Renewable solar energy is the key target to reduce fossil fuel consumption, minimize global warming issues, and indirectly minimizes erratic weather patterns. Herein, the authors synthesized an ultrathin reduced graphene oxide (rGO) nanosheet with ~47 nm via an improved Hummer's method. The TiO2 was deposited by RF sputtering onto an rGO nanosheet with a variation of temperature to enhance the photogenerated electron or charge carrier mobility transport for the photoanode component. The morphology, topologies, element composition, crystallinity as well as dye-sensitized solar cells' (DSSCs) performance were determined accordingly. Based on the results, FTIR spectra revealed presence of Ti-O-C bonds in every rGO-TiO2 nanocomposite samples at 800 cm-1. Besides, XRD revealed that a broad peak of anatase TiO2 was detected at ~25.4° after incorporation with the rGO. Furthermore, it was discovered that sputtering temperature of 120 °C created a desired power conversion energy (PCE) of 7.27% based on the J-V plot. Further increase of the sputtering temperature to 160 °C and 200 °C led to excessive TiO2 growth on the rGO nanosheet, thus resulting in undesirable charge recombination formed at the photoanode in the DSSC device.
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.
In recent years, studies on psychrophilic lipases have been an emerging area of research in the field of enzymology. This study focuses on bacterial strains isolated from anthropogenically-influenced soil samples collected around Signy Island Research Station (South Orkney Islands, maritime Antarctic). Limited information on lipase activities from bacteria isolated from Signy station is currently available. The presence of lipase genes was determined using real time quantification PCR (qPCR) in samples obtained from three different locations on Signy Island. Twenty strains from the location with highest lipase gene detection were screened for lipolytic activities at a temperature of 4 °C, and from this one strain was selected for further examination based on the highest enzymatic activities obtained. Analysis of 16S rRNA sequence data of this strain showed the highest level of sequence similarity (98%) to a Pseudomonas sp. strain also isolated from Antarctica. In order to increase lipase production of this psychrophilic strain, optimisation of different parameters of physical and nutritional factors were investigated. Optimal production was obtained at 10 °C and pH 7.0, at 150 rev/min shaking rate over 36 h incubation.
Dielectric spectroscopy is employed to study the relaxation phenomena in natural polyhydroxyalkanoates (PHAs) upon temperature and frequency variations. Effects of PHAs molecular structure on the relaxation, arising from the differences in monomeric composition, are investigated under identical conditions in a frequency range of 10-2-106 Hz, and at different temperatures. All PHA samples showed different dielectric response at different temperature. Primary α-relaxation signals are observed at temperature corresponding to the glass transition temperature. On the other hand, secondary β- and γ-relaxations are detected at low temperatures, and attributed to local motions of polar groups and small segments of the polymer chain. The dielectric properties of representative PHA samples are compared and discussed.
Matched MeSH terms: Temperature; Transition Temperature
International competition inevitably presents logistical challenges for athletes. Events such as the Tokyo 2020 Olympic Games require further consideration given historical climate data suggest athletes will experience significant heat stress. Given the expected climate, athletes face major challenges to health and performance. With this in mind, heat alleviation strategies should be a fundamental consideration. This review provides a focused perspective of the relevant literature describing how practitioners can structure male and female athlete preparations for performance in hot, humid conditions. Whilst scientific literature commonly describes experimental work, with a primary focus on maximizing magnitudes of adaptive responses, this may sacrifice ecological validity, particularly for athletes whom must balance logistical considerations aligned with integrating environmental preparation around training, tapering and travel plans. Additionally, opportunities for sophisticated interventions may not be possible in the constrained environment of the athlete village or event arenas. This review therefore takes knowledge gained from robust experimental work, interprets it and provides direction on how practitioners/coaches can optimize their athletes' heat alleviation strategies. This review identifies two distinct heat alleviation themes that should be considered to form an individualized strategy for the athlete to enhance thermoregulatory/performance physiology. First, chronic heat alleviation techniques are outlined, these describe interventions such as heat acclimation, which are implemented pre, during and post-training to prepare for the increased heat stress. Second, acute heat alleviation techniques that are implemented immediately prior to, and sometimes during the event are discussed. Abbreviations: CWI: Cold water immersion; HA: Heat acclimation; HR: Heart rate; HSP: Heat shock protein; HWI: Hot water immersion; LTHA: Long-term heat acclimation; MTHA: Medium-term heat acclimation; ODHA: Once-daily heat acclimation; RH: Relative humidity; RPE: Rating of perceived exertion; STHA: Short-term heat acclimation; TCORE: Core temperature; TDHA: Twice-daily heat acclimation; TS: Thermal sensation; TSKIN: Skin temperature; V̇O2max: Maximal oxygen uptake; WGBT: Wet bulb globe temperature.
Adaptation to environmental conditions within the native range of exotic species can condition the invasion success of these species outside their range. The striking success of the Asian tiger mosquito, Aedes albopictus, to invade temperate regions has been attributed to the winter survival of diapause eggs in cold environments. In this study, we evaluate genetic polymorphisms (SNPs) and wing morphometric variation among three biogeographical regions of the native range of A. albopictus. Reconstructed demographic histories of populations show an initial expansion in Southeast Asia and suggest that marine regression during late Pleistocene and climate warming after the last glacial period favored expansion of populations in southern and northern regions, respectively. Searching for genomic signatures of selection, we identified significantly differentiated SNPs among which several are located in or within 20 kb distance from candidate genes for cold adaptation. These genes involve cellular and metabolic processes and several of them have been shown to be differentially expressed under diapausing conditions. The three biogeographical regions also differ for wing size and shape, and wing size increases with latitude supporting Bergmann's rule. Adaptive genetic and morphometric variation observed along the climatic gradient of A. albopictus native range suggests that colonization of northern latitudes promoted adaptation to cold environments prior to its worldwide invasion.
In this study, the effects of thermosonication and thermal treatment on Escherichia coli O157:H7 and Salmonella Enteritidis in mango juice were investigated at 50 and 60°C. Besides, nonlethal injury of Salm. Enteritidis after both treatments was also examined. The highest inactivation was attained with thermosonication at 60°C. The inactivation rate was different for both pathogens, and Salm. Enteritidis was found to be more sensitive to thermosonication than E. coli O157:H7. Salmonella Enteritidis was recovered in all treated samples, except those subjected to more than 5-min thermosonication at 60°C. It was found that the introduction of high-intensity ultrasound enhanced the inactivation of pathogens compared to thermal treatment alone. On the other hand, Salm. Enteritidis was detected in a number of samples following incubation in universal pre-enrichment broth, but no growth was detected after incubation in mango juice.
The effects of global warming are increasingly evident, where global surface temperatures and atmospheric concentration of carbon dioxide have increased in past decades. Given the role of terrestrial bacteria in various ecological functions, it is important to understand how terrestrial bacteria would respond towards higher environmental temperatures. This study aims to determine soil bacterial diversity in the tropics and their response towards in situ warming using an open-top chamber (OTC). OTCs were set up in areas exposed to sunlight throughout the year in the tropical region in Malaysia. Soil samples were collected every 3 months to monitor changes in bacterial diversity using V3-V4 16S rDNA amplicon sequencing inside the OTCs (treatment plots) and outside the OTCs (control plots). After 12 months of simulated warming, an average increase of 0.81 to 1.15 °C was recorded in treatment plots. Significant changes in the relative abundance of bacterial phyla such as Bacteroidetes and Chloroflexi were reported. Increases in the relative abundance of Actinobacteria were also observed in treatment plots after 12 months. Substantial changes were observed at the genus level, where most bacterial genera decreased in relative abundance after 12 months. This study demonstrated that warming can alter soil bacteria in tropical soils from Kota Kinabalu.
Matched MeSH terms: Hot Temperature/adverse effects
Expanded bed adsorption chromatography (EBAC) is a single pass operation that has been used as primary capture step in various protein purifications. The most common problem in EBAC is often associated with successful formation of a stable fluidized bed during the absorption stage, which is critically dependent on parameters such as liquid velocity, bed height, particle (adsorbent) size and density as well as design of column and type of flow distributor. In this study, residence time distribution (RTD) test using acetone as non-binding tracer acetone was performed to evaluate liquid dispersion characteristics of the EBAC system. A high B(o) number was obtained indicating the liquid dispersion in the system employed is very minimal and the liquid flow within the bed was close to plug flow, which mimics a packed bed chromatography system. Evaluation on the effect of flow velocities and bed height on the performance of Streamline DEAE using feedstock containing heat-treated crude Escherichia coli homogenate of different biomass concentrations was carried out in this study. The advantages and disadvantages as well as the problems encountered during recovery of HBcAg with aforementioned parameters are also discussed in this paper.
Heat shock response (HSR), in terms of transcription regulation of two heat shock proteins genes hsp70 and hsp90), was analysed in a widespread tropical copepod Pseudodiaptomus annandalei. The mRNA transcripts of both genes were quantified after copepods at a salinity of 20 underwent an acclimation process involving an initial acclimation temperature of 29 °C, followed by gradual thermal ramping to the target exposure temperature range of 24-36 °C. The respective cellular HSR and organismal metabolism, measured by respiratory activity at exposure temperatures, were compared. The fold change in mRNA expression for both hsp70 and hsp90 (8-9 fold) peaks at 32 °C, which is very close to 32.4 °C, the upper thermal optimum for respiration in the species. Unexpectedly, the modelled HSR curves peak at only 3 °C (hsp90) and 3.5 °C (hsp70) above the mean water temperature (29.32 °C) of the copepod in the field. We propose that copepods in tropical waters adopt a preparative HSR strategy, early at the upper limit of its thermal optimum, due to the narrow thermal range of its habitat thus precluding substantial energy demand at higher temperatures. However, the model suggests that the species could survive to at least 36 °C with short acclimation time. Nevertheless, the significant overlap between its thermal range of hsp synthesis and the narrow temperature range of its habitat also suggests that any unprecedented rise in sea temperature would have a detrimental effect on the species.
Among several animals, Rattus rattus (rat) lives in polluted environments and feeds on organic waste/small invertebrates, suggesting the presence of inherent mechanisms to thwart infections. In this study, we isolated gut bacteria of rats for their antibacterial activities. Using antibacterial assays, the findings showed that the conditioned media from selected bacteria exhibited bactericidal activities against Gram-negative (Escherichia coli K1, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, and Salmonella enterica) and Gram-positive (Bacillus cereus, methicillin-resistant Staphylococcus aureus, and Streptococcus pyogenes) pathogenic bacteria. The conditioned media retained their antibacterial properties upon heat treatment at boiling temperature for 10 min. Using MTT assays, the conditioned media showed minimal cytotoxic effects against human keratinocyte cells. Active conditioned media were subjected to tandem mass spectrometry, and the results showed that conditioned media from Bacillus subtilis produced a large repertoire of surfactin and iturin A (lipopeptides) molecules. To our knowledge, this is the first report of isolation of lipopeptides from bacteria isolated from the rat gut. In short, these findings are important and provide a platform to develop effective antibacterial drugs.
A thermostable bacterial lipase from Geobacillus zalihae was expressed in a novel yeast Pichia sp. strain SO. The preliminary expression was too low and discourages industrial production. This study sought to investigate the optimum conditions for T1 lipase production in Pichia sp. strain SO. Seven medium conditions were investigated and optimized using Response Surface Methodology (RSM). Five responding conditions namely; temperature, inoculum size, incubation time, culture volume and agitation speed observed through Plackett-Burman Design (PBD) method had a significant effect on T1 lipase production. The medium conditions were optimized using Box-Behnken Design (BBD). Investigations reveal that the optimum conditions for T1 lipase production and Biomass concentration (OD600) were; Temperature 31.76 °C, incubation time 39.33 h, culture volume 132.19 mL, inoculum size 3.64%, and agitation speed of 288.2 rpm with a 95% PI low as; 12.41 U/mL and 95% PI high of 13.65 U/mL with an OD600 of; 95% PI low as; 19.62 and 95% PI high as; 22.62 as generated by the software was also validated. These predicted parameters were investigated experimentally and the experimental result for lipase activity observed was 13.72 U/mL with an OD600 of 24.5. At these optimum conditions, there was a 3-fold increase on T1 lipase activity. This study is the first to develop a statistical model for T1 lipase production and biomass concentration in Pichia sp. Strain SO. The optimized production of T1 lipase presents a choice for its industrial application.
3-Monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters (GE) are heat-induced contaminants which form during oil refining process, particularly at the high temperature deodorization stage. It is worth to investigate the content of 3-MCPD and GE in fries which also involved high temperature. The content of 3-MCPD esters and GE were monitored in fries. The factors that been chosen were temperature and duration of frying, and different concentration of salt (NaCl). The results in our study showed that the effect was in the order of concentration of sodium chloride
This study presents a novel tool to predict temperature-exposure of incinerated pig teeth as a proxy for understanding impacts of fire on human teeth. Previous studies on the estimation of temperature-exposure of skeletal elements have been limited to that of heat-exposed bone. This predictive tool was developed using a multinomial regression model of colourimetric and hydroxyapatite crystal size variables using data obtained from unheated pig teeth and teeth incinerated at 300 °C, 600 °C, 800 °C and 1000 °C. An additional variable based on the observed appearance of the tooth was included in the tool. This enables the tooth to be classified as definitely burnt (600 °C-1000 °C) or uncertain (27 °C/300 °C). As a result, the model predicting the temperature-exposure of the incinerated teeth had an accuracy of 95%. This tool is a holistic, robust and reliable approach to estimate temperature of heat-exposed pig teeth, with high accuracy, and may act as a valuable proxy to estimate heat exposure for human teeth in forensic casework.
The method of liquid chromatographic tandem mass spectrometry was utilized and modified to confirm and quantify acrylamide in heating cooking oil and animal fat. Heating asparagine with various cooking oils and animal fat at 180°C produced varying amounts of acrylamide. The acrylamide in the different cooking oils and animal fat using a constant amount of asparagine was measured. Cooking oils were also examined for peroxide, anisidine and iodine values (or oxidation values). A direct correlation was observed between oxidation values and acrylamide formation in different cooking oils. Significantly less acrylamide was produced in saturated animal fat than in unsaturated cooking oil, with 366ng/g in lard and 211ng/g in ghee versus 2447ng/g in soy oil, followed by palm olein with 1442ng/g.
We report a detailed structural analysis of the psychrophilic exo-β-1,3-glucanase (GaExg55) from Glaciozyma antarctica PI12. This study elucidates the structural basis of exo-1,3-β-1,3-glucanase from this psychrophilic yeast. The structural prediction of GaExg55 remains a challenge because of its low sequence identity (37 %). A 3D model was constructed for GaExg55. Threading approach was employed to determine a suitable template and generate optimal target-template alignment for establishing the model using MODELLER9v15. The primary sequence analysis of GaExg55 with other mesophilic exo-1,3-β-glucanases indicated that an increased flexibility conferred to the enzyme by a set of amino acids substitutions in the surface and loop regions of GaExg55, thereby facilitating its structure to cold adaptation. A comparison of GaExg55 with other mesophilic exo-β-1,3-glucanases proposed that the catalytic activity and structural flexibility at cold environment were attained through a reduced amount of hydrogen bonds and salt bridges, as well as an increased exposure of the hydrophobic side chains to the solvent. A molecular dynamics simulation was also performed using GROMACS software to evaluate the stability of the GaExg55 structure at varying low temperatures. The simulation result confirmed the above findings for cold adaptation of the psychrophilic GaExg55. Furthermore, the structural analysis of GaExg55 with large catalytic cleft and wide active site pocket confirmed the high activity of GaExg55 to hydrolyze polysaccharide substrates.
Channa striatus (“haruan”) fish destined for fillet preparation was subjected to two freezing treatments, freezing with distilled water (FW) or freezing directly without distilled water (DF). Fish that was freshly processed without freezing served as control (C). Fillet yield (%) was in the range 33.8% to 35.3% and the highest yield was recorded in FW samples. Whole Fillet Powder (WFP) was prepared from the fillets through low temperature vacuum oven drying (50°C) and its composition and physicochemical properties were assessed. There was no significant difference in moisture and protein contents of all samples (p > 0.05). All WFP were generally dark in colour with whiteness indices ranging from 55.23 - 63.98. The redness (a*) values were 4.33, 11.12, 8.83 whilst the yellowness (b*) were 19.31, 23.04, 21.20 for C, WFP-FW and WFP-DF respectively. WFPs were generally high in histidine, arginine, threonine and tyrosine when compared to egg whites and these (except histidine) and other amino acids (serine, glycine, methionine and phenylalanine) were significantly higher (p < 0.05) in WFP-FW compared to other samples. Overall, freezing treatments affected the composition and physicochemical properties of WFPs.
Isonicotinamide-4-methoxybenzoic acid co-crystal (1), C6H6N2O·C8H8O3, is formed through slow evaporation from methanol solution and it undergoes a first-order isosymmetry (monoclinic I2/a ↔ monoclinic I2/a) structural phase transition at Tc= 142.5 (5) K, which has been confirmed by an abrupt jump of crystallographic interaxial angle β from variable-temperature single-crystal XRD and small heat hysteresis (6.25 K) in differential scanning calorimetry measurement. The three-dimensional X-ray crystal structures of (1) at the low-temperature phase (LTP) (100, 140 and 142 K) and the high-temperature phase (HTP) (143, 150, 200, 250 and 300 K) were solved and refined as a simple non-disordered model with final R[F2> 2σ(F2)] ≃ 0.05. The asymmetric unit of (1) consists of crystallographically independent 4-methoxybenzoic acid (A) and isonicotinamide (B) molecules in both enantiotropic phases. Molecule A adopts a `near-hydroxyl' conformation in which the hydroxyl and methoxy groups are positioned on the same side. Both `near-hydroxyl' and `near-carbonyl' molecular conformations possess minimum conformational energies with an energy difference of
Matched MeSH terms: Temperature; Transition Temperature
This study reports the production of P(3HB-co-4HB) [Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)] in possession of high molecular weight and elastomeric properties by Cupriavidus sp. USMAA1020 in single-stage mixed-substrate cultivation system. 1,4-butanediol and 1,6-hexanediol are found to be efficient substrate mixture that has resulted in high copolymer yield, occupying a maximum of 70wt% of the total biomass and producing higher 4HB monomer composition ranging from 31mol% to 41mol%. In substrate mixtures involving 1,6-hexanediol, cleavage of the 6-hydroxyhexanoyl-CoA produces Acetyl-CoA and 4-hydroxybutyryl-CoA. Acetyl-CoA is instrumental in initiating the cell growth in the single-stage fermentation system, preventing 4-hydroxybutyryl-CoA from being utilized via β-oxidation and retained the 4HB monomer at higher ratios. Macroscopic kinetic models of the bioprocesses have revealed that the P(3HB-co-4HB) formation appears to be in the nature of mixed-growth associated with higher formation rate during exponential growth phase; evidenced by higher growth associated constants, α, from 0.0690g/g to 0.4615g/g compared to non-growth associated constants, β, from 0.0092g/g/h to 0.0459g/g/h. The P(3HB-co-31mol% 4HB) produced from the substrate mixture exhibited high weight-average molecular weight, Mwof 927kDa approaching a million Dalton, and possessed elongation at break of 1637% upon cultivation at 0.56wt% C. This is the first report on such properties for the P(3HB-co-4HB) copolymer. The copolymer is highly resistant to polymer deformation after being stretched.