L-Band Harmonic Mode Locking of Single-, Two-, and Three-Soliton Bunches from C-Band Amplifier in a Figure-of-Eight Fiber Laser

We report the experimental emission above 1.6 μm of harmonic mode locking of single-, two-, and three-soliton bunches in a C-band Er:Yb codoped silica fiber laser. The laser cavity consists of two connected fiber loops in the figure-of-eight configuration. In such a system the mode-locking regime arises spontaneously due to the nonlinear optical loop mirror, which acts as a saturable absorber. The 1.6 μm oscillation is enhanced by minimizing the linear intra-cavity losses. Depending on the pump power and the polarization controllers, the laser generates harmonic mode locking above 1.6 μm containing patterns with one, two or three pulses. These two last regimes have not been achieved so far at a long-wavelength range

Application of Adsorption Models for Fluoride, Nitrate, and Sulfate Ion Removal by AMX Membrane

An anion exchange membrane, (AMX) that carries a quaternary ammonium functional group has been investigated for its adsorption of fluoride, nitrate and sulfate from aqueous solutions. Fitting of the Freundlich, Langmuir, and Dubinin–Radushkevich adsorption models to the equilibrium data was performed at different temperatures in the range of 283?313K. The sorption parameters of the studied models were determined by linear regression and discussed. Adsorption analysis results obtained at various temperatures showed that the adsorption pattern on the membrane followed Langmuir isotherms. Thermodynamic studies revealed that the adsorption of the AMX membrane to the studied ions was spontaneous. The 0 ?GT values suggested the affinity order of the membrane for the studied anions. At 283K and 298K, the affinity order was: ? ? ? SO ? NO3 ? F 2 4 . This order was: ? ? ? ? ? 3 2 F SO4 NO at 313K. The standard enthalpy change and the standard entropy change were found to be ?11.63 kJ/mol and ?9.93 J/mol. K for the adsorption of nitrate, 7.42 kJ/mol and 58,73 J/mol. K for the adsorption of sulfate, and 74.21 kJ/mol and 274.9 J/mol. K for the adsorption of fluoride, respectively. The negative values of standard free energy 0 ?GT indicate the spontaneous natures of adsorption of studied anions onto the AMX membrane

A Numerical-Analytical Hybrid Approach for the Identification of SDM Solar Cell Unknown Parameters

Appropriate modeling and accurate parameter identification of solar cells are crucial in the optimization of photovoltaic (PV) systems. The single-diode model (SDM), consisting of an ideal current source, an ideal diode, a shunt resistor and a series resistor, is widely used to simulate the behavior of PV cells/panels. In this article, a hybrid approach for identification of solar cell SDM parameters is presented. This approach uses the inverse of the slope of the I-V curve under short-circuit and open-circuit conditions and combines numerical and analytical solutions. Indeed, knowing that numerical methods require appropriate initial values, the main idea of the proposed approach is to provide these solutions by analytical methods. The comparison of obtained results with experimental ones, based on manufacturer’s datasheet, proves that the algorithm thus obtained requires less information from the manufacturer and improves significantly the parameter identification accuracy

Optimizing enzymatic dyeing of wool and leather

This work reports on the environmental friendly enzymatic dyeing of wool and leather performed at low temperature and mild pH conditions without any dyeing auxiliaries. The substrates have been dyed with “in situ” generated pigment by means of laccase-catalyzed oxidative coupling of dye modifier 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and dye precursor 1,3-benzenediol in a batchwise process. The process reaction variables (laccase, precursor and modifier concentrations, temperature and dyeing time) were optimized by response surface methodology using an appropriate experimental design. The temperature, precursor concentration, interaction between precursor and modifier and time are the most important factors in the dyeing process. The best-optimized wool dyeing conditions (2 h reaction time, 50 μl laccase (0.1 U), 500 mM precursor, 10 mM modifier at 40 °C) were then successfully applied onto leather material. The enzymatic-dyeing optimized process can be successfully performed on wool and leather at low temperature and mild pH obtaining different hues and depths of shades by varying the modifier concentration and time. The colouring enzymatic system has a good reusability (which has a huge advantage in terms of cost reduction) and washing durability and is comparable in terms of fastness properties to the traditional dyeing process for both wool and leather.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the project UID/CTM/00264/2019 and A. Zille contract IF/00071/2015

Ordered growth of nanodots on a pre-structured metallic template: Au/N/Cu(001)

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Reactivity of oxygen species formed upon N2O dissociation over Fe-ZSM-5 zeolite: CO oxidation as a model

International audienceThe oxidative power toward CO of α-oxygen formed upon N2O dissociation over isolated and binuclear Fe/ZSM-5 zeolite is investigated by means of DFT calculations. The two α-sites [Fe-O]+ and [Fe-(μO)-(μOH)-Fe]+ exchanged in ZSM-5 were considered since their activity in the N2O decomposition was recently shown. Computed electronic properties, charge transfers and frequency analysis of α-oxygen and iron in [O-Fe-O]+ and [OFe-(μO)-(μOH)-FeO]+ suggest a FeII character for the isolated and FeIV for the binuclear Fe-ZSM-5 sites. Addition of CO on oxygen atoms reveals that along the oxidation reaction the valence state for the isolated iron is II and remains relatively constant while a clear change from IV to II is calculated for the binuclear iron. According to DFT calculations CO addition on the α-oxygen from the iron active sites induces a significant length increase of the Fe-α-oxygen bond. Whatever the α-sites, the addition of CO is strongly exothermic and leads to stable minima resembling an adsorbed CO2 on iron active site. This reactivity is in line with the well known high reactivity of α-oxygen and the rapid CO2 formation at low temperatures. Based on the calculated enthalpy values, the adsorption of CO is slightly more favourable on binuclear [OFe-(μO)-(μOH)-FeO]+ than over isolated [O-Fe-O]+ iron site. A comparison of the entropic parameters suggests the opposite with a stronger oxidative power of α-oxygen from isolated over those from binuclear iron site