Structural and Bluish-White Luminescent Properties of Li+-Doped BPO4 as a Potential Environmentally Friendly Phosphor Material

Many efforts have been devoted to exploring novel luminescent materials that not contain expensive or toxic elements, or do not need a mercury vapor plasma source. In this paper, BPO4 and Li+-doped BPO4 powder samples were prepared by the Pechini-type sol-gel (PSG) process. The structure and optical properties of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), photoluminescence (PL) excitation and emission spectra, kinetic decay, and X-ray photoelectron spectra (XPS), respectively. It was found that PSG -derived Li+-doped BPO4 annealed at 960 degrees C exhibited bright bluish-white emission centered at 416 nm. The luminescence decay curves analysis indicates that each sample has two kinds of lifetimes (5.9 ns and 0.529 ms) and two types of kinetic decay behaviors which can be fitted into a single-exponential function and a double-exponential function, respectively.

Sol-gel-derived BPO4/Ba2+ as a new efficient and environmentally-friendly bluish-white luminescent material

In this paper, BPO4 and Ba2+-doped BPO4 powder samples were prepared by the sol-gel process using glycerol and poly(ethylene glycol) as additives. The structure and optical properties of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), diffuse reflection spectra, photoluminescence (PL) excitation and emission spectra, quantum yield, kinetic decay, and electron paramagnetic resonance (EPR), respectively. It was found that the undoped BPO4 showed a weak purple blue emission (409 nm, lifetime 6.4 ns) due to the carbon impurities involved in the host lattice. Doping Ba2+ into BPO4 resulted in oxygen-related defects as additional emission centers which enhanced the emission intensity greatly (> 10x) and shifted the emission to a longer-wavelength region (lambda(max) = 434 nm; chromaticity coordinates: x = 0.174, y = 0. 187) with a bluish-white color. The highest emission intensity was obtained ;when doping 6 mol % Ba2+ in BPO4, which has a quantum yield as high as 31%. The luminescent mechanisms of BPO4 and Ba2+-doped BPO4 were discussed in detail according to the existing models for silica-based materials.

Supporting the case for “progressive universalism” in health visiting: Scottish mothers and health visitors’ perspectives on targeting and rationing health visiting services, with a focus on the Lothian Child Concern Model.

Aims. To explore parents and professionals’ experience of family assessment in health visiting (public health nursing), with a focus on the Lothian Child Concern Model (LCCM). Background. Health visitors (HVs) currently assess families as requiring core, additional or intensive support, and offer support at a corresponding level. The majority of families are assessed as core and receive no pro-active support beyond the early days. Previous assessment tools, consisting of checklists, have been criticised as being ineffective in identifying a range of health needs and unacceptable to parents and HVs. The LCCM model was developed and introduced in the study area to promote a partnership approach with parents and assess strengths as well as difficulties in parents’ capacity to care for their child. Methods. Qualitative methods were used. Ten mothers and twelve HVs took part in individual semi-structured interviews. Results. Most mothers were aware of the assessment process but some felt that they were not involved in the decision making process. Explaining the assessment process to parents is problematic and not all HVs do so. The assessment process was stressful for some mothers. HVs find the model useful for structuring and documenting the assessment process. Many believe that most families benefit from some support, using public health approaches. Families are often assessed as core because there are insufficient resources to support all those who meet the criteria of the additional category, and managers assess caseloads in terms of families with child protection concerns. Conclusions. The study findings support the concept of “progressive universalism” which provides a continuum of intensity of support to families, depending on need. Mothers would like better partnership working with HVs. Relevance to clinical practice. The study endorses proposed policy changes to re-establish the public health role of HVs and to lower the threshold for families to qualify for support.

Friendly Virtual Machine: Leveraging a Feedback-Control Model for Application Adaptation

With the increased use of "Virtual Machines" (VMs) as vehicles that isolate applications running on the same host, it is necessary to devise techniques that enable multiple VMs to share underlying resources both fairly and efficiently. To that end, one common approach is to deploy complex resource management techniques in the hosting infrastructure. Alternately, in this paper, we advocate the use of self-adaptation in the VMs themselves based on feedback about resource usage and availability. Consequently, we define a "Friendly" VM (FVM) to be a virtual machine that adjusts its demand for system resources, so that they are both efficiently and fairly allocated to competing FVMs. Such properties are ensured using one of many provably convergent control rules, such as AIMD. By adopting this distributed application-based approach to resource management, it is not necessary to make assumptions about the underlying resources nor about the requirements of FVMs competing for these resources. To demonstrate the elegance and simplicity of our approach, we present a prototype implementation of our FVM framework in User-Mode Linux (UML)-an implementation that consists of less than 500 lines of code changes to UML. We present an analytic, control-theoretic model of FVM adaptation, which establishes convergence and fairness properties. These properties are also backed up with experimental results using our prototype FVM implementation.

TCP-friendly SIMD Congestion Control and Its Convergence Behavior

The increased diversity of Internet application requirements has spurred recent interests in flexible congestion control mechanisms. Window-based congestion control schemes use increase rules to probe available bandwidth, and decrease rules to back off when congestion is detected. The parameterization of these control rules is done so as to ensure that the resulting protocol is TCP-friendly in terms of the relationship between throughput and packet loss rate. In this paper, we propose a novel window-based congestion control algorithm called SIMD (Square-Increase/Multiplicative-Decrease). Contrary to previous memory-less controls, SIMD utilizes history information in its control rules. It uses multiplicative decrease but the increase in window size is in proportion to the square of the time elapsed since the detection of the last loss event. Thus, SIMD can efficiently probe available bandwidth. Nevertheless, SIMD is TCP-friendly as well as TCP-compatible under RED, and it has much better convergence behavior than TCP-friendly AIMD and binomial algorithms proposed recently.

A Spectrum of TCP-Friendly Window-Based Congestion Control Algorithms

The increased diversity of Internet application requirements has spurred recent interests in transport protocols with flexible transmission controls. In window-based congestion control schemes, increase rules determine how to probe available bandwidth, whereas decrease rules determine how to back off when losses due to congestion are detected. The parameterization of these control rules is done so as to ensure that the resulting protocol is TCP-friendly in terms of the relationship between throughput and loss rate. In this paper, we define a new spectrum of window-based congestion control algorithms that are TCP-friendly as well as TCP-compatible under RED. Contrary to previous memory-less controls, our algorithms utilize history information in their control rules. Our proposed algorithms have two salient features: (1) They enable a wider region of TCP-friendliness, and thus more flexibility in trading off among smoothness, aggressiveness, and responsiveness; and (2) they ensure a faster convergence to fairness under a wide range of system conditions. We demonstrate analytically and through extensive ns simulations the steady-state and transient behaviors of several instances of this new spectrum of algorithms. In particular, SIMD is one instance in which the congestion window is increased super-linearly with time since the detection of the last loss. Compared to recently proposed TCP-friendly AIMD and binomial algorithms, we demonstrate the superiority of SIMD in: (1) adapting to sudden increases in available bandwidth, while maintaining competitive smoothness and responsiveness; and (2) rapidly converging to fairness and efficiency.

A Spectrum of TCP-friendly Window-Based Congestion Control Algorithms

The increasing diversity of Internet application requirements has spurred recent interest in transport protocols with flexible transmission controls. In window-based congestion control schemes, increase rules determine how to probe available bandwidth, whereas decrease rules determine how to back off when losses due to congestion are detected. The control rules are parameterized so as to ensure that the resulting protocol is TCP-friendly in terms of the relationship between throughput and loss rate. This paper presents a comprehensive study of a new spectrum of window-based congestion controls, which are TCP-friendly as well as TCP-compatible under RED. Our controls utilize history information in their control rules. By doing so, they improve the transient behavior, compared to recently proposed slowly-responsive congestion controls such as general AIMD and binomial controls. Our controls can achieve better tradeoffs among smoothness, aggressiveness, and responsiveness, and they can achieve faster convergence. We demonstrate analytically and through extensive ns simulations the steady-state and transient behavior of several instances of this new spectrum.

Decision support systems for eco-friendly electronic products

This paper discusses an optimisation based decision support system and methodology for electronic packaging and product design and development which is capable of addressing in efficient manner specified environmental, reliability and cost requirements. A study which focuses on the design of a flip-chip package is presented. Different alternatives for the design of the flip-chip package are considered based on existing options for the applied underfill and volume of solder material used to form the interconnects. Variations in these design input parameters have simultaneous effect on package aspects such as cost, environmental impact and reliability. A decision system for the design of the flip-chip that uses numerical optimisation approach is used to identify the package optimal specification which satisfies the imposed requirements. The reliability aspect of interest is the fatigue of solder joints under thermal cycling. Transient nonlinear finite element analysis (FEA) is used to simulate the thermal fatigue damage in solder joints subject to thermal cycling. Simulation results are manipulated within design of experiments and response surface modelling framework to provide numerical model for reliability which can be used to quantify the package reliability. Assessment of the environmental impact of the package materials is performed by using so called Toxic Index (TI). In this paper we demonstrate the evaluation of the environmental impact only for underfill and lead-free solder materials. This evaluation is based on the amount of material per flip-chip package. Cost is the dominant factor in contemporary flip-chip packaging industry. In the optimisation based decision support system for the design of the flip-chip package, cost of materials which varies as a result of variations in the design parameters is considered.

Template-free environmentally friendly synthesis and characterization of unsupported tungsten carbide with a controllable porous framework

Tungsten carbide (WC) with controlled pore size distribution was synthesized using a novel “precursor reassembly” method. The precursor crystal was assembled by mixing ammonium metatungstate (AMT) and ammonium carbonate (AC) in distilled water, followed by hydrothermal treatment. The mesostructure, crystal phase, and amount of deposited graphitic carbon can be conveniently tuned by controlling carburizing atmosphere (CO or a CO/H2 mixture). Moreover, the influence of precursor preparation (AMT/AC mass ratio and hydrothermal temperature) on the materials was also investigated. The resultant materials with low carbon content were mesoporous WCs, which showed high specific surface areas (11.3-20.4 m2 g-1) and adjustable pore-size distributions (average pore size: 15.3-22.3 nm). A mechanism for the formation of WC with a controllable porous framework is proposed. Finally, cyclic voltammetry was used to investigate the inference of different mesoporous structure.

Design considerations for the autism spectrum disorder-friendly Key Stage 1 classroom

There is a growing consensus that an appropriate classroom environment will aid the performance of the pupil with autism spectrum disorder (ASD). There are, however, very few design guidelines available when considering ASD and the school environment. Such guidelines that do exist tend only to be in general terms. Therefore, this article seeks to highlight design considerations specifically for the ASD-friendly Key Stage 1 (age five to eight) classroom. It will first highlight some of the challenges for those with autism spectrum disorder in a school environment and the triad of challenges faced by architects and designers when considering ASD-friendly classroom design. It will then go on to describe the findings and results of a two-year study carried out in conjunction with the ASD teaching staff of Northern Ireland's Southern Education and Library Board. These consist of 16 specific design considerations for the Key Stage 1 ASD-friendly classroom applicable to all classrooms for pupils between five and eight years of age.