Enhanced viscosity reduction in heavy oils by subcritical water

We determine the chemical changes associated with viscosity reduction when heavy oil is cracked in subcritical water. The viscosity reduction has a temperature threshold for onset of 290 °C—this suggests an enhanced acid cracking regime associated with the maximisation of water dissociation at these conditions aided by the already increased solubility. The mean molecular weight is reduced by nearly 50%. Oxygen and sulphur are reduced by about half of this—either by expelled gas effluent (H 2S) or by conversion into mono-aromatic base sulphur-containing structures. The amount of lower branched paraffins is increased.</p

Enhanced viscosity reduction in heavy oils by subcritical water

We determine the chemical changes associated with viscosity reduction when heavy oil is cracked in subcritical water. The viscosity reduction has a temperature threshold for onset of 290 °C—this suggests an enhanced acid cracking regime associated with the maximisation of water dissociation at these conditions aided by the already increased solubility. The mean molecular weight is reduced by nearly 50%. Oxygen and sulphur are reduced by about half of this—either by expelled gas effluent (H 2S) or by conversion into mono-aromatic base sulphur-containing structures. The amount of lower branched paraffins is increased.</p

Collateral and Debt Maturity Choice. A Signaling Model

This paper derives optimal loan policies under asymmetric information where banks offer loan contracts of long and short duration, backed or unbacked with collateral. The main novelty of the paper is that it analyzes a setting in which high quality firms use collateral as a complementary device along with debt maturity to signal their superiority. The least-cost signaling equilibrium depends on the relative costs of the signaling devices, the difference in firm quality and the proportion of good firms in the market. Model simulations suggest a non-monotonic relationship between firm quality and debt maturity, in which high quality firms have both long-term secured debt and short-term secured or non-secured debt.

Improving rubber concrete strength and toughness by plasma-induced end-of-life tire rubber surface modification

This study evaluates the effectiveness of using different plasma treatments to favor the compatibility between rubber and a cement matrix in composites, thus leading to a different surface reactivity of the rubber component. Plasmatreated rubbers were introduced into two d ifferent types of concr ete. Mechanical tests highlighted that Portland concrete composites filled with N2/H2 plasmatreated rubber had increased flexural strength, toughness, and compression strength compared to composites containing untreated rubber. A scaling law is also proposed to qualitatively discriminate between related effects due to topological/roughness or intrinsic/chemical adhesion modifications. Plasma treatment can improve both intrinsic adhesion and roughness of the rubber–cement interface and thus the overall concrete strength and toughness

Improving mental health of student and novice nurses to prevent dropout:A systematic review

Aims: To provide: (a) an overview of interventions aimed at improving mental health of student or novice nurses; and (b) an evaluation of their effectiveness on dropout-related outcomes. Design: Systematic review. Data sources: Research papers published between January 1971–February 2019 were identified from the following databases: Embase, Medline, PsycInfo, CINAHL, ERIC, the Cochrane Library, Web of Science, and Google Scholar. Review methods: We followed the procedures recommended by the Editorial Board of the Cochrane Collaboration Back Review Group. We included peer-reviewed articles with a quantitative research design, examining interventions aimed at improving mental health of student and novice nurses and their effect on dropout-related outcomes. The large variation in studies prohibited statistical pooling and a synthesis without meta-analysis of studies was performed. Results: We identified 21 studies with three areas of focus: managing stress or stressors (N = 4); facilitating the transition to nursing practice (N = 14); and a combined approach (N = 3). Five studies showed a statistically significant effect on dropout-related outcomes. The overall risk of bias was high. Conclusion: A wide range of interventions are available, but the evidence for their effectiveness is limited. There is a need for high-quality studies in this field, preferably with a randomized controlled design

Optimal Supernova Search Strategies

Recent use of Type Ia supernovae to measure acceleration of the universe has motivated questions regarding their optimal use to constrain cosmological parameters Omega_M, Omega_{\Lambda} and w_Q. In this work we address the question: what is the optimal distribution of supernovae in redshift in order to best constrain the cosmological parameters? The solution to this problem is not only of theoretical interest, but can be useful in planning supernova searches. Using the Fisher matrix formalism we show that the error ellipsoid corresponding to N parameters (for N=1, 2, 3) has the smallest volume if the supernovae are located at N discrete redshifts, with equal number of supernovae at each redshift and with one redshift always being the maximum one probed. Including marginalization over the ``nuisance parameter'' M changes this result only trivially.Comment: 12 pages, 6 eps figures. To appear in Proceedings of "Sources and Detection of Dark Matter/Energy in the Universe", Marina Del Rey, Feb. 200

Relativistic ponderomotive force, uphill acceleration, and transition to chaos

Starting from a covariant cycle-averaged Lagrangian the relativistic oscillation center equation of motion of a point charge is deduced and analytical formulae for the ponderomotive force in a travelling wave of arbitrary strength are presented. It is further shown that the ponderomotive forces for transverse and longitudinal waves are different; in the latter, uphill acceleration can occur. In a standing wave there exists a threshold intensity above which, owing to transition to chaos, the secular motion can no longer be described by a regular ponderomotive force. PACS number(s): 52.20.Dq,05.45.+b,52.35.Mw,52.60.+hComment: 8 pages, RevTeX, 3 figures in PostScript, see also http://www.physik.th-darmstadt.de/tqe

Catalytic Depolymerization of Lignin and Woody Biomass in Supercritical Ethanol:Influence of Reaction Temperature and Feedstock

The one-step ethanolysis approach to upgrade lignin to monomeric aromatics using a CuMgAl mixed oxide catalyst is studied in detail. The influence of reaction temperature (200-420 °C) on the product distribution is investigated. At low temperature (200-250 °C), recondensation is dominant, while char-forming reactions become significant at high reaction temperature (&gt;380 °C). At preferred intermediate temperatures (300-340 °C), char-forming reactions are effectively suppressed by alkylation and Guerbet and esterification reactions. This shifts the reaction toward depolymerization, explaining high monomeric aromatics yield. Carbon-14 dating analysis of the lignin residue revealed that a substantial amount of the carbon in the lignin residue originates from reactions of lignin with ethanol. Recycling tests show that the activity of the regenerated catalyst was strongly decreased due to a loss of basic sites due to hydrolysis of the MgO function and a loss of surface area due to spinel oxide formation of the Cu and Al components. The utility of this one-step approach for upgrading woody biomass was also demonstrated. An important observation is that conversion of the native lignin contained in the lignocellulosic matrix is much easier than the conversion of technical lignin.</p

Automatic mental processes, automatic actions and behaviours in game transfer phenomena: an empirical self-report study using online forum data

Previous studies have demonstrated that the playing of videogames can have both intended and unintended effects. The purpose of this study was to investigate the influence of videogames on players’ mental processes and behaviours in day-to-day settings. A total of 1,023 self-reports from 762 gamers collected from online videogame forums were classified, quantified, described and explained. The data include automatic thoughts, sensations and impulses, automatic mental replays of the game in real life, and voluntary/involuntary behaviours with videogame content. Many gamers reported that they had responded – at least sometimes – to real life stimuli as if they were still playing videogames. This included overreactions, avoidances, and involuntary movements of limbs. These experiences lasted relatively short periods of time but in a minority of players were recurrent. The gamers' experiences appeared to be enhanced by virtual embodiment, repetitive manipulation of game controls, and their gaming habits. However, similar phenomena may also occur when doing other non-gaming activities. The implications of these game transfer experiences are discussed

Investigation of the combustion and emissions of lignin‐derived aromatic oxygenates in a marine diesel engine

As a hard-to-decarbonize sector, the shipping industry is experiencing demands to accelerate the transition from fossil fuels to alternative low-carbon fuels, to significantly reduce the negative impacts on the environment. Biofuels are regarded as one of the solutions for decarbonization in the marine sector. This paper introduces a lignin-derived drop-in biofuel, 2-methoxy-4-propylphenol (2M4PP), from non-edible feedstocks and investigates engine performance using its 10% (by volume) blend with standard diesel fuel (DF) at variable engine speeds and loads. Results show insignificant difference between the in-cylinder pressures of the proposed blend and DF. The diesel-2M4PP blend emits less carbon monoxide (CO) and nitric oxide (NOx) than DF at all speeds by up to 39.6% and 10.7% respectively, although its brake-specific fuel consumption (BSFC) is higher. A Ricardo wave model, which is validated with engine experimental data at 2400 rpm speed and full load, is investigated by adjusting injection pressure, injection timing, injection duration and nozzle diameter. The optimal parameters, i.e., 214 bar injection pressure, 6° injection timing, 41.4° injection duration, and 0.37 mm injector orifice, lead to the best engine performance with improved brake power, reduced NOx emissions, and limited influence on BSFC and hydrocarbon emissions compared to DF