Activity Of Different Materials Research Articles

Inactivation of influenza virus as representative of enveloped RNA viruses on photocatalytically active nanoparticle and nanotubular TiO2 surfaces

The recent pandemic showed us that there is a strong demand for standardized methods to evaluate the antiviral activity of different materials using enveloped RNA viruses (e.g. SARS-CoV-2, influenza virus). Virucidal activity can be achieved as a result of photoexcitation of a TiO2 photocatalyst under UV illumination. All standardized methods evaluating the virucidal activity of photocatalytic surfaces use bacteriophage Q-beta, a representative of small non-enveloped viruses. This work was thus devoted to the evaluation of the virucidal efficiency of photocatalytically active nanostructured TiO2 surfaces (nanotubular and nanoparticle) to inactivate the influenza virus with particular interest paid to the methodology of virucidal testing and the influence of the surface nanostructure (porosity). Two different TiO2 nanostructures were used in this study, namely nanoparticle and nanotubular structures. A significant decrease in the amount of viral RNA and titre was obtained after rinsing, because the virus was retained on the surface of the nanostructured TiO2 during exposure in the dark. The decrease can be understood as an additional effect of the surface porosity on the TiO2 virucidal activity after UV illumination. However, this fact was taken into account in the calculation of virucidal activity due to UV light. Both nanostructured TiO2 coatings have comparable porosity and thickness, but the photocatalytic activity (to oxidatively degrade aqueous pollutants) is higher for the nanoparticle than for the nanotubular surface. On the other hand, the virucidal activity is much higher for the nanotubular surface. This can be explained by the uniform and open structure of nanotubes resulting in a lower amount of virus being retained on the surface under dark conditions and the high surface area of the nanotubes.

Neutronic response of the neutral beam after EAST NBI upgraded

In order to improve the heating effect of neutral beam injector, the neutral beam injector (NBI) of the Experimental Advanced Superconducting Tokamak (EAST) is planned to be upgraded. After the EAST NBI is upgraded, the neutron emission intensity will increase. Neutron leaking from the neutral beam port penetrate the beamline, resulting in the material radiation damage. The neutronic response has been investigated by using the Monte Carlo particle transport code MCNP with the two dimensional RZ model of the EAST NBI. The results demonstrate that a 40% increase of the neutron emission rate has been attained with the upgraded EAST NBI. However, the simulations for the activation of different materials, displacement damage and nuclear heating of the neutral beam still satisfy the requirement of material safety performance. The calculations of nuclear response show that the materials can meet the requirements of the NBI steady state operation after the EAST NBI updated.

On the Sensitivity to Density-Functional Approximations for CO Binding Energies of Single-Atom Catalysts in Nitrogen-Doped Graphene.

Density functional theory (DFT) methods are the working horse in screening new catalytic materials. They are widely used to predict trends in binding energies, which are then used to compare the activity of different materials. The binding strength of CO is an important descriptor to the CO2 reduction catalytic activity of the single transition metal atoms embedded on nitrogen-doped graphene (TM/NG). In this work, however, we show that CO binding strengths in different TM/NG has very different sensitivity to DFT methods. Specifically, Fe/NG CO binding energy changes dramatically with the percentage of exact exchange in the functional; Co/NG does less so, while Ni/NG nearly has no change. Such varying behaviors is a direct result of different local spin configurations, similar to the performance of DFT methods for metal porphyrin complexes. Therefore, caution should be exercised when using DFT binding energies for quantitative predictions in TM/NG single atom catalysis.

Synthesis of Iodine‐Functionalized Graphene Electrocatalyst Using Deep Eutectic Solvents for Oxygen Reduction Reaction and Supercapacitors

Iodine‐functionalized reduced graphene oxide (I@RGO) as an active oxygen reduction reaction (ORR) electrocatalyst and energy‐storage material for supercapacitors is synthesized. Herein, a novel deep eutectic solvent (DES) of choline chloride and potassium triiodide is prepared. It is applied to reduce GO and for the consequential functionalization of iodine. The metal‐free iodine‐functionalized graphene is prepared by a facile method, which has a decent electrocatalytic activity for ORR. However, the triiodide structure in I@RGO demonstrates an essential role, considerably indicating electron transfer numbers of 3.87 at a potential of −0.25 V that suggests that the reaction follows a more predominant 4e−(equivalent) pathway. The material also exhibits 242 F g−1specific capacitance and 27.2 Wh kg−1energy density at a current density of 1 A g−1. The electrochemical activity of different materials is analyzed and equally compared with a commercial Pt/C electrode. Based on these noteworthy properties, I@RGO is an excellent contender as a metal‐free ORR catalyst and energy‐storage material for practical applications.

Comprehensive Assessment of the Electrocatalytic Activity of Vanadium, Niobium Nitrides and Molybdenum-Based Materials Towards Dinitrogen Reduction to Ammonia

Electrochemical nitrogen reduction reaction (NRR) that can be powered by renewable energy is currently broadly investigated as a sustainable alternative method for the industrial ammonia synthesis to replace, at least partially, the Haber-Bosch technology. Inspired by recent theoretical reports advocating several types of materials as active NRR catalysts, our experimental work aimed to assess the validity of some of these predictions.Vanadium and niobium nitrides were suggested by the previous computational work to be catalytically active towards the electrochemical reduction of dinitrogen to ammonia occurring via the Mars-van Krevenlen (MvK) mechanism [1]. The present experimental study thoroughly investigates the electrocatalytic activity of cubic vanadium(III) nitride, niobium(III) nitride and tetragonal Nb4N5 for the nitrogen reduction reaction in aqueous electrolyte solutions of different pH under ambient conditions [2]. VN and Nb4N5 (supported on carbon cloth) were synthesised by annealing of hydrothermally produced hydroxide precursors in NH3 atmosphere at 600-1100 °C; NbN was obtained by solid state reaction between niobium(V) chloride and urea at 1000 °C. Comprehensive testing of the materials under a wide range of aqueous conditions unambiguously demonstrates their inability to catalyse the electrosynthesis of ammonia from dinitrogen, as well as the propensity of VN synthesised at 600 °C and Nb4N5 to release lattice nitride in a non-catalytic process, which produces ammonia under reductive conditions. Thus, polycrystalline nitrides of vanadium and niobium are concluded to be catalytically inactive towards the ammonia electrosynthesis from N2 dissolved in water. When tested in non-aqueous aprotic electrolyte, Nb4N5 sustained slow ammonia electrosynthesis (4 pmol s-1 cm-2) at low faradaic efficiency (20 %). The present work additionally emphasises the compulsory requirement for the implementation of reliable testing and analysis procedures for the assessment of the catalytic properties of materials for the nitrogen reduction reaction.Another type of materials suggested by DFT to be catalytically active for the NRR at low overpotentials is molybdenum disulphide promoted with Mo metal particles (Mo/MoS2), which was suggested to provide energetically favourable binding with N2 molecule [3]. However, MoS2 is a well-known hydrogen evolution catalyst rendering any reasonable selectivity for the N2 reduction with Mo/MoS2 in aqueous medium essentially impossible, as confirmed in our experiments. Therefore, we applied two aprotic ionic liquids providing high N2 solubility [4], viz. [C4mpyr][eFAP] and [P66614][eFAP], as electrolyte media for testing the electrocatalytic properties of molybdenum-based materials. Molybdenum metal and Mo/MoS2 catalysts were synthesised by reducing 2H-MoS2 with H2 at 950 and 850 °C, respectively. In [C4mpyr][eFAP], metal catalyst did not demonstrate significant rates of the NRR, but Mo/MoS2 enabled the electrosynthesis of ammonia at the yield rate of 17 pmol cm-2 s-1 and faradaic efficiency of ca 50% at an applied potential of -0.97 V vs. NHE, when using a mixture of 90% dry N2 and 10% H2O-saturated N2 as a feed gas. However, there no ammonia was detected when Mo/MoS2 was tested in [P66614][eFAP] under the same as well as other potential and humidity conditions. Juxtaposition of cyclic voltammograms of Mo/MoS2 recorded in two ionic liquids reveals very different electrochemical behaviour of the material in [C4mpyr][eFAP] and [P66614][eFAP], which is likely to explain the lack of activity in the latter medium. Further tests in tetrahydrofuran as a solvent and using a conventional lithium triflate electrolyte have further supported the hypothesis on the catalytic activity of Mo/MoS2 for the NRR, although the ammonia yield rate (3 pmol s-1 cm-2) and faradaic efficiency (ca 3%) were very low. However, further control experiments are needed before the final conclusion on the genuine NRR catalytic activity of this material can be achieved.Overall, the present study demonstrates that theoretical predictions on the catalytic activity of different materials for the NRR should be considered with caution, and that robust NRR testing and ammonia analysis protocols must be implemented to unambiguously prove genuine ammonia electrosynthesis from N2 [5].

Short analysis of cosmogenic production of radioactive isotopes in argon as target for the next neutrino experiments

The reduction of the radioactive background, the knowledge of its sources and mechanisms of its production, as well as the characteristics of its signals represent important steps for the next generation neutrino experiments, because thus the sensitivity of huge detectors is increased, and also the capability to discriminate between various particles interacting with the detector. Liquid - gaseous argon as LAr TPC technology represents a major option as target and an excellent tracking - calorimeter detector. In this class of detectors, both the scintillation light emitted and the charges produced by ionization are used to detect and identify the characteristics of the primary and secondary particles. Cosmogenic sources of background or activation of different materials become more important in this context. The radioactivity induced by cosmogenic reactions in Ar is discussed by considering muon capture and reactions induced by neutrons as sources of background. The ratio between the vertical and horizontal components of the very low energy terrestrial muons at ground level is measured in a particular location and the total flux of the low energy component of muon spectra is estimated using the EXPACS code, developed in the frame of the PARMA model. For neutron interactions, only the simulated cross sections for possible production of radioactive isotopes of argon are considered using the TALYS and EMPIRE software codes, highlighting the similarities and differences between the results of these nuclear codes and the level of concordance with the few existing experimental data. A short discussion about the scintillation processes in the argon bulk and the possible effects due of the presence of radioactive isotopes is presented.

Angiogenesis and the prevention of alveolar osteitis: a review study.

Angiogenesis is one of the essential processes that occur during wound healing. It is responsible for providing immunity as well as the regenerative cells, nutrition, and oxygen needed for the healing of the alveolar socket following tooth extraction. The inappropriate removal of formed blood clots causes the undesirable phenomenon of alveolar osteitis (AO) or dry socket. In this review, we aimed to investigate whether enhanced angiogenesis contributes to a more effective prevention of AO. The potential pro- or anti-angiogenic activity of different materials used for the treatment of AO were evaluated. An electronic search was performed in the PubMed, MEDLINE, and EMBASE databases via OVID from January 2000 to September 2016 using the keywords mentioned in the PubMed and MeSH (Medical Subject Headings) terms regarding the role of angiogenesis in the prevention of AO. Our initial search identified 408 articles using the keywords indicated above, with 38 of them meeting the inclusion criteria set for this review. Due to the undeniable role of angiogenesis in the socket healing process, it is beneficial if strategies for preventing AO are directed toward more proangiogenic materials and modalities.

Application of the Monte Carlo method to estimate doses due to neutron activation of different materials in a nuclear reactor

All materials exposed to some neutron flux can be activated independently of the kind of the neutron source. In this study, a nuclear reactor has been considered as neutron source. In particular, the activation of control rods in a BWR is studied to obtain the doses produced around the storage pool for irradiated fuel of the plant when control rods are withdrawn from the reactor and installed into this pool. It is very important to calculate these doses because they can affect to plant workers in the area. The MCNP code based on the Monte Carlo method has been applied to simulate activation reactions produced in the control rods inserted into the reactor. Obtained activities are introduced as input into another MC model to estimate doses produced by them. The comparison of simulation results with experimental measurements allows the validation of developed models. The developed MC models have been also applied to simulate the activation of other materials, such as components of a stainless steel sample introduced into a training reactors. These models, once validated, can be applied to other situations and materials where a neutron flux can be found, not only nuclear reactors. For instance, activation analysis with an Am-Be source, neutrography techniques in both medical applications and non-destructive analysis of materials, civil engineering applications using a Troxler, analysis of materials in decommissioning of nuclear power plants, etc.

Estimation of the fast neutron fluence in Laguna Verde RPV-Steel specimens simulating their irradiation in a TRIGA reactor

The main purpose of this paper is to predict the fast neutron fluence value expected at four Laguna Verde Nuclear Power Plant RPV-steel specimens, when they are loaded in Mexican TRIGA Mark III reactor. Numerical simulation is done by neutronic calculation with MCNP5 Monte Carlo code for a detailed model of this research reactor core. This calculation will enable the estimation of the irradiation time needed for aging the specimens quickly. In the first part of this work, the MCNP5 developed model was validated through different operating conditions of the TRIGA reactor. The core was simulated to analyze the behavior of the keff when all the control rods are fully withdrawn and fully inserted in cold conditions (293 K); an analysis of the behavior of keff when only the regulating control rod is fully withdrawn is also included. Real operating conditions of the reactor at a power of 1 MWth in steady state were also simulated, in order to obtain the neutron flux in the six irradiation holes of the TRIGA reactor. The calculation of the axial neutron flux in each irradiation hole was validated applying the Neutron Activation Analysis technique (NAA), to calculate the activity of different materials that were irradiated in the TRIGA reactor; the results were compared with the activity calculated with MCNP5 for each material. Afterwards, the fast neutron flux that the RPV-steel specimens received in the experimental facility E−16 was also calculated with MCNP5. Finally, the irradiation time of the specimens in the TRIGA was estimated in order to obtain values of the fast neutron fluence at 24, 32 and 48 Effective Full Power Years (EFPY).

Manifestation of optical activity in different materials

Various manifestations of optical activity (OA) in crystals and organic materials are considered. Examples of optically active enantiomorphic and nonenantiomorphic crystals of 18 symmetry classes are presented. The OA of enantiomorphic organic materials as components of living nature (amino acids, sugars, and proteins) is analyzed. Questions related to the origin of life on earth are considered. Examples of differences in the enantiomers of drugs are shown. The consequences of replacing conventional left-handed amino acids with additionally right-handed amino acids for living organisms are indicated.

Renewable Energy via Photocatalysis

The generation of renewable energy through photocatalysis is an attractive option to utilize the abundantly available solar radiation for a sustainable future. Photocatalysis refers to charge-carrier, i.e. electron and hole, mediated reactions occurring on a semiconductor surface in presence of ultraviolet or visible light radiation. Photocatalysis is a well established advanced oxidation technique for the decontamination of toxic organic pollutants to CO2 and H2O. However, the generation of energy in the form of hydrogen, hydrocarbon fuels and electricity via photocatalysis is an upcoming field with great many technical challenges towards practical implementation. This review will describe the fundamental reaction mechanism of (i) photocatalytic water splitting, (ii) photocatalytic H2 generation in presence of different sacrificial agents, (iii) H2 and electricity generation in a photofuel cell, (iv) photocatalytic reduction of CO2 to hydrocarbons and useful chemicals, and (v) photocatalytic water-gas shift reaction. A historic and recent perspective of the above conversion techniques, especially with regard to the development of TiO2-based and non-TiO2 materials is provided. The activity of different materials for the above reactions based on quantifiers like reaction rate, quantum yield and incident-photon-to-current efficiency is compared, and key design considerations of the “best” photocatalyst or photoelectrode is outlined. An overall assessment of the research area indicates that the presently achieved quantum efficiencies for the above reactions are rather moderate in the visible region, and the goal is to develop a catalyst that absorbs visible radiation, provides good charge-carrier separation, and exhibits high stability for long periods of usage.

Applicability of surfaces containing silver in domestic refrigerators

AbstractHygiene is an area of great concern in private households. Especially refrigerator interior surfaces are contaminated with food residues or microorganisms. Refrigerator manufacturers are attempting to improve the hygienic conditions by including antimicrobial refrigerator plastic surfaces. However, although refrigerator surfaces are already frequently compounded using, e.g. silver additives, it is still unclear whether these surfaces have the ability to decrease contamination under the special application conditions found within refrigerators. Thus, the aim of this study was to evaluate the ability of surfaces containing silver to decrease bacterial count in domestic refrigerators considering realistic conditions in domestic refrigerators. Laboratory investigations have been conducted concerning the rate of antimicrobial activity of different materials containing silver as regards their functioning to reduce surface contamination as related to test organisms and environmental conditions (e.g. temperature, food residues). The reduction rate on the tested plastic materials containing silver varied between log10 0.1–7.4 cfu/ml compared with the reference sheets. Thereby the rate is influenced by the plastic type, the microorganism and temperature. Further on the investigations made evident that the inhibitory effect of silver compounds is greatly reduced by the presence of protein residues. Consequently, investigations concerning the hygienic status within domestic refrigerators have been conducted and the cleaning behaviour by refrigerator users has been assessed. It became evident that, in particular, glass surfaces are often contaminated with protein residues. Furthermore, the cleaning frequency is very low as only 16% of refrigerator users clean their refrigerators monthly or more frequently. Thus, under these conditions found in practice, no additional benefit as to hygiene status can be expected by adding silver to refrigerator glass surfaces. Therefore, a careful choice of silver applications in domestic refrigerators is necessary considering the special conditions in private households. In addition, the factor of sustainability needs to be considered with regard to the unnecessary entry of silver ions into sewage.

Sol-Gel Titania and Titania-Silica Mixed Oxides Photocatalysts

This paper presents a review of the work published by the authors on the synthesis, characterization and evaluation of the photocatalytic activity of TiO2/SiO2 materials. The use of titania-silica mixed oxides photocatalysts is proposed basically as a process improvement to overcome the difficulties of recovering titania from the slurries after the photocatalytic treatment of contaminated waters. To understand the mechanism governing the photocatalytic activity of these materials, several titania-silica photocatalysts have been prepared through a sol-gel method that allows controlling the main variables to obtain materials with different textural properties, degree of titania incorporation, dispersion of the photoactive phase and crystallinity of titanium dioxide. The samples have been characterized in depth, looking for correlations between the main physicochemical properties (TiO2 crystallite size, band gap energy and titania surface area) and the activity shown in the photocatalytic oxidation of cyanide, selected as model pollutant. The results suggest that the photocatalytic activity is strongly influenced by the quality of the titania crystal network, which in turn is improved by the use of a hydrothermal crystallization procedure. Additionally, the evaluation of the fraction of the total surface area corresponding to titania is mandatory for comparing the catalytic activity of different materials in processes in which titanium dioxide is the only phase catalytically active and silica behaves as an inert support.

Preparation, conversion, and comparison of the photocatalytic property of Cd(OH) 2, CdO, CdS and CdSe

In this paper, we report the hydrothermal preparation of Cd(OH) 2 nanowires and further conversion to CdO nanobelts, CdS nanowires and CdSe nanoparticles through thermal treatment, solvothermal and mixed-solvothermal routes, respectively. The as-obtained products were characterized by means of powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FEMSEM). Research showed that four cadmium compounds were good photocatalysts for the degradation of organic dyes such as Safranine T and Pyronine B, under irradiation of 365 nm UV light. The order of catalytic activity of different materials was found to be Cd(OH) 2<CdO<CdS<CdSe.

Methodology for Rapid Determination of Pozzolanic Activity of Materials

Abstract Determination of pozzolanic activity, and in particular lime reactivity, of various materials such as fly ash, cenospheres, blast furnace slag, etc., is quite essential for their efficient application in cement and concrete. It also plays an important role in the selection of the material as a stabilizer in various environmental cleanup projects, such as heavy metal retention and waste immobilization strategies. Though ASTM C 311, ASTM C 593, and IS 1727 are being followed to determine pozzolanic activity of different materials, they are quite time consuming. This necessitates development of a methodology that can be employed for determining the pozzolanic activity of different materials, quite rapidly and easily. With this in view, a methodology that indirectly estimates pozzolanic activity of different materials, by measuring electrical conductivity of their mixture in partially saturated lime solution, has been developed and its details are presented in this paper.

On the comparison of photocatalysts activity: A novel procedure for the measurement of titania surface in TiO 2/SiO 2 materials

The distribution of two different phases in a mixed oxide material could be investigated through several physicochemical characterization techniques. However, the estimation of the fraction of the total surface area corresponding to each oxide is a very difficult task. In this work, we present a novel procedure for the determination of the titanium dioxide surface in titania–silica materials. This new method is based on the measurement of the phosphorus content of the mixed oxide after reaction with phenylphosphonic acid. The quantification of the TiO 2 surface has permitted the comparison of the catalytic activity of different materials in processes in which titanium dioxide is the only catalytically active phase and silica behaves as an inert support, as, for instance, in photocatalytic reactions. The activity of several TiO 2/SiO 2 photocatalysts for cyanide and methanol photooxidation have been analysed and compared with pure TiO 2 materials in terms of equal mass of semiconductor, photonic efficiency and active surface area. The results suggest the possibility of achieving surface activity rates even higher than the material Degussa P25 when using nanocrystalline titania supported on silica.

Neutron transport calculations in support of neutron diagnostics at JET

At JET the primary diagnostic for monitoring the neutron emission is a set of fission chambers. These are calibrated using the neutron activation technique. A second independent measurement of the neutron yield can be obtained from the neutron profile monitor. Both measurements depend on neutron transport calculations and at JET this has been done using the neutron transport code MCNP. The introduction of tritium into JET plasmas provided an opportunity to check the modeling by comparing the activation of different materials. The calculation of the neutron spectrum at a re-entrant irradiation position was found to be consistent with measurements and an accuracy of &amp;lt;7% in the neutron yield measurement was obtained. Neutron transport calculations of the effective collimator correction and attenuation for the profile monitor are also described.

The pozzolanic activity of different materials, its influence on the hydration heat in mortars

This work presents the relationship that exists between pozzolanic activity in certain materials (opaline rocks, fly ash and silica fume) and hydration heat, measured using the Langavant calorimeter method. Pozzolanic activity is evaluated using an accelerated method that establishes the reaction speed of the different materials considered. While replacement of part of the cement in a mortar or concrete typically reduces the overall heat of hydration, it is shown that, compared to a control cement, silica fume and opaline rock mixes with cement give increased heat output during early hydration. This is due to their rapid and strong limepozzolanic reaction. The much less reactive fly ash decreased early heat output, compared to the control cement, a good correlation of between pozzolanic activity and hydration heat found.

Characterization of a nitrogen flow within a plasma wind tunnel

This article presents a comparison of numerical and measured results of a nitrogen high-enthalpy flow. Experimental data at a first cross section are used as initial and boundary conditions for a numerical simulation of the high-enthalpy flow, the results at a second cross section are compared with the numerical solution. The program system employed to examine the flow consists of a Navier-Stokes flowfield solver including models to investigate thermal and chemical nonequilibrium flows. Different measurement techniques were applied to determine the flowfield properties. The measurements made possible the calculation of the local specific enthalpy and mass flux distributions of the plasma plume by basic thermodynamic equations. These mass flux distributions are compared with measurements by mass spectrometry. Special emphasis is also placed on the investigation of the catalytic activity of different materials.

Testing of an activation cross sections library according to integral data

Comparing the experimental data on the activation of different materials in neutron fluxes, whose spectra are similar to the spectrum of a thermonuclear reactor, to the computational results obtained using the activation cross sections from the ADL-3 library shows the following: