Refined bleached and deodorized palm oil (RBDPO) was crystallized from the melt in a thermally controlled water bath at 14 and 22°C for 90 min. Slurries were withdrawn after 5, 15, 30, 60 and 90 min of crystallization for crystal morphology studies. Crystallization was also performed in a similar manner using a Labmax reactor connected to a FBRM detector to obtain the information on crystal count and size distribution during crystallization. Based on the shape of the crystals viewed under the microscope, all crystals appeared as needle shaped spherulitic β´- form at both crystallization temperatures studied. Crystals were slightly larger with increase in crystallization time and at higher crystallization temperature (22°C). Crystals size range between 4.34 to 22.29µm. FBRM recorded high count of crystals with increased in crystallization time and at lower temperature (14°C).
Ultrasound-assisted extraction (UAE) was applied for the extraction of bioactive valuable compounds from winter melon (Benincasa hispida) seeds. Effects of amplitude (25-75%), temperature (40-60°C) and sonication time (20-60 min) on crude extraction yield (CEY) and radical scavenging activities (RSA, % inhibition of DPPH˙ and ABTS˙+ free radicals) of extracts were determined using complete randomised design (CRD). The results showed that the CEY and RSA of extracts significantly affected by independent variables. The maximum value of CEY (97.14±0.36 mgg-1), scavenging of DPPH˙ radicals (32.12 ± 0.38%) and scavenging of ABTS˙+ radicals (40.52±0.73%) were obtained at the combined treatment conditions of 75%, 55°C and 40 min. The UAE results obtained were compared with those achieved by using conventional Soxhlet extraction (CSE) method. It was found UAE allowed extraction at lower temperature and the extracts obtained posses higher quality compare with CSE. UAE is a promising environment friendly technique for the extraction of bioactive compounds from winter melon (Benincasa hispida) seeds.
Mitigating and adapting to the impacts of climate change at regional level require downscaled projection of future climate states. This paper examined the possible changes of future climate extremes over Malaysia based on the IPCC SRES A1B emission scenario. The projected changes at 17 stations were produced by bias correcting the UKMO PRECIS downscaling simulation output. The simulation expected higher probability of rainfall extreme occurrences over the west coast of Peninsular Malaysia during the autumn transitional monsoon period. In addition, possible early monsoon rainfall was projected for certain stations located over East Malaysia. The simulation also projected larger increase of warm temperature extremes but smaller decrease of cold extremes, suggesting asymmetric expansion of the temperature distribution. The impact of the elevated green house gases (GHG) is higher in the night time temperature extremes as compared to the day time temperature extremes. The larger increment of warm night frequencies as compared to the warm day suggests smaller diurnal temperature ranges under the influence of higher greenhouse gases. Stations located in East Malaysia were projected to experience the largest increase of warm night occurrence.
Gene reassortment has proved useful in improving yields of influenza A antigens of egg-based inactivated vaccines, but similar approaches have been difficult with influenza B antigens. Current regulations for influenza vaccine seed viruses limit the number of egg passages and as a result resultant yields from influenza B vaccine seed viruses are frequently inconsistent. Therefore, reliable approaches to enhance yields of influenza B vaccine seed viruses are required for efficient vaccine manufacture. In the present study three stable cold-adapted (ca) mutants, caF, caM and caB derived from seasonal epidemic strains, B/Florida/4/2006, B/Malaysia/2506/2004 and B/Brisbane/60/2008 were prepared, which produced high hemagglutinin antigen yields and also increased viral yields of reassortants possessing the desired 6:2 gene constellation. The results demonstrate that consistent improvements in yields of influenza B viruses can be obtained by cold adaptation following extended passage. Taken together, the three ca viruses were shown to have potential as donor viruses for the preparation of high-yielding influenza B vaccine viruses by reassortment.
The structure of a novel psychrophilic β-mannanase enzyme from Glaciozyma antarctica PI12 yeast has been modelled and analysed in detail. To our knowledge, this is the first attempt to model a psychrophilic β-mannanase from yeast. To this end, a 3D structure of the enzyme was first predicted using a threading method because of the low sequence identity (<30%) using MODELLER9v12 and simulated using GROMACS at varying low temperatures for structure refinement. Comparisons with mesophilic and thermophilic mannanases revealed that the psychrophilic mannanase contains longer loops and shorter helices, increases in the number of aromatic and hydrophobic residues, reductions in the number of hydrogen bonds and salt bridges and numerous amino acid substitutions on the surface that increased the flexibility and its efficiency for catalytic reactions at low temperatures.
The gene encoding a cold-adapted, organic solvent stable lipase from a local soil-isolate, mesophilic Staphylococcus epidermidis AT2 was expressed in a prokaryotic system. A two-step purification of AT2 lipase was achieved using butyl sepharose and DEAE sepharose column chromatography. The final recovery and purification fold were 47.09 % and 3.45, respectively. The molecular mass of the purified lipase was estimated to be 43 kDa. AT2 lipase was found to be optimally active at pH 8 and stable at pH 6-9. Interestingly, this enzyme demonstrated remarkable stability at cold temperature (<30 °C) and exhibited optimal activity at a temperature of 25 °C. A significant enhancement of the lipolytic activity was observed in the presence of Ca(2+), Tween 60 and Tween 80. Phenylmethylsulfonylfluoride, a well known serine inhibitor did not cause complete inhibition of the enzymatic activity. AT2 lipase exhibited excellent preferences towards long chain triglycerides and natural oils. The lipolytic activity was stimulated by dimethylsulfoxide and diethyl ether, while more than 50 % of its activity was retained in methanol, ethanol, acetone, toluene, and n-hexane. Taken together, AT2 lipase revealed highly attractive biochemical properties especially because of its stability at low temperature and in organic solvents.
Terminal moieties of most proteins are long known to be disordered and flexible. To unravel the functional role of these regions on the structural stability and biochemical properties of AT2 lipase, four C-terminal end residues, (Ile-Thr-Arg-Lys) which formed a flexible, short tail-like random-coil segment were targeted for mutation. Swapping of the tail-like region had resulted in an improved crystallizability and anti-aggregation property along with a slight shift of the thermostability profile. The lipolytic activity of mutant (M386) retained by 43 % compared to its wild-type with 18 % of the remaining activity at 45 °C. In silico analysis conducted at 25 and 45 °C was found to be in accordance to the experimental findings in which the RMSD values of M386 were more stable throughout the total trajectory in comparison to its wild-type. Terminal moieties were also observed to exhibit large movement and flexibility as denoted by high RMSF values at both dynamics. Variation in organic solvent stability property was detected in M386 where the lipolytic activity was stimulated in the presence of 25 % (v/v) of DMSO, isopropanol, and diethyl ether. This may be worth due to changes in the surface charge residues at the mutation point which probably involve in protein-solvent interaction.
This paper reports the findings of the ongoing studies on cryopreservation of the snakehead, Channa striata embryos. The specific objective of this study was to collect data on the sensitivity of C. striata embryo hatching rate to low temperatures at two different developmental stages in the presence of four different cryoprotectants. Embryos at morula and heartbeat stages were selected and incubated in 1M dimethyl sulfoxide (Me2SO), 1M ethylene glycol (EG), 1M methanol (MeOH) and 0.1M sucrose solutions at different temperatures for a period of time. Embryos were kept at 24 °C (control), 15 °C, 4 °C and -2 °C for 5 min, 1h and 3h. Following these treatments, the embryos were then transferred into a 24 °C water bath until hatch to evaluate the hatching rate. The results showed that there was a significant decrease of hatching rate in both developmental stages following exposure to 4 °C and -2 °C at 1h and 3h exposure in each treatment. Heartbeat stage was more tolerant against chilling at -2 °C for 3h exposure in Me2SO followed by MeOH, sucrose and EG. Further studies will be conducted to find the best method to preserve embryos for long term storage.
BACKGROUND: The indiscriminate use of cough and cold medicines (CCMs) in children has become a public health concern. The study evaluates the prescription pattern of CCMs in primary care setting.
METHODS: Analysis of CCMs prescription data among children aged 12 years and below who had participated in the National Medical Care Survey (NMCS) 2010. Data was extracted from NMCS 2010, a cross-sectional survey on the primary healthcare service which was carried out from December 2009 to April 2010 in public and private primary care clinics in Malaysia.
RESULT: Of 21,868 encounters for NMCS 2010, 3574 (16.3%) were children 12 years old and below; 597 (17%) were from public clinics and 2977 (83%) were from private clinics. Of these 3574 encounters, 1748 (49%) children were prescribed with CCM with total of 2402 CCMs. On average, CCMs were prescribed at a rate of 1.3 CCMs per encounter in public clinics and 1.4 CCMs per encounter in private clinics. CCMs containing single ingredient constituted 77% of the prescriptions while 23% were of multiple ingredient preparations. There were 556 (23%) CCMs prescribed to children younger than 2 years. Majority (65%) were prescribed with one CCM per visit, 32% received two CCMs and 3% of the children received three or more CCMs per visit.
CONCLUSION: Prescription of CCMs to children is common. Prevalence of CCM prescriptions among young children is of concern, in view of concerns about the safety and adverse effects related to the use of CCMs in this age group. Firmer policies and greater effort is needed to monitor the prescriptions of CCMs to children.
We report the synthesis of amorphous carbon nanotubes/silver (αCNTs/Ag) nanohybrids via simple chemical route without additional reactant and surfactant at low temperature. Field emission scanning microscope (FESEM) and transmission electron microscope (TEM) confirmed formation of CNTs. X-ray diffraction (XRD) pattern confirmed the amorphous phase of carbon and the formation of Ag nanoparticles crystalline phase. Raman spectra revealed the amorphous nature of α CNTs. UV-visible spectroscopy showed enhancement of optical properties of α CNTs/Ag nanohybrids.
The main challenge in microfiltration (MF) is membrane fouling, which leads to a significant decline in permeate flux and a change in membrane selectivity over time. This work aims to elucidate the mechanisms of membrane fouling in cold MF of skim milk by identifying and quantifying the proteins and minerals involved in external and internal membrane fouling. Microfiltration was conducted using a 1.4-μm ceramic membrane, at a temperature of 6±1°C, cross-flow velocity of 6m/s, and transmembrane pressure of 159kPa, for 90min. Internal and external foulants were extracted from a ceramic membrane both after a brief contact between the membrane and skim milk, to evaluate instantaneous adsorption of foulants, and after MF. Four foulant streams were collected: weakly attached external foulants, weakly attached internal foulants, strongly attached external foulants, and strongly attached internal foulants. Liquid chromatography coupled with tandem mass spectrometry analysis showed that all major milk proteins were present in all foulant streams. Proteins did appear to be the major cause of membrane fouling. Proteomics analysis of the foulants indicated elevated levels of serum proteins as compared with milk in the foulant fractions collected from the adsorption study. Caseins were preferentially introduced into the fouling layer during MF, when transmembrane pressure was applied, as confirmed both by proteomics and mineral analyses. The knowledge generated in this study advances the understanding of fouling mechanisms in cold MF of skim milk and can be used to identify solutions for minimizing membrane fouling and increasing the efficiency of milk MF.
Poly(lactic acid) (PLA)-based nanocomposites filled with graphene nanoplatelets (xGnP) that contains epoxidized palm oil (EPO) as plasticizer were prepared by melt blending method. PLA was first plasticized by EPO to improve its flexibility and thereby overcome its problem of brittleness. Then, xGnP was incoporated into plasticized PLA to enhance its mechanical properties. Plasticized and nanofilled PLA nanocomposites (PLA/EPO/xGnP) showed improvement in the elongation at break by 3322% and 61% compared to pristine PLA and PLA/EPO, respectively. The use of EPO and xGnP increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA. The nanocomposites also resulted in an increase of up to 26.5% in the tensile strength compared with PLA/EPO blend. XRD pattern showed the presence of peak around 26.5° in PLA/EPO/xGnP nanocomposites which corresponds to characteristic peak of graphene nanoplatelets. Plasticized PLA reinforced with xGnP showed that increasing the xGnP content triggers a substantial increase in thermal stability. Crystallinity of the nanocomposites as well as cold crystallization and melting temperature did not show any significant changes upon addition of xGnP. However, there was a significant decrease of glass transition temperature up to 0.3wt% of xGnP incorporation. The TEM micrograph of PLA/EPO/xGnP shows that the xGnP was uniformly dispersed in the PLA matrix and no obvious aggregation was observed.
Channa striatus (“haruan”) fish destined for fillet preparation was subjected to two freezing treatments, freezing with distilled water (FW) or freezing directly without distilled water (DF). Fish that was freshly processed without freezing served as control (C). Fillet yield (%) was in the range 33.8% to 35.3% and the highest yield was recorded in FW samples. Whole Fillet Powder (WFP) was prepared from the fillets through low temperature vacuum oven drying (50°C) and its composition and physicochemical properties were assessed. There was no significant difference in moisture and protein contents of all samples (p > 0.05). All WFP were generally dark in colour with whiteness indices ranging from 55.23 - 63.98. The redness (a*) values were 4.33, 11.12, 8.83 whilst the yellowness (b*) were 19.31, 23.04, 21.20 for C, WFP-FW and WFP-DF respectively. WFPs were generally high in histidine, arginine, threonine and tyrosine when compared to egg whites and these (except histidine) and other amino acids (serine, glycine, methionine and phenylalanine) were significantly higher (p < 0.05) in WFP-FW compared to other samples. Overall, freezing treatments affected the composition and physicochemical properties of WFPs.
Solid oxide fuel cells (SOFC) are efficient and clean power generation devices. Lowtemperature
SOFC (LTSOFC) has been developed since high-temperature SOFC (HTSOFC) is not
feasible to be commercialized due to cost. Lowering the operation temperature reduces its substantial
performance resulting from cathode polarization resistance and overpotential of cathode. The
development of composite cathodes regarding mixed ionic-electronic conductor (MIEC) and ceriabased
materials for LTSOFC minimizes the problems significantly and leads to an increase in
electrocatalytic activity for the occurrence of oxygen reduction reaction (ORR). Lanthanum-based
materials such as lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-δ) have been discovered
recently, which offer great compatibility with ceria-based electrolyte to be applied as composite
cathode materials for LTSOFC. Cell performance at lower operating temperature can be maintained
and further improved by enhancing the ORR. This paper reviews recent development of various ceriabased
composite cathodes especially related to the ceria-carbonate composite electrolytes for
LTSOFC. The influence of the addition of metallic elements such as silver (Ag), platinum (Pt) and
palladium (Pd) towards the electrochemical properties and performance of LSCF composite cathodes
are also discussed.
In this work, 10 mol% yttrium-doped ceria powders, Ce0.9Y0.1O1.95, were synthesised using a new mechanical technique, mechanochemical reaction, in which both impact action and shearing forces were applied for efficient fine grinding, subsequently leading to higher homogeneity of the resultant powders. Ce0.9Y0.1O1.95 prepared using this new technique was systematically compared with a sample of the same prepared using conventional solid-state methodology. X-ray diffraction analysis showed all prepared samples were single phase with a cubic fluorite structure. Generally, Y2O3-doped CeO2 electrolytes prepared by mechanochemical reactions were stable at a lower temperature (1100 °C) compared with a sample of the same synthesised using the conventional solid-state method. Characterisations using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) showed no thermal changes and phase transitions, indicating all materials were thermally stable. The electrical properties of the samples investigated by AC impedance spectroscopy in the temperature range 200–800 ˚C are presented and discussed. Scanning electron microscopy (SEM) was used to study the morphology of the materials. Fine-grained powders with uniform grain-size distribution were obtained from the mechanochemical reaction.
In this study, various methods and applications of flat plate solar collectors are discussed and pictorial representations are presented. Low temperature applications of flat plate collectors are identified in solar cooking, solar water heating, space and air heating, industrial heating plants and in agricultural produce drying processes. Basic equations, as presented by many researchers in the performances of flat plate collectors, are also presented. The review discusses the analysis of losses from flat plate collectors towards obtaining the overall heat loss coefficient which indicate the performance of flat plate collectors.
Oceanographic cruises in Pahang water in October 2003 and April 2004, monsoon transition months, produce data on water characteristics. The temperature in both months showed higher values in nearshore compared to the offshore stations. The nearshore salinity in both months is lower than offshore stations. Comparatively, there were smaller differences in temperature and salinity in October than in April, with very little variation between nearshore and offshore stations. T-S diagram showed significant differences between October and April water characteristics. According to the water characteristic observations, the temperature and salinity in October was lower than in April, while dissolved oxygen was higher than in April. The lower temperature and salinity taken during the sampling time in October suggested that during this time, the study area already received the influences of strong winds due to upcoming monsoon. The warmer and saltier water obtained in April showed that during this time, the study area was influenced by southwest monsoon. Winds related to rainfall were observed to have impact to the dynamics of water characteristics during both months.
This study investigates the southwest monsoon circulation and temperature along the east coast of Peninsular Malaysia by using the Regional Ocean Modeling System at 9 km resolution. The simulated circulation shows strong northward flowing western boundary currents along the east coast of Peninsular Malaysia with maximum speed of approximately of 0.6-0.7 ms-1. The western boundary current, that extends to a depth of about 35 m, continues flowing northward up to approximately 7oN where it changes direction eastward. The circulation along the east coast of Peninsular Malaysia is also characterized by two anti-cyclonic eddies. Furthermore, an elongated of cooler sea surface temperature that stretches along the coast was also simulated. The existence of this cool SST pattern is associated with coastal upwelling process due to localized lifting of isotherms near the coast as a response to the southerly-southwesterly wind stress along the coast during the southwest monsoon.
Here, we present a novel psychrophilic β-glucanase from Glaciozyma antarctica PI12 yeast that has been structurally modeled and analyzed in detail. To our knowledge, this is the first attempt to model a psychrophilic laminarinase from yeast. Because of the low sequence identity (<40%), a threading method was applied to predict a 3D structure of the enzyme using the MODELLER9v12 program. The results of a comparative study using other mesophilic, thermophilic, and hyperthermophilic laminarinases indicated several amino acid substitutions on the surface of psychrophilic laminarinase that totally increased the flexibility of its structure for efficient catalytic reactions at low temperatures. Whereas several structural factors in the overall structure can explain the weak thermal stability, this research suggests that the psychrophilic adaptation and catalytic activity at low temperatures were achieved through existence of longer loops and shorter or broken helices and strands, an increase in the number of aromatic and hydrophobic residues, a reduction in the number of hydrogen bonds and salt bridges, a higher total solvent accessible surface area, and an increase in the exposure of the hydrophobic side chains to the solvent. The results of comparative molecular dynamics simulation and principal component analysis confirmed the above strategies adopted by psychrophilic laminarinase to increase its catalytic efficiency and structural flexibility to be active at cold temperature.
Psychrophilic microorganisms are cold-adapted with distinct properties from other thermal classes thriving in cold conditions in large areas of the earth's cold environment. Maintenance of functional membranes, evolving cold-adapted enzymes and synthesizing a range of structural features are basic adaptive strategies of psychrophiles. Among the cold-evolved enzymes are the cold-active lipases, a group of microbial lipases with inherent stability-activity-flexibility property that have engaged the interest of researchers over the years. Current knowledge regarding these cold-evolved enzymes in psychrophilic bacteria proves a display of high catalytic efficiency with low thermal stability, which is a differentiating feature with that of their mesophilic and thermophilic counterparts. Improvement strategies of their adaptive structural features have significantly benefited the enzyme industry. Based on their homogeneity and purity, molecular characterizations of these enzymes have been successful and their properties make them unique biocatalysts for various industrial and biotechnological applications. Although, strong association of lipopolysaccharides from Antarctic microorganisms with lipid hydrolases pose a challenge in their purification, heterologous expression of the cold-adapted lipases with affinity tags simplifies purification with higher yield. The review discusses these cold-evolved lipases from bacteria and their peculiar properties, in addition to their potential biotechnological and industrial applications.