Multivariate analysis approach to the plasma protein profile of patients with advanced colorectal cancer

The aim of the present study was to identify the pattern of plasma protein species of interest as markers of colorectal cancer (CRC). Using matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS), the plasma protein profile was determined in nine stage IV CRC patients (study group) and nine clean-colon healthy subjects (control group). Multivariate analysis methods were employed to identify distinctive disease patterns at protein spectrum. In the study and control groups, cluster analysis (CA) on the complete MALDI-MS spectra plasma protein profile showed a distinction between CRC patients and healthy subjects, thus allowing the identification of the most discriminating ionic species. Principal component analysis (PCA) and linear discriminant analysis (LDA) yielded similar grouping results. LDA with leave-one-out cross validation achieved a correct classification rate of 89% in both the patients and the healthy subjects.     

An investigation on the possible role of melatonin in melanogenesis

The possible role of melatonin in melanogenesis was investigated by performing reactions of melatonin with peroxidase + H2O2 or H2O2 only, in the presence or absence of UV irradiation. Samples of the reaction mixtures were drawn at different times (from 15 to 480 min), the enzyme (when present) was removed by ultrafiltration and the samples so obtained were analyzed by MALDI/MS.The results show that melatonin undergoes oligomerization reaction with peroxidase + H2O2, leading to heptameric species. For high reaction times the MALDI/MS data do not show the formation of larger oligomers, but UV-vis spectroscopy indicates that the oligomerization processes proceed. The failure of MALDI-TOF in the identification of larger oligomers was related to the chemical-physical and morphological behavior of melanins.In the case of UV irradiation, the formation of species originating from the O- and O2 addition to melatonin, which activate new oligomerization channels, has been observed.     

Coherent Structures Formation During Wake-Boundary Layer Interaction on a LP Turbine Blade

Particle Image Velocimetry (PIV) measurements have been analyzed in order to characterize the dynamics of coherent structures (eddies and streaks) within the suction side boundary layer of a low pressure turbine cascade perturbed by impinging wakes. To this end, the instantaneous flow fields at low Reynolds number and elevated free-stream turbulence intensity level (simulating the real condition of the blade row within the engine) were investigated in two orthogonal planes (a blade-to-blade and a wall-parallel plane). Proper Orthogonal Decomposition (POD) has been employed to filter the instantaneous flow maps allowing a better visualization of the structures involved in the transition process of the boundary layer. For the unsteady case properly selected POD modes have been also used to sort the instantaneous PIV images in the wake passage period. This procedure allows computing phase-averaged data and visualizing structures size and intensity in the different parts of the boundary layer during the different wake passage phases. The contributions to the whole shear stress due to the largest spanwise oriented scales at the leading and trailing boundaries of the wake-jet structures and those associated with streaky structures observed in the bulk of the wake are discussed. Instantaneous images in the wall-parallel plane are filtered with POD and they allow us to further highlight the occurrence of low and high speed traveling streaks (Klebanoff mode). The periodic advection along the suction side of the high turbulent content regions carried by the wakes anticipates both formation and sinuous instability of the streaks inside the boundary layer as compared with the steady case. The dynamics driving the breakdown of the streaks and the consequent formation of nuclei with high wall-normal vorticity have been found to be almost the same in the steady and the unsteady cases. Auto-correlation of the instantaneous images are also presented in order to highlight analogies and differences in the size and spacing of streaks in the two cases. These results are also compared with the available literature concerning simplified geometries (i.e flat plate) operating under steady inflow.     

An unprecedented switching of the second-order nonlinear optical response in aggregate bis(salicylaldiminato)zinc(II) Schiff-base complexes

A luminescent bis(salicylaldiminato)zinc(II) Schiff-base complex, 1, is characterized by a concentration dependent second-order nonlinear optical response, related to the degree of aggregation of the complex in a dichloromethane solution. The formation of the monomeric adduct, by addition of a Lewis base, such as pyridine, to concentrated solutions of 1, leads to a switch-on of the quadratic hyperpolarizability. This represents an unprecedented mode of NLO switching in molecular materials.     

Monolayers of polyethilenimine on flat glass: a versatile platform for cations coordination and nanoparticles grafting in the preparation of antibacterial surfaces

A polyethylenimine (PEI) self-assembled monolayer (SAM) is prepared, capable of complexing silver and copper cations and of anchoring silver nanoparticles, exerting antibacterial activity against Escherichia coli and Staphylococcus aureus. Functionalized glassy surfaces have been fully characterized through spectroscopic techniques (UV-Vis spectroscopy, spectroscopic ellipsometry), atomic force microscopy imaging and quantitative Ag and Cu analysis (ICP optical emission spectroscopy).     

DNA as invisible ink for AFM nanolithography

We have used nanografting, an atomic force microscopy (AFM)-based nanolithography technique, to fabricate thiolated DNA nanostructures on gold surfaces. The tip-guided assembly offers opportunities for locally controlling the packing order, density, and thus the thickness of the DNA patterns. By selecting proper nanografting parameters, we can embed single-stranded DNA (ssDNA) patches into a background composed of the same DNA molecule prepared by self-assembly, in which the patches remain topographically (and chemically) invisible but have much improved packing order. When the complementary DNA (cDNA) is added, the thickness of the nanografted layer increases much more dramatically than that of the self-assembled layer during the hybridization process, and as a result, the pattern emerges. Interestingly, the pattern can be reversibly hidden and shown with high fidelity simply by dehybridizing and appending the cDNA repeatedly.     

Total positivity properties of Jacobi–Stirling numbers

The Jacobi–Stirling numbers of the first and second kinds were first introduced in Everitt et al. (2007) [8] and they are a generalization of the Legendre–Stirling numbers. Quite remarkably, they share many similar properties with the classical Stirling numbers. In this paper we study total positivity properties of these numbers. In particular, we prove that the matrix whose entries are the Jacobi–Stirling numbers is totally positive and that each row and each column is a Pólya frequency sequence, except for the columns with (unsigned) numbers of the first kind.     

ESI-MS and MALLS analysis of quaternary structure of molluscan hemocyanins

The understanding of the function of macromolecular complexes is mainly related to a precise knowledge of their structure. Recently, the development of suitable mass spectrometric techniques (electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI)) and multi-angle laser light scattering has enabled mass determination of native complexes and of their subunits. By these techniques, the structure and association/dissociation behavior of huge molecules of molluscan Octopus vulgaris, Sepia officinalis and Rapana venosa have been characterized. Molecular masses of the native and dissociated molecule of cephalopodan Hcs O. vulgaris (3545 and 359.3?kDa, respectively) and S. officinalis (4134 and 443.8?kDa, respectively) revealed that only one type subunit organizes their molecules, while the presence of two isoforms with different masses (422.8 and 400.0?kDa) has been determined for gastropodan R. venosa Hc, aggregated into didecamers. The difference of their structural subunits was also established after limited proteolysis with TPCK-trypsin. Eight functional units (FUs) with masses of?~?50?kDa were isolated from both subunits of RvH and isoform of Sepia officinalis, while seven FUs were purified from OvH. Further characterization of proteins by ESI-mass spectrometry (MS) and MALDI-MS, methods gave insights into post-translational modifications such as glycosylation. Glycosylation of O. vulgaris and S. officinalis Hcs was suggested based on the differences (11.6 and 40.0?kDa, respectively) between the masses measured by ESI-MS and those calculated by their gene sequences.