Transformation pathways of 2,2-dimethyloxirane on aluminosilicates: the effects of catalyst structure and reaction conditions

The ring transformation reactions of 2,2-dimethyloxirane were studied over various aluminosilicates (HZSM-5, CuZSM-5, HY, AIMCM-41 or NaNa-loaded A1MCM-41) in a pulse reactor at 423 K. The main reactions identified were isomerisation and cyclic dimerisation. The product formation selectivities could be tuned by varying the pore size of the molecular sieves and/or altering the reaction parameters. Large pore size and mild conditions favoured isomerisation, while an optimally constrained environment and overloading the catalyst with the epoxide (increased pulse size) was advantageous for cyclic dimerisation

The Feminist Hollywood

Writings and art examining feature films thought to represent feminist values, the evolution of female Disney characters, and female musicians who challenge the patriarchal music industry.https://digitalcommons.chapman.edu/feminist_zines/1020/thumbnail.jp

The Dynamical Functional Particle Method for Multi-Term Linear Matrix Equations

Recent years have seen a renewal of interest in multi-term linear matrix equations, as these have come to play a role in a number of important applications. Here, we consider the solution of such equations by means of the dynamical functional particle method, an iterative technique that relies on the numerical integration of a damped second order dynamical system. We develop a new algorithm for the solution of a large class of these equations, a class that includes, among others, all linear matrix equations with Hermitian positive definite or negative definite coefficients. In numerical experiments, our MATLAB implementation outperforms existing methods for the solution of multi-term Sylvester equations. For the Sylvester equation AX + XB = C, in particular, it can be faster and more accurate than the built-in implementation of the Bartels–Stewart algorithm, when A and B are well conditioned and have very different size

Harga Pokok Produksi dalam Kaitannya dengan Penentuan Harga Jual untuk Pencapaian Target Laba Analisis (Studi Kasus pada PT. Indra Brothers di Bandar Lampung)

The purpose of this study was to determine the cost of production calculation is applied to the PT. Brother's senses and its effect on the determination of the selling price of the company, and the study is expected to be useful as a conceptual contribution to the company in conducting its business activities and for determining policies for the betterment of the company, particularly regarding the determination and the determination of cost of production in relation to the determination of the selling price.Based on the above problems posed hypothesis, namely: "Calculation of Cost of Production is carried out by PT. Indra Brother's has not been implemented properly as the basis for determining the selling price. "In analyzing the problems used tool for qualitative and quantitative analysis. In the approach used to analyze the qualitative theory related to the cost of production and the theory used to analyze quantitative calculation of the cost of production and selling price. Based on the analysis it can be concluded that during the PT. Brother's senses in relation to determining the selling price has not appropriately allocate production costs which companies should take into account the elements of the ending inventory of raw material costs in the calculation of the cost of production. Miscalculation of the cost of production of the company could result in the selling price of the products is higher than the selling price of similar companies. Thus, it can be concluded that the calculation of cost of production and selling price of the products produced by the company is not yet right

A Backward/Forward Recovery Approach for the Preconditioned Conjugate Gradient Algorithm

Several recent papers have introduced a periodic verification mechanism to detect silent errors in iterative solvers. Chen [PPoPP'13, pp. 167--176] has shown how to combine such a verification mechanism (a stability test checking the orthogonality of two vectors and recomputing the residual) with checkpointing: the idea is to verify every $d$ iterations, and to checkpoint every $c \times d$ iterations. When a silent error is detected by the verification mechanism, one can rollback to and re-execute from the last checkpoint. In this paper, we also propose to combine checkpointing and verification, but we use algorithm-based fault tolerance (ABFT) rather than stability tests. ABFT can be used for error detection, but also for error detection and correction, allowing a forward recovery (and no rollback nor re-execution) when a single error is detected. We introduce an abstract performance model to compute the performance of all schemes, and we instantiate it using the preconditioned conjugate gradient algorithm. Finally, we validate our new approach through a set of simulations

Assessment of the Tyhume river health status using macroinvertebrates as indicators

Ten sampling sites were selected along the Tyhume River corresponding to the upper, mid and lower reaches of the River. In total 48 families were collected during the study. The study observed different types of macroinvertebrate taxa; very low tolerant to pollution (e.g Heptageniidae; Notonemouridae; Perlidae), moderately pollution-tolerant (e.g. Caenidae; Chlorolestidae; Tricorythidae) and very tolerant of polluted conditions (e.g. Chironomidae; Muscidae; Oligochaetae). Both univariate and multivariate analyses were done using PRIMER V6. Above Confluence (ABCON, Site 10) had the highest number (37) of species while Mtloko (MTLOK, Site 2) had the lowest number (24) (Chi-square = 0.87; p 0.05) across sites. No significant difference was observed in the ASPT scores across the 10 sites (F = 0.75; df = 9.60; P > 0.05). Site 4 had the highest mean ASPT Scores with mean of 7.6), whereas the lowest. Three biotopes types, namely: stone, vegetation, gravel-sand-mud, stone and vegetation being the dominant biotopes at the 10 sites. The cluster analyses showed that macroinvertebrates were dependent on biotope preference while stone biotope showing greater macroinvertebrate densities. Euclidean distance of site classification with respect to physico-chemical parameters showed very low stress value (0.01) implying that physico-chemical parameters influenced species distribution within each sampling site. The results also showed that good health conditions existed at the most upstream sites than the lower reaches of the river, thus, indicating impacts of pollution within the river

Attitudes of Saudi Arabian Students Toward the Use of Digital Libraries in Higher Education

Universities worldwide are transitioning to integrate technology to enhance and augment using E-learning. This study investigated attitudes of Saudi Arabian students toward the use of digital libraries in higher education at Taibah University in Madina. Data were collected to explore the relationship between Saudi students’ computer literacy skills, as well as their demographic background, and 1) their use of digital libraries, 2) their attitudes toward digital libraries, and 3) their perceived usability of digital libraries. Descriptive statistics, independent-samples , simple and multiple linear regression analyses were conducted to address the research questions. Participants were 240 undergraduate students enrolled at Taibah University. Most of them were senior (about 52%), female (about 62%), and majored in Education Science (about 47%). Analyses of the self-report survey data show that students used digital libraries on a weekly basis (M = 3.52, SD = 1.45), using a 6-point Likert-scale (1 = Never and 6 = More than 4 times per day). Results also show that students’ computer literacy skills were pretty good (M = 3.82, SD = 0.88), based on a 5-point Likert-scale (1 = No experience and 5 = Very skilled). On average, students’ attitudes toward digital libraries were positive (M = 4.21, SD = .68), measured by a 5-point Likert-scale (1 = Strongly disagree and 5 = Strongly agree). In general, the level of students’ perceived usability of digital libraries was moderate (M = 3.34, SD = .49), according to a 5-point Likert-scale (1 = Strongly disagree and 5 = Strongly agree). Results of linear regression and independent-samples show that students’ computer literacy skills were a significant predictor of their use of digital libraries, attitudes toward digital libraries, and perceived usability of digital libraries. The more skilled students were in computer literacy, the more likely they would use digital libraries (β = .299, t(221) = 2.57, p = .01); the more skilled they were in computer literacy, the more positive their attitudes were toward digital libraries (β = .201, t(225) = 3.70, p <. 001); and the more skilled they were in computer literacy, the higher the level of the perceived usability of digital libraries was (β = .115, t(202) = 2.99, p = .003). Only the access to technology and the Internet at school was significantly and positively related to students’ attitudes toward digital libraries. No relationships were found between the access to technology and the Internet (either at school or at home) and students’ use of digital libraries or their perceived usability of digital libraries. Regarding the impact of students’ demographic background on the three dependent variables (i.e., students’ use of digital libraries, attitudes toward digital libraries, and perceived usability of digital libraries), only one significant relationship was found. That is, students’ perceived usability of digital libraries was significantly related to their gender. Female students had a higher level of perceived usability of digital libraries