Process investigation on meso-scale hard milling of ZrO2 by diamond coated tools

This paper investigates the feasible machining of zirconium oxide (ZrO₂) ceramics, in the hard state, via milling by diamond coated miniature tools (from here on briefly indicated as meso-scale hard milling). The workpiece material is a fully sintered yttria stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP). Diamond coated WC mills, 2 mm in diameter, four flutes and large corner radius (0.5 mm) are chosen as cutting tools, and experiments are conducted on a state-of-the-art micro milling machine centre. The influence of cutting parameters, including axial depth of cut (a_p) and feed per tooth (f_z), on the achievable surface quality is studied by means of a one-factor variation experimental design. Further tests are also conducted to monitor the process performance, including surface roughness, tool wear and machining accuracy, over the machining time. Mirror quality surfaces, with average surface roughness Ra below 80 nm, are obtained on the machined samples; the SEM observations of the surface topography reveal a prevailing ductile cutting appearance. Tool wear initiates with delamination of the diamond coating and progresses with the wear of the WC substrate, with significant effect on the cutting process and its performance. Main applications of this research include three dimensional surface micro structuring and superior surface finishing.     

Multilevel modelling for the regional effect of enforcement on road accidents

This paper investigates the effect of the intensification of Police enforcement on the number of road accidents at national and regional level in Greece, focusing on one of the most important road safety violations: drinking-and-driving. Multilevel negative binomial models are developed to describe the effect of the intensification of alcohol enforcement on the reduction of road accidents in different regions of Greece. Moreover, two approaches are explored as far as regional clustering is concerned: the first one concerns an ad hoc geographical clustering and the second one is based on the results of mathematical cluster analysis through demographic, transport and road safety characteristics. Results indicate that there are significant spatial dependences among road accidents and enforcement. Additionally, it is shown that these dependences are more efficiently interpreted when regions are determined on the basis of qualitative similarities than on the basis of geographical adjacency.     

The Effect of a Silver Nanoparticle Polysaccharide System on Streptococcal and Saliva-Derived Biofilms

In this work, we studied the antimicrobial properties of a nanocomposite system based on a lactose-substituted chitosan and silver nanoparticles: Chitlac-nAg. Twofold serial dilutions of the colloidal Chitlac-nAg solution were both tested on Streptococcus mitis, Streptococcus mutans, and Streptococcus oralis planktonic phase and biofilm growth mode as well as on saliva samples. The minimum inhibitory and bactericidal concentrations of Chitlac-nAg were evaluated together with its effect on sessile cell viability, as well as both on biofilm formation and on preformed biofilm. In respect to the planktonic bacteria, Chitlac-nAg showed an inhibitory/bactericidal effect against all streptococcal strains at 0.1% (v/v), except for S. mitis ATCC 6249 that was inhibited at one step less. On preformed biofilm, Chitlac-nAg at a value of 0.2%, was able to inhibit the bacterial growth on the supernatant phase as well as on the mature biofilm. For S. mitis ATCC 6249, the biofilm inhibitory concentration of Chitlac-nAg was 0.1%. At sub-inhibitory concentrations, the Streptococcal strains adhesion capability on a polystyrene surface showed a general reduction following a concentration-dependent-way; a similar effect was obtained for the metabolic biofilm activity. From these results, Chitlac-nAg seems to be a promising antibacterial and antibiofilm agent able to hinder plaque formation.     

The Versatile 2‐Substituted Imidazoline Nucleus as a Structural Motif of Ligands Directed to the Serotonin 5‐HT1A Receptor

The involvement of the serotonin 5‐HT_1A receptor (5‐HT_1A‐R) in the antidepressant effect of allyphenyline and its analogues indicates that ligands bearing the 2‐substituted imidazoline nucleus as a structural motif interact with 5‐HT_1A‐R. Therefore, we examined the 5‐HT_1A‐R profile of several imidazoline molecules endowed with a common scaffold consisting of an aromatic moiety linked to the 2‐position of an imidazoline nucleus by a biatomic bridge. Our aim was to discover other ligands targeting 5‐HT_1A‐R and to identify the structural features favoring 5‐HT_1A‐R interaction. Structure–activity relationships, supported by modeling studies, suggested that some structural cliché such as a polar function and a methyl group in the bridge, as well as proper steric hindrance in the aromatic area of the above scaffold, favored 5‐HT_1A‐R recognition and activation. We also highlighted the potent antidepressant‐like effect (mouse forced swimming test) of (S)‐(+)‐ 19 [(S)‐(+)‐naphtyline] at very low dose (0.01 mg kg^?1). This effect was clearly mediated by 5‐HT_1A, as it was significantly reduced by pretreatment with the 5‐HT_1A antagonist WAY100635.     

NotI Microarrays: Novel Epigenetic Markers for Early Detection and Prognosis of High Grade Serous Ovarian Cancer

Chromosome 3-specific NotI microarray (NMA) containing 180 clones with 188 genes was used in the study to analyze 18 high grade serous ovarian cancer (HGSOC) samples and 7 benign ovarian tumors. We aimed to find novel methylation-dependent biomarkers for early detection and prognosis of HGSOC. Thirty five NotI markers showed frequency of methylation/deletion more or equal to 17%. To check the results of NMA hybridizations several samples for four genes (LRRC3B, THRB, ITGA9 and RBSP3 (CTDSPL)) were bisulfite sequenced and confirmed the results of NMA hybridization. A set of eight biomarkers: NKIRAS1/RPL15, THRB, RBPS3 (CTDSPL), IQSEC1, NBEAL2, ZIC4, LOC285205 and FOXP1, was identified as the most prominent set capable to detect both early and late stages of ovarian cancer. Sensitivity of this set is equal to (72 ± 11)% and specificity (94 ± 5)%. Early stages represented the most complicated cases for detection. To distinguish between Stages I + II and Stages III + IV of ovarian cancer the most perspective set of biomarkers would include LOC285205, CGGBP1, EPHB1 and NKIRAS1/RPL15. The sensitivity of the set is equal to (80 ± 13)% and the specificity is (88 ± 12)%. Using this technique we plan to validate this panel with new epithelial ovarian cancer samples and add markers from other chromosomes.     

Suppression of three dimensional twinning for a 100% yield of vertical GaAs nanowires on silicon

Multiple seed formation by three-dimensional twinning at the initial stages of growth explains the manifold of orientations found when self-catalyzed GaAs nanowires grow on silicon. This mechanism can be tuned as a function of the growth conditions by changing the relative size between the GaAs seed and the Ga droplet. We demonstrate how growing under high V/III ratio results in a 100% yield of vertical nanowires on silicon(111). These results open up the avenue towards the efficient integration of III-V nanowire arrays on the silicon platform.     

Isolation, characterization and differentiation of mesenchymal stem cells from amniotic fluid, umbilical cord blood and Wharton's jelly in the horse

Mesenchymal stem cells (MSCs) have been derived from multiple sources of the horse including umbilical cord blood (UCB) and amnion. This work aimed to identify and characterize stem cells from equine amniotic fluid (AF), CB and Wharton's Jelly (WJ). Samples were obtained from 13 mares at labour. AF and CB cells were isolated by centrifugation, while WJ was prepared by incubating with an enzymatic solution for 2 h. All cell lines were cultured in DMEM/TCM199 plus fetal bovine serum. Fibroblast-like cells were observed in 7/10 (70%) AF, 6/8 (75%) CB and 8/12 (66.7%) WJ samples. Statistically significant differences were found between cell-doubling times (DTs): cells isolated from WJ expanded more rapidly (2.0±0.6 days) than those isolated from CB (2.6±1.3 days) and AF (2.3±1.0 days) (P<0.05). Positive von Kossa and Alizarin Red S staining confirmed osteogenesis. Alcian Blue staining of matrix glycosaminoglycans illustrated chondrogenesis and positive Oil Red O lipid droplets staining suggested adipogenesis. All cell lines isolated were positive for CD90, CD44, CD105; and negative for CD34, CD14 and CD45. These findings suggest that equine MSCs from AF, UCB and WJ appeared to be a readily obtainable and highly proliferative cell lines from a uninvasive source that may represent a good model system for stem cell biology and cellular therapy applications in horses. However, to assess their use as an allogenic cell source, further studies are needed for evaluating the expression of markers related to cell immunogenicity.     

Dimensional analysis of a prototype mould-making process for thermoplastic resin transfer moulding

The resin transfer moulding (RTM) process is a low-cost process for the production of parts of composite material. However, the economic convenience is lost when large components should be produced, because of the high tooling cost. The step milling of a resin master and the subsequent deposition of a nickel shell could be a valid alternative for the fabrication of an RTM mould. So far, information about the quality of this method of fabricating RTM moulds is lacking, thus more efforts are needed to quantify the error induced by the manufacturing sequence. In order to control the whole process and to assess the quality of the manufactured part, the dimensional deviation due to single manufacturing steps is evaluated for a reference part. Both traditional pointwise measurements and contactless scanning are used for dimensional inspection.     

Realization of high performance large area Z‐series‐interconnected opaque dye solar cell modules

We have designed and fabricated dye solar cell (DSC) modules with optimized geometries and processes. Integrated interconnections were made following the “Z” architecture for series connections. Several modules were prepared varying the materials, multilayer combination of the TiO₂ active layers, and the fabrication processes. With the best combination of TiO₂ multilayers, titanium tetrachloride (TiCl₄) treatment, a back reflector/diffusor, and optimized layout of cells via simulations, we fabricated a DSC module with a conversion efficiency of 6.9% on 43 cm² aperture area and 9.4% on active area. This result confirms that an effective scale‐up of high performance Z‐series‐connected DSC modules can be achieved comparable with other thin film technology. Note that the materials used to produce the devices of this work are all commercially available: an important result for a technology that is being developed for industrial application. Copyright © 2012 John Wiley & Sons, Ltd.     

Green tea extract as food antioxidant. Synergism and antagonism with α-tocopherol in vegetable oils and their colloidal systems

The antioxidant effects of α-tocopherol (TOH) in combination with green tea extract (GTE), the green tea polyphenol (−)-epicatechin (EC) or the isomeric (+)-catechin (C), were investigated using different lipid systems based on high linoleic sunflower oil: bulk oil, o/w-emulsion and a phosphatidylcholine-based liposome system. Both polyphenols as well as TOH were efficient antioxidants in all systems when used alone, as detected by the formation of free radicals and conjugated dienes and by oxygen consumption. Strong synergistic effect was found for the combination of TOH and GTE in a methyl linoleate o/w-emulsion and in the pure bulk oil, while only an additive effect was observed in a liposome system. The synergism was already evident for the tendency for radical formation in the bulk oil as detected by electron spin resonance (ESR) spectroscopy. On the contrary, combinations of TOH with either EC or C showed clear synergistic effects in both heterogeneous systems, but antagonistic or additive effects in bulk oil. GTE may accordingly be used to protect both vegetable oils and their emulsions against oxidation through enhancement of the activity of their endogenous antioxidants, while GTE is less efficient in the protection of phospholipids as in liposomes.