Showing papers by "Queen's University Belfast published in 2005"
TL;DR: A surface plasmon polariton (SPP) is an electromagnetic excitation existing on the surface of a good metal, whose electromagnetic field decays exponentially with distance from the surface.
2,211 citations
TL;DR: It is shown that factor H (HF1), the major inhibitor of the alternative complement pathway, accumulates within drusen and is synthesized by the retinal pigmented epithelium, implicating HF1 function in the pathogenetic mechanisms underlying AMD.
Abstract: Age-related macular degeneration (AMD) is the most frequent cause of irreversible blindness in the elderly in developed countries. Our previous studies implicated activation of complement in the formation of drusen, the hallmark lesion of AMD. Here, we show that factor H (HF1), the major inhibitor of the alternative complement pathway, accumulates within drusen and is synthesized by the retinal pigmented epithelium. Because previous linkage analyses identified chromosome 1q25-32, which harbors the factor H gene (HF1/CFH), as an AMD susceptibility locus, we analyzed HF1 for genetic variation in two independent cohorts comprised of ≈900 AMD cases and 400 matched controls. We found association of eight common HF1 SNPs with AMD; two common missense variants exhibit highly significant associations (I62V, χ2 = 26.1 and P = 3.2 × 10-7 and Y402H, χ2 = 54.4 and P = 1.6 × 10-13). Haplotype analysis reveals that multiple HF1 variants confer elevated or reduced risk of AMD. One common at-risk haplotype is present at a frequency of 50% in AMD cases and 29% in controls [odds ratio (OR) = 2.46, 95% confidence interval (1.95-3.11)]. Homozygotes for this haplotype account for 24% of cases and 8% of controls [OR = 3.51, 95% confidence interval (2.13-5.78)]. Several protective haplotypes are also identified (OR = 0.44-0.55), further implicating HF1 function in the pathogenetic mechanisms underlying AMD. We propose that genetic variation in a regulator of the alternative complement pathway, when combined with a triggering event, such as infection, underlie a major proportion of AMD in the human population.
2,012 citations
TL;DR: The signalling pathways involved in regulating tumour cell response to chemotherapy more completely than ever before are characterized, which will facilitate the future development of rational combined chemotherapy regimens, in which the newer targeted therapies are used in combination with cytotoxic drugs to enhance chemotherapy activity.
Abstract: Resistance to chemotherapy limits the effectiveness of anti-cancer drug treatment. Tumours may be intrinsically drug-resistant or develop resistance to chemotherapy during treatment. Acquired resistance is a particular problem, as tumours not only become resistant to the drugs originally used to treat them, but may also become cross-resistant to other drugs with different mechanisms of action. Resistance to chemotherapy is believed to cause treatment failure in over 90% of patients with metastatic cancer, and resistant micrometastic tumour cells may also reduce the effectiveness of chemotherapy in the adjuvant setting. Clearly, if drug resistance could be overcome, the impact on survival would be highly significant. This review focuses on molecular mechanisms of drug resistance that operate to reduce drug sensitivity in cancer cells. Drug resistance can occur at many levels, including increased drug efflux, drug inactivation, alterations in drug target, processing of drug-induced damage, and evasion of apoptosis. Advances in DNA microarray and proteomic technology, and the ongoing development of new targeted therapies have opened up new opportunities to combat drug resistance. We are now able to characterize the signalling pathways involved in regulating tumour cell response to chemotherapy more completely than ever before. This will facilitate the future development of rational combined chemotherapy regimens, in which the newer targeted therapies are used in combination with cytotoxic drugs to enhance chemotherapy activity. The ability to predict response to chemotherapy and to modulate this response with targeted therapies will permit selection of the best treatment for individual patients.
1,416 citations
TL;DR: The ideas and experimental results within 350 references are marshalled to illustrate the design bases and application potential of molecular luminescent sensing and switching devices that have appeared since the turn of the century as mentioned in this paper.
1,032 citations
TL;DR: This study demonstrates that systematic design and modulation of the surface charge and particle size of chitosan-TPP nanoparticles can be readily achieved with the right control of critical processing parameters, especially the chitOSan to TPP weight ratio.
813 citations
TL;DR: In this article, the electrical conductivity and linear viscoelastic behavior of polyethylene (PE) multiwalled carbon nanotubes (MWCNTs) with weight fractions ranging from 0.1 to 10 wt% were prepared by melt blending using a mini-twin screw extruder.
796 citations
TL;DR: In this paper, a two-part paper aims to address the question of whether or not entrepreneurship can be taught, which has led to an ongoing debate in the entrepreneurship academy about whether we can actually teach individuals to be entrepreneurs.
Abstract: Purpose – Despite a growing body of literature in the field, there is still considerable uncertainty as to whether entrepreneurs are born are made, which has led to an ongoing debate in the entrepreneurship academy about whether we can actually teach individuals to be entrepreneurs. With this in mind, this two‐part paper aims to address the question of whether or not entrepreneurship can be taught.Design/methodology/approach – Part I of the paper dealt with the importance of entrepreneurship in a modern and constantly changing environment; the various ways in which entrepreneurship programmes and courses can be categorised, and the objectives, content and delivery of programmes. The second part of the paper, which is presented in this issue, deals with the topic of determining and measuring programme effectiveness.Findings – Despite the growth in entrepreneurship education and training programmes, the paper reports that little uniformity can be found. Attention is drawn to the art and the science of entre...
750 citations
TL;DR: It is demonstrated that LRRK2 G2019S accounts for parkinsonism in several families within Europe and North America, highlighting the fact that a proportion of clinically typical, late-onset PD cases have a genetic basis.
Abstract: Autosomal dominant parkinsonism has been attributed to pathogenic amino acid substitutions in leucine-rich repeat kinase 2 (LRRK2). By sequencing multiplex families consistent with a PARK8 assignment, we identified a novel heterozygous LRRK2 mutation. A referral sample of 248 affected probands from families with autosomal dominant parkinsonism was subsequently assessed; 7 (2.8%) were found to carry a heterozygous LRRK2 6055G→A transition (G2019S). These seven patients originate from the United States, Norway, Ireland, and Poland. In samples of patients with idiopathic Parkinson disease (PD) from the same populations, further screening identified six more patients with LRRK2 G2019S; no mutations were found in matched control individuals. Subsequently, 42 family members of the 13 probands were examined; 22 have an LRRK2 G2019S substitution, 7 with a diagnosis of PD. Of note, all patients share an ancestral haplotype indicative of a common founder, and, within families, LRRK2 G2019S segregates with disease (multipoint LOD score 2.41). Penetrance is age dependent, increasing from 17% at age 50 years to 85% at age 70 years. In summary, our study demonstrates that LRRK2 G2019S accounts for parkinsonism in several families within Europe and North America. Our work highlights the fact that a proportion of clinically typical, late-onset PD cases have a genetic basis.
535 citations
TL;DR: In this article, the effects of nitriding on the micro-hardness and the corrosion resistance of titanium and titanium alloys are analyzed in relation to the potential for applying these alloys to different industries.
Abstract: Over the last 40 years, the commercial production of titanium and its alloys has increased steadily. Whilst these materials have some very attractive properties, enabling applications in many industries, they are seldom used in mechanical engineering applications because of their poor tribological properties. This paper starts with an introduction to the titanium material and a review of the different types of surface treatment. The processes of nitriding, oxidation and carburizing are among the most popular thermochemical treatments aiming at improving the surface properties of Ti-alloys. Different kinds of nitriding are investigated like plasma nitriding, ion nitriding, and laser and gas nitriding. The kinetics of nitriding and the conditions for the formation of nitrided layers are studied. The influence of the main processing parameters such as temperature, time on the microstructure and the formation of new phases during the processes of nitriding is discussed. Also based on investigations presented in the literature, the effects of nitriding on the microhardness and the corrosion resistance of titanium and titanium alloys are analyzed. The improved mechanical properties, which arise from these thermochemical treatments, are discussed in relation to the potential for applying these alloys to different industries.
494 citations
TL;DR: The weight of evidence currently favours oxidative stress and aberrant apoptosis as the major candidates for DNA damage in the male germ line and positive results have been reported for antioxidant therapy both in vivo and in vitro.
Abstract: DNA damage in the male germ line has been associated with poor semen quality, low fertilization rates, impaired preimplantation development, increased abortion and an elevated incidence of disease in the offspring, including childhood cancer. The causes of this DNA damage are still uncertain but the major candidates are oxidative stress and aberrant apoptosis. The weight of evidence currently favours the former and, in keeping with this conclusion, positive results have been reported for antioxidant therapy both in vivo and in vitro. Resolving the causes of DNA damage in the male germ line will be essential if we are to prevent the generation of genetically damaged human embryos, particularly in the context of assisted conception therapy.
481 citations
TL;DR: High hydrostatic pressure has the potential to produce high quality foods that are microbiologically safe and with an extended shelf-life, and a knowledge of how these factors interact is necessary in order to select the optimum processing conditions for foods.
Abstract: High hydrostatic pressure has the potential to produce high quality foods that are microbiologically safe and with an extended shelf-life. Micro-organisms vary in their response to high pressure. Bacterial spores are the most resistant group and they cannot be significantly inactivated by pressure alone. Combination treatments using high pressure and heat have been proposed as a method of producing shelf-stable low acid foods. Viruses are less resistant than bacterial spores and their infectivity can be abolished without destroying their ability to elicit antibodies, leading to the possibility of vaccine production. Yeasts, moulds and vegetative bacteria vary in their response to pressure, depending on factors such as species, strain, processing temperature and substrate, and these are reviewed in the paper. A knowledge of how these factors interact is necessary in order to select the optimum processing conditions for foods. A number of pressure-treated foods are already commercially available and these are discussed in the paper.
TL;DR: In this article, the authors investigated the use of noble metal-based catalysts for the steam reforming of a few model compounds and that of an actual bio-oil and found that the Pt/ceria-zirconia sample showed essentially constant activity, while extensive carbonaceous deposits were observed on the quartz reactor walls.
Abstract: The production of hydrogen by steam reforming of bio-oils obtained from the fast pyrolysis of biomass requires the development of efficient catalysts able to cope with the complex chemical nature of the reactant. The present work focuses on the use of noble metal-based catalysts for the steam reforming of a few model compounds and that of an actual bio-oil. The steam reforming of the model compounds was investigated in the temperature range 650–950 °C over Pt, Pd and Rh supported on alumina and a ceria–zirconia sample. The model compounds used were acetic acid, phenol, acetone and ethanol. The nature of the support appeared to play a significant role in the activity of these catalysts. The use of ceria–zirconia, a redox mixed oxide, lead to higher H 2 yields as compared to the case of the alumina-supported catalysts. The supported Rh and Pt catalysts were the most active for the steam reforming of these compounds, while Pd-based catalysts poorly performed. The activity of the promising Pt and Rh catalysts was also investigated for the steam reforming of a bio-oil obtained from beech wood fast pyrolysis. Temperatures close to, or higher than, 800 °C were required to achieve significant conversions to CO x and H 2 (e.g., H 2 yields around 70%). The ceria–zirconia materials showed a higher activity than the corresponding alumina samples. A Pt/ceria–zirconia sample used for over 9 h showed essentially constant activity, while extensive carbonaceous deposits were observed on the quartz reactor walls from early time on stream. In the present case, no benefit was observed by adding a small amount of O 2 to the steam/bio-oil feed (auto-thermal reforming, ATR), probably partly due to the already high concentration of oxygen in the bio-oil composition.
TL;DR: Evidence of increased Akt activation, and hyperphosphorylation of critical Akt substrates in AD brain, which link to AD pathogenesis is provided, suggesting that treatments aiming to activate the pathway in AD need to be considered carefully.
Abstract: Studies suggest that activation of phosphoinositide 3-kinase-Akt may protect against neuronal cell death in Alzheimer's disease (AD). Here, however, we provide evidence of increased Akt activation, and hyperphosphorylation of critical Akt substrates in AD brain, which link to AD pathogenesis, suggesting that treatments aiming to activate the pathway in AD need to be considered carefully. A different distribution of Akt and phospho-Akt was detected in AD temporal cortex neurons compared with control neurons, with increased levels of active phosphorylated-Akt in particulate fractions, and significant decreases in Akt levels in AD cytosolic fractions, causing increased activation of Akt (phosphorylated-Akt/total Akt ratio) in AD. In concordance, significant increases in the levels of phosphorylation of total Akt substrates, including: GSK3βSer9, tauSer214, mTORSer2448, and decreased levels of the Akt target, p27kip1, were found in AD temporal cortex compared with controls. A significant loss and altered distribution of the major negative regulator of Akt, PTEN (phosphatase and tensin homologue deleted on chromosome 10), was also detected in AD neurons. Loss of phosphorylated-Akt and PTEN-containing neurons were found in hippocampal CA1 at end stages of AD. Taken together, these results support a potential role for aberrant control of Akt and PTEN signalling in AD.
TL;DR: Rhodococcus appear to have adopted a strategy of hyper-recombination associated with a large genome that contributes to their catabolic diversity by acting as 'mass storage' for a large number of catabolic genes.
National Institutes of Health1, Eötvös Loránd University2, Slovak Academy of Sciences3, Pusan National University4, Pontifical Catholic University of Chile5, University of Tartu6, Complutense University of Madrid7, Keele University8, Sapienza University of Rome9, University of Iowa10, University of Malta11, Cayetano Heredia University12, University of Melbourne13, University of Paris14, University of Ouagadougou15, University of Coimbra16, University of the Philippines Diliman17, University of Illinois at Urbana–Champaign18, University of Otago19, Victoria University of Wellington20, Al Akhawayn University21, Koç University22, Lund University23, The Catholic University of America24, Academy of Sciences of the Czech Republic25, University of Copenhagen26, University of Iceland27, American University of Beirut28, University of Belgrade29, University of Buenos Aires30, Susquehanna University31, National University of Malaysia32, San Francisco State University33, Queen's University Belfast34, International University, Cambodia35, University of Botswana36, Iwate Prefectural University37, Makerere University38, University of Virginia39, University of Ibadan40, University of British Columbia41, University of Puerto Rico, Río Piedras42, Andhra University43, University of Lausanne44, University of Ljubljana45, Queensland University of Technology46, Bunkyo Gakuin University47, Ramapo College48, Jagiellonian University49, University of Sussex50, University of Winnipeg51, Peking University52, Hong Kong University of Science and Technology53
TL;DR: Perceptions of national character appear to be unfounded stereotypes that may serve the function of maintaining a national identity.
Abstract: Most people hold beliefs about personality characteristics typical of members of their own and others' cultures. These perceptions of national character may be generalizations from personal experience, stereotypes with a "kernel of truth," or inaccurate stereotypes. We obtained national character ratings of 3989 people from 49 cultures and compared them with the average personality scores of culture members assessed by observer ratings and self-reports. National character ratings were reliable but did not converge with assessed traits. Perceptions of national character thus appear to be unfounded stereotypes that may serve the function of maintaining a national identity.
TL;DR: The majority of children and adults with CLP do not appear to experience major psychosocial problems, although some specific problems may arise, and a few differences between cleft types have been found.
Abstract: This systematic review examined the published scientific research on the psychosocial impact of cleft lip and palate (CLP) among children and adults. The primary objective of the review was to determine whether having CLP places an individual at greater risk of psychosocial problems. Studies that examined the psychosocial functioning of children and adults with repaired non-syndromal CLP were suitable for inclusion. The following sources were searched: Medline (January 1966-December 2003), CINAHL (January 1982-December 2003), Web of Science (January 1981-December 2003), PsycINFO (January 1887-December 2003), the reference section of relevant articles, and hand searches of relevant journals. There were 652 abstracts initially identified through database and other searches. On closer examination of these, only 117 appeared to meet the inclusion criteria. The full text of these papers was examined, with only 64 articles finally identified as suitable for inclusion in the review. Thirty of the 64 studies included a control group. The studies were longitudinal, cross-sectional, or retrospective in nature.Overall, the majority of children and adults with CLP do not appear to experience major psychosocial problems, although some specific problems may arise. For example, difficulties have been reported in relation to behavioural problems, satisfaction with facial appearance, depression, and anxiety. A few differences between cleft types have been found in relation to self-concept, satisfaction with facial appearance, depression, attachment, learning problems, and interpersonal relationships. With a few exceptions, the age of the individual with CLP does not appear to influence the occurrence or severity of psychosocial problems. However, the studies lack the uniformity and consistency required to adequately summarize the psychosocial problems resulting from CLP.
TL;DR: In this article, a range of interpolation methods were applied to map monthly precipitation in Great Britain from sparse point data using a variety of data sources, such as moving window regression (MWR), inverse distance weighting (IDW), ordinary kriging (OK), simple Kriging with a locally varying mean (SKlm), and krigging with an external drift (KED).
TL;DR: In this article, the authors review the development of the field of entrepreneurship as a context for the emergence of learning as an area of scholarly attention, summarize a number of key themes emerging from the organizational learning literature, and outline the article selection process and summarize the key elements of each of the included articles.
Abstract: The context for the research presented in this article arises from increasing interest, by academics and practitioners, in the importance of learning and knowledge in the knowledge-based economy. In particular, we consider the scope for applying concepts of learning within the field of entrepreneurship. While it has gained currency within the field of management, the application of these concepts to entrepreneurship has been limited. In this Introduction to the Special Issue, we review the development of the field of entrepreneurship as a context for the emergence of learning as an area of scholarly attention, summarize a number of key themes emerging from the organizational learning literature, and outline the article selection process and summarize the key elements of each of the included articles. The article concludes with some reflections on future research at the interface between learning and the entrepreneurial context.
TL;DR: Analysis of trends in squamous cell carcinoma of the cervix uteri in 13 European countries to evaluate effectiveness of screening against a background of changing risk found period- and cohort-specific declines in cervical SCC.
Abstract: Despite there being sufficient evidence for the effectiveness of screening by cytology in preventing cancer of the cervix uteri, screening policies vary widely among European countries, and incidence is increasing in younger women. This study analyzes trends in squamous cell carcinoma (SCC) of the cervix uteri in 13 European countries to evaluate effectiveness of screening against a background of changing risk. Age-period-cohort models were fitted and period and cohort effects were estimated; these were considered as primarily indicative of screening interventions and changing etiology, respectively. A unique set of estimates was derived by fixing age slopes to one of several plausible age curves under the assumption that the relation between age and cervical cancer incidence is biologically determined. There were period-specific declines in cervical SCC in several countries, with the largest decreases seen in northern Europe. A pattern emerged across Europe of escalating risk in successive generations born after 1930. In the western European countries, a decrease followed by a stabilization of risk by cohort was accompanied by period-specific declines. In southern Europe, stable period, but increasing cohort trends, were observed. Substantial changes have occurred in cervical SCC incidence in Europe and well-organized screening programs have been highly effective in reducing the incidence of cervical SCC. Screening and changing sexual mores largely explain the changing period- and cohort-specific patterns, respectively. The increasing risk in recent cohorts is of obvious concern particularly in countries where no screening programs are in place. Further investigation of the effectiveness of opportunistic screening is warranted as is the observation of differing risk patterns in young cohorts in countries with relatively similar societal structures.
TL;DR: The HOM‐C clustered prototype homeobox genes of Drosophila, and their counterparts, the HOX genes in humans, are highly conserved at the genomic level and their role in other neoplasms is currently being studied.
Abstract: The HOM-C clustered prototype homeobox genes of Drosophila, and their counterparts, the HOX genes in humans, are highly conserved at the genomic level. These master regulators of development continue to be expressed throughout adulthood in various tissues and organs. The physiological and patho-physiological functions of this network of genes are being avidly pursued within the scientific community, but defined roles for them remain elusive. The order of expression of HOX genes within a cluster is co-ordinated during development, so that the 3' genes are expressed more anteriorly and earlier than the 5' genes. Mutations in HOXA13 and HOXD13 are associated with disorders of limb formation such as hand-foot-genital syndrome (HFGS), synpolydactyly (SPD), and brachydactyly. Haematopoietic progenitors express HOX genes in a pattern characteristic of the lineage and stage of differentiation of the cells. In leukaemia, dysregulated HOX gene expression can occur due to chromosomal translocations involving upstream regulators such as the MLL gene, or the fusion of a HOX gene to another gene such as the nucleoporin, NUP98. Recent investigations of HOX gene expression in leukaemia are providing important insights into disease classification and prediction of clinical outcome. Whereas the oncogenic potential of certain HOX genes in leukaemia has already been defined, their role in other neoplasms is currently being studied. Progress has been hampered by the experimental approach used in many studies in which the expression of small subsets of HOX genes was analysed, and complicated by the functional redundancy implicit in the HOX gene system. Attempts to elucidate the function of HOX genes in malignant transformation will be enhanced by a better understanding of their upstream regulators and downstream target genes.
TL;DR: The pseudo-second-order model was the best choice among all the kinetic models to describe the adsorption behaviour of RB onto MOMD, suggesting that the advertisersorption mechanism might be a chemisorption process.
TL;DR: Since only the red cell lineage is involved, the term erythrocytosis has more validity and will be used throughout this article, and polycythaemia will be retained in relation to the clonal disorder, polycytaemia vera (PV), in which three cell lineages are involved.
Abstract: Traditionally, polycythaemia has been used to identify a group of varied disorders with an increase in circulating red cells that are typified by a persistently raised haematocrit (Hct). Since only the red cell lineage is involved, the term erythrocytosis has more validity and will be used throughout this article. Polycythaemia will be retained in relation to the clonal disorder, polycythaemia vera (PV), in which three cell lineages are involved.
TL;DR: Adsorption on the external surface by n-pi interaction between the pi system of the RB and the electron lone pairs of the oxygen atoms of siloxane group and columbic attraction between the dye and the surface of calcined diatomite was proposed as a possible adsorption mechanism.
TL;DR: Findings confirm the importance of two genetic factors associated with long-term antipsychotic-induced weight increases in schizophrenia, and implicate a role for leptin in the 5-HT receptor-mediated weight regulation.
Abstract: ObjectivesWeight gain, leading to further morbidity and poor treatment adherence, is a common consequence of treatment with antipsychotic drugs. Two recent studies in the same cohort of Chinese Han subjects have shown that polymorphisms of the promoter regions of both the serotonin 5-hydroxytryptami
TL;DR: The effect of postnatal corticosteroids on the combined outcome of death or CP varies with the level of risk for CLD, whereas with risks for ClD exceeding 65%, it reduced this chance.
Abstract: Objective In preterm infants, chronic lung disease (CLD) is associated with an increased risk for cerebral palsy (CP). However, systemic postnatal corticosteroid therapy to prevent or treat CLD, although effective in improving lung function, may cause CP. The objective of this study was to determine the effect of systemic postnatal corticosteroid treatment on death and CP and to assess any modification of effect arising from risk for CLD. Methods Randomized, controlled trials of postnatal corticosteroid therapy for prevention or treatment of CLD in preterm infants that reported rates of both mortality and CP were reviewed and their data were synthesized. Twenty studies with data on 1721 randomized infants met eligibility criteria. The relationship between the corticosteroid effect on the combined outcome, death or CP, and the risk for CLD in control groups was analyzed by weighted meta-regression. Results Among all infants who were randomized, a significantly higher rate of CP after corticosteroid treatment (typical risk difference [RD]: 0.05; 95% confidence interval [CI]: 0.02, 0.08) was partly offset by a nonsignificant reduction in mortality (typical RD: -0.02; 95% CI: -0.06 to 0.02). Consequently, there was no significant effect of corticosteroid treatment on the combined rate of mortality or CP (typical RD: 0.03; 95% CI: -0.01 to 0.08). However, on meta-regression, there was a significant negative relationship between the treatment effect on death or CP and the risk for CLD in control groups. With risks for CLD below 35%, corticosteroid treatment significantly increased the chance of death or CP, whereas with risks for CLD exceeding 65%, it reduced this chance. Conclusions The effect of postnatal corticosteroids on the combined outcome of death or CP varies with the level of risk for CLD.
TL;DR: Fibrinogen, D-dimer, PAI-1 activity, and factor VIIc each has potential to increase the prediction of coronary disease/ischemic stroke in middle-aged men, in addition to conventional risk factors.
Abstract: Background— Few studies have examined whether hemostatic markers contribute to risk of coronary disease and ischemic stroke independently of conventional risk factors. This study examines 11 hemostatic markers that reflect different aspects of the coagulation process to determine which have prognostic value after accounting for conventional risk factors. Methods and Results— A total of 2398 men aged 49 to 65 years were examined in 1984 to 1988, and the majority gave a fasting blood sample for assay of lipids and hemostatic markers. Men were followed up for a median of 13 years, and cardiovascular disease (CVD) events were recorded. There were 486 CVD events in total, 353 with prospective coronary disease and 133 with prospective ischemic stroke. On univariable analysis, fibrinogen, low activated protein C ratio, D-dimer, tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) were associated significantly with risk of CVD. On multivariable analyses with conventional risk factors ...
TL;DR: The Flory theory of mixtures provides a useful, semiquantitative correlation between the excess volumes and excess enthalpies in these systems, allowing for comparison with analogous results obtained within the linear primary alcohols.
Abstract: Excess molar volumes of six binary mixtures composed of two ionic liquids of the 1-methyl-3-alkyl-imidazolium bis(trifluoromethylsulfonyl)amide family([Cmmim] + [Cnmim])[NTf2] with n and m ranging from 2 to 10were measured for several compositions at 298 and 333 K. Similarly, three other binary systems containing [C4mim]+ (1-methyl-3-butylimidazolium) as a common cation have been studied: [C4mim]([NTf2] + [PF6]), [C4mim]([NTf2] + [BF4]) and [C4mim]([BF4] + [PF6]). Thus, the mixing process of two distinct ions of equal sign embedded in a constant field network of a given counterion was analyzed. All systems exhibit small, positive VE values of the order of a few tenths of cm3 mol-1, which are essentially temperature and pressure independent. The results show additive trends, for instance, the VE values become larger as the difference between the alkyl chain lengths of the two cations increases. The Flory theory of mixtures provides a useful, semiquantitative correlation between the excess volumes and exce...
TL;DR: A review of low-energy positron interactions with atoms and molecules is given in this article, including elastic scattering, electronic and vibrational excitation, ionization, positronium formation and annihilation.
Abstract: This paper is a review of low-energy positron interactions with atoms and molecules. Processes of interest include elastic scattering, electronic and vibrational excitation, ionization, positronium formation and annihilation. An overview is presented of the currently available theoretical and experimental techniques to study these phenomena, including the use of trap-based positron beam sources to study collision processes with improved energy resolution. State-resolved measurements of electronic and vibrational excitation cross sections and measurement of annihilation rates in atoms and molecules as a function of incident positron energy are discussed. Where data are available, comparisons are made with analogous electron scattering cross sections. Resonance phenomena, common in electron scattering, appear to be less common in positron scattering. Possible exceptions include the sharp onsets of positron-impact electronic and vibrational excitation of selected molecules. Recent energy-resolved studies of positron annihilation in hydrocarbons containing more than a few carbon atoms provide direct evidence that vibrational Feshbach resonances underpin the anomalously large annihilation rates observed for many polyatomic species. We discuss open questions regarding this process in larger molecules, as well as positron annihilation in smaller molecules where the theoretical picture is less clear.
TL;DR: In this paper, the acceleration of multi-MeV protons from the rear surface of thin solid foils irradiated by an intense ($\ensuremath{\sim}{10}^{18}\text{ }\text{ W}/{\mathrm{cm}}^{2}$) and short (1.5
Abstract: The acceleration of multi-MeV protons from the rear surface of thin solid foils irradiated by an intense ($\ensuremath{\sim}{10}^{18}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) and short ($\ensuremath{\sim}1.5\text{ }\text{ }\mathrm{ps}$) laser pulse has been investigated using transverse proton probing. The structure of the electric field driving the expansion of the proton beam has been resolved with high spatial and temporal resolution. The main features of the experimental observations, namely, an initial intense sheath field and a late time field peaking at the beam front, are consistent with the results from particle-in-cell and fluid simulations of thin plasma expansion into a vacuum.