Thermal stress coupling mechanism during nanosecond impulse delay for the synergistic study of continuous-nanosecond combined laser removal of the rubber layer on a concrete surface.

Based on the principle of laser ablation and elastic vibration effect, a model of continuous nanosecond combined laser removal of rubber marks on a concrete surface was established. The model can explain the evolution of temperature, stress, and removal depth on time and laser energy density during laser cleaning. The results show that the theoretical adsorption force between the rubber layer and the concrete base is approximately 3.88×10-9 N. The continuous laser cleaning threshold is 561.31J/c m 2. In the combined laser, the continuous laser is 534.41J/c m 2, and the nanosecond laser is 0.35J/c m 2. As the delay time between the 2 ns laser beams increases, the maximum peak in the temperature curve gradually decreases. The optimal cleaning delay was obtained as Δ t=0.65S. The peak temperature at the characteristic position (0 µm, 0 µm) is 592.13 K, which is lower than the vaporization temperature of the rubber layer. The thermal stress values generated at this characteristic position exceed the adsorption stress values, indicating that the elastic removal mechanism is the main removal mechanism at the junction between the rubber layer and the concrete substrate.

Photophysical Properties of (E)-1-(4-(Diethyla-mino)-2-hydroxybenzylidene)-4,4-dimethylthiosemicarbazide Compound and Its Triple Fluorescence Emission Mechanism: A Theoretical Perspective.

In view of the application prospects in biomedicine of (E)-1-(4-(diethyla-mino)-2-hydroxybenzylidene)-4,4-dimethylthiosemicarbazide (DAHTS), the behavior of excited-state dynamics and photophysical properties were studied using the density functional theory/time-dependent density functional theory method. A series of studies indicated that the intramolecular hydrogen-bond (IHB) intensity of DAHTS was enhanced after photoexcitation. This was conducive to promoting the excited-state intramolecular proton-transfer (ESIPT) process. Combining the analysis of the IHB and hole-electron, it revealed that the molecule underwent both the ESIPT process and the twisted charge-transfer (TICT) process. Relying on exploration of the potential energy surface, it was proposed that the different competitive mechanisms between the ESIPT and TICT processes were regulated by solvent polarity. In acetonitrile (ACN) solvent, the ESIPT process occurred first, and the TICT process occurred later. In contrast, in the CYH solvent, the molecule first underwent the TICT process and then the ESIPT process. Furthermore, we raised the possibility that the TICT behavior was the cause of weak fluorescence emission for the DAHTS in CYH and ACN solvents. By the dimer correlation analysis, the corresponding components of triple fluorescence emission were clearly assigned, corresponding to the monomer, dimer, and ESIPT isomer in turn. Our work precisely elucidated the photophysical mechanism of DAHTS and the attribution of the triple fluorescence emission components, which provided valuable guidance for the development and regulation of bioactive fluorescence probes with multiband and multicolor emission characteristics.

A Capillary-Force-Assisted Transfer for Monolayer Transition-Metal-Dichalcogenide Crystals with High Utilization.

The capillary-force-assisted transfer has shown application potential for constructing two-dimensional (2D) electronic and optoelectronic devices for the advantage of free of spin coating the organic compound and etching the substrate. Currently, the transfer mechanism remains obscure. The capillary adhesion mechanism and capillary invasion separation mechanism were proposed independently and rarely discussed in a comprehensive manner. What is more, the integrity and utilization remain to be improved. Here, we developed the capillary-force-assisted transfer method with high utilization and integrity. Uniformity of water transport was improved by introducing water from the sidewall of the small polydimethylsiloxane (PDMS) stamp driven by capillary force. The transfer integrity rate increased, and the location of the complete samples became predictable. The transfer utilization increased as the limited water transportation minimized the impact on the surrounding WS2. The monolayer triangle WS2 crystals from adjacent areas on the sapphire substrate were transferred one after another. Besides, local mechanical exfoliation of the continuous WS2 thin films was demonstrated, implying that the capillary adhesion is strong enough to break the strong in-plane covalent bond and overcome the van der Waals force between WS2 and sapphire substrate. Finally, the water transport model between two surfaces with different hydrophobicity combinations was derived on the basis of the Young-Laplace equation. The analysis of water transport between different interfaces reveals how capillary adhesion and capillary invasion work together to achieve capillary force transfer. This study highlights the potential of the capillary-force-assisted transfer as an efficient technique for fabricating van der Waals structures based on two-dimensional atomic crystals, especially periodic structures.

Comparative clinical studies of primary chemoradiotherapy versus S-1 and nedaplatin chemotherapy against stage IVb oesophageal squamous cell carcinoma: a multicentre open-label randomised controlled trial.

INTRODUCTION: Oesophageal squamous cell carcinoma (OSCC) is one of the most commonly occurring devastating tumours worldwide, including in China. To date, the standard care of patients with stage IV OSCC is systemic chemotherapy and palliative care, which results in poor prognosis. However, no consensus has been established regarding the role of radiotherapy in targeting the primary tumour in patients with stage IVa OSCC. Thus, the aim of this study is to assess the effectiveness of primary radiotherapy combined with S-1 and nedaplatin (NPD) chemotherapy in the patients with stage IV OSCC. METHODS AND ANALYSIS: The study is a multicentre, open-label, randomised controlled trial. A total of 180 eligible patients with stage IV OSCC will be randomised into a study group (90 patients) and a control group (90 patients). Patients in the study group will receive radiotherapy to the primary tumour at a dose of 50.4 Gy combined with 4-6 cycles of S-1 and NPD chemotherapy. In the control group, patients will only receive 4-6 cycles of S-1 and NPD chemotherapy. The primary and secondary outcomes will be measured. The differences between the two groups will be statistically analysed with regard to overall survival, the progression-free survival and safety. All outcomes will be ascertained before treatment, after treatment and after the follow-up period.The results of this study will provide evidence on the role of radiotherapy in patients with stage IV OSCC in China, which will show new options for patients with advanced oesophageal cancer. ETHICS AND DISSEMINATION: This study was approved by the Institutional Ethics Committee of The First Hospital Affiliated of Zhengzhou University (approval number: SS-2018-04). TRIAL REGISTRATION: The trial has been registered at the Chinese Clinical Trial Registry (ChiCTR1800015765) on 1 November 2018; retrospectively registered, http://www.chictr.org.cn/index.aspx.

Optimization Strategies for High Photoluminescence Quantum Yield of Monolayer Chemical Vapor Deposition Transition Metal Dichalcogenides.

Chemical vapor deposition (CVD) is a promising method to obtain monolayer transition metal dichalcogenides (TMDCs) with high quality and enough size to meet the requirements of practical photoelectric devices. However, the as-grown monolayers often exhibit a lower PL performance due to the stress between the as-grown TMDCs flakes and the substrate. Therefore, finding a facile method to effectively promote the photoluminescence quantum yield (PL QY) of CVD monolayer TMDCs with a clean surface is highly desirable for practical applications. In this work, based on the CVD monolayers MoS2 and MoSe2, the effect of various stress relaxation methods on the TMDCs PL enhancement is systemically studied. By comparing the different kinds of volatile solution treatment processes, as well as the traditional transfer process, it can be found that the volatile solution with a moderate volatilization rate such as ethanol or IPA is a preferred option to improve the PL performance of the CVD monolayer TMDCs, which also surpasses the traditional transfer method by avoiding wrinkles, defects, and contamination to the samples. PL QY of ethanol-treated CVD samples could increase by 6 times on average. Significantly, PL QY of CVD MoSe2 treated by ethanol can reach ∼16%, which is at the forefront of the previous reports of 2D MoSe2. Our study demonstrated an optimized method to enhance the PL QY of CVD monolayer TMDCs, which would facilitate TMDCs optoelectronics.