Reduced energy consumption is one of the main requirements for application of water electrolyzers with alkaline electrolyte for small-scale power industry. The energy consumption can be reduced, ...among other things, by changing the assembling of electrodes and diaphragm material. The phase inversion method, which is used for fabricating the polymer-based porous diaphragms for alkaline water electrolyzers, enabled us to develop an electrode–diaphragm assembly in which the electrodes with the catalytic layers and the diaphragm material comprise a single unit. The electrolysis cells with the electrode–diaphragm assemblies of various compositions and the cells of conventional “zero-gap” design are studied.
Thermal dark matter models with particle χ masses below the electroweak scale can provide an explanation for the observed relic dark matter density. This would imply the existence of a new feeble ...interaction between the dark and ordinary matter. We report on a new search for the sub-GeV χ production through the interaction mediated by a new vector boson, called the dark photon A^{'}, in collisions of 100 GeV electrons with the active target of the NA64 experiment at the CERN SPS. With 9.37×10^{11} electrons on target collected during 2016-2022 runs NA64 probes for the first time the well-motivated region of parameter space of benchmark thermal scalar and fermionic dark matter models. No evidence for dark matter production has been found. This allows us to set the most sensitive limits on the A^{'} couplings to photons for masses m_{A^{'}}≲0.35 GeV, and to exclude scalar and Majorana dark matter with the χ-A^{'} coupling α_{D}≤0.1 for masses 0.001≲m_{χ}≲0.1 GeV and 3m_{χ}≤m_{A^{'}}.
The article is devoted to the development of a new-generation elemental base for aqueous alkaline electrolyzers with anion-exchange membranes. Two new membranes and various types of electrodes are ...proposed, which significantly increase the purity of the generated electrolysis gases and the operating outlet pressure directly at the outlet of the electrolysis module, while maintaining low specific energy consumption. The electrolysis module consists entirely of membrane–electrode assemblies. Their composition includes components tested in the industrial alkaline electrolysis; they stand out from the known analogues in their chemical resistance. Various types of catalysts that can be used as part of membrane–electrode assemblies are considered. The results of express tests of the 12Kh18N10T-stainless-steel electrodes revealed the oxidation process of chromium, a part of the alloy, which is shown to lower its corrosion resistance. When testing electrodes based on a steel mesh coated with a protective nickel layer, an extensive anode pitting corrosion was detected during its operating at high current densities. As an alternative, nickel-mesh electrodes are proposed. They showed excellent corrosion resistance and high adhesion of the electrodeposited catalysts. Catalytic coatings consisting of nickel or nickel–cobalt powder with chemically deposited phosphorus are investigated as catalysts.
Тhe efficiency and the performance of membrane electrode assemblies (MEAs) of the anion exchange membrane (AEM) water electrolyzer is determined to a significant degree by the properties of the ...materials used as porous transport layers (PTLs). Due to the high surface roughness, porosity, and pore size, the direct use of Ni foam as an electrode material is difficult, and its preliminary compression is required, which irreversibly affects the electrode structure. In the presented work, the effect of Ni foam compression on the structure of an electrode based on it, as well as on the AEM water electrolyzer MEA is considered, including the distribution of voltage losses. The effect of the compression degree on the Ni-foam electrode structure and the performance of the AEM water electrolyzer MEA is considered. The optimal electrode compression provides a significant decrease in the loss of microporous layer particles and catalyst layer nanoparticles in deep surface voids of the PTL, and the development of an interface between the nanostructured catalyst layer and the electrode.
Abstract
In this work, we develop a systemic approach to the study of a new model of COVID-19 pandemic. The main goal is to minimize the pandemic damage to economy and society by defining the model ...optimal management parameters. Our approach consists of two main parts: 1) the adaptive-compartmental model of the epidemic (ACM-SEIR) – a generalization of the classical SEIR model and 2) the module to tune ACM-SEIR parameters using artificial intelligence methods (collection, storage and processing of big data from heterogeneous sources) that allow the most accurate adjustment of ACM-SEIR parameters turning it into an intelligent system for decision support called herein iACM-SEIR. We show that among iACM-SEIR parameters, the most important are individual economic, demographic and psychologic characteristics of society and the governmental actions.
High-temperature electrochemical synthesis (HTES) in molten salts is highly promising among the up-to-date methods for the production of carbide powders. Ultrafine composite powders of tungsten ...carbides (WC|C, WC|C|Pt, W
2
C|WC, and W
2
C|W) were synthesized using the HTES method in electrolytic baths with different chemical compositions under various synthesis conditions (cathode current density, CO
2
pressure in the electrolyzer, temperature, and cathode material). Composite powders (up to 3 wt.% free carbon) with a WC particle size of 20–30 nm were prepared using Na, K|Cl (1 : 1)–Na
2
W
2
O
7
(6.4 wt.%)–CO
2
(1.25 MPa) and Na, K|Cl (1 : 1)–Na
2
WO
4
(12.0 wt.%)–NaPO
3
(0.7 wt. %)–CO
2
(1.25 MPa) electrolytic baths at a temperature of 750°C. When the CO
2
pressure was reduced to 0.75 MPa, composite W
2
C|WC powders formed at the cathode. The ratio of carbide phases in the composites depended on the initial concentration of tungsten salts in the electrolyte and on the CO
2
gas pressure in the electrolyzer. The addition of Li
2
CO
3
(4.5 wt.%) to the electrolytic salt mixture decreased the tungsten carbide particles to 10 nm, changed their morphology, and increased the free carbon content in the composite up to 5 wt.%. The specific surface area of the powder increased by a factor of 4 to 7 (from 20–35 to 140 m
2
/g). The resulting products were modified with fine platinum particles through the use of platinum cathodes. The HTES method demonstrated its potential for producing tungsten carbide powders with the properties allowing their use as electrocatalysts in the hydrogen evolution reaction. For the WC|C composite powders synthesized in the Na, K|Cl–Na
2
W
2
O
7
–Li
2
CO
3
–CO
2
system, the hydrogen evolution potential was –0.02 V relative to the normal hydrogen electrode, the overpotential η at a current density of 10 mA/cm
2
was –110 mV, the exchange current was 7.0 ⋅ 10
–4
A/cm
2
, and the Tafel slope was –85 mV/dec.
Hunting down the X17 boson at the CERN SPS Depero, E.; Andreev, Yu. M.; Banerjee, D. ...
The European physical journal. C, Particles and fields,
12/2020, Letnik:
80, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Recently, the ATOMKI experiment has reported new evidence for the excess of
e
+
e
-
events with a mass
∼
17 MeV in the nuclear transitions of
4
He, that they previously observed in measurements with
...8
Be. These observations could be explained by the existence of a new vector
X
17
boson. So far, the search for the decay
X
17
→
e
+
e
-
with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining
X
17
parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the
X
17
decay with the proposed method. To reach this goal an optimization of the
X
17
production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results
1
, validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible.
The article characterizes the importance of occupational risk assessment in order to reduce injuries. The study show that the level of professional stress of employees influences the magnitude of ...occupational risk. A study was conducted to assess the professional stress of workers according to the method of K. Weisman The influence of the factors of a healthy lifestyle and the "work-family conflict" on the level of professional stress in the engineering industry has been confirmed. Authors propose and implement actions to improve the stress tolerance of workers and reduce the level of professional stress. The study conducted confirms the effectiveness of the implemented actions to reduce the level of occupational risks in the organization.
We present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c. The analysis, performed using data ...collected by the NA64-e experiment in 2022, is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64 detector. We determined the contamination by comparing the results obtained using the nominal electron/positron beamline configuration with those from a dedicated setup, in which only hadrons impinged on the detector. We also obtained an estimate of the relative protons, anti-protons and pions yield by exploiting the different absorption probabilities of these particles in matter. We cross-checked our results with a dedicated Monte Carlo simulation for the hadron production at the primary T2 target, finding a good agreement with the experimental measurements.
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