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Research on high-field magnetic resonance imaging (HF-MRI) has been increased in recent years, aiming to improve diagnosis accuracy by increasing the signal-to-noise ratio and hence image quality. Conventional contrast agents (CAs) have important limitations for HF-MRI, with the consequent need for the development of new CAs. Among them, the most promising alternatives are those based on Dy3+ or Ho3+ compounds. Notably, the high atomic number of lanthanide cations would bestow a high capability for X-ray attenuation to such Dy or Ho-based compounds, which would also allow them to be employed as CAs for X-ray computed tomography (CT). In this work, we have prepared uniform NaDy(WO4)2 and NaHo(WO4)2 nanoparticles (NPs), which were dispersible under conditions that mimic the physiological media and were nontoxic for cells, meeting the main requirements for their use in vivo. Both NPs exhibited satisfactory magnetic relaxivities at 9.4 T, thus making them a promising alternative to clinical CAs for HF-MRI. Furthermore, after their intravenous administration in tumor-bearing mice, both NPs exhibited significant accumulation inside the tumor at 24 h, attributable to passive targeting by the enhanced permeability and retention (EPR) effect. Therefore, our NPs are suitable for the detection of tumors through HF-MRI. Finally, NaDy(WO4)2 NPs showed a superior X-ray attenuation capability than iohexol (commercial CT CA), which, along with their high r2 value, makes them suitable as the dual-probe for both HF-MRI and CT imaging, as demonstrated by in vivo experiments conducted using healthy mice.
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Bimodal medical imaging based on magnetic resonance imaging (MRI) and computed tomography (CT) is a well-known strategy to increase the diagnostic accuracy. The most recent advances in MRI and CT instrumentation are related to the use of ultra-high magnetic fields (UHF-MRI) and different working voltages (spectral CT), respectively. Such advances require the parallel development of bimodal contrast agents (CAs) that are efficient under new instrumental conditions. In this work, we have synthesized, through a precipitation reaction from a glycerol solution of the precursors, uniform barium dysprosium fluoride nanospheres with a cubic fluorite structure, whose size was found to depend on the Ba/(Ba + Dy) ratio of the starting solution. Moreover, irrespective of the starting Ba/(Ba + Dy) ratio, the experimental Ba/(Ba + Dy) values were always lower than those used in the starting solutions. This result was assigned to lower precipitation kinetics of barium fluoride compared to dysprosium fluoride, as inferred from the detailed analysis of the effect of reaction time on the chemical composition of the precipitates. A sample composed of 34 nm nanospheres with a Ba0.51Dy0.49F2.49 stoichiometry showed a transversal relaxivity (r2) value of 147.11 mM-1·s-1 at 9.4 T and gave a high negative contrast in the phantom image. Likewise, it produced high X-ray attenuation in a large range of working voltages (from 80 to 140 kVp), which can be attributed to the presence of different K-edge values and high Z elements (Ba and Dy) in the nanospheres. Finally, these nanospheres showed negligible cytotoxicity for different biocompatibility tests. Taken together, these results show that the reported nanoparticles are excellent candidates for UHF-MRI/spectral CT bimodal imaging CAs.
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The fine control of synaptic function requires robust trans-synaptic molecular interactions. However, it remains poorly understood how trans-synaptic bridges change to reflect the functional states of the synapse. Here, we develop optical tools to visualize in firing synapses the molecular behavior of two trans-synaptic proteins, LGI1 and ADAM23, and find that neuronal activity acutely rearranges their abundance at the synaptic cleft. Surprisingly, synaptic LGI1 is primarily not secreted, as described elsewhere, but exo- and endocytosed through its interaction with ADAM23. Activity-driven translocation of LGI1 facilitates the formation of trans-synaptic connections proportionally to the history of activity of the synapse, adjusting excitatory transmission to synaptic firing rates. Accordingly, we find that patient-derived autoantibodies against LGI1 reduce its surface fraction and cause increased glutamate release. Our findings suggest that LGI1 abundance at the synaptic cleft can be acutely remodeled and serves as a critical control point for synaptic function.
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Péptidos y Proteínas de Señalización Intracelular , Sinapsis , Transmisión Sináptica , Animales , Humanos , Proteínas ADAM/metabolismo , Autoanticuerpos/inmunología , Ácido Glutámico/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones Endogámicos C57BL , Neuronas/metabolismo , Transporte de Proteínas , Sinapsis/metabolismo , Transmisión Sináptica/fisiología , Ratas , Ratas Sprague-DawleyRESUMEN
The application of metal-based nanoparticles (mNPs) in cancer therapy and diagnostics (theranostics) has been a hot research topic since the early days of nanotechnology, becoming even more relevant in recent years. However, the clinical translation of this technology has been notably poor, with one of the main reasons being a lack of understanding of the disease and conceptual errors in the design of mNPs. Strikingly, throughout the reported studies to date on in vivo experiments, the concepts of "tumor targeting" and "tumor cell targeting" are often intertwined, particularly in the context of active targeting. These misconceptions may lead to design flaws, resulting in failed theranostic strategies. In the context of mNPs, tumor targeting can be described as the process by which mNPs reach the tumor mass (as a tissue), while tumor cell targeting refers to the specific interaction of mNPs with tumor cells once they have reached the tumor tissue. In this review, we conduct a critical analysis of key challenges that must be addressed for the successful targeting of either tumor tissue or cancer cells within the tumor tissue. Additionally, we explore essential features necessary for the smart design of theranostic mNPs, where 'smart design' refers to the process involving advanced consideration of the physicochemical features of the mNPs, targeting motifs, and physiological barriers that must be overcome for successful tumor targeting and/or tumor cell targeting.
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Nanopartículas del Metal , Neoplasias , Nanomedicina Teranóstica , Humanos , Neoplasias/terapia , Neoplasias/tratamiento farmacológico , Neoplasias/diagnóstico , Neoplasias/patología , Nanomedicina Teranóstica/métodos , Animales , Nanopartículas del Metal/química , Nanopartículas del Metal/uso terapéutico , Sistemas de Liberación de Medicamentos/métodosRESUMEN
RESUMEN Objetivo: Describir los cambios percibidos en hábitos de alimentación, composición corporal, condición física y psicológica de deportistas universitarios durante la cuarentena por Covid-19 en 2020. Materiales y métodos: Estudio transversal, de fuente de información secundaria; 403 deportistas universitarios diligenciaron una encuesta en línea en el segundo semestre de 2020. Se utilizó la estadística descriptiva para analizar los datos, para determinar asociación entre las variables de interés: tipo de deporte, sexo y Covid-19 se utilizó la prueba de significancia estadística Chi X2 de Pearson <0,05. Resultados: Del total de deportistas, el 53,3 eran hombres. La mayoría practicaba deportes individuales (55,3 %). Alrededor del 89 % de atletas no presentó Covid-19. El 59,8 % sintió que el peso empeoró, siendo mayor en los deportes individuales (p= 0,005). Una proporción mayor de mujeres recibió asesoría por parte de un entrenador y de redes sociales (62,7 %) y 7 de cada 10 hombres complementaba su entrenamiento con información proveniente de redes sociales (p=0,001). Las características psicológicas fueron las que mostraron mayores diferencias significativas según sexo y el tipo de deporte. Conclusión: La cuarentena por Covid-19 está asociada con cambios desfavorables en los deportistas universitarios; específicamente, se percibieron cambios en los hábitos de alimentación con un aumento en la cantidad de alimentos de baja calidad nutricional y alta densidad calórica, cambios negativos en el peso y peor condición física. Los deportes individuales se vieron más afectados frente a los deportes de conjunto; en lo psicológico se resalta la mala adaptación a la cuarentena con sentimientos de soledad, ansiedad y mal estado de ánimo, donde las mujeres fueron las más afectadas.
ABSTRACT Objetive: Describe the perceived changes in eating habits, body composition, physical and psychological condition of university athletes during the quarantine by Covid-19, in the year 2020. Materials and methods: Cross-sectional study, from a secondary data source, 403 universitary athletes answered an online survey on 2020's second semester. Descriptive statistics was used to analyze data, Pearson's Chi X2 <0,05 test was used to determine association between variables of interest: Sport type, sex and Covid-19. Results: The majority practiced individual sports (55.3 %). About 89 % of athletes did not present Covid-19 59.8 % felt that body weight worsened, being higher in individual sports (p= 0.005). Most of the athletes trained for at least one hour a day (81.1 %), a higher proportion of women received advice from a coach and from social networks (62.7 %), while 7 out of 10 men only complemented their training with information from social networks (p=0.001), the type of sport also presented an association in this variable (p=0.024) The psychological characteristics were those that showed the greatest significant differences according to gender and type of sport. Conclusion: The Covid-19 quarantine is associated with unfavorable changes in university athletes, specifically changes in eating habits were perceived with an increase in the amount of foods of low nutritional quality, negative changes in weight, worse physical condition, where the individual sports were more affected compared to group sports, feelings of loneliness, anxiety and bad mood, where women were the most affected.
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Iron Oxide Nanoparticles (IONPs) hold the potential to exert significant influence on fighting cancer through their theranostics capabilities as contrast agents (CAs) for magnetic resonance imaging (MRI) and as mediators for magnetic hyperthermia (MH). In addition, these capabilities can be improved by doping IONPs with other elements. In this work, the synthesis and characterization of single-core and alloy ZnFe novel magnetic nanoparticles (MNPs), with improved magnetic properties and more efficient magnetic-to-heat conversion, are reported. Remarkably, the results challenge classical nucleation and growth theories, which cannot fully predict the final size/shape of these nanoparticles and, consequently, their magnetic properties, implying the need for further studies to better understand the nanomagnetism phenomenon. On the other hand, leveraging the enhanced properties of these new NPs, successful tumor therapy by MH is achieved following their intravenous administration and tumor accumulation via the enhanced permeability and retention (EPR) effect. Notably, these results are obtained using a single low dose of MNPs and a single exposure to clinically suitable alternating magnetic fields (AMF). Therefore, as far as the authors are aware, for the first time, the successful application of intravenously administered MNPs for MRI-tracked MH tumor therapy in passively targeted tumor xenografts using clinically suitable conditions is demonstrated.
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Hipertermia Inducida , Imagen por Resonancia Magnética , Hipertermia Inducida/métodos , Imagen por Resonancia Magnética/métodos , Animales , Ratones , Humanos , Línea Celular Tumoral , Zinc/química , Nanopartículas Magnéticas de Óxido de Hierro/química , Medios de Contraste/química , Nanopartículas de Magnetita/química , Hierro/químicaRESUMEN
Alzheimer's disease is the main cause of aging-associated dementia, for which there is no effective treatment. In this work, we reanalyze the information of a previous genome wide association study, using a new pipeline design to identify novel potential drugs. With this approach, ribonucleoside-diphosphate reductase gene (RRM2B) emerged as a candidate target and its inhibitor, 2', 2'-difluoro 2'deoxycytidine (gemcitabine), as a potential pharmaceutical drug against Alzheimer's disease. We functionally verified the effect of inhibiting the RRM2B homolog, rnr-2, in an Alzheimer's model of Caenorhabditis elegans, which accumulates human Aß1-42 peptide to an irreversible paralysis. RNA interference against rnr-2 and also treatment with 200â ng/ml of gemcitabine, showed an improvement of the phenotype. Gemcitabine treatment increased the intracellular ATP level 3.03 times, which may point to its mechanism of action. Gemcitabine has been extensively used in humans for cancer treatment but at higher concentrations. The 200â ng/ml concentration did not exert a significant effect over cell cycle, or affected cell viability when assayed in the microglia N13 cell line. Thus, the inhibitory drug of the RRM2B activity could be of potential use to treat Alzheimer's disease and particularly gemcitabine might be considered as a promising candidate to be repurposed for its treatment.
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Enfermedad de Alzheimer , Caenorhabditis elegans , Desoxicitidina , Modelos Animales de Enfermedad , Caenorhabditis elegans/efectos de los fármacos , Enfermedad de Alzheimer/tratamiento farmacológico , Animales , Desoxicitidina/análogos & derivados , Desoxicitidina/farmacología , Desoxicitidina/uso terapéutico , Péptidos beta-Amiloides/metabolismo , Humanos , Gemcitabina , Ribonucleósido Difosfato Reductasa/genética , Ribonucleótido Reductasas/antagonistas & inhibidores , Ribonucleótido Reductasas/metabolismo , Adenosina Trifosfato/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/uso terapéutico , Interferencia de ARNRESUMEN
Triple negative breast cancer (TNBC) is highly immunogenic and high levels of tumor infiltrating lymphocytes (TILs) have been associated with a better prognosis and higher probability to achieve pathological complete response. Here, we explore the potential role of stromal TILs level and composition as a prognostic and predictive biomarker in TNBC. 195 Tumor biospecimens from patients diagnosed with TNBC were included. Stromal TILs (sTILs), positive CD4/CD8 cells were evaluated. Differences in clinic-pathological characteristics according to immune infiltration were assessed. The predictive and prognostic value of immune infiltration was analyzed by multivariate models. Higher immune infiltration was observed in patients with favorable clinical-pathological features. Survival analysis showed that longer overall survival times were observed in patients with a higher infiltration of sTILs (p = 0.00043), CD4 + (p = 0.0074) and CD8 + (p = 0.008). In the multivariate analysis, low levels of sTILs were found to be associated with a higher mortality hazard (HR: 1.59, 95% CI 1.01-2.48). CD4 and CD8 immune infiltration were associated with higher odds for pathological complete response (OR: 1.20, 95% CI 1.00-1.46, OR: 1.28, 1.02-1.65, respectively). Our results suggest that immune infiltration could be used as a prognostic marker for overall survival in TNBC patients.
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Neoplasias de la Mama Triple Negativas , Humanos , Neoplasias de la Mama Triple Negativas/patología , Linfocitos Infiltrantes de Tumor , Colombia , Pronóstico , Biomarcadores , Biomarcadores de Tumor/análisisRESUMEN
Anisotropic hybrid nanostructures stand out as promising therapeutic agents in photothermal conversion-based treatments. Accordingly, understanding local heat generation mediated by light-to-heat conversion of absorbing multicomponent nanoparticles at the single-particle level has forthwith become a subject of broad and current interest. Nonetheless, evaluating reliable temperature profiles around a single trapped nanoparticle is challenging from all of the experimental, computational, and fundamental viewpoints. Committed to filling this gap, the heat generation of an anisotropic hybrid nanostructure is explored by means of two different experimental approaches from which the local temperature is measured in a direct or indirect way, all in the context of hot Brownian motion theory. The results were compared with analytical results supported by the numerical computation of the wavelength-dependent absorption efficiencies in the discrete dipole approximation for scattering calculations, which has been extended to inhomogeneous nanostructures. Overall, we provide a consistent and comprehensive view of the heat generation in optical traps of highly absorbing particles from the viewpoint of the hot Brownian motion theory.
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Superparamagnetic iron oxide nanoparticles have hogged the limelight in different fields of nanotechnology. Surprisingly, notwithstanding the prominent role played as agents in magnetic hyperthermia treatments, the effects of nanoparticle size and shape on the magnetic hyperthermia performance have not been entirely elucidated yet. Here, spherical or cubical magnetic nanoparticles synthesized by a thermal decomposition method with the same magnetic and hyperthermia properties are evaluated. Interestingly, spherical nanoparticles displayed significantly higher magnetic relaxivity than cubic nanoparticles; however, comparable differences were not observed in specific absorption rate (SAR), pointing out the need for additional research to better understand the connection between these two parameters. Additionally, the as-synthetized spherical nanoparticles showed negligible cytotoxicity and, therefore, were tested in vivo in tumor-bearing mice. Following intratumoral administration of these spherical nanoparticles and a single exposure to alternating magnetic fields (AMF) closely mimicking clinical conditions, a significant delay in tumor growth was observed. Although further in vivo experiments are warranted to optimize the magnetic hyperthermia conditions, our findings support the great potential of these nanoparticles as magnetic hyperthermia mediators for tumor therapy.
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Hipertermia Inducida , Neoplasias , Ratones , Animales , Hipertermia Inducida/métodos , Campos Magnéticos , Neoplasias/diagnóstico por imagen , Neoplasias/terapia , Nanopartículas Magnéticas de Óxido de Hierro , Imagen por Resonancia MagnéticaRESUMEN
Dimethyl fumarate is an ester from the Krebs cycle intermediate fumarate. This drug is approved and currently used for the treatment of psoriasis and multiple sclerosis, and its anti-angiogenic activity was reported some years ago. Due to the current clinical relevance of this compound and the recently manifested importance of endothelial cell metabolism on the angiogenic switch, we wanted to elucidate whether dimethyl fumarate has an effect on energetic metabolism of endothelial cells. Different experimental approximations were performed in endothelial cells, including proteomics, isotope tracing and metabolomics experimental approaches, in this work we studied the possible role of dimethyl fumarate in endothelial cell energetic metabolism. We demonstrate for the first time that dimethyl fumarate promotes glycolysis and diminishes cell respiration in endothelial cells, which could be a consequence of a down-regulation of serine and glycine synthesis through inhibition of PHGDH activity in these cells. Dimethyl fumarate alters the energetic metabolism of endothelial cells in vitro and in vivo through an unknown mechanism, which could be the cause or the consequence of its pharmacological activity. This new discovery on the targets of this compound could open a new field of study regarding the mechanism of action of dimethyl fumarate.
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Dimetilfumarato , Esclerosis Múltiple , Humanos , Dimetilfumarato/farmacología , Dimetilfumarato/uso terapéutico , Células Endoteliales/metabolismo , Fumaratos/farmacología , Fumaratos/uso terapéutico , Regulación hacia AbajoRESUMEN
Gastric cancer (GC) is the fifth most frequent malignancy worldwide and has a high mortality rate related to late diagnosis. Although the gold standard for the GC diagnosis is endoscopy with biopsy, nonetheless, it is not cost-effective and is invasive for the patient. The Human leukocyte antigen G (HLA-G) molecule is a checkpoint of the immune response. Its overexpression in cancer is associated with immune evasion, metastasis, poor prognosis, and lower overall survival. We evaluate the plasma levels of soluble HLA-G, (sHLA-G) in patients with GC and benign gastric pathologies using an ELISA test. A higher concentration of sHLA-G in patients with GC than in those with benign pathologies, higher levels of plasma sHLA-G in women with GC compared with men and significant differences in the sHLA-G levels between the benign gastric pathologies evaluated, was our main findings. As no significant differences were found between the GC assessed stages in our study population, we suggest that sHLA-G is not an adequate marker for staging GC, but it does have diagnostic potential. In addition to providing information on the potential of sHLA-G as a diagnostic marker for GC, our study demonstrate that HLA-G molecules can be found in the membrane of exosomes, which highlights the need to perform studies with a larger number of samples to explore the functional implications of HLA-G positive exosomes in the context of gastric cancer, and to determine the clinical significance and possible applications of these findings in the development of non-invasive diagnostic methods.
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Antígenos HLA-G , Neoplasias Gástricas , Masculino , Humanos , Femenino , Neoplasias Gástricas/diagnóstico , Detección Precoz del Cáncer , Estadificación de Neoplasias , BiomarcadoresRESUMEN
Chitosan-functionalized magnetite/poly(ε-caprolactone) nanoparticles were formulated by interfacial polymer disposition plus coacervation, and loaded with gemcitabine. That (core/shell)/shell nanostructure was confirmed by electron microscopy, elemental analysis, electrophoretic, and Fourier transform infrared characterizations. A short-term stability study proved the protection against particle aggregation provided by the chitosan shell. Superparamagnetic properties of the nanoparticles were characterized in vitro, while the definition of the longitudinal and transverse relaxivities was an initial indication of their capacity as T2 contrast agents. Safety of the particles was demonstrated in vitro on HFF-1 human fibroblasts, and ex vivo on SCID mice. The nanoparticles demonstrated in vitro pH- and heat-responsive gemcitabine release capabilities. In vivo magnetic resonance imaging studies and Prussian blue visualization of iron deposits in tissue samples defined the improvement in nanoparticle targeting into the tumor when using a magnetic field. This tri-stimuli (magnetite/poly(ε-caprolactone))/chitosan nanostructure could find theranostic applications (biomedical imaging & chemotherapy) against tumors.
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Quitosano , Nanopartículas de Magnetita , Nanopartículas , Neoplasias , Ratones , Animales , Humanos , Óxido Ferrosoférrico/uso terapéutico , Quitosano/uso terapéutico , Medicina de Precisión , Ratones SCID , Nanopartículas de Magnetita/química , Neoplasias/diagnóstico por imagen , Neoplasias/tratamiento farmacológico , Neoplasias/patología , Gemcitabina , Imagen por Resonancia Magnética/métodosRESUMEN
During neuronal circuit formation, local control of axonal organelles ensures proper synaptic connectivity. Whether this process is genetically encoded is unclear and if so, its developmental regulatory mechanisms remain to be identified. We hypothesized that developmental transcription factors regulate critical parameters of organelle homeostasis that contribute to circuit wiring. We combined cell type-specific transcriptomics with a genetic screen to discover such factors. We identified Telomeric Zinc finger-Associated Protein (TZAP) as a temporal developmental regulator of neuronal mitochondrial homeostasis genes, including Pink1 . In Drosophila , loss of dTzap function during visual circuit development leads to loss of activity-dependent synaptic connectivity, that can be rescued by Pink1 expression. At the cellular level, loss of dTzap/TZAP leads to defects in mitochondrial morphology, attenuated calcium uptake and reduced synaptic vesicle release in fly and mammalian neurons. Our findings highlight developmental transcriptional regulation of mitochondrial homeostasis as a key factor in activity-dependent synaptic connectivity.
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We have developed a trimodal bioimaging probe for near-infrared luminescent imaging, high-field magnetic resonance imaging, and X-ray computed tomography using Dy3+ as the paramagnetic component and Nd3+ as the luminescent cation, both of them incorporated in a vanadate matrix. Among different essayed architectures (single phase and core-shell nanoparticles) the one showing the best luminescent properties is that consisting of uniform DyVO4 nanoparticles coated with a first uniform layer of LaVO4 and a second layer of Nd3+-doped LaVO4. The magnetic relaxivity (r2) at high field (9.4 T) of these nanoparticles was among the highest values ever reported for this kind of probes and their X-ray attenuation properties, due to the presence of lanthanide cations, were also better than those of a commercial contrast agent (iohexol) commonly used for X-ray computed tomography. In addition, they were chemically stable in a physiological medium in which they could be easily dispersed owing to their one-pot functionalization with polyacrylic acid, and, finally, they were non-toxic for human fibroblast cells. Such a probe is, therefore, an excellent multimodal contrast agent for near-infrared luminescent imaging, high-field magnetic resonance imaging, and X-ray computed tomography.
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Elementos de la Serie de los Lantanoides , Nanopartículas , Humanos , Elementos de la Serie de los Lantanoides/química , Vanadatos , Medios de Contraste/química , Tomografía Computarizada por Rayos X/métodos , Imagen por Resonancia Magnética/métodos , Nanopartículas/químicaRESUMEN
Microgels are soft microparticles that often exhibit thermoresponsiveness and feature a transformation at a critical temperature, referred to as the volume phase transition temperature. Whether this transformation occurs as a smooth or as a discontinuous one is still a matter of debate. This question can be addressed by studying individual microgels trapped in optical tweezers. For this aim, composite particles are obtained by decorating Poly-N-isopropylacrylamide (pNIPAM) microgels with iron oxide nanocubes. These composites become self-heating when illuminated by the infrared trapping laser, performing hot Brownian motion within the trap. Above a certain laser power, a single decorated microgel features a volume phase transition that is discontinuous, while the usual continuous sigmoidal-like dependence is recovered after averaging over different microgels. The collective sigmoidal behavior enables the application of a power-to-temperature calibration and provides the effective drag coefficient of the self-heating microgels, thus establishing these composite particles as potential micro-thermometers and micro-heaters. Moreover, the self-heating microgels also exhibit an unexpected and intriguing bistability behavior above the critical temperature, probably due to partial collapses of the microgel. These results set the stage for further studies and the development of applications based on the hot Brownian motion of soft particles.
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We know little about how smoking prevention interventions might leverage social network structures to enhance protective social norms. In this study we combined statistical and network science methods to explore how social networks influence social norms related to adolescent smoking in school-specific settings in Northern Ireland and Colombia. Pupils (12-15 years old) participated in two smoking prevention interventions in both countries (n = 1344). A Latent Transition Analysis identified three groups characterized by descriptive and injunctive norms towards smoking. We employed a Separable Temporal Random Graph Model to analyze homophily in social norms and conducted a descriptive analysis of the changes in the students' and their friends' social norms over time to account for social influence. The results showed that students were more likely to be friends with others who had social norms against smoking. However, students with social norms favorable towards smoking had more friends with similar views than the students with perceived norms against smoking, underlining the importance of network thresholds. Our results support the notation that the ASSIST intervention takes advantage of friendship networks to leverage greater change in the students' smoking social norms than the Dead Cool intervention, reiterating that social norms are subject to social influence.
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Prevención del Hábito de Fumar , Normas Sociales , Humanos , Adolescente , Niño , Fumar , Estudiantes , Amigos , Grupo Paritario , Red SocialRESUMEN
Uniform sodium-dysprosium double molybdate (NaDy(MoO4)2) nanoparticles having different morphologies (spheres and ellipsoids) and tunable size have been synthesized for the first time in literature. The procedure is based on a homogeneous precipitation process at moderated temperatures (≤220 °C) from solutions containing appropriated precursors dissolved in ethylene glycol-water mixtures, in the absence (spheres) or the presence (ellipsoids) of tartrate anions. The effects of the morphological characteristics (size and shape) of the nanoparticles on the magnetic relaxivity at high field (9.4 T) have been evaluated finding that the latter magnitude was higher for the spheres than for the ellipsoids, indicating their better suitability as contrast agents for high-field magnetic resonance imaging. Such nanoparticles have been successfully coated with polymers bearing carboxylate functional groups through a layer-by-layer process, which improves the colloidal stability of the nanoparticles in physiological media. It has been also found that the coating layer had no significant effects on the nanoparticles relaxivity and that such coated nanoparticles exhibited a high biocompatibility and a high chemical stability. In summary, we have developed NaDy(MoO4)2 based bioprobes which meet the required criteria for their use as contrast agents for high-field magnetic resonance imaging.
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Medios de Contraste , Nanopartículas , Tartratos , Disprosio , Imagen por Resonancia Magnética/métodos , Polímeros , Campos Magnéticos , Aniones , Agua , Glicoles de Etileno , SodioRESUMEN
Carbon footprint has become a reference indicator of the environmental impact of food production. Governments are increasingly demanding a trend towards low-carbon-footprint production in order to reduce the impact on climate change. In this sense, the study of consumers' preferences and assessment of products from the perspective of their carbon footprint is crucial to achieve a green and circular economy. This paper specifically attempted to assess consumer preference and willingness to pay for beef that has been carbon-footprint-labelled as an attribute. In order to attain this objective, a choice experiment was designed and applied to a total of 362 Spanish consumers. The results revealed a positive preference towards beef produced in low-carbon-footprint systems. In addition, the segmentation of these consumers revealed the existence of a group of consumers who prioritise environmental impact over product price.
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The stereoselective addition of ethyl acetate enolate to the CâN bond of N-tert-butylsulfinylimines has been investigated in depth. A significant effect of the LHMDS amount and the N-sulfinylimine nature on the stereoselectivity of the process was observed. Conditions were found where sulfinylimines of differently substituted salicylaldehydes derivatives, ethyl acetate, and LHMDS afforded the corresponding addition products as a single diastereomer in good yields. The developed protocol was successfully applied to the first stereoselective synthesis of differently substituted 4-amino-3,4-dihydrocoumarin derivatives. Computational models confirmed the prominent role of the ortho aryl substituent in the stereoselectivity of the process. A significant and selective cytotoxic activity against Glioblastoma Multiforme (GBM) cancer line has been determined for the noncyclic hydroxy ester derivative.