Adjusting agronomic measures to alleviate the kernel position effect in maize is important for ensuring high yields.In order to clarify whether the combined application of organic fertilizer and chemical fertilizer(CA...Adjusting agronomic measures to alleviate the kernel position effect in maize is important for ensuring high yields.In order to clarify whether the combined application of organic fertilizer and chemical fertilizer(CAOFCF)can alleviate the kernel position effect of summer maize,field experiments were conducted during the 2019 and 2020 growing seasons,and five treatments were assessed:CF,100%chemical fertilizer;OFCF1,15%organic fertilizer+85%chemical fertilizer;OFCF2,30%organic fertilizer+70%chemical fertilizer;OFCF3,45%organic fertilizer+55%chemical fertilizer;and OFCF4,60%organic fertilizer+40%chemical fertilizer.Compared with the CF treatment,the OFCF1 and OFCF2 treatments significantly alleviated the kernel position effect by increasing the weight ratio of inferior kernels to superior kernels and reducing the weight gap between the superior and inferior kernels.These effects were largely due to the improved filling and starch accumulation of inferior kernels.However,there were no obvious differences in the kernel position effect among plants treated with CF,OFCF3,or OFCF4 in most cases.Leaf area indexes,post-silking photosynthetic rates,and net assimilation rates were higher in plants treated with OFCF1 or OFCF2 than in those treated with CF,reflecting an enhanced photosynthetic capacity and improved postsilking dry matter accumulation(DMA)in the plants treated with OFCF1 or OFCF2.Compared with the CF treatment,the OFCF1 and OFCF2 treatments increased post-silking N uptake by 66.3 and 75.5%,respectively,which was the major factor driving post-silking photosynthetic capacity and DMA.Moreover,the increases in root DMA and zeatin riboside content observed following the OFCF1 and OFCF2 treatments resulted in reduced root senescence,which is associated with an increased post-silking N uptake.Analyses showed that post-silking N uptake,DMA,and grain yield in summer maize were negatively correlated with the kernel position effect.In conclusion,the combined application of 15-30%organic fertilizer and 70-85%chemical fertilizer alleviated the kernel position effect in summer maize by improving post-silking N uptake and DMA.These results provide new insights into how CAOFCF can be used to improve maize productivity.展开更多
cis-Diamminedichloroplatinum(CDDP)is widely used for the treatment of various solid cancers.Here we reported that CDDP increased the expression and enzymatic activities of carboxylesterase 1(CES1)and carboxylesterase ...cis-Diamminedichloroplatinum(CDDP)is widely used for the treatment of various solid cancers.Here we reported that CDDP increased the expression and enzymatic activities of carboxylesterase 1(CES1)and carboxylesterase 2(CES2),along with the upregulation of pregnane X receptor(PXR)and the downregulation of differentiated embryonic chondrocyte-expressed gene 1(DEC1)in human hepatoma cells,primary mouse hepatocytes,mouse liver and intestine.The overexpression or knockdown of PXR alone upregulated or downregulated the CES1 and CES2 expression,respectively.The increases in CES1 and CES2 expression levels induced by CDDP abolished or enhanced by PXR knockdown or overexpression,implying that CDDP induces carboxylesterases through the activation of PXR.Likewise,the overexpression or knockdown of DEC1 alone significantly decreased or increased PXR and its targets.Moreover,the increases of PXR and its targets induced by CDDP were abolished or alleviated by the overexpression or knockdown of DEC1.The overexpression or knockdown of DEC1 affected the response of PXR to CDDP,but not vice versa,suggesting that CDDP increases carboxylesterases by upregulating PXR mediated by the decrease of DEC1.In addition,CDDP did not increase DEC1 mRNA degradation but suppressed DEC1 promoter reporter activity,indicating that it suppresses DEC1 transcriptionally.The combined use of CDDP and irinotecan had a synergistic effect on two cell lines,especially when CDDP was used first.展开更多
Land use change (LUC) is widely recognized as one of the most important driving forces of global carbon cycles. The soil organic carbon (SOC) and labile organic carbon (LOC) stores were investigated at arable land (AL...Land use change (LUC) is widely recognized as one of the most important driving forces of global carbon cycles. The soil organic carbon (SOC) and labile organic carbon (LOC) stores were investigated at arable land (AL), artificial grassland (AG), artificial woodland (AW), abandoned arable land (AAL) and desert steppe (DS) in the Longzhong region of the Loess Plateau in Northwest China. The results showed that conversions from DS to AL, AL to AG and AL to AAL led to an increase in SOC content, while the conversion from DS to AW led to a decline. The differences in SOC content were significant between DS and AW at the 20-40 cm depth and between AL and AG at the 0-10 cm depth. The SOC stock in DS at the 0-100 cm depth was 39.4 t/hm 2 , increased by 28.48% after cultivation and decreased by 19.12% after conversion to AW. The SOC stocks increased by 2.11% from AL to AG and 5.10% from AL to AAL. The LOC stocks changed by a larger magnitude than the SOC stocks, which suggests that it is a more sensitive index of carbon dynamics under a short-term LUC. The LOC stocks increased at 0-20 cm and 0-100 cm depths from DS to AW, which is opposite to that observed for SOC. The proportion of LOC to SOC ranged from 0.14 to 0.20 at the 0-20 cm depth for all the five land use types, indicating low SOC dynamics. The allocation proportion of LOC increased for four types of LUC conversion, and the change in magnitude was largest for DS to AW (40.91%). The afforestation, abandonment and forage planting on arable land led to sequestration of SOC; the carbon was lost initially after afforestation. However, the carbon sink effect after abandonment may not be sustainable in the study area.展开更多
The quantitative research of wetland landscape fragmentation in the middle reaches of the Heihe River is important for the wetland and oasis sustainable development in the Hexi Corridor. Based on the data of remote se...The quantitative research of wetland landscape fragmentation in the middle reaches of the Heihe River is important for the wetland and oasis sustainable development in the Hexi Corridor. Based on the data of remote sensing and GIS, we constructed the type change tracker model with sliding window technique and spatially morphological rule. The suitable scale and optimum scale of the fragmentation model of wetland landscape in the middle reaches of the Heihe River were determined by the area frequency statistics method, Chi-square distribution normalized scale variance, fractal dimension and diversity index. By integrating type change tracker model and the optimum scale with GIS spatial analysis, the spatial distribution characteristics of wetland landscape fragmentation in different periods and the related spatial-temporal change process were clarified. The results showed that(1) the type change tracker model, which analyzes the spatial pattern of wetland fragmentation on the pixel level, is better than the traditional wetland fragmentation analysis on the landscape and patch levels;(2) The suitable scale for the wetland fragmentation ranged from 150 m×150 m to 450 m×450 m and the optimum scale was 250 m×250 m in the middle reaches of the Heihe River; and(3) In the past 35 years, the total wetland area decreased by 23.2% and the fragmentation of wetland markedly increased in the middle reaches of the Heihe River. The areas of core wetlands reduced by 12.8% and the areas of perforated, edge and patch wetlands increased by 0.8%, 3.1% and 8.9%, respectively. The process of wetland fragmentation in the research region showed the order of core wetland, perforated or edge wetland, patch wetland or non-wetland. The results of this study would provide a reference for the protection, utilization and restoration of limited wetland resources and for the sustainable development of the regional eco-environment in the Heihe River Basin.展开更多
Tyrosol is a pharmacologically active phenolic compound widely used in the medicine and chemical industries.Traditional methods of plant extraction are complicated and chemical synthesis of tyrosol is not commercially...Tyrosol is a pharmacologically active phenolic compound widely used in the medicine and chemical industries.Traditional methods of plant extraction are complicated and chemical synthesis of tyrosol is not commercially viable. In this study, a recombinant Escherichia coli strain was constructed by overexpressing the phenylpyruvate decarboxylase ARO10 from Saccharomyces cerevisiae, which could produce tyrosol from glucose. Furthermore,genes encoding key enzymes from the competing phenylalanine and tyrosine synthesis pathways and the repression protein TyrR were eliminated, and the resulting engineered strain generated 3.57 mmol·L^(-1) tyrosol from glucose. More significantly, codon optimization of ARO10 increased expression and tyrosol titer. Using the novel engineered strain expressing codon-optimized AR10 in shake-flask culture, 8.72 mmol·L^(-1) tyrosol was obtained after 48 h. Optimization of the induction conditions improved tyrosol production to 9.53 mmol·L^(-1)(1316.3 mg·L^(-1)). A higher titer of tyrosol was achieved by reconstruction of tyrosol synthetic pathway in E. coli.展开更多
The added mass coefficient and the water level index formulas for the same-phase and anti-phase vibration of rectangular liquid tanks' bulkheads were derived based on dry mode theory. Three fluid-structure interac...The added mass coefficient and the water level index formulas for the same-phase and anti-phase vibration of rectangular liquid tanks' bulkheads were derived based on dry mode theory. Three fluid-structure interaction numerical methods including Fluid FEM and Fluid BEM were used in this case. The comparison of numerical and theoretical results by the present method shows that ANSYS/Fluid80 is more credible, the NASTRAN/Virtual Mass Method is more suitable for engineering calculations and results of the same-phase vibration by the present method is more accurate.展开更多
In this study,we investigated the effects of environmental factors on plant phenolic variability,seasonal dynamics of total phenolic content(TP),extractable condensed tannins(ECT),protein-bound condensed tannins(PBCT)...In this study,we investigated the effects of environmental factors on plant phenolic variability,seasonal dynamics of total phenolic content(TP),extractable condensed tannins(ECT),protein-bound condensed tannins(PBCT),fiber-bound condensed tannins(FBCT),total condensed tannins(TCT),protein precipitation capacity(PPC)and nutrient content in the branchlets and fine roots of Casuarina equisetifolia.TP and TCT concentrations in branchlets were lowest in the spring,then increased in summer and autumn,similar to the seasonal dynamics in air temperature.TP and TCT concentrations in fine roots were highest in summer,coinciding with heavy precipitation.In general,TP and TCT concentrations were higher in branchlets than in fine roots.No significant difference was found in C concentration among various seasons for either branchlets or fine roots.Branchlets had significantly higher N and P concentrations than fine roots in most seasons.The C/N and N/P ratios in branchlets were significantly lower than in fine roots in all seasons,except summer.The relationship between branchlets and fine roots was significant for C,P and FBCT,but no significant relationships were found for N,TP,ECT,PBCT and TCT.Additionally,TP and TCT content were each significantly correlated with PPC in branchlets and in fine roots.Both TP/N and TCT/N ratios were highest in the autumn for the branchlets and in the summer for fine roots.The results indicate that high temperatures lead to increased tannin production in branchlets,but that the tannin content in fine roots is mainly affected by precipitation.Tannin content was greater in branchlets than in fine roots,which may indicate that selective pressure is greater on branchlets than on fine roots.展开更多
Grazing and mowing are two common practices for grassland management. Mowing is now recommended as an alternative to the traditional grazing for grassland conservation in Inner Mongolia, northern China. Many studies h...Grazing and mowing are two common practices for grassland management. Mowing is now recommended as an alternative to the traditional grazing for grassland conservation in Inner Mongolia, northern China. Many studies have revealed that mowing may alter ecosystem properties in various ways. However, little attention has been paid to the effect of mowing on trace gas emissions, especially on N2O flux. We conducted an experiment to investigate the effects of mowing on N2O fluxes from the semiarid grassland in Inner Mongolia. The mowing experiment, which started in 2003, comprised four mowing intensity treatments, i.e. mowing heights at 2 cm, 5 cm, 10 cm and 15 cm above the soil surface, respectively, and a control (non-mowing), with five replicates. Gas fluxes were measured through a closed static chamber technique during the growing seasons (usually from May to September, depending on local climate at the time) of 2008 and 2009, respectively. Our results showed that mowing decreased N2O emissions, above-ground biomass and total litter production. N2O emissions were greater in May and June than in other sampling periods, regardless of treatments (P 2O fluxes were mainly driven by variations in soil moisture, except in July and August. In July and August, above-ground plant biomass and soil total nitrogen became the major drivers of N2O fluxes under the soil temperatures between 16 ° C and 18 ° C. Though there were some uncertainties due to the low frequency of N2O flux measurement, our study mainly indicated that 5 cm mowing height might decrease N2O emissions in grasslands during the growing season, and soil properties affected the magnitude of the reduction.展开更多
[Objective]Using fiber optic chemical sensor based fluorescence method to accurately determine the content of VB2tablets.[Method]VB2tablets were dissolved in aqueous solution and the detection system of fiber optic ch...[Objective]Using fiber optic chemical sensor based fluorescence method to accurately determine the content of VB2tablets.[Method]VB2tablets were dissolved in aqueous solution and the detection system of fiber optic chemical sensor based fluorescence method was used to measure the spectrum of the solution and to quantitative analyze the content of VB2.[Result]With this method the maximum emission wavelength of VB2was 533 nm.The mass concentration was3.2×10-5-8×10-4mg/ml,which had good linear relationship with fluorescence intensity.The detection line was 1.55×10-8mg/ml and within-day precision was 0.19%while day to day precision was 1.2%,and the recovery was 97.9%-105.1%.[Conclusion]The degree of accuracy was high and the detection line was low when this method was used to determine the content of VB2tablets,and the results were satisfactory.展开更多
Purpose:This study aims to detect research fronts of a scientific field in its early development stage using bibliometric indicators developed based on the features of research fronts.Design/methodology/approach:We fi...Purpose:This study aims to detect research fronts of a scientific field in its early development stage using bibliometric indicators developed based on the features of research fronts.Design/methodology/approach:We first focused on conceptualization of"research fronts"and outlined 4 indicators to measure different aspects of the concept:Innovation,timeliness,stability and interdisciplinarity.Then research specialties obtained based on direct citation networks were evaluated with the 4 indicators and research fronts were identified.Finally,methodology was illustrated and verified in the research domain of complex networks.Findings:The results indicate that the proposed method is useful in detecting research fronts in a specific field which is at an early development stage.Research limitations:The quality of clustering results was not assessed.It needs to be further studied whether the method can be applicable to the fields that evolve slowly such as mathematics or are highly specialized like entomology and zoology.Practical implications:This study helps researchers keep abreast of emerging trends and policy-makers formulate science and technology policies and strategic plans.Originality/value:This research provides insights into a quantitative assessment method to detect research fronts of a scientific field in its early development stage.展开更多
<div style="text-align:justify;"> Pomegranate flowers as row materials were used for extraction of polysaccharides by water-extraction and alcohol-precipitation method. After purification, the physical...<div style="text-align:justify;"> Pomegranate flowers as row materials were used for extraction of polysaccharides by water-extraction and alcohol-precipitation method. After purification, the physical and chemical properties, structure, monosaccharide composition and molecular weight were studied. The results showed that the polysaccharides from pomegranate flowers mainly contained two kinds of water soluble acidic polysaccharides, and monosaccharide composition were arabinose and galactose, both contained hydroxyl, carboxyl, amino, hydroxyl radical, sulfate, beta glycosidic bond and alpha glycosidic bond structure. The molecular weight of PP1 and PP2 were 6.16 × 104 (±6.6%) and 9.01 × 104 (±3.2%), respectively. The results of this study laid the foundation for further development and application of polysaccharides from pomegranate flowers. </div>展开更多
The current underwater terrain surface matching algorithm,which uses Hu moment as the similarity index,cannot gain accurate location due to the algorithm’s disadvantage in detecting slight differences.To solve this p...The current underwater terrain surface matching algorithm,which uses Hu moment as the similarity index,cannot gain accurate location due to the algorithm’s disadvantage in detecting slight differences.To solve this problem,a line-surface integrated terrain matching algorithm is presented.First,the similarity evaluation method of the traditional Terrain Contour Matching(TERCOM)algorithm is improved,and the strategy used to select the matching regions is developed.Then,a surface matching algorithm based on the geometric similarity is established to determine the optimum match between the reference maps and the actual measured terrains.Finally,a means of“line matching algorithm”and“surface matching algorithm”integration is proposed based on a fixed threshold.The experimental results show that the proposed algorithm can obtain a more accurate location and has greater robustness than that of the surface underwater matching algorithm based on Hu moment.展开更多
For the current automatic coastline generalization method,only one-line element is considered separately,but the relationship between the nearby elements is not effectively considered.A synergistic simplification meth...For the current automatic coastline generalization method,only one-line element is considered separately,but the relationship between the nearby elements is not effectively considered.A synergistic simplification method for multiple coastlines based on the hierarchical triangulation network partition(HTNP)is proposed in this paper.Firstly,the constrained Delaunay triangulation is constructed to partition the regions that can be simplified.Then,a hierarchical binary tree model to structure the morphological characteristics of the above several coastlines and the spatial proximity between different coastlines is constructed.Finally,the small curved and curved invisible parts of the coastline are deleted according to the visual constraints,and the narrow part between the coastline itself or the different coastlines is exaggerated appropriately,and the automatic simplification of the coastline is realized.The experimental results show that:①Relationships between the different coastlines are considered,and the shortcomings of considering the coastline separately are overcome;②Under the condition of the multiple coastlines in complex sea areas,the problem of collaborative simplification is solved,the quality of the coastlines are improved obviously,and the proposed method can be applied into more types of coastlines.展开更多
The sonic hedgehog protein not only plays a key role in early embryonic development, but also has essential effects on the adult nervous system, including neural stem cell proliferation, differentiation, migration and...The sonic hedgehog protein not only plays a key role in early embryonic development, but also has essential effects on the adult nervous system, including neural stem cell proliferation, differentiation, migration and neuronal axon guidance. The N-terminal fragment of sonic hedgehog is the key functional element in this process. Therefore, this study aimed to clone and analyze the N-terminal fragment of the sonic hedgehog gene. Total RNA was extracted from the notochord of a Sprague-Dawley rat at embryonic day 9 and the N-terminal fragment of sonic hedgehog was amplified by nested reverse transcription-PCR. The N-terminal fragment of the sonic hedgehog gene was successfully cloned. The secondary and tertiary structures of the N-terminal fragment of the sonic hedgehog protein were predicted using Jpred and Phyre online.展开更多
Based on the fractal theory,a normal contact stiffness model is established.In the model,the asperity is initially in elastic deformation under contact interference.As the interference is increased,a transition from e...Based on the fractal theory,a normal contact stiffness model is established.In the model,the asperity is initially in elastic deformation under contact interference.As the interference is increased,a transition from elastic to elastoplastic to full plastic deformation occurs in this order.The critical elastic interference,the first elastoplastic critical interference and the second elastoplastic critical interference are scale-dependent.According to the truncated asperity size distribution function,the relations between the total normal contact stiffness and the total contact load are obtained.The results show the total normal contact stiffness depends on the range of frequency indexes of asperities.The normal contact stiffness in elastic deformation is major contribution to the total normal contact stiffness.When the first six frequency indexes are less than the critical elastic frequency index,the dimensionless load-stiffness relation approximately isF^*r^(K^*r)^3.When the initial frequency index is greater than the critical elastic frequency index,the dimensionless load-stiffness relation approximately isF^*r^K^*r.The comparison between the theoretical results and the experimental results indicates that the theoretical results are consistent with the experimental data;therefore,the present fractal model of contact stiffness is reasonable.展开更多
Engineering oxygen vacancy formation and distribution is a powerful route for controlling the oxygen sublattice evolution that affects diverse functional behavior.The controlling of the oxygen vacancy formation proces...Engineering oxygen vacancy formation and distribution is a powerful route for controlling the oxygen sublattice evolution that affects diverse functional behavior.The controlling of the oxygen vacancy formation process is particularly important for inducing topotactic phase transitions that occur by transformation of the oxygen sublattice.Here we demonstrate an epitaxial nanocomposite approach for exploring the spatial control of topotactic phase transition from a pristine perovskite phase to an oxygen vacancy-ordered brownmillerite(BM)phase in a model oxide La_(0.7)Sr_(0.3)MnO_(3)(LSMO).Incorporating a minority phase NiO in LSMO films creates ultrahigh density of vertically aligned epitaxial interfaces that strongly influence the oxygen vacancy formation and distribution in LSMO.Combined structural characterizations reveal strong interactions between NiO and LSMO across the epitaxial interfaces leading to a topotactic phase transition in LSMO accompanied by significant morphology evolution in NiO.Using the NiO nominal ratio as a single control parameter,we obtain intermediate topotactic nanostructures with distinct distribution of the transformed LSMO-BM phase,which enables systematic tuning of magnetic and electrical transport properties.The use of self-assembled heterostructure interfaces by the epitaxial nanocomposite platform enables more versatile design of topotactic phase structures and correlated functionalities that are sensitive to oxygen vacancies.展开更多
Zn_(1-x)Mg_(x)O alloy films are important deep ultraviolet photoelectric materials.In this work,we used plasma-assisted molecular beam epitaxy to prepare Zn_(1-x)Mg_(x)O films with different magnesium contents on pola...Zn_(1-x)Mg_(x)O alloy films are important deep ultraviolet photoelectric materials.In this work,we used plasma-assisted molecular beam epitaxy to prepare Zn_(1-x)Mg_(x)O films with different magnesium contents on polar(0001)and nonpolar(1010)ZnO substrates.The nanoscale structural features of the grown alloy films as well as the interfaces were investigated.It was observed that the cubic phases of the alloy films emerged when the Mg content reached 20%and 37%for the alloy films grown on the(0001)and(1010)ZnO substrates,respectively.High-resolution transmission electron microscopy images revealed cubic phases without visible hexagonal phases for the alloy films with more than 70%magnesium,and the cubic phases exhibited three-fold and two-fold rotations for the alloy films on the polar(0001)and nonpolar(1010)ZnO substrates,respectively.This work aims to provide references for monitoring the Zn_(1-x)Mg_(x)O film structure with respect to different substrate orientations.展开更多
The mechanized large-ridge production technology of potato was summarized,including preparation before sowing,deep tillage and land preparation,deep application of chemical fertilizer,sowing,intertillage,disease and p...The mechanized large-ridge production technology of potato was summarized,including preparation before sowing,deep tillage and land preparation,deep application of chemical fertilizer,sowing,intertillage,disease and pest control,harvesting and other related contents.The comparative experimental study of large ridge and small ridge modes focused on the effects of ridge spacing on soil bulk density,temperature,water retention,crop growth and yield.The technology has the advantages of time saving,labor saving,seed saving,and fertilizer saving.It can significantly improve production efficiency,and is a high-yield and high-efficiency planting mode that increases potato yield.This model can increase yield by 370 kg/hm 2 and improve income by 160 yuan/hm 2.The results of this study have greatly promoted the promotion and application of mechanized largo-ridge potato planting technology.展开更多
基金financially supported by the HAAFS Science and Technology Innovation Special Project China(2022KJCXZX-LYS-9)the Natural Science Foundation of Hebei Province China(C2021301004)the Key Research and Dvelopment Program of Hebei Province China(20326401D)。
文摘Adjusting agronomic measures to alleviate the kernel position effect in maize is important for ensuring high yields.In order to clarify whether the combined application of organic fertilizer and chemical fertilizer(CAOFCF)can alleviate the kernel position effect of summer maize,field experiments were conducted during the 2019 and 2020 growing seasons,and five treatments were assessed:CF,100%chemical fertilizer;OFCF1,15%organic fertilizer+85%chemical fertilizer;OFCF2,30%organic fertilizer+70%chemical fertilizer;OFCF3,45%organic fertilizer+55%chemical fertilizer;and OFCF4,60%organic fertilizer+40%chemical fertilizer.Compared with the CF treatment,the OFCF1 and OFCF2 treatments significantly alleviated the kernel position effect by increasing the weight ratio of inferior kernels to superior kernels and reducing the weight gap between the superior and inferior kernels.These effects were largely due to the improved filling and starch accumulation of inferior kernels.However,there were no obvious differences in the kernel position effect among plants treated with CF,OFCF3,or OFCF4 in most cases.Leaf area indexes,post-silking photosynthetic rates,and net assimilation rates were higher in plants treated with OFCF1 or OFCF2 than in those treated with CF,reflecting an enhanced photosynthetic capacity and improved postsilking dry matter accumulation(DMA)in the plants treated with OFCF1 or OFCF2.Compared with the CF treatment,the OFCF1 and OFCF2 treatments increased post-silking N uptake by 66.3 and 75.5%,respectively,which was the major factor driving post-silking photosynthetic capacity and DMA.Moreover,the increases in root DMA and zeatin riboside content observed following the OFCF1 and OFCF2 treatments resulted in reduced root senescence,which is associated with an increased post-silking N uptake.Analyses showed that post-silking N uptake,DMA,and grain yield in summer maize were negatively correlated with the kernel position effect.In conclusion,the combined application of 15-30%organic fertilizer and 70-85%chemical fertilizer alleviated the kernel position effect in summer maize by improving post-silking N uptake and DMA.These results provide new insights into how CAOFCF can be used to improve maize productivity.
基金The work was supported by the National Natural Science Foundation of China(Grant Nos.82073934 and 81872937)to J.Y.
文摘cis-Diamminedichloroplatinum(CDDP)is widely used for the treatment of various solid cancers.Here we reported that CDDP increased the expression and enzymatic activities of carboxylesterase 1(CES1)and carboxylesterase 2(CES2),along with the upregulation of pregnane X receptor(PXR)and the downregulation of differentiated embryonic chondrocyte-expressed gene 1(DEC1)in human hepatoma cells,primary mouse hepatocytes,mouse liver and intestine.The overexpression or knockdown of PXR alone upregulated or downregulated the CES1 and CES2 expression,respectively.The increases in CES1 and CES2 expression levels induced by CDDP abolished or enhanced by PXR knockdown or overexpression,implying that CDDP induces carboxylesterases through the activation of PXR.Likewise,the overexpression or knockdown of DEC1 alone significantly decreased or increased PXR and its targets.Moreover,the increases of PXR and its targets induced by CDDP were abolished or alleviated by the overexpression or knockdown of DEC1.The overexpression or knockdown of DEC1 affected the response of PXR to CDDP,but not vice versa,suggesting that CDDP increases carboxylesterases by upregulating PXR mediated by the decrease of DEC1.In addition,CDDP did not increase DEC1 mRNA degradation but suppressed DEC1 promoter reporter activity,indicating that it suppresses DEC1 transcriptionally.The combined use of CDDP and irinotecan had a synergistic effect on two cell lines,especially when CDDP was used first.
基金supported by the Foundation for Excellent Youth Scholars of Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences(Y084941)the National Natural Science Foundation of China (41171027)
文摘Land use change (LUC) is widely recognized as one of the most important driving forces of global carbon cycles. The soil organic carbon (SOC) and labile organic carbon (LOC) stores were investigated at arable land (AL), artificial grassland (AG), artificial woodland (AW), abandoned arable land (AAL) and desert steppe (DS) in the Longzhong region of the Loess Plateau in Northwest China. The results showed that conversions from DS to AL, AL to AG and AL to AAL led to an increase in SOC content, while the conversion from DS to AW led to a decline. The differences in SOC content were significant between DS and AW at the 20-40 cm depth and between AL and AG at the 0-10 cm depth. The SOC stock in DS at the 0-100 cm depth was 39.4 t/hm 2 , increased by 28.48% after cultivation and decreased by 19.12% after conversion to AW. The SOC stocks increased by 2.11% from AL to AG and 5.10% from AL to AAL. The LOC stocks changed by a larger magnitude than the SOC stocks, which suggests that it is a more sensitive index of carbon dynamics under a short-term LUC. The LOC stocks increased at 0-20 cm and 0-100 cm depths from DS to AW, which is opposite to that observed for SOC. The proportion of LOC to SOC ranged from 0.14 to 0.20 at the 0-20 cm depth for all the five land use types, indicating low SOC dynamics. The allocation proportion of LOC increased for four types of LUC conversion, and the change in magnitude was largest for DS to AW (40.91%). The afforestation, abandonment and forage planting on arable land led to sequestration of SOC; the carbon was lost initially after afforestation. However, the carbon sink effect after abandonment may not be sustainable in the study area.
基金supported by the National Natural Science Foundation of China (41261047, 41201196, 41271133)the Youth Teacher Scientific Capability Promoting Project of Northwest Normal University (NWNU-LKQN-11-11)
文摘The quantitative research of wetland landscape fragmentation in the middle reaches of the Heihe River is important for the wetland and oasis sustainable development in the Hexi Corridor. Based on the data of remote sensing and GIS, we constructed the type change tracker model with sliding window technique and spatially morphological rule. The suitable scale and optimum scale of the fragmentation model of wetland landscape in the middle reaches of the Heihe River were determined by the area frequency statistics method, Chi-square distribution normalized scale variance, fractal dimension and diversity index. By integrating type change tracker model and the optimum scale with GIS spatial analysis, the spatial distribution characteristics of wetland landscape fragmentation in different periods and the related spatial-temporal change process were clarified. The results showed that(1) the type change tracker model, which analyzes the spatial pattern of wetland fragmentation on the pixel level, is better than the traditional wetland fragmentation analysis on the landscape and patch levels;(2) The suitable scale for the wetland fragmentation ranged from 150 m×150 m to 450 m×450 m and the optimum scale was 250 m×250 m in the middle reaches of the Heihe River; and(3) In the past 35 years, the total wetland area decreased by 23.2% and the fragmentation of wetland markedly increased in the middle reaches of the Heihe River. The areas of core wetlands reduced by 12.8% and the areas of perforated, edge and patch wetlands increased by 0.8%, 3.1% and 8.9%, respectively. The process of wetland fragmentation in the research region showed the order of core wetland, perforated or edge wetland, patch wetland or non-wetland. The results of this study would provide a reference for the protection, utilization and restoration of limited wetland resources and for the sustainable development of the regional eco-environment in the Heihe River Basin.
基金Supported by the Fundamental Research Funds for the Central Universities(JUSRP51611A,JUSRP51504)the Natural Science Foundation of Jiangsu Province(BK20171138)+1 种基金the National High Technology Research and Development Program of China(863 program,2013AA102101-5)the 111 Project(No.1112-06)
文摘Tyrosol is a pharmacologically active phenolic compound widely used in the medicine and chemical industries.Traditional methods of plant extraction are complicated and chemical synthesis of tyrosol is not commercially viable. In this study, a recombinant Escherichia coli strain was constructed by overexpressing the phenylpyruvate decarboxylase ARO10 from Saccharomyces cerevisiae, which could produce tyrosol from glucose. Furthermore,genes encoding key enzymes from the competing phenylalanine and tyrosine synthesis pathways and the repression protein TyrR were eliminated, and the resulting engineered strain generated 3.57 mmol·L^(-1) tyrosol from glucose. More significantly, codon optimization of ARO10 increased expression and tyrosol titer. Using the novel engineered strain expressing codon-optimized AR10 in shake-flask culture, 8.72 mmol·L^(-1) tyrosol was obtained after 48 h. Optimization of the induction conditions improved tyrosol production to 9.53 mmol·L^(-1)(1316.3 mg·L^(-1)). A higher titer of tyrosol was achieved by reconstruction of tyrosol synthetic pathway in E. coli.
基金supported by the Dalian Shipbuilding Industry Co., Ltd
文摘The added mass coefficient and the water level index formulas for the same-phase and anti-phase vibration of rectangular liquid tanks' bulkheads were derived based on dry mode theory. Three fluid-structure interaction numerical methods including Fluid FEM and Fluid BEM were used in this case. The comparison of numerical and theoretical results by the present method shows that ANSYS/Fluid80 is more credible, the NASTRAN/Virtual Mass Method is more suitable for engineering calculations and results of the same-phase vibration by the present method is more accurate.
基金This research was supported by the National Natural Science Foundation of China(Nos.41201293,31622007,31670237).
文摘In this study,we investigated the effects of environmental factors on plant phenolic variability,seasonal dynamics of total phenolic content(TP),extractable condensed tannins(ECT),protein-bound condensed tannins(PBCT),fiber-bound condensed tannins(FBCT),total condensed tannins(TCT),protein precipitation capacity(PPC)and nutrient content in the branchlets and fine roots of Casuarina equisetifolia.TP and TCT concentrations in branchlets were lowest in the spring,then increased in summer and autumn,similar to the seasonal dynamics in air temperature.TP and TCT concentrations in fine roots were highest in summer,coinciding with heavy precipitation.In general,TP and TCT concentrations were higher in branchlets than in fine roots.No significant difference was found in C concentration among various seasons for either branchlets or fine roots.Branchlets had significantly higher N and P concentrations than fine roots in most seasons.The C/N and N/P ratios in branchlets were significantly lower than in fine roots in all seasons,except summer.The relationship between branchlets and fine roots was significant for C,P and FBCT,but no significant relationships were found for N,TP,ECT,PBCT and TCT.Additionally,TP and TCT content were each significantly correlated with PPC in branchlets and in fine roots.Both TP/N and TCT/N ratios were highest in the autumn for the branchlets and in the summer for fine roots.The results indicate that high temperatures lead to increased tannin production in branchlets,but that the tannin content in fine roots is mainly affected by precipitation.Tannin content was greater in branchlets than in fine roots,which may indicate that selective pressure is greater on branchlets than on fine roots.
文摘Grazing and mowing are two common practices for grassland management. Mowing is now recommended as an alternative to the traditional grazing for grassland conservation in Inner Mongolia, northern China. Many studies have revealed that mowing may alter ecosystem properties in various ways. However, little attention has been paid to the effect of mowing on trace gas emissions, especially on N2O flux. We conducted an experiment to investigate the effects of mowing on N2O fluxes from the semiarid grassland in Inner Mongolia. The mowing experiment, which started in 2003, comprised four mowing intensity treatments, i.e. mowing heights at 2 cm, 5 cm, 10 cm and 15 cm above the soil surface, respectively, and a control (non-mowing), with five replicates. Gas fluxes were measured through a closed static chamber technique during the growing seasons (usually from May to September, depending on local climate at the time) of 2008 and 2009, respectively. Our results showed that mowing decreased N2O emissions, above-ground biomass and total litter production. N2O emissions were greater in May and June than in other sampling periods, regardless of treatments (P 2O fluxes were mainly driven by variations in soil moisture, except in July and August. In July and August, above-ground plant biomass and soil total nitrogen became the major drivers of N2O fluxes under the soil temperatures between 16 ° C and 18 ° C. Though there were some uncertainties due to the low frequency of N2O flux measurement, our study mainly indicated that 5 cm mowing height might decrease N2O emissions in grasslands during the growing season, and soil properties affected the magnitude of the reduction.
基金Supported by National Natural Science Foundation of China(21162030)College Student Innovation Fund Project of Xinjiang Medical University(CX201435)
文摘[Objective]Using fiber optic chemical sensor based fluorescence method to accurately determine the content of VB2tablets.[Method]VB2tablets were dissolved in aqueous solution and the detection system of fiber optic chemical sensor based fluorescence method was used to measure the spectrum of the solution and to quantitative analyze the content of VB2.[Result]With this method the maximum emission wavelength of VB2was 533 nm.The mass concentration was3.2×10-5-8×10-4mg/ml,which had good linear relationship with fluorescence intensity.The detection line was 1.55×10-8mg/ml and within-day precision was 0.19%while day to day precision was 1.2%,and the recovery was 97.9%-105.1%.[Conclusion]The degree of accuracy was high and the detection line was low when this method was used to determine the content of VB2tablets,and the results were satisfactory.
文摘Purpose:This study aims to detect research fronts of a scientific field in its early development stage using bibliometric indicators developed based on the features of research fronts.Design/methodology/approach:We first focused on conceptualization of"research fronts"and outlined 4 indicators to measure different aspects of the concept:Innovation,timeliness,stability and interdisciplinarity.Then research specialties obtained based on direct citation networks were evaluated with the 4 indicators and research fronts were identified.Finally,methodology was illustrated and verified in the research domain of complex networks.Findings:The results indicate that the proposed method is useful in detecting research fronts in a specific field which is at an early development stage.Research limitations:The quality of clustering results was not assessed.It needs to be further studied whether the method can be applicable to the fields that evolve slowly such as mathematics or are highly specialized like entomology and zoology.Practical implications:This study helps researchers keep abreast of emerging trends and policy-makers formulate science and technology policies and strategic plans.Originality/value:This research provides insights into a quantitative assessment method to detect research fronts of a scientific field in its early development stage.
文摘<div style="text-align:justify;"> Pomegranate flowers as row materials were used for extraction of polysaccharides by water-extraction and alcohol-precipitation method. After purification, the physical and chemical properties, structure, monosaccharide composition and molecular weight were studied. The results showed that the polysaccharides from pomegranate flowers mainly contained two kinds of water soluble acidic polysaccharides, and monosaccharide composition were arabinose and galactose, both contained hydroxyl, carboxyl, amino, hydroxyl radical, sulfate, beta glycosidic bond and alpha glycosidic bond structure. The molecular weight of PP1 and PP2 were 6.16 × 104 (±6.6%) and 9.01 × 104 (±3.2%), respectively. The results of this study laid the foundation for further development and application of polysaccharides from pomegranate flowers. </div>
基金The National Nature Science Foundation of China(Nos.414713804160149841774014)。
文摘The current underwater terrain surface matching algorithm,which uses Hu moment as the similarity index,cannot gain accurate location due to the algorithm’s disadvantage in detecting slight differences.To solve this problem,a line-surface integrated terrain matching algorithm is presented.First,the similarity evaluation method of the traditional Terrain Contour Matching(TERCOM)algorithm is improved,and the strategy used to select the matching regions is developed.Then,a surface matching algorithm based on the geometric similarity is established to determine the optimum match between the reference maps and the actual measured terrains.Finally,a means of“line matching algorithm”and“surface matching algorithm”integration is proposed based on a fixed threshold.The experimental results show that the proposed algorithm can obtain a more accurate location and has greater robustness than that of the surface underwater matching algorithm based on Hu moment.
基金National Natural Science Foundation of China(Nos.41871369,41901320,41471380)。
文摘For the current automatic coastline generalization method,only one-line element is considered separately,but the relationship between the nearby elements is not effectively considered.A synergistic simplification method for multiple coastlines based on the hierarchical triangulation network partition(HTNP)is proposed in this paper.Firstly,the constrained Delaunay triangulation is constructed to partition the regions that can be simplified.Then,a hierarchical binary tree model to structure the morphological characteristics of the above several coastlines and the spatial proximity between different coastlines is constructed.Finally,the small curved and curved invisible parts of the coastline are deleted according to the visual constraints,and the narrow part between the coastline itself or the different coastlines is exaggerated appropriately,and the automatic simplification of the coastline is realized.The experimental results show that:①Relationships between the different coastlines are considered,and the shortcomings of considering the coastline separately are overcome;②Under the condition of the multiple coastlines in complex sea areas,the problem of collaborative simplification is solved,the quality of the coastlines are improved obviously,and the proposed method can be applied into more types of coastlines.
基金sponsored by the Guangdong Provincial Natural Science Foundation,No.S2012010009592the Science and Technology Talent Foundation of Guangdong Provincial Natural Science Foundation,No.30900725+2 种基金the Joint Research Program by Southern Medical University-Shunde Guizhou Hospital,No.09000608the Science Foshan Municipal Key Project in Medical Sciences,No.201008063and the Shunde Medical Research Program,No.2011050
文摘The sonic hedgehog protein not only plays a key role in early embryonic development, but also has essential effects on the adult nervous system, including neural stem cell proliferation, differentiation, migration and neuronal axon guidance. The N-terminal fragment of sonic hedgehog is the key functional element in this process. Therefore, this study aimed to clone and analyze the N-terminal fragment of the sonic hedgehog gene. Total RNA was extracted from the notochord of a Sprague-Dawley rat at embryonic day 9 and the N-terminal fragment of sonic hedgehog was amplified by nested reverse transcription-PCR. The N-terminal fragment of the sonic hedgehog gene was successfully cloned. The secondary and tertiary structures of the N-terminal fragment of the sonic hedgehog protein were predicted using Jpred and Phyre online.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51105304,51475364)the China Postdoctoral Science Foundation funded project(Grant No.2014M552467).
文摘Based on the fractal theory,a normal contact stiffness model is established.In the model,the asperity is initially in elastic deformation under contact interference.As the interference is increased,a transition from elastic to elastoplastic to full plastic deformation occurs in this order.The critical elastic interference,the first elastoplastic critical interference and the second elastoplastic critical interference are scale-dependent.According to the truncated asperity size distribution function,the relations between the total normal contact stiffness and the total contact load are obtained.The results show the total normal contact stiffness depends on the range of frequency indexes of asperities.The normal contact stiffness in elastic deformation is major contribution to the total normal contact stiffness.When the first six frequency indexes are less than the critical elastic frequency index,the dimensionless load-stiffness relation approximately isF^*r^(K^*r)^3.When the initial frequency index is greater than the critical elastic frequency index,the dimensionless load-stiffness relation approximately isF^*r^K^*r.The comparison between the theoretical results and the experimental results indicates that the theoretical results are consistent with the experimental data;therefore,the present fractal model of contact stiffness is reasonable.
基金the support by National Natural Science Foundation of China(Grant No.62004200)Zhejiang Provincial Natural Science Foundation(Grant No.LZ21F040001)+1 种基金the support by Q-MEEN-Cfunded by the U.S.DOE-BES under award No.DE-SC0019273.
文摘Engineering oxygen vacancy formation and distribution is a powerful route for controlling the oxygen sublattice evolution that affects diverse functional behavior.The controlling of the oxygen vacancy formation process is particularly important for inducing topotactic phase transitions that occur by transformation of the oxygen sublattice.Here we demonstrate an epitaxial nanocomposite approach for exploring the spatial control of topotactic phase transition from a pristine perovskite phase to an oxygen vacancy-ordered brownmillerite(BM)phase in a model oxide La_(0.7)Sr_(0.3)MnO_(3)(LSMO).Incorporating a minority phase NiO in LSMO films creates ultrahigh density of vertically aligned epitaxial interfaces that strongly influence the oxygen vacancy formation and distribution in LSMO.Combined structural characterizations reveal strong interactions between NiO and LSMO across the epitaxial interfaces leading to a topotactic phase transition in LSMO accompanied by significant morphology evolution in NiO.Using the NiO nominal ratio as a single control parameter,we obtain intermediate topotactic nanostructures with distinct distribution of the transformed LSMO-BM phase,which enables systematic tuning of magnetic and electrical transport properties.The use of self-assembled heterostructure interfaces by the epitaxial nanocomposite platform enables more versatile design of topotactic phase structures and correlated functionalities that are sensitive to oxygen vacancies.
基金Project supported by the National Natural Science Foundation of China(Grant No.11804050).
文摘Zn_(1-x)Mg_(x)O alloy films are important deep ultraviolet photoelectric materials.In this work,we used plasma-assisted molecular beam epitaxy to prepare Zn_(1-x)Mg_(x)O films with different magnesium contents on polar(0001)and nonpolar(1010)ZnO substrates.The nanoscale structural features of the grown alloy films as well as the interfaces were investigated.It was observed that the cubic phases of the alloy films emerged when the Mg content reached 20%and 37%for the alloy films grown on the(0001)and(1010)ZnO substrates,respectively.High-resolution transmission electron microscopy images revealed cubic phases without visible hexagonal phases for the alloy films with more than 70%magnesium,and the cubic phases exhibited three-fold and two-fold rotations for the alloy films on the polar(0001)and nonpolar(1010)ZnO substrates,respectively.This work aims to provide references for monitoring the Zn_(1-x)Mg_(x)O film structure with respect to different substrate orientations.
基金Supported by Agricultural Machinery Promotion Station Project(HLBER2016002)
文摘The mechanized large-ridge production technology of potato was summarized,including preparation before sowing,deep tillage and land preparation,deep application of chemical fertilizer,sowing,intertillage,disease and pest control,harvesting and other related contents.The comparative experimental study of large ridge and small ridge modes focused on the effects of ridge spacing on soil bulk density,temperature,water retention,crop growth and yield.The technology has the advantages of time saving,labor saving,seed saving,and fertilizer saving.It can significantly improve production efficiency,and is a high-yield and high-efficiency planting mode that increases potato yield.This model can increase yield by 370 kg/hm 2 and improve income by 160 yuan/hm 2.The results of this study have greatly promoted the promotion and application of mechanized largo-ridge potato planting technology.
