查看更多>>摘要：Tea oil camellia (Camellia oleifera Abel.) shell (TOCS) can annually provide about 1.8-million-ton lignocellulose resources for particleboard manufacturing in China, instead of discharging or burning that cause various forms of environmental pollution. In this study, different TOCS particle sizes were used in the core and surface layers of the 3-layer particleboard to systematically investigate the effects of particle geometry on physical and me-chanical properties, besides the macro and micro-structure. The results indicated geometry of TOCS particles in either core or surface layers plays a vital role in the properties of panels. Accordingly, using 100% TOCS particles in the mat-mixture with an overall 5% Polymethylene diphenyl diisocyanate adhesive exhibited a modulus of rupture and modulus of elasticity of 4.07 MPa and 664 MPa, respectively. The lower internal bonding was recorded for the smallest particle size in the core layer. It was also observed that 40% of TOCS particles in surfaces and wood particles in the core resulted in close mechanical properties and surface quality to the control panel. Although, an increase in surface layers particle size caused large inter-particle voids.
查看更多>>摘要：Escalating environmental concerns associated with the usage of plastic leads to the present study for developing a novel natural based biodegradable starch film with nanocellulose and nanohemicellulose reinforcements. An effective sequential strategy for enhancing the yield of high purity cellulose and hemicellulose from rice straw was developed by maximum lignin removal through microwave pre-treatment and complete separation of cellulose and hemicellulose by combined ultrasonic-alkali treatment. The two-step approach of microwave-assisted delignification and ultrasonic extraction produced a delignification of 84.51 +/- 1.21% and a yield of 0.282 +/- 0.011 g/g cellulose and 0.19 +/- 0.008 g/g hemicellulose. The proposed methodology produced cellulose of purity 93.37 +/- 2.43% and hemicellulose of purity 98.6 +/- 1.32%. The cellulose and hemicellulose were hydrolyzed to reduce their mean size to 198 +/- 14.9 nm and 141.2 +/- 23.7 nm respectively. SEM-EDX and TEM analysis confirmed that intense ultrasonication followed during the process resulted in the formation of spherical nanocellulose and nanohemicellulose. XRD analysis revealed that the isolated nanocellulose has a crystallinity of 88.66% and the nanohemicellulose were found to be semicrystalline. Spherical nanoparticle reinforced films exhibited uniformity and enhanced polymeric structure. Films prepared using 0.75% nanocellulose showed a higher tensile strength of 5.22 +/- 0.05 MPa, Young's modulus of 200.83 +/- 6.94 MPa and films reinforced with 0.75% nanohemicellulose resulted in tensile strength of 6.16 +/- 0.03 MPa and Young's modulus of 356.88 +/- 8.01 MPa respectively. The Water Vapor Permeability significantly reduced to 0.31 +/- 0.08 x 10(-9) gm(-1) s(-1) Pa-1 on addition of 1% nanocellulose and 0.32 +/- 0.05 x 10(-9) gm(-1) s(-1) Pa-1 on addition of 1% nanohemicellulose respectively. Onset degradation temperature increased to 290 ?& nbsp;and 280 ? for nanocellulose and nano-hemicellulose loaded films respectively. Results show that high purity hemicellulose was also attained along with cellulose by the proposed method and intense ultrasonication coupled with acid hydrolysis results in the production of spherical nanoparticles. Results also reveal that the underutilized hemicellulose poses an excellent prospect in film fabrication when reinforced as a nanoparticle by improving the mechanical and water vapor permeability.
查看更多>>摘要：The biggest challenge of utilizing lignocellulosic feedstocks for efficient ethanol fermentation is to improve strains and processes capable of mixed sugar fermentation in the presence of released inhibitors. A previously reported Saccharomyces cerevisiae strain WXY70 was further engineered to overexpress up to eight xylose metabolic genes or a transcription factor SPT2, and their efficacy in fermentation was evaluated in a simulated corn hydrolysate, resulting in two favored strains 8G-3 and SPT2(OE). SPT2(OE) produced 0.503 and 0.508 g ethanol/ g total sugars in ball milling-based and corn hydrolysates, respectively, within 24 h. Moreover, SPT2(OE) produced about 40 g/L ethanol from 120 g/L xylose mother liquid solution. Overall, the fermentation performance of SPT2 overexpression was superior to recently reported SFA1 overexpression and achieved promising results of ethanol yield and titer in different hydrolysates.
Rodriguez-Sanz, AndreaFucinos, ClaraTorrado, Ana M.Rua, Maria L....
13页
查看更多>>摘要：Wheat straw is a highly promising raw material for bio-refinery strategies. Most of the literature related to lignocellulose fractionation focuses on cellulose purification and hemicellulose solubilization. Pre-treatments for hemicellulose solubilization without the formation of undesired products usually reach low extraction yields, which leaves an important hemicellulose fraction unused. In this work, we propose a mild process for the efficient extraction of the hemicellulose fraction of wheat straw assisted by partial enzymatic hydrolysis with three commercial endo-xylanase cocktails. A first step with alkali at 40 oC helped to disrupt the lignocellulosic structure and removed 19% of lignin while maintaining most of the hemicellulose in the solid. The enzymatic step enabled reaching extraction yields of 59.8%, 51.9%, and 42.5% with Ultraflo L, Pentopan mono conc, and Shearzyme 500L, respectively. We also discuss the catalytic properties of each endo-xylanase, in particular, their adscription to the GH10 or GH11 glycosyl hydrolase family, and the relevant role of accessory enzymes.
查看更多>>摘要：Nuciferine is an aporphine alkaloid first isolated from Nelumbo nucifera Gaertn as the main bioactive ingredient. Additionally, it was also obtained from some other plants. Nuciferine exhibited diverse bioactivities such as antihyperlipidemic, anti-obesity, anti-fatty liver, antidiabetic, anti-hyperuricemic, antitumor, anti-inflammatory, antiviral, antioxidant activity, and thus has tremendous potential to be developed into drugs. This overview comprehensively summarized the widespread knowledge regarding to the chemistry and biology of nuciferine including isolation techniques, total synthesis, structural modification and structure-activity relationships, bioactivities, metabolism in vivo, and biosynthesis. Furthermore, an expectation was prospectively made for the future research on nuciferine through a careful analysis of the related literature up to early February 2022 and on the strength of our expertise in chemistry and biology of natural products.
查看更多>>摘要：Nanocellulose-based aerogels are widely used in various fields due to the lightweight and porous features. The pore structure plays a decisive role in the performances, but controllable fabrication of the nanocellulose-based aerogel with a tunable structure is still a challenge. Herein, we reported a facile approach to prepare nano-cellulose aerogel with a designable pore structure by ice-induced self-assembly. The relationship between the properties and structure was investigated by simply tuning factors such as temperature gradient, freezing rate, infiltration interface, and solute concentration. The as-prepared aerogel exhibited regulable density (2.35-15.96 mg/cm(3)), pore size (2 nm-500 mu m), and desirable flexibility which is suitable for thermal insulation application. The research provides new insight into the controllable preparation and functional application of nanocellulose-based aerogels.
查看更多>>摘要：Non-specific lipid transfer proteins (LTPs) comprise various protein families in plant responses to biotic and abiotic stresses. LTPGs encoding a glycosylphosphatidylinositol (GPI)-anchored lipid transfer protein are a large subgroup within the LTP family. We identified 36 PtLTPG genes in the poplar genome, divided into four subgroups based on phylogenetic analysis. A total of 29 PtLTPG genes were amplified from the poplar genome. PtLTPG1, 2, and 31 were localized to the plasma membrane and PtLTPG9 to the nucleus, suggesting functional dissimilarity. The PtLTPG genes were expressed in all poplar tissues tested, but the expression levels of PtLTPG7 and 11 were low. Most PtLTPG and FA-related genes were induced by abiotic stresses, and the expression patterns of PtLTPGs were associated with those of FA-related genes. The FA composition, including the ratio of linolenic acid to linoleic acid, was altered by osmotic stress. Taken together, our results show that PtLTPGs and FA-related genes mediate tolerance to osmotic stress by modulating the FA composition in poplar.
查看更多>>摘要：Phenolic additives, including 2-naphthol, 2-naphthol-7-sulfonate, and resorcinol were evaluated for their impact on the lignin re-polymerization and subsequent hydrolysis of bamboo residues. Low surface lignin concentration (65.68%) of the substrate and high Tg value (185 ?) of lignin was observed for 2-naphthol-7-sulfonate assisted pretreatment, leading to the most significant increase (14%) in enzymatic hydrolysis efficiency of pretreated bamboo residues. Meanwhile, physicochemical properties of lignin revealed that the introduced sulfonic acid groups increased the surface charge, decreased the molecular weight, promoted the cleavage of beta-O-4 linkages, and prevented the re-condensation of lignin. Even though resorcinol-assisted pretreatment, by contrast, was found to be an inhibitor for enzymatic hydrolysis. NMR analysis of modified lignin showed that resorcinol led to a higher amount of non-condensed phenolic OH groups and promoted the cleavage of beta-O-4 linkages, acting as an inhibitor in lignin re-polymerization during the dilute acidic pretreatment. In short, the above findings present a detailed view of suppressing lignin re-polymerization for boosting the utilization of bioresources with acidic pretreatment.
查看更多>>摘要：The mechanical performance and dimensional stability of bamboo is highly dependent on the microfibril orientation in its cell wall sublayers. However, a comprehensive and quantitative description of this orientation at the sublayer scale of cell wall is very challenging to do. Here, we proposed a new approach to quantitatively estimate the cellulose microfibril orientation across the whole cell wall of both fibers and parenchyma cells in bamboo. This new approach is based on the geometrical correlation between the actual and apparent dimensions of cellulose microfibril aggregates, which are respectively determinedly with CP/MAS C-13 NMR and high-resolution field emission scanning electron microscopy (FE-SEM). For comparison, the average microfibril angle (MFA) of both fibers and parenchyma cells were also measured using X-ray diffraction (XRD). It was concluded that the cellulose microfibrils in the broad sublayers of the bamboo fibers exhibited a relatively small MFA of about 10 degrees, while those in the narrow sublayers were nearly oriented in the transverse with a MFA of about 80 degrees. For parenchyma cells, the MFA of the broad and narrow sublayers were estimated to be 50-70 degrees and 70-80 degrees, respectively. Modified cell wall structural models for the two types of cells were then proposed.
NSTL
Elsevier