Aluminum-assisted crystallization and p-type doping of polycrystalline Si

Aluminum-doped p-type polycrystalline silicon thin films have been synthesized on glass substrates using an aluminum target in a reactive SiH 4+Ar+H2 gas mixture at a low substrate temperature of 300∈°C through inductively coupled plasma-assisted RF magnetron sputtering. In this process, it is possible to simultaneously co-deposit Si-Al in one layer for crystallization of amorphous silicon, in contrast to the conventional techniques where alternating metal and amorphous Si layers are deposited. The effect of aluminum target power on the structural and electrical properties of polycrystalline Si films is analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and Hall-effect analysis. It is shown that at an aluminum target power of 100 W, the polycrystalline Si film features a high crystalline fraction of 91%, a vertically aligned columnar structure, a sheet resistance of 20.2 kΩ/□ and a hole concentration of 6.3×1018 cm-3. The underlying mechanism for achieving the semiconductor-quality polycrystalline silicon thin films at a low substrate temperature of 300∈°C is proposed.

The cost-effectiveness of total laparoscopic hysterectomy compared to total abdominal hysterectomy for the treatment of early stage endometrial cancer

Objective To summarise how costs and health benefits will change with the adoption of total laparoscopic hysterectomy compared to total abdominal hysterectomy for the treatment of early stage endometrial cancer. Design Cost-effectiveness modelling using the information from a randomised controlled trial. Participants Two hypothetical modelled cohorts of 1000 individuals undergoing total laparoscopic hysterectomy and total abdominal hysterectomy. Outcome measures Surgery costs; hospital bed days used; total healthcare costs; quality-adjusted life years; and net monetary benefits. Results For 1000 individuals receiving total laparoscopic hysterectomy surgery, the costs were $509 575 higher, 3548 hospital fewer bed days were used and total health services costs were reduced by $3 746 221. There were 39.13 more quality-adjusted life years for a 5 year period following surgery. Conclusions The adoption of total laparoscopic hysterectomy is almost certainly a good decision for health services policy makers. There is 100% probability that it will be cost saving to health services, a 86.8% probability that it will increase health benefits and a 99.5% chance that it returns net monetary benefits greater than zero.

Nanocrystalline vanadium oxide films synthesized by plasma-assisted reactive rf sputtering deposition

Plasma-assisted reactive rf magnetron sputtering deposition is used to fabricate vanadium oxide films on glass, silica and silicon substrates. The process conditions are optimized to synthesize phase-pure vanadium pentoxide (V2O5) featuring a nanocrystalline structure with the predominant (0 0 1) crystallographic orientation, surface morphology with rod-like nanosized grains and very uniform (the non-uniformity does not exceed 4%) coating thickness over large surface areas. The V2O5 films also show excellent and temperature-independent optical transmittance in a broad temperature range (20-95 °C). The results are relevant to the development of smart functional coatings with temperature-tunable properties. © 2007 IOP Publishing Ltd.

Nanosphere monolayer-templated, ion-assisted nanofeature etching in dielectric materials : a numerical simulation of nanoscale ion flux topography

The results of numerical simulations of nanometer precision distributions of microscopic ion fluxes in ion-assisted etching of nanoscale features on the surfaces of dielectric materials using a self-assembled monolayer of spherical nanoparticles as a mask are presented. It is shown that the ion fluxes to the substrate and nanosphere surfaces can be effectively controlled by the plasma parameters and the external bias applied to the substrate. By proper adjustment of these parameters, the ion flux can be focused onto the areas uncovered by the nanospheres. Under certain conditions, the ion flux distributions feature sophisticated hexagonal patterns, which may lead to very different nanofeature etching profiles. The results presented are generic and suggest viable ways to overcome some of the limitations of the existing plasma-assisted nanolithography.

Ion-assisted functional monolayer coating of nanorod arrays in hydrogen plasmas

Uniformity of postprocessing of large-area, dense nanostructure arrays is currently one of the greatest challenges in nanoscience and nanofabrication. One of the major issues is to achieve a high level of control in specie fluxes to specific surface areas of the nanostructures. As suggested by the numerical experiments in this work, this goal can be achieved by manipulating microscopic ion fluxes by varying the plasma sheath and nanorod array parameters. The dynamics of ion-assisted deposition of functional monolayer coatings onto two-dimensional carbon nanorod arrays in a hydrogen plasma is simulated by using a multiscale hybrid numerical simulation. The numerical results show evidence of a strong correlation between the aspect ratios and nanopattern positioning of the nanorods, plasma sheath width, and densities and distributions of microscopic ion fluxes. When the spacing between the nanorods and/or their aspect ratios are larger, and/or the plasma sheath is wider, the density of microscopic ion current flowing to each of the individual nanorods increases, thus reducing the time required to apply a functional monolayer coating down to 11 s for a 7-μm-wide sheath, and to 5 s for a 50-μm-wide sheath. The computed monolayer coating development time is consistent with previous experimental reports on plasma-assisted functionalization of related carbon nanostructures [B. N. Khare et al., Appl. Phys. Lett. 81, 5237 (2002)]. The results are generic in that they can be applied to a broader range of plasma-based processes and nanostructures, and contribute to the development of deterministic strategies of postprocessing and functionalization of various nanoarrays for nanoelectronic, biomedical, and other emerging applications.

Transforming the future of treatment for ovarian cancer

As for many other cancers, metastasis is the leading cause of death of patients with ovarian cancer. Vigorous basic and clinical research is being performed to initiate more efficacious treatment strategies to improve the poor outcome of women with this cancer. Current treatment for ovarian cancer includes advanced cyto-reductive surgery and traditional platinum and taxane combined chemotherapy. Clinical trials using novel cytotoxic reagents and tyrosine kinase inhibitors have also been progressing. In parallel, the application of robust unbiased high throughput research platforms using transcriptomic and proteomic approaches has identified that not only individual cell signalling pathways, but a network of molecular pathways, play an important role in the biology of ovarian cancer. Furthermore, intensive genomic and epigenetic analyses have also revealed single nucleotide polymorphisms associated with risk and/or aetiology of this cancer including patient response to treatment. Taken together, these approaches, that are advancing our understanding, will have an impact on the generation of new therapeutic approaches and strategies for improving the outcome and quality of life of patients with ovarian cancer in the near future.

Nanoparticle manipulation in plasma-assisted nanofabrication of electron field emitters based on single crystalline carbon nanotip patterns

Nanoparticle manipulation by various plasma forces in near-substrate areas of the Integrated Plasma-Aided Nanofabrication Facility (IPANF) is investigated. In the IPANF, high-density plasmas of low-temperature rf glow discharges are sustained. The model near-substrate area includes a variable-length pre-sheath, where a negatively charged nanoparticle is accelerated, and a self-consistent collisionless sheath with a repulsive electrostatic potential. Conditions enabling the nanoparticle to overcome the repulsive barrier and deposit onto the substrate are investigated numerically and experimentally. Under certain conditions the momentum gained by the nanoparticle in the pre-sheath area appears to be sufficient for the driving ion drag force to outbalance the repulsive electrostatic and thermophoretic forces. Numerical results are applied for the explanation of size-selective nanoparticle deposition in the Ar+H2+CH4 plasma-assisted chemical vapor deposition of various carbon nanostructure patterns for electron field emitters and are cross-referenced by the field emission scanning electron microscopy. It is shown that the nanoparticles can be efficiently manipulated by the temperature gradient-controlled thermophoretic force. Experimentally, the temperature gradients in the near-substrate areas are measured in situ by means of the temperature gradient probe and related to the nanofilm fabrication conditions. The results are relevant to plasma-assisted synthesis of numerous nanofilms employing structural incorporation of the plasma-grown nanoparticles, including but not limited to nanofabrication of ordered single-crystalline carbon nanotip arrays for electron field emission applications.

Network-targeted combination therapy : a new concept in cancer treatment

Toxicity is a major concern for anti-neoplastic drugs, with much of the existing pharmacopoeia being characterized by a very narrow therapeutic index. 'Network-targeted' combination therapy is a promising new concept in cancer therapy, whereby therapeutic index might be improved by targeting multiple nodes in a cell's signaling network, rather than a single node. Here, we examine the potential of this novel approach, illustrating how therapeutic benefit could be achieved with smaller doses of the necessary agents.

Cutting the Gordian knot of futility : a case for law reform on unilateral withholding and withdrawal of potentially life-sustaining treatment

In this paper, we propose law reform with respect to the unilateral withholding or withdrawal of potentially life-sustaining treatment in Australia and New Zealand. That is, where a doctor withholds or withdraws potentially life-sustaining treatment without consent from a patient or a patient’s substitute decision-maker (where the patient lacks capacity), or authorisation from a court or tribunal, or by operation of a statute or justifiable government or institutional policy. Our proposal is grounded in the core values that do (or should) underpin a regulatory framework on an issue such as this; these values are drawn from existing commitments made by Australia and New Zealand through legislation, the common law, and conventions and treaties. It is also grounded in a critical review of the law on unilateral withholding and withdrawal as well as the legal context within which this issue sits in Australasia. We argue that the current law is inconsistent with the core values and develop a proposal for a legal response to this issue that more closely aligns with the core values it is supposed to serve.

Withholding and withdrawing life-sustaining medical treatment

• At common law, a competent adult can refuse life-sustaining medical treatment, either contemporaneously or through an advance directive which will operate at a later time when the adult’s capacity is lost. • Legislation in most Australian jurisdictions also provides for a competent adult to complete an advance directive that refuses life-sustaining medical treatment. • At common law, a court exercising its parens patriae jurisdiction can consent to, or authorise, the withdrawal or withholding of life-sustaining medical treatment from an adult or child who lacks capacity if that is in the best interests of the person. A court may also declare that the withholding or withdrawal of treatment is lawful. • Guardianship legislation in all jurisdictions allows a substitute decision-maker, in an appropriate case, to refuse life-sustaining medical treatment for an adult who lacks capacity. • In terms of children, a parent may refuse life-sustaining medical treatment for his or her child if it is in the child’s best interests. • While a refusal of life-sustaining medical treatment by a competent child may be valid, this decision can be overturned by a court. • At common law and generally under guardianship statutes, demand for futile treatment need not be complied with by doctors.

Compatibility of stormwater treatment performance data between different geographical areas

Using a case study approach, this paper presents a robust methodology for assessing the compatibility of stormwater treatment performance data between two geographical regions in relation to a treatment system. The desktop analysis compared data derived from a field study undertaken in Florida, USA, with South East Queensland (SEQ) rainfall and pollutant characteristics. The analysis was based on the hypothesis that when transposing treatment performance information from one geographical region to another, detailed assessment of specific rainfall and stormwater quality parameters is required. Accordingly, characteristics of measured rainfall events and stormwater quality in the Florida study were compared with typical characteristics for SEQ. Rainfall events monitored in the Florida study were found to be similar to events that occur in SEQ in terms of their primary characteristics of depth, duration and intensity. Similarities in total suspended solids (TSS) and total nitrogen (TN) concentration ranges for Florida and SEQ suggest that TSS and TN removal performances would not be very different if the treatment system is installed in SEQ. However, further investigations are needed to evaluate the treatment performance of total phosphorus (TP). The methodology presented also allows comparison of other water quality parameters.

Regional trade-offs between mine water and energy use : a water treatment case study

The mining industry faces concurrent pressures of reducing water use, energy consumption and greenhouse gas (GHG) emissions in coming years. However, the interactions between water and energy use, as well as GHG e missions have largely been neglected in modelling studies to date. In addition, investigations tend to focus on the unit operation scale, with little consideration of whole-of-site or regional scale effects. This paper presents an application of a hierarchical systems model (HSM) developed to represent water, energy and GHG emissions fluxes at scales ranging from the unit operation, to the site level, to the regional level. The model allows for the linkages between water use, energy use and GHG emissions to be examined in a fl exible and intuitive way, so that mine sites can predict energy and emissions impacts of water use reduction schemes and vice versa. This paper examines whether this approach can also be applied to the regional scale with multiple mine sites. The model is used to conduct a case study of several coal mines in the Bowen Basin, Australia, to compare the utility of centralised and decentralised mine water treatment schemes. The case study takes into account geographical factors (such as water pumping distances and elevations), economic factors (such as capital and operating cost curves for desalination treatment plants) and regional factors (such as regionally varying climates and associated variance in mine water volumes and quality). The case study results indicate that treatment of saline mine water incurs a trade-off between water and energy use in all cases. However, significant cost differences between centralised and decentralised schemes can be observed in a simple economic analysis. Further research will examine the possibility for deriving model up-scaling algorithms to reduce computational requirements.

A review on solar assisted heat pump systems in Singapore

A solar assisted heat pump is used for different applications, such as, water heating, drying and air conditioning. The unglazed evaporator-collector enables to absorb both solar energy and ambient energy due to low operating temperature. Three different systems are described: solar assisted heat pump system for hot water using an unglazed evaporator collector; solar assisted heat pump for hot water and drying, where evaporator collector and air collector are used; an integrated solar heat pump system making use of solar and ambient energy, and air-con waste heat. Unlike conventional collector, evaporator collector was found to have higher efficiency, 80% to 90%, and the coefficient of performance attained a value as high as 8.0. The integrated system leads to a reduction of global warming, as it uses solar energy, ambient energy and air-con waste heat.

Desalination with a solar-assisted heat pump : an economic optimization

The solar-assisted heat pump (SAHP) desalination, based on the Rankin cycle, operates in low temperature and utilizes both solar and ambient energy. An experimental SAHP desalination system has been constructed at the National University of Singapore, Singapore. The system consisted of two main sections: an SAHP and a water distillation section. Experiments were carried out under the different meteorological condition of Singapore and results showed that the system had a performance ratio close to 1.3. The heat pump has a coefficient of performance of about 8, with solar collector efficiencies of 80% and 60% for evaporator and liquid collectors, respectively. Economic analysis showed that at a production rate of 900 L/day and an evaporator collector area of around 70m2 will have a payback period of about 3.5 years.

Mathematical modelling and experimental validation of solar assisted heat pump system

Singapore is located at the equator, with abundant supply of solar radiation, relatively high ambient temperature and relative humidity throughout the year. The meteorological conditions of Singapore are favourable for efficient operation of solar energy based systems. Solar assisted heat pump systems are built on the roof-top of National University of Singapore’s Faculty of Engineering. The objectives of this study include the design and performance evaluation of a solar assisted heat-pump system for water desalination, water heating and drying of clothes. Using MATLAB programming language, a 2-dimensional simulation model has been developed to conduct parametric studies on the system. The system shows good prospect to be implemented in both industrial and residential applications and would give new opportunities in replacing conventional energy sources with green renewable energy.