Nickel oxide/carbon nanotube/polyaniline nanocomposite as bifunctional anode catalyst for high-performance Shewanella-based dual-chamber microbial fuel cell

Bioprocess and Biosystems Engineering - A novel nickel oxide/carbon nanotube/polyaniline (NCP) nanocomposite has been prepared and used to modify the electrocatalytic properties of carbon cloth...     

The molecular and biochemical analyses of CO2-concentrating mechanisms in cyanobacteria and microalgae

Abstract. The supply of dissolved inorganic carbon for photosynthesis in the aquatic environment is much more variable than that experienced by terrestrial plants. In response to this variability, cyanobacteria and many species of microalgae acclimate to rapid changes in the availability of dissolved inorganic carbon by the induction of high affinity/high capacity CO₂-concentrating systems (CCMs). Biochemical and molecular analyses of the acclimation response have recently identified several components that are required for efficient operation of the CCMs and CO₂ assimilation. This has been accomplished using in vivo labelling studies, and characterization of high inorganic carbon (C_i) requiring cyanobacterial and algal mutants. The identification and regulation of expression of polypeptides synthesized in response to limiting C_i concentrations, and the proposed role of the carboxysome and the pyrenoid in the functioning of the CCMs are examined.     

Cataractogenic action of accelerated carbon ions with energies of 300 MeV/nucleon

The influence of carbon ions of 300 MeV/nucleon on the incidence of lenticular opacity has been studied on mice. The cataractogenic efficiency of low carbon ion doses (0.003 to 0.5 Gy) is higher than that of gamma-radiation. The threshold dose of carbon ions is 0.05 Gy. The RBE ratios vary from 30.4 to 11.1 as the period of the postirradiation observation increases from 20 to 50 weeks.     

The Aspergillus niger carbon catabolite repressor encoding gene, creA

In order to undertake a comparative analysis of carbon catabolite repression in two Aspergillus species, the creA gene has been isolated from A. niger by cross hybridization, using the cloned A. nidulans gene. The A. niger gene has been shown to be functional in A. nidulans by heterologous complementation of the creA204 mutation of A. nidulans. Overall, the genes show 90% sequence similarity (82% identity) at the amino acid (aa) level. There were some striking similarities between the aa sequences encoded by the two fungal creA genes and two genes involved in carbon catabolite repression in Saccharomyces cerevisiae. The zinc-finger regions showed 96% similarity (84% identity) with the zinc-finger region of the MIG1 gene of S. cerevisiae. The CREA protein contains a stretch of 42 aa that is identical in A. niger and A. nidulans, and these show 81% similarity (33% identity) with a region of the S. cerevisiae RGR1 gene.     

Sensitivity of a dynamic global vegetation model to climate and atmospheric CO2

The equilibrium carbon storage capacity of the terrestrial biosphere has been investigated by running the Lund–Potsdam–Jena Dynamic Global Vegetation Model to equilibrium for a range of CO₂ concentrations and idealized climate states. Local climate is defined by the combination of an observation-based climatology and perturbation patterns derived from a 4 × CO₂ warming simulations, which are linearly scaled to global mean temperature deviations, Δ T _glob. Global carbon storage remains close to its optimum for Δ T _glob in the range of ±3°C in simulations with constant atmospheric CO₂. The magnitude of the carbon loss to the atmosphere per unit change in global average surface temperature shows a pronounced nonlinear threshold behavior. About twice as much carbon is lost per degree warming for Δ T _glob above 3°C than for present climate. Tropical, temperate, and boreal trees spread poleward with global warming. Vegetation dynamics govern the distribution of soil carbon storage and turnover in the climate space. For cold climate conditions, the global average decomposition rate of litter and soil decreases with warming, despite local increases in turnover rates. This result is not compatible with the assumption, commonly made in global box models, that soil turnover increases exponentially with global average surface temperature, over a wide temperature range.     

Fecundity of Euphausia lucens (Hansen) - laboratory evidence for multiple broods

There has been much controversy in the past as to how many broods euphausiids are capable of producing per season. Several authors have suggested that multiple broods are possible, although this has not been demonstrated in the laboratory. In the present study, two Euphausia lucens females were shown to spawn continuously over a period of at least 2.5 months. The euphausiids produced ≈ 33–40 broods during this period, representing 134–192% of their body carbon. Daily egg production rates varied from 0 to 86 eggs, representing a mean of 3–4% of their body carbon d⁻¹. Egg production rates were often severely depressed during moulting, and were also somewhat lower during experimental manipulation (changing food conditions). The results suggest that egg production by E. lucens, and perhaps by many other euphausiid species, are considerably higher than was previously thought.     

Use of Pleurotus dryinus for lignocellulolytic enzymes production in submerged fermentation of mandarin peels and tree leaves

It has been shown that the wood-rotting mushroom Pleurotus dryinus IBB 903 is able to effectively produce cellulases, xylanase, laccase, and manganese peroxidase in submerged fermentation of mandarin peels and tree leaves. Gradual increasing of lignocellulosic substrates concentration from 1 to 4–6% enhanced enzyme accumulation in culture liquid. A simple and inexpensive medium containing mandarin peels and yeast extract as sole carbon and nitrogen sources allowed simultaneous production of high levels of both hydrolases and oxidases by P. dryinus IBB 903. Supplementation of this medium by copper and manganese caused earlier and faster accumulation of laccase and manganese peroxidase increasing their yield by 1.5 and 7.5 times, respectively. In addition, by adding manganese to the medium it is possible to regulate the ratio of laccase and MnP in enzyme preparation. The presence of lignocellulosic substrate is the requisite for MnP production by P. dryinus IBB 903 since there was no production of MnP when mushroom has been cultivated in the synthetic medium with different carbon source. Among carbon source tested only utilization of glucose resulted to 21-fold increase of fungus laccase specific activity compared to control medium without carbon source. Carboxymethyl cellulase and xylanase appeared to be inducible enzymes.     

Prospects for manipulating the substrate specificity of ribulose bisphosphate carboxylase/oxygenase

Pierce, J. 1988. Prospects for manipulating the substrate specificity of ribulose bisphosphate carboxylase/oxygenase. - Physiol. Plant. 72: 690–698.
The idea of enhancing plant productivity by minimizing the apparently wasteful process of photorespiration has been an enduring one. Since the relative fluxes of carbon through the competing pathways of photosynthesis and photorespiration are determined by the kinetic properties of a single enzyme, ribulose bisphosphate carboxylase/oxygenase, it has been conjectured that genetic modification of this protein could provide more productive plants. Recent advances in techniques for studying ribulose bisphosphate carboxylase/oxygenase hold promise for determining whether such modifications will prove possible.     

Microbial transformation of a fungicide-derived amine, dimethyl-p-phenylene diamine by Alcaligenes DM4

Abstract Microbial transformation of N , N -dimethyl- p -phenylene diamine (DMPDA), a microbial product formed from the fungicide fenaminosulf ( p -dimethylaminobenzenediazo sodium sulfonate) was studied by enriching microbes in soils treated with the amine. Microorganisms isolated from DMPDA-treated soil belonged to the genera of Micrococcus, Alcaligenes , and Corynebacterium . Of the various isolates, Alcaligenes DM₄ showed maximal growth on DMPDA utilizing it as sources of carbon and nitrogen. When grown in mineral salts basal medium containing 0.05% DMPDA to serve as carbon and nitrogen sources, Alcaligenes DM₄ grew exponentially up to 18 h. Even though the characterization of the complete pathway of microbial degradation of DMPDA could not be carried out due to the auto-oxidation of the compound, the initial transformation product of DMPDA by Alcaligenes DM₄ has been identified as a dimer. The dimer is generated into the culture medium presumably by the extra-cellular oxidase of Alcaligenes DM₄. It is suggested that the risk-benefit evaluation on the use of fenaminosulf is to be made taking into consideration the microbial transformations of the fungicide.     

The impact of elevated CO2 and global climate change on arbuscular mycorrhizas: a mycocentric approach

Arbuscular mycorrhizal (AM) symbioses are a potentially important link in the chain of response of ecosystems to elevated atmospheric [CO₂]. By promoting plant phosphorus uptake and acting as a sink for plant carbon, they can alleviate photosynthetic down-regulation. Because hyphal turnover is likely to be fast, especially in warmer soils, they can also act as a rapid pathway for the return of carbon to the atmosphere. However, most experiments on AM responses to [CO₂] have failed to take into account the difference in growth of mycorrhizal and non- mycorrhizal plants; those that have done so suggest that AM colonization of roots is little altered by [CO₂], although this issue remains to be resolved. Very little is known about the effects of other factors of global environmental change on mycorrhizas. These issues need urgent attention. It is also necessary to understand the potential for the various AM fungal taxa to respond differentially to environmental changes, including carbon supply and soil temperature and moisture, especially because of the differential abilities of plant and fungal species to migrate in response to changing environments. Indeed, there is a need for a new approach to the study of mycorrhizal associations, which has been too plant-centred. It is essential to regard the fungus as an organism itself, and to understand its biology both as an entity and as part of a symbiosis.     

Photoinhibition of respiratory CO2 release in the green alga Scenedesmus

¹⁴CO₂ evolution of prelabeled Scenedesmus obliquus Kütz, has been followed in the dark and in the light. In the light, no carbon dioxide is evolved. Addition of unlabeled NaHCO, leads to ¹⁴CO₂ release attaining 20 to 30% of the dark rate. Double-reciprocal plots of NaHCO₃ concentrations vs ¹⁴CO₂ release results in a straight line, indicative of competition between exogenously supplied bicarbonate and endogenously evolved carbon dioxide. With this method, it is possible to measure CO₂ evolved by respiration in the light and to show that true photoinhibition of respiration occurs in Scenedesmus . In the light. DCMU substantially increases ¹⁴CO₂ evolution; in the presence of the uncoupler carbonyl cyanide- m -chlorophenylhydrazone. ¹⁴CO₂ evolution is comparable to that in the dark. ¹⁴CO₂ release and oxygen uptake in the dark are only slightly affected by cyanide, indicative of a cyanide-resistant respiration and/or fermentation as the essential CO₂-yielding processes in the presence of cyanide. These results, compared with concurrent ATP levels, lead us to assume that energy charge is not the only factor responsible for photoinhibition of respiration.     

Carbon/Nitrogen Imbalance Associated with Drought-Induced Leaf Senescence in Sorghum bicolor

Drought stress triggers mature leaf senescence, which supports plant survival and remobilization of nutrients; yet leaf senescence also critically decreases post-drought crop yield. Drought generally results in carbon/nitrogen imbalance, which is reflected in the increased carbon:nitrogen (C:N) ratio in mature leaves, and which has been shown to be involved in inducing leaf senescence under normal growth conditions. Yet the involvement of the carbon/nitrogen balance in regulation of drought-induced leaf senescence is unclear. To investigate the role of carbon/nitrogen balance in drought-induced senescence, sorghum seedlings were subjected to a gradual soil drought treatment. Leaf senescence symptoms and the C:N ratio, which was indicated by the ratio of non-structural carbohydrate to total N content, were monitored during drought progression. In this study, leaf senescence developed about 12 days after the start of drought treatment, as indicated by various senescence symptoms including decreasing photosynthesis, photosystem II photochemistry efficiency (Fv/Fm) and chlorophyll content, and by the differential expression of senescence marker genes. The C:N ratio was significantly enhanced 10 to 12 days into drought treatment. Leaf senescence occurred in the older (lower) leaves, which had higher C:N ratios, but not in the younger (upper) leaves, which had lower C:N ratios. In addition, a detached leaf assay was conducted to investigate the effect of carbon/nitrogen availability on drought-induced senescence. Exogenous application of excess sugar combined with limited nitrogen promoted drought-induced leaf senescence. Thus our results suggest that the carbon/nitrogen balance may be involved in the regulation of drought-induced leaf senescence.     

Cyanide-induced transition from endogenous carbohydrate to lipid oxidation as indicated by the carbon-13 content of respiratory CO2

The respiration of thin aerated discs of potato tuber tissue rises sigmoidally through 24 h. Aged disc respiration is ostensibly resistant to concentrations of cyanide which inhibit the respiration of fresh discs. It has been shown that cyanide-resistant respiration does not represent indifference to the inhibitor, but is rather due to the suppression of one respiratory carbon path and the evocation of another. The predominant respiratory carbon path of aged discs in the absence of cyanide comprises glycolysis linked to the tricarboxylic acid cycle. The carbon path mediating the cyanide-induced respiration reflects tricarboxylic acid cycle-independent lipid degradation.

The respiratory substrate at any time was deduced by comparing the ¹³C/¹²C ratio of respired CO₂, collected from discs in the presence or absence of cyanide, with the ¹³C/¹²C ratios characterizing endogenous potential metabolites. The determination of the predominant respiratory substrate in potato discs, which have an endogenous substrate reserve, proved possible because the relative concentrations of the stable carbon isotopes in endogenous compounds such as lipid and starch are widely different.     

Re-evaluation of proposed C4 photosynthetic characteristics in the genus Larix

It has been suggested previously that Japanese larch ( Larix kaempferi ) exhibits characteristics of C₄ photosynthesis. To further evaluate this suggestion, stable carbon isotope ratios were determined for leaf and bark tissue of Larix gmelini, L. kaempferi, L. laricina, L. Iyallii, L. occidentalis , and L. sibirica. All δ¹³C values were more negative than –22‰. Short-term labeling with ¹⁴CO₂ showed that phosphoglyceric acid and other phosphorylated compounds were the first products of photosynthesis in L. sibirica. Both of these results strongly suggest that the initial fixation of atmospheric CO₂ in these six Larix species is accomplished solely via the C₃ photosynthetic pathway.     

Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum “cast” intended for examination by transmission electron microscopy. Specimens are subjected to ultrarapid freezing rates, often in the presence of cryoprotective agents to limit ice crystal formation, with subsequent fracturing of the specimen at liquid nitrogen cooled temperatures under high vacuum. The resultant fractured surface is replicated and stabilized by evaporation of carbon and platinum from an angle that confers surface three-dimensional detail to the cast. This technique has proved particularly enlightening for the investigation of cell membranes and their specializations and has contributed considerably to the understanding of cellular form to related cell function. In this report, we survey the instrument requirements and technical protocol for performing freeze-fracture, the associated nomenclature and characteristics of fracture planes, variations on the conventional procedure, and criteria for interpretation of freeze-fracture images. This technique has been widely used for ultrastructural investigation in many areas of cell biology and holds promise as an emerging imaging technique for molecular, nanotechnology, and materials science studies.     

南亚热带格木、马尾松幼龄人工纯林及其混交林生态系统碳氮储量

研究比较了南亚热带6年生格木(Erythrophleum fordii)、马尾松(Pinus massoniana)幼龄人工纯林及马尾松与格木混交林生态系统碳氮储量及其分配特征。结果表明,生态系统总碳储量依次为马尾松-格木混交林(137.75 t/hm2)格木纯林(134.07 t/hm2)马尾松纯林(131.10 t/hm2),总氮储量则为格木纯林(10.19 t/hm2)马尾松-格木混交林(8.68 t/hm2)马尾松纯林(7.01 t/hm2)。3种人工林生态系统碳氮库空间分布基本一致,绝大部分储存于0—100 cm土壤层,平均占生态系统总储量的81.49%和96.91%,其次为乔木层(分别占17.52%和2.69%),林下植被和凋落物层所占比例最小。林地土壤碳主要集中于表土层,其中0—30 cm土层平均碳储量为52.52 t/hm2,占土壤总碳储量(0—100 cm)的47.99%,土壤氮的分布则无明显规律。相比于纯林,与固氮树种混交的营林方式表现出更大的碳储存能力。3种幼龄人工林生态系统较低的地上与地下部分碳氮分配比,表明其仍具有较强的碳氮固持潜力。     

Conventional vs CO2 demand-controlled ventilation systems

1. 1. The feasibility of controlling the ventilation system using the occupant-generated carbon dioxide as an indicator of ventilation rate and indoor air quality has been investigated in an eleven storey office building.

2. 2. The study compares the indoor environment created by two different types of ventilation control systems.

3. 3. The two ventilation systems tested consisted of: a conventional system controlled by outdoor temperatures, and a demand-controlled system regulated by indoor carbon dioxide concentration.

4. 4. The results show that the CO₂-based demand-controlled ventilation system does not worsen indoor air quality and thermal comfort. It was also noticed that an energy saving of 12% was achieved using the CO₂ control system.

5. 5. The occupants perceived that their productivity is proportional to their perception of the indoor environment; indicating that higher productivity rates can be achieved by better controlling the working environment above satisfactory levels.

盐单胞菌利用短链脂肪酸合成聚羟基脂肪酸酯

盐单胞菌(Halomonas)能够利用多种底物为碳源生长,由于其能在高盐条件下进行不灭菌的开放发酵,已被开发用作下一代生物技术的底盘细胞.包括乙酸、丙酸和丁酸在内的短链挥发性脂肪酸能够以生物质为原料制备,有望成为用于微生物发酵的新型碳源.利用10-50g/L浓度的丁酸为碳源对Halomonas sp.TD01和TD08...     

闽江河口芦苇沼泽和短叶茳芏沼泽生态系统含碳温室气体的年收支

河口感潮沼泽是全球重要的蓝碳生态系统,具有很强的固碳能力。碳收支研究是量化生态系统碳源/汇过程及固碳规模的基础。本研究运用透明箱和不同遮光率布遮盖+红外气体分析仪/气相色谱相结合的方法,模拟不同光照条件,测定闽江河口鳝鱼滩半咸水芦苇沼泽和短叶茳芏沼泽的瞬时净生态系统二氧化碳（CO₂）交换量（net ecosystem exchange,NEE）、生态系统呼吸（ecosystem respiration,ER）以及甲烷（CH₄）排放通量,并通过对总光合吸收量（gross ecosystem exchange,GEE）与光合有效辐射的拟合以及ER与气温的拟合,外推2个沼泽生态系统CO₂气体在月、年尺度上的NEE和ER,评估其年固碳量。2个沼泽生态系统的NEE和ER均具有明显的季节变化,春夏秋季为大气中CO₂的汇,而冬季则转化为大气中CO₂的源,芦苇沼泽年尺度固碳能力显著高于短叶茳芏沼泽。芦苇沼泽与短叶茳芏沼泽CH₄排放通量差异不显著。综合考虑CH₄排放,闽江河口鳝鱼滩半咸水芦苇沼泽、短叶茳芏沼泽生态系统年固碳量分别为（5371.52±336.97） g CO₂-eq/m²和（2730.32±503.67） g CO₂-eq/m²。研究表明：闽江河口半咸水沼泽湿地在年尺度上是一个较强的碳汇,在缓解全球变暖方面发挥着重要的角色。