Volume 16 Issue 4

Cellulose solution and nanocellulose were prepared from corn straw and wheat straw and then used to fabricate an all-cellulose nanocomposites film (ANF). The crystal structure (CS) of ANFs was analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FTIR). Cellulose-I and cellulose-II were found to coexist within regenerated cellulose films (RCF) and ANFs. With the change of nanocellulose content, the proportions of cellulose-I and cellulose-II changed. Cellulose transformation was found to depend on the raw material and the preparation method. When cellulose solution was prepared from corn straw that had been extracted, the cellulose type tended to be transformed from cellulose-I to cellulose-II; the proportion of cellulose-I showed a tendency to increase when nanocellulose content exceeded 1.5%. When the dissolved cellulose had been treated by an acid-alkali method, the results did not follow a clear pattern. However, when cellulose solution was prepared from wheat straw, under extraction method, the cellulose type tended to transform from cellulose-I to cellulose-II; under acid-alkali method, cellulose-I did not follow a clear pattern with nanocellulose content. Though the small amount of nanocellulose can’t dominate the content of cellulose-I, it could cause an increase in disorder of the cellulose matrix.

Fungal spoilage and mycotoxin contamination are two of the greatest hazards of silage. The present work was carried out to evaluate the impact of Lactobacillus bulgaricus and cellulolytic enzymes on the maize silage (MS) quality. Fungal analysis of different MS samples showed different mycotoxigenic fungi. The highest frequency (62.8%) was associated with Fusarium spp. Four species with different relative densities were found: F. graminearum (71.1%), F. culmorum (15.2%), F. proliferatum (11.2%), and F. oxysporum (2.50 %). High-performance liquid chromatography analysis showed the presence of trichothecene, nivalenol, zearalenone, and fumonisins mycotoxins in MS inoculated by F. graminearum. The inhibition % of trichothecene, nivalenol, and zearalenone synthesis was 50.2%, 47.5%, and 23.5%, respectively, in MS inoculated by Lactobacillus bulgaricus after a 30 d incubation period. Trichoderma harzianum succeeded in producing cellulolytic enzymes, i.e., carboxymethyl cellulase, manganase peroxidase, and laccase, with a maximum production of 350 µg/mL, 5.47 µg/mL, and 16.0 µg/mL, respectively, after 21 d using MS as the substrate. Treatment by the extracted cellulolytic enzyme with L. bulgaricus enhanced unfavorable conditions for MS fungal contamination, i.e., the production of lactic acid, a lowered pH, and increased L. bulgaricus colony-forming units, compared to the addition of enzyme extract or L. bulgaricus alone.

This paper presents the state of the art of wood surface densification method by pressing with ultrasound. The properties of ultrasound and its effects on the structure and properties of wood, as well as ultrasound-induced chemical changes in wood material, are described. The following research results were analyzed: the effects of acoustic cavitation in wood material, plasticization of wood lignin by processing with ultrasound, the influence of ultrasound on the wood anatomical structure, the combined effect of ultrasound and wood pressing, and the sterilization of wood using ultrasonic action. Ultrasound causes conversion of lignin from glassy into a quasi-rubbery state, which facilitates compaction of the workpiece surface. Additionally, under ultrasound, growth and collapse of gas bubbles (cavitation phenomena) occur within a liquid medium of wooden substance accompanied by high local temperatures and production of chemically active radicals. This contributes to the destruction of the former and the formation of new bonds in the wood substance, which is important for increasing the stability of the workpiece size after densification. The conclusions made about the ultrasound can be effectively used for the wood plasticization and about prospects of joint use of wood pressing and ultrasound for wood surface densification.

Thousands of oil spill incidents regrettably have occurred on a daily basis around the globe. Oil spills are a form of pollution that poses major catastrophic threats to marine ecosystems. Oil spill incidents commonly occur in the middle of the ocean, and the process to remove the oil becomes a great challenge. Absorbents, due to their good oil-absorbing characteristics, are becoming more popular nowadays as one of the effective oil spill clean-up methods. Among the many types of oil absorbents, plant fibers were also being studied to remove the oil spills from the sea surface. This paper reviews factors leading to oil spills, the detrimental effect of the oil spill on the environment, the oil spill removal methods, and the application of plant fibers as oil absorbent material. The paper also will highlight the latest development on the utilization of kenaf core fibers as oil-absorbent material and the use of oil absorbed kenaf core fibers as fuel briquette by taking advantage the high calorific value of the oil spill.

Gamma-valerolactone (GVL) is a highly reactive keto-lactone and a promising platform biomolecule, used as an additive for food and fuels, green solvent, and fuels precursor, among others. Its production from biomass usually involves hydrogenation and subsequent cyclization of levulinic acid or its esters. The process of conventional hydrogenation requires high pressures and temperatures, an external hydrogen source, and scarce noble/precious materials as catalysts. However, it could be produced under mild conditions, using bifunctional metal-acid catalysts with high metal dispersion and meso or microporosity, high surface area, temperatures lower than 200 °C, pressures ≤ 1MPa, and secondary alcohols (such as isopropanol) as hydrogen donors. The catalytic transfer hydrogenation followed by cyclization (CTHC) of levulinic acid (LA) and its esters (LE) to produce GVL using secondary alcohols as H donor is a great alternative. Variables involved in CTHC such as raw material, time, temperature, and type of catalyst, mainly transition metals and their combinations, are reviewed in this work.

In the furniture industry, some traditional Chinese mortise and tenon joints are not suitable for the current requirements for carbon reduction and environmental protection of furniture products. This article aims to explore new ideas and new methods of modern mortise and tenon structure design. The reduction principle in the green design concept is introduced for the furniture modern mortise and tenon structure design. Based on modern furniture, a systematic analysis of the modern mortise and tenon structure design is carried out. Additionally, this review discusses the method of applying the reduction principle in modern tenon and tenon structure design in the context of green design. The development status and trend of modern mortise and tenon structure design is summarized and an innovative design practice of modern mortise and tenon structure is carried out. The combination of green design and furniture design has important practical significance in a modern context.

Pectin, as a sustainable biopolymer with its two complementary functionalities (carboxyl and hydroxyl moieties) imparted in the α-1,4-galacturonic acid repeating unit, has gained increasing attention in the last few years. The interest in this ubiquitously occurring plant originating polysaccharide (PS) has shifted slowly from applications as a food additive to a broader range of potential applications in medicine, cosmetics, and other industries. Due to the increasing interest in alternatives for petrochemical materials, PSs as biomaterials have gained increasing attention in industrial processes in general. In the last decade, an increasing number of chemical transformations related to pectin have been published, and this is a prerequisite for the design of the structure and hence properties of novel biopolymer-based materials. This work aims to review the chemical modifications of pectin by covalent linkage of the last decade and analyze the materials obtained with these chemical methods critically.

State-of-the-art steel-timber composite structures (STC), using cold-formed steel (CFS) and cross-laminated timber (CLT), are considered in this review. Literature on this type of construction solution is reviewed to provide an overview of the characteristics and advantages of STC. Previous experimental and numerical studies with STC structures, mainly composite solutions with CFS beams and CLT panels, are discussed to assess the behavior of this structural typology. A comprehensive description of the connection systems performance in different STC structures is also provided. Furthermore, the design and analytical methods currently available are presented. Likewise, details on aspects related to dynamic properties and fire resistance are discussed.

In recent years, microbial degradation technology has shown broad potential in the fields of agriculture, industry, and environmental protection. However, in practical applications the technology still encounters many problems, such as low bacterial survivability during dynamic operations, the need to remove bacterial liquid, and low tolerance in high-toxic environments, among other issues. Immobilization technology has been developed to overcome such limitations. Microbial strains have been prepared for a specific range of activities utilizing self-fixation or exosome fixation. Immobilization can significantly improve strain density, toxicity tolerance, and bacterial liquid removal. This review first presents the advantages and disadvantages of the current microbial immobilization technologies and then summarizes the properties and characteristics of various carrier materials. The review focuses on how biomass-derived materials have been used as the carriers in new microbial immobilization technologies. The excellent biocompatibility, unique physical structure, and diversified modification methods of biomass-derived materials have shown excellent prospects in the field of microbial immobilization. Finally, microbial immobilization technologies’ potential applications in agriculture, industry, and environmental applications are considered.

Chitosan (CS) is a natural polysaccharide isolated from insects, molluscs, and fungi. The specific properties of chitosan can be enhanced using physicochemical processes. The composites prepared using CS and graphene oxide (GO) contain active functional groups such as epoxide, carboxyl, and hydroxyl, which possess excellent biocompatibility, high adsorption capacity, and biodegradability. Their low cost and ease of scale-up make them employable for multiple applications in water-treatment plants, electronics, solar cells, and pharmaceuticals. This review provides an overview of sources, types, and properties of chitin, chitosan, and graphene oxide. The use of these composites for the preparation of anti-microbial drugs has been discussed here. The article also explores the applicability of such composites for removal of heavy metals (lead, copper, chromium, cobalt, mercury, etc.), dyes (methylene blue and other reactive dyes), and organic and inorganic contaminants (ofloxacin, naphthanol, phenol, and oil, etc.). The article highlights various knowledge gaps in the field and the scope of future work.