Coordination States and Catalytic Performance of Ti in Titanium Silicalite-1

In the past two decades, we studied the synthesis, modification, and application of titanium silicalite-1 (TS-1) systematically with the goal of exploring its role as a catalyst for industrial selective oxidation reactions. Three factors were primarily considered for catalytic performance: the coordination states of titanium ions, locations of titanium ions, and diffusion properties. The coordination state of Ti, which was the most important of all the three factors, was tuned by controlling the synthesis conditions and posttreating with organic bases. Spectroscopy was used to help establishing the relationship between catalytic activity and coordination state. More active titanium species were located on the external surface by posttreatment, so the catalytic performance for larger molecules was improved significantly. The diffusion properties can be enhanced by posttreatment with organic bases. Furthermore, meso−/microporous titanium silicalite was synthesized by one-pot synthesis with cetyltrimethyl ammonium bromide (CTAB) as a mesoporous porogen. The TS-1 plate with a short b-axis length was also provided

Distinguishing quantum dynamics via Markovianity and Non-Markovianity

To study various quantum dynamics, it is important to develop effective methods to detect and distinguish different quantum dynamics. A common non-demolition approach is to couple an auxiliary system (ancilla) to the target system, and to measure the ancilla only. By doing so, the target system becomes an environment for the ancilla. Thus, different quantum dynamics of target systems will correspond to different environment properties. Here, we analytically study XX spin chains presenting different kinds of quantum dynamics, namely localized, delocalized, and dephasing dynamics, and build connections between Markovianity and non-Markovianity - the two most common properties of an environment. For a qubit coupled to the XX chain, we derived the reduced density matrix of the qubit through the projection method. Furthermore, when dephasing noise was introduced to the XX chain, we generalized the projection method by introducing an open-system interaction picture - a modification of the Dirac interaction picture. By calculating the reduced density matrix for the qubit analytically and numerically, we found that the delocalized (localized) chain corresponds to the Markovian (non-Markovian) bath when boundary effects are not considered, and the feature of the chain with dephasing noise as a bath is dependent on the dephasing strength. The three kinds of quantum dynamics can be distinguished by measuring the qubit only.Comment: 6 pages, 8 figure

Keldysh Nonlinear Sigma Model for a Free-Fermion Gas under Continuous Measurements

We analytically analyze the quantum dynamics of a $d$-dimension free-fermion gas subject to continuous projective measurements. By mapping the Lindblad master equation to the functional Keldysh field theory, we observe that the Keldysh Lindblad partition function resembles that in the Keldysh treatment of the disordered fermionic systems. Based on this observation, we develop an effective theory termed as the Keldysh nonlinear sigma model to describe the low-energy physics. Two types of diffuson correlators, similar to those in the disordered fermionic systems, are derived. In addition, up to the one-loop level of the effective theory, we obtain a Drude-form conductivity where the elastic scattering time is replaced by the inverse measurement strength. According to these similarities, these two different concepts, i.e., projective measurements and disorders, are unified in the same framework.Comment: 10 pages, updated the reference list in V

Isolation of microsatellite markers for Bletilla striata and cross-amplification in other related species

Bletilla is a temperate, terrestrial genus of orchids containing 6 species. For the species whose whole genome is unknown, we used magnetic bead hybridization method to develop microsatellite Simple Repeat Polymorphoresis (SSR) for Bletilla striata and 9 primer sets were characterized in two wild populations of B. striata and one wild population of Bletilla ochracea. The number of alleles per locus ranged from 1 to 12. The expected and observed heterozygosities ranged from 0 to 0.7646 and 0 to 0.950 in B. striata, respectively. In B. ochracea, the expected and observed heterozygosities ranged from 0.296 to 0.871 and 0.05 to 1, respectively. The 9 pairs of primers we designed can be used to distinguish different ecotypes and species, and might be used for other subspecies or species in genera Bletilla.Keywords: Bletilla striata, cross-species amplification, simple repeat polymorphoresis (SSR)

Rejuvenation of brain, liver and muscle by simultaneous pharmacological modulation of two signaling determinants, that change in opposite directions with age.

We hypothesize that altered intensities of a few morphogenic pathways account for most/all the phenotypes of aging. Investigating this has revealed a novel approach to rejuvenate multiple mammalian tissues by defined pharmacology. Specifically, we pursued the simultaneous youthful in vivo calibration of two determinants: TGF-beta which activates ALK5/pSmad 2,3 and goes up with age, and oxytocin (OT) which activates MAPK and diminishes with age. The dose of Alk5 inhibitor (Alk5i) was reduced by 10-fold and the duration of treatment was shortened (to minimize overt skewing of cell-signaling pathways), yet the positive outcomes were broadened, as compared with our previous studies. Alk5i plus OT quickly and robustly enhanced neurogenesis, reduced neuro-inflammation, improved cognitive performance, and rejuvenated livers and muscle in old mice. Interestingly, the combination also diminished the numbers of cells that express the CDK inhibitor and marker of senescence p16 in vivo. Summarily, simultaneously re-normalizing two pathways that change with age in opposite ways (up vs. down) synergistically reverses multiple symptoms of aging

Crossover between Weak Antilocalization and Weak Localization of Bulk States in Ultrathin Bi2Se3 Films

We report transport studies on the 5 nm thick Bi2Se3 topological insulator films which are grown via molecular beam epitaxy technique. The angle-resolved photoemission spectroscopy data show that the Fermi level of the system lies in the bulk conduction band above the Dirac point, suggesting important contribution of bulk states to the transport results. In particular, the crossover from weak antilocalization to weak localization in the bulk states is observed in the parallel magnetic field measurements up to 50 Tesla. The measured magneto-resistance exhibits interesting anisotropy with respect to the orientation of B// and I, signifying intrinsic spin-orbit coupling in the Bi2Se3 films. Our work directly shows the crossover of quantum interference effect in the bulk states from weak antilocalization to weak localization. It presents an important step toward a better understanding of the existing three-dimensional topological insulators and the potential applications of nano-scale topological insulator devices