IRON MAN (IMA) peptides have a critical role in iron uptake and homeostasis, but whether and how they associate with plant immunity signaling remain unclear. Recently, Cao et al. provided intriguing insights into the underlying plant mechanisms that restrict root iron acquisition on perception of microorganism-associated molecular patterns (MAMPs) by spatial IMA-1 turnover.

The combustion of biomass fuels has been a significant source of global energy, and about 10 million tons of straw are used annually, yielding at least 0.5 million tons of straw ash. However, the ash from rice straw has rarely been reused, thereby contributing to environmental pollution. A new approach is reported for preparing mesoporous silica aerogels using straw ash-based biosilica via a sol-gel process and vacuum freeze drying. The mesoporous structure, porosity, pore volume, and specific surface area of this straw ash-based aerogel had satisfactory values. Effects of pH on the synthesis of silica aerogel were investigated to better understand the most important factors influencing the gelation, final structure, physicochemical properties, morphology, and thermostability of the samples.

Ethylene glycol and caprolactam were added during the synthesis process of melamine formaldehyde (MF) resins to develop a new MF formulation with high flexibility, storage stability, and low formaldehyde emissions that can be used for the impregnation of papers. It was demonstrated that the MF resins with amounts of ethylene glycol (molar ratio of ethylene glycol to melamine was 1.0) and caprolactam (molar ratio of caprolactam to formaldehyde was 0.12) achieved higher storage stability, flexibility, and lower free formaldehyde content. The impregnated papers made from these MF resins displayed good dry and wet tensile strength and passed the relevant standard specifications for decorative paper on wood-based panels. The size exclusion chromatography (SEC) and Fourier transform-infrared spectrometry (FT-IR) studies showed that the MF resins produced via incorporation of ethylene glycol and caprolactam had a different molecular weight distribution and polymeric structure.

The selective biodegradation of grape pomace tannins was studied using Aspergillus niger strains. The conditions were optimized in terms of monomeric catechin production. The optimal degradation conditions were: 10.0 g·L-1 of tannins in the induced medium, pH 6.5, and cultured on a shaking table at a rate of 120 r·min-1 at 28 °C for 36 h. The biodegraded tannins were used to partially substitute for phenol-formaldehyde in adhesive formulations. The biodegradation enabled the production of adhesives and wood panels with better properties (lower resin viscosity, higher internal bond strength, and lower thickness swelling). A particleboard in which the resin contained 60% biodegraded grape tannins displayed good performances (IBdry = 0.46 MPa, IBwet = 0.15 MPa) and passed the standard specifications for dry and wet conditions.

Dimethyldichlorosilane was used to improve the hydrophobicity of wood surface. The water contact angle of the treated wood surface increased from 85 degrees to 143 degrees, which indicated increased hydrophobicity. The nanomechanical properties of the wood cell wall were evaluated using a nanoindentation test to analyse the hydrophobic mechanism on the nano scale. The elastic modulus of the cell wall was significantly affected by the concentration but the influence of treatment time is insignificant. The hardness of the cell wall for treated samples was significantly affected by both treatment time and concentration. The interaction between treatment time and concentration was extremely significant for the elastic modulus of the wood cell wall.

纤维素是地球上储量最丰富的天然高分子.结晶度是表征聚合物性质的重要参数,结晶度越大材料的尺寸稳定性、强度、耐热性等特性越好,因此纤维素结晶度的研究对于生物质材料的研发与应用至关重要.现今纤维素结晶度的测定方法主要有密度法、X射线衍射光谱法、红外光谱法、核磁共振法、拉曼光谱法、近红外光谱法.生物质材料的高强度等特性,主要是来源于其含有的纤维素,而纤维素的结晶度更是表征其性质的主要参数.因此测量多种生物质的纤维素结晶度就具有重要的意义.归纳了生物质材料中提取的天然纤维素、再生纤维素以及微纳米级纤维素结晶度的研究结果,并对测定纤维素结晶度的新技术进行简要展望.

Molybdenum (Mo) deficiency in the farmland of China may limit biological nitrogen fixation (BNF), however, the impact of Mo application on BNF capacities and diazotrophic communities in rice-soil systems is unclear. In this experiment, treatments in a 6.7 atom% 15N2-labelling field-based growth chamber for 74 days and treatments in a 99 atom% 15N2-labelling microcosm experiment for 40 days combined with 16S rRNA gene sequencing and DNA-stable isotope probing (SIP) were used to investigate the impacts of Mo application on BNF and diazotrophic communities. Our results showed that under the condition that no nitrogen (N) fertilizer was applied, Mo application (500 g sodium molybdate ha-1) significantly increased N2 fixation in a rice-Inceptisol system, from 22.3 to 53.1 kg N ha-1. Mo application significantly increased the number of nifH gene copies and the relative abundance of cyanobacteria in both growth chamber and microcosm experiments. Among cyanobacteria, the relative abundances of the most abundant genera Leptolyngbya and Microcoleus were significantly increased by Mo application. 15N2-DNA-SIP further demonstrated that Leptolyngbya and Microcoleus incorporated 15N2. Mo application greatly increased BNF in Mo-deficient paddy field (≤0.068 mg kg-1) and stimulated the growth of cyanobacteria. These results indicated that Mo application in Mo-deficient paddy field could be a useful measure to increase soil N input under no N fertilization.

我国作为农业大国,丰富的粮食产量会伴随产生大量的农作物秸秆废弃物,焚烧秸秆既污染环境又会造成资源浪费.农作物秸秆中含有丰富的硅元素,而稻秸秆二氧化硅含量比其他秸秆多.提取稻秸秆材料中的二氧化硅,并用其制备新型材料,既可以变废为宝,减少环境污染,提高农作物秸秆的附加值,又有利于农业学科与其他学科的交叉.因此,分别利用硅酸钠和稻秸秆中的二氧化硅为硅源,通过真空冷冻干燥法制备二氧化硅气凝胶,并对气凝胶的微观形貌、密度、孔隙率以及组分进行分析,探讨较佳的制备工艺条件,研究以稻秸秆为原料制备生物质基气凝胶的可行性.结果表明,稻秸秆中提取得到的二氧化硅可以制备得到性能优异的生物质基二氧化硅气凝胶;在水玻璃与去离子水比例为1:10、凝胶pH值为7的工艺条件下得到二氧化硅气凝胶具有密度最低和孔隙率最大的特点,利用扫描电镜观测其孔隙结构最为均匀.

The inorganic magnesium-aluminium hydroxide composite flame retardant was prepared by coprecipitation method.Then flame retardant medium density fiberboard (MDF) was pressed using magnesium-aluminium hydroxide composite and aluminium hydroxide (ATH) as flame retardant,respectively.Effects of different inorganic metal hydroxide on heat release performace,mass loss,smoke performance and toxicity of MDF were discussed.The results showed that the ignition time of flame retardant MDF prolonged,the heat release rate and the total heat release decreased,the mass loss rate declined during combustion and the mass of residue increased after combustion,the smoke release and the production of CO2 and CO in flue gas decreased.It showed significant flame retardant and smoke suppression effects.Compared to ATH,the magnesium hydroxide (MH) and ATH had synergisitic flame retardant effect in inorganic hydroxide compound system.It could more effectively reduce the heat and smoke release of MDF,improve the fire resistance properties and reduce the dosage of flame retardant.

China,as a large agricultural country,produces a large number of straw wastes every year with abundant grain output.If we make full use of these straw waste resources and turn these straw wastes into treasures,it will increase the added value of biomass waste resources.In this study,rice straw was used to prepare biomass based silica by acid hydrolysis and pyrolysis methods.Biomass based water glass was prepared by biomass based silica mixed with NaOH.X ray fluorescence spectrometer (XRF) analysis was used to analyze mass fraction silica.The dissolution rate of silica was calculated.Effects of reaction temperature,time and concentration of sodium hydroxide on the dissolved silica and silica dissolution rate were explored by Box-behnken design.A quadratic regression polynomial model was built taking silica dissolution rate as a response value.The results indicated that the dissolution rate of SiO2 increased with the increase of reaction time,reaction temperature and concentration of NaOH solution.The interaction between reaction temperature and reaction time on SiO2 dissolution rate was significant.Reaction time and reaction temperature had secondary influence on SiO2 dissolution rate.From the RSM prediction,the better reaction time was 4.9 h,the better reaction temperature was 96.02℃,and the NaOH concentration was 4 mol · L-1.Under this technological condition,the dissolution rate of SiO2 was 84.54 ％.

In this paper, Penicillium sp. and Aspergillus oryzae were selected as biological strains to degrade grape pomace tannins to reduce its molecular weight and polymerization. The conversion and yield of catechin were chosen as index. The effects of carbon source, nitrogen source, culture time, culture temperature, pH and mass concentration of the tannins on the degradation of the tannins were studied. The results show that adding carbon and nitrogen sources is beneficial to the growth of microorganism strains. The incubation time is a key parameter influencing the intermedi-ate degradation products of the condensed tannins. The incubation temperature, pH and mass concentration of the tan-nins have different effects on the activity and degradation ability of the strains. The degradation ability of P. sp. strain is better than A. oryzae strain. The optimal degradation condition of P. sp. strains is that the mass concentration of the tannins in induced medium is 12.5 g/ L;the pH is 6.5;and the strains is cultured in shaking table at 28℃ for 24 h. The maximum mass concentration of the catechin is 0.32 mg/ mL, and the maximum conversion is 52. 3%. The opti-mal degradation condition of A. oryzae strains is that the mass concentration of the tannins in induced medium is 10. 0 g/ L;the pH is 6. 5;and the strains is cultured in shaking table at 28℃ for 36 h. The maximum mass concentration of the catechin is 0. 16 mg/ mL, and the maximum conversion is 32. 2%. It is possible to control the chemical composition of the grape pomace tannins and decrease its molecular weight and polymerization by microbial degradation method.

二氧化硅气凝胶因其优异的性质被广泛应用于各行各业,而农作物秸秆中也含有二氧化硅,若用其制备成秸秆基气凝胶,则可以将农作物秸秆变废为宝,提高其附加值,也有利于气凝胶产业的发展.本文以稻秸秆中的二氧化硅为硅源,通过真空冷冻干燥法制备二氧化硅气凝胶,并对其微观形貌、密度、孔隙率以及孔结构进行分析,评价秸秆基气凝胶的结构特性,并探讨较佳的制备工艺条件.结果表明:稻秸秆可以成功制备得到性能优异的二氧化硅气凝胶.较佳的工艺条件是秸秆基水玻璃和去离子水比例为1∶10,凝胶体系pH值为7,并在真空度为20Pa的条件下真空冷冻干燥24小时.得到的气凝胶振实密度为0.2 g/cm3,孔隙率在90％左右,吸附量最大可达230cm3/g,孔比表面积为154m2/g,平均孔径为17nm.

Urea-formaldehyde (UF) resin and phenol-formaldehyde (PF) resin played an important role in the production of wood-based panels like particleboard (PB),medium density fibreboard (MDF) and plywood.The bonding quality and the mechanical properties of wood-based panels mainly depend on adhesives qualities.Melamine has been added to the UF resins to improve its water resistance and lower formaldehyde emission.However,the melamine-ureaformaldehyde (MUF) resin is more brittle than the UF resin due to the high reactivity of melamine and the presence of rigid heterocycles in its structure.Diethylene glycol ether can react with the hydroxyl group of the MUF and act as the soft segment in the macromolecule of the MUF.Diethylene glycol ether modified the MUF adhesives was synthesized and applied for the preparation of plywood.The effects of diethylene glycol ether contents on the shear strength,modulus of elasticity (MOE),modulus of rupture (MOR),and impact strength of plywood were investigated in this study.The results showed that the curing time of modified MUF adhesive increased,and the shear strength of plywood decreased when the content of diethylene glycol ether was between 2％ and 8％.The flexural failure changed from brittle fracture to ductile fracture with diethylene glycol ether content of 2％-6％.Compared with the control samples,the MOE,MOR and impact strength of the plywood using modified MUF adhesives increased obviously.The optimal addition of diethylene glycol ether in the MUF adhesives was 2％,and the MOE,MOR and impact strength of the modified MUF adhesives manufactured plywood increased 66.7％,71.1％ and 100％,respectively,compared with those of the control samples.

选用氢氧化铝(ATH)与硼酸锌(ZB)组成的无机复合型阻燃剂压制阻燃稻草刨花板,采用锥形量热仪法研究不同配比的ATH和ZB对稻草刨花板阻燃性能的影响.结果表明:无机复合型阻燃剂能有效减少稻草刨花板的热释放和烟释放,减少烟气中CO和CO2的释放浓度,降低燃烧过程中的质量损失速率,表现出良好的阻燃抑烟效果;ATH与ZB具有协同阻燃作用,ZB的加入能有效提高复合阻燃剂的阻燃效果,减少ATH的用量,10％的ATH用量可达到比较好的阻燃效果.

Condensed tannins were extracted from grape pomace by acid precipitation and lyophilisation, respectively. Influence of the recovery methods on the chemical structure and composition of tannin extracts was investigated by using Carbon Nuclear Magnetic Resonance ( 13 C-NMR ) and Matrix?Assisted Laser Desorption/Ionization Time of Flight ( MALDI-TOF) Mass Spectrometry. The results showed that the procyanidin units played a dominait role in two kinds of condensed tannin extracts, and small proportion glucose and gallic acid substitutions bonded in procyanidin units which was linked together by C4-C8 bond. The polymerization degree of acidified condensed tannins was higher than that of ly?ophilized condensed tannins. In addition, relatively low carbonhydrate and high catechinc acid content in acidified con?densed tannins were observed compared with lyophilized condensed tannins. Different extraction methods had great influ?ence on the chemical composition of grape pomace tannin extracts.

Condensed tannins were extracted from grape pomace using a water medium in presence of three different bases as catalyst (NaOH, Na2CO3 or NaHCO3) and were characterized by FT-IR and MALDI-TOF spectrometry. It was demonstrated that the tannin extracts contained oligomers up to 6 repeating flavonoid units, with dominant procyanidin with a minor amount of prodelphinidin units. The structure of grape pomace tannin extracted did not present noticeable discrepancy exception of the ratio of the opening pyran ring which was different as a function of the catalyst used. Two different formulations (nonfortified tannin adhesive and fortified with addition of 20% of polymeric 4,4′-diphenyl methane diisocyanate (pMDI)) were used to press one layer particle board. It has been proved that the extraction processes largely affect the adhesive properties of the extracts obtained from the same raw material. Especially the particleboards prepared from tannins extracted using Na2CO3 as catalyst and without pMDI, give a high internal bonding value (IB = 0.45 MPa), which was good enough to pass relevant international standard specifications for interior grade panels. Formaldehyde emission of these panels is very low, well under the European Norm requirements (≤6.5 mg/100 g panel).

Organosolv lignins were extracted from lignocellulosic raw materials (Miscanthus x Giganteus and Empty Fruit Palm Bunch) and condensed tannins were extracted from grape by-product in an aqueous medium using different catalysts. Resin formulations with total polyphenolic contents (tannin and/or lignin) ranging from 70% to 95% of the total resin solids content were employed for the elaboration of particleboards. Mixtures of glyoxylated lignin/tannin and pure tannin were produced and tested. The importance of the nature of the basic reagent used for the extraction of tannins from grape pomace was demonstrated. Most of the adhesives produced yielded good internal bond strength results of the panels, enough to meet relevant international standard specifications for interior-grade panels (European Norm EN 312).

The extraction of condensed tannins from grape pomace was examined using water medium in the presence of different bases as catalyst (NaOH, Na2CO3, NaHCO3 and Na2SO3). Two different extraction processes and the influence of 4 parameters (i.e., temperature, reaction time, chemical reagents and concentration of the chemical reagents) on the tannin extracts yields and properties were studied. The tannin fractions were characterized by Fourier transform-infrared spectroscopy ( FT-IR), thermogravimetric analysis (TGA), carbon nuclear magnetic resonance spectroscopy (13C-NMR) and matrix assisted laser desorption ionization time of flight mass spectrometry ( MALDI-TOF ). It was demonstrated that it is possible to extract reactive tannins from grape pomace in basic medium. The tannin extracts obtained by precipitation in acidic conditions display a high phenolic content (Stiasny number higher 95%) but low water solubility and low reactivity toward formaldehyde because of the formation of catechinic acid phlobatannins during the acidification step. The tannins extracts obtained by lyophilization of the liquid, despite of their lower phenolic contents, displayed promising properties for adhesive applications. The optimum temperature of the extraction process was 100 °C, reaction time was 120 min; the best concentration of reagent was 10% (w/w). It was also shown that addition of sulphite ions during the extraction step improved the process :y the introduction of a sulfonic group through sulfitation increased both tannin solubility and reactivity as a result from the opening of the heterocyclic ring during extraction The structure of grape pomace sulfited tannin extracts did not present noticeable discrepancy exception of the ratio of the opening pyran ring which was different as a function of the catalyst used. The opening of pyran ring during the tannins extraction seem to be more important by using Na2CO3 and NaHCO3 than when using NaOH. The FT-IR bands assigned to aromatic ring vibration and carbonyl groups were stronger and no bands attributed to sulfited groups were tested detected in acidified tannins compared to lyophilized tannins. The TG2 results showed that the weight lost of these tannin extracts mainly composed of two steps. The first step starts from room temperature to 200 °C. It is attributed to the mass lost of water and some easy-degraded small low molecules. The secondly steps which is the mainly degradation step of tannin extract samples from 200 to 400 °C. The results from 13C-NMR showed that condensed tannin extracts from grape pomace were consistent with dominant procyanidin units with a minor amount of prodelphinidin units that are linked together by a C4-C8 bond. Relatively low carbonhydrate and high catechinc acid content was observed in acidified tannins compared to lyophilized tannins. It was shown by MADI-TOF experiments that grape pomace tannin extracts are mainly composed of flavoinoid oligomers up to 6 repeating units in lyophilized tannins and 10 repeating units in acidified tannins respectively, with dominant procyanidin units. A small proportion of substitution with glucose and gallic acid was detected in procyanidin units of polyflavonoid oligomers. The degree of polymerization of acidified tannins is higher than lyophilized tannins. Two different formulations (nonfortified tannin adhesive and fortified with addition of 20% of polymeric 4, 4'-diphenyl methane diisocyanate (p-MDI)) were used to press one layer wood particle board. It was shown that the nature of the extraction reagent (NaOH, Na2CO3 or NaHCO3) greatly impacts the properties of the resins and the mechanical properties of the panel internal bonding strengths. The particleboards bonded by the tannins extracted using Na2CO3 as catalyst give the best performance and were good enough to pass relevant international standard specifications for interior grade panels. Formaldehyde emission of these panels was below the European Norm requirements (<= 6.5 mg/ 100g panel)