Removal of chlorophyll and pheophorbide from Chlorella pyrenoidosa by supercritical fluid extraction: potential of protein resource.

This study tried to quantitatively clarify the usefulness of supercritical fluid extraction for removal of chlorophyll and pheophorbide from Chlorella pyrenoidosa. C. pyrenoidosa powder was subjected to supercritical fluid extraction, and chlorophyll a and pheophorbide a in its extracted fractions were measured by HPLC-UV. Chlorophyll a and pheophorbide a in residue after supercritical fluid extraction became below of detection limit.

Correspondence between Spectral-Derived and Viscosity-Derived Local Composition in Binary Liquid Mixtures Having Specific Interactions with Preferential Solvation Theory.

Local interactions between unlike molecules (1-2) in solution are commonly measured with spectroscopy and used to estimate local composition. Herein, a viscosity model based on preferential solvation (PS) theory is developed for aqueous and nonaqueous binary liquid mixtures containing a dipolar aprotic solvent that provides local composition considering the hydration or solvation shell around complex (1-2) molecules. Spectral-derived and viscosity-derived local composition distributions showed similar trends with bulk composition, and their correspondence is attributed to characteristics of the hydration or solvation shell. Viscosity-derived local compositions were consistent with literature molecular simulations, whereas spectral-derived local composition distributions contained artifacts. The PS viscosity model is also applicable to nonpolar-polar mixtures for which self-association occurs, and it can be used to estimate solvent mixture dipolarity/polarizability. Since the PS viscosity model only requires bulk viscosity, it may provide a means to estimate microviscosity or the solvent environment around biomolecules.

Fractional Exhaled Nitric Oxide (FeNO) and Spirometry as Indicators of Inhalation Exposure to Chemical Agents in Pathology Workers.

OBJECTIVE: The objective of this study was to examine whether fractional exhaled nitric oxide (FeNO) and spirometry can be used as indices to evaluate adverse health effects of low-concentrated chemical inhalation exposure, mainly to formaldehyde. METHODS: Thirty-three subjects (pathology technicians) and 30 controls (workers without handling any chemicals in the same hospitals) participated in this study. All participants underwent FeNO measurement and spirometry before and after 5 days of work. RESULTS: FeNO significantly increased in the subjects with a history of asthma (P < 0.05), whereas forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) decreased in the subjects (P < 0.05). Furthermore, work duration and pre-work levels of FEV1 in the subjects had a significant association. CONCLUSION: The results suggest that FeNO, FVC, and FEV1 represent effective health-effect indices of low-concentrated chemical inhalation exposure.

Does Synergism in Microscopic Polarity Correlate with Extrema in Macroscopic Properties for Aqueous Mixtures of Dipolar Aprotic Solvents?

Aqueous mixtures of dipolar aprotic solvents (acetonitrile, γ-valerolactone, γ-butyrolactone, tetrahydrofuran, 1,4-dioxane, acetone, pyridine, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide) show synergism in microscopic polarity and extrema in macroscopic viscosity (η) and molar excess enthalpy (HE) in water-rich compositions that correlate with solvent functional group electrostatic basicity (ß2H). Microscopic polarities of aqueous solvent mixtures were estimated by measuring the spectral shift (λmax) of 4-nitroaniline with UV-vis spectroscopy at 25 °C. Dynamic viscosities (η) and densities were measured for eight aqueous dipolar aprotic mixtures over the full range of compositions at (25 to 45) °C. The λmax, η, and HE values of the aqueous mixtures showed a linear trend with increasing electrostatic basicity of the solvent functional groups that is attributed to the size and strength of the hydration shell of water. Density functional theory (DFT) calculations were performed for 1:3 complexes (solvent: (H2O)3) and it was found that aqueous mixtures with high basicity have high binding energies and short hydrogen bonding distances implying that the size and strength of the hydration shell of water is proportional to functional group basicity. Consideration of functional group basicity of dipolar aprotic solvents allows one to relate synergism in microscopic polarity to extrema in macroscopic properties for a wide range of aqueous dipolar aprotic solvent mixtures.

Extraction of nobiletin from Citrus Unshiu peels by supercritical fluid and its CRE-mediated transcriptional activity.

BACKGROUND: Polymethoxyflavone (PMF) is one of bioactive compounds in Citrus Unshiu and included mainly in the peels rather than the fruits, seeds and leaves. HYPOTHESIS/PURPOSE: Supercritical CO2 extraction is one candidate for selective extraction of polymethoxyflavone and in this study, supercritical CO2 extraction with/without ethanol entrainer from Citrus Unshiu peels was examined at a temperature of 333K and a pressure of 30MPa. METHODS: CRE (cyclic AMP response element)-mediated transcriptional assay was examined by using the extracts from supercritical fluid extraction. RESULTS: The results showed that extracts including nobiletin increased with increasing ethanol concentration in supercritical CO2 and the elapsed extraction time. Extracts at ethanol concentration of 5 mol% showed high CRE-mediated transcription activity. This can be caused by activity of the extract including nobiletin in addition to the other methoxylated flavonoid species such as tangeretin. Extracts at ethanol concentration of 50% showed the highest CRE-mediated transcription activity, which can be attributed to flavonoid glycoside such as hesperidin. From our investigations, flavonoid glycoside can be one of promoters of CRE-mediated transcription activity.

Nutrient recycle from defatted microalgae (Aurantiochytrium) with hydrothermal treatment for microalgae cultivation.

Defatted heterotrophic microalgae (Aurantiochytrium limacinum SR21) was treated with high temperature water (175-350°C, 10-90min) to obtain nitrogen and phosphorous nutrients as a water soluble fraction (WS). Yields of nitrogen and phosphorous recovered in WS varied from 38 to 100% and from 57 to 99%, respectively. Maximum yields of nitrogen containing compounds in WS were proteins (43%), amino acids (12%) and ammonia (60%) at treatment temperatures of 175, 250 and 350°C, respectively. Maximum yield of phosphorous in WS was 99% at a treatment temperature of 250°C. Cultivation experiments of microalgae (A. limacinum SR21) using WS obtained at 200 and 250°C showed positive growth. Water soluble fractions from hydrothermal treatment of defatted microalgae are effective nitrogen and phosphorous nutrient sources for microalgae cultivation.

A flow cell for measuring X-ray Compton scattering of liquid at temperatures up to 623 K and pressures up to 20 MPa.

A flow-type cell was developed for measuring Compton scattering spectra of heat-sensitive aqueous solution. Compton scattering spectra of water and ethanol were measured in the region from ambient conditions to 623 K and 20 MPa. Compton profiles derived from measurement with the flow-type cell were comparable with those in the literature. Results obtained from the flow-type cell showed that delocalization of electronic charge density of water and ethanol at high temperatures occurred. Delocalization of the electronic charge density of ethanol was greater than that of water at high temperature, which is consistent with the prior works that use proton NMR chemical shifts to describe hydrogen bonding.

Analysis of the Cybotactic Region of Two Renewable Lactone-Water Mixed-Solvent Systems that Exhibit Synergistic Kamlet-Taft Basicity.

Kamlet-Taft solvatochromic parameters (polarity, basicity, acidity) of hydrogen bond donor (HBD)/acceptor (HBA) mixed-solvent systems, water (H2O)-γ-valerolactone (GVL), methanol (MeOH)-GVL, ethanol (EtOH)-GVL, H2O-γ-butyrolactone (GBL), MeOH-GBL, and EtOH-GBL, were measured over their entire composition region at 25 °C using UV-vis spectroscopy. Basicity of H2O-GVL and H2O-GBL systems exhibited positive deviation from ideality and synergism in the Kamlet-Taft basicity values. The cybotactic region around each indicator in the mixed-solvent systems was analyzed with the preferential solvation model. Both H2O-GVL and H2O-GBL mixed-solvent systems were found to be completely saturated with mutual complex molecules and to have higher basicity than pure water because water prefers to interact with GVL or GBL molecules rather than with itself. Formation of H2O-GVL and H2O-GBL complex molecules via specific hydrogen bond donor-acceptor interactions were confirmed by infrared spectroscopy. In MeOH-GVL or MeOH-GBL mixed-solvent systems, MeOH molecules prefer self-interaction over that with GVL or GBL so that synergistic basicity was not observed. Synergistic basicity and basicity increase for various functional groups of ten mixed-solvent (water-HBA solvent) systems can be quantitatively explained by considering electrostatic basicity and a ratio of the partial excess HBA solvent basicity with the HBA solvent molar volume that correlate linearly with the preferential solvation model complex molecular parameter (f12/1). Analysis of the cybotactic region of indicators in aqueous mixtures with the preferential solvation model allows one to estimate the trends of mixed-solvent basicity.

Spectroscopic Analysis of Binary Mixed-Solvent-Polyimide Precursor Systems with the Preferential Solvation Model for Determining Solute-Centric Kamlet-Taft Solvatochromic Parameters.

Hydrogen bond donor/acceptor mixed-solvent systems for solutes that exhibit strong specific interactions are not readily characterized with methods that depend on solvatochromic parameters. In this work, the reaction of two monomers, 4,4'-oxidianiline (ODA) and pyromellitic dianhydride (PMDA), to form the common engineering plastic precursor, poly(amic acid) (PAA), are studied for the tetrahydrofuran (THF) mixed-solvent systems (THF-methanol, THF-ethanol, THF-water) with spectroscopy. Solute-centric (SC) Kamlet­Taft solvatochromic (K-T) parameters for the solvent environment around the monomer are determined using a proposed model that incorporates spectroscopically determined local composition (X(L)) around the ODA monomer and the preferential solvation model. For the example reaction to occur under homogeneous conditions, mixed-solvent conditions need have HBA-rich local compositions (0.30 < X(HBA)(L) < 0.83), high solute-centric basicity (ß(SC) > 0.60), high solute-centric polarity, (π(SC)* > 0.63), and low solute-centric acidity (α(SC) < 0.63). The method developed allows characterization of mixed-solvent effects and can be readily extended to other systems that have strong specific interactions.

Variation of photoautotrophic fatty acid production from a highly CO2 tolerant alga, Chlorococcum littorale, with inorganic carbon over narrow ranges of pH.

Photoautotrophic fatty acid production of a highly CO2 -tolerant green alga Chlorococcum littorale in the presence of inorganic carbon at 295 K and light intensity of 170 µmol-photon m(-2) s(-1) was investigated. CO2 concentration in the bubbling gas was adjusted by mixing pure gas components of CO2 and N2 to avoid photorespiration and ß-oxidation of fatty acids under O2 surrounding conditions. Maximum content of total fatty acid showed pH-dependence after nitrate depletion of the culture media and increased with the corresponding inorganic carbon ratio. Namely, [HCO3 (-) ]/([CO2 ]+n[ CO32-]) ratio in the culture media was found to be a controlling factor for photoautotrophic fatty acid production after the nitrate limitation. At a CO2 concentration of 5% (vol/vol) and a pH of 6.7, the fatty acid content was 47.8 wt % (dry basis) at its maximum that is comparable with land plant seed oils.

Effects of light intensity and temperature on photoautotrophic growth of a green microalga, Chlorococcum littorale.

A highly CO2-tolerant green alga, Chlorococcum littorale, was investigated at temperatures ranging from 8 to 28 °C, light intensities from 30 to 170 µmol m-2 s-1, a constant CO2 concentration of 5% (v/v) and atmospheric pressure. The experimental results showed that a specific growth rate µ, defined in terms of cell growth rate under a logarithmic growth phase, increased with temperature up to the maximum value (ca. 22 °C), while the µ decreased at higher temperatures. These promotion and inhibition of the cell growth rate were expressed by both a multiple linear regression and a mathematical model taking account of the Arrhenius activation/deactivation energies. Light intensity affected on the cell growth was independently treated in the mathematical model. The proposed growth model agreed well with the experimental data to within 6.6 %, which provides good correlation for both temperature and light intensity effects on the microalgal cell growth.

Direct C-H carboxylation with carbon dioxide using 1,2,3-triazol-5-ylidene copper(I) complexes.

1,2,3-Triazol-5-ylidene copper(I) complexes (tzNHC-Cu) efficiently catalyzed the direct C-H carboxylation of benzoxazole and benzothiazole derivatives with CO(2) to give the corresponding esters in excellent yields after treatment with alkyl iodide. The tzNHC copper(I) complex, i.e., [(TPr)CuCl], worked somewhat more effectively than the corresponding imidazol-2-ylidene copper(I) complex [(IPr)CuCl] to give the carboxylation product in higher yields.

Effects of nitrate and oxygen on photoautotrophic lipid production from Chlorococcum littorale.

Effects of oxygen and nitrate on fatty acid/lipid production from a highly CO(2)-tolerant microalgal species Chlorococcum littorale were examined under photoautotrophic conditions of 295 K, a light intensity of 170 µmol-photon m(-2) s(-1), a bubbling CO(2) concentration of 5% (v/v) and bubbling oxygen concentrations to be volumetrically adjusted by mixing oxygen gas with inert nitrogen gas at concentrations ranging from 0% to 95% (v/v). The results showed that maximum fatty acid content reached ca. 34 wt.% under oxygen-freely bubbling conditions and this value decreased to be ca. 20 wt.% when air-like oxygen concentration of 20% was chosen. This means that degree of the accumulation strongly depended on the level of bubbling oxygen concentrations, which can be a crucial factor after nitrogen depletion in the photoautotrophic culture system. TLC-FID/FPD analyses showed that triglycerides were found to be a dominant lipid class for this accumulation.

Carotenoid production from Chlorococcum littorale in photoautotrophic cultures with downstream supercritical fluid processing.

Carotenoid production from highly CO(2 )tolerant microalga Chlorococcum littorale in photoautotrophic cultures with downstream supercritical fluid processing was studied. Increasing temperature, increasing light intensity and decreasing CO(2) and O(2) gas concentrations enhanced growth rate under nitrate-rich conditions. Carotenoid content was insensitive to nitrate concentration, temperature and gas composition, but was greatly promoted by light intensity. Growth rate and carotenoid content had an optimum light intensity of ca. 120 micromol-photon * m(-2)s(-1). Separation of two sample cultures was studied by applying supercritical fluid extraction with CO(2 )and 10 mol% ethanol co-solvent. Extraction yield of carotenoids was 90% with 10 mol% ethanol at 333 K and 30 MPa. Selectivity of a sample with less lipid content (12.9 wt%) was five-fold higher than that with higher lipid content (29.4 w%).

Fatty acid production from a highly CO2 tolerant alga, Chlorocuccum littorale, in the presence of inorganic carbon and nitrate.

Photoautotrophic fatty acid production of a highly CO(2)-tolerant green alga Chlorococcum littorale was investigated in the presence of inorganic carbon and nitrate at 295 K and a light intensity of 170 micromol-photon m(-2) s(-1). CO(2) concentration in the bubbling gas was adjusted by mixing pure gas components of CO(2) and N(2) to avoid photorespiration and beta-oxidation of fatty acids under O(2) atmosphere conditions. Fatty acid content was almost constant for the CO(2) concentrations ranging from 5% to 50% under nitrate-rich conditions corresponding to the logarithmic growth phase. After nitrate depletion, the content drastically increased with a decrease in CO(2) concentration. HCO(3)(-)/CO(2) ratio in the culture media was found to be a controlling factor for fatty acid production after the nitrate limitation phase. For a CO(2) concentration of 5%, the fatty acid content was ca. 34 wt.% at maximum, which is comparable with other land plant seed oils.

Effect of inorganic carbon on photoautotrophic growth of microalga Chlorococcum littorale.

The growth rate of a highly CO(2)-tolerant green alga, Chlorococcum littorale, was investigated in semi-batch cultures at a temperature of 22 degrees C, a light intensity of 170 micromol-photon m(-2) s(-1) and CO(2) concentrations ranging from 1 to 50% (v/v) at atmospheric pressure. In the experiments, solutions were bubbled with CO(2) and N(2) gas mixtures to adjust CO(2) concentrations to minimize the influence of O(2). Growth rate, which was defined in terms of a specific growth rate mu, decreased with increasing CO(2) concentration at the conditions studied. The inhibition of growth by CO(2) gas could be attributed to the concentration of inorganic carbon in the culture medium. A growth model is proposed where key assumptions are the formation of bicarbonate ion HCO(3) (-) as substrate for algal growth and equilibrium between CO(2) inhibitor. The proposed growth model based on the Monod equation agreed with the experimental data to within 5% and provides better correlation than the conventional inhibition model, especially in the high CO(2) concentration region.

Reaction of cellulose-starch gel mixtures in water at high-temperatures and pressures for developing continuous batch microreactor systems.

Cellulose-starch gel mixtures (4 wt% cellulose and 4 wt% starch gel) were mixed with water in a 9:1, water:organic, volume ratios and rapidly heated (ca. 20s) to high-temperatures (ca. 520 degrees C) and high-pressures (ca. 800 MPa) in 0.04 microL microreactors to examine their characteristics and reaction products. Contents of the microreactors were observed during the heating with microscopy and residues were analyzed with chromatography and spectroscopy. At high water loading densities (ca. 980 kg/m(3)), heating of either starch gels or cellulose-starch gel mixtures gave a light yellow colored liquid associated with 5-hydroxymethylfurfural along with solid products that had strong absorptions at 1630 and 1530 cm(-1) associated with aromatic and polycyclic ring compounds. At low water loading densities (<700 kg/m(3)), a brown colored liquid was generated that had an oil-like, paraffinic hydrocarbon character along with gases, but no particles were formed. The cellulose-starch gels studied in this work can possibly be used as feedstocks in continuous batch microreactor systems.

Reaction chemistry and phase behavior of lignin in high-temperature and supercritical water.

Decomposition of organosolve lignin in water/phenol solutions was studied in a 50 nL micro-reactor coupled with optical, Raman and infrared microscopies at temperatures up to 600 degrees C and water densities up to 1165 kg/m3. It was found that when phenol was used with {lignin+water} mixtures that a homogenous phase was formed that seemed to promote the decomposition of lignin into phenolic fragments by hydrolysis and pyrolysis. Phenol, along with the homogenous reaction conditions also inhibited re-polymerization of the phenolics and promoted oil formation. On the other hand, in the absence of phenol, lignin remained as a heterogeneous phase with water over the range of conditions studied. The homogeneous conditions and conditions for inhibiting char formation by phenol were elucidated and it was found that mixtures of phenol and lignin become homogeneous at 400-600 degrees C and high water densities of 428-683 kg/m3, corresponding to maximum pressures of 93 MPa. These results were further used to propose reaction paths.