Articles

Seed coat macadamia preparation of activated carbon with chemical agent K2CO3 from macadamia shells as per ratio: K2CO3: distilled water = 1:1:10ml, optimal temperature condition 6500C and burning time 60 minutes. Efficiency removal of zinc (II) in wastewater efficiency (53.42%) with the concentration of 25ppm, conducted a survey at pH = 4.5 with 1.8g/l of carbon, treated in 100 minutes. Survey results have similarities with other studies and are applicable to application removal of zinc (II) in wastewater.

The study was conducted at Fuji Seal Vietnam Co., Ltd. to examine the exposure and health risks of workers working in the printing and ink phase area when exposed to solvent vapor through the respiratory apparatus Toluene, Methyl Ethyl Ketone, Ethyl Acetate, Isopropyl Acohol. The results show that: During the monitoring period from July to November 2016, the amount of solvent vapor in the printing area and ink phase is quite high, at the highest Toluene printing area, it was 2.63 times higher than the standard equal to the health risk HQ male is 2.61 and HQ female is 3.37; Ethyl Acetate exceeded the highest of 4.34 times equal to the male HQ risk ratio of 4.29 and female HQ equal to 5.53; MEK exceeds 8.43 times equal to the health risk HQ male is 8.36 and HQ female is 10.79; Isopropyl Acohol exceeds 8.4 times equal to the health risk HQ male is 8.33 and HQ female is 10.75; At the inking area, MEK exceeds 8.43 times equal to the health risk HQ male is 8.36 and HQ female is 10.79. From the calculated data - analysis, found that the health of workers working in the printing and inking areas had high risks, the ability of workers suffering from diseases such as he dache, dizziness, skin damage,... and especially respiratory failure.

Survey of methylene orange wastewater treatment by activated carbon material prepared from macadamia husk with chemical activator H3PO4 shows that coal with the best methylene orange color treatment is achieved Optimal conditions such as pH = 5, coal dose 0.9 g/L and time 120 minutes. The results show that it is applicable to color wastewater treatment and the results are similar to other research results.

Investigate the possibility of treating wastewater containing heavy metals Zn2+ with activated carbon material prepared from macadamia shell with chemical activating agent H3PO4, showing high efficiency of adsorption of Zn2+. The results of the study showed that activated carbon with H3PO4 activating agent has high adsorption capacity, capable of handling Zn2+ best at pH = 4.5, dosage 1.8 g/L and time is 120 minutes. . The results show similarities with other research results and are capable of treating wastewater containing heavy metals Zn2+.

This study investigated grammatical difficulties encountered by students of the People’s Police University while learning grammar in ESP courses. The design included questionnaires to teachers and students, and classroom participant observations. The findings indicated that the student respondents only perceived four target features to be difficult to learn. The results also showed that the students’ perceptions of grammatical difficulty were influenced by several factors including the inherent complexity of rules, L1 transfer, students’ differences in language aptitude, students’ infrequency of practice, and teaching methodology. The findings will hopefully be useful for teachers and researchers with an interest in this line of research.

In this article, a class of Hindmarsh-Rose model is studied. First, all necessary conditions for the parameters of system are found in order to have one stable fixed point which presents the resting state for this famous model. After that, using the Hopf’s theorem proofs analytically the existence of a Hopf bifurcation, which is a critical point where a system’s stability switches and a periodic solution arises. More precisely, it is a local bifurcation in which a fixed point of a dynamical system loses stability, as a pair of complex conjugate eigenvalues cross the complex plane imaginary axis. Moreover, with the suitable assumptions for the dynamical system, a small-amplitude limit cycle branches from the fixed point.

This article introduces the general issues and benefits of simulation in teaching and scientific research. Thereby, the author illustrates by making 3D drawings, assemblies, videos simulating machine structures for teaching Theoretical mechanics, Construction machine subjects and the author's studies in the mechanical field. The application of simulation in teaching is to create videos by using Solidworks software, simulating the operating principle of machine structures. After that, show the videos to the students, excite them and make the lesson lively. And the simulation application in scientific research is mentioned as the way to use 3D drawings and simulation videos to preview the research results, promptly fix the wrong places. Since then, the research is quick, cost reduction is not worth it. The results of this paper are to point out the unique benefits that contribute positively to simulation in teaching and in scientific research.