Nano-scale study on molecular structure, thermal stability, and mechanical properties of geopolymer

The well thermal stability and mechanical properties of geopolymer can be attributed to its predominant adhesive constituent, sodium alumino-silicate hydrate (N-A-S-H). However, the intrinsic relation between molecular structure, stoichiometry, and performance of N-A-S-H is far from being understood. Herein, the structure, thermal stability, and tensile behavior of N-A-S-H at different Si/Al ratio are investigated by means of ReaxFF molecular dynamics. The results show that, after extreme low/high temperature treatment, the atomic configuration can also recover to a large extent. The hydrolysis during high temperature treatment slightly inhibits the structure recovery. Its expansion strain at elevated temperature is much smaller than that of calcium silicate hydrate, the primary component of Portland cement. Aluminum addition diminishes alumino-silicate skeleton’s connectivity and promotes the formation of energetically unstable Al–O–Al bonds, resulting in the drop of thermal stability and mechanical properties. The consistence between simulations and experiments demonstrates the considerable function of molecular structure of N-A-S-H for the macro-performance of geopolymer. Graphical abstract: [Figure not available: see fulltext.] Sodium alumino-silicate hydrate (N-A-S-H), featuring cross-linked glassy structure, exhibits excellent thermal stability. Mechanical properties increase with Si/Al ratio

Lifetime Difference and Endpoint effect in the Inclusive Bottom Hadron Decays

The lifetime differences of bottom hadrons are known to be properly explained within the framework of heavy quark effective field theory(HQEFT) of QCD via the inverse expansion of the dressed heavy quark mass. In general, the spectrum around the endpoint region is not well behaved due to the invalidity of $1/m_Q$ expansion near the endpoint. The curve fitting method is adopted to treat the endpoint behavior. It turns out that the endpoint effects are truly small and the explanation on the lifetime differences in the HQEFT of QCD is then well justified. The inclusion of the endpoint effects makes the prediction on the lifetime differences and the extraction on the CKM matrix element $|V_{cb}|$ more reliable.Comment: 11 pages, Revtex, 10 figures, 6 tables, published versio

Correlation effects in the ground state charge density of Mott-insulating NiO: a comparison of ab-initio calculations and high-energy electron diffraction measurements

Accurate high-energy electron diffraction measurements of structure factors of NiO have been carried out to investigate how strong correlations in the Ni 3d shell affect electron charge density in the interior area of nickel ions and whether the new ab-initio approaches to the electronic structure of strongly correlated metal oxides are in accord with experimental observations. The generalized gradient approximation (GGA) and the local spin density approximation corrected by the Hubbard U term (LSDA+U) are found to provide the closest match to experimental measurements. The comparison of calculated and observed electron charge densities shows that correlations in the Ni 3d shell suppress covalent bonding between the oxygen and nickel sublattices.Comment: 6 pages, LaTeX and 5 figures in the postscript forma

Multivariate risks and depth-trimmed regions

We describe a general framework for measuring risks, where the risk measure takes values in an abstract cone. It is shown that this approach naturally includes the classical risk measures and set-valued risk measures and yields a natural definition of vector-valued risk measures. Several main constructions of risk measures are described in this abstract axiomatic framework. It is shown that the concept of depth-trimmed (or central) regions from the multivariate statistics is closely related to the definition of risk measures. In particular, the halfspace trimming corresponds to the Value-at-Risk, while the zonoid trimming yields the expected shortfall. In the abstract framework, it is shown how to establish a both-ways correspondence between risk measures and depth-trimmed regions. It is also demonstrated how the lattice structure of the space of risk values influences this relationship.Comment: 26 pages. Substantially revised version with a number of new results adde

Design of a thin-plate based tunable high-quality narrow passband filter for elastic transverse waves propagate in metals

For the elastic SV (transverse) waves in metals, a high-quality narrow passband filter that consists of aligned parallel thin plates with small gaps is designed. In order to obtain a good performance, the thin plates should be constituted by materials with a smaller mass density and Young’s modulus, such as polymethylmethacrylate (PMMA), compared to the embedded materials in which the elastic SV waves propagate. Both the theoretical model and the full numerical simulation show that the transmission spectrum of the designed filter demonstrates several peaks with flawless transmission within 0 KHz ∼20 KHz frequency range. The peaks can be readily tuned by manipulating the geometrical parameters of the plates. Therefore, the current design works well for both low and high frequencies with a controllable size. Even for low frequencies on the order of kilohertz, the size of this filter can be still limited to the order of centimeters, which significantly benefits the real applications. The investigation also finds that the same filter is valid when using different metals and the reason behind this is explained theoretically. Additionally, the effect of bonding conditions of interfaces between thin plates and the base material is investigated using a spring model

CD133 positive cells isolated from A549 cell line exhibited high liver metastatic potential

Lung cancer remains a major cause of cancer-related lethality because of high incidence and recurrence in spite of significant advances in staging and therapy. In present study, we identified a subpopulation of cells isolated from the A549 cell line with marker CD133. In vivo results showed that A549 CD133+ cells displayed high liver metastatic potential. Severe liver cell damage with tumor cell invasion revealed by pathological examination and these changes were consistent with the results of serological tests where the plasma GPT and GOT level are significantly higher than that of the control group. Compared with A549 cells, A549 CD133+ cells expressed high levels of VEGF and exhibited high migration and invasion capability. In conclusion, we first reported that A549 CD133+ cells exhibited characteristic of high liver metastatic potential which makes it be a suitable model for further study of liver metastasis of lung adenocarcinoma and provide a potential platform for anti-metastatic drug discovery or evaluation