Metal-only Lewis pairs between group 10 metals and Tl(I) or Ag(I): insights into the electronic consequences of Z-type ligand binding†

Complexes bearing electron rich transition metal centers, especially those displaying coordinative unsaturation, are well-suited to form reverse-dative σ-interactions with Lewis acids. Herein we demonstrate the generality of zerovalent, group 10 m-terphenyl isocyanide complexes to form reverse-dative σ-interactions to Tl(I) and Ag(I) centers. Structural and spectroscopic investigations of these metal-only Lewis pairs (MOLPs) has allowed insight into the electronic consequences of Lewis-acid ligation within the primary coordination sphere of a transition metal center. Treatment of the bis-isocyanide complex, Pt(CNArDipp2)2 (ArDipp2 = 2,6-(2,6-(i-Pr)2C6H3)2C6H3) with TlOTf (OTf = [O3SCF3]−) yields the Pt/Tl MOLP [TlPt(CNArDipp2)2]OTf (1). 1H NMR and IR spectroscopic studies on 1, and its Pd congener [TlPd(CNArDipp2)2]OTf (2), demonstrate that the M → Tl interaction is labile in solution. However, treatment of complexes 1 and 2 with Na[BArF4] (ArF = 3,5-(CF3)2C6H3) produces [TlPt(CNArDipp2)2]BArF4 (3) and [TlPd(CNArDipp2)2]BArF4 (4), in which Tl(I) binding is shown to be static by IR spectroscopy and, in the case of 3, 195Pt NMR spectroscopy as well. This result provides strong evidence that the M → Tl linkages can be attributed primarily to σ-donation from the group 10 metal to Tl, as loss of ionic stabilization of Tl by the triflate anion is compensated for by increasing the degree of M → Tl σ-donation. In addition, X-ray Absorption Near-Edge Spectroscopy (XANES) on the Pd/Tl and Ni/Tl MOLPs, [TlPd(CNArDipp2)2]OTf (2) and [TlNi(CNArMes2)3]OTf, respectively, is used to illustrate that the formation of a reverse-dative σ-interaction with Tl(I) does not alter the spectroscopic oxidation state of the group 10 metal. Also reported is the ability of M(CNArDipp2)2 (M = Pt, Pd) to form MOLPs with Ag(I), yielding the complexes [AgM(CNArDipp2)2]OTf (5, M = Pt; 6, M = Pd). As was determined for the Tl-containing MOLPs 1–4, it is shown that the spectroscopic oxidation states of the group 10 metal in 5 and 6 are essentially unchanged compared to the zerovalent precursors M(CNArDipp2)2. However, in the case of 5 and 6, the formation of a dative M → Ag σ-bonding interaction facilitates the binding of Lewis bases to the group 10 metal trans to Ag, illustrating the potential of acceptor fragments to open up new coordination sites on transition metal complexes without formal, two-electron oxidation

Diseño de una pieza gráfica sobre el uso de redes sociales y la comprensión del mensaje en estudiantes de un colegio de Puente Piedra, Lima, 2017

Con esta investigación se busca determinar la relación que existe entre el diseño de una pieza gráfica sobre el uso de redes sociales y la comprensión del mensaje en estudiantes de un colegio de Puente Piedra, Lima, 2017. El presente estudio posee un enfoque cuantitativo-correlacional, de tipo no experimental. Para realizar la investigación, se seleccionó una muestra de 286 estudiantes que pertenecen a una población finita conformada por 1120 estudiantes entre hombres y mujeres de cuarto y quinto de secundaria. Se realizó un muestreo aleatorio sistemático y se hizo uso un cuestionario como instrumento de recolección de datos conformada por 11 interrogantes con 5 alternativas elaboradas según la escala de Likert. Se realizó un análisis estadístico con los datos reunidos, haciendo uso del software IBM SPSS Statistics 20.0. Dando como resultado una correlación de 0,659 y al ser mayor a 0, se afirma la existencia de una correlación positiva media entre ambas variables. La significancia de correlación resultó con un nivel de 0,000 y al ser menor a 0,01 , se rechaza la hipótesis nula y se acepta la hipótesis de investigación

Motivos de abandono de la práctica deportiva en estudiantes del 10° año de Educación General Básica de la Unidad Educativa “Víctor Manuel Peñaherrera” de la ciudad de Ibarra

Determinar cuáles son las causas que inciden en el abandono de las prácticas deportivas en los estudiantes de 10° año de E.GB de la Unidad Educativa “Víctor Manuel Peñaherrera” de la ciudad de Ibarra.El siguiente trabajo de investigación tiene como finalidad analizar los motivos de abandono de la práctica deportiva en los estudiantes de 10° año de E.G.B de la Unidad Educativa “Víctor Manuel Peñaherrera” de la ciudad de Ibarra, ya que se evidencia que un número considerable de estudiantes ya no realizaba una práctica deportiva ni actividad física ya sea en el centro educativo o fuera de él. Posteriormente se redactó la contextualización del problema, los objetivos y la justificación del problema, dónde se explicó las razones porque se realizó este diagnóstico, y a los beneficiarios de la investigación. Para la construcción del Marco Teórico, se investigó de acuerdo a las categorías relacionadas con los motivos de abandono deportivo, en orden a la matriz categorial poder identificar las causas de este suceso, en libros, revistas, internet, artículos. Después se desarrolló la Metodología, refiriendo a los tipos, métodos de investigación, las técnicas e instrumentos, población y muestra. Seguido de esto, se aplicó la encuesta de motivos de abandono deportivo en los estudiantes de estudiantes de 10° año de E.G.B, luego se procedió al análisis y discusión de resultados. Esto permitió redactar las conclusiones y recomendaciones derivadas del análisis y la tabulación de la información recolectada y por último los anexos, fotografías y certificados.Licenciatur

Automated outlier detection with machine learning in GRACE and GRACE-FO post-fit residuals

GRACE/GRACE-FO inter-satellite range-rates are the main observable for the determination of the monthly solutions of the Earthâ?Ts gravity field. The range-rates are sensitive not only to the mass distribution on the Earth, and as a consequence, the relative motion of both GRACE and GRACE-FO satellites, respectively, but also to the relative orientation of the satellites and consequently on the attitude handling, which relies on the star camera observations, object to blinding by sun and moon. In consequence the range-rates observations exhibit a number of difficult to identify error sources and efficient screening is not trivial. We therefore apply novel outlier detection methods such as Isolation Forest and Local Outlier Factor, (collectively known under the term machine learning), to flag outliers in an unsupervised fully automated way. We apply both techniques to the post-fit residuals of monthly, joined orbit and gravity field determination processes, combined with the geographical position of each observation. The flagged outliers are investigated for local geographical correlations to distinguish between unfitted signal from graivitational sources and artefacts caused by the satellite's instrumentation. For that we train a Mutual Information Neural Network, learning the mutual information between the post-fit residuals and the geographical location. The outliers flagged as artefacts are removed from the original inter-satellite range-rate data and orbit and gravity field determination process is repeated to investigate if the gravitational model fits improves

Enhancing Oxygen Uptake Efficiency Through Nasal Breathing in Aerobic Exercise

An individual’s ability to use oxygen to sustain aerobic performance, as denoted by the oxygen uptake efficiency (OUE), is calculated by dividing oxygen uptake (VO2) by ventilation (VE). Whether nasal breathing (NB) during exercise would improve OUE more significantly compared to combined breathing (CB) remains uncertain. PURPOSE: To determine the effects of utilizing NB during exercise on OUE. METHODS: Fourteen males (age: 20.57 ± 1.22 yrs; BMI: 26.03 ± 3.16 kg/m2) were randomly assigned to the NB (n = 8) or CB (n = 6) group for a 4-week supervised aerobic exercise intervention conducted four times per week for 30 minutes at moderate intensity (70% maximal heart rate). VO2max tests were performed during the pre- (week 0) and post-study (week 4) periods on a recumbent bike to determine the change in OUE, VO2, and VE at varying intensities (40%, 55%, 70%, 85%, and 100% of VO2max). The OUE was calculated as VO2 (L) ÷ VE (L). A one-way ANCOVA, controlling for OUE, VO2, and VE at pre-study, was utilized to examine if NB elicited cardiorespiratory adaptations that were superior to the CB training at post-study. A paired-sample t-test examined changes in OUE, VO2, and VE throughout the GXT from week 0 to week 4. Data are presented as mean ± standard error. RESULTS: The NB group demonstrated significantly greater [F(1,11) = 7.213, p = 0.021] OUE (0.048 ± 0.002) at 85% of VO2max than the CB (0.037 ± 0.003) group. Similarly, the NB group had a significantly greater (p = 0.014) OUE (0.025 ± 0.001) at 100% of VO2max than the CB (0.021 ± 0.001) group. Only the NB group experienced significant improvements after exercise training in VO2 at 40% ( p = 0.003, 12.02 ± 0.50 to 13.72 ± 0.59 mL·kg·min-1], 55% (p = 0.006, 16.68 ± 0.71 to 18.87 ± 0.81 mL·kg·min-1), 70% (p = 0.005, 21.16 ± 0.93 to 24.00 ± 1.01 mL·kg·min-1), 85% (p = 0.004, 25.81 ± 1.11 to 29.03 ± 1.23 mL·kg·min-1), and 100% VO2max (p = 0.005, 30.31 ± 1.30 to 34.18 ± 1.48 mL·kg·min-1). While not statistically significant, the NB group displayed a trend of reduced VE compared to the CB group. CONCLUSION: The integration of NB during aerobic exercise enhanced the OUE, particularly at higher intensities, compared to CB. This adaptation is noteworthy, as the NB group achieved a comparable range of VO2 as the CB group while maintaining a lower VE after just 1-month of training. This denotes that NB could promote enhanced oxygen movement. Future studies are warranted to investigate additional health adaptations resulting from such training benefits

The FLARE Network: Vicarious Cal/Val for Earth Observation Satellites

Calibration and characterization of radiometric and geospatial performance is necessary for the accurate retrieval of information from Earth Observation platforms. For small satellite constellations, this is especially true to ensure data quality and consistency among multiple craft that lack on-board calibration equipment. The Field Line-of-sight Automate Radiance Exposure (FLARE) Network provides an automated, on-demand calibration solution designed to meet the requirements of both agency and commercial operators by providing NIST traceable data without the need for expensive campaigns o r on-board calibration sources. FLARE radiometric performance has been verified with Landsat 8 – OLI. FLARE was successfully utilized with Planet SkySat and PlanetScope assets for rapid verification of resolution performance, and in commissioning efforts of new satellites following launch

Evaluación y diseño del sistema de agua potable en el caserío Inaco- Huacaschuque - Ancash- 2023

Esta investigación ha sido llevada a cabo en el marco de la responsabilidad social universitaria, específicamente en el ámbito del diseño de obras hidráulicas y saneamiento. El objetivo del estudio fue evaluar y diseñar el sistema de suministro de agua potable para el caserío Inaco, Huacaschuque – Áncash. Se utilizó una metodología de tipo aplicada, de diseño no experimental y con alcance correlacional que permitió obtener resultados precisos. Como resultado se encontró deficiencias significativas en el sistema actual, por lo que fue necesario realizar estudios físico-químicos y bacteriológicos del agua, así como un estudio de mecánica de suelos. Se llevó a cabo un levantamiento topográfico y se diseñó un sistema destinado a abastecer a 351 habitantes, con una proyección a 20 años. El caudal necesario fue de 0.497 l/s y se utilizó una captación en pendiente. Además, se construyó un almacenamiento de agua de 10 m3, se utilizó una tubería principal de 1 pulgada para la conducción, por último para la aducción y red de distribución tuberías principales de 1 1/2 pulg. y tuberías secundarias de ¾ pulg. En conclusión, la evaluación, los estudios realizados y el diseño propuesto contribuyeron a mejorar la calidad de vida en el caserío

Heart Failure in Humans Reduces Contractile Force in Myocardium from Both Ventricles

This study measured how heart failure affects the contractile properties of the human myocardium from the left and right ventricles. The data showed that maximum force and maximum power were reduced by approximately 30% in multicellular preparations from both ventricles, possibly because of ventricular remodeling (e.g., cellular disarray and/or excess fibrosis). Heart failure increased the calcium (Ca2+) sensitivity of contraction in both ventricles, but the effect was bigger in right ventricular samples. The changes in Ca2+ sensitivity were associated with ventricle-specific changes in the phosphorylation of troponin I, which indicated that adrenergic stimulation might induce different effects in the left and right ventricles

Intercomparison of shallow water bathymetry, hydro-optics, and benthos mapping techniques in Australian and Caribbean coastal environments

Science, resource management, and defense need algorithms capable of using airborne or satellite imagery to accurately map bathymetry, water quality, and substrate composition in optically shallow waters. Although a variety of inversion algorithms are available, there has been limited assessment of performance and no work has been published comparing their accuracy and efficiency. This paper compares the absolute and relative accuracies and computational efficiencies of one empirical and five radiative-transfer-based published approaches applied to coastal sites at Lee Stocking Island in the Bahamas and Moreton Bay in eastern Australia. These sites have published airborne hyperspectral data and field data. The assessment showed that (1) radiative-transfer-based methods were more accurate than the empirical approach for bathymetric retrieval, and the accuracies and processing times were inversely related to the complexity of the models used; (2) all inversion methods provided moderately accurate retrievals of bathymetry, water column inherent optical properties, and benthic reflectance in waters less than 13 m deep with homogeneous to heterogeneous benthic/substrate covers; (3) slightly higher accuracy retrievals were obtained from locally parameterized methods; and (4) no method compared here can be considered optimal for all situations. The results provide a guide to the conditions where each approach may be used (available image and field data and processing capability). A re-analysis of these same or additional sites with satellite hyperspectral data with lower spatial and radiometric resolution, but higher temporal resolution would be instructive to establish guidelines for repeatable regional to global scale shallow water mapping approaches

Evaluating the Theoretical Background of STOFFENMANAGER® and the Advanced REACH Tool

STOFFENMANAGER® and the Advanced REACH Tool (ART) are recommended tools by the European Chemical Agency for regulatory chemical safety assessment. The models are widely used and accepted within the scientific community. STOFFENMANAGER® alone has more than 37 000 users globally and more than 310 000 risk assessment have been carried out by 2020. Regardless of their widespread use, this is the first study evaluating the theoretical backgrounds of each model. STOFFENMANAGER® and ART are based on a modified multiplicative model where an exposure base level (mg m−3) is replaced with a dimensionless intrinsic emission score and the exposure modifying factors are replaced with multipliers that are mainly based on subjective categories that are selected by using exposure taxonomy. The intrinsic emission is a unit of concentration to the substance emission potential that represents the concentration generated in a standardized task without local ventilation. Further information or scientific justification for this selection is not provided. The multipliers have mainly discrete values given in natural logarithm steps (…, 0.3, 1, 3, …) that are allocated by expert judgements. The multipliers scientific reasoning or link to physical quantities is not reported. The models calculate a subjective exposure score, which is then translated to an exposure level (mg m−3) by using a calibration factor. The calibration factor is assigned by comparing the measured personal exposure levels with the exposure score that is calculated for the respective exposure scenarios. A mixed effect regression model was used to calculate correlation factors for four exposure group [e.g. dusts, vapors, mists (low-volatiles), and solid object/abrasion] by using ~1000 measurements for STOFFENMANAGER® and 3000 measurements for ART. The measurement data for calibration are collected from different exposure groups. For example, for dusts the calibration data were pooled from exposure measurements sampled from pharmacies, bakeries, construction industry, and so on, which violates the empirical model basic principles. The calibration databases are not publicly available and thus their quality or subjective selections cannot be evaluated. STOFFENMANAGER® and ART can be classified as subjective categorization tools providing qualitative values as their outputs. By definition, STOFFENMANAGER® and ART cannot be classified as mechanistic models or empirical models. This modeling algorithm does not reflect the physical concept originally presented for the STOFFENMANAGER® and ART. A literature review showed that the models have been validated only at the ‘operational analysis’ level that describes the model usability. This review revealed that the accuracy of STOFFENMANAGER® is in the range of 100 000 and for ART 100. Calibration and validation studies have shown that typical log-transformed predicted exposure concentration and measured exposure levels often exhibit weak Pearson’s correlations (r is <0.6) for both STOFFENMANAGER® and ART. Based on these limitations and performance departure from regulatory criteria for risk assessment models, it is recommended that STOFFENMANAGER® and ART regulatory acceptance for chemical safety decision making should be explicitly qualified as to their current deficiencies.Peer reviewe