PARIDAH TAHIR

This review article summarizes in vitro and in vivo experiments on seaweed anticancer activity and seaweed chemical components. Seaweed use in cancer therapy, chemopreventive randomized control trials (RCTs) and quasi-experiments are discussed. The literature reviewed in this article was obtained from various scientific sources and encompasses publications from 2000–2012. Seaweed therapeutic effects were deemed scientifically plausible and may be partially explained by the in vivo and in vitro pharmacological studies described. Although the mechanisms of action remain unclear, seaweed's anticancer properties may be attributable to its major biologically active metabolites. Much of the seaweed research outlined in this paper can serve as a foundation for explaining seaweed anticancer bioactivity. This review will open doors for developing strategies to treat malignancies using seaweed natural products.

Crystalline nanocellulose was prepared from Semantan bamboo (Gigantochloa scortechinii) via acid hydrolysis and was used to synthesize a nanocomposite of polyaniline/crystalline nanocellulose (PANi/CNC) via in situ oxidative polymerization of aniline in the presence of crystalline nanocellulose. The electrochemical properties of the nanocomposite were studied using a modified PANi/CNC electrode via cyclic voltammetry, and higher current response was observed for the PANi/CNC-modified electrode compared to that for the modified electrode with PANi. The results obtained from EIS displayed lower value of Rct for the PANi/CNCmodified electrode, indicating that the incorporation of CNC into the PANi structure could enhance the electron transfer rate. The characteristic peaks of PANi and CNC were observed in the FTIR spectra of the nanocomposite, indicating the incorporation of CNC inside the nanocomposite structure. Moreover, in the XRD diffractogram, lower crystallinity was observed at ...

ABSTRACT The mechanical properties of adhesive materials change over time, especially when they are subjected to long-term loadings. The significance of this is often overlooked at the design stage. When adhesives are subjected to a constant load, they may deform continuously, depending on temperature, humidity, and cross-link density. This progressive deformation is called creep. It is imperative that reliable accelerated tests be developed to determine the long-term time-dependent performance of adhesives under different environmental conditions. The long-term creep behavior of thixotropic and room temperature cure epoxy-based adhesives reinforced with nano particles were investigated. The adhesives in this investigation are formulated with the target of application for in situ bonding of pultruded rod into timber for the repair and strengthening of timber structures. In this study, two epoxy-based adhesives with added nano particles (silica fume and rubber) were subjected to bending creep tests in accelerated environments. Experimental data showed that the adhesives reinforced with nano rubber particles exhibited less creep deformation than the unreinforced ones. DOI: 10.1061/(ASCE)MT.1943-5533.0000453. (C) 2012 American Society of Civil Engineers.

ABSTRACT The objective of this study was to evaluate physical and mechanical properties of medium density fibreboard (MDF) panels made from kenaf core as function of fibre geometry and refining conditions. Raw material was prepared by using pressure levels of 3, 5 and 7 bar at two heating times, namely 3 and 5 min. The length and width of the fibres were determined employing image analyser. Experimental samples with a target density of 700 kg m−3 were produced with 12% of urea formaldehyde as a binder. Physical properties such as swelling in thickness (TS) and water absorption (WA) of the panels in addition to their mechanical properties including modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding (IB) were evaluated based on MS 1787:2005. Based on the test results, low digestion pressure produced longer fibre length and panels made from these fibres had higher TS with MOR and MOE than those of the others panels. However, the IB properties of samples were low. Panels made from shorter fibre resulted in contradict properties found above. The ideal properties of the samples were found for the panels made having fibre length of 0.81 mm and aspect ratio of 23.4. Such sample had 14.6%, 63.2%, 30.3 MPa, 3619 MPa and 0.66 MPa for TS, WA, MOR, MOE and IB, respectively.

In this study, the effect of superheated steam (SHS) treatment on the changes of the chemical composition and biological properties of two tropical hardwoods was investigated. SHS was carried out on light red meranti (Shorea spp.) and kedondong (Canarium spp.) wood with dimensions of 410 × 25 × 25 mm, using superheated steam as the heating medium. Wood samples were heat-treated at nine treatment levels, ranging from 172 to 228 °C and 95 to 265 min, respectively. The chemical constituents and resistance against white rot fungus (Pycnoporus sanguineus) and subterranean termite (Coptotermus curvignathus) of the treated wood were evaluated. A significant reduction in holocellulose content and increment in lignin was observed after SHS treatment. Consequently, the resistance against white rot fungus and termites improved. The biological durability improved with an increasing treatment temperature and time. A regression analysis revealed that the reduced equilibrium moisture content impar...

Microbial xylanase and pectinase are two extremely valuable enzymes, which have captivated much attention. This can be seen from the increased demand for these enzymes by many industrial sectors. This study investigates the isolation and screening of extracellular xylanopectinolytic enzymes-producing bacteria in a submerged fermentation (SmF). Samples are collected from the compost of empty fruit bunch (EFB) at Biocompost Pilot Plant, located at Biorefinery Plant, Universiti Putra Malaysia. From the experiment, out of 20 isolates, 11 isolates show xylanase or/and pectinase activity, and only one isolate (EFB-11) shows the concurrent activities of xylanase and pectinase. These activities are selected for enzyme production under submerged fermentation (quantitative screening). At the 72nd hour of incubation, xylanase and pectinase show the highest production, which ranges about 42.33 U/mL and 62.17 U/mL (with low amount of cellulase present), supplemented with 2% (w/v) of rice bran as...

Cellulosic nanofibers (NFs) from kenaf bast were used to reinforce glycerol plasticized thermoplastic starch (TPS) matrices with varying contents (0-10wt%). The composites were prepared by casting/evaporation method. Raw fibers (RFs) reinforced TPS films were prepared with the same contents and conditions. The aim of study was to investigate the effects of filler dimension and loading on linear and non-linear mechanical performance of fabricated materials. Obtained results clearly demonstrated that the NF-reinforced composites had significantly greater mechanical performance than the RF-reinforced counterparts. This was attributed to the high aspect ratio and nano dimension of the reinforcing agents, as well as their compatibility with the TPS matrix, resulting in strong fiber/matrix interaction. Tensile strength and Young's modulus increased by 313% and 343%, respectively, with increasing NF content from 0 to 10wt%. Dynamic mechanical analysis (DMA) revealed an elevational tren...

... Forestry (Wood Industry) Project Report. Faculty of Forestry, University Pertanian Malaysia, Serdang, Selangor, Malaysia. 1996. ... Mechanical properties of pineapple leaf fiber-reinforced polyester composites. Journal of Applied Polymer Science, 64(9):1739-1748 (1997). ...

The mechanical properties of adhesive materials change over time, especially when they are subjected to long-term loading regimes. The significance of this is often overlooked at the design stage. When adhesives are subjected to a constant load, they may deform continuously, depending on temperature, humidity and cross-link density. This progressive deformation is called creep and will continue until rupture or yielding causes failure. It is imperative that reliable accelerated tests be developed to determine the long-term time-dependent performance of adhesives under different environmental conditions. The long-term creep behaviors of thixotropic and room temperature cure epoxy based adhesives reinforced with nano-particles specially formulated for in-situ bonding of pultruded rod into timber for repair and strengthening of timber structures were investigated. In this study two epoxy-based adhesives with nano-particles (silica fume and rubber) addition were subjected to bending creep tests, in accelerated environments. Experimental data showed that the adhesives reinforced with nano-rubber particles showed less creep deformation than the unreinforced adhesives.

This research was conducted to study the feasibility of producing medium density fibreboard (MDF) from 4-year old rubberwood clone RRIM 2020. The 4-year old rubberwood is obtained from different planting densities, which is 500, 1000, 1500 and 2000 trees/ha and were processed to produce MDF. The MDF is analyzed in term of its mechanical properties (static bending and densities to comply with JIS A 5905-2006 Standard (Type 30, MOR > 30.0 MPa and MOE > 2500 MPa and Type 25, MOR > 25.0 - 30.0 MPa and MOE > 2000 - 2500 MPa). MDF made from 25 year trees clone, PB260 which come from the same clone was used as a control. The results showed that the PB260 and the 4-year old rubberwood clone with planting densities of 500 trees/ha satisfied the requirement of Type 30, and the remaining passed at Type 25. It shows that it is feasible to produce an MDF using the 4-year old rubberwood clone.

Summary The phenolic content of condensed tannins varies considerably, depending on the method of determination. Even though the Stiasny precipitation number has been commonly used to estimate the amount of reactive tannin towards formaldehyde, particularly in adhesive applications, this estimation alone is not sufficient. In this study two methods of determining the amount of reactive tannin towards formaldehyde were examined. These were (1) the reactivity towards formaldehyde or the Stiasny precipitation number, and (2) the formaldehyde uptake. Five different types of tannin were examined from Rhizophora mucronata, P. radiata, mimosa, quebracho and chestnut. The study indicates that the phenolic content in tannin can be better estimated by determining both the Stiasny number and the amount of formaldehyde uptake. High correlation (r2 = 0.905) was detected between the two methods. The study also revealed that hot water extracts of R. mucronata contain relatively small amounts of reactive polyphenols and are less reactive than sulfite extracts. The consumption of formaldehyde by this type of tannin was only 0.294 molecules per flavanoid unit. Similar to R. mucronata, the sulfite extracts of P. radiata contain relatively high amounts of reactive polyphenols and reacted with substantially higher amounts of formaldehyde per flavanoid unit, comparable to mimosa and quebracho tannins. Nonetheless, the reactivity towards formaldehyde (gel time) of the latter tannins is muchlower, despite their higher polyphenolic content. Of the two methods used to estimate the polyphenolic content of bark extracts, the Stiasny number had a relatively higher correlation (r2 = 0.518) with gel time than formaldehyde uptake (r2 = 0.345) did. The behaviour of these tannins in relation to their reactivity and chemical structures is discussed.

Abstract: A study was undertaken to impregnate bamboo strips (Gigantochloa scortechinii) with low-molecular-weight phenol formaldehyde resin (LMwPF). The bamboo samples were taken from the basal and middle portions of the culm. Upon treatment with LMwPF using vacuum process, the weight percent gain (WPG) and moisture content (MC) of the treated bamboo strips were evaluated. The WPG of the impregnated strips increased when the duration of soaking in the resin increased. After 120 min of soaking, the WPG increased by 4.51 per cent and 7.52 per cent for basal and middle portions, respectively. The MC of the treated strips gradually decreased from the original mean of 20 per cent to 5 per cent after drying in an oven at 60>C for 12 h. The optimum drying duration was approximately 9 h, beyond which the treated samples started to warp.

A study on the evaluation of the selected physical and mechanical properties of multiple leadered Acacia crassicarpa A. Cunn. Ex. Benth, genotype was carried out to maximize its utilization. The study involved two classes of multiple leaders (ML), namely; ML2 (two leadered stems) and ML3 more than two leadered stems and 4 provenances: Claudie River, and Chillie Beach from Queensland (QLD) and Bensbach WP and Bimadebum WP from Papua New Guinea (PNG). ML classes showed significant difference at P<0.05 for physical properties but not between provenances. ML2 produced better mean values of specific gravity, radial and tangential shrinkage, with the values of 0.48%, 1.4% and 2.89% respectively compared to ML3 with values of 0.45, 3.56%, and 5.83%, respectively. Similarly, the ML classes were found to be significantly different at P<0.05 for Modulus of Elasticity (MOE) and Modulus of Rupture (MOR). Once again, ML2 produced higher mean values of 9858.4 N/mm 2

ABSTRACT The aim of the present study was to examine the characteristics and physical properties of low molecular weight phenol formaldehyde resin (LmwPF, mw approximately 600) and modified nanoclay admixture. LmwPF resins (45% w/v) were added separately with 0.5%, 1.0% and 1.5% w/w montmorillonite nanoclay nanomer (based on solid PF). Each of the solution was ultrasonicated in a sonifier. The dispersion of nanoclay in LmwPF was examined using X-ray diffraction (XRD), and transmission electron microscopy (TEM). It was found that ultrasonication in a sonifier at 50 kHz for 60 min was able to disperse modified nanoclay up to 1.5% into the resin. XRD and TEM analyses showed that the nanoclay dispersion in the resin were either intercalated or exfoliated. The results also showed that the presence of nanocaly in the admixture significantly increased the non-volatile content and reduced gelation time and pH values.