声子玻璃三维建模研究

声子玻璃是一种基于网络化局域共振机制的新型水下吸声材料,不仅可以在宽频(12kHz-30kHz)范围内对声波进行有效的强吸收,同时还具备良好的抗压能力。本文利用有限元方法,建立了三维隐函数模型。该模型能够描述声子玻璃的吸声机理与宽频强吸声性能,计算结果与实验结果相符,可以用来研究各个因素对声子玻璃吸声性能的影响以及它的吸声机理,可以为实验中组分材料的选择及性能优化提供理论支撑

泡沫金属对声子玻璃吸声性能的影响研究

水下吸声材料需要在宽频范围内实现对声波的强吸收性质,文章通过考虑材料的粘弹性时,在局域共振声子晶体中引入互穿网络结构来制备一种新型的小尺度水下宽频强吸声材料——声子玻璃(Phononic glass)。泡沫金属是声子玻璃的组分材料之一,研究其对声子玻璃吸声性能的影响有着重要意义。文中利用均一孔径的泡沫铜制备了一种声子玻璃,利用有限元方法对该声子玻璃的声共振频带进行估算,并将实验结果与泡沫铝基声子玻璃进行了对比。结果表明基于均一孔径泡沫金属的声子玻璃不具有宽频效应,当金属部分的质量增大时,声子玻璃共振吸声频带向低频移动,与计算结果一致

莱州湾-龙口湾表层沉积物有机质特征及来源分析

通过对莱州湾-龙口湾表层沉积物样品中总有机碳(TOC)、总氮(TN)、有机碳与总氮的比值(C/N)、稳定碳氮同位素(δ13C、δ15N)生物地球化学指标的测定,分析了该区域沉积物中有机质的特征和来源.结果显示,莱州湾表层沉积物中TOC含量为0.47%±0.40%,龙口湾TOC含量为0.82%±0.37%,TN含量相差不大,因此龙口湾沉积物有机质相对含量高于莱州湾.港口的建设使龙口湾内水体流速减慢,加上龙口湾入海河流较少,使得龙口湾沉积物平均粒径(19.40μm)远低于莱州湾(43.89μm),比较容易吸附有机质.莱州湾沉积物中δ13C值为-24.96‰—21.46‰,平均值为-23.63‰;龙口湾表层沉积物中δ13C值为-23.02‰—22.39‰,平均值为-22.73‰.由此看来,莱州湾沉积物中有机质主要来源于陆生C3植物和藻类,而龙口湾有机质大部分来源于藻类,少数来自陆生C3植物.根据经典的二元模式计算,龙口湾陆源有机质的贡献比例范围为23.15%—33.67%,平均值为28.84%,莱州湾陆源贡献比例范围为7.65%—65.97%,平均值为43.75%.莱州湾沿岸有众多河流入海,尤其是含沙量最多的黄河,给湾内带来大量的陆上有机质,而龙口湾入海河流较少,沉积物中的陆上有机质较少.&nbsp

Preparation of Pt/H-TiO_2 Catalyst with Improved Catalytic Performance for Methanol Electrooxidation

以四氯化钛为前驱体,采用水热法合成二氧化钛纳米棒(TIO2,白色),在纯H2气氛,将其550OC热处理2H,即得有氧缺陷和TI3+填隙原子的二氧化钛纳米棒(H-TIO2,灰黑色).将PT纳米粒子(~1.9 nM)负载于此两种二氧化钛纳米棒上,制得PT/TIO2和PT/H-TIO2催化剂.Xrd和XPS测试表明,氢处理TIO2晶型没有变化,仍属金红石型,但增加了TI-OH表面物种.电化学测试表明,H-TIO2载体能够增强氧在PT表面的吸脱附能力,从而提高其甲醇电催化氧化活性,PT/H-TIO2电极甲醇氧化峰电流密度为PT/TIO2电极的1.6倍、PT/C电极的2.1倍.White TiO2 nanorods were synthesized by hydrothermal method with TiCl4 as a precursor.As-synthesized TiO2 nanorods were further subjected to high-temperature(550oC) heat treatment for 2 h under H2atmosphere to prepare gray black hydrogen-treated TiO2(H-TiO2) nanorods with oxygen vacancies and Ti3+interstitial atoms.The Pt nanoparticles of 1.9 nm were supported on these two types of TiO2nanorods to form Pt/TiO2and Pt/H-TiO2catalysts.XRD data indicates that the crystal structure of TiO2was still reserved as rutile after hydrogen treatment,but the surface was covered by some Ti-OH species,as evidenced by XPS test.Electrochemical tests demonstrate that the oxygen vacancies of H-TiO2can enhance the adsorption/desorption of oxygen on Pt nanoparticles,which promotes the electrocatalytic activity of H-TiO2towards methanol oxidation.As a result,the peak current density of methanol oxidation on Pt/H-TiO2was 1.6 and 2.1 times those of methanol oxidation on Pt/TiO2and Pt/C,respectively.国家自然科学基金项目(No.20933004)资

Characteristics and sources of organic matter in surface sediments of Laizhou Bay and Longkou Bay

通过对莱州湾-龙口湾表层沉积物样品中总有机碳(TOC)、总氮(TN)、有机碳与总氮的比值(C/N)、稳定碳氮同位素(δ13C、δ15N)生物地球化学指标的测定,分析了该区域沉积物中有机质的特征和来源.结果显示,莱州湾表层沉积物中TOC含量为0.47%±0.40%,龙口湾TOC含量为0.82%±0.37%,TN含量相差不大,因此龙口湾沉积物有机质相对含量高于莱州湾.港口的建设使龙口湾内水体流速减慢,加上龙口湾入海河流较少,使得龙口湾沉积物平均粒径(19.40μm)远低于莱州湾(43.89μm),比较容易吸附有机质.莱州湾沉积物中δ13C值为-24.96‰—21.46‰,平均值为-23.63‰;龙口湾表层沉积物中δ13C值为-23.02‰—22.39‰,平均值为-22.73‰.由此看来,莱州湾沉积物中有机质主要来源于陆生C3植物和藻类,而龙口湾有机质大部分来源于藻类,少数来自陆生C3植物.根据经典的二元模式计算,龙口湾陆源有机质的贡献比例范围为23.15%—33.67%,平均值为28.84%,莱州湾陆源贡献比例范围为7.65%—65.97%,平均值为43.75%.莱州湾沿岸有众多河流入海,尤其是含沙量最多的黄河,给湾内带来大量的陆上有机质,而龙口湾入海河流较少,沉积物中的陆上有机质较少.&nbsp

Preparation of Pt/H-TiO2 Catalyst with Improved Catalytic Performance for Methanol Electrooxidation

以四氯化钛为前驱体，采用水热法合成二氧化钛纳米棒（TiO2，白色），在纯H2气氛，将其550 oC热处理2 h，即得有氧缺陷和Ti3+填隙原子的二氧化钛纳米棒（H-TiO2，灰黑色）. 将Pt纳米粒子（~ 1.9 nm）负载于此两种二氧化钛纳米棒上，制得Pt/TiO2和Pt/H-TiO2催化剂. XRD和XPS测试表明，氢处理TiO2晶型没有变化，仍属金红石型，但增加了Ti-OH表面物种. 电化学测试表明，H-TiO2载体能够增强氧在Pt表面的吸脱附能力，从而提高其甲醇电催化氧化活性，Pt/H-TiO2电极甲醇氧化峰电流密度为Pt/TiO2电极的1.6倍、Pt/C电极的2.1倍.White TiO2 nanorods were synthesized by hydrothermal method with TiCl4 as a precursor. As-synthesized TiO2 nanorods were further subjected to high-temperature (550 oC) heat treatment for 2 h under H2 atmosphere to prepare gray black hydrogen-treated TiO2 (H-TiO2) nanorods with oxygen vacancies and Ti3+ interstitial atoms. The Pt nanoparticles of 1.9 nm were supported on these two types of TiO2 nanorods to form Pt/TiO2 and Pt/H-TiO2 catalysts. XRD data indicates that the crystal structure of TiO2 was still reserved as rutile after hydrogen treatment, but the surface was covered by some Ti-OH species, as evidenced by XPS test. Electrochemical tests demonstrate that the oxygen vacancies of H-TiO2 can enhance the adsorption/desorption of oxygen on Pt nanoparticles, which promotes the electrocatalytic activity of H-TiO2 towards methanol oxidation. As a result, the peak current density of methanol oxidation on Pt/H-TiO2 was 1.6 and 2.1 times those of methanol oxidation on Pt/TiO2 and Pt/C, respectively.国家自然科学基金项目（No. 20933004）资助作者联系地址：1. 厦门大学 固体表面物理化学国家重点实验室，化学化工学院化学系，福建 厦门 361005；2. 华东理工大学化学工程国家重点实验室，上海 200237Author's Address: 1. State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China; 2. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China通讯作者E-mail：[email protected]

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies