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Recent decades have witnessed an increasing number of studies investigating petroleum systems with the application of rhenium-osmium (Re-Os) isotopic geochemistry. Here, we review the use of the 187Re-187Os geochronometer with respect to the geochemical behaviour of rhenium and osmium in hydrocarbon-related geological processes. The Re-Os budget in hydrocarbon source rock predominantly originates from natural water columns during its deposition. Open seawater tends to have a homogeneous Os isotopic composition because its residence time in seawater is longer than the time taken for ocean mixing. On the contrary, restricted water bodies (e.g., lakes) may have heterogeneous Os isotopic compositions due to the greater amount of terrigenous input. Hydrogenous Re and Os atoms are sequestered from the water body into sedimentary organic matter and transferred into crude oil through thermal maturation of organic matter. Thermal maturation likely does not significantly alter the Re-Os isotopic systematics of the source rock as a Re-Os isochron age of 442±21 Ma (2σ) is yielded in this study for over matured source rocks within the Silurian Longmaxi Formation from the Sichuan Basin. Re-Os atoms are mainly hosted by the highly polar/aggregating/aromatic asphaltenes in hydrocarbons, possibly chelating with organic complexes or occurring as metalloporphyrins. Resin and aromatic hydrocarbons also contribute to the Re-Os budget, but are 2 to 3 orders of magnitude lower than that of asphaltenes, whereas saturates do not contain appreciable Re-Os contents. The distribution of Re-Os atoms in hydrocarbons is heterogeneous because the duplicate analysis of pure single bitumen samples yields similar 187Os/188Os ratios whereas variable 187Re/188Os ratios. The Re-Os system in crude oils can be reset during transport away from the source rocks, with Os-rich organic fractions more readily expelled than Re-rich fractions. Contact with metal-rich fluids (e.g., hydrothermal fluid) or compositional changes related to asphaltene contents (e.g., deasphalting, biodegradation, thermal cracking and thermochemical sulphate reduction) are also likely to alter the Re-Os systematics in hydrocarbons. These geochemical features enable the 187Re-187Os isotopic system to have robust applicability for petroleum system investigations, which may use the Re-Os radiometric tool for: (1) stratigraphic correlation of source rocks, (2) dating geological events altering the asphaltene content in hydrocarbon such as hydrocarbon generation, thermochemical sulphate reduction, etc., and, (3) fingerprinting hydrocarbons. Regardless of the robustness of the 187Re-187Os geochronometer for petroleum system investigations, there are several pending questions such as partitioning between solid organic species or between organic matter and sulphide, chelating sites in hydrocarbons and Os isotopic equilibration between hydrocarbon subfractions. To improve the understanding of the Re-Os behaviour in petroleum systems, we underscore multi-proxies-based geochemistry (e.g., inorganic-organic geochemistry) and experimental studies (e.g., hydrous pyrolysis).

In recent years, deoxynivalenol (DON) has frequently been detected in wheat grains and their products. The enantioselective impact of flutriafol on the growth and DON biosynthesis of Fusarium graminearum was investigated in relation to water activity (αw, 0.97 and 0.99) and temperature (20, 25, and 30 °C) on the wheat-based medium. R-(-)-flutriafol exhibited higher bioactivity than S-(+)-flutriafol and Rac-flutriafol under the above conditions. Flutriafol enantiomers reduced or stimulated DON biosynthesis depending on αw. DON levels were negligible after 14 or 7 days of incubation times under 0.97 and 0.99 aw, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses showed that the expression levels of trichothecene biosynthetic (TRI) genes of F. graminearum under 0.97 aw were significantly higher than those under 0.99 aw. In addition, R-(-)-flutriafol can induce more TRI gene expression than S-(+)-flutriafol. Taken together, this study indicated that aw and temperature play important roles in regulating DON biosynthesis in F. graminearum with flutriafol enantiomers.

A new chromatographic method for isolation of W from large masses of silicate samples (>1 g) for ultrahigh precision isotopic analysis was developed. The purification of W was achieved through two stages of rapid chromatographic separations. In the first step, Ti, Zr, Hf, and W were separated collectively from the sample matrix through an AG1-X8 (100-200 mesh) column with a 10 mL resin volume. Subsequently, W was rapidly separated from Ti and Zr-Hf with high purity by a two-step extraction chromatographic method using 0.6 and 0.3 mL TODGA resin columns (50-100 μm particle size), respectively. The total yield of W, including the anion exchange and the TODGA chromatographic separation steps, is greater than 90%. The procedure was employed to isolate W from rock reference materials GSJ JB-3 and USGS BHVO-2; the separated W was analyzed by TRITON Plus TIMS, yielding a 182W/184W of 0.864898 ± 0.000005 (n = 8, 2 SD) for JB-3 and 182W/184W of 0.864896 ± 0.000006 (n = 5, 2 SD) for BHVO-2, which are in agreement with previously reported values within analytical errors.

Ferulate 5-hydroxylase (F5H) is a limiting enzyme involved in biosynthesizing sinapyl (S) monolignol in angiosperms. Genetic regulation of F5H can influence S monolignol synthesis and therefore improve saccharification efficiency and biofuel production. To date, little is known about whether F5H is post-transcriptionally regulated by endogenous microRNAs (miRNAs) in woody plants. Here, we report that a microRNA, miR6443, specifically regulates S lignin biosynthesis during stem development in Populus tomentosa. In situ hybridization showed that miR6443 is preferentially expressed in vascular tissues. We further identified that F5H2 is the direct target of miR6443. Overexpression of miR6443 decreased the transcript level of F5H2 in transgenic plants, resulting in a significant reduction in S lignin content. Conversely, reduced miR6443 expression by short tandem target mimics (STTM) elevated F5H2 transcripts, therefore increasing S lignin composition. Introduction of a miR6443-resistant form of F5H2 into miR6443-overexpression plants restored lignin ectopic composition, supporting that miR6443 specifically regulated S lignin biosynthesis by repressing F5H2 in P. tomentosa. Furthermore, saccharification assays revealed decreased hexose yields by 7.5-24.5% in miR6443-overexpression plants compared with the wild-type control, and increased hexoses yields by 13.2-14.6% in STTM6443-overexpression plants. Collectively, we demonstrate that miR6443 modulates S lignin biosynthesis by specially regulating F5H2 in P. tomentosa.

A cation-exchange resin is commonly used to separate Sr from geological and environmental samples. AG50 resin is the most traditional cation-exchange resin and has the advantages of good reusability and low cost. Although AG50 resin can meet the demands of most conventional geological samples, eliminating 87Rb isobaric interference from samples with high Rb/Sr ratios (>30) is difficult during one-step separation. Separating Sr twice using AG50 resin is the general approach to Rb removal. The two-step separation method is time consuming and leads to a low Sr yield. This study aimed to improve the sample throughput and overcome the problem of 87Rb isobaric interference from imperfect separation. A new separation method involving hydrofluoric acid (HF acid) coprecipitation combined with a cation-exchange resin (i.e. AG50 resin) for samples with high Rb/Sr ratios was developed. HF acid was used as a coprecipitator to remove most Rb (>90%) and recover Sr before performing AG50 column chemistry. The reliability of this method was examined using the rhyolite standard JR-2, a typical sample with a high Rb/Sr ratio (Rb/Sr = 37.36). Results in the JR-2 case showed that approximately 92% of Rb and most of the matrix elements (K, Ti, Fe, Al, Mn and Na) could be removed effectively. Moreover, Sr recovery exceeded 91% during HF acid coprecipitation. After the removal of Rb by HF acid coprecipitation, the Sr fraction with high purity was easily obtained through one-step separation using the AG50 resin column. However, we found that the removal rates of Rb and some matrix elements (such as Al and Na) were strongly affected by the composition of Al–Ca–Mg in samples. Our separation method is more suitable for samples with high Rb/Sr ratios and low Ca and Mg contents. A series of silicate rock reference materials were selected to evaluate the applicability of our method, and the Sr isotopic results were consistent with previously reported values. Overall, this rapid, simple and low-cost method shows great potential for the separation of Sr from geological samples with high Rb/Sr ratios, such as alkaline feldspar granite, alkaline granite and alkaline rhyolite.

This study describes a simple and low-cost method that requires small samples (

Circadian rhythm is believed to play important roles in atherosclerosis. The gut microbiota is found to be closely related to atherogenesis, and shows compositional and functional circadian oscillation. However, it's still unclarified whether circadian clock and intestinal microbiota are involved in the progression of atherosclerosis induced by environmental pollutant acrolein. Herein, patients with atherosclerosis showed higher MMP9, a promising biomarker for atherosclerosis, and lower Bmal1 and Clock expression in the plasma. Interestingly, acrolein exposure contributed to the increased MMP9, decreased Clock and Bmal1, and activated MAPK pathways in human umbilical vein endothelial cells (HUVECs). We found that knockdown of Clock or Bmal1 lead to upregulation of MMP9 in HUVECs, and that Clock and Bmal1 expression was elevated while MAPK pathways were blocked. Atherosclerotic apolipoproteinE-deficient mice consumed a high-fat diet were used and treated with acrolein (3 mg/kg/day) in the drinking water for 12 weeks. Upregulation of MMP9, and downregulation of Clock and Bmal1 were also observed in plasma of the mice. Besides, acrolein feeding altered gut microbiota composition at a phylum level especially for an increased Firmicutes and a decreased Bacteroidetes. Additionally, gut microbiota showed correlation with atherosclerotic plaque, MMP9 and Bmal1 levels. Therefore, our findings indicated that acrolein increased the expression of MMP9 through MAPK regulating circadian clock, which was associated with gut microbiota regulation in atherosclerosis. Circadian rhythms and gut microbiota might be promising targets in the prevention of cardiovascular disease caused by environmental pollutants.

The secondary cell wall is an important carbon sink in higher plants and its biosynthesis requires coordination of metabolic fluxes in the phenylpropanoid pathway. In Arabidopsis (Arabidopsis thaliana), MYB75 and the KNOX transcription factor KNAT7 form functional complexes to regulate secondary cell wall formation in the inflorescence stem. However, the molecular mechanism by which these transcription factors control different branches of the phenylpropanoid pathway remains poorly understood in woody species. We isolated an R2R3-MYB transcription factor MYB6 from Populus tomentosa and determined that it was expressed predominately in young leaves. Overexpression of MYB6 in transgenic poplar upregulated flavonoid biosynthetic gene expression, resulting in significantly increased accumulation of anthocyanin and proanthocyanidins. MYB6-overexpression plants showed reduced secondary cell wall deposition, accompanied by repressed expression of secondary cell wall biosynthetic genes. We further showed that MYB6 interacted physically with KNAT7 and formed functional complexes that acted to repress secondary cell wall development in poplar and Arabidopsis. The results provide an insight into the transcriptional mechanisms involved in the regulation of the metabolic fluxes between the flavonoid and lignin biosynthetic pathways in poplar.

UDP-glycosyltransferases (UGTs), as phase II detoxification enzymes, are widely distributed within living organisms and play vital roles in the biotransformation of endobiotics and xenobiotics in insects. Insects increase the expression of detoxification enzymes to cope with the stress of xenobiotics, including insecticides. However, the roles of UGTs in insecticide resistance are still seldom reported. In this study, two UGT inhibitors, namely, 5-nitrouracil and sulfinpyrazone, were found to synergistically increase the toxicity of imidacloprid in the resistant population of Diaphorina citri. Based on transcriptome data, a total of 17 putative UGTs were identified. Quantitative real-time PCR showed that fourteen of the 17 UGT genes were overexpressed in the resistant population relative to the susceptible population. Using RNA interference technology to knockdown six UGT genes, the results suggested that silencing the selected UGT375A1, UGT383A1, UGT383B1, and UGT384A1 genes dramatically increased the toxicity of imidacloprid in the resistant population. However, silencing the UGT362B1 and UGT379A1 genes did not result in a significant increase in the toxicity of imidacloprid in the resistant population. These findings revealed that some upregulated UGT genes were involved in imidacloprid resistance in D. citri. These results shed some light upon and further our understanding of the mechanisms of insecticide resistance in insects.

Background Cellulase is the one of the largest contributors to the high production costs of the lignocellulose-based biorefineries. As the most widely used cellulase producer, Trichoderma reesei has two weaknesses, deficiencies in β-glucosidase and cellobiohydrolase II. This work aimed at solving this problem by simultaneous enhancement of the beta–exo synergism and exo–exo synergism in T. reesei cellulase to increase the cellulose degrading capability, i.e. enhanced co-expression of the β-glucosidase gene the cellobiohydrolase II gene of T. reesei. Results Enhanced co-expression of the β-glucosidase gene and the cellobiohydrolase II gene in T. reesei using the strong promoter Pcbh1 was found successful in overcoming the two weaknesses. Filter paper activities of T. reesei cellulase were greatly elevated, which were 7.21 ± 0.45 (E7, Aabgl1 and Trcbh2) and 7.69 ± 0.42 (F6, Anbgl1 and Trcbh2) FPIU/mL. They were much higher than that of the parental strain Rut-C30, 2.45 ± 0.36 FPIU/mL. Enzymatic hydrolysis yields were also improved, from 67.22 ± 1.61% by Rut-C30 cellulase to 87.98 ± 0.65% by E7 cellulase and 86.50 ± 1.01% by F6 cellulase. The substrate loading for 1 g glucose release from SECS were decreased, from 2.9637 g SECS using Rut-C30 cellulase to 2.0291 g SECS using E7 cellulase and 2.0573 g SECS using F6 cellulase. As a result, the efficiency of the process from SECS to glucose was substantially improved. Conclusions Enhanced co-expression of the β-glucosidase gene and the cellobiohydrolase II gene in T. reesei using the strong promoter Pcbh1 in T. reesei was proven triumphal in the simultaneous enhancement of the beta–exo synergism and exo–exo synergism in T. reesei cellulase. This strategy also improved the cellulase production, enzymatic hydrolysis yield and the efficiency of the process from SECS to glucose in the context of on-site cellulase production. This work is a commendable attempt in the cellulase composition optimization at the transcriptional level.

Background The biomanufacturing of d-glucaric acid has attracted increasing interest because it is one of the top value-added chemicals produced from biomass. Saccharomyces cerevisiae is regarded as an excellent host for d-glucaric acid production. Results The opi1 gene was knocked out because of its negative regulation on myo-inositol synthesis, which is the limiting step of d-glucaric acid production by S. cerevisiae. We then constructed the biosynthesis pathway of d-glucaric acid in S. cerevisiae INVSc1 opi1Δ and obtained two engineered strains, LGA-1 and LGA-C, producing record-breaking titers of d-glucaric acid: 9.53 ± 0.46 g/L and 11.21 ± 0.63 g/L d-glucaric acid from 30 g/L glucose and 10.8 g/L myo-inositol in fed-batch fermentation mode, respectively. However, LGA-1 was preferable because of its genetic stability and its superior performance in practical applications. There have been no reports on d-glucaric acid production from lignocellulose. Therefore, the biorefinery processes, including separated hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF) and consolidated bioprocessing (CBP) were investigated and compared. CBP using an artificial microbial consortium composed of Trichoderma reesei (T. reesei) Rut-C30 and S. cerevisiae LGA-1 was found to have relatively high d-glucaric acid titers and yields after 7 d of fermentation, 0.54 ± 0.12 g/L d-glucaric acid from 15 g/L Avicel and 0.45 ± 0.06 g/L d-glucaric acid from 15 g/L steam-exploded corn stover (SECS), respectively. In an attempt to design the microbial consortium for more efficient CBP, the team consisting of T. reesei Rut-C30 and S. cerevisiae LGA-1 was found to be the best, with excellent work distribution and collaboration. Conclusions Two engineered S. cerevisiae strains, LGA-1 and LGA-C, with high titers of d-glucaric acid were obtained. This indicated that S. cerevisiae INVSc1 is an excellent host for d-glucaric acid production. Lignocellulose is a preferable substrate over myo-inositol. SHF, SSF, and CBP were studied, and CBP using an artificial microbial consortium of T. reesei Rut-C30 and S. cerevisiae LGA-1 was found to be promising because of its relatively high titer and yield. T. reesei Rut-C30 and S. cerevisiae LGA-1were proven to be the best teammates for CBP. Further work should be done to improve the efficiency of this microbial consortium for d-glucaric acid production from lignocellulose.

Purpose/Objective(s) To clarify the efficacy of FLASH radiotherapy (FLASH-RT) in inhibiting mammary tumorigenesis and normal tissue sparing. Materials/Methods We used a spontaneous mammary tumor model of MMTV-PyMT mice for the study. Prior to the formation of mammary tumor, MMTV-PyMT mice (3–6-week-old) were treated with a single fraction dose of 9-16 Gy FLASH-RT or conventional radiotherapy (CONV-RT) using a mice-applicator designed targeting five pair of mammary glands. Tumor growth was detected by thorough palpation of all 10 mammary glands twice a week. Liver function, HE however, IFN-g and IL-6 also significantly increased in FLASH compared with control, while IL-10 significantly decreased in CONV compared with control. Serum IL-6, IFN-g and TNF-a levels in FLASH did not markedly change on D6, D18 and D31 post-IR compared with control. Serum IL-6, IFN-g and TNF-a levels were elevated on D6 and continuously increased on D18 and D31 in CONV, but began to increase on D6, and then recovered to the control level on D18 or D31 in FLASH. Serum IL-10 levels decreased at D6, D18 and D31 in CONV, but began to decrease at D6, and then recovered to the control level at D18 or D31 in FLASH. FLASH induced reactive oxygen species (ROS) accumulation in the tumor tissue but not in normal tissue; while absence of ROS accumulation in either tumor or normal tissue under CONV. Notably, the ROS level of normal liver tissue did not differ under CONV or FLASH. Conclusion We found that mammary tumorigenesis was inhibited by FLASH without significant liver injury compared with CONV-RT. The alteration of serum and liver inflammatory cytokines induced by CONV-RT was mildly altered by FLASH. This unique benefit can by partially explained by the accumulatio of ROS in tumor tissue after FLASH.

Heavy metals in food packaging materials have been indicated to release into the environment at slow rates. Heavy metal contamination, especially that of cadmium (Cd), is widely acknowledged as a global environment threat that leads to continuous growing pollution levels in the environment. Traditionally, the detection of the concentration of Cd relies on expensive precision instruments, such as inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). In this study, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on a specific monoclonal antibody was proposed to rapidly detect Cd. The half-inhibitory concentration and detection sensitivity of the anti-cadmium monoclonal antibody of the ic-ELISA were 5.53 ng mL−1 and 0.35 ng mL−1, respectively. The anti-Cd monoclonal antibody possessed high specificity while diagnosising other heavy metal ions, including Al (III), Ca (II), Cu (II), Fe (III), Hg (II), Mg (II), Mn (II), Pb (II), Zn (II), Cr (III) and Ni (II). The average recovery rates of Cd ranged from 89.03–95.81% in the spiked samples of packing materials, with intra- and inter-board variation coefficients of 7.20% and 6.74%, respectively. The ic-ELISA for Cd detection was applied on 72 food packaging samples that consisted of three material categories—ceramic, glass and paper. Comparison of the detection results with ICP-AES verified the accuracy of the ic-ELISA. The correlation coefficient between the ic-ELISA and the ICP-AES methods was 0.9634, demonstrating that the proposed ic-ELISA approach could be a useful and effective tool for the rapid detection of Cd in food packaging materials.

Background The recalcitrance of lignocellulosic biomass provided technical and economic challenges in the current biomass conversion processes. Lignin is considered as a crucial recalcitrance component in biomass utilization. An in-depth understanding of lignin biosynthesis can provide clues to overcoming the recalcitrance. Laccases are believed to play a role in the oxidation of lignin monomers, leading to the formation of higher-order lignin. In plants, functions of only a few laccases have been evaluated, so little is known about the effect of laccases on cell wall structure and biomass saccharification. Results In this study, we screened a gain-of-function mutant with a significant increase in lignin content from Arabidopsis mutant lines overexpressing a full-length poplar cDNA library. Further analysis confirmed that a Chinese white poplar (Populus tomentosa) laccase gene PtoLAC14 was inserted into the mutant, and PtoLAC14 could functionally complement the Arabidopsis lac4 mutant. Overexpression of PtoLAC14 promoted the lignification of poplar and reduced the proportion of syringyl/guaiacyl. In contrast, the CRISPR/Cas9-generated mutation of PtLAC14 results in increased the syringyl/guaiacyl ratios, which led to integrated enhancement on biomass enzymatic saccharification. Notably, the recombinant PtoLAC14 protein showed higher oxidized efficiency to coniferyl alcohol (precursor of guaiacyl unit) in vitro. Conclusions This study shows that PtoLAC14 plays an important role in the oxidation of guaiacyl deposition on cell wall. The reduced recalcitrance of the PtoLAC14-KO lines suggests that PtoLAC14 is an elite target for cell wall engineering, and genetic manipulation of this gene will facilitate the utilization of lignocellulose.

For woody plants, clonal propagation efficiency is largely determined by adventitious root (AR) formation at the bases of stem cuttings. However, our understanding of the molecular mechanisms contributing to AR morphogenesis in trees remains limited, despite the importance of vegetative propagation, currently the most common practice for tree breeding and commercialization. Here, we identified Populus-specific miR476a as a regulator of wound-induced adventitious rooting that acts by orchestrating mitochondrial homeostasis. MiR476a exhibited inducible expression during AR formation and directly targeted several Restorer of Fertility like (RFL) genes encoding mitochondrion-localized pentatricopeptide repeat proteins. Genetic modification of miR476a-RFL expression revealed that miR476a/RFL-mediated dynamic regulation of mitochondrial homeostasis influences AR formation in poplar. Mitochondrial perturbation via exogenous application of a chemical inhibitor indicated that miR476a/RFL-directed AR formation depends on mitochondrial regulation that acts via auxin signaling. Our results thus establish a microRNA-directed mitochondrion-auxin signaling cascade required for AR development, providing insights into the role of mitochondrial regulation in the developmental plasticity of plants.

Poly-ether-ether ketone (PEEK) is a great potential thermoplastic in industry and medical treatment and health. In this work, PEEK/graphene oxide (GO) and PEEK/MoS2 composites were prepared by a novel hot isostatic pressing method. The addition of GO alters the tribological behaviors mechanism, fatigue wear mechanism is predominant to PEEK/GO composites. However, the combination of abrasive and adhesive wear mechanisms is observed for PEEK/MoS2 composites and PEEK. The reason for this is that the hardness and tensile strength of composites are increased with the appropriate addition of GO. The response time to stable friction state of PEEK/GO and PEEK/MoS2 composites is reduced in comparison with PEEK, which is conducive to shorten running-in time, reduce the energy consumption, and improve the tribological performances of composites. The addition of GO and MoS2 can effectively decrease the friction coefficient and wear rate, and the optimal content of GO and MoS2 was 0.7 wt.% and 15 wt.%, respectively. The results indicate that PEEK/GO and PEEK/MoS2 are impressive composites that possess super tribological properties.

WRKY transcription factors (WRKY TFs) are one of the largest protein families in plants, and most of them play vital roles in response to biotic and abiotic stresses by regulating related signaling pathways. In this study, we isolated two WRKY TF genes PtrWRKY18 and PtrWRKY35 from Populustrichocarpa and overexpressed them in Arabidopsis. Expression pattern analyses showed that PtrWRKY18 and PtrWRKY35 respond to salicylic acid (SA), methyl JA (MeJA), abscisic acid (ABA), B. cinereal, and P. syringae treatment. The transgenic plants conferred higher B. cinerea tolerance than wild-type (WT) plants, and real-time quantitative (qRT)-PCR assays showed that PR3 and PDF1.2 had higher expression levels in transgenic plants, which was consistent with their tolerance to B. cinereal. The transgenic plants showed lower P. syringae tolerance than WT plants, and qRT-PCR analysis (PR1, PR2, and NPR1) also corresponded to this phenotype. Germination rate and root analysis showed that the transgenic plants are less sensitive to ABA, which leads to the reduced tolerance to osmotic stress and the increase of the death ratio and stomatal aperture. Compared with WT plants, a series of ABA-related genes (RD29A, ABO3, ABI4, ABI5, and DREB1A) were significantly down-regulated in PtrWRKY18 and PtrWRKY35 overexpression plants. All of these results demonstrated that the two WRKY TFs are multifunctional transcription factors in plant resistance.

Direct dating of petroleum systems by hydrocarbon or associated authigenic minerals is crucial for petroleum system analysis and hydrocarbon exploration. The precipitation of authigenic pyrite in petroliferous basins is commonly genetically associated with hydrocarbon generation, migration, accumulation, or destruction. Pyrite rubidium-strontium (Rb-Sr) isotope dilution thermal ionization mass spectrometry (ID-TIMS) is a well-developed technique, and its successful application for high-temperature ore systems suggests that this dating method has the potential to directly date key processes in the low-temperature petroleum systems. Rb-Sr data for pyrites in two Ordovician carbonate rock specimens collected from ~4952 m in the YD-2 well in the Yudong region, northern Tarim Basin (NW China), yield two identical isochron ages within analytical uncertainties: 206 &plusmn, 13 (2&sigma, ) and 224 &plusmn, 28 Ma (2&sigma, ). SEM investigations demonstrate that Rb and Sr atoms mainly reside in the crystal lattice of the pyrites due to the absence of fluid and mineral inclusions. The rigorous Rb-Sr isochron relations documented in the samples indicate that such residency can result in sufficient Rb/Sr fractionation and initial Sr isotopic homogenization for geochronology. In addition, the closure temperature (227&ndash, 320 &deg, C) for the Rb-Sr isotope system in pyrite is higher than the precipitation temperature for pyrite in petroleum-related environments (below 200 &deg, C), suggesting that the Rb-Sr age of pyrite was not overprinted by post-precipitation alteration. Integrating the lead-strontium-sulfur isotopes of the pyrites with burial history analysis, the ages are interpreted as the timing of alteration of the paleo-oil pool by a hydrothermally-triggered thermochemical sulfate reduction process. This study, for the first time, demonstrates that Rb-Sr pyrite geochronology, combined with radiogenic and stable isotopic analyses, can be a useful tool to evaluate the temporal evolution of oil pools. This approach bears great potential for dating of petroleum systems anywhere else in the world.

The nickel isotope has a great potential for investigating biogeochemical processes in the geosciences and has been proven to be extremely useful for studying the chronology of the early solar system. As one of the most powerful techniques in metal isotopic ratio measurements, thermal ionization mass spectrometry (TIMS) shows poor sensitivity for Ni isotope ratio analysis, because the high ionization potential (7.640eV) of Ni makes it difficult to be ionized on a hot filament. In previous studies, a minimum of 1000 ng Ni was required using the classical Sigel-H3BO3-Al emitter or the Sigel-H3PO4-Al emitter. The present study is first to employ a highly sensitive zirconium hydrogen phosphate (Zr(HPO4)2) emitter to measure the Ni isotopes with TIMS. This emitter produces a significant enhancement in the ionization efficiency of Ni and enables the analysis of the Ni isotope at the 200 ng level with high precision. In addition, this newly developed emitter shows a strong inhibition to the Fe and Zn signals, which are the main potential isobaric interferences during Ni measurement. A series of analyses of the NIST SRM 986 standard demonstrated that an internal precision (2 RSE) of ± 0.03 to 0.05 ‰ can be achieved depending on the sample size. Analysis of the NIST SRM 986 standard also shows an external reproducibility (2 RSD, n = 10) of better than ± 0.11‰, even for Ni at 200 ng.

The Asian citrus psyllid, Diaphorina citri Kuwayama, is one of the most damaging pests of citrus-producing regions throughout the world. The use of insecticides is the main strategy for controlling psyllid and has increased year by year. In this study, four field populations of D. citri were evaluated for resistance to nine different insecticides using the leaf-dip method. The results showed that the highest level of resistance for D. citri was found in imidacloprid with a resistance ratio of 15.12 in the Zengcheng population compared with the laboratory susceptible population. This was followed by chlorpyriphos (6.47), dinotefuran (6.16), thiamethoxam (6.04), lambda-cyhalothrin (4.78), and bifenthrin (4.16). Piperonyl butoxide (PBO) and triphenyl phosphate (TPP) showed significant synergism on imidacloprid effects in the Zengcheng population (3.84- and 2.46-fold, respectively). Nevertheless, diethyl maleate (DEM) had no synergism on imidacloprid. Biochemical enzyme assays suggested that general esterase, glutathione S-transferase and cytochrome P450 monooxygenase activities were higher in the field-collected populations than in the laboratory susceptible population. However, glutathione S-transferase may play a minor role in the resistance of adult D. citri to insecticides. At the molecular level, resistance of D. citri to imidacloprid is mainly related to the increased expression of CYP4C68 and CYP4G70 (>5-fold).

In underground confined spaces with a crowded population, the thermal environment will be hot-humid and occurred with high CO2 concentration. Investigating the combined effect of increased temperature, relative humidity and CO2 concentration on human responses is important for confined spaces. In this paper, 32 subjects were exposed to different combinations of air temperature (Ta), relative humidity (RH) and CO2 concentrations in an underground climate chamber, with thermal response, physiological response and acute health symptoms being investigated. Results show that: at a Ta of 28 °C, RH of 65% and CO2 level of 12,000 ppm, thermal sensation votes (TSV) and thermal acceptability (TA) did not significantly changed, while a significant change was recorded with a RH of 85%. When CO2 concentration increased to 8000 ppm, the subjects' perceived air quality acceptability significantly decreased at Ta of 33 °C, however it did not significantly change at Ta of 28 °C and RH of 65%. Maximum mean skin temperature and wetness difference did not exceed 0.3 °C and 0.15 units between the different exposure conditions, respectively. Significant changes of headaches were observed when CO2 concentrations increased to 12,000 ppm at a RH of 85%, but the difference was not statistically significant at a RH of 65%. This indicated that the combined effects of high Ta, RH and CO2 concentration lead to different human responses.

The Nd isotopic composition of ancient seawater recorded by marine carbonates is valuable for revealing temporal changes in continental weathering inputs and ocean circulation patterns. When analysing carbonate Nd isotopic composition, it is important to extract the primary carbonate portion without bringing in contaminative Nd released from non-carbonate phases, such as clay minerals in sample dissolution. However, there has been no specific research on the dissolution method required for neodymium isotope analysis of carbonates, whereas different dissolution methods vary significantly in selecting the appropriate acid and dissolution procedures. In this study, we conducted a set of chemical leaching experiments based on carbonate reference materials with high purity and excellent homogeneity, aiming to evaluate and optimise the dissolution method for bulk analysis of carbonate neodymium isotopes. We selected a suite of reference materials, including carbonate certified reference materials and non-carbonate minerals, such as kaolinite, montmorillonite, illite, and Fe-Mn nodules, and created a set of artificial carbonate mixed reference materials with different purities. A set of leaching experiments were carried out on these mixed reference materials. The results showed that dilute acetic acid should be preferentially selected over hydrochloric and nitric acids to dissolve carbonate rocks to obtain the Nd isotopic composition. Our study revealed that the carbonate Nd isotopes are not prone to being affected by clay minerals, as the Nd contamination released from clay minerals was limited, especially for samples with purity higher than 85% (m/m). Contrarily, the Nd contamination from Fe-Mn nodules is significant. Regarding the optimised protocol for carbonate Nd isotope analysis, we suggest a one-step leaching protocol to dissolve approximately 60% (m/m) of the total sample for sample purity above 85% (m/m). Specifically, 4 mL of 2.5% (v/v) HAc is used to dissolve 100 mg of the sample, and the leachate is analysed for Nd isotopes. For sample purity lower than 85%, we suggest a two-step leaching protocol in which 30–40% (m/m) of the sample is preleached and discarded, and another 30–40% (m/m) of the sample is dissolved to prepare for Nd isotope analysis. Specifically, 100 mg of the sample is first preleached with 2.5 mL 2.5% (v/v) HAc and then dissolved in 2.5 mL 2.5% (v/v) HAc to prepare for Nd isotope analysis. All the results indicate that accurate data of Nd isotopes can be easily obtained, which potentially broadens the application of carbonate Nd isotope. Based on the chemical leaching technique, we first report high-precision Nd isotope ratios for two carbonate standards (JDo-1 and IAEA-B-7) that can be used for quality control in Nd isotope analyses of carbonates.

Isotope dilution thermal ionization mass spectrometry (ID-TIMS) is considered the “gold standard” for obtaining precise 87Rb/86Sr and 87Sr/86Sr isotope ratios and accurate elemental concentrations of Rb–Sr. However, the classical ID-TIMS technique is laborious and time-consuming because the purified Rb and Sr fractions must be individually loaded onto different independent filaments due to severe 87Rb isobaric interference on 87Sr. To overcome this issue, we developed a new method whereby Rb and Sr were sequentially measured by TIMS on the same filament, without venting, to obtain both ratios of 87Rb/86Sr and 87Sr/86Sr and concentrations of Rb and Sr. Results obtained from six silicate powders of certified reference materials are in good agreement with recommended values within ±0.002% for the 87Sr/86Sr ratio, ±2% for the 87Rb/86Sr ratio and the Rb and Sr elemental contents. The only exception is JG-1a, with slightly higher 87Rb/86Sr and slightly lower 87Sr/86Sr. This new method improved the analytical efficiency and sample throughput without compromising the analytical accuracy and precision. The filament consumption is reduced by 50% compared with conventional methods and therefore significantly reduces operation costs.

The Archean Anshan Complex in the northeastern part of the North China Craton is one of the few areas on Earth where rocks older than 3.8 Ga have been identified, and thus it provides a rare opportunity to determine the relative roles of primordial silicate differentiation versus progressive differentiation in shaping the Earth’s chemical architecture. We undertook 142,143Nd isotopes and major and trace element analyses on well-dated 3.81–3.0 Ga Anshan rocks. This study is the first to report significant positive 142Nd anomalies in the Anshan Complex of up to +9.2 ± 2.8 ppm relative to the modern accessible Earth. The most prominent feature is that the 143Nd isotopes tightly correlate with incompatible trace element ratios. Trends of e143Nd(t) as a function of incompatible trace element ratios reveal that the Anshan source consists of high- and low-μ142Nd end-members. The high-μ142Nd end-member had μ142Nd = +15 and e143Nd(t) = +10 and is characterized by highly enriched incompatible trace element ratios, similar to average early Archean upper continental crust, suggesting a crustal origin. The low-μ142Nd end-member had μ142Nd ≤ −4 and e143Nd(t) ≤ 0 and is characterized by depleted incompatible trace elements. Both 142,143Nd isotopes and incompatible trace element ratios of the low-μ142Nd end-member are similar to that of Barbteron komatiites derived from an early-formed and deep-seated mantle reservoir. Furthermore, the estimated incompatible trace element ratios of the low-μ142Nd end-member are similar to that of a 4.5–4.4 Ga dense melt that was possibly preserved above the core-mantle boundary. The relationships between 147Sm-143Nd, 146Sm-142Nd, and incompatible trace elements provide important constraints on both primary silicate differentiation within 100–150 Ma of solar system formation and late Hadean and early Archean mantle-crust differentiation events. Coupled 147Sm-143Nd and 146Sm-142Nd systematics suggest ca. 4.5–4.4 Ga model ages for the precursor of the oldest components of the Anshan Complex, whereas decoupled 147Sm-143Nd, 146Sm-142Nd, and trace element systematics imply multiple mantle-crust differentiation events from 4.3 to 3.8 Ga.

Wood formation is a complex developmental process under multi-level transcriptional control executed by a large set of transcription factors. However, only limited members have been characterized to be key regulators of lignin biosynthesis in poplar. Here we report the conserved and unique functions of PtoMYB170, a transcription factor identified from Populus tomentosa (Chinese white poplar), in lignin deposition and drought tolerance in comparison with its duplicate paralog PtoMYB216. PtoMYB170 is preferentially expressed in young leaves and xylem tissues. Overexpression of PtoMYB170 in transgenic poplar plants resulted in stronger lignification and more thickened secondary wall in xylem compared with wild-type plants, whereas the CRISPR/Cas9-generated mutation of PtoMYB170 weakened lignin deposition, thereby leading to a more flexible and collapsed xylem phenotype. Transient expression experiments demonstrated that PtoMYB170 specifically activated the expression of lignin biosynthetic genes, consistent with the function of PtoMYB216. However, GUS staining assays revealed that PtoMYB170 was specifically expressed in guard cells of transgenic Arabidopsis while PtoMYB216 was not. Heterologous expression of PtoMYB170 in Arabidopsis enhanced stomatal closure in the dark and resulted in drought tolerance of the transgenic plants through reduced water loss, indicating a diversified role from PtoMYB216. These results revealed the PtoMYB170-dependent positive transcriptional regulation on lignin deposition in poplar and its coordinated function in enhancing drought tolerance by promoting dark-induced stomatal closure.

WRKY transcription factors play important roles in response to diverse environmental stresses, but exact functions of these proteins in poplar defense are still largely unknown. In a previous study, we have shown that poplar WRKY89 is induced by salicylic acid (SA) treatment and plays an important role in resistance against fungi in transgenic poplars. Here, we determined an increase in transcript levels of Group IIa WRKY members in transgenic poplars overexpressing WRKY89 using quantitative real-time polymerase chain reaction analysis. Yeast one-hybrid assay showed that PtrWRKY18 and PtrWRKY35 were potential target genes of WRKY89. Furthermore, we demonstrated that PtrWRKY18 and PtrWRKY35 were localized in the nucleus, and exhibited no transcription activation activity. Constitutive overexpression of PtrWRKY18 and PtrWRKY35 in poplars activated pathogenesis-related genes, and increased resistance to the biotrophic pathogen Melampsora. The results also provided support for the involvement of SA-mediated signaling in Melampsora resistance.

This study has led to a new technique for the separation of Cr from small silicate samples (0.3–2 mg) and determination of stable Cr isotopes in silicates by double spike thermal ionization mass spectrometry (DS-TIMS). Based on our recent two-step exchange resin scheme (Li et al., JAAS, 2016, 31, 2375), we further significantly reduced the procedural blank and improved Cr recovery (94.7–97.5%) from a range of complex silicate rocks varying in composition from andesite to ultra-mafic, and carbonates as well. The key improvement is that KMnO4 was employed to replace conventional (NH4)2S2O8 as the oxidizing reagent, which reduces the procedural blank from 1–20 ng in previous studies to 0.15 ± 0.04 ng (n = 8). In addition, the inhibition effect on the Cr signal caused by residual SO42− in the Cr fraction using the conventional method has been completely eliminated during TIMS measurements. This permits the high precision determination of Cr isotopic ratios from geological samples as small as ∼46 ng. This chemical procedure was verified using a variety of silicate rocks in the size range of 0.3–2 mg. A series of analyses demonstrated that it is possible to attain internal precisions (2 SE) of ±0.03 to 0.06‰. Replicate digestions and analyses of basalt standard BIR-1 with a sample size of 0.3 mg (δ53Cr = −0.158 ± 0.052‰, 2 SD) demonstrated that good intermediate precision is obtainable for extremely small silicate samples.

Objective. To investigate the efficacy and safety of the combination use of tegafur and apatinib as a first-line therapy strategy in advanced gastric cancer (GC). Methods. The present study included a total of 62 advanced GC patients. The patients were randomized into the combined group (treated with both tegafur and apatinib) and the control group (treated with only tegafur). Treatment efficacy, KPS score, nutrition condition, and progression-free survival time (PFS) were recorded. Results. Both the response and disease control rates were significantly higher in the combined group. The PFS time was remarkably higher and the KPS score was significantly reduced in the combined group after treatment. After treatment, both groups showed significantly increased nutrition risk, but the rates of patients with nutrition risk or innutrition were remarkably higher in the combined group. The ADR rates were also significantly higher in the combined group. Conclusion. The combination use could achieve good efficacy and prolong patients’ PFS time; however, apatinib also reduced the patients’ quality of life and enhanced the nutrition risk and adverse drug reactions.

Thermal ionization mass spectrometry (TIMS) has shown excellent analytical precision for Sr isotopic ratio analysis, even for small masses of material (0.5-10 ng). However, because of the sensitivity limit of TIMS, it is still not possible to obtain high precision Sr/Sr isotope ratios for picogram-level sample sizes (30-100 pg) due to the lack of a highly sensitive emitter. This study is the first to employ a highly sensitive silicotungstic acid emitter to measure Sr isotopes at the picogram-level using TIMS. This emitter produces a 3-fold enhancement in the ionization efficiency of Sr and not only significantly reduces the required sample size but also has good external precision. Analyses of the NIST 987 standard yield an external reproducibility (2 RSD, n = 8) better than ±0.013% even for 30 pg of Sr. It is possible to yield an internal precision (2 RSE) of ±0.003% for 100 pg of sample using the default 10 Ohm feedback resistors. This method was verified by using a suite of silicate reference materials. Replicate digestions and analyses (n = 8) of the basalt standard BCR-2 (Sr/Sr = 0.704998 ± 0.000028, 2 SD) at the 326 ± 30 pg level demonstrates that good external reproducibility is reached on ultratrace level silicate samples. This method has a wide variety of potential applications for samples containing ultralow amounts of Sr in geoscience and archeological studies, such as single grains of mica, sphalerite, and pyrite, single mantle melt inclusions, precious extra-terrestrial materials, and human hair to name just a few.

Chromium isotopes have important applications in cosmochemistry, environmental science, geochemistry, and paleoceanography studies. In previous investigations, thermal ionization mass spectrometry (TIMS) showed excellent precision for Cr isotopic ratios analysis. However, relative large sample sizes (200–2000 ng) were required for TIMS measurements and therefore hampered its wider application in geoscience and environmental science. In this study, a highly sensitive Nb2O5 emitter is employed for the first time to measure Cr isotopes using TIMS. This Nb2O5 emitter produces at least a 10-fold enhancement in the sensitivity and can not only significantly reduce the sample size, but also obtain good external precision. In this study, an external precision of ±0.23‰ (2 SD, n = 10) on δ53Cr was obtained on a 5 ng sample of NIST SRM 3112a standard. In addition, an improved two-column chemical separation procedure was devised in order to separate Cr from complex geological materials. Compared to the classical anion resin purification method, the procedural blank and severe inhibition effect from SO42− is significantly reduced by carefully optimizing and evaluating the dosage of (NH4)2S2O8 oxidant. This method has been verified using one dolomite, three basalt and one peridotite reference materials. A range of analytical tests demonstrates that it is possible to attain internal precisions (2 SE) of ±0.017 to 0.037‰ on a single 30 min analysis. Long-term reproducibility (2 SD) for 53Cr/52Cr is 0.113454 ± 0.000004 (∼0.035‰) obtained by replicate analyses (n = 105) of NIST SRM 3112a over a 6 month period. Replicate digestions and analyses of the basalt standard BIR-1 (δ53Cr = −0.110 ± 0.048‰, 2 SD) and the carbonate standard JDo-1 (δ53Cr = 1.710 ± 0.054‰, 2 SD) demonstrate that good external reproducibility is obtainable on natural samples.

A straightforward tandem column separation procedure is presented for the separation of Sr, Nd, Pb, and Hf from silicate materials. It allows rapid purification, without any intervening evaporation, of these four elements of great interest in Earth science and cosmochemistry. After sample loading, the upper Sr Spec column adsorbs Sr and Pb, while the lower TODGA Spec column adsorbs Hf and Nd. Strontium-lead and hafnium–neodymium elements are then back-extracted from the Sr Spec and TODGA Spec columns, respectively. The whole separation procedure, including column setup, cleaning, and pre-conditioning, takes approximately eight hours for separating a batch of 25 samples. The proposed procedure offers significant improvement in separation efficiency of these often-used four elements, compared with conventional four column methods. Fractions of Sr, Nd and Pb are then measured by TIMS and the Hf fraction is determined by MC-ICP-MS. The stability of this procedure was demonstrated by replicate measurements of 87Sr/86Sr, 143Nd/144Nd, 176Hf/177Hf, 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb isotope ratios of eight international silicate rock reference materials, spanning a wide range of bulk compositions. The analytical results obtained in this study agree well with published data. The external reproducibility (2RSD, n = 8) of standard BCR-2 was ±0.0026% for 87Sr/86Sr, ±0.0020% for 143Nd/144Nd, ±0.0049% for 176Hf/177Hf, and ±0.026–0.034% for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb isotope ratios.

Strontium isotope stratigraphy (SIS) is widely used in geoscience as a chemo-stratigraphic tracer. In past SIS research, diverse sample dissolution methods have been developed and applied to bulk carbonate rocks to extract target Sr isotope signatures of primary carbonates, which are easily contaminated with Sr from extraneous phases. However, the accuracy of the various dissolution methods is debated because all carbonate materials in previous studies were collected directly from the field and did not undergo strict homogeneity examination before sample dissolution. To verify and evaluate the actual bias for carbonate in SIS research, in this study, we analysed a set of artificial carbonate mixed standard samples including carbonate certificate reference materials (CRMs) GBW03105a for limestone and JDo-1 for dolostone in addition to that for clay minerals, GBW03103. These samples were verified to be stable in their Sr concentrations and 87Sr/86Sr ratios and could be used as benchmarks to enable reasonable evaluation on the extraction method for carbonate materials. We conducted a subtle chemical leaching experiment with 12 steps on these samples after preleaching by ammonium acetate. Our results show that the acidic preleach is useful in diminishing the Sr contamination from the extraneous phases. Nevertheless, the Sr contamination from the clay mineral can not be completely removed by the chemical leaching method and it would be more substantial for carbonate samples with lower purity and relatively lower original 87Sr/86Sr. Our work suggests an optimised dissolution scheme for carbonate 87Sr/86Sr analysis: (1) an acidic preleach to dissolve about ~60% of the sample, (2) a further dissolution of ~20% of the sample to prepare for the 87Sr/86Sr analysis, (3) leaving at least 10% of the sample undissolved. A simplified dissolution protocol with advantage of rapid operational and relatively-high reliability was finally proposed for strontium isotope stratigraphy research, particularly for reconstruction of secular Sr isotope evolution curve.

Wood development is strictly regulated by various phytohormones and auxin plays a central regulatory role in this process. However, how the auxin signaling is transducted in developing secondary xylem during wood formation in tree species remains unclear. Here, we identified an Aux/INDOLE-3-ACETIC ACID 9 (IAA9)-AUXIN RESPONSE FACTOR 5 (ARF5) module in Populus tomentosa as a key mediator of auxin signaling to control early developing xylem development. PtoIAA9, a canonical Aux/IAA gene, is predominantly expressed in vascular cambium and developing secondary xylem and induced by exogenous auxin. Overexpression of PtoIAA9m encoding a stabilized IAA9 protein significantly represses secondary xylem development in transgenic poplar. We further showed that PtoIAA9 interacts with PtoARF5 homologs via the C-terminal III/IV domains. The truncated PtoARF5.1 protein without the III/IV domains rescued defective phenotypes caused by PtoIAA9m. Expression analysis showed that the PtoIAA9-PtoARF5 module regulated the expression of genes associated with secondary vascular development in PtoIAA9m- and PtoARF5.1-overexpressing plants. Furthermore, PtoARF5.1 could bind to the promoters of two Class III homeodomain-leucine zipper (HD-ZIP III) genes, PtoHB7 and PtoHB8, to modulate secondary xylem formation. Taken together, our results suggest that the Aux/IAA9-ARF5 module is required for auxin signaling to regulate wood formation via orchestrating the expression of HD-ZIP III transcription factors in poplar.

In vascular plants, R2R3-MYB transcription factors are important regulators of secondary cell wall formation. Although 192 annotated R2R3 MYB genes were identified in the poplar genome, only a few members were characterized to participate in the regulation of the secondary cell wall biosynthesis. In this paper, we identify an R2R3-MYB transcription factor, PtoMYB74, which is predicted to be an ortholog of Arabidopsis AtMYB61, a transcription activator that regulates the secondary cell wall formation, lignin biosynthesis, stomatal aperture, and the mucilage of seed coat. PtoMYB74 is mainly expressed in the stems, especially in the xylem tissues and organs. PtoMYB74 as a transcriptional activator is localized to the nucleus. The overexpression of PtoMYB74 increased the secondary cell wall thickness of vessels in transgenic poplar and changed the secondary cell wall compositions. The expression levels of lignin and cellulose biosynthetic genes were elevated in the transgenic poplar overexpressing PtoMYB74 compared to the wild type, while there was no change in the xylan biosynthetic genes. Transcriptional activation assays demonstrated that PtoMYB74 could activate the promoters of structural genes in the lignin and cellulose biosynthetic pathways. Taken together, our data show that PtoMYB74 positively regulates the secondary cell wall biosynthesis in poplar.

In this work, sandwich-like structured CoAl-LDH@ZIF-67 hybrids were constructed by in situ growth of nanosized ZIF-67 crystallites on CoAl-LDH nanoplates. The structure and morphology of CoAl-LDH@ZIF-67 hybrids were represented by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). Accordingly, the hybrids were introduced into epoxy resins to explore their effect on the thermal and fire safety properties of epoxy composites. With the introduction of 2% CoAl-LDH@ZIF-67 hybrids, the T10%, T50% and Tmax values were decreased to some extent and the char residue yield was higher than that of pristine epoxy. The peak heat release rate (PHRR) of epoxy composites declined by 26.4%, in comparison with those of pure epoxy. Moreover, the quantity of smoke produced, toxic CO released and CO2 produced were suppressed markedly and decreased by 16.7%, 59.8% and 32.2%, respectively. A possible mechanism for improving fire safety was put forward based on the analysis of the carbon residues.

BACKGROUND The Asian citrus psyllid, Diaphorina citri, is one of the major pests in citrus-growing areas around the world. The application of insecticides is the most effective method to reduce the population of D. citri. However, D. citri has developed resistance to multiple classes of insecticides. Understanding resistance mechanisms is crucial to the management of D. citri. In this study, molecular assays were performed to characterize imidacloprid resistance mechanisms. RESULTS Based on the D. citri transcriptome database and other known insect resistance genes, 16 cytochrome P450, eight glutathione-S-transferase and six esterase genes were selected for cloning and sequencing. The gene expression analysis of 30 detoxification genes demonstrated that the relative expression of CYP4g15, CYP303A1, CYP4C62, CYP6BD5, GSTS1 and EST-6 were moderately high (>5-fold increase) in the imidacloprid-resistant strain. Feeding of double-stranded RNA (dsRNA) reduced the expression of the six genes (46.7%-72.1%) and resulted in significant adult mortality (65.62%-82.76%). We also determined the ability of different insecticides to induce the six selected genes. The expression of CYP4C62 and GSTS1 genes were the most significantly upregulated in adults treated with all insecticides, except for chlorfenapyr. In chlorfenapyr-treated D. citri, expression of CYP4g15 and CYP303A1 were the most highly induced. CONCLUSION Overexpressed detoxification genes were associated with imidacloprid resistance, as confirmed by RNA interference feeding tests. The induction of the six selected genes when exposed to different insecticides supported the hypothesis that they were involved in the metabolism of the tested insecticides. © 2018 Society of Chemical Industry.

Wood is the most abundant biomass in perennial woody plants and is mainly made up of secondary cell wall. R2R3-MYB transcription factors are important regulators of secondary wall biosynthesis in plants. In this study, we describe the identification and characterization of a poplar MYB transcription factor PtoMYB92, a homolog of Arabidopsis MYB42 and MYB85, which is involved in the regulation of secondary cell wall biosynthesis. PtoMYB92 is specifically expressed in xylem tissue in poplar. Subcellular localization and transcriptional activation analysis suggest that PtoMYB92 is a nuclear-localized transcriptional activator. Overexpression of PtoMYB92 in poplar resulted in an increase in secondary cell wall thickness in stems and ectopic deposition of lignin in leaves. Quantitative real-time PCR showed that PtoMYB92 specifically activated the expression of lignin biosynthetic genes. Furthermore, transient expression assays using a β-glucuronidase (GUS) reporter gene revealed that PtoMYB92 is an activator in the lignin biosynthetic pathway during secondary cell wall formation. Taken together, our results suggest that PtoMYB92 is involved in the regulation of secondary cell wall formation in poplar by controlling the biosynthesis of monolignols.

Salicylic acid (SA) is a defense-related key signaling molecule involved in plant immunity. In this study, a subgroup IIa WRKY gene PtrWRKY40 was isolated from Populus trichocarpa, which displayed amino acid sequence similar to Arabidopsis AtWRKY40, AtWRKY18 and AtWRKY60. PtrWRKY40 transcripts accumulated significantly in response to SA, methyl jasmonate and hemibiotrophic fungus Dothiorella gregaria Sacc. Overexpression of PtrWRKY40 in transgenic poplar conferred higher susceptibility to D. gregaria infection. This susceptibility was coupled with reduced expression of SA-associated genes (PR1.1, PR2.1, PR5.9, CPR5 and SID2) and jasmonic acid (JA)-related gene JAZ8. Decreased accumulation of endogenous SA was observed in transgenic lines overexpressing PtrWRKY40 when compared with wild-type plants. However, constitutive expression of PtrWRKY40 in Arabidopsis thaliana displayed resistance to necrotrophic fungus Botrytis cinerea, and the expression of JA-defense-related genes such as PDF1.2, VSP2 and PR3 was remarkably increased in transgenic plants upon infection with fugal pathogens. Together, our findings indicate that PtrWRKY40 plays a negative role in resistance to hemibiotrophic fungi in poplar but functions as a positive regulator of resistance toward the necrotrophic fungi in Arabidopsis.

We present a novel method for high precision measurement of (186)Os/(188)Os and (187)Os/(188)Os ratios, applying isobaric oxide interference correction based on in-run measurements of oxygen isotopic ratios. For this purpose, we set up a static data collection routine to measure the main Os(16)O3(-) ion beams with Faraday cups connected to conventional 10(11) amplifiers, and (192)Os(16)O2(17)O(-) and (192)Os(16)O2(18)O(-) ion beams with Faraday cups connected to 10(12) amplifiers. Because of the limited number of Faraday cups, we did not measure (184)Os(16)O3(-) and (189)Os(16)O3(-) simultaneously in-run, but the analytical setup had no significant influence on final (186)Os/(188)Os and (187)Os/(188)Os data. By analyzing UMd, DROsS, an in-house Os solution standard, and several rock reference materials, including WPR-1, WMS-1a, and Gpt-5, the in-run measured oxygen isotopic ratios were proven to present accurate Os isotopic data. However, (186)Os/(188)Os and (187)Os/(188)Os data obtained with in-run O isotopic compositions for the solution standards and rock reference materials show minimal improvement in internal and external precision, compared to the conventional oxygen correction method. We concluded that, the small variations of oxygen isotopes during OsO3(-) analytical sessions are probably not the main source of error for high precision Os isotopic analysis. Nevertheless, use of run-specific O isotopic compositions is still a better choice for Os isotopic data reduction and eliminates the requirement of extra measurements of the oxygen isotopic ratios.

Thermal ionization mass spectrometry (TIMS) allows excellent precision for determining Sr isotope ratios in natural water samples. Traditionally, a chemical separation procedure using cation exchange resin has been employed to obtain a high purity Sr fraction from natural water, which makes sample preparation time-consuming. In this study, we present a rapid and precise method for the direct determination of the Sr isotope ratio of natural water using TIMS equipped with amplifiers with two 10(12) Ω resistors. To eliminate the (87)Rb isobaric interference, Re ribbons are used as filaments, providing a significant advantage over W ribbons in the inhibition of Rb(+) emission, based on systematically examining a series of NIST SRM987 standard doping with various amounts of Rb using Re and W ribbons. To validate the applicability of our method, twenty-two natural water samples, including different water types (rain, snow, river, lake and drinking water), that show a large range in Sr content variations (2.54-922.8 ppb), were collected and analyzed from North and South China. Analytical results show good precision (0.003-0.005%, 2 RSE) and the method was further validated by comparative analysis of the same water with and without chemical separation. The method is simple and rapid, eliminates sample preparation time, and prevents potential contamination during complicated sample-preparation procedures. Therefore, a high sample throughput inherent to the TIMS can be fully utilized.

In view of the low initial abundance of 146Sm, 142Nd anomalies are expected to be extremely small (less than 40 ppm), and their detection requires ultra-precise 142Nd/144Nd measurements. A rapid solid-phase micro-extraction (SPME) technique, using HEHEHP resin as sorbent, is established to completely separate Ce from rare earth element (REE) mixtures. This technique is applied to ultra-high-precision 142Nd/144Nd measurements in geological materials. In contrast to the traditional liquid–liquid micro-extraction (LLME) technique, the benefits of the SPME tandem column are high Nd recovery, low residual Ce (Ce/Nd 3.0. Thus, 142Ce interferences on 142Nd never exceed 1.3 ppm. Ultra-high-precision thermal ionization mass spectrometry analyses of silicate standards show that the internal precision of all runs are better than 4 ppm (2 RSE) for 142Nd/144Nd values. 142Nd/144Nd values for JNdi-1, JR-3, and BCR-2 have external precisions of ±4.8, ±4.4, and ±3.9 ppm (2 RSD), respectively. The external reproducibility is sufficient to distinguish and resolve 5 ppm anomalies in 142Nd/144Nd values.

Thermal ionization mass spectrometry (TIMS) is considered the most accurate technique for determining Sr–Nd–Pb isotopic ratios in geological samples. However, time-consuming and complex sample separation procedures greatly hinder the instrumental measurement efficiency. In this study, a single-column separation chemistry procedure for Sr–Nd–Pb from single rock dissolution was developed. The chemistry procedure was designed to minimize the number of evaporation steps and considerably shorten the separation time, enabling high throughput for TIMS. In contrast to conventional three-column separation procedures (∼3 days), this technique was characterized by high efficiency superiority in terms of separation time (∼8 hours), a 3-fold enhancement in the separation efficiency. The stability of our procedure was demonstrated by replicated TIMS measurements of 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios for six international silicate rock reference materials, spanning a wide range of bulk compositions. The analytical results obtained for these standards agreed well with published data. The external reproducibility (2 RSD, n = 10) of a BCR-2 standard sample was ±0.0020% for 87Sr/86Sr, ±0.0023% for 143Nd/144Nd, and ±0.021–0.033% for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios.

Acrolein, a highly toxic α, β-unsaturated aldehyde, promotes the progression of atherosclerosis in association with inflammatory signaling pathway and reverse cholesterol transport (RCT) process. Additionally, hepatic flavin containing monooxygenase 3 (FMO3) is involved in the pathogenesis of atherosclerosis by regulating cholesterol metabolism. Hydroxytyrosol (HT), as a major phenolic compound in olive oil, exerts anti-inflammatory and anti-atherogenic activities in vitro and animal models. The current study was designed to evaluate whether FMO3 participated in pro-atherogenic process by acrolein and HT showed protective effect during this process. Here, endothelial cells and macrophage Raw264.7 cells were used as the cell models. Following oxidized low-density lipoprotein (OX-LDL) treatment, acrolein exposure promoted foam cells formation in macrophage Raw264.7 cells. The expression of FMO3 and inflammatory makers such as phospho-NF-κB, IL-1β, TNFα as well as IL-6 were significantly increased. However, ATP-binding cassette transporters subfamily A member 1 (ABCA1), a major transporter in RCT process, was repressed by acrolein. In addition, FMO3 knockdown could suppress inflammatory markers and promote ABCA1 expression. Hydroxytyrosol (HT) was observed to reduce lipid accumulation, FMO3 expression as well as inflammatory response. Moreover, it promoted ABCA1 expression. Therefore, our findings indicated that acrolein-enhanced atherogenesis by increasing FMO3 which increased inflammatory responses and decreased ABCA1 in vitro can be alleviated by HT, which may have a therapeutic potential for the treatment of atherosclerosis.

Melanins are enigmatic biological macromolecules that can be produced by plants, animals and microorganisms and are especially suited for production in fermentation broth, which is easily industrialised and requires few inputs. This research was conducted to purify, characterise and determine the biological activity of extracellular melanin extracted from Streptomyces sp. The extracellular melanin (M) was extracted from Streptomyces sp. with a yield of 1.46 g L-1. Ma, Mb, Mc and Md were fractionated from M using a Sephadex G-50 column. Ma was detected as the homogeneous component. After studying its ultraviolet-visible absorbance, infrared and electron paramagnetic resonance spectra, as well as scanning electron microscopy images, Ma was confirmed to be typical melanin. Based on its elemental analysis, Ma consisted of carbon, hydrogen, nitrogen, oxygen and sulfur, the percentages of which suggest that phaeomelanin was the main component. In addition, Ma showed significant anti-radiation and free radical scavenging activity. Thus, these results indicated that Streptomyces sp. could be a new source from which to obtain melanin. Ma might be a potential antioxidant and ultraviolet protector and could be used in cosmetics, pesticides, food and other industries.

A novel R2R3 MYB transcription factor PtrMYB57 interacted with bHLH131 and PtrTTG1 to form the MBW complex and negatively regulated the biosynthesis of both anthocyanins and PAs in poplar. R2R3-MYB transcription factors (TFs) are important regulators of secondary metabolite biosynthesis in woody species. A series of R2R3-MYB TFs involved in anthocyanin and proanthocyanidin (PA) biosynthesis have been identified in poplar. In this study, we report the identification and characterization of a subgroup 4 MYB member PtrMYB57, which contains a repressor domain (LxLxL) at the C-terminal end. PtrMYB57 encodes an R2R3 MYB protein localized in the nucleus and is predominantly expressed in mature leaves. Transgenic poplar overexpressing PtrMYB57 showed a reduction in anthocyanin and PA accumulation compared to wild-type plants. By contrast, a high anthocyanin and PA phenotype was observed in Ptrmyb57 mutants generated by the CRISPR/Cas9 system. Furthermore, transient expression assays revealed that PtrMYB57 interacted with bHLH131 (bHLH) and PtrTTG1 (WDR) to form the MBW complex and bound to the flavonoid gene promoters, leading to inhibition of these promoters. Taken together, our results suggest that PtrMYB57 plays a negative role in the regulation of anthocyanin and PA biosynthesis in poplar.

Some R2R3 MYB transcription factors have been shown to be major regulators of phenylpropanoid biosynthetic pathway and impact secondary wall formation in plants. In this study, we describe the functional characterization of PtoMYB156, encoding a R2R3-MYB transcription factor, from Populus tomentosa. Expression pattern analysis showed that PtoMYB156 is widely expressed in all tissues examined, but predominantly in leaves and developing wood cells. PtoMYB156 localized to the nucleus and acted as a transcriptional repressor. Overexpression of PtoMYB156 in poplar repressed phenylpropanoid biosynthetic genes, leading to a reduction in the amounts of total phenolic and flavonoid compounds. Transgenic plants overexpressing PtoMYB156 also displayed a dramatic decrease in secondary wall thicknesses of xylem fibers and the content of cellulose, lignin and xylose compared with wild-type plants. Transcript accumulation of secondary wall biosynthetic genes was down-regulated by PtoMYB156 overexpression. Transcriptional activation assays revealed that PtoMYB156 was able to repress the promoter activities of poplar CESA17, C4H2 and GT43B. By contrast, knockout of PtoMYB156 by CRISPR/Cas9 in poplar resulted in ectopic deposition of lignin, xylan and cellulose during secondary cell wall formation. Taken together, these results show that PtoMYB156 may repress phenylpropanoid biosynthesis and negatively regulate secondary cell wall formation in poplar.

A co-doped LiNb0.3Ta0.7O3:Er3+,Yb3+ ceramic was prepared by a high temperature solid state procedure. Under the excitation of 980 nm laser radiation, intense 660 nm red light and 550 nm green light emissions corresponding to the 4F9/2→4I15/2 and 2H11/2/4S3/2→4I15/2 transitions of Er3+ were observed. The change of Yb3+ concentration has a more significant influence on luminous intensity than the Er3+ concentration. The emission of red and green lights is attributed to a two-photon process. The upconversion luminescence mechanisms were analyzed in detail.