Phytochemical analysis and antioxidant activity of different plant parts of Pellacalyx axillaris

Pellacalyx axillaris or locally known as ‘membuloh’ is a mangrove species belonging to the Rhizophoraceae family. Till date, there has been only one phytochemical study found on this particular plant species and that without any documentation on its biological activities. Therefore, the present work aimed to reveal the phytoconstituents and the antioxidant activity of different crude extracts from different plant parts of P. axillaris. Experimentally, three organic solvents of different polarities i.e. n-hexane, ethyl acetate and methanol were used to prepare the crude extracts from the dried leaves, twigs and barks of P. axillaris. The preliminary phytochemical screening of this species indicated the presence of terpenoids, phenolic compounds, tannins, flavonoids, alkaloids, anthraquinone glycosides and carbohydrates. The in vitro antioxidant activity of the species evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, and ferric reducing antioxidant power (FRAP) suggested that the methanolic bark extract contained potential source of natural antioxidants. Further research into isolation of antioxidant compounds from this species is highly recommended

Application of ultrasonic-assisted enzymatic digestion system for digestion of cockles

Sample preparation is the most time consuming part of elemental analysis where homogeneous samples that are almost free from organic matter is necessary. Therefore, preliminary operations such as separation of interferents and preconcentration of the analytes are required prior to analysis. Ultrasonic digestion recently proposed as an efficient method for extraction of trace metals from solid samples. The ultrasonic digestion was optimized by using two parameters whilst another two other parameters were used in enzymatic digestion. Conventional one-variable-at-a-time (OVAT) optimization method was applied to both digestion techniques. Fe and Zn were extracted from the samples and were determined by using flame atomic absorption spectrometry (FAAS).The combination of ultrasonic and enzymatic digestion techniques is known as Ultrasonic-Assisted Enzymatic Digestion (USAED) method. The ultrasonication equipment used was ultrasonic bath. Four parameters studied for optimization were sample mass, sonication time, protease enzyme volume and incubation time. The optimum condition of parameters for sample mass was 0.2 g, sonication time of 30 min whilst for enzyme volume was 1000 µL and for incubation time of 24 hours. For the kinetic study, these reactions had undergone zero order reaction. This USAED method was successfully applied for the digestion and kinetic study of the cockle samples

Chemical constituents and antioxidant activity of garcinia parvifolia Miq. stem bark

The chemical constituents of GarciniaparvifoliaMiq.stem bark have been studied. The dried samples have been extracted using Soxhlet apparatus to give the crude products. The constituents were separated and purified by using vacuum column chromatography, gravity column chromatography and recrystallisation. The chemical compounds obtained were elucidated by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. Two compounds namely as 1,6,7-trihydroxy-3-methoxyxanthone and 3,8''-binaringenin were isolated from the ethyl acetate crude extracts of G. parvifoliaMiq. The free-radical scavenging activity of the crude extracts were determined by the 2,2- diphenyl-1-picrylhydrazyl (DPPH) assay. The ethyl acetate extract was found to be the most active free radical scavenger with IC50 value of 4.2 ppm, followed by methanol extract (IC50 96 ppm) and petroleum ether extract (IC50 200 ppm)

The Analysis of Student Colla borative Work Inside Social Learning Network Analysis Based on Degree and Eigenvector Centrality

Social learning network analysis is a potential approach to analyze the behaviour of students in collaborative work. However, most of the previous works focus on asynchronous discussion forum as the learning activity.  Very few of them are trying to analyze the students' collaborative work while using wiki e-learning. This paper proposes the degree centrality and eigenvector method for identifying the collaborative work of students while in wiki e-learning. The log data of the Moodle e-learning system is observed that records the students' activities and actions while using wiki.  The result shows that there is a close similarity between the degree centrality and the eigenvector. The result also reveals the students who obtain high outdegree values.  Furthermore, Agent_1 and Agent_12 represent the students who obtained high outdegree values, which mean these two nodes are acting as source providers that able to supply information and knowledge through the network. This result also strengthened by value of closeness and betweenness where Agent_1 and Agent_12 leading on this measurement. The high closeness value of Agent_1 and Agent_12 will lead into fast spreading information since they have fastest route and has the most direct route to the other node inside the network, thus collaborative work is easy to be initialized by these Agents. This work has successfully identified collaborative work of student. This finding is believed to bring enormous benefit on the e-learning system improvement in the future

A Concise Fuzzy Rule Base to Reason Student Performance Based on Rough-Fuzzy Approach

A fuzzy inference system employing fuzzy if then rules able to model the qualitative aspects of human expertise and reasoning processes without employing precise quantitative analyses. This is due to the fact that the problem in acquiring knowledge from human experts is that much of the information is uncertain, inconsistent, vague and incomplete (Khoo and Zhai, 2001; Tsaganou et al., 2002; San Pedro and Burstein, 2003; Yang et al., 2005). The drawbacks of FIS are that a lot of trial and error effort need to be taken into account in order to define the best fitted membership functions (Taylan and Karagözoglu, 2009) and no standard methods exist for transforming human knowledge or experience into the rule base (Jang, 1993)

Cases of contact lens related Acanthamoeba keratitis

Acanthamoeba keratitis is a potentially blinding ocular disease that is often misdiagnosed and remains difficult to treat. If not diagnosed early, it can be devastating to vision. Acanthamoeba keratitis may be associated with previous ocular trauma but the majority of cases in the developed world are associated to contact lens wear. We present two cases of contact lens related Acanthamoeba keratitis whose diagnosis were missed at initial presentation. The history, clinical findings and treatment instituted are briefly discussed here. In the light of prevention of the disease, lessons learnt from these cases especially on the role of poor hygienic practice during of contact lens wear in precipitating the disease, are highlighted

Phylogenetic relationship of non-typeable Haemophilus influenzae isolated in Malaysia

The epidemiology of non-typeable Haemophilus influenzae (NTHi) remains poorly understood. We therefore sought to determine the genetic relationship of 25 NTHi isolated from various states in Malaysia using multilocus sequence typing (MLST). The majority of isolates were obtained from sputum. There were 24 novel sequence types (STs). Eight isolates were single-locus variants, the remainder being singletons. Clustering was not based on clinical site of isolation or geographical origin. Despite the limited number of isolates examined in this study, we demonstrate that NTHi isolates in Malaysia are diverse and warrant further investigation

Student classification in adaptive hypermedia learning system using neural network

Conventional hypermedia learning system can pose disorientation and lost in hyperspace problem that will cause learning objectives hard to achieve. Adaptive hypermedia learning system is the solution to overcome this problem by personalizing the learning module presented to the student based on the student knowledge acquisition.This research aims to use neural network to classify the student whether he is advanced, intermediate and beginner student.The classification process is important in adaptive hypermedia learning system in order to provide suitable learning module to each individual student by taking consideration of the studentsí knowledge level, his learning style and his performance as he learn through the system. Data about the student will be collected using implicit and explicit extraction technique. Implicit extraction technique gathers and analyses the studentís behavior captured in the server log while they navigate through the system. Explicit extraction technique on the other hand collects studentís basic information from user registration data. Three classifiers were identified in determining the studentís category.The first classifier determines the student initial status based on data collected from explicit data extraction technique.The second classifier identifies studentís status from implicit data extraction technique by monitoring his behavior while using the system.The third classifier, meanwhile will be executed if the student has finished studying and finished doing the exercises provided in the system. Further, the data collected using both techniques will be integrated to form a user profile that will be used for classification using simple back propagation neural network

(E)-3-(2H-1,3-Benzodioxol-5-yl)-1-(7-hy­droxy-5-meth­oxy-2,2-dimethyl­chroman-8-yl)prop-2-en-1-one

The reaction of 5,6-(2,2-dimethyl­chromane)-2-hy­droxy-4-meth­oxy­acetophenone and 3,4-methlene­dioxy­benzaldehyde affords the title chalcone derivative, C22H22O6. The two benzene rings are connected through a —C(=O)—CH=CH— (propenone) unit, which is in an E conformation; the ring with the hy­droxy substitutent is aligned at 6.2 (1)° with respect to this unit, whereas the ring with the methyl­enedi­oxy substituent is aligned at 8.2 (1)°. The dihdral angle between the rings is 14.32 (7)°. The hy­droxy group engages in an intra­molecular hydrogen bond with the carbonyl O atom of the propenone unit, generating an S(5) ring