Gas-phase electrocatalytic conversion of CO_2 to chemicals on sputtered Cu and Cu–C catalysts electrodes

A novel gas-phase electrocatalytic cell containing a low-temperature proton exchange membrane(PEM)was developed to electrochemically convert CO_2into organic compounds.Two different Cu-based cathode catalysts(Cu and Cu–C)were prepared by physical vapor deposition method(sputtering)and subsequently employed for the gas-phase electroreduction of CO_2at different temperatures(70–90°C).The prepared electrodes Cu and Cu–C were characterized by X-ray diffraction(XRD),X-ray photoemission spectroscopy(XPS)and scanning electron microscopy(SEM).As revealed,Cu is partially oxidized on the surface of the samples and the Cu and Cu–C cathodic catalysts were comprised of a porous,continuous,and homogeneous film with nanocrystalline Cu with a grain size of 16 and 8 nm,respectively.The influence of the applied current and temperature on the electro-catalytic activity and selectivity of these materials was investigated.Among the two investigated electrodes,the pure Cu catalyst film showed the highest CO_2specific electrocatalytic reduction rates and higher selectivity to methanol formation compared to the Cu–C electrode,which was attributed to the higher particle size of the former and lower Cu O/Cu ratio.The obtained results show potential interest for the possible use of electrical renewable energy for the transformation of CO_2into valuable products using low metal loading Cu based electrodes(0.5 mg Cu cm^(-2))prepared by sputtering.

A Review of the Production Cycle of Titanium Dioxide Pigment

Titanium is a very important element for several industrial applications, being one of the ninth most abundant elements in the Earth’s crust (0.63% wt). In this work it will discuss the different mining and industrial activities involved in the production of titanium dioxide. The first step analyzed will treat about the beneficiation mining process of titanium mineral, and secondly, it will discuss the two main processes of the TiO2 manufacturing (sulphate and chloride routes). In addition, we will show different uses of the titanium dioxide pigment as filler in paper, plastics and rubber industries and as flux in glass manufacture, etc. Finally, we will show that the old wastes are currently called co-products since they were valorized, being commercialized by the Spanish industry of TiO2 production in different fields such as agriculture, civil engineering, or cement manufacturing.

Synthesis and Thermal Behavior of Metallic Cobalt Micro and Nanostructures

In this contribution, a comparative study of metallic cobalt micro and nanoparticles obtained in solution by four different chemical routes is reported. Classic routes such as borohydride reduction in aqueous media and the so-called polyol methodology were used to obtain the cobalt nanostructures to be studied. Using CTAB as surfactant, cobalt hollow nanostructures were obtained. The use of strong reducing agents, like sodium borohydride, favors the formation of quasi-monodispersed nanoparticles of about 2 nm size but accompanied with impurities; for hydrazine(a mild reducer), nanoparticles of larger size are obtained which organize in spherical microagglomerates. Valuable information on the particles thermal stability and on nature of the species anchored at their surface was obtained from thermogravimetric curves. The samples to be studied were characterized from UV-vis, IR, X-ray diffraction, and electron microscopy images(scanning and transmission).

Transient Behavior of a System Composed of Conductive Thin Wire Structures Excited by Harmonic and Lightning Type Signals

The transient response of a system of independent electrodes buried in a semi-infinite conducting medium is studied. Using a simple and versatile numerical scheme written by the authors and based on the Electric Field Integral Equation (EFIE), the effect caused by harmonic signals ranging on frequency from Hz to hundred of MHz, and also by lightning type driving signal striking at a remote point far from the conductors, is extensively studied. The value of the scalar potential appearing on the electrodes as a function of the frequency of the applied signal is one of the variables investigated. Other features such as the input impedance at the injection point of the signal and the Ground Potential Rise (GPR) over the electrode system are also discussed.

Radon exhalation from phosphogypsum stabilized in sulfur polymer cement

Phosphogypsum (PG), primary by-product from phosphoric acid production, is accumulated in large stock-piles which were active until 2010, when spills were banned. It is considered as NORM material that contains radionuclides from 238U and decay series which are of most radiotoxicity. PG was valorized and/or recycled in a building material, sulfur polymer cement (SPC). The SPC-PG samples reach the international regulation to use in the manufacture of building materials without radiological restrictions, except the sample with the 50% of PG. Under normal conditions of ventilation the contribution to the expected radon indoor concentration is also below the international recommendation.

Photoluminescence Response of HfO₂:Eu³⁺Obtained by Hydrothermal Route

In this work, the synthesis and photoluminescence response of HfO2 doped with Eu3+ (HfO2:Eu3+) are reported. The synthesis was carried out by the hydrothermal route of HfCl4 and EuCl3?.6H2O with NH4OH dissolved in deionized water. To perform the hydrolysis, the precursors were subjected to hydrothermal treatment at 120°C, under autogenously pressure at reaction times of 24, 40, 52 and 72 hours. The synthesized nanoparticles were characterized by mean of X- ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), and energy dispersive spectroscopy (EDS). Samples excited with 395 nm radiation show photoluminescence emission lines corresponding to the electronic transitions 5D0 → 7FJ (J = 0 → 4), characteristics of the Eu3+ ion. The photoluminescence emission intensity increases with the increasing of the reaction time, reaching a maximum at 72 hours. The excitation band peaked at 395 nm, makes this material an excellent candidate for applications in solid state white lamps.

Nanomaterials for Sensor Applications

Recently, a large part of the advances in nanotechnology have been directed towards the development of high-speed electronics, more efficient catalysts, and sensors. This latter group of applications has great relevance and unprecedented development potential for the coming years.So far, some of the main objectives for the development of sensors have focused on making more sensitive, effective and specific sensing devices.The improvement of these systems and the increase of specificity are clearly associated with a decrease in size of the components, which can lead to obtaining more rapid action, almost in real time. Nanomaterials currently used in sensor development include a long list of nanostructured systems, as for example: metal nanotubes, nanowires, nanofibers, nanocomposites, nanorods, nanoparticles, nanostructured polymers, and different allotropes of carbon as carbon nanotubes, graphene or fullerenes, among others.

Tailoring Properties of Biocompatible PEG-DMA Hydrogels with UV Light

Hydrogels are highly water-absorbent hydrophilic polymer networks, which show potential in many biocompatible applications. In previous work, we demonstrated the feasibility of using poly(ethylene glycol) dimethacrylate (PEG-DMA) gels polymerized with a photoinitiator for encapsulation and stabilization of painted biomimetic membrane arrays for novel separation technologies or biosensor applications. These gels were formed from PEG-DMA monomers suspended in phosphate buffered saline (PBS) solution and gelated by radical polymerization in the presence of the photoinitiator Darocur 1173. In this work, we show that the properties of a PEG-DMA hydrogel formed by photoinitiated polymerizetion can be tailored by varying the photocrosslinking time. Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy (RS) showed that the optimal crosslinking time for the gel was 6 - 10 minutes and that the water content of the gels could be tuned in the range of 50 - 90 wt%. The resistivity was between 0.8 - 3.5 Ωm, which is comparable to that of PBS. The low resistivity of the gel makes it compatible for encapsulating membranes for (ion channel based) biosensor applications. With FTIR and RS we identified spectral features of the hydrogel, which may serve as a diagnostic tool to monitor changes in the gels due to variation in parameters such as time, pH, temperature, aging or exposure to chemicals or biological material.

Experimental implementation of phase triplicator gratings in a spatial light modulator

In this work,we compare different methods for implementing a triplicator,a phase grating that generates three equiintense diffraction orders.The design with optimal efficiency features a continuous phase profile,which cannot be easily reproduced,and is typically affected by quantization.We compare its performance with binary and sinusoidal phase profiles.We also analyze the effect of quantizing the phase levels.Finally,a random approach is adopted to eliminate the additional harmonic orders.In all cases,a liquid-crystal-on-silicon spatial light modulator is employed to experimentally verify and compare the different approaches.

Towards efficient strain engineering of 2D materials:A four-points bending approach for compressive strain

Strain engineering,as a powerful strategy to tune the optical and electrical properties of two-dimensional(2D)materials by deforming their crystal lattice,has attracted significant interest in recent years.2D materials can sustain ultra-high strains,even up to 10%,due to the lack of dangling bonds on their surface,making them ideal brittle solids.This remarkable mechanical resilience,together with a strong strain-tunable band structure,endows 2D materials with a broad optical and electrical response upon strain.However,strain engineering based on 2D materials is restricted by their nanoscale and strain quantification troubles.In this study,we have modified a homebuilt three-points bending apparatus to transform it into a four-points bending apparatus that allows for the application of both compressive and tensile strains on 2D materials.This approach allows for the efficient and reproducible construction of a strain system and minimizes the buckling effect caused by the van der Waals interaction by adamantane encapsulation strategy.Our results demonstrate the feasibility of introducing compressive strain on 2D materials and the potential for tuning their optical and physical properties through this approach.

Single-Particle Analysis in An Indoor Working Environment in Valencia, Spain

Actually is recognized the importance of indoor air environment and associated health risks. In order to evaluate indoor air quality and to characterize the particles in terms of size, composition and shape were done measurements of the suspended particulate matter in a mechanical workshop of the Polytechnic University of Valencia (Spain). These measurements were performed using scanning electron microscope (SEM) with energy dispersive X-ray microanalysis (EDX) and image digital analysis. To differentiation of individual particles in the fine- ultrafine fraction, in some case, was used the atomic force microscopy (AFM). Multivariate statistics, such as hierarchical cluster analysis and factor analysis were appliqued and allowed to establish groups of elements and in this way to facilitate the identification of the natural and anthropogenic sources. It is confirmed that indoor air is influenced by outdoor surroundings and the anthropogenic sources due to the daily activity.

基底旋转速度对射频溅射法制备Al掺杂ZnO薄膜结构和性能的影响（英文）

采用射频溅射法于室温在玻璃基底上制备了铝掺杂ZnO(AZO)薄膜,研究了基底旋转速度(ωS)对薄膜形态、结构、光学和电学性质的影响。扫描电子显微镜横向图片显示,通过基底旋转能够产生致密的柱状结构。原子力显微镜图像表明,基底旋转状态下形成的样品其表面颗粒比基体静止状态下的颗粒小且致密,从而导致细小的晶粒尺寸。XRD结果表明,所有薄膜均为六方纤锌矿结构,c轴择优取向且分布有拉应力。紫外可见光区平均透光率在90%以上。当ωS=0 r/min时,电阻率处于最低值(8.5×10^(-3)?·cm),载流子浓度为1.8×10^(20)cm^(-3),霍尔迁移率为4.19 cm^2/(V·s)。对于其他样品,基底旋转会引起载流子浓度和霍尔迁移率的变化,从而导致电阻率增加。结果表明:基底旋转速度对AZO薄膜的形貌、结构、光学和电学性能存在较大影响。

All-optical nonlinear chiral ultrafast magnetization dynamics driven by circularly polarized magnetic fields

Ultrafast laser pulses provide unique tools to manipulate magnetization dynamics at femtosecond timescales,where the interaction of the electric field usually dominates over the magnetic field.Recent proposals using structured laser beams have demonstrated the possibility to produce regions where intense oscillating magnetic fields are isolated from the electric field.In these conditions,we show that technologically feasible tesla-scale circularly polarized high-frequency magnetic fields induce purely precessional nonlinear magnetization dynamics.This fundamental result not only opens an avenue in the study of laser-induced ultrafast magnetization dynamics,but also sustains technological implications as a route to promote all-optical non-thermal magnetization dynamics both at shorter timescales-towards the subfemtosecond regime-and at THz frequencies.

Prediction of seakeeping in the early stage of conventional monohull vessels design using artificial neural network

Nowadays seakeeping is mostly analyzed by means of model testing or numerical models.Both require a significant amount of time and the exact hull geometry,and therefore seakeeping is not taken into account at the early stages of ship design.Hence the main objective of this work is the development of a seakeeping prediction tool to be used in the early stages of ship design.This tool must be fast,accurate,and not require the exact hull shape.To this end,an artificial intel-ligence(AI)algorithm has been developed.This algorithm is based on Artificial Neural Networks(ANNs)and only requires a number of ship coefficients of form.The methodology developed to obtain the predictive algorithm is presented as well as the database of ships used for training the ANN.The data were generated using a frequency domain seakeeping code based on the boundary element method(BEM).Also,the AI predictions are compared to the BEM results using both,ship hulls included and not included in the database.As a result of this work it has been obtained an AI tool for seakeeping prediction of conventional monohull vessels.

Preparation and Characterization of Flexible, Transparent and Thermally Stable Aromatic Co-polyamides

Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid(DEAIA) and 5-tert-butylisophthalic acid(TERT), with 4,4′-(hexafluoroisopropylidene)dianiline(HFA) or 2,3,5,6-tetramethyl-1,4-phenylenediamine(Durene) by direct polycondensation. The structures of the obtained aromatic co-polyamides were confirmed by FTIR, Raman and 1 H-NMR. The co-copolyamide films, DHTH and DDTD, exhibited rms-roughness values between 0.94 and 1.60 nm, respectively. Moreover, they presented good thermal stability up to300 °C. Young's moduli of the co-polyamide films were between 4.1 and 4.3 GPa. X-ray diffraction results showed that the co-polyamide films were amorphous due to the incorporation of both bulky pendant groups, tert-butyl and dibenzobarrelene. The combination of bulky pendant groups provided intrinsically transparent co-polyamide films with a transmittance higher than 88% in the range of 400-780 nm.Due to these outstanding film and optical properties, they are suggested to be flexible substrates in applications for solar cell and other portable electronic devices.

Photoluminescence characteristics of soft PZT 53/47 ceramic doped at A and/or B sites

This study presents the photoluminescence characteristics of the PZT 53/47 system doped at A and/or B sites, with Nb(PZTN), La(PLZT), and Nb–La(PLZTN) in the concentration range from 0.2 to 1.0 molar fraction. The intensity of the emission bands of the system PZTN is two orders higher than the intensity of the emission bands of the systems PLZT and PLZTN, and these emission bands are located at 1.73 eV(718 nm), 2.56 eV(485 nm), and 2.93 eV(424 nm). The origin of the luminescence in these systems is associated with lead and oxygen vacancies produced during the sintering process. The results from X-ray diffraction(XRD) show a mixture of rhombohedral and tetragonal phases. The system PZTN shows a higher tetragonal phase concentration, while PLZT and PLZTN systems show a higher rhombohedral phase concentration. The cell volume shows an increase with dopant concentration only in the case of the PLZTN system. The band gap energy shows a small variation in the PZTN and PLZTN cases around 3.0 eV, a close value to the band gap energy of the pure PZT 53/47 sample. The system PLZT shows an increasing behavior until 4.41 eV for the higher dopant concentration.

Analysis of Strehl ratio limit with superresolution binary phase filters

Several pupil filtering techniques have been developed in the last few years to obtain transverse superresolution （a narrower point spread function core）. Such a core decrease entails two relevant limitations： a decrease of the peak intensity and an increase of the sidelobe intensity. Here, we calculate the Strehl ratio as a function of the core size for the most used binary phase filters. Furthermore, we show that this relation approaches the fundamental limit of the attainable Strehl ratio at the focal plane for any filter. Finally, we show the calculation of the peak-to-sidelobe ratio in order to check the system viability in every application.

Development and characterization of photovoltaic tandemjunction nanowires using electron-beam-induced current measurements

Nanowires have many interesting properties that are of advantage for solar cells,such as the epitaxial combination of latticemismatched materials without plastic deformation.This could be utilized for the synthesis of axial tandem-junction nanowire solar cells with high efficiency at low material cost.Electron-beam-induced current measurements have been used to optimize the performance of single-junction nanowire solar cells.Here,we use electron-beam-induced current measurements to break the barrier to photovoltaic tandem-junction nanowires.In particular,we identify and subsequently prevent the occurrence of a parasitic junction when combining an InP n-i-p junction with a tunnel diode.Furthermore,we demonstrate how to use optical and electrical biases to individually measure the electron-beam-induced current of both sub-cells of photovoltaic tandem-junction nanowires.We show that with an applied voltage in forward direction,all junctions can be analyzed simultaneously.The development of this characterization technique enables further optimization of tandem-junction nanowire solar cells.

Stronger Hardy-like proof of quantum contextuality

A Hardy-like proof of quantum contextuality is a compelling way to see the conflict between quantum theory and noncontextual hidden variables(NCHVs),as the latter predict that a particular probability must be zero,while quantum theory predicts a nonzero value.For the existing Hardy-like proofs,the success probability tends to 1/2when the number of measurement settings n goes to infinity.It means the conflict between the existing Hardy-like proof and NCHV theory is weak,which is not conducive to experimental observation.Here we advance the study of a stronger Hardy-like proof of quantum contextuality,whose success probability is always higher than the previous ones generated from a certain n-cycle graph.Furthermore,the success probability tends to 1 when n goes to infinity.We perform the experimental test of the Hardy-like proof in the simplest case of n=7 by using a four-dimensional quantum system encoded in the polarization and orbital angular momentum of single photons.The experimental result agrees with the theoretical prediction within experimental errors.In addition,by starting from our Hardy-like proof,one can establish the stronger noncontextuality inequality,for which the quantumclassical ratio is higher with the same n,which provides a new method to construct some optimal noncontextuality inequalities.Our results offer a way for optimizing and enriching exclusivity graphs,helping to explore more abundant quantum properties.

Effect of the Coulomb and dielectric forces on the onset of Rayleigh-Bénard convection

In this paper,the effect of Coulomb and dielectric forces on the onset of Rayleigh-Bénard convection(RBC)in a dielectric liquid layer contained between two parallel electrode plates has been numerically investigated.Two different operating conditions have been considered in electrohydrodynamic(EHD)conduction:ohmic and saturation,and variations in the physical properties of the dielectric fluid with temperature.The electric equations and the state equations based on the Boussinesq approximation are integrated in the framework of OpenFOAM buoyantBoussinesqPimpleFoam program.The results show that in the ohmic regime,the combined effect of Coulomb and dielectric forces promotes the onset of RBC flow,while in the saturation state,the inhibition of RBC flow by Coulomb force is more significant.The value of the critical Rayleigh number Ra decreases with increasing electric Reynolds number ReE in the ohmic regime,whereas in the saturation state,the critical Ra increases with increasing ReE.In the saturation regime,the flow field always has a steady flow in the range of parameters considered.However,the onset of the RBC flow promoted by the dielectric force is more pronounced in the ohmic state.Due to the presence of the dielectric force,the flow field exhibits periodic oscillatory flow at low electric Reynolds numbers for the range of parameters considered.