Utilization of Cellulose to Its Full Potential: A Review on Cellulose Dissolution, Regeneration, and Applications

As the most abundant natural polymer, cellulose is a prime candidate for the preparation of both sustainable and economically viable polymeric products hitherto predominantly produced from oil-based synthetic polymers. However, the utilization of cellulose to its full potential is constrained by its recalcitrance to chemical processing. Both fundamental and applied aspects of cellulose dissolution remain active areas of research and include mechanistic studies on solvent–cellulose interactions, the development of novel solvents and/or solvent systems, the optimization of dissolution conditions, and the preparation of various cellulose-based materials. In this review, we build on existing knowledge on cellulose dissolution, including the structural characteristics of the polymer that are important for dissolution (molecular weight, crystallinity, and effect of hydrophobic interactions), and evaluate widely used non-derivatizing solvents (sodium hydroxide (NaOH)-based systems, N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl), N-methylmorpholine-N-oxide (NMMO), and ionic liquids). We also cover the subsequent regeneration of cellulose solutions from these solvents into various architectures (fibers, films, membranes, beads, aerogels, and hydrogels) and review uses of these materials in specific applications, such as biomedical, sorption, and energy uses.

Mechanism and Conformation Changes for the Whole Regeneration Process of Cellulose in Pyridinium-Based Ionic Liquids

In this work, mechanism and conformation changes of cellulose regenerated from ionic liquid by anti-solvents (water, ethanol and acetone) were investigated by molecular simulations. Cellulose model consists of seven glucose single chains were constructed. In order to depict the regeneration mechanism, both the dissolution and regeneration processes of cellulose in [Bpy][OAc] IL were simulated. The methyl hydroxyl group of cellulose will change its conformation during dissolution and regeneration. The conformation of initial cellulose crystal is mainly the tg conformation. After dissolved in ILs, the cellulose conformation changes into the gt conformation and the gg conformation. After regenerated by anti-solvent, the proportion of the gg and gt conformation changes, and the gg conformation increased and the gt conformation decreased. Based on energy analysis, it is concluded that the energy for tg is the lowest, and the tg widely exists in cellulose I. After cellulose is dissolved in ILs, the conformation changes into two higher energy conformations, the gt and gg. In the subsequent regeneration process, with the completion of regeneration, the gg conformation increases and the gt conformation decreases.

L-Cysteine Increases the Transformation Efficiency of Chinese Cabbage (Brassica rapa ssp. pekinensis)

Successful Agrobacterium-mediated transformations of Chinese cabbage have been limited owing to the plant’s recalcitrant nature, genomic background and explant necrosis upon infection, which hinders the transfer of T-DNA region into the Chinese cabbage. Consequently, in the current experiment, a stable Agrobacterium tumefaciens-mediated transformation method for Chinese cabbage cv. Kenshin established by employing important anti-oxidants in the co-cultivation and subsequent regeneration media. Four-day-old in vitro derived cotyledon explants were infected with A. tumefaciens strain GV3101 harboring the vector pCAMIBA1303. Cotyledon explants exposed to an Agrobacterium suspension (OD600 of approximately 0.6) for 10 min and then incubated for 3 days co-cultivation in Murashige and Skoog medium containing an L-cysteine + AgNO3 combination exhibited the highest β-glucuronidase (GUS) expression (94%) and explant regeneration efficiency (76%). After 3 days, the cotyledon explants were subjected to three selection cycles with gradually increasing hygromycin B concentrations (10 to 12 mg/L). The incorporation and expression of hptII in T0 transformed plants were verified by polymerase chain reaction and Southern blot analyses. These transgenic plants (T0) were fertile and morphologically normal. Using the present protocol, a successful transformation efficiency of 14% was achieved, and this protocol can be applied for genome editing and functional studies to improve Chinese cabbage traits.

Peeling with 30% Salicylic acid in the treatment of facial skin photoaging

Introduction: Chemical peeling consists of the application of one or more chemical ablative agents to the surface of the skin to induce keratolysis or keratocoagulation, with subsequent regeneration, achieving improved texture and pigmentation. It is currently a popular tool in the dermatology therapeutic arsenal, however, few studies objectively evaluate its efficacy. Objective: To evaluate the efficacy and safety of the 30% salicylic acid peeling in the treatment of facial skin rejuvenation. Method: An observational, analytical and longitudinal study was carried out in 280 patients from two hospitals (Surgical Clinic: “Hermanos Ameijeiras” and General Teaching: “Enrique Cabrera”), in the period between January 2010 and January 2020. Treatment It was applied monthly for 6 months. The final evaluation was carried out 3 months after the end of the treatment. Results: 256 women and 24 men were treated with an average age of 34.2 (± 6.3) years. After treatment, there were significant changes in the Glogau Photo Damage Scale (P = 0.015), in the Global Aesthetic Improvement Scale (P = 0.023) and in the Lemperle Wrinkle Assessment Scale (P = 0.017). The adverse events found were burning, inflammation and scaling. The degree of satisfaction reported by the patients was good (6.4%) and very good (93.5%) (P = 0.001). Conclusions: The 30% salicylic acid peel proved to be effective and safe to reduce the signs of facial skin aging, associated with a high degree of patient satisfaction.

The key stages of creation and functionality of the sites of war memorial heritage

  The relevance of studying the war memorial heritage consists in the adoption of new norms of the Constitution of the Russian Federation on protection of historical truth, which implies commemoration of the defenders of the homeland, and heroism of the people. The subject of this article is the stages of creation and functionality of the sites of war memorial heritage in time and in space. The object of this research is the war memorial heritage. The author highlights and analyzes six key stages of creation and functionality of the sites of war memorial heritage: motivational-explanatory (grounds for memorialization); procedural-memorial (procedure for perpetuation of the memory); maintenance-protective (repair, restoration, improvement; prevention of unlawful actions (inaction) with regards to the sites of war memorial heritage); mobilization (relocation of a war memorial site); destructive (demolition, damage); constructive-restorative (reconstruction of a site). The scientific novelty consists in comprehension of the key stages of creation and functionality of the sites of war memorial heritage, which is of scientific, theoretical and practical interest for the development of effective cultural strategies in the future. The conclusion is made that the period of creation and functionality of the war memorial sites is characterized by the presence of six key stages. The tangible component of a site can be subjected to destructive processes, including demolition. However, sustainability of the symbolic component allows subsequent regeneration of tangible mediums of the monuments, which is confirmed by constructive-restorative activity. The author underlines the antagonism of the tangible and symbolic components of war memorial heritage, in the context of which tangible is constantly subject to modernization, while symbolic should remain unchanged.  

Effects of hypolimnetic aeration on the quantity and quality of settling material in a eutrophied dimictic lake

Effects of hypolimnetic aeration (pumping of epilimnetic water into the hypolimnion) on the quantity of settling material in eutrophied Lake Vesijärvi, Finland were studied by comparing spatially comprehensive gross sedimentation rates as dry and organic matter prior to aeration activity and during two aerated years. Possible changes in the organic matter (as loss on ignition, LOI), carbon (C) and nitrogen (N) contents and changes in the C/N ratio of the settling material and surface sediment were quantified. Thermal stratification broke up earlier due to aeration and was followed by sedimentation peaks. The absolute amount of dry and organic matter as well as C and N settling to the lake bottom were significantly higher in the aerated years. Increased sedimentation rates were especially pronounced in the deep zones indicating enhanced sediment focusing. Increased sedimentation of C and N reflected higher primary production during the aerated years, which most likely was associated with increased temperature and turbulence and the subsequent regeneration and recycling of nutrients in the water body. Aeration seemed to slightly enhance degradation, but contrary to its ultimate aim, it failed to decrease the phosphorus content of the water column and deposits of organic material in the deep zones of the lake.

Debating “Culture Loss” in Urban Indigeneity in the Metropolitan District of Quito, Ecuador

This article examines the modern, popularized discourse of “culture loss” in the urban indigenous community of Lumbisí, Ecuador. The political ideology of mestizaje that emerged in the mid-1970s-80s became the reigning nationalism of Ecuador well into the first decade of the 21st century. This ideology catalyzed conflicting discourses of “whitening” and narratives of “culture loss” from within white-mestizo populations towards indigenous ones. Over the course of 30 years, the foothold obtained by these discourses shaped urban indigeneity, for some like the Kitu-Kara, justifying their “culture loss” followed by the subsequent regeneration of indigenous identities and cultures. In this article, I examine the case of Lumbisí, where residents maintain a strong urban, indigenous identity, rooted in their land, ancestry and traditions, yet perceive cultural shifts and innovations from within their own community as steady “cultural loss.” I argue that the Lumbisí narrative of culture loss becomes a harsh self-critique that aligns with an unattainable notion of culture stasis rather than a natural process of shift and innovation.

Learning Local Wisdom for Character Education: an Insight from Choblong Sundanese Village in Indonesia

The purpose of this study is to describe the various local wisdom and describe the diverse character education, which contain in local wisdom in the Sundanese society of Choblong, Cisarua village located in Bogor, West Java, Indonesia. Observation method is the best way to collect information and understand local culture in a society. The local wisdom of these Choblong villagers is believed to have a useful contribution to the values of character education that must always be taught and preserved for the benefit of subsequent regeneration. The local wisdom of the Choblong village can be penetrated to school curriculum for preparing their next generations and the cultural preservation. Although there are many adjustments required when immersion between local culture and school curriculum, but it is possible if the applications of carefully selected local culture are given in their local environmental settings.