Displaying publications 21 - 40 of 189 in total

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  1. Fulltext Self-Fluxing Mechanism in Geopolymerization for Low-Sintering Temperature of Ceramic
    Jamil NH, Abdullah MMAB, Pa FC, Mohamad H, Ibrahim WMAW, Amonpattaratkit P, et al.
    Materials (Basel), 2021 Mar 10;14(6).
    PMID: 33801862 DOI: 10.3390/ma14061325
    Kaolin, theoretically known as having low reactivity during geopolymerization, was used as a source of aluminosilicate materials in this study. Due to this concern, it is challenging to directly produce kaolin geopolymers without pre-treatment. The addition of ground granulated blast furnace slag (GGBS) accelerated the geopolymerization process. Kaolin-GGBS geopolymer ceramic was prepared at a low sintering temperature due to the reaction of the chemical composition during the initial stage of geopolymerization. The objective of this work was to study the influence of the chemical composition towards sintering temperature of sintered kaolin-GGBS geopolymer. Kaolin-GGBS geopolymer was prepared with a ratio of solid to liquid 2:1 and cured at 60 °C for 14 days. The cured geopolymer was sintered at different temperatures: 800, 900, 1000, and 1100 °C. Sintering at 900 °C resulted in the highest compressive strength due to the formation of densified microstructure, while higher sintering temperature led to the formation of interconnected pores. The difference in the X-ray absorption near edge structure (XANES) spectra was related to the phases obtained from the X-ray diffraction analysis, such as akermanite and anothite. Thermal analysis indicated the stability of sintered kaolin-GGBS geopolymer when exposed to 1100 °C, proving that kaolin can be directly used without heat treatment in geopolymers. The geopolymerization process facilitates the stability of cured samples when directly sintered, as well as plays a significant role as a self-fluxing agent to reduce the sintering temperature when producing sintered kaolin-GGBS geopolymers.
    Matched MeSH terms: Cold Temperature
  2. Structural and functional characterisation of a cold-active yet heat-tolerant dehydroquinase from Glaciozyma antarctica PI12
    Jaafar NR, Mahadi NM, Mackeen MM, Illias RM, Murad AMA, Abu Bakar FD
    J Biotechnol, 2021 Mar 10;329:118-127.
    PMID: 33539893 DOI: 10.1016/j.jbiotec.2021.01.019
    Dehydroquinase or 3-dehydroquinate dehydratase (DHQD) reversibly cleaves 3-dehydroquinate to form 3-dehydroshikimate. Here, we describe the functional and structural features of a cold active type II 3-dehydroquinate dehydratase from the psychrophilic yeast, Glaciozyma antarctica PI12 (GaDHQD). Functional studies showed that the enzyme was active at low temperatures (10-30 °C), but displayed maximal activity at 40 °C. Yet the enzyme was stable over a wide range of temperatures (10-70 °C) and between pH 6.0-10.0 with an optimum pH of 8.0. Interestingly, the enzyme was highly thermo-tolerant, denaturing only at approximately 84 °C. Three-dimensional structure analyses showed that the G. antarctica dehydroquinase (GaDHQD) possesses psychrophilic features in comparison with its mesophilic and thermophilic counterparts such as higher numbers of non-polar residues on the surface, lower numbers of arginine and higher numbers of glycine-residues with lower numbers of hydrophobic interactions. On the other hand, GaDHQD shares some traits (i.e. total number of hydrogen bonds, number of proline residues and overall folding) with its mesophilic and thermophilic counterparts. Combined, these features contribute synergistically towards the enzyme's ability to function at both low and high temperatures.
    Matched MeSH terms: Cold Temperature*
  3. Fulltext Head Cooling Prior to Exercise in the Heat Does Not Improve Cognitive Performance
    Mazalan NS, Landers GJ, Wallman KE, Ecker U
    J Sports Sci Med, 2021 03;20(1):69-76.
    PMID: 33707989 DOI: 10.52082/jssm.2021.69
    This study investigated the effectiveness of head cooling on cognitive performance after 30 min and 60 min of running in the heat. Ten moderately-trained, non-heat-acclimated, male endurance athletes (mean age: 22 ± 6.6 y; height: 1.78 ± 0.10 m; body-mass: 75.7 ± 15.6 kg; VO2peak: 51.6 ± 4.31 mL-1>kg-1>min) volunteered for this study. Participants performed two experimental trials: head cooling versus no-cooling (within-subjects factor with trial order randomized). For each trial, participants wore a head-cooling cap for 15 min with the cap either cooled to 0°C (HC) or not cooled (22°C; CON). Participants then completed 2 × 30 min running efforts on a treadmill at 70% VO2peak in hot conditions (35°C, 70% relative humidity), with a 10 min rest between efforts. Working memory was assessed using an operation span (OSPAN) task immediately prior to the 15 min cooling/no-cooling period (22°C, 35% RH) and again after 30 min and 60 min of running in the heat. Numerous physiological variables, including gastrointestinal core temperature (Tc) were assessed over the protocol. Scores for OSPAN were similar between trials, with no interaction effect or main effects for time and trial found (p = 0.58, p = 0.67, p = 0.54, respectively). Forehead temperature following precooling was lower in HC (32.4 ± 1.6°C) compared with CON (34.5 ± 1.1°C) (p = 0.01), however, no differences were seen in Tc, skin temperature, heart rate and ratings of perceived exertion between HC and CON trials at any time point assessed (p > 0.05). In conclusion, despite HC reducing forehead temperature prior to exercise, it did not significantly improve cognitive performance during (half-time break) or after subsequent exercise in hot environmental conditions, compared to a no cooling control.
    Matched MeSH terms: Cold Temperature
  4. 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
  5. Fulltext CHARACTERISTIC OF PRASEODYMIUM OXIDE DOPED MANGANESE/RUTHENIUM CATALYST IN METHANATION: EFFECT CALCINATION TEMPERATURE
    Salmiah Jamal Mat Rosid, Susilawati Toemen, Wan Azelee Wan Abu Bakar, Sarina Mat Rosid, Wan Nazwanie Wan Abdullah, Siti Maisarah Aziz
    Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2021;9(1):49-55.
    MyJurnal
    Lanthanide element in the methanation reaction gives an excellent catalytic performance at low reaction temperature. Praseodymium is one of lanthanide element and was chosen due to its properties which are thermally stable and provide excess of oxygen in the oxide lattice. Therefore, a catalyst of Ru/Mn/Pr (5:30:65)/Al2O3 (RMP, 5:30:65/Al2O3) was prepared via wetness impregnation method and the effect of calcination temperature on the catalyst performance was investigated using FTIR analysis. The RMP/Al2O3 catalyst calcined at 800 o C was chosen as an excel catalyst with CO2 conversion of 96.9% and CH4 formation of 45.1% at 350 o C reaction temperature. From the EDX mapping, it can be observed that the distribution of all element is homogeneous at 800 o C and 900 o C except Ru, O and Al at 1000 o C calcination temperature. The image from FESEM also shows the presence of some crystal shape on the catalyst surface. From the FTIR analysis, the peak stretching and bending mode of O-H bond decreased when the calcination temperature increased.
    Matched MeSH terms: Cold Temperature
  6. Fulltext Statistical Optimisation of Phenol Degradation and Pathway Identification through Whole Genome Sequencing of the Cold-Adapted Antarctic Bacterium, Rhodococcus sp. Strain AQ5-07
    Lee GLY, Zakaria NN, Convey P, Futamata H, Zulkharnain A, Suzuki K, et al.
    Int J Mol Sci, 2020 Dec 09;21(24).
    PMID: 33316871 DOI: 10.3390/ijms21249363
    Study of the potential of Antarctic microorganisms for use in bioremediation is of increasing interest due to their adaptations to harsh environmental conditions and their metabolic potential in removing a wide variety of organic pollutants at low temperature. In this study, the psychrotolerant bacterium Rhodococcus sp. strain AQ5-07, originally isolated from soil from King George Island (South Shetland Islands, maritime Antarctic), was found to be capable of utilizing phenol as sole carbon and energy source. The bacterium achieved 92.91% degradation of 0.5 g/L phenol under conditions predicted by response surface methodology (RSM) within 84 h at 14.8 °C, pH 7.05, and 0.41 g/L ammonium sulphate. The assembled draft genome sequence (6.75 Mbp) of strain AQ5-07 was obtained through whole genome sequencing (WGS) using the Illumina Hiseq platform. The genome analysis identified a complete gene cluster containing catA, catB, catC, catR, pheR, pheA2, and pheA1. The genome harbours the complete enzyme systems required for phenol and catechol degradation while suggesting phenol degradation occurs via the β-ketoadipate pathway. Enzymatic assay using cell-free crude extract revealed catechol 1,2-dioxygenase activity while no catechol 2,3-dioxygenase activity was detected, supporting this suggestion. The genomic sequence data provide information on gene candidates responsible for phenol and catechol degradation by indigenous Antarctic bacteria and contribute to knowledge of microbial aromatic metabolism and genetic biodiversity in Antarctica.
    Matched MeSH terms: Cold Temperature
  7. Fulltext Storage Stability Assessment of Red Palm Olein in Comparison to Palm Olein
    Loganathan R, Tarmizi AHA, Vethakkan SR, Teng KT
    J Oleo Sci, 2020 Oct 07;69(10):1163-1179.
    PMID: 32908089 DOI: 10.5650/jos.ess20036
    Sixty-four bottles of red palm olein and palm olein (constituted as control) samples were stored at permutations of common home setting variables which are: temperature (room temperature (24°C) or 8°C), light (kept in dark or exposure under light) and oxygen (opened or sealed caps). The effects of temperature, oxygen and light on the stability of red palm olein and palm olein were studied over 4 months of storage at simulated domestic conditions. The degree of auto- and photo-oxidations was evaluated by monitoring the following quality parameters: acidity, peroxide and p-anisidine values, fatty acids composition, carotenes and vitamin E. It is noted from the study that opened bottles of red palm olein was found to be stable for 4 months in comparison to its counterpart (palm olein) evidenced from their primary oxidative constituents (peroxides) and hydrolytic behavior (free fatty acids). Opened bottles are better off when stored at 8°C and protected from light for a longer shelf-life. Sealed bottles of palm olein showed better storage stability in the dark at 8°C; whereas sealed bottles of red palm olein was found to be stable at both temperatures studied without the influence of light. After 4 months of varying storage conditions, the fatty acid composition, vitamin E and carotenes of both oils remained unchanged. The phytonutrients in red palm olein rendered better storage stability when compared to palm olein.
    Matched MeSH terms: Cold Temperature*
  8. 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
  9. Low-temperature and long-time heating regimes on non-volatile compound and taste traits of beef assessed by the electronic tongue system
    Ismail I, Hwang YH, Joo ST
    Food Chem, 2020 Aug 01;320:126656.
    PMID: 32224424 DOI: 10.1016/j.foodchem.2020.126656
    The influence of temperature-time combinations on non-volatile compound and taste traits of beef semitendinosus muscles tested by the electronic tongue was studied. Single-stage sous-vide at 60 and 70 °C (6 and 12 h), and two-stage sous-vide that sequentially cooked at 45 °C (3 h) and 60 °C (either 3 or 9 h) were compared with traditional cooking at 70 °C (30 min). Umami was better explained in the given model of partial least squares regression than astringency, sourness, saltiness, bitterness, and richness. Sous-vide at 70 °C for 12 h characterized the most umami, likely adenosine-5'-monophosphate (AMP) and guanosine-5'-monophosphate (GMP) as significant contributors. Two-stage sous-vide projected higher histidine, leucine, inosine, and hypoxanthine with the astringent and sour taste significant after 6 and 12 h cooking, respectively. Equivalent umami concentration (EUC) between umami amino acids and umami nucleotides showed a strong relationship to umami taste assessed by the electronic tongue.
    Matched MeSH terms: Cold Temperature
  10. Fulltext Cryobiopsy in the diagnosis of bronchiolitis: a retrospective analysis of twenty-three consecutive patients
    Sirol Aflah Syazatul S, Piciucchi S, Tomassetti S, Ravaglia C, Dubini A, Poletti V
    Sci Rep, 2020 07 02;10(1):10906.
    PMID: 32616807 DOI: 10.1038/s41598-020-67938-y
    Bronchiolitis manifests as a variety of histological features that explain the complex clinical profiles and imaging aspects. In the period between January 2011 and June 2015, patients with a cryobiopsy diagnosis of bronchiolitis were retrospectively retrieved from the database of our institution. Clinical profiles, imaging features and histologic diagnoses were analysed to identify the role of cryobiopsy in the diagnostic process. Twenty-three patients with a multidisciplinary diagnosis of small airway disease were retrieved (14 females, 9 males; age range 31-74 years old; mean age 54.2 years old). The final MDT diagnoses were post-infectious bronchiolitis (n = 5), constrictive bronchiolitis (n = 3), DIPNECH (n = 1), idiopathic follicular bronchiolitis (n = 3), Sjogren's disease (n = 1), GLILD (n = 1), smoking-related interstitial lung disease (n = 6), sarcoid with granulomatous bronchiolar disorder (n = 1), and subacute hypersensitivity pneumonitis (n = 2). Complications reported after the cryobiopsy procedure consisted of two cases of pneumothorax soon after the biopsy (8.7%), which were successfully managed with the insertion of a chest tube. Transbronchial cryobiopsy represents a robust and mini-invasive method in the characterization of small airway diseases, allowing a low percentage of complications and good diagnostic confidence.
    Matched MeSH terms: Cold Temperature
  11. Fulltext Experimental Investigation and Performance Evaluation of Modified Viscoelastic Surfactant (VES) as a New Thickening Fracturing Fluid
    Chieng ZH, Mohyaldinn ME, Hassan AM, Bruining H
    Polymers (Basel), 2020 Jun 30;12(7).
    PMID: 32629958 DOI: 10.3390/polym12071470
    In hydraulic fracturing, fracturing fluids are used to create fractures in a hydrocarbon reservoir throughout transported proppant into the fractures. The application of many fields proves that conventional fracturing fluid has the disadvantages of residue(s), which causes serious clogging of the reservoir's formations and, thus, leads to reduce the permeability in these hydrocarbon reservoirs. The development of clean (and cost-effective) fracturing fluid is a main driver of the hydraulic fracturing process. Presently, viscoelastic surfactant (VES)-fluid is one of the most widely used fracturing fluids in the hydraulic fracturing development of unconventional reservoirs, due to its non-residue(s) characteristics. However, conventional single-chain VES-fluid has a low temperature and shear resistance. In this study, two modified VES-fluid are developed as new thickening fracturing fluids, which consist of more single-chain coupled by hydrotropes (i.e., ionic organic salts) through non-covalent interaction. This new development is achieved by the formulation of mixing long chain cationic surfactant cetyltrimethylammonium bromide (CTAB) with organic acids, which are citric acid (CA) and maleic acid (MA) at a molar ratio of (3:1) and (2:1), respectively. As an innovative approach CTAB and CA are combined to obtain a solution (i.e., CTAB-based VES-fluid) with optimal properties for fracturing and this behaviour of the CTAB-based VES-fluid is experimentally corroborated. A rheometer was used to evaluate the visco-elasticity and shear rate & temperature resistance, while sand-carrying suspension capability was investigated by measuring the settling velocity of the transported proppant in the fluid. Moreover, the gel breaking capability was investigated by determining the viscosity of broken VES-fluid after mixing with ethanol, and the degree of core damage (i.e., permeability performance) caused by VES-fluid was evaluated while using core-flooding test. The experimental results show that, at pH-value ( 6.17 ), 30 (mM) VES-fluid (i.e., CTAB-CA) possesses the highest visco-elasticity as the apparent viscosity at zero shear-rate reached nearly to 10 6 (mPa·s). Moreover, the apparent viscosity of the 30 (mM) CTAB-CA VES-fluid remains 60 (mPa·s) at (90 ∘ C) and 170 (s - 1 ) after shearing for 2-h, indicating that CTAB-CA fluid has excellent temperature and shear resistance. Furthermore, excellent sand suspension and gel breaking ability of 30 (mM) CTAB-CA VES-fluid at 90 ( ∘ C) was shown; as the sand suspension velocity is 1.67 (mm/s) and complete gel breaking was achieved within 2 h after mixing with the ethanol at the ratio of 10:1. The core flooding experiments indicate that the core damage rate caused by the CTAB-CA VES-fluid is ( 7.99 % ), which indicate that it does not cause much damage. Based on the experimental results, it is expected that CTAB-CA VES-fluid under high-temperature will make the proposed new VES-fluid an attractive thickening fracturing fluid.
    Matched MeSH terms: Cold Temperature
  12. 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
  13. Fulltext Influence of Temperature Reaction for the CdSe-TiO2 Nanotube Thin Film Formation via Chemical Bath Deposition in Improving the Photoelectrochemical Activity
    Lai CW, Samsudin NA, Low FW, Abd Samad NA, Lau KS, Chou PM, et al.
    Materials (Basel), 2020 Jun 03;13(11).
    PMID: 32503128 DOI: 10.3390/ma13112533
    In this present work, we report the deposition of cadmium selenide (CdSe) particles on titanium dioxide (TiO2) nanotube thin films, using the chemical bath deposition (CBD) method at low deposition temperatures ranging from 20 to 60 °C. The deposition temperature had an influence on the overall CdSe-TiO2 nanotube thin film morphologies, chemical composition, phase transition, and optical properties, which, in turn, influenced the photoelectrochemical performance of the samples that were investigated. All samples showed the presence of CdSe particles in the TiO2 nanotube thin film lattice structures with the cubic phase CdSe compound. The amount of CdSe loading on the TiO2 nanotube thin films were increased and tended to form agglomerates as a function of deposition temperature. Interestingly, a significant enhancement in photocurrent density was observed for the CdSe-TiO2 nanotube thin films deposited at 20 °C with a photocurrent density of 1.70 mA cm-2, which was 17% higher than the bare TiO2 nanotube thin films. This sample showed a clear surface morphology without any clogged nanotubes, leading to better ion diffusion, and, thus, an enhanced photocurrent density. Despite having the least CdSe loading on the TiO2 nanotube thin films, the CdSe-TiO2 nanotube thin films deposited at 20 °C showed the highest photocurrent density, which confirmed that a small amount of CdSe is enough to enhance the photoelectrochemical performance of the sample.
    Matched MeSH terms: Cold Temperature
  14. Fulltext Late-spring frost risk between 1959 and 2017 decreased in North America but increased in Europe and Asia
    Zohner CM, Mo L, Renner SS, Svenning JC, Vitasse Y, Benito BM, et al.
    Proc Natl Acad Sci U S A, 2020 06 02;117(22):12192-12200.
    PMID: 32393624 DOI: 10.1073/pnas.1920816117
    Late-spring frosts (LSFs) affect the performance of plants and animals across the world's temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resistance strategies of Northern Hemisphere woody species to infer trees' adaptations for minimizing frost damage to their leaves and to forecast forest vulnerability under the ongoing changes in frost frequencies. Trait values on leaf-out and leaf-freezing resistance come from up to 1,500 temperate and boreal woody species cultivated in common gardens. We find that areas in which LSFs are common, such as eastern North America, harbor tree species with cautious (late-leafing) leaf-out strategies. Areas in which LSFs used to be unlikely, such as broad-leaved forests and shrublands in Europe and Asia, instead harbor opportunistic tree species (quickly reacting to warming air temperatures). LSFs in the latter regions are currently increasing, and given species' innate resistance strategies, we estimate that ∼35% of the European and ∼26% of the Asian temperate forest area, but only ∼10% of the North American, will experience increasing late-frost damage in the future. Our findings reveal region-specific changes in the spring-frost risk that can inform decision-making in land management, forestry, agriculture, and insurance policy.
    Matched MeSH terms: Cold Temperature*
  15. Fulltext Browning metabolism and quality of fresh-cut drumstick (Moringa oleifera) as influenced by acidulant treatments
    Siddiqui MW, Homa F, Nayyer MA, Ghatak A, Yousuf B, Aftab MA, et al.
    J Food Sci Technol, 2020 Jun;57(6):2010-2016.
    PMID: 32431327 DOI: 10.1007/s13197-019-04233-3
    Though fresh-cut products save our time, but they are very much prone to enzymatic browning that drastically affects product's quality and marketability. Drumstick pods are considered as super food due to high nutritional contents. However, the fresh-cut pods are prone to brown discoloration. The enzyme activities promote the softening and cut-surface browning of pods, thus deteriorates their texture, decreases consumer appeal and shortens the shelf life. So, we aimed to assess the effect of citric (1%) and ascorbic (1%) acid treatments on quality attributes of fresh-cut drumsticks at 3-d interval during storage (5 ± 1 °C). In general there was an increase in lignin and quinone contents, while phenolic content was decreased during storage. However, samples subjected to ascorbic acid dip had higher phenolic content, lower rate of lignin formation, and reduced membrane permeability. Enzyme activities (polyphenol oxidase and peroxidase) were found to increase during storage, however, samples treated with ascorbic acid showed lower activities than that of the control and citric acid treated samples. The reduced enzyme activities resulted in the reduced browning incidence and maintained the quality. Therefore, postharvest dip of fresh-cut drumstick in to ascorbic acid (1%) could be suggested to increase the shelf life with reduced browning during low temperature storage.
    Matched MeSH terms: Cold Temperature
  16. Prevalence of Acute Myocardial Infarction and Changing Meteorological Conditions in Iran: Fuzzy Clustering Approach
    Sharif Nia H, Gorgulu O, Pahlevan Sharif S, Froelicher ES, Haghdoost AA, Golshani S, et al.
    Iran J Public Health, 2020 May;49(5):923-930.
    PMID: 32953680
    Background: The prevalence of Acute Myocardial Infarction (AMI) varies from region to region caused by seasonal climate changes and temperature variation. This study aimed to assess the relationship between changing meteorological conditions and incidence of AMI in Iran.

    Methods: This retrospective prevalence study was based on medical records of the heart center of Mazandaran Province on all patients diagnosed with AMI in Mazandaran, northern Iran between 2013 and 2015. Patients' sex and the day, month, year and time of hospital admission were extracted from patients' records. Moreover, the meteorological reports were gathered.

    Results: A statistically significant difference was found between the distributions of AMI cases across 12 months of the year (P < 0.01). Fuzzy clustering analysis using 16 different climatic variables showed that March, April, and May were in the same cluster together. The other 9 months were in different clusters.

    Conclusion: Significant increase in AMI was seen in March, April and May (cold to hot weather).

    Matched MeSH terms: Cold Temperature
  17. 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
  18. Fulltext Effect of Lignin Modification on Properties of Kenaf Core Fiber Reinforced Poly(Butylene Succinate) Biocomposites
    Ahmad Saffian H, Hyun-Joong K, Md Tahir P, Ibrahim NA, Lee SH, Lee CH
    Materials (Basel), 2019 Dec 05;12(24).
    PMID: 31817323 DOI: 10.3390/ma12244043
    In this study, the effects of lignin modification on the properties of kenaf core fiber reinforced poly(butylene succinate) biocomposites were examined. A weight percent gain (WPG) value of 30.21% was recorded after the lignin were modified with maleic anhydride. Lower mechanical properties were observed for lignin composites because of incompatible bonding between the hydrophobic matrix and the hydrophilic lignin. Modified lignin (ML) was found to have a better interfacial bonding, since maleic anhydrides remove most of the hydrophilic hydrogen bonding (this was proven by a Fourier-transform infrared (FTIR) spectrometer-a reduction of broadband near 3400 cm-1, corresponding to the -OH stretching vibration of hydroxyl groups for the ML samples). On the other hand, ML was found to have a slightly lower glass transition temperature, Tg, since reactions with maleic anhydride destroy most of the intra- and inter-molecular hydrogen bonds, resulting in a softer structure at elevated temperatures. The addition of kraft lignin was found to increase the thermal stability of the PBS polymer composites, while modified kraft lignin showed higher thermal stability than pure kraft lignin and possessed delayed onset thermal degradation temperature.
    Matched MeSH terms: Cold Temperature
  19. Fulltext The effects of temperature and shading on mortality and development rates of Aedes aegypti (Diptera: Culicidae)
    Sukiato F, Wasserman RJ, Foo SC, Wilson RF, Cuthbert RN
    J Vector Ecol, 2019 12;44(2):264-270.
    PMID: 31729799 DOI: 10.1111/jvec.12358
    Urbanization has caused an increase in favorable habitats for Aedes aegypti (Diptera: Culicidae), given their ability to reproduce in small and often non-degradable artificial water-containers. While much work has been done on Ae. aegypti biology and ecology in urban landscapes, the role of shading on immature stages as an independent factor from temperature, and any possible interactions between these factors, remains unexamined. We assessed how temperature and shading affected egg hatch-rate, larval/pupal mortality, and larval development to adult stage under different factorial temperature (28; 31; 34; 37; 40° C) and shade (0%, 3,100 lux; 40%, 1,860 lux; 75%, 775 lux; 100%, 0 lux) regimes. Hatch-rate was significantly lower at 37° C (57 %), and no eggs hatched at 40° C. There was no significant effect caused by shading on hatchability. Larval and pupal mortality at 37° C was significantly higher (35%) compared to lower temperature groups, while the effects of shading were emergent at low temperatures. Developmental times from hatching to adult emergence were significantly reduced with increasing temperatures and with greater light exposures. The eco-physiological response of Ae. aegypti larvae to temperature and light regimes suggest a photosensitivity previously unstudied in this species.
    Matched MeSH terms: Cold Temperature
  20. Fulltext Performance of Fly Ash Geopolymer Concrete Incorporating Bamboo Ash at Elevated Temperature
    Ishak S, Lee HS, Singh JK, Ariffin MAM, Lim NHAS, Yang HM
    Materials (Basel), 2019 Oct 17;12(20).
    PMID: 31627479 DOI: 10.3390/ma12203404
    This paper presents the experimental results on the behavior of fly ash geopolymer concrete incorporating bamboo ash on the desired temperature (200 °C to 800 °C). Different amounts of bamboo ash were investigated and fly ash geopolymer concrete was considered as the control sample. The geopolymer was synthesized with sodium hydroxide and sodium silicate solutions. Ultrasonic pulse velocity, weight loss, and residual compressive strength were determined, and all samples were tested with two different cooling approaches i.e., an air-cooling (AC) and water-cooling (WC) regime. Results from these tests show that with the addition of 5% bamboo ash in fly ash, geopolymer exhibited a 5 MPa (53%) and 5.65 MPa (66%) improvement in residual strength, as well as 940 m/s (76%) and 727 m/s (53%) greater ultrasonic pulse velocity in AC and WC, respectively, at 800 °C when compared with control samples. Thus, bamboo ash can be one of the alternatives to geopolymer concrete when it faces exposure to high temperatures.
    Matched MeSH terms: Cold Temperature
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