Effect of tunable π bridge on two-photon absorption property and intramolecular charge transfer process of polycyclic aromatic hydrocarbons.

The influences of the conjugation effect on the charge transfer and nonlinear optical (NLO) properties of polycyclic aromatic hydrocarbons (PAHs) are comprehensively investigated at the microscopic molecular level. We found that the conjugation effect of π bridge is negatively correlated with molecular planarity, excitation energy, two-photon absorption (TPA) cross-section, and the second hyperpolarizability. For the first time, the charge transfer matrix (CTM) is applied to the molecular two-photon transition process. Combining the charge difference density (CDD) diagram with CTM heat map to visually quantitative investigate the characteristics of excited states, the charge transfer path and transfer amount between atoms. During the two-photon transition of all molecules, the electronic excited state is locally excited. Compared with the first process, the range of intramolecular charge transfer in the second process of the two-photon transition is expanded. Comprehensive results prove that the π bridge with large conjugation effect distorts the molecular structure, which is not conducive to the intramolecular charge transfer. Therefore, the molecule DBP-1 with a carbon-carbon double bond as the π bridge has the largest transition dipole moments, TPA cross-section, and second static hyperpolarizability. Our research method can provide effective guidance for the design and optimization of nonlinear organic conjugated molecular materials.

Sandwiched ZnO@Au@CdS nanorod arrays with enhanced visible-light-driven photocatalytical performance.

The development of high-performance photocatalysts is central to efforts focused on taking advantage of solar energy to overcome environmental and energy crises. Integrating different functional materials artfully into nanostructures can deliver more efficient photocatalytic activity. Here, sandwiched ZnO@Au@CdS nanorod films were synthesized via successive ZnO nanorod electrodeposition, Au sputtering and CdS electrodeposition. The as-synthesized composites were characterized by UV-vis spectrophotometer, x-ray diffractometer, scanning and transmission electron microscopy. Their photocatalytic activity was assessed by degrading Rhodamine B solution under visible light irradiation. ZnO@Au@CdS exhibited better photocatalytic performance than ZnO@CdS throughout the visible light region, and the corresponding enhancement factor of Au nanoparticles was measured as a function of CdS loading amount, and it could reach 190% with CdS deposition for 1 min. The normalized rate constant could reach 0.387 h-1 for ZnO@Au@CdS-1min, which was equivalent to or better than results in reference photocatalysts. The enhancement mechanism of Au nanoparticles was estimated by comparing the monochromatic photocatalytic action spectra with the absorption spectrum of ZnO@Au@CdS, and it was mainly determined by incident photon energy. With selective excitation of Au nanoparticles by incident photons, the excited hot electrons in Au NPs are transferred to the conduction band of ZnO to boost photocatalytic reaction. With selective excitation of CdS, the enhanced interband absorption of CdS and relay station effect of Au nanoparticles should be responsible for the enhanced photocatalytic performance. Our work not only opens the door to the design of efficient supported photocatalysts, but also helps to understand the enhancement mechanism of LSPR effect on the photoelectric conversion of semiconductors.

Mechanism for the photoreduction of poly(vinylpyrrolidone) to HAuCl4 and the dominating saturable absorption of Au colloids.

Both fabrication of Au nano-objects and the nonlinear optical properties of Au nano-objects are the focus of research. In the present work, Au nanoparticles with different mean sizes (18, 32, 42, and 70 nm) are controllably fabricated in ethanol by changing the concentration of poly(vinylpyrrolidone) (PVP) and HAuCl4, as well as the power of continuous wave UV light at 365 nm. PVP acts as both reducing and protective agent. The mechanism of photoreduction of PVP to HAuCl4 is proposed. PVP undergoes a series of chemical reactions which include the attack of the hydrogen atom on the tertiary carbon atom at the α-position of the nitrogen atom, production of a hydroxyl radical, and chain scission. The hydroxyl radical combines with the hydrogen atom produced through the dissociation of HAuCl4, which facilitates the decomposition of HAuCl4. The fabrication mechanism of Au nanoparticles is discussed. The nonlinear absorption of these Au nanoparticles is investigated; all of them exhibit saturable absorption, and the saturable absorption dominates the nonlinear absorption with the increase of laser energy. The dominance of saturable absorption in the nonlinear absorption is due to the stronger single-photon absorbed intraband absorption from the ground state to the first excited state in the conduction band, the weaker excited state absorption in the conduction band, and the weaker two-photon absorption from the d band to the conduction band.

Advanced light-trapping effect of thin-film solar cell with dual photonic crystals.

A thin-film solar cell with dual photonic crystals has been proposed, which shows an advanced light-trapping effect and superior performance in ultimate conversion efficiency (UCE). The shapes of nanocones have been optimized and discussed in detail by self-definition. The optimized shape of nanocone arrays (NCs) is a parabolic shape with a nearly linearly graded refractive index (GRI) profile from the air to Si, and the corresponding UCE is 30.3% for the NCs with a period of 300 nm and a thickness of only 2 µm. The top NCs and bottom NCs of the thin film have been simulated respectively to investigate their optimized shapes, and their separate contributions to the light harvest have also been discussed fully. The height of the top NCs and bottom NCs will also influence the performances of the thin-film solar cell greatly, and the result indicates that the unconformal NCs have better light-trapping ability with an optimal UCE of 32.3% than the conformal NCs with an optimal UCE of 30.3%.

Resveratrol inhibits oesophageal adenocarcinoma cell proliferation via AMP-activated protein kinase signaling.

Resveratrol has been examined in several model systems for potential effects against cancer. Adenosine monophosphate-activated protein kinase (AMPK) is reported to suppress proliferation in most eukaryocyte cells. Whether resveratrol via AMPK inhibits proliferation of oesophageal adenocarcinoma cells (OAC) is unknown. The aim of this study was to determine the roles of AMPK in the protective effects of resveratrol in OAC proliferation and to elucidate the underlying mechanisms. Treatment of cultured OAC derived from human subjects or cell lines with resveratrol resulted in decreased cell proliferation. Further, inhibition of AMPK by pharmacological reagent or genetical approach abolished resveratrol-suppressed OAC proliferation, reduced the level of p27Kip1, a cyclin-dependent kinase inhibitor, and increased the levels of S-phase kinase-associated protein 2 (Skp2) of p27Kip1-E3 ubiquitin ligase and 26S proteasome activity reduced by resveratrol. Furthermore, gene silencing of p27Kip1 reversed resveratrol-suppressed OAC proliferation. In conclusion, these findings indicate that resveratrol inhibits Skp2-mediated ubiquitylation and 26S proteasome-dependent degradation of p27Kip1 via AMPK activation to suppress OAC proliferation.

[Analysis of preoperative concurrent chemoradiotherapy in the treatment of patients with superior sulcus tumor of the lung].

BACKGROUND: Recently chemoradiotherapy becomes a standard treatment for un- resectable advanced non-small cell lung cancer (NSCLC) instead of radiotherapy alone. Superior sulcus tumor of the lung (Pancoast tumor) is a clinical subtype of NSCLC. The aim of this study is to compare the clinical effects and toxicities of preoperative concurrent chemoradiotherapy with radiotherapy alone in patients with superior sulcus tumors. METHODS: Fifty-six patients with superior sulcus tumors were divided randomly into two groups: twenty-six patients received concurrent chemoradiotherapy (chemoradiotherapy group), the other thirty patients received only radiotherapy (radiotherapy group). For both groups, the same radiation technic was given with the convention fraction. The total dose was 45Gy/25 fraction/5 weeks. For the chemoradiotherapy group, the patients were also given with concurrent chemotherapy (navelbine 15-18mg/m² on the 1st and 8th day, cisplatin 60mg/m² on the 1st day). RESULTS: The rate of complete resection in the chemoradiotherapy group was significantly higher than that in the radiotherapy group (92.3% vs 80.0%, P < 0.05); The complete pathological response rate and 2-year survival rate in the chemoradiotherapy group were significantly higher than those in the radiotherapy group (P < 0.01, P < 0.01). The incidences of grade III-IV radiation esophagitis and leukopenia in the chemoradiotherapy group were significantly higher than those in the radiotherapy group (23.1% and 23.1% vs 6.7% and 0, P < 0.01, P < 0.01). CONCLUSIONS: Preoperative concurrent chemoradiotherapy has the potential of improving the survival rate of superior sulcus tumors. It can also increase the acute toxic effect, but all patients can tolerate this treatment regimen, so it might be a new "standard treatment" for superior sulcus tumor of the lung.

[Study on the determination of Cd and Pb in Radix Salviae Miltiorrhizae by ICP-AES].

In the present paper, a method was developed for the determination of Cd and Pb by ICP-AES. The effects of two different sample treatment methods, including wet digestion method and dry ash method, were compared. The contents of Cd and Pb in Danshen (Radix Salviae miltiorrhizae) grown in some areas of Shandong were determined. The results show that it is satisfactory to apply ICP-AES to the determination of Cd and Pb with the detection limits (DL) of 1.92 ng x mL(-1) and 1.07 ng x mL(-1), the precision values (RSD) of 3.14% and 1.83%, and the recovery rates of 103.0% and 96.2% respectively. The wet digestion method is better than the dry ash method for its lower RSD and higher recovery rate. The dry ash method is suitable for the determination of Pb, but not suitable for the determination of Cd due to its low recovery rate. The results also show that the contents of Cd and Pb in Danshen are lower than the standard of Chinese Pharmacopoeia (2005), which meets the standard of GAP production.