Viscoelastic type magnetic effects and self-gravity on the propagation of MHD waves

Meccanica - We take up the challenge to explain the correlation between the Jeans instability topic towards star formation within the accelerated expansion of universe and the role of torsional...     

Semi-preparative HPLC purification of δ-tocotrienol (δ-T3) from Elaeis guineensis Jacq. and Bixa orellana L. and evaluation of its in vitro anticancer activity in human A375 melanoma cells

In this work, we report a rapid and convenient HPLC-UV-DAD method for the isolation of δ-T3 on semi-preparative scale from two different vitamin E rich processed, commercially available products obtained from the fruits of Elaeis guineensis Jacq. (oil palm) and from the seeds of Bixa orellana L. (achiote tree). Chromatography was run using reverse phase (RP) C-18 columns and HPLC-grade acetonitrile as mobile phase. The purity of the isolated δ-T3, assessed by GC–MS and ¹H NMR was above 98%. The δ-T3 cytotoxic activity found in vitro against the proliferation of human A375 melanoma cells compared to that of the other δ-T3 free tocols mixture suggest its primary role in the experimental anticancer activity observed for palm oil derived products. Taken altogether, the results of this study highlight the importance of the application of suitable purification systems for the preparations of tocotrienols prior to their experimental or clinical testing.     

Non-existence of one-signed solutions for variational equations with locally amplifying potentials

In questo lavoro si considerano equazioni differenziali ordinarie del secondo ordine di tipo singolare della forma

Hybrid Photonic Nanostructures by In Vivo Incorporation of an Organic Fluorophore into Diatom Algae

Biotechnological processes harnessing living organisms' metabolism are low‐cost routes to nanostructured materials for applications in photonics, electronics, and nanomedicine. In the pursuit of photonic biohybrids, diatoms microalgae are attractive given the properties of the porous micro‐to‐nanoscale structures of the biosilica shells (frustules) they produce. The investigations have focused on in vivo incorporation of tailored molecular fluorophores into the frustules of Thalassiosira weissflogii diatoms, using a procedure that paves the way for easy biotechnological production of photonic nanostructures. The procedure ensures uniform staining of shells in the treated culture and permits the resulting biohybrid photonic nanostructures to be isolated with no damage to the dye and periodic biosilica network. Significantly, this approach ensures that light emission from the dye embedded in the isolated biohybrid silica is modulated by the silica's nanostructure, whereas no modulation of photoluminescence is observed upon grafting the fluorophore onto frustules by an in vitro approach based on surface chemistry. These results pave the way to the possibility of easy production of photonic nanostructures with tunable properties by simple feeding the diatoms algae with tailored photoactive molecules.     

Tuning of a Vertical Spin Valve with a Monolayer of Single Molecule Magnets

The synthesis and the chemisorption from solution of a terbium bis‐phthalocyaninato complex suitable for the functionalization of lanthanum strontium manganite (LSMO) are reported. Two phosphonate groups are introduced in the double decker structure in order to allow the grafting to the ferromagnetic substrate actively used as injection electrode in organic spin valve devices. The covalent bonding of functionalized terbium bis‐phthalocyaninato system on LSMO surface preserves its molecular properties at the nanoscale. X‐ray photoelectron spectroscopy confirms the integrity of the molecules on the LSMO surface and a small magnetic hysteresis reminiscent of the typical single molecule magnet behavior of this system is detected on surface by X‐ray magnetic circular dichroism experiments. The effect of the hybrid magnetic electrode on spin polarized injection is investigated in vertical organic spin valve devices and compared to the behavior of similar spin valves embedding a single diamagnetic layer of alkyl phosphonate molecules analogously chemisorbed on LSMO. Magnetoresistance experiments have evidenced significant alterations of the magneto‐transport by the terbium bis‐phthalocyaninato complex characterized by two distinct temperature regimes, below and above 50 K, respectively.     

Modified organophilic montmorillonites/LDPE nanocomposites

In this work a commercially available organophilic Montmorillonite (Cloisite 30B) was modified by interaction with different surfactants, namely dodecylsuccinic anhydride (DSA), octadecylamine (ODA), octadecanoic alcohol (ODOH) and octadecanoic acid (ODAc), in order to increase its basal spacing and to achieve a better dispersibility in LDPE. The morphology of the dispersions was investigated through XRD and TEM analyses. Intercalation phenomena were found for all the systems investigated. The thermal properties of the obtained nanocomposites were studied by means of DSC and TGA measurements. No variation of T _m and crystallinity of LDPE was found after the addition of the nanoclays (5 mass/mass%). A significant increase of the air thermal stability of LDPE was achieved in the presence of the modified nanoclays.     

Perspectives in paramagnetic NMR of metalloproteins

NMR experiments and tools for the characterization of the structure and dynamics of paramagnetic proteins are presented here. The focus is on the importance of (13)C direct-detection NMR for the assignment of paramagnetic systems in solution, on the information contained in paramagnetic effects observed both in solution and in the solid state, and on novel paramagnetism-based tools for the investigation of conformational heterogeneity in protein-protein complexes or in multi-domain proteins.     

A New Sulfur‐containing Schiff‐Base Ligand and Binding to Copper(II) and Cobalt(II)

A new Schiff‐base ligand having a potentially coordinating thioether group (2‐quinoline‐N‐(2′‐methylthiophenyl)methyleneimine, qmtpm ) has been prepared. The synthesis, structure, UV‐Vis and EPR studies of one copper(II) and two cobalt(II) complexes from this ligand is reported. The X‐ray structures of the Cu^II and Co^II chlorido complexes 1 and 2 reveal the metal atoms in highly distorted square‐pyramidal environments constituted of one tridentate ligand and two anions. On the other hand, the thiocyanato Co^II compound 3 exhibits a distorted trigonal‐bipyramidal structure. These structural variations are apparently due to the different counter‐ions which leads to distinct lattice interactions. The spectroscopic data obtained by EPR and UV‐Vis investigations are in agreement with the solid‐state structures of the coordination compounds.     

Synthesis and anti‐HIV‐1 evaluation of 1,5‐disubstituted pyrimidine‐2,4‐diones

1,5‐Disubstituted pyrimidine‐2,4‐diones were synthesized by fusion of 5‐bromouracil with an aniline derivative followed by coupling with benzyl halide whereas the opposite synthesis sequence failed. Also 4,6‐dichloro‐N,N,5‐trimethylpyrimidin‐2‐amine was treated with phenols. The products were tested for their activity against HIV‐1.