The purpose of this study was to investigate ethnic differences in cutaneous thermal sensation thresholds and the inter-threshold sensory zone between tropical (Malaysians) and temperate natives (Japanese). The results showed that (1) Malaysian males perceived warmth on the forehead at a higher skin temperature (Tsk) than Japanese males (p<0.05), whereas cool sensations on the hand and foot were perceived at a lower Tsk in Malaysians (p<0.05); (2) Overall, the sensitivity to detect warmth was greater in Japanese than in Malaysian males; (3) The most thermally sensitive body region of Japanese was the forehead for both warming and cooling, while the regional thermal sensitivity of Malaysians had a smaller differential than that of Japanese; (4) The ethnic difference in the inter-threshold sensory zone was particularly noticeable on the forehead (1.9±1.2C for Japanese, 3.2±1.6°C for Malaysians, p<0.05). In conclusion, tropical natives had a tendency to perceive warmth at a higher Tsk and slower at an identical speed of warming, and had a wider range of the inter-threshold sensory zone than temperate natives.
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.
Seeds of two selected clones of Artemisia annua L., TC1 and TC2, were germinated in a greenhouse. Four-week-old seedlings from both clones were grown in the Thù Đúc province of Ho Chi Minh City on 2(nd) January 2009 and Đà Lat on 20(th) January 2009. During this study period in Thù Đúc province, which is situated 4-5 m above sea level, was experiencing a tropical, dry season with temperatures ranging from 26.2°C-32.8°C. Đà Lat, situated at 1500-2000 m above sea level, was having temperate, dry season with lower temperatures, ranging from 10.5°C-18.0°C. The high temperatures and low elevation in Thù Đúc Province led to slow vegetative growth for all of the plants from the two different clones and the artemisinin contents were significantly reduced. The temperate environment of Đà Lat supported robustly growing plants, with plant heights and branch lengths 4-5 times taller and longer that those planted at Thù Đúc Province. The artemisinin contents of A. annua planted at Đà Lat were 3-4 times greater than those cultivated at Thù Đúc Province. Hence, this study indicated that the variations observed in plant growth and artemisinin contents were due to temperature effects because the two selected clones were genetically homogenous. The cold weather of Đà Lat was suitable for planting of A. annua as opposed to the tropical weather of Thù Đúc Province.
The influence of the cool and warm temperatures on early life development and
survival of tropical oyster, Crassostrea iredalei was studied. D-hinged larvae (day 1 larvae)
were reared to three different temperatures (20°C, 27°C, and 34°C) for nine days. Oyster
larvae reared in temperature 27°C, acted as control (ambient temperature). The highest
survival rate occurred when the larvae were reared in 20°C and 27°C. Larvae reared at
34°C exhibited reduced survival but increase in the growth rate. The growth rate in larvae
reared in high temperature (34°C) was significantly higher compared to larvae reared in
20°C and 27°C (p
General flowering (GF) is a unique phenomenon wherein, at irregular intervals, taxonomically diverse trees in Southeast Asian dipterocarp forests synchronize their reproduction at the community level. Triggers of GF, including drought and low minimum temperatures a few months previously has been limitedly observed across large regional scales due to lack of meteorological stations. Here, we aim to identify the climatic conditions that trigger large-scale GF in Peninsular Malaysia using satellite sensors, Tropical Rainfall Measuring Mission (TRMM) and Moderate Resolution Imaging Spectroradiometer (MODIS), to evaluate the climatic conditions of focal forests. We observed antecedent drought, low temperature and high photosynthetic radiation conditions before large-scale GF events, suggesting that large-scale GF events could be triggered by these factors. In contrast, we found higher-magnitude GF in forests where lower precipitation preceded large-scale GF events. GF magnitude was also negatively influenced by land surface temperature (LST) for a large-scale GF event. Therefore, we suggest that spatial extent of drought may be related to that of GF forests, and that the spatial pattern of LST may be related to that of GF occurrence. With significant new findings and other results that were consistent with previous research we clarified complicated environmental correlates with the GF phenomenon.
Iran is situated in a very diverse environmental area. The climate of the region is varied and influencedby different patterns. In order to best describe the expected climate change impacts for the region,climate change scenarios and climate variables must be developed on a regional, or even site-specific,scale. The weather generator is one of the valid downscaling methods. In the current study, LARSWG(a weather generator) and the outputs from ECHO-G for present climate, as well as future timeslice of 2010-2039 based on A1 scenario, were used to evaluate LARS-WG as a tool at 13 synopticstations located in the north and northeast parts of Iran. The results obtained in this study illustratethat LARS-WG has a reasonable capability of simulating the minimum and maximum temperaturesand precipitation. In addition, the results showed that the mean precipitation decreased in Semnan, thesouth of Khorasan and Golestan. Meanwhile, the mean temperature during 2010-2039 would increaseby 0.5°C, especially in the cold season.
Refined bleached and deodorized palm oil (RBDPO) was crystallized from the melt in a thermally controlled water bath at 14 and 22°C for 90 min. Slurries were withdrawn after 5, 15, 30, 60 and 90 min of crystallization for crystal morphology studies. Crystallization was also performed in a similar manner using a Labmax reactor connected to a FBRM detector to obtain the information on crystal count and size distribution during crystallization. Based on the shape of the crystals viewed under the microscope, all crystals appeared as needle shaped spherulitic β´- form at both crystallization temperatures studied. Crystals were slightly larger with increase in crystallization time and at higher crystallization temperature (22°C). Crystals size range between 4.34 to 22.29µm. FBRM recorded high count of crystals with increased in crystallization time and at lower temperature (14°C).
Changes in nitrate and nitrite contents (leaves and stem) of Amaranthus gangeticus (AG) and Amaranthus paniculatus (AP), resulting from blanching, storage time (0-4 days), storage temperature (0 and 4ºC), and reheating were analysed. Results showed that fresh AG (1859 ± 7.07 mg/kg) had higher nitrite content than AP (1262 ± 2.12 mg/kg). Nitrites content was 506 ± 2 and 825 ± 3.5 mg/kg for AG and AP, respectively. Reheating and storage times significantly increased the conversion of nitrate to nitrite in AG and AP. Storage at 0 and 4oC exhibited a significant change (P < 0.05) in nitrate and nitrite contents for both samples. Higher nitrite content was found in AP when stored at 4oC and 0oC. The present study indicated that storage time and temperature affected the nitrite contents in blanched AG and AP when stored in low temperatures. Apart from that reheating was also found to increase the formation of nitrite.
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.
This paper looks at electrical power generation from solar concentrator using thermoelectric generator. An experiment was conducted on a concentrator thermoelectric generator (CTEG) utilising solar thermal energy. The CTEG used a parabolic dish as concentrator with thermoelectric device installed at the focal point to convert thermal energy to generate electricity. The investigation covered the cooling effect of the cold side of the thermoelectric generator using natural and forced convection cooling for optimum output. Forced convection cooling with a fan provided 69% more power output from the CTEG system as the temperature difference across the TEG was greater than the system cooled by natural convection. The outcome of this project showed maximum power output was obtained for the CTEG system cooled by forced convection cooling.
In recent years, injection moulding process is one of the most advanced and efficient manufacturing processes for mass production of plastic bottles. However, a good quality of parison is difficult to achieve due to uncontrollable humidity, pressure inlet and water inlet velocity. This paper investigates the effect of using multiple mould cavities to improve the process fill time and injection pressure in the production of PET plastic bottles using MoldFlow software. The modelling of parison was developed using CATIA with the consideration of every part of the parison. MoldFlow software was used to analyse the flow of 20 g parison with different cavity numbers (1, 8, 16, 24 cavity), as well as its corresponding runner size towards its fill time and injection pressure. Other important parameters that affect the production of parison, such as melting temperature, mould temperature, atmospheric temperature and cooling time, were remained constant. The fill time required to produce 24 moulds was improved by 60% compared to using 8 mould cavity only, and this enable the production of more plastic bottles in a day. Therefore, fill time and injection pressure are two important parameters to be considered in the injection moulding process, especially to reduce parison defect and increase its production rate.
A good temperature management, such as precooling and cold storage, can delay deterioration of fresh produce. In this study, different forced-air precooling times were applied on Musa AAA Berangan to investigate the influence of forced-air precooling time on the changes of quality attributes and consumer acceptance. The banana was subjected to forced-air precooling treatment (5 ± 1°C) for 0, 14, 50, and 120 min and then stored in a cold room (13 ± 1°C) for 2 weeks. Then, all the fruits were transferred to a ripening room (25 ± 2°C) and initiated to ripen with ethylene gas. Quality attributes analyses and sensory evaluations were conducted when the fruits reached maturity index 5. Quality parameters, such as soluble solids concentration, titratable acidity, pulp firmness, and peel colour, showed no significant differences when fruits were precooled at different times. Blackening of peel as a result of chilling injury occurred in fruits treated with forced-air precooling for 50 and 120 min. This blackening significantly influenced consumer acceptance, although it did not affect the pulp colour and taste.
The electrical resistivity of Mg0.6Zn0.4Fe2O4 ferrite was measured as a function of temperature in the range 300-630 K. Two anomalies are observed in the resistivity curves for measurements during heating up. These anomalies are identified as a magnetic anomaly at the Neel temperature, TN = 598 K, while the other one at TOt = 445 K is discussed as due to the contribution of conduction from the tetrahedral sites. The anomaly at Tot was reduced in the measurements during recooling, while the anomaly at TN was disappeared completely during recooling and second cycle. These effects are discussed as due to the increase of Fe2+ ions at the octahedral sites as a result of cation redistribution at higher temperatures. A relatively small anomaly at Tot still can be observed during the second run. This is possible if the Fe2+ ions have a preference to be relocated at the tetrahedral sites at lower temperatures.
Kerintangan elektrik Mg0.6Zn0.4Fe2O4 ferit telah diukur sebagai fungsi suhu dalam julat 300 - 630 K. Dua anomali dapat dicerap pada lengkung kerintangan bagi pengukuran semasa pemanasan. Dua anomali tersebut dikenalpasti sebagai anomali magnet pada suhu Neel, TN = 598 K, manakala yang satu lagi pada Tot = 445 K dibincangkan sebagai berpunca daripada sumbangan kekonduksian pada tapak tetrahedron. Anomali pada Tot mengurang dalam pengukuran semasa penyejukan semula pada julat suhu yang sarna, manakala anomali pada TN terus lenyap dalam pengukuran semasa penyejukan semula dan juga semasa kitar kedua. Kesan ini dibincangkan sebagai disebabkan oleh peningkatan ion Fe2+ pada tapak oktahedron daripada proses taburan semula kation pada suhu tinggi. Anomali yang berkurang pada Tot masih boleh dicerap semasa pengukuran kitar kedua. Keadaan seperti ini adalah mungkin jika ion Fe2+ mempunyai kecenderongan untuk bertempat semula pada tapak tetrahedron apabila suhu menurun.
This paper delves into the problem of mixed convection boundary layer flow from a horizontal circular cylinder filled in
a Jeffrey fluid with viscous dissipation effect. Both cases of cooled and heated cylinders are discussed. The governing
equations which have been converted into a dimensionless form using the appropriate non-dimensional variables are solved
numerically through the Keller-box method. A comparative study is performed and authentication of the present results
with documented outcomes from formerly published works is excellently achieved. Tabular and graphical representations
of the numerical results are executed for the specified distributions, considering the mixed convection parameter, Jeffrey
fluid parameters and the Prandtl and Eckert numbers. Interestingly, boundary layer separation for mixed convection
parameter happens for some positive (assisting flow) and negative (opposing flow) values. Strong assisting flow means
the cylinder is heated, which causes the delay in boundary layer separation, whereas strong opposing flow means the
cylinder is cooled, which conveys the separation point close to the lower stagnation point. Contradictory behaviours
of both Jeffrey fluid parameters are observed over the velocity and temperature profiles together with the skin friction
coefficient and Nusselt number. The increase of the Prandtl number leads to the decrement of the temperature profile,
while the increase of the Eckert number results in the slight increment of the skin friction coefficient and decrement of
the Nusselt number. Both velocity and temperature profiles of Eckert number show no effects at the lower stagnation
point of the cylinder.
The mechanical properties of fractured rock mass are largely dependent on the fracture structure under the coupling of freeze-thaw cycles and large temperature difference. Based on the traditional macroscopic continuum theory, the thermal and mechanical model and the corresponding theories ignore the material internal structure characteristics, which add difficulty in describing the mesoscopic thermal and mechanical behavior of the fractured rock mass among different phases. In order to uncover the inherent relationship and laws among the internal crack development, structural change and the physical and mechanical properties of rock under strong cold and frost weathering in cold area, typical granite and sandstone in cold region were analyzed in laboratory tests. The SEM scanning technology was introduced to record the microstructural change of rock samples subject to freeze-thaw cycles and large temperature difference. Association rules between the microstructure and the physical mechanical properties of rock mass were analyzed. The results indicated that, with the increase of the cyclic number, the macroscopic physical and mechanical indexes and the microscopic fracture index of granite and sandstone continuously and gradually deteriorate. The width of original micro crack continues to expand and extend and new local micro cracks are generated and continue to expand. The fracture area and width of the rock increase and the strength of the rock is continuously damaged. In particular, the strength and elastic modulus of granite decrease by 20.2% and 33.36%, respectively; the strength and elastic modulus of sandstone decrease by 33.4% and 36.43%, respectively.
The mechanical properties of Dual Phase Steel (DPS)-duplex structure-produced by quenching in pre-heated bitumen have been investigated. Medium carbon steels intercritically heated at different temperatures and holding times were quenched in hot bitumen. Optical and scanning electron microscopy characterisation of the duplex structure showed extensive network of fibrous martensite in a ferritic matrix with occasional presence of polygonal martensite. The duplex phase structure exhibited continuous yielding dynamics, improving the tensile and hardness values by about 42 and 35%, respectively, relative to the normalised structure. But, the elongation and impact values decreased by about 42 and 50%, respectively, when compared to the normalised structure. These values are similar to those obtained in duplex structure produced using conventional oil quenching. The tensile fractured surface showed transition between a predominantly cleavage mode in the lower annealing temperature to a mixed mode in the upper bound of the annealing temperature. These findings suggest that pre-heated bitumen can be exploited for the production of DPSs.
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.
Chilling restrains the distribution of mangroves. We tested whether foliar phosphorus (P) fractions and gene expression are associated with cold tolerance in mangrove species. We exposed seedlings of six mangrove populations from different latitudes to favorable, chilling and recovery treatments, and measured their foliar P concentrations and fractions, photochemistry, nighttime respiration, and gene expression. A Kandelia obovata (KO; 26.45°N) population completely and a Bruguiera gymnorhiza (Guangxi) (BGG; 21.50°N) population partially (30%) survived chilling. Avicennia marina (24.29°N), and other B. gymnorhiza (26.66°N, 24.40°N, and 19.62°N) populations died after chilling. Photosystems of KO and photosystem I of BGG were least injured. During chilling, leaf P fractions, except nucleic acid P in three populations, declined and photoinhibition and nighttime respiration increased in all populations, with the greatest impact in B. gymnorhiza. Leaf nucleic acid P was positively correlated with photochemical efficiency during recovery and nighttime respiration across populations for each treatment. Relatively high concentrations of nucleic acid P and metabolite P were associated with stronger chilling tolerance in KO. Bruguiera gymnorhiza exhibited relatively low concentrations of organic P in favorable and chilling conditions, but its partially survived population showed stronger compensation in nucleic acid P and Pi concentrations and gene expression during recovery.
Low-temperature growth, as well as the transfer free growth on substrates, is the major concern of graphene research for its practical applications. Here we propose a simple method to achieve the transfer free graphene growth on SiO2 covered Si (SiO2/Si) substrate at 250 °C based on a solid-liquid-solid reaction. The key to this approach is the catalyst metal, which is not popular for graphene growth by chemical vapor deposition. A catalyst metal film of 500 nm thick was deposited onto an amorphous C (50 nm thick) coated SiO2/Si substrate. The sample was then annealed at 250 °C under vacuum condition. Raman spectra measured after the removal of the catalyst by chemical etching showed intense G and 2D peaks together with a small D and intense SiO2 related peaks, confirming the transfer free growth of multilayer graphene on SiO2/Si. The domain size of the graphene confirmed by optical microscope and atomic force microscope was about 5 μm in an average. Thus, this approach will open up a new route for transfer free graphene growth at low temperatures.
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%.