Stochastic response determination of U-OWC energy harvesters: a statistical linearization solution treatment accounting for intermittent wave excitation

Nonlinear Dynamics - A novel statistical linearization technique is developed for determining approximately the response statistics and the power output of U-Oscillating Water Column (U-OWC) energy...     

Spectroscopic parameters of theJ π=1+,T=0 excited6Li level

An analysis of thed- coincidence spectra of the⁷Li(³He, d)⁴He reaction at incident energy of 5.0 MeV and at various detector angles has been carried out. The values of the spectroscopic parameters of theJ =1⁺,T=0⁶Li state at excitation energy of 5.65 MeV have been deduced. The results, considering the experimental errors, do not appear to be dependent on the geometry and are in line with the ones adopted in literature.     

A New Water Soluble Calixarene: 5,11,17,23-tetrasulphonato-25,27-di(hydroxycarbonylmethoxy)-26, 28-dihydroxycalix[4]arene. A Thermodynamic and Spectroscopic Investigation of Its Proton and Copper(II) Complexes

A new water soluble receptor 5,11,17,23-tetrasulphonato-25,27-di(hydroxycarbonylmethoxy)-26,28-dihydroxycalix[4]arene was synthesized andcharacterized and its proton and copper(II) complexes were studied andcompared with the analogous species of the fully carboxylated ligand5,11,17,23-tetrasulphonato-25,26,27,28-tetrakis(hydroxycarbonylmethoxy)calix[4]arene. H° and S° values are crucial for understanding thepeculiar acid-base properties of the ligand. EPR spectra together with theUV-VIS spectral data reveal the coordination stereochemistry of thecopper(II) species.     

New Bimetallic Ni–Rh Carbonyl Clusters: Synthesis and X-ray Structure of the [Ni7Rh3(CO)18]3?, [Ni3Rh3(CO)13]3? and [NiRh8(CO)19]2? Cluster Anions

The reaction of the [Ni₆(CO)₁₂]²⁻ dianion with [Rh(COD)Cl]₂ (COD = cyclooctadiene) in acetone affords a mixture of bimetallic Ni–Rh clusters, mainly consisting of the new [Ni₇Rh₃(CO)₁₈]³⁻ and [Ni₈Rh(CO)₁₈]³⁻ trianions. A study of the reactivity of [Ni₇Rh₃(CO)₁₈]³⁻ led to isolation of the new [Ni₃Rh₃(CO)₁₃]³⁻ and [NiRh₈(CO)₁₉]²⁻ anions. All these new bimetallic Ni–Rh carbonyl clusters have been isolated in the solid state as tetrasubstituted ammonium salts and have been characterised by elemental analysis, X-ray diffraction studies, ESI-MS and electrochemistry. The unit cell of the [NEt₄]₃[Ni₇Rh₃(CO)₁₈] salt contains two orientationally-disordered ν₂-tetrahedral [Ni₇Rh₃(CO)₁₈]³⁻ trianions with occupancy factors of 0.75 and 0.25. Besides, their inner Ni₃Rh₃ octahedral moieties show two cis sites purely occupied by Rh atoms, two trans sites purely occupied by Ni atoms and the remaining two cis sites are disordered Ni and Rh sites with respective occupancy fraction of 0.5. At difference from the parent [Ni₇Rh₃(CO)₁₈]³⁻, the octahedral [Ni₃Rh₃(CO)₁₃]³⁻ displays an ordered distribution of Ni and Rh atoms in two staggered triangles. The [NiRh₈(CO)₁₉]²⁻ dianion adopts an isomeric metal frame with respect to that of the [PtRh₈(CO)₁₉]²⁻ congener. As a fallout of this work, new high-yield synthesis of the known [Ni₆Rh₃(CO)₁₇]³⁻ and [Ni₆Rh₅(CO)₂₁]³⁻, as well as other currently-investigated bimetallic Ni–Rh clusters have been obtained.     

High-yield one-step synthesis in water of [Pt3n(CO)6n]2- (n > 6) and [Pt38(CO)44]2-

Carbonylation of Na2PtCl6.6H2O, as well as K2PtCl6, in water under a CO pressure of 900 mm Hg selectively and quantitatively affords [Pt3n(CO)6n]2- (n > 6) salts; conversely, their corresponding carbonylation at reduced CO pressure of 760-800 mm Hg leads to a convenient one-step synthesis of [Pt38(CO)44]2-.     

Functional and structural characterization of ovine ornithine transcarbamoylase

Ornithine transcarbamoylase from ovine liver has been purified to homogeneity. Like all anabolic OTCs, the ovine enzyme is a trimer, constituted by identical subunits of 34 kDa. Sequence analysis of the 54 N-terminal residues of ovine OTC shows a high degree of homology with the human enzyme. The optimum pH and the Michaelis constants for the catalytic reaction were determined. The ovine enzyme is the most thermostable one among mammals OTCs, its critical temperature being 6 degrees C higher than those measured for the other enzymes. The enzyme has been crystallised and the structure determined at 3.5 A resolution. Crystals belong to the cubic P4(3)32 space group, with a = b = c = 184.7 A and a solvent content of about 80%. There is no evidence of any ligand in the active site cavity, indicating that the crystals contain an unliganded or T state of the enzyme. The unliganded OTCase enzyme adopts a trimeric structure which, in the crystal, presents a three-fold axis coincident with the crystallographic one. The conformation of each monomer in the trimer is quite similar to that of the liganded human protein, with the exception of a few loops, directly interacting with the substrate(s), which are able to induce a rearrangement of the quaternary organisation of the trimer, that accounts for the cooperative behaviour of the enzyme following the binding of the substrates.     

A proteomic approach to study protein variation in GM durum wheat in relation to technological properties of semolina

Genetic manipulation of durum wheats by tobacco rab-1 genes influence the trafficking of gluten proteins through the secretory system by up- or down-regulating the transport step from the ER to the Golgi apparatus which may in turn modify functional performance of the grain. Gluten proteins were extracted from two genetically manipulated lines - Svevo B730 1-1 and Ofanto B688 1-2 - and their control lines and were analyzed by two dimensional gel electrophoresis. When the two-dimensional maps were compared by image analysis no significant differences between the GM line with an up-regulated trafficking containing the wild type tobacco rab1 (Svevo B730 1-1) and its control (Svevo control). By contrast, significant differences were found between the GM line with a down-regulated trafficking due to the tobacco rab1 mutant form (Ofanto B688 1-2) and its control (Ofanto control). Of the new protein spots detected in the down-regulated Ofanto B688 1-2 map, only a beta-amylase was identified. The remaining spots were susceptible to chymotripsin action but not to trypsin one, as in the case of the gluten protein. Rheological measurements showed that gluten quality was enhanced in the down-regulated Ofanto B688 1-2 without an increase in the amount of gluten. Proteomics is a useful and powerful tool for investigating protein changes in GMOs and in understanding events in food science and technology.     

Hydrophilic interaction liquid chromatography--mass spectrometry for the analysis of paralytic shellfish poisoning (PSP) toxins

Hydrophilic interaction liquid chromatography (HILIC) was examined for the separation of paralytic shellfish poisoning (PSP) toxins using the stationary phase TSK-gel Amide-80. The parameters tested included type of organic modifier and percentage in the mobile phase, buffer concentration, pH, flow rate and column temperature. Using mass spectrometric (MS) detection, the HILIC column allowed the determination of all the major PSP toxins in one 30 min analysis with a high degree of selectivity and sensitivity. The high percentage of organic modifier in the mobile phase and the omission of ion pairing reagents, both favored in HILIC, provided limits of detection (LOD) in the range 50-100 nM in selected ion monitoring (SIM) mode on a single quadrupole LC-MS system. LOD in selected reaction monitoring (SRM) mode on a sensitive triple quadrupole system were as low as 5-30 nM. Excellent linearity of response was observed.     

LATERAL INTERACTIONS BETWEEN VERTEBRATE PHOTORECEPTORS

Vertebrate photoreceptors generate electrical signals across their cell membrane when they absorb light. Recent studies show, moreover, that the membrane potential of an individual photoreceptor may be also modified by illumination of its neighbors. Two types of lateral interactions have been described: a direct interaction mediated by electrical synapses between adjacent photoreceptors, and a recurrent interaction mediated by a feedback circuit involving horizontal cells. In the first mechanism, photoreceptors summate their responses over short retinal distances. In the feedback circuit photoreceptors may develop light responses of opposite polarity to those induced by direct illumination. In general, these 'antagonistic' responses are best elicited by large area retinal illumination. As a consequence of these photoreceptor interactions rather complex processing of visual information, in both spatial and chromatic domains, occurs at the first stage of the retinal network.