The thermal decomposition behavior of hard coal fly ash (HCA2), obtained from the combustion of an Australian hard coal in
thermoelectric power plants, in different atmospheres (air, N2 and N2-H2 mixture), was studied using thermogravimetry (TG), infrared-evolved gas analysis (IR-EGA), differential scanning calorimetry
(DSC) and thermodilatometry (DIL) techniques. It was found that changing of the applied atmosphere affects the carbon content
of the ash which results in different thermal decomposition behaviors. In air, the carbon content was oxidized to carbon dioxide
before the decomposition of carbonate. In N2 or in N2-H2 atmospheres, the carbon content acts as a spacer causing a fewer points of contact between calcium carbonate particles, thus
increasing the interface area which results in a decrease of the carbonate decomposition temperature. Following the carbonate
decomposition, the iron oxide content of the ash undergoes a reductive decomposition reaction with the unburned carbon. This
oxidation-reduction reaction was found to be fast and go to completion in presence of the N2-H2 mixture than in the pure nitrogen atmosphere due to the reducing effect of the hydrogen.
The kinetics of the carbonate decomposition step, in air and N2-H2 mixture was performed under non-isothermal conditions using different integral methods of analysis. The dynamic TG curves
obeyed the Avrami-Erofeev equation (A2) in air, and phase boundary controlled reaction equation (R2) in N2-H2 mixture. The change in the reaction mechanism and the difference in the calculated values of activation parameters with the
change of the atmosphere were discussed in view of effect of the atmosphere on the carbon content of the ash.
Authors:Shane W. Kraus, Mateusz Gola, Joshua B. Grubbs, Ewelina Kowalewska, Rani A. Hoff, Michał Lew-Starowicz, Steve Martino, Steven D. Shirk, and Marc N. Potenza
Background and Aims
To address current gaps around screening for problematic pornography use (PPU), we initially developed and tested a six-item Brief Pornography Screen (BPS) that asked about PPU in the past six months.
Methods and Participants
We recruited five independent samples from the U.S. and Poland to evaluate the psychometric properties of the BPS. In Study 1, we evaluated the factor structure, reliability, and elements of validity using a sample of 224 U.S. veterans. One item from the BPS was dropped in Study 1 due to low item endorsement. In Studies 2 and 3, we further investigated the five-item the factor structure of the BPS and evaluated its reliability and validity in two national U.S. representative samples (N = 1,466, N = 1,063, respectively). In Study 4, we confirmed the factor structure and evaluated its validity and reliability using a sample of 703 Polish adults. In Study 5, we calculated the suggested cut-off score for the screen using a sample of 105 male patients seeking treatment for compulsive sexual behavior disorder (CSBD).
Findings from a principal components analysis and confirmatory factor analysis supported a one-factor solution which yielded high internal consistency (α = 0.89–0.90), and analyses further supported elements of construct, convergent, criterion, and discriminant validity of the newly developed screen. Results from a Receiver Operating Characteristic (ROC) curve suggested a cut-off score of four or higher for detecting possible PPU.
The BPS appears to be psychometrically sound, short, and easy to use in various settings with high potential for use in populations across international jurisdictions.