Weak and strong coupling theories for polarizable colloids and nanoparticles

A theory is presented which allows us to accurately calculate the density profile of monovalent and multivalent counterions in suspensions of polarizable colloids or nanoparticles. In the case of monovalent ions, we derive a weak-coupling theory that explicitly accounts for the ion-image interaction, leading to a modified Poisson-Boltzmann equation. For suspensions with multivalent counterions, a strong-coupling theory is used to calculate the density profile near the colloidal surface and a Poisson-Boltzmann equation with a renormalized boundary condition to account for the counterion distribution in the far field. All the results are compared with the Monte?Carlo simulations, showing an excellent agreement between the theory and the simulations.     

Doping radius effects on an erbium-doped fiber amplifier

In an erbium-doped fiber amplifier(EDFA), erbium ions act as a three-level system. Therefore, much higher pump energy is required to achieve the population inversion in an erbium-doped fiber(EDF). This higher pump energy requirement complicates the efficient design of an EDFA. However, efficient use of the pump power can improve the EDFA performance. The improved performance of an EDFA can be obtained by reducing the doping radius of the EDF. A smaller doping radius increases pump–dopant interactions and subsequently increases the pump–photon conversion efficiency. Decreasing the doping radius allows a larger proportion of dopant ions,which are concentrated near the core, to interact with the highest pump intensity. However, decreasing the doping radius beyond a certain limit will bring the dopant ions much closer and introduce detrimental ion–ion interaction effects. In this Letter, we show that an optimal doping radius in an EDF can provide the best gain performance. Moreover, we have simulated the well-known numerical aperture effects on EDFA gain performance to support our claim.     

Effects of polyvinylpyrrolidone on structural and optical properties of willemite semiconductor nanoparticles by polymer thermal treatment method

Journal of Thermal Analysis and Calorimetry - Willemite is an inorganic semiconductor material used for optoelectronic applications. The present study purposes a new polymer thermal treatment...     

Antioxidant activities and bioactive compounds of five Jalopeno peppers (Capsicum annuum) cultivars

The present study was designed to evaluate the contents of different antioxidants compounds and their antioxidant activities in Jalopeno peppers (Capsicum annuum) cultivars (El Dorido, Grande, Tula, Sayula and El Rey) extracts. Free radical scavenging activity of Grande was recorded as high as 87% followed by El Dorido (83%). Results of reducing power (Fe³⁺ to Fe²⁺) showed that Grande (0.85%) and El Dorido (0.81%) fruit extract absorbance value were close to synthetic antioxidant BHT (0. 97%) obtained at100 μg/mL. The results showed that total phenolic content of El Dorido and Grande were significantly higher compared to other Jalapeno pepper. Results indicated strong and positive correlation between antioxidant activity and carotenoids content (r = 0.75), vitamin C (r = 0.78) and total capsaicinoids (r = 0.84), respectively. The results of the antioxidant activity assays showed that the El Dorido and Grande had strongest antioxidant activity compared to other peppers cultivars in this study.     

Functional Nickel Oxide Nanostructures for Ethanol Oxidation in Alkaline Media

Nickel oxide (NiO) nanostructures are employed in the basic medium for the oxidation of ethanol. A variety of NiO nanostructures are synthesized by wet chemical growth method, using different hydroxide (OH^?) ion sources, particularly from ammonia, hexamethylenetetramine, urea and sodium hydroxide. The use of urea as (OH^?) ion source results in flower‐like NiO structures composed by extremely thin nanowalls (thickness lower than 10 nm,), which demonstrated to be the most active for ethanol oxidation. All the samples exhibit NiO cubic phase, and no other impurity was detected. The cyclic voltammetry (CV) curves of NiO nanostructures were found linear over the concentration range 0.1–3.5 mM (R²=0.99) of ethanol, with the limit of detection estimated to be 0.013 mM for ethanol. The NiO nanostructures exhibit a selective signal towards ethanol oxidation in the presence of different members of alcohol family. The proposed NiO nanostructures showed a significant practicality for the reproducible and sensitive determination of ethanol from brandy, whisky, mixture of brandy and rum, and vodka samples. The nanomaterial was used as a surface modifying agent for the glassy carbon electrode and it showed a stable electro‐oxidation activity for the ethanol for 16 days. These findings indicate that the presented NiO nanomaterial can be applied in place of noble metals for ethanol sensing and other environmental applications (like fuel cells).     

Techno-economic analysis of new integrated system of humid air turbine,organic Rankine cycle,and parabolic trough collector

Journal of Thermal Analysis and Calorimetry - Microgas turbines are one of the most well-known technologies for distributed generation. Unfortunately, their efficiency is not as high as it should...     

Synthesis,characterization, and biological investigation of new mixed-ligand complexes

A novel series of mixed-ligand complexes of 5,5′-{(1E,1E′)-1,4-phenelynebis(diazene-2,1-diyl)}bis(quinolin-8-ol) (H₂L₁) as a primary ligand and 4-aminoantipyrine(L₂) as a secondary ligand with Mn(II) ion were prepared using two general formulae: [Mn₂(H₂L₁)₂(L₂)₂X₄].4Cl (X = OH₂( 1 ), ONO₂⁻( 2 ), Cl=nil; OAc( 3 ), Cl = nil) and [Mn₂(H₂L₁)(L₂)₂(O₂SO₂)₂]( 4 ). Free ligands and their complexes were characterized. Electronic absorption spectra of the mixed-ligand complexes indicate a distorted octahedral geometry around the central metal ion, and the anions X⁻ are in the axial positions for all compounds. The ligands behave in a neutral bidentate manner, through nitrogen atoms and oxygen atoms of the carbonyl group (L₂), whereas H₂L₁ coordinated through nitrogen and OH groups as a neutral bidentate ligand. All complexes do not contain coordinated water molecules, but complex ( 1 ) contains four water molecules. The water molecules are removed in a single step. The complexes exhibited magnetic susceptibility corresponding to five unpaired electrons. The antimicrobial activity of the Mn(II) mixed-ligand complexes ( 1–4 ) against two gram-positive bacteria, three local gram-negative bacteria, and three fungi species was tested. Mn(II) mixed-ligand complex ( 2 ) exhibited significant antibacterial activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas sp. Mixed-ligand complex ( 2 ) exhibited a high potential cytotoxicity against the growth of human lung cancer cells.     

Studies of Hindered Rotation and Magnetic Anisotropy by 1H, 13C and 19F NMR. The Diels-Alder Adduct of N- Pentafluorophenylmaleimide and Phencyclone: A Model for Drugs.

The potent Diels-Alder diene, phencyclone, 1, reacts with N-pentafluorophenylmaleimide, 2, to form an adduct, 3, characterized by ¹H, ¹³C, and ¹⁹F NMR at 300, 75 and 282 MHz, respectively. The one-dimensional (1D) and two-dimensional (2D) ¹H and ¹³C NMR spectra of 3 at ambient temperatures imply a slow exchange limit (SEL) regime with respect to rotation of the unsubstituted bridgehead phenyl groups about severely hindered C(sp²)-C(sp³) bonds. Major non-bonded interactions are expected between the ortho protons of the C₆H₅ groups and H-1, 8 of the phenanthrenoid moiety of 3. ¹⁹F 1D and 2D (COSY) NMR spectra show that the SEL regime also obtains for rotation about the N-C₆F₅ bond of 3, with five separate fluorine signals seen, consistent with a preferred conformation in which the C₆F₅ may lie roughly perpendicular to the plane of the pyrrolidinedione moiety, and may be in the mirror symmetry plane of 3. The results are considered relevant to hindered aryl rotations in numerous Pharmaceuticals. Selected spectral data for 2 and precursors are also presented.     

On the numerical inversion of the Laplace transform by the use of an optimized Legendre polynomials

A method for inverting the Laplace transform is presented, using a finite series of the classical Legendre polynomials. The method recovers a real valued function f(t) in a finite interval of the positive real axis when f(t) belongs to a certain class and requires the knowledge of its Laplace transform F(s) only at a finite number of discrete points on the real axis s>0. The choice of these points will be carefully considered so as to improve the approximation error as well as to minimize the number of steps needed in the evaluations. The method is tested on few examples, with particular emphasis on the estimation of the error bounds involved.     

A neural network to solve quadratic programming problems with fuzzy parameters

In this paper, a representation of a recurrent neural network to solve quadratic programming problems with fuzzy parameters (FQP) is given. The motivation of the paper is to design a new effective one-layer structure neural network model for solving the FQP. As far as we know, there is not a study for the neural network on the FQP. Here, we change the FQP to a bi-objective problem. Furthermore, the bi-objective problem is reduced to a weighting problem and then the Lagrangian dual is constructed. In addition, we consider a neural network model to solve the FQP. Finally, some illustrative examples are given to show the effectiveness of our proposed approach.