A REVIEW OF MIXED REVERSE MICELLE SYSTEM FOR ANTIBIOTIC RECOVERY

This article discusses the application of mixed reverse micelles in downstream processing of antibiotics. Purification and recovery processes for antibiotics in downstream processing are major expenses, about 70% of the total cost of production, giving them a significant impact on manufacturing cost. Moreover, there are a number of challenges and difficulties in the separation process requirements for antibiotics, since the mixture is quite complex, with broth, hazardous solvents, by-products, intermediate material, and impurities; in addition, antibiotics are easy to denature. Therefore, the development of effective separation techniques is required to produce high-purity of biomaterials. The use of reverse micelles is thought to be among the most promising due to the process's high selectivity and efficiency. Most studies on reverse micelle extraction technology have been performed by using anionic surfactant sodium bis (2-ethyl-1-hexyl) sulfosuccinate (AOT). However, the activities of antibiotics hosted in this type of surfactant have a significant effect due to the strong electrostatic and hydrophobic interaction between antibiotic and surfactant molecules. Due to these problems many alternatives have been developed recently, and reverse micelles have high potential in the purification of biomolecules. Therefore, this review discusses the ability of mixed ionic-nonionic reverse micelles to provide a safe microenvironment for antibiotics by maintaining the strength of attraction between the reverse micelle molecule and the antibiotic while avoiding the denaturation of the antibiotic. The article highlights the potential of mixed ionic-nonionic reverse micelle technology as a tool of antibiotic recovery from various mediums.     

Optimized conditions for the grafting reaction of poly(methyl methacrylate) onto oil‐palm empty fruit bunch fibers

This article describes the graft copolymerization of poly(methyl methacrylate) (PMMA) onto oil‐palm empty fruit bunches (OPEFBs) with a fiber length of less than 75 μm. The graft copolymerization was carried out under a nitrogen atmosphere by a free‐radical initiation technique in an aqueous medium. Hydrogen peroxide and ferrous ions were used as a redox initiator/cocatalyst system. The PMMA homopolymer that formed during the reaction was removed from the grafted copolymers by Soxhlet extraction. Determining the effects of the reaction period, reaction temperature, and monomer concentration on the grafting percentage was the main objective, and they were investigated systematically. The optimum reaction period, reaction temperature, monomer concentration, and initiator concentration were 60 min, 50°C, 47.15 × 10^?3 mol, and 3.92 × 10^?3 mol, respectively. The maximum percentage of grafting achieved under these optimum conditions was 173%. The presence of PMMA functional groups on OPEFB and the enormous reduction of the hydroxyl‐group absorption band in PMMA‐g‐OPEFB spectra provided evidence of the successful grafting reaction. The improvement of the thermal stability of PMMA‐g‐OPEFB also showed the optimal achievement of the grafting reaction of PMMA onto OPEFB. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Biodiesel fuels from palm oil via the non-catalytic transesterification in a bubble column reactor at atmospheric pressure: A kinetic study

Biodiesel has become more attractive recently because of its environmental benefits and the fact that it is made from renewable resources. Transesterification of vegetable oils with short-chain alcohol has long been a preferred method for producing biodiesel fuel. A new reactor was developed to produce fatty acid methyl esters (FAME) by blowing bubbles of superheated methanol vapor continuously into vegetable oil without using any catalysts. A kinetic study on the non-catalytic transesterification of palm oil was made in a reactor without stirring at atmospheric pressure. The effects of reaction temperatures (523, 543, and 563 K) on the rate constant, conversion, yield of methyl esters (ME) and composition of the reaction product under semi-batch mode operation are investigated. The activation energy and the frequency factor values of the transesterification reaction obtained in this experiment are 31 kJ/mol and 4.2, respectively. The optimum reaction temperature which gives the highest ME content (95.17% w/w) in the reaction product is 523 K, while the rate constant of the total system increased with reaction temperature.     

Evaluation of Elemental Distributions in Wild-Caught and Farmed Pangasius sp. Using Pattern Recognition Techniques

The concentrations of Na, Mg, K, Ca, Cr, Fe, Ni, Cu, Zn, As, Se, and Pb in various tissues of Pangasius sp. were determined using microwave-assisted digestion/inductively coupled plasma–mass spectrometry. The clustering tendency related to elemental patterns associated with tissue variants and fish habitats were explored using hierarchical cluster analysis and principal component analysis. The results revealed that the general elemental accumulation pattern was strongly dependent on the type of tissue, whereas latent deviations within particular tissue samples can be linked to the natural variability between wild-caught and farmed fish. The inherent elemental patterns allowed us to differentiate between those wild-caught and farmed fish through linear discrimination analysis with 100% precision. In terms of food safety, the elemental concentrations in edible muscle were found to be far below the legal limits, as the associated health risks at the 90th percentile were well within tolerable regions, although wild-caught fish were found to pose a higher risk.     

Solid-state 13C NMR study of palm trunk cell walls

Trunk material from the oil palm Elaeis guineensis was dissected into parenchyma and vascular bundle fractions, which were individually examined by ¹³C solid-state nuclear magnetic resonance at low field (25 MHz). Cross-polarisation and magic-angle spinning were used with dipolar dephasing to reveal the aromatic carbons of lignin free from interference by carbohydrate. The lignin contents of the parenchyma and vascular bundles were found to be 240 g kg^?1 and 130 g kg^?1, respectively. The lignin appeared to contain a high proportion of aryl ether-linked syringyl units, but little or no ferulic or p-coumaric acid. The cellulose of both fractions had a high proportion of the crystalline component. The acetyl content was c 6 mol %C. The in-vitro digestibility of the two fractions was measured using the rumen liquor-pepsin method and was found to be low compared with forage materials: 19.5% in the parenchyma and only 11.1% in the vascular bundles.     

Oil palm biomass as a sustainable energy source: A Malaysian case study

It has been widely accepted worldwide that global warming is by far the greatest threat and challenge in the new millennium. In order to stop global warming and to promote sustainable development, renewable energy is a perfect solution to achieve both targets. Presently million hectares of land in Malaysia is occupied with oil palm plantation generating huge quantities of biomass. In this context, biomass from oil palm industries appears to be a very promising alternative as a source of raw materials including renewable energy in Malaysia. Thus, this paper aims to present current scenario of biomass in Malaysia covering issues on availability and sustainability of feedstock as well as current and possible utilization of oil palm biomass. This paper will also discuss feasibility of some biomass conversion technologies and some ongoing projects in Malaysia related to utilization of oil palm biomass as a source of renewable energy. Based on the findings presented, it is definitely clear that Malaysia has position herself in the right path to utilize biomass as a source of renewable energy and this can act as an example to other countries in the world that has huge biomass feedstock.     

Irradiation Modification of PVC/NBR Blend

Electron beam initiated cross-linking on the 50/50 poly(vinyl chloride), PVC/acrylonitrile butadiene rubber, NBR blend was studied in the absence and presence of 4 phr trimethylolpropane triacrylate (TMPTA). The 50/50 NBR/PVC blend was prepared by mixing in a Brabender Plasticoder at 170°C. The blend was then irradiated by using a 3.0 MeV electron beam machine at doses ranging from 0 to 200 kGy in air and room temperature. The changes in gel fraction, tensile strength, hardness, impact strength, scanning electron micrographs and dynamic mechanical properties of the samples were investigated. The gel fraction results indicate that under the irradiation conditions employed, the PVC/NBR blend cross-linked by electron beam irradiation. The addition of TMPTA was found to be effective in the acceleration of the radiation-induced cross-linking. Gradual increases in mechanical properties with irradiation dose were observed before exhibiting a decline due to embrittlement as a consequence of excessive cross-linking at higher irradiation doses. The gradual changeover from ductile to brittle fracture due to the irradiation-induced cross-linking was evident from the SEM examination The increase in the storage modulus and T_g as well as the reduction in the damping peak with the increase in irradiation dose reveal that the enhancement in mechanical properties of NBR/PVC blends upon irradiation is due to the irradiation-induced cross-linking, as well as the improved interaction between NBR and PVC.     

An overview of time-based and condition-based maintenance in industrial application

This paper presents an overview of two maintenance techniques widely discussed in the literature: time-based maintenance (TBM) and condition-based maintenance (CBM). The paper discusses how the TBM and CBM techniques work toward maintenance decision making. Recent research articles covering the application of each technique are reviewed. The paper then compares the challenges of implementing each technique from a practical point of view, focusing on the issues of required data determination and collection, data analysis/modelling, and decision making. The paper concludes with significant considerations for future research. Each of the techniques was found to have unique concepts/principles, procedures, and challenges for real industrial practise. It can be concluded that the application of the CBM technique is more realistic, and thus more worthwhile to apply, than the TBM one. However, further research on CBM must be carried out in order to make it more realistic for making maintenance decisions. The paper provides useful information regarding the application of the TBM and CBM techniques in maintenance decision making and explores the challenges in implementing each technique from a practical perspective.