Mathematical Modelling of Lithium-ion Concentration in Rechargeable Lithium Batteries

The demand for lithium ion batteries has increased due to the increasing need by consumers for rechargeable batteries. In the effort to produce high performance batteries, mathematical model becomes a vital instrument in helping batteries developers to understand the behaviour of the battery systems during charge and discharge process. This understanding is useful in the optimization of the battery design and parameters. This paper presents a mathematical model used to simulate the intercalation process of lithium ions in the electrode of a lithium-ion battery. This model is used to study the intercalation process through the lithium-ion concentration profiles during charge/discharge of a rechargeable lithium-ion battery. This approach resulted in solving the diffusion equation in the solution phase and the solid phase of the battery. Results from both phases are plotted and compared. (Abstract by authors

Particle size analysis on ginger essential oil nanoemulsions

Ginger essential oil has various biological properties such as antioxidant and anti-inflammatory. However, ginger essential oils has its own weaknesses, such as high volatility, low absorption, and poor water-solubility. Transdermal drug delivery is one of the alternatives to transport ginger essential oil into the body. The transdermal drug delivery system which is a nanoemulsion was introduced to overcome the weakness of essential oil. The droplet size of a nanoemulsion is an important property which determines the stability and ease of penetration. In this research, the nanoemulsions were prepared using a spontaneous emulsification method. The effect of preparation conditions and system composition on particle size of ginger essential oil nanoemulsions were examined. In organic phase, ginger essential oil and surfactants which are Tween 40, 60 and 80 were used. In aqueous phase, distilled water and co-solvent (glycerol) were used. For nanoemulsion formation, the organic phase was slowly added into the aqueous phase while being stirred at 500 rpm. The surfactant type had a major effect on particle size, where the smallest droplets particle size were formed by using Tween 80 (15.40 nm). The surfactant concentration also shows a great impact on particle size, where at surfactantto- emulsion ratio (SER) 25 %, the smallest droplets were formed (11.3 nm). By increasing the temperature of organic phase and stirring speed, the particle size was reduced with the smallest droplets being formed at 90 °C (11.16 nm) and at 800 rpm (11.23 nm). Co-solvent addition also had shown an impact on particle size where at 10 % of co-solvent concentration, the smallest droplets were formed (11.22 nm). For thermodynamic stability, nanoemulsions with SER 15 %, 20 %, 25 % and 30% had shown a great stability with no phase and size separation. For storage stability, the droplets particle size were increased by 23 % throughout the two months of storage. In conclusion, a smaller droplet particle (< 15 nm) can be formed by optimizing the system composition and homogenization conditions of nanoemulsions

The Gravity Model between Malaysia and selected EU countries

This study applied the Gravity Model to estimate the factors influence the trade and assess the trade potential between Malaysia and selected major trading partners of the EU countries. The model was estimated with a sample of five selected EU countries: Germany, United Kingdom, Netherlands, Belgium and France. A panel data analysis was used to disentangle the time invariant country-specific effect, and to capture the relationship between the relevant variables across time. The findings showed that the random effect was preferred over the fixed effect specification in the Gravity Model. Additionally, the variables, namely the gross domestic product, gross domestic products per capita, distance, and exchange rate were found to be the significant determinants in the bilateral trade flows. The trade potential is also found yet to be explored fully. Based on these findings, various policy implications and recommendations are suggeste

Pemisahan dan pencirian sebatian semulajadi daripada kayu Vitex vestita (Verbenaceae)

Sampel kayu Vitex vestita (Verbenaceae) telah dikutip dari Hutan Simpan Bukit Belata, Hulu Selangor, Selangor. Kajian ini melibatkan penyaringan fitokimia, keaktifan biologi dan pemencilan komponen kimia dalam ekstrak metanol kayu. Penyaringan fitokimia dijalankan bagi menentukan kehadiran alkaloid, flavonoid, triterpena/steroid dan saponin manakala ujian biologi dijalankan bagi menilai ketoksikan ekstrak tersebut menggunakan ujian kematian anak udang (UKAU). Ujian awal fitokimia mendapati hanya sebatian steroid hadir dalam ekstrak manakala UKAU memberi LC > 1000 ppm. Pemisahan komponen kimia 50 ekstrak dilakukan dengan menggunakan kromatografi cecair vakum, kromatografi radial dan lapisan nipis penyediaan. Dua sebatian telah dipencilkan dan dikenalpasti sebagai 3-epi-20-hidroksiekdison dan 2,3,14,20 ,22,25-heksahidroksikolesta-4,6-diena. Struktur kedua-dua sebatian dielusidasi dengan pelbagai kaedah spektroskopi seperti spektroskopi ultralembayung (UL), inframerah (IM), jisim dan resonans magnet nukleus (RMN) serta secara perbandingan data spektrum diperolehi dengan data spektrum kepustakaan

Surface sediment analysis on petroleum hydrocarbon and total organic carbon from coastal area of Papar to Tuaran, Sabah

Total petroleum hydrocarbons (TPH) and total organic carbon (TOC) were investigated in surface sediments along coastal area of Papar to Tuaran, Sabah. Surface sediment samples were collected in 24 different stations in each area by using Ponar grab sampler. Samples were extracted for TPH using standard method sediment/sludge APHA 5520E and analyzed using UV/VIS spectrophotometer while for TOC method analysis using United Nations Environment Programme (UNEP)/MAP Athens (2006). The range of TPH concentrations in surface sediments were recorded at 0.24 – 20.65 mg/kg dw Miri crude oil equivalents, meanwhile the TOC percentage ranged from 0.03 – 4.02%. In the mean time, the statistical analysis by Pearson correlation showed a positive correlation with coefficient, r = 0.790 which showing the TPH concentrations significantly have influence on the TOC accumulations in the surface sediment

Graphene growth at low temperatures using RF-plasma enhanced chemical vapour deposition

The advantage of plasma enhanced chemical vapour deposition (PECVD) method is the ability to deposit thin films at relatively low temperature. Plasma power supports the growth process by decomposing hydrocarbon to carbon radicals which will be deposited later on metal catalyst. In this work, we have successfully synthesis graphene on Ni and Co films at relatively low temperature and optimize the synthesis conditions by adjusting the plasma power. Low temperature growth of graphene was optimized at 600°C after comparing the quality of as-grown graphene at several temperatures from 400 to 800°C and by varying plasma powers in the range of 20 - 100 W. Raman analysis of the as-grown samples showed that graphene prefers lower plasma power of 40 W. The annihilation of graphene formation at higher plasma powers is attributed to the presence of high concentration of hydrogen radical from methane which recombines with carbon elements on thin film surface. The optimum graphene growth conditions were obtained at growth temperature of 600°C, plasma power of 40 W and growth time of 10 min with methane flow rate of 120 sccm

Integrating Technology in Government Internal Audit: Catalysts and Challenges

In an era marked by digital transformation, various sectors, including government entities, are reevaluating their operational methodologies. This research delves into the pivotal elements influencing the adoption of Information Technology (IT) within the internal audit departments of governmental agencies. The study is grounded in detailed interviews conducted at three distinct government organizations, revealing the intricate dynamics of incentives, barriers, and the prospective benefits associated with IT integration. Preliminary results suggest that a myriad of factors critically shape the strategy toward IT implementation. These include the anticipated enhancements in audit efficiency and effectiveness due to IT adoption, the level of support from senior management, budgetary constraints, and the lack of specialized IT expertise. The findings offer insightful recommendations for government bodies, aiming to aid them in navigating the complexities of IT integration. This study not only highlights the significant role of supportive leadership and resource allocation in facilitating IT adoption but also underscores the need for skill development in this domain. Ultimately, it serves as a strategic guide for government agencies to optimize their auditing processes through effective IT integration

The supervisory styles of supervisors as perceived by counselling interns in Malaysia

Supervisors play different roles and styles during supervision process. However, the styles of supervisors in Malaysia has not been explored and investigated thoroughly. Therefore, the purpose of this study is to identify the prevalent supervisory styles among supervisors in Malaysian public universities as perceived by counselling interns. Descriptive research design was used in this study. Sample size of 138 respondents from four public universities in Malaysia were chosen through stratified random sampling technique. The inventory used to measure the styles was The Adapted Supervisory Styles Inventory by [1]. The inventory measures four type of supervisory styles namely; Directive Teacher Style, Supportive Teacher Style, Counsellor Style and Consultant Style. The findings showed that most of the respondent perceived their supervisors using Supportive Teacher Style followed by Directive Style during supervision process. Practical and theoretical implications are then discuses

SIMULATION OF KORTEWEG DE VRIES EQUATION

Korteweg de Vries (KdV) equation has been used as a mathematical model of shallow water waves. In this paper, we present one-, two-, and three-soliton solution of KdV equation. By definition, soliton is a nonlinear wave that maintains its properties (shape and velocity) upon interaction with each other. In order to investigate the behavior of soliton solutions of KdV equation and the interaction process of the two- and three-solitons, computer programs have been successfully simulated. Results from these simulations confirm that the solutions of KdV equation obtained are the soliton solutions. (Abstract by authors