基于小波变换的图像文字水印方案

【摘 要】 : 数字水印是一种新的有效的数字产品版权保护和数据安全维护的技术, 它是一种十分贴近实际应用的信息 隐藏技术。小波变换因其良好的空频特性, 及与图象编码标准 JPEG2000 的兼容性, 使得小波域水印更具鲁棒性, 以及更大的 嵌入容量。因此基于小波变换的数字水印技术成为当前的一个研究热点。本文介绍了一种小波变换域在静态图像上嵌入文 字水印的方案, 实验表明, 该方法是可行的

Iron and manganese oxides enhance electron output efficiency of Clostridium pasteurianum

[Background] Fermentative dissimilatory metal-reducing bacteria, which are capable of reducing metallic oxides, get energy from fermentation. Little is known about how metallic oxides affect electron output efficiency of fermentative dissimilatory metal-reducing microorganisms. [Objective] This study was conducted to explore the influence of iron and manganese oxides (Fe_2O_3/MNO_2) on electron output efficiency. [Methods] Different concentrations of Fe_2O_3/MNO_2 were added into fermented system containing glucose and inoculated 5% C. pasteurianum. Electrochemical activity of C. pasteurianum was detected. The concentrations of Fe(Ⅱ) and Mn(Ⅱ) were measured by ferrozine spectrophotometry and formaldoxime method. Fermentation substrate and metabolites of C. pasteurianum were detected by gas chromatography and high performance liquid chromatography. Lastly, we calculated the electron output efficiency. [Results] The current density peaked with the value of about 0.93 mA/m~2. The concentrations of Fe(Ⅱ) and Mn(Ⅱ) gradually accumulated. The consumption of glucose was increased by 9.4%/7.7%, Meanwhile, acetate production was increased by 37.5%/25.0%, and butyrate production was increased by 22.7%/6.8%. Additionally, hydrogen production was increased by 21.6%/9.8%, and the total electron output efficiency was increased by 24.27%/10.82%, respectively. The pH values between experimental group and control are no significant difference. [Conclusion] This study shows that iron and manganese oxides can improve the electron output efficiency of C. pasteurianum by increasing glucose consumption and buffering pH value. The results provide evidence for revealing the effects of multivalent metal oxides on the electron output of fermentative dissimilatory metal-reducing bacteria, and further expand our understanding of the interaction mechanism between multivalent metal oxides and fermentative dissimilatory metal-reducing bacteria.</p

A SVPWM Overmodulation Method Based on Three-Phase Bridge Arm Coordinates

讨论了一种新型的SVPWM过调制方法,并对其过调制性能及谐波成分进行了分析。首先,对经典SVPWM技术进行了分析,探讨了常规过调制策略的实质。其次,引入了新的三相桥臂坐标,在该坐标下将现有的SVPWM的串行合成时间关系推导为并行。最后,给出了线性调制和过调制统一的求解模型,避免了现有过调制算法中控制角和保持角的计算。新方法取消了扇区的概念并简化了计算,可实现从线性调制到六阶梯模式的连续平滑调制。文中介绍了该过调制算法的基本原理,进行了仿真和实验。结果表明,该方法在线性调制和六阶梯模式下调制效果与经典SVPWM方法相当;而过调制区,其输出PWM波形的THd明显小于常规过调制方法。A new overmodulation method based on space vector pulse width modulation(SVPWM) is discussed, and the performance and harmonic components of which are also analyzed.Firstly, the essence of original overmodulation strategy in the classical SVPWM is investigated.Then, a three-phase-bridge-arm coordination is introduced in which the relationship between three up-bridge arm working situations is parallel.Finally, a unified solution of linear modulation and overmodulation is proposed, to avoid the calculation of the reference angle and holding angle in existing strategies.The new method cancels traditional sector division, simplifies the computation, and gives smooth transitions from linear modulation, overmodulation, to six-step operation finally.The overmodulation strategy is theoretically analyzed, simulated and experimented.The results demonstrate that the PWM wave generated by the new method is similar to the classic, and the total harmonic distortion(THD) of the output voltage is markedly reduced.国家自然科学基金(51177141); 福建省自然科学基金(2010J01310); 中央高校基本科研(0620ZK1007)资助项

武夷山市洲庵遗址考古发掘简报

洲庵遗址位于福建省城村汉城遗址西南2公里处,2013年被调查发现。随后对其进行抢救性考古发掘,共发现汉代房址1处,宋代灰坑6个、窑炉3座,出土一批汉代、宋代建筑材料、陶瓷器标本,这为研究..

Expression and test of the neutralization Fab antibody against infectious bursal disease virus

为表达抗鸡传染性法氏囊病病毒(IbdV)抗体fAb并检测其中和活性,本研究将抗IbdV抗体的轻链(l)和重链片段(fd)基因分别克隆于P ET-27b(+)载体中,并转化于大肠杆菌rOSETTA(dE3)进行诱导表达。将l和fd片段包涵体蛋白变性后等量混合于复性液中,制备fAb并对其进行活性鉴定。结果显示l和fd蛋白相对分子质量大小分别为25 ku和28 ku。WESTErn blOT和ElISA检测结果表明,获得的抗体fAb大小约为50 ku,并且与VP2蛋白和不同病毒株均具有特异性结合能力。体外中和试验结果表明,获得的IbdV抗体fAb具有中和活性,可以有效阻断IbdV(b87株)对鸡胚成纤维细胞(df1)的感染。本实验获得的IbdV抗体fAb有望成为治疗Ibd的候选生物制剂,为研制治疗Ibd抗体制剂奠定了基础。To express the neutralizing Fab antibody against infectious bursal disease virus(IBDV),the gene of light chain(L)or heavy chain fragment(Fd) against IBDV was cloned into the prokaryotic expression plasmid,respectively,and then the recombinant L or Fd was expressed in E.coli Rosetta(DE3),respectively,and purified through sole denaturation and co-renaturation of inclusion body.Western blot results showed that the Fab was approximately 50 ku.ELISA results showed that the Fab exhibited binding ability and specify to VP2 for different IBDV strains.The results of neutralization test in vitro showed that the Fab exhibited neutralizing activity to IBDV-B87 strainin chicken embryo fibroblast(DF1) cells.The Fab antibody prepared in this study is expected to become a candidate drug for treatment of IBD,which laid the foundation for the treatment of IBD.黑龙江省应用技术研究与开发计划项目(GC13C104

Promoting electrocatalytic CO2 reduction to formate via sulfur-boosting water activation on indium surfaces

一般认为，H2O还原析氢反应是CO2还原反应的竞争反应，若促进H2O活化将降低CO2还原反应的法拉第效率。因此，基于该认识设计出的高CO2还原法拉第效率的催化剂常常活性低。王野课题组打破这种认识，提出H2O分子活化在CO2还原中起着重要的作用，成功合成出硫修饰In催化剂来活化H2O分子而促进CO2还原制甲酸的新方法，该催化剂在非常宽的电流密度范围内（25~100 mA cm-2），均可以维持85%以上的甲酸法拉第效率。将硫拓展至硒和碲等其它硫族元素以及将金属铟拓展至铋和锡等其它p区金属，均实现很好的促进效果，表明通过促进水的活化来提高CO2电催化还原性能具有普适性。该工作为理性设计高效的CO2还原电催化剂提供了新策略。 该研究工作实验部分主要由王野、张庆红教授指导，能源材料化学协同创新中心iChEM2016级博士生马文超、固体表面物理化学国家重点实验室高级工程师谢顺吉（共同第一作者）完成；理论计算部分由吴德印教授指导，2015级博士生张霞光（共同第一作者）完成。醇醚酯国家工程实验室高级工程师康金灿参与了部分实验表征。上海光源姜政教授和孙凡飞博士为同步辐射表征提供了支持。【Abstract】Electrocatalytic reduction of CO2 to fuels and chemicals is one of the most attractive routes for CO2 utilization. Current catalysts suffer from low faradaic efficiency of a CO2-reduction product at high current density (or reaction rate). Here, we report that a sulfur-doped indium catalyst exhibits high faradaic efficiency of formate (>85%) in a broad range of current density (25–100 mA cm−2) for electrocatalytic CO2 reduction in aqueous media. The formation rate of formate reaches 1449 μmol h−1 cm−2 with 93% faradaic efficiency, the highest value reported to date. Our studies suggest that sulfur accelerates CO2 reduction by a unique mechanism. Sulfur enhances the activation of water, forming hydrogen species that can readily react with CO2 to produce formate. The promoting effect of chalcogen modifiers can be extended to other metal catalysts. This work offers a simple and useful strategy for designing both active and selective electrocatalysts for CO2This work was supported by the National Key Research and Development Program of the Ministry of Science and Technology of China (No. 2017YFB0602201), the National Natural Science Foundation of China (Nos. 21690082, 91545203, and 21503176). We thank staff at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facilities (SSRF) for assistance with the EXAFS measurements. 研究工作得到科技部重点研发计划（批准号：2017YFB0602201）和国家自然科学基金（批准号：21690082、91545203、21503176）等项目的资助

In situ Raman spectroscopic evidence for oxygen reduction reaction intermediates at platinum single crystal surfaces

铂基催化剂表面的氧还原反应（ORR）是燃料电池重最重要的阴极反应。虽然经过几十年的研究，ORR的具体反应路径并没有真正解析清楚。在本研究中，李剑锋教授课题组首次利用其发展的电化学壳层隔绝纳米粒子增强拉曼光谱（SHINERS）技术原位研究了Pt(hkl)单晶表面的ORR反应过程，成功捕获到在1150 cm-1、1080 cm-1和732 cm-1区域O2-、OH*和HO2*等重要反应中间物种的直接拉曼光谱证据，并通过相应的同位素取代实验（氘和O-18同位素实验）及DFT理论模拟确认了中间物种的谱峰归属和吸附构型。总的来说，该项研究首次在Pt(hkl)单晶表面原位获得ORR反应重要中间物种的直接拉曼光谱证据，提出合理的ORR反应路径，加深了人们对ORR反应机理的认识，也为其他界面催化反应机理的研究提供了一条可行的研究思路。 该研究工作由校内外多个课题组共同努力完成，化学化工学院李剑锋教授课题组负责相关电化学原位拉曼光谱实验，Alicante大学Juan Feliu教授课题组负责单晶电化学实验，化学化工学院吴德印教授课题组负责DFT理论模拟，物理系杨志林教授课题组负责3D-FDTD的理论模拟。该研究工作的第一作者董金超和第二作者张霞光分别为化学化工学院2014级博士生（已毕业）和2015级博士生。【Abstract】Developing an understanding of structure-activity relationships and reaction mechanisms of catalytic processes is critical to the successful design of highly efficient catalysts. As a fundamental reaction in fuel cells, elucidation of the oxygen reduction reaction (ORR) mechanism at Pt(hkl) surfaces has remained a significant challenge for researchers. Here, we employ in situ electrochemical surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) calculation techniques to examine the ORR process at Pt(hkl) surfaces. Direct spectroscopic evidences for ORR intermediates indicates that under acid conditions, the pathway of ORR at Pt(111) occurs through the formation of HO2, while at Pt(110) and Pt(100) it occurs via the generation of OH*. However, we propose that the pathway of ORR under alkaline conditions at Pt(hkl) surfaces mainly occurs through the formation of O2- . Significantly, these results demonstrate that the SERS technique offers an effective and reliable way for real-time investigation of catalytic processes at atomically flat surfaces.This work was supported by the NSFC (21522508, 21427813, 21521004, 21533006, 21621091,and 21775127), "111" Project (B16029 and B17027), Natural Science Foundation of Guangdong Province (2016A030308012), the Fundamental Research Funds for the Central Universities (20720180037), and the Thousand Youth Talents Plan of China. Support from MINECO and Generalitat Valenciana (Spain), through projects CTQ2016-76221-P (AEI/FEDER, UE) and PROMETEOII/2014/013 respectively, is greatly acknowledged. V.B.M thankfully acknowledges to MINECO the award of a pre-doctoral grant (BES-2014-068176, project CTQ2013-44803-P). 该研究工作得到国家自然科学基金委（21522508、21427813、21521004、21533006、21621091和21775127）的大力资助和支持。化学化工学院周志有教授、程俊教授，材料学院张华副教授，英国利物浦大学Gary Attard教授，以及化学化工学院苏敏、王耀辉、卢邦安等博士生和杨晓冬博士对本课题的研究给予了大力的支持和帮助

3D-printed integrative probeheads for magnetic resonance

射频探头前端作为核磁共振设备的核心部件之一，极大程度的决定着系统实验性能的优劣。探头前端通常由射频线圈、射频电路及样品检测管道等部分组成。现有的射频线圈制作技术主要是通过手工或机械手段按照所需的线圈形状进行绕制。但是，当线圈结构较为复杂、不规则，或体积尺寸较小时，常规绕制方法便难以满足结构设计和制造的精度需求，因此造成线圈性能的劣化，增大检测区域的射频场不均匀性，对核磁共振检测产生负面影响。本研究中，利用3D打印熔融沉积制造或光敏树脂选择性固化技术精确加工出一体化磁共振探头前端，使用常温液态金属填充线圈模型管路形成射频线圈，搭建出稳定的一体化磁共振射频探头。利用高精度3D打印和液态金属灌注技术制备出包含有射频线圈和定制化样品管道结构在内的一体化磁共振射频探头前端，克服了传统磁共振三维微型线圈成型困难、与样品腔匹配程度差等问题，提高了探头的信噪比，为定制化的磁共振检测提供了新思路。 该工作由厦门大学电子科学与技术学院陈忠教授、游学秋副研究员和孙惠军高级工程师共同指导完成，博士研究生谢君尧为论文第一作者。厦门大学电子科学与技术学院黄玉清高级工程师、王忻昌副教授、倪祖荣助理教授、硕士研究生张德超，化学化工学院杨朝勇教授、博士研究生李星锐，萨本栋微米纳米科学技术研究院陈宏教授为合作作者。【Abstract】Magnetic resonance (MR) technology has been widely employed in scientific research, clinical diagnosis and geological survey. However, the fabrication of MR radio frequency probeheads still face difficulties in integration, customization and miniaturization. Here, we utilized 3D printing and liquid metal filling techniques to fabricate integrative radio frequency probeheads for MR experiments. The 3D-printed probehead with micrometer precision generally consists of liquid metal coils, customized sample chambers and radio frequency circuit interfaces. We screened different 3D printing materials and optimized the liquid metals by incorporating metal microparticles. The 3D-printed probeheads are capable of performing both routine and nonconventional MR experiments, including in situ electrochemical analysis, in situ reaction monitoring with continues-flow paramagnetic particles and ions separation, and small-sample MR imaging. Due to the flexibility and accuracy of 3D printing techniques, we can accurately obtain complicated coil geometries at the micrometer scale, shortening the fabrication timescale and extending the application scenarios.The work is supported by the National Natural Science Foundation of China (Grants U1632274, 11761141010, U1805261, 11475142, 22073078, and 61801411), and China Postdoctoral Science Foundation (2017M622075).研究工作得到国家自然科学基金、中国博士后科学基金等项目支持