Production of ultrafine calcite particles by coccolithophorid algae grown in a biosolar reactor supplied with sunlight

Applied Biochemistry and Biotechnology - Ultrafine calcite particle production by coccolithophorid algae using a biosolar reactor system was carried out. Solar light was collected by Fresnel lenses...     

Microbial conversion of 4-oxoisophorone by thermomonospora curvata using an air-bubbling hollow fiber reactor

Microbial conversion of 4-oxoisophorone (OIP) by thermophilic bacteriumThermomonospora curvata was attempted in a continuous process. The correlation between cell growth and microbial conversion was first examined in a batch culture. The results indicated that this microbial conversion was strongly dependent upon cell growth. In a continuous microbial conversion of OIP using a continuous stirred tank reactor, the cell density in the reactor seemed to be the limiting factor in the OIP conversion. Therefore, we developed an air-bubbling hollow fiber reactor to achieve a high density culture. By using this bioreactor, more than 3.3 times higher productivity was achieved. In addition, during the process, only a slight cell contamination to the product was observed. Therefore, this bioreactor is suitable for the continuous microbial conversion, considering further downstream processes and high productivity.     

Ethanol production from corn starch in a fluidized-bed bioreactor

The production of ethanol from industrial dry-milled corn starch was studied in a laboratory-scale fluidized-bed bioreactor using immobilized biocatalysts. Saccharification and fermentation were carried out either simultaneously or separately. Simultaneous saccharification and fermentation (SSF) experiments were performed using small, uniform κ-carrageenan beads (1.5–2.5 mm in diameter) of co-immobilized glucoamylase and Zymomonas mobilis. Dextrin feeds obtained by the hydrolysis of 15% drymilled corn starch were pumped through the bioreactor at residence times of 1.5–4h. Single-pass conversion of dextrins ranged from 54–89%, and ethanol concentrations of 23–36 g/L were obtained at volumetric productivities of 9–15 g/L-h. Very low levels of glucose were observed in the reactor, indicating that saccharification was the rate-limiting step. In separate hydrolysis and fermentation (SHF) experiments, dextrin feed solutions of 150–160 g/L were first pumped through an immobilized-glucoamylase packed column. At 55°C and a residence time of 1 h, greater than 95% conversion was obtained, giving product streams of 162–172 g glucose/L. These streams were then pumped through the fluidized-bed bioreactor containing immobilized Z. mobilis. At a residence time of 2 h, 94% conversion and ethanol concentration of 70 g/L were achieved, resulting in an overall process productivity of 23 g/L-h. Atresidence times of 1.5 and 1 h, conversions of 75 and 76%, ethanol concentrations of 49 and 47 g/L, and overall process productivities of 19 and 25 g/L-h, respectively, were achieved.     

便携式微型液相色谱仪的研制

该工作报道了一种自行设计研制的便携式微型液相色谱仪(portable micro liquid chromatograph, p-μLC)。p-μLC集成了二元大推力注射泵作为流动相驱动装置、毛细管整体柱为分离介质和紫外-可见/荧光两用流通池为在线检测单元。自行设计研制的二元大推力注射泵可以实现等度/梯度洗脱和流动相再装填功能,可控流速范围在0.025 μL/min到5.6 mL/min之间;自制的甲基丙烯酸酯C-18有机聚合物毛细管整体微柱可实现自有机小分子至生物大分子的分离;自行研制的光纤式紫外-可见/荧光两用流通池,可以通过光纤导入来自光源的紫外光和可见光,并采集透射光和与入射光反方向射出的荧光信号,流通池内使用自聚焦透镜和全反射光导毛细管等器件提高通光效率和吸收光程;两用流通池通过光纤分别连接由大功率发光二极管/脉冲氙灯光源和微型光栅光谱仪所组成的检测装置进行在线吸收和荧光光谱检测,检测波长范围为220~700 nm。p-μLC采用整体手提箱式结构,流路模块、检测模块等位于下主箱体中,采集、控制模块等位于上盖中,全重不超过8 kg。仪器由装载了自编控制采集软件的内置平板电脑进行控制和数据采集。使用自行制备的甲基丙烯酸酯C-18有机聚合物毛细管整体柱,在等度洗脱模式下,在p-μLC上分离了烷基苯化合物混合样品,其分离检测效果可以与商品化大型HPLC仪器相媲美。     

CO2 removal by high-density culture of a marine cyanobacterium synechococcus sp. using an improved photobioreactor employing light-diffusing optical fibers

A light diffusing optical fiber (LDOF) photobioreactor with an improved gas input system has been used for the high-density culture of a marine cyanobacterium Synechococcus sp. Optimum conditions for CO2 removal and biomass production were investigated. Maximum CO2 removal of 4.44 g/L/d was achieved using an initial cell concentration of 6.8 g/L. The biomass yield was 0.97 g/L for a 12-culture time. Continuous cultures, in which medium was filtered using a ceramic membrane module, showed enhanced growth, with a final cell concentration of 11.2 g/L. These results demonstrate the potential of LDOF photobioreactor units for CO2 removal and biomass production using marine cyanobacteria.

     

Hydrogen Production from Methane Through Pulsed DC Plasma

A non-equilibrium warm plasma reactor has been constructed for methane reforming and hydrogen production. The discharge reactor was derived with 20 kV pulsed DC power supply with pulse duration of 4 µs, pulse frequency of 33 kHz. Electrical and optical characterizations of the reactor have been investigated. The electrical characteristics of the discharge revealed that the discharge was ignited by streamer to glow transition. The optical characteristics of the discharge revealed that the discharge was found to be strongly non-equilibrium with rotational temperature (T_rot) of 2873 K and vibrational temperature (T_vib) of 12,130 K. The Stark broadening of the emitted H_α line profile was used to deduce the electron density, which was found to be in the order of 10¹⁶ cm^?3. Methane conversion was strongly dependent upon the applied voltage and the methane flow rate. In general, under the specified operating condition, a methane conversion percentage of about 92% and a maximum hydrogen selectivity of 44.6% have been achieved. Specific energy consumption of methane conversion (SEC) and specific energy requirements for hydrogen formation (SER) of 5 eV/molecule has been achieved simultaneously with a maximum hydrogen production energy cost of about 3.8 µg/J. Finally, the decomposition of methane gas resulted in the deposition of an important byproduct namely graphene oxide.     

Light-emitting-diode-induced fluorescence detector for capillary electrophoresis using optical fiber with spherical end

A simple fluorescence detector for capillary electrophoresis (CE) using a blue light-emitting-diode (LED) as excitation source is constructed and evaluated. An optical fiber was used to collect the fluorescence, and a flat end of the fiber was modified to spherical end, resulting in 50% increase of efficiency over the flat end. A simple device for optical alignment of the fibers and capillary column was designed. The concentration and mass detection limits for fluorescein were 1.8×10⁻⁷ mol l⁻¹ and 4.3 femol, respectively.     

发光二极管诱导荧光用于毛细管电泳检测

利用发光二极管作为激发光源，组装了用于毛细管电泳的荧光检测器。光纤用于传输荧光信号；光纤端面修饰成球形使耦合效率比平面端光纤提高了50．8％；光阑、光纤及毛细管检测池之间的光学校准简单、便捷。荧光素染料用于评价该体系性能，得到了fmol的质量检出限。     

Evaluation of a membrane-sparged helical tubular photobioreactor for carbon dioxide biofixation by Chlorella vulgaris

A membrane-sparged helical tubular photobioreactor (MSTR) with a cultivation volume of 800 ml was designed in this study. It consisted of a cylindrical-shaped light receiver and a mass transfer system. A helical tube was used to ensure good light regime, and hollow fiber membranes were uniformly fitted inside the reactor, which functioned as a gas sparger and produced small bubbles. Mass transfer coefficients, mixing intensities and capabilities of CO₂ biofixation through the photosynthesis of Chlorella vulgaris in MSTR under different gas, liquid flow rates and light intensities were compared with two other photobioreactors (BCTR and MCTR). BCTR took a perforated pipe as sparger, while MCTR employed a membrane contactor as the whole mass transfer system. To establish if the limitation of CO₂ removal was improved in MSTR, pH, dissolved oxygen, cell damage, and characteristic times for mixing, mass transfer and CO₂ consumption were analyzed during batch culture.     

Single fiber-in-capillary annular column for gas chromatographic separation

A method for preparation of a stationary phase-adjustable column with in-column stationary phase-coated fused-silica fiber annular column was successfully developed. The surface of a 0.12 mm o.d. bare optical fiber was first coated with a stationary phase and then inserted into a fused-silica capillary (non-coated or coated) as an annular column for gas chromatographic study. The optical fiber and capillary were coated with polydimethylsiloxane (SE-30) and polyethylene glycol 20M (PEG-20M) as nonpolar and polar stationary phases, respectively. Among the investigated annular and open tubular columns, the PEG-20M-coated fiber-in-PEG-20M-coated capillary annular column showed the highest column efficiency with a minimum plate height of 0.35 mm and an optimum gas velocity of 25 cm/s. When a SE-30/PEG-20M-coated fiber-in-uncoated capillary annular column was applied to separate a 9-component complex mixture, the total analysis time was 5.3 min and the column length was 12 m. By contrast, when a SE-30-coated fiber-in-PEG-20M-coated capillary annular column was used to separate the same 9-component mixture, the analysis time was reduced to 3.5 min and the column length was shortened by half to 6 m. Our results show that the stationary phase-coated fiber-in-stationary phase-coated capillary annular column is a better choice for gas chromatographic separation as it is more efficient and flexible. In addition, the proposed annular column design provides flexibility in using two or even more types of stationary phases to achieve optimal analytical separation.     

Direct C−H Trifluoromethylation of (Hetero)Arenes in Water Enabled by Organic Photoredox-Active Amphiphilic Nanoparticles

Photoredox-catalyzed chemical conversions are predominantly operated in organic media to ensure good compatibility between substrates and catalysts. Yet, when conducted in aqueous media, they are an attractive, mild, and green way to introduce functional groups into organic molecules. We here show that trifluoromethyl groups can be readily installed into a broad range of organic compounds by using water as the reaction medium and light as the energy source. To bypass solubility obstacles, we developed robust water-soluble polymeric nanoparticles that accommodate reagents and photocatalysts within their hydrophobic interior under high local concentrations. By taking advantage of the high excited state reduction potential of N-phenylphenothiazine (PTH) through UV light illumination, the direct C−H trifluoromethylation of a wide array of small organic molecules is achieved selectively with high substrate conversion. Key to our approach is slowing down the production of CF₃ radicals during the chemical process by reducing the catalyst loading as well as the light intensity, thereby improving effectiveness and selectivity of this aqueous photocatalytic method. Furthermore, the catalyst system shows excellent recyclability and can be fueled by sunlight. The method we propose here is versatile, widely applicable, energy efficient, and attractive for late-stage introduction of trifluoromethyl groups into biologically active molecules.     

Compact polytetrafluoroethylene assembly-type capillary electrophoresis with chemiluminescence detection

We have developed a compact polytetrafluoroethylene (PTFE) assembly-type capillary electrophoresis with chemiluminescence (CL) detection system. Luminol-microperoxidase-hydrogen peroxide chemiluminescence reaction was adopted. The device is rectangular in shape (60 mm x 40 mm x 30 mm) and includes three reservoirs (sample, migration buffer, and detection reservoirs) with electrodes. The detection reservoir includes an optical fiber to transport light at the capillary tip to a photomultiplier tube. Isoluminol isothiocyanate (ILITC) was analyzed as a model using this device with fused-silica or polytetrafluoroethylene capillary tubes 10 cm in length. We also used the sample reservoir as a reactor for an immune reaction between anti-human serum albumin immobilized on glass beads and isoluminol isothiocyanate-labeled human serum albumin. The present polytetrafluoroethylene assembly with the capillary tube was useful as a palm-sized analysis device for separation and detection, as well as a reactor.     

Photocatalytic Reduction of Greenhouse Gas CO2 to Fuel

Sun is the Earth’s ultimate and inexhaustible energy source. One of the best routes to remedy the CO₂ problem is to convert it to valuable hydrocarbons using solar energy. In this study, CO₂ was photocatalytically reduced to produce methanol, methane and ethylene in a steady-state optical-fiber reactor under artificial light and real sunlight irradiation. The photocatalyst was dip-coated on the optical fibers that enable the light to transmit and spread uniformly inside the reactor. The optical-fiber photoreactor, comprised of nearly 120 photocatalyst-coated fibers, was designed and assembled. The XRD spectra indicated the anatase phase for all photocatalysts. It is found that the methanol yield increased with UV light intensity. A maximum methanol yield of 4.12 μmole/g-cat h is obtained when 1.0 wt% Ag/TiO₂ photocatalyst was used under a light intensity of 10 W/cm². When mixed oxide, TiO₂–SiO₂, is doped with Cu and Fe metals, the resulting photocatalysts show substantial difference in hydrocarbon production as well as product selectivity. Methane and ethylene were produced on Cu–Fe loaded TiO₂–SiO₂ photocatalyst. Since dye-sensitized Cu–Fe/P25 photocatalyst can fully harvest the light energy of 400–800 nm from sunlight, its photoactivity was significantly enhanced. Finally, CO₂ photoreduction was studied by in situ IR spectroscopy and possible mechanism for the photoreaction was proposed.     

Pretreatment of corn fiber by pressure cooking in water

The pretreatment of corn fiber using liquid water at temperatures between 220 and 260°C enhances enzymatic hydrolysis. This paper describes the laboratory reactor system currently in use for cooking of corn fiber at temperatures ranging from 200 to 260°C. The corn fiber at approx 4.4% solid/liquid slurry was treated in a 2-L, 304 SS, Parr reactor with three turbine propeller agitators and a Proportional-Integral-Derivative (PID), controller that controlled temperature within ±1°C. Heat-up times to the final temperatures of 220, 240, or 260°C were achieved in 50 to 60 min. Hold time at the final temperature was less than 10 s. A serpentine cooling coil, through which tap water was circulated at the completion of the run, cooled the reactor’s contents to 180°C within 2 min after the maximum temperature was attained. Ports in the reactor’s head plate facilitated sampling of the slurry and monitoring the pH. A continuous pH monitoring system was developed to help observe trends in pH during pretreatment and to assist in the development of a base (2.0M KOH) addition profile to help keep the pH within the range of 5.0 to 7.0. Enzymatic hydrolysis gave 33 to 84% conversion of cellulose in the pretreated fiber to glucose compared to 17% for untreated fiber.     

Mode-filtered light methane gas sensor based on cryptophane A

A mode-filtered light sensor has been developed for methane (CH₄) gas determination at ambient conditions. The proposed chemosensor consisted of an annular column which was constructed by inserting an optical fiber coated with a thin silicone cladding of cryptophane A into a fused-silica capillary. When CH₄ was introduced to the sensor, selective inclusion of CH₄ into the silicone layer would cause a change in the local refractive index of the cladding, resulting in the change of mode-filtered light that emanated from the fiber. Three detection windows were set alongside the capillary to propagate the light to a charge-coupled device (CCD). The changes of mode-filtered light on exposure to various concentrations of CH₄ were thus simultaneously monitored. The mode-filtered light intensity decreased with the increase in concentration of CH₄. The dynamic concentration range of the sensor for CH₄ was 0.0-16.0% v/v with a detection limit of 0.15% v/v. The highest sensitivity was found at the channel furthest away from the excitation light source. The response time (t_95%) was about 5 min. The reproducibility was good with a relative standard deviation (RSD) of less than 7% from evaluating six cryptophane A-coated fibers. Oxygen, hydrogen and carbon dioxide showed very little interference on detection but interferences from dichloromethane and carbon tetrachloride were observed. The proposed mode-filtered light sensor has been successfully applied to determine CH₄ samples and the accuracy was good. Our work offers a promising approach for CH₄ detection.     

Sensitivity enhancement of fluorescence detection in CE by coupling and conducting excitation light with tapered optical fiber

This paper reports the enhancement of sensitivity of detection for in‐column fiber optic‐induced fluorescence detection system in CE by tapered optical fiber (TOF). Two types of optical fiber, TOF and conventional cylindrical optical fiber (COF), were employed to construct the CE (TOF‐CE and COF‐CE) and were compared for sensitivity to riboflavin (RF). The fluorescence intensities from a RF sample with excitation light sources and fibers at various coupling angles were investigated. The fluorescence signal from TOF‐CE was ca. ten times that of COF‐CE. In addition, the detection performance of four excitation light source‐fiber configurations including Laser‐TOF, Laser‐COF, LED‐TOF, and LED‐COF were compared. The LODs for RF were 0.21, 0.82, 0.80, and 7.5 nM, respectively, for the four excitation light source–fiber configurations. The results demonstrate that the sensitivity obtained by LED‐TOF is close to that of Laser‐COF. Both Laser‐TOF and LED‐TOF can greatly improve the sensitivity of detection in CE. TOF has the major attribute of collecting and focusing the excitation light intensity. Thus, the sensitivity obtained by LED‐TOF without focusing lens is just same as that of LED‐COF with a focusing lens. This demonstrates that the CE system can be further simplified by eliminating the focusing lens for excitation light. LED‐TOF‐CE and LED‐COF‐CE system were applied to the separation and determination of RF in real sample (green tea), respectively. The tapered fiber optic‐induced fluorescence detection system in CE is an ideal tool for trace analysis.     

OPTIMIZATION OF MULTIFIBER LIGHT DELIVERY FOR THE PHOTODYNAMIC THERAPY OF LOCALIZED PROSTATE CANCER

The understanding of light distribution within the target organ is essential in ensuring efficacy and safety in photodynamic therapy (PDT). A computer simulator of light distribution in prostatic tissue was employed for optimizing dosimetry for PDT in localized prostatic cancer. The program was based on empirically determined light distributions and optical constants and an assumed Ruence rate differential from fiber source to necrosis periphery. The diffusion theory approximation to the Boltzmann transport equation was the applicable formulation relevant to prostatic tissue, which has a high albedo with forward-scattering characteristics. Solving this equation of diffusive transfer for the appropriate fiber geometry yielded the energy fluence distributions for cleaved fiber and cylindrical diffuser light delivery. These distributions, confirmed by our measurements, show a l/r and l/r dependency (r = distance from light source) of the fluence ø(r) for the cleaved fiber and diffuser, respectively. This manifests itself by the tighter spacing of energy fluence isodoses in the case of the cleaved fiber. It was predicted that for a typical PDT regime a single interstitially placed cleaved fiber would treat 0.05–0.72 cm³, Four parallel fibers improve the uniformity of light distribution and treatment volume, and an interfiber separation of 12 mm would be necessary to provide optimal overlap of PDT necrosis, treating 0.26–3.6 cm³. The cylindrical diffuser, however, could treat larger volumes, and it was predicted that four 3 cm long diffusers at an optimal separation of 25 mm would treat 25–88 cm³ of prostatic tissue.     

Open tube combustion method of organic samples for stable carbon isotope analysis

A simple and effective method for the conversion of organic carbon into carbon dioxide for analysis of stable carbon isotopes (delta(13)C) in samples of various organic substances, soils, sedimentary rocks, oils and volatile organic liquids is presented. The conversion of organic carbon of the samples is carried out in a quartz reactor connected to a vacuum line for CO(2) freezing and purification. A solid organic sample mixed with CuO is placed at the reactor bottom and the reactor is subsequently filled with granular CuO. One end of the CuO column is preheated to 850 degrees C while the other end of the column in contact with the sample is kept at ambient temperature. Heating of the sample (850 degrees C) and the remainder of the column is then performed. The preheated part of the column provides efficient conversion of carbon into CO(2). The reactor for the conversion of volatile liquid organic compounds is filled with granular CuO. The column of CuO is heated to 850 degrees C. Samples of volatile liquids are introduced into the reactor through a septum using a microsyringe. Complete conversion takes 10 min for solid samples and 3 min for volatile liquids. The precision of the delta(13)C analysis for solid and volatile liquid organic substances is +/-0.1 per thousand and +/-0.04 per thousand, respectively.     

Optimization of medium by orthogonal matrix method for submerged mycelial culture and exopolysaccharide production in Collybia maculata

Optimization of submerged culture conditions for the production of mycelial growth and exopolysaccharides (EPSs) by Collybia maculata was investigated. The optimum temperature and the initial pH for EPS production in a shake-flask culture of C. maculata were found to be 20°C and 5.5, respectively. Among the various medium’s constituents examined, glucose, Martone A-1, K₂HPO₄, and CaCl₂ were the most suitable carbon, nitrogen, and mineral sources for EPS production, respectively. The optimum concentration of the medium’s ingredients determined using the orthogonal matrix method was as follows: 30 g/L of glucose, 20 g/L of Martone A-1, 1g/L of K₂HPO₄, and 1g/L of CaCl₂. Under the optimized culture conditions, the maximum concentration of EPSs in a 5-L stirred-tank reactor was 2.4 g/L, which was approximately five times higher than that in the basal medium. A comparative fermentation result showed that the EPS productivity in an airlift reactor was higher than that in the stirred-tank reactor despite the lower mycelial growth rate. The specific productivities and the yield coefficients in the airlift reactor were higher than those in the stirred-tank reactor even though the volumetric productivities were higher in the stirred-tank reactor than in the airlift reactor.     

Use of an on-line,precolumn photochemical reactor in high-performance liquid chromatography of naphthodianthrones in Hypericum perforatum preparations

A method has been developed for the determination of naphthodianthrones in Hypericum perforatum L. extracts and phytopharmaceutical preparations by high-performance liquid chromatography combined with on-line, precolumn photochemical conversion followed by photodiode-array detection. The chromatographic separation was performed on a C18 column under isocratic reversed-phase conditions. An on-line, precolumn photochemical reactor equipped with a knitted PTFE reaction coil around a visible light source was used in order to transform the light sensitive naphthodianthrones, protohypericin and protopseudohypericin, very easily into the non-protoforms, hypericin and pseudohypericin, respectively. Two UV chromatograms (photochemical reactor "on" and "off") were compared and were quite useful in characterizing the sample. Validation studies demonstrated that this HPLC method is simple, rapid, reliable and reproducible. The time-consumptive manual irradiation of the samples is omitted by this automated on-line irradiation step. The developed method was successfully applied to the quality control of Hypericum perforatum L. extracts and its phytopharmaceutical preparations.