Investigation of the Interaction Mechanism between Lignin Structural Units and Enzyme

The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with enzymes.Milled wood lignin(MWL)was isolated from different hardwoods of poplar,eucalyptus and acacia.The isolated lignin samples were characterized by elemental analysis,gel permeation chromatography,nitrobenzene oxidation and fourier infrared spectroscopy.The mechanism of lignin structural units on enzymatic hydrolysis of cellulose was studied by quartz crystal microbalance(QCM).The results showed that different structural units of lignin had different adsorption capacity for enzymes.The results of nitrobenzene oxidation indicated that the S/G ratio(S:syringyl-like lignin structures;G:guaiacyl-like lignin structures)of lignin of poplar was 0.99,that of eucalyptus was 1.92 and that of acacia was 1.34.According to the results of QCM,the adsorption capacity of the three lignin films was as follows:Poplar MWL(S/G ratio 0.99)<Acacia MWL(S/G ratio 1.34)<Eucalyptus MWL(S/G ratio 1.92).Eucalyptus MWL with higher degree of condensation and S/G ratio showed stronger affinity to enzymes and more non-productive adsorption with enzymes,resulting in less adsorption between enzymes and cellulose,and lower enzymatic hydrolysis efficiency.

Degradation of Alkaline Lignin in the Lactic Acid-Choline Chloride System under Mild Conditions

Lignin is a natural polymer,second only to cellulose in natural reserves.Degradation is one of the ways to achieve the high-value transformation of lignin.Deep eutectic solvent(DES)thermal degradation of lignin can be used as an excellent green degradation method.This paper introduces the degradation mechanism and effect of the lactic acid-choline chloride DES system in dissolving and degrading alkaline lignin,and the final solvent recovery.It can also be found from the scanning electron microscope(SEM)images that the surface of the degraded solid product is transformed from smooth to disordered.Fourier transform infrared(FTIR)spectroscopy and 1H-NMR spectroscopy were used to characterize the changes in lignin functional groups during DES treatment.The results showed that the content of phenolic hydroxyl groups increased after degradation,indicating that theβ-O-4 ether bond was broken.The molecular weight of the degraded lignin was observed by gel permeation chromatography(GPC),and the lignin residue with low molecular weight and narrow polydispersity index was obtained.The lowest average molecular weight(Mw)reached 2512 g/mol.The ratio of oxygen to carbon atoms in lignin increased substantially during degradation as measured by X-ray photoelectron spectroscopy(XPS),probably because DES treatment was accompanied by many oxidation reactions,which led to significant structural changes in lignin and a large number of ether bond breakage reactions during the reaction.The main final degradation products are aromatic monomers,vanillin,butyrovanillone,etc.

The influence of selective cutting of mixed Korean pine(Pinus koraiensis Sieb.et Zucc.) and broad-leaf forest on rare species distribution patterns and spatial correlation in Northeast China

This study aimed to demonstrate change in spatial correlation between Korean pine （Pinus koraiensis Sieb. et Zucc.） and three rare species, and change in spatial distribution of four species in response to a range of selective cutting intensities. We sampled three plots of mixed Korean pine and broad-leaf forest in Lushuihe Forestry Bureau of Jilin province, China. Plot 1, a control, was unlogged Korean pine broad-leaf forest. In plots 2 and 3, Korean pine was selectively cut at 15 and 30 % intensity, respectively, in the 1970s. Other species were rarely cut. We used point-pattern analysis to research the spatial distributions of four tree species and quantify spatial correlations between Korean pine and the other three species, Amur linden （Tilia amurensis Rupr.）, Manchurian ash （Fraxinus mandshurica Rupr.）, and Mongolian oak （Quercus mongolica Fisch.） in all three plots. The results of the study show that selective cutting at 15 % intensity did not significantly change either the species spatial patterns or the spatial correlation between Korean pine and broadleaf species. Selective cutting at 30 % intensity slightly affected the growth of Korean pine and valuable species in forest communities, and the effect was considered nondestructive and recoverable.

Sulfite-Formaldehyde Pulping and Oxygen Delignification of Wheat Straw

In this study,wheat straw pulp was prepared by sulfiteformaldehyde(SF) pulping combined with oxygen delignification to develop a sustainable methodology for chemical pulping of straw materials.The bleachability of oxygen-delignified SF pulp was also evaluated by hypochlorite bleaching.The results indicated that the Na_2SO_3 charge played an important role in lignin removal during SF pulping as well as oxygen delignification.The efficiency of oxygen delignification of wheat straw SF pulp was markedly high.After the oxygenation stage,the Kappa number decreased by over 50%(the original Kappa number of SF pulp was lower than 30) when the Na OH charge was in the range of 3%~5%.The optimal conditions for preparing bleached pulp via combined SF pulping and oxygen delignification involved the use of 12% of Na_2SO_3 and 3% of Na OH,respectively.Pulp with relatively high brightness,a low Kappa number,as well as an acceptable viscosity could be obtained when oxygen-delignified SF pulp was bleached with hypochlorite under a low active chlorine dosage.

Technical development and long-term performance observations of long-life asphalt pavement: A case study of Shandong Province

Based on the investigation of long-life asphalt pavement at home and abroad,the development of long-life asphalt pavement technology in Shandong Province,China is reviewed in this paper.The structural combination char-acteristics of typical long-life asphalt pavement in Shandong Province and their popularization and application are introduced.The application effect of combined base long-life asphalt pavement,which has been widely promoted,is evaluated.At the same time,taking the Binda perpetual pavement test road in Shandong Province as an example,the dynamic response and long-term performance evolution of long-life asphalt pavement are analyzed over a period of more than 17 years.Sections S1,S2,and S3 present information about full-depth asphalt pavement.Section S4 describes combined base asphalt pavement.The results show that the maximum strain of S1–S4 is within the endurance strain limit.S1,S2,S3 and S4 are all expected to be long-life asphalt pavements.In the current study,Sections S1–S4 were maintained in good condition during a service period of more than 17 years with no structural cracks and good deflection,rutting,and IRI indexes.The deflection index was stable without growth,and the IRI was also relatively stable following the opening to traffic.The rutting depth un-derwent a slight cumulative increase within 8 years of opening,and then stabilized.The average rutting depth over the 17-year period was less than 15 mm.Therefore,S1–S4 meet the design standards required for use as long-life pavements.From the perspectives of resource saving,energy saving,and emission reduction and service performance,full-depth asphalt pavement can be considered to represent a new generation of green and durable pavement structures with great future promotion potential.

Rice transcription factors OsLBD37/38/39 regulate nitrate uptake by repressing OsNRT2.1/2.2/2.3 under high-nitrogen conditions

Nitrate(NO_(3)^(-)) uptake involves a finely regulated and complex multilevel response system.Elucidating the molecular mechanism of nitrate uptake may lead to improving the growth and productivity of plants in the presence of dynamic variation in nitrate concentration.In this study,we identified three lateral organ boundaries domain(LBD)transcription factors,OsLBD37,OsLBD38,and OsLBD39,as regulators of nitrate uptake in response to nitrogen(N)availability.OsLBD37,OsLBD38,and OsLBD39 were induced by ammonium and glutamine in rice roots.Individual or collective knockout of OsLBD37,OsLBD38,and OsLBD39 led to increased concentrations of nitrate and increased expression of OsNRT2.1,OsNRT2.2,and OsNRT2.3respectively under high-N conditions,whereas overexpression of each of these three LBD genes produced opposite effects where N accumulation was reduced.Dual-luciferase reporter assay further confirmed that OsLBD37,OsLBD38,and OsLBD39 possessed transcription inhibitory activities in rice protoplast cells,downregulating the expression of OsNRT2.1/OsNRT2.2/OsNRT2.3.Yeast two-hybrid and bimolecular fluorescence complementation assays showed that OsLBD37 interacted with OsLBD37,OsLBD38,and OsLBD39in the nucleus.Together,these results show that OsLBD37,OsLBD38,and OsLBD39 collaborate to inhibit the expression of OsNRT2.1/OsNRT2.2/OsNRT2.3 transporters under N-sufficient conditions,thereby helping rice plants avoid excessive nitrate accumulation that may affect their growth.

A New Global Asymptotic Stability Result of Delayed Neural Networks via Nonsmooth Analysis

In the paper, we obtain new sufficient conditions ensuring existence, uniqueness, and asymptotic stability of the equilibrium point for delayed neural network via nonsmooth analysis, which makes use of the Lipschitz property of the functions. Based on this tool of nonsmooth analysis, we first obtain a couple of general results concerning the existence and uniqueness of the equilibrium point. Then we drive some new sufficient conditions ensuring global asymptotic stability of the equilibrium point. Finally, there are the illustrative examples feasibility and effectiveness of our results. Throughout our paper, the activation function is a more general function which has a wide application.

Effect of various aromatic compounds with different functional groups on enzymatic hydrolysis of microcrystalline cellulose and alkaline pretreated wheat straw

Low molecular aromatic compounds are detrimental to the enzymatic hydrolysis of lignocellu-lose.However,the specific role of their functional groups remains unclear.Here,a series of nine aromatic compounds as additives were tested to understand their effect on the hydrolysis yield of microcrystalline cellulose(MCC)and alkaline pretreated wheat straw.Based on the results,the inhibition of aldehyde groups on MCC was greater than that of carboxyl groups,whereas for the alkaline pretreated wheat straw case,the inhibitory effect of aldehyde groups was lower than that of carboxyl groups.Increased methoxyl groups of aromatic compounds reduced the inhibitory ef-fect on enzymatic hydrolysis of both substrates.Stronger inhibition of aromatic compounds on MCC hydrolysis was detected in comparison with the alkaline pretreated wheat straw,indicating that the substrate lignin can offset the inhibition to a certain extent.Among all aromatic com-pounds,syringaldehyde with one aldehyde group and two methoxyl groups improved the glucan conversion of the alkaline pretreated wheat straw.

A mild iodocyclohexane demethylation for highly enhancing antioxidant activity of lignin

Lignin,as a natural antioxidant,shows great potential in food engineering and medicine.How-ever,the inherent macromolecular structure,high polydispersity,and few phenolic hydroxy seri-ously limit its antioxidant activity.In this work,a mild iodocyclohexane demethylation for highly improving the antioxidant activity of lignin was proposed.The results showed-OCH 3 content exhibited an almost linear decrease as a function of treating time,and the demethylation and cleavage of𝛽-aryl ether bonds prompt an obvious increase in phenolic hydroxyl content(4.01 mmol/g)and a significant decline in aliphatic hydroxyl(∼0.03 mmol/g).Meanwhile,attributing to the fragmentation of𝛽β-O-4,β-β,and𝛽β-5 substructures,the polydispersity of lignin molecular weight decreases from 2.7 to 2.2.As a result,the formed catechol-typed lignin showed an out-standing antioxidant activity,with the radical(DPPH·)scavenging index(inverse of concentration for 50%of maximal effect(EC 50)value)over 2000 mL/mg,much superior to the commercial antioxidants(<500 mL/mg).Further structure-activity relationship analysis implied that the Ph-OH/-OCH 3 ratio might act as a key factor influencing the antioxidant activity of lignin.This mild demethylation demonstrates a facile and effective method for highly enhancing the antioxidant activity of lignin and makes the catechol-typed lignin a green and promising product for practical use in food,medicine,and pharmacy.

Efficacy and safety of ixekizumab in Chinese patients with plaque psoriasis

To the Editor:Psoriasis is a common,chronic papulosquamous skin disease occurring worldwide,presenting at any age,and leading to a substantial burden for individuals and society.Interleukin(IL)-17A is considered the key effector cytokine inducing psoriatic inflammation and tissue damage.[1]Ixekizumab is a humanized monoclonal immunoglobulin G specifically binding to and inhibiting IL-17A.The efficacy and safety of ixekizumab in patients with psoriasis have been clearly demonstrated in several randomized clinical trials,namely UNCOVER-1,UNCOVER-2,UNCOVER-3,and UNCOVER-J.[2,3]However,the clinical research data on ixekizumab in Chinese psoriasis patients remain limited.

Predicting community traits along an alpine grassland transect using field imaging spectroscopy

Assessing plant community traits is important for understanding how terrestrial ecosystems respond and adapt to global climate change.Field hyperspectral remote sensing is effective for quantitatively estimating vegetation properties in most terrestrial ecosystems,although it remains to be tested in areas with dwarf and sparse vegetation,such as the Tibetan Plateau.We measured canopy reflectance in the Tibetan Plateau using a handheld imaging spectrometer and conducted plant community investigations along an alpine grassland transect.We estimated community structural and functional traits,as well as community function based on a field survey and laboratory analysis using 14 spectral vegetation indices(VIs)derived from hyperspectral images.We quantified the contributions of environmental drivers,VIs,and community traits to community function by structural equation modelling(SEM).Univariate linear regression analysis showed that plant community traits are best predicted by the normalized difference vegetation index,enhanced vegetation index,and simple ratio.Structural equation modelling showed that VIs and community traits positively affected community function,whereas environmental drivers and specific leaf area had the opposite effect.Additionally,VIs integrated with environmental drivers were indirectly linked to community function by characterizing the variations in community structural and functional traits.This study demonstrates that community-level spectral reflectance will help scale plant trait information measured at the leaf level to larger-scale ecological processes.Field imaging spectroscopy represents a promising tool to predict the responses of alpine grassland communities to climate change.

Microscopic origin and relevant grain size effect of discontinuous grain growth in BaTiO_(3)-based ferroelectric ceramics

Barium titanate[BaTiO_(3)(BT)]-based ceramics are typical ferroelectric materials.Here,the discontinuous grain growth(DGG)and relevant grain size effect are deeply studied.An obvious DGG phenomenon is observed in a paradigmatic Zr^(4+)-doped BT-based ceramic,with grains growing from∼2.2–6.6 to∼121.8–198.4μm discontinuously near 1320℃.It is found that fine grains can get together and grow into large ones with liquid phase surrounding them above eutectic temperature.Then the grain boundary density(D g)is quantitatively studied and shows a first-order reciprocal relationship with grain size,and the grain size effect is dependent on D g.Fine grains lead to high D g,and then cause fine domains and pseudocubic-like phase structure because of the interrupted long-range ferroelectric orders by grain boundary.High D g also causes the diffusion phase transition and low Curie dielectric peak due to the distribution of phase transition temperature induced by internal stress.Local domain switching experiments reveal that the polarization orientation is more difficult near the grain boundary,implying that the grain boundary inhibition dominates the process of polarization orientation in fine-grain ceramics,which leads to low polarization but a high coercive field.However,large-grain ceramics exhibit easy domain switching and high&similar ferroelectricity.This work reveals that the grain boundary effect dominates the grain size effect in fine-grain ceramics,and expands current knowledge on DGG and grain size effect in polycrystalline materials.

Experimental investigation of the stimulated Raman scattering effect in high-power nanosecond superfluorescent fiber source

In this work,we experimentally investigate the dependence of the stimulated Raman scattering(SRS)effect on the seed linewidth of a high-power nanosecond superfluorescent fiber source(ns-SFS).The results reveal that the SRS in the ns-SFS amplifier is significantly influenced by the full width at half maximum(FWHM)of the ns-SFS seed,and there is an optimal FWHM linewidth of 2 nm to achieve the lowest SRS in our case.The first-order SRS power ratio increases rapidly when the seed’s linewidth deviates from the optimal FWHM linewidth.By power scaling the ns-SFS seed with the optimal FWHM linewidth,a narrowband all-fiberized ns-SFS amplifier is achieved with a maximum average power of 602 W,pulse energy of 24.1 mJ and corresponding peak power of 422.5 kW.This is the highest average power and pulse energy achieved for all-fiberized ns-SFS amplifiers to the best of our knowledge.

Lignocellulose pretreatment by deep eutectic solvents and related technologies:A review

Lignocellulose is the main component of plants and has a wide range of sources.The high-value production of lignocellulose lies in the biorefinery of lignin,cellulose and hemicellulose.The ad-vantages and disadvantages of traditional lignocellulose pretreatment methods were summarized,and the effective pretreatment parameters were listed.As a green solvent system with excellent performance,deep eutectic solvents(DES)are considered to be the most potential biomass pre-treatment system.Based on this,the new trend and progress of DES in lignocellulose pretreatment were reviewed,focusing on the effects of distinct kinds of lignocellulose raw materials,distinct components of DES,distinct reaction conditions and assisted by microwave ultrasound on the pre-treatment of lignocellulose,and the recyclability of DES solution system was discussed.Finally,the application and development direction of DES in lignocellulose pretreatment are proposed and prospected.

“四个一体化”破解长寿命沥青路面技术瓶颈

改革开放40年来,我国高速公路建设从无到有,公路建设能力已经达到世界先进水平.截至2019年12月,我国建成了世界最长的国家高速公路网,有力地支撑了经济的快速发展.然而,我国高速公路沥青路面仍面临着设计寿命短、社会与自然资源耗费大、运营维护成本高等诸多问题,难以满足全寿命周期技术经济最优化的要求.高速公路沥青路面的可持续发展亟待长寿命沥青路面技术的支撑.要科学构建我国高速公路长寿命沥青路面技术标准和技术体系,应首先了解高速公路可持续发展对长寿命沥青路面的迫切需求、长寿命沥青路面在我国的实践及发展现状.

Inhibition of Rac1-dependent forgetting alleviates memory deficits in animal models of Alzheimer's disease

Accelerated forgetting has been identified as a feature of Alzheimer's disease(AD),but the therapeutic efficacy of the manipulation of biological mechanisms of forgetting has not been assessed in AD animal models.Ras-re-lated C3 botulinum toxin substrate 1(Rac1),a small GTPase,has been shown to regulate active forgetting in Drosophila and mice?Here,we showed that Rac1 activity is aberrantly elevated in the hippocampal tissues of AD patients and AD animal models.Moreover,amyloid-beta 42 could induce Rac1 activation in cultured cells.The elevation of Rac1 activity not only accelerated 6-hour spatial memory decay in 3-month-old APP/PS1 mice,but also significantly contributed to severe memory loss in aged APP/PS1 mice.A similar age-dependent Rac1 activity-based memory loss was also observed in an AD fly model.Moreover,inhibition of Rac1 activity could ameliorate cognitive defects and synaptic plasticity in AD animal models.Finally,two novel compounds,identified through behavioral screening of a randomly selected pool of brain permeable small molecules for their positive effect in rescuing memory loss in both fly and mouse models,were found to be capable of inhibiting Rac1 activity.Thus,multiple lines of evidence corroborate in supporting the idea that inhibition of Rac1 activity is effective for treating AD-related memory loss.

THF_1 mutations lead to increased basal and wound-induced levels of oxylipins that stimulate anthocyanin biosynthesis via COI_1 signaling in Arabidopsis

Mutants defective in chloroplast development or photosynthesis are liable to accumulate higher levels of anthocyanin in photo-oxidative stress.However,regulatory mechanisms of anthocyanin biosynthesis in the mutants remain unclear.Here,we investigated the mechanism by which the deletion of thylakoid formation1（THF1） leads to an increased level of anthocyanin in Arabidopsis thaliana L.Physiological and genetic evidence showed that the increased level of anthocyanin in thf1 is dependent on coronatine-insensitive1（COM）signaling.Our data showed that thf1 had higher levels of basalα-linolenic acid（α-LeA）,and methyl jasmonate（JA）-induced α-LeA and 12-oxophytodienoic acid（OPDA） than the wild type（WT）.Consistently,expression levels of phospholipase genes including pPLAIIα and PLA-Iγ1 were elevated in thf1.Furthermore,inhibition of lipase activity by bromoenol lactone,a specific inhibitor of plant pPLA,led to producing identical levels of anthocyanins in WT and thf1 plants.Interestingly,OPDA biosynthesis was triggered by light illumination in isolated chloroplasts,indicating that new protein import into chloroplasts is not required for OPDA biosynthesis.Thus,we conclude that the elevated anthocyanin accumulation in thf1 is attributed to an increase in JA levels.This JA-mediated signaling to coordinate plant metabolism and growth in stress may be conserved in other photosensitive mutants.

Defective Etioplasts Observed in Variegation Mutants May Reveal the Light-Independent Regulation of White/Yellow Sectors of Arabidopsis Leaves

Leaf variegation resulting from nuclear gene mutations has been used as a model system to elucidate the molecular mechanisms of chloroplast development. Since most variegation genes also function in photosynthesis, it remains unknown whether their roles in photosynthesis and chloroplast development are distinct. Here, using the variegation mutant thylakoid formation1 （thfl） we show that variegation formation is light independent. It was found that slow and uneven chloroplast development in thfl can be attributed to defects in etioplast development in darkness. Ultrastructural analysis showed the coexistence of plastids with or without prolamellar bodies （PLB） in cells of thfl, but not of WT. Although THF1 mutation leads to significant decreases in the levels of Pchlide and Pchliide oxidoreductase （POR） expression, genetic and 5-aminolevulinic acid （ALA）-feeding analysis did not reveal Pchlide or POR to be critical factors for etioplast formation in thfl. Northern blot analysis showed that plastid gene expression is dramatically reduced in thfl compared with that in WT, particularly in the dark. Our results also indicate that chlorophyll biosynthesis and expression of plastidic genes are coordinately suppressed in thfl. Based on these results, we propose a model to explain leaf variegation formation from the plastid development perspective.

RETRACTED ARTICLE:Human H9N2 Avian Influenza Infection:Epidemiological and Clinical Characterization of 16 Cases in China

The authors are retracting this paper owing to errors in the reported data.The paper claimed that 16 patient cases were infected with H9N2 virus.However,when the authors recently further investigated all the thirteen sera samples,no anti-H9N2 antibodies were found by the haemagglutination inhibition assay.Moreover,re-sequencing of the remaining five throat swabs showed all five samples were H1N1 virus.

Effect of microbial fermentation on the sensory characteristics and chemical compositions of Chinese sweet tea(Lithocarpus litseifolius(Hance)Chun)

Sweet tea,which has hundreds of years of use among in Chinese folk,is a traditional herbal tea with pleasant sweetness,bitterness and astringency.In the current study,we used traditional microbial fermentation to improve sensory characteristics of sweet tea,especially for the reduction of bitterness and astringency.The dynamic changes of non-volatile,volatile compounds and microbial community were investigated during microbial fermentation.The contents of polyphenols,flavonoids,soluble sugar,soluble protein,catechins and dihydrochalcones decreased significantly while the tea pigments,free amino acids and gallic acid content inversely increased during microbial fermentation.A total of 61 volatile compounds were identified and quantified in sweet tea,of which 20 key compounds were identified as odor active compounds(OAV),including 3 aldehydes,1 ketone,4 alcohols,9 esters,4 alkenes and 3 other compounds.In addition,eight fungi and four bacteria were considered as core microorganisms,such as Aspergillus,Alternaria,Cladosporium,Epicoccum,Itersonilia,Penicillium,Periconia,Wallemia,Aureimonas,Enterobacter,Klebsiella and Stenotrophomonas,which were significantly correlated with non-volatile compounds and flavor compounds.These results provided theoretical guidance for processing of fermented sweet tea.