Cuttlebone-Derived Organic Matrix: A Facile Periosteum Substitute for Bone Regeneration

Artificial periosteum has become a novel strategy for bone healing. Several efforts are made to develop novel periosteum substitutes with excellent osteogenesis and angiogenesis performance. The problem, however, is that many inconveniences, such as unattainable materials and complex preparation processes, limit its clinical application. In this study, cuttlebone-derived organic matrix (CDOM) film is developed as a facile obtained artificial periosteum with good bioactivity, biodegradability, and biosafety. In this study, CDOM films are prepared by etching calcium carbonate of cuttlebone with hydrochloric acid (HCl), phosphoric acid (H₃PO₄), and ethylenediaminetetraacetic acid (EDTA), respectively. CDOM films possess “S” oriented grooves on one surface, providing suitable space for survival, adhesion, and proliferation of rat mesenchymal stem cells and human umbilical vein endothelial cells. Among three CDOM films, CDOM-EDTA is the most efficient at enhancing bone regeneration in vivo, with an increase in neovascularization and new bone formation. Meanwhile, CDOM-EDTA is degradable in two months and of extremely low toxicity. There is a great deal of promise in the future for this novel periosteum substitute to be used for bone defect healing in clinical settings.     

Eco‐friendly base fluids for lubricant oil formulations

There is an increasing move towards the use of environmentally safe lubricants. However, the development of a common biodegradable base stock that could replace conventional ones is a big challenge. Synthetic lubricants, whether synthetic hydrocarbons, organic esters, or others, all have problems associated with their use. However, in general terms synthetic lubricants protect better, last longer, and outperform their conventional mineral‐based counterparts in certain applications. Future lubricant specifications in view of the demand for improved performance to meet stringent environmental regulations are the main drivers for new technological developments. As part of a study to produce polyol ester lubricant base stocks from C₅ polyols and C₆‐C₁₄ carboxylic acids in the presence of eco‐friendly catalysts, a series of products has been synthesised. A biodegradable lubricant formulation for automotive transmission fluids has been developed based on a synthesised product as a base fluid. This paper reports on the physico‐chemical characteristics and performance evaluation results of this formulation, which is a promising base stock for automotive transmission fluids.     

Biodegradable polymers: A review about biodegradation and its implications and applications

Plastic waste pollution is a global environmental problem that could be solved by biodegradable materials. In addition, its biodegradability has been important for medical applications. In this way, the biodegradability performance has been investigated for different materials under diversified environmental conditions. In this context, this review shows the main up-to-date biodegradable polymers (from renewable sources and fossil-based), their structure and properties, and their biodegradability characteristics. Also, this review shows the effect of polymer properties and environmental conditions on biodegradability, methods of biodegradability and toxicity determination, modification processes to enhance biodegradability, and main applications of biodegradable polymers for agriculture, medical, and packaging. Finally, this review presents a discussion of the implications of biodegradation on the environment, the current context, and future perspectives of plastic biodegradation.     

Performance of a novel,eco-friendly,cellulose-based superabsorbent polymer (Cellulo-SAP): Absorbency,stability, reusability,and biodegradability

Superabsorbent polymers (SAPs) have attracted tremendous attention recently, with researchers noting that their high water absorbability is valuable for various applications, especially in agricultural contexts. Two types of materials can be used to produce SAPs: Fossil-based (which are harmful to the environment) and bio-based (which are significantly more environmentally friendly, given their biodegradability and minimal toxic side effects). Although bio-based SAPs are preferable for environmental reasons, their synthesis tends to be time consuming and labour intensive, while their absorption capacity (AC) can be far below expectations. To address these problems, a novel, eco-friendly, cellulose-based superabsorbent polymer (Cellulo-SAP) was developed in this study through facile preparation via free radical synthesis using modified cellulose. Then, the absorbency, thermal/pH stability, reusability, and biodegradability of Cellulo-SAP were evaluated. This new polymer demonstrated reusability as a water reservoir, in addition to high thermal and pH stability. More importantly, Cellulo-SAP achieved an AC of 475 g/g and exhibited superior biodegradability compared to a commercial, fossil-based SAP. Accordingly, these results prove that Cellulo-SAP can be used in agriculture as an effective alternative to fossil-based SAPs.     

Applications of the concept of tribopolymerisation in fuels,lubricants, metalworking,and ‘minimalist’ lubrication

Tribopolymerisation, a novel concept of molecular design developed by Furey and Kajdas, involves the continuous formation of thin polymeric films on rubbing surfaces; the protective films formed are self‐replenishing. The antiwear compounds developed are effective with metals and ceramics and in the liquid and vapour phases. Furthermore, they are ashless and contain no harmful phosphorus or sulphur, and many are biodegradable. The potential applications are diverse and have cost, performance, energy, and environmental advantages. The present paper describes some applications of the concept of tribopolymerisation as a mechanism of boundary lubrication, including recent laboratory research and in‐plant industrial demonstrations. Applications include: (a) ashless antiwear or ‘lubricity’ additives for fuels; (b) ashless lubricants for automotive engines to reduce exhaust catalyst poisoning and environmental emissions; (c) lubrication of ceramic engines or ceramic components; (d) machining and cutting using thin films to reduce friction and ceramic tool wear; (e) vapour‐phase applications in high‐temperature gaseous systems or to counter fuel injector wear problems in natural gas engines; (f) special ‘minimalist’ pre‐treatment compositions for engine assembly and running‐in; and (g) enabling technology in the development of new engines and propulsion systems.     

COD removal from actual industrial wastewater using a three-dimensional electrochemical apparatus

Chemical oxygen demand (COD) removal was investigated using a three-dimensional electrochemical system. The effects of electrode position, pH value, initial temperature, circulation flow, aeration, and addition of hydrogen peroxide on the removal efficiency of the pollutant were studied. The fillers used in the experiment were centimetre-sized and electrolyte was obtained from an industrial factory with a concentration of COD as high as 25 000–27 500 mg L⁻¹, which was rare in other studies of the past. The degradation of organics was affected by pH and circulation flow, and a decrease in the initial pH value led to the increase in removal efficiency, while a trend of increasing at first and then decreasing was observed with the extension of circulation flow. Aeration and hydrogen peroxide served as enhanced processes for a higher removal rate. Both ultrasound and ultraviolet had effects on the electrolysis system. Oxygen uptake rate measurement and bio-treatment experiments demonstrated a significant increase in biodegradability with this three-dimensional electrochemical system. In addition, a pilot scale test in a pharmaceutical factory showed an economic benefit on energy consumption, which was as low as 10 kWh  kg⁻¹ COD.     

Total vegetable oil greases

A grease has two major constituents, namely, a lubricant, that performs the function of lubrication; and a gellant, that provides a solid continuous phase, occludes the lubricant, and gives apparent physical structure to the grease. Generally, the gellant is 5–30% and the lubricant 65–90%, additives and fillers making up the rest. In conventional greases, the gellant is a vegetable oil soap, and the lubricant is a liquid oil of petroleum origin or is a synthetic. Such greases have limited biodegradability, because the major constituent, i.e., the lubricant, is normally not biodegradable. In total vegetable oil grease, both the gellant and the lubricant are derived from vegetable oils, giving a grease of potentially high eco‐compatibility. Esters, dibasic acid esters, and alkylated esters of vegetable oil are known to be high‐quality lubricants. These can be used with soap stocks prepared from vegetable oils to give a grease of total vegetable oil origin. The vegetable‐oil based lubricants and soaps are prepared separately and combined in appropriate proportions to give a grease of the required specifications. Alternatively, esterification and saponification can be carried out simultaneously to give a grease of the desired specifications, where an alkali will be the catalyst for esterification, and reactant for saponification. In this paper, the process parameters, and kinetics of these simultaneous reactions are discussed. The results of experimental evaluation of some of these greases are also presented.     

Biodegradable,Sustainable Hydrogel Actuators with Shape and Stiffness Morphing Capabilities via Embedded 3D Printing

Despite the impressive performance of recent marine robots, many of their components are non-biodegradable or even toxic and may negatively impact sensitive ecosystems. To overcome these limitations, biologically-sourced hydrogels are a candidate material for marine robotics. Recent advances in embedded 3D printing have expanded the design freedom of hydrogel additive manufacturing. However, 3D printing small-scale hydrogel-based actuators remains challenging. In this study, Free form reversible embedding of suspended hydrogels (FRESH) printing is applied to fabricate small-scale biologically-derived, marine-sourced hydraulic actuators by printing thin-wall structures that are water-tight and pressurizable. Calcium-alginate hydrogels are used, a sustainable biomaterial sourced from brown seaweed. This process allows actuators to have complex shapes and internal cavities that are difficult to achieve with traditional fabrication techniques. Furthermore, it demonstrates that fabricated components are biodegradable, safely edible, and digestible by marine organisms. Finally, a reversible chelation-crosslinking mechanism is implemented to dynamically modify alginate actuators' structural stiffness and morphology. This study expands the possible design space for biodegradable marine robots by improving the manufacturability of complex soft devices using biologically-sourced materials.     

Ecological and health aspects of metalworking fluids' manufacture and use

The manufacture, use, and disposal of metalworking products are reviewed in the light of modern health and environmental considerations, and new stricter legislation, notably in Europe. Some new vegetable oil based formulations, which meet the new criteria, are presented.