Controlling the Critical Temperature in Mg1−x Al x B2

Here we report synthesis and characterization of high quality samples of the superconducting system Mg_1−x Al _x B₂, with a novel optimized preparation method, in a wide range of Al concentration. All the physical properties of the samples can be tuned continuously with increasing Al content. We have characterized the samples for their structural, morphological and magnetic properties with high resolution XRD, SEM-EDS and susceptibility measurements. We have prepared a large number of Al doped MgB₂ in the range 0<x<0.57. All the samples are bulk superconductors and the critical temperature show a smooth and regular behavior as a function of x. This work was supported by European project 517039 “Controlling Mesoscopic Phase Separation” (COMEPHS) (2005). An erratum to this article can be found at     

Mycotoxin occurrence in beer produced in several European countries

The occurrence of ochratoxin A, trichothecenes, fumonisins and aflatoxins in a sample of 106 beers produced in several European countries, was investigated. The analyses were conducted using high-performance liquid chromatography with fluorimetric detection for ochratoxin A and aflatoxins, gas-chromatography and high-performance liquid chromatography, both coupled with mass spectrometer, for trichothecenes and fumonisins, respectively. Aflatoxins were not detected in any samples, whereas ochratoxin A, deoxynivalenol and fumonisins were found in a relatively high number of samples. Their presence was at low levels in all samples; however, some differences were observed between the European countries. As regards ochratoxin A, beer samples from southern Europe showed levels always lower than 0.040 μg l^?1, while the samples from other European countries showed significantly higher values, up to 0.189 μg l^?1 (P < 0.001). For fumonisins, the levels of Italian beers were significantly higher compared to the samples from other countries (P = 0.006).     

Maternal dietary habits and mycotoxin occurrence in human mature milk

During 2006, 82 samples of human mature milk were collected at Italian hospitals and checked for aflatoxin M1 (AFM1) and ochratoxin A (OTA) by immunoaffinity column extraction and HPLC. AFM1 was detected in four (5%) of milk samples (ranging from < 7 ng/L to 140 ng/L; mean level: 55.35 ng/L); OTA was detected in 61 (74%) of milk samples (ranging from < 5 ng/L to 405 ng/L; mean level: 30.43 ng/L. OTA levels were significantly higher (p less, not double equals 0.05) in milk of habitual consumers of bread, bakery products and cured pork meat. No other statistically significant differences were observed although habitual consumers of pasta (p = 0.059), cookies (p = 0.061) and juices (p = 0.063) had mean contamination values of OTA higher than the moderate consumer. The very few AFB1 positive samples did not allow statistical comparisons. The present study confirms that the occurrence of OTA in human milk is related to maternal dietary habits. The findings support the possibility of dietary recommendations to woman, during pregnancy and lactation, aimed to tentatively reduce the OTA contamination of human milk.     

Prenatal THC Does Not Affect Female Mesolimbic Dopaminergic System in Preadolescent Rats

Cannabis use among pregnant women is increasing worldwide along with permissive sociocultural attitudes toward it. Prenatal cannabis exposure (PCE), however, is associated with adverse outcome among offspring, ranging from reduced birth weight to child psychopathology. We have previously shown that male rat offspring prenatally exposed to Δ9-tetrahydrocannabinol (THC), a rat model of PCE, exhibit extensive molecular, cellular, and synaptic changes in dopamine neurons of the ventral tegmental area (VTA), resulting in a susceptible mesolimbic dopamine system associated with a psychotic-like endophenotype. This phenotype only reveals itself upon a single exposure to THC in males but not females. Here, we characterized the impact of PCE on female behaviors and mesolimbic dopamine system function by combining in vivo single-unit extracellular recordings in anesthetized animals and ex vivo patch clamp recordings, along with neurochemical and behavioral analyses. We find that PCE female offspring do not show any spontaneous or THC-induced behavioral disease-relevant phenotypes. The THC-induced increase in dopamine levels in nucleus accumbens was reduced in PCE female offspring, even when VTA dopamine activity in vivo and ex vivo did not differ compared to control. These findings indicate that PCE impacts mesolimbic dopamine function and its related behavioral domains in a sex-dependent manner and warrant further investigations to decipher the mechanisms determining this sex-related protective effect from intrauterine THC exposure.     

Chemical etching in processing cortical bone specimens for scanning electron microscopy

Transverse and longitudinal sectioning of undecalcified cortical bone is a commonly employed technique for investigating the lamellar structure of the osteons. Since a flat surface is required, the specimen has to be grinded and then polished. Whereas the smear of debris and inorganic/organic deposits left by these treatments cannot be removed by ultrasonication alone, a chemical treatment of the specimen surface with either a basic or an acid etching solution is currently employed. A further effect of the latter can be the enhancement of the lamellar bone pattern. The kind of etching solution, its pH, the concentration of etchants, and the contact time significantly affect the sectioned surface when it is observed with scanning electron microscopy (SEM). The etching procedures can severely influence the obtained images. Homogeneous cortical bone specimens were sampled from the first metatarsal of two fresh human subjects. One or two cut surfaces were exposed to different acid and basic solutions in bonded conditions. Considering the type of chemical agents, the solution pH, and the exposure time of the specimens, the effects of several etching media have been investigated and compared. Strong etching, either acid or basic produced surface decalcification and severe damage of the collagen matrix, compromising any morphological or morphometric analysis. Weak acid etching (for example citric and acetic acid), even though causing distinctive alteration of the sample, enhanced the visibility of the lamellar pattern, while the polyphosphate treatment of the surface decalcified a thin layer matrix, ensuring a good visibility of fibrils and avoiding rough distortions. Microsc. Res. Tech. 77:653–660, 2014. © 2014 Wiley Periodicals, Inc.     

Characterization of stoichiometric nanocrystalline spinel ferrites dispersed on porous silica aerogel

Stoichiometric magnetic nanosized ferrites MFe2O4 (M = Mn, Co, Ni) were prepared in form of nearly spherical nanocrystals supported on a highly porous silica aerogel matrix, by a sol-gel procedure. X-ray diffraction and transmission electron microscopy indicate that these materials are made out of non-agglomerated ferrite nanocrystals having size in the 5-10 nm range. Investigation by M?ssbauer Spectroscopy was used to gain insights on the superparamagnetic relaxation and on the inversion degree. Magnetic ordering at room temperature varies from superparamagnetic in the NiFe2O4 sample, highly blocked (approximately 70%) in the MnFe2O4 sample and nearly fully blocked in the CoFe2O4 sample. A fitting procedure of the M?ssbauer data has been used in order to resolve the spectrum into the tetrahedral and octahedral components; in this way, an inversion degree of 0.68 (very close to bulk values) was obtained for 6 nm silica-supported CoFe2O4 nanocrystals.     

Human Primary Dermal Fibroblasts Interacting with 3-Dimensional Matrices for Surgical Application Show Specific Growth and Gene Expression Programs

Several types of 3-dimensional (3D) biological matrices are employed for clinical and surgical applications, but few indications are available to guide surgeons in the choice among these materials. Here we compare the in vitro growth of human primary fibroblasts on different biological matrices commonly used for clinical and surgical applications and the activation of specific molecular pathways over 30 days of growth. Morphological analyses by Scanning Electron Microscopy and proliferation curves showed that fibroblasts have different ability to attach and proliferate on the different biological matrices. They activated similar gene expression programs, reducing the expression of collagen genes and myofibroblast differentiation markers compared to fibroblasts grown in 2D. However, differences among 3D matrices were observed in the expression of specific metalloproteinases and interleukin-6. Indeed, cell proliferation and expression of matrix degrading enzymes occur in the initial steps of interaction between fibroblast and the investigated meshes, whereas collagen and interleukin-6 expression appear to start later. The data reported here highlight features of fibroblasts grown on different 3D biological matrices and warrant further studies to understand how these findings may be used to help the clinicians choose the correct material for specific applications.     

Participation of tachykinins in experimental models of lung damage

In the present investigation a possible involvement of tachykinins during sulfur dioxide-(SO2) and metabisulfite-(MBS) induced bronchoconstriction, and paraquat (PQ)-induced mortality was studied. SO2 (250ppm) inhalation and MBS (3mM) perfusion induced a marked decrease of compliance and conductance in the isolated and perfused lung. SO2-induced bronchoconstriction was associated with release of Calcitonin Gene Related Peptide, suggesting activation of capsaicin sensitive sensory nerves. Pretreatment of animals with capsaicin, in order to deplete the tachykinin content of sensory nerves, significantly reduced SO2- and MBS-induced bronchoconstriction. PQ (25mg/Kg) treatment induced high mortality (75%) after 3 weeks. Pretreatment with capsaicin significantly protected versus PQ induced mortality (25%). The results suggest that tachykinin content in the respiratory airways participate to SO2- and MBS-induced bronchoconstriction and PQ mortality.