The upconversion quantum yield (UCQY):a review to standardize the measurement methodology, improve comparability, and define efficiency standards

Advancing the upconversion materials field relies on accurate and contrastable photoluminescence efficiency measurements, which are characterised by the absolute upconversion quantum yield (UCQY). However, the methodology for such measurements cannot be extrapolated directly from traditional photoluminescence quantum yield techniques, primarily due to issues that arise from the non-linear behaviour of the UC process. Subsequently, no UCQY standards exist, and significant variations in their reported magnitude can occur between laboratories. In this work, our aim is to provide a path for determining and reporting the most reliable UCQYs possible, by addressing all the effects and uncertainties that influence its value. Here the UCQY standard, at a given excitation power density, is defined under a range of stated experimental conditions, environmental conditions, material properties, and influential effects that have been estimated or corrected for. A broad range of UCQYs reported for various UC materials are scrutinized and categorized based on our assertion of the provided information associated with each value. This is crucial for improved comparability with other types of photoluminescent materials, and in addition, the next generation of UC materials can be built on top of these reliable standards

Timing of sperm capacitation appears to be programmed according to egg availability in the female genital tract

The time course of the level of A23187-induced acrosome reaction between human and rabbit spermatozoa was compared. It was extended in the former (a periodic ovulator) and short in the latter (an induced ovulator). This finding suggests that the capacitated state is programmed to maximize the prospects that an ovulated egg will meet spermatozoa in the best functional state.Fil: Giojalas, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Biología Celular; ArgentinaFil: Rovasio, Roberto Americo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Biología Celular y Molecular; ArgentinaFil: Fabro, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Biología Celular y Molecular; ArgentinaFil: Gakamsky, Anna. Weizmann Institute of Science; IsraelFil: Eisenbach, Michael. Weizmann Institute of Science; Israe

Human sperm chemotaxis: Both the oocyte and its surrounding cumulus cells secrete sperm chemoattractants

Background: Human sperm chemotaxis to pre-ovulatory follicular fluid is well established in vitro. However, it is not known whether the female's oocyte-cumulus complex secretes sperm chemoattractants subsequent to ovulation (for enabling sperm chemotaxis within the Fallopian tube) and, if so, which of these cell types - the oocyte or the cumulus oophorus - is the physiological origin of the secreted chemoattractant. Methods: By employing a directionality-based chemotaxis assay, we examined whether media conditioned with either individual, mature (metaphase II) human oocytes or the surrounding cumulus cells attract human sperm by chemotaxis. Results: We observed sperm chemotaxis to each of these media, suggesting that both the oocyte and the cumulus cells secrete sperm chemoattractants. Conclusions: These observations suggest that sperm chemoattractants are secreted not only prior to ovulation within the follicle, as earlier studies have demonstrated, but also after oocyte maturation outside the follicle, and that there are two chemoattractant origins: the mature oocyte and the surrounding cumulus cells.Fil: Sun, Fei. Weizmann Institute of Science. Department of Biological Chemistry; IsraelFil: Bahat, Anat. Weizmann Institute of Science. Department of Biological Chemistry; IsraelFil: Gakamsky, Anna. Weizmann Institute of Science. Department of Biological Chemistry; IsraelFil: Girsh, Eliezer. Ben Gurion University of the Negev; IsraelFil: Katz, Nathan. Ben Gurion University of the Negev; IsraelFil: Giojalas, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Biología Celular y Molecular; ArgentinaFil: Tur-Kaspa, Ilan. Ben Gurion University of the Negev; IsraelFil: Eisenbach, Michael. Weizmann Institute of Science. Department of Biological Chemistry; Israe

State transition diagrams for the modes during midsections in normal, alcohol-, cocaine I-, and Cocaine II-treated flies.

<p>Bold large font size numerals highlight high transition rates.</p

Density plots of spatial and angular parameters.

<p>Blue line – empirical distribution, green line – the Gaussians established by the EM algorithm, red line – the algebraic summation of the two Gaussians. The threshold value is provided by the x-value at the intersection point between the Gaussians.A) Spatial spread values for progression segments extending between two successive arrests; B) Angular spread values for segments extending between 2 successive arrests in <i>rotation of body axis</i>. The left peak of the density plot has an asymmetrical shape, which is in some cases better fitted with two Gaussians. We considered this peak as representing fluctuations in orientation caused by both noise in the detection system and in real small body movements (body wobble). Since we were interested in identification of segments with pronounced body rotations, an intersection point between the two rightmost Gaussians was accepted as the threshold for angular spread above which a segment was counted as a body rotation;. C) Angular spread values for segments extending between 2 successive arrests of the velocity vector (intervals in which the fly's path direction is stationary); D) Distances from the wall for all data points belonging to progression segments. The leftmost Gaussian corresponds to the wall zone, the middle to the near wall zone, and the rightmost corresponds to the central zone. Data were pooled from 8 intact flies. The intersection point between the middle and the rightmost peaks (10 mm) was chosen as a boundary defining the central zone of the arena.</p

The proportion of the angular interval during the different phases of a movement segment in normal, alcohol- and cocaine treated flies.

<p>Dark blue – φ = 0±22.5; light blue – φ = 45±22.5; green – φ = 90±22.5 deg; orange – φ = 135±22.5 deg; brown – φ = 180±22.5 deg. Each stack bar represents the proportion out of the whole population of the misalignment angles characterizing each of the mode types in the normal and in the treated flies. Proportions were calculated for the data pooled from 8 flies.</p

Frame classification and coding scheme.

<p>A) a plot of the scalar values V_c obtained during a movement segment. Progression is marked by spatial Spread, ‘D’, values exceeding the threshold distinguishing lingering (staying in place) episodes from movement segments (D_ling denotes the threshold value for lingering; see methods). B) A plot of the velocity vector ω_v, denoting the change in the direction of translation of the fly's center, includes 3 bouts of change of direction, where only the first exceeds the threshold Ψ, the angular spread of the velocity vector distinguishing between straight and curved paths. C) The first 2 bouts are accompanied by a rotation of the fly, but only the first rotation exceeds the threshold of Θ, the angular spread of the fly's body orientation distinguishing between rotations and fixed orientation. The gray rectangles highlight segments of scalar and vectorial values exceeding the respective thresholds thus delineating segments marked by significant amounts of translation, curvature and rotation. The mode of coordination between the 3 kinematic variables is summarized and coded in D) by the letters: L for Lingering, C for Fixated-Front-on-Curved-Path, B for Rotation-on-Straight-Path and A for Fixed-Front-on-Straight-Path. E) The body-related directions of movement (angular interval between the direction of progression and body orientation. ±45° coded by 1; ±90° coded by 2; ±135° coded by 3; 180° coded by 4; Lingering coded by 9).</p