双激光脉冲打靶形成Gd等离子体的极紫外光谱辐射

高端芯片制造所需要的极紫外光刻技术位于我国当前面临35项"卡脖子"关键核心技术之首.高转换效率的极紫外光源是极紫外光刻系统的重要组成部分.本文通过采用双激光脉冲打靶技术实现较强的6.7 nm极紫外光输出.首先,理论计算Gd¹⁸⁺—Gd²⁷⁺离子最外层4d壳层的4p-4d和4d-4f能级之间跃迁、以及Gd¹⁴⁺—Gd¹⁷⁺离子最外层4f壳层的4d-4f能级之间跃迁对波长为6.7 nm附近极紫外光的贡献.其后开展实验研究,结果表明,随着双脉冲之间延时的逐渐增加,波长为6.7 nm附近的极紫外光辐射强度呈现先减弱、后增加、之后再减弱的变化趋势,在双脉冲延时为100 ns处产生的极紫外光辐射最强.并且,在延时为100 ns处产生的光谱效率最高,相比于单脉冲激光产生的光谱效率提升了33%.此外,发现双激光脉冲打靶技术可以有效地减弱等离子体的自吸收效应,获得的6.7 nm附近极紫外光谱宽度均小于单激光脉冲打靶的情形,且在脉冲延时为30 ns时刻所产生的光谱宽度最窄,约为单独主脉冲产生极紫外光谱宽度的1/3.同时...     

Tumor‐Targeting W18O49 Nanoparticles for Dual‐Modality Imaging and Guided Heat‐Shock‐Response‐Inhibited Photothermal Therapy in Gastric Cancer

Photothermal therapy (PTT) is an emerging noninvasive and precise localized therapeutic modality; however, it is deeply limited by its poor tumor accumulation, inadequate photothermal conversion efficiency, and the thermoresistance of cancer cells. Aimed at these shortcomings, tumor‐targeting nanoparticles (iRGD‐W₁₈O₄₉‐17AAG) comprising carboxyl‐group‐functionalized W₁₈O₄₉ nanoparticles, integrin‐targeting peptide iRGD, and HSP90‐inhibitor 17AAG are developed. The W₁₈O₄₉ nanoparticles act as excellent PTT carriers and computed tomography (CT) imaging contrast agents. The ring type polypeptide iRGD promotes the accumulation of nanoparticles in the tumour and further penetration into cancer cells. The introduction of 17AAG can inhibit the heat‐shock response and overcome the thermoresistance, thus increasing the curative effect of PTT and reducing the chance of tumor recurrence. The W₁₈O₄₉ nanoparticles can also be used to monitor and guide the phototherapeutic through CT and near‐infrared fluorescence imaging after modification with Cy5.5. In addition, superior biosafety is also indicated in both preliminary in vitro and in vivo assessments. The potential of iRGD‐W₁₈O₄₉‐17AAG in tumor targeting, dual modality imaging‐guided and remarkable enhanced PTT of gastric cancer with ignorable side effect both in vitro and in vivo, which may be further applied in clinic, is highlighted.     

Necessary and Sufficient Conditions for Qualitative Properties of Infinite Dimensional Linear Programming Problems

Necessary and sufficient conditions for qualitative properties of infinite dimensional linear programing problems such as solvability, duality, and complementary slackness conditions are studied in this article. As illustrations for the results, we investigate the parametric version of Gale’s example.     

Semi‐heterogeneous Dual Nickel/Photocatalysis using Carbon Nitrides: Esterification of Carboxylic Acids with Aryl Halides

Cross‐coupling reactions mediated by dual nickel/photocatalysis are synthetically attractive but rely mainly on expensive, non‐recyclable noble‐metal complexes as photocatalysts. Heterogeneous semiconductors, which are commonly used for artificial photosynthesis and wastewater treatment, are a sustainable alternative. Graphitic carbon nitrides, a class of metal‐free polymers that can be easily prepared from bulk chemicals, are heterogeneous semiconductors with high potential for photocatalytic organic transformations. Here, we demonstrate that graphitic carbon nitrides in combination with nickel catalysis can induce selective C?O cross‐couplings of carboxylic acids with aryl halides, yielding the respective aryl esters in excellent yield and selectivity. The heterogeneous organic photocatalyst exhibits a broad substrate scope, is able to harvest green light, and can be recycled multiple times. In situ FTIR was used to track the reaction progress to study this transformation at different irradiation wavelengths and reaction scales.     

General π‐Electron‐Assisted Strategy for Ir,Pt, Ru,Pd, Fe,Ni Single‐Atom Electrocatalysts with Bifunctional Active Sites for Highly Efficient Water Splitting

Both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are crucial to water splitting, but require alternative active sites. Now, a general π‐electron‐assisted strategy to anchor single‐atom sites (M=Ir, Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The M atoms can simultaneously anchor on two distinct domains of the hybrid support, four‐fold N/C atoms (M@NC), and centers of Co octahedra (M@Co), which are expected to serve as bifunctional electrocatalysts towards the HER and the OER. The Ir catalyst exhibits the best water‐splitting performance, showing a low applied potential of 1.603 V to achieve 10 mA cm^?2 in 1.0 m KOH solution with cycling over 5 h. DFT calculations indicate that the Ir@Co (Ir) sites can accelerate the OER, while the Ir@NC₃ sites are responsible for the enhanced HER, clarifying the unprecedented performance of this bifunctional catalyst towards full water splitting.     

Characteristics of a dual‐radio‐frequency cylindrical inductively coupled plasma

The plasma parameters such as electron density, effective electron temperature, plasma potential, and uniformity are investigated in a new dual‐frequency cylindrical inductively coupled plasma (ICP) source operating at two frequencies (2 and 13.56 MHz) and two antennas (a two‐turn high‐frequency antenna and a six‐turn low‐frequency (LF) antenna). It is found that the electron density increases with 2 MHz power, whereas the electron temperature and plasma potential decrease with 2 MHz power at a fixed 13.56 MHz power. Moreover, the plasma uniformity can be improved by adjusting the LF power. These results indicate that a dual‐frequency synergistic discharge in a cylindrical ICP can produce a high‐density, low‐potential, low‐effective‐electron‐temperature, and uniform plasma.     

Development of a syn‐Selective Mannich Reaction of Aldehydes with Propargylic Imines by Dual Catalysis: Asymmetric Synthesis of Functionalized Propargylic Amines

Direct coupling of enolizable aldehydes with C‐alkynyl imines is realized affording the corresponding propargylic Mannich adducts of syn configuration, thus complementing previous methods that gave access to the anti‐isomers. The combination of proline and a urea Brønsted base cocatalyst is key for the reactions to proceed under very mild conditions (3–10 mol % catalyst loading, dichloromethane as solvent, ?20 °C, 1.2 molar equivalents of aldehyde) and with virtually total stereocontrol (syn/anti ratio up to 99:1; ee up to 99 %). Some possibilities of further chemical elaboration of adducts are also briefly illustrated.     

Dual‐signal amplification strategy for ultrasensitive chemiluminescence detection of PDGF–BB in capillary electrophoresis

Many efforts have been made toward the achievement of high sensitivity in capillary electrophoresis coupled with chemiluminescence detection (CE‐CL). This work describes a novel dual‐signal amplification strategy for highly specific and ultrasensitive CL detection of human platelet‐derived growth factor–BB (PDGF–BB) using both aptamer and horseradish peroxidase (HRP) modified gold nanoparticles (HRP–AuNPs–aptamer) as nanoprobes in CE. Both AuNPs and HRP in the nanoprobes could amplify the CL signals in the luminol–H₂O₂ CL system, owing to the excellent catalytic behavior of AuNPs and HRP in the CL system. Meanwhile, the high affinity of aptamer modified on the AuNPs allows detection with high specificity. As proof‐of‐concept, the proposed method was employed to quantify the concentration of PDGF–BB from 0.50 to 250 fm with a detection limit of 0.21 fm. The applicability of the assay was further demonstrated in the analysis of PDGF–BB in human serum samples with acceptable accuracy and reliability. The result of this study exhibits distinct advantages, such as high sensitivity, good specificity, simplicity, and very small sample consumption. The good performances of the proposed strategy provide a powerful avenue for ultrasensitive detection of rare proteins in biological sample, showing great promise in biochemical analysis. Copyright © 2015 John Wiley & Sons, Ltd.