Isothermal hydrogen absorption process of Pd-capped Mg films traced by ion beam techniques and optical methods

Pd-capped nanocrystalline Mg films were prepared by electron beam evaporation and hydrogenated under isothermal conditions to inves-tigate the hydrogen absorption process via ion beam techniques and in situ optical methods.Films were characterized by different techniques such as X-ray diffraction(XRD)and scanning electron microscopy(SEM).Rutherford backscattering spectrometry(RBS)and elastic recoil detection analysis(ERDA)provided a detailed compositional depth profile of the films during hydrogenation.Gas-solid reaction kinetics theory applied to ERDA data revealed a H absorption mechanism controlled by H diffusion.This rate-limiting step was also confirmed by XRD measurements.The diffusion coefficient(D)was also determined via RBS and ERDA,with a value of(1.1±0.1)·10^(−13)cm^(2)/s at 140℃.Results confirm the validity of IBA to monitor the hydrogenation process and to extract the control mechanism of the process.The H kinetic information given by optical methods is strongly influenced by the optical absorption of the magnesium layer,revealing that thinner films are needed to extract further and reliable information from that technique.

Isolated attosecond pulse generation in a semiinfinite gas cell driven by time-gated phase matching

Isolated attosecond pulse(IAP)generation usually involves the use of short-medium gas cells operated at high pressures.In contrast,long-medium schemes at low pressures are commonly perceived as inherently unsuitable for IAP generation due to the nonlinear phenomena that challenge favourable phase-matching conditions.Here we provide clear experimental evidence on the generation of isolated extreme-ultraviolet attosecond pulses in a semiinfinite gas cell,demonstrating the use of extended-medium geometries for effective production of IAPs.To gain a deeper understanding we develop a simulation method for high-order harmonic generation(HHG),which combines nonlinear propagation with macroscopic HHG solving the 3D time-dependent Schrödinger equation at the singleatom level.Our simulations reveal that the nonlinear spatio-temporal reshaping of the drivingfield,observed in the experiment as a bright plasma channel,acts as a self-regulating mechanism boosting the phase-matching conditions for the generation of IAPs.

Low-Cost and Biodegradable Thermoelectric Devices Based on van der Waals Semiconductors on Paper Substrates

We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates.The devices are based on thin films of WS_(2),Te,and BP(P-type semiconductors)and TiS_(3)and TiS_(2)(N-type semiconductors),deposited by simply rubbing powder of these materials against paper.The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of(+1.32±0.27)mV K^(-1)and(-0.82±0.15)mV K^(-1)for WS_(2)and TiS_(3),respectively.Additionally,Peltier elements were fabricated by interconnecting the P-and N-type films with graphite electrodes.A thermopower value up to 6.11 mV K^(-1)was obtained when the Peltier element were constructed with three junctions.The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic devices.

Processes involving soil CO_(2)dynamic in a sector of Chaco-Pampean plain,Argentina:An isotope geochemical approach

The magnitude and spatial variability of CO_(2)surface emissions and processes involving CO_(2)released to the atmosphere from the soils are relevant issues in the context of climate change.This work evaluated CO_(2)fluxes and^(13)C/^(12)C ratio of vegetation,organic matter,and soil gases from no disturbed soils of Chaco Pampean Plain(Argentina)with different soil properties and environmental conditions(PL and PA units).Soil organic decomposition from individual layers was accompanied byδ^(13)C of total organic carbon(δ^(13)C-TOC)values more enriched to depth.δ^(13)C-TOC values in the upper soil profile~ca.0–15 cm were like the plant community of this area(~−33 to−29‰)whileδ^(13)CTOC varied stronger bellow horizon A,till~−24‰.Bothδ^(13)C-TOC and soilδ^(13)C-CO_(2)were similar(~−24 to 26‰)at deeper horizons(~50–60 cm).Toward the superficial layers,δ^(13)C-TOC andδ^(13)C-CO_(2)showed more differences(till~4‰),due influence of the diffusion process.Horizon A layer(~0–20 cm)from both PL and PA units contained the most enrichedδ^(13)C-CO_(2)values(~−15–17‰)because atmospheric CO_(2)permeated the soil air.A simple two-component mixing model between sources(atmosphericδ^(13)C-CO_(2)and soil CO_(2))confirmed that process.Isotopically,CO_(2)fluxes reflected the biodegradation of C3 plants(source),diffusive transport,and CO_(2)exchange(atmosphere/soil).Soil moisture content appeared as a determining factor in the diffusion process and the magnitude of CO_(2)surface emissions(12–60 g·m^(−2)·d^(−1)).That condition was confirmed by CO_(2)diffusion coefficients estimated by air-filled porosity parameters and soil radon gradient model.

Plant growth and metabolism of exotic and native Crotalaria species for mine land rehabilitation in the Amazon

Despite its enormous benefits,mining is respon-sible for intense changes to vegetation and soil properties.Thus,after extraction,it is necessary to rehabilitate the mined areas,creating better conditions for the establishment of plant species which is challenging.This study evaluated mineral and organic fertilization on the growth,and carbon and nitrogen(N)metabolism of two Crotalaria species[Cro-talaria spectabilis(exotic species)and Crotalaria maypu-rensis(native species from Carajás Mineral Province(CMP)]established on a waste pile from an iron mine in CMP.A control(without fertilizer application)and six fertilization mixtures were tested(i=NPK;ii=NPK+micronutrients;iii=NPK+micronutrients+organic compost;iv=PK;v=PK+micronutrients;vi=PK+micronutrients+organic compost).Fertilization contributed to increased growth of both species,and treatments with NPK and micronutrients had the best results(up to 257%cf.controls),while organic fertilization did not show differences.Exotic Crotalaria had a greater number of nodules,higher nodule dry mass,chlorophyll a and b contents and showed free ammonium as the predominant N form,reflecting greater increments in biomass compared to native species.Although having lower growth,the use of this native species in the rehabilitation of mining areas should be considered,mainly because it has good development and meets current government legislation as an opportunity to restore local biodiversity.

Antifungal activity against Fusarium oxysporum of quinolizidines isolated from three controlled-growth Genisteae plants:structure-activity relationship implications

The Genisteae tribe belongs to the Fabaceae family.The wide occurrence of secondary metabolites,explicitly high-lighting the quinolizidine alkaloids(QAs),characterizes this tribe.In the present study,twenty QAs(1-20),including lupanine(1-7),sparteine(8-10),lupanine(11),cytisine and tetrahydrocytisine(12-17),and matrine(18-20)-type QAs were extracted and isolated from leaves of three species(i.e.,Lupinus polyphyllus(’rusell’hybrid),Lupinus muta-bilis,and Genista monspessulana)belonging to the Genisteae tribe.These plant sources were propagated under greenhouse conditions.The isolated compounds were elucidated by analyzing their spectroscopical data(MS,NMR).The antifungal effect on the mycelial growth of Fusarium oxysporum(Fox)of each isolated QA was then evaluated through the amended medium assay.The best antifungal activity was found to be for compounds 8(IC_(50)=16.5μM),9(IC_(50)=7.2μM),12(IC_(50)=11.3μM),and 18(IC_(50)=12.3μM).The inhibitory data suggest that some QAs could effi-ciently inhibit Fox mycelium growth depending on particular structural requirements deduced from structure-activity relationship scrutinies.The identified quinolizidine-related moieties can be involved in lead structures to develop further antifungal bioactives against Fox.

Synthesis and Characterization of a Polymeric Material Blended to Bone Forming Elements

A synthetizing material blended with two distinct proteins (collagen and casein) and mineral mixture, was developed in order to evaluate their properties suitable for possible applications in the biomedical such as inducing the regeneration of damaged bone, either due to an accident or illness. Samples were evaluated by 1) Mechanical properties tests under the bending, 2) Scanning electronic microscopy and 3) Infrared spectroscopy were carried out. The results showed that the developed material has breaking strength and structure characteristics associated with the protein used in their composition. This fact suggests that the used protein determines the resistance of the material, in such a way according to the required use, being able to choose appropriate strength and duration either short or long time. The material composition for specific use, in order to find the most suitable mixture for bone replacement, or induce bone recovery, according to the required properties similar to those of damaged living tissue.

Pacman Renormalization in Siegel Parameters of Bounded Type

A novel method of renormalization called Pacman renormalization allows us to study (unicritical) Siegel functions through Pacman-type functions. It has been used to investigate the Siegel parameters with combinatorially periodic rotation number in the main cardioid of the Mandelbrot set. It is already known that it can be defined a Pacman renormalization operator such that for Siegel pacmen, with combinatorially periodic rotation numbers, the operator is compact, analytic and has a unique fixed point, at which it is hyperbolic with one-dimensional unstable manifold. In this paper we observe that this Pacman renormalization operator is compact and analytic at any Siegel Pacman or Siegel map with combinatorially bounded rotation number. This allows us to define a renormalization operator on the hybrid classes of the standard Siegel pacmen to which we built its horseshoe where the operator is topologically semiconjugated to the left shift on the space of bi-infinite sequences of natural numbers bounded by some constant.

Shared Memory Semi-Implicit Solver for Hydrodynamical Instability Processes

The Advection-Diffusion Reaction (ADR) equation appears in many problems in nature. This constitutes a general model that is useful in various scenarios, from porous media to atmospheric processes. Particularly, it is used at the interface between two fluids where different types of instabilities due to surface mobility may appear. Together with the ADR equation, the Darcy-Brinkman model describes the phenomena known as fingering that appear in different contexts. The study of this type of system gains in complexity when the number of chemical species dissolved in both fluids increases. With more solutes, the increasing complexity of this phenomenon generally requires much computational power. To face the need for more computational resources, we build a solver tool based on an Alternating Direction Implicit (ADI) scheme that can be run in Central Processing Unit (CPU) and Graphic Processing Unit (GPU) architectures on any notebook. The implementation is done using the MATLAB platform to compare both versions. It is shown that using the GPU version strongly saves both resources and calculation times.

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.

Pendulum systems for harvesting vibration energy from railroad tracks and sleepers during the passage of a high-speed train: A feasibility evaluation

We evaluate the feasibility of recovering energy from the vibrations of track and sleepers,during passage of a high-speed train,by means of a pendulum harvester.A simple mathematical model of the parametric pendulum is employed to obtain numerical predictions,while measured data of vibration tests during the passage of a Thalys high-speed train are considered as input forcing.Since a sustained rotation is the most energetic motion of a pendulum,the possibility of achieving such state is evaluated,taking into account the influence of initial conditions,damping and other factors.Numerical simulations show that rotating pendulum harvesters with sufficiently low viscous damping could be able to generate a usable average power on the order of 5–6 W per unit.Considering a modular arrangement of devices,such energy is enough to feed variety of rail-side equipment,as wireless sensors or warning light systems.However,a suitable choice of initial conditions could be a difficult task,leading to the need of a control action.

钙钛矿结构荧光材料MZrO_3:Eu^(3+),A(M=Ca^(2+), Ba^(2+);A=Li^+, Na^+, K^+)的制备及其发光性质(英文)

Calcium and barium zirconate powders based upon CaZrO 3:Eu3+ , A and BaZrO 3:Eu3+, A(A=Li+, Na+, K+) were prepared by combustion synthesis method and heating to ~1000 °C to improve crystallinity. The structure and morphology of materials were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results showed that CaZrO 3:Eu3+, A and BaZrO 3:Eu3+, A (A=Li+, Na+, K+) perovskites possessed orthorhombic and cubic structures, respectively. The morphologies of all powders were very similar consisting of small, coagulated, cubical particles with narrow size distributions and smooth and regular surfaces. The characteristic luminescences of Eu 3 + ions in CaZrO 3 :Eu3+ , A (A=Li+, Na+, K+) lattices were present with strong emissions at 614 and 625 nm for 5D0 →7F2 transitions with other weaker emissions observed at 575, 592, 655, and 701 nm corresponding to 5D0 → 7Fn transitions (where n=0,1,3,4, respectively). In BaZrO3:Eu3 + both the 5D0 → 7F1and5D0 → 7F2 transitions at 595 and 613 nm were strong. Photoluminescence intensities of CaZrO3:Eu3+samples were higher than those of BaZrO 3:Eu3+lattices. This remarkable increase of photoluminescence intensity (corresponding to 5D0→7Fn transitions) was observed in CaZrO3:Eu3+and BaZrO3:Eu3+ if co-doped with Li + ions. An additional broad band composed of many peaks between 440 to 575 nm was observed in BaZrO3:Eu3+, A samples. The intensity of this band was greatest in Li + co-doped samples and lowest for K + doped samples.

Evaluation of p53 codon 72 polymorphism in adenocarcinomas of the colon and rectum in La Plata, Argentina

AIM： To evaluate the potential association between p53 codon 72 polymorphism and sporadic colorectal adenocarcinoma development, and human papillornavirus （HPV） infection. METHODS： One-hundred and nine controls and 53 patients with colon cancer from the city of La Plata, Argentina were analyzed, p53 codon 72 genotypes and HPV infection were identified using allele-specific polymerase chain reaction and nested polymerase chain reaction, respectively. RESULTS： The differences in the distribution ofp53 codon 72 polymorphisrn between the cases and controls were statistically significant. The arginine allele had a prevalence of 0.65 in controls and 0.77 in cases. The corresponding odds ratio for the homozygous arginine genotype was 2.08 （95% CI, 1.06-4.05; P〈0.05）. Lack of association was found between ,053 polymorphism and HPV infection in the set of adenocarcinomas. CONCLUSION： The findings of the present study indicate that p53 codon 72 arginine homozygous genotype may represent a genetic predisposing factor for colon cancer development. However, further studies are needed in order to elucidate the role of p53 codon 72 polymorphism in colorectal cancer.

Synthesis of Cu nanoparticles by chemical reduction method

Cu nanoparticles (CuNPs) have been synthesized through an easy route by chemical reduction at room temperature. The Cu^2+ ions were reduced and stabilized with sodium borohydride and polyvinylpyrrolidone, respectively. The effect of the variation of the reducing agent/precursor-salt (RA/PS) ratio on the size and morphology of the CuNPs was evaluated. The synthesized material was studied by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The UV-Vis spectra showed a CuNPs plasmon peak at 569 nm and another peak belonging to Cu2O at 485 nm. XRD analysis showed the fcc-Cu phase with a small amount of fcc-Cu2O compound. SEM and TEM studies displayed that small semispherical CuNPs of approximately 7 nm were obtained at the RA/PS ratio of 2.6. The excess of polyvinylpyrrolidone stabilizer played an essential role in preventing CuNPs oxidation. On the other side, Cu2O polyhedral particles with larger sizes up to 150 nm were identified in the RA/PS ratio range of 2.0-1.84. In addition, Cu2O particles having star morphologies with quantum confinement at their tips were obtained at the RA/PS ratio of 1.66.

The Influence of the Precipitation Heat Treatment Temperature on the Metallurgical, Microstructure, Thermal Properties, and Microhardness of an Alpha Brass

Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of the copper alloys which has many applications in everyday life and the industry. In this work, the influence of the precipitation heat treatment temperature on the metallurgical microstructure, structure, thermal properties, and microhardness of an alpha brass is analyzed. Samples were heat treated by precipitation for 2 h at 300°C, 400°C, 500°C, 600°C, and 700°C. The best mechanical properties were found at 500°C of precipitation heat treatment temperature. Specimens were characterized by scanning electron microscopy, X-ray diffraction, Vickers microhardness, photothermal radiometry, and photoacoustic to study the thermal diffusivity and conductivity, as well as the heat capacity. The inverse of the full width at the half maximum analysis showed that the crystallinity decreased as the precipitation heat treatment temperature increased. Metallurgical microstructure and microhardness were correlated to the precipitation heat treatment temperatures to determine the effect on the metallurgical and mechanical properties, as well as the effect on the thermal properties of alpha brass.

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.

New insights into petrogenesis of Miocene magmatism associated with porphyry copper deposits of the Andean Pampean flat slab,Argentina

The Paramillos de Uspallata mining district located in the backarc region of the Pampean flat-slab segment(28°-33°S) features porphyry-type deposits genetically associated with Middle Miocene volcanics. This mineralizing magmatism comprising hydrothermally altered(sodic-calcic, potassic and phyllic alteration) subvolcanic and pyroclastic rocks of andesite-basaltic andesite and dacite-rhyolite composition with a typical arc signature, represents the eastward broadening of the Farellones arc by ~17 Ma. Its geochemistry also reveals a residual mineralogy of amphibole ± garnet with limited plagioclase fractionation resulting in an adakitic signal; however, according to the isotopic data collected in our study, the contributions of MASH(melting-assimilation-storage-homogenization) processes in the acquisition of this signal cannot be disregarded.Both the broadening of the Farellones arc and its residual mineralogy e typical of relatively deep magmatic chambers e are consistent with a slab shallowing and outcoming crustal thickening setting.This tectonic scenario could be interpreted as a result of an early effect of the Juan Fernandez Ridge collision that was further to the north by ~17 Ma. Our findings suggest that magmas were fertile for porphyry type deposits during the early stages of the slab shallowing.

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.

Effect of substrate rotation speed on structure and properties of Al-doped ZnO thin films prepared by rf-sputtering

Al-doped ZnO(AZO)thin films were deposited on glass substrates by rf-sputtering at room temperature.The effects of substrate rotation speed(ωS)on the morphological,structural,optical and electrical properties were investigated.SEM transversal images show that the substrate rotation produces dense columnar structures which were found to be better defined under substrate rotation.AFM images show that the surface particles of the samples formed under substrate rotation are smaller and denser than those of a stationary one,leading to smaller grain sizes.XRD results show that all films have hexagonal wurtzite structure and preferred c-axis orientation with a tensile stress along the c-axis.The average optical transmittance was above90%in UV-Vis region.The lowest resistivity value(8.5×10?3Ω·cm)was achieved atωS=0r/min,with a carrier concentration of1.8×1020cm?3,and a Hall mobility of4.19cm2/(V·s).For all other samples,the substrate rotation induced changes in the carrier concentration and Hall mobility which resulted in the increasing of electrical resistivity.These results indicate that the morphology,structure,optical and electrical properties of the AZO thin films are strongly affected by the substrate rotation speed.

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).