Identification and quantitation of pathogenic bacteria via in-situ formation of silver nanoparticles on cell walls,and their detection via SERS

Microchimica Acta - The authors present a fast and sensitive surface-enhanced Raman spectroscopy (SERS) method for the determination of Mycobacterium smegmatis. It is based on the formation of...     

Results on Nonlocal Boundary Value Problems

In this article, we provide a variational theory for nonlocal problems where nonlocality arises due to the interaction in a given horizon. With this theory, we prove well-posedness results for the weak formulation of nonlocal boundary value problems with Dirichlet, Neumann, and mixed boundary conditions for a class of kernel functions. The motivating application for nonlocal boundary value problems is the scalar stationary peridynamics equation of motion. The well-posedness results support practical kernel functions used in the peridynamics setting.

We also prove a spectral equivalence estimate which leads to a mesh size independent upper bound for the condition number of an underlying discretized operator. This is a fundamental conditioning result that would guide preconditioner construction for nonlocal problems. The estimate is a consequence of a nonlocal Poincaré-type inequality that reveals a horizon size quantification. We provide an example that establishes the sharpness of the upper bound in the spectral equivalence.     

Weighted and regularity estimates for nonlinear equations on Reifenberg flat domains

Global weighted Lp estimates are obtained for the gradient of solutions to nonlinear elliptic Dirichlet boundary value problems over a bounded nonsmooth domain. Morrey and Hölder regularity of solutions are also established, as a consequence. These results generalize various existing estimates for nonlinear equations. The nonlinearities are of at most linear growth and assumed to have a uniform small mean oscillation. The boundary of the domain, on the other hand, may exhibit roughness but assumed to be sufficiently flat in the sense of Reifenberg. Our approach uses maximal function estimates and Vitali covering lemma, and also known regularity results of solutions to nonlinear homogeneous equations.     

基于第一性原理研究铱(111)和(100)表面的原子吸附（英文）

本文利用第一性原理密度泛函理论研究了九种不同的吸附原子在铱(Ir)的(111)和(100)表面上的吸附性质.探讨了Ir表面的功能化,因此吸附能、稳定的结构、态密度和磁矩,这将为进一步研究其在催化和其他表面应用中的可能展现的功能提供重要信息.研究表明,三/四重空位点是Ir(111)/(100)表面最有利的吸附位点.通过对大范围的覆盖率(从0.04到1个单层)的研究,表明吸附原子的吸附能具有很强的覆盖率依赖性.吸附能随着覆盖率的增加而增加,这意味着吸附物之间存在排斥相互作用.吸附原子和衬底电子态之间的强杂化会影响吸附性质,同时吸附原子的磁矩被抑制.通过Bader电荷分析,揭示了吸附原子和衬底之间的大量电荷转移.与(111)表面的结合相比,(100)表面吸附原子的结合更强.     

Direct approach to the problem of strong local minima in calculus of variations

Let (M,g) be a two-dimensional compact Riemannian manifold. In this paper, we use the method of blowing up analysis to prove several Moser–Trudinger type inequalities for vector bundle over (M,g). We also derive an upper bound of such inequalities under the assumption that blowing up occurs. The research of the second author was partially supported by NSFC grant and the Foundation of Shanghai for Priority Academic Discipline.     

Simultaneous determination of N-acetyl-p-aminophenol and p-aminophenol with poly(3,4-ethylenedioxythiophene) modified glassy carbon electrode

A sensitive and selective method was developed for the determination of N-acetyl-p-aminophenol (APAP) and p-aminophenol (PAP) using poly(3,4-ethylenedioxythiophene) (PEDOT)-modified glassy carbon electrode (GCE). Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical reaction of APAP and PAP at the modified electrode. Both APAP and PAP showed quasireversible redox reactions with formal potentials of 367 mV and 101 mV (vs. Ag/AgCl), respectively, in phosphate buffer solution of pH 7.0. The significant peak potential difference (266 mV) between APAP and PAP enabled the simultaneous determination both species based on differential pulse voltammetry. The voltammetric responses gave linear ranges of 1.0 × 10⁻⁶-1.0 × 10⁻⁴ mol L⁻¹ and 4.0 × 10⁻⁶-3.2 × 10⁻⁴ mol L⁻¹, with detection limits of 4.0 × 10⁻⁷ mol L⁻¹ and 1.2 × 10⁻⁶ mol L⁻¹ for APAP and PAP, respectively. The method was successfully applied for the determination of APAP and PAP in pharmaceutical formulations and biological samples.     

Nonlocal Constrained Value Problems for a Linear Peridynamic Navier Equation

In this paper, we carry out further mathematical studies of nonlocal constrained value problems for a peridynamic Navier equation derived from linear state-based peridynamic models. Given the nonlocal interactions effected in the model, constraints on the solution over a volume of nonzero measure are natural conditions to impose. We generalize previous well-posedness results that were formulated for very special kernels of nonlocal interactions. We also give a more rigorous treatment to the convergence of solutions to nonlocal peridynamic models to the solution of the conventional Navier equation of linear elasticity as the horizon parameter goes to zero. The results are valid for arbitrary Poisson ratio, which is a characteristic of the state-based peridynamic model.     

Iron-based nanoparticles in wastewater treatment: A review on synthesis methods,applications, and removal mechanisms

Nanomaterial is an emerging material with potential technological impacts in various applications. It imposes great opportunities in various disciplines including wastewater remediation. Industrial wastewater is generated with anthropogenic activities and is the most environmental threat that needs remediation to overcome the environmental damages, thereby reducing human risks. Currently, several wastewater treatment techniques are applied and the utilization of nanomaterials for pollutant removal is an emerging technology. This is evident that the publication trends in the field of iron-based wastewater have been drastically increased. In this work, the overview of the preparation of iron-based nanoparticles, such as different polymorphs of iron-oxides, oxyhydroxides, iron hydroxide, and zero-valent iron nanoparticles are reviewed. In addition to the detailed discussion on the preparation of iron-based nanoparticles, their application on waste water treatment, removal mechanisms, advantages, and limitations are also assessed and discussed. Moreover, the iron-based nanoparticles' removal efficiency for specific pollutants and perspective in environmental remediation are also analyzed. Additionally, the advancements and future perspectives of iron-based nanoparticles are highlighted.