Growth of thin films of molybdenum and tungsten oxides by combustion CVD using aqueous precursor solutions

Using combustion chemical vapour deposition, layers of molybdenum and tungsten oxides have been deposited on glass and silicon at low temperatures. Inexpensive ammonium salts of molybdate and metatungstate ions were used as precursors and were delivered to the coating flame as an aqueous solution using a nebuliser. The resulting films were analysed by scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), Rutherford backscattering (RBS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). These indicate that the films are continuous, moderately smooth and consist of amorphous, disordered molybdenum and tungsten trioxides

What is prosumerism for? Exploring the normative dimensions of decentralised energy transitions

Energy systems are in transformation towards increasingly renewable, decentralised, demand responsive and smart configurations. This has led to advocacy of the ‘prosumer’ phenomenon: characterised by actors who both consume and produce renewable energy. In parallel a range of prosumer business models are emerging, governed by a range of market, municipal and community actors. Through a series of semi-structured interviews, focus groups and documentary analysis - centred on a case study of Bristol in the UK - this paper critically evaluates the normative dimensions of prosumer business models, modes of governance and understandings of value. We discuss how competing ‘value logics’ are present within imagined futures of prosumer-ism, and through a novel conceptual framework, how these modes of governance may lead to divergent material outcomes in a decentralised energy transition. We argue that a more explicit recognition of competing theories of value, agency and change is needed in future discussions of prosumer-ism

A comparison of the sensitivities of detection of Plasmodium falciparum gametocytes by magnetic fractionation, thick blood film microscopy, and RT-PCR

<p>Abstract</p> <p>Background</p> <p>The magnetic properties of <it>Plasmodium</it>-infected erythrocytes have been exploited for different clinical and research purposes. A recent study in a rural clinical setting in Papua New Guinea has demonstrated that <it>Plasmodium falciparum </it>gametocyte detection is facilitated by magnetic deposition microscopy but no study has yet determined the relative sensitivity and limit of detection of a magnetic fractionation technique. The present study compares the detection limit and sensitivity of a technique based on the use of commercially available magnetic fractionation columns with those for thick blood film microscopy and reverse transcriptase polymerase chain reaction (RT-PCR) methods.</p> <p>Methods</p> <p>Gametocyte detection in six series of dilutions of cultured <it>P. falciparum </it>parasites with known gametocytaemia was conducted using magnetic fractionation, thick blood film, and RT-PCR techniques.</p> <p>Results</p> <p>The preparations obtained by the magnetic fractionation method were of thin film quality allowing easy gametocyte identification by light microscopy. Magnetic fractionation had a higher sensitivity and approximately two orders of magnitude better limit of detection than thick blood film microscopy. Gametocytes were also more readily detectable on the magnetically fractionated preparations. Magnetic fractionation had a similar limit of detection to that of RT-PCR.</p> <p>Conclusion</p> <p>Magnetic fractionation is a highly sensitive and convenient method for gametocyte detection in comparison with the standard thick blood film and RT-PCR methods, and could readily be adapted to field application.</p

Parameterization of high magnetic field gradient fractionation columns for applications with Plasmodium falciparum infected human erythrocytes

<p>Abstract</p> <p>Background</p> <p>Magnetic fractionation of erythrocytes infected with <it>Plasmodium falicparum </it>has several research uses including enrichment of infected cells from parasite cultures or enhanced detection of <it>P. falciparum </it>gametocytes. The aim of the present study was to quantitatively characterize the magnetic fractionation process and thus enable optimization of protocols developed for specific uses.</p> <p>Methods</p> <p>Synchronized cultures of <it>P. falciparum </it>parasites incubated with human erythrocytes were magnetically fractionated with commercially available columns. The timing of the fractionation experiments was such that the parasites were in second half of their erythrocytic life cycle with parasite densities ranging from 1 to 9%. Fractionations were carried out in a single pass through the columns. Cells were enumerated and differentiated in the initial samples as well as in the positive and negative fractions. The capture of cells by the fractionation column was described by a saturation binding model.</p> <p>Results</p> <p>The magnetic binding affinity to the column matrix was approximately 350 times greater for infected cells compared with uninfected cells. The purity of infected cells in the captured fraction was generally >80% but decreased rapidly (to less than 50%) when the number of infected cells that passed through the column was substantially decreased (to less than 9 ± 5 × 10⁵cells). The distribution of captured parasite developmental stages shifted to mature stages as the number of infected cells in the initial samples and flow rate increased. The relationship between the yield of infected cells in the captured fraction and flow rate of cells conformed to a complementary cumulative log-normal equation with flow rates >1.6 × 10⁵cells per second resulting in yields <50%.</p> <p>Conclusions</p> <p>A detailed quantitative analysis of a batchwise magnetic fractionation process for malaria infected erythrocytes using high gradient magnetic fractionation columns was performed. The models applied in this study allow the prediction of capture efficiency if the initial infected cell concentration and the flow rate are known.</p

On the Hardness of SAT with Community Structure

Recent attempts to explain the effectiveness of Boolean satisfiability (SAT) solvers based on conflict-driven clause learning (CDCL) on large industrial benchmarks have focused on the concept of community structure. Specifically, industrial benchmarks have been empirically found to have good community structure, and experiments seem to show a correlation between such structure and the efficiency of CDCL. However, in this paper we establish hardness results suggesting that community structure is not sufficient to explain the success of CDCL in practice. First, we formally characterize a property shared by a wide class of metrics capturing community structure, including "modularity". Next, we show that the SAT instances with good community structure according to any metric with this property are still NP-hard. Finally, we study a class of random instances generated from the "pseudo-industrial" community attachment model of Gir\'aldez-Cru and Levy. We prove that, with high probability, instances from this model that have relatively few communities but are still highly modular require exponentially long resolution proofs and so are hard for CDCL. We also present experimental evidence that our result continues to hold for instances with many more communities. This indicates that actual industrial instances easily solved by CDCL may have some other relevant structure not captured by the community attachment model.Comment: 23 pages. Full version of a SAT 2016 pape

A comparative study of a flow-cytometry-based assessment of in vitro Plasmodium falciparum drug sensitivity

<p>Abstract</p> <p>Background</p> <p>Recently developed Sybr Green-based <it>in vitro Plasmodium falciparum </it>drug sensitivity assays provide an attractive alternative to current manual and automated methods. The present study evaluated flow cytometry measurement of DNA staining with Sybr Green in comparison with the <it>P. falciparum </it>lactate dehydrogenase assay, the tritiated hypoxanthine incorporation assay, a previously described Sybr Green based plate reader assay and light microscopy.</p> <p>Methods</p> <p>All assays were set up in standardized format in 96-well plates. The 50% inhibitory concentrations (IC₅₀) of chloroquine, mefloquine and dihydroartemisinin against the laboratory adapted <it>P. falciparum </it>strains 3D7, E8B, W2mef and Dd2 were determined using each method.</p> <p>Results</p> <p>The resolution achieved by flow cytometry allowed quantification of the increase in individual cell DNA content after an incubation period of only 24 h. Regression, and Bland and Altman analyses showed that the IC₅₀values determined using the flow cytometry assay after 24 h agreed well with those obtained using the hypoxanthine incorporation assay, the <it>P. falciparum </it>lactate dehydrogenase assay, the Sybr Green plate reader assay and light microscopy. However the values obtained with the flow cytometry assay after 48 h of incubation differed significantly from those obtained with the hypoxanthine incorporation assay, and the <it>P. falciparum </it>lactate dehydrogenase assay at low IC₅₀values, but agreed well with the Sybr Green plate reader assay and light microscopy.</p> <p>Conclusions</p> <p>Although flow cytometric equipment is expensive, the necessary reagents are inexpensive, the procedure is simple and rapid, and the cell volume required is minimal. This should allow field studies using fingerprick sample volumes.</p

Prosumers in the post subsidy era: an exploration of new prosumer business models in the UK.

This paper explores the evolving renewable energy ‘prosumer’ phenomenon in the United Kingdom (UK). It identifies and evaluates how prosumer business models can exist beyond direct subsidy and the range of prosumer business model archetypes currently in operation. Through a series of in-depth interviews and document analysis, the paper identifies the key opportunities and challenges for these innovative energy business models. The analysis shows that recent developments in technology such as the diffusion of smart meters, li-ion batteries, peer-to-peer trading platforms and electric vehicles are opening up a range of new value propositions, which in turn are beginning to be exploited by a range of new business models. In many cases the regulatory, financing and institutional governance landscape of the UK lags behind, however, inhibiting these emerging business models. Moreover, these business models rely on managing a complex set of values for consumers that reach deeper into their lives than traditional tariffs. Thus, successful business models must manage this complexity if they are to be adopted by the disengaged majority. Energy policy and energy practitioners can leverage these emerging trends in service of a low carbon energy transition by adopting ‘ten principles’ of prosumerism; and six UK policy recommendations

Maintenance Requirements of Implant Supported Fixed Prostheses Opposed by Either Implant Supported Fixed Prostheses or Natural Teeth: 5 Years Results

AIM: To compare the maintenance requirements of implant supported fixed prostheses opposed by implant supported fixed prostheses natural teeth or complete dentures. METHOD: The maintenance requirements were obtained by examining the dental records of 15 people, of whom 6 were edentulous in both arches and 9 edentulous in one arch. The results were compared to those obtained from 22 edentulous people in whom implants had been used in the mandible (control group). All the patients were treated with Nobel Biocare implants using standard implant and prosthetic protocols. RESULTS: The main maintenance requirement was the need to repair part of the superstructure. The artificial teeth and the acrylic resin had to be repaired on 44 occasions in the group with implants in both jaws and 14 occasions in the group with implants opposed by natural teeth. This compared with 2 occasions in the control group. Similarly the group with implants in both jaws were more likely to fracture the gold alloy framework, an event which occurred on 6 occasions. The Kruskal- Wallis one way analysis of variance on ranks was used to identify significant differences and Dunn’s method of All Pairwise Multiple Comparison Procedures was used to distinguish which group differed from the other. The group with implants in both jaws was significantly different to the other two groups in relation to the higher incidence of fracture of the teeth and acrylic resin superstructure (p<0.0001) and fracture of the gold alloy framework (p = 0.0002). CONCLUSION: The maintenance requirements of implant supported fixed prostheses opposed by implant supported fixed prostheses are much greater than when opposed by natural teeth or complete dentures