Characterization and tracking of the three-dimensional translational motion and rotation of single nanoparticles using a fiber-based microcavity with high finesse

Sophisticated new sensor techniques have to be developed to enable the detection of the temporal dynamics of single nanoparticles and molecules. Some of the new microscopy techniques are based on nanoparticle labeling, achieving high sensitivity on the single nanometer scale, but also changing the nanoparticle\u27s natural behavior. In this work, a fiber-based Fabry-Pérot (FP) microcavity with high finesse is presented, which allows the detection of unlabeled nanoparticles. Single nanoparticle resolution is achieved by forcing the light to thousands of round trips between two high-reflective mirrors of micrometer size and consequently enhancing the interaction between light and nanoparticle. So far, fiber-based FP cavities in air, vacuum and liquid helium have been reported in the past. In order to enable single nanoparticle measurements in liquids, two different microfluidic channels are demonstrated. Both channels allow an easy integration of the fiber-based FP cavity, provide a controllable laminar flow, and the measurement of small sample volumes. Furthermore the microfluidic channel and the integrated FP cavity are embedded in a sensing platform, that provides a high passive stability of $\sim1$pm and a low root-mean-square measurement noise of $0.39$pm. Combined with a high Cooperativity of the FP cavity in water of $C\sim Q\lambda_0^3/({n_{\mathrm{m}}^3 V_{\mathrm{m}}})=2.1\cdot10^4$ single SiO$_2$ nanospheres with a hydrodynamic radius down to $11.7$nm can already be detected. In this work, it is shown that the FP cavity allows the detection of hundreds of single SiO$_2$ nanosphere transit events within a few hours. From the derived statistical data, the SiO$_2$ nanosphere\u27s mean polarizability, as well as the mean effective refractive index, are deduced. Here, the first important finding is the detection of the nanosphere\u27s expanded size in pure water originating from a hydrate shell. This allows the estimation of the mean thickness as well as the mean refractive index of the hydrate shell of different SiO$_2$ nanosphere samples. Besides, the effect of salt on the hydrate shell is investigated. Already small salt concentrations presumably lead to a suppression of the formation of the hydrate shell and give indications of the significantly lower polarizability of the bare nanosphere. Furthermore, by improving the measurement time resolution, the polarizability of a single SiO$_2$ nanosphere is determined. In addition, the autocorrelation of the dispersive signal of several SiO$_2$ nanosphere transit events is compared with the theoretical numerical autocorrelation of a punctiform nanosphere and the Monte Carlo simulated autocorrelation of several nanosphere transit events with expanded size. As a result, a purely diffusive motion is identified. Completely new is the detection of the three-dimensional Brownian motion of a single nanosphere with a microcavity. By the simultaneous measurement of the dispersive shifts of the fundamental and two higher-order transverse modes, the three-dimensional coordinate of the nanosphere can be derived with a high spatial resolution of $8$nm and a high temporal resolution of $0.3$ms. This is first analyzed by simulations and then demonstrated with measured signals. From the three-dimensional track, the nanosphere\u27s diffusivity, as well as its hydrodynamic radius, is deduced. The rotational diffusion of single anisotropically shaped nanoparticles is measured by the polarization-split fundamental mode with a high temporal resolution of $0.07$ms. Already nanospheres with a specified roundness of >0.98 can be investigated in their rotational diffusion, showing that this detection method is highly sensitive. The presented FP microcavity already achieves a sensitivity, which allows the detection of different molecules like viruses, ribosomes, and exosomes. Therefore, it is a promising candidate for a future detection of the dynamics of single, unlabeled molecules with a small molecular mass

Tracking Brownian motion in three dimensions and characterization of individual nanoparticles using a fiber-based high-finesse microcavity

The dynamics of nanosystems in solution contain a wealth of information with relevance for diverse fields ranging from materials science to biology and biomedical applications. When nanosystems are marked with fluorophores or strong scatterers, it is possible to track their position and reveal internal motion with high spatial and temporal resolution. However, markers can be toxic, expensive, or change the object's intrinsic properties. Here, we simultaneously measure dispersive frequency shifts of three transverse modes of a high-finesse microcavity to obtain the three-dimensional path of unlabeled SiO$_2$ nanospheres with $300$$\mathrm{\mu}$s temporal and down to $8$nm spatial resolution. This allows us to quantitatively determine properties such as the polarizability, hydrodynamic radius, and effective refractive index. The fiber-based cavity is integrated in a direct-laser-written microfluidic device that enables the precise control of the fluid with ultra-small sample volumes. Our approach enables quantitative nanomaterial characterization and the analysis of biomolecular motion at high bandwidth.Comment: 7 pages, 3 figure

LIMITES ENTRE LITERATURA, HISTÓRIA E TRADIÇÃO EM O QUE TERIA NA TROUXA DE MARIA?, DE DIANE VALDEZ

Este trabalho buscou compreender como a obra O que teria na trouxa de Maria? (2017), de Diane Valdez e ilustrações de Alda Miriam Ribeiro, está situada no panorama das tendências estéticas da literatura infantil e juvenil em Goiás e da literatura brasileira contemporânea para jovens leitores. A partir de estudos de Tietzmann Silva (1987; 2004; 2012; 2016), foi analisado como a literatura infantil e juvenil de Valdez apresenta características históricas e geográficas do espaço goiano, bem como os hábitos e costumes das categorias sociais dos lugares de onde se narra. Ademais, tendo em vista as conceituações propostas por Edmir Perrotti (1986), observou-se que a obra de Valdez rompe com o utilitarismo e o utilitarismo às avessas quando se volta para a elaboração de um discurso memorialístico plurissignificativo, sem que se feche na transmissão de ensinamentos. A obra de Valdez propõe um outro olhar sobre os marginalizados, dando ênfase ao protagonismo de uma figura alheia aos discursos oficiais que permeiam a historiografia de e sobre Goiás

Despossessão, violências e a potência transformadora: um olhar interseccional sobre as remoções

The present article takes the following question as its starting point: What does it mean to think about eviction and its consequences based on the narratives of women who have faced these processes? By examining the narratives and thoughts of women who have either undergone eviction or are living under its threat, it is possible to highlight dimensions of the process that may otherwise go unnoticed by analyses that focus on other dimensions, and which do not appraise the characteristics of those being evicted and what this represents in terms of the totality of the phenomenon. By shedding light on the multiplicity of impacts resulting from the eviction processes, it is possible to return to the conceptual notion itself, so that it may be formulated from the bottom up, i.e., from the various experiences that comprise it. Ultimately, what is eviction? What does it mean to live under the threat of losing your home?O presente artigo parte da seguinte questão: o que significa pensar a remoção e suas consequências com base na narrativa de mulheres que enfrentam esses processos? Ao recuperar as narrativas e as reflexões de mulheres que sofreram remoção ou se encontram em situação de ameaça, é possível iluminar dimensões do processo que podem passar despercebidas ou ser encobertas por análises cujo enfoque recai sobre outras dimensões, que não passam por uma reflexão sobre as características de quem está sendo removido, e sobre o significado disso diante da totalidade do fenômeno. Ao lançar luz sobre a multiplicidade dos impactos decorrentes dos processos de remoção, pode-se retomar a própria noção conceitual para, então, formulá-la desde baixo, quer dizer, a partir das várias experiências que a compõem. Afinal, o que é remoção? O que significa viver sob a ameaça de perder o lugar onde se vive

Scanning cavity microscopy of a single-crystal diamond membrane

Spin-bearing color centers in the solid state are promising candidates for the realization of quantum networks and distributed quantum computing. A remaining key challenge is their efficient and reliable interfacing to photons. Incorporating minimally processed membranes into open-access microcavities represents a promising route for Purcellenhanced spin-photon interfaces: it enables significant emission enhancement and efficient photon collection, minimizes deteriorating influence on the quantum emitter, and allows for full spatial and spectral tunability, key for controllably addressing suitable emitters with desired optical and spin properties. Here, we study the properties of a high-finesse fiber Fabry-Pérot microcavity with integrated single-crystal diamond membranes by scanning cavity microscopy. We observe spatially resolved the effects of the diamond-air interface on the cavity mode structure: a strong correlation of the cavity finesse and mode structure with the diamond thickness and surface topography, significant transverse-mode mixing under diamond-like conditions, and mode-character-dependent polarization-mode splitting. Our results reveal the influence of the diamond surface on the achievable Purcell enhancement, which helps to clarify the route towards optimized spin-photon interfaces

Scanning cavity microscopy of a single-crystal diamond membrane

Spin-bearing color centers in the solid state are promising candidates for the realization of quantum networks and distributed quantum computing. A remaining key challenge is their efficient and reliable interfacing to photons. Incorporating minimally processed membranes into open-access microcavities represents a promising route for Purcellenhanced spin-photon interfaces: it enables significant emission enhancement and efficient photon collection, minimizes deteriorating influence on the quantum emitter, and allows for full spatial and spectral tunability, key for controllably addressing suitable emitters with desired optical and spin properties. Here, we study the properties of a high-finesse fiber Fabry-P\'erot microcavity with integrated single-crystal diamond membranes by scanning cavity microscopy. We observe spatially resolved the effects of the diamond-air interface on the cavity mode structure: a strong correlation of the cavity finesse and mode structure with the diamond thickness and surface topography, significant transverse-mode mixing under diamond-like conditions, and mode-character-dependent polarization-mode splitting. Our results reveal the influence of the diamond surface on the achievable Purcell enhancement, which helps to clarify the route towards optimized spin-photon interfaces

Importin α7 Is Essential for Zygotic Genome Activation and Early Mouse Development

Importin α is involved in the nuclear import of proteins. It also contributes to spindle assembly and nuclear membrane formation, however, the underlying mechanisms are poorly understood. Here, we studied the function of importin α7 by gene targeting in mice and show that it is essential for early embryonic development. Embryos lacking importin α7 display a reduced ability for the first cleavage and arrest completely at the two-cell stage. We show that the zygotic genome activation is severely disturbed in these embryos. Our findings indicate that importin α7 is a new member of the small group of maternal effect genes

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others