S-band depressed-cladding erbium-doped fiber amplifier with double-pass configuration

A new S-band erbium-doped fiber amplifier module with a double-pass configuration based on two circulators has been designed and constructed. The bending losses of a depressed-cladding doped fiber have been exploited to suppress the amplified spontaneous emission in the C band. The experimental characterization of the double-pass amplifier has shown that significant advantages can be obtained with respect to the single-pass configuration.     

Early raise of BDNF in hippocampus suggests induction of posttranscriptional mechanisms by antidepressants

Background  

The neurotrophin BDNF has been implicated in the regulation of neuroplasticity, gene expression, and synaptic function in the adult brain, as well as in the pathophysiology of neuropsychiatric disorders and the mechanism of action of antidepressants. Antidepressant treatments have been shown to increase the expression of BDNF mRNA, although the changes measured were found to be different depending on various factors. A few studies only have measured levels of BDNF protein after antidepressant treatments, and poor correlation was found between mRNA and protein changes. We studied the time course of expression of BDNF mRNA and protein during drug treatments, in order to elucidate the temporal profile of regulation of this effector and whether mRNA and protein levels correlate. Rat groups were treated for 1, 2 or 3 weeks with fluoxetine or reboxetine; in additional groups drug treatment was followed by a washout week (3+1). Total BDNF mRNA was measured by Real Time PCR, pro- and mature BDNF proteins were measured by Western blot.     

Iron doping of lithium niobate by thermal diffusion from thin film: study of the treatment effect

Thermal diffusion from thin film is one of the most widespread approaches to prepare iron doped regions in lithium niobate with limited size for photorefractive applications. In this work, we investigate the doping process with the aim of determining the best process conditions giving a doped region with the characteristics required for photorefractive applications. Six samples were prepared by changing the atmosphere employed in the diffusion treatment in order to obtain different combination of diffusion profiles and reduction degrees and also to check the effect of employing a wet atmosphere. The compositional, optical, and structural properties are then extensively characterized by combining Secondary ion Mass Spectrometry, UV, visible and IR spectrophotometry, High Resolution X-Rays Diffraction, and Micro-Raman Spectroscopy. Moreover, the sample topography was checked by Atomic Force Microscopy. An analysis of all our data shows that the best results are obtained performing a double step process, i.e. diffusion in oxidizing atmosphere and subsequent reduction at lower temperature in an hydrogen-containing atmosphere.     

A comparison of numerical integration rules for the meshless local Petrov–Galerkin method

The meshless local Petrov–Galerkin (MLPG) method is a mesh-free procedure for solving partial differential equations. However, the benefit in avoiding the mesh construction and refinement is counterbalanced by the use of complicated non polynomial shape functions with subsequent difficulties, and a potentially large cost, when implementing numerical integration schemes. In this paper we describe and compare some numerical quadrature rules with the aim at preserving the MLPG solution accuracy and at the same time reducing its computational cost.     

On the Höpf boundary lemma for singular semilinear elliptic equations

In this paper we consider positive solutions to semilinear elliptic problems with singular nonlinearity. We provide a Höpf type boundary lemma via a suitable scaling argument that allows to deal with the lack of regularity of the solutions up to the boundary.     

The relationships between phenolic content, pollen diversity, physicochemical information and radical scavenging activity in honey

Honey is rich in different secondary plant metabolites acting as natural antioxidants and contributing to human health. Radical scavenging activity (RSA) is related to antioxidant activity, while the correlation between the phenolic content and RSA is often weak. Consequently, exclusive information on phenolics is often insufficient to qualify the RSA and the health promoting effects of honey. The paper deals with a case study of honey samples originating from the alpine areas of Italy's Lombardia and Veneto regions and realized by standard physicochemical and statistical analytical methods. In pure honey, the total phenolic content and the RSA were measured in spectrophotometric tests with the 2,2-diphenyl-1-picrylhydrazyl (DPPH·) free radical and Folin-Ciocalteu assays, respectively. Melissopalynological data was used to qualify pollen diversity through rank-frequency curves separating the samples into two groups. On the basis of physicochemical data, the samples were analyzed through multivariate classification and ranking procedures resulting in the identification of an outlier. Elimination of the outlier produced a high correlation between the total phenolic content and RSA in the two pollen diversity groups. The case study suggests that, after disregarding outliers, the RSA activity can be satisfactorily qualified on the basis of phenolics with pollen diversity as a covariate.     

Solid-phase synthesis of arginine-based double-tailed cationic lipopeptides: potent nucleic acid carriers

Herein we report a highly-efficient solid-phase strategy for the modular synthesis of 63 double-tailed lipid-peptide conjugates and their application in DNA delivery.     

Atom Economic and Highly Syn‐selective Prolinamide‐Catalyzed Cross‐aldol Addition of Hydroxyacetone to Aromatic Aldehydes

The highly selective cross‐aldol addition of hydroxyacetone (HA) to p‐nitro and m‐nitrobenzaldehyde is reported; the reaction is catalyzed by three different di‐ or tripeptides all containing D‐Pro in the N‐terminal position and one or two residues of β³‐homophenylglycine (β³‐hPhg): H‐D‐Pro‐(R)‐β³‐hPhg‐OBn, H‐D‐Pro‐(R)‐β³‐hPhg‐(S)‐β³‐hPhg‐OBn and H‐D‐Pro‐[(S)‐β³‐hPhg]₂‐OBn. Several reaction conditions have been tested, always in the absence of a protecting group on the HA hydroxyl. This reaction affords the desired compounds with complete regioselectivities being the other regioisomer completely avoided. Furthermore high enantioselectivities and satisfactory diastereoselectivities, always favouring the syn diastereoisomers, were obtained. The stereochemistry of the diols was further confirmed by the analysis of the ¹H NMR spectrum of the corresponding carbonates, obtained by reaction of the syn/anti mixtures with triphosgene in presence of dimethylamino‐pyridine (DMAP).