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Prognostication in acute pulmonary embolism (PE) requires reliable markers. While cellular indices such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) appear promising, their utility in PE prognostication needs further exploration. We utilized data from the RIETE registry and the Loyola University Medical Center (LUMC) to assess the prognostic value of NLR, PLR, and SII in acute PE, using logistic regression models. The primary outcome was 30-day all-cause mortality. We compared their prognostic value versus the simplified Pulmonary Embolism Severity Index (sPESI) alone. We included 10 085 patients from RIETE and 700 from the LUMC. Thirty-day mortality rates were 4.6% and 8.3%, respectively. On multivariable analysis, an elevated NLR (>7.0) was associated with increased mortality (adjusted odds ratio [aOR]: 3.46; 95% CI: 2.60-4.60), outperforming the PLR > 220 (aOR: 2.36; 95% CI: 1.77-3.13), and SII > 1600 (aOR: 2.52; 95% CI: 1.90-3.33). The c-statistic for NLR in patients with low-risk PE was 0.78 (95% CI: 0.69-0.86). Respective numbers were 0.66 (95% CI: 0.63-0.69) and 0.68 (95% CI: 0.59-0.76) for intermediate-risk and high-risk patients. These findings were mirrored in the LUMC cohort. Among 9810 normotensive patients in RIETE, those scoring 0 points in sPESI and with an NLR ≤ 7.0 (35% of the population) displayed superior sensitivity (97.1%; 95% CI: 95.5-98.7) and negative predictive value (99.7%; 95% CI: 99.5-99.8) than sPESI alone (87.1%; 95% CI: 83.9-90.3, and 98.7%; 95% CI: 98.4-99.1, respectively) for 30-day mortality. The NLR is a significant prognostic marker for 30-day mortality in PE patients, especially useful to identify patients with very low-risk PE.
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Neutrófilos , Embolia Pulmonar , Humanos , Embolia Pulmonar/sangre , Embolia Pulmonar/mortalidad , Embolia Pulmonar/diagnóstico , Masculino , Femenino , Anciano , Persona de Mediana Edad , Pronóstico , Linfocitos/patología , Anciano de 80 o más Años , Recuento de Linfocitos , Plaquetas/patología , Sistema de Registros , Índice de Severidad de la Enfermedad , Recuento de Plaquetas , Biomarcadores/sangreRESUMEN
Hybrid magnetic nanoparticles made up of an iron oxide, Fe3O4, core and a mesoporous SiO2 shell with high magnetization and a large surface area were proposed as an efficient drug delivery platform. The core/shell structure was synthesized by two seed-mediated growth steps combining solvothermal and sol-gel approaches and using organic molecules as a porous scaffolding template. The system presents a mean particle diameter of 30(5) nm (9 nm magnetic core diameter and 10 nm silica shell thickness) with superparamagnetic behavior, saturation magnetization of 32 emu/g, and a significant AC magnetic-field-induced heating response (SAR = 63 W/gFe3O4, measured at an amplitude of 400 Oe and a frequency of 307 kHz). Using ibuprofen as a model drug, the specific surface area (231 m2/g) of the porous structure exhibits a high molecule loading capacity (10 wt %), and controlled drug release efficiency (67%) can be achieved using the external AC magnetic field for short time periods (5 min), showing faster and higher drug desorption compared to that of similar stimulus-responsive iron oxide-based nanocarriers. In addition, it is demonstrated that the magnetic field-induced drug release shows higher efficiency compared to that of the sustained release at fixed temperatures (47 and 53% for 37 and 42 °C, respectively), considering that the maximum temperature reached during the exposure to the magnetic field is well below (31 °C). Therefore, it can be hypothesized that short periods of exposure to the oscillating field induce much greater heating within the nanoparticles than in the external solution.
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Portadores de Fármacos , Nanopartículas , Portadores de Fármacos/química , Preparaciones de Acción Retardada , Dióxido de Silicio/química , Ibuprofeno , Campos Magnéticos , Nanopartículas/químicaRESUMEN
Recreational marijuana laws (RMLs) continue to grow in popularity, but the effects on mental health treatment are unclear. This paper uses an event-study within a difference-in-differences framework to study the short-run impact of state RMLs on admissions into mental health treatment facilities. The results indicate that shortly after a state adopts an RML, they experience a decrease in the average number of mental health treatment admissions. The findings are driven by white, Black, and Medicaid-funded admissions and are consistent for both male and female admissions. The results are robust to alternative specifications and sensitivity analysis.
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Cannabis , Estados Unidos , Humanos , Masculino , Femenino , Salud Mental , Legislación de Medicamentos , Hospitalización , MedicaidRESUMEN
This study uses a difference-in-differences design within an event-study framework to examine how state decisions to expand Medicaid following the passage of the Affordable Care Act (ACA) affected mental health treatment. The findings suggest that expansion states experienced increased admissions to mental health treatment facilities and Medicaid-reimbursed prescriptions for medications used to treat common forms of mental illness. The results also indicate an increase in admissions with trauma, anxiety, conduct, and depression disorders. There is also suggestive evidence of an increase in the number of mental health treatment facilities accepting Medicaid as a form of payment. Lastly, as with previous studies, I find weak evidence of a decrease in suicides in Medicaid expansion states. These findings highlight the vital role of the ACA in providing access to mental health treatment for low-income Americans.
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Medicaid , Suicidio , Humanos , Estados Unidos , Patient Protection and Affordable Care Act , Salud Mental , Cobertura del Seguro , Accesibilidad a los Servicios de Salud , Seguro de SaludRESUMEN
BACKGROUND: The length of hospital stay (LOS) for acute pulmonary embolism (PE) varies considerably. Whether the upfront use of a PE prognostic assessment and management pathway is effective in reducing the LOS remains unknown. METHODS: We conducted a randomised controlled trial of adults hospitalised for acute PE: patients were assigned either to a prognostic assessment and management pathway involving risk stratification followed by predefined criteria for mobilisation and discharge (intervention group) or to usual care (control group). The primary end-point was LOS. The secondary end-points were the cost of prognostic tests and of hospitalisation, and 30-day clinical outcomes. RESULTS: Of 500 patients who underwent randomisation, 498 were included in the modified intention-to-treat analysis. The median LOS was 4.0â days (interquartile range (IQR) 3.7-4.2â days) in the intervention group and 6.1â days (IQR 5.7-6.5â days) in the control group (p<0.001). The mean total cost of prognostic tests was EUR 174.76 in the intervention group, compared with EUR 233.12 in the control group (mean difference EUR -58.37, 95% CI EUR -84.34- to -32.40). The mean total hospitalisation cost per patient was EUR 2085.66 in the intervention group, compared with EUR 3232.97 in the control group (mean difference EUR -1147.31, 95% CI EUR -1414.97- to -879.65). No significant differences were observed in 30-day readmission (4.0% versus 4.8%), all-cause mortality (2.4% versus 2.0%) or PE-related mortality (0.8% versus 1.2%) rates. CONCLUSIONS: The use of a prognostic assessment and management pathway was effective in reducing the LOS for acute PE.
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Readmisión del Paciente , Embolia Pulmonar , Enfermedad Aguda , Adulto , Humanos , Tiempo de Internación , Pronóstico , Embolia Pulmonar/tratamiento farmacológico , Embolia Pulmonar/terapiaRESUMEN
Dense systems of magnetic nanoparticles may exhibit dipolar collective behavior. However, two fundamental questions remain unsolved: i) whether the transition temperature may be affected by the particle anisotropy or it is essentially determined by the intensity of the interparticle dipolar interactions, and ii) what is the minimum ratio of dipole-dipole interaction (Edd ) to nanoparticle anisotropy (Kef V, anisotropyâ volume) energies necessary to crossover from individual to collective behavior. A series of particle assemblies with similarly intense dipolar interactions but widely varying anisotropy is studied. The Kef is tuned through different degrees of cobalt-doping in maghemite nanoparticles, resulting in a variation of nearly an order of magnitude. All the bare particle compacts display collective behavior, except the one made with the highest anisotropy particles, which presents "marginal" features. Thus, a threshold of Kef V/Edd ≈ 130 to suppress collective behavior is derived, in good agreement with Monte Carlo simulations. This translates into a crossover value of ≈1.7 for the easily accessible parameter TMAX (interacting)/TMAX (non-interacting) (ratio of the peak temperatures of the zero-field-cooled magnetization curves of interacting and dilute particle systems), which is successfully tested against the literature to predict the individual-like/collective behavior of any given interacting particle assembly comprising relatively uniform particles.
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Magnetismo , Nanopartículas , Anisotropía , Cobalto , Transición de FaseRESUMEN
Mandatory access Prescription Drug Monitoring Programs (MA-PDMPs) aim to curb the epidemic at a common point of initiation of use, the prescription. However, there is recent concern about whether opioid policies have been too restrictive and reduced appropriate access to patients with the most need for opioid pharmaceuticals. We assess MA-PDMP's effect on specialty-specific opioid prescribing behavior of Medicare providers. Our findings suggest that requiring providers to query a PDMP differentially affects opioid prescribing across provider specialties. We find a three to four percent decrease in prescribing for Primary Care and Internal Medicine providers. This result is driven by healthcare providers at the lower end of the prescribing distribution. There is also suggestive evidence of an increase in opioid use disorder treatment drugs prescribed by these same providers. We also find no evidence for the hypothesis that MA-PDMPs restrict prescribing by providers who treat patients with potentially high levels of pain, few drug substitutes, or urgency for pain treatment (e.g., Oncology/Palliative care). This result is not dependent on whether a state provides exemptions for these providers. Our results indicate that MA-PDMPs may help close provider-patient informational gaps while retaining a provider's ability to supply these drugs to patients with a need for opioids.
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Mal Uso de Medicamentos de Venta con Receta , Programas de Monitoreo de Medicamentos Recetados , Anciano , Analgésicos Opioides/uso terapéutico , Humanos , Medicare , Pautas de la Práctica en Medicina , Estados UnidosRESUMEN
OBJECTIVE: Patients who present with lower extremity ischemia are frequently anemic and the optimal transfusion threshold for this cohort remains controversial. We sought to evaluate the impact of blood transfusion on postoperative major adverse cardiac events (MACE), including myocardial infarction, dysrhythmia, stroke, congestive heart failure, and 30-day mortality for these patients. METHODS: All consecutive patients who underwent infra-inguinal bypass at our institution from 2011 to 2020 were included. Perioperative red blood cell transfusion was the primary exposure, and the primary outcome was MACE. Univariate and multivariable analyses were performed to assess the impact of patient and procedural variables, including red blood cell transfusion, stratified by hemoglobin (Hgb) nadir: <7, 7-8, and >8 g/dL. RESULTS: Of the 287 patients reviewed for analysis, 146 (50.9%) had a perioperative transfusion (mean: 1.6 ± 3 units). Patients who received a transfusion had a mean nadir Hgb of 8.3 ± 1.0 g/dL, compared to 10.1 ± 1.7 g/dL without a transfusion. The overall incidence of MACE was 15.7% (45 of 287 patients). Univariate analysis demonstrated that MACE was associated with blood transfusion (P = 0.009), lower Hgb nadir (P = 0.02), and higher blood loss (P = 0.003). On multivariate analysis, transfusion was independently associated with MACE for patients with a Hgb nadir >8 g/dL (OR: 3.09; P = 0.006), but not for patients with Hgb nadir 7-8 g/dL (OR: 0.818; P = 0.77). Additionally, patients with MACE had significantly longer length of hospital stay than for patients without (13 vs. 7.7 days, P = 0.001). CONCLUSIONS: For patients undergoing infra-inguinal bypass, receiving a red blood cell transfusion with a Hgb nadir >8 g/dL was associated with a 3-fold increase in MACE, with nearly twice the length of stay. For patients with a Hgb 7-8 g/dL, transfusion did not increase or reduce the incidence of MACE. These findings suggest no benefit of blood transfusion for patients with Hgb nadir >7 g/dL and harm for Hgb >8 g/dL, however causation cannot be proven due to the retrospective nature of the study and randomized studies are needed to confirm or refute these findings.
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Anemia/complicaciones , Enfermedades Cardiovasculares/etiología , Transfusión de Eritrocitos/efectos adversos , Isquemia/cirugía , Atención Perioperativa , Enfermedad Arterial Periférica/cirugía , Injerto Vascular , Anciano , Anciano de 80 o más Años , Anemia/sangre , Anemia/diagnóstico , Anemia/mortalidad , Biomarcadores/sangre , Enfermedades Cardiovasculares/diagnóstico , Enfermedades Cardiovasculares/mortalidad , Transfusión de Eritrocitos/mortalidad , Femenino , Hemoglobinas/metabolismo , Humanos , Isquemia/complicaciones , Isquemia/diagnóstico , Isquemia/mortalidad , Tiempo de Internación , Masculino , Persona de Mediana Edad , Atención Perioperativa/efectos adversos , Atención Perioperativa/mortalidad , Enfermedad Arterial Periférica/complicaciones , Enfermedad Arterial Periférica/diagnóstico , Enfermedad Arterial Periférica/mortalidad , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Factores de Tiempo , Resultado del Tratamiento , Injerto Vascular/efectos adversos , Injerto Vascular/mortalidadRESUMEN
The Radiation and Dust Sensor is one of six sensors of the Mars Environmental Dynamics Analyzer onboard the Perseverance rover from the Mars 2020 NASA mission. Its primary goal is to characterize the airbone dust in the Mars atmosphere, inferring its concentration, shape and optical properties. Thanks to its geometry, the sensor will be capable of studying dust-lifting processes with a high temporal resolution and high spatial coverage. Thanks to its multiwavelength design, it will characterize the solar spectrum from Mars' surface. The present work describes the sensor design from the scientific and technical requirements, the qualification processes to demonstrate its endurance on Mars' surface, the calibration activities to demonstrate its performance, and its validation campaign in a representative Mars analog. As a result of this process, we obtained a very compact sensor, fully digital, with a mass below 1 kg and exceptional power consumption and data budget features.
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Polvo , Medio Ambiente Extraterrestre , AtmósferaRESUMEN
Interfaces play a crucial role in composite magnetic materials and particularly in bimagnetic core/shell nanoparticles. However, resolving the microscopic magnetic structure of these nanoparticles is rather complex. Here, we investigate the local magnetization of antiferromagnetic/ferrimagnetic FeO/Fe3O4 core/shell nanocubes by electron magnetic circular dichroism (EMCD). The electron energy-loss spectroscopy (EELS) compositional analysis of the samples shows the presence of an oxidation gradient at the interface between the FeO core and the Fe3O4 shell. The EMCD measurements show that the nanoparticles are composed of four different zones with distinct magnetic moment in a concentric, onion-type, structure. These magnetic areas correlate spatially with the oxidation and composition gradient with the magnetic moment being largest at the surface and decreasing toward the core. The results show that the combination of EELS compositional mapping and EMCD can provide very valuable information on the inner magnetic structure and its correlation to the microstructure of magnetic nanoparticles.
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Evidence is emerging of the pandemic disproportionately impacting communities of color. This study investigates mental health distress among essential workers during the coronavirus pandemic across race and ethnicity. We evaluate individual responses to the patient health questionnaire and general anxiety disorder questionnaire using a unique, nationally representative data set. Our findings suggest that essential healthcare workers reported the highest rates of mental health distress at the beginning of the coronavirus pandemic. However, when evaluated across race and ethnicity, we find that Black essential healthcare workers disproportionately report symptoms of anxiety; while, Hispanic essential healthcare workers disproportionately report symptoms of depression. Additionally, we find that being a Black or Hispanic essential nonhealthcare worker is associated with higher levels of distress related to anxiety and depression. These findings highlight the additional dimensions to which Black and Hispanic Americans may be disproportionately affected by the coronavirus pandemic. Furthermore, it calls into question how the essential worker classification, compounded by US unemployment policies, is potentially amplifying the mental health distress experienced by workers.
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BACKGROUND: Bronchiectasis (BE) impact the clinical course and prognosis of patients with chronic obstructive pulmonary disease (COPD). Yet, the temporal evolution of BE in these patients is unknown. This study seeks to assess the temporal evolution of BE in persons with COPD. METHODS: 201 moderate-to-severe patients were recruited between 2004 and 2007 and followed up at least every 6 monts (median of 102 months). To investigate the temporal evolution of BE, in 2015 a second high-resolution computed tomography scan (HRCT) was obtained in survivors and compared with the one obtained at recruitment. RESULTS: 99 (49.3%) died during follow-up. The second HRCT could be obtained in 77 patients and showed that (1) in 27.3% of patients BE never developed, in 36.4% they remained stable, in 16.9% they increased in size and/or extension, and in 19.5% new BE emerged; and that (2) the presence of chronic purulent sputum (hazard ratio [HR], 2.8 [95% confidence interval {CI}, 1.3-5.8]), number of hospitalizations due to exacerbatons (HR, 1.2 [95% CI, 1.1-1.5]), and number of pathogenic microorganism (PPM) isolations (HR, 1.1 [95% CI, 1.02-1.3]) were independent risk factors for the progression or development of BE. CONCLUSIONS: The presence of chronic purulent sputum production, number of PPMs isolated in sputum, and number of hospitalizations due to exacerbations of COPD are independent risk factors of BE progression in patients with COPD.
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Bronquiectasia , Bronquitis , Enfermedad Pulmonar Obstructiva Crónica , Bronquiectasia/complicaciones , Bronquiectasia/diagnóstico por imagen , Bronquiectasia/epidemiología , Progresión de la Enfermedad , Humanos , Enfermedad Pulmonar Obstructiva Crónica/complicaciones , Enfermedad Pulmonar Obstructiva Crónica/epidemiología , Índice de Severidad de la Enfermedad , EsputoRESUMEN
Screening of cellular activity for inhibitors of histone lysine modifiers is most frequently performed indirectly by analyzing changes in the total levels of histone marks targeted by lysine methylases/demethylases. However, inhibition of histone lysine modifiers often leads to local rather than total changes in histone marks. Also, because histone modifications can be modulated by more than one cellular enzyme, it is not always clear whether changes in histone marks are a direct or indirect consequence of the inhibitor treatment applied. Direct assessment of target occupation can provide a useful tool to quantify the fraction of an epigenetic modifier that is bound to a pharmacological inhibitor (target engagement). Here, we developed and used a novel chemoprobe-based immunoassay to quantify target engagement in cells. Quantification of the fraction of free KDM1A was made possible, in an immune-based assay, by coupling a biotinylated chemoprobe to a warhead capable of selectively and irreversibly binding to the free active form of KDM1A. The results obtained confirmed that this approach is able to determine the degree of target engagement in a dose-dependent manner. Furthermore, the assay can be also used on tissue extracts to analyze the in vivo pharmacokinetics and pharmacodynamics relationship of KDM1A inhibitors, as has been exemplified with ORY-1001 (iadademstat), a potent and irreversible inhibitor of KDM1A. The principle of this assay may be applied to other targets, and the KDM1A probe may be employed in chemoproteomic analyses.
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Inhibidores Enzimáticos , Histona Demetilasas/antagonistas & inhibidores , Histona Demetilasas/metabolismo , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacocinética , Inhibidores Enzimáticos/farmacología , Humanos , Células THP-1RESUMEN
Obstructive sleep apnoea (OSA) and pulmonary embolism (PE) remain major health issues worldwide. Data from pathophysiological studies suggest that both intermittent hypoxia and sleep fragmentation are associated with increased blood coagulability, endothelial dysfunction and venous stasis. There is growing evidence that OSA is potentially prevalent in and a risk factor for PE. Conversely, patients with acute PE have two to four times greater risk of moderate-to-severe OSA. The role of continuous positive airway pressure (CPAP) treatment in improving clinically meaningful outcomes in PE patients remains unclear, although some authors have suggested that CPAP could improve the hypercoagulability state and normalise circadian alterations in some of the coagulation molecules, as observed in patients with OSA. Emerging research highlights the complex interdependent relationships between OSA and PE, emphasising the need for rigorous, well-powered trials that address the impact of OSA and its treatment on the prevention and management of PE. Undoubtedly, these will require closer collaboration between the sleep medicine and clinical/venous thromboembolism communities.
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Apnea Obstructiva del Sueño/complicaciones , Apnea Obstructiva del Sueño/fisiopatología , Tromboembolia Venosa/complicaciones , Tromboembolia Venosa/fisiopatología , Coagulación Sanguínea , Estudios de Casos y Controles , Ritmo Circadiano , Presión de las Vías Aéreas Positiva Contínua , Humanos , Hipoxia/fisiopatología , Estudios Prospectivos , Embolia Pulmonar , Factores de Riesgo , Sueño , Apnea Obstructiva del Sueño/terapia , Privación de Sueño/fisiopatología , Resultado del Tratamiento , Tromboembolia Venosa/terapiaRESUMEN
A desire to replicate the structural and functional complexity of proteins with structured, sequence-specific oligomers motivates study of the structural features of water-soluble peptoids (N-substituted glycine oligomers). Understanding the molecular-level details of peptoid self-assembly in water is essential to advance peptoids' application as novel materials. Peptoid 1, an amphiphilic, putatively helical peptoid previously studied in our laboratory, shows evidence of self-association in aqueous solution. In this work, we evaluate how changes to aqueous solution conditions influence the self-association of 1. We report that changes to pH influence the fluorescence and CD spectroscopic features as well as the peptoid's interaction with a solvatochromic fluorophore and its apparent size as estimated by size exclusion chromatography. Addition of guanidine hydrochloride and ammonium sulfate also modulate spectroscopic features of the peptoid, its interaction with a solvatochromic fluorophore, and its elution in size exclusion chromatography. These data suggest that the ordering of the self-assembly changes in response to pH and with solvent additives and is more ordered at higher pH and in the presence of guanidine hydrochloride. The deeper understanding of the self-association of 1 afforded by these studies informs the design of new stimuli-responsive peptoids with stable tertiary or quaternary structures.
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Peptoides/química , Agua/química , Dicroismo Circular , Concentración de Iones de Hidrógeno , Solubilidad , Solventes/química , Espectrometría de FluorescenciaRESUMEN
Although adequate adherence is paramount in achieving the beneficial effects of continuous positive airway pressure therapy in patients with obstructive sleep apnea, long-term adherence and the variables involved in continuous positive airway pressure compliance in patients with resistant hypertension and obstructive sleep apnea are yet unknown. We conducted a prospective, multicentre, observational study in 177 patients recruited from hypertensive units with resistant hypertension confirmed by means of 24-hr blood pressure monitoring (blood pressure ≥â 130 and/or ≥â 80â mmHg, despite taking at least three antihypertensive drugs or <â 130/80â mmHg with >â 3 drugs) and obstructive sleep apnea (apnea-hypopnea index ≥â 5 in a respiratory polygraph) who were prescribed continuous positive airway pressure treatment. Good adherence was defined as an average cumulative continuous positive airway pressure use of ≥â 4â hr per night at the end of the follow-up. A multivariate Cox regression analysis was performed to identify independent predictors of continuous positive airway pressure adherence. Patients were followed for a median of 57.6 (42-72)â months after initiating continuous positive airway pressure therapy. At the end of the follow-up, the median continuous positive airway pressure use was 5.7 (inter-quartile range 3.9-6.6) hr per night, and 132 patients (74.5%) showed good continuous positive airway pressure adherence. The only baseline variable associated with poor adherence was the presence of previous stroke (hazard ratio 4.00, 95% confidence interval 1.92-8.31). Adequate adherence at 1â month also predicted good adherence at the end of the follow-up (hazard ratio 14.4, 95% confidence interval 4.94-56). Both variables also predicted adherence at a threshold of 6â hr per night. Our results show that good continuous positive airway pressure adherence is an achievable and feasible goal in patients with resistant hypertension and obstructive sleep apnea. Previous stroke and short-term adherence predicted long-term adherence.
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Presión de las Vías Aéreas Positiva Contínua/métodos , Hipertensión/terapia , Apnea Obstructiva del Sueño/terapia , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios ProspectivosRESUMEN
The atomic structure of nanoparticles can be easily determined by transmission electron microscopy. However, obtaining atomic-resolution chemical information about the individual atomic columns is a rather challenging endeavor. Here, crystalline monodispersed spinel Fe3O4/Mn3O4 core-shell nanoparticles have been thoroughly characterized in a high-resolution scanning transmission electron microscope. Electron energy-loss spectroscopy (EELS) measurements performed with atomic resolution allow the direct mapping of the Mn2+/Mn3+ ions in the shell and the Fe2+/Fe3+ in the core structure. This enables a precise understanding of the core-shell interface and of the cation distribution in the crystalline lattice of the nanoparticles. Considering how the different oxidation states of transition metals are reflected in EELS, two methods of performing a local evaluation of the cation inversion in spinel lattices are introduced. Both methods allow the determination of the inversion parameter in the iron oxide core and manganese oxide shell, as well as detecting spatial variations in this parameter, with atomic resolution. X-ray absorption measurements on the whole sample confirm the presence of cation inversion. These results present a significant advance toward a better correlation of the structural and functional properties of nanostructured spinel oxides.
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Nonlinear optical nanostructured materials are gaining increased interest as optical limiters for various applications, although many of them suffer from reduced efficiencies at high-light fluences due to photoinduced deterioration. The nonlinear optical properties of ferrite core/shell nanoparticles showing their robustness for ultrafast optical limiting applications are reported. At 100 fs ultrashort laser pulses the effective two-photon absorption (2PA) coefficient shows a nonmonotonic dependence on the shell thickness, with a maximum value obtained for thin shells. In view of the local electric field confinement, this indicates that core/shell is an advantageous morphology to improve the nonlinear optical parameters, exhibiting excellent optical limiting performance with effective 2PA coefficients in the range of 10-12 cm W-1 (100 fs excitation), and optical limiting threshold fluences in the range of 1.7 J cm-2 . These values are comparable to or better than most of the recently reported optical limiting materials. The quality of the open aperture Z-scan data recorded from repeat measurements at intensities as high as 35 TW cm-2 , indicates their considerably high optical damage thresholds in a toluene dispersion, ensuring their robustness in practical applications. Thus, the high photostability combined with the remarkable nonlinear optical properties makes these nanoparticles excellent candidates for ultrafast optical limiting applications.
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Understanding the microstructure in heterostructured nanoparticles is crucial to harnessing their properties. Although microscopy is ideal for this purpose, it allows for the analysis of only a few nanoparticles. Thus, there is a need for structural methods that take the whole sample into account. Here, a novel bulk-approach based on the combined analysis of synchrotron X-ray powder diffraction with whole powder pattern modeling, Rietveld and pair distribution function is presented. The microstructural temporal evolution of FeO/Fe3 O4 core/shell nanocubes is studied at different time intervals. The results indicate that a two-phase approach (FeO and Fe3 O4 ) is not sufficient to successfully fit the data and two additional interface phases (FeO and Fe3 O4 ) are needed to obtain satisfactory fits, i.e., an onion-type structure. The analysis shows that the Fe3 O4 phases grow to some extent (≈1 nm) at the expense of the FeO core. Moreover, the FeO core progressively changes its stoichiometry to accommodate more oxygen. The temporal evolution of the parameters indicates that the structure of the FeO/Fe3 O4 nanocubes is rather stable, although the exact interface structure slightly evolves with time. This approach paves the way for average studies of interfaces in different kinds of heterostructured nanoparticles, particularly in cases where spectroscopic methods have some limitations.
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A crucial challenge in nanotherapies is achieving accurate and real-time control of the therapeutic action, which is particularly relevant in local thermal therapies to minimize healthy tissue damage and necrotic cell deaths. Here, a nanoheater/thermometry concept is presented based on magnetoplasmonic (Co/Au or Fe/Au) nanodomes that merge exceptionally efficient plasmonic heating and simultaneous highly sensitive detection of the temperature variations. The temperature detection is based on precise optical monitoring of the magnetic-induced rotation of the nanodomes in solution. It is shown that the phase lag between the optical signal and the driving magnetic field can be used to detect viscosity variations around the nanodomes with unprecedented accuracy (detection limit 0.0016 mPa s, i.e., 60-fold smaller than state-of-the-art plasmonic nanorheometers). This feature is exploited to monitor the viscosity reduction induced by optical heating in real-time, even in highly inhomogeneous cell dispersions. The magnetochromic nanoheater/thermometers show higher optical stability, much higher heating efficiency and similar temperature detection limits (0.05 °C) compared to state-of-the art luminescent nanothermometers. The technological interest is also boosted by the simpler and lower cost temperature detection system, and the cost effectiveness and scalability of the nanofabrication process, thereby highlighting the biomedical potential of this nanotechnology.