膜分离后的儿茶色素染发性能研究

本文采用聚偏氟乙烯膜提纯天然儿茶色素,结果表明膜分离法具有较好的分离效果.考察了染色温度,时间,pH值及媒染剂浓度等对白色牦牛毛染色效果的影响.结果表明,天然儿茶色素对白色牦牛毛具有直接染色效果,可染成棕色系列.锌离子可使毛发颜色偏向栗子色,铁离子和铜离子可使毛发颜色偏向黑色.其中温度与媒染剂浓度是影响颜色的重要因素.     

Decolorization of aqueous solutions of disperse textile dyes by oxidoreductases

The potential of three oxidoreductases, a laccase preparation of Pleurotus sajor-caju PS-2001, horseradish peroxidase (HRP) and a microbial peroxidase (MP) was evaluated for the decolorization of disperse textile dyes (CI Disperse Red 343, CI Disperse Red 167 and CI Disperse Blue 148) used in polyester dyeing. Decolorization was studied in aqueous solutions varying in dye concentration, pH, temperature, enzyme concentration and the addition of mediators HBT and syringaldazine. The best conditions found for Disperse Red 343 with laccase, HRP and MP were: 15 mg L^?1 dye concentration, 50°C, pH 3.0 for laccase and pH 5.0 for peroxidases. Without mediator, the highest decolorizaton results (38.5% and 58.6%) were achieved with the highest tested concentrations of laccase (10 U mL^?1) and HRP (89.7 U mL^?1), respectively, but no significant difference in decolorization was found for the tested MP concentrations (29.9–89.7 U mL^‐1). HBT or syringaldazine increased decolorization with peroxidases significantly, but no effect was observed for the laccase. Decolorization of Disperse Red 167 (up to 15%) and Disperse Blue 148 (up to 25%) was much lower than of Disperse Red 343. With respect to enzyme concentration, the use of mediator and under the selected test conditions the laccase of P. sajor-caju PS-2001 turned out to be more efficient in disperse dye decolorization, than peroxidases HRP and MP.     

Reduction mechanism of L-cysteine on keratin fibers using microspectrophotometry and Raman spectroscopy

In order to investigate the reduction mechanism of L-cysteine (Cys) on keratin fibers, cross-sectional samples of virgin white human hair treated with Cys were prepared. The heterogeneous reaction between Cys and keratin fibers involving the diffusion of Cys into human hair was analyzed at the molecular level using microspectrophotometry and Raman spectroscopy. The diffusion pattern of Cys into human hair showed non-Fickian type characteristics, thus indicating the free amino groups of electrostatically interacted with the anionic ions of the fiber surface. The disconnected relative concentration of -SS- groups at various depths of the hair samples with pH 9.0 was less than the Cys relative concentration, indicating that the reaction rate (the disconnection of -SS- groups) was slower than the diffusion rate of Cys into human hair. From these experiments, we concluded that the free amino groups of Cys electrostatically interacted with the anionic ions of the fiber surface, thereby decreasing the reaction rate (the disconnection of -SS- groups) of Cys at pH 9.0.     

Selenium concentration in blood and hair of holstein dairy cows

Four-hundred Holstein cows in 40 dairy farms in north Greece were included in this study, and blood (n=400), black hair (n=400), white hair (n=40), and feed (n=40) samples were obtained. Although the feeding regime in these farms was similar, the selenium content of feeds was variable. The Se content of concentrate feeds was 0.104±0.086 mg/kg dry matter (DM), and of silage, it was 0.025±0.018 mg/kg. A significantly positive correlation was found between the Se concentration in black hair and the Se concentration in blood (r ²=0.610, p<0.001), the Se concentration in white hair and the Se concentration in blood (r ²=0.770, p<0.001), and the Se concentration in white hair and the Se concentration in black hair (r ²=0.921, p<0.001). The Se concentration in white hair was significantly smaller than that in black hair (p<0.001).     

Hexavalent chromium removal from aqueous solution by adsorption on treated sawdust

The studies on adsorption of hexavalent chromium were conducted by varying various parameters such as contact time, pH, amount of adsorbent, concentration of adsorbate and temperature. The kinetics of adsorption of Cr(VI) ion followed pseudo second order. Langmuir adsorption isotherm was employed in order to evaluate the optimum adsorption capacity of the adsorbent. The adsorption capacity was found to be pH dependant. Sawdust was found to be very effective and reached equilibrium in 3 h (adsorbate concentration 30 mg l⁻¹). The rate constant has been calculated at 303, 308, 313 and 318 K and the activation energy (E_a) was calculated using the Arrhenius equation. Thermodynamic parameters such as standard Gibbs energy (ΔG°) and heat of adsorption (ΔH_r) were calculated. The ΔG° and ΔH_r values for Cr(VI) adsorption on the sawdust showed the process to be exothermic in nature. The percentage of adsorption increased with decrease in pH and showed maximum removal of Cr(VI) in the pH range 4.5–6.5 for an initial concentration of 5 mg l⁻¹.     

One-pot production of d-allulose from inulin by a novel identified thermostable exoinulinase from Aspergillus piperis and Dorea sp. d-allulose 3-epimerase

Inulin has been widely used as a cheap bioresource for producing many valuable products by enzymatic hydrolysis or microbial fermentation, such as high-fructose syrup and fructooligosaccharides. In this work, a one-pot two-enzyme reaction system was developed to produce d-allulose from inulin using A. piperis exoinulinase and Dorea sp. d-Allulose 3-epimerase. The exoinulinase that was identified from Aspergillus piperis CBS 112811 was cloned and intracellularly expressed in Escherichia coli. The enzyme displayed the maximal activity as 3750 U mg⁻¹ at pH 6.0 and 55 °C. For the effects of different cations, Mn²⁺ simulated the enzyme activity by 41 %. When 10 g L⁻¹ inulin was hydrolyzed by A. piperis exoinulinase, the conversion rate reached 98 % within 6 h. Furthermore, the optimum pH, temperature and the ratio of the two enzymes loaded for one-pot reaction were measured to be pH 6.0, 60 °C and 15/15 U mL⁻¹, respectively. The conversion rate of inulin to d-allulose reached 23.3 % after reaction for 4 h with 10 g L⁻¹ inulin. When adding 100 g L⁻¹ as a substrate, 21.4 g L⁻¹ d-allulose was produced using the two-enzyme system.     

Biosynthesis of lipids by Rhodosporidium toruloides ATCC 10788

The limiting amount of nitrogen required to trigger lipid accumulation in the oleaginous yeast Rhodosporidium toruloides ATCC 10788 was studied, batchwise, by subjecting washed mid-exponentially grown cells to nitrogen at levels of 10⁻² M down to 10⁻⁴ M per g l⁻¹ of lean cells (2–5% fat content) in a mineral medium where glucose was present at 35 g l⁻¹. The results showed that lipid accumulation always started sometime after nitrogen reached a level of 3 × 10⁻⁵ M and the specific initial lipid productivity was constant. Furthermore, the cells were subjected to nine combinations of temperature and pH, from (25° C, pH 4.5) to (35° C, pH 7.5) in the mineral medium supplemented with 0.5 g l⁻¹ of yeast extract and 1 g l⁻¹ (NH₄)₂SO₄. As was expected, lipid content in the cells was higher at 25° C, but pH around 6.0–7.5 slightly enhanced the effect of lower temperature. The effect of pH was also noticed to affect the size of changes in the temporal profiles of the oil's fatty acid distribution prior to nitrogen depletion, whereas no significant difference in the fatty acid composition of the oil was shown after exhaustion of nitrogen from the medium for all combinations of temperature and pH.     

pH and thermal stability studies of chitinase from Trichoderma harzianum: A thermodynamic consideration

The combined effect of pH and temperature on chitinase was investigated using response surface methodology. A central composite design for two variables was employed. The optimal pH and temperature for the least degree of deactivation were found out to be 5.4 and 24°C respectively. The deactivation rate constants and the half life of chitinase were estimated at different pH and temperature combinations. At the optimal pH of 5.4, the rate of the deactivation was found to be the least. Thermodynamic parameters, viz., ΔH^*, ΔS^*, ΔG^* and activation energy of thermal deactivation of chitinase were calculated in the temperature range from 50°C to 60°C.     

Optimization of extracellular lipase production from the biocontrol fungus Nomuraea rileyi

Lipases are important cuticle-degrading enzymes that hydrolyze the ester bonds of waxes, fats and lipoproteins during the infection of insects by the fungus Nomuraea rileyi. Lipase production by the N. rileyi strain MJ was optimized by varying environmental and nutritional conditions in culture medium containing different vegetable oils at various concentrations with shaking at 150 rpm for 8 days at 25°C. The maximum lipase production was obtained using castor oil (30.5±0.6 U mL^?1), followed in order by coconut oil (20.8±0.4 U mL^?1), olive oil (20.8±0.4 U mL^?1) and cottonseed oil (20.6±0.4 U mL^?1). The highest lipase activity (37.7±0.4 U mL^?1) was obtained when castor oil was used at a concentration of 4% (v/v) of basal medium. When the surfactant Tween 80 was added at the fourth day rather than at the beginning of incubation, a maximum lipase activity of 44.9±3.5 U mL^?1 was obtained. The optimal temperature and pH for lipase production were 25°C and pH 8.0, respectively. This is the first report on lipase production by the biocontrol fungus N. rileyi.     

Cloud point extraction-flame atomic absorption spectrometry for pre-concentration and determination of trace amounts of silver ions in water samples

A cloud point extraction (CPE) method was used as a pre-concentration strategy prior to the determination of trace levels of silver in water by flame atomic absorption spectrometry (FAAS) The pre-concentration is based on the clouding phenomena of non-ionic surfactant, triton X-114, with Ag (I)/diethyldithiocarbamate (DDTC) complexes in which the latter is soluble in a micellar phase composed by the former. When the temperature increases above its cloud point, the Ag (I)/DDTC complexes are extracted into the surfactant-rich phase. The factors affecting the extraction efficiency including pH of the aqueous solution, concentration of the DDTC, amount of the surfactant, incubation temperature and time were investigated and optimized. Under the optimal experimental conditions, no interference was observed for the determination of 100 ng·mL⁻¹ Ag⁺ in the presence of various cations below their maximum concentrations allowed in this method, for instance, 50 μg·mL⁻¹ for both Zn²⁺ and Cu²⁺, 80 μg·mL⁻¹ for Pb²⁺, 1000 μg·mL⁻¹ for Mn²⁺, and 100 μg·mL⁻¹ for both Cd²⁺ and Ni²⁺. The calibration curve was linear in the range of 1–500 ng·mL⁻¹ with a limit of detection (LOD) at 0.3 ng·mL⁻¹. The developed method was successfully applied for the determination of trace levels of silver in water samples such as river water and tap water.     

Estimation of intracellular pH in muscle of fishes from different thermal environments

A technique based on homogenisation of rapidly frozen tissue was used to investigate the regulation of intracellular pH (pH_i) in freshwater and marine fish from diverse environmental temperatures. The following species were held at ambient temperatures of ca. 1°C (Notothenia coriiceps; Antarctica), 5°C (Pleuronectes platessa, Myoxocephalus scorpius; North Sea), and 26°C (Oreochromis niloticus; African lakes). The effects of seasonal acclimatisation to 4, 11 and 18°C were also examined in rainbow trout in the winter, autumn and summer, respectively. Extracellular (whole blood) pH (pH_e) did not follow the constant relative alkalinity relationship, where pH⁺=pOH⁻ for any particular temperature, over a range of 1–26°C (overall δpH_e/δT=0.009±0.002 U °C⁻¹; P<0.001), apparently being regulated by ionic fluxes and ventilation. Intracellular pH (pH_i) was also regulated independently of pN(=0.5 pK water) in all species of fish examined. The inverse relationship between pH_i and environmental temperature gave an overall δpH_i/δT of −0.010±0.001 U °C⁻¹ (for both white and red muscle) and −0.004±0.003 U °C⁻¹ (cardiac muscle). However, between 1 and 11°C δpH_i/δT was much higher (P<0.001), −0.022±0.003 U °C⁻¹ (white muscle) and −0.022±0.004 U °C⁻¹ (red muscle). The possible adaptive roles for these different acid–base responses to environmental temperature variation among tissues and species, and the potential difficulties of estimating pH_i, are discussed.     

Association-dependent active folding of alpha and beta subunits of lutropin (luteinizing hormone).

The kinetics of the structural transition of ovine lutropin (luteinizing hormone) from a dissociated and partially unfolded state to a biologically active, folded and associated state were studied from pH 1.8 to 6.5 by difference spectroscopy, circular dichroism, light scattering and ultracentrifugation under various conditions of temperature and ionic strength. Between pH 2.8 and 5.3 there is a thermodynamically reversible equilibrium between the two states of the hormone with a half-transition pH of 4.3 ± 0.1 at 26 °C. The interconversion of native folding to dissociated state is strictly first-order, and most of the kinetic results can be described in terms of two exponential decays with lifetimes of 20 and 100 seconds at pH 2 and 26 °C with one intermediate. A second intermediate with a short lifetime (1.5 s) is detected with stopped-flow experiments; its spectroscopic contribution is small. Refolding from the dissociated state is always second-order in the concentration range studied (12 to 110 μm lutropin), with rates at 26 °C, 1.4 m⁻¹ s⁻¹ at pH 4.3 and 2.2 m⁻¹ s⁻¹ at pH 5.3. The temperature dependence of the rate constant of active folding at pH 5.3 corresponds to activation parameters $\text{ΔH}{}^1\text{= +23.5}\text{kcal mol}{}^{\mathrm{-1}}\text{and}\text{ΔS}{}^1\text{= +21.6}\text{cal deg}{}^{\mathrm{-1}}$ mol⁻¹.From these data and computer-simulation studies, a simplest possible mechanism is proposed that involves the formation of a loose complex between the α and β subunits of the hormone, followed by a slow step of formation of the active, folded state. In the pituitary gland this would be a necessary pathway towards the active form. The storage of the hormone in the gland would offer enough time for this activation step to proceed.     

Thermodynamics of gelation of sickle cell deoxyhemoglobin.

This paper describes the thermodynamic behavior of gels of deoxyhemoglobin S. The solubility of the protein with respect to assembled hemoglobin fibers has been measured using a sedimentation technique. The solubility in 0.15 m-potassium phosphate buffer (pH 7.15) is found to decrease with increasing temperature, attain a minimum value of 0.16 g cm^?3 at 37 °C, and then increase at higher temperatures. The amount of polymer present at various hemoglobin concentrations and temperatures is presented as part of a phase diagram that may be useful for the calibration of other measurement techniques. The effects of varying pH and urea concentration upon the solubility have also been studied.The heat absorption accompanying gelation has been measured by scanning calorimetry. Using sedimentation data on the amount of polymer formed, molar enthalpy changes are obtained. There is a large negative heat capacity change of ? 197 cal deg. mol^?1 and ΔH = 0 near 37 °C. Calorimetric molar enthalpy changes are found to agree with those calculated from the temperature dependence of the solubility by the van't Hoff equation.Our previous two-phase, two-component thermodynamic model of gelation is extended to include the effects of solution non-ideality. A large contribution to the activity of the hemoglobin in the solution phase results from the geometric effect of excluded volume. Incorporating solution phase non-ideality permits the calculation of standard state thermodynamic quantities for the gelation process at 37 °C: ΔG^O ? ?3 k cal mol^?1, ΔH^O ~ 0, ΔS^O ~ 10 cal deg.^?1 mol^?1. The excluded volume effect is also capable of explaining observations of the minimum gelling concentrations of hemoglobin mixtures containing deoxyhemoglobin S without requiring copolymerization of the non-S hemoglobin.     

Determination of panthenol enantiomers in cosmetic preparations using an achiral-chiral–coupled column HPLC system

A new high-performance liquid chromatography (HPLC) method for separation and determination of panthenol enantiomers in hair care products was developed. Two types of detectors, low-wavelength ultraviolet (UV) and polarimetric, were used. Optimized conditions consisted of coupled achiral, amino type, and chiral, amylose tris(3,5-dimethylphenylcarbamate), stationary phases, mixture of n-hexane/ethanol (60:40, v/v) as mobile phase under isocratic conditions and flow rate 0.8 cm³ min⁻¹. The effect of column temperature on retention and resolution of enantiomers was studied. The analysis runtime was 10 minutes, and the average retention times for d - and l -panthenol were 7.10 ±0.1 minutes and 8.21 ±0.2 minutes, respectively. The resolution of enantiomers on coupled achiral-chiral columns was R_s = 2.7. The solid-phase extraction method was employed for extraction and purification of analytes. The validated method was selective, accurate, and linear (R² > .998) over the concentration range of 0.001 to 1.0 mg cm⁻³ for both enantiomeric forms. The limits of detection (LOD) and quantitation (LOQ) of each enantiomer were 0.3 and 1.0 μg cm⁻³, respectively. The results demonstrated the occurrence of d -panthenol in hair care products.     

Regulation of root hair density by phosphorus availability in Arabidopsis thaliana

We characterized the response of root hair density to phosphorus (P) availability in Arabidopsis thaliana. Arabidopsis plants were grown aseptically in growth media with varied phosphorus concentrations, ranging from 1 mmol m⁻³ to 2000 mmol m⁻³ phosphorus. Root hair density (number of root hairs per mm of root length) was analysed starting at 7 d of growth. Root hair density was highly regulated by phosphorus availability, increasing significantly in roots exposed to low-phosphorus availability. The initial root hairs produced by the radicle were not sensitive to phosphorus availability, but began to respond after 9 d of growth. Root hair density was about five times greater in low phosphorus (1 mmol m⁻³) than in high phosphorus (1000 mmol m⁻³) media. Root hair density decreased logarithmically in response to increasing phosphorus concentrations within that range. Root hair density also increased in response to deficiencies of several other nutrients, but not as strongly as to low phosphorus. Indoleacetic acid (IAA), the auxin transport inhibitor 2-(p-chlorophenoxy)-2-methylpropionic acid (CMPA), the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), and the ethylene synthesis inhibitor amino-oxyacetic acid (AOA) all increased root hair density under high phosphorus but had very little effect under low phosphorus. Low phosphorus significantly changed root anatomy, causing a 9% increase in root diameter, a 31% decrease in the cross-sectional area of individual trichoblasts, a 40% decrease in the cross-sectional area of individual atrichoblasts, and 45% more cortical cells in cross-section. The larger number of cortical cells and smaller epidermal cell size in low phosphorus roots increased the number of trichoblast files from eight to 12. Two-thirds of increased root hair density in low phosphorus roots was caused by increased likelihood of trichoblasts to form hairs, and 33% of the increase was accounted for by changes in low phosphorus root anatomy resulting in an increased number of trichoblast files. These results show that phosphorus availability can fundamentally alter root anatomy, leading to changes in root hair density, which are presumably important for phosphorus acquisition.     

A new bioprocess for the production of prebiotic lactosucrose by an immobilized β-galactosidase

A new bioprocess for the synthesis of lactosucrose was studied using a covalently immobilized β-galactosidase on macrospheres of chitosan. The effects of temperature and pH on the production of lactosucrose and other oligosaccharides were evaluated. At 30 °C and pH 7.0, the maximum concentration of lactosucrose reached to 79 g L⁻¹. The change of the reaction conditions allowed to modify the qualitative profile of the final products without quantitative change in the total of oligosaccharides produced. At pH 7 and 30 °C, products profile was 79 g L⁻¹ of lactosucrose, 37 g L⁻¹ of galactooligosaccharides and 250 g L⁻¹ of total oligosaccharides, while at pH 5 and 64 °C the concentrations for the same compounds were 40, 62 and 250 g L⁻¹, respectively. The immobilization increased the thermal stability up to 260-fold. Using 300 g L⁻¹ of sucrose and 300 g L⁻¹ of lactose, and 8.5 mg of chitosan mL⁻¹, 30 cycles of reuse were performed and the biocatalyst kept the maximal lactosucrose synthesis. These results fulfill some important aspects for the enzyme immobilization and oligosaccharides synthesis: the simplicity of the protocols, the high operational stability of the enzyme and the possibility of driving the final products.     

Effects of temperature and stocking density on intensive culture of Pacific white shrimp in freshwater

In aquaculture, the application of predictive techniques based on statistical-mathematical modeling allows not only to project and study individual growth trajectories, but also to evaluate the probable effect of external factors that would explain their behavior over time. This is the case of this work, which takes the above as a principle to demonstrate the effect of water temperature on the growth of the Pacific white shrimp Litopenaeus vannamei cultured in fresh water (0 mg L⁻¹), using densities of 90, 120, 180, 230, 280 and 330 shrimp m⁻². Shrimp were exposed to water temperature between 11.5 °C and 31.6 °C. Temperature effect was determined using a parameterized Gompertz growth model with experimental data from each initial culture density. The best shrimp productivity yield was obtained above 26 °C, and the least efficient was below 22 °C. Densities of 90–180 shrimp m⁻² and 230–330 shrimp m⁻² generated a maximum average size of 12.6 g and 8.8 g in 30 weeks, respectively. Here we present the implications of the effect of water temperature on the intensive culture of white shrimp with zero salinity (0 mg L⁻¹) using these techniques from a predictive analytical approach.     

Hair cortisol detection in dairy cattle by using EIA: protocol validation and correlation with faecal cortisol metabolites

Hair may be a useful matrix to detect cumulative cortisol concentrations in studies of animal welfare and chronic stress. The aim of this study was to validate a protocol for cortisol detection in hair from dairy cattle by enzyme immunoassay (EIA). Seventeen adult Holstein–Friesian dairy cows were used during the milking period. Hair cortisol concentration was assessed in 25-day-old hair samples taken from the frontal region of the head, analysing black and white coloured hair separately. Concentrations of cortisol metabolites were determined in faeces collected twice a week during the same period of time. There was a high correlation between cortisol values in faeces and cortisol in white colour hair samples but such correlation was not significant with the black colour hair samples. The intra- and inter-assay coefficients of variation were 4.9% and 10.6%, respectively. The linearity showed R²=0.98 and mean percentage error of −10.8±1.55%. The extraction efficiency was 89.0±23.52% and the parallelism test showed similar slopes. Cortisol detection in hair by using EIA seems to be a valid method to represent long-term circulating cortisol levels in dairy cattle.     

Application of a white and green spectrofluorimetric approach for facile quantification of amlodipine,a hypotensive drug,in batch materials,dosage forms,and biological fluids; content homogeneity testing

The suggested study adheres to a particular protocol to ensure that the process is environmentally friendly and sustainable. It is worth mentioning that several tools have been adopted as prospective measures of the method greenness. Fortunately, the established analytical method is identified as white by the white analytical chemistry (WAC) concept, which uses the red/ green/blue color scheme (RGB 12 tool) to combine ecological and functional factors for the first time in studying of the cited drug. Amlodipine (AMD), a cardiovascular treating agent, belongs to the dihydropyridine class of oral calcium channel-blocking agents. This article presents a novel, simple, green, one-pot-processed, fast, and ultrasensitive fluorimetric approach for monitoring and assessment of AMD using molecular-size-dependent fluorescence augmentation of the light scattering-driven signal of eosin, a biological stain at a wavelength of 415 nm. This enhancement was directly proportional to the size of the produced complex. The linearity range was from 30 to 900 ng mL⁻¹, with corresponding sensitivity limits (detection and quantitation levels) of 9.2 and 28 ng mL⁻¹, respectively. The planned approach was also successfully used to track AMD content in bulk, dosage forms, and bio-fluids (human plasma and urine). The developed method's eco-friendliness was established by different eco-rating metric tools.     

Xylose fermentation by Candida shehatae and Pichia stipitis: effects of pH,temperature and substrate concentration

The effects of temperature, pH and xylose concentration on the fermentation parameters of Candida shehatae and Pichia stipitis were evaluated. The optimum pH was in the region of pH 4–5.5, with an optimum fermentation temperature of 30°C. Maximum fermentation rates were reached at 50 g l⁻¹ xylose. A maximum volumetric ethanol productivity of about 0.9 g (l h)⁻¹ was obtained with both yeast strains. The ethanol yield of C. shehatae decreased considerably when cultivated above 30°C or when the xylose concentration was increased. Xylitol accumulated concomitantly. Xylitol production by P. stipitis was observed only during cultivation at 36°C. Whereas the ethanol yield of C. shehatae was usually about 75% of the theoretical maximum, it was 85–90% with P. stipitis.