Universiti Teknologi Petronas

About: Universiti Teknologi Petronas is a education organization based out in Ipoh, Malaysia. It is known for research contribution in the topics: Adsorption & Ionic liquid. The organization has 6127 authors who have published 11284 publications receiving 119400 citations.

Towards multilevel mental stress assessment using SVM with ECOC: an EEG approach

Abstract: Mental stress has been identified as one of the major contributing factors that leads to various diseases such as heart attack, depression, and stroke. To avoid this, stress quantification is important for clinical intervention and disease prevention. This study aims to investigate the feasibility of exploiting electroencephalography (EEG) signals to discriminate between different stress levels. We propose a new assessment protocol whereby the stress level is represented by the complexity of mental arithmetic (MA) task for example, at three levels of difficulty, and the stressors are time pressure and negative feedback. Using 18-male subjects, the experimental results showed that there were significant differences in EEG response between the control and stress conditions at different levels of MA task with p values < 0.001. Furthermore, we found a significant reduction in alpha rhythm power from one stress level to another level, p values < 0.05. In comparison, results from self-reporting questionnaire NASA-TLX approach showed no significant differences between stress levels. In addition, we developed a discriminant analysis method based on multiclass support vector machine (SVM) with error-correcting output code (ECOC). Different stress levels were detected with an average classification accuracy of 94.79%. The lateral index (LI) results further showed dominant right prefrontal cortex (PFC) to mental stress (reduced alpha rhythm). The study demonstrated the feasibility of using EEG in classifying multilevel mental stress and reported alpha rhythm power at right prefrontal cortex as a suitable index.

Synthesis and Physical Properties of Choline Carboxylate Ionic Liquids

Abstract: A series of choline carboxylate ionic liquids (ILs) have been synthesized by neutralization of choline hydroxide solution with acetic, propanoic, butanoic, pivalic, and hexanoic acids. The salts so obtained were characterized by NMR spectroscopy, thermal methods, and elemental analysis. Key physical properties (density, viscosity, and refractive index) were measured for the propanoate, butanoate, and hexanoate salts at temperatures from (293.15 to 353.15) K. The densities were used to estimate the molecular volumes, standard entropies, crystal lattice energies, and thermal expansion coefficients. All five choline carboxylates were found to have cytotoxicities (IC50 values) above 10 mM toward the human breast cancer cell line, MCF-7, indicating they are much less toxic than common imidazolium-based ILs.

Advanced in developmental organic and inorganic nanomaterial: a review

Abstract: With the unique properties such as high surface area to volume ratio, stability, inertness, ease of functionalization, as well as novel optical, electrical, and magnetic behaviors, nanomaterials ha...