Phase Control on Surface for the Stabilization of High Energy Cathode Materials of Lithium Ion Batteries.

The development of high energy electrode materials for lithium ion batteries is challenged by their inherent instabilities, which become more aggravated as the energy densities continue to climb, accordingly causing increasing concerns on battery safety and reliability. Here, taking the high voltage cathode of LiNi0.5Mn1.5O4 as an example, we demonstrate a protocol to stabilize this cathode through a systematic phase modulating on its particle surface. We are able to transfer the spinel surface into a 30 nm shell composed of two functional phases including a rock-salt one and a layered one. The former is electrochemically inert for surface stabilization while the latter is designated to provide necessary electrochemical activity. The precise synthesis control enables us to tune the ratio of these two phases, and achieve an optimized balance between improved stability against structural degradation without sacrificing its capacity. This study highlights the critical importance of well-tailored surface phase property for the cathode stabilization of high energy lithium ion batteries

Novel Pactamycin Analogs Induce p53 Dependent Cell-Cycle Arrest at S-Phase in Human Head and Neck Squamous Cell Carcinoma (HNSCC) Cells

Pactamycin, although putatively touted as a potent antitumor agent, has never been used as an anticancer drug due to its high cytotoxicity. In this study, we characterized the effects of two novel biosynthetically engineered analogs of pactamycin, de-6MSA-7-demethyl-7- deoxypactamycin (TM-025) and 7-demethyl-7-deoxypactamycin (TM-026), in head and neck squamous cell carcinoma (HNSCC) cell lines SCC25 and SCC104. Both TM-025 and TM-026 exert growth inhibitory effects on HNSCC cells by inhibiting cell proliferation. Interestingly, unlike their parent compound pactamycin, the analogs do not inhibit synthesis of nascent protein in a cell-based assay. Furthermore, they do not induce apoptosis or autophagy in a dose- or a time-dependent manner, but induce mild senescence in the tested cell lines. Cell cycle analysis demonstrated that both analogs significantly induce cell cycle arrest of the HNSCC cells at S-phase resulting in reduced accumulation of G2/M-phase cells. The pactamycin analogs induce expression of cell cycle regulatory proteins including master regulator p53, its downstream target p21Cip1/WAF1, p27kip21, p19, cyclin E, total and phospho Cdc2 (Tyr15) and Cdc25C. Besides, the analogs mildly reduce cyclin D1 expression without affecting expression of cyclin B, Cdk2 and Cdk4. Specific inhibition of p53 by pifithrin- α reduces the percentage of cells accumulated in S-phase, suggesting contribution of p53 to S-phase increase. Altogether, our results demonstrate that Pactamycin analogs TM- 025 and TM-026 induce senescence and inhibit proliferation of HNSCC cells via accumulation in S-phase through possible contribution of p53. The two PCT analogs can be widely used as research tools for cell cycle inhibition studies in proliferating cancer cells with specific mechanisms of action

Screening of deafness-causing DNA variants that are common in patients of European ancestry using a microarray-based approach

The unparalleled heterogeneity in genetic causes of hearing loss along with remarkable differences in prevalence of causative variants among ethnic groups makes single gene tests technically inefficient. Although hundreds of genes have been reported to be associated with nonsyndromic hearing loss (NSHL), GJB2, GJB6, SLC26A4, and mitochondrial (mt) MT-RNR1 and MTTS are the major contributors. In order to provide a faster, more comprehensive and cost effective assay, we constructed a DNA fluidic array, CapitalBioMiamiOtoArray, for the detection of sequence variants in five genes that are common in most populations of European descent. They consist of c.35delG, p.W44C, p.L90P, c.167delT (GJB2); 309kb deletion (GJB6); p.L236P, p.T416P (SLC26A4); and m.1555A>G, m.7444G>A (mtDNA). We have validated our hearing loss array by analyzing a total of 160 DNAs samples. Our results show 100% concordance between the fluidic array biochip-based approach and the established Sanger sequencing method, thus proving its robustness and reliability at a relatively low cost

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Methods and prospects for lithospheric structure imaging

In recent years, with rich observation data, the perfection of physical chemistry theory and the remarkable improvement of computer technology, great changes have taken place in the understanding of lithospheric physical and chemical properties. This paper introduces the current imaging methods of lithospheric structure and their advantages and disadvantages. Based on thermodynamic simulation and probability density inversion, we study the lithospheric thermal and compositional structure in South China (Sichuan Basin, Jiangnan Orogenic Belt, Lower Yangtze Craton and Cathaysian Block)using the observed Rayleigh wave phase velocity dispersion curve, geoid height, topography and surface heat flow. The results show that the lithosphere in the east of South China block is thin, and the lithospheric mantle is dominated by fertile peridotite, while the subduction of the Pacific plate from east to west may be the main dynamic mechanism of lithospheric thinning in the east of South China.Finally, we introduce the existing problems of lithospheric structure imaging and the prospect of future lithospheric structure imaging based on the current research status of lithospheric structure

Discrete element simulation study on micromechanical characteristics of undisturbed and remolded loess in biaxial test

Loess is a special granular material, and its mechanical properties are determined by the microscopic structure of granules. The undisturbed and remolded loess have different mechanical properties due to the difference in structure. In order to solve the basic problem of how the structural properties of loess affect its mechanical characteristics, based on scanning electron microscopy (SEM) to study the macroscopic and microscopic mechanical properties of undisturbed loess and saturated remolded loess under constant strain rate biaxial test, while considering the shape of particles and the possibility of particle breakage. The simulation results show that when the stress is low, the undisturbed loess and the remolded loess force chains are mostly distributed near the large framework particles. With the increase of stress, the undisturbed force chains form a network pattern but still have the main conduction region, while the remolded loess has no obvious major conduction region and presents a uniform mesh. Under the same confining pressure and strain, the number of cracks in the undisturbed loess is lower and they are concentrated in the shear zone. The number of cracks in the remolded loess is more but more uniform.Tension cracks are mostly formed around the clusters of undisturbed loess and remolded loess. Shear cracks are mostly formed inside the clusters of framework particles, and the most obvious is when the clusters of particles are in contact with each other. Using this modeling method can effectively reflect the different internal stress states of undisturbed and remolded loess under the same stress condition due to the difference in internal structure composition. Based on the above research conclusions, a microscopic explanation of the influence of loess structure on the macroscopic strength is given. The research results can provide a certain basis for the prevention and control of geological disasters in the loess area