Advanced microstructural characterization of plasma-sprayed zirconia coatings over extended length scales

Achieving control of the microstructure of plasma-sprayed thermal barrier coating (TBC) systems offers an opportunity to tailor coating properties to demanding applications. Accomplishing this requires a fundamental understanding of the correlations among processing, microstructure development, and related TBC properties. This article describes the quantitative characterization of the microstructure of plasma-sprayed partially stabilized zirconia (PSZ) coatings by means of x-ray and neutron-scattering imaging techniques. Small-angle neutron scattering, ultra-small-angle x-ray scattering, and x-ray microtomography were used to characterize and visualize the nature and structure of the features in these material systems. In addition, the influence of processing parameters on microstructure development is discussed along with thermal cycling effects on the pore morphology, and their resultant influence of the porosity on the thermal conductivity and elastic modulus of plasma-sprayed PSZ TBCs.     

Investigation of elastic constants of polymer/nanoparticles composites using the brillouin spectroscopy and the mechanical homogenization modeling

A numerical model using homogenization techniques is proposed to simulate the evolution of elastic properties of nanocomposite polymer‐nanoparticles, depending on the concentration of nanoparticles and the rigidity of the particle–matrix interface. To validate this model, it was confronted to several physical systems having different interface behavior, the nanocomposite systems: poly(vinylidene fluoride trifluoroethylene)/Al₂O₃ (alumina nanoparticles incorporated into copolymer of vinylidene difluoride and trifluoroethylene to form nanocomposite), PMMA/CNT (carbon nanotube/poly(methyl methacrylate) composite) and PMMA/SiO₂ with nanoparticles with or without surface treatment of silanization. For all these systems, the Young's modulus (nanoparticles and matrix) has been obtained experimentally from the elastic modulus C₁₁ obtained by Brillouin spectroscopy. These macroscopic measurements coupled with the theoretical model allow a multiscale approach of the elastic behavior of nanocomposite systems, providing information on the global elastic properties of polymer‐nanoparticle material, and also indications about the strength of physical and chemical bonds between the nanoparticles and the matrix. Our results validate the hypothesis of the crucial role of the interface module, provided by numerical simulation which shows that incorporation of nanoparticles may lead to a strengthening or a weakening of the matrix. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

Formulation and characterization of chitosan-based biocomposites with potential use for bone adhesion

The effects of the addition of calcium carbonate (CC) and hydroxyapatite (HA) in chitosan-based biocomposites were studied keeping in mind their potential use as bone adhesives. The formation of coordination bonds between calcium ions and chitosan amino groups was evident, producing ionic cross-links between chitosan macromolecules, which changed chitosan gelation mechanisms, gel strengths, and adhesiveness into bone surfaces; CC concentration is a key factor in these phenomena. A formulation with 2% chitosan and 4% of both CC and HA showed the most promising performance having high levels of adhesion to bone surfaces (0.27?MPa) and a cohesive mode of failure.     

Estimating a minimum set of physically based dynamic parameters to enhance statistical inference in block-oriented modeling

In process identification (i.e., dynamic model development) information on the precision and reliability of a parameter estimate is conveyed by a confidence interval. The best confidence interval is the one with the shortest width for a given level of confidence. Confidence intervals widen as the standard error increases or as the number of estimated parameters increases. When the value of a parameter is needed for physical understanding of process characteristics, its precision and reliability, i.e., certainty, is crucial. Parameter certainty increases as the number of estimated parameters decreases because this causes confidence intervals to shorten and confidence levels to increase. Hence, this article focuses on maximizing parameter certainty of physically interpretable dynamic parameters under block-oriented modeling by obtaining accurate values for all the dynamic parameters from a minimum set of estimated parameters. This objective is accomplished by the development of a procedure that identifies equivalent sets of parameters and estimates one parameter for each set. For a seven (7) input, five (5) output, simulated CSTR, its 84 physically based dynamic parameters were accurately determined from 23 estimated parameters that resulted in an increase in confidence level from 50% to 99.9% for a fixed interval width.     

Developing antibacterial surgical adhesives: An enhancement of cyanoacrylate polymers

Surgical site infections (SSIs) and traumatic wounds have a significant risk of becoming contaminated by microbial pathogens of both endogenous and nosocomial origins, including Staphylococcus aureus and Enterococci sp.. One preventative approach is to protect wounds from infection by using a rapidly curing adhesive to seal the wound and prevent further contamination. Here, we demonstrate the covalent incorporation of an antimicrobial, quaternary ammonium chloride monomer (quat) into a 2-octyl cyanoacrylate (2oc) polymer adhesive. Copolymerization was confirmed via nuclear magnetic resonance spectroscopy. Cytotoxicity of the copolymer was assessed against: S. epidermidis and E. coli, and 3T3 mouse fibroblasts. The CA-Quat polymer was found to exhibit dose-dependent bacteriostatic and bactericidal effects against both E. coli and S. epidermidis, importantly without showing any demonstrable toxicity against mammalian 3T3 fibroblast cells. The described experiments provide promising data to suggest successful copolymerization, effective antibacterial properties, and remarkably low cytotoxic effects of the copolymer on mammalian cells.     

The Effect of Seasonal Variations,Covariations with Minerals and Forage Value on Itchgrass’ Foliar Silicification from Sudanian Benin

Silica (SiO ₂) in forage grasses has been found in reducing cell-wall digestibility. This study investigates whether: (i) the seasonal variability affects the silica and minerals accumulation and forage values of leaves of R. cochinchinensis and (ii) silica concentration is correlated with minerals and fodder value. In an itchgrass population selected in the W Biosphere Reserve, leaves were collected on 90 marked plants from May to October 2003 and 2004, at 15 days intervals except May, June and October. Some 300 g of fresh blades from the 3 ^rd most recently expanded leaves were oven dried and analyzed for dry mass, SiO ₂, ash, N, Na, Ca, P, K, and Mg. Digestible Nitrogen Matter (DNM) and Fodder Energetic Value (FEV) were calculated using the Demarquilly formula. Apart from SiO ₂, ash and forage value, data were log-transformed to restore homoscedasticity before statistical analyses. SiO ₂ ranges from 5.69 % to 9.95 %, i.e. varying 1.4 fold between May and October, reaching 1.75 fold at mid-September. SiO ₂ is positively related to Ca but negatively to K, P, N, DNM and FEV. The negative correlations suggest that SiO ₂ concentration in R. cochinchinensis could be reduced with a significant increase in energy and accumulation of important nutrients such as N, P and K. Therefore, leaf silicification and nutritive value relationship should be conclusive in the case of itchgrass.     

A W‐band RF‐MEMS switched LNA in a 70 nm mHEMT process

This work presents a monolithic integrated reconfigurable active circuit consisting of a W‐band RF micro‐electro‐mechanical‐systems (MEMS) Dicke switch network and a wideband low‐noise amplifier (LNA) realized in a 70 nm gallium arsenide (GaAs) metamorphic high electron mobility transistor process technology. The RF‐MEMS LNA has a measured gain of 10.2–15.6 dB and 1.3–8.2 dB at 79–96 GHz when the Dicke switch is switched ON and OFF, respectively. Compared with the three‐stage LNA used in this design the measured in‐band noise figure (NF) of MEMS switched LNA is minimum 1.6 dB higher. To the authors’ knowledge, the experimental results represent a first time demonstration of a W‐band MEMS switched LNA monolithic microwave integrated circuit (MMIC) in a GaAs foundry process with a minimum NF of 5 dB. The proposed novel integration of such MEMS switched MMICs can enable more cost‐effective ways to realize high‐performance single‐chip mm‐wave reconfigurable radiometer front‐ends for space and security applications, for example. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:639–646, 2015.     

Codes of conduct in Open Source Software—for warm and fuzzy feelings or equality in community?

Software Quality Journal - This paper focuses on codes of conduct (CoC) of Free and Open Source Software (F/OSS) and their role in improving women’s participation in online communities of...     

Classical conditioning provides paternity advantage for territorial male blue gouramis (Trichogaster trichopterus).

An irony of territorial behavior is that successful territory defense requires males to be aggressive, but highly aggressive males often inadvertently repel females, potential mates that the territory was created to attract. The authors provide empirical evidence that learning to anticipate the arrival of a female not only can overcome this well-recognized cost of territorial behavior but also can provide a significant paternity advantage. Following a short training period in which male blue gourami fish (Trichogaster trichopterus) either received classically conditioned pairings of a signal and a receptive female or received unpaired presentations of the signal and a female, male subjects were given an opportunity to mate. Signaling of female accessibility not only enabled classically conditioned males to attenuate their initial aggressive response to arriving females but, more important, classically conditioned males were able to spawn with females sooner, clasp females more often, and produce more young than males that did not have the benefit of a signal. Results provide the first demonstration of direct reproductive benefits resulting from classical conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Results of three courses of adriamycin, bleomycin, vindesine, and dacarbazine with subtotal nodal irradiation in 189 patients with nodal Hodgkin''s disease (stage I, II and IIIA)

This paper will explore the delivery of mental health nursing care within a neo-liberal model of mental health care delivery in New Zealand. Mental health nursing as a socially constructed activity occurs within a particular political context, which determines its role and function. This environment determines the nature of the nurse-patient relationship which is integral to the role of mental health nurses. Critical analysis of the New Zealand Government's neo-liberal health policies will be conducted to explore their effect on mental health care delivery and the nurse-patient relationship. Some of the ideologies and values maintained by current dominant discourses within nursing and the State are discussed. To establish therapeutic partnerships with service-users, mental health nurses are urged to critically analyse their practice and the context in which it occurs.