•Chitin/chitosan have tunable biological properties in tissue engineering.•Chitin/chitosan nanofibers enhance seed cell’s osteogenic activities.•Chitin/chitosan nanofibers promote drug delivery and ...angiogenesis during osteogenesis.•Chitosan derivative nanofibers improve biological properties for osteogenesis.
Promoting bone regeneration and repairing defects are urgent and critical challenges in orthopedic clinical practice. Research on bone substitute biomaterials is essential for improving the treatment strategies for bone regeneration. Chitin and its derivative, chitosan, are among the most abundant natural biomaterials and widely found in the shells of crustaceans. Chitin and chitosan are non-toxic, antibacterial, biocompatible, degradable, and have attracted significant attention in bone substitute biomaterials. Chitin/chitosan nanofibers and nanostructured scaffolds have large surface area to volume ratios and high porosities. These scaffolds can be fabricated by electrospinning, thermally induced phase separation and self-assembly, and are widely used in biomedical applications such as biological scaffolds, drug delivery, bacterial inhibition, and wound dressing. Recently, some chitin/chitosan-based nanofibrous scaffolds have been found structurally similar to bone’s extracellular matrix and can assist in bone regeneration. This review outlines the biomedical applications and biological properties of chitin/chitosan-based nanofibrous scaffolds in bone tissue engineering.
Principal component analysis (PCA) minimizes the mean square error (MSE) and is sensitive to outliers. In this paper, we present a new rotational-invariant PCA based on maximum correntropy criterion ...(MCC). A half-quadratic optimization algorithm is adopted to compute the correntropy objective. At each iteration, the complex optimization problem is reduced to a quadratic problem that can be efficiently solved by a standard optimization method. The proposed method exhibits the following benefits: 1) it is robust to outliers through the mechanism of MCC which can be more theoretically solid than a heuristic rule based on MSE; 2) it requires no assumption about the zero-mean of data for processing and can estimate data mean during optimization; and 3) its optimal solution consists of principal eigenvectors of a robust covariance matrix corresponding to the largest eigenvalues. In addition, kernel techniques are further introduced in the proposed method to deal with nonlinearly distributed data. Numerical results demonstrate that the proposed method can outperform robust rotational-invariant PCAs based on L 1 norm when outliers occur.
Flexible and self-supported carbon-coated FeS on carbon cloth films (denoted as FeS@C/carbon cloth) is prepared by a facial hydrothermal method combined with a carbonization treatment. The ...FeS@C/carbon cloth could be directly used as electrodes for Li-ion batteries (LIBs) and sodium-ion batteries (NIBs). The synthetic effects of the structure, highly electron-conductive of carbon cloth, porous structure for electrolyte access, and uniform carbon shell on FeS surface to accommodate the volume change lead to improved cyclability and rate capability. For lithium storage, the FeS@C/carbon cloth electrode delivers a high discharge capacity of 420 mAh g–1 even after 100 cycles at a current density of 0.15 C and 370 mAh g–1at a high current density of 7.5 C (1 C = 609 mA g–1. When used for sodium storage, it keeps a reversible capacity of 365 mAh g–1after 100 cycles at 0.15 C. Similar process can be utilized for the formation of various cathode and anode composites on carbon cloth for flexible energy storage devices.
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs (typically consisting of 18–25 nucleotides) that negatively control expression of target genes at the post-transcriptional level. Owing to the ...biological significance of miRNAs, miRTarBase was developed to provide comprehensive information on experimentally validated miRNA–target interactions (MTIs). To date, the database has accumulated >13,404 validated MTIs from 11,021 articles from manual curations. In this update, a text-mining system was incorporated to enhance the recognition of MTI-related articles by adopting a scoring system. In addition, a variety of biological databases were integrated to provide information on the regulatory network of miRNAs and its expression in blood. Not only targets of miRNAs but also regulators of miRNAs are provided to users for investigating the up- and downstream regulations of miRNAs. Moreover, the number of MTIs with high-throughput experimental evidence increased remarkably (validated by CLIP-seq technology). In conclusion, these improvements promote the miRTarBase as one of the most comprehensively annotated and experimentally validated miRNA–target interaction databases. The updated version of miRTarBase is now available at http://miRTarBase.cuhk.edu.cn/.
This paper proposes a novel nonnegative sparse representation approach, called two-stage sparse representation (TSR), for robust face recognition on a large-scale database. Based on the divide and ...conquer strategy, TSR decomposes the procedure of robust face recognition into outlier detection stage and recognition stage. In the first stage, we propose a general multisubspace framework to learn a robust metric in which noise and outliers in image pixels are detected. Potential loss functions, including L 1 , L 2,1 , and correntropy are studied. In the second stage, based on the learned metric and collaborative representation, we propose an efficient nonnegative sparse representation algorithm to find an approximation solution of sparse representation. According to the L 1 ball theory in sparse representation, the approximated solution is unique and can be optimized efficiently. Then a filtering strategy is developed to avoid the computation of the sparse representation on the whole large-scale dataset. Moreover, theoretical analysis also gives the necessary condition for nonnegative least squares technique to find a sparse solution. Extensive experiments on several public databases have demonstrated that the proposed TSR approach, in general, achieves better classification accuracy than the state-of-the-art sparse representation methods. More importantly, a significant reduction of computational costs is reached in comparison with sparse representation classifier; this enables the TSR to be more suitable for robust face recognition on a large-scale dataset.
3,4‐Dihydroquinolinones were synthesized by the palladium‐catalyzed, oxidative‐addition‐initiated activation and arylation of inert C(sp3)H bonds. Pd(OAc)2 and P(o‐tol)3 were used as the catalyst ...and ligand, respectively, to improve the efficiency of the reaction. A further advantage of this reaction is that it could be performed in air. A relatively rare seven‐membered palladacycle was proposed as a key intermediate of the catalytic cycle.
3,4‐Dihydroquinolinones were synthesized by the palladium‐catalyzed, oxidative‐addition‐initiated activation and arylation of inert C(sp3)H bonds. Pd(OAc)2 and P(o‐tol)3 were used as the catalyst and ligand, respectively, to improve the efficiency of the reaction. A further advantage of this reaction is that it could be performed in air.
The existing phase shifter models adopted for reconfigurable intelligent surfaces (RISs) have ignored the electromagnetic (EM) waves propagation behavior, thus cannot reveal practical effects of RIS ...on wireless communication systems. Based on the equivalent circuit, this letter introduces an angle-dependent phase shifter model for varactor-based RISs. To the best of our knowledge, this is the first phase shifter model which reveals that the incident angle of EM waves has influence on the reflection coefficient of RIS. In addition, the angle-reciprocity on RIS is investigated and further proved to be tenable when the reflection phase difference of adjacent RIS unit cells is invariant for an impinging EM wave and its reverse incident one. The angle-dependent characteristic of RIS is verified through full-wave simulation. According to our analysis and the simulation results, we find that the angle-reciprocity of varactor-based RIS only holds under small incident angles of both forward and reverse incident EM waves, thus limits the channel reciprocity in RIS-assisted TDD systems.
Substitutional heterovalent doping represents an effective method to control the optical and electronic properties of nanocrystals (NCs). Highly monodisperse II−VI NCs with deep substitutional ...dopants are presented. The NCs exhibit stable, dominant, and strong dopant fluorescence, and control over n‐ and p‐type electronic impurities is achieved. Large‐scale, bottom‐up superlattices of the NCs will speed up their application in electronic devices.
The applications of lithium-ion batteries (LIBs) still suffer from thermal sensitivity and safety issues, especially given the rigorous requirements of fast charging and discharging. When choosing a ...proper battery thermal management system (BTMS), a comprehensive investigation should be made in terms of design complexity, system cost, and cooling efficiency, which usually forms a trade-off. In this study, four types of BTMS including air cooling, single phase immersion, indirect cooling, and two phase immersion are first evaluated on pouch battery pack. To describe the uniform heat generation, batteries are simulated by a three-dimensional electrochemical-thermal coupled model. Results show that air cooling and immersion cooling exhibits less extra weight, while two phase immersion delivers better in suppressing temperature rise and maintaining temperature uniformity. Then, the simulations involving different coolants are conducted for two phase immersion-based BTMS. The thermal behaviors of battery pack are examined at 5, 7, and 9 C discharge rates. The R1336mzz(Z) coolant with high boiling heat transfer coefficient is suitable for thermal management at high discharge rates. Besides, analysis reveals that increasing the immersion level of battery pack can improve battery temperature behaviors. This work is expected to provide preliminary proof of BTMS design for fast discharging.
•A three-dimensional electrochemical-thermal coupled model for a pouch battery is established.•Comparative studies on air cooling, single phase immersion, indirect cooling and two phase immersion are conducted.•Effects of different immersion coolants and immersion levels are investigated.•R1336mzz(Z) performs optimal in regulating temperature and higher immersion level is recommended at fast discharging.
Metabolic reprogramming greatly contributes to the regulation of macrophage activation. However, the mechanism of lipid accumulation and the corresponding function in tumor-associated macrophages ...(TAMs) remain unclear. With primary investigation in colon cancer and confirmation in other cancer models, here we determine that deficiency of monoacylglycerol lipase (MGLL) results in lipid overload in TAMs. Functionally, macrophage MGLL inhibits CB2 cannabinoid receptor-dependent tumor progression in inoculated and genetic cancer models. Mechanistically, MGLL deficiency promotes CB2/TLR4-dependent macrophage activation, which further suppresses the function of tumor-associated CD8+ T cells. Treatment with CB2 antagonists delays tumor progression in inoculated and genetic cancer models. Finally, we verify that expression of macrophage MGLL is decreased in cancer tissues and positively correlated with the survival of cancer patients. Taken together, our findings identify MGLL as a switch for CB2/TLR4-dependent macrophage activation and provide potential targets for cancer therapy.
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