Spectral characterization of hydroxyapatite extracted from Black Sumatra and Fighting cock bone samples: A comparative analysis

At present, chicken business is occupying a major portion in the market and huge amount of bone wastes are dumped into the open places lead in environmental pollution. In this analysis, natural hydroxyapatite was extracted by thermal calcination process at different temperature ranges from 700 °C, 900 °C and 1100 °C and compared its spectral characteristics. The crystalline nature, functional groups and morphological characteristics of hydroxyapatite obtained from both bone samples were studied using XRD, FTIR and SEM analysis. The crystallite size, lattice parameters, specific surface area, volume and degree of crystallinity were measured using XRD data. The mean grain size of Black Sumatra and Fighting Cock bone hydroxyapatite was 62.67 nm and 31.34 nm respectively. The FTIR spectrum showed major peaks at 634.58 cm⁻¹ and 470.63 cm⁻¹, 1413.82 cm⁻¹ and 1460 cm⁻¹ indicates the presence of carbonate group and phosphate groups in both samples. The SEM micrograph confirmed the existence of maximum pores in matrix of fighting cock bone than Black Sumatra bone sample. Thus, the comparative analysis concluded that nano-sized hydroxyapetite obtained from bone wastes of fighting cock can be utilized as a low-cost biomaterial for the production of various implant coating materials and substitute for ceramics in bones and dentistry applications.     

Systematic Study on the Self-Assembled Hexagonal Au Voids,Nano-Clusters and Nanoparticles on GaN (0001)

Au nano-clusters and nanoparticles (NPs) have been widely utilized in various electronic, optoelectronic, and bio-medical applications due to their great potentials. The size, density and configuration of Au NPs play a vital role in the performance of these devices. In this paper, we present a systematic study on the self-assembled hexagonal Au voids, nano-clusters and NPs fabricated on GaN (0001) by the variation of annealing temperature and deposition amount. At relatively low annealing temperatures between 400 and 600°C, the fabrication of hexagonal shaped Au voids and Au nano-clusters are observed and discussed based on the diffusion limited aggregation model. The size and density of voids and nano-clusters can systematically be controlled. The self-assembled Au NPs are fabricated at comparatively high temperatures from 650 to 800°C based on the Volmer-Weber growth model and also the size and density can be tuned accordingly. The results are symmetrically analyzed and discussed in conjunction with the diffusion theory and thermodynamics by utilizing AFM and SEM images, EDS maps and spectra, FFT power spectra, cross-sectional line-profiles and size and density plots.     

Experimental and theoretical analyses of nano-silver for antibacterial activity based on differential crystal growth temperatures

The modulation of antimicrobial properties of nanomaterials can be achieved through various physical and chemical processes, which ultimately affect subsequent properties. In this study, the antibacterial potential of nano-silver was investigated at 0.5, 1.0, 2.0, and 3.0 g/L, and its differential temperature synthesis was achieved at 20, 50, and 70 °C using the solvent evaporation method. Nano-silver particles exhibited FCC (octahedral) crystalline structure with crystallite sizes ranging between 28 and 39 nm calculated using XRD analysis. Moreover, irregular and non-uniform surface morphology was evident from SEM micrographs. The UV–Vis absorbance spectrum of nano-silver exhibited wave maxima at 433 nm, while the FTIR analysis depicted different modes of vibration indicating the CH, OH, C≡C, C-Cl, and CH₂ functional groups attached to the surface. Lastly, nano-silver caused prominent inhibition (12.5 mm) in the Escherichia coli growth, particularly at 70 °C synthesis temperature and 3.0 g/L dose. It is concluded that both the nano-silver crystal growth temperature and dose contributed substantially to bacterial growth inhibition linked with subsequent size, shape-dependent properties.     

Biological synthesis of gold nanoparticles using Magnolia kobus and Diopyros kaki leaf extracts

Leaf extracts of two plants, Magnolia kobus and Diopyros kaki, were used for ecofriendly extracellular synthesis of metallic gold nanoparticles. Stable gold nanoparticles were formed by treating an aqueous HAuCl₄ solution using the plant leaf extracts as reducing agents. UV–visible spectroscopy was used for quantification of gold nanoparticle synthesis. Only a few minutes were required for >90% conversion to gold nanoparticles at a reaction temperature of 95 °C, suggesting reaction rates higher or comparable to those of nanoparticle synthesis by chemical methods. The synthesized gold nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and particle analysis using a particle analyzer. SEM and TEM images showed that a mixture of plate (triangles, pentagons, and hexagons) and spherical structures (size, 5–300 nm) were formed at lower temperatures and leaf broth concentrations, while smaller spherical shapes were obtained at higher temperatures and leaf broth concentrations.     

Growth of Rhizobium japonicum Strains at Temperatures Above 27°C

A study was conducted to examine the growth responses of different Rhizobium japonicum strains to increasing temperatures, determine the degree of variability among strains in those responses, and identify temperature-related growth characteristics that could be used to select temperature-tolerant strains. Each of 42 strains was grown in liquid culture for 96 h at 19 incubation temperatures ranging from 27.4 to 54.1°C in a temperature gradient apparatus. Growth was estimated by measuring the change in optical density over time. Strains differed in their responses to increasing temperatures. Three characteristic temperatures were determined for each strain: the temperature giving the maximum optical density at 96 h (optimum temperature), the maximum temperature allowing a continuous increase in optical density during the 96-h period (maximum permissive temperature), and the maximum temperature allowing growth of the cultures after they were transferred to a uniform incubation temperature of 28°C (maximum survival temperature). The three characteristic temperatures varied among strains and had the following ranges: optimum temperature, from 27.4 to 35.2°C; maximum permissive temperature, from 29.8 to 38.0°C; and maximum survival temperature, from 33.7 to 48.7°C. Significant positive correlations were found between maximum permissive temperature and optimum temperature and between maximum permissive temperature and maximum survival temperature. Eight strains which had the highest maximum permissive temperature, optimum temperature, and maximum survival temperature were considered tolerant of high temperatures and were able to grow at temperatures higher than those previously reported for the most tolerant R. japonicum strains. The strains were of diverse geographical origin, but the response to high temperatures was not related to their origin. Evaluation of the temperature responses in pure culture may be useful in the search for R. japonicum strains better suited to environments in which high soil temperature is a limiting factor.     

CONCERNING THE HEREDITARY ADAPTATION OF ORGANISMS TO HIGHER TEMPERATURE

1. Imagos of Drosophila raised at temperatures of from 12–28.5°C. when placed at any temperature from 15–32.5°C. produce eggs which develop normally at these temperatures. 2. Imagos raised at temperatures of from 29–32.5° and then kept permanently within these temperatures produce eggs which do not develop. 3. Imagos raised at from 28.5–32.5°C. and then placed at temperatures of from 12–25°C. produce eggs which develop normally. 4. Imagos raised at from 28.5–32.5°C. placed at 15–25°C. for 24 hours or longer and then put back into a temperature of from 28.5–32.5°C., produce eggs which will develop at the latter temperature. 5. There is no evidence of any hereditary adaptation to higher temperatures.     

Suggested limits to the use of the hot tub and sauna by pregnant women

Because of reports of the potential risk of maternal hyperthermia to a developing embryo or fetus, studies were done to determine the length of time a woman must stay in a hot tub or sauna before her temperature reaches 38.9°C. The vaginal temperatures of 20 nonpregnant women of childbearing age were recorded while they sat in hot tubs set at 39.0°C or 41.1°C and in a sauna with an average temperature of 81.4°C. Five women were able to remain in the 39.0°C tub and six in the 41.1°C tub until their temperature reached 38.9°C, but in none did their temperature reach that level before 15 minutes in the 39.0°C tub or 10 minutes in the 41.1°C tub. The remainder left in discomfort while their body temperatures were lower. This indicates that the usual use of hot tubs is unlikely to raise a woman''s body temperature to potentially teratogenic levels, although prolonged use may. None of the women were able to remain in the sauna long enough for their temperature to reach 39.9°C.     

Effects of cycling temperatures on fiber metabolism in cultured cotton ovules

The effects of temperature on rates of cellulose synthesis, respiration, and long-term glucose uptake were investigated using cultured cotton ovules (Gossypium hirsutum L. cv Acala SJ1). Ovules were cultured either at constant 34°C or under cycling temperatures (12 h at 34°C/12 h at 15-40°C). Rates of respiration and cellulose synthesis at various temperatures were determined on day 21 during the stage of secondary wall synthesis by feeding cultured ovules with [¹⁴C]glucose. Respiration increased between 18 and approximately 34°C, then remained constant up to 40°C. In contrast, the rate of cellulose synthesis increased above 18°C, reached a plateau between about 28 and 37°C, and then decreased at 40°C. Therefore, the optimum temperature for rapid and metabolically efficient cellulose synthesis in Acala SJ1 is near 28°C. In ovules cycled to 15°C, respiration recovered to the control rate immediately upon rewarming to 34°C, but the rate of cellulose synthesis did not fully recover for several hours. These data indicate that cellulose synthesis and respiration respond differently to cool temperatures. The long-term uptake of glucose, which is the carbon source in the culture medium, increased as the low temperature in the cycle increased between 15 and 28°C. However, glucose uptake did not increase in cultures grown constantly at 34°C compared to those cycled at 34/28°C. These observations are consistent with previous observations on the responses of fiber elongation and weight gain to cycling temperatures in vitro and in the field.     

Effects of Temperature on Resistance in Phaseolus vulgaris Genotypes and on Development of Meloidogyne Species

Phaseolus vulgaris lines with heat-stable resistance to Meloidogyne spp. may be needed to manage root-knot nematodes in tropical regions. Resistance expression before and during the process of nematode penetration and development in resistant genotypes were studied at pre- and postinoculation temperatures of 24 °C and 24 °C, 24 °C and 28 °C, 28 °C and 24 °C, and 28 °C and 28 °C. Resistance was effective at all temperature regimes examined, with fewer nematodes in roots of a resistant line compared with a susceptible line. Preinoculation temperature did not modify resistance expression to later infections by root-knot nematodes. However, postinoculation temperatures affected development of Meloidogyne spp. in both the resistant and susceptible bean lines tested. The more rapid development of nematodes to adults at the higher postinoculation temperature of 28 °C in both bean lines suggests direct temperature effects on nematode development instead of on resistance expression of either of two gene systems. Also, resistance was stable at 30 °C and 32 °C.     

Temperature Dependence of Photosynthesis in Agropyron smithii Rydb. : II. CONTRIBUTION FROM ELECTRON TRANSPORT AND PHOTOPHOSPHORYLATION

As part of an analysis of the factors regulating photosynthesis in Agropyron smithii Rydb., a C₃ grass, the response of electron transport and photophosphorylation to temperature in isolated chloroplast thylakoids has been examined. The response of the light reactions to temperature was found to depend strongly on the preincubation time especially at temperatures above 35°C. Using methyl viologen as a noncyclic electron acceptor, coupled electron transport was found to be stable to 38°C; however, uncoupled electron transport was inhibited above 38°C. Photophosphorylation became unstable at lower temperatures, becoming progressively inhibited from 35 to 42°C. The coupling ratio, ATP/2e⁻, decreased continuously with temperature above 35°C. Likewise, photosystem I electron transport was stable up to 48°C, while cyclic photophosphorylation became inhibited above 35°C. Net proton uptake was found to decrease with temperatures above 35°C supporting the hypothesis that high temperature produces thermal uncoupling in these chloroplast thylakoids. Previously determined limitations of net photosynthesis in whole leaves in the temperature region from 35 to 40°C may be due to thermal uncoupling that limits ATP and/or changes the stromal environment required for photosynthetic carbon reduction. Previously determined limitations to photosynthesis in whole leaves above 40°C correlate with inhibition of photosynthetic electron transport at photosystem II along with the cessation of photophosphorylation.     

Adaptation of Phytoplankton-Degrading Microbial Communities to Thermal Reactor Effluent in a New Cooling Reservoir

In water column and sediment inocula from a nuclear reactor cooling reservoir, natural phytoplankton substrate labeled with ¹⁴C was used to determine aerobic and anaerobic mineralization rates for a range of temperatures (25, 40, 55, and 70°C) expected during reactor operation. For experiments that were begun during reactor shutdown, aerobic decomposition occurred at temperatures of <55°C. After 2 months of reactor operation, aerobic rates increased substantially at 55 and 70°C, although maximum rates were observed at temperatures of ≤40°C. The temperature range for which maximum anaerobic mineralization (i.e., the sum of CH₄ and CO₂) was observed was 25 to 40°C when the reactor was off, expanding to 25 to 55°C during reactor operation. Increased rates at 55°C, but not 70°C, correlated with an increase in the ratio of cumulative methane to carbon dioxide produced over 21 days. When reduced reactor power lowered the maximum temperature of the reservoir to 42°C, aerobic decomposition at 70°C was negligible, but remained substantial at 55°C. Selection for thermophilic decomposers occurred rapidly in this system in both aerobic and anaerobic communities and did not require prolonged exposure to elevated temperatures.     

Acetate Degradation at 70°C in Upflow Anaerobic Sludge Blanket Reactors and Temperature Response of Granules Grown at 70°C

Anaerobic acetate degradation at 70°C and at 55°C (as a reference) was studied by running laboratory upflow anaerobic sludge blanket (UASB) reactors inoculated with mesophilic granular sludge. In UASB reactors fed with acetate-containing media (3 g of chemical oxygen demand [COD] per liter, corresponding to 47 mM acetate) approximately 50 days was needed at 70°C and less than 15 days was needed at 55°C to achieve an effluent COD of 500 to 700 mg/liter. In the UASB reactors at both 70 and 55°C up to 90% of the COD was removed. Batch assays showed that sludges from two 70°C UASB reactors, one run at a low effluent acetate concentration and the other run at a high effluent acetate concentration, exhibited slightly different responses to temperatures in the range from 37 to 70°C. Both 70°C sludges, as well as the 55°C sludge, produced methane at temperatures of 37 to 73°C. The 55°C sludge exhibited shorter lag phases than the 70°C sludges and higher specific methane production rates between 37 and 65°C.     

DEVELOPMENT OF THE EGG OF THE MACKEREL AT DIFFERENT CONSTANT TEMPERATURES

1. Mackerel egg development was followed to hatching at constant temperatures of 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, 21°, 22°, and 24°C. Experiment showed that typical development could be realized only between 11° and 21°. 2. The length of the developmental period increases from 49.5 hours to 207 hours when the temperature is lowered from 21° to 10°C. 3. The calculated µ for the development of the mackerel egg is about 19,000 at temperatures above 15° and approximately 24,900 for temperatures below 15°C. 15° is, apparently, a critical temperature for this process. 4. The calculated values of µ for eight stages of development preceding hatching, i.e. 6 somites, 12 somites, 18 somites, 24 somites, three-quarters circles, four-fifths circles, five-sixths circles, and full circles, are essentially the same as the µ''s for hatching, indicating that the rate of differentiation up to hatching is governed by one process throughout. Critical temperatures for these stages approximate 15°. 5. The total mortality during the incubation period was least at 16°C. where it amounted to 43 per cent. At temperatures above and below this there was a steady increase in the percentage of mortality which reached 100 per cent at 10° and 21°.     

Developmental history affects the susceptibility of spinach leaves to in vivo low temperature photoinhibition

Room temperature chlorophyll a fluorescence was used to determine the effects of developmental history, developmental stage, and leaf age on susceptibility of spinach to in vivo low temperature (5°C) induced photoinhibition. Spinach (Spinacia oleracea cv Savoy) leaves expanded at cold hardening temperatures (5°C day/night), an irradiance of 250 micromoles per square meter per second of photosynthetic proton flux density, and a photoperiod of 16 hours were less sensitive than leaves expanded at nonhardening temperatures (16 or 25°C day/night) and the same irradiance and photoperiod. This differential sensitivity to low-temperature photoinhibition was observed at high (1200) but not lower (500 or 800 micromoles per square meter per second) irradiance treatment. In spite of a differential sensitivity to photoinhibition, both cold-hardened and nonhardened spinach exhibited similar recovery kinetics at either 20 or 5°C. Shifting plants grown at 16°C (day/night) to 5°C (day/night) for 12 days after full leaf expansion did not alter the sensitivity to photoinhibition at 5°C. Conversely, shifting plants grown at 5°C (day/night) to 16°C (day/night) for 12 days produced a sensitivity to photoinhibition at 5°C similar to control plants grown at 16°C. Thus, any resistance to low-temperature photoinhibition acquired during growth at 5°C was lost in 12 days at 16°C. We conclude that leaf developmental history, developmental stage, and leaf age contribute significantly to the in vivo photoinhibitory response of spinach. Thus, these characteristics must be defined clearly in studies of plant susceptibility to photoinhibition.     

Variable Temperature Stress in the Nematode Caenorhabditis elegans (Maupas) and Its Implications for Sensitivity to an Additional Chemical Stressor

A wealth of studies has investigated how chemical sensitivity is affected by temperature, however, almost always under different constant rather than more realistic fluctuating regimes. Here we compared how the nematode Caenorhabditis elegans responds to copper at constant temperatures (8–24°C) and under fluctuation conditions of low (±4°C) and high (±8°C) amplitude (averages of 12, 16, 20°C and 16°C respectively). The DEBkiss model was used to interpret effects on energy budgets. Increasing constant temperature from 12–24°C reduced time to first egg, life-span and population growth rates consistent with temperature driven metabolic rate change. Responses at 8°C did not, however, accord with this pattern (including a deviation from the Temperature Size Rule), identifying a cold stress effect. High amplitude variation and low amplitude variation around a mean temperature of 12°C impacted reproduction and body size compared to nematodes kept at the matching average constant temperatures. Copper exposure affected reproduction, body size and life-span and consequently population growth. Sensitivity to copper (EC₅₀ values), was similar at intermediate temperatures (12, 16, 20°C) and higher at 24°C and especially the innately stressful 8°C condition. Temperature variation did not increase copper sensitivity. Indeed under variable conditions including time at the stressful 8°C condition, sensitivity was reduced. DEBkiss identified increased maintenance costs and increased assimilation as possible mechanisms for cold and higher copper concentration effects. Model analysis of combined variable temperature effects, however, demonstrated no additional joint stressor response. Hence, concerns that exposure to temperature fluctuations may sensitise species to co-stressor effects seem unfounded in this case.     

Temperature Adaptations in the Terminal Processes of Anaerobic Decomposition of Yellowstone National Park and Icelandic Hot Spring Microbial Mats

The optimum temperatures for methanogenesis in microbial mats of four neutral to alkaline, low-sulfate hot springs in Yellowstone National Park were between 50 and 60°C, which was 13 to 23°C lower than the upper temperature for mat development. Significant methanogenesis at 65°C was only observed in one of the springs. Methane production in samples collected at a 51 or 62°C site in Octopus Spring was increased by incubation at higher temperatures and was maximal at 70°C. Strains of Methanobacterium thermoautotrophicum were isolated from 50, 55, 60, and 65°C sites in Octopus Spring at the temperatures of the collection sites. The optimum temperature for growth and methanogenesis of each isolate was 65°C. Similar results were found for the potential rate of sulfate reduction in an Icelandic hot spring microbial mat in which sulfate reduction dominated methane production as a terminal process in anaerobic decomposition. The potential rate of sulfate reduction along the thermal gradient of the mat was greatest at 50°C, but incubation at 60°C of the samples obtained at 50°C increased the rate. Adaptation to different mat temperatures, common among various microorganisms and processes in the mats, did not appear to occur in the processes and microorganisms which terminate the anaerobic food chain. Other factors must explain why the maximal rates of these processes are restricted to moderate temperatures of the mat ecosystem.     

Photoinduced Seed Germination of Oenothera biennis L: III. Analysis of the Postinduction Period by Means of Temperature

The postinduction period of Oenothera biennis L. seed germination was examined by temperature treatments. For all experiments, seeds received a standard 24 hour/24°C preinduction period and 12 hour/32°C photoinduction period. Germination is inhibited by postinduction temperatures above 32°C. When seeds are briefly incubated at 44°C and then transferred to 28°C, they germinate at a much lower percentage than 28°C controls. When thermally inhibited seeds are placed in the dark at 28°C for 20 hours, they can be promoted to germinate by a single pulse of red light. Seeds incubated at 12°C or below immediately after photoinduction enter a lag period in which they germinate slowly or not at all for a long time and then resume germination. The length of the lag period is exponentially related to the postinduction temperature. When seeds are incubated at a low temperature and then transferred to a warm temperature, they germinate much more rapidly than seeds not incubated at a low temperature. A model is proposed which is consistent with these and additional results. In the model, a germination promoter is irreversibly formed from a precursor and the synthesis of the precursor is favored at low temperatures and its degradation is favored at high temperatures.     

Effects of temperature on the coupled activities of the vanadate-sensitive proton pump from maize root microsomes

The mechanism by which proton transport is coupled to ATP hydrolysis by vanadate-sensitive pumps is poorly understood. The effects of temperature on the activities of the vanadate-sensitive ATPase from maize (Zea mays) roots were assessed to provide insight into the coupling mechanism. The initial rate of proton transport had a bell-shaped dependence on temperature with an optimal range between 20 and 30°C. However, the rate of vanadate-sensitive ATP hydrolysis increased as the temperature was raised from 4 to 43°C. The differential sensitivity of proton transport to temperatures above 30°C was also observed when the ATPase was reconstituted into dioleoylphosphatidylcholine vesicles. Inhibition of proton transport with temperatures above 30°C was associated with higher rates of proton leakage from the membranes. In addition, proton transport was more inhibited than ATP hydrolysis at temperatures below 10°C. Reduced rates of proton transport at lower temperatures were not associated with higher rate of proton conductivity across the membranes. Therefore, the preferential inhibition of proton transport at temperatures below 10°C may reflect an effect of temperature on the coupling between proton transport and ATP hydrolysis within the vanadate-sensitive ATPase.     

Rapid increase in deep supercooling of xylem parenchyma

Malus pumila Mill. twigs were collected from September through December and stored at 5°C until the low temperature exotherms of the xylem were determined by differential thermal analysis. During the differential thermal analysis, cooling was interrupted, and temperatures of 5 to −18°C were held for 0.4 to 10 hours before cooling to −50°C was resumed. Control twigs were cooled to −50°C without interruption. Holding the twigs at 1.3 to −5°C shifted the start of the low temperature exotherm from about −20 to −30°C. Slightly higher (2.6°C) and lower (−10°C) temperatures were occasionally effective. The shift began within 20 to 30 minutes and increased progressively to 150 minutes. The acclimation was reversibly inhibited by N₂ atmosphere.     

Preparation of High Purity Crystalline Silicon by Electro-Catalytic Reduction of Sodium Hexafluorosilicate with Sodium below 180°C

The growing field of silicon solar cells requires a substantial reduction in the cost of semiconductor grade silicon, which has been mainly produced by the rod-based Siemens method. Because silicon can react with almost all of the elements and form a number of alloys at high temperatures, it is highly desired to obtain high purity crystalline silicon at relatively low temperatures through low cost process. Here we report a fast, complete and inexpensive reduction method for converting sodium hexafluorosilicate into silicon at a relatively low reaction temperature (∼200°C). This temperature could be further decreased to less than 180°C in combination with an electrochemical approach. The residue sodium fluoride is dissolved away by pure water and hydrochloric acid solution in later purifying processes below 15°C. High purity silicon in particle form can be obtained. The relative simplicity of this method might lead to a low cost process in producing high purity silicon.