Recent insights in synthesis and energy storage applications of porous carbon derived from biomass waste: A review

In the last few decades, global warming, environmental pollution, and an energy shortage of fossil fuel may cause a severe economic crisis and health threats. Storage, conversion, and application of regenerable and dispersive energy would be a promising solution to release this crisis. The development of porous carbon materials from regenerated biomass are competent methods to store energy with high performance and limited environmental damages. In this regard, bio-carbon with abundant surface functional groups and an easily tunable three-dimensional porous structure may be a potential candidate as a sustainable and green carbon material. Up to now, although some literature has screened the biomass source, reaction temperature, and activator dosage during thermochemical synthesis, a comprehensive evaluation and a detailed discussion of the relationship between raw materials, preparation methods, and the structural and chemical properties of carbon materials are still lacking. Hence, in this review, we first assess the recent advancements in carbonization and activation process of biomass with different compositions and the activity performance in various energy storage applications including supercapacitors, lithium-ion batteries, and hydrogen storage, highlighting the mechanisms and open questions in current energy society. After that, the connections between preparation methods and porous carbon properties including specific surface area, pore volume, and surface chemistry are reviewed in detail. Importantly, we discuss the relationship between the pore structure of prepared porous carbon with surface functional groups, and the energy storage performance in various energy storage fields for different biomass sources and thermal conversion methods. Finally, the conclusion and prospective are concluded to give an outlook for the development of biomass carbon materials, and energy storage applications technologies. This review demonstrates significant potentials for energy applications of biomass materials, and it is expected to inspire new discoveries to promote practical applications of biomass materials in more energy storage and conversion fields.     

The influence of carbon atom distribution in precursors with 1:1 carbon to silicon atoms ratio on structure and thermal evolution of obtained silicon oxycarbide based materials

In this work, a number of precursors with 1:1 silicon to carbon atoms ratio and various carbon atom distributions were synthesized and pyrolyzed in order to obtain silicon oxycarbide based materials. The different carbon atom distributions were obtained using both simple monomers with only one silicon atom, as well as large monomers containing either four or sixteen silicon atoms with predefined carbon atom positions. The silicon oxycarbide based materials were investigated using IR, XRD, ²⁹Si MAS NMR and elemental analysis after annealing at various temperatures, as well as TG. The research shows that carbon atom distribution has great impact on the structure of final material and can be used to tailor the material for its projected uses.     

Systematic Review: Adipose-Derived Mesenchymal Stem Cells,Platelet-Rich Plasma and Biomaterials as New Regenerative Strategies in Chronic Skin Wounds and Soft Tissue Defects

The number of clinical trials evaluating adipose-derived mesenchymal stem cells (AD-MSCs), platelet-rich plasma (PRP), and biomaterials efficacy in regenerative plastic surgery has exponentially increased during the last ten years. AD-MSCs are easily accessible from various fat depots and show intrinsic plasticity in giving rise to cell types involved in wound healing and angiogenesis. AD-MSCs have been used in the treatment of soft tissue defects and chronic wounds, employed in conjunction with a fat grafting technique or with dermal substitute scaffolds and platelet-rich plasma. In this systematic review, an overview of the current knowledge on this topic has been provided, based on existing studies and the authors’ experience. A multistep search of the PubMed, MEDLINE, Embase, PreMEDLINE, Ebase, CINAHL, PsycINFO, Clinicaltrials.gov, Scopus database, and Cochrane databases has been performed to identify papers on AD-MSCs, PRP, and biomaterials used in soft tissue defects and chronic wounds. Of the 2136 articles initially identified, 422 articles focusing on regenerative strategies in wound healing were selected and, consequently, only 278 articles apparently related to AD-MSC, PRP, and biomaterials were initially assessed for eligibility. Of these, 85 articles were excluded as pre-clinical, experimental, and in vitro studies. For the above-mentioned reasons, 193 articles were selected; of this amount, 121 letters, expert opinions, commentary, and editorials were removed. The remaining 72 articles, strictly regarding the use of AD-MSCs, PRP, and biomaterials in chronic skin wounds and soft tissue defects, were analyzed. The studies included had to match predetermined criteria according to the patients, intervention, comparator, outcomes, and study design (PICOS) approach. The information analyzed highlights the safety and efficacy of AD-MSCs, PRP, and biomaterials on soft tissue defects and chronic wounds, without major side effects.     

Effect of aluminium acetyl acetonate on the hydrogen and nitrogen permeation of carbon molecular sieves membranes

With a growing interest in hydrogen as energy carrier, the efficient purification of hydrogen from gaseous mixtures is very important. This paper addresses the separation of hydrogen using Carbon Molecular Sieves Membranes (CMSM), which show an attractive combination of high permeability, selectivity and stability. Supported CMSM containing various amounts of aluminium have been prepared from novolac and aluminium acetyl acetonate (Al(acac)₃) as carbon and alumina precursors. The thickness of the CMSM layers depend on the content of Al(acac)₃ in the dipping solution, which also has influence in the pore size and pore size distribution of the membranes. The permeation properties of the membranes against the Al content in the membrane follows a volcano shape, where the membrane containing 4 wt (%) of Al(acac)₃ has the best properties and was stable during 720 h for hydrogen at 150 °C and 6 bar pressure difference. All the CMSM have permeation properties well above the Robeson Upper limit.     

Unipolar plasma electrolytic oxidation: Waveform optimisation for corrosion resistance of commercially pure titanium

This study deals with the anodisation of titanium grade 2 in 0.5-M sulphuric acid using a pulsed signal in a unipolar regime. The electrical parameters investigated are voltage, frequency and duty cycle. The use of duty cycles with a high percentage of anodic polarisation (90%), combined with high frequencies (1000 Hz) and the higher voltage tested (220 V), favoured the establishment of a plasma regime involving strong dielectric discharges, allowing the growth of thicker oxides but with rough architecture. The corrosion resistance of the formed film has been characterised by potentiodynamic tests in 0.5-M NaBr for localised corrosion resistance and by immersion tests in 10% v/v sulphuric acid solution for a uniform corrosion assessment. Current–time curves, visual observations and electron microscope analysis (scanning electron microscopy, energy-dispersive X-ray spectroscopy) were the tools selected to provide a correlation between technological parameters and oxide growth mechanism. For localised and uniform corrosion, anodisation at 220 V with a high level of anodic polarisation (90%) and frequency (1000 Hz) was verified to be particularly advantageous.     

Carbon corrosion mechanism on nitrogen-doped carbon support — A density functional theory study

In this work, density functional theory (DFT) calculations were used to investigate the mechanism of carbon corrosion on nitrogen-doped carbon support. Free energy diagrams were generated based on three proposed reaction pathways to evaluate corrosion mechanisms. The most energetically preferred mechanism on nitrogen-doped carbon was determined. The results show that the step of water dissociation to form ^#OH was the rate-determining step for gra-G-1N (graphene doped with graphitic N) and pyrr-G-1N (graphene doped with pyrrolic N). As for graphene doped with pyridinic N, the step of C^#OC^#O formation was critical. It was found that the control of nitrogen concentration was necessary for precisely designing optimized carbon materials. Abundance of nitrogen moieties aggravated the carbon corrosion. When the high potential was applied, specific types of graphitic N and pyridinic N were found to be favorable carbon modifications to improve carbon corrosion resistance. Moreover, the solvent effect was also investigated. The results provide theoretical insights and design guidelines to improve corrosion resistance in carbon support through material modification by inhibiting the adsorption of surface oxides (OH, O, and OOH).     

Effects of non-thermal plasma treating wheat kernel on the physicochemical properties of wheat flour and the quality of fresh wet noodles

The effects of non-thermal plasma (NTP) on the physicochemical properties of wheat flour and the quality of fresh wet noodles ( FWN) were investigated. The results showed that NTP effectively decreased the total plate count (TPC), yeast and mould count (YMC) and Bacillus spp. in wheat flour. Wet gluten contents and the stability time reached the maximum when treated for 20 s. The viscosity of starch increased significantly after treatment due to the increased of damaged starch. The contents of secondary structure were altered to some extent, which was because that the ordered network structure of gluten protein broken. Furthermore, compared with the control, texture properties of FWN were enhanced significantly at 20 s, and the darkening rate of FWN was greatly inhibited due to the low polyphenol oxidase (PPO) activity. Consequently, the most suitable treatment was 500 W for 20 s, providing a basis for the application of NTP in flour products.     

Microstructure and mechanical properties of α/β-Si3N4 composite ceramics with novel ternary additives prepared via spark plasma sintering

In this study, α/β-Si₃N₄ composite ceramics with high hardness and toughness were fabricated by adopting two different novel ternary additives, ZrN–AlN–Al₂O₃/Y₂O₃, and spark plasma sintering at 1550 °C under 40 MPa. The phase composition, microstructure, grain distribution, crack propagation process and mechanical properties of sintered bulk were investigated. Results demonstrated that the sintered α/β-Si₃N₄ composite ceramics with ZrN–AlN–Al₂O₃ contained the most α phase, which resulted in a maximum Vickers hardness of 18.41 ± 0.31 GPa. In the α/β-Si₃N₄ composite ceramics with ZrN–AlN–Y₂O₃ additives, Zr₃AlN MAX-phase and ZrO phase were found and their formation mechanisms were explained. The fracture appearance presented coarser elongated β-Si₃N₄ grains and denser microstructure when 20 wt% TiC particles were mixed into Si₃N₄ matrix, meanwhile, exhibited maximum mean grain diameter of 0.98 ± 0.24 μm. As a result, the compact α/β-Si₃N₄ composite ceramics containing ZrN–AlN–Y₂O₃ additives and TiC particles displayed the optimal bending strength and fracture toughness of 822.63 ± 28.75 MPa and 8.53 ± 0.21 MPa?m^1/2, respectively. Moreover, the synergistic toughening of rod-like β-Si₃N₄ grains and TiC reinforced particles revealed the beneficial effect on the enhanced fracture toughness of Si₃N₄ ceramic matrix.     

异种铁素体耐热钢接头界面组织及其影响

综述了铁素体与铁素体异种金属焊缝（dissimilar metal welds，DMWs）接头界面组织及其影响。结果表明，在焊后热处理或运行温度下的铁素体钢DMWs接头的不均匀界面组织中，通常会形成脱碳层和增碳层。在铁素体钢DMWs焊接接头界面组织影响因素中，焊缝金属的化学成分有重要影响；焊后热处理规范（温度和时间）、工作温度下运行时间的影响较为突出；焊接工艺参数的影响亦不可忽略。异种钢接头界面处近缝区裂纹的产生，以及接头的蠕变强度随Larson Miller 参数增大而下降等不利影响，均为异种钢界面碳迁移行为所导致。焊缝成分控制法是接头界面组织控制或改善的必要条件，而脱碳层部位转移法能有效防止裂纹发生，亦是接头安全运行的重要工艺措施之一。