Pemanfaatan Bottom Ash Batubara Menjadi Produk Briket Dengan Penambahan Arang Daun Jati

The use of coal as the primary fossil fuels in Indonesia are increasingly widespread. Now, the use of coal is not only used for the power plant but also a wide range of industries. Resulting from the use of coal bottom ash which can still be used because they save the calorific value for alternative fuel that is becoming briquette product. Through research it is known that the bottom ash can be processed into briquettes products with the addition of teak leaves charcoal to improve its quality.This study was conducted with a variety of compositions between bottom ash and teak leaves charcoal. The treatment uses ratio of coal bottom ash : teak leaves charcoal 0%:100%, 20%:80%, 40%:60%, 50%:50%, 60%:40%, 80%:20% and 100%:0%. The results showed that the optimum variation of briquettes is a variation of 20 % coal bottom ash and 80% teak leaves charcoal, this briquettes has a water content of 4,052 %,ash content of 36,358 %, calorific value of 4.520 cal/g, compressive stength of 2,383 kg/cm2,CO 54 ppm or 61,84 mg/Nm3,Cu 0,85 µg/g and Zn 1,21 µg/g.The result of the briquttes characteristics test showed that with increasing amounts of teak leaves charcoal can increase the moisture content and calorific value, and be able to lower ash content and compressive strength

Interface modification of clay and graphene platelets reinforced epoxy nanocomposites: a comparative study

The interface between the matrix phase and dispersed phase of a composite plays a critical role in influencing its properties. However, the intricate mecha-nisms of interface are not fully understood, and polymer nanocomposites are no exception. This study compares the fabrication, morphology, and mechanical and thermal properties of epoxy nanocomposites tuned by clay layers (denoted as m-clay) and graphene platelets (denoted as m-GP). It was found that a chemical modification, layer expansion and dispersion of filler within the epoxy matrix resulted in an improved interface between the filler mate-rial and epoxy matrix. This was confirmed by Fourier transform infrared spectroscopy and transmission electron microscope. The enhanced interface led to improved mechanical properties (i.e. stiffness modulus, fracture toughness) and higher glass transition temperatures (Tg) compared with neat epoxy. At 4 wt% m-GP, the critical strain energy release rate G1c of neat epoxy improved by 240 % from 179.1 to 608.6 J/m2 and Tg increased from 93.7 to 106.4 �C. In contrast to m-clay, which at 4 wt%, only improved the G1c by 45 % and Tg by 7.1 %. The higher level of improvement offered by m-GP is attributed to the strong interaction of graphene sheets with epoxy because the covalent bonds between the carbon atoms of graphene sheets are much stronger than silicon-based clay

Integral equation formulations of exterior acoustic scattering problems

The work presented in this thesis is particularly concerned with a robust integral equation formulation of acoustic scattering and radiation problems, which are essentially exterior Neumann boundary-value problems. Both layer theory and the Helmholtz formula, used in the classical formulation (pre- 1968), result in a non-uniqueness problem. This non-uniqueness is purely mathematical and has no bearing on the actual physical problem. Various workers over the past two decades or so developed alternative formulations, which resolve the problem of non-uniqueness but also suffer from computational drawbacks. Kussmaul (1969) developed a formulation involving the superposition of a simple-layer potential and a double-layer potential, combined by a coupling parameter. Kussmaul also presented a uniqueness proof valid for all wave- numbers. However his formulation involves an integral operator which has a hypersingular kernel. This creates computational difficulties. My thesis presents a new integral equation formulation which involves the superposition of a layer potential generated by simple sources on the given boundary, plus a layer potential generated by dipole sources located on an interior boundary similar and similarly situated to the given boundary. These two potentials are also combined by a coupling parameter. However, unlike the Kussmaul formulation, this avoids the integral operator containing the hypersingular kernel. An argument towards uniqueness is presented. Some test radiation problems and some scattering problems are investigated. Numerical results are given which show that the new formulation gives excellent agreement with the analytical results. The thesis also presents a derivation of wave-functions via layer potentials generated by a uniform distribution of sources on a spherical surface. This is utilized in the discussion of the hypersingular kernel of a certain integral operator, and the analysis is used to verify Terai’s (1980) result for a hypersingular integral on a flat plate

Evaluating the Effectiveness of Lumber Corset Wearing in Low Back Ache: A Rehabilitation Center Based Cross-sectional Study

Patients are most commonly advised by medical practitioners even after remaining wide range of controversy regarding wearing of lumber corset in low backache (LBA). Therefore, this study aimed to determine the potential evidence of using lumber orthosis in LBA. The study adopted 50 participants (21 male and 29 female) ages ranging between 20 to 60 years as sample selecting randomly from September to December 2015. Outcome evaluated by calculating and presenting descriptive statistics at 0.05 p-value and x2 test with confidence intervals (95%), Odd Ratio (OR), and Relative Risk (RR). Age and sex were not statistically significant determinants (x2 1.172, p 0.279 and x2 0.593, p 0.441, respectively). Wearing orthosis and reduce pain in a journey found as protective (RR 0.79 and RR 0.94) also poor relationship discovered in considering OR (OR 0.242, 95% CI 0.021-2.780 and OR 0.857, 95% CI 0.164-4.467). Our data were unable to provide adequate proof that wearing lumber corset bring any clinical or therapeutic benefit in managing LBA to the patients

Sympathetic Activation in Deadlines of Deskbound Research - A Study in the Wild

Paper and proposal deadlines are important milestones, conjuring up emotional memories to researchers. The question is if in the daily challenging world of scholarly research, deadlines truly incur higher sympathetic loading than the alternative. Here we report results from a longitudinal, in the wild study of n = 10 researchers working in the presence and absence of impeding deadlines. Unlike the retrospective, questionnaire-based studies of research deadlines in the past, our study is real-time and multimodal, including physiological, observational, and psychometric measurements. The results suggest that deadlines do not significantly add to the sympathetic loading of researchers. Irrespective of deadlines, the researchers' sympathetic activation is strongly associated with the amount of reading and writing they do, the extent of smartphone use, and the frequency of physical breaks they take. The latter likely indicates a natural mechanism for regulating sympathetic overactivity in deskbound research, which can inform the design of future break interfaces

The Experience of International Students and Institutional Recommendations: A Comparison Between the Students From the Developing and Developed Regions

Prior studies on the experiences of international students in China have mostly focused on their academic, sociocultural, and accommodation experiences. Hence, student health and safety, discrimination, and the services by the International Student Office (ISO) have remained unexplored. Moreover, due to the motivational differences between the students from developing and developed regions, a study that samples students from both regions may depict an exact picture of the experience of international students. Therefore, the objective of this study is to examine the influence of the dimensions (including those dimensions that have been ignored) of the experience of international students on their satisfaction. In addition, we make recommendations regarding Chinese institutes for future students based on a comparison between the students from developing and developed regions. Using hierarchical regression analysis, this study reveals that educational and non-educational experiences vary among students from different regions. Therefore, based on developing (e.g., Asia and Africa) and developed (e.g., America, Europe, and Australia) regions, important recommendations are discussed regarding how educational institutions and the Chinese government could best allocate resources and introduce policies to improve the experience of international students

Active involvement of students in co-curriculum (sports) versus generic skills

The active involvement of students in sports activities is viewed from different levels of achievement beginning with the national representation of the residential colleges, faculties, and universities in prestigious sporting events at international levels. The skills that are developed through extra-curricular activities are generic skills. The involvement of students in co-curricular activities can help to shape their generic skills, thus leading to self-promotion in the workplace. Therefore, the purpose of this research was to examine the enhancement of generic skills among engineering and technical students of UTHM who are actively involved in co-curricular activities (sports). This study will focus on identifying the factors of involvement, the level of application among students, and the perceptions of the students through their active involvement in extra-curricular activities (sports). A survey was conducted using a quantitative approach. A general questionnaire, which was designed to fulfil the objectives and to answer the research questions for this study, was distributed to 213 engineering and technical student athletes of UTHM who are actively involved in co-curricular activities (sports). It was found that the engineering and technical student athletes of UTHM agreed that their active involvement in extra-curricular activities (sports) was due to interpersonal, intrapersonal and structural factors. The results showed that out of seven generic skills, three constructs of generic skills, namely communication, teamwork and management, demonstrate a high level of application through active involvement in extra-curricular activities (sports). These findings may also help the university to focus on the development of generic skills in engineering and technical students through co-curricular activities (sports) in addition to producing athletes who are able to create a name for the university at national or international level

Development and in-vitro Evaluation of Once Daily Tablet Dosage Form of Loxoprofen Sodium

Purpose: To formulate and characterize once daily controlled release tablet of loxoprofen sodium.Methods: Eudragit RS-100, hydroxylpropyl methylcellulose (HPMC) and pectin were used as release retarding polymers. All the formulations were prepared by direct compression method. Various precompression studies were carried out to determine Hausner’s ratio, Carr’s index, angle of repose, bulk density and tapped density Differential scanning calorimetry (DSC) studies and also post-compression studies to evaluate hardness, friability, weight variation, drug content, in-vitro drug release were conducted on the tablets. The drug release data were subjected to kinetic models, including zero order, first order, Hixon Crowell, Higuchi and Korsmeyer-Peppas.Results: Compressibility index (7.6 ± 1.32 - 12.5 ± 1.43%), Hausner’s ratio (1.08 ± 0.04 - 1.14 ± 0.03), angle of repose (27.78 ± 0.47 - 30.49 ± 0.46°), hardness (6.25 ± 0.27 - 7.21±0.21 kg/cm2), friability (0.14 ± 0.06 - 0.28 ± 0.0 %), weight variation (249.5 ± 2.09 - 251.35 ± 2.41 mg) and drug content  (97.30 ± 0.28 - 103.70 ± 0.31 %) were within generally accepted limits for the pre-and post-compression formulations, respectively. The tablets having the maximum amount of among the three polymers tested as matrix materials, HPMC, represented by F3 tablets, exerted better sustained release properties after 12 h. Release pattern was more of Fickian diffusion followed by Higuchi mechanism.Conclusion: The release of the loxoprofen sodium was optimized up to 12 h.Keywords: Loxoprofen, Sustained release, hydroxypropyl methylcelluose, Pectin, Eudragit, Matrix tablet