Ce dopant segregation in Y3Al5O12 optical ceramics

Ce³⁺-doped YAG garnet optical ceramic have been sintered at the Shanghai Institute of Ceramics in China to characterize dopant distribution in optical ceramics by combining optical spectroscopy and two spatially resolved techniques as imaging confocal microscopy and transmission electron microscopy. A strong Ce³⁺ segregation and spatial variations of content between grains and grain boundaries has been confirmed by quantitative data obtained by TEM microscopy. This observation is another evidence of the inhomogeneous Ce³⁺ distribution across grain and grain boundaries in optical ceramics comparable to that of Nd³⁺ ions in YAG ceramics. These results correlate well with low segregation coefficients of Nd³⁺ and Ce³⁺ observed in the garnet crystals grown from the melt and/or flux.     

Optimization of synthesis parameters in interfacial polycondensation using design of experiments

The reaction of phenylphosphonic dichloride with 4,4′-cyclohexylidenebisphenol by a gas–liquid interfacial polycondensation was investigated. The design of experiments (DoE) method is used for determination of the best reaction conditions. The correlation of simultaneous influence of the parameters (reaction time, reaction temperature, alkaline medium, reagents molar ratio) on yield and inherent viscosity was studied.     

Noise in Refrigerating Tunnel Junctions and in Microbolometers

Microrefrigerators based on normal metal–insulator–superconductor (NIS) junctions represent a very attractive alternative to cool the microbolometers and calorimeters for astrophysical observations in space-borne experiments. The performance in such measurements requires a good knowledge of the noise sources in the detectors. In this paper we present detailed calculations of the thermal fluctuations and of the noise equivalent power due to the heat transfer through the NIS junctions or the thermal contact between different subsystems of the detector. The influence of the input optical power—which, in the cases that interest us, is the cosmic background radiation—will also be evaluated. Analytical approximations valid at low temperatures are given.     

Risk assessment for pipelines with active defects based on artificial intelligence methods

The paper provides another insight into the pipeline risk assessment for in-service pressure piping containing defects. Beside of the traditional analytical approximation methods or sampling-based methods safety index and failure probability of pressure piping containing defects will be obtained based on a novel type of support vector machine developed in a minimax manner. The safety index or failure probability is carried out based on a binary classification approach. The procedure named classification reliability procedure, involving a link between artificial intelligence and reliability methods was developed as a user-friendly computer program in MATLAB language. To reveal the capacity of the proposed procedure two comparative numerical examples replicating a previous related work and predicting the failure probabilities of pressured pipeline with defects were presented.     

Iron Powder Treated Gray Irons: Critical Shape Characteristics for Graphite Nuclei

A program was conducted to research how to characterize the size and shape of micro-particles. These can act as graphite nuclei, but are altered by adding a commercial iron powder, or after a similar treatment combined with inoculation. Resin sand mold (RSM) and metal mold (MM) solidified sample structures were subjected to automatic image analysis. In general, a higher cooling rate, typical for MM solidification, favors smaller size and more compact particles, even in RSM media. Iron powder treatment led to the largest particles with unusual morphologies, better defined by complex shape factors, which employ actual perimeters, rather than the simpler median size and aspect ratio method. Conventional inoculation employed after an iron powder treatment altered the particles (smaller and more compact), which benefited their effectiveness to act as graphite nuclei, especially at slower solidification rates in RSMs. The results confirm that promoting more compact micro-inclusions, at smaller sizes, involved in graphite nucleation, reduces the sensitivity to chill and improves the eutectic cell characteristics in gray cast iron.     

Impedimetric detection of dopamine on poly(3-aminophenylboronic acid) modified skeleton nickel electrodes

Detection of biologic compounds in particular dopamine is usually based on the complexation between boronic acid groups and diols. For this reason the development of new sensors based on direct monitoring of boronic acid–diol complexation is attractive. A measurable electric response due to a change in the dopamine concentration can be achieved on electrodes modified with boronic groups. In this work a modified electrode has been obtained by electropolymerization of 3-aminophenylboronic acid in aqueous solutions on a preformed polyaniline layer electrochemically deposited on smooth and skeleton nickel electrodes. The modified electrodes have been tested as impedimetric sensors for the detection of dopamine in aqueous phosphate buffer at pH = 7.4. Both sensors gave a linear response for dopamine concentrations between 10^?5 and 10^?10 mol L^?1. Poly(3-aminophenylboronic acid) modified skeleton nickel electrode has the advantage of an increased specific surface area, that lead to a high density of boronic acid groups and hence to a better sensitivity.     

Hybrid nanostructured coating for increased resistance of prosthetic devices to staphylococcal colonization

Prosthetic medical device-associated infections are responsible for significant morbidity and mortality rates. Novel improved materials and surfaces exhibiting inappropriate conditions for microbial development are urgently required in the medical environment. This study reveals the benefit of using natural Mentha piperita essential oil, combined with a 5 nm core/shell nanosystem-improved surface exhibiting anti-adherence and antibiofilm properties. This strategy reveals a dual role of the nano-oil system; on one hand, inhibiting bacterial adherence and, on the other hand, exhibiting bactericidal effect, the core/shell nanosystem is acting as a controlled releasing machine for the essential oil. Our results demonstrate that this dual nanobiosystem is very efficient also for inhibiting biofilm formation, being a good candidate for the design of novel material surfaces used for prosthetic devices.     

Semi-batch reactive crystallisation of mono-ammonium phosphate: An experimental study

NH₄H₂PO₄, mono-ammonium phosphate (MAP) and (NH₄)₂HPO₄, di-ammonium phosphate (DAP) have become leading phosphate fertiliser products worldwide. Ammonium phosphates are produced by reactions of ammonia and phosphoric acid resulting in the formation of the mono-basic, di-basic, or tri-basic salts. Inefficiencies in the MAP/DAP production process are due to the lack of a fundamental understanding of the crystallisation–reaction mechanisms. A semi-batch reactive crystalliser equipped with a cooling jacket, a dual feed system and a turbine type agitator has been used in this study. Effects of N/P ratio, seed crystals, feeding system, feed flow rate, initial supersaturation, feeding time and mixing intensity to the real-time supersaturation, crystal yield, crystal shape (aspect ratio) and final crystal size distribution (CSD) were studied in order to understand the kinetics. This study aims to provide new insights into the MAP/DAP reaction–crystallisation mechanisms.     

Low density polyethylene composites containing cellulose pulp fibers

Unbleached and bleached Kraft cellulose pulp fibers modified with a long chain carboxylic acid, i.e. oleic acid in cold plasma conditions have been used as reinforcements in low density polyethylene (LDPE). The purpose of the modification is to enhance the interfacial adhesion between cellulose and matrix and to increase the dispersability. Composites containing up to 10 wt.% of untreated and modified cellulose pulp fibers with LDPE were prepared by melt mixing. The samples were characterized by processing behavior, mechanical and rheological properties, SEM, contact angle measurements, TGA and DSC. It was found that when the modified pulp fibers were incorporated into composites matrix, most of the properties have been improved.