This preliminary study aimed to isolate and identify microbes that inhabit the coelomic fluid of two local species of sea cucumbers collected from Malaysian waters - a ‘gamat’ species i.e. Stichopus chloronotus Brandt, 1835 and the most abundant ‘timun laut’ species in Malaysia i.e. Holothuria (Mertensiothuria) leucospilota (Brandt 1835). Phylogenetic analyses of partial 16S rRNA mtDNA gene sequences suggested the presence of at least eight microbial genera i.e. five bacterial genera - Bacillus, Exiguobacterium, Pseudomonas, Stenotrophomonas and Vibrio - isolated from the coelomic fluid of H. leucospilota and three genera of gram-positive bacteria from the Micrococcaceae family - Kytococcus, Micrococcus and either Kocuria or Rothia - isolated from the coelomic fluid of S. chloronotus. We speculate that less diverse microbial population in S. chloronotus as compared to H. leucospilota could be due to a number of environmental factors e.g. penetration of light surrounding the habitats of both species, the feeding behaviour of H. leucospilota and the higher level of antimicrobial properties of coelomic fluid in S. chloronotus. In terms of antimicrobial-resistance capability test, an isolate from genus Pseudomonas that is suspected to be P. alcaligenes exhibited high resistance towards streptomycin. Another isolate from genus Stenotrophomonas that was suspected to be S. maltophilia showed moderate resistance towards streptomycin and lower resistance towards kanamycin. Both isolates were from the coelomic fluid of H. leucospilota. Tetracycline inhibited the growth of all bacterial isolates tested. Further studies with more specimens of S. choronotus and H. leucospilota from broader geographical locations and the use of complete mtDNA genes along with morphological approaches for species identification may facilitate to provide better insights into the microbial population in the coelomic fluid of both local sea cucumber species.
Analysis of relationship between sea surface temperature (SST) and Chlorophyll-a (chl-a) improves our understanding on the variability and productivity of the marine environment, which is important for exploring fishery resources. Monthly level 3 and daily level 1 images of Moderate Resolution Imaging Spectroradiometer Satellite (MODIS) derived SST and chl-a from July 2002 to June 2011 around the archipelagic waters of Spermonde Indonesia were used to investigate the relationship between SST and chl-a and to forecast the potential fishing ground of Rastrelliger kanagurta. The results indicated that there was positive correlation between SST and chl-a (R=0.3, p<0.05). Positive correlation was also found between SST and chl-a with the catch of R. kanagurta (R=0.7, p<0.05). The potential fishing grounds of R. kanagurta were found located along the coast (at accuracy of 76.9%). This study indicated that, with the integration of remote sensing technology, statistical modeling and geographic information systems (GIS) technique were able to determine the relationship between SST and chl-a and also able to forecast aggregation of R. kanagurta. This may contribute in decision making and reducing search hunting time and cost in fishing activities.
One of the concerns of the air pollution studies is to compute the concentrations of one or more pollutants’ species in space and time in relation to the independent variables, for instance emissions into the atmosphere, meteorological factors and parameters. One of the most significant statistical disciplines developed for the applied sciences and many other disciplines for the last few decades is the extreme value theory (EVT). This study assesses the use of extreme value distributions of the two-parameter Gumbel, two and three-parameter Weibull, Generalized Extreme Value (GEV) and two and three-parameter Generalized Pareto Distribution (GPD) on the maximum concentration of daily PM10 data recorded in the year 2010 - 2012 in Pasir Gudang, Johor; Bukit Rambai, Melaka; and Nilai, Negeri Sembilan. Parameters for all distributions are estimated using the Method of Moments (MOM) and Maximum Likelihood Estimator (MLE). Six performance indicators namely; the accuracy measures which include predictive accuracy (PA), coefficient of determination (R2), Index of Agreement (IA) and error measures that consist of Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Normalized Absolute Error (NAE) are used to find the goodness-of-fit of the distribution. The best distribution is selected based on the highest accuracy measures and the smallest error measures. The results showed that the GEV is the best fit for daily maximum concentration for PM10 for all monitoring stations. The analysis also demonstrates that the estimated numbers of days in which the concentration of PM10 exceeded the Malaysian Ambient Air Quality Guidelines (MAAQG) of 150 mg/m3 are between ½ and 1½ days.
Minyak pati Goniothalamus ridleyi daripada sampel segar dan kering bahagian kulit batang, kayu, buah, akar dan
daun telah diekstrak menggunakan hidro penyulingan. Minyak pati tersebut telah dianalisis menggunakan kromatografi
gas (KG) kapilari dan kromatografi gas-spektrometer jisim (KG-SJ). Komposisi sebatian kimia dalam minyak pati telah
dikenal pasti secara perbandingan data spektrum jisim sampel dengan spektrum jisim yang ada dalam rujukan Wiley,
perbandingan pengiraan indeks penahanan dengan nilai kepustakaan dan ko-kromatografi bagi sesetengah sebatian
dengan sebatian autentik pada turus kapilari DB-5. Sebanyak 50 sebatian telah dikenal pasti dan mewakili 89.5% minyak
pati kulit batang segar G. ridleyi. Minyak pati daripada kulit batang segar kaya dengan sebatian linalool (15.2%) dan
sitronellal (10.9%). Sejumlah 47 sebatian telah dikenal pasti dan mewakili 90.1% jumlah minyak pati kayu segar yang
menunjukkan kehadiran sebatian utama β-eudesmol (27.1%) dan γ-eudesmol (20.8%). Sementara itu, minyak pati
daripada bahagian buah menunjukkan kehadiran 49 sebatian serta mewakili 89.8% jumlah minyak pati. Sebatian utama
dalam minyak pati buah adalah β-kubebena (20.7%) dan elemol (20.2%). Sebatian utama dalam sampel segar adalah
sama dengan sebatian utama dalam sampel kering, kecuali bahagian sampel kering didapati kaya dengan sebatiansebatian
seperti β-karyofilena, limonena, β-selinena, viridifloral, α-kopaena dan cyperena.
A study was conducted to determine the effects of a plant growth regulator (paclobutrazol, PBZ) and commercial
fertilizer (Krista-K Plus) as a source of potassium nitrate (KNO3
) on the growth of Xanthostemon chrysantus. It was
also attempted to investigate the anatomical changes in the leaf and stem after the treatment. Nine treatments, i.e.
control (no PBZ and Krista-K Plus application), 0 PBZ gL-1 + 100 g Krista-K Plus, 0 PBZ gL-1 + 200 g Krista-K Plus,
0.125 PBZ gL-1 + 0 g Krista-K Plus, 0.125 PBZ gL-1 + 100 g Krista-K Plus, 0.125 PBZ gL-1 + 200 g Krista-K Plus, 0.25
PBZ gL-1 + 0 g Krista-K Plus, 0.25 PBZ gL-1 + 100 g Krista-K Plus and 0.25 PBZ gL-1 + 200 g Krista-K Plus, were
tested. PBZ was soil drenched at the commencement of the study while Krista-K Plus was applied at three-month
intervals. Plant growth performances such as tree height, diameter at breast height, canopy diameter and leaf area
were recorded monthly throughout the study period. Stem and leaf samples were collected before the application
of treatments and after six months of treatments for anatomical observation by using electron microscope. Plant
height, diameter at breast height, crown diameter and leaf area were significantly reduced with the application of
PBZ. Palisade parenchyma thickness was increased by 33.83% with 0.25 PBZ gL-1 + 200 g Krista-K Plus, while only
2.44% increment recorded in the control tree. Xylem thickness in the stem was reduced by 21.81% after treated with
the highest dosage of PBZ, while the control tree only had 1.78% increment. Spongy parenchyma thickness in the leaf
was unaffected. However, palisade parenchyma was found the thickest after combined treatment with 0.25 PBZ gL-1
+ 200 g Krista-K Plus. Micrograph images of the cross-section of leaf lamina and stem showed that the cells were
tightly arranged in response to the application of PBZ.
Phytochemical studies were conducted on the stem bark, stem, root and fruit of Goniothalamus ridleyi (Annonaceae)
collected at Post Brooke, Gua Musang, Kelantan, Malaysia. Extraction using organic solvent followed by extensive
purification using standard procedure afforded an epoxystyryllactone, 5-acetoxyisogoniothalamin oxide (1) from the
stem bark and fruit; a styryllactone, 5-acetoxygoniothalamin (2) and a styrylpyrone, dehydrogoniothalamin (3) from
the stem and root; a styryllactone, 5-hydroxygoniothalamin (4) from the root and styrylpyrone as well as goniothalamin
(5) from the fruit. These compounds were characterized using spectroscopic techniques.
Introductions: Recurrent oral ulcers primarily effect mucosal surfaces and are among the most common chronic inflammatory diseases. Numerous studies to find the aetiopathogenesis have been conducted however the cause still remains unclear. Saliva is of utmostimportance for oral health maintenance. In current study, saliva was used as a diagnostic tool for comparison of salivary flow rate and pH in patients suffering from recurrent oral ulcers and control group. Materials and Methods: Saliva samples taken from 20 recurrent aphthous ulcer patients and 20 control (healthy) patients using a convient sampling method. Drooling method was used to collect unstimulated whole saliva sample. Pre-weighted specimen bottles were used and then weighed after sample collection on a graduated scale where as chair-side pH meter was used to determine the salivary pH. Independent t-test and Pearson’s correlation were performed. A p-value of less than 0.05 was considered statistically significance. Results: Positive correlation was found between the flow rate and pH in recurrent oral ulcer patients. Patients with recurrent oral ulcers had higher flow rate and pH compared to the control group. These effects were exaggerated in female patients with ulcers. Conclusions: Disturbances in salivary flow rate and pH were not significantly associated with recurrent oral ulcers.
The biosynthesis of nanoparticles has been proposed as a cost-effective and environmental friendly alternative to chemical and physical methods. The present study was aimed to characterise Catharanthus roseus (C. roseus)-silver nanoparticles (AgNPs) using a standardised C. roseus aqueous extract. Methods: The standardisation was performed by using Liquid Chromatography/Time-of-Flight ion trap Mass Spectrometry. An optimised C. roseus-AgNPs have been previously synthesised. Further characterisation of C. roseus-AgNPs was evaluated by zeta potential analysis and fourier transform infrared spectroscopy (FTIR). Results: The chromatography analysis has revealed presence of thirteen possible indole alkaloids in C. roseus extract which were lochrovicine, lochnerine, vinleurosine, vindolinine, tabersonine, catharanthine, serpentine, catharosine, vincristine, catharine, ajmalicine, vinleurosine, and vindolicine. Zeta potential analysis exhibited the value at -16.6 mV. FTIR spectrum of C. roseus aqueous extract showed the absorption band at 3210.83 cm-1 (C-H stretch), 2934.11 (C-H bond), 1578.15 (N=O stretch), 1388.76 and 1314.89 (N=O bend), 1119.29 (C-O bond) and 729.94 (C-Cl bond). In comparison, FTIR spectrum of C. roseus-AgNP s showed the absorption band at 2925.01 and 2924.97 (C-H bond), 1622.93 (C-C=C symmetric stretch), 1383.19 and 1384.13 (N-O bend), 1037.92/1038.76/1238.3/1117.2 (C-O bond), 3169.4 (O-H bond), 774.59 and 691.53 (C-Cl bond). Conclusion: The present findings have shown that the C. roseus aqueous extract contains alkaloids that may responsible as reducing and stabilising agents in the synthesis of AgNPs.
The changes on the vegetables oil trading environment might change the foundation of palm oil pricing and induce a structural change to the price model. Failing to take it account the structural change in a data series might lead to misspecification of the actual model. This study, however, showed that structural change was not present in the monthly, January 1983 to July 1995, palm oil price, but it was present on the unconditional variance. The underlying model of this series was ARIMA (3, 1, 0) with ARCH (1). The critical change of the unconditional variance took place in April 1989.
Perubahan dalam suasana perdagangan minyak sayuran boleh mengubah asas harga minyak kelapa sawit. Seterusnya ia merangsang perubahan dalam struktur model harga minyak tersebut. Kegagalan untuk mengambil kira perubahan struktur dalam siri data menjadikan model itu tidak menepati spesifikasi daripada model sebenar. Kajian ini mendapati bahawa perubahan struktur tidak berlaku bagi data harga minyak sawit dari Januari 1983 hingga Julai 1995. Tetapi perubahan berlaku pada varians tidak bersyaratnya. Model asas bagi siri ini adalah ARIMA (3,1,0) dengan ARCH(1). Didapati juga bahawa perubahan yang kritikal bagi varians tidak bersyarat berlaku pada bulan April 1989.
This paper describes the effect of pro-degradant additives (PDA) on photo-oxidative aging of polypropylene (PP) films after being time accelerated in UV-weathering chamber. Thin films (0.12 mm) containing these additives were prepared by sheeting process. The effect of UV on PP films in the presence of these additives was investigated. Changes in the PP films appearance, tensile properties and carbonyl index (CI) were used to investigate the degradation behavior. The films became completely pulverised after 100 h of photo-oxidative treatment and could not be tested further. Films containing PDA showed rapid loss in tensile properties within 100 h of photo-oxidative aging. In addition, the CI results of photo-oxidative films increased with increasing PDA amount within the time interval of aging and the activity was due to the mechanism reaction of PP with PDA particles. During the aging process the material becomes denser due to tighter packing and incorporation of oxygen into the amorphous regions of the polymer. The results indicated that the presence of PDA contributed to the photo degradation and the activity was very much influenced by the amount PDA.
Working environmental conditions in automotive industry are very challenging to the human workers. Meanwhile, products quality is very much dependent on workers’ health, safety and comfort in their working environment. Environmental factors, such as temperature, illuminance and humidity levels have significant effect on workers’ performance at the production line. In this experiment, temperature, humidity, illuminance levels and productivity rate were observed in a control room. An automotive manufacturing firm production line was chosen to be simulated in the control room to observe the temperature, relative humidity, illuminance and worker’s productivity rate. The experimental data collected was analyzed using Response Surface Method (RSM). RSM is an analysis technique, which combined statistical systems and mathematical methods. It can be applied for research and development, reform and optimize a process, which involves several design variables. As a result, the combined effect of temperature, illuminance and humidity toward productivity can be clearly seen. Optimum environmental factor cannot be predicted using first order RSM analysis because it gives low reliability for obtaining the optimum level. Thus, a second order RSM analysis was generated for obtaining the optimum level of environmental factors.
Suatu kajian telah dijalankan untuk menentukan potensi makroinvertebrat bentik sebagai penunjuk biologi di hulu Sungai
Ikan, Terengganu. Sebanyak lima stesen pensampelan telah dipilih untuk pensampelan makroinvertebrat bentik dan
analisis kualiti air. Pensampelan makroinvertebrat bentik telah dilakukan menggunakan jaring Surber dan analisis
kualiti air dilakukan menurut kaedah APHA. Piawaian Kualiti Air Kebangsaan (NWQS) telah digunakan untuk menilai
parameter kualiti air di kawasan kajian dan hasil menunjukkan Sungai Ikan berada dalam keadaan baik iaitu kelas I
hingga II. Ujian ANOVA satu hala menunjukkan bahawa kesemua parameter air yang diuji adalah seragam di sepanjang
kawasan kajian (p>0.05, α=0.05). Sebanyak 2 filum, 3 kelas, 8 order, 39 famili dan 1353 individu telah dikenal pasti dan
didominasi oleh famili Baetidae, Siphlonuridae, Simuliidae, Chironomidae dan Elmidae. Famili dominan didapati hadir
pada hampir kesemua stesen pensampelan. Memandangkan kualiti air adalah baik dan tidak berubah sepanjang kawasan
kajian, ujian CCA dilakukan untuk memperlihatkan faktor persekitaran lain yang mempengaruhi sebaran makroinvertebrat
terutamanya famili dominan. Hasil ujian CCA menunjukkan pengaruh persekitaran yang khusus terhadap famili tertentu
dan mempunyai pengaruh yang kuat terhadap sebaran makroinvertebrat bentik. Ujian korelasi menunjukkan batuan
besar mempunyai pengaruh besar terhadap sebaran famili Baetidae, Siphlonuridae dan sub-famili Orthocladiinae,
manakala komposisi pasir pula mempunyai pengaruh terhadap famili Elmidae. Hasil kajian ini menunjukkan dalam
ekosistem yang bersih, faktor persekitaran habitat adalah kritikal untuk diambil kira dalam menentukan taksa tertentu
yang sesuai digunakan sebagai penunjuk biologi ekosistem sungai rekreasi.
Epoxidized natural rubber (ENR-50) has been used as a compatibilizer for natural rubber-recycled acrylonitrile-butadiene
rubber (NR/NBRr) blends, vulcanized by sulfur. NBR gloves have excellent resistance to punctures, tear and many types
of chemicals, while NR has good physical and mechanical properties. Incorporation of ENR-50 into the rubber blends
has improved processability, stiffness, resilience and excellent oil resistance. NR/NBRr blends were prepared by two-roll
mill with five different compositions with the ENR-50 content fixed at 10 phr. Cure characteristics, mechanical properties
and morphology (SEM) studies were performed to determine the compatibility of NR/NBRr blends in the presence of ENR-
50. The cure characteristics showed that NR/NBRr blends with the presence of ENR-50 have lower scorch time (ts2) and
cure time (t90) than NR/NBRr blends without ENR-50. However, the NR/NBRr blends with ENR-50 exhibited higher minimum
torque (ML
) and maximum torque (MH) which indicated difficult processability of the blends after compatibilization.
Incorporation of ENR-50 into NR/NBRr blends improved all the tensile properties (tensile strength, tensile modulus and
elongation at break) compared with NR/NBRr blends without ENR-50. The improvement in hardness upon compatibilization
is due to an increase in crosslink density. Scanning electron microscopy (SEM images) of the fracture surfaces indicates
that, with the addition of ENR-50 in NR/NBRr blends, better adhesion between NR and NBRr was obtained, thus improving
the compatibility of NR/NBRr blends.
The integration of human knowledge between the medical and health care sciences with revealed knowledge was established since the era of Al-Razi (Rhazes), Ibn Sina (Avicenna), Ibn Rushd (Averroes), AlZahrawi (Albucasis) and others. However, the glorious period of Islamic medicine gradually declined after the period of 'Abbasiyyah and 'Uthmaniyyah. At present, many scholars tend to separate the modern medicine and the revealed knowledge, resulting in the disconnection between these two fields. There is little to suggest the presence of reference collections that integrate the Qur’an and Hadith with medicine. This review aimed to fill that gap. Relevant Qur’anic verses and authentic Hadith of the Prophet Muhammad (peace be upon him; henceforth PBUH) in relation to a specific field in medicine i.e. the anatomy of human musculoskeletal system was extracted. The musculoskeletal system is unique in which it forms the ‘backbone’ of normal human posture. The system plays a vital role in maintaining human daily activities. From this review, it is noted that many Qur’anic verses and Hadith relate to the musculoskeletal system. A few examples include the number human joints and its relationship with the daily prayers (Salah), the daily charitable act recommended to all Muslim, the coccyx bone that is indestructible and shall be the source for human resurrection during the hereafter, and others. These examples necessitate for a more in-depth analysis to enlighten the revealed knowledge from the medical perspective.
CAD accounts for 25% of mortality in Malaysia public hospitals. CABG is one of treatment for patients with CAD, but requires RBC transfusion, which is associated with morbidity and mortality. This study was to evaluate the association between RBC transfusion and morbidity and mortality in CABG patients at the National Heart Centre, Malaysia (IJN). Methods: Retrospective cross-sectional study performed using data from 434 patients who underwent CABG in 2013 and 2014. Subjects had systematic random sampling every fifth subject of the patients in the sequence of dates of the year. Data related to the relationship between RBC transfusion with mortality and morbidity, and the predicting factors captured. Results: 64.3% of CABG patients (n = 279) received RBC transfusion perioperatively. Age, gender, BMI, and EF, were factors that contributed for RBC transfusion. RBC transfusion was a contributor to longer intensive care unit length of stay (ICULOS) and hospital length of stay (HLOS). Multiple logistic regression revealed, for every 1 year increase of age, there is 3.5% higher chance of transfusion. Whereas an increase of 1 kg/m2 of BMI and 1% of EF reduced the odds of RBC transfusion by 13.0% and 3.0% respectively. Conclusions: Age, gender, BMI, and EF determine the probability of needing RBC transfusion during CABG, and RBC transfusion will result in longer ICULOS, and HLOS. Probability of RBC transfusion will be higher in older patients and reduced in those with higher BMI and EF.
This study aims to identify the expression of emotions and how emotions are controlled by adolescents. The sample comprised three male and two female students who were from a secondary school located in Penang. Semi-structured interviews were conducted in this study. Transcribed contents of the interviews were analyzed. The main findings showed generally, adolescents like to have fun, seek to try something new, like to relax with friends, and they also follow their feelings. Female adolescents were found to be sensitive. Generally, adolescents indicated that they were more comforlable sharing problems with friends than with parents. Implications of findings area also discussed.
The determination technique for U (238U, 235U, 234U) and Th (232Th, 230Th, 228Th) isotopes using alpha spectrometry was developed. The developed technique involved digestion, dissolution, coprecipitation, solvent extraction and electrodeposition methods. The NBS River Sediment and Rocky Flats Soil Standard Reference Materials were analysed to determine the accuracy of the technique. A good accuracy and high percentage recovery of the carrier (70 - 90%) indicated that the developed technique was suitable for U and Th isotopes determination. The technique was used to determine the U and Th concentration in monazite, xenotime and zircon samples. The results showed that the U and Th total concentrations were in the range of 21.03 to 171.25 Bq/g and 27.48 to 242.87 Bq/g respectively.
Kaedah penguraian, pemelarutan, pemendakan bersama, ekstraksi pelarut dan pemendapan elektrik telah dikaji dan digunakan untuk mendapatkan suatu teknik yang terbaik dalam penentuan isotop uranium 234U, 235U & 238U) dan torium 228Th, 230Th & 232Th) menggunakan sistem spektrometri alfa. Kepekatan isotop U dan Th dalam bahan rujukan piawai River Sediment dan Rocky Flats Soil (NBS) telah dianalisis untuk menentukan kejituan teknik yang dibangunkan. Kajian ini mendapati kepekatan isotop yang diperolehi adalah menghampiri nilai teraku (sijil) dan peratus perolehan semula pembawa yang besar (70-90%). Ini menunjukkan teknik yang dibangunkan sesuai digunakan untuk penentuan isotop uranium dan torium. Seterusnya teknik yang dibangunkan telah digunakan untuk menentukan kandungan uranium dan torium dalam sampel monazit, xenotim dan zirkon tempatan. Kepekatan jumlah isotop uranium yang diperolehi didapati berada dalam julat 21.03 - 171.25 Bq/g manakala kepekatan jumlah isotop torium pula terletak antara 27.48 - 242.87 Bq/g.
In this research we introduce an analyzing procedure using the Kullback-Leibler information criteria (KLIC) as a statistical tool to evaluate and compare the predictive abilities of possibly misspecified density forecast models. The main advantage of this statistical tool is that we use the censored likelihood functions to compute the tail minimum of the KLIC, to compare the performance of a density forecast models in the tails. Use of KLIC is practically attractive as well as convenient, given its equivalent of the widely used LR test. We include an illustrative simulation to compare a set of distributions, including symmetric and asymmetric distribution, and a family of GARCH volatility models. Our results on simulated data show that the choice of the conditional distribution appears to be a more dominant factor in determining the adequacy and accuracy (quality) of density forecasts than the choice of volatility model.
The primary source of water on many small islands is the fragile freshwater lens that floats on saline water in its shallow aquifer. The management of such a limited groundwater resource on these islands is seriously constrained by the occurrence of seawater intrusion. Sipadan Island, the renowned and only oceanic island in Malaysia, had experienced in the over-extraction of its groundwater for more than ten years to cater for freshwater demand associated with tourism activities. This paper discusses the output of modelling of seawater intrusion into the island’s aquifer using SEAWAT-2000. The findings indicated that the island’s coastal aquifer has been encroached by seawater. The infiltration of isochlor (chloride concentration) of 2.5 and 45% of seawater and freshwater mixing ratios has moved 63.4 m and 12.7 m inland from the coastline, respectively. The upconing event at the pumping well, as simulated by the three-dimensional model, showed that 14.5% of seawater-freshwater mixing ratio took place below the bottom of each well. Intensive and unregulated exploitation of groundwater from such an unconfined aquifer of the island by pumping wells contributed to the upconing. In order to protect the fresh groundwater resources in the study area from seawater intrusion, adjustment of groundwater pumping rate is needed. This study showed that the model is useful in demonstrating the mechanism and movement of freshwater-seawater interface in the island, and thus provide a powerful management tool for such an aquifer.
Organomontmorillonites were synthesized by grafting cationic surfactants i.e quaternary ammonium compounds into the interlayer space and were characterized using XRD, FTIR and N2 adsorption/ desorption analysis. The organomontmorillonites were applied as catalyst for the esterification of glycerol (GL) with lauric acid (LA). The catalyst which had symmetrical onium salts (tetrabuthylammoniumbromide, TBAB) gave higher activity than that of unsymmetrical onium salts (cetyltrimethylammoniumbromide, CTAB). Over the TBAB-montmorillonite catalyst, glycerol monolaurate was obtained with a selectivity of about 80%, a lauric acid conversion of about 71% and a glycerol monolaurate yield of about 57%.