Implementation and analysis of temperature control strategies for outdoor photobiological hydrogen production

For outdoor photobiological hydrogen production, the effective control of temperature in photobioreactors is a challenge. In this work, an internal cooling system for outdoor tubular photobioreactors was designed, built, and tested. The temperatures in the reactors with bacteria were consistently higher than those without bacteria, and were also strongly influenced by solar irradiation and ambient air temperature. The cooling protocol applied successfully kept the reactor temperatures below the threshold limit (38 °C) required for the bioprocess and provided a uniform distribution of temperature along the reactor tube length. The biomass growth and hydrogen production were similar in the reactors cooled co-currently and counter-currently. The biomass growth rate was 0.1 l/h, the maximum hydrogen production rate was 1.28 mol/m³/h, and the overall hydrogen yield obtained was 20 %. The change in the biomass was fitted using the logistic model while cumulative hydrogen production was fitted using the modified Gompertz equation.     

Circuit Model of Fano Resonance on Tetramers,Pentamers, and Broken Symmetry Pentamers

This paper presents the representation circuit model for Fano resonance of plasmonic nanoparticles in the optical domain. An intuitive explanation is provided for the physical nature of Fano resonance based on the three-level quantum system, and the Fano resonance effects of three basic nanoparticle arrangements, namely tetramer, pentamer, and symmetry broke pentamer are discussed. A coupling capacitor is calculated as an equivalent component in the proposed circuit model in order to describe the coupling effect between subradiant and superradiant mode in the Fano resonance. The circuit impedances of tetramer, pentamer, and broken symmetry pentamer are simulated, with resultant circuit models in agreement with the calculated results based on S-parameters.     

Investigation of the eIF2α phosphorylation mechanism in response to proteasome inhibition in melanoma and breast cancer cells

The 26S proteasome is an ATP-dependent proteolytic complex found in all eukaryotes, archaebacteria, and some eubacteria. Inhibition of the 26S proteasome causes pleiotropic effects in cells, including cellular apoptosis, a fact that has led to the use of the 26S proteasome inhibitor, bortezomib, for treatment of the multiple myeloma cancer. We previously showed that in addition to the effects of proteolysis, inhibition of the 26S proteasome causes a rapid decrease in the protein synthesis rate due to phosphorylating alfa subunit of the eukaryotic translation initiation factor 2 (eIF2α) by the heme-regulated inhibitor kinase (HRI). In order to test whether inhibition of the 26S proteasome causes the same effect in cancer cells, we have investigated the influence of two commonly used proteasome inhibitors, bortezomib and MG132, on the phosphorylation status of eIF2α in B16F10 melanoma and 4T1 breast cancer cells. It was found that both of the inhibitors caused rapid phosphorylation of eIF2α. Taking into account that the Hsp70 is a critical component needed for the HRI activation and enzymatic activity, we have tested a possible participation of this protein in the eIF2α phosphorylation event. However, treatment of the cells with two structurally different Hsp70 inhibitors, quercetin and KNK437, in the presence of the proteasome inhibitors did not affect the eIF2α phosphorylation. In addition, neither protein kinase C (PKC) nor p38 mitogen-activated protein kinase (MAPK) was required for the proteasome inhibitor-induced eIF2α phosphorylation; furthermore, both the PKC inhibitor staurosporine and the p38 MAPK inhibitor SB203580 caused enchanced phosphorylation of eIF2α. Zinc(II) protoporphyrine IX (ZnPP), an inhibitor of the heme-oxygenase-1 (HO-1), which has also been previously reported to be involved in HRI activation, also failed to prevent the induction of eIF2α phosphorylation in the presence of the proteasome inhibitor bortezomib or MG132.     

Changes in growth and photosynthetic patterns of oil palm (<Emphasis Type="Italic">Elaeis guineensis</Emphasis> Jacq.) seedlings exposed to short-term CO<Subscript>2</Subscript> enrichment in a closed top chamber

Three varieties of oil palm seedlings (Deli Yangambi, Deli Urt, Deli AVROS) were exposed to three levels of CO₂ (400, 800, 1,200 μmol/mol) in split plot design to determine growth (net assimilation rate, NAR; relative growth rate, RGR) and photosynthetic patterns of the seedlings under short-term CO₂ exposure of 15 weeks. Increasing CO₂ from 400 to 800 and 1,200 μmol/mol significantly enhanced total biomass and leaf area, net photosynthesis (A) and water use efficiency (WUE) especially from weeks 9 to 15. By the end of week 15, total biomass increased by 113%, and A and WUE by one- and fivefold, respectively, while specific leaf area decreased by 37%. Both enhanced biomass and A under elevated CO₂ were effective in modifying NAR and RGR as shown by high correlation coefficient values (r ² = 0.68 and 0.72; r ² = 0.63 and 0.67, respectively), although WUE seemed to have more influence over the NAR (r ² = 0.97) and RGR (r ² = 0.93). Neither interspecific preference nor its interaction with CO₂ imposed any significant effect on parameters observed. Growth improvement with CO₂ seemed able to produce healthy, bigger and vigorous oil palm seedlings, and the technique may have potential to be developed for use to reduce nursery period.     

DEXA analysis on the bones of rats exposed in utero and neonatally to static and 50 Hz electric fields

Effects of the electromagnetic fields on living bodies, bones in particular, are among the relevant issues of contemporary life. In this study, we report the influences of 50 Hz and 0 Hz (static) electric fields (EF), on intact rat bones, as evaluated by dual energy X-ray absorbtion (DEXA) measurements on bone content and density when these animals (n = 27) are continuously exposed in utero and neonatally to EFs (10 kV/m) 14 days before and 14 days after their birth, for 28 days in total. Differences between 50 Hz EF and static EF groups are found to be significant (95% confidence level) for total bone mineral content (BMC), TBMC (P = .002). Differences between 50 Hz and control groups are found to be significant for total bone mineral density (BMD), TBMD (P = .002), lumbar BMC, LBMC (P = .023), and TBMC (P = .001). Differences between static EF and control groups are found to be significant for femoral BMD, FBMD (P = .009), TBMD (P = .002), LBMC (P = .001), and TBMC (P = .001). Note that TBMC parameters are jointly significant for all differences between the three groups of test animals. These results have shown that both static and 50 Hz EFs influence the early development of rat bones. However, the influence of static EFs is more pronounced than that of the 50 Hz field.     

N-acetyl-L-cysteine abrogates fibrogenic properties of fibroblasts isolated from Dupuytren's disease by blunting TGF-beta signalling

Dupuytren's disease, a benign fibroproliferative disorder of the palmar fascia, represents an ideal model to study tissue fibrosis. Transforming growth factor-beta1 (TGF-beta1) and its downstream Smad signalling system is well established as a key player during fibrogenesis. Thus, targeting this basic pathomechanism seems suitable to establish new treatment strategies. One such promising treatment involves the substance N-acetyl-L-cysteine (NAC), shown to have antifibrotic properties in hepatic stellate cells and rat fibroblasts. In order to investigate antifibrotic effects of N-acetyl-L-cysteine (NAC), fibroblasts were isolated from surgically resected fibrotic palmar tissues (Dupuytren fibroblasts, DF) and exposed to different concentrations of NAC and recombinant TGF-beta1. Fibroblasts isolated from tendon pulleys served as controls (control fibroblasts, CF). Smad signalling was investigated by a Smad binding element driven reporter gene analysis. Both cell types express TGF-beta1, indicating autocrine signalling in DF and CF. This was confirmed by comparing reporter gene activity from LacZ and Smad7 adenovirus infected cells. NAC treatment resulted in abrogation of Smad mediated signalling comparable to ectopically overexpressed Smad7, even when the cells were stimulated with recombinant TGF-beta1 or ectopically expressed a constitutively active TGF-beta receptor type I. Additionally, NAC dose-dependently decreased expression of three major indicators of impaired fibrotic matrix turnover, namely alpha-smooth muscle actin (alpha-SMA), alpha 1 type I procollagen (Col1A1), and plasminogen activator inhibitor-type I (PAI-1). Our results suggest that TGF-beta signalling and subsequent expression of fibrogenesis related proteins in Dupuytren's disease is abrogated by NAC thus providing a basis for a therapeutic strategy in Dupuytren's disease and other fibroproliferative disorders.     

Expression of Glucose‐6‐Phosphate Dehydrogenase and 6‐Phosphogluconate Dehydrogenase in Oxidative Stress Induced by Long‐Term Iron Toxicity in Rat Liver

Reactive oxygen species (ROS) are highly reactive and oxygen‐containing molecules that are derived by metabolic activities or from environmental sources. Toxicity of heavy metals including iron has the ability to generate ROS in all living organisms. The pentose phosphate pathway enzymes, which are glucose 6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase, produce nicotinamide adenine dinucleotide phosphate (NADPH) that enables cells to counterbalance the oxidative stress via the action of the glutathione system. The results presented here have shown that toxic and nontoxic levels of iron have a strong effect on the expression of both genes. While toxic levels of iron exhibited significant changes in enzyme activity, nontoxic levels had no effect on enzymes in rat liver. Our results are the first evidence to elucidate how oxidative stress induced by long‐term iron toxicity affects both enzymes at the enzymatic and molecular level and also to determine any possible correlation between the enzymatic and molecular levels.