Ultrasonic treatment on activated sewage sludge from petro-plant for reduction

In this essay, the influences of low frequency ultrasound (20 kHz) on dewater ability and anaerobic digestion behaviors of activated sewage sludge, obtained from Yangzi Water Treatment Plant, Yangzi Petrochemical Corporation, were discussed. Ultrasound pretreatment could enhance the filtration progress and decrease the moisture content of the sludge from 99% to 80%. Together with flocculant, the ultrasound pretreatment decreased the specific filtration resistance (SFR) of the sludge from 3.59 x 10(12) m/kg to 1.18 x 10(12) m/kg and saved about 25-50% of the flocculant dosage. Bound water of the sludge was measured by dilatometer. After 2-4 min treatment of ultrasound under intensity of 400 W/m(2), the bound water of sludge decreased from 16.7 g/g (dry base) to above 2.0 g/g (dry base). Ultrasound pretreatment could also enhance digestion and reduce digestion time. To the same resolution ratio, such as 49%, the digestion time of sludge with ultrasound pretreatment was 7 days less than that without ultrasound. Proper ultrasound pretreatment could also improve the dewater ability of the digested sludge, the final moisture of which was 73.7%.     

Preparation of a novel ferrofluidic photoresist for two-photon photopolymerization technique

We present a novel route for the preparation of ferrofluidic photoresist compatible with two-photon photopolymerization (TPP). To get a homogeneous ferrofluidic photoresit, the compatibility of photoresist and magnetic materials has been improved. Monodispersed Fe₃O₄ nanoparticles synthesized via thermal decomposition of iron precursor were stabilized by 6-(methacryloyloxy) hexanoic acid (a kind of acrylate-based monomer). A ferrofluidic photoresist was prepared by doping the modified Fe₃O₄ nanoparticles in acrylate-based resin. In this way, the dispersibility of nanoparticles in photoresist was enhanced significantly. As a representative example, a precise magnetic micron-sized spring was created. In the test of the magnetic response, the sensitivity of magnetic microspring was improved remarkably due to the optimization of the ferrofluidic photoresist. When the intensity of external magnetic field reached a value of 1500 Gs, the deformation rate of the microspring would get to 2.25, indicating the compatibility of the ferrofluidic photoresist in microfabrication.     

Suppression of superconductivity in layered Bi<Subscript>4</Subscript>O<Subscript>4</Subscript>S<Subscript>3</Subscript> by Ag doping

We report X-ray diffraction, magnetization and transport measurements for polycrystalline samples of the new layered superconductor Bi_4?x Ag _x O₄S₃(0 ≤ x ≤ 0.2). The superconducting transition temperature (T _C) decreases gradually and finally suppressed when x < 0.10. Accordingly, the resistivity changes from a metallic behavior for x < 0.1 to a semiconductor-like behavior for x > 0.1. The analysis of Seebeck coefficient shows there are two types of electron-like carriers dominate at different temperature regions, indicative of a multiband effect responsible for the transport properties. The suppression of superconductivity and the increased resistivity can be attributed to a shift of the Fermi level to the lower-energy side upon doping, which reduces the density of states at E _F. Further, our result indicates the superconductivity in Bi₄O₄S₃ is intrinsic and the dopant Ag prefers to enter the BiS₂ layers, which may essentially modify the electronic structure.     

Hydrothermal-assisted ion exchange synthesis and photoluminescence of Li+ and Eu3+ co-doped NaLa(WO4)2 as near-UV type red phosphors

A series of Li⁺ and Eu³⁺ co-doped double tungstate NaLa(WO₄)₂ (NLW) red phosphors have been successfully synthesized by an ion exchange method under a hydrothermal condition. The effects of Li⁺ doping concentration on the crystal structure, morphology and photoluminescence properties were investigated using the XRD, TEM and photoluminescence (PL) measurements. The results reveal that the samples have phase-pure scheelite structure and adopt spherical particle morphology. Furthermore, room temperature PL spectrum shows that the optical brightness is highly dependent on the concentration of doping Li⁺, which is determined by ion exchange duration and the precursor concentration of LiNO₃. As 5% Li⁺ ions was introduced into the crystal lattice, the emission intensity was enhanced by more than 10-fold as compared with the pristine one. Moreover, the co-doping of Li⁺ can substantially improve the effective excitation of the NaLa(WO₄)₂:Eu³⁺ phosphors under near-UV region.     

Theoretical study on the phase stability,elasticity, hardness and electronic structures of Ni–P compounds

A systematic investigation concerned with phase stability, elastic properties, hardness and relevant electronic structure of Ni–P compounds (Ni₃P, Ni₁₂P₅, Ni₂P, Ni₅P₄, NiP, NiP₂ and NiP₃) was carried out using first principles calculations. The calculated results show that the Ni–P compounds have strong hardness, ranging from 7.80–14.54 GPa. Also, the hardness values gradually increase with the P content. Electronic structure analysis shows that the strong Ni–P and part of P–P hybrid orbitals play important roles in the hardness of these compounds. The calculated elastic constants indicated that the Ni₃P, Ni₁₂P₅ and NiP₂ phases are significantly anisotropic, the NiP and Ni₂P exhibit some anisotropy, while the Ni₅P₄ and NiP₃ show a relatively isotropic character. At last, the properties of these Ni–P compounds including lattice constants, thermodynamic stability, elastic constants C_ij, bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν have been calculated.     

Robust improvement schemes for road networks under demand uncertainty

This paper is concerned with development of improvement schemes for road networks under future travel demand uncertainty. Three optimization models, sensitivity-based, scenario-based and min–max, are proposed for determining robust optimal improvement schemes that make system performance insensitive to realizations of uncertain demands or allow the system to perform better against the worst-case demand scenario. Numerical examples and simulation tests are presented to demonstrate and validate the proposed models.     

Optimized local basis set for Kohn–Sham density functional theory

We develop a technique for generating a set of optimized local basis functions to solve models in the Kohn–Sham density functional theory for both insulating and metallic systems. The optimized local basis functions are obtained by solving a minimization problem in an admissible set determined by a large number of primitive basis functions. Using the optimized local basis set, the electron energy and the atomic force can be calculated accurately with a small number of basis functions. The Pulay force is systematically controlled and is not required to be calculated, which makes the optimized local basis set an ideal tool for ab initio molecular dynamics and structure optimization. We also propose a preconditioned Newton–GMRES method to obtain the optimized local basis functions in practice. The optimized local basis set is able to achieve high accuracy with a small number of basis functions per atom when applied to a one dimensional model problem.     

Nanoplasmonic directional couplers and Mach–Zehnder interferometers

We present a novel design and analysis of two nano-scale plasmonic devices: a directional coupler and a Mach–Zehnder interferometer. The designs of the two devices are based on our recent work on the air-gap coupler that resulted in high coupling efficiency between a dielectric waveguide and a plasmonic waveguide. The two devices are embedded between two dielectric waveguides and operate at optical telecom wavelengths. The overall efficiency was 37% for a 2×2 directional coupler switch and above 50% for the proposed designs for a Mach–Zehnder Interferometer. The efficiency in the proposed devices can be increased using broader plasmonic waveguides.     

Existence and fractional regularity of solutions for a doubly nonlinear differential inclusion

This article considers the issues of existence and regularity of solutions to the following doubly nonlinear differential inclusion $$\omega_t+\alpha (\omega_t)-\Delta \omega-\Delta_p{\omega} \ni f$$ where α is a maximal monotone operator in ${\mathbb{R}^2}$ and Δ _p denotes the p-Laplacian with p > 2. The investigation on fractional regularity is based on the Galerkin method combined with a suitable basis for W ^1,p , which we exhibit as a preliminary result. This approach also allows the obtaining of estimates in the so-called Nikolskii spaces, since it balances the interplay between the maximal monotone operator with the appearing higher order nonlinear terms.     

Broadening of Cr nanostructures in laser-focused atomic deposition

This paper presents the experimental progress of laser-focused Cr atomic deposition and the experimental condition.The result is an accurate array of lines with a periodicity of 212.8±0.2 nm and mean full-width at half maximum as approximately 95 nm.Surface growth in laser-focused Cr atomic deposition is modeled and studied by kinetic Monte Carlo simulation including two events:the one is that atom trajectories in laser standing wave are simulated with the semiclassical equations of motion to obtain the deposition position;the other is that adatom diffuses by considering two major diffusion processes,namely,terrace diffusion and step-edge descending.Comparing with experimental results(Anderson W R,Bradley C C,McClelland J J and Celotta R J 1999 Phys.Rev.A 59 2476),it finds that the simulated trend of dependence on feature width is in agreement with the power of standing wave,the other two simulated trends are the same in the initial stage.These results demonstrate that some surface diffusion processes play important role in feature width broadening.Numerical result also shows that high incoming beam flux of atoms deposited redounds to decrease the distance between adatoms which can diffuse to minimize the feature width and enhance the contrast.