Environmental stress and elicitors enhance taxol production by endophytic strains of Paraconiothyrium variabile and Epicoccum nigrum

This study examined the effect of different elicitors (seven, different concentrations) and environmental factors (water activity (a_w), pH) on taxol production by strains of two endophytic fungi, Paraconiothyrium variabile and Epicoccum nigrum, isolated from temperate yew trees. A defined liquid broth medium was modified with elicitors, solute a_w depressors at different pH values. For P. variabile, the best elicitor was salicylic acid at 50 mg/l which gave a taxol yield of 14.7 ± 4.8 μg/l. The study of synergistic effects between elicitor, a_w and pH on taxol production showed that the highest yield of taxol (68.9 ± 11.9 μg/l) was produced under modified ionic stress of 0.98 a_w (KCl) at pH 5 when supplemented with 20 mg/l of salicylic acid. For E. nigrum, serine was the best elicitor which increased yield significantly (29.6 fold) when KCL was used as the a_w depressor (0.98 a_w) at pH 5.0 with 30 mg/l of serine. The maximum taxol yield produced by E. nigrum was 57.1 ± 11.8 μg/l. Surface response models were used to build contour maps to determine the conditions for maximum and marginal conditions for taxol yield in relation to the best elicitor and a_w, and the best pH for the first time. This will be beneficial for identifying key parameters for improvement of taxol yields by endophytic fungi.     

l-Lactic acid production from liquefied cassava starch by thermotolerant Rhizopus microsporus: Characterization and optimization

The thermotolerant Rhizopus microsporus DMKU 33 capable of producing l-lactic acid from liquefied cassava starch was isolated and characterized for its phylogenetic relationship and growth temperature and pH ranges. The concentrations of (NH₄)₂SO_4, KH₂PO₄, MgSO₄ and ZnSO₄·7H₂O in the fermentation medium was optimized for lactic acid production from liquefied cassava starch by Rhizopus microsporus DMKU 33 in shake-flasks at 40 °C. The fermentation was then studied in a stirred-tank bioreactor with aeration at 0.75 vvm and agitation at 200 rpm, achieving the highest lactic acid production of 84 g/L with a yield of 0.84 g/g at pH 5.5 in 3 days. Lactic acid production was further increased to 105–118 g/L with a yield of 0.93 g/g and productivity of 1.25 g/L/h in fed-batch fermentation. R. microsporus DMKU 33 is thus advantageous to use in simultaneous saccharification and fermentation for l-lactic acid production from low-cost starchy substrates.     

Glycation of lysozyme with galactose,galactooligosaccharides and potato galactan through the Maillard reaction and optimization of the production of prebiotic glycoproteins

The production of glycated lysozyme (LZM), with galactose, galactooligosaccharides (GOSs) and potato galactan through the Maillard reaction, was investigated. The percent blocked lysine, estimated from the furosine content, reached a maximum value of 11.2% for LZM:galactan conjugates after 1 day incubation at a a_w of 0.65. A maximum percent blocked lysine of 7.0 and 13.5% were obtained for LZM:galactose/GOS conjugates at a lower a_w of 0.45 after 3 and 7 days, respectively. However, the low percent blocked lysine and the high protein aggregation index of LZM:galactose/GOS conjugates at a_w 0.79 and 0.65 revealed the prevalence of the degradation of the Amadori compounds and the protein cross-linking. Mass spectrometry of LZM conjugates revealed the formation of different glycoforms. Glycated LZMs containing up to seven galactose moieties were formed; while only mono- and diglycated LZMs with GOSs were detected. 2–3 mol of galactan were conjugated to 1 mol of LZM. Response surface methodology, based on a 5-level and 3-factor central composite design, revealed that molar ratio and temperature were the most significant variables for the glycation of LZM with GOSs. The optimal conditions leading to a high percent blocked lysine (16.11%) with a low protein aggregation index (0.11) were identified: temperature of 49.5 °C, LZM:GOS molar ratio of 1:9 and a_w of 0.65. To the best of our knowledge, this is the first study on the optimization of LZM glycation with GOSs.     

Carbon mineralization of Chinese fir (Cunninghamia lanceolata) soils under different temperature and humidity conditions

Burned and unburned mineral soils (0–10 cm) from a 40-year-old Chinese fir (Cunninghamia lanceolata) forest in Nanping, Fujian, China were incubated for 90 days at different temperatures (25 °C and 35 °C) and humidity [25%, 50%, and 75% of water holding capacity (WHC)] conditions. Carbon (C) mineralization of all soils was determined using CO₂ respiration method. The results showed that CO₂ evolution rates of the burned and control soils exhibited similar temporal patterns, and similar responses to temperature and moisture. CO₂ evolution rates for all soil samples decreased with incubation time. At different humidity conditions, average rate of C mineralization and cumulative mineralized C from burned and control soils were significantly higher at 35 °C than at 25 °C. This implied that C mineralization was less sensitive to soil moisture than to temperature. In both soils at 25 °C or 35 °C, the amount of soil evolved CO₂ over the 90 days incubation increased with increasing moisture content from 25% to 75% WHC. A temperature coefficient (Q₁₀) varied with soil moisture contents. The maximum values recorded for Q₁₀ were 1.7 in control soil and 1.6 in burned soil both at 25% WHC. However, there were no significant differences in Q₁₀ values between the control and burned soils over all moisture ranges (P > 0.05). The data of cumulative C–CO₂ released from control and burned soils were fitted to two different kinetic models. The two simultaneous reactions model described mineralization better than the first-order exponential model, which reflected the heterogeneity of substrate quality. Based on these results, it is possible to conclude that temperature and moisture are important in the controls of C mineralization, and the combined effects of these variables need to be considered to understand and predict the response of CO₂ release in subtropical ecosystems to climate change.     

Dried alginate-entrapped enzymes (DALGEEs) and their application to the production of fructooligosaccharides

A modification of the classical calcium alginate enzyme entrapment technique is described aiming to overcome some of the limitations of the former gel-based biocatalysts. Dried alginate entrapped enzymes (DALGEEs) were obtained dehydrating calcium alginate gel beads containing entrapped enzymes. A fructosyltransferase from Aspergillus aculeatus, present in Pectinex Ultra SP-L, was entrapped using this technique. The resulting DALGEEs were successfully tested both operating batchwise and in a continuous fixed-bed reactor for fructooligosaccharides (FOS) synthesis from sucrose. Interestingly, DALGEEs did not re-swell upon incubation in concentrated (600 g/L) sucrose solutions, probably due to the lowered water activity (a_w) of such media. Confocal laser scanning microscopy of DALGEEs revealed that the enzyme molecules accumulated preferably in the shell of the particles. DALGEEs showed an approximately 30-fold higher volumetric activity (300 U/mL) compared with the calcium alginate gel beads. Moreover, a significant enhancement (40-fold) of the space-time-yield of fixed-bed bioreactors was observed when using DALGEEs as biocatalyst compared with gel beads (4030 g/day L of FOS vs. 103 g/day L). The operational stability of fixed-bed reactors packed with DALGEEs was extraordinary, providing a nearly constant FOS composition of the outlet during at least 700 h. It was also noticeable their resistance against microbial attack, even after long periods of storage at room temperature. The DALGEEs immobilisation strategy may also be useful for other biotransformations, in particular when they take place in low a_w media.     

Modeling small-scale cassava starch extraction. Simulation of the reduction of water consumption through a recycling process

The purpose of this study was to model the extraction unit operation of the cassava starch manufacturing process and to propose a realistic recycling simulation in order to reduce the volumes of effluents. The model was developed from reactors which are commonly used for cassava starch extraction at a household scale in Vietnam. The reactors were tested using inflow starch as a marker at the beginning of the batch process. The experimental residence time distribution (RTD_exp) was calculated by the outflow of the starch concentration. Using Matlab^®, the RTD_exp was compared to the theoretical residence time distribution (RTD_th). The dynamic model obtained was built up on Simulink^® and tested with four different strategies of recycling methods. Sedimented starch was collected from the different types of processes; the pH value and the titratable acidity of starch were then measured. The results showed a good correlation between RTD_exp and RTD_th. The reactors were described by a model of two mixed tanks in series. The simulation of the recycling process revealed a reduction in quantity of water used up to 43%; however, the recycling process increased significantly the titratable acidity of starch up to 6.48 ± 0.11 mequiv. H⁺/100 g dry matter.     

Impact of annealing and heat-moisture treatment on rapidly digestible,slowly digestible and resistant starch levels in native and gelatinized corn,pea and lentil starches

Impact of annealing (ANN) and heat-moisture treatment (HMT) on rapidly digestible starch (RDS), slowly digestible starch (SDS), resistant starch (RS), and expected glycemic index (eGI) of corn, pea, and lentil starches in their native and gelatinized states were determined. ANN was done for 24 h at 70% moisture at temperatures 10 and 15 °C below the onset (T_o) temperature of gelatinization, while HMT was done at 30% moisture at 100 and 120 °C for 2 h. The swelling factor (SF), amylose leaching (AML) and gelatinization parameters of the above starches before and after ANN and HMT were determined. SF and AML decreased on ANN and HMT (HMT > ANN). The gelatinization temperatures increased on ANN and HMT (HMT > ANN). However, the gelatinization temperature range decreased on ANN but increased on HMT. Birefringence remained unchanged on ANN but decreased on HMT. The Fourier transform infrared (FT-IR) absorbance ratio of 1047 cm^?1/1022 cm^?1 increased on ANN but decreased on HMT. ANN and HMT increased RDS, RS and eGI levels and decreased SDS levels in granular starches. HMT had a greater impact than ANN on RDS, RS, and SDS levels. In gelatinized starches, ANN and HMT decreased RDS and eGI, but increased SDS and RS levels. These changes were more pronounced on HMT. This study showed that amylopectin structure and interactions formed during ANN and HMT had a significant impact on RDS, SDS, RS and eGI levels of starches.     

Starch pastes thinning during high-pressure homogenization

High-pressure homogenization induced thinning of potato and cassava starch paste was investigated. The starch slurries at a concentration of 2.0 wt.% were heated at 90 °C for 1 h and then rapidly cooled in tap water. The cooled starch pastes were homogenized at various pressures ranging from 0 to 100 MPa using a lab-scale high-pressure homogenizer. The influence of homogenizing pressure on the temperature, apparent viscosity, electrical conductivity, and percent light transmittance of homogenized starch pastes were determined. Temperatures of homogenized starch pastes increased linearly with the increase of the applied pressure, and the rate was 0.177 °C/MPa and 0.186 °C/MPa for potato and cassava starch pastes, respectively. After high-pressure homogenization, the apparent viscosities of the starch pastes decreased, while the percent light transmittances of them increased. However, the electrical conductivities of starch pastes were not affected by homogenization.     

Cellular damage during drying and storage of Trichoderma harzianum spores

Factors that cause cellular damage during the drying and storage of Trichoderma harzianum conidia were independently studied to determine their effects on spore viability. Specifically, thermal stress and dehydration levels (water activity, a_w = 0.1–0.7) were assessed for their effect on spore survival. In addition, environmental conditions, such as water activity and temperature, were evaluated during storage of the spores. T. harzianum spores produced in liquid culture are highly sensitive to thermal stress, but dehydration does not seem to be a factor that influences spore death during desiccation. An inverse correlation between spore survival and the specific concentration of malondialdehyde (MDA) was observed during storage, especially when the conidia moisture levels were lower than the monolayer moisture levels. We prepared spore suspensions without additives and spray-dried the samples. Our data showed that reduced sample viability was mainly caused by the temperature of the drying process, an effect that appears to be independent of water activity.     

Estudios de la viabilidad y la vitalidad frente al congelado de la levadura probiótica Saccharomyces boulardii: efecto del preacondicionamiento fisiológico

The aim of this study was to evaluate the vitality and viability of the probiotic yeast Saccharomyces boulardii after freezing/thawing and the physiological preconditioning effect on these properties. The results indicate that the specific growth rate (0.3/h^?1) and biomass (2-3 × 10⁸ cells/ml) of S. boulardii obtained in flasks shaken at 28 °C and at 37 °C were similar. Batch cultures of the yeast in bioreactors using glucose or sugar-cane molasses as carbon sources, reached yields of 0.28 g biomass/g sugar consumed, after 10 h incubation at 28 °C; the same results were obtained in fed batch fermentations. On the other hand, in batch cultures, the vitality of cells recovered during the exponential growth phase was greater than the vitality of cells from the stationary phase of growth. Vitality of cells from fed-batch fermentations was similar to that of stationary growing cells from batch fermentations. Survival to freezing at –20 °C and subsequent thawing of cells from batch cultures was 0.31% for cells in exponential phase of growth and 11.5% for cells in stationary phase. Pre-treatment of this yeast in media with water activity (a_w) 0.98 increased the survival to freezing of S. boulardii cells stored at –20 °C for 2 months by 10 fold. Exposure of the yeast to media of reduced a_w and/or freezing/thawing process negatively affected cell vitality. It was concluded that stress conditions studied herein decrease vitality of S. boulardii. Besides, the yeast strain studied presented good tolerance to bile salts even at low pH values.     

Pasting properties of a heat-moisture treated canna starch in relation to its structural characteristics

Native and moistened canna starches (moisture contents of 15%, 18%, 20%, 22%, and 25%) were heat treated at 100 °C for 16 h. Heat-moisture treatment (HMT) did not alter the shape or size of starch granules. Heat-treated starches showed lower paste viscosity, more stable paste (with no breakdown) and noticeable decrease in setback value compared to untreated native starch. These changes were more obvious when the starch samples contained more moisture. Starch gel morphology investigated by I₂ staining revealed that the granules of untreated native canna starch were completely ruptured, whereas those of HMT22% and HMT25% samples remained in granular form. These gel morphologies were correlated and provided the information to explain the pasting behaviors of treated and untreated canna starches. Shifts of gelatinization endotherms towards higher temperatures (1–8 °C) with broadened peaks following the moisture contents in starch samples were found after HMT. Amylose leaching of treated samples tended to be lower when the moisture content of the samples increased. HMT did not alter crystalline type of canna starch (B-type), but with increase of the moisture, slight reduction of a peak at 5.7° and a fusion of doublet at 22° and 24° were observed.     

Partitioning of latent heat flux at a northern peatland

The partitioning of latent heat flux (Q_E) to vascular plant and moss surface components was assessed for a Sphagnum-dominated bog with a hummock–hollow surface having a sparse canopy of low shrubs. Results from porometry and eddy covariance measurements of Q_E showed evaporation from the moss surface ranged from greater than 50% of total Q_E early in the growing season to less than 20% after a dry period toward the end of the growing season. Both soil moisture and vapour pressure deficit (D_a) affected this partitioning with drier moss and peat, lower water table, and smaller D_a all reducing moss Q_E. Daily maximum moss Q_E ranged from greater than 200 W m⁻² early in the growing season to less than 100 W m⁻² during a dry period. In contrast, vascular contribution to total Q_E increased over the season from a daily maximum of about 150 W m⁻² to 250 W m⁻² due to increase in leaf area by leaf replacement and emergence and to drying of the moss surface. Porometry results showed average daily maximum conductance from bog shrubs was near 8 mm s⁻¹. These conductance values were smaller than those reported for vascular plants from more nutrient-rich wetlands. The effect of increases in D_a on vascular Q_E were moderated by decreases in stomatal conductance. At constant available energy, vascular leaf conductance was reduced by as much as 2 mm s⁻¹ and moss surface conductance was enhanced by up to 3 mm s⁻¹ by large D_a. Considering vascular and non-vascular water transport characteristics and frequency of water table position and given the observed variations of Q_E partitioning with water table location and moss and peat water content, it is suggested that modelling efforts focus on how dry hummocks and wet hollows each contribute to Q_E, especially as related to D_a and soil moisture dynamics.     

N,N-dimethylacetamide/lithium chloride plasticized starch as solid biopolymer electrolytes

In this study, N, N-dimethylacetamide (DMAc) with certain concentration ranges of lithium chloride (LiCl) was used to plasticize starch by melting extrusion. Solid state ionic conductors, DMAc-plasticized starch containing LiCl also had a potential application as solid biopolymer electrolytes. Scanning electron microscope (SEM) showed that many remanent starch granules embed in DMAc-plasticized starch matrix. With increasing LiCl content, the number of remanent starch granules decreased dramatically and homogeneous thermoplastic starch (TPS) could be achieved. Moreover, Fourier Transform infrared (FT-IR) spectroscopy revealed that LiCl could increase the interaction between starch and plasticizers. In addition, the supermolecular structure of starch was destructed by LiCl detected by wide-angle X-ray scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Finally, LiCl not only could increase the water absorption of TPS, but also improved the conductance of TPS. The conductance of TPS with 18 wt% LiCl content could achieve to 10^?0.5 S cm^?1 at 18 wt% water content.     

Effect of enzymatic and hydrothermal treatments of rapeseeds on quality of the pressed rapeseed oils: Part I: Antioxidant capacity and antioxidant content

Response surface methodology was used to evaluate the quantitative effects of three independent variables: rapeseed moisture content, concentration of the added enzymes and conditioning temperature, on the antioxidant capacity and total phenolic, tocopherol, and phospholipid contents in the enzyme-treated rapeseed oils. The highest antioxidant capacity (1220.0, 964.8 μmol TE/100 g) total phenolic (83.3, 74.0 mg SA/100 g) and phospholipid (12,532, 12,376 mg/kg) contents reveal two rapeseed oils extruded from seeds contained 11% moisture, treated with cellulolytic and pectolytic enzymes (0.05%), respectively, and heated at 120 °C. However, the highest content of total tocopherols was determined in rapeseed oils pressed from seeds with 7% moisture, after addition of cellulolytic (0.05%) and pectolytic (0.1%) enzymes, heated at 90 and 105 °C, respectively. Total phenolic and phospholipid contents in the enzyme-treated rapeseed oils correlated significantly (p < 0.0000001) with antioxidant capacities of oils (R² = 0.8710 and 0.6581, respectively). Experimental results of the antioxidant capacity, total phenolic, tocopherol and phospholipid contents were close to the predicted values calculated from the polynomial response surface models equations (R² = 0.9727, 0.9870, 0.8390 and 0.9706 for the cellulolytic enzyme-assisted rapeseed oils and R² = 0.9148, 0.9489, 0.9426 and 0.9479 for the pectolytic enzyme-assisted rapeseed oils). The optimum rapeseed moisture content, enzyme concentration and conditioning temperature for the cellulolytic and pectolytic enzyme-treated rapeseed oils were 11% and 9.7%, 0.08% and 0.1%, and 120 °C, respectively.     

Spontaneously reduced body temperature and gasping ability as a mechanism of extreme tolerance to asphyxia in neonatal rats

The aim of the investigation was to verify our hypothesis that extreme tolerance of newborn rodents to anoxia is determined by their ability to maintain reduced body temperature and to keep on gasping.Newborn Wistar rats were used. In separate experiments we checked (1) effect of extreme thermal conditions on rectal temperature (T_re) of the newborns in their nests; (2) effect of ambient temperature (T_a) on oxygen consumption; (3) effects of controlled changes in T_re on thermoregulatory and respiratory responses to anoxia and on anoxia tolerance.In their nests rat pups controlled T_re at 32–36 °C while the T_re–T_a difference changed within a range of 1–20 °C. The lowest oxygen consumption of ∼24 ml O₂ kg⁻¹ min⁻¹ was recorded at T_a of 32 °C. Pups, exposed to anoxia at their normal T_re of 33 °C, were able to decrease T_re by another 1.7 °C and they kept on extremely slow and quiescent gasping for scheduled 25 min. In contrast, rats at T_re of 37 °C and 39 °C reached a critical phase of accelerated and shallow gasping after 14.95±0.40 min and 9.25±0.30 min, respectively.In conclusion, reduced T_re and unique gasping ability make newborn rats extremely tolerant to asphyxia.     

Conversion of cassava flour to fuel ethanol by sequential solid state and submerged cultures

A process for conversion of cassava flour to ethanol was developed. This involved direct inoculation of Aspergillus awamori spores into a cassava flour paste and incubation for some period during which hydrolytic enzymes are produced (solid state culture or koji production) and subsequent addition of water and yeast cells, during which there is simultaneous hydrolysis and ethanol production (submerged culture). When cassava flour alone was used for the solid state phase, the paste was very sticky, making mixing and aeration difficult. However, addition of rice bran improved the texture and enzyme production. The optima rice bran concentration, spore inoculum concentration, and duration of solid state culture before submerged culture were 20%, 6.16 × 10⁶ spores/100 g, and 2 days, respectively. Under these optimum conditions, a high ethanol concentration of 120 g/L and ethanol yield of 0.309 g-ethanol/g-cassava flour were obtained. This ethanol yield corresponds to 0.44 g-ethanol/g-cassava starch.     

Release of ferulic acid from corn cobs by alkaline hydrolysis

The process of corn cobs alkaline hydrolysis to produce solutions with high hydroxy-cinnamic acids content was investigated. In particular the attention was focused on the solubilisation of ferulic acid (FA) and related compounds, mainly p-coumaric acid (p-CA). Although these compounds have applications as antioxidants, the purpose of this work was to obtain FA solutions that can be used as feedstock for the biotechnological production of vanillin in future studies. The effects of different concentrations of NaOH (0.2 ≤ C_a ≤ 2.0N) and solid/liquid ratios (0.028 ≤ S/L ≤ 0.168 g/g) on the solubilisation of FA versus time have been investigated at room temperature. Optimal hydrolysis conditions (C_a = 0.5N, S/L = 0.084 g/g after 6 h) ensured the production of hydrolysates with relatively high contents of both FA (1171 ± 34 mg/L) and p-coumaric acid (2156 ± 64 mg/L), which can be used in future studies for the microbial transformation into vanillin.     

5-((1-Aroyl-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-diones as potential anticancer agents with anti-inflammatory properties

A series of novel 5-((1-aroyl-1H-indol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-diones (3a–z) have been evaluated for in vitro cytotoxicity against a panel of 60 human tumor cell lines. Compound 3k exhibited the most potent growth inhibition against melanoma MDA-MB-435 cells (GI₅₀ = 850 nM), against leukemia SR cancer cells (GI₅₀ = 1.45 μM), and OVCAR-3 (GI₅₀ = 1.26 μM) ovarian cancer cell lines. The structurally related compound 3s had a GI₅₀ value of 1.77 μM against MDA-MB-435 cells. The N-naphthoyl analogue 3t had GI₅₀ values of 1.30 and 1.91 μM against HOP-92 non-small cell lung cancer and MDA-MB-435 melanoma cell lines, respectively. The related analogue 3w had GI₅₀ values of 1.09 μM against HOP-92 non-small cell lung cancer cell lines. Interestingly, docking of the two active molecules 3k and 3w into the active site of COX-2 indicates that these compounds are COX-2 ligands with strong hydrophobic and hydrogen bonding interactions. Thus, compounds 3k, 3t, 3s, and 3w constitute a new class of anticancer/anti-inflammatory agents that may have unique potential for cancer therapy.     

Temperature dependence of growth,development, and photosynthesis in maize under elevated CO2

Global atmospheric carbon dioxide concentrations (C_a) are rising. As a consequence, recent climate models have projected that global surface air temperature may increase 1.4–5.8 °C with the doubling of C_a by the end of the century. Because, changes in C_a and temperature are likely to occur concomitantly, it is important to evaluate how the temperature dependence of key physiological processes are affected by rising C_a in major crop plants including maize (Zea mays L.), a globally important grain crop with C₄ photosynthetic pathway. We investigated the temperature responses of photosynthesis, growth, and development of maize plants grown at five temperature regimes ranging from 19/13 to 38.5/32.5 °C under current (370 μmol mol⁻¹) and doubled (750 μmol mol⁻¹) C_a throughout the vegetative stages using sunlit controlled environmental chambers in order to test if the temperature dependence of these processes was altered by elevated C_a. Leaf and canopy photosynthetic rates, C₄ enzyme activities, leaf appearance rates, above ground biomass accumulation and leaf area were measured. We then applied temperature response functions (e.g., Arrhenius and Beta distribution models) to fit the measured data in order to provide parameter estimates of the temperature dependence for modeling photosynthesis and development at current and elevated C_a in maize. Biomass, leaf area, leaf appearance rate, and photosynthesis measured at growth C_a was not changed in response to CO₂ enrichment. Carboxylation efficiency and the activities of C₄ enzymes were reduced with CO₂ enrichment indicating possible photosynthetic acclimation of the C₄ cycle. All measured parameters responded to growth temperatures. Leaf appearance rate and leaf photosynthesis showed curvilinear response with optimal temperatures near 32 and 34 °C, respectively. Total above ground biomass and leaf area were negatively correlated with growth temperature. The dependence of leaf appearance rate, biomass, leaf area, leaf and canopy photosynthesis, and C₄ enzyme activities on growth temperatures was comparable between current and elevated C_a. The results of this study suggest that the temperature effects on growth, development, and photosynthesis may remain unchanged in elevated C_a compared with current C_a in maize.     

XRD studies of UV-irradiated chitin based polyurethane elastomers

Chitin based polyurethane (PU) elastomers constituted on 4,4´-diphenylmethane diisocyanate (MDI), poly(ε-caprolactone) (PCL) and extended with blends of chitin/1,4-butane diol were synthesized via two step polymerization technique. The synthesized samples were irradiated for 50, 100 and 200 h in an UV exposure chamber as such the spectral distribution of the light is good match for terrestrial solar radiation. The crystalline behavior of the irradiated PU samples were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and dynamic mechanical thermal analysis (DMTA) techniques. The effect of irradiation time and chitin contents on crystallinity were studied and investigated. The maximum decrease in the crystalline behavior of samples after irradiation observed by XRD, DSC and tan δ peaks were found for the PU samples extended with lower contents of chitin (chitin/BDO; 0/100). In comparison with irradiation times the 200 h irradiation showed maximum change in the crystalline behavior.