Controlling the Production of Acid Catalyzed Products of Furfural Hydrogenation by Pd/TiO2

We demonstrate a modified sol-immobilization procedure using (MeOH)x/(H2O)1-x solvent mixtures to prepare Pd/TiO2 catalysts that are able to reduce the formation of acid catalyzed products, e. g. ethers, for the hydrogenation of furfural. Transmission electron microscopy found a significant increase in polyvinyl alcohol (PVA) deposition at the metal-support interface and temperature programmed reduction found a reduced uptake of hydrogen, compared to an established Pd/TiO2 preparation. We propose that the additional PVA hinders hydrogen spillover onto the TiO2 support and limits the formation of Brønsted acid sites, required to produce ethers. Elsewhere, the new preparation route was able to successfully anchor colloidal Pd to the TiO2 surface, without the need for acidification. This work demonstrates the potential for minimizing process steps as well as optimizing catalyst selectivity – both important objectives for sustainable chemistry

An assessment of the Jenkinson and Collison synoptic classification to a continental mid-latitude location

A weather-type catalogue based on the Jenkinson and Collison method was developed for an area in south-west Russia for the period 1961--2010. Gridded sea level pressure data was obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The resulting catalogue was analysed for frequency of individual types and groups of weather types to characterise long-term atmospheric circulation in this region. Overall, the most frequent type is anticyclonic (A) (23.3 {%}) followed by cyclonic (C) (11.9 {%}); however, there are some key seasonal patterns with westerly circulation being significantly more common in winter than summer. The utility of this synoptic classification is evaluated by modelling daily rainfall amounts. A low level of error is found using a simple model based on the prevailing weather type. Finally, characteristics of the circulation classification are compared to those for the original JC British Isles catalogue and a much more equal distribution of flow types is seen in the former classification

Impact of network structure and cellular response on spike time correlations

Novel experimental techniques reveal the simultaneous activity of larger and larger numbers of neurons. As a result there is increasing interest in the structure of cooperative -- or correlated -- activity in neural populations, and in the possible impact of such correlations on the neural code. A fundamental theoretical challenge is to understand how the architecture of network connectivity along with the dynamical properties of single cells shape the magnitude and timescale of correlations. We provide a general approach to this problem by extending prior techniques based on linear response theory. We consider networks of general integrate-and-fire cells with arbitrary architecture, and provide explicit expressions for the approximate cross-correlation between constituent cells. These correlations depend strongly on the operating point (input mean and variance) of the neurons, even when connectivity is fixed. Moreover, the approximations admit an expansion in powers of the matrices that describe the network architecture. This expansion can be readily interpreted in terms of paths between different cells. We apply our results to large excitatory-inhibitory networks, and demonstrate first how precise balance --- or lack thereof --- between the strengths and timescales of excitatory and inhibitory synapses is reflected in the overall correlation structure of the network. We then derive explicit expressions for the average correlation structure in randomly connected networks. These expressions help to identify the important factors that shape coordinated neural activity in such networks

Fear of COVID-19 and perceived COVID-19 infectability supplement theory of planned behavior to explain Iranians' intention to get COVID-19 vaccinated

One of the most efficient methods to control the high infection rate of the coronavirus disease 2019 (COVID-19) is to have a high coverage of COVID-19 vaccination worldwide. Therefore, it is important to understand individuals’ intention to get COVID-19 vaccinated. The present study applied the Theory of Planned Behavior (TPB) to explain the intention to get COVID-19 vaccinated among a representative sample in Qazvin, Iran. The TPB uses psychological constructs of attitude, subjective norm, and perceived behavioral control to explain an individual’s intention to perform a behavior. Fear and perceived infectability were additionally incorporated into the TPB to explain the intention to get COVID-19 vaccinated. Utilizing multistage stratified cluster sampling, 10,843 participants (4092 males; 37.7%) with a mean age of 35.54 years (SD = 12.00) completed a survey. The survey assessed TPB constructs (including attitude, subjective norm, perceived behavioral control, and intention related to COVID-19 vaccination) together with fear of COVID-19 and perceived COVID-19 infectability. Structural equation modeling (SEM) was performed to examine whether fear of COVID-19, perceived infectability, and the TPB constructs explained individuals’ intention to get COVID-19 vaccinated. The SEM demonstrated satisfactory fit (comparative fit index = 0.970; Tucker-Lewis index = 0.962; root mean square error of approximation = 0.040; standardized root mean square residual = 0.050). Moreover, perceived behavioral control, subjective norm, attitude, and perceived COVID-19 infectability significantly explained individuals’ intention to get COVID-19 vaccinated. Perceived COVID-19 infectability and TPB constructs were all significant mediators in the relationship between fear of COVID-19 and intention to get COVID-19 vaccinated. Incorporating fear of COVID-19 and perceived COVID-19 infectability effectively into the TPB explained Iranians’ intention to get COVID-19 vaccinated. Therefore, Iranians who have a strong belief in Muslim religion may improve their intention to get COVID-19 vaccinated via these constructs

Representation of Dynamical Stimuli in Populations of Threshold Neurons

Many sensory or cognitive events are associated with dynamic current modulations in cortical neurons. This raises an urgent demand for tractable model approaches addressing the merits and limits of potential encoding strategies. Yet, current theoretical approaches addressing the response to mean- and variance-encoded stimuli rarely provide complete response functions for both modes of encoding in the presence of correlated noise. Here, we investigate the neuronal population response to dynamical modifications of the mean or variance of the synaptic bombardment using an alternative threshold model framework. In the variance and mean channel, we provide explicit expressions for the linear and non-linear frequency response functions in the presence of correlated noise and use them to derive population rate response to step-like stimuli. For mean-encoded signals, we find that the complete response function depends only on the temporal width of the input correlation function, but not on other functional specifics. Furthermore, we show that both mean- and variance-encoded signals can relay high-frequency inputs, and in both schemes step-like changes can be detected instantaneously. Finally, we obtain the pairwise spike correlation function and the spike triggered average from the linear mean-evoked response function. These results provide a maximally tractable limiting case that complements and extends previous results obtained in the integrate and fire framework

Mode locking in a periodically forced resonate-and-fire neuron model

The resonate-and-fire (RF) model is a spiking neuron model which from a dynamical systems perspective is a piecewise smooth system (impact oscillator). We analyze the response of the RF neuron oscillator to periodic stimuli by expressing the firing events in terms of an implicit one-dimensional time map. Based on such a firing map, we describe mode-locked solutions and their stability, leading to the so-called Arnol'd tongues. The boundaries of these tongues correspond to either local bifurcations of the firing time map or grazing bifurcations of the discontinuity of the flow. Despite the fact that the periodically driven RF system shows periodic firing, its behavior may become chaotic when the forcing frequency is near the resonant frequency. We compare these results to numerical simulations of the model undergoing sinusoidal forcing. Furthermore, upon varying a system parameter, the RF system can be reduced to the integrate-and-fire system and in this case we show the consistency of the results on mode-locked solutions

Nonlinear vibrations of plates in axial pulsating flow

A theoretical approach is presented to study nonlinear vibrations of thin infinitely long and wide rectangular plates subjected to pulsatile axial inviscid flow. The flow is set in motion by a pulsating pressure gradient. The case of plates in axial uniform flow under the action of constant transmural pressure is also addressed for different flow velocities. The plate is assumed to be periodically simply supported in both in-plane directions with immovable edges and the flow channel is bounded by a rigid wall. In this way the system under study is a finite rectangular plate with conditions on the fluid and the plate boundaries coming from the periodicity of the infinite system. The equations of motion are obtained based on the von Kárman nonlinear plate theory retaining in-plane inertia via Lagrangian approach. The fluid model is based on the potential flow theory. The resulting Lagrange equations of motion of the coupled system contain quadratic and cubic nonlinear terms and are studied by using a code based on the pseudo-arc-length continuation and collocation scheme. The effect of different system parameters such as flow velocity, pulsation amplitude, pulsation frequency and channel pressurization on the stability of the plate and its geometrically nonlinear response to pulsating flow are fully discussed. It has been found that the presence of positive transmural uniform pressure and small pulsation frequency would destroy the pitchfork bifurcation (divergence) that flat plates exhibit when subjected to uniform flow. Moreover, in case of zero uniform transmural pressure numerical results show a hardening type behavior for the entire flow velocity range when the pulsation frequency is spanned in the neighborhood of the plate's fundamental frequency. On the contrary, a softening type behavior is presented when a uniform transmural pressure is introduced

Non-linear vibrations and stability of a periodically supported rectangular plate in axial flow

In the present study, the geometrically non-linear vibrations of thin infinitely long rectangular plates subjected to axial flow and concentrated harmonic excitation are investigated for different flow velocities. The plate is assumed to be periodically simply supported with immovable edges and the flow channel is bounded by a rigid wall. The equations of motion are obtained based on the von Karman non-linear plate theory retaining in-plane inertia and geometric imperfections by employing Lagrangian approach. The fluid is modeled by potential flow and the flow perturbation potential is derived by applying the Galerkin technique. A code based on the pseudo-arc-length continuation and collocation scheme is used for bifurcation analysis. Results are shown through bifurcation diagrams of the static solutions, frequency-response curves, time histories, and phase-plane diagrams. The effect of system parameters, such as flow velocity and geometric imperfections, on the stability of the plate and its geometrically non-linear vibration response to harmonic excitation are fully discussed and the convergence of the solutions is verified