Cone Beam Micro-CT System for Small Animal Imaging and Performance Evaluation

A prototype cone-beam micro-CT system for small animal imaging has been developed by our group recently, which consists of a microfocus X-ray source, a three-dimensional programmable stage with object holder, and a flat-panel X-ray detector. It has a large field of view (FOV), which can acquire the whole body imaging of a normal-size mouse in a single scan which usually takes about several minutes or tens of minutes. FDK method is adopted for 3D reconstruction with Graphics Processing Unit (GPU) acceleration. In order to reconstruct images with high spatial resolution and low artifacts, raw data preprocessing and geometry calibration are implemented before reconstruction. A method which utilizes a wire phantom to estimate the residual horizontal offset of the detector is proposed, and 1D point spread function is used to assess the performance of geometric calibration quantitatively. System spatial resolution, image uniformity and noise, and low contrast resolution have been studied. Mouse images with and without contrast agent are illuminated in this paper. Experimental results show that the system is suitable for small animal imaging and is adequate to provide high-resolution anatomic information for bioluminescence tomography to build a dual modality system

A Review of Current Methodologies for Regional Evapotranspiration Estimation from Remotely Sensed Data

An overview of the commonly applied evapotranspiration (ET) models using remotely sensed data is given to provide insight into the estimation of ET on a regional scale from satellite data. Generally, these models vary greatly in inputs, main assumptions and accuracy of results, etc. Besides the generally used remotely sensed multi-spectral data from visible to thermal infrared bands, most remotely sensed ET models, from simplified equations models to the more complex physically based two-source energy balance models, must rely to a certain degree on ground-based auxiliary measurements in order to derive the turbulent heat fluxes on a regional scale. We discuss the main inputs, assumptions, theories, advantages and drawbacks of each model. Moreover, approaches to the extrapolation of instantaneous ET to the daily values are also briefly presented. In the final part, both associated problems and future trends regarding these remotely sensed ET models were analyzed to objectively show the limitations and promising aspects of the estimation of regional ET based on remotely sensed data and ground-based measurements

Determination of intracellular lipid and main fatty acids of Nannochloropsis oceanica by ATR-FTIR spectroscopy

Fatty acid profile was one of the important characteristic parameters of edible oil. With the intensification of interest in microalgae as a potential source of edible oil, rapid methods are needed to determine the fatty acid composition of microalgae. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was applied to determine the lipid and fatty acid contents of Nannochloropsis oceanica, a species rich in eicosapentaenoic acid. Samples with different intracellular components were obtained by setting different culture conditions (light intensity and nitrogen concentration). In the spectra of FTIR, some characteristic bands for lipids (3025-2800 cm(-1), 1770-1710 cm(-1), 1480-1350 cm(-1)) were identified. Partial least square regression (PLSR) models were developed to predict total biomass, lipid contents, and main fatty acid contents (palmitic acid C16:0, palmitoleic acid C16:1, eicosatetraenoic acid C20:4, eicosapentaenoic acid C20:5). Generally, the prediction ability of the model established with full spectra was slightly better than that of the model established with specific bands. In the optimized model, excellent coefficients of determination (R-2 >= 0.90), both for calibration and prediction, were found for all variables, except for fatty acid C20:4, which was slightly worse (R-2 = 0.8797). The pretreatment methods of samples were further studied. It was found that the acid-heating method (0.1 M HCl, 100 degrees C, 0.5 h) effectively reduced the interference of the carbohydrate in samples, thus improving the measurement of the characteristic fatty acids C20:4 and C20:5 of N. oceanica. This study showed the feasibility of FTIR as a rapid screening method for evaluating biomass and lipid content, especially some special fatty acid profile of microalgae

Promotion of microalgal biomass production and efficient use of CO2 from flue gas by monoethanolamine

BACKGROUNDFlue gas as carbon source for microalgae culture has been applied to reduce the high cost of production. However, low mass transfer efficiency owing to the low CO2 partial pressure in flue gas limited its utilization. In this work, monoethanolamine was proposed to enhance CO2 utilization and microalgal biomass production.</p

A novel photobioreactor structure using optical fibers as inner light source to fulfill flashing light effects of microalgae

In this work, a novel photobioreactor structure using optical fibers being fixed vertically to culture flow direction as inner light source was proposed to fulfill flashing light effects (FLE) of microalgae, so as to obtain high light efficiency. Three types of optical-fiber photobioreactor fulfilling FLE of microalgae, i.e. air-driven panel, pump-driven panel and stirred tank type, were proposed and a 130 L airlift panel one was practically constructed on which both cold (light profile, liquid velocity) and hot model tests were carried out. Results demonstrated that it could produce uniformed light/dark frequencies being over 10 Hz and microalgae productivity increased by 43% and 38% for Spirulina platensis and Scenedesmus dimorphus respectively, compared with the control. This suggested the structure to be a viable and promising option for future photobioreactors. (C) 2013 Elsevier Ltd. All rights reserved

Hydrolytic degradation of cellulose-graft-poly(L-lactide) copolymers

A series of cellulose-g-poly(L-lactide) (cellulose-g-PLLA) copolymers with 30.65-85.21 % PLLA weight content and the molar substitution of PLLA (MSPLLA) from 0.99 to 12.73 were synthesized via the homogeneous graft-from reaction in 1-allyl-3-methylimidazolium chloride (AmimCI) with 4-dimethylaminopyridine (DMAP) acting as the catalyst. In common organic solvents, the solubility of obtained graft copolymers was better than cellulose and strongly depended on the MSPLLA. The hydrolytic degradation of cellulose-g-PLLA copolymers was investigated in phosphate buffered solution (PBS, pH 7.4) at 37 degrees C. Interestingly, it was found that, when the MSPLLA was below 8.83, the hydrolytic degradation rate of cellulose-g-PLLA copolymers was obviously faster than that of both pristine cellulose and PLLA. Moreover, as the MSPLLA, decreased, the cellulose-g-PLLA copolymers showed a more rapid weight loss, due to its higher hydrophilicity. Both XPS and H-1 NMR analyses demonstrated the degradation occurred mainly at PLLA segments. The morphological observations indicated that, during the hydrolytic degradation, the graft copolymers firstly experienced a surface erosion process, and then the bulk erosion happened. (C) 2015 Elsevier Ltd. All rights reserved.</p

Installation of flow deflectors and wing baffles to reduce dead zone and enhance flashing light effect in an open raceway pond

To reduce the dead zone and enhance the flashing light effect, a novel open raceway pond with flow deflectors and wing baffles was developed. The hydrodynamics and light characteristics in the novel open raceway pond were investigated using computational fluid dynamics. Results showed that, compared with the control pond, pressure loss in the flow channel of the pond with optimized flow deflectors decreased by 14.58%, average fluid velocity increased by 26.89% and dead zone decreased by 60.42%. With wing baffles built into the raceway pond, significant swirling flow was produced. Moreover, the period of average L/D cycle was shortened. In outdoor cultivation of freshwater Chlorella sp., the biomass concentration of Chlorella sp. cultivated in the raceway pond with wing baffles was 30.11% higher than that of the control pond. (C) 2015 Elsevier Ltd. All rights reserved

Outdoor cultivation of Chlorella sp. in an improved thin-film flat-plate photobioreactor in desertification areas

In order to reduce the flow resistance of the thin-film flat plat photobioreactor (FPPBR) and make it more suitable for mass microalgae cultivation, the channel diameter was modified to 0.06 m and the thin-film FPPBR consisted of 10 parallel shunt-wound channels. A thin-film FPPBR system with 100 modified FPPBRs was constructed and used for Chlorella sp. cultivation in desertification areas (Ordos, China) from July to September of 2018. The pressure drop of the modified FPPBR system decreased significantly and the microalgae showed much higher productivity. The pressure drop was about 11.8 kPa when the liquid velocity was 0.238 m s(-1). The final biomass concentration and area productivity reached 2.01 g L-1 and 49.79 g m(-2) day(-1) respectively, and the yearly productivity of Chlorella sp. was estimated to be about 15.24 t ha(-2) year(-1). The results demonstrated that high productivity of Chlorella sp. could be achieved in the improved FPPBR system in desertification areas and the improved FPPBR system was feasible for mass cultivation of microalgae in the commercial application. (C) 2019, The Society for Biotechnology, Japan. All rights reserved

Enhancement of biofilm formation and microalgae growth by preparing cellulose film with rough surface

A series of cellulose films with rough surface were prepared by dissolution and regeneration in the ionic liquid, 1-allyl-3-methylimidazolium chloride (AmimCl). The cellulose films possessed a rough surface with the maximum height difference (S-z) of 128-217 mu m, a macroporous structure with a high porosity of 84.7%-90.5%, and a negative potential between -40.00 and -54.15 mV. Furthermore, the cellulose films exhibited excellent microalgae adhesion properties. After 18 days of attached Chlorella sp. cultivation experiments, the average productivities of C-A-120 films (C-A-X, X means the mesh number of the substrate) reached 20.80 g m(-2) d(-1)), which is 2.69 times than that of the cellulose film with a smooth surface. The result indicates that the cellulose films with a rough surface and high water adsorption ratio have a huge potential in serving as the substrate of the attached microalgae cultivation to promote microalgae cells growth and biofilm formation