Synthesis,structure and optical properties of x(CuO)/(1−x)Ni(OH)2 [x=0, 0.1 and 0.3] nanocomposites

The x(CuO)/(1−x)Ni(OH)₂ [x=0, 0.1 and 0.3] nanocomposites were prepared by the hydrothermal method in the presence of the surfactant polyethylenglycol-10000 (PEG-10000). X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the as-prepared samples. The increase of the CuO content led to the increase of the crystallite size of both, the β-Ni(OH)₂ and the CuO. The increase in the crystallite size greatly affects the band gap energy of the as-prepared nanocomposites. The band gap energies of the x(CuO)/(1−x)Ni(OH)₂ nanocomposites were estimated by UV–vis spectroscopic method. UV–vis spectroscopic results showed an apparent decrease in the direct band gap energies. The x(CuO)/(1−x)Ni(OH)₂ [x=0, 0.1 and 0.3] nanocomposites show low band gap energies compared to the Ni(OH)₂ bulk materials. The enhanced optical properties lead to their possible use in photocatalytic and photovoltaic applications.     

Two-degree-of-freedom robust speed controller for high-performancerolling mill drives

A scheme is presented for the speed control of rolling mill drives. The proposed speed controller is based on a two-degree-of-freedom (TDF) structure and uses an observer-based state feedback compensator for the major control loop. The control method yields a robust system with respect to system uncertainties and modeling errors and is very effective for vibration suppression. Experimental verification was carried out on a prototype rolling mill minimodel system. The experimental drive system has a three-mass-model structure (motor-gear-load) connected by low stiffness shafts. The mechanical resonances and the inertia ratios between the motor, gear, and load are comparable to those of an actual rolling mill system (resonant frequencies are at 17.4 Hz and 51.3 Hz). The proposed scheme was compared to the conventional PI controller and the performance of each scheme is presented. A high closed loop speed bandwidth was obtained with the proposed TDF speed controller     

Solid effects on hydrodynamics and heat transfer in an external loop airlift reactor

The effect of a solid presence on global hydrodynamic parameters and heat transfer in an external loop airlift reactor has been experimentally investigated. Results obtained in both two- and three-phase flow are presented in this study. Two different external loop airlift reactor sizes have been used and local hydrodynamic characteristics including local gas hold-up and bubble velocity have been obtained in two-phase flow. Optical and ultrasound probes have been used to obtain this information, respectively. It was found that an increase of solid hold-up leads to a decrease of liquid velocity and heat transfer coefficient. Measured in a two- and three-phase reactor using a horizontal-heating probe, a correlation of the average gas hold-up and heat transfer coefficient is proposed. Correlation parameters are identified in homogeneous and heterogeneous flow regimes, which have been derived from the gas slip velocity concept. The experimental liquid velocity and gas hold-up in the riser have been represented in a satisfactory way by a hydrodynamic model, either in the absence or in the presence of solid particles.     

Sucrose supplementation during traditional carob syrup processing affected its chemical characteristics and biological activities

The addition of sucrose is optional during carob syrups traditional processing. In this work, the polyphenolic profiles of carob syrups supplemented (CSS) or not with sugar (CS) were analyzed using RP-HPLC–ESI-MS. Quantitative data showed that adding of sucrose significantly (p < 0.05) decreased the polyphenolic amounts of about 58.6%, from 4.5 ± 0.32 to 1.86 ± 0.26 mg/g of CS and CSS, respectively. Gallic acid was the most abundant compound in both syrups representing 60.93% (CS) and 69.26% (CSS) of the total phenolics. Moreover, the adding of sugar decreased (p < 0.05) the antiradical potentials of 28% and 74%, as determined, respectively, by the ABTS and DPPH assays. CS was found to exhibit stronger antibacterial and antifungal activities than CSS. Bacillus cereus was the most sensitive strain to the extracts with CMI ≈500 (CS) and 622 (CSS) μg/ml. Both syrup extracts were cytotoxic to human neuroblastoma (SH-SY5Y) and fibroblast (3T3) cell lines as well as to mouse embryonic stem cells (D3). Tumoral SH-SY5Y cells were the most susceptible to the extracts with IC50 = 311.7 ± 23.65 (CS) and 390.6 ± 34.97 μg/ml (CSS). This study provides, for the first time, new analytical insights into traditionally made carob syrups and highlights the negative effect of sugar supplementation during processing.     

Synthesis and Electrical Properties of Well-Ordered Layered α-MoO3 Nanosheets

Nano-Micro Letters - α-MoO3 ordered nanosheets have been synthesized under hydrothermal conditions using commercial MoO3 and hydroquinone as structuring agent. X-ray diffraction (XRD),...     

Using IoT and smart monitoring devices to optimize the efficiency of large-scale distributed solar farms

Wireless Networks - This paper presents a novel IoT-based architecture that utilizes IoT hardware, software, and communication technologies to enable real-time monitoring and management of solar...     

Analysis of current-regulated voltage-source inverters forpermanent magnet synchronous motor drives in normal and extended speedranges

For a high-performance PMSM (permanent magnet synchronous motor) drive, appropriate choice of the power converter and of the controller is achieved using computer simulation of the drive system. The generation of a smooth torque at low speeds and the system operating limits in the high and extended-speed ranges are investigated. A numerical simulation of the drive is used to study various control strategies. Simulation results for ramp, hysteresis, and space-vector-type current controllers are presented to illustrate important performance characteristics of each. The nature of current regulator saturation is described and a flux weakening algorithm is discussed in order to achieve extended torque-speed characteristics above the rated speed     

Polyphenolic Extract of Barbary-Fig (Opuntia ficus-indica) Syrup: RP–HPLC–ESI–MS Analysis and Determination of Antioxidant, Antimicrobial and Cancer-Cells Cytotoxic Potentials

The traditionally derived syrup of Opuntia ficus-indica fruit is commonly used in homemade confectionery. Herein, the aqueous-acetone extract prepared from the Tunisian O. ficus-indica syrup was investigated. The qualitatively and quantitatively polyphenolic content was analysed using reversed-phase high-performance liquid chromatography–diode array detection (RP-HPLC–DAD) coupled to electrospray ionisation–mass spectrometry (ESI–MS). The extract contained 19.95?±?2.01 mg phenolics per gram of fresh starting material with isorhamnetin 3-O-robinobioside as the major compound (22.76%). The syrup extract showed strong antioxidant potentials as assessed by both ABTS and DPPH functional methods. It exhibited effective antimicrobial activity, particularly against Staphylococcus aureus and Staphylococcus epidermidis with a minimal bactericide concentration (MBC) of 1.3 mg phenolics/ml. Furthermore, at final concentrations in the range of 41.38–186.25 μg polyphenols/ml, the extract decreased human SH-SY5Y neuroblastoma and 3T3 fibroblast in vitro cell viability in a dose- and time-dependent manner compared to non-treated control cells. The observed effects were significantly (P?<?0.05) high against cancer lines. Extract concentrations higher than 106.43 μg/ml reduced cancer cells viability to 50–60% 1–3 h post-treatment. Further in vivo insight studies should emphasise and validate the herein obtained results.     

Vat dye sorption onto crude dehydrated sewage sludge

In this work, sewage sludge is used as a textile dye adsorbent. A sample of crude dehydrated sewage sludge issued from an urban wastewater treatment plant (high-rate aeration, activated sludge process, Sahline, Tunisia) is utilized for vat dye retention. The main objective of this work is to evaluate the "efficiency" of the crude material on vat dye sorption. However, no treatment to modify any of the adsorbent properties was considered. Although the relatively low specific surface area (about 3.2m(2)g(-1)) compared to more conventional adsorbents, the used material shows very interesting retention capacities when used with water pollutants. The pseudo, first and second order kinetic models have been used to investigate the retention mechanism. When linearized, the pseudo-second order fit, for the both used dyes, in a better way the obtained experimental results than the pseudo-first order kinetic model. For equilibrium dye uptake amount it is found that the used material has a capacity (Langmuir Freundlich monolayer) of 73.1mg/g to fix the VAT RED 10 and 58.7 mg/g to fix the VAT ORANGE 11.     

Crystal structure and spectroscopic investigations of an organic monophosphate

Single crystals of (p-ClC₆H₄NH₃)H₂PO₄ are synthesized in water by interaction of H₃PO₄ and (p-ClC₆H₄NH₂). This compound crystallizes in the orthorhombic system with the Pbca space group. Its unit-cell parameters are a = 9.724(3), b = 7.861(1), c = 25.078(6) Å, V = 1917.1(6) Å³ and Z = 8. The crystal structure has been solved and refined to R = 0.039, using 4298 independent reflections. The atomic arrangement can be described by inorganic layers parallel to ab plane, between which the organic cations are located. This compound exhibits a reversible phase transition at 403 K. The electrical conductivity measurements show that the (p-ClC₆H₄NH₃)H₂PO₄ has a conductivity value which goes from σ = 0.88 × 10⁻⁶ Ω⁻¹ cm⁻¹ at room temperature (293 K) to 3.31 × 10⁻⁴ Ω⁻¹ cm⁻¹ at 433 K. Its characterisation by TA, NMR and IR is reported too.