Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Structural Insight into the Stabilizing Effect of O-Glycosylation
No full textProtein glycosylation has been shown to have a variety of site specific and glycan-specific effects, but so far, the molecular logic that lead's to such observations has been elusive. Understanding the structural changes that Occur and being able to correlate those with the physical properties of the glycopeptide are valuable steps toward being able to predict how specific glycosylation patterns will affect the stability of glycoproteins: By systematically comparing the structural features of the O-glycosylated carbohydrate-binding module of a Trichoderma reesei-derived Family 7 cellobiohydrolase, we were able to develop a better understanding of the influence of O-glycan structure on the molecule's physical stability. Our results indicate that the previously observed stabilizing effects of O-glycans come from the introduction of new bonding interactions to the structure and increased rigidity, while the decreased stability seemed to result from the impaired interactions and increased conformational flexibility. This type of knowledge provides a powerful and potentially general mechanism for improving the stability of proteins through glycoengineering
Characteristics of PAHs in farmland soil and rainfall runoff in Tianjin, China
No full textRainfall runoff can remove certain amounts of pollutants from contaminated farmland soil and result in a decline in water quality. However, the leaching behaviors of polycyclic aromatic hydrocarbons (PAHs) with rainfall have been rarely reported due to wide variations in the soil compositions, rainfall conditions, and sources of soil PAHs in complex farmland ecosystems. In this paper, the levels, spatial distributions, and composition profiles of PAHs in 30 farmland soil samples and 49 rainfall-runoff samples from the Tianjin region in 2012 were studied to investigate their leaching behaviors caused by rainfall runoff. The contents of the Sigma(16)PAHs ranged from 58.53 to 3137.90 mu g/kg in the soil and 146.58 to 3636.59 mu g/L in the runoff. In total, most of the soil sampling sites (23 of 30) were contaminated, and biomass and petroleum combustion were proposed as the main sources of the soil PAHs. Both the spatial distributions of the soil and the runoff PAHs show a decreasing trend moving away from the downtown, which suggested that the leaching behaviors of PAHs in a larger region during rainfall may be mainly affected by the compounds themselves. In addition, 4- and 5-ring PAHs are the dominant components in farmland soil and 3- and 4-ring PAHs dominate the runoff. Comparisons of the PAH pairs and enrichment ratios showed that acenaphthylene, acenaphthene, benzo[a]anthracene, chrysene, and fluoranthene were more easily transferred into water systems from soil than benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[ghi]perylene, and indeno[123-cd]pyrene, which indicated that PAHs with low molecular weight are preferentially dissolved due to their higher solubility compared to those with high molecular weight
Influence of acidogenic headspace pressure on methane production under schematic of diversion of acidogenic off-gas to methanogenic reactor
No full textThis study investigated the effects of 12.6 psi (T1), 6.3 psi (T2), 3.3 psi (T3) and ambient (T4) headspace pressure on the metabolic pathways in the acidogenic leach bed reactor (LBR) and overall methane recovery during two-phase anaerobic digestion of food waste. Diversion of biogas from LBR enhanced COD and soluble product generation in T2, T3 and T4 whereas, high pressure (T1) resulted in comparatively higher lactate production and low protein degradation. A pressure of 3-6 psi (T2 and T3) improved the production of COD by similar to 22-36%, soluble products by similar to 9-43%, volatile solid reduction by similar to 14-19%, and CH4 production by similar to 10-31% compared with control. Besides, similar to 3-6 psi headspace pressure positively influenced the composition of soluble products resulting in enhanced methane recovery adding advantage to the two-phase system. A headspace pressure of similar to 3-6 psi is recommended to enhance the hydrolysis-acidogenesis; however, the actual hydrogen concentration should be considered
Changes in the heavy metal distributions in whole soil and aggregates affected by the application of alkaline materials and phytoremediation
No full textTo explore the combined remedy effect of alkaline materials and plants on the distribution of heavy metals in whole soil and aggregates, a 3 year in situ experiment was carried out in a dual copper (Cu)/cadmium (Cd)-contaminated farmland in this study. Treatment was applied by the addition of soda residue (11.2 t ha(-1)), apatite (22.3 t ha(-1)), or lime (4.45 t ha(-1)), respectively, into the heavy metals-contaminated soil as a single application; Elsholtzia splendens was continually planted for 3 years in all the experimental plots. The total metals amounts and distributions of Cu and Cd in the whole soil and aggregates were then investigated. Our results showed that (1) although the total concentrations of Cu and Cd were slightly increased in the whole soil, their exchangeable concentrations were significantly reduced in both abovementioned treatments; (2) all the abovementioned 3 treatments significantly increased the stability of the dry and wet aggregates when compared with the control treatment; (3) similar to the whole soil, combined remediation groups slightly increased the concentrations of Cu and Cd in the aggregates, but decreased their available and exchangeable concentrations observably. Specifically, the highest concentrations of Cu and Cd were found in the aggregates sized <0.053 mm; however, mass loadings of Cu and Cd were observed in the 0.053-0.25 mm and 0.25-2 mm sized fractions, respectively; moreover, the treatments increased the mass loading of Cu and Cd in the aggregates sized >0.25 mm. In total, the combined remediation adopted in our study dramatically decreased the available concentrations of both Cu and Cd in the whole soil and aggregates. The distribution variations of Cu and Cd caused by passivator-plant combined remediation in the whole soil might be because more metal ions have been transformed into less mobile fractions, whereas the heavy metal distribution differences in the aggregates might be not only correlated with the size of the soil wet aggregates, but also possibly controlled by the soil organic carbon
Bithienopyrroledione vs. thienopyrroledione based copolymers: dramatic increase of power conversion efficiency in bulk heterojunction solar cells
No full textBithienopyrroledione (bi-TPD) based polymers P1 and P2 are designed and synthesized. Photovoltaic devices based on P1:PC71BM and P2:PC71BM blend films show power conversion efficiencies (PCEs) of 8.22% and 9.08%, respectively, whereas devices based on their thienopyrroledione (TPD)-based analogue P3 and PC71BM blend films display a PCE of 5.10%
Dicer and Argonaute Genes Involved in RNA Interference in the Entomopathogenic Fungus Metarhizium robertsii
No full textRNA interference (RNAi) is a gene -silencing mechanism that plays an important role in gene regulation in a number of eukaryotic organisms. Two core components, Dicer and Argonaute, are central in the RNAi machinery. However, the physiological roles of Dicer and Argonaute in the entomopathogenic fungus Metarhizium robertsii have remained unclear. Here, the roles of genes encoding Dicer (M. robertsii dclI1 [Mrdcl1] and Mrdcl2) and Argonaute (Mrago1 and Mrogo2) proteins in M. robertsii were investigated. The results showed that the Dicer -like protein MrDCL2 and Argonaute protein MrAGO1 are the major components of the RNAi process occurring in M. robertsii. The Dicer and Argonaute genes were not involved in the regulation of growth and diverse abiotic stress response in M. robertsii under the tested conditions. Moreover, our results showed that the Dicer and Argonaute gene mutants demonstrated reduced abilities to produce conidia, compared to the wild type (WT) and the gene -rescued mutant. In particular, the conidial yields in the Delta dcl2 and Aogol mutants were reduced by 55.8% and 59.3%, respectively, compared with those from the control strains. Subsequently, for the \ATI and Delta dcl2 mutant strains, digital gene expression (DGE) profiling analysis of the stage of mycelium growth and conidiogenesis revealed that modest changes occur in development or metabolism processes, which may explain the reduction in conidiation in the Delta dcl2 mutant. In addition, we further applied high -throughput sequencing technology to identify small RNAs (sRNAs) that are differentially expressed in the WT and the Delta dcl2 mutant and found that 4 known microRNA-like small RNAs (milRNAs) and 8 novel milRNAs were Mrdcl2 dependent in M. robertsii
The search of proper oxygen carriers for chemical looping partial oxidation of carbon
No full textChemical looping partial oxidation process has more advantages over conventional chemical looping process, which can not only completely avoid the problem of greenhouse gas emissions, but also supply syngas products for chemical industry. The aim of the present work is to perform fundamental investigation on chemical looping partial oxidation of solid fuels. Production of CO through chemical looping partial oxidation of carbon was investigated in order to find proper oxygen carrier with good reactivity and high selectivity. A simple and easy to use method based on the zone division of Ellingham diagram was offered to distinguish the oxidation ability of various metal oxides, and three zones including complete oxidation, partial oxidation and inert zones were divided. CaFe2O4, Ca2Fe2O5 and FeAl2O4 in partial oxidation zone together with Fe2O3 in complete oxidation zone were chosen as target oxygen carriers (OCs) for chemical looping partial oxidation of carbon in this work. Of the target metal oxides, CaFe2O4 and Ca2Fe2O5 were found to have fast reaction rate, large oxygen-carrying capacity, high CO selectivity, and good regeneration performance, which made them very attractive for the purpose of chemical looping partial oxidation of solid fuels in real applications. (C) 2017 Elsevier Ltd. All rights reserved
"Watching" the Dark State in Ultrafast Nonadiabatic Photoisomerization Process of a Light-Driven Molecular Rotary Motor
No full textPhotoisomerization dynamics of a light-driven molecular rotary motor, 9-(2-methyl-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene, is investigated with trajectory surface-hopping dynamics at the semiempirical OM2/MRCI level. The rapid population decay of the S-1 excited state for the M isomer is observed, with two different decay time scales (500 fs and 1.0 ps). By weighting the contributions of fast and slow decay trajectories, the averaged lifetime of the S-1 excited state is about 710 fs. The calculated quantum yield of the M-to-P photoisomerization of this molecular rotary motor is about 59.9%. After the S-0 -> S-1, excitation, the dynamical process of electronic decay is followed by twisting about the central C=C double bond and the motion of pyramidalization at the carbon atom of the stator-axle linkage. Although two S-0/S-1 minimum-energy conical intersections are obtained at the OM2/MRCI level, only one conical intersection is found to be responsible for the nonadiabatic dynamics. The existence of "dark state" in the molecular rotary motor is confirmed through the simulated time-resolved fluorescence emission spectrum. Both quenching and red shift of fluorescence emission spectrum observed by Conyard et al. [Conyard, J.; Addison, K.; Heisler, I. A.; Cnossen, A.; Browne, W.R.; Feringa, B. L.; Meech, S.R. Nat. Chem. 2012, 4, 547-551; Conyard, J.; Conssen, A.; Browne, W. R.; Feringa, B. L.; Meech, S. R. J. Am. Chem. Soc. 2014, 136, 9692-9700] are well understood. We find that this "dark state" in the molecular rotary motor is not a new electronic state, but the "dark region" with low oscillator strength on the initial S-1 state
Rhodanine side-chained thiophene and indacenodithiophene copolymer for solar cell applications
No full textHigh Time-Resolution Optical Sensor for Monitoring Atmospheric Nitrogen Dioxide
No full textHigh time-resolution monitoring of nitrogen dioxide (NO2) is of great importance for studying the formation mechanism of aerosols and improving air quality. Based on the Griess-Saltzman (GS) reaction, a portable NO2 optical sensor was developed by employing a porous polypropylene membrane tube (PPMT) integrated gas permeation collector and detector. The PPMT was filled with GS reagents and covered with a coaxial jacket tube for gas collection. Its two ends were respectively fixed with a yellowish-green light-emitting diode and a photodiode for optic signal reception. NO2 was automatically introduced through the collector by two air pumps cooperating with a homemade gas injector. Under the optimized conditions, the device presented good performance for monitoring NO2, such as a limit of detection of 5.1 ppbv (parts per billion by volume), an intraday precision of 4.1% (RSD, relative standard deviation, n = 11, c = 100 ppbv), an interday precision of 5.7% (RSD, n = 2-3 per day for 5 days, c = 100 ppbv), an analysis time of 4.0 min, and a linearity range extended to 700 ppbv. The developed device was successfully applied to analyzing outdoor air with a comparable precision to that of the standard method of China. The high time resolution characteristic that includes sampling 15 times per hour and a good stability for 10 days of urban air analysis had also been evaluated