A Defective Nanotube Molecule of C552H496N24 with Pyridinic and Pyrrolic Nitrogen Atoms

A 3-nm molecule comprising a cylindrical core and cross-shaped rims was designed and synthesized by developing a modular synthetic route. By using a cyclic precursor from previous studies as a starting material, multiple carbazole units were installed at the rims of the defective cylinder. The defective cylinder was synthetically doped with two types of nitrogen atoms, that is, pyridinic and pyrrolic nitrogen atoms, which resulted in solvatochromic shifts in fluorescence by charge-transfer interactions. The structure of the large, C₅₅₂H₄₉₆N₂₄ molecule was fully disclosed by crystallographic analyses, and the unique helical arrangement of nitrogen-doped cylinders in the crystal was revealed.     

Interlayer Space Engineering of MXenes for Electrochemical Energy Storage Applications

The increasing demand for high-performance rechargeable energy storage systems has stimulated the exploration of advanced electrode materials. MXenes are a class of two-dimensional (2D) inorganic transition metal carbides/nitrides, which are promising candidates in electrodes. The layered structure facilitates ion insertion/extraction, which offers promising electrochemical characteristics for electrochemical energy storage. However, the low capacity accompanied by sluggish electrochemical kinetics of electrodes as well as interlayer restacking and collapse significantly impede their practical applications. Recently, interlayer space engineering of MXenes by different chemical strategies have been widely investigated in designing functional materials for various applications. In this review, an overview of the most recent progress of 2D MXenes engineering by intercalation, surface modification as well as heterostructures design is provided. Moreover, some critical challenges in future research on MXene-based electrodes have been also proposed.     

Defect Engineering on Boron Nitride for O2 Activation and Subsequent Oxidative Desulfurization

The rational design of highly active hexagonal boron nitride (h-BN) catalysts at the atomic level is urgent for aerobic reactions. Herein, a doping impurity atom strategy is adopted to increase its catalytic activities. A series of doping systems involving O, C impurities and B, N antisites are constructed and their catalytic activities for molecular O₂ have been studied by density functional theory (DFT) calculations. It is demonstrated that O₂ is highly activated on O_N and B_N defects, and moderately activated on C_B and C_N defects, however, it is not stable on N_B and O_B defects. The subsequent application in oxidative desulfurization (ODS) reactions proves the O_N and C-doped (C_B, C_N) systems to be good choice for sulfocompounds oxidization, especially for dibenzothiophene (DBT). While the B_N antisite is not suitable for such aerobic reaction due to the extremely stable B−O^*−B species formed during the oxidation process.     

In Vivo Biological Behavior of Polymer Scaffolds of Natural Origin in the Bone Repair Process

Autologous bone grafts, used mainly in extensive bone loss, are considered the gold standard treatment in regenerative medicine, but still have limitations mainly in relation to the amount of bone available, donor area, morbidity and creation of additional surgical area. This fact encourages tissue engineering in relation to the need to develop new biomaterials, from sources other than the individual himself. Therefore, the present study aimed to investigate the effects of an elastin and collagen matrix on the bone repair process in critical size defects in rat calvaria. The animals (Wistar rats, n = 30) were submitted to a surgical procedure to create the bone defect and were divided into three groups: Control Group (CG, n = 10), defects filled with blood clot; E24/37 Group (E24/37, n = 10), defects filled with bovine elastin matrix hydrolyzed for 24 h at 37 °C and C24/25 Group (C24/25, n = 10), defects filled with porcine collagen matrix hydrolyzed for 24 h at 25 °C. Macroscopic and radiographic analyses demonstrated the absence of inflammatory signs and infection. Microtomographical 2D and 3D images showed centripetal bone growth and restricted margins of the bone defect. Histologically, the images confirmed the pattern of bone deposition at the margins of the remaining bone and without complete closure by bone tissue. In the morphometric analysis, the groups E24/37 and C24/25 (13.68 ± 1.44; 53.20 ± 4.47, respectively) showed statistically significant differences in relation to the CG (5.86 ± 2.87). It was concluded that the matrices used as scaffolds are biocompatible and increase the formation of new bone in a critical size defect, with greater formation in the polymer derived from the intestinal serous layer of porcine origin (C24/25).     

State of the art and research development prospects of energy and resource-efficient environmentally safe chemical process systems engineering

In this focus overview, the main types and directions of engineering, methods and techniques of intensification of chemical process systems (CPS) and process optimization of energy- and resource-efficient processes for the representative production of titanium compounds, mining waste processing systems, electrochemical coating technologies, combined technologies for the treatment of industrial effluents and energy-and resource-efficient technologies for cleaning soils from petroleum and chemical pollution products are reviewed. The following issues have been discussed: methods of complex assessment of production energy efficiency and software and information support for automated synthesis of optimal energy-efficient regenerative heat exchange systems using pinch analysis; methods and algorithms for fractal-statistical characteristics analysis of nonstationary gas flows in complex gas pipelines; methods of ecological and economic optimization of production, infrastructure supply chains; methods for assessing and preventing the dangerous environmental impact assessment of chemical pollution; organization and logistics management of business processes engineering for improving the energy efficiency of plants; engineering of problem oriented computer systems, heuristic-computational models and algorithms for intelligent integrated logistics support of the equipment life cycle; engineering developments in the field of digital transformation of energy-efficient CPS and technological production systems; application of methods for optimizing reliability factors optimization, digitalized risk and safety management in the engineering of energy- and resource efficient CPS.     

A perspective of the engineering applications of carbon-based selenium-containing materials

Carbon-based selenium-containing materials are novel materials just being invented recently. Owing to the low cost and bio-compatible features of carbon and selenium, these materials are practical. The unique chemical- and bio-activities of selenium endow them wide range of applications in catalysis, environment-protection, fertilizer and biocide development etc. Recent progresses in this field are summarized and prospected from the engineering application viewpoint in this mini-review.     

高中化学必修课程“变化观念与平衡思想”学科核心素养的系统构成研究

“变化观念与平衡思想”学科核心素养的系统构成对开展“素养导向”的教学与评价具有重要意义。通过课标分析,基于学科能力模型明确了高中必修学段“变化观念与平衡思想”核心素养的核心知识与活动经验、认识方式、研究对象及问题情境、学科能力活动及其表现等4个维度的具体内涵,系统建构了高中化学必修课程“变化观念与平衡思想”学科核心素养模型。     

Evaluation of PEGylated fibrin as a three-dimensional biodegradable scaffold for ovarian tissue engineering

The most challenging task of creating a bioengineered ovary to restore fertility in cancer patients is choosing an appropriate biomaterial to encapsulate isolated preantral follicles and ovarian cells. In this study, as a biocompatible and biodegradable biomaterial containing fibrin-like bioactivity and manageable physical properties, PEGylated fibrin aims to encapsulate isolated ovarian stromal cells as a first step of creating an engineered ovarian tissue. For this purpose, human ovarian stromal cells were isolated from frozen-thawed ovarian tissue and cultured in the PEGylated fibrin hydrogels (PEG:Fib), which were fabricated by combining two different molar ratios of PEG:Fib (10:1 and 5:1) and two thrombin concentrations. The samples were analyzed at days 0 and 5 of in vitro for cell density, proliferation (Ki67), and apoptosis (caspase-3). Moreover, LIVE/DEAD and PrestoBlue assays assessed cell viability and proliferation on days 1, 3, and 5. The effect of PEGylation on the biodegradation behavior of fibrin was evaluated by measuring the remaining mass ratio of non-modified fibrin, PEG:Fib 10:1, and PEG:Fib 5:1 hydrogels after 1, 2, 3, 5, 8, 11, and 15 days. The results showed that PEGylated fibrin hydrogels enhanced scaffold stability and supported cell viability and proliferation. In addition, PEG:Fib 5:1 T50 indicated a significantly higher cell density dynamic and non-significantly lower expression of caspase-3 on day 5. Besides, uniformity of cell distribution inside the hydrogel and a tendency to a high rate of Ki67-positive cells was observed in PEG:Fib 10:1 T50 hydrogels. In conclusion, this study reveals the positive effects of PEGylated fibrin hydrogels on isolated human ovarian stromal cells. Based on such promising findings, we believe that this matrix should be tested to encapsulate isolated human ovarian follicles.     

K-Carrageenan Stimulates Pre-Osteoblast Proliferation and Osteogenic Differentiation: A Potential Factor for the Promotion of Bone Regeneration?

Current cell-based bone tissue regeneration strategies cannot cover large bone defects. K-carrageenan is a highly hydrophilic and biocompatible seaweed-derived sulfated polysaccharide, that has been proposed as a promising candidate for tissue engineering applications. Whether κ-carrageenan can be used to enhance bone regeneration is still unclear. In this study, we aimed to investigate whether κ-carrageenan has osteogenic potential by testing its effect on pre-osteoblast proliferation and osteogenic differentiation in vitro. Treatment with κ-carrageenan (0.5 and 2 mg/mL) increased both MC3T3-E1 pre-osteoblast adhesion and spreading at 1 h. K-carrageenan (0.125–2 mg/mL) dose-dependently increased pre-osteoblast proliferation and metabolic activity, with a maximum effect at 2 mg/mL at day three. K-carrageenan (0.5 and 2 mg/mL) increased osteogenic differentiation, as shown by enhanced alkaline phosphatase activity (1.8-fold increase at 2 mg/mL) at day four, and matrix mineralization (6.2-fold increase at 2 mg/mL) at day 21. K-carrageenan enhanced osteogenic gene expression (Opn, Dmp1, and Mepe) at day 14 and 21. In conclusion, κ-carrageenan promoted MC3T3-E1 pre-osteoblast adhesion and spreading, metabolic activity, proliferation, and osteogenic differentiation, suggesting that κ-carrageenan is a potential osteogenic inductive factor for clinical application to enhance bone regeneration.