"Bottom-up" and "top-down" strategies toward strong cellulose-based materials.

Cellulose, as the most abundant natural polymer on Earth, has long captured researchers' attention due to its high strength and modulus. Nevertheless, transferring its exceptional mechanical properties to macroscopic 2D and 3D materials poses numerous challenges. This review provides an overview of the research progress in the development of strong cellulose-based materials using both the "bottom-up" and "top-down" approaches. In the "bottom-up" strategy, various forms of regenerated cellulose-based materials and nanocellulose-based high-strength materials assembled by different methods are discussed. Under the "top-down" approach, the focus is on the development of reinforced cellulose-based materials derived from wood, bamboo, rattan and straw. Furthermore, a brief overview of the potential applications fordifferent types of strong cellulose-based materials is given, followed by a concise discussion on future directions.

Piezoelectric deformable mirror driven by unimorph actuator arrays on multi-spatial layers.

In order to reduce the cost of the piezo actuator array deformable mirror (DM), a piezoelectric DM driven by unimorph actuator arrays on multi-spatial layers is proposed. The actuator density can be multiplied by increasing the spatial layers of the actuator arrays. A low-cost DM prototype with 19 unimorph actuators located on three spatial layers is developed. The unimorph actuator can generate a wavefront deformation up to 11 µm at an operating voltage of 50 V. The DM can reconstruct typical low-order Zernike polynomial shapes accurately. The mirror can be flattened to 0.058 µm in RMS. Furthermore, a focal spot close to Airy spot is obtained in the far field after the aberrations of the adaptive optics testing system being corrected.

Nanocellulose-based composite aerogels toward the environmental protection: Preparation, modification and applications.

Nanocellulose aerogel has the advantages of porosity, low density and high specific surface area, which can effectively realize the adsorption and treatment of wastewater waste gas. The methods of preparing nanocellulose mainly include mechanical, chemical and biological methods. Nanocellulose is formed into nanocellulose aerogel after gelation, solvent replacement and drying processes. Based on the advantages of easy modification of nanocellulose aerogels, nanocellulose aerogels can be functionalized with conductive fillers, reinforcing fillers and other materials to give nanocellulose aerogels in electrical, mechanical and other properties. Through functionalization, the properties of nanocellulose composite aerogel such as hydrophobicity and adsorption are improved, and the aerogel is endowed with the ability of electrical conductivity and electromagnetic shielding. Through functionalization, the applicability and general applicability of nanocellulose composite aerogel in the field of environmental protection are improved. In this paper, the preparation and functional modification methods of nanocellulose aerogels are reviewed, and the application prospects of nanocellulose composite aerogels in common environmental protection fields such as dye adsorption, heavy metal ion adsorption, gas adsorption, electromagnetic shielding, and oil-water separation are specifically reviewed, and new solutions are proposed.

Performance of Rod-Shaped Ce Metal-Organic Frameworks for Defluoridation.

The performance of a Ce(III)-4,4',4″-((1,3,5-triazine-2,4,6-triyl) tris (azanediyl)) tribenzoic acid-organic framework (Ce-H3TATAB-MOFs) for capturing excess fluoride in aqueous solutions and its subsequent defluoridation was investigated in depth. The optimal sorption capacity was obtained with a metal/organic ligand molar ratio of 1:1. The morphological characteristics, crystalline shape, functional groups, and pore structure of the material were analyzed via SEM, XRD, FTIR, XPS, and N2 adsorption-desorption experiments, and the thermodynamics, kinetics, and adsorption mechanism were elucidated. The influence of pH and co-existing ions for defluoridation performance were also sought. The results show that Ce-H3TATAB-MOFs is a mesoporous material with good crystallinity, and that quasi-second kinetic and Langmuir models can describe the sorption kinetics and thermodynamics well, demonstrating that the entire sorption process is a monolayer-governed chemisorption. The Langmuir maximum sorption capacity was 129.7 mg g-1 at 318 K (pH = 4). The adsorption mechanism involves ligand exchange, electrostatic interaction, and surface complexation. The best removal effect was reached at pH 4, and a removal effectiveness of 76.57% was obtained under strongly alkaline conditions (pH 10), indicating that the adsorbent has a wide range of applications. Ionic interference experiments showed that the presence of PO43- and H2PO4- in water have an inhibitory effect on defluoridation, whereas SO42-, Cl-, CO32-, and NO3- are conducive to the adsorption of fluoride due to the ionic effect.

High Value Utilization of Waste Wood toward Porous and Lightweight Carbon Monolith with EMI Shielding, Heat Insulation and Mechanical Properties.

With the increasing pollution of electromagnetic (EM) radiation, it is necessary to develop low-cost, renewable electromagnetic interference (EMI) shielding materials. Herein, wood-derived carbon (WC) materials for EMI shielding are prepared by one-step carbonization of renewable wood. With the increase in carbonization temperature, the conductivity and EMI performance of WC increase gradually. At the same carbonization temperature, the denser WC has better conductivity and higher EMI performance. In addition, due to the layered superimposed conductive channel structure, the WC in the vertical-section shows better EMI shielding performance than that in the cross-section. After excluding the influence of thickness and density, the specific EMI shielding effectiveness (SSE/t) value can be calculated to further optimize tree species. We further discuss the mechanism of the influence of the microstructure of WC on its EMI shielding properties. In addition, the lightweight WC EMI material also has good hydrophobicity and heat insulation properties, as well as good mechanical properties.

ADP receptor P2y12 prevents excessive primitive hematopoiesis in zebrafish by inhibiting Gata1.

In the past two decades, purinergic signaling has emerged as a key regulator of hematopoiesis in physiological and pathological conditions. ADP receptor P2y12 is a crucial component of this signaling, but whether it is involved in primitive hematopoiesis remains unknown. To elucidate the function of P2y12 and provide new insights for drug development, we established a zebrafish P2y12 mutant by CRISPR/Cas 9-based genetic modification system, and investigated whether P2y12 acted as an important regulator for primitive hematopoiesis. By using mass spectrometry (MS) combined with RNA sequencing, we showed that absence of P2y12 induced excessive erythropoiesis, evidenced by significantly increased expression of mature erythrocytes marker α-globin (Hbae1 and Hbae3), ß-globin (Hbbe1 and Hbbe3). Expression pattern analysis showed that P2y12 was mainly expressed in red blood cells and endothelial cells of early zebrafish embryos. Further studies revealed that primitive erythroid progenitor marker Gata1 was markedly up-regulated. Remarkably, inhibition of Gata1 by injection of Gata1 morpholino could rescue the erythroid abnormality in P2y12 mutants. The present study demonstrates the essential role of purinergic signaling in differentiation of proerythrocytes during primitive hematopoiesis, and provides potential targets for treatment of blood-related disease and drug development.

Heat shock protein DNAJA1 stabilizes PIWI proteins to support regeneration and homeostasis of planarian Schmidtea mediterranea.

PIWI proteins are key regulators of germline and somatic stem cells throughout different evolutionary lineages. However, how PIWI proteins themselves are regulated remains largely unknown. To identify candidate proteins that interact with PIWI proteins and regulate their stability, here we established a yeast two-hybrid (Y2H) assay in the planarian species Schmidtea mediterranea We show that DNAJA1, a heat shock protein 40 family member, interacts with the PIWI protein SMEDWI-2, as validated by the Y2H screen and co-immunoprecipitation assays. We found that DNAJA1 is enriched in planarian adult stem cells, the nervous system, and intestinal tissues. DNAJA1-knockdown abolished planarian regeneration and homeostasis, compromised stem cell maintenance and PIWI-interacting RNA (piRNA) biogenesis, and deregulated SMEDWI-1/2 target genes. Mechanistically, we observed that DNAJA1 is required for the stability of SMEDWI-1 and SMEDWI-2 proteins. Furthermore, we noted that human DNAJA1 binds to Piwi-like RNA-mediated gene silencing 1 (PIWIL1) and is required for PIWIL1 stability in human gastric cancer cells. In summary, our results reveal not only an evolutionarily conserved functional link between PIWI and DNAJA1 that is essential for PIWI protein stability and piRNA biogenesis, but also an important role of DNAJA1 in the control of proteins involved in stem cell regulation.

Ca(2+) Ion and Autophagy.

Controlled by a strict mechanism, intracellular calcium (Ca(2+)) is closely related to various cellular activities, including the regulation of autophagy. Researchers believed that under normal or stress state, Ca(2+) has a positive or negative regulation effect on autophagy, the mechanisms of which are different. This bidirectional role of Ca(2+), promotive or suppressing in the regulation of autophagy under different conditions remains controversial, so as the potential mechanisms. Several studies reported that Ca(2+) promotes autophagy through plenty of ways, like inositol 1,4,5-trisphosphate receptor (IP3R) and beclin1 pathway, calmodulin-dependent kinase kinase beta (CaMKKß)-AMPK-mTOR pathway, mitochondrial energy metabolism-related Ca(2+) uptake, lysosome's regulation of Ca(2+) signal, and so on. Others thought Ca(2+) may inhibit autophagy through IP3R and beclin1-Bcl-2 complex and the AMPK-mTOR pathway, either. It seems to be still a long way to thoroughly understand the truth of Ca(2+) and autophagy.

Autophagy in Development and Differentiation.

Autophagy is crucial in the differentiation and development of both mammals and invertebrates, as a rapid response to environmental and hormonal stimuli. Autophagy is also important for intracellular renewal, maintaining the health of terminally differentiated cells. Studies of Drosophila, Caenorhabditis elegans, and other species revealed abnormal autophagy lead to developmental and differential abnormality, including those in salivary glands and midgut development, protein aggregation, removal of apoptotic cell corpses, and development of dauer and synapse. Autophagy also participates in the development of mammalian embryos before implantation into the uterus, adaption to the nascent hunger environment, blood cells production, and cell differentiation in adipogenesis. Autophagy found in various stem cells, like hematopoietic stem cells, bone marrow mesenchymal stem cells and neural stem cells (NSCs), is tightly associated with their self-renewal, directed differentiation, and senescence.

Preparation of nanocellulose and its applications in wound dressing: A review.

Nanocellulose, as a nanoscale polymer material, has garnered significant attention worldwide due to its numerous advantages including excellent biocompatibility, thermal stability, non-toxicity, large specific surface area, and good hydrophilicity. Various methods can be employed for the preparation of nanocellulose. Traditional approaches such as mechanical, chemical, and biological methods possess their own distinct characteristics and limitations. However, with the growing deterioration of our living environment, several green and environmentally friendly preparation techniques have emerged. These novel approaches adopt eco-friendly technologies or employ green reagents to achieve environmental sustainability. Simultaneously, there is a current research focus on optimizing traditional nanocellulose preparation methods while addressing their inherent drawbacks. The combination of mechanical and chemical methods compensates for the limitations associated with using either method alone. Nanocellulose is widely used in wound dressings owing to its exceptional properties, which can accelerate the wound healing process and reduce patient discomfort. In this paper, the principle, advantages and disadvantages of each preparation method of nanocellulose and the research findings in recent years are introduced Moreover, this review provides an overview of the utilization of nanocellulose in wound dressing applications. Finally, the prospective trends in its development alongside corresponding preparation techniques are discussed.

A Sandwich Structural Filter Paper-AgNWs/MXene Composite for Superior Electromagnetic Interference Shielding.

A thin, lightweight and flexible electromagnetic interference (EMI) shielding paper composite is an urgent need for modern military confrontations. Herein, a sandwich-structured EMI shielding paper composite with an easy pavement consisting of a filter paper layer, middle AgNWs/MXene layer, and polyvinyl butyral (PVB) layer was constructed by vacuum-assisted filtration, spraying and air-drying. The middle AgNWs/MXene compound endowed the filter paper with excellent electrical conductivity (166 S cm-1) and the fabricated filter paper-AgNWs/MXene-PVB composite exhibits superior EMI shielding (30 dB) with a 141 µm thickness. Remarkably, the specific EMI shielding effectiveness (SSE/t) of the filter paper-AgNWs/MXene-PVB composite reached 13,000 dB cm2 g-1 within the X-band frequency range. This value represents one of the highest reported for cellulose-based EMI shielding materials. Therefore, our sandwich-structured filter paper composite with superior EMI shielding performance can be used in the medical and military fields.

Surface modifications towards superhydrophobic wood-based composites: Construction strategies, functionalization, and perspectives.

Amidst the burgeoning interest in multifunctional superhydrophobic wood-based composites (SWBCs) for their varied applications and the need for improved environmental resilience, recent efforts focus on enhancing their utility by integrating features such as mechanical and chemical stability, self-healing capabilities, flame resistance, and antimicrobial properties. Research indicates that various external conditions can influence the wettability and additional characteristics of SWBCs. This comprehensive review outlines three critical factors affecting SWBCs' performance: synthesis methods, wood taxonomy, and chemical agents. It further provides a detailed overview of SWBCs' specific attributes, including essential qualities for diverse applications and the limitations posed by different contexts. Additionally, it elaborates on performance evaluation techniques, offering a foundational framework for SWBCs' practical application. This work aims to serve as an important resource for future research and development in SWBC engineering.

Coordination-driven in-situ controlled synthesis of cellulose-based fluorescent composite with tunable color for decoration, anti-counterfeiting, and accurate color recognition.

Fluorescent composites have widespread applications in many aspects. Wood-derived cellulose is a renewable, easily processed and biodegradable, and cellulose-based fluorescent composites are highly favored for in different fields. However, the existing cellulose-based fluorescent composites still have many urgent problems to be solved, such as unstable luminescence properties and easy shedding of luminescent substances, and the development of their practical applications is still a formidable challenge. Herein, a green and mild strategy for the in-situ controllable synthesis of cellulose-based fluorescent composites membrane (CFM) was developed. Firstly, delignified wood (DW) was modified with citric acid, and then lanthanide ions were introduced on modified DW through coordinated covalent bonds. Additionally, the luminescence mechanism of CFM is proposed. CFMs show adjustable color for decorative and light conversion and can be accurately identified for data protection, which increases the high value-added of cellulose-based composites. The stable luminescent properties were maintained after sonication for 30 min or solvent immersion for three months. Therefore, this work presents a new approach for the synthesis of CFM, which provides an environment-friendly strategy for manufacturing cellulose-based fluorescent materials, which is significant for the subsequent development of environment-friendly composites for anti-counterfeiting and decorative applications.

The Effect of Polyepoxyphenylsilsesquioxane and Diethyl Bis(2-hydroxyethyl)aminomethylphosphonate on the Thermal Stability of Epoxy Resin.

Polyepoxyphenylsilsesquioxane (PEPSQ) and diethyl bis(2-hydroxyethyl) aminomethylphosphonate (DBAMP) can improve the flame retardancy of epoxy resin (EP). In this paper, the results of the limiting oxygen index (LOI) and UL94 tests exhibited that PEPSQ and DBAMP had good synergistic flame retardancy. The non-isothermal degradation kinetics of EP containing PEPSQ and DBAMP was investigated by the Kissinger and Flynn-Wall-Ozawa methods. The results of the Kissinger method displayed that the addition of two flame retardants, PEPSQ and DBAMP, can slightly enhance the activation energy of EP, indicating that the additives delayed the thermal degradation of EP. The Flynn-Wall-Ozawa method further confirmed that the activation energy of EP during the whole thermal degradation process can be significantly increased by addition of the two flame retardants PEPSQ and DBAMP. When the degree of conversion exceeded 80%, the increase was more significant. This illustrated that the flame retardants finally achieved the purpose of improving the flame retardancy of EP by stabilizing the char layer.

A Strong, Tough and Fire-Retardant Biomimetic Multifunctional Wooden Laminate.

Mildly delignified wood showed a well-preserved wood cell wall framework, and its derived compressed materials demonstrate excellent mechanical properties and advanced functional material potential. Here, we proposed a simple yet effective approach for making strong, tough, and fire-retardant wooden laminate by a three-step process of mild delignification, infiltrating potassium nonafluoro-1-butanesulfonate (PFBS), and hot-pressing to densify the material. PFBS can be infiltrated into the micro/nano-structures of the mildly delignified wood to achieve a good flame-resistant protective barrier. Flame retardant tests showed that this strong, tough, and fire-retardant wooden laminate has a superior flame-retardant performance to natural wood. Additionally, the wooden laminate also exhibits a simultaneously enhanced tensile strength (175.6 MPa vs. 89.9 MPa for natural wood) and toughness (22.9 MJ m-3vs. 10.9 MJ m-3 for natural wood). Given these attributes, the resulting wooden laminates are identified as promising candidates for high-performance structural applications, fulfilling stringent requirements for both mechanical resilience and flame-retardant efficacy.

Potential new material for optical fiber: Preparation and characterization of transparent fiber based on natural cellulosic fiber and epoxy.

In order to reduce the dependence on fossil energy products, natural fiber/polymer hybrid composites have been increasingly researched. The high price of the quartz optical fibers and glass optical fibers has greatly inspired researchers to engage in the research on polymer optical fibers. Herein, transparent fibers based on plant fibers were innovatively prepared for the first time by delignification and impregnating epoxy diluted with acetone. The epoxy improved the thermal stability of the fiber without deteriorating its mechanical properties, and also endowed the fiber with the property of transparency. The tensile strength of transparent fibers of three diameters were 34.5, 58.6 and 100.3 MPa, respectively and the corresponding Young's modulus reached 1.1, 1.7 and 2.3 GPa, respectively. In addition, the light-conducting properties of transparent fibers were displayed with a green laser and the fibers displayed good light transmission along the fiber growth direction. Transparent fibers are expected to be used in optical fibers because of their high thermal stability, good mechanical properties and light-conducting properties.

Oxidation of cellulose molecules toward delignified oxidated hot-pressed wood with improved mechanical properties.

Wooden building materials have advantages in terms of biodegradability, non-toxicity, pollution-free and recycling. Currently, applications of natural wood are extremely limited because of low density, low strength and toughness. Therefore, we reported an effective modification strategy with nano-scale cellulose nanofibrils design to prepare a synergistically enhanced cellulosic material. Via three steps: i) the secondary alcohol hydroxyl groups in C2, C3 position were cut; ii) oxidize the hydroxyl group at C2, C3 position to achieve dialdehyde cellulose; and iii) oxidized again to obtain dicarboxylic cellulose. Subsequently, thanks to the regulation of the average moisture content, the moisture content in the wood surface and subsurface increased in a short time. The wood softening layer contributes to the hotpressing treatment of the wood. The mechanical properties and dimensionality have been greatly improved. The obtained delignified oxidated hot-pressed wood with 0.55 mmol/g carboxyl group content demonstrates excellent strength of 328.8 ± 7.43 MPa and Young's modulus of 8.1 ± 0.14 GPa, which is twice than that of natural wood. Delignified oxidated hot-pressed wood also shows exceptional toughness of 8.3 ± 0.28 MJ/m3. Other than that, the shore hardness indicates 0.55 mmol/g carboxylic group, which could increase the hardness at the wood surface hardness to 72.5 ± 4.29°.

Source of Nanocellulose and Its Application in Nanocomposite Packaging Material: A Review.

Food packaging nowadays is not only essential to preserve food from being contaminated and damaged, but also to comply with science develop and technology advances. New functional packaging materials with degradable features will become a hot spot in the future. By far, plastic is the most common packaging material, but plastic waste has caused immeasurable damage to the environment. Cellulose known as a kind of material with large output, wide range sources, and biodegradable features has gotten more and more attention. Cellulose-based materials possess better degradability compared with traditional packaging materials. With such advantages above, cellulose was gradually introduced into packaging field. It is vital to make packaging materials achieve protection, storage, transportation, market, and other functions in the circulation process. In addition, it satisfied the practical value such as convenient sale and environmental protection, reduced cost and maximized sales profit. This review introduces the cellulose resource and its application in composite packaging materials, antibacterial active packaging materials, and intelligent packaging materials. Subsequently, sustainable packaging and its improvement for packaging applications were introduced. Finally, the future challenges and possible solution were provided for future development of cellulose-based composite packaging materials.

Thermal Degradation Behavior of Thiol-ene Composites Loaded with a Novel Silicone Flame Retardant.

A novel silicone flame retardant PMDA was synthesized and blended with a commercial thiol-ene (TE) to obtain a flame-retardant TE (FRTE) composite. The cone calorimeter measurement showed the incorporation of PMDA improved the flame retardancy of the TE composite at concentrations of 5 wt%. The thermal stability and degradation mechanism of FRTE in nitrogen was studied by thermogravimetric analysis. The degradation behaviour of TE containing a PMDA flame retardant was found to be changed. The kinetics of thermal degradation was evaluated by Kissinger method and Flynn-Wall-Ozawa method. The results showed that the activation energies of the FRTE degradation were higher than those of neat TE. However, the degradation mechanism of the TE matrix was not changed by the incorporation of flame-retardant PMDA. In this study, the flame-retardant mechanism of PMDA flame-retardant TE polymer was explained by using two kinetic analysis methods.

Finite Element Analysis of Strengthening Mechanism of Ultrastrong and Tough Cellulosic Materials.

Superior strong and tough structural materials are highly desirable in engineering applications. However, it remains a big challenge to combine these two mutually exclusive mechanical properties into one body. In the work, an ultrastrong and tough cellulosic material was fabricated by a two-step process of delignification and water molecule-induced hydrogen bonding under compression. The strong and tough cellulosic material showed enhanced tensile strength (352 MPa vs. 56 MPa for natural wood) and toughness (4.1 MJ m-3 vs. 0.42 MJ m-3 for natural wood). The mechanical behaviors of ultrastrong and tough bulk material in a tensile state were simulated by finite element analysis (FEA) using mechanical parameters measured in the experiment. FEA results showed that the tensile strength and toughness gradually simultaneously improved with the increase in moisture content, demonstrating that water molecules played an active role in fabricating strong and tough materials, by plasticizing and forming hydrogen bonding among cellulose nanofibrils.