Kinetics Studies of Metallic Ions Adsorption by Immobilised Chitosan

Immobilised chitosan on glass plates was used as an adsorbent for metallic ions from aqueous solutions in a batch adsorption system. Experiments were carried out as a function of contact time and initial metallic ions concentration. The adsorption efficiency increased with increasing initial metallic ions concentration (5 – 20 mg L-1) and the observed trend was: Ag2+ > Cu2+ > Ni2+ > Fe3+ > Cd2+ > Zn2+. The experimental data were fitted to pseudo-first, pseudo-second-order, intra-particle, and liquid film diffusion kinetic models. The applicability of the pseudo-second-order kinetic model indicated that the adsorption behaviour was ascribed by chemisorption. Further data analysis by the diffusion kinetic models suggested that the metallic ions adsorption was controlled by more than one step; adsorption at the active sites, intra-particle, and liquid film diffusion.

Genetic Variation Analysis between Wild and Cultured Pangasianodon hypopthalmus Using COI and Cytochrome b Among Asian Countries

One of the top species in the aquaculture sector, known as striped catfish or Pangasianodon hypophthalmus, is an important and valuable freshwater fish in many countries. Due to the high demand for this species, their number has declined to "threatened" levels. Hence, the purpose of this study is to analyse the genetic variation of wild and cultured striped catfish collected from five producers in Asian countries; Thailand, Vietnam, Indonesia, India, and Philippines, by using mitochondrial DNA partial region data sequence; CO1 and cytochrome b gene. Population analyses using 395 base pairs length for CO1 and 275 base pairs length of cytochrome b partial region nucleotide sequence have shown no significance difference between wild and cultured striped catfish. Vietnam species had shown a wide range of genetic distance of the intrapopulation compared with other countries in the range of 0.000-0.040 for CO1 gene and 0.003-0.008 for cytochrome b gene. The Neighbour-joining method has also been used to construct phylogenetic trees using CO1 gene; the tree formed few subclades with mixed populations, and the tree using cytochrome b showed only Vietnam species divided into a few sub-populations. For the other four countries, Thailand, Indonesia, India, and Philippines were in the same group. Hence, this study's findings may provide a reference for inter and intra-relationships of P. hypophthalmus that may help in the aquaculture activity of this striped catfish.

Inhibitory Effect of Oral Thin Films (OTFs) Containing Xylitol Against Streptococcus mutans

Dental Caries is a chronic disease affecting half of the global population, causing pain and discomfort due to progressive damage to the teeth. Whilst xylitol has been studied for its effect on dental caries prevention, current practices present few limitations for its successful oral delivery, including short residence time in the mouth and poor patient compliance. Recently, oral thin films (OTFs) emerged as an alternative to delivering xylitol in the oral cavity. This research aims to develop novel OTFs containing xylitol with extended-release properties (as determined by the disintegration time) and to investigate its effect on a cariogenic bacterial strain, Streptococcus mutans. The minimum inhibitory concentration (MIC) of xylitol was determined. Employing the microdilution broth method, the antibacterial activity of the oral thin films containing xylitol for oral S. mutans was performed with simulated salivary fluid, incubated at 1, 4, and 10 h. The MIC of xylitol was found at 10%. Meanwhile, there was no significant difference in the inhibition of S. mutans (p > 0.05) between the control, OTFs (10 h), and xylitol-OTF (1 h), with the latter, demonstrated only 16.58% inhibition. Interestingly, when compared to xylitol-OTF (1 h), xylitol-OTF showed significant inhibition (p < 0.05) to S. mutans after four h (+53.24 %) and almost a complete inhibition after ten h (-92.58 %). These results suggest that the OTFs demonstrated a gradual release of xylitol and inhibited oral biofilm formation by decreasing the growth of S. mutans in a time-dependent manner. Most importantly, the study indicated the successful development of a novel xylitol-OTF with potential as an oral health biotherapeutic agent.

Lotka-Volterra Model of Wastewater Treatment in Bioreactor System using 4th Order Runge-Kutta Method

Wastewater treatment is essential to preserve the ecosystem and to ensure water resources are uncontaminated. This paper presents the Lotka-Volterra model of nonlinear ordinary differential equations of the interaction between predator-prey and substrate. The dimensionless ordinary differential equations of the model are solved using the 4th Order Runge-Kutta method (RK4) in MATLAB®. This study discusses the behaviour parameters of predators, prey and substrate. The results are shown graphically for different values of each parameter. Hence, the biological reaction of clean water from the interaction of predator-prey and substrate in wastewater treatment is identified. The higher the concentration of prey, the faster the concentration of substrate reaches 0 with and without the natural death of prey. The clean water will be produced whenever the concentration of prey and the concentration of predator are in balance regardless of the natural death rate. Stability analysis using the Jacobian matrix at the equilibrium point is also performed to determine the stability of the system.

In Silico Study of the Effectiveness of 16S rRNA Gene as a Universal Genetic Marker to Identify Closely Related Burkholderia Spp. in Panicle Blight of Rice

The 16S rRNA gene is a housekeeping genetic marker that is available in almost all bacterial species and it is used in bacterial phylogeny and taxonomy studies. In many studies, the 16S rRNA gene is used in identification of certain bacterial species. Being a less conserved genetic marker, certain studies found it is a useful tool to infer the genome-wide similarity levels among the closely related prokaryotic organisms. Thus, this study aimed to compare the variation in the 16S rRNA partial region of Burkholderia spp. that infect the panicle of rice from eight different geographical areas. 58 sequences with total of 688 base pairs (bp) of 16S rRNA gene in B. glumae and B. gladioli were retrieved from public database based on several countries namely United State, Panama, Ecuador, Thailand, China, India, Korea and Malaysia. Then, the data sequences were analysed and validated using MEGAX and ABGD software respectively. The result of phylogenetic tree confirmed that B. glumae and B. gladioli were species that present in the panicle blight of rice. However, Data Analysis in Molecular Biology and Evolution (DAMBE) and Automatic Barcode Gap Discovery (ABGD) software were not able to detect substitution saturation and divergence between B. glumae and B. gladioli respectively based on the 58 sequences of the 16S rRNA partial region. Hence, it proves that 16S rRNA gene is an ineffective genetic marker to be used to differentiate the closely related species of bacteria from similar genus.

Improving the Photostabilization of Poly(vinyl chloride) Using 4-(benzylideneamino)benzenesulfonamide Tin Complex

The photostabilization of poly (vinyl chloride) (PVC) film filled with an organotin complex in its structure was examined and compared with the blank PVC film. The organotin (IV) complex that contains 4-(benzylideneamino) benzenesulfonamide as a ligand was synthesized and applied as a PVC photostabilizer. The impact of the complex on the polymer was assessed by comparing the properties of the films with and without the complex, before and after irradiation, using Fourier transform infrared spectroscopy, weight loss, viscosity change, atomic force microscopy, and field emission scanning electron microscopy (FE-SEM). Results showed that the complex film had lower weight loss, gel content, and molecular weight deterioration than the plain PVC film. Also, surfaces of the complexes-filled films were smoother, less lumpy, and more homogeneous. These findings were obtained via the FE-SEM and light microscope images and confirmed by measuring the roughness factor. The organotin (IV) complex proved its activity in delaying the photo-degradation of PVC by several mechanisms. Ultimately, the Tin complex has effectively protected the PVC film against irradiation. The photostabilization of poly (vinyl chloride) (PVC) film filled with an organotin complex in its structure was examined and compared with the blank PVC film. The organotin (IV) complex that contains 4-(benzylideneamino) benzenesulfonamide as a ligand was synthesized and applied as a PVC photostabilizer. The impact of the complex on the polymer was assessed by comparing the properties of the films with and without the complex, before and after irradiation, using Fourier transform infrared spectroscopy, weight loss, viscosity change, atomic force microscopy, and field emission scanning electron microscopy (FE-SEM). Results showed that the complex film had lower weight loss, gel content, and molecular weight deterioration than the plain PVC film. Also, surfaces of the complexes-filled films were smoother, less lumpy, and more homogeneous. These findings were obtained via the FE-SEM and light microscope images and confirmed by measuring the roughness factor. The organotin (IV) complex proved its activity in delaying the photo-degradation of PVC by several mechanisms. Ultimately, the Tin complex has effectively protected the PVC film against irradiation.

Pollution and Potential Ecological Risk Assessment of Heavy Metals Around the Active Bukit Mendi Palm Oil Mill Area, Bera Pahang, Malaysia

The study on the impact of palm oil mill processing activities on the environment of Bukit Mendi Palm Oil Mill was conducted by determining the distribution of six heavy metal concentrations Cadmium (Cd), Copper (Cu), Manganese (Mn), Lead (Pb), Iron (Fe) and Zinc (Zn) and the selected pollution indices. This study provided some information on the accumulation of heavy metals in the selected area and served to identify the potential sources contributing to these heavy metals. Soil samples were collected from eight sampling sites around the palm oil mill and analysed for the selected metals using ICP-OES. Three types of pollution indices were used to observe the pollution level of the area, namely Enrichment Factor (EF), potential ecological risk index (PERI), and Contamination Factor (CF) of heavy metal content. The average total concentration of the selected metals was found to increase in the order of Fe, Mn, Zn, Cd, Pb, and Cu. The metal Fe showed the highest metal content, followed by Mn at 1573.00 mg/kg and 154.00 mg/kg, respectively. The values of EF showed that the metal was unevenly distributed throughout the sampling areas, where heavy metal content ranged from minimal to extremely high enrichment. The potential ecological risk ranging from low to severe was observed in this study. The CF values revealed that the area was heavily contaminated with Cd and only slightly contaminated with Pb. The pollution indices determined in this study suggested that the study area was moderately contaminated with metals, and the metal Cd was found to be the only metal potentially posing an ecological risk to the area.Keywords: ICP-OES, palm oil mill, heavy metals, soil pollution, pollution indices

Antibacterial Activity and Phytochemical Screening of Erythrina fusca Lour. Leaf Extract (Fabaceae)

Erythrina fusca Lour. (family Fabaceae) is a flowering tree that is locally known as ‘chengkering’. The plant is traditionally used in treatment of some symptoms related to bacterial infections such as wound infections, inflammations, and skin itching. This work reports for the first time in vitro antibacterial screening of the E. fusca Lour. methanolic leaf extract against some common Gram-negative and Gram-positive bacteria such as Klebsiella pneumonia, Proteus vulgaris, Pseudomonas aeruginosa, Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus. The in vitro antibacterial assay was carried out using agar diffusion method with the extract concentration of 3 mg/well and vancomycin 30 µg/well as the positive control. It was found that the extract exhibits antibacterial effects in range of 10.5 – 14 mm of zone of inhibition (ZOI) against all tested bacteria except for K. pneumoniae. P. aeruginosa showing ZOI of 14 mm was the most sensitive bacterium while P. vulgaris (ZOI of 10.5 mm) was the least sensitive strain to the extract. Based on the preliminary phytochemical screening of using standard qualitative phytochemical tests, this species contains significant amount of alkaloids, flavonoids, terpenoids, and tannins, which might contribute to the antibacterial activity of the extract. Both antibacterial potential and presence of various phytochemicals in the extract could support the traditional uses of E. fusca , and the obtained results would serve as a basis for further exploration of antibacterial properties of the plant’s leaves.

Screening of Lactic Acid Fermentation by Rhizopus oryzae on Banana Peel Using Two-Level Factorial Analysis

For ages, pure sugars or edible crops have produced lactic acid. However, a major concern on lactic acid production lies in the cost of the raw materials used. Thus, an alternative to overcome this situation is urgently needed. Characterization of banana peels shows that it contains promising sugar that can be utilized for lactic acid production, which are xylose (0.774 g/L), glucose (0.756 g/L) and fructose (0.532 g/L). Thus, this study aims to screen the potential of banana peel as a substrate by using Rhizopus oryzae through batch fermentation for lactic acid production, as R. oryzae can synthesize lactic acid in low nutrient requirements. Two-level factorial analysis was designed to screen the effects of moisture content (60% and 80%), temperature (27 °C and 40 °C), pH (4.5 and 6.5) and inoculum size (1x104 spores/mL and 1x108 spores/g) on the lactic acid production. Based on the Two-level factorial (2LF) analysis, the highest lactic acid production of 0.0813 g/L was detected at 80 % moisture content, pH 4.5, the temperature of 27 °C and inoculum size of 1x104 spores/g. The findings show that most of the conditions have a significant difference between each other (p<0.05). Therefore, the fermentation of banana peels by R. oryzae could be a promising method to produce a lactic acid concentration.

Cetrimonium Surfactants with Biologically Active Counter Ions as Self-Immolative Drug Delivery Systems

Novel derivatives of cationic surfactant cetyltrimethylammonium bromide (CTAB) possessing anions of ibuprofen and naproxen as hydrophobic counterions were synthesized and characterized using Fourier transform infrared and differential electronic absorption spectroscopy. The self-assembly of each surfactant was investigated using surface tensiometry. The self-immolative nature of these compounds was analyzed through study of their behavior in response to trigger such as medium pH. ADMET-SAR (adsorption, distribution, metabolism, excretion, toxicity – structure-activity relationship) profiles of synthesized surfactants were generated using admetSAR v. 1.0). The cetrimonium drugs exhibited better profiles than the corresponding pure drugs, save the aqueous solubility which was reduced due to hydrophobicity of counterions.