The Effect of Chemical and High-Pressure Homogenization Treatment Conditions on the Morphology of Cellulose Nanoparticles

Cellulose nanoparticles were fabricated from microcrystalline cellulose (MCC) through combined acid hydrolysis with sulfuric and hydrochloric acids and high-pressure homogenization. The effect of acid type, acid-to-MCC ratio, reaction time, and numbers of high-pressure homogenization passes on morphology and thermal stability of the nanoparticles was studied. An aggressive acid hydrolysis was shown to lead to rod-like cellulose nanocrystals with diameter about 10 nm and lengths in the range of 50–200 nm. Increased acid-to-MCC ratio and number of homogenization treatments reduced the dimension of the nanocrystals produced. Weak acid hydrolysis treatment led to a network of cellulose nanofiber bundles having diameters in the range of 20–100 nm and lengths of a few thousands of nanometers. The high-pressure homogenization treatment helped separate the nanofiber bundles. The thermal degradation behaviors characterized by thermogravimetric analysis at nitrogen atmosphere indicated that the degradation of cellulose nanocrystals from sulfuric acid hydrolysis started at a lower temperature and had two remarkable pyrolysis processes. The thermal stability of cellulose nanofibers produced from hydrochloric acid hydrolysis improved significantly

Electrospun Nanofibers Made of Silver Nanoparticles, Cellulose Nanocrystals, and Polyacrylonitrile as Substrates for Surface-Enhanced Raman Scattering

Nanofibers with excellent activities in surface-enhanced Raman scattering (SERS) were developed through electrospinning precursor suspensions consisting of polyacrylonitrile (PAN), silver nanoparticles (AgNPs), silicon nanoparticles (SiNPs), and cellulose nanocrystals (CNCs). Rheology of the precursor suspensions, and morphology, thermal properties, chemical structures, and SERS sensitivity of the nanofibers were investigated. The electrospun nanofibers showed uniform diameters with a smooth surface. Hydrofluoric (HF) acid treatment of the PAN/CNC/Ag composite nanofibers (defined as p-PAN/CNC/Ag) led to rougher fiber surfaces with certain pores and increased mean fiber diameters. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed the existence of AgNPs that were formed during heat and HF acid treatment processes. In addition, thermal stability of the electrospun nanofibers increased due to the incorporation of CNCs and AgNPs. The p-PAN/CNC/Ag nanofibers were used as a SERS substrate to detect p-aminothiophenol (p-ATP) probe molecule. The results show that this substrate exhibited high sensitivity for the p-ATP probe detection

Experimental Study on the Safety Assessment of Reinforced Concrete Shear Wall Structure with the Correspondence between Damage Image and Index

The post-disaster emergency rescue and loss evaluation hinges on the timeliness and accuracy of safety assessment of building structures in quake-hit regions. At present, the damage identification of quake-hit buildings in China is mainly conducted based on the experience of the experts. Such an assessment method will inevitably lead to the differences in identification results because each expert has his/her own subjective understanding of the degree of structural damage. In order to solve this problem, the low cyclic loading test of 7 specimens of shear wall is conducted and the hysteretic curves of seven shear walls are drawn. The failure modes and seismic performance of members under different design parameters (axial compression ratio of shear wall, shear span ratio, form of edge member, reinforcement ratio, stirrup ratio of coupling beam, and span height ratio) are compared. By recording the damage images taken at the controlled displacement under each level of load, the corresponding damage indexes are calculated, and the correspondence between the typical component damages and the damage indexes is discovered. After that, the images are compiled into an atlas. The authors calculate the damage index of the overall structure based on the damage indexes of the components and carries out damage identification of RC shear wall structure with the said damage index

Genome-wide identification and expression pattern analysis of the SABATH gene family in Neolamarckia cadamba

Plant SABATH methyltransferases are a class of enzymes that catalyze the transfer of the methyl group from S-adenosyl-L-methionine (SAM) to the carboxyl group or the nitrogen group of the substrate to form small molecule methyl esters or N-methylated compounds, which are involved in various secondary metabolite biosynthesis and have important impacts on plant growth, development, and defense reactions. We previously reported the monoterpenoid indole alkaloids (MIAs) cadambine biosynthetic pathway in Neolamarckia cadamba, a woody tree species that provides an important traditional medicine widely used to treat diseases such as diabetes, leprosy, and cancer in Southeast Asia. However, the functions of NcSABATHs in cadambine biosynthesis remain unclear. In this study, 23 NcSABATHs were identified and found to be distributed on 12 of the total 22 chromosomes. Gene structure, conserved motifs, and phylogenetic analysis showed that NcSABATHs could be divided into three groups. According to cis-element analysis, the NcSABATH promoters contained a large number of elements involved in light, plant hormone, and environmental stress responses, as well as binding sites for the BBR-BPC, DOF, and MYB transcription factor families. Based on RNA-seq data and qRT-PCR analysis, the NcSABATH genes exhibited diverse tissue expression patterns. Furthermore, NcSABATH7/22, which clustered with LAMT in the same clade, were both up-regulated under MeJA treatment. The correlation analysis between gene expression and cadambine content showed that NcSABATH7 potentially participated in cadambine biosynthesis. Taken together, our study not only enhanced our understanding of SABATH in N. cadamba but also identified potential candidate genes involved in cadambine biosynthesis

Zeolitic imidazolate framework-cellulose nanofiber hybrid membrane as Li-Ion battery separator: Basic membrane property and battery performance

Zeolitic imidazolate framework-8 (ZIF8) concept was introduced in the fabrication of li-ion battery (LIB) separator for the first time. The ZIF8 crystals were synthesized on the surface of cellulose nanofibers (CNFs) by mixing 2-methylimidazole (Hmim) with zinc nitrate hexahydrate (Zn) in methanol. ZIF8- or Zn (mim)2-CNF composite membrane was fabricated and the effect of ZIF8 on the pore structure of CNF network was investigated. The pores of the ZIF8-CNF membrane distributed more homogeneously than that of the pure CNF membrane. The porosity increased from 42% (pure CNF membrane) to 55% (composite membrane). The successful synthesis of ZIF8 crystals on CNF surface was confirmed through elemental composition and crystalline structure analysis of the composite. Compared with polymer based separator, the ZIF8-2-CNF membrane exhibited better thermal stability, mechanical property (isotropic vs. anisotropic), thermal expansion behavior (15.53 vs. 178.90 ppm/k), and surface wettability (13.31 degrees vs. 96.18 degrees). The LIB fabricated with ZIF8-CNF membrane had a comparable cycling stability and a better discharge retention stability (88.3% vs 80.2%) in comparison with these of a tri-layer commercial polymer membrane. The environmentally friendly ZIF8-CNF nanocomposite membrane can be considered as a good alternative for manufacturing LIBs

Soy Protein Isolate As Fluid Loss Additive in Bentonite-Water-Based Drilling Fluids

Wellbore instability and formation collapse caused by lost circulation are vital issues during well excavation in the oil industry. This study reports the novel utilization of soy protein isolate (SPI) as fluid loss additive in bentonite-water based drilling fluids (BT-WDFs) and describes how its particle size and concentration influence on the filtration property of SPI/BT-WDFs. It was found that high pressure homogenization (HPH)-treated SPI had superior filtration property over that of native SPI due to the improved ability for the plugging pore throat. HPH treatment also caused a significant change in the surface characteristic of SPI, leading to a considerable surface interaction with BT in aqueous solution. The concentration of SPI had a significant impact on the dispersion state of SPI/BT mixtures in aquesous solution. At low SPI concentrations, strong aggregations were created, resulting in the formation of thick, loose, high-porosity and high-permeability filter cakes and high fluid loss. At high SPI concentrations, intercatlated/exfoliated structures were generated, resulting in the formation of thin, compact, low-porosity and low-permeability filter cakes and low fluid loss. The SPI/BT-WDFs exhibited superior filtration property than pure BT-WDFs at the same solid concentraion, demonstrating the potential utilization of SPI as an effective, renewable, and biodegradable fluid loss reducer in well excavation applications

Electrospun Nanofibers Made of Silver Nanoparticles, Cellulose Nanocrystals, and Polyacrylonitrile as Substrates for Surface-Enhanced Raman Scattering

Nanofibers with excellent activities in surface-enhanced Raman scattering (SERS) were developed through electrospinning precursor suspensions consisting of polyacrylonitrile (PAN), silver nanoparticles (AgNPs), silicon nanoparticles (SiNPs), and cellulose nanocrystals (CNCs). Rheology of the precursor suspensions, and morphology, thermal properties, chemical structures, and SERS sensitivity of the nanofibers were investigated. The electrospun nanofibers showed uniform diameters with a smooth surface. Hydrofluoric (HF) acid treatment of the PAN/CNC/Ag composite nanofibers (defined as p-PAN/CNC/Ag) led to rougher fiber surfaces with certain pores and increased mean fiber diameters. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed the existence of AgNPs that were formed during heat and HF acid treatment processes. In addition, thermal stability of the electrospun nanofibers increased due to the incorporation of CNCs and AgNPs. The p-PAN/CNC/Ag nanofibers were used as a SERS substrate to detect p-aminothiophenol (p-ATP) probe molecule. The results show that this substrate exhibited high sensitivity for the p-ATP probe detection

Using Cellulose Nanocrystals as a Sustainable Additive to Enhance Hydrophilicity, Mechanical and Thermal Properties of Poly(vinylidene fluoride)/Poly(methyl methacrylate) Blend

The aim of this study is to use cellulose nanocrystals (CNCs) as a sustainable additive for improving hydrophilicity, mechanical and thermal properties of poly­(vinylidene fluoride) (PVDF)/poly­(methyl methacrylate) (PMMA) blends. A casting-evaporation method was used to prepare the nanocomposites, and their surface wettability, mechanical, thermal and morphological properties were characterized. With the addition of only 3 wt% CNCs, tensile strength, tensile modulus, dynamic storage modulus at 45 °C, and onset thermal decomposition temperature of the ternary composite exhibited 32%, 70%, 36% and 4.0 °C increase, respectively, while the static water angle decreased by 6°. As the CNC content increased to 6 wt %, further improvement was observed in all above properties except tensile strength. The observed performance enhancement is attributed to a considerably increased crystallinity of PVDF (e.g., from 28.5% for the binary blend to 43.3% for ternary composite at the 3 wt % CNC level). Our present work demonstrates the importance of using sustainable CNCs to achieve synergetic improvement in physical and mechanical performance of PVDF/PMMA blend, suggesting a facile way to prepare nanocomposites for potential membrane-based separation applications