Thiophene-Based Covalent Organic Frameworks: Synthesis, Photophysics and Light-Driven Applications

Porous crystalline materials, such as covalent organic frameworks (COFs), have emerged as some of the most important materials over the last two decades due to their excellent physicochemical properties such as their large surface area and permanent, accessible porosity. On the other hand, thiophene derivatives are common versatile scaffolds in organic chemistry. Their outstanding electrical properties have boosted their use in different light-driven applications (photocatalysis, organic thin film transistors, photoelectrodes, organic photovoltaics, etc.), attracting much attention in the research community. Despite the great potential of both systems, porous COF materials based on thiophene monomers are scarce due to the inappropriate angle provided by the latter, which hinders its use as the building block of the former. To circumvent this drawback, researchers have engineered a number of thiophene derivatives that can form part of the COFs structure, while keeping their intrinsic properties. Hence, in the present minireview, we will disclose some of the most relevant thiophene-based COFs, highlighting their basic components (building units), spectroscopic properties and potential light-driven applications

Perovskite-Quantum Dots Interface: Deciphering its Ultrafast Charge Carrier Dynamics

Understanding electron and hole (e,h) transport at semiconductor interfaces is paramount to developing efficientoptoelectronic devices. Halide perovskite/semiconductor quantum dots (QDs) have emerged as smart hybridsystems with a huge potential for light emission and energy conversion. However, the dynamics of generated e-hpairs are not fully understood. Ultrafast UV–VIS transient absorption and THz spectroscopies have enabled us tounravel the processes of the e-h recombination within a hybrid film of methylammonium lead triiodide (MAPbI3)interacting with different amount of PbS/CdS core/shell QDs. To accurately analyze the complex behavior, weapplied a new model for e-h events in this hybrid material. The results obtained with sample having a highconcentration of QDs (7.3 mass percentage) indicate: (i) a large population (92%) of the photogenerated chargecarriers are affected by QDs presence. The main part of these carriers (85% of the total) in perovskite domaindiffuse towards QDs, where they transfer to the interface (electrons) and QD´s valence bands (holes) with rateconstants of 1.2 × 1010s−1and 4.6 × 1010s−1, respectively. 7% of these affected charged entities are excitonsin the perovskite domain in close vicinity of the interface, and show a recombination rate constant of 3.7 × 1010s−1.(ii) The carriers not affected by QDs presence (8%) recombine through known perovskite deactivationchannels. Lowering the QDs mass percentage to 0.24 causes a decrease of electron and hole effective transfer rateconstants, and disappearance of excitons. These results provide clues to improve the performance of perovskite/QD based device

Deciphering the Role of Quantum Dots Size in the Ultrafast Charge Carrier Dynamics at the Perovskite-Quantum Dots Interface

Understanding the behaviour of electrons and holes (e, h) diffusion and transfer at the interfaces of photoexcited hybrid materials at different densities of photoexcited charge carriers is paramount to the development of efficient optoelectronic devices. Nanocomposites formed by methylammonium lead iodide perovskite (MAPbI3) and semiconductor colloidal quantum dots (QDs)are among these hybrid materials under intensive studies. However, the reciprocal influence of the components in the composite material on the temporal evolution of the photoinduced charge carriers is still poorly explored. This study explores the ultrafast temporal behaviour of the photoexcited charge carriers in MAPbI3/PbS QDs films, letting a special attention to the role of the PbS QD size. Armed with fs-time-resolved UV-VIS transient absorption and terahertz techniques, we unravel the effect of different sizes of PbS QDs, embedded in perovskite (PS) host matrix, on the processes of e and h diffusion, transfer to the QDs phase and recombination. While the decays are dominated by e and h transition from PS to QDs, the increase in the size of QDs results in an acceleration of the charge carriers transition processes represented by the total transition rate constants of electrons (ke) and holes (kh). The total ke and kh values change form 0.1and 1 (109 s-1) to 4.5and 22 (109 s-1), respectively. We extract the rate constants of their diffusions (kediff = 2.2 × 1010s-1 and khdiff = 1.1 × 1010 s-1) and transfers to the interfaces (ket = 0.1 to 1.6 × 1010 s-1 and kht = 0.1 to 0.8 × 1010 s-1). Furthermore, the analysis of spectral behavior of PS and PS/QDs upon pumping with different fs-laser fluences indicate the presence and photoformation of excitonic states. The acceleration of such processes decreases the contribution of undesirable charge carriers trapping and non-radiative recombination within PS

Facile Synthesis, Characterization, and Deciphering of Their Ultrafast-to-Slow Photodynamics

InP-based quantum dots (QDs) are an environment-friendly alternative to their heavy metal-ion-based counterparts. Herein we report a simple procedure for synthesizing blue emissive InP QDs using oleic acid and oleylamine as surface ligands, yielding ultrasmall QDs with average sizes of 1.74 and 1.81 nm, respectively. Consecutive thin coating with ZnS increased the size of these QDs to 4.11 and 4.15 nm, respectively, alongside a significant enhancement of their emission intensities centered at ∼410 nm and ∼430 nm, respectively. Pure phase synthesis of these deep-blue emissive QDs is confirmed by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Armed with femtosecond to millisecond time-resolved spectroscopic techniques, we decipher the energy pathways, reflecting the effect of successive ZnS passivation on the charge carrier (electrons and holes) dynamics in the deep-blue emissive InP, InP/ZnS, and InP/ZnS/ ZnS QDs. Successive coating of the InP QDs increases the intraband relaxation times from 200 to 700 fs and the lifetime of the hot electrons from 2 to 8 ps. The lifetime of the cold holes also increase from 1 to 4 ps, and remarkably, the Auger recombination escalates from 15 to 165 ps. The coating also drastically decreases the quenching by the molecular oxygen of the trapped charge carriers at the surfaces of the QDs. Our results provide clues to push further the emission of InP QDs into more energetically spectral regions and to increase the fluorescence quantum yield, targeting the construction of efficient UV-emissive light-emitting devices (LEDs)

Gestión del conocimiento. Perspectiva multidisciplinaria. Volumen 8

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, volumen 8, de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada de acceso abierto a todas las áreas del conocimiento, que cuenta con el esfuerzo de investigadores de varios países del mundo, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico que consoliden la transformación del conocimiento en diferentes escenarios, tanto organizacionales como universitarios, para el desarrollo de habilidades cognitivas del quehacer diario. La gestión del conocimiento es un camino para consolidar una plataforma en las empresas públicas o privadas, entidades educativas, organizaciones no gubernamentales, ya sea generando políticas para todas las jerarquías o un modelo de gestión para la administración, donde es fundamental articular el conocimiento, los trabajadores, directivos, el espacio de trabajo, hacia la creación de ambientes propicios para el desarrollo integral de las instituciones

Spatiotemporal Characteristics of the Largest HIV-1 CRF02_AG Outbreak in Spain: Evidence for Onward Transmissions

Background and Aim: The circulating recombinant form 02_AG (CRF02_AG) is the predominant clade among the human immunodeficiency virus type-1 (HIV-1) non-Bs with a prevalence of 5.97% (95% Confidence Interval-CI: 5.41–6.57%) across Spain. Our aim was to estimate the levels of regional clustering for CRF02_AG and the spatiotemporal characteristics of the largest CRF02_AG subepidemic in Spain.Methods: We studied 396 CRF02_AG sequences obtained from HIV-1 diagnosed patients during 2000–2014 from 10 autonomous communities of Spain. Phylogenetic analysis was performed on the 391 CRF02_AG sequences along with all globally sampled CRF02_AG sequences (N = 3,302) as references. Phylodynamic and phylogeographic analysis was performed to the largest CRF02_AG monophyletic cluster by a Bayesian method in BEAST v1.8.0 and by reconstructing ancestral states using the criterion of parsimony in Mesquite v3.4, respectively.Results: The HIV-1 CRF02_AG prevalence differed across Spanish autonomous communities we sampled from (p < 0.001). Phylogenetic analysis revealed that 52.7% of the CRF02_AG sequences formed 56 monophyletic clusters, with a range of 2–79 sequences. The CRF02_AG regional dispersal differed across Spain (p = 0.003), as suggested by monophyletic clustering. For the largest monophyletic cluster (subepidemic) (N = 79), 49.4% of the clustered sequences originated from Madrid, while most sequences (51.9%) had been obtained from men having sex with men (MSM). Molecular clock analysis suggested that the origin (tMRCA) of the CRF02_AG subepidemic was in 2002 (median estimate; 95% Highest Posterior Density-HPD interval: 1999–2004). Additionally, we found significant clustering within the CRF02_AG subepidemic according to the ethnic origin.Conclusion: CRF02_AG has been introduced as a result of multiple introductions in Spain, following regional dispersal in several cases. We showed that CRF02_AG transmissions were mostly due to regional dispersal in Spain. The hot-spot for the largest CRF02_AG regional subepidemic in Spain was in Madrid associated with MSM transmission risk group. The existence of subepidemics suggest that several spillovers occurred from Madrid to other areas. CRF02_AG sequences from Hispanics were clustered in a separate subclade suggesting no linkage between the local and Hispanic subepidemics

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Dynamics of proton, charge & energy transfers in solutions and within metal-organic frameworks: toward sensing and nanophotonic applications

In this Ph.D. thesis, I have investigated the spectroscopic and photodynamical properties of different molecular systems as well as a series of nanomaterials known as “Metal-Organic Frameworks” (MOFs). I explored in “real time” the photophysical and photochemical processes that take place in the excited state of these systems and I also determined how the environment or different structural changes affect these excited state processes. A brief summary of the obtained results is shown below: 1) The spectroscopic and photophysical properties of (2´-hydroxyphenyl)benzoxazole (HBO) and two amino-derivatives (5A-HBO and 6A-HBO) have been investigated. The presence of the electron-donor group in 5A-HBO and 6A-HBO produces an increment in the electron density of the molecule owing to a photoinduced intramolecular charge transfer (ICT) process. This provokes a decrease in the acidity of -OH group at the electronically first excited state (S1), and thus, the ESIPT process is slowing down. The position of the (-NH2) group in the molecular frame also influences the photoacid properties of the -OH group. When the (-NH2) group is in the 5-position, the -OH group is less photoacid than when the (-NH2) is in the 6-position, and thus, the ESIPT is faster for the latter molecule than for the former. Moreover, the environment, in this case the basicity of the solvents, influences the ESIPT process. For example, in slightly basic solvents (ACN or THF), the ESIPT is not taking place for 5A-HBO, while for 6A-HBO it is occurring in a reversible way. In a less basic solvent (DCM), the ESIPT is reversible for 5A-HBO and irreversible for 6A-HBO. 2) The spectroscopic and photodynamical properties of a series of Zr-based MOFs (Zr-NDC, Zr-NADC (2-35%), Zr-NDC/Tz and Zr-NDC/CN) and their interaction with different molecules were also explored. We have observed the emission of monomers and excimers of naphthalene linkers in Zr-NDC MOF. When part of the naphthalene linkers are functionalized with amino-groups (Zr-NADC) an energy transfer from the excited naphthalene linkers to the amino-functionalized ones are shown. Both MOFs (Zr-NDC and Zr-NADC) exhibits also an ultrafast Ligand-to-Cluster Charge Transfer with the subsequent generation of a long-lived charge-separated state. The generation of this state is fundamental to use these materials as photocatalysts. Taking advantage of the porous structure of Zr-NDC MOF, different organic fluorescent molecules have been entrapped into those pores. By using energy transfer processes from MOF to the encapsulated dyes, we fabricated hybrid materials that emit cool white light with a high quantum yield. As a final goal to fabricate a MOF-LED, the first step was getting and studying a homogenous film. To this end, Zr-NDC and C153@Zr-NDC MOF materials were dispersed in polycarbonate (PC) films. The NDC excimer formation in Zr-NDC as well as the energy transfer from MOF to C153 in C153@Zr-NDC were observed when both materials are embedded in PC films. With this in mind, we fabricated the first Zr-MOF-LEDs and investigated their electroluminescence properties. In this way, we demonstrated that both, the dye encapsulation and the presence of defect in the MOF structure have considerable influence in the device performance. Finally, we also explored the spectroscopic and photodynamical properties of new functionalized Zr-NDC/Tz and Zr-NDC/CN MOFs, and how the presence of different nitroaromatic explosive molecules affect them. The presence of small amounts of trinitrophenol produces large quenching of their emission intensity. This quenching is favoured owing to specific interactions (H-bonds) between the Tz and CN groups of the MOFs and the -OH of the TNP molecule. All these photophysical studies are keystones for further improvements of this kind of nanomaterials to use in different fields as photocatalysts, fluorescent sensors or optoelectronic devices

Stent duodenal en obstrucción maligna del tracto de salida gástrico en un centro de referencia de Cundinamarca: serie de casos

Objetivo: describir la experiencia de la inserción del stent duodenal en pacientes con obstrucción maligna del tracto de salida gástrico en un centro de referencia de tercer nivel de Cundinamarca. Materiales y métodos: estudio observacional, serie de casos. Pacientes con obstrucción maligna del tracto de salida gástrico (OTSG) diagnosticados entre diciembre de 2019 y febrero de 2022 llevados a inserción de stent metálico autoexpandible duodenal en la unidad de Gastroenterología del Hospital Universitario de la Samaritana. Resultados: 17 pacientes fueron incluidos, de los cuales el 76 % eran hombres, con una edad promedio de 69 años (desviación estándar [DE]: 11 años). Se encontró adenocarcinoma gástrico confirmado por histología en el 82 % de los pacientes, y el 41 % tenía carcinomatosis peritoneal. El éxito técnico fue del 100 % y el éxito clínico fue del 88 % (15 pacientes). En cuanto al tamaño del stent utilizado, el 35 % (6 pacientes) fue de 12 cm, el 53 % (9 pacientes) de 9 cm y el 12 % (2 pacientes) de 6 cm. Se utilizó guía fluoroscópica y endoscópica en el 88 % de los casos. La sobrevida de los pacientes en el seguimiento fue en promedio de 84 días (2,8 meses; rango: 0-414 días) y actualmente 1 paciente continúa en vigilancia posterior a la inserción de stent en el tiempo descrito del estudio. Conclusión: el stent duodenal es una alternativa de manejo paliativo efectiva y segura en los pacientes con OTSG que permite mejorar los síntomas y, en especial, la tolerancia a la vía oral y el egreso hospitalario temprano en este grupo de pacientes con una enfermedad neoplásica avanzada terminal en fase de manejo paliativo, lo que disminuye la necesidad de manejo quirúrgico

NME1 and DCC variants are associated with susceptibility and tumor characteristics in Mexican patients with colorectal cancer

Abstract Background Colorectal cancer (CRC) ranks third in cancer incidence globally and is the second leading cause of cancer-related mortality. The nucleoside diphosphate kinase 1 (NME1) and netrin 1 receptor (DCC) genes have been associated with resistance against tumorigenesis and tumor metastasis. This study investigates the potential association between NME1 (rs34214448 G > T and rs2302254 C > T) and DCC (rs2229080 G > C and rs714 A > G) variants and susceptibility to colorectal cancer development. Methods Samples from 232 colorectal cancer patients and 232 healthy blood donors underwent analysis. Variants were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) methodology. Associations were assessed using odds ratios (OR), and the p values were adjusted with Bonferroni test. Results Individuals carrying the G/T and T/T genotypes for the NME1 rs34214448 variant exhibited a higher susceptibility for develop colorectal cancer (OR = 2.68, 95% CI: 1.76–4.09, P = 0.001 and OR = 2.47, 95% CI: 1.37–4.47, P = 0.001, respectively). These genotypes showed significant associations in patients over 50 years (OR = 2.87, 95% CI: 1.81–4.54, P = 0.001 and OR = 2.99, 95% CI: 1.54–5.79, P = 0.001 respectively) and with early Tumor-Nodule-Metastasis (TNM) stage (P = 0.001), and tumor location in the rectum (P = 0.001). Furthermore, the DCC rs2229080 variant revealed that carriers of the G/C genotype had an increased risk for develop colorectal cancer (OR = 2.00, 95% CI: 1.28–3.11, P = 0.002) and were associated with age over 50 years, sex, and advanced TNM stages (P = 0.001). Conclusions These findings suggest that the NME1 rs34214448 and DCC rs2229080 variants play a significant role in colorectal cancer development