Synthesis, Characterization, and Properties of Graphene-Based Hybrids with Cobalt Oxides for Electrochemical Energy Storage and Electrocatalytic Glucose Sensing

A library of graphene-based hybrid materials was synthesized as novel hybrid electrochemical electrodes for electrochemical energy conversion and storage devices and electrocatalytical sensing namely enzymeless glucose sensing. The materials used were supercapacitive graphene-family nanomaterials (multilayer graphene-MLG; graphene oxide-GO, chemically reduced GO-rGO and electrochemical reduced GOErGO) and pseudocapacitive nanostructured transition metal oxides including cobalt oxide polymorphs (CoO and Co3O4) and cobalt nanoparticles (CoNP). These were combined through physisorption, electrodeposition, and hydrothermal syntheses approaches. This project was carried out to enhance electrochemical performance and to develop electrocatalytic platforms by tailoring structural properties and desired interfaces. Particularly, electrodeposition and hydrothermal synthesis facilitate chemically-bridged (covalently- and electrostatically- anchored) interfaces and molecular anchoring of the constituents with tunable properties, allowing faster ion transport and increased accessible surface area for ion adsorption. The surface morphology, structure, crystallinity, and lattice vibrations of the hybrid materials were assessed using electron microscopy (scanning and transmission) combined with energy dispersive spectroscopy and selected-area electron diffraction, X-ray diffraction, and micro-Raman Spectroscopy. The electrochemical properties of these electrodes were evaluated in terms of supercapacitor cathodes and enzymeless glucose sensing platforms in various operating modes. They include cyclic voltammetry (CV), ac electrochemical impedance spectroscopy, charging-discharging, and scanning electrochemical microscopy (SECM). These hybrid samples showed heterogeneous transport behavior determining diffusion coefficient (4⨯10-8 – 6⨯10-6 m2/s) following an increasing order of CoO/MLG \u3c Co3O4/MLG \u3c Co3O4/rGOHT \u3c CoO/ErGO \u3c CoNP/MLG and delivering the maximum specific capacitance 450 F/g for CoO/ErGO and Co3O4/ rGOHT. In agreement with CV properties, these electrodes showed the highest values of low-frequency capacitance and lowest charge-discharge response (0.38 s – 4 s), which were determined from impedance spectroscopy. Additionally, through circuit simulation of experimental impedance data, RC circuit elements were derived. SECM served to investigate electrode/electrolyte interfaces occurring at the solid/liquid interface operating in feedback probe approach and imaging modes while monitoring and mapping the redox probe (re)activity behavior. As expected, the hybrids showed an improved electroactivity as compared to the cobalt oxides by themselves, highlighting the importance of the graphene support. These improvements are facilitated through molecular/chemical bridges obtained by electrodeposition as compared with the physical deposition

Geometric Phase and Modulo Relations for Probability Amplitudes as Functions on Complex Parameter Spaces

We investigate general differential relations connecting the respective behavior s of the phase and modulo of probability amplitudes of the form \amp{\psi_f}{\psi}, where $\ket{\psi_f}$ is a fixed state in Hilbert space and $\ket{\psi}$ is a section of a holomorphic line bundle over some complex parameter space. Amplitude functions on such bundles, while not strictly holomorphic, nevertheless satisfy generalized Cauchy-Riemann conditions involving the U(1) Berry-Simon connection on the parameter space. These conditions entail invertible relations between the gradients of the phase and modulo, therefore allowing for the reconstruction of the phase from the modulo (or vice-versa) and other conditions on the behavior of either polar component of the amplitude. As a special case, we consider amplitude functions valued on the space of pure states, the ray space ${\cal R} = {\mathbb C}P^n$, where transition probabilities have a geometric interpretation in terms of geodesic distances as measured with the Fubini-Study metric. In conjunction with the generalized Cauchy-Riemann conditions, this geodesic interpretation leads to additional relations, in particular a novel connection between the modulus of the amplitude and the phase gradient, somewhat reminiscent of the WKB formula. Finally, a connection with geometric phases is established.Comment: 11 pages, 1 figure, revtex

Customer perceptions about family firms and their effects on customer behaviors

The current is an exploratory project exploring the associations and impressions evoked by the term “family-owned business” (FOBs) and how these impressions affect intentions to buy from a family firm. Four studies were conducted to assess the perceptions about family firms. Based on signaling theory and the theory of reason action, it was predicted that the family nature of firms would act as a signal that consumers will use to determine perceptions, attitudes towards family firms, and intentions to buy from family firms. Results indicate that, in general, participants had positive perceptions about organizational values and neutral perceptions about products and services offered by family firms. As suggested by the Theory of Reasoned Action, these perceptions affected attitudes and intentions towards FOBs. Implications for theory and practice are discussed

An online survey of UK women's attitudes to having children, the age they want children and the effect of the COVID-19 pandemic

STUDY QUESTION: What are women's views on having children, including the age they want to have them and other influences such as the coronavirus disease 2019 (COVID-19) pandemic? SUMMARY ANSWER: Women's views on having children, at their preferred age of 30 years, included their maternal urge and concerns about their biological clock and stability, while 19% said COVID-19 had affected their views. WHAT IS KNOWN ALREADY: Women globally are delaying the birth of their first child, with the average age of first birth approaching 32 years in some countries. The average age women have their first child in the UK is 30.7 years and over 50% of women aged 30 years are childless. The fertility rate stands at 1.3 in several European Union countries. Some people are not having their desired family size or are childless by circumstance. It is essential to understand people's attitudes to having children in different countries to identify trends so we can develop educational resources in an age-appropriate manner. STUDY DESIGN, SIZE, DURATION: We conducted an anonymous, online survey of multiple choice and open-ended questions. The survey was live for 32 days from 15 May 2020 to 16 June 2020 and was promoted using social media. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 887 women from 44 countries participated in the survey. After filtering out women who did not consent, gave blank or incomplete responses, and those not in the UK, 411 responses remained. From the data, three areas of questioning were analysed: their views on having children, the ideal age they want to have children and the effects of the COVID-19 pandemic. Qualitative data were analysed by thematic analysis. MAIN RESULTS AND THE ROLE OF CHANCE: The average age (±SD) of the women who completed the survey was 32.2 years (±5.9), and they were mainly heterosexual (90.8%) and 84.8% had a university education. One-third of women were married/in a civil partnership (37.7%) and 36.0% were cohabitating. In relation to their views on having children, the main themes identified were: the maternal urge, the ticking of the biological clock, why did no one teach us this?, the need for stability and balance in their life, pressure to start a family and considering other ways to have a family. When asked 'In an ideal world, at what age approximately would you like to have had or have children?' a normal distribution was observed with a mean age of 29.9 (±3.3) years. When asked 'What factors have led you to decide on that particular age?' the most frequent choice was 'I am developing my career'. Three themes emerged from the qualitative question on why they chose that age: the need for stability and balance in their life, the importance of finding the right time and life experiences. The majority of women felt that the COVID-19 pandemic had not affected their decision to have children (72.3%), but 19.1% said it had. The qualitative comments showed they had concerns about instability in their life, such as finances and careers, and delays in fertility treatment. LIMITATIONS, REASONS FOR CAUTION: The survey was promoted on social media only and the women who answered the survey were highly educated. WIDER IMPLICATIONS OF THE FINDINGS: The women surveyed ideally want children at age 30 years but there are obstacles in their way, such as the need to develop their career. Global tailored fertility education is essential to ensure people make informed reproductive choices. In addition, it is essential for supportive working environments and affordable childcare to be in place in every country. STUDY FUNDING/COMPETING INTEREST(S): J.C.H. is founder of www.globalwomenconnected.com and Reproductive Health at Work, and author of the book Your Fertile Years. This project was funded by the Institute for Women's Health, UCL. TRIAL REGISTRATION NUMBER: N/A

Aplicación de la teoría de robots manipuladores a la biomecánica del brazo humano1

ResumenEste artículo presenta la aplicación de un conjunto de técnicas propias de la teoría de los robots manipuladores al estudio del movimiento del brazo humano. Para ello el brazo humano se modela como un robot manipulador redundante. En particular se aplica el concepto de índices de desempeño para predecir posturas óptimas del brazo durante la realización de tareas. En el estudio se incluyen tanto posiciones estáticas, como secuencias de posiciones para la formulación de trayectorias óptimas de movimiento

Incumbent Decisions About Succession Transitions in Family Firms: A Conceptual Model

In the family business literature, succession research has focused on the family member as they enter the leadership role or on the different issues that affect the succession process. Although researchers have acknowledged that succession in family businesses is “punctuated” by decision making events, less attention has been given to understanding how incumbents make decisions about ownership and management transitions. In an effort to continue to understand the succession process it is important to understand how incumbents make decisions about the type of transitions they intend to engage in (i.e., intra-family succession, out of family succession, or no succession). Building on the theory of planned behavior and the socioemotional wealth framework (SEW), this manuscript presents a conceptual framework to understand the factors that influence succession transitions and the role that contextual factors can play in this decision-making process. We present theory driven propositions and discuss the implications for understanding and evaluation of the succession process

An AB effect without closing a loop

We discuss the consequences of the Aharonov-Bohm effect in setups involving several charged particles, wherein none of the charged particles encloses a closed loop around the magnetic flux. We show that in such setups, the AB phase is encoded either in the relative phase of a bi-partite or multi-partite entangled photons states, or alternatively, gives rise to an overall AB phase that can be measured relative to another reference system. These setups involve processes of annihilation or creation of electron/hole pairs. We discuss the relevance of such effects in "vacuum Birefringence" in QED, and comment on their connection to other known effects.Comment: 4 pages, 3 figure

Towards a better understanding of the life cycle of Trypanosoma copemani

Trypanosoma copemani has been found infecting several threatened/endangered marsupial species within Australia and is thought to be a key player in the rapid decline of the woylie (Bettongia penicillata). To better understand the biology and life cycle of this parasite, the growth requirements, and kinetics of infection of two newly described genotypes, T. copemani G1 and G2, were investigated and compared with the T. cruzi strain-10R26 in vitro. Both G1 and G2 were able to infect all four cell lines tested. The number of infected cells where at least one intracellular amastigote of T. copemani G1 and G2 was seen was below 7% and 15% respectively in most cell lines. However, in VERO cells the rate of infection for T. copemani G2 was 70%-approximately seven and two times higher than for G1 and T. cruzi respectively. Despite the higher infection rate, the number of intracellular forms of T. copemani G2 was lower compared with T. cruzi, and intracellular replicating forms were not observed. The capability of T. copemani G2 to infect cells may have important consequences for pathogenicity and suggests it might employ similar strategies to complete its life cycle in the vertebrate host to those seen in T. cruzi

Diseño un controlador robusto basado en observador para el modelo lineal de un helicóptero de un grado de libertad (VTOL)

Este artículo propone un controlador basado en observador para un modelo de helicóptero tipo VTOL de un grado de libertad. El objetivo de control es mantener la posición del VTOL en un punto de operación, a pesar de las incertidumbres ocasionadas por inexactitud en el modelo y ruido en las mediciones. El controlador y el observador son diseñados con base en algoritmos que inducen modos deslizantes en el sistema en lazo cerrado, ofreciendo características de robustez y convergencia en tiempo finito. Los resultados de simulación muestran un buen desempeño del esquema propuesto tanto en condiciones de ausencia de ruido como cuando se consideran mediciones ruidosas.Universidad Nacional de ColombiaCinvestavColcienciasBanco Mundia