MyMedR

Displaying publications 21 - 40 of 47 in total

Abstract:

Sort:

Application of the threshold model for modelling and forecasting of exchange rate in selected ASEAN countries

Behrooz Gharleghi, Abu Hassan Shaari Md Nor, Tamat Sarmidi

Sains Malaysiana, 2014;43:1609-1622.

Linear time series models are not able to capture the behaviour of many financial time series, as in the cases of exchange rates and stock market data. Some phenomena, such as volatility and structural breaks in time series data, cannot be modelled implicitly using linear time series models. Therefore, nonlinear time series models are typically designed to accommodate for such nonlinear features. In the present study, a nonlinearity test and a structural change test are used to detect the nonlinearity and the break date in three ASEAN currencies, namely the Indonesian Rupiah (IDR), the Malaysian Ringgit (MYR) and the Thai Baht (THB). The study finds that the null hypothesis of linearity is rejected and evidence of structural breaks exist in the exchange rates series. Therefore, the decision to use the self-exciting threshold autoregressive (SETAR) model in the present study is justified. The results showed that the SETAR model, as a regime switching model, can explain abrupt changes in a time series. To evaluate the prediction performance of SETAR model, an Autoregressive Integrated Moving Average (ARIMA) model used as a benchmark. In order to increase the accuracy of prediction, both models are combined with an exponential generalised autoregressive conditional heteroscedasticity (EGARCH) model. The prediction results showed that the construct model of SETAR-EGARCH performs better than that of the ARIMA model and the combined ARIMA and EGARCH model. The results indicated that nonlinear models give better fitting than linear models.

Matched MeSH terms: Volatilization
Effectiveness of mixing poultry litter compost with rice husk biochar in mitigating ammonia volatilization and carbon dioxide emission

Alarefee HA, Ishak CF, Othman R, Karam DS

J Environ Manage, 2023 Mar 01;329:117051.
PMID: 36549060 DOI: 10.1016/j.jenvman.2022.117051

Nitrogen-rich materials such as poultry litter (PL) contributes to substantial N and C loss in the form of ammonia (NH3) and carbon dioxide (CO2) during composting. Biochar can act as a sorbent of ammonia (NH3) and CO2 emission released during co-composting. Thus, co-composting poultry litter with rice husk biochar as a bulking agent is a good technique to mitigate NH3 volatilization and CO2 emission. A study was conducted to evaluate the effects of composting the mixtures of poultry litter with rice husk biochar at different ratios on NH3 and CO2 emissions. Four mixtures of poultry litter and rice husk biochar at different rate were composted at 0:1, 0.5:1, 1.3:1 and 2.3:1 ratio of rice husk biochar (RHB): poultry litter (PL) on a dry weight basis to achieve a suitable C/N ratio of 15, 20, 25, and 30, respectively. The results show that composting poultry litter with rice husk biochar can accelerate the breakdown of organic matter, thereby shortening the thermophilic phase compared to composting using poultry litter alone. There was a significant reduction in the cumulative NH3 emissions, which accounted for 78.38%, 94.60%, and 97.30%, for each C/N ratio of 20, 25, and 30. The total nitrogen (TN) retained relative was 75.96%, 85.61%, 90.24%, and 87.89% for each C/N ratio of 15, 20, 25, and 30 at the completion of composting. Total carbon dioxide lost was 5.64%, 6.62%, 8.91%, and 14.54%, for each C/N ratio of 15, 20, 21, and 30. In addition, the total carbon (TC) retained were 66.60%, 72.56%, 77.39%, and 85.29% for 15, 20, 25, and 30 C/N ratios and shows significant difference as compared with the initial reading of TC of the compost mixtures. In conclusion, mixing and composting rice husk biochar in poultry litter with C/N ratio of 25 helps in reducing the NH3 volatilization and CO2 emissions, while reducing the overall operational costs of waste disposal by shortening the composting time alongside nitrogen conservation and carbon sequestration. In formulating the compost mixture with rice husk biochar, the contribution of C and N from the biochar can be neglected in the determination of C/N ratio to predict the rate of mineralization in the compost because biochar has characteristic of being quite inert and recalcitrant in nature.

Matched MeSH terms: Volatilization
Microencapsulation of Citrus Grandis Peel Oil Using Interfacial Precipitation Chemistry Technique for Repellent Application

Misni N, Mohamed Nor Z, Ahmad R

Iran J Pharm Res, 2019;18(1):198-209.
PMID: 31089355

Essential oil of Citrus family plant is known to have repellent effect against mosquito. Unfortunately, due to its high volatility effect, its repellency effect was compromised. The incorporation of essential oil in a microencapsulation formulation has been shown to help improve the stability and potency of the repellent. In this study, Citrus grandis peel oil (CGPO) was encapsulated by using the interfacial precipitation chemistry technique. The microencapsulated CGPO was then formulated into lotion form to produce topical repellent formulation. This study includes the characterization of microcapsules with regards to the morphology, size distribution, zeta potential, Fourier Transmission Infrared spectrophotometer (FTIR), and Thermogravity analysis (TGA). The effectiveness of the microencapsulated CGPO-lotion formulation against mosquitoes was evaluated in the laboratory setting. Results indicated that CGPO have been successfully encapsulated with 6.5 µm in diameter and zeta potential values, -47.9 mV. The FTIR analysis spectrum indicated the presence of interaction between the wall materials in microcapsules. The TGA analysis demonstrated that microencapsulation improved the thermal stability of CGPO. Repellency assay revealed that microencapsulated CGPO- based formulation possessed excellent effect compared with pure CGPO. In conclusion, CGPO was successfully encapsulated and the microencapsulation aid to improve the repellency effect of CGPO against mosquito bites.

Matched MeSH terms: Volatilization
Pyrolysis kinetics of raw and hydrothermally carbonized Karanj (Pongamia pinnata) fruit hulls via thermogravimetric analysis

Islam MA, Asif M, Hameed BH

Bioresour Technol, 2015 Mar;179:227-233.
PMID: 25545092 DOI: 10.1016/j.biortech.2014.11.115

The pyrolysis of karanj fruit hulls (KFH) and karanj fruit hull hydrothermal carbonization (KFH-HTC) hydrochar was thermogravimetrically investigated under a nitrogen environment at 5 °C/min, 10 °C/min, and 20 °C/min. The pyrolysis decomposition of KFH biomass was faster than that of KFH-HTC hydrochar because of the high volatility and fixed carbon of KFH biomass. Weight loss percentage was also affected by the heating rates. The kinetic data were evaluated with the Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa methods. The activation energy values obtained with these two methods were 61.06 and 68.53 kJ/mol for KFH biomass and 130.49 and 135.87 kJ/mol for KFH-HTC hydrochar, respectively. The analysis of kinetic process mechanisms was verified with the Coats-Redfern method. KFH-HTC hydrochar may play a potential role in transforming biomass to energy-rich feedstock for thermochemical applications because of its high heating value, high fixed carbon, and low ash and sulfur contents.

Matched MeSH terms: Volatilization/drug effects
Effect of HPMC concentration on β-cyclodextrin solubilization of norfloxacin

Loh GO, Tan YT, Peh KK

Carbohydr Polym, 2014 Jan 30;101:505-10.
PMID: 24299805 DOI: 10.1016/j.carbpol.2013.09.084

The effect of hydroxypropyl methylcellulose (HPMC) concentration on β-cyclodextrin (β-CD) solubilization of norfloxacin was examined. The solubility and dissolution of norfloxacin/β-CD and norfloxacin/β-CD/HPMC inclusion complexes were studied. The presence of β-CD increased significantly the solubility and dissolution of norfloxacin. The addition of HPMC until 5% (w/w) improved the solubilization of norfloxacin but further addition above 5% (w/w), decreased norfloxacin solubilization. Fourier transformed Infra-red (FTIR) showed that norfloxacin was successfully included into β-CD. Differential scanning calorimetry (DSC) showed that the norfloxacin endothermic peak shifted to a lower temperature with reduced intensity indicating the formation of inclusion complex. The addition of HPMC reduced further the intensity of norfloxacin endothermic peak. Most of the sharp and intense peaks of norfloxacin disappeared with the addition of HPMC. In conclusion, the concentration of hydrophilic polymer used to enhance β-CD solubilization of poorly soluble drugs is very critical.

Matched MeSH terms: Volatilization
Investigation on thermochemical behaviour of low rank Malaysian coal, oil palm biomass and their blends during pyrolysis via thermogravimetric analysis (TGA)

Idris SS, Abd Rahman N, Ismail K, Alias AB, Abd Rashid Z, Aris MJ

Bioresour Technol, 2010 Jun;101(12):4584-92.
PMID: 20153633 DOI: 10.1016/j.biortech.2010.01.059

This study aims to investigate the behaviour of Malaysian sub-bituminous coal (Mukah Balingian), oil palm biomass (empty fruit bunches (EFB), kernel shell (PKS) and mesocarp fibre (PMF)) and their respective blends during pyrolysis using thermogravimetric analysis (TGA). The coal/palm biomass blends were prepared at six different weight ratios and experiments were carried out under dynamic conditions using nitrogen as inert gas at various heating rates to ramp the temperature from 25 degrees C to 900 degrees C. The derivative thermogravimetric (DTG) results show that thermal decomposition of EFB, PMF and PKS exhibit one, two and three distinct evolution profiles, respectively. Apparently, the thermal profiles of the coal/oil palm biomass blends appear to correlate with the percentage of biomass added in the blends, thus, suggesting lack of interaction between the coal and palm biomass. First-order reaction model were used to determine the kinetics parameters for the pyrolysis of coal, palm biomass and their respective blends.

Matched MeSH terms: Volatilization
Persistence of fenvalerate in three Malaysian agricultural soils

Ismail BS, Maznah Z

Bull Environ Contam Toxicol, 2005 Oct;75(4):789-96.
PMID: 16400562
Matched MeSH terms: Volatilization
Combustion of chlorinated volatile organic compounds (VOCs) using bimetallic chromium-copper supported on modified H-ZSM-5 catalyst

Abdullah AZ, Bakar MZ, Bhatia S

J Hazard Mater, 2006 Feb 28;129(1-3):39-49.
PMID: 16310938

The paper reports on the performance of chromium or/and copper supported on H-ZSM-5(Si/Al = 240) modified with silicon tetrachloride (Cr1.5/SiCl4-Z, Cu1.5/SiCl4-Z and Cr1.0Cu0.5/SiCl4-Z) as catalysts in the combustion of chlorinated VOCs (Cl-VOCs). A reactor operated at a gas hourly space velocity (GHSV) of 32,000 h(-1), a temperature between 100 and 500 degrees C with 2500 ppm of dichloromethane (DCM), trichloromethane (TCM) and trichloroethylene (TCE) is used for activity studies. The deactivation study is conducted at a GHSV of 3800 h(-1), at 400 degrees C for up to 12 h with a feed concentration of 35,000 ppm. Treatment with silicon tetrachloride improves the chemical resistance of H-ZSM-5 against hydrogen chloride. TCM is more reactive compared to DCM but it produces more by-products due to its high chlorine content. The stabilization of TCE is attributed to resonance effects. Water vapor increases the carbon dioxide yield through its role as hydrolysis agent forming reactive carbocations and acting as hydrogen-supplying agent to suppress chlorine-transfer reactions. The deactivation of Cr1.0Cu0.5/SiCl4-Z is mainly due to the chlorination of its metal species, especially with higher Cl/H feed. Coking is limited, particularly with DCM and TCM. In accordance with the Mars-van Krevelen model, the weakening of overall metal reducibility due to chlorination leads to a loss of catalytic activity.

Matched MeSH terms: Volatilization
Fulltext Novel chemical synthesis and characterization of copper pyrovanadate nanoparticles and its influence on the flame retardancy of polymeric nanocomposites

Ghiyasiyan-Arani M, Masjedi-Arani M, Ghanbari D, Bagheri S, Salavati-Niasari M

Sci Rep, 2016 05 04;6:25231.
PMID: 27143312 DOI: 10.1038/srep25231

In this work, copper pyrovanadate (Cu3V2O7(OH)2(H2O)2) nanoparticles have been synthesized by a simple and rapid chemical precipitation method. Different copper-organic complexes were used to control the size and morphology of products. The morphology and structure of the as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrum, electron dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and photoluminescence (PL) spectroscopy. The influence of copper pyrovanadate nanostructures on the flame retardancy of the polystyrene, poly vinyl alcohol and cellulose acetate was studied. Dispersed nanoparticles play the role of a magnetic barrier layer, which slows down product volatilization and prevents the flame and oxygen from the sample during decomposition of the polymer. Cu3V2O7(OH)2(H2O)2 is converted to Cu3V2O8 with an endothermic reaction which simultaneously releases water and decrease the temperature of the flame region.

Matched MeSH terms: Volatilization
Drying kinetics and stabilization of sewage sludge in lagoon in hot climate

Idris A, Yen OB, Hamid MH, Baki AM

Water Sci Technol, 2002;46(9):279-86.
PMID: 12448479

A sludge lagoon has been adopted as a simple and cost effective method for dewatering of sludge. The processes occurring in a sludge lagoon include thickening, dewatering, storage and stabilization; all happening simultaneously. The objective of this study is to determine the dewatering and drying rates at pilot-scale which occur in a lagoon having different design configurations. Two types of sludge lagoons with different initial sludge depth (0.75 m and 0.375 m) were investigated to measure the drying behavior and drying efficiency. The first design is a sludge lagoon with a clay bottom where the dewatering mechanisms are decanting supernatant and evaporation. The second design is a sludge lagoon installed with a sand and underdrains system, where the dewatering mechanisms are filtration or draining and evaporation. Sludge drying kinetic models with high fitness were plotted to describe the sludge drying behavior. Drying of sludge in a sludge lagoon with a clay bottom can best be described by an exponential function. Whereas, drying of sludge in a sludge lagoon with sand and underdrains system followed a logarithmic function. A lagoon designed with sand and underdrains system and having shallower sludge depth was the most efficient. The reduction in volatile solids was lower than 4% during the study period. The drying process proceeded with an increase in dryness and decline in pH value.

Matched MeSH terms: Volatilization
Behaviors of 323Th, 238U, 228Ra and 226Ra on combustion of crude oil terminal sludge

Puad HA, Noor MY

J Environ Radioact, 2004;73(3):289-305.
PMID: 15050361

Crude oil terminal sludge contains technologically enhanced naturally occurring radionuclides such as (232)Th, (238)U, (228)Ra and (226)Ra, thus cannot be disposed of freely without proper control. The current method of disposal, such as land farming and storing in plastic drums is not recommended because it will have a long-term impact on the environment. Due to its organic nature, there is a move to treat this sludge by thermal methods such as incineration. This study has been carried out to determine the behaviors of (232)Th, (238)U, (228)Ra and (226)Ra present in the sludge during combustion at a certain temperature and time. The percentage of volatilization was found to vary between 2% and 70%, (238)U was the most volatile in comparison with (232)Th, (228)Ra and (226)Ra. (238)U is found to be significantly volatilized above 500 degrees C, and might reach maximum volatilization at above 700 degrees C. A mathematical model was developed to predict the percentage of volatilization of (232)Th, (238)U, (228)Ra and (226)Ra contained in the sludge. With this known percentage of volatilization, the concentration of (232)Th, (238)U, (228)Ra and (226)Ra present in the bottom and filter ashes can be calculated.

Matched MeSH terms: Volatilization
Fulltext Phase behavior and fluid interactions of a CO2-Light oil system at high pressures and temperatures

Rezk MG, Foroozesh J

Heliyon, 2019 Jul;5(7):e02057.
PMID: 31384679 DOI: 10.1016/j.heliyon.2019.e02057

This paper investigates the phase behavior and mutual interactions between a light crude oil and CO2 at high pressures and high temperatures (HPHT). To do so, we have measured PVT properties of the CO2-oil system at HPHT using a PVT setup. We have also tried to present a detailed methodology for measuring PVT properties of CO2-oil systems and highlight the difficulties such as oil vaporization by CO2 during the experiments. A crude oil sample, collected from a Malaysian oil field, was used here. Our experiments indicated that, CO2 solubility in the oil increased at higher pressures when measured at a fixed temperature. Our experiments also showed that increasing the test temperature would reduce CO2 solubility in the oil, while its effect is more significant at higher pressures. The swelling factor (SF) measurements showed an increasing trend with pressure up to a certain value so-called extraction pressure, at which, the SF started to be reduced even became less than one. The measurements of oil viscosity indicated that CO2 dissolution in the oil sample could reduce the mixture viscosity up to 61%. The interfacial tensions between CO2 and the crude oil at different pressures were also measured while the results were used to estimate the minimum miscibility pressure (MMP) and the first contact miscibility (FCM) pressure. The IFT measurements at various pressures displayed a reduction trend as a result of more CO2 dissolution in the oil but with two different slopes. That is, at lower pressure values, the measured IFTs were sharply reduced with pressure, while the reduction rate of the IFT became less when pressures exceeded the extraction pressure. This study helps with determining the optimum pressure and temperature conditions of CO2-oil systems to have a minimum IFT, a maximum CO2 solubility and SF, and a minimum oil viscosity that are favorable for CO2-enhanced oil recovery projects. Additionally, the methodology presented here gives guidelines on how to design PVT experiments of CO2-oil systems for petroleum and chemical engineering applications.

Matched MeSH terms: Volatilization
Fulltext Comparison of Peak-area Ratios and Percentage Peak Area Derived from HPLC-evaporative Light Scattering and Refractive Index Detectors for Palm Oil and its Fractions

Ping BTY, Aziz HA, Idris Z

J Oleo Sci, 2018;67(3):265-272.
PMID: 29491321 DOI: 10.5650/jos.ess17164

High-Performance Liquid Chromatography (HPLC) methods via evaporative light scattering (ELS) and refractive index (RI) detectors are used by the local palm oil industry to monitor the TAG profiles of palm oil and its fractions. The quantitation method used is based on area normalization of the TAG components and expressed as percentage area. Although not frequently used, peak-area ratios based on TAG profiles are a possible qualitative method for characterizing the TAG of palm oil and its fractions. This paper aims to compare these two detectors in terms of peak-area ratio, percentage peak area composition, and TAG elution profiles. The triacylglycerol (TAG) composition for palm oil and its fractions were analysed under similar HPLC conditions i.e. mobile phase and column. However, different sample concentrations were used for the detectors while remaining within the linearity limits of the detectors. These concentrations also gave a good baseline resolved separation for all the TAGs components. The results of the ELSD method's percentage area composition for the TAGs of palm oil and its fractions differed from those of RID. This indicates an unequal response of TAGs for palm oil and its fractions using the ELSD, also affecting the peak area ratios. They were found not to be equivalent to those obtained using the HPLC-RID. The ELSD method showed a better baseline separation for the TAGs components, with a more stable baseline as compared with the corresponding HPLC-RID. In conclusion, the percentage area compositions and peak-area ratios for palm oil and its fractions as derived from HPLC-ELSD and RID were not equivalent due to different responses of TAG components to the ELSD detector. The HPLC-RID has a better accuracy for percentage area composition and peak-area ratio because the TAG components response equally to the detector.

Matched MeSH terms: Volatilization
MortalitY in caRdIAc surgery (MYRIAD): A randomizeD controlled trial of volatile anesthetics. Rationale and design

Landoni G, Lomivorotov V, Pisano A, Nigro Neto C, Benedetto U, Biondi Zoccai G, et al.

Contemp Clin Trials, 2017 08;59:38-43.
PMID: 28533194 DOI: 10.1016/j.cct.2017.05.011

OBJECTIVE: There is initial evidence that the use of volatile anesthetics can reduce the postoperative release of cardiac troponin I, the need for inotropic support, and the number of patients requiring prolonged hospitalization following coronary artery bypass graft (CABG) surgery. Nevertheless, small randomized controlled trials have failed to demonstrate a survival advantage. Thus, whether volatile anesthetics improve the postoperative outcome of cardiac surgical patients remains uncertain. An adequately powered randomized controlled trial appears desirable.
DESIGN: Single blinded, international, multicenter randomized controlled trial with 1:1 allocation ratio.
SETTING: Tertiary and University hospitals.
INTERVENTIONS: Patients (n=10,600) undergoing coronary artery bypass graft will be randomized to receive either volatile anesthetic as part of the anesthetic plan, or total intravenous anesthesia.
MEASUREMENTS AND MAIN RESULTS: The primary end point of the study will be one-year mortality (any cause). Secondary endpoints will be 30-day mortality; 30-day death or non-fatal myocardial infarction (composite endpoint); cardiac mortality at 30day and at one year; incidence of hospital re-admission during the one year follow-up period and duration of intensive care unit, and hospital stay. The sample size is based on the hypothesis that volatile anesthetics will reduce 1-year unadjusted mortality from 3% to 2%, using a two-sided alpha error of 0.05, and a power of 0.9.
CONCLUSIONS: The trial will determine whether the simple intervention of adding a volatile anesthetic, an intervention that can be implemented by all anesthesiologists, can improve one-year survival in patients undergoing coronary artery bypass graft surgery.

Matched MeSH terms: Volatilization
Effects of different types of biochar on methane and ammonia mitigation during layer manure composting

Chen W, Liao X, Wu Y, Liang JB, Mi J, Huang J, et al.

Waste Manag, 2017 Mar;61:506-515.
PMID: 28117129 DOI: 10.1016/j.wasman.2017.01.014

Biochar, because of its unique physiochemical properties and sorption capacity, may be an ideal amendment in reducing gaseous emissions during composting process but there has been little information on the potential effects of different types of biochar on undesired gaseous emissions. The objective of this study was to examine the ability and mechanism of different types of biochar, as co-substrate, in mitigating gaseous emission from composting of layer hen manure. The study was conducted in small-scale laboratory composters with the addition of 10% of one of the following biochars: cornstalk biochar, bamboo biochar, woody biochar, layer manure biochar and coir biochar. The results showed that the cumulative NH3 production was significantly reduced by 24.8±2.9, 9.2±1.3, 20.1±2.6, 14.2±1.6, 11.8±1.7% (corrected for initial total N) in the cornstalk biochar, bamboo biochar, woody biochar, layer manure biochar and coir biochar treatments, respectively, compared to the control. Total CH4 emissions was significantly reduced by 26.1±2.3, 15.5±2.1, 22.4±3.1, 17.1±2.1% (corrected for the initial total carbon) for cornstalk biochar, bamboo biochar, woody biochar and coir biochar treatments than the control. Moreover, addition of cornstalk biochar increased the temperature and NO3(-)-N concentration and decreased the pH, NH4(+)-N and organic matter content throughout the composting process. The results suggested that total volatilization of NH3 and CH4 in cornstalk biochar treatment was lower than the other treatments; which could be due to (i) decrease of pH and higher nitrification, (ii) high sorption capacity for gases and their precursors, such as ammonium nitrogen from composting mixtures, because of the higher surface area, pore volumes, total acidic functional groups and CEC of cornstalk biochar.

Matched MeSH terms: Volatilization
Fulltext Macroeconomic dataset for generating macroeconomic volatility among selected countries in the Asia Pacific region

Chow YP, Muhammad J, Amin Noordin BA, Cheng FF

Data Brief, 2018 Feb;16:23-28.
PMID: 29167816 DOI: 10.1016/j.dib.2017.11.015

This data article provides macroeconomic data that can be used to generate macroeconomic volatility. The data cover a sample of seven selected countries in the Asia Pacific region for the period 2004-2014, including both developing and developed countries. This dataset was generated to enhance our understanding of the sources of macroeconomic volatility affecting the countries in this region. Although the Asia Pacific region continues to remain as the most dynamic part of the world's economy, it is not spared from various sources of macroeconomic volatility through the decades. The reported data cover 15 types of macroeconomic data series, representing three broad categories of indicators that can be used to proxy macroeconomic volatility. They are indicators that account for macroeconomic volatility (i.e. volatility as a macroeconomic outcome), domestic sources of macroeconomic volatility and external sources of macroeconomic volatility. In particular, the selected countries are Malaysia, Thailand, Indonesia and Philippines, which are regarded as developing countries, while Singapore, Japan and Australia are developed countries. Despite the differences in level of economic development, these countries were affected by similar sources of macroeconomic volatility such as the Asian Financial Crisis and the Global Financial Crisis. These countries were also affected by other similar external turbulence arising from factors such as the global economic slowdown, geopolitical risks in the Middle East and volatile commodity prices. Nonetheless, there were also sources of macroeconomic volatility which were peculiar to certain countries only. These were generally domestic sources of volatility such as political instability (for Thailand, Indonesia and Philippines), natural disasters and anomalous weather conditions (for Thailand, Indonesia, Philippines, Japan and Australia) and over-dependence on the electronic sector (for Singapore).

Matched MeSH terms: Volatilization
Polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in the equatorial Indian Ocean: temporal trend, continental outflow and air-water exchange

Huang Y, Li J, Xu Y, Xu W, Cheng Z, Liu J, et al.

Mar Pollut Bull, 2014 Mar 15;80(1-2):194-9.
PMID: 24462236 DOI: 10.1016/j.marpolbul.2014.01.007

Nineteen pairs of air and seawater samples collected from the equatorial Indian Ocean onboard the Shiyan I from 4/2011 to 5/2011 were analyzed for PCBs and HCB. Gaseous concentrations of ∑(ICES)PCBs (ICES: International Council for the Exploration of the Seas) and HCB were lower than previous data over the study area. Air samples collected near the coast had higher levels of PCBs relative to those collected in the open ocean, which may be influenced by proximity to source regions and air mass origins. Dissolved concentrations of ∑(ICES)PCBs and HCB were 1.4-14 pg L⁻¹ and 0.94-13 pg L⁻¹, with the highest concentrations in the sample collected from Strait of Malacca. Fugacity fractions suggest volatilization of PCBs and HCB from the seawater to air during the cruise, with fluxes of 0.45-34 ng m⁻² d⁻¹ and 0.36-18 ng m⁻² d⁻¹, respectively.

Matched MeSH terms: Volatilization
Organochlorine pesticides in the atmosphere and surface water from the equatorial Indian Ocean: enantiomeric signatures, sources, and fate

Huang Y, Xu Y, Li J, Xu W, Zhang G, Cheng Z, et al.

Environ Sci Technol, 2013;47(23):13395-403.
PMID: 24251554 DOI: 10.1021/es403138p

Nineteen pairs of gaseous and surface seawater samples were collected along the cruise from Malaysia to the south of Bay of Bengal passing by Sri Lanka between April 12 and May 4, 2011 on the Chinese research vessel Shiyan I to investigate the latest OCP pollution status over the equatorial Indian Ocean. Significant decrease of α-HCH and γ-HCH was found in the air and dissolved water phase owing to global restriction for decades. Substantially high levels of p,p'-DDT, o,p'-DDT, trans-chlordane (TC), and cis-chlordane (CC) were observed in the water samples collected near Sri Lanka, indicating fresh continental riverine input of these compounds. Fugacity fractions suggest equilibrium of α-HCH at most sampling sites, while net volatilization for DDT isomers, TC and CC in most cases. Enantiomer fractions (EFs) of α-HCH and o,p'-DDT in the air and water samples were determined to trace the source of these compounds in the air. Racemic or close to racemic composition was found for atmospheric α-HCH and o,p'-DDT, while significant depletion of (+) enantiomer was found in the water phase, especially for o,p'-DDT (EFs = 0.310 ± 0.178). 24% of α-HCH in the lower air over the open sea of the equatorial Indian Ocean is estimated to be volatilized from local seawater, indicating that long-range transport is the main source.

Matched MeSH terms: Volatilization
Solid-phase microextraction for determining twelve orange flavour compounds in a model beverage emulsion

Mirhosseini H, Tan CP, Yusof S, Hamid NS

Phytochem Anal, 2008 Sep-Oct;19(5):429-37.
PMID: 18435528 DOI: 10.1002/pca.1068

Solid-phase microextraction (SPME) coupled to gas chromatography has been applied for the headspace analysis (HS) of 12 target flavour compounds in a model orange beverage emulsion. The main volatile flavour compounds studied were: acetaldehyde, ethyl acetate, alpha-pinene, ethyl butyrate, beta-pinene, myrcene, limonene, gamma-terpinene, octanal, decanal, linalool and citral (neral plus geranial). After screening the fibre type, the effect of other HS-SPME variables such as adsorption temperature (25-55 degrees C), extraction time (10-40 min), sample concentration (1-100% w/w), sample amount (5-10 g) and salt amount (0-30% w/w) were determined using a two-level fractional factorial design (2(5-2)) that was expanded further to a central composite design. It was found that an extraction process using a carboxen-polydimethylsiloxane fibre coating at 15 masculineC for 50 min with 5 g of diluted emulsion 1% (w/w) and 30% (w/w) of sodium chloride under stirring mode resulted in the highest HS extraction efficiency. For all volatile flavour compounds, the linearity values were accurate in the concentration ranges studied (r(2) > 0.97). Average recoveries that ranged from 90.3 to 124.8% showed a good accuracy for the optimised method. The relative standard deviation for six replicates of all volatile flavour compounds was found to be less than 15%. For all volatile flavour compounds, the limit of detection ranged from 0.20 to 1.69 mg/L.

Matched MeSH terms: Volatilization
Copper vapour laser ID labelling on metal dentures and restorations

Ling BC, Nambiar P, Low KS, Lee CK

J Forensic Odontostomatol, 2003 Jun;21(1):17-22.
PMID: 12793127

Denture marking is accepted as a means of identifying dentures and persons in geriatric institutions, or post-mortem during war, crimes, civil unrest, natural and mass disasters. Labelling on the acrylic resin component of the denture can easily be damaged or destroyed by fire but on cobalt-chromium components it would be more resistant. A copper vapour laser (CVL) can be used to label the cobalt-chromium components of dentures and metal restorations easily, and legibly, and miniaturised for the incorporation of more personal particulars necessary for the identification of the deceased person. The CVL beam is focussed by its optics and delivered to the material surface by the two-axis scanner mounted with mirrors. A personal computer controls the movement of the scanner and the firing of the CVL. The high peak power of the pulsed CVL is focussed to very high energy density producing plasma ablation of the alloy surface. Very fine markings of a few microns width can be produced enabling the storage of detailed information of the deceased person on a metal surface for the purpose of rapid identification.

Matched MeSH terms: Volatilization

Filters

Please provide feedback to Administrator ([email protected])

External Links