Displaying publications 1 - 20 of 188 in total

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  1. Fulltext The Impact of Ethylene Glycol on Droplet Growth Inhibition in Ethylene Vinyl Acetate Emulsions
    Rosdi MRH, Ahmad Razali MA, Ku Ishak KM, Ariffin A
    ACS Omega, 2020 Jun 23;5(24):14473-14480.
    PMID: 32596585 DOI: 10.1021/acsomega.0c01114
    Pour point depressant (PPD) emulsion has been gaining attention in crude oil transportation owing to its potential to solve solidification issues that arise in cold climate environments. An emulsion system provides a wide range of temperature application that combines good shelf life and tunable thermal properties to tackle this problem. These features can be achieved by incorporating an antifreeze agent into the emulsion. One of the most commonly used antifreeze agents is ethylene glycol (EG). Hence, this study focuses on the thermal properties and droplet size growth of PPD emulsions that were aged in variable concentrations of EG solution. EG50 exhibited the lowest freezing temperature of -44 °C, while EG25 demonstrated the lowest vitrification temperature of -68.7 °C. The particle size of the emulsions underwent a significant reduction from 332.3 to 228.9 nm upon the stepwise EG concentration increment to EG50. However, when the concentration was increased to EG75, a slight increase in the emulsion particle size was observed with a recorded value of 237.8 nm. Thus, it is concluded that EG50 represents the optimum concentration for delivering the best freezing protection and producing a smaller droplet particle size.
    Matched MeSH terms: Cold Temperature
  2. Effects of Crude Palm Oil and Crude Palm Kernel Oil Upon Wax Inhibition
    Ragunathan T, Husin H, Wood CD
    ACS Omega, 2020 Aug 11;5(31):19342-19349.
    PMID: 32803027 DOI: 10.1021/acsomega.0c00753
    The ever-increasing demand for the finite source of oil has led oil production companies to produce and transport the produced crude oil as efficiently and economically as possible. One of the major concerns especially in waters like the South China Sea is the deposition of wax on the walls of the pipeline or wellbore, constricting and hindering the hydrocarbon flow. This is due to the low seabed temperatures, which can be below the wax appearance temperature (WAT), leading to the deposition of wax out of waxy crude oil through the molecular dispersion mechanism. Currently, many prevention and remedy methods are in place to overcome the problem, but most of the additives possess environmental threat, as most of the chemical solutions used are toxic, nonorganic, and costly. Hence, this paper aims to provide some insights into the effect of palm oil derivatives such as crude palm oil (CPO) and crude palm kernel oil (CPKO) on wax inhibition. The effect of aging time (i.e., immersion time) was also evaluated. A comparison was made between paraffin inhibition efficiency results (PIE %) obtained by CPO, CPKO, poly(ethylene-co-vinyl acetate) (EVA), and triethanolamine (TEA). It was observed that the average efficiency of 81.67% was obtained when 1% CPO was added to heavy crude oil. The wax inhibition performance reached a plateau after 1.5 h of aging time for all of the investigated samples.
    Matched MeSH terms: Cold Temperature
  3. Fulltext Non-benzodiazepine hypnotic dependence: a case report
    Amer Siddiq Amer Nordin, Azreen Hashim, Mohamad Hussain Habil, Noor Zurani Md Haris Robson
    ASEAN Journal of Psychiatry, 2010;11(1):108-112.
    MyJurnal
    Objective: This case report highlights the abuse and dependence potential of Zolpidem and the risk of life-threatening withdrawal symptoms upon abrupt discontinuation. Method: We report a case of Zolpidem dependence which presented with withdrawal symptoms upon abrupt discontinuation. Results: A 32 year old male, who had abused non-benzodiazepine Zolpidem for 6 years presented to the accident and emergency unit with generalized seizures upon stopping Zolpidem ‘cold turkey’. He required admission to the neurology high dependency unit for stabilization of the seizures and was later managed by the addiction team where a tapering dose of benzodiazepine was prescribed. Conclusion: This case demonstrates that non-benzodiazepine agents can cause tolerance and dependence, and thus produce withdrawal symptoms upon discontinuation.
    Matched MeSH terms: Cold Temperature
  4. Fulltext Antarctica: bioprospecting, access and benefit-sharing of genetic resources
    Zakri, A.H.
    ASM Science Journal, 2009;3(2):200-202.
    MyJurnal
    Recent studies by the United Nations University - Institute of Advanced Studies (UNU-IAS) demonstrate that bioprospecting is taking place in Antarctica and the Southern Ocean and that related commercial applications were being marketed. The bioprospectors’ interest in Antarctica stems from two reasons. First, the lack of knowledge surrounding Antarctic biota provides opportunities to discover novel organisms of potential use to biotechnology. Second, Antarctica’s environmental extremes, such as cold temperatures, extreme aridity and salinity present conditions in which biota have evolved unique characteristics for survival (UNU-IAS 2003). Thus bioprospecting opportunities include, inter alia, the discovery of novel bioactives in species found in cold and dry lithic habitat, novel pigments found in hyper-saline lakes and antifreezes in sea-lakes (Cheng & Cheng 1999).
    Matched MeSH terms: Cold Temperature
  5. Fulltext Effects of nitrate, phosphate, temperature and light-dark cycle on algal growth potential of Chlorococcum sp. from Reeve Hill, Antarctica
    Masdialily, D., Maznah, W.O.W., Faradina, M., Mashhor, M.
    ASM Science Journal, 2010;4(1):74-80.
    MyJurnal
    In this study the effects of phosphorus and nitrogen levels, temperature and light-dark cycle on the algal growth potential (AGP) of an Antarctic Chlorococcum isolated from an ephemeral stream at Reeve Hill, Antarctica was investigated. The highest AGP was attained when the cultures were grown at high nitrogen concentration (329.87 mg NO3-N/l) and low phosphorus concentration (2.6 mg PO4-P/l) at 4ºC on a 12 h:12 h light-dark cycle. The results showed that Chlorococcum sp. required a high concentration of nitrogen, low concentration of phosphorus, low temperature with equal lengths of light and dark period (12 h:12 h) for optimum growth.
    Matched MeSH terms: Cold Temperature
  6. Fulltext Purification of metallurgical grade silicon by acid leaching
    Lashgari, V.A., Yoozbashizadeh, H.
    ASM Science Journal, 2007;1(1):37-41.
    MyJurnal
    Silicon, as the most important electronic material, has a lot of applications in the electronic industry and this includes the use of silicon in solar cells. One of the solar grade silicon production processes is the use of acid leaching for the removal of metallic impurities from silicon. The main advantage of this process for silicon purification is that it is based on a low temperature process. The purification of metallurgical grade silicon by acid leaching was studied as a function of time, temperature and etching. Based upon experimental results and under optimum conditions, it was possible to remove 41%, 71% and 25% of iron, calcium and aluminum respectively, with the use of aqua regia.
    Matched MeSH terms: Cold Temperature
  7. The 143 and 300 K polymorphs of hexamethylenetetraminium 2,4-dinitrophenolate monohydrate
    Usman A, Chantrapromma S, Fun HK
    Acta Crystallogr C, 2001 Dec;57(Pt 12):1443-6.
    PMID: 11740112
    The title compound, 3,5,7-triaza-1-azoniatricyclo[3.3.1.1(3,7)]decane 2,4-dinitrophenolate monohydrate, C6H13N4+*C6H3N2O5-*H2O, the 1:1 hydrate adduct of hexamethylenetetramine (HMT) and 2,4-dinitrophenol, undergoes a temperature phase transition. In the room-temperature phase, the adduct crystallizes in the monoclinic P2(1)/m space group, whereas in the low-temperature phase, the adduct crystallizes in the triclinic P1 space group. This phase transition is reversible, with the transition temperature at 273 K, and the phase transition is governed by hydrogen bonds and weak interactions. In both these temperature-dependent polymorphs, the crystal structure is alternately layered with sheets of hexamethylenetetramine and sheets of dinitrophenol stacked along the c axis. The hexamethylenetetramine and dinitrophenol moieties are linked by intermolecular hydrogen bonds. The water molecule in the adduct plays an important role, forming O-H...O hydrogen bonds which, together with C-H...O hydrogen bonds, bridge the adducts into molecular ribbons. Extra hydrogen bonds and weak interactions exist for the low-temperature polymorph and these interconnect the molecular ribbons into a three-dimensional packing structure. Also in these two temperature-dependent polymorphs, dinitrophenol acts as a hydrogen-bond acceptor and HMT acts as a hydrogen-bond donor.
    Matched MeSH terms: Cold Temperature
  8. IDIOPATHIC AUTO-IMMUNE HAEMOLYTIC ANAEMIA IN MALAYA
    LIE-INJOLUAN EN, PILLAY RP
    Acta Haematol., 1964 May;31:282-8.
    PMID: 14172696
    Matched MeSH terms: Cold Temperature*
  9. Natural Variation in Freezing Tolerance and Cold Acclimation Response in Arabidopsis thaliana and Related Species
    Zuther E, Lee YP, Erban A, Kopka J, Hincha DK
    Adv Exp Med Biol, 2018 10 6;1081:81-98.
    PMID: 30288705 DOI: 10.1007/978-981-13-1244-1_5
    During low-temperature exposure, temperate plant species increase their freezing tolerance in a process termed cold acclimation. The molecular mechanisms involved in cold acclimation have been mostly investigated in Arabidopsis thaliana. In addition, other Brassicaceae species related to A. thaliana have been employed in recent years to study plant stress responses on a phylogenetically broader basis and in some cases with extremophile species with a much higher stress tolerance. In this paper, we briefly summarize cold acclimation responses in A. thaliana and current knowledge about cold acclimation in A. thaliana relatives with special emphasis on Eutrema salsugineum and two closely related Thellungiella species. We then present a transcriptomic and metabolomic analysis of cold acclimation in five A. thaliana and two E. salsugineum accessions that differ widely in their freezing tolerance. Differences in the cold responses of the two species are discussed.
    Matched MeSH terms: Cold Temperature
  10. A Review on Psychrophilic β-D-Galactosidases and Their Potential Applications
    Reddy LJ, Kumar PS, Pandrangi SL, Chikati R, Srinivasulu C, John A, et al.
    Appl Biochem Biotechnol, 2023 Apr;195(4):2743-2766.
    PMID: 36422804 DOI: 10.1007/s12010-022-04215-w
    The majority of the Earth's ecosystem is frigid and frozen, which permits a vast range of microbial life forms to thrive by triggering physiological responses that allow them to survive in cold and frozen settings. The apparent biotechnology value of these cold-adapted enzymes has been targeted. Enzymes' market size was around USD 6.3 billion in 2017 and will witness growth at around 6.8% CAGR up to 2024 owing to shifting consumer preferences towards packaged and processed foods due to the rising awareness pertaining to food safety and security reported by Global Market Insights (Report ID-GMI 743). Various firms are looking for innovative psychrophilic enzymes in order to construct more effective biochemical pathways with shorter reaction times, use less energy, and are ecologically acceptable. D-Galactosidase catalyzes the hydrolysis of the glycosidic oxygen link between the terminal non-reducing D-galactoside unit and the glycoside molecule. At refrigerated temperature, the stable structure of psychrophile enzymes adjusts for the reduced kinetic energy. It may be beneficial in a wide variety of activities such as pasteurization of food, conversion of biomass, biological role of biomolecules, ambient biosensors, and phytoremediation. Recently, psychrophile enzymes are also used in claning the contact lens. β-D-Galactosidases have been identified and extracted from yeasts, fungi, bacteria, and plants. Conventional (hydrolyzing activity) and nonconventional (non-hydrolytic activity) applications are available for these enzymes due to its transgalactosylation activity which produce high value-added oligosaccharides. This review content will offer new perspectives on cold-active β-galactosidases, their source, structure, stability, and application.
    Matched MeSH terms: Cold Temperature
  11. Psychrophilic enzymes: structural adaptation, pharmaceutical and industrial applications
    Parvizpour S, Hussin N, Shamsir MS, Razmara J
    Appl Microbiol Biotechnol, 2021 Feb;105(3):899-907.
    PMID: 33427934 DOI: 10.1007/s00253-020-11074-0
    Psychrophiles are cold-living microorganisms synthesizing enzymes that are permanently active at almost near-zero temperatures. Psychrozymes are supposed to be structurally more flexible than their homologous proteins. This structural flexibility enables these proteins to undergo conformational changes during catalysis and improve catalytic efficiency at low temperatures. The outstanding characteristics of the psychrophilic enzymes have attracted the attention of the scientific community to utilize them in a wide variety of industrial and pharmaceutical applications. In this review, we first highlight the current knowledge of the cold-adaptation mechanisms of the psychrophiles. In the sequel, we describe the potential applications of the enzymes in different biotechnological processes specifically, in the production of industrial and pharmaceutical products. KEY POINTS: • Methods that organisms have evolved to survive and proliferate at cold environments. • The economic benefits due to their high activity at low and moderate temperatures. • Applications of the psychrophiles in biotechnological and pharmaceutical industry.
    Matched MeSH terms: Cold Temperature
  12. Cold plasma inactivation of chronic wound bacteria
    Mohd Nasir N, Lee BK, Yap SS, Thong KL, Yap SL
    Arch Biochem Biophys, 2016 09 01;605:76-85.
    PMID: 27046340 DOI: 10.1016/j.abb.2016.03.033
    Cold plasma is partly ionized non-thermal plasma generated at atmospheric pressure. It has been recognized as an alternative approach in medicine for sterilization of wounds, promotion of wound healing, topical treatment of skin diseases with microbial involvement and treatment of cancer. Cold plasma used in wound therapy inhibits microbes in chronic wound due to its antiseptic effects, while promoting healing by stimulation of cell proliferation and migration of wound relating skin cells. In this study, two types of plasma systems are employed to generate cold plasma: a parallel plate dielectric barrier discharge and a capillary-guided corona discharge. Parameters such as applied voltage, discharge frequency, treatment time and the flow of the carrier gas influence the cold plasma chemistry and therefore change the composition and concentration of plasma species that react with the target sample. Chronic wound that fails to heal often infected by multidrug resistant organisms makes them recalcitrant to healing. Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (Pseudomonas aeruginosa) are two common bacteria in infected and clinically non-infected wounds. The efficacies of the cold plasma generated by the two designs on the inactivation of three different isolates of MRSA and four isolates of P. aeruginosa are reported here.
    Matched MeSH terms: Cold Temperature
  13. Fulltext Functional expression of a novel α-amylase from Antarctic psychrotolerant fungus for baking industry and its magnetic immobilization
    He L, Mao Y, Zhang L, Wang H, Alias SA, Gao B, et al.
    BMC Biotechnol, 2017 02 28;17(1):22.
    PMID: 28245836 DOI: 10.1186/s12896-017-0343-8
    BACKGROUND: α-Amylase plays a pivotal role in a broad range of industrial processes. To meet increasing demands of biocatalytic tasks, considerable efforts have been made to isolate enzymes produced by extremophiles. However, the relevant data of α-amylases from cold-adapted fungi are still insufficient. In addition, bread quality presents a particular interest due to its high consummation. Thus developing amylases to improve textural properties could combine health benefits with good sensory properties. Furthermore, iron oxide nanoparticles provide an economical and convenient method for separation of biomacromolecules. In order to maximize the catalytic efficiency of α-amylase and support further applications, a comprehensive characterization of magnetic immobilization of α-amylase is crucial and needed.

    RESULTS: A novel α-amylase (AmyA1) containing an open reading frame of 1482 bp was cloned from Antarctic psychrotolerant fungus G. pannorum and then expressed in the newly constructed Aspergillus oryzae system. The purified recombinant AmyA1 was approximate 52 kDa. AmyA1 was optimally active at pH 5.0 and 40 °C, and retained over 20% of maximal activity at 0-20 °C. The K m and V max values toward soluble starch were 2.51 mg/mL and 8.24 × 10-2 mg/(mL min) respectively, with specific activity of 12.8 × 103 U/mg. AmyA1 presented broad substrate specificity, and the main hydrolysis products were glucose, maltose, and maltotetraose. The influence of AmyA1 on the quality of bread was further investigated. The application study shows a 26% increase in specific volume, 14.5% increase in cohesiveness and 14.1% decrease in gumminess in comparison with the control. AmyA1 was immobilized on magnetic nanoparticles and characterized. The immobilized enzyme showed improved thermostability and enhanced pH tolerance under neutral conditions. Also, magnetically immobilized AmyA1 can be easily recovered and reused for maximum utilization.

    CONCLUSIONS: A novel α-amylase (AmyA1) from Antarctic psychrotolerant fungus was cloned, heterologous expression in Aspergillus oryzae, and characterized. The detailed report of the enzymatic properties of AmyA1 gives new insights into fungal cold-adapted amylase. Application study showed potential value of AmyA1 in the food and starch fields. In addition, AmyA1 was immobilized on magnetic nanoparticles and characterized. The improved stability and longer service life of AmyA1 could potentially benefit industrial applications.

    Matched MeSH terms: Cold Temperature
  14. Fulltext Structural adaptation of cold-active RTX lipase from Pseudomonas sp. strain AMS8 revealed via homology and molecular dynamics simulation approaches
    Mohamad Ali MS, Mohd Fuzi SF, Ganasen M, Abdul Rahman RN, Basri M, Salleh AB
    Biomed Res Int, 2013;2013:925373.
    PMID: 23738333 DOI: 10.1155/2013/925373
    The psychrophilic enzyme is an interesting subject to study due to its special ability to adapt to extreme temperatures, unlike typical enzymes. Utilizing computer-aided software, the predicted structure and function of the enzyme lipase AMS8 (LipAMS8) (isolated from the psychrophilic Pseudomonas sp., obtained from the Antarctic soil) are studied. The enzyme shows significant sequence similarities with lipases from Pseudomonas sp. MIS38 and Serratia marcescens. These similarities aid in the prediction of the 3D molecular structure of the enzyme. In this study, 12 ns MD simulation is performed at different temperatures for structural flexibility and stability analysis. The results show that the enzyme is most stable at 0°C and 5°C. In terms of stability and flexibility, the catalytic domain (N-terminus) maintained its stability more than the noncatalytic domain (C-terminus), but the non-catalytic domain showed higher flexibility than the catalytic domain. The analysis of the structure and function of LipAMS8 provides new insights into the structural adaptation of this protein at low temperatures. The information obtained could be a useful tool for low temperature industrial applications and molecular engineering purposes, in the near future.
    Matched MeSH terms: Cold Temperature*
  15. Fulltext Effect of uv-ozone treatment on physicochemical properties of mesoporous hollow carbon nanoparticles
    Muhammad Nur Amir Azman, Yusilawati Ahmad Nor, Nur Husna Samsudin, Ma’an Fahmi Rashid Alkhatib, Yeow, Tshai Kim
    Biological and Natural Resources Engineering Journal, 2020;3(2):35-45.
    MyJurnal
    Carbon nanoparticles have been widely used in various applications. However, they are commonly known to have low dispersibility and chemical inertness which limit their practical ability in medical or biological area. Some studies have been performed to modify carbon nanoparticles such as carbon nanotubes using ultraviolet (UV)-Ozone system. However, little is known on the effects of such system towards other types of carbon nanoparticles such as mesoporous hollow carbon nanoparticles (MHCNs). Thus, in this study, improvement of MHCNs physiochemical properties have been studied using UV-Ozone treatment for the first time. The treatment was conducted in water as dispersant agent at ozone flowrate of 1.0 L/min and exposure time of 45 min. SEM images observed that MHCNs morphology and surface structure remain intact after the treatment. Observations on the dispersibility of MHCNs in phosphate buffered saline (PBS) solution shows that the dispersibility was improved compared to the untreated ones. This was supported by the low Z-average and PDI values of treated MHCNs obtained at ~400 nm and 0.2, respectively when compared to the untreated MHCNs which was obtained at 970 nm and 0.417, respectively. Thermogravimetric analysis (TGA) showed an increased in weight loss of treated MHCNs at the lower temperature compared to untreated MHCNs. Results from Fourier Transform Infrared (FTIR) showed an increase number of new functional groups that includes carboxylic acid group presence at the surface of treated MHCNs which contributes to the improvement of their dispersibility, thermal properties and chemical functionality. These findings opened a new possibility of using UV-Ozone treatment to improve physicochemical properties of MHCNs for medical area such as in drug delivery application in addition to their excellent storage and carrier system.
    Matched MeSH terms: Cold Temperature
  16. Effect of ultrasonic pre-treatment on low temperature acid hydrolysis of oil palm empty fruit bunch
    Yunus R, Salleh SF, Abdullah N, Biak DR
    Bioresour Technol, 2010 Dec;101(24):9792-6.
    PMID: 20719502 DOI: 10.1016/j.biortech.2010.07.074
    Various pre-treatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. The effect of ultrasonic pre-treatment on oil palm empty fruit bunch (OPEFB) fibre prior to acid hydrolysis has been evaluated. The main objective of this study was to determine if ultrasonic pre-treatment could function as a pre-treatment method for the acid hydrolysis of OPEFB fibre at a low temperature and pressure. Hydrolysis at a low temperature was studied using 2% sulphuric acid; 1:25 solid liquid ratio and 100 degrees C operating temperature. A maximum xylose yield of 58% was achieved when the OPEFB fibre was ultrasonicated at 90% amplitude for 45min. In the absence of ultrasonic pre-treatment only 22% of xylose was obtained. However, no substantial increase of xylose formation was observed for acid hydrolysis at higher temperatures of 120 and 140 degrees C on ultrasonicated OPEFB fibre. The samples were then analysed using a scanning electron microscope (SEM) to describe the morphological changes of the OPEFB fibre. The SEM observations show interesting morphological changes within the OPEFB fibre for different acid hydrolysis conditions.
    Matched MeSH terms: Cold Temperature*
  17. Characterization of natural low transition temperature mixtures (LTTMs): Green solvents for biomass delignification
    Yiin CL, Quitain AT, Yusup S, Sasaki M, Uemura Y, Kida T
    Bioresour Technol, 2016 Jan;199:258-264.
    PMID: 26253419 DOI: 10.1016/j.biortech.2015.07.103
    The aim of this work was to characterize the natural low transition temperature mixtures (LTTMs) as promising green solvents for biomass pretreatment with the critical characteristics of cheap, biodegradable and renewable, which overcome the limitations of ionic liquids (ILs). The LTTMs were derived from inexpensive commercially available hydrogen bond acceptor (HBA) and l-malic acid as the hydrogen bond donor (HBD) in distinct molar ratios of starting materials and water. The peaks involved in the H-bonding shifted and became broader for the OH groups. The thermal properties of the LTTMs were not affected by water while the biopolymers solubility capacity of LTTMs was improved with the increased molar ratio of water and treatment temperature. The pretreatment of oil palm biomass was consistence with the screening on solubility of biopolymers. This work provides a cost-effective alternative to utilize microwave hydrothermal extracted green solvents such as malic acid from natural fruits and plants.
    Matched MeSH terms: Cold Temperature*
  18. Comparative toxicity of nine metals to two Malaysian aquatic dipterian larvae with reference to temperature variation
    Vedamanikam VJ, Shazilli NA
    Bull Environ Contam Toxicol, 2008 Jun;80(6):516-20.
    PMID: 18414763 DOI: 10.1007/s00128-008-9413-x
    A study was conducted to determine the suitability of using selected aquatic dipterian larvae for biomonitoring bioassays. The organisms included a member of the biting midge family that was identified as Culicoides furens and a member of the non-biting midge family, identified as Chironomus plumosus. Median lethal toxicity tests were conducted to observe the variation between metal sensitivities between the two larval forms and how variations in temperature could affect the experimental setup. Nine heavy metals were used in the study. It was observed that the 96 h LC(50) (in mg/L) for the different metals was found to be Zn-16.21 (18.55 +/- 13.87); Cr-0.96 (1.08 +/- 0.84); Ag-4.22 (6.87 +/- 1.57); Ni-0.42 (0.59 +/- 0.25); Hg-0.42 (0.59 +/- 0.25); Pb-16.21 (18.31 +/- 14.11); Cu-42.24 (45.18 +/- 39.30); Mn-4.22 (7.19 +/- 1.25); Cd-0.42 (0.59 +/- 0.25) for the Chironomus plumosus and Zn-4.22 (6.56 +/- 1.88); Cr-0.42 (0.54 +/- 0.30); Ag-0.42 (0.54 +/- 0.30); Ni-0.42 (0.54 +/- 0.30); Hg-0.04 (0.07 +/- 0.01); Pb-0.42 (0.54 +/- 0.30); Cu-42.24 (45.18 +/- 39.30); Mn-4.22 (6.56 +/- 1.88); Cd-0.42 (0.54 +/- 0.30) in the case of the Culicoides furens. With temperature as a variable the LC(50) values were observed to increase from 2.51 mg/L at 10 degrees C to 4.22 ppm at 30 degrees C and to reduce slightly to 3.72 mg/L at 35 degrees C as seen in the case of Zn. It was also observed that at 40 degrees C thermal toxicity and chemical toxicity overlapped as 100% mortality was observed in the controls. This trend was observed in all metals for both C. plumosus and C. furens. Thus indicating temperature played an important role in determining LC(50) values of toxicants.
    Matched MeSH terms: Cold Temperature/adverse effects*
  19. Fulltext Evaluation of cold chain monitoring in Kelantan, Malaysia
    Hanjeet K, Lye MS, Sinniah M, Schnur A
    Bull World Health Organ, 1996;74(4):391-7.
    PMID: 8823961
    An analysis was carried out on a total of 883 cold chain monitor (CCM) cards, which had been attached to batches of poliomyelitis, measles, DPT (diphtheria, pertussis, tetanus) and hepatitis B vaccines, during their transport and storage from the central store in Kuala Lumpur to Kelantan, a state in north-eastern Malaysia; 234 freeze watches attached to hepatitis B vaccines were also analysed. The monitor cards and freeze watches were observed at six levels between the central store and the periphery during distribution of the vaccines, and a colour change in any of the four windows (A, B, C, D) on the CCM cards or the freeze watches was recorded. In addition, 33 unopened vials of oral poliovirus vaccine (OPV), collected from refrigerators in 29 health facilities in Kelantan, were tested for potency using the tissue culture infective dose 50 (TCID50) method; 14 of them (42%) did not meet the WHO criteria for potent vaccines. The results showed that at the final destination 13.4% of all cards remained white while a colour change to blue was observed in 65% in window A, 16.6% in window B, and 4.4% in window C; none had turned blue in window D indicating that the vaccine had not been subjected to temperatures > or = 34 degrees C for 2 hours. All but 2 of the 234 freeze watches had turned purple, which indicates exposure of the hepatitis B vaccines to temperatures below 0 degree C. These results will assist health planners to correct the weaknesses identified in the cold chain system.
    Matched MeSH terms: Cold Temperature*
  20. Thermal design and zeotropic working fluids mixture selection optimization for a solar waste heat driven combined cooling and power system
    Kheimi M, K Salamah S, A Maddah H, Mustafa Al Bakri Abdullah M
    Chemosphere, 2023 Sep;335:139036.
    PMID: 37245592 DOI: 10.1016/j.chemosphere.2023.139036
    Considering the limitation of fossil fuel resources and their environmental effects, the use of renewable energies is increasing. In the current research, a combined cooling and power production (CCPP) system is investigated, the energy source of which is solar energy. Solar energy absorbs by solar flat plate collectors (SFPC). The system produces power with the help of an organic Rankine cycle (ORC). An ejector refrigeration cycle (ERC) system is considered to provide cooling capacity. The motive flow is supplied from the expander extraction in the ERC system. Various working fluids have been applied so far for the ORC-ERC cogeneration system. This research investigates the effect of using two working fluids R-11 and R-2545fa, and the zeotropic mixtures obtained by mixing these two fluids. A multiobjective optimization process is considered to select the appropriate working fluid. In the optimization design process, the goal is to minimize the total cost rate (TCR) and maximize the exergy efficiency of the system. The design variables are the quantity of SFPC, heat recovery vapor generator (HRVG) pressure, ejector motive flow pressure, evaporator pressure, condenser pressure, and entertainment ratio. Finally, it is observed that using zeotropic mixtures obtained from these two refrigerants has a better result than using pure refrigerants. Finally, it is observed that the best performance is achieved when R-11 and R245fa are mixed with a ratio of 80 to 20%, respectively and led to 8.5% improvement in exergy efficiency, while the increase in TCR is only 1.5%.
    Matched MeSH terms: Cold Temperature
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