adverso frecuente. Los neonatos son un grupo poblacional afectado debido a su inmadurez inmunitaria. La Organización Mundial de la Salud estima que estas infecciones varían entre 5% a 25% en función del nivel de ingresos de cada país. En Colombia se evidencia un subregistro para estas infecciones, particularmente en los neonatos. Este estudio buscó identificar los factores de riesgo, microorganismos más comunes, y las vías de transmisión y colonización relacionadas a las infecciones asociadas a la atención en salud en neonatos, según lo reportado en la literatura mundial. Metodología. Se realizó una búsqueda sistemática por duplicado, que incluyó pesquisa de artículos, primera lectura y exclusión de duplicados, conciliación entre autores y evaluación de la calidad, en la base de datos PubMed, con artículos publicados entre los años 2014 a 2019. Resultados. El nivel de evidencia y el grado de recomendación fue bueno en general (niveles 1 y 2, recomendación A y B). Los factores de riesgo más comunes fueron la prematuridad y el bajo peso al nacer, el uso de catéter venoso central, ventilación mecánica, estancia hospitalaria prolongada y el uso de antibióticos por largo tiempo. Se reportaron microorganismos de importancia como Staphylococcus coagulasa negativos y Serratia marcenscens, y vías de transmisión y colonización comunes como el torrente sanguíneo, la vía respiratoria, la gastrointestinal y la piel. Conclusión. Las infecciones asociadas a la atención en salud son más frecuentes de lo estimado y se pueden prevenir con la adopción de políticas sanitarias, como son un correcto lavado de manos, la desinfección del ambiente y equipos médicos, un adecuado cuidado de la piel del neonato y protocolos de aislamiento para pacientes con estas infecciones

Introduction. Health care-associated infections are a frequent adverse effect. Neonates are an affected population group due to their immune immaturity. The World Health Organization estimates that these infections vary between 5% to 25% depending on the income level of each country. In Colombia these infections are underreported, particularly in neonates. The aim of this review was to identify the risk factors, the most common microorganisms, and the routes of transmission for these type of infections in neonates, as reported in the world literature. Methodology. A systematic duplicate search was carried out in PubMed, with articles published between 2014 to 2019, which included a search for articles, reading and exclusion of duplicates, reconciliation between authors, and quality assessment. Results. The level of evidence and the grade of recommendation was optimal in general (levels 1 and 2, recommendation A and B). The most common risk factors were prematurity and low birth weight, the use of central venous catheter, mechanical ventilation, prolonged hospital stay, and long-term use of antibiotics. Microorganisms such as coagulase negative Staphylococcus and Serratia marcenscens were reported, and common routes of transmission such as the bloodstream, respiratory tract, gastrointestinal tract, and skin were described. Conclusion. Health care-associated infections are more frequent than estimated, and can be prevented with the adoption of health policies, such as proper hand washing, disinfection of environmental surfaces and medical equipment, an adequate skin care of the neonate, and isolation protocols for patients with these infections

Partial Reversibility of the Cytotoxic Effect Induced by Graphene-Based Materials in Skin Keratinocytes.

In the frame of graphene-based material (GBM) hazard characterization, particular attention should be given to the cutaneous effects. Hence, this study investigates if HaCaT skin keratinocytes exposed to high concentrations of few-layer graphene (FLG) or partially dehydrated graphene oxide (d-GO) for a short time can recover from the cytotoxic insult, measured by means of cell viability, mitochondrial damage and oxidative stress, after GBM removal from the cell medium. When compared to 24 or 72 h continuous exposure, recovery experiments suggest that the cytotoxicity induced by 24 h exposure to GBM is only partially recovered after 48 h culture in GBM-free medium. This partial recovery, higher for FLG as compared to GO, is not mediated by autophagy and could be the consequence of GBM internalization into cells. The ability of GBMs to be internalized inside keratinocytes together with the partial reversibility of the cellular damage is important in assessing the risk associated with skin exposure to GBM-containing devices.

Growth and Self-Assembly of Silicon⁻Silicon Carbide Nanoparticles into Hybrid Worm-Like Nanostructures at the Silicon Wafer Surface.

This work describes the growth of silicon⁻silicon carbide nanoparticles (Si⁻SiC) and their self-assembly into worm-like 1D hybrid nanostructures at the interface of graphene oxide/silicon wafer (GO/Si) under Ar atmosphere at 1000 °C. Depending on GO film thickness, spread silicon nanoparticles apparently develop on GO layers, or GO-embedded Si⁻SiC nanoparticles self-assembled into some-micrometers-long worm-like nanowires. It was found that the nanoarrays show that carbon⁻silicon-based nanowires (CSNW) are standing on the Si wafer. It was assumed that Si nanoparticles originated from melted Si at the Si wafer surface and GO-induced nucleation. Additionally, a mechanism for the formation of CSNW is proposed.

Development of highly faceted reduced graphene oxide-coated copper oxide and copper nanoparticles on a copper foil surface.

This work describes the formation of reduced graphene oxide-coated copper oxide and copper nanoparticles (rGO-Cu2ONPs, rGO-CuNPs) on the surface of a copper foil supporting graphene oxide (GO) at annealing temperatures of 200-1000 °C, under an Ar atmosphere. These hybrid nanostructures were developed from bare copper oxide nanoparticles which grew at an annealing temperature of 80 °C under nitrogen flux. The predominant phase as well as the particle size and shape strongly depend on the process temperature. Characterization with transmission electron microscopy and scanning electron microscopy indicates that Cu or Cu2O nanoparticles take rGO sheets from the rGO network to form core-shell Cu-rGO or Cu2O-rGO nanostructures. It is noted that such ones increase in size from 5 to 800 nm as the annealing temperature increases in the 200-1000 °C range. At 1000 °C, Cu nanoparticles develop a highly faceted morphology, displaying arm-like carbon nanorods that originate from different facets of the copper crystal structure.

Optical and structural characterization of oleic acid-stabilized CdTe nanocrystals for solution thin film processing.

This work presents results of the optical and structural characterization of oleic acid-stabilized cadmium telluride nanocrystals (CdTe-NC) synthesized by an organometallic route. After being cleaned, the CdTe-NC were dispersed in toluene to obtain an ink-like dispersion, which was drop-cast on glass substrate to deposit a thin film. The CdTe-NC colloidal dispersion as well as the CdTe drop-cast thin films were characterized with regard to the optical and structural properties. TEM analysis indicates that the CdTe-NC have a nearly spherical shape (3.5 nm as mean size). Electron diffraction and XRD diffraction analyses indicated the bulk-CdTe face-centered cubic structure for CdTe-NC. An additional diffraction line corresponding to the octahedral Cd3P2 was also detected as a secondary phase, which probably originates by reacting free cadmium ions with trioctylphosphine (the tellurium reducing agent). The Raman spectrum exhibits two broad bands centered at 141.6 and 162.3 cm(-1), which could be associated to the TO and LO modes of cubic CdTe nanocrystals, respectively. Additional peaks located in the 222 to 324 cm(-1) range, agree fairly well with the wavenumbers reported for TO modes of octahedral Cd3P2.

[HGH release after I.M. glucagon injection]. / Respuesta de la hormona del crecimiento (HGH) al glucagón intramuscular

Intramuscular injection of glucagon was used to assess HGH release in 31 normal children and 4 hypopituitary dwarfs. The peak response in controls was obtained at 120 min. with values (nanograms) of 12.93 plus or minus 5.18 (p smaller than 0.0005). Values at 60 and 180 min. were equally significant when compared with basal (7.04 plus or minus 9.24, p smaller than 0.025 and 6.74 plus or minus 6.65, p smaller than 0.001). Hypopituitary dwarfs did not respond to glucagon injection.