Development and Characterization of Curcumin-Silver Nanoparticles as a Promising Formulation to Test on Human Pterygium-Derived Keratinocytes

Pterygium is a progressive disease of the human eye arising from sub-conjunctival tissue and extending onto the cornea. Due to its invasive growth, pterygium can reach the pupil compromising visual function. Currently available medical treatments have limited success in suppressing efficiently the disease. Previous studies have demonstrated that curcumin, polyphenol isolated from the rhizome of Curcuma longa, induces apoptosis of human pterygium fibroblasts in a dose- and time-dependent manner showing promising activity in the treatment of this ophthalmic disease. However, this molecule is not very soluble in water in either neutral or acidic pH and is only slightly more soluble in alkaline conditions, while its dissolving in organic solvents drastically reduces its potential use for biomedical applications. A nanoformulation of curcumin stabilized silver nanoparticles (Cur-AgNPs) seems an effective strategy to increase the bioavailability of curcumin without inducing toxic effects. In fact, silver nitrates have been used safely for the treatment of many ophthalmic conditions and diseases for a long time and the concentration of AgNPs in this formulation is quite low. The synthesis of this new compound was achieved through a modified Bettini’s method adapted to improve the quality of the product intended for human use. Indeed, the pH of the reaction was changed to 9, the temperature of the reaction was increased from 90 °C to 100 °C and after the synthesis the Cur-AgNPs were dispersed in Borax buffer using a dialysis step to improve the biocompatibility of the formulation. This new compound will be able to deliver both components (curcumin and silver) at the same time to the affected tissue, representing an alternative and a more sophisticated strategy for the treatment of human pterygium. Further in vitro and in vivo assays will be required to validate this formulation.     

Human capital estimation in higher education

The concept of human capital (HC) could be defined, from an economical viewpoint, as a stock variable representing the capacity of an individual to produce a sustained flow of income due to its investment in (higher) education and work experience. This paper focuses on the empirical estimation of the graduates’ latent variable HC, composed of two principal dimensions, Educational HC and Work Experience HC, within a realistic structural model, allowing causal relationship among endogenous and exogenous indicators, taking into account possible effects of external covariates. New administrative archives and a novel methodological approach are used. The methodology is applied to estimate HC of graduates in several universities of the Milan area in the early stages of their working career. The empirical results confirm the structure of the Italian job market, where investment in HC through higher education plays only a marginal role for explaining the economic performance.     

Further Remarks on the Luo–Hou’s Ansatz for a Self-similar Solution to the 3D Euler Equations

It is shown that the self-similar ansatz proposed by T. Hou and G. Luo to describe a singular solution of the 3D axisymmetric Euler equations leads, without assuming any asymptotic condition on the self-similar profiles, to an overdetermined system of partial differential equations that produces two families of solutions: a class of trivial solutions in which the vorticity field is identically zero, and a family of solutions that blow-up immediately, where the vorticity field is governed by a stationary regime. In any case, the analytical properties of these solutions are not consistent with the numerical observations reported by T. Hou and G. Luo. Therefore, this result is a refinement of the previous work published by D. Chae and T.-P. Tsai on this matter, where the authors found the trivial class of solutions under a certain decay condition of the blow-up profiles.     

Spatial and temporal plasma inhomogeneity effects on the luminescence of highly excited GaAs/AlGaAs multiple quantum well structures

Summary The effects on the luminescence lineshape of the spatial and temporal inhomogeneities of the electron-hole plasma generated by strong laser pulses in GaAs/AlGaAs multiple quantum well structures are experimentally investigated. It is found that inhomogeneities strongly affect the luminescence spectra and must be taken into account for a correct interpretation of the experimental data. The lineshape of the luminescence spectra is analysed using a statistical model that includes, in a simple way, the spatial and temporal inhomogeneities of the laser pulses used for excitation. A fair agreement is obtained with the experimental data; at the same time the values of the fit parameters turn out to be rather sensitive to the model assumed for describing the inhomogeneities. Therefore, caution has to be used when inferring plasma properties, such as the carrier density and temperature, from a lineshape analysis.

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Riassunto Si presenta, in questo lavoro, uno studio sperimentale degli effetti delle disomogeneità spaziali e temporali nei plasmi di elettroni e lacune generati da impulsi laser potenti in strutture a buche quantiche di GaAs/AlGaAs. Si trova che tali disomogeneità modificano fortemente gli spettri di fotoluminescenza e devono quindi essere considerate per una corretta interpretazione dei dati sperimentali. La forma di riga degli spettri di luminescenza viene analizzata mediante un modello statistico che include, in modo semplice, le disomogeneità spaziali e temporali degli impulsi laser usati per l’eccitazione. Si ottiene un accordo soddisfacente con i dati sperimentali e si trova che i valori dei parametri ottenuti dal fit dipendono in modo sensibile dal modello assunto per la descrizione delle disomogeneità. Grande cautela deve essere quindi usata nel dedurre le proprietà del plasma fotogenerato a partire da una analisi delle forme di riga.

     

O(3P)+1，2-丁二烯反应的交叉分子束和理论研究：丙烯+CO和亚乙基+乙烯酮反应的主要分子通道

详细了解O(~3P)与不饱和烃的多通道燃烧反应机理需要鉴定所有主要反应产物、确定分支比、评估三重态与单重态势能面之间的系间窜跃.将交叉分子束实验、软电离、质谱、飞行时间分析,以及高级从头算计算三重态/单线态势能面,RRKM/Master方程计算支化比包括系间窜跃,均可以获得最佳效果.最近已经证明这些方法对于含有两个或三个碳原子的最简单的不饱和烃(炔烃,烯烃,二烯)和O(~3P)反应是成功的.本文通过交叉分子束与理论相结合的方法研究O(~3P)和含有四个C原子的二烯类化合物,1,2-丁二烯(甲基芳烃)的反应,探索产物分布、分支比和系间窜跃如何随着分子复杂性的增加而变化,即从O(~3P)和丙二烯反应到O(~3P)1,2-丁二烯的反应变化.尤其关注了最重要的导致链终止的主导分子通道(即形成丙烯+CO(分支≥0.5)和亚乙基+乙烯酮(分支比≥0.15))与导致链传递的自由基形成通道进行对比(分支比≥0.35).     

Bad behavior of Godunov mixed methods for strongly anisotropic advection–dispersion equations

We study the performance of Godunov mixed methods, which combine a mixed-hybrid finite element solver and a Godunov-like shock-capturing solver, for the numerical treatment of the advection–dispersion equation with strong anisotropic tensor coefficients. It turns out that a mesh locking phenomenon may cause ill-conditioning and reduce the accuracy of the numerical approximation especially on coarse meshes. This problem may be partially alleviated by substituting the mixed-hybrid finite element solver used in the discretization of the dispersive (diffusive) term with a linear Galerkin finite element solver, which does not display such a strong ill conditioning. To illustrate the different mechanisms that come into play, we investigate the spectral properties of such numerical discretizations when applied to a strongly anisotropic diffusive term on a small regular mesh. A thorough comparison of the stiffness matrix eigenvalues reveals that the accuracy loss of the Godunov mixed method is a structural feature of the mixed-hybrid method. In fact, the varied response of the two methods is due to the different way the smallest and largest eigenvalues of the dispersion (diffusion) tensor influence the diagonal and off-diagonal terms of the final stiffness matrix. One and two dimensional test cases support our findings.