National University of Malaysia

About: National University of Malaysia is a education organization based out in Kuala Lumpur, Malaysia. It is known for research contribution in the topics: Population & Heat transfer. The organization has 26593 authors who have published 41270 publications receiving 552683 citations. The organization is also known as: NUM & Universiti Kebangsaan Malaysia.

Effect of ethanol concentration, extraction time and extraction temperature on the recovery of phenolic compounds and antioxidant capacity of Orthosiphon stamineus extracts

Abstract: Optimization of phenolic extraction from Orthosiphon stamineus was carried out in present study by investigating the effects of ethanol concentration (0-100%, v/v), extraction time (60-300 min) and extraction temperature (25-65oC) on the phenolic recovery using single factor experiment. Total phenolic content (TPC), total flavonoid content (TFC) and condensed tannins content (CTC) were used for determination of phenolic compounds while 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical-scavenging capacity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity were used for evaluating the antioxidant capacities of crude extract. Experimental results showed that all extraction parameters had significant (p<0.05) effect on phenolic contents (TPC, TFC and ABTS) and antioxidant capacities (ABTS and DPPH) of crude extract. The optimized conditions for phenolic extraction were 40% ethanol for 120 min at 65oC with values of 2003.4 mg GAE/100 g DW for TPC, 1611.9 mg CE/100 g DW for TFC, 202.4 mg CE/100 g DW for CTC, 765.4 μmol TEAC/100 g DW for ABTS and 2180.9 μmol TEAC/100 g DW for DPPH. DPPH was found to be positively significantly correlated with TPC but negatively significantly correlated with CTC under the influence of ethanol concentration. As a function of extraction temperature, all antioxidant compounds assays (TPC, TFC and CTC) were negatively correlated with antioxidant capacities (ABTS and DPPH).

Synthesis and thermal conductivity characteristic of hybrid nanofluids – A review

Abstract: Most of the researches on nanofluids conducted since the past decade focused on the single type particle based nanofluids. The characteristics of this type of nanofluid are well defined and explored. The advancement in nanomaterial has enabled the production of hybrid nanoparticles (nanocomposites) and recently, there are noticeable amount of researchers investigated on the characteristic of hybrid nanofluids. Therefore, the purpose of this review is to explore the synthesis method used by the researchers to develop hybrid nanofluids. Apart from that, hybrid nanofluid's thermal conductivity, challenges and future direction of this field are discussed. Based on the review, it is found that carbon nanotube is often combined with other material to synthesize hybrid nanoparticles. Hybrid nanofluids exhibit improved thermal conductivity characteristic. However, challenges such as hybrid nanofluids stability, selection of proper hybrid nanoparticles and its complex fabrication process and limited thermal conductivity model for hybrid nanofluids need to be addressed first. Better knowledge and understanding on these area are required in order to develop hybrid nanofluid which is not only provide enhanced thermal conductivity but also stable and does not require complicated synthesis process.

Docosahexaenoic acid-concentrated fish oil supplementation in subjects with mild cognitive impairment (MCI): a 12-month randomised, double-blind, placebo-controlled trial

Abstract: Epidemiological studies have suggested a beneficial effect of fish oil supplementation in halting the initial progression of Alzheimer’s disease. However, it remains unclear whether fish oil affects cognitive function in older people with mild cognitive impairment (MCI). This study investigated the effects of fish oil supplementation on cognitive function in elderly person with MCI. This was a 12-month, randomised, double-blind, placebo-controlled study using fish oil supplementation with concentrated docosahexaenoic acid (DHA). Thirty six low-socioeconomic-status elderly subjects with MCI were randomly assigned to receive either concentrated DHA fish oil (n = 18) or placebo (n = 18) capsules. The changes of memory, psychomotor speed, executive function and attention, and visual-constructive skills were assessed using cognitive tests. Secondary outcomes were safety and tolerability of the DHA concentrate. The fish oil group showed significant improvement in short-term and working memory (F = 9.890; ηp 2 = 0.254; p < 0.0001), immediate verbal memory (F = 3.715; ηp 2 = 0.114; p < 0.05) and delayed recall capability (F = 3.986; ηp 2 = 0.121; p < 0.05). The 12-month change in memory (p < 0.01) was significantly better in the fish oil group. Fish oil consumption was well tolerated, and the side effects were minimal and self-limiting. This study suggested the potential role of fish oil to improve memory function in MCI subjects. Studies with larger sample sizes, longer intervention periods, different fish oil dosages and genetic determinations should be investigated before definite recommendations can be made.