Explore the vast range of titles available.

Silicon (Si) plays a large number of diverse roles in plants, but the structural and chemical mechanisms operating at the single‐cell level remain unclear. We isolate the cell walls from suspension‐cultured individual cells of rice (Oryza sativa) and fractionate them into three main fractions including cellulose (C), hemicellulose (HC) and pectin (P). We find that most of the Si is in HC as determined by inductively coupled plasma‐mass spectrometry (ICP‐MS), where Si may covalently crosslink the HC polysacchrides confirmed by X‐ray photoelectron spectroscopy (XPS). The HC‐bound form of Si could improve both the mechanical property and regeneration of the cell walls investigated by a combination of atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). This study provides further evidence that HC could be the major ligand bound to Si, which broadens our understanding of the chemical nature of ‘anomalous’ Si in plant cell walls.

A new method was developed to quickly produce carboxymethyl hemicellulose (CM-Hemi) and fluorescent nitrogen-doped carbon dots (N–CDs) from sugarcane bagasse (SB). These materials were then combined with calcium chloride (CaCl₂) to create hydrogel sensors with antibacterial and antifungal properties. The CM-Hemi@Ca-N–CDs hydrogel was effective against both Gram-negative ( Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria compared to CM-Hemi@Ca which give no antibacterial activity. Both hydrogels also exhibited antifungal properties against Candida albicans . Molecular docking studies revealed that the CM-Hemi@Ca-N–CDs hydrogel had strong binding interactions with the protein from Staphylococcus aureus and Candida albicans (1.92 A°) compard to Escherichia coli (2.01 A°), which was aligned with the inhibition zone measurements from the antibacterial test. The fluorescence microscope revealed differences in the emitted light color when the hydrogel interacted with different types of microorganisms, likely due to variations in their cell walls. Density functional theory (DFT) calculations indicate that the incorporation of N–CDs into the CM-Hemi@Ca hydrogel enhances its stability and rigidity. This is evidenced by the lower energy gap (E g ), higher electron affinity (μ), and lower softness (S) of the CM-Hemi@Ca-N–CDs compared to the CM-Hemi@Ca hydrogel. Additionally, the formation of amide bonds between the N–CDs and CM-Hemi contributes to the increased rigidity of the hydrogel.These findings supporting th effectiveness of CM-Hemi@Ca-N–CDs as an antibacterial/antifungal sensor.

The straw return method has been increasingly implemented in rice production in Northeast China. In-depth studies on the characteristics of rice straw decomposition are of great importance for achieving sustainable agricultural development. In this study, the nylon mesh bagging method was used to study the patterns of rice straw decomposition and nutrient release during a 5-year period of rice growth. The results showed that straw decomposition occurred mainly during the first 3 years after straw return, with the cumulative amount of decomposition reaching 77.0%, and that the rate of straw decomposition decreased linearly with time. The release of carbon, nitrogen, cellulose and hemicellulose occurred mainly during the first and second years after straw return. Moreover, the release of phosphorus and potassium occurred mainly during the first month after straw return, and lignin was released at various rates throughout the entire study period. These results indicated that straw returned to the soil acts both as a source of phosphorus and potassium in the short term and as a source of nitrogen and carbon in the long term during the rice growing season in Northeast China.

Plant cells build nanofibrillar walls that are central to plant growth, morphogenesis and mechanics. Starting from simple sugars, three groups of polysaccharides, namely, cellulose, hemicelluloses and pectins, with very different physical properties are assembled by the cell to make a strong yet extensible wall. This Review describes the physics of wall growth and its regulation by cellular processes such as cellulose production by cellulose synthase, modulation of wall pH by plasma membrane H+-ATPase, wall loosening by expansin and signalling by plant hormones such as auxin and brassinosteroid. In addition, this Review discusses the nuanced roles, properties and interactions of cellulose, matrix polysaccharides and cell wall proteins and describes how wall stress and wall loosening cooperatively result in cell wall growth.Plant cells assemble a strong yet extensible primary cell wall consisting largely of polysaccharides. Emerging models of wall growth integrate physical properties such as mechanical strength and tension with cellular processes that govern wall loosening and expansion.

Capirona ( Calycophyllum spruceanum (Benth.) K. Schum.) and Bolaina ( Guazuma crinita Lam.) are fast-growing Amazonian trees with increasing demand in timber industry. Therefore, it is necessary to determine the content of cellulose, hemicellulose, holocellulose and lignin in juvenile trees to accelerate forest breeding programs. The aim of this study was to identify chemical differences between apical and basal stem of Capirona and Bolaina to develop models for estimating the chemical composition using Fourier transform infrared (FTIR) spectra. FTIR-ATR spectra were obtained from 150 samples for each species that were 1.8 year-old. The results showed significant differences between the apical and basal stem for each species in terms of cellulose, hemicellulose, holocellulose and lignin content. This variability was useful to build partial least squares (PLS) models from the FTIR spectra and they were evaluated by root mean squared error of predictions (RMSEP) and ratio of performance to deviation (RPD). Lignin content was efficiently predicted in Capirona (RMSEP = 0.48, RPD > 2) and Bolaina (RMSEP = 0.81, RPD > 2). In Capirona, the predictive power of cellulose, hemicellulose and holocellulose models (0.68 < RMSEP < 2.06, 1.60 < RPD < 1.96) were high enough to predict wood chemical composition. In Bolaina, model for cellulose attained an excellent predictive power (RMSEP = 1.82, RPD = 6.14) while models for hemicellulose and holocellulose attained a good predictive power (RPD > 2.0). This study showed that FTIR-ATR together with PLS is a reliable method to determine the wood chemical composition in juvenile trees of Capirona and Bolaina.

Lignocellulose nanofibrils (LCNFs) are nano-objects produced in aqueous suspension by industrially adaptable methods, with a high yield, low production cost and the potential to replace or complement delignified cellulose nanofibrils in their current applications. To this end, it is necessary to understand how their constituents affect the production and characteristics of the final product. This review explores the most recent results on the effect of the residual amount of lignin and hemicelluloses on the properties of LCNF suspensions. In the current literature, there is a consensus on hemicelluloses, a larger amount of which favors the mechanical fibrillation process, with mannans providing the greatest benefits. Meanwhile, there is no consensus on the effect of residual lignin on mechanical fibrillation, since it can act as an antioxidant, which promotes fibrillation, or as a cementing agent, which hinders fibrillation and, therefore, the production of LCNFs.

Parenchyma cells and fibers are the two dominant types of cells in the bamboo culm. Their mechanical and biological functions in bamboo differ substantially, derived from their cell wall structures and chemical compositions. The objective of this work was to comparatively study the hygroscopicity and the thermal degradation of bamboo fibers and parenchyma cells in order to better understand how to optimize heat treatment of bamboo. FTIR spectroscopy showed that parenchyma cells had a higher hemicellulose content and higher S/G lignin ratio than bamboo fibers based on the spectral changes at 1602 cm−1 with respect to 1505 cm−1. Upon heat treatment, spectral changes related to esterification reactions and loss of hydroxyl groups were observed. The heat treatment reduced hygroscopicity of parenchyma cells more than for bamboo fibers due to their lower thermal stability attributed to the higher hemicellulose content and less compact cell wall structure. Although heat treatment at 180 °C could improve the thermal stability of bamboo, mild heat treatments at 140 °C and 160 °C were found to be adequate to facilitate the degradation of bamboo.

Chiral asymmetry is important in a wide variety of disciplines and occurs across length scales. While several natural chiral biomolecules exist only with single handedness, they can produce complex hierarchical structures with opposite chiralities. Understanding how the handedness is transferred from molecular to the macroscopic scales is far from trivial. An intriguing example is the transfer of the handedness of helicoidal organizations of cellulose microfibrils in plant cell walls. These cellulose helicoids produce structural colors if their dimension is comparable to the wavelength of visible light. All previously reported examples of a helicoidal structure in plants are left-handed except, remarkably, in the Pollia condensata fruit; both left- and right-handed helicoidal cell walls are found in neighboring cells of the same tissue. By simultaneously studying optical and mechanical responses of cells with different handednesses, we propose that the chirality of helicoids results from differences in cell wall composition. In detail, here we showed statistical substantiation of three different observations: 1) light reflected from right-handed cells is red shifted compared to light reflected from left-handed cells, 2) right-handed cells occur more rarely than left-handed ones, and 3) right-handed cells are located mainly in regions corresponding to interlocular divisions. Finally, 4) right-handed cells have an average lower elastic modulus compared to left-handed cells of the same color. Our findings, combined with mechanical simulation, suggest that the different chiralities of helicoids in the cell wall may result from different chemical composition, which strengthens previous hypotheses that hemicellulose might mediate the rotations of cellulose microfibrils.

This review is a summary of the Raman spectroscopy applications made over the last 10 years in the field of cellulose and lignocellulose materials. This paper functions as a status report on the kinds of information that can be generated by applying Raman spectroscopy. The information in the review is taken from the published papers and author’s own research—most of which is in print. Although, at the molecular level, focus of the investigations has been on cellulose and lignin, hemicelluloses have also received some attention. The progress over the last decade in applying Raman spectroscopy is a direct consequence of the technical advances in the field of Raman spectroscopy, in particular, the application of new Raman techniques (e.g., Raman imaging and coherent anti-Stokes Raman or CARS), novel ways of spectral analysis, and quantum chemical calculations. On the basis of this analysis, it is clear that Raman spectroscopy continues to play an important role in the field of cellulose and lignocellulose research across a wide range of areas and applications, and thereby provides useful information at the molecular level.

A process is described for the transformation of bulk wood into a low-cost, strong, tough, lightweight structural material, by the partial removal of lignin and hemicellulose followed by hot-pressing to densify the natural wood. Stronger material comes out of the woodwork Densification is a common processing route for wood, but defects often remain and wood can be susceptible to weakening in the presence of humidity. This paper reports a method for treating wood before densification in order to substantially enhance its strength and resilience. The authors show that partially removing lignin and hemicellulose from the wood makes it around three times denser, with an 80% reduction in thickness. However, complete removal of lignin and hemicellulose results in a poor-quality material, leading the authors to suggest that some lignin must be retained to bind the wood. The resulting materials and their laminates show impressive strength, toughness and ballistic resistance while being more lightweight, simple to process and less environmentally damaging than many other structural materials. Synthetic structural materials with exceptional mechanical performance suffer from either large weight and adverse environmental impact (for example, steels and alloys) or complex manufacturing processes and thus high cost (for example, polymer-based and biomimetic composites) 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . Natural wood is a low-cost and abundant material and has been used for millennia as a structural material for building and furniture construction 9 . However, the mechanical performance of natural wood (its strength and toughness) is unsatisfactory for many advanced engineering structures and applications. Pre-treatment with steam, heat, ammonia or cold rolling 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 followed by densification has led to the enhanced mechanical performance of natural wood. However, the existing methods result in incomplete densification and lack dimensional stability, particularly in response to humid environments 14 , and wood treated in these ways can expand and weaken. Here we report a simple and effective strategy to transform bulk natural wood directly into a high-performance structural material with a more than tenfold increase in strength, toughness and ballistic resistance and with greater dimensional stability. Our two-step process involves the partial removal of lignin and hemicellulose from the natural wood via a boiling process in an aqueous mixture of NaOH and Na 2 SO 3 followed by hot-pressing, leading to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres. This strategy is shown to be universally effective for various species of wood. Our processed wood has a specific strength higher than that of most structural metals and alloys, making it a low-cost, high-performance, lightweight alternative.