Aging of NTC Ceramics in the System Mn-Ni-Fe-O

The aging behaviour at 150°C of negative temperature coefficient ceramics in the system Mn-Ni-Fe-O has been investigated. Comparison is made between samples cooled in air and in a controlled atmosphere in which no oxidation can occur. The results show that the aging is dependent on composition and is strongly dependent on oxidation which occurs during cooling in air after sintering of the ceramics. From these results a model has been derived which describes the aging mechanism as a migration of cationic vacancies from the grain boundaries to the bulk. Additionally, cations and cationic vacancies migrate to their thermodynamically favourable site in the spinel structure.     

论经验与天真

建筑创造的过程中存在着对立的两种趋势,知之甚多与知之甚少,作者的实践就持续在这两极之间进行,当开展一个项目时,他们首先与经验丰富的工匠一起,寻找,发展出建筑设计中的关键要素,让工匠们成为设计发展过程中的重要成员,工匠与建筑师一起,深入开发设计之中。通过提出天真的问题,不断探索新的解决方法,筑造大样测试设计的可行性,制订出经济有效的细部节点,使设计方案得以实施,他们称此为“总营造师”方法。北美普遍存在的建造承包商和设计师的隔离,已经成为创新的障碍,他们认为“总营造师”的建造过程,将重塑两者间应有的历史角色,激发出优秀的建筑设计。     

Bactericidal polyurethane foam mattresses: Microbiological characterization and effectiveness

The antimicrobial compounds 2.4.4.″-tricloro-2″ hydroxydiphenyl ether (triclosan), 5-chloro-2-methyl-4-isothiazolin-3-one (isothiazolone) and bis(2-pyridylthio)zinc 1,1′-dioxide (zinc pyrithione) were incorporated into polyurethane foam matrixes. Concentrations of 0.20 wt.%, 0.50 wt.% and 1.00 wt.% of each biocide compound were used, and the infection reduction capacity was evaluated for different types of bacteria. The microbiological tests with polyurethane foams were performed with agar diffusion tests using the pour plate technique and analyzing the colony formation units (CFU) as a function of time. In preliminary tests, the micro-organisms Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella choleraesuis and Staphylococcus aureus were used. Tests in vitro showed that polyurethane foam containing zinc pyrithione gave the best performance. Genotoxicity tests were conducted to evaluate if the use of zinc pyrithione in the polyurethane causes harm to human users. Microbiological tests were also performed on the surfaces of mattresses that were produced with polyurethane foam to verify their antimicrobial properties. The significant decrease in the number of micro-organisms within the foam showed the effectiveness of the zinc pyrithione as an antimicrobial, while the genotoxicity tests demonstrated the absence of collateral effects for the users.     

The role of coastal processes in the management of the mouth of the River Murray,Australia: Present and future challenges

The Murray–Darling Basin is the largest river system in Australia to enter the sea. Prior to regulation of water flows, the Murray Mouth remained open to the sea even during droughts. An open mouth assists in sustaining the ecology of a Ramsar listed wetland and enables the flushing of salt, nutrients, and suspended sediments to the sea. Construction of barrages designed to prevent saltwater ingress has separated the estuary into two sections, a set of freshwater lakes and a saline tidal lagoon area, creating a unique set of management challenges. Under current overextraction of water resources upstream, river flows have been largely insufficient to counter wave and tide processes, which propel marine sands thereby constricting the Murray Mouth. Dredging has been required to maintain an open entrance. Managing this system is part of a 2012 agreement between state and federal governments, through the Murray–Darling Basin Plan. This plan recognizes a healthy end of system; however, the hydrological models failed to factor in the power of the sea in blocking the Murray Mouth. The plan requires that there will be sufficient river flows for the mouth to be open 95% of the time without dredging. Currently, sand ingress from the sea requires dredging most of the time. It is unlikely that there will be sufficient river flows to counteract continued sequestration of marine sand into the mouth. Sea level rise and decreased rainfall in the southern half of the Basin under climate change conditions will require a review of management options to prevent the long‐term degradation of the end of system.     

Ultrasound enhanced friction stir welding of aluminum and steel: Process and properties of EN AW 6061/DC04-Joints

In this work, the joining of aluminum to steel was conducted by ultrasound enhanced friction stir welding (USE-FSW). The power ultrasound was introduced into one of the metal sheets by an ultrasonic roll seam module synchronously to the FSW-process. The effect of the ultrasound on the resulting welds, their microstructure and their corrosion properties was investigated by light and scanning electron microscopy and corrosion investigations. The USE-FSW-joints showed less and smaller steel particles in the nugget zone as well as a thinner continuous intermetallic phase of FeAl₃ at the interface. The nondestructive testing method of computed laminography proved the observations made by optic microscopy due to non-porous joints for both techniques. Corrosion investigations showed only low corrosion current densities and no enhanced galvanic corrosion for the EN AW-6061/DC04-hybrid joints in sodium chloride solution.     

Model Scenarios for Direction-Selective Adaptive Antennas in Cellular Mobile Communication Systems – Scanning the Literature

Intelligent antennas offer the possibility of greatly increasing the capacity of cellular mobile radio systems. We give a comprehensive overview of the literature concerning model scenarios for applications of direction-selective intelligent antennas. Measurement campaigns and simplified models are described that have been derived from these measurements or from physical considerations. Furthermore, directional fading simulators are reviewed which are essential for testing of smart antenna systems.     

Analysis of In-Room mm-Wave Propagation: Directional Channel Measurements and Ray Tracing Simulations

Frequency bands above 6 GHz are being considered for future 5G wireless systems because of the larger bandwidth availability and of the smaller wavelength, which can ease the implementation of high-throughput massive MIMO schemes. However, great challenges are around the corner at each implementation level, including the achievement of a thorough multi-dimensional characterization of the mm-wave radio channel, which represents the base for the realization of reliable and high-performance radio interfaces and system architectures. The main properties of the indoor radio channel at 70 GHz, including angular and temporal dispersion as well as an assessment of the major interaction mechanisms, are investigated in this study by means of UWB directional measurements and ray tracing simulations in a reference, small-indoor office environment.     

Phosphorylation of αS1-casein is regulated by different genes

Casein phosphorylation is a posttranslational modification catalyzed by kinase enzymes that attach phosphate groups to specific AA in the protein sequence. This modification is one of the key factors responsible for the stabilization of calcium phosphate nanoclusters in casein micelles and for the internal structure of the casein micelles. α_S1-Casein (α_s1-CN) is of special interest because it constitutes up to 40% of the total casein fraction in milk, and it has 2 common phosphorylation states, with 8 (α_S1-CN-8P) and 9 (α_S1-CN-9P) phosphorylated serine residues. Factors affecting this variation in the degree of phosphorylation are not currently known. The objective of this research was to determine the genetic background of α_S1-CN-8P and α_S1-CN-9P. The genetic and phenotypic correlation between α_S1-CN-8P and α_S1-CN-9P was low (0.18 and 0.19, respectively). This low genetic correlation suggests a different genetic background. These differences were further investigated by means of a genome-wide association study, which showed that both α_S1-CN-8P and α_S1-CN-9P were affected by a region on Bos taurus autosome (BTA) 6, but only α_S1-CN-8P was affected by a region on BTA11 that contains the gene that encodes for β-lactoglobulin (β-LG), and only α_S1-CN-9P was affected by a region on BTA14 that contains the diacylglycerol acyltransferase 1 (DGAT1) gene. Estimated effects of β-LG protein genotypes showed that only α_S1-CN-8P was associated with the β-LG A/B polymorphism (g.1772G>A and g.3054C>T); the AA genotype of β-LG was associated with a lower concentration of α_S1-CN-8P (−0.32% wt/wt) than the BB genotype (+0.41% wt/wt). Estimated effects of DGAT1 K232A genotypes showed that only α_S1-CN-9P was associated with the DGAT1 gene polymorphism; DGAT1 AA genotype was associated with a higher α_S1-CN-9P concentration (+0.53% wt/wt) than the DGAT1 KK genotype (−0.44% wt/wt). The results give insight in phosphorylation of α_S1-CN-8P and α_S1-CN-9P, which seem to be regulated by a different set of genes.     

Decision support method to systematically evaluate first-level inspections of the functional status of check dams

First-level inspections could be provided by skilled volunteers or technicians to pre-screen the functional status of check dams. This paper discusses the design and testing of a support method in collaboration with the responsible technicians in evaluating inspection reports. Reports are based on linguistic rating scales that are systematically aggregated into indices by means of a multi-criteria TOPSIS method with fuzzy terms. The aggregation procedure is carried out for three parameters representing the structure’s status while highlighting any lack of completeness of inspection reports. The method was evaluated using inspection reports collected during a workshop in the Fella basin in the Italian Alps. The method allows the responsible technicians to set rules to categorise the aggregated indices in one of three levels, each corresponding with a course of action. Rules were useful to categorise the aggregated indices according to the structure’s status. Disagreements on rating defects suggest that a weighted aggregation procedure to calculate the indices might lead to overestimating or underestimating defects. Complementary data from historical inspections or remote sensing are required to initiate specific actions. The method can be applied to pre-screen different types of hydraulic structures after adaptation to the local conditions and functional requirements.