New insights into the Pt(hkl)-alkaline solution interphases from the laser induced temperature jump method

The interfacial properties of platinum single crystal electrodes in contact with alkaline aqueous solutions (pH = 13) have been investigated using the laser induced temperature jump method. This technique offers insights into the net orientation of water dipoles in contact with the electrode surface by recording the coulostatic potential changes after a sudden increase of the interfacial temperature in the submicrosecond time scale. This information is intimately related with the magnitude and sign of charge separation at the interphase and the resulting electric field. In all cases, water shows a net orientation with the hydrogen towards the metal at the lowest investigated potential value, reflected in negative potential transients. The magnitude of the water orientation decreases as the applied potential increases. Eventually, the sign of the potential transient changes, reflecting a reorientation of the water dipoles. The potential where such inversion takes place follows the order Pt(110) < Pt(100) < Pt(111) in accordance with the observed behavior in acid solution and the trend of the work function. For Pt(111) the change of sign of the laser induced potential transient takes place at the onset of hydroxyl adsorption. For the three surfaces, when the pH is decreased to ca. pH = 11, a slow response is detected at potentials values above the inversion point. This could be due to a fast adsorption process or to a slow reorientation of water. After the introduction of steps on the (111) terrace, the inversion shifts to the double layer region, allowing the unambiguous identification of the inversion with a change on the net orientation of the water molecules. For stepped surfaces, a second inversion of the laser induced potential transient is observed that could be related with an effect of the local charge on steps disrupting the ordering of the water network. Comparison with analogous results in acid solution gives information about the local distribution of charges on the stepped surfaces.This work has been financially supported by the MINECO (Spain) project no. CTQ2016-76221-P

SIT4 protein phosphatase is required for the normal accumulation of SWI4, CLN1, CLN2, and HCS26 RNAs during late G1

In Saccharomyces cerevisiae, the RNA levels of the G1 cyclins CLN1, CLN2, and HCS26 increase dramatically during the late G1 phase of the cell cycle. The SIT4 gene, which encodes a serine/threonine protein phosphatase, is required for the normal accumulation of CLN1, CLN2, and HCS26 RNAs during late G1. This requirement for SIT4 in normal G1 cyclin RNA accumulation is at least partly via SWI4. Strains containing mutations in SIT4 are sensitive to the loss of either CLN2 or CLN3 function. At the nonpermissive temperature, temperature-sensitive sit4 strains are blocked for both bud emergence and DNA synthesis. Heterologous expression of CLN2 in the absence of SIT4 function results in DNA synthesis, but most of the cells are still blocked for bud emergence. Therefore, SIT4 is required for at least two late G1 or G1/S functions: the normal accumulation of G1 cyclin RNAs (which is required for DNA synthesis) and some additional function that is required for bud emergence or cell cycle progression through late G1 or G1/S

The Degree and regularity of vanishing ideals of algebraic toric sets over finite fields

Let X* be a subset of an affine space A^s, over a finite field K, which is parameterized by the edges of a clutter. Let X and Y be the images of X* under the maps x --> [x] and x --> [(x,1)] respectively, where [x] and [(x,1)] are points in the projective spaces P^{s-1} and P^s respectively. For certain clutters and for connected graphs, we were able to relate the algebraic invariants and properties of the vanishing ideals I(X) and I(Y). In a number of interesting cases, we compute its degree and regularity. For Hamiltonian bipartite graphs, we show the Eisenbud-Goto regularity conjecture. We give optimal bounds for the regularity when the graph is bipartite. It is shown that X* is an affine torus if and only if I(Y) is a complete intersection. We present some applications to coding theory and show some bounds for the minimum distance of parameterized linear codes for connected bipartite graphs

Elucidating the Structure of the Cu-Alkaline Electrochemical Interface with the Laser-Induced Temperature Jump Method

A detailed description of the Cu–electrolyte interface is vital to understand the electrocatalytic properties of Cu surfaces. Herein, we combine cyclic voltammetry and the laser-induced temperature jump technique to describe the structure of the Cu(111) and Cu(100) | electrolyte interfaces in 0.1 M NaOH in a glass-free electrochemical cell. The laser-induced potential transients recorded at different potentials provided information of the surface charge distribution, which allowed us to calculate the potential of maximum entropy (pme), which can be considered as a good estimation of the potential of zero charge (pzc) of Cu(111) and Cu(100). We found that pzcCu(111) > pzcCu(100), following the same order as their respective work function values. Interestingly, the estimated pzc appears to be located at the onset potential of the OH* voltammetric feature for Cu(111) and Cu(100), which suggests that this feature shifts with the pzc of each crystallographic orientation. This is the first study that provides the experimental evidence of charge distribution at the Cu–solution interface under alkaline conditions.M.E.-E. gratefully acknowledges the Villum Foundation for the award of a Villum Young Investigator Grant (project number 19142). J.M.F. thanks the MCINN (FEDER) (Spain) project PID2019-105653GB-100

A Framework for Simulating Home Control Networks

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Air conditioning production by a single effect absorption cooling machine directly coupled to a solar collector field. Application to Spanish climates

Due to the increasing energy consumption of air conditioning in buildings and the need to decrease the fossil CO2 emissions to the environment, the interest of using renewable energy sources shows up stronger than ever. We present a general study whose aim is to propose a method to evaluate an upper bound in the potential of solar cooling by using some simplified models. As an example it has been applied to the very diverse climates of Spain. In the paper it has been assumed a direct solar coupling between the solar collector field and a single effect absorption cooling machine, without any intermediate solar storage tank. An equation is obtained that shows the dependence of the generator/solar-collectors equilibrium temperature on basic design parameters of the system (absorption machine-solar collectors). The paper analyzes the effect of these on the total amount of cooling produced along a typical mean year and the peak cooling power. The paper also includes a discussion on how to estimate the values and what is their physical meaning of the parameters which define the behavior of real absorption machines. Finally tables are included for the 12 climates of Spain that can be used as an example of how to make a quick pre-sizing of such direct coupled system. The classification of the Spanish climates is based on general data (average monthly total horizontal solar radiation, average monthly dry temperature, etc.) and the results could be generalized for climates with the same severity. Moreover if hourly weather data is available for any place (like tmy2, bin, epw, etc. files), the procedure can be applied without further changes.Sarabia Escrivà, EJ.; Lamas Sivila, EV.; Soto Francés, VM. (2011). Air conditioning production by a single effect absorption cooling machine directly coupled to a solar collector field. Application to Spanish climates. Solar Energy. 85(9):2108-2121. doi:10.1016/j.solener.2011.05.019S2108212185

Cu(111) single crystal electrodes: Modifying interfacial properties to tailor electrocatalysis

Tailoring electrocatalyst materials to the specific requirements of a certain reaction and to optimize activity or enhance selectivity is a key tactic for the development of low-temperature fuel and electrolyzer cells for clean energy production. Here, we demonstrate the modification of Cu(111) electrodes with different sub-monolayer coverages of foreign metals (Cd) and metal hydroxides (Co(OH)2 and Ni(OH)2) for application in the hydrogen evolution reaction (HER) in alkaline media. In situ electrochemical scanning tunneling microscopy (EC-STM) reveals that these modifications have a significant influence on the morphology and structure of the Cu(111) surface with its characteristics depending on both the nature and the amount of the adsorbed metal(hydroxide). Ni(OH)2 and Co(OH)2 on Cu(111) lead to a significant enhancement of the electrocatalytic activity towards the HER in alkaline electrolyte, whereas a decrease in activity is found for Cd modified Cu(111). These trends can be rationalized by considering the strength of the interfacial electric field and its influence on the specific interactions of the electrode with the water ad-layer close to the surface, as determined by laser-induced temperature jump measurements. This comparative study therefore provides valuable information on the structure-activity relation as well as insights on the interfacial characteristics of different bimetallic Cu electrocatalysts.A.A. is a recipient of a doctorate (DOC) Fellowship of the Austrian Academy of Sciences at the Institute of Physical Chemistry. C.G. thanks the Austrian Research Promotion Agency (FFG) for funding by the project number 870523. J.K-L. acknowledges funding by the Austrian Science Fund (FWF) via grant I-4114-N37. J.M.F and V.C. acknowledge financial support from Ministerio de Ciencia e Innovación (project PID2019-105653GB-100) and Generalitat Valenciana (project PROMETEO/2020/063)

On the behavior of CTAB/CTAOH adlayers on gold single crystal surfaces

The behavior of adsorbed CTAB and CTAOH on gold single crystal electrodes has been studied in solutions with different pH values. For the different single crystal electrodes, the adsorbed adlayer formed by CTA+ cations is in contact with the surface, when the electrode charge is negative. As the surface charge becomes positive, the adlayer detaches from the surface and water molecules permeate through it, giving rise to characteristic peaks in the voltammogram. Charge and laser induced jump temperature measurements show that the composition of the adlayer contains not only the CTA+ cations but also anions, which are required to stabilize the adlayer. In alkaline solutions, the higher solubility of CTAB/CTAOH in alkaline solutions leads to the partial desorption of the adlayer when these species are not present in the solution. When CTAB or CTAOH are dissolved in the alkaline cell solution, the adlayer is strongly bonded to the surface in the whole potential window due to the negative charge of the surface.Financial support from Ministerio de Ciencia e Innovación (Project PID2019-105653GB-I00) and Generalitat Valenciana (Project PROMETEO/2020/063) is acknowledged

Underpotential deposition of Nickel on platinum single crystal electrodes

The initial stages of nickel electrodeposition on platinum single crystal electrodes have been investigated using cyclic voltammetry and CO charge displacement. While at pH = 1, nickel deposition is not visible in the voltammogram, regardless of the crystal orientation, at buffered solutions with pH > 3, nickel presence in solution produces clear voltammetric peaks around 0.35 V RHE on Pt(111) and Pt(110). Conversely, no clear voltammetric peaks are observed at any of the studied pHs on Pt(100). CO charge displacement experiments suggest that deposited nickel is in the form of a nickel hydroxide. Coulometric analysis is used to deduce the stoichiometry of the deposited adlayer. Moreover, the effect of nickel presence on CO oxidation has been investigated and the CO adlayer characterised using FTIR reflection absorption spectroscopy.The authors thankfully acknowledge financial support from the Ministerio de Economia, Industria y Competitividad (CTQ2016-76221-P and PEJ-2014-A-57942/PEJ-2014-P-00295)

Bayesian estimation of incomplete data using conditionally specified priors

In this paper, a class of conjugate prior for estimating incomplete count data based on a broad class of conjugate prior distributions is presented. The new class of prior distributions arises from a conditional perspective, making use of the conditional specification methodology and can be considered as the generalisation of the form of prior distributions that have been used previously in the estimation of in- complete count data well. Finally, some examples of simulated and real data are given