Quantifying the Volumetric Performance Metrics of Supercapacitors

Nanostructured materials have greatly improved the performance of electrochemical energy storage devices because of the increased activity and surface area. However, nanomaterials (e.g., nanocarbons) normally possess low packing density, and thus occupy more space which restricts their suitability for making electrochemical devices as compact as possible. This has resulted in their low volumetric performance (capacitance, energy density, and power density), which is a practical obstacle for the application of nanomaterials in mobile and on‐board energy storage devices. While rating electrode materials for supercapacitors, their volumetric performance is equally important as the gravimetric metrics and more reliable in particular for systems with limited space. However, the adopted criteria for measuring the volumetric performance of supercapacitors vary in the literature. Identifying the appropriate performance criteria for the volumetric values will set a universal ground for valid comparison. Here, the authors discuss the rationale for quantifying the volumetric performance metrics of supercapacitors from the three progressive levels of materials, electrodes, and devices. It is hoped that these thoughts will be of value for the general community in energy storage research.     

Refilling Nitrogen to Oxygen Vacancies in Ultrafine Tungsten Oxide Clusters for Superior Lithium Storage

Morphological engineering of nanosized transitional metal oxides shows great promise for performance improvement, yet limited efforts have been attempted to engineer the atomic structure. Oxygen vacancy (V_O) can boost charge transfer leading to enhanced performance; yet excessive V_O may impair the conductivity. Herein, tungsten oxide is atomically tailored by incorporating nitrogen heteroatoms into the oxygen vacancies. The efficient nitrogen‐filling into the oxygen vacancies is evidenced by the electron paramagnetic resonance spectroscopy and X‐ray absorption spectroscopy. The coordinated N atoms play a crucial role in facilitating the charge transfer and maintaining efficient lithium‐ion diffusion. Consequently, the tungsten oxide with N‐filled oxygen vacancies exhibits superior lithium‐ion storage performance.     

Inhibition of polypeptide N-acetyl-α-galactosaminyltransferases is an underlying mechanism of dietary polyphenols preventing colorectal tumorigenesis

Ellagitannin-derived ellagic acid (EA) and colonic metabolite urolithins are functional dietary ingredients for cancer prevention, but the underlying mechanism need elucidation. Mucin-type O-glycosylation, initiated by polypeptide N-acetyl-α-galactosaminyltransferases (ppGalNAc-Ts), fine-tunes multiple biological processes and is closely associated with cancer progression. Herein, we aim to explore how specific tannin-based polyphenols affect tumor behavior of colorectal cancer cells (CRC) by modulating O-glycosylation. Utilizing HPLC-based enzyme assay, we find urolithin D (UroD), EA and gallic acid (GA) potently inhibit ppGalNAc-Ts. In particular, UroD inhibits ppGalNAc-T2 through a peptide/protein-competitive manner with nanomolar affinity. Computational simulations combined with site-directed mutagenesis further support the inhibitors’ mode of action. Moreover, lectin analysis and metabolic labelling reveal that UroD can reduce cell O-glycans but not N-glycans. Transwell experiments prove that UroD inhibits migration and invasion of CRC cells. Our work proves that specific tannin-based polyphenols can potently inhibit ppGalNAc-Ts activity to reduce cell O-glycosylation and lead to lowering the migration and invasion of CRC cells, suggesting that disturbance of mucin-type O-glycosylation is an important mechanism for the function of dietary polyphenols.     

Evaluating changes to Ralstonia pickettii in high-purity water to guide selection of potential calibration materials for online water bioburden analyzers

Online water bioburden analyzers (OWBAs) can provide real-time feedback on viable bacteria in high-purity water (HPW) systems for pharmaceutical manufacturers. To calibrate and validate OWBAs, which detect bacteria using scattered light and bacterial autofluorescence, standards are needed that mimic the characteristics of bacteria in HPW. To guide selection of potential standards, e.g., fluorescent microspheres, a relevant bacterial contaminant, Ralstonia pickettii, was characterized for size, count, viability, and autofluorescence after exposure for 24 h to HPW or a nutrient environment. The cells exposed to HPW showed smaller sizes, with lower counts and autofluorescence intensities, but similar spectral features. The cell characteristics are discussed in comparison with a set of fluorescent microspheres, considering factors relevant to OWBAs. These studies suggest that fluorescent microspheres should be relatively small (< 1 µm diameter) and dim, while covering a broad emission range from ≈ (420 to 600) nm to best mimic the representative R. pickettii.

     

人嗅黏膜间充质干细胞来源外泌体的分离鉴定及生物学特性研究

外泌体是指释放到细胞外微环境中的直径约50～130 nm的纳米级的膜性囊泡。嗅黏膜间充质干细胞（olfactory mucosa mesenchymal stem cells,OM-MSCs）作为一类新发现的间充质干细胞,在许多疾病中均具有治疗作用,且其内在机制与其旁分泌的外泌体密切相关,但OM-MSCs外泌体的分离、鉴定及生物学特性的研究尚未见报道。本研究采用超速离心法提取OM-MSCs培养液中的外泌体,应用流式细胞术及免疫荧光进行细胞鉴定后,分别用透射电子显微镜、纳米粒径分析及Western印迹对外泌体形态、颗粒大小和表面的特异性分子标志进行分析鉴定。采用CCK8增殖实验,Western印迹和划痕实验,分析其对人脑微血管内皮细胞增殖和迁移的影响。电镜、Western 印迹和纳米粒径分析的结果显示：OM-MSCs来源外泌体形态多为圆形,直径约为40～150 nm;表达外泌体标记物CD63,CD81;CCK-8法检测显示：不同浓度的OM-MSCs源外泌体可提高人脑微血管内皮细胞的增殖活性,且其增殖促进作用具有浓度依赖性（P<0.05）。Western 印迹检测结果显示：相比空白对照组,OM-MSCs源外泌体可显著提高内皮细胞的增殖细胞核抗原蛋白质水平表达（P<0.01）,细胞划痕实验结果显示,OM-MSCs源外泌体可增强内皮细胞的迁移能力,且高于对照组（P<0.01）。本研究表明：通过超速离心法可以分离纯化获得OM-MSCs源外泌体,且该外泌体具有促进人脑微血管内皮细胞迁移和增殖的作用。     

Waist-to-height ratio is an accurate and easier index for evaluating obesity in children and adolescents

Objectives: The present study aims to evaluate the accuracy of the index of waist‐to‐height ratio (WHTR), and proposed the optimal thresholds of WHTR in the definition of childhood overweight and obesity in a bi‐ethnic Chinese school‐aged population. Research Methods and Procedures: Overweight and obese were identified by BMI for age and gender in a random sample including 2055 Han and 2132 Uygur ethnic school‐aged children (8 to 18 years old). WHTR was calculated by waist circumference divided by height on the basis of standard anthropometric measurements. Receiver operating characteristic (ROC) curve analyses were performed to assess the accuracy of WHTR as a diagnostic test for childhood overweight and obesity, compared with waist circumference. The optimal thresholds of WHTR for defining overweight and obesity were recommended respectively by gender. The correlation between WHTR and age was analyzed and compared with BMI. Results: A‐values (area under curve) of WHTR for diagnosing overweight and obesity were both over 0.90 in both genders and better than those of waist circumference. A threshold of 0.445 was identified for overweight in both genders, with the sensitivity and specificity >0.80. The thresholds for defining obesity was 0.485 in boys and 0.475 in girls, both having the sensitivity and specificity >0.90. WHTR showed less association with age than BMI. Conclusions: WHTR is a simple, easy, accurate, and non‐age‐dependent index with high applicability to screening overweight and obesity in children and adolescents. The use of WHTR in the general childhood population has been justified by this study.     

Computational Simulations of the Early Steps of Protein Aggregation

There is strong evidence that the oligomers of key proteins, formed during the early steps of aggregation, could be the primary toxic species associated with human neurodegenerative diseases, such as Alzheimer''s and prion diseases. Here, we review recent progress in the development of computational approaches in order to understand the structures, dynamics and free energy surfaces of oligomers. We also discuss possible research directions for the coming years.Key Words: protein aggregation, simulations, amyloid fibril, oligomers, coarse-grained model, inhibitors