Purification and characterization of cyclodextrin glucanotransferase from alkalophilic Bacillus sp. G1

A cyclodextrin glucanotransferase (CGTase) was successively purified by ammonium sulphate precipitation, and affinity chromatography on a-CD (epoxy)-Sepharose 6B column. The specific activity of the CGTase was increased approximately 2200-fold, from 8.43 U/mg protein to 18,866 U/mg protein. SDS-PAGE showed that the purified CGTase was homogeneous and the molecular weight of the purified CGTase was about 75 kDa. The molecular weight of the enzyme that was estimated by gel filtration under native condition was 79 kDa. This has indicated that Bacillus sp. G1 CGTase is a monomeric protein. The isoelectric point (pI) of the enzyme was about 8.8. Characterization of the enzyme exhibited optimum pH and temperature of 6.0 and 60 8C, respectively. The enzyme was stable from pH 7.0 to 9.0 and retained its high activity up to 60 8C. However, in the presence of 20 mM Ca2+, the purified CGTase is able to prolong its thermal stability up to 70 8C. CGTase was strongly inhibited by ZnSO4, CuSO4, CoCl2, FeSO4, FeCl3 and EDTA. Km and Vmax for the purified enzyme were 0.15 mg/ml and 60.39 mg bcyclodextrin/( ml min), respectively, with soluble starch as substrate. In cyclodextrin production, tapioca starch was found to be the best substrate used to produce CDs. The enzyme produced g- and b-CD in the ratio of 0.11:0.89 after 24 h incubation at 60 8C, without the presence of any selective agents

Near-real-time Biomonitoring of Heavy Metals Using the Xenoassay® System

Heavy metals have widespread industrial uses and have been found in increasing quantities as contaminants in all components of the biosphere. Water and sediment of rivers near industrial areas such as the Juru River in Penang and Langat River in Selangor are polluted with heavy metals. Thus, rapid and fast methods to detect the presence of heavy metals in the environment are necessary. Existing instrumental methods such as atomic absorption and emission spectrometry are very sensitive but the sole use of these instruments for heavy metal detection is extremely expensive, needs a skillful person to operate and is not amenable to near-real-time analysis. The best scenario for routine biomonitoring of heavy metals is the marriage between instrument- and bioassays. Currently, the USEPA has recognized whole cell-based bioassays such as as PolytoxTM and Microtox® for the detection of heavy metals. Unfortunately these cell-based assays cannot be used as real-time or near real-time assays in the field as they require bulky incubators. Near-real-time monitoring of heavy metals giving results in less than one hour is very useful in environmental CSI (Criminal Scene Investigation) or ECSI where temporal and spatial concentrations of heavy metals in running waters are a challenge to environmentalists to pinpoint heavy metals POS (point of source) for legal purposes. Enzyme-based inhibitive assays are simple, rapid and fast and could be developed for near real-time assays. We have developed an inhibitive assay system –Xenoassay® based on proteases for the assay of heavy metals. The system could detect the heavy metals mercury, cadmium, lead, copper, zinc and silver at the sub parts per million level. Field trial near-real-time assay capability shows promising results

Adhesion Characterization of Palm Oil Mill Sludge Modified Asphalt Binder

The adhesion of mineral aggregates to asphalt binder is an essential point that attributes to the quality and performance of the asphalt mixture. Moreover, the considerable problem to the asphalt pavement could come from the lack of bonding between the materials. Generally, adhesion of mineral aggregates depends on the source or type of aggregate and asphalt binder. This study investigated the adherence coverage of palm oil mill sludge (POMS) modified binder with granite aggregate. Base asphalt binder of penetration grade 60/70 was blended with 1%,2%,3%,4% and 5% of POMS to produce the modified asphalt binders, respectively. Consequently, POMS modified binders were mixed with the granite aggregate to produce loose mix samples. In this current study, boiling test procedure was used to reduce the adhesive bonding of the loose mix sample. Then, Image J software was used to evaluate the stripping area of the samples. The results from image analysis revealed that different stripping areas due to different amounts of POMS incorporated in the modified asphalt binder. Up to 4% POMS modified asphalt showed an acceptable resistance toward moisture compared to un-modified asphalt. Image J helped to produce a clear stripping result compared to visual observation. In conclusion, POMS could be used as an asphalt modifier with satisfactory adhesion properties

Guidelines for Process Safety Hazard Assessment Based on Process Information

In any new chemical process development and design, process safety is a critical aspect to be considered besides economic and technical feasibility of the manufacture of the product. A lack of proper hazard assessment during the design phase may later result in accidents with disastrous consequences to workers, the public as well as the environment. Many methods have been introduced to qualitatively and quantitatively assess the safety level of processes. Despite the availability of a large amount of methods, a systematic framework that details guidelines for hazard identification, risk assessment, safety measure design, and safe critical decision-making is still missing. To address this issue, the main objective of this study was to propose a systematic framework that outlines comprehensive guidelines for assessing the safety performance of processes based on information from the piping and instrumentation diagram (P&ID). Apart from proposing the framework, appropriate strategies for minimizing safety hazards and risks are also recommended. In addition, the user is assisted in selecting the most appropriate assessment method according to his or her needs and the scope and constraints of the assessment. A case study is presented to illustrate the application of the proposed framework

The effect of mdea/amp and span-80 in water-in-oil (w/o) emulsion for carbon dioxide absorption

Emulsion liquid membrane (ELM) has been widely studied as an alternative method for amine absorption technology in the removal of acid gases such as carbon dioxide (CO2) and hydrogen sulphide (H2S). However, searching for stable ELM formulation with an enhanced CO2absorption remains as challenge. Therefore, in this study, the aqueous solution containing a mixture of methyl diethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) in sodium hydroxide (NaOH) solution was introduced as a dispersed phase, kerosene as continuous phase and Span-80 acts as a surfactant for the formation of water-in-oil (W/O) emulsion. In this study, the dispersed phase consists of 8% v/v MDEA and 4% v/v AMP and the continuous phase which contains 6% v/v Span-80 produced a stable emulsion and exhibited 65.2% of CO2removal. This study indicates that the introduction of blended amine able to produce stable emulsion with an enhanced CO2remova

Outcomes of cardiopulmonary resuscitation performed in Emergency Department, Hospital Universiti Sains Malaysia.

Despite the progresses made in the science of cardiopulmonary resuscitation, there is lack of published works on this area in the Malaysian context. This survey was done to look at the outcomes of all cardiopulmonary resuscitation performed in Emergency Department (ED), Hospital Universiti Sains Malaysia (HUSM). This is a one year cross-sectional study from March 2005-March 2006. All adult cardiac arrest cases with CPR performed in ED, HUSM were included in the survey. The end points are return of spontaneous circulation (ROSC) and survival to ward admission. Out of the total 63 cases of cardiac arrest with CPR performed, only 19 cases (30.2%) had ROSC after CPR performed on them. Eventually only six patients (9.5%) had survival to ward admission. Patients with shockable intial arrest rhythm has a significantly higher chance to achieve ROSC (60.0%) compared to non-shockable rhythms (24.5%) (p = 0.025). However, there was no different in survival to ward admission between shockable and non shockable rhythms groups. The survival after cardiac arrest is still dismally poor. Perhaps we should be more selective in initiating CPR especially for out of hospital cardiac arrest

Effects of titanate coupling agent on engineering properties of asphalt binders and mixtures incorporating LLDPE-CaCO3 pellet

This study was initiated to evaluate the performance of asphalt binders and mixtures incorporating linear low-density polyethylene- calcium carbonate (LLDPE-CaCO3) pellet, either with or without titanate coupling agent. The detailed manufacturing process of modifier pellets was displayed. The coupling agent was used to enhance the cross-linking between materials by means of winding up covalent bonds or molecule chains, thus improving the performance of composites. In the preparation of modified bitumen, the preheated asphalt binder was mixed with the modifiers using a high shear mixer at 5000 rpm rotational speed for 45 min. Experimental works were conducted to evaluate the performance of asphalt binders in terms of volatile loss, viscosity, rutting potential, and low temperature cracking. Meanwhile, the asphalt mixtures were tested using the flow number test and tensile strength ratio (TSR) test. The addition of LLDPE-CaCO3 modifiers and coupling agent does not significantly affect the volatile loss of modified asphalt binders. The addition of modifiers and coupling agent has significantly improved the resistance to permanent deformation of asphalt binders. Even though, the addition of LLDPE-CaCO3 modifier and coupling agent remarkably increased the mixture stiffness that contributed to lower rutting potential, the resistance to low temperature cracking of asphalt binder was not adversely affected. The combination of 1% coupling agent with 3% PECC is optimum dosage for asphalt binder to have satisfactory performance in resistance to moisture damage and rutting