Enhanced CO2 biofixation and protein production by microalgae biofilm attached on modified surface of nickel foam.

In this work, a photobioreactor with microalgae biofilm was proposed to enhance CO2 biofixation and protein production using nickel foam with the modified surface as the carrier for immobilizing microalgae cells. The results demonstrated that, compared with microalgae suspension, microalgae biofilm lowered mass transfer resistance and promoted mass transfer efficiency of CO2 from the bubbles into the immobilized microalgae cells, enhancing CO2 biofixation and protein production. Moreover, parametric studies on the performance of the photobioreactor with microalgae biofilm were also conducted. The results showed that the photobioreactor with microalgae biofilm yielded a good performance with the CO2 biofixation rate of 4465.6 µmol m-3 s-1, the protein concentration of effluent liquid of 0.892 g L-1, and the protein synthesis rate of 43.11 g m-3 h-1. This work will be conducive to the optimization design of microalgae culture system for improving the performance of the photobioreactor.

Long-term outcomes of PCI vs. CABG for ostial/midshaft lesions in unprotected left main coronary artery.

BACKGROUND: There are limited data on long-term (> 5 years) outcomes of drug-eluting stent (DES) implantation compared with coronary artery bypass grafting (CABG) for ostial/midshaft left main coronary artery (LMCA) lesions. METHODS: Of the 259 consecutive patients in Beijing Anzhen Hospital with ostial/midshaft LMCA lesions, 149 were treated with percutaneous coronary intervention (PCI) with DES and 110 were with CABG. The endpoints of the study were death, repeat revascularization, myocardial infarction (MI), stroke, the composite of cardiac death, and major adverse cardiac and cerebrovascular events (MACCE, the composite of cardiac death, MI, stroke or repeat revascularization).The duration of follow-up is 7.1 years (interquartile range 5.3 to 8.2 years). RESULTS: There is no significant difference between the PCI and CABG group during the median follow-up of 7.1 years (interquartile range: 5.3-8.2 years) in the occurrence of death (HR: 0.727, 95% CI: 0.335-1.578; P = 0.421), the composite endpoint of cardiac death, MI or stroke (HR: 0.730, 95% CI: 0.375-1.421; P = 0.354), MACCE (HR: 1.066, 95% CI: 0.648-1.753; P = 0.801), MI (HR: 1.112, 95% CI: 0.414-2.987; P = 0.833), stroke (HR: 1.875, 95% CI: 0.528-6.659; P = 0.331), and repeat revascularization (HR: 1.590, 95% CI: 0.800-3.161; P = 0.186). These results remained after multivariable adjusting. CONCLUSION: During a follow-up up to 8.2 years, we found that DES implantation had similar endpoint outcomes compared with CABG.

A multiphase mixture model for substrate concentration distribution characteristics and photo-hydrogen production performance of the entrapped-cell photobioreactor.

A multiphase mixture model was developed for revealing the interaction mechanism between biochemical reactions and transfer processes in the entrapped-cell photobioreactor packed with gel granules containing Rhodopseudomonas palustris CQK 01. The effects of difference operation parameters, including operation temperature, influent medium pH value and porosity of packed bed, on substrate concentration distribution characteristics and photo-hydrogen production performance were investigated. The results showed that the model predictions were in good agreement with the experimental data reported. Moreover, the operation temperature of 30 °C and the influent medium pH value of 7 were the most suitable conditions for photo-hydrogen production by biodegrading substrate. In addition, the lower porosity of packed bed was beneficial to enhance photo-hydrogen production performance owing to the improvement on the amount of substrate transferred into gel granules caused by the increased specific area for substrate transfer in the elemental volume.

Enhanced photo-H2 production by unsaturated flow condition in continuous culture.

A biofilm photobioreactor under unsaturated flow condition (BFPBR-U) is proposed using a polished optical fiber as the internal light source for photo-H2 production in continuous culture. The main chamber was filled with spherical glass beads to create the reaction bed and the cells were immobilized to form a biofilm under unsaturated flow condition obtained by pumping substrate solution over a packing bed at a rate to create a thin fluid film and injecting the argon to maintain the gas phase space. The effects of operational conditions, including flow rate and influent substrate concentration, on the photo-H2 production performance were investigated. The unsaturated flow conditions eliminated the inhibition caused by high organic loading rate and enhanced light transmission efficiency, leading to an improvement in the photo-H2 production performance.

Bioconversion characteristics of Rhodopseudomonas palustris CQK 01 entrapped in a photobioreactor for hydrogen production.

The performance of the entrapped-cell photobioreactor during H2 production was assessed by using glucose as substrate in a continuous operation mode. The maximal hydrogen production rate and light conversion efficiency, 2.61 mmol/L/h and 82.3%, were obtained at a HRT of 11.4 h, an substrate loading rate of 4.2 mmol/h and an illumination of 590 nm and 6000 lux, the corresponding hydrogen yield and total energy efficiency were 0.62 mmol H2/(mmol glucose) and 4.8%, respectively. The results indicate the H2 production system illuminated at 590 nm wavelength engaged in energy storage for H2 production due to more ATP synthesized in primary reaction center, and was of higher energy recovery capacity. Furthermore, the total energy efficiency was far lower than the corresponding light conversion efficiency due to intermediates production.

Enhancement of photo-hydrogen production in a biofilm photobioreactor using optical fiber with additional rough surface.

In this study, a biofilm photobioreactor with optical fibers that have additional rough surface (OFBP-R) was developed and it was shown that additional rough surface greatly enhanced the biofilm formation and thus increased the cell concentration, leading to an improvement in the hydrogen production performance. The effects of operational conditions, including the influent substrate concentration, flow rate, temperature and influent medium pH, on the performance of OFBP-R were also investigated. The experimental results showed that the optimum operational conditions for hydrogen production were: the influent substrate concentration 60 mM, flow rate 30 mL/h, temperature 30 °C and influent medium pH 7. Under the optimal operation conditions discovered in this work, the OFBP-R yielded fairly good and stable long-term performance with hydrogen production rate of 1.75 mmol/L/h, light conversion efficiency of 9.3% and substrate degradation efficiency of 75%.