Screening of a Composite Microbial System and Its Characteristics of Wheat Straw Degradation

To accelerate the decomposition of wheat straw directly returned to soil, we constructed a microbial system （ADS-3） from agricultural soil containing rotting straw residues using a 40-wk limited cultivation. To assess its potential use for accelerating straw decomposing, the decomposing characteristics and the microbial composition of ADS-3 were analyzed. The results indicated that it could degrade wheat straw and filter paper by 63.8 and 80%, respectively, during 15 d of incubation. Straw hemicellulose degraded dramatically 51.2% during the first 3 d, decreasing up to 73.7% by the end of incubation. Cellulose showed sustained degradation reaching 53.3% in 15 d. Peak values of xylanase and cellulase activities appeared at 3 and 11 d, with 1.32 and 0.15 U mL-1, respectively. Estimated pH averaged 6.4-7.6 during the degradation process, which approximated acidity and alkalinity of normal soils. The microbial composition of ADS-3 was stable based on denaturing gradient gel electrophoresis （DGGE） analysis. By using bacterial 16S rRNA and fungal 26S rRNA gene clone library analysis, 20 bacterial clones and 7 fungal clones were detected. Closest identified relatives of bacteria represented by Bacillus fusiformis, Cytophaga sp., uncultured Clostridiales bacterium, Ruminobacillus xylanolyticum, Clostridium hydroxybenzoicum, and uncultured proteobacterium and the fungi were mainly identified as related to Pichia sp. and uncultured fungus.

Research of Mechanical and Thermal Properties of Composite Material Based on Gypsum and Straw

This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards.This composite material is made of gypsum and reinforcing natural fibers.The article verifies whether this natural reinforcement can improve the investigated properties compared to conventional plasters and gypsum plasterboards made of pure gypsum.From this composite material,high-strength plasterboards could then be produced,which meet the higher demands of users than conventional gypsum plasterboards.For their production,natural waste materials would be used efficiently.As part of the development of new building materials,it is necessary to specify essential characteristics for their later use in civil engineering.Crushed wheat straw and three gypsum classes with strengths G2(2 MPa)—gypsum Class I.,G5(5 MPa)—gypsum Class II.and G16(16 MPa)—gypsum Class III.were used to create the test samples.Samples were made with different ratios of the two ingredients,with the percentages of straw being 0%,2.5%,and 5%for each gypsum grade.The first part of the article describes how the increasing proportion of straw affects the composite’s mechanical properties(flexural strength and compressive strength).The second part of the article focuses on the change of thermal properties(thermal conductivity and specific heat capacity).The last part of the article mentions the verification of the fire properties(single-flame source fire test and gross heat of combustion)of this composite material.The research has shown that the increasing proportion of straw reinforcement caused a deterioration in the flexural strength(up to 56.49%in the 3.series of gypsum Class II.)and compressive strength(up to 80.27%in the 3.series of gypsum Class III.)and an improvement in the specific heat capacity and thermal conductivity(up to 31.40%in the 3.series).This composite material is thus not suitable for the production of high-strength plasterboards,but its reduced mechanical properties do not prevent its use for interior plasters.Based on the performed fire tests,it can be said that this composite material can be classified as a non-flammable material of reaction to fire Classes A1 or A2.From an ecological point of view,it is advantageous to use a composite material with a higher straw content.

Effect of Cellulase and Lactic Acid Bacteria on Fermentation Quality and Chemical Composition of Wheat Straw Silage

The object of this study was to determine the effect of cellulase and lactic acid bacteria (LAB) on fermentation quality and chemical composition of wheat straw silage. Silages were prepared using a small-scale fermentation system and the moisture level was adjusted to 60% of fresh matter (FM) with deionized water. Treatments were designed as: control silage without additives, LAB inoculant Lactobacillus casei Z3-1 (1.0 × 106 cfu·g-1 of FM), commercial inoculant L. plantarum FG 1 (1.0 × 106 cfu·g-1 of FM), Z3-1 + cellulase and FG 1 + cellulase. The neutral detergent fiber (NDF), acid detergent fiber (ADF) and crude protein (CP) contents of the wheat straw prior to ensiling were 76.93%, 48.52% and 4.63% of dry matter (DM), respectively. After 30 days of fermentation, the silages treated with LAB and LAB + cellulase had a lower (P < 0.05) pH and higher (P < 0.05) lactic acid content than the control, and the coliform bacteria, yeast and mold were inhibited at the early stage of fermentation. Besides, silages treated with cellulase had lower (P < 0.05) values of ADF and NDF than the control. The results confirmed that the addition of cellulase and LAB contributed to improving the fermentation quality of wheat straw silage.

The effect of increased atmospheric temperature and CO_2 concentration during crop growth on the chemical composition and in vitro rumen fermentation characteristics of wheat straw

This experiment was conducted to investigate the effects of increased atmospheric temperature and CO2 concentration during crop growth on the chemical composition and in vitro rumen fermentation characteristics of wheat straw. The field experiment was carried out from November 2012 to June 2013 at Changshu （31°32′93″N, 120°41′88″E） agro-ecological experimental station. A total of three treatments were set. The concentration of CO2 was increased to 500 pmol/mol in the first treatment （CO2 group）. The temperature was increased by 2℃ in the second treatment （TEM group） and the concentration of CO2 and temperature were both increased in the third treatment （CO2 ＋ TEM group）. The mean temperature and concentration of CO2 in control group were 10.5 ℃ and 413μmol/mol. At harvesting, the wheat straws were collected and analyzed for chemical composition and in vitro digestibility. Results showed that dry matter was significantly increased in all three treatments. Ether extracts and neutral detergent fiber were significantly increased in TEM and CO2 ＋ TEM groups. Crude protein was significantly decreased in CO2＋TEM group. In vitro digestibility analysis of wheat straw revealed that gas production was significantly decreased in CO2 and CO2 ＋ TEM groups. Methane production was significantly decreased in TEM and CO2 ＋ TEM groups. Ammonia nitrogen and microbial crude protein were significantly decreased in all three treatments. Total volatile fatty acids were significantly decreased in CO2 and CO2 ＋ TEM groups. In conclusion, the chemical composition of the wheat straw was affected by temperature and CO2 and the in vitro digestibility of wheat straw was reduced, especially in the combined treatment of temperature and CO2.

Radiation grafting of poly(vinyl acetate) onto wheat straw and properties of the product

Poly(vinyl acetate)(PVAc) was grafted onto wheat straw by γ-irradiation to improve the compatibility between wheat straw and high-density polyethelene(PE).The grafting was proved by Fourier transform infrared(FTIR) spectroscopy. The compact structure of wheat straw was loosened because the chemical bonds and crystalline structure were destructed by the γ-rays. The modified wheat straw needed less energy for thermal transition, as revealed by differential scanning calorimetry(DSC).Thermal analysis revealed that grafted PVAc acted as a protective barrier for the wheat straw and leads to an increase in maximum pyrolysis temperature. The crystallite size of grafted wheat straw decreased to 5.33 nm from 5.63 nm before irradiation. There were holes in melted form appeared on the surface of the grafted wheat straws.Both the grafted PVAc and irradiation are beneficial to lower the torque of wheat straw/PE melts and improve its mechanical properties by 36%. Possible mechanism of irradiation grafting was proposed.

Gypsum-bonded particleboard manufactured from agricultural based material

Gypsum-bonded particleboard(GBPB) panels were made from various mixtures of particles of bagasse(Saccharum officinarum L.) and wheat straw(Triticum aestivum L.), bonded with different ratios of particle/gypsum. This study examined the feasibility of bagasse and wheat straw particles in the production of GBPB. One-layer experimental GBPBs with a density of 1.05 or 1.20 g·cm 3were manufactured at different ratios of bagasse/wheat straw, i.e., 100%/0%, 93.75%/6.25%, 87.5%/12.5%, 75%/25%, 50%/50%, 25%/75% and 0%/100% using two particle/ gypsum composite ratios, i.e., 1/2.75 and 1/3.25 by weight. Thickness swelling(TS), water absorption(WA), modulus of rupture(MOR), modulus of elasticity(MOE) and internal bond strength(IB) properties of the boards were evaluated and a statistical analysis was performed in order to examine the possible feasibility of these agricultural residues for use in commercial GBPB manufacturing. We determined that WA of panels decreases as the amount of straw increases to 100% and the LR/G(wood/gypsum) ratio decreases to 1/3.25, whereas the TS of panels decreases as the proportion of straw decreases to 0% and the LR/G ratio increases to 1/2.75. The experimental results also show that the MOR and MOE of panels containing 0%, 6.25% and 12.5% wheat straw with a LR/G ratio of 1/2.75 were higher than those of panels made from 25%–100% wheat straw with a LR/G ratio of 1/2.75, as well as those from all other percentages of straw with a LR/G ratio of 1/3.25. On the other hand, the IB of panels containing more than 12.5% straw with LR/G ratios of 1/2.75 and 1/3.25 were lower than those of panels made from 0–12.5% straw also with both LR/G ratios. Panels consisting of 0%, 6.25% and 12.5% wheat straw with LR/G ratios of 1/2.75 and 1/3.25 met the minimum EN standard requirements of mechanical properties for general purposes. All of the panels containing 0–100% wheat straw with a LR/ G ratio of 1/2.75 or 1/3.25 met the required level of TS for 24-h immersion.

微晶纤维素改性聚乙烯醇复合膜的性能及其作用机理

从麦秆中提取微晶纤维素(MCC),将其加入到聚乙烯醇(PVA)中对其进行改性,通过共混、流延制备了PVA/MCC复合膜。研究了NaOH用量对麦杆纤维素收率的影响,以及MCC用量对复合膜力学性能和热性能的影响,并考察了PVA/MCC复合膜的结构、微观形貌。结果表明:当NaOH质量分数为4%时,麦杆纤维素收率最大,为53.9%;加入MCC后,PVA/MCC复合膜的热稳定性提高;复合膜的力学性能随着MCC用量的增加先上升后下降,当MCC用量为9%(w)时,复合膜的拉伸强度及断裂标称应变均最大,分别较纯PVA提升了约191%,636%;MCC用量为12%(w)时,MCC在PVA中团聚,形成明显的“海岛”结构,导致复合膜的力学性能下降。

秸秆复合管地下灌溉对冬小麦生长与水分利用效率的影响

为了推进秸秆复合管地下灌溉技术的应用,以冬小麦为供试作物,通过田间试验,研究了秸秆复合管地下灌溉对冬小麦生长及水分利用效率的影响。结果表明,与无灌溉对照相比,秸秆复合管地下灌溉、地表滴灌和地下滴灌对冬小麦的生长与产量的提升均有促进作用,其中秸秆复合管地下灌溉的提升效果最显著。与地表滴灌相比,秸秆复合管地下灌溉显著提升了冬小麦起身期至抽穗期的株高、开花期之后的叶面积指数及地上干物质量,冬小麦穗长和穗粒数分别增加了5.84%和9.23%,产量提升了15.55%,水分利用效率与灌溉水利用效率分别提高了21.88%与15.55%,净收益提高了77.95%。与地下滴灌相比,秸秆复合管地下灌溉提高了冬小麦返青期后的株高、叶面积指数与开花期后的地上干物质量,冬小麦穗长和穗粒数分别增加了5.15%和9.8%,产量提高了5.11%,水分利用效率与灌溉水利用效率分别提高了8.81%与5.11%,净收益提升了23.53%。秸秆复合管地下灌溉有助于促进拔节期以后冬小麦生长,提高冬小麦的产量与水分利用效率,经济效益较高,在补充灌溉区对大田密植作物具有较好的推广应用前景。

Mechanical properties of straw basalt fiber reinforced concrete composites

One of the biggest problems responsible of the nonrenewable resources depletion and environmental issues is the construction industries,which generates large amounts of mineral waste and harmful emitted gases.Therefore,these problems generated the necessity to search for alternative natural building materials based on renewable resources.To study the mechanical characteristics and microstructural behavior of the concrete reinforced by raw wheat straw basalt fiber composite(RWSBFc),and treated rice straw basalt fiber composite(TRSBFc),a number of experimental tests were carried out with different composites ratios.Concrete compressive strength,splitting tensile strength,and flexural strength tests were considered as main parameters.The results showed that the RWSBFC has a positive effect on concrete flexural strength by increasing of 12.58%,compared with control samples.Also,it showed good enhancement in concrete flexibility and ductility.In contrast,both RWSBFc and TRSBFc showed uneven deterioration in concrete compressive strength and splitting tensile strength.To avoid the deterioration in compressive strengths of the various composites types,some improvement methods such as processors for the used straw,and adding some additives were recommended.

秸杆/聚丙烯复合材料

秸杆与聚丙烯复合制备了能替代木材使用的复合材料。考察了秸秆含量、界面处理剂用量对复合材料力学性能、流动性及形态的影响。结果表明 :复合材料的拉伸强度和冲击强度随秸杆含量增加而下降 ,但下降幅度较小 ;耐热性随秸杆含量增加而升高。处理剂效果较好 ,最佳用量为 8PHR。未经处理的复合材料随秸杆含量增加 ,其流动性先增加后逐渐降低 ;经处理过的复合材料流动性受秸杆含量影响不大。秸秆含量较少时 ,分散均匀 ;较多时有敛集现象 ,相畴较大 ;在某些含量时 ,秸秆有取向现象。

麦秸预处理方式对麦秸—无机凝胶复合材的影响

以麦秸、水泥和石膏为原料,通过单因子试验,研究原料预处理方式对麦秸/无机凝胶复合材性能的影响,并利用体视显微镜和扫描电子显微镜观察分析复合材的胶接状况。结果表明:麦秸经过稀碱处理或热水处理后,所制得的麦秸/水泥复合材和麦秸/石膏复合材物理力学性能较佳。

微生物菌喷施对集沟还田稻麦秸秆的影响

在稻麦轮作、秸秆集沟还田模式下,针对沟内秸秆因腐解过慢而妨碍下茬作物正常生长的问题,利用微生物复合菌对秸秆的催腐特性,采用已研制的稻麦联合收获开沟埋草多功能一体机的喷施功能,对沟内秸秆进行喷菌使其快速腐解还田。为考察菌剂对秸秆的腐解效果,设计了裂区对比试验。试验结果表明:观察期内,夏季麦秸秆在液体菌剂+覆土处理下腐解率达74.60%,远高于对照组(不施菌剂+覆土)的12.80%,也高于未覆土+液体菌剂处理的44.11%,表明适宜的菌剂对麦秸秆有较好的促腐效果;冬季稻秸秆在各菌剂处理下秸秆的腐解率均不超过30%,且与对照组无显著差异(P>0.05)。粉末状菌剂的各处理腐解率均在25%以下,促腐效果不明显,表明粉剂在该模式下适用性有限。该研究为集沟还田的秸秆进一步处理提供了参考。

用红外光谱法研究麦秸各层面的化学组成

本文以麦秸为例 ,用红外OMNI采样器研究了麦秸各层面红外光谱的差异 ,并进一步研究了麦草表面在不同的处理条件下 ,表面化学成分的变化规律。实验结果表明 :麦秸表面聚积着大量的SiO2 (～ 1 0 70cm- 1 ～ 80 0cm- 1 ) ,麦秸表皮层脂类物质含量高 (νCO =1 733cm- 1 )。麦秸表面的羟基 (～ 330 0cm- 1 )物质很少。麦秸的中层和内层主要是木素 ( 1 731 ,1 65 0 ,1 5 95 ,1 5 0 5 1 ,1 45 5 ,1 42 5 ,1 2 34,1 0 39和 835cm- 1 )和纤维素类物质 ( 335 0 ,2 935 ,2 85 0 ,1 65 0 ,1 45 5 ,1 430 ,1 367,1 31 7,1 1 60 ,1 0 34和 891cm- 1 )。木素的含量由外向里逐渐减少。麦秸表面的SiO2 是人造板制造中麦草不易粘接的主要原因。用热水处理后 ,表面仅有部分简单的碳水化合物和少量脂类物质溶出 ,而用NaOH处理麦草 ,可使表面的脂类物质和SiO2 溶出 ,便于人造板加工。

聚丙烯/麦秸秆木塑复合材料的力学性能

采用转矩流变仪混合造粒,通过注射成型方法制备了聚丙烯(PP)/麦秸秆木塑复合材料,研究了NaOH浓度、增容剂的含量和麦秸秆含量对PP/麦秸秆木塑复合材料力学性能的影响,采用扫描电子显微镜对麦秸秆表面及复合材料的断面形貌进行分析。结果表明:8%NaOH溶液处理麦秸秆时,PP/麦秸秆木塑复合材料的拉伸强度、弯曲强度和冲击强度达到最大;马来酸酐接枝PP增容剂的加入使得麦秸秆与PP的界面相容性提高,复合材料的力学性能增加;在一定范围内麦秸秆的添加降低了PP材料的拉伸强度和冲击强度,而提高了其弯曲强度,并且PP/麦秸秆复合材料的弯曲强度随着麦秸秆含量的增加而增加,在麦秸秆含量为30%时弯曲强度达到最大值为43.4 MPa。

麦秸/石膏复合材的工艺研究

以麦秸和石膏为原料,采用铺装生产工艺,通过单因子试验,研究原料形态、料膏比、乳白胶加入量和原料预处理方式等工艺因子对麦秸/石膏复合材性能的影响,并利用体视显微镜和扫描电子显微镜观察复合材的胶接状况。结果表明:料膏比10%、原料筛网目数10～20目、乳白胶的加入量12.5%、麦秸经热水处理3h,所制备的麦秸/石膏复合材各项物理力学性能较佳,指标可达到LY/T1598—2002石膏刨花板标准合格品的要求。

水泥基麦秸碎料复合材的制备工艺研究

以麦秸和水泥为原料,采用加压法生产工艺,研究了麦秸尺寸、灰秸比和原料预处理方式等工艺因子对水泥基麦秸碎料复合材性能的影响,并利用体视显微镜和扫描电子显微镜观察该复合材的胶接状况.结果表明：在灰秸比为7∶1（质量比,下同）,水灰比为0.4∶1,麦秸尺寸为0.95～0.60 mm,且利用稀碱对麦秸进行预处理,化学助剂（CaCl2）的施加量为水泥质量的7%,加压压力为2.5 MPa,加压时间为4 h,自然养生28 d,最终含水率约8%～12%的条件下,所制备的复合材各项物理力学性能较佳,其指标可达到JC 411—91《水泥木屑板》标准中的合格品要求.

有机基质配比对草莓幼苗生长的影响

以牛粪和小麦秸秆混合后作为腐熟物,将该腐熟物与消毒后的小麦壳按照9∶1、8∶2、7∶3的体积比分别混匀形成3种基质,并以园土栽培作为对照,研究3种混合基质对草莓幼苗生长及生理特性的影响。结果表明基质配比为8∶2时草莓幼苗的叶片数、株高、冠幅、叶面积、叶柄长、叶绿素含量、可溶性蛋白含量均高于对照,而超氧化物歧化酶(SOD)、过氧化物酶(POD)活性则低于对照,其他2种配比则相反。通过对草莓幼苗形态指标的比较以及相关生理指标的分析,认为在所设置的3种基质配比中草莓幼苗生长的最佳配比为8∶2,另外2种配比下幼苗生长效果均不及对照,不宜作为草莓的栽培基质。

木聚糖酶处理后麦草浆的表面形态及化学组成

采用木聚糖酶对麦草浆进行处理,研究了木聚糖酶处理对麦草浆表面形态及化学组成的影响.发现酶处理可以改变麦草浆的表面形态及化学组成,酶处理后的麦草浆变得柔软,纤维表面变得粗糙,出现明显的裂隙和沟槽.ESCA、SEM分析结果表明:经木聚糖酶处理后,麦草浆表面木素含量提高;且随着木聚糖酶用量的增加,处理后的麦草浆表面木素的含量也随之增加.

水热处理对麦秸化学构成的影响

采用傅立叶红外光谱(FTIR)法,分析了麦秸化学组成的层间差异,探讨了水热处理对麦秸表面基团构成的影响。结果表明:麦秸外表面被SiO2等无机矿物质覆盖,羟基浓度低;麦秸内部(包含内表层)主要由纤维素、半纤维素和木质素等构成,富含羟基官能团;经过水热处理,麦秸外表层部分简单碳水化合物和少量脂肪类物质溶出,热处理时间具有明显的影响;适度NaOH水热处理,可以同时去除碳水化合物、脂肪类物质和SiO2等无机矿物质。

秸秆/聚氯乙烯复合材料的初步研究

本文介绍了一种新型的秸秆处理方法 ,即将秸秆与聚氯乙烯复合制备替代木材使用的秸秆 /塑料复合材料。主要从秸秆含量、处理剂含量对复合材料的力学性能和成型加工性能的影响 ,以及复合材料的形态等方面进行了研究。