Synergistic interactions of binary suspensions of magnetic anisotropic particles.

We report the effect of the dipole-dipole interaction and shape anisotropy in suspensions of permanently magnetized anisotropic particles. We quantify the dipolar interaction energy using an ellipsoid-dipole model to describe particles with similar or dissimilar shapes. The expression captures the physics of the point-dipole interaction energy between uniformly magnetized spherical particles. Additionally, we report Monte Carlo simulations to describe the effect of dipolar interaction and shape anisotropy under different field strengths. Results show that the shape anisotropy and dipolar interactions modify the head-to-tail interaction with respect to spheres, promoting dendritic and barbed-wire structures in uniform ellipsoids and binary mixtures, respectively. Furthermore, competing entropic and energy interactions generate a synergistic effect reducing the magnetic response of binary suspensions.

Occupational radiation exposure assessment during the management of [68Ga]Ga-DOTA-TOC.

BACKGROUND: Since it was first approved in Europe in 2016, the gallium-68 (68Ga) radiopharmaceutical [68Ga]Ga-DOTA-TOC has been widely used for imaging of somatostatin receptor (SSTR) positive tumours using positron emission tomography-computed tomography (PET/CT). Significant patient benefits have been reported, so its use is rapidly increasing. However, few studies have been published regarding occupational doses to nuclear medicine personnel handling this radiopharmaceutical, despite its manual usage at low distances from the skin and the beta-emission decay scheme, which may result in an increased absorbed dose to their hands. In this context, this study aims to analyse the occupational exposure during the administration of [68Ga]Ga-DOTA-TOC for PET/CT imaging. For this purpose, extremity, eye lens and whole-body dosimetry in terms of Hp(0.07), Hp(3) and Hp(10), respectively, was conducted on six workers with both thermoluminescent dosimeters, and personal electronic dosimeters. RESULTS: The non-dominant hand is more exposed to radiation than the dominant hand, with the thumb and the index fingertip being the most exposed sites on this hand. Qualitative analysis showed that when no shielding is used during injection, doses increase significantly more in the dominant than in the non-dominant hand, so the use of shielding is strongly recommended. While wrist dosimeters may significantly underestimate doses to the hands, placing a ring dosimeter at the base of the ring or middle finger of the non-dominant hand may give a valuable estimation of maximum doses to the hands if at least a correction factor of 5 is applied. Personal equivalent doses for the eyes did not result in measurable values (i.e., above the lowest detection limit) for almost all workers. The extrapolated annual dose estimations showed that there is compliance with the annual dose limits during management of [68Ga]Ga-DOTA-TOC for diagnostics with PET in the hospital included in this study. CONCLUSIONS: Imaging with [68Ga]Ga-DOTA-TOC is a safe process for the workers performing the administration of the radiopharmaceutical, including intravenous injection to the patient and the pre- and post-activity control, as it is highly unlikely that annual dose limits will be exceeded if good working practices and shielding are used.

Surface Morphology-Enhanced Delivery of Bioinspired Eco-Friendly Microcapsules.

We report the development of novel mineralized protein microcapsules to address critical challenges in the environmental impact and performance of consumer, pharmaceutical, agrochemical, cosmetic, and paint products. We designed environment-friendly capsules composed of proteins and biominerals as an alternative to solid microplastic particles or core-shell capsules made of nonbiodegradable synthetic polymeric resins. We synthesized mineralized capsule surface morphologies to mimic the features of natural pollens, which dramatically improved the deposition of high value-added fragrance chemicals on target substrates in realistic application conditions. A mechanistic model accurately captures the observed enhanced deposition behavior and shows how surface features generate an adhesive torque that resists shear detachment. Mineralized protein capsule performance is shown to depend both on material selection that determines van der Waals attraction and on capsule-substrate energy landscapes as parameterized by a geometric taxonomy for surface morphologies. These findings have broad implications for engineering multifunctional environmentally friendly delivery systems.

Hard superellipse phases: particle shape anisotropy & curvature.

We report computer simulations of two-dimensional convex hard superellipse particle phases vs. particle shape parameters including aspect ratio, corner curvature, and sidewall curvature. Shapes investigated include disks, ellipses, squares, rectangles, and rhombuses, as well as shapes with non-uniform curvature including rounded squares, rounded rectangles, and rounded rhombuses. Using measures of orientational order, order parameters, and a novel stretched bond orientational order parameter, we systematically identify particle shape properties that determine liquid crystal and crystalline phases including their coarse boundaries and symmetry. We observe phases including isotropic, nematic, tetratic, plastic crystals, square crystals, and hexagonal crystals (including stretched variants). Our results catalog known benchmark shapes, but include new shapes that also interpolate between known shapes. Our results indicate design rules for particle shapes that determine two-dimensional liquid, liquid crystalline, and crystalline microstructures that can be realized via particle assembly.

Anisotropic colloidal interactions & assembly in AC electric fields.

We match experimental and simulated configurations of anisotropic epoxy colloidal particles in high frequency AC electric fields by identifying analytical potentials for dipole-field and dipole-dipole interactions. We report an inverse Monte Carlo simulation algorithm to determine optimal fits of analytical potentials by matching simulated and experimental distribution functions for non-uniform liquid, liquid crystal, and crystal microstructures in varying amplitude electric fields. Two potentials that include accurate particle volume and dimensions along with a concentration dependent prefactor quantitatively capture experimental observations. At low concentrations, an effective ellipsoidal point dipole potential works well, whereas a novel stretched point dipole potential is found to be suitable at all concentrations, field amplitudes, and degrees of ordering. The simplicity, accuracy, and adjustability of the stretched point dipole potential suggest it can be applied to model field mediated microstructures and assembly of systematically varying anisotropic particle shapes.

Non-equilibrium steady-state colloidal assembly dynamics.

Simulations and experiments are reported for nonequilibrium steady-state assembly of small colloidal crystal clusters in rotating magnetic fields vs frequency and amplitude. High-dimensional trajectories of particle coordinates from image analysis of experiments and from Stokesian Dynamic computer simulations are fit to low-dimensional reaction coordinate based Fokker-Planck and Langevin equations. The coefficients of these equations are effective energy and diffusivity landscapes that capture configuration-dependent energy and friction for nonequilibrium steady-state dynamics. Two reaction coordinates that capture condensation and anisotropy of dipolar chains folding into crystals are sufficient to capture high-dimensional experimental and simulated dynamics in terms of first passage time distributions. Our findings illustrate how field-mediated nonequilibrium steady-state colloidal assembly dynamics can be modeled to interpret and design pathways toward target microstructures and morphologies.

Easy, Quick, and Reproducible Sonochemical Synthesis of CuO Nanoparticles.

Copper oxide nanoparticles (CuO NPs) were synthesized in air by reducing copper (II) sulfate pentahydrate salt (CuSO4·5H2O) in the presence of sodium borohydride. The reaction was stabilized with Hexadecyltrimethylammonium bromide (CTAB) in a basic medium and using ultrasound waves. Different molar ratios of CTAB:Cu2+ and NaBH4:Cu2+ were explored, to optimize the synthesis conditions, and to study the stability, size, and Zeta potential of the colloidal suspension. Optimum conditions to generate spherical, stable, and monodispersed nanoparticles with hydrodynamic diameters of 36 ± 1.3 nm were obtained, using 16 mM CTAB and 2 M NaBH4 (molar ratios Cu2+:CTAB:NaBH4 of 1:6:10). X-ray diffraction (XRD) was implemented, and a monoclinic CuO crystal system was formed. This demonstrated a monoclinic crystal system corresponding to CuO. The diffraction peaks were identified and confirmed according to their selected area electron diffraction (SAED) patterns.

Direct Measurements of kT-Scale Capsule-Substrate Interactions and Deposition Versus Surfactants and Polymer Additives.

We report a novel approach to directly measure the interactions and deposition behavior of functional capsule delivery systems on glass substrates versus the concentration of an anionic surfactant sodium lauryl ether sulfate (SLES) and a cationic acrylamide-acrylamidopropyltrimonium copolymer (AAC). Analyses of three-dimensional optical microscopy trajectories were used to quantify lateral diffusive dynamics, deposition lifetimes, and potentials of mean force for different solution conditions. In the absence of additives, negatively charged capsule surfaces yield electrostatic repulsion with the negatively charged substrate, which inhibits deposition. With an increasing SLES concentration below the critical micelle concentration (CMC), capsule-substrate electrostatic repulsion is mediated by the charged surfactant solution that decreases the Debye length. Above the SLES CMC, depletion attraction causes enhanced deposition until eventually depletion repulsion inhibits deposition at concentrations ∼10 wt %. Addition of an ACC causes deposition via capsule-substrate bridging at all concentrations; the weakest deposition occurs at intermediate AAC concentrations from a competition of steric repulsion and attraction via a few extended bridges. The novel measurements and models of capsule interactions and deposition on substrates in this work provide a basis to fundamentally understand and rationally design complex rinse-off cleansing formulations with optimal characteristics.

Energy landscapes for ellipsoids in non-uniform AC electric fields.

We report a closed-form analytical model for energy landscapes of ellipsoidal particles in non-uniform high-frequency AC electric fields to identify all possible particle positions and orientations. Three-dimensional equilibrium positions and orientations of prolate (rx = ry < rz), oblate (rx = rz > ry), and scalene (rx≠ry≠rz) ellipsoids are reported vs. field frequency and amplitude, which are determined from energy landscape minima. For ellipsoids within non-uniform electric fields between co-planar parallel electrodes, the number of configurations of position and orientation is 6 for prolate, 5 for oblate, and 9 for scalene ellipsoids. In addition, for coplanar electrodes, conditions are identified when particles can be treated using a quasi-2D analysis in the plane of their most probable elevation near an underlying surface. The reported expressions are valid for time-averaged interactions of ellipsoid particles in arbitrary AC electric field configurations, such that our results are applicable to electromagnetic tweezers interacting with particles having an appropriate material property contrast with the medium in the frequency range of interest.

Measurement of Anisotropic Particle Interactions with Nonuniform ac Electric Fields.

Optical microscopy measurements are reported for single anisotropic polymer particles interacting with nonuniform ac electric fields. The present study is limited to conditions where gravity confines particles with their long axis parallel to the substrate such that particles can be treated using quasi-2D analysis. Field parameters are investigated that result in particles residing at either electric field maxima or minima and with long axes oriented either parallel or perpendicular to the electric field direction. By nonintrusively observing thermally sampled positions and orientations at different field frequencies and amplitudes, a Boltzmann inversion of the time-averaged probability of states yields kT-scale energy landscapes (including dipole-field, particle-substrate, and gravitational potentials). The measured energy landscapes show agreement with theoretical potentials using particle conductivity as the sole adjustable material property. Understanding anisotropic particle-field energy landscapes vs field parameters enables quantitative control of local forces and torques on single anisotropic particles to manipulate their position and orientation within nonuniform fields.

Analysis of the complete organellar genomes of the rockweed Fucus spiralis (Fucaceae, Phaeophyceae) supports its infraspecific recognition as Fucus vesiculosus var. spiralis.

Fucus spiralis L. is a broadly distributed monoecious intertidal seaweed. The specific status of F. spiralis however is debatable. Here, we contribute to the bioinformatics and systematics of F. spiralis by analysing the complete mitochondrial and plastid genomes of a specimen from California, U.S.A. The F. spiralis mitogenome is 36,396 base pairs (bp) in length and contains 67 genes, and the plastid genome is 125,066 bp in length and contains 171 genes. The F. spiralis genomes are 99.7% and 99.8% similar in nucleotide sequence to F. vesiculosus, and support the revised classification of F. spiralis to Fucus vesiculosus var. spiralis.

General Potential for Anisotropic Colloid-Surface Interactions.

A general closed-form, analytical potential is developed for the interaction of planar surfaces with superellipsoidal particles (which includes shapes such as spheres, ellipsoids, cylinders, polygons, superspheres, etc.). The Derjaguin approximation is used with DLVO half-space interactions (e.g., electrostatics and van der Waals) to yield potentials for arbitrary particle-wall separation and orientation. The resulting potential is a function of the minimum distance between surfaces and the particle's local Gaussian curvature at the minimum distance position. The validity of the solution is reported in terms of the local Gaussian curvature (Γ) and characteristic interaction range (e.g., Debye length, κ-1, for electrostatics) based on the limits of the Derjaguin approximation. This solution is limited for superellipsoids with convex shapes and orientations where the condition κ/Γ1/2 > 2 is satisfied. The potentials reported in this work should be useful for modeling a wide range of natural and synthetic nonspherical and anisotropic colloidal particles in environmental, biological, and advanced material applications.

Nódulos periarticulares, artritis y nefropatía crónica / Periarticular nodules, arthritis and chronic nephropathy

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Magnetic Assembly and Cross-Linking of Nanoparticles for Releasable Magnetic Microstructures.

This article describes a versatile method to fabricate magnetic microstructures with complex two-dimensional geometric shapes using magnetically assembled iron oxide (Fe3O4) and cobalt ferrite (CoFe2O4) nanoparticles. Magnetic pole patterns are imprinted into magnetizable media, onto which magnetic nanoparticles are assembled from a colloidal suspension into defined shapes via the shaped magnetic field gradients. The kinetics of this assembly process are studied by evaluation of the microstructure features (e.g., line width and height) as a function of time, particle type, and volume fraction. After assembly, the iron oxide particles are cross-linked in situ and subsequently released by dissolving a sacrificial layer. The free-floating magnetic structures are shown to retain their patterned shape during manipulation with external magnetic fields.

[Daily living activity in chronic obstructive pulmonary disease: validation of the Spanish version and comparative analysis of 2 questionnaires]. / Actividades de la vida diaria en pacientes con enfermedad pulmonar obstructiva crónica: validación de la traducción española y análisis comparativo de 2 cuestionarios.

BACKGROUND AND OBJECTIVE: Exercise limitation is a common finding in chronic obstructive pulmonary disease (COPD) patients and has an important role in disease prognosis and the use of health care services. There are no questionnaires in Spanish language that evaluate the impact of the disease in the activities of daily living in these patients. Our objective was to adapt and validate the Spanish versions of 2 standard questionnaires for assessment of physical activity: the London Chest Activity of Daily Living scale (LCADL) and the Modified Baecke Physical Activity Questionnaire (modified Baecke). PATIENTS AND METHOD: After carrying out the translation and back-translation, the 2 questionnaires were administered to 55 patients with COPD (mean age [standard deviation]: 66 [8] years; forced expiratory volume in 1 s: 1.2 [0.5] l, 38 [15]%) in 2 occasions and a conventional exercise test was performed. RESULTS: Cronbach's alpha coefficient was very high (0.98 and 0.97 for LCADL and modified Baecke, respectively; p < 0.0001 each). Intraclass correlation coefficients of the test re-test reliability was also very high (0.97 and 0.96, respectively). Mean values of the questionnaires in the 2 administrations were 20 (11) vs 19 (11) for LCADL (p = 0.26), and 15 (9) vs 14 (9) for modified Baecke (p = 0.51). The 2 questionnaires showed a significant correlation with quality of life (St. George's Respiratory Questionnaire), dyspnea score (Medical Research Council scale) and 6 min walk test. CONCLUSIONS: The Spanish versions of these 2 questionnaires to assess physical activity are relibale and they display the expected association with health related quality of life, dyspnea score, and the 6 min walk test, confirming their validity. Therefore, we propose its use to complement the assessment of physical activity in those patients with COPD in whom direct measurements of this variable are not available.

Actividades de la vida diaria en pacientes con enfermedad pulmonar obstructiva crónica: validación de la traducción española y análisis comparativo de 2 cuestionarios / Daily living activity in chronic obstructive pulmonary disease: validation of the Spanish version and comparative analysis of 2 questionnaires

Fundamento y objetivo: La limitación de la capacidad de ejercicio es una característica de los pacientes con enfermedad pulmonar obstructiva crónica (EPOC), con un papel relevante en el pronóstico de la enfermedad y la utilización de servicios sanitarios. La inexistencia de cuestionarios que permitan evaluar el grado de actividad física diaria limita la evaluación clínica de estos pacientes. Nuestro objetivo ha sido adaptar al español y evaluar la fiabilidad y validez de 2 cuestionarios de actividad física formados por varias subescalas: la escala London Chest Activity of Daily Living (LCADL) y el Modified Baecke Physical Activity Questionnaire (Baecke modificado). Pacientes y método: Después de efectuar la traducción directa e inversa de ambos cuestionarios, éstos se aplicaron en 2 ocasiones a 55 pacientes con EPOC ­media (desviación estándar) de edad de 66 (8) años y de volumen espiratorio forzado en el primer segundo de 1,2 (0,5) l, con un 38 (15)% del valor de referencia­ y se realizaron pruebas convencionales de tolerancia al ejercicio. Resultados: El coeficiente alfa de Cronbach fue muy elevado en ambos casos (0,98 y 0,97 para LCADL y Baecke modificado, respectivamente; p < 0,0001 ambos). La reproducibilidad test-retest fue también muy alta para ambos cuestionarios (0,97 y 0,96, respectivamente). Para la LCADL, los valores medios obtenidos en las 2 administraciones fueron de 20 (11) frente a 19 (11) (p = 0,26), y para el Baecke modificado de 15 (9) frente a 14 (9) (p = 0,51). Ambos cuestionarios presentaron una correlación moderada con la calidad de vida (determinada por el St. George's Respiratory Questionnaire), con el índice de disnea (medida por la escala del Medical Research Council) y con la prueba de la marcha de 6 min. Conclusiones: Las versiones españolas de los cuestionarios de actividad física evaluados son fiables y ambas presentan la asociación esperada con la calidad de vida, el índice de disnea y la tolerancia al ejercicio, lo que refleja su validez. Aconsejamos la utilización complementaria de estos cuestionarios para la evaluación de la actividad física en pacientes con EPOC en ausencia de mediciones objetivas de esta variable

Background and objective: Exercise limitation is a common finding in chronic obstructive pulmonary disease (COPD) patients and has an important role in disease prognosis and the use of health care services. There are no questionnaires in Spanish language that evaluate the impact of the disease in the activities of daily living in these patients. Our objective was to adapt and validate the Spanish versions of 2 standard questionnaires for assessment of physical activity: the London Chest Activity of Daily Living scale (LCADL) and the Modified Baecke Physical Activity Questionnaire (modified Baecke). Patients and method: After carrying out the translation and back-translation, the 2 questionnaires were administered to 55 patients with COPD (mean age [standard deviation]: 66 [8] years; forced expiratory volume in 1 s: 1.2 [0.5] l, 38 [15]%) in 2 occasions and a conventional exercise test was performed. Results: Cronbach's alpha coefficient was very high (0.98 and 0.97 for LCADL and modified Baecke, respectively; p < 0.0001 each). Intraclass correlation coefficients of the test re-test reliability was also very high (0.97 and 0.96, respectively). Mean values of the questionnaires in the 2 administrations were 20 (11) vs 19 (11) for LCADL (p = 0.26), and 15 (9) vs 14 (9) for modified Baecke (p = 0.51). The 2 questionnaires showed a significant correlation with quality of life (St. George's Respiratory Questionnaire), dyspnea score (Medical Research Council scale) and 6 min walk test. Conclusions: The Spanish versions of these 2 questionnaires to assess physical activity are relibale and they display the expected association with health related quality of life, dyspnea score, and the 6 min walk test, confirming their validity. Therefore, we propose its use to complement the assessment of physical activity in those patients with COPD in whom direct measurements of this variable are not available