Blue-light-excited NaCe(MoO4)2 microcrystals for photoelectrochemical water splitting

We report the structural, morphological, and optical characterization, and the application of sodium-cerium molybdate (NaCe(MoO₄)₂) as a promising photoelectroactive material for water splitting. Information on these several properties was obtained by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and UV–Vis–NIR diffuse reflectance. For the photoelectrochemical tests, NaCe(MoO₄)₂ microcrystals were deposited on conductive indium-tin oxide (ITO) glass substrate by drop coating, and the activity of the as-prepared photoanode toward oxygen evolution reaction was investigated in the absence and presence of blue light-emitting diode irradiation. Studies carried out by linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy attested to a significant photoelectroactivity of molybdate associated with the fast electron-hole pairs generation. The steady-state photocurrent density recorded under irradiation achieved a remarkable increase, varying from 1.5 µA cm⁻² (light off) to 44.1 µA cm⁻² (light on), in addition, it presents high stability after on–off cycles, what proves the proper performance of NaCe(MoO₄)₂/ITO as photoanode for water splitting.     

Reinforced polymer concrete: Physical properties of the matrix and static/dynamic bond behaviour

The paper aims at analysing the performance of Polyester Polymer Concrete (PPC) reinforced with steel and FRP rebars. The PPC is also compared with conventional cement concrete.

On the one hand, the effect of the polymer matrix microstructure on the mechanical performance (compression and flexural strength, deformability and Young’s modulus) is discussed.

On the other hand, static and dynamic bond behaviour under pure pull-out forces between the PPC and different rebars is tackled. It is analysed the behaviour of metallic and non-metallic rebars embedded in a PPC matrix when they are subjected to both monotonic and cyclic loads. Likewise, analogous tests were performed on cement concrete specimens in order to be able to compare the bonding performance in both types of concrete.     

The Minimum Range Assignment Problem on Linear Radio Networks

Given a set S of radio stations located on a line and an integer h ≥ 1 , the MIN ASSIGNMENT problem consists in finding a range assignment of minimum power consumption provided that any pair of stations can communicate in at most h hops. Previous positive results for this problem are only known when h=|S|-1 or in the uniform chain case (i.e., when the stations are equally spaced). As for the first case, Kirousis et al. [7] provided a polynomial-time algorithm while, for the second case, they derive a polynomial-time approximation algorithm. This paper presents the first polynomial-time, approximation algorithm for the MIN ASSIGNMENT problem. The algorithm guarantees a 2-approximation ratio and runs in O(hn 3 ) time. We also prove that, for fixed h and for ``well spaced'' instances (a broad generalization of the uniform chain case), the problem admits a polynomial-time approximation scheme . This result significantly improves over the approximability result given by Kirousis {et al}. Both our approximation results are obtained via new algorithms that exactly solve two natural variants of the MIN ASSIGNMENT problem: the problem in which every station must reach a fixed one in at most h hops and the problem in which the goal is to select a subset of bases such that all the other stations must reach one base in at most h-1 hops. Finally, we show that for h=2 the MIN ASSIGNMENT problem can be exactly solved in O(n 3 ) time.     

Bayesian wavelet denoising and evolutionary calibration

Wavelet shrinkage estimation has become an attractive and efficient method for signal denoising and compression. Despite the ample variety of methods which have been used in the wavelet denoising context, it has proven elusive to construct threshold estimators with good adaptive properties. Recently, empirical Bayes selection criteria have been proposed to derive adaptive shrinkage estimators. We consider the application of empirical Bayes variable selection criteria to each level of the wavelet transform to obtain adaptive threshold estimates. A set of level-dependent hyperparameters has to be estimated to derive nonlinear data-dependent thresholding rules. We propose the use of an evolutionary algorithm to calibrate the multilevel parameters, in order to automate parameter selection and enhance adaptivity of the threshold estimators. Comparative simulations on a set of standard model functions show good performance. Applications to data drawn from various fields of application are used to explore the practical performance of the proposed approach.     

Current sharing between diode clamps of polar capacitor bank

The layout of a capacitor bank with clamping diodes is investigated based on an experimental 5.5-kJ energy storage unit for pulsed power applications. While the current sharing between parallel-connected capacitors is good, it is not the case with parallel-connected clamping diodes. Despite a very-low-inductance busbar and attention to symmetrical layout, unequal current sharing results. Good agreement was obtained between measured waveforms and a detailed simulation model. The simulation model indicated that the unequal current sharing is due to small differences between the coupling factors of the parasitic busbar inductances near the capacitors at the ends and at the middle of the bank. It is concluded that the best solution is to place the parallel diodes as close as possible to each other at a position where best averaged coupling is achieved with the individual capacitors of the bank.     

Rotary ultrasonic machining for face milling of ceramics

Among the various material removal processes applicable to ceramic materials, rotary ultrasonic machining has the potential for high material removal rate while maintaining low machining pressure and resulting in less surface damage. The limitation of rotary ultrasonic machining is that only circular holes or cavities can be machined due to the rotary motion of the tool. Attempts have been made by other researchers to extend rotary ultrasonic machining process to machining flat surfaces or milling slots. However, these extensions either changed the material removal mechanisms or had some severe drawbacks. One of the reasons for this might be an insufficient understanding of the material removal mechanisms involved. In this paper, a new approach to extend rotary ultrasonic machining to face milling of ceramics is proposed, which keeps all the material removal mechanisms of rotary ultrasonic machining. The development of the experimental apparatus and the design of the cutting tool are described. Preliminary experimental results are presented and discussed.     

The corrosion resistance of hot dip galvanised steel and AA2024-T3 pre-treated with bis-[triethoxysilylpropyl] tetrasulfide solutions doped with Ce(NO3)3

The present work aims at evaluating the anti-corrosion behaviour of a novel pre-treatment based on bis-[triethoxysilylpropyl] tetrasulfide (BTESPT) doped with cerium nitrate for application on hot dip galvanised steel and AA2024-T3 substrates. The corrosion resistance was evaluated by electrochemical impedance spectroscopy (EIS) and by the scanning vibrating electrode technique (SVET), during immersion in NaCl solutions. The electrochemical results showed that the pre-treatment provides excellent corrosion protection to the substrates. Furthermore, the results evidenced improved protection comparatively to the use of undoped BTESPT pre-treatments, both for galvanised steel and AA2024-T3. This improvement is most likely due to enhanced barrier properties of the film and additional active corrosion protection originated from the inhibiting action of the cerium-based inhibitor impregnated in the silane matrix.     

Preparation of polyclonal antibodies specific for wine proteins

Immunology is an expanding area of research with potentially important applications in the analysis of many biological molecules. Polyclonal antibodies were raised in rabbits against specific proteins as well as against the total protein from a Portuguese wine. FPLC cation exchange chromatography was used to isolate the total protein fraction and, when in combination with denaturing electrophoresis, to purify individual wine polypeptides. To obtain a high titre, an injection of each antigen followed by three boosters were given in the immunisation of each rabbit. The titre of the antisera was measured by the ELISA technique and the specificity of the antibodies detected by immunoblotting. The antibodies produced were shown to be highly specific for the corresponding antigens. However, antibodies obtained specifically against a highly purified wine polypeptide seem to recognize the other major wine polypeptides, raising the possibility of structure similarity between different wine proteins. Neither the anti‐total wine protein antibodies not the anti‐specific wine protein antibodies originated a signal when used to probe thaumatin or chitinase. © 1999 Society of Chemical Industry     

Identification of impact odorants of young red wines made with Merlot,Cabernet Sauvignon and Grenache grape varieties: a comparative study

An Aroma Extract Dilution Analysis (AEDA) has been carried out on three monovarietal young red wines plus a mixture of wines aged one year. The aromograms contain 85 odour-active regions classified in four categories of intensity. The 11 most powerful odorants, 14 out of the 17 second-most powerful, and 34 of the rest could be identified using a HPLC prefractionation method and standard HRGC-MS-olfactometric techniques. The most active odorants of the monovarietal wines were isoamyl and β-phenylethyl alcohols, the ethyl esters of butyric, isobutyric, 2-methyl butyric and hexanoic acids, γ-nonalactone and eugenol. Some others worth mentioning are ethyl isovalerate, isoamyl acetate, hexanol, c-3-hexenol, linalool, geraniol, guaiacol, ethyl cinnamate, ethyl dihydrocinnamate, β-damascenone, δ-decalactone and wine lactone. Compounds with less aromatic intensity but also present in some of the wines were sotolon, isopropyl- and isobutylmethoxypyrazines and 4-mercapto-4-methylpentan-2-one. Data show that there are no impact compounds characteristic of only one variety, and that differences between varieties are quantitative rather than qualitative. © 1999 Society of Chemical Industry     

The AEROPILs Generation: Novel Poly(Ionic Liquid)-Based Aerogels for CO2 Capture

CO₂ levels in the atmosphere are increasing exponentially. The current climate change effects motivate an urgent need for new and sustainable materials to capture CO₂. Porous materials are particularly interesting for processes that take place near atmospheric pressure. However, materials design should not only consider the morphology, but also the chemical identity of the CO₂ sorbent to enhance the affinity towards CO₂. Poly(ionic liquid)s (PILs) can enhance CO₂ sorption capacity, but tailoring the porosity is still a challenge. Aerogel’s properties grant production strategies that ensure a porosity control. In this work, we joined both worlds, PILs and aerogels, to produce a sustainable CO₂ sorbent. PIL-chitosan aerogels (AEROPILs) in the form of beads were successfully obtained with high porosity (94.6–97.0%) and surface areas (270–744 m²/g). AEROPILs were applied for the first time as CO₂ sorbents. The combination of PILs with chitosan aerogels generally increased the CO₂ sorption capability of these materials, being the maximum CO₂ capture capacity obtained (0.70 mmol g⁻¹, at 25 °C and 1 bar) for the CHT:P[DADMA]Cl_30% AEROPIL.