Antioxidative Responses of Two Marine Microalgae During Acclimation to Static and Fluctuating Natural UV Radiation

Photoacclimation properties were investigated in two marine microalgae exposed to four ambient irradiance conditions: static photosynthetically active radiation (PAR: 400–700 nm), static PAR + UVR (280–700 nm), dynamic PAR and dynamic PAR + UVR. High light acclimated cultures of Thalassiosira weissflogii and Dunaliella tertiolecta were exposed outdoors for a maximum of 7 days. Dynamic irradiance was established by computer controlled vertical movement of 2 L bottles in a water filled basin. Immediate (<24 h), short-term (1–3 days) and long-term (4–7 days) photoacclimation was followed for antioxidants (superoxide dismutase, ascorbate peroxidase and glutathione cycling), growth and pigment pools. Changes in UVR sensitivity during photoacclimation were monitored by measuring UVR-induced inhibition of carbon assimilation under standardized UV conditions using an indoor solar simulator. Both species showed immediate antioxidant responses due to their transfer to the outdoor conditions. Furthermore, upon outdoor exposure, carbon assimilation and growth rates were reduced in both species compared with initial conditions; however, these effects were most pronounced in D. tertiolecta . Outdoor UV exposure did not alter antioxidant levels when compared with PAR-only controls in both species. In contrast, growth was significantly affected in the static UVR cultures, concurrent with significantly enhanced UVR resistance. We conclude that antioxidants play a minor role in the reinforcement of natural UVR resistance in T. weissflogii and D. tertiolecta .     

Light Regime Characterization in an Airlift Photobioreactor for Production of Microalgae with High Starch Content

The slow development of microalgal biotechnology is due to the failure in the design of large-scale photobioreactors (PBRs) where light energy is efficiently utilized. In this work, both the quality and the amount of light reaching a given point of the PBR were determined and correlated with cell density, light path length, and PBR geometry. This was made for two different geometries of the downcomer of an airlift PBR using optical fiber technology that allows to obtain information about quantitative and qualitative aspects of light patterns. This is important since the ability of microalgae to use the energy of photons is different, depending on the wavelength of the radiation. The results show that the circular geometry allows a more efficient light penetration, especially in the locations with a higher radial coordinate (r) when compared to the plane geometry; these observations were confirmed by the occurrence of a higher fraction of illuminated volume of the PBR for this geometry. An equation is proposed to correlate the relative light intensity with the penetration distance for both geometries and different microalgae cell concentrations. It was shown that the attenuation of light intensity is dependent on its wavelength, cell concentration, geometry of PBR, and the penetration distance of light.     

Research on Ice Crystal Growth Inside the Vitrified Vs55 with Magnetic Nanoparticles During Devitrification by Cryomicroscopy

The effect of magnetic nanoparticles(mNPs) on the devitrification crystallization of typical vitrification solution Vs55 was systematically explored by differential scanning calorimetry(DSC) and cryomicroscope system. The results show tliat,(i) the mNPs coated by both carboxylic acid(CA) and polyethylene glycol(PEG) had little effect on the glass transition temperature(rg) of Vs55, but had significant effect on the devitrification transition temperature(7a) and devitrification enthalpy(Hrd),(ii) in the range of the devitrification area(-85- 0℃), the MNPs coated by CA can significantly accelerate the devitrification of Vs55 as the isothermal temperatures and the cooling rates increased, and the ice growth rate was 0.37 p.m/s at the isothermal temperature of-85 ℃, and was about 2.19 gm/s at -75℃. Also, the ice growth rates rose from 1.72 pm/s to 3.54 pm/s when the cooling rates were increased from 2 ℃/min to 100 ℃/min(at the isothennal temperature of -75℃),(iii) magnetic nanoparticles coated by both PEG and CA could promote the devitrification of Vs55, for instance, without any crystal growth inside Vs55 at the isothermal temperature of-80℃, but 1.04 and 2.31 gm/s for adding magnetic nanoparticles coated by CA and PEG, respectively. Compared with the samples coated by CA, PEG promoted the devitrification of Vs55 in a much more positive way, and the ice growth rates were 0.62 and 6.25 μm/s at the isothermal temperatures of -85 and -75 ℃, respectively. Tliese results indicate that the surface coating of MNPs could significantly affect tlie recrystallization of Vs55, and further work should be conducted in the future research.     

Effect of UVB Radiation on Utilization of Inorganic Nitrogen by Antarctic Microalgae

Abstract— The impact of UVB (280-315 nm) radiation (WG 305) on uptake of ¹⁵N-ammonium and ¹⁵N-nitrate of marine phytoplankton from station 219 (47°W, 61.5°S) and sea ice-algae from station 265 (22.6°W, 73.29°S) was studied during the Polarstern Cruise (EPOS III, Leg 3) to the Weddell Sea, Antarctica 1989. Uptake rates of ¹⁵NH₄⁺ were higher and more affected by UVB radiation than those of ¹⁵N0₃-. Pool sizes of the main amino acids changed in response to the used inorganic nitrogen source and UV exposure. Pools of glutamine, serine and glycine decreased, whereas those of alanine, asparagine and glutamate increased after UVB irradiation. The ¹⁵N-incorporation into the amino acids was reduced as a result of UVB exposure of phytoplankton and ice algae. Results are discussed with reference to an inhibitory effect on the enzymes of both carbon and nitrogen metabolism as well as to adaptation strategies.     

石墨管内被测原子间的平衡关系

本文探讨了石墨管内被测原子间的平衡关系,从理论上推导了基态原子数与吸光度之间的系数β,计算了部分元素的理论特征量N值.     

Cultivating <Emphasis Type="BoldItalic">Chlorella</Emphasis> sp. in a Pilot-Scale Photobioreactor Using Centrate Wastewater for Microalgae Biomass Production and Wastewater Nutrient Removal

This study is concerned with a novel mass microalgae production system which, for the first time, uses “centrate”, a concentrated wastewater stream, to produce microalgal biomass for energy production. Centrate contains a high level of nutrients that support algal growth. The objective of this study was to investigate the growth characteristics of a locally isolated microalgae strain Chlorella sp. in centrate and its ability to remove nutrients from centrate. A pilot-scale photobioreactor (PBR) was constructed at a local wastewater treatment plant. The system was tested under different harvesting rates and exogenous CO₂ levels with the local strain of Chlorella sp. Under low light conditions (25 μmol·m^-2s^-1) the system can produce 34.6 and 17.7 g·m^-2day^-1 biomass in terms of total suspended solids and volatile suspended solids, respectively. At a one fourth harvesting rate, reduction of chemical oxygen demand, total Kjeldahl nitrogen, and soluble total phosphorus were 70%, 61%, and 61%, respectively. The addition of CO₂ to the system did not exhibit a positive effect on biomass productivity or nutrient removal in centrate which is an organic carbon rich medium. The unique PBR system is highly scalable and provides a great opportunity for biomass production coupled with wastewater treatment.     

Screening,Growth Medium Optimisation and Heterotrophic Cultivation of Microalgae for Biodiesel Production

This article presents a study on screening of microalgal strains from the Peking University Algae Collection and heterotrophic cultivation for biodiesel production of a selected microalgal strain. Among 89 strains, only five were capable of growing under heterotrophic conditions in liquid cultures and Chlorella sp. PKUAC 102 was found the best for the production of heterotrophic algal biodiesel. Composition of the growth medium was optimised using response surface methodology and optimised growth conditions were successfully used for cultivation of the strain in a fermentor. Conversion of algal lipids to fatty acid methyl esters (FAMEs) showed that the lipid profile of the heterotrophically cultivated Chlorella sp. PKUAC 102 contains fatty acids suitable for biodiesel production.     

Growth of Microalgae in High CO2 Gas and Effects of SOX and NOX

Growth and lipid production of microalgae were investigated, with attention to the feasibility of making use of flue gas CO₂ as a carbon source. The effect of a high CO₂ level in artificial seawater differed from strain to strain. Three algal strains from the Solar Energy Research Institute (Golden, CO) collection were selected as good fixers of CO₂ when the level of CO₂ in the sparging gas was high. These algae also accumulated large amounts of crude lipids. SO_X and NO_X inhibited algal growth, but a green alga,Nannochloris sp. NANNO2 grew after a lag period, even when it received NO gas at the concentration of 300 ppm.     

广义簇合物在非均匀几率密度下的生长

采用族合物生长的自调整模型，并用扩散粒子的非均匀几率密度场模拟了簇合物和扩散粒子之间的非均匀相互作用势场,研究了广义簇合物在非均匀场下的生长形态，考察了深度因子α、粘附参数t等对簇合物生长形态及对非均匀场的影响，结果表明，非均匀场的性质是决定族合物生长几何形态的主要因素，深度因子α决定了簇合物中生长形态的紧密程度，粘附参数t决定了致密程度，α、t等参数对场的作用有一定的影响     

广义簇合物在均匀几率密度场下的生长

通过对广义簇合物生长的自调整模型的解析,得出了粒子在均匀几率密度场下簇合物生长形态的变化特征,揭示了表征其生长形态结构分式维数D的物理意义,同时考查了格子模型对簇合物生长形态的影响以及自调整模型的动力学行为。     

亚心形四爿藻培养和产氢过程一体化平板光生物反应系统

利用整合了燃料电池的平板光生物反应器, 探讨了将亚心型四爿藻高密度培养和产氢两段工艺一体化集成的可行性. 在培养阶段通入体积分数为2%~5%的CO2可使藻细胞迅速增殖, 9 d内即可达到产氢要求的生物量(8.5×106 cell/mL). 通过叶绿素荧光参数分析, 选择2%的CO2培养的藻进行后续的产氢实验. 结果表明, PSⅡ活性和光合电子传递速率均随时间的推移而逐渐下降. 通过对产氢动力学曲线的分析, 计算出最大产氢速率为1.1 mL/(h·L), 持续产氢时间为60 h.     

金纳米粒子的阳光光化学合成和晶种媒介生长

在柠檬酸盐-HAuCl4溶液体系中, 于高原太阳紫外线辐射下光化学合成了分散良好、尺寸分布窄的胶体金纳米粒子. 研究了溶液的酸度和太阳辐射条件对Au(Ⅲ)离子光化学还原反应速率和形成金纳米粒子尺寸的影响; 采用晶种媒介生长技术, 通过改变Au(0)/Au(Ⅲ)比合成了平均直径为4.9~9.7 nm的球形金粒子. 根据紫外-可见吸收光谱和透射电子显微镜的表征和分析, 讨论了光化学反应中自由基反应、金纳米粒子成核和生长机理.     

Microalgae as a Source of Valuable Phenolic Compounds and Carotenoids

Microalgae are photosynthetic, eukaryotic organisms that are widely used in the industry as cell factories to produce valuable substances, such as fatty acids (polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), sterols (sitosterol), recombinant therapeutic proteins, carbohydrates, vitamins, phenolic compounds (gallic acid, quercetin), and pigments (β-carotene, astaxanthin, lutein). Phenolic compounds and carotenoids, including those extracted from microalgae, possess beneficial bioactivities such as antioxidant capacity, antimicrobial and immunomodulatory activities, and direct health-promoting effects, which may alleviate oxidative stress and age-related diseases, including cardiovascular diseases or diabetes. The production of valuable microalgal metabolites can be modified by using abiotic stressors, such as light, salinity, nutrient availability, and xenobiotics (for instance, phytohormones).     

Measurement of Reactive Hydroxyl Radical Species Inside the Biosolutions During Non-thermal Atmospheric Pressure Plasma Jet Bombardment onto the Solution

Non-thermal atmospheric pressure plasma jet could generate various kinds of radicals on biosolution surfaces as well as inside the biosolutions. The electron temperature and ion density for this non-thermal plasma jet have been measured to be about 0.8~1.0 eV and 1 × 10¹³ cm^?3 in this experiment, respectively, by atmospheric pressure collisional radiative model and ion collector current. In this context, the hydroxyl OH radical density inside the biosolutions has been also investigated experimentally by ultraviolet absorption spectroscopy when the Ar non-thermal plasma jet has been bombarded onto them. It is found that the emission and absorption profiles for the other reactive oxygen species such as NO (226 nm) and O₂*^? (245 nm) are shown to be very small inside the biosolution in comparison with those for the OH radical species. It is found that the densities of OH radical species inside the biosolutions are higher than those on the surface in this experiment. The densities of the OH radical species inside the deionized water, Dulbecco’s modified eagle medium, and phosphate buffered saline are measured to be about 2.1 × 10¹⁶, 1.1 × 10¹⁶, and 1.0 × 10¹⁶ cm^?3, respectively, at 2 mm downstream from the surface under optimized Ar gas flow of 200 sccm. It is also found that the critical hydroxyl OH radical density for the lung cancer H460 cells to experience an apoptosis is observed to be around 0.3 × 10¹⁶ cm^?3 under 1 min plasma exposure in this experiment.     

Microalgae Biomass as a New Potential Source of Sustainable Green Lubricants

Lubricants are materials able to reduce friction and/or wear of any type of moving surfaces facilitating smooth operations, maintaining reliable machine functions, and reducing risks of failures while contributing to energy savings. At present, most worldwide used lubricants are derived from crude oil. However, production, usage and disposal of these lubricants have significant impact on environment and health. Hence, there is a growing pressure to reduce demand of this sort of lubricants, which has fostered development and use of green lubricants, as vegetable oil-based lubricants (biolubricants). Despite the ecological benefits of producing/using biolubricants, availability of the required raw materials and agricultural land to create a reliable chain supply is still far from being established. Recently, biomass from some microalgae species has attracted attention due to their capacity to produce high-value lipids/oils for potential lubricants production. Thus, this multidisciplinary work reviews the main chemical-physical characteristics of lubricants and the main attempts and progress on microalgae biomass production for developing oils with pertinent lubricating properties. In addition, potential microalgae strains and chemical modifications to their oils to produce lubricants for different industrial applications are identified. Finally, a guide for microalgae oil selection based on its chemical composition for specific lubricant applications is provided.     

均匀电场对冰晶结构及生长的影响

Homogeneous crystallization of supercooled water under electric field with strength ranging from 4.0 to 40.0 V·nm^-1 was investigated by using molecular simulation technique. The liquid-solid transition was successfully obtained based on ice component analysis using the CHILL algorithm. The analysis suggested that the produced crystalline was cubic ice dominant. The influence of the field strength on the structure and the growth rate of the ice was studied. The results revealed that the presence of an electric field drove the system to crystallize rapidly into dense and distorted cubic ice. The density of the crystals increased as a function of the field strength, from 0.98 to 1.08 g·cm^-3. The growth rate of the ice nucleus increased along with the field strength according to the characteristic time derived from the Avrami equation which ranged from 0.254 to 5.513 ns. This type of acceleration can be partially attributed to the enhancement of the rotational dynamics of the water molecules. Moreover, by monitoring the formation history of the cubic ice, we found that the defective ice acted as a transition state linking the liquid water and the cubic ice.     

均匀电场对冰晶结构及生长的影响

采用分子动力学模拟方法研究了强度为4.0-40.0 V·nm^-1的均匀电场对过冷水冰晶结构和冰晶生长速率的影响. 文中通过CHILL 算法来识别不同的冰相结构,通过拟合Avrami 公式来得到冰晶生长所需的特征时间. 结果表明,在所施加的电场强度范围内生成的冰相以立方冰为主. 随着电场强度的增加,形成的立方冰的变形程度逐渐增大,冰晶的密度从0.98 g·cm^-3 增加到1.08 g·cm^-3,同时冰晶生长的特征时间从5.153 ns 减小到0.254 ns,冰晶生长的速率逐渐增长. 对水分子的动力学分析表明,冰晶生长速率增加的部分原因是电场能够促进水分子运动到形成冰晶所需要的取向. 此外,对冰相分子形成过程的分析表明缺陷冰分子在冰晶的生长过程中扮演着中间态的角色. 随电场强度的增加,由缺陷冰转变为立方冰的比例增长的速率逐渐提高.     

Exposure of Arctic Field Scientists to Ultraviolet Radiation Evaluated Using Personal Dosimeters

During July 2000 we used an electronic personal dosimeter (X-2000) and a biological dosimeter (Deutsches Zentrum für Luft- und Raumfahrt: Biofilm) to characterize the UV radiation exposure of arctic field scientists involved in biological and geological fieldwork. These personnel were working at the Haughton impact structure on Devon Island (75 degrees N) in the Canadian High Arctic under a 24 h photoperiod. During a typical day of field activities under a clear sky, the total daily erythemally weighted exposure, as measured by electronic dosimetry, was up to 5.8 standard erythemal dose (SED). Overcast skies (typically 7-8 okta of stratus) reduced exposures by a mean of 54%. We estimate that during a month of field activity in July a typical field scientist at this latitude could potentially receive approximately 80 SED to the face. Because of body movements the upper body was exposed to a UV regimen that often changed on second-to-second time-scales as assessed by electronic dosimetry. Over a typical 10 min period on vehicle traverse, we found that erythemal exposure could vary to up to 87% of the mean exposure. Time-integrated exposures showed that the type of outdoor field activities in the treeless expanse of the polar desert had little effect on the exposure received. Although absolute exposure changed in accordance with the time of day, the exposure ratio (dose received over horizontal dose) did not vary much over the day. Under clear skies the mean exposure ratio was 0.35 +/- 0.12 for individual activities at different times of the day assessed using electronic dosimetry. Biological dosimetry showed that the occupation was important in determining daily exposures. In our study, scientists in the field received an approximately two-fold higher dose than individuals, such as medics and computer scientists, who spent the majority of their time in tents.     

氮化铝纳米锥的低温生长与场发射性能(英文)

考察了在600℃以下通过反应AlCl3+NH3→AlN+3HCl制备AlN纳米锥的规律,结果表明在500℃时仍可获得AlN纳米锥,当温度为480℃时则无氮化物生成。场发射测试显示在500~600℃温区内制得的AlN纳米锥的开启电场处于14.2~20 V·μm-1范围,且随制备温度升高而减小。结果表明AlN纳米锥可在低温条件下获得,且具有较好的场发射性能。