Development of smooth finishes in electrostatic fluidized bed (EFB) coating process of high-performance thermoplastic powders (PPA 571 H)

This paper deals with the analysis of the evolution of the surface morphology of metal substrates coated with high-performance thermoplastic powders, namely PPA 571 H, by using electrostatic fluidized bed (EFB) process. Attention has been particularly focused on the relationship between baking time and temperature of EFB coated substrates and the morphological characteristics of the resulting polymeric films.

First, thermal behaviour of PPA 571 H polymeric powders was characterized by using standard calorimetric techniques. Accordingly, PPA 571 H melting kinetic was experimentally deduced. Based upon experimental findings, predictive analytical model was also developed and employed to trace ‘iso-conversion’ curves out.

Second, metal substrates, made from low carbon steel (AISI 1040), were EFB coated and baked at several baking time and temperatures. Combined analyses of scanning electron and confocal microscopes were led to measure the evolution of the films surface morphology under different baking conditions. Accordingly, a relationship between film morphologies and melting degree was sought. Consistent trends of roughness parameters versus baking parameters were found, with smoother finishes of the polymeric films being achieved for higher degrees of melting, that is, for higher baking temperature and time. Full maps and related analytical models of the finishing levels according to baking parameters were also built up, hence providing first useful indications to powder coaters on how to best deal with their settings.     

Asset Price Anomalies under Bounded Rationality

We analyze the classical asset pricing model assuming non fully rationalagents.Agents forecast future prices cum dividend through an adaptive learning rule.This assumption provides an explanation of some anomalies encounteredin the empirical analysis of asset prices under full rationality:returns are serially correlated(positively over a short horizon and negatively over a longer horizon)and the dividend yield predicts future returns (positive correlation).Considering the continuous time limit process,the same regularities are established analytically for price increments.     

Video laparoscopic cholecystectomy in a case of biliary lithiasis associated with gallbladder tuberculosis. Considerations and review of the literature

METHODS: We have investigated the effects of allergen immunotherapy on the nasal responses in the guinea-pigs with allergic rhinitis. Thirty-three male Hartley guinea-pigs with allergic rhinitis were divided into three groups; those receiving intradermal injection of saline (Group 1) or 0.1% ovalbumin (Group 2) 6 days after the last intranasal sensitization, and those injected with 0.1% ovalbumin intradermally once daily for 6 consecutive days from the next day after the last intranasal sensitization (Group 3). RESULTS: The dye leakage and histamine content into the nasal lavage significantly decreased at 30 min after antigen challenge in Group 3, compared with Group 1 or 2. We also observed the change of mast cell numbers in superficial nasal mucosa, lamina propria and injected dorsal skin. The number of mast cells in superficial nasal mucosa significantly decreased in Group 3 compared with Group 1 or 2, but not those in nasal lamina propria or dorsal skin. CONCLUSIONS: These results suggest that the improvements of nasal responses such as dye leakage and histamine content may be caused by the decrease of mast cell numbers in the superficial mucosal layer after the specific immunotherapy, which may be developing tolerance and one of the mechanisms underlying the beneficial effect of immunotherapy.     

Moving Out of Home Ownership in Later Life: The Influence of the Family and Housing Careers

Home ownership is often regarded as the preferred housing tenure; however, situations in parallel life-course careers might make moving to a rental home necessary or attractive to home owners. Retrospective data from the SHARELIFE survey were used to study the short- and long-term impact of situations and disruptions in the family and housing careers on leaving home ownership at middle (45–64) and older ages (65–80) in Denmark, Sweden and the Netherlands. We found that directly after separation and widowhood, the likelihood of leaving home ownership was the greatest. However, more than 10 years after separation and widowhood, individuals were still significantly more likely to leave ownership than those in their first marriage. Furthermore, late first childbirth and early first-time home ownership were associated with lower chances of leaving home ownership. We conclude that situations and changes in family and housing careers have both a short-term and a long-term impact on the likelihood of moving out of home ownership.     

RC columns externally strengthened with RC jackets

In this paper the behaviour in compression of RC columns externally strengthened with concrete jacketing is analysed and a cross-section analysis of the jacketed member under axial load and bending moment is developed. The focus was to study the effect of confinement of concrete jacket on concrete core and the behaviour of compressed bars with buckling effects. Some other important aspects such as shrinkage, creep, old to new concrete surfaces and bond split effects were not included in the model because: the use of thick non-shrink grout jacket and a well-roughened surface of old-to-new concrete was supposed; long term effects were included though corrective coefficients for monolithic behaviour proposed in the literature. A preliminary validation of the model adopted was made referring to the short-term experimental data available in the literature on the compressive behaviour of RC columns strengthened with concrete jacketing. Good agreement was obtained with the available data in terms of moment-axial force domains and moment–curvature diagrams. The analysis showed the effectiveness of this reinforcing technique in improving both the strength and the ductility of RC cross-sections of columns, highlighting the importance of an accurate choice of strengthened materials (concrete grade, thickness of jacket, space and diameter of stirrups, etc.).     

Effectiveness of nitrogen incorporation to enhance the photoelectrochemical activity of nanostructured TiO2:NH3 versus H2-N2 annealing

Highly ordered TiO(2) nanohole layers were synthesized by anodic oxidation of titanium foils using ethylene glycol and ammonium fluoride as the electrolyte. The effectiveness of different methods, namely annealing at 500?°C in NH(3) and in H(2) diluted in N(2), to incorporate nitrogen into TiO(2) and thus extend its photoelectrochemical (PEC) activity to the visible range was studied. The intra-gap levels introduced by both processes were identified by means of XPS and PL measurements. Water splitting experiments demonstrated that annealing in H(2) improved the photocatalytic activity of pure TiO(2), while annealing in ammonia led to a decrease in the PEC performance.     

Study of the in vitro corrosion behavior and biocompatibility of Zr-2.5Nb and Zr-1.5Nb-1Ta (at%) crystalline alloys

The in vitro corrosion behavior and biocompatibility of two Zr alloys, Zr-2.5Nb, employed for the manufacture of CANDU reactor pressure tubes, and Zr-1.5Nb-1Ta (at%), for use as implant materials have been assessed and compared with those of Grade 2 Ti, which is known to be a highly compatible metallic biomaterial. The in vitro corrosion resistance was investigated by open circuit potential and electrochemical impedance spectroscopy (EIS) measurements, as a function of exposure time to an artificial physiological environment (Ringer’s solution). Open circuit potential values indicated that both the Zr alloys and Grade 2 Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Zr-1.5Nb-1Ta alloy and that this oxide has better corrosion protection characteristics than the ones formed on Grade 2 Ti or on the Zr-2.5Nb alloy. EIS study showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film presents on the metals surface, improving their resistance with exposure time, presenting the highest values to the Zr-1.5Nb-1Ta alloy. For the biocompatibility analysis human osteosarcoma cell line (Saos-2) and human primary bone marrow stromal cells (BMSC) were used. Biocompatibility tests showed that Saos-2 cells grow rapidly, independently of the surface, due to reduced dependency from matrix deposition and microenvironment recognition. BMSC instead display a reduced proliferation, possibly caused by a reduced crosstalk with the metal surface microenvironment. However, once the substrate has been colonized, BMSC seem to respond properly to osteoinduction stimuli, thus supporting a substantial equivalence in the biocompatibility among the Zr alloys and Grade 2 titanium. In summary, high in vitro corrosion resistance together with satisfactory biocompatibility make the Zr-2.5Nb and Zr-1.5Nb-1Ta crystalline alloys promising biomaterials for surgical implants.     

Biodegradation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) by Phanerochaete chrysosporium: new insight into the degradation pathway

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is a recalcitrant energetic chemical that tends to accumulate in soil, close to the surface. The present study describes the aerobic biodegradability of HMX using Phanerochaete chrysosporium. When added to 7 day old static P. chrysosporium liquid cultures, HMX (600 nmol) degraded within 25 days of incubation. The removal of HMX was concomitant with the formation of transient amounts of its mono-nitroso derivative (1-NO-HMX). The latter apparently degraded via two potential routes: the first involved N-denitration followed by hydrolytic ring cleavage, and the second involved alpha-hydroxylation prior to ring cleavage. The degradation of 1-NO-HMX gave the ring-cleavage product 4-nitro-2,4-diazabutanal (NDAB), nitrite (NO2 -), nitrous oxide (N2O), and formaldehyde (HCHO). Using [14C]-HMX, we obtained 14CO2 (70% in 50 days), representing three C atoms of HMX. Incubation of real soils, contaminated with either HMX (403 micromol kg(-1)) (military base soil) or HMX (3057 micromol kg(-1)), and RDX (342 micromol kg(-1)) (ammunition soil) with the fungus led to 75 and 19.8% mineralization of HMX (liberated 14CO2), respectively, also via the intermediary formation of 1-NO-HMX. Mineralization in the latter soil increased to 35% after the addition of glucose, indicating that a fungus-based remediation process for heavily contaminated soils is promising. The present findings improve our understanding about the degradation pathway of HMX and demonstrate the utility of using the robust and versatile fungus P. chrysosporium to develop effective remediation processes for the removal of HMX.     

Improved inference on a scalar fixed effect of interest in nonlinear mixed-effects models

Likelihood-based inference on a scalar fixed effect of interest in nonlinear mixed-effects models usually relies on first-order approximations. If the sample size is small, tests and confidence intervals derived from first-order solutions can be inaccurate. An improved test statistic based on a modification of the signed likelihood ratio statistic is presented which was recently suggested by Skovgaard [1996. An explicit large-deviation approximation to one-parameter tests. Bernoulli 2, 145-165]. The finite sample behaviour of this statistic is investigated through a set of simulation studies. The results show that its finite-sample null distribution is better approximated by the standard normal than it is for its first-order counterpart. The R code used to run the simulations is freely available.