Nondestructive Online In Vitro Monitoring of Pre-Osteoblast Cell Proliferation Within Microporous Polymer Scaffolds

We present a system for the online, in vitro, nondestructive monitoring of tissue growth within microporous polymer scaffolds. The system is based on measuring the admittance of the sample over a frequency range of 10-200 MHz using an open-ended coaxial probe and impedance analyzer. The sample admittance is related to the sample complex permittivity (CP) by a quasi-static model of the probe's aperture admittance. A modified effective medium approximation is then used to relate the CP to the cell volume fraction. The change of cell volume fraction is used as a measure of tissue growth inside the scaffold. The system detected relative cell concentration differences between microporous polymer scaffolds seeded with 0.4, 0.45, 0.5, and 0.6 x 10⁶ pre-osteoblast cells. In addition, the pre-osteoblast proliferation within 56 scaffolds over 14 days was recorded by the system and a concurrent DNA assay. Both techniques produced cell proliferation curves that corresponded to those found in literature. Thus, our data confirmed that the new system can assess relative cell concentration differences in microporous scaffolds enabling online nondestructive tissue growth monitoring.     

Inquiry-based mobile learning in secondary school science education: A systematic review

Recent years have seen a growing call for inquiry-based learning in science education, and mobile technologies are perceived as increasingly valuable tools to support this approach. However, there is a lack of understanding of mobile technology-supported inquiry-based learning (mIBL) in secondary science education. More evidence-based, nuanced insights are needed into how using mobile technologies might facilitate students' engagement with various levels of inquiry and enhance their science learning. We, therefore, conducted a robust systematic literature review (SLR) of the research articles on mIBL in secondary school science education that have been published from 2000 to 2019. We reviewed and analysed 31 empirical studies (34 articles) to explore the types of mIBL, and the benefits and constraints of mIBL in secondary school science education. The findings of this SLR suggest new research areas for further exploration and provide implications for science teachers' selection, use and design of mIBL approaches in their teaching.     

Oxidation Of Iron And Manganese By Ozone

The oxidation of iron and manganese by ozone was studied in the laboratory. Model waters both with and without organic matter were used. Results showed iron to be very rapidly oxidized to an insoluble form in the absence of organic matter. However, in the presence of organic matter the iron was protected from oxidation by ozone and precipitation. The degree to which this occurred depended on the nature of the organic matter and the chemical environment at the time of mixing the iron stock and the dissolved organic matter.

Experiments with manganese allowed the determination of second order rate constants for the reaction of ozone with manganese at various pH values. The oxidation of manganese in the presence of organic matter occurred in competition with oxidation of the organic matter. As a result, high ozone doses were required to achieve the same degree of removal of manganese. An increase in bicarbonate alkalinity from 50 mg/L to 200 mg/L did not result in an acceleration of the manganese oxidation in the absence of organic matter. However, in the presence of organic matter, higher levels of bicarbonate created conditions that resulted in more complete oxidation of the manganese following total consumption of the dosed ozone.     

A numerical hydrodynamic and thermal characterization of an inter-strata liquid cooling solution for 3D ICs

A novel integrated thermal management solution is proposed to alleviate hot spots in a contemporary 3D IC architecture. The solution employs a series of integrated microchannels, interconnected through each stratum by through silicon fluidic vias (TSFVs), and permits the transfer of heat, via a coolant, from hot to cold zones. This microfluidic system is driven by an integrated AC electrokinetic pump embedded in the channel walls. Recent advancements in electrokinetic micropump technology have allowed greater increases in fluid velocity (mm/s) while operating within the voltage constraints of a 3D IC. This paper presents a 2D simulation of an electrokinetic micropump operating at V_pp = 1.5 V in a 40 μm channel and examines its velocity profile for six frequencies in the range 100 ≤ ω ≤ 100 MHz. An optimum frequency of 100 kHz was established within this range and this was further examined with a constant heat flux of 186 W/cm2 imposed on the wall for an inlet fluid temperature of 40°C. Temperature profiles are presented at the channel-silicon interface and compared with theory.     

The YouthMood Project: A cluster randomized controlled trial of an online cognitive behavioral program with adolescents.

The aim in the current study was to investigate the effectiveness of an online, self-directed cognitive–behavioral therapy program (MoodGYM) in preventing and reducing the symptoms of anxiety and depression in an adolescent school-based population. A cluster randomized controlled trial was conducted with 30 schools (N = 1,477) from across Australia, with each school randomly allocated to the intervention or wait-list control condition. At postintervention and 6-month follow-up, participants in the intervention condition had significantly lower levels of anxiety than did participants in the wait-list control condition (Cohen’s d = 0.15–0.25). The effects of the MoodGYM program on depressive symptoms were less strong, with only male participants in the intervention condition exhibiting significant reductions in depressive symptoms at postintervention and 6-month follow-up (Cohen’s d = 0.27–0.43). Although small to moderate, the effects obtained in the current study provide support for the utility of universal prevention programs in schools. The effectiveness of booster sessions should be explored in future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Magnetic properties of iron alloys

The purpose of this work was to compare the properties of high purity atomized iron powder compacts with conventional high purity irons and to show the effects of porosity on magnetic properties. It was found that if powders were hot repressed so that no porosity was present, the magnetic properties were as good as or better than conventional high purity irons, depending on the sintering conditions employed. Intrinsic properties were similar because the amount of iron available to magnetize was equivalent. Structure-sensitive properties depended on the grain size. If the compacts were sintered above the delta transition temperature, these properties were equivalent to the purest of the conventional high purity irons. As the compacts became less dense and more porosity was present, induction and remanent magnetization decreased linearly with density; resistivity increased. In the case of structure-sensitive properties, porosity restricted grain growth. Small, closely spaced pores caused the greatest degradation of properties. Equations were derived through regression analyses and were found to explain more than 90% of the data. The intrinsic properties: induction, remanent magnetization, and resistivity were all linear functions of the density. The maximum permeability and the coercive force were power functions of the mean grain size intercept. These equations provide a basis for design of magnetic components using P/M compacts. If the properties that are desired are known, the density or the grain size required may be calculated. From this, the powder and the processing conditions required can be established to provide the desired properties.     

Integration of Computational Models Inspired by Economics and Genetics

Multi-agent software systems can be modelled as complex dynamic systems in which agent adaptation and interaction occur continuously and concurrently. A genetics-inspired view has interaction occurring via exchange of agent characteristics encoded as genes, plus measures of success. An economics-inspired view has agent adaptation driven by changes in prices, and supply and demand. This paper describes work towards a synergistic combination of these views.     

An Overview of Web Services Security

Security and Web Services are consistently reported among the top technologies of interest to businesses. Concerns about security are a major deterrent to companies considering use of the technology. This paper attempts to give an overview of the current state of Web Services security. The main body of the paper is a tour through key concepts used in Web Services security. Examples based on software demonstrators built by the authors are used to explain how the ideas are used in combination to achieve particular aims. The state of play as regards standards is also reviewed. The concluding section gives some pointers as to active research topics. This revised version was published online in July 2006 with corrections to the Cover Date.