2023年机械英语专业论文及翻译 机械英语论文及翻译字左右(大全4篇)

机械英语专业论文及翻译 机械英语论文及翻译字左右篇二

外文文献翻译

（2013届）

译文一：特殊工艺抛光机床的研究

学生姓名

祝彬彬

学

号

09143333

院

系

工学院机电系

专

业

机械设计制造及其自动化

指导教师

娄建国

完成日期

2013-03-01

特殊工艺抛光机床的研究

research on polishing process of a special

polishing machine tool guilian wang1,2 and yiqiang wang1 1college of mechanical engineering, jilin university, changchun, china 2college of mechanical engineering, jiamusi university, jiamusi, china

介绍

抛光是一个重要的模具加工过程。其目的是为了去除轻微划痕，降低工件表面粗糙度。据报道，技术工人完成制作模型和模型上的工作所花总时间的37%到50%中使用的都是传统的技术。由于现代工业加工过程需要更高的精度和生产效率，自动化和优化生产过程成为了日益增加的重要任务。因此，高效率抛光加工和精加工技术在很长一段时间里都是很理想的，这也提高了劳动生产率，降低了劳动强度。

许多用于模具抛光的自动抛光机使用的组合磨料被调查了。ahn等人开发了拥有智能抛光系统的五轴抛光机床，并对气动抛光头和抛光条件，比如压力、进给量和刀具库进行了调整，使用此智能监控，可以可以实现更快更好的表面加工。wu等人研究了一个新的使用弹性球形轮的抛光磨削中心在自由曲面上加工的技术。这项技术仅删除尖的高度，适用于切割过程中切割位点的保证，有效地保持了切割生产过程中的形状精度。furukawa等人研究了一种通过使用安装在机器人手腕上合适的被动末端执行器的自动抛光系统。该系统用于抛光一个未知的三维表面。

tsai和huang提出了一种由五轴机器人和力量控制机制组成的自动模具抛光系统，并制定了有效地自动抛光工艺和新标准磨具。liao等人通过使用扩展检测工具整合的压力传感器制定了一个兼容抛光和去毛刺双重用途的工具头，并且在打磨面积上所有的的抛光动作都可以沿着工件的几何形状改变曲率。目前，许多抛光设备大多数基于传统机床和工业机器人。对于精处理系统组成的工业机器人，可以稳定的完成对力量和位置的控制。

然而，它对的自由面精加工是相对困难的，比如由计算机数字控制机器加工 的自由面，因为其轨迹误差较大。由于多样化和模具表面的不规则性，抛光工具在加工过程中必须根据工件表面形状改变运动轨迹。此外，对自由曲面的抛光要求对抛光力精确控制和高的加工稳定性，可有效完成工件表面材料的均匀去除。所以开发一种特殊的抛光设备是有意义且必须的。

20世纪80年代以来，许多研究者制定了并联机制。近几年，并联机构在工业上去的了广泛的应用。并联机床是基于并行机制并结合了机床、机器人和数控技术的新一代机械加工设备，比如并行铣床，钻床。并联机床拥有高刚度重量比、高响应率、高环境适应技术和高附加价值等特殊性能。

由于电动机可以安装在底座上，从而减轻了重量，并联机器人的速度通常比普通的关节机器人快。它们比串行机器人也更强，因为终端控制器可以有更多的链接。另一个好处是，相比串行机器人将误差平均，终端控制器的错误更少。但是大多数时候并联机器人的的工作空间有限，例如它们通常不能绕过障碍到达目的地。在执行中涉及的计算所需的操作通常也很难，并且有不止一个的唯一解决方案。

串联机器人拥有更大的工作空间和良好的灵活性等优势。这些都是并联机床的缺点，所以将两者的配置进行组合已经被开发，它可以拥有双方的综合效益。自由曲面抛光可以通过使用这个五自由度串并联抛光工具实现。

在这项研究中，一种基于弹性抛光原理的新型串并联混合动力专用抛光机被开发出来，使用限制的磨料，它可以用于抛光模具表面。此弹性抛光工具系统可以通过气压伺服系统进行主动控制，由弹簧实现被动整合，并且统一的材料去除可以通过对切削力和依据姿态角检测的旋转速度的实时控制来达到。对表面粗糙度和抛光效率有影响的主要工艺参数被调查收集并通过抛光实验进行分析。taguchi通过自己和相关的分析报告得到优化过程的参数

串并联混合抛光机床

图一是串并联混合抛光机床照片（jdyp51型），图二是本机床结构示意图。本机床主要由并联机构三维运动平台和一系列两自由度旋转机制组成。并联机构由一个等边三角形的移动平台、三个立柱、三个鞍座，以及三个等长的通过组合的hooke接头连接移动平台和鞍座的支架组成。鞍座被伺服电机和滚珠丝杠推动。并联机构控制抛光工具的空间位置。转动关节由一个可以提供一个自由度的转动副组成。该串联机械设备有两个转动关节，使它们分别绕过水平轴和垂直轴成为可能。串联机械结构控制抛光工具的姿态

图一：串并联混合抛光jdyp51型机床

据指出，许多弹性抛光工具和灵活的磨具被进行了调查，其目的是为了实抛光加工过程中的主动控制和被动协调。弹性抛光的定义是这工具系统使用弹性磨具，比如橡胶粘合剂或者树脂结合剂，根据工件表面形状它们都是可被控制的，并且工艺参数也被调整以实现统一性的材料去除和良好的表面质量。这项研究中的最终执行机构的结构图框如图三所示。从图三可以看出，该抛光工具由主轴电机驱动，而抛光力则通过调整气动伺服系统的汽缸压力来控制；同时被动协调工件表面形状的机构是一个弹簧。统一性的材料去除可以通过对抛光力合旋转速度的实时控制来实现。抛光工具和工件的位置关系在图四，如下：

fn=fs cosα（1）vs=nrsinα（2）

其中fs是汽缸轴的轴向力，fn是由抛光工具作用在工件表面正方向的力，vs是抛光工具在其与工件表面接触区域的线速度，n是工具的旋转速度，r是工具半径，α是定义为外曲面法线和工具杆轴方向的的夹角。

通过虚拟轴混合机床与抛光工具系统的结合，本机床拥有两个平衡部件和串联部件，所以它有快速反应、短传播链和高环境适应力的优势，它可以提供任何方向的运动非常适合抛光自由曲面。yu等人研究了这个由灵活的多体系统动力学原理研制的混联机床的动态特性。除了运动的开始时间，在抛光运动的各个时 期机器可以保持稳定的状态。此外，本机床使用的cnc系统是自主开发的基于pmac（可编程多轴控制器）的并行双cpu系统。后台管理和人机界面都是由工业pc实时控制，如六轴运动控制和逻辑i/o信号控制都是基于pmac的。

图二：串并联混合抛光机床结构示意图 1.柱2.鞍座3.支架4.运动平台5.系列机械结构 6.抛光工具7.工件8.静平台

图三：抛光机末端执行器 1.伺服电机2.汽缸连接接头3.汽缸4.调心轴承5.马达缸6.弹簧7.导柱8.耦合器9.钳10.主轴

图四：抛光工具和工件的位置关系图

结论：

在这项研究中，基于弹性抛光原理的串并联混合混合抛光机床已经发展成熟，并且进行了一些以分析抛光过程为目的的平面加工实验。本文的重点是其应用。通过研究工艺参数对表面特性和抛光效率的影响，可以得到加工参数的最佳组合。主要结论归纳如下：

1.包含并行机制的三维移动平台和串联的两自由度旋转机构的串并联混合机床，可以为抛光工具提供五自由度的运动。并联机构控制抛光工具的空间位置，串联机构控制抛光工具的姿态。弹性抛光工具系统可以借由气动伺服控制系统实现主动控制，由弹簧实现被动协调。统一性的材料去除可以由对切削力和根据姿态角来计算的旋转速度的实时控制来实现。

2.经过抛光实验证明刀具转速、进给速度、切削力和姿态角这些是对抛光效率和表面粗糙度影响很打的主要工艺参数。增加刀具转速和抛光次数，进给速度和姿态角可以降低表面粗糙度。切削力增加，表面粗糙度降低，但是切削力过大会适得其反。抛光效率随刀具转速和进给速度的增加而增加，随姿态角和抛光次数的增加而减小。切削力增加可以提高抛光效率，但是过大的切削力会减小效率。3.在本文所给出的条件下，最低表面粗糙度的最佳工艺参数组合为：工具转速1200r/min，进给速度0.2m/min，切削力30n，姿态角30º，抛光次数6次；在保证良好的表面粗糙度的前提下提高抛光效率的最佳工艺参数组合为：工具转速1200r/min，进给速度0.6m/min，切削力30n，姿态角30º，抛光次数2次。这些结果为在自由表面抛光加工实践中选择最佳工艺参数提供了依据。

参考文献

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机械英语专业论文及翻译 机械英语论文及翻译字左右篇三

专做机械类毕业设计，可代画cad、proe图 有需要可联系q q3590003551、calypso2、calypso13、holonic生产系统的产品设计

4、标准化在塑料注射模具初始化设计中的应用

5、不规则制造系统的动态代理人模型和说明书

6、常规压力对采用非牛顿学流体润滑的光滑碟片表面的作用

7、超精密加工与超高速加工技术

8、车床及其切削加工

9、车削、铣削和磨削

10、冲压变形

11、淬硬齿轮的加工

12、刀具成本的检测

13、对振动侦查和测量的一种实用方法-物理原则和侦查技术

14、发展“机电一体化”的思路和对策

15、反求工程

16、非开挖技术在电力工程中的应用

17、废旧轮胎资源综合利用技术

18、分析一组协作移动机械手

19、高速切削加工在模具制造中的应用

20、机床实践

21、机器人传感器的网络

22、机器人技术发展趋势

23、机器人介绍

24、机械加工表面质量

25、机械零件的强度和计算机与制造业

26、机械零配件中圆柱表面的智能定位

27、机械设计基础

28、基于代理的模型为处理综合产品信息

29、基于快速原形制造的综合应用

30、基于快速原型的综合制造

31、基于事例推理的夹具设计研究与应用

32、基于网络的快速原型制造

33、计算机辅助过程规划管理信息基础薄板

34、浇铸钛和金的显微结构和机械性能

35、快速成型技术和系统的回顾

36、快速原形机的软件补偿

37、快速原型技术及在模具制造中的应用

38、宽槽圆柱凸轮数控加工技术的研究

39、蜡模精确成型在浇注中的实验性研究

40、冷锻技术的发展现状与趋势

41、利用三坐标测量仪确定聚苯乙烯材料表面形态

42、模具快速制造技术的发展方向

43、破碎粉磨设备的磨损与耐磨材料的发展

44、汽车零件加工中的环保技术

45、切削侧表面刀具的磨损高速干切削

46、认识曲柄摇臂机构设计的最优传动方法

47、柔性制造系统

48、润滑和摩擦学在海水水力活塞泵中的应用

49、生产胶粉—废旧轮胎回收利用的方向

50、事例研究—反求工程零部件的远程制造

51、数控技术和装备发展趋势及对策

52、数控技术和装备发展趋势及对策153、数字控制

54、铁金属及其合金

55、先进制造技术的新发展

56、现代集成制造技术

57、现代集成制造系统的技术构成及发展策略研究

58、现代制造业中计算机的应用

59、虚拟制造的机械加工过程仿真

60、虚拟制造技术及其应用

61、选域激光熔解法在钛模快速原型加工中的作用

62、研磨机的最佳优化设计

63引线键合的现状与发展趋势

64、影响切割工艺的材料属性的总体

65、在干和湿的高速加工环境下表面涂上碳化物和不涂碳化物对产品生命周期的影响

66、在干燥和潮湿的条件下研究高速切削的费用以及便于机械制造过程的优化

67、在高速潮湿机械加工条件下后刀面表层磨损机理

68、在高速干加工条件下含有tialn涂层的插入物磨损机理的实验性观察

69、制造业为产品设计花费模型

机械英语专业论文及翻译 机械英语论文及翻译字左右篇四

a smart copper(ii)-responsive binucleargadolinium(iii)complex-based magnetic resonanceimaging contrast agent†

yan-meng xiao,ab gui-yan zhao,ab xin-xiu fang,ab yong-xia zhao,ab guan-hua wang,c wei yang*a and jing-wei xu*a a novel gd-do3a-type bismacrocyclic complex, [gd2(do3a)2bmpna], with a cu2+-selective binding unitwas synthesized as a potential “smart” copper(ii)-responsive magnetic resonance imaging(mri)contrast relaxivity of the complex was modulated by the presence or absence of cu2+;in the absence of cu2+, the complex exhibited a relatively low relaxivity value(6.40 mm1 s1), while the addition of cu2+ triggered an approximately 76% enhancement in relaxivity(11.28 mm1 s1).moreover, this cu2+-responsive contrast agent was highly selective in its response to cu2+ over other biologically-relevant metal influence of some common biological anions on the cu2+-responsive contrast agent and the luminescence lifetime of the complex were also results of the luminescence lifetime measurements indicated that the enhancement in relaxivity was mainly ascribed to the increased number of inner-sphere water molecules binding to the paramagnetic gd3+ core upon the addition of cu2+.in addition, the visual change associated with the significantly enhanced relaxivity due to the addition of cu2+ was observed from t1-weighted phantom uction copper(ii)ion is a vital metal nutrient for the metabolism of life and plays a critical role in various biological processes.1,2 its homeostasis is critical for the metabolism and development of living organisms.3,4 on the other hand, the disruption of its homeostasis may lead to a variety of physical diseases and neurological problems such as alzheimer's disease,5 menkes and wilson's disease,6 amyotrophic lateral sclerosis,7,8 and prion disease.9,10 therefore, the assessment and understanding of the distribution of biological copper in living systems by noninvasive imaging is crucial to provide more insight into copper homeostasis and better understand the relationship between copper regulation and its physiological function.a wide variety of organic uorescent dyes have been exploited for the optical detection of ions in the last few decades.11–13however, optical imaging using organic uorescent dyes hasseveral limitations such as photobleaching, light scattering,limited penetration, low spatial resolution and the disturbance of auto uorescence.14 by comparison, magnetic resonance imaging(mri)is an increasingly accessible technique used as a noninvasive clinical diagnostic modality for medical diagnosis and biomedical research.15 it can provide high spatial resolution three-dimensional anatomical images with information about physiological signals and biochemical events.16 as a powerful diagnostic imaging tool in medicine, mri can distinguish normal tissue from diseased tissue and lesions in a noninvasive manner,17–19 which avoids diagnostic thoracotomy or laparotomy surgery for medical diagnoses and greatly improves the diagnostic le mri imaging parameters can provide a wealth of diagnostic addition, the desired cross-section for acquiring multi-angle and multi-planar images of various parts of the entire body can be freely chosen by adjusting the mri magnetic eld;this ability makes medical diagnostics and studies of the body's metabolism and function more and more effective and st agents are often used in mri examinations to improve the resolution and sensitivity;the image quality can be signicantly improved by applying contrast agents which enhance the mri signal intensity by increasing the relaxation rates of the surrounding water protons.20 due to the high magnetic moment(seven unpaired electrons)and slow electronic relaxation of the

paramagnetic gadolinium(iii)ion, gadolinium(iii)-based mri contrast agents are commonly employed to increase the relaxation rate of the surrounding water protons.16,21 however, most of these contrast agents are nonspecific and provide only anatomical the basis of solomon–bloembergen–morgan theory,22–24 several parameters can be manipulated to alter the relaxivity of gadolinium(iii)-based mri contrast parameters include the number of coordinated water molecules(q), the rotational correlation time(sr)and the residence lifetime of coordinated water molecules bound to the paramagnetic gd3+ center(sm).adjusting any of these three factors provides the opportunity to design “smart” mri contrast agents for specific biochemical events.25–27 in recent years, there have been many studies on the development of responsive gadolinium(iii)-based mri contrast agents;most of them have focused on the development of targeted, high relaxivity and bioactivated contrast responsive gadolinium(iii)-based mri contrast agents can be modulated by particular in vivo stimuli including ph,28–35 metal ion concentration36–43 and enzyme activity.44–50 notably, a number of copper-responsive mri contrast agents have been reported to detect uctuations of copper ions in vivo.51–58 these activated contrast agents exploit the modulation of the number of coordinated water molecules to generate distinct enhancements in longitudinal relaxivity in response to copper ions(cu+ or cu2+).in this study, we designed and synthesized a binuclear gadolinium-based mri contrast agent, [gd2(do3a)2bmpna], that is specically responsive to cu2+ over other biologicallyrelevant metal new copper-responsive mri contrast agent comprises two gd-do3a cores connected by a 2,6-bis(3-methyl-1h-pyrazol-1-yl)isonicotinic acid scaffold59,60(bmpna), which functions as a receptor for copper-induced relaxivity synthetic strategy for [gd2(do3a)2bmpna] is depicted in scheme uently, the t1 relaxivity of [gd2(do3a)2bmpna] was studied at 25 c and 60 mhz in the absence or presence of cu2+.experiments to determine the selectivity of [gd2(do3a)2bmpna] towards cu2+ over other biologically-relevant ions were carried out as scence lifetime was measured to determine the number of coordinated water molecules(q)of [gd2(do3a)2bmpna] in the absence or presence of cu2+.in addition, t1-weighted phantom images were collected to visualize the relaxivity enhancement caused by cu2+, suggesting potential in vivo mental section

materials and instruments

all materials for synthesis were purchased from commercial suppliers and used without further purication.1h and 13c nmr spectra were taken on an amx600 bruker ft-nmr spectrometer with tetramethylsilane(tms)as an internal scence measurements were performed on a hitachi fluorescence time-resolved luminescence emission spectra were recorded on a perkin-elmer ls-55 uorimeter with the following conditions: excitation wavelength, 295 nm;emission wavelength, 545 nm;dela time, 0.02 ms;gate time, 2.00 ms;cycle time, 20 ms;excitation slit, 5 nm;emission slit, 10 luminescence lifetime was measured on a lecroy wave runner 6100 digital oscilloscope(1 ghz)using a tunable laser(pulse width ¼ 4 ns, gate ¼ 50 ns)as the excitation(continuum sunlite opo).mass spectra(ms)were obtained on an auto ex iii tof/tof maldi-ms and anionspec esi-fticr mass tal analyses were performed on a vario el element sis synthesis of compound 2,6-bis(3-(bromomethyl)-1h-pyrazol-1-yl)isonicotinate(compound1)59,60 and 4,7,10-tris(2-(tert-butoxy)-2-oxoethyl)-4,7,10-triaza-azoniacyclododecan-1-ium bromide(compound 2)61 were prepared following thereported nd 2(0.25 g, 0.296 mmol)was suspended in 2 ml anhydrous acetonitrile with 6 equivalents of nahco3(0.1492 g)and the mixture was stirred at room temperature for 0.5 nd 1(0.0675 g, 0.148 mmol)was added, and the mixture was slowly heated to reflux(80 c)and stirred the reaction was terminated, the mixture was cooled to room temperature, and the solution was precipitate was washed several times with anhydrous acetonitrile, and the collected ltrate solution was evaporated under reduced residue was puried using silicagel column chromatography eluted with ch2cl2–n-hexane–ch3oh(10 : 3 : 1, v/v/v)to afford compound 3(0.1038 g, 53%)as a pale yellow solid.1h nmr(600 mhz, dmso): 8.22(s, 2h), 8.15(s, 2h), 6.62(s, 2h), 4.53(s, 4h), 3.82(s, 3h), 3.42(m, 4h), 2.98(m, 8h), 2.85(s, 8h), 2.71(m, 24h), 1.33(s, 54h)(fig.s1†).13c nmr(151 mhz, cdcl3): d 173.21, 172.44, 163.99, 152.38, 150.11, 143.13, 128.07, 109.83, 108.36, 82.59, 57.84, 56.52, 56.06, 55.56, 52.98, 50.55, 48.91, 47.30, 27.96(fig.s2†).hrms(esi): m/z c67h111n13o14 [m + 2h]2+ 661.92650, [m + h + na]2+ 672.91747, [m + 2na]2+ 683.90844, found [m + 2h]2+ 661.92584, [m+ h + na]2+ 672.91690, [m + 2na]2+ 683.90682(fig.s3†).synthesis of compound nd 3(0.1 g, 0.0756 mmol)was stirred with triuoroacetic acid in methylene chloride solution(2 ml)at room temperature for 24 solvent was then evaporated under reduced pressure, and the residue was washed three times in ch3oh and ch2cl2 to eliminate excess obtained residue was dissolved with a minimum volume of ch3oh and precipitated with cold precipitate was ltered to afford a brown yellow solid(0.1022 g).1h nmr(600 mhz, dmso): 9.06(s, 2h), 8.17(s, 2h), 6.84(s, 2h), 4.33(s, 4h), 3.98(s, 3h), 3.56(b, 20h), 3.09(m, 24h)(fig.s4†).13c nmr(151 mhz, d2o): d 174.11, 169.13, 164.64, 150.75, 148.85, 142.10, 129.88, 109.75, 107.99, 55.69, 54.01, 53.10, 52.43, 51.15, 49.59, 48.22, 47.69(fig.s5†).maldi-tofms spectrum(ch3oh): m/z c43h63n13o14 [m h] 984.46, found 984.7(fig.s6†).anal c43h63n13o14-$3cf3cooh$2h2o: c, 43.14;h, 5.17;n, 13.35;found c, 42.34;h, 4.999;n, 13.29%.preparation of [gd2(do3a)2bmpna] and [tb2(do3a)2-bmpna].compound 4(0.05 mmol)was dissolved in 2 ml of highly-puried 3 or tbcl3(0.1 mmol)was added ph was maintained at 6.5–7.0 with naoh during the whole solution was then stirred at 75 c for 24 -ms(h2o): m/z c42h55n13o14gd2 [m + h]+ 1281.46, found 1281.4(fig.s7†).maldi-ms(h2o): m/z c42h55n13o14tb2 [m + h]+ 1284.3, found 1284.4(fig.s8†).t1 longitudinal relaxation times(t1)of aqueous solutions of [gd2(do3a)2bmpna] were measured on an ht-mrsi60-25 spectrometer(shanghai shinning globe science and education equipment co., ltd)at 1.5 of the tested samples were prepared in hepes-buffered aqueous solutions at ph of the metal ions(na+, k+, ca2+, mg2+, cu2+, zn2+, fe3+, fe2+)were used as chloride trations of gd3+ were determined by vities were determined from the slope of the plot of 1/t1 vs.[gd].the data were tted to the following eqn(1),20

(1/t1)obs ¼(1/t1)d + r1[m](1)

where(1/t1)obs and(1/t1)d are the observed values in the presence and absence of the paramagnetic species, respectively, and [m] is the concentration of paramagnetic [gd].luminescence scence emission spectra were collected on a hitachi uorescence luminescence lifetime was measured on a lecroy wave runner 6100 digital oscilloscope(1 ghz)using a tunable laser(pulse width ¼ 4 ns, gate ¼ 50 ns)as the excitation(continuum sunlite opo).samples were excited at 290 nm, and the emission maximum(545 nm)was used to determine luminescence tb(iii)-based emission spectra were measured using 0.1 mm solutions of tb complex analog in 100 mm hepes buffer at ph 7.4 in h2o and d2o in the absence and presence of cu2+.the number of coordinated water molecules(q)was calculated according to eqn(2):62,63 q= ¼ 5(sh2o1 sd2o1 0.06)(2)t1-weighted mri phantom m images were collected on a 1.5 t ht-mrsi60-25 spectrometer(shanghai shinning globe science and education equipment co., ltd).instrument parameter settings were as follows: 1.5 t magnet;matrix =256 256;slice thickness =1 mm;te= 13 ms;tr= 100 ms;and number of acquisitions =s and discussion longitudinal relaxivity of [gd2(do3a)2bmpna] in response to copper(ii)ion to investigate the inuence of cu2+ on the relaxivity of [gd2(do3a)2bmpna], the longitudinal relaxivity r1 for the [gd2(do3a)2bmpna] contrast agent was determined using t1 measurements in the absence or presence of cu2+ at 60 mhz and 25 c using a 0.2mmgd3+ solution of [gd2(do3a)2bmpna] in 100 mm hepes buffer(ph 7.4)under simulated physiological condit concentrations of gd3+ were determined by relaxivity r1 was calculated from eqn(1).in the absence of cu2+, the relaxivity of [gd2(do3a)2bmpna] was 6.40 mm1 s1, which was higher than that of [gd(dota)(h2o)](4.2 mm1 s1, 20 mhz, 25 c)and gd(do3a)(h2o)2(4.8 mm1 s1, 20 mhz, 40 c).64 upon addition of up to 1 cu2+, the relaxivity of [gd2(do3a)2bmpna] increased to 11.28 mm1 s1(76% relaxivity enhancement).as shown in fig.1, the relaxivity gradually increased with the copper ion concentration, reaching a maximum value of approximately 1.2 equivalents of cu2+.due to the use of triuoroacetic acid in the synthesis of compound 4, triuoroacetic acid residues produced cf3coo in the [gd2(do3a)2bmpna] solution, allowing cf3coo to partially coordinate with cu2+ to form “chinese lantern” type structure complexes.65 when the amount of added copper ions was further increased to above 1.2 equiv., the relaxivity was maintained at the same observed difference in cu2+-triggered relaxivity enhancement demonstrated the ability of this contrast agent to sense cu2+ in vivo by means of designed contrast agent not only exhibited a higher relaxivity, but also displayed a cu2+-responsive relaxivity ivity studies the relaxivity response of [gd2(do3a)2bmpna] exhibited excellent selectivity for cu2+ over a variety of other competing, biologically-relevant metal ions at physiological depicted in fig.2(white bars), the addition of alkali metal cations(10 mm na+, 2 mm k+)and alkaline earth metal cations(2 mm mg2+, 2 mm ca2+)did not generate an increase in relaxivity compared to the copper ion turn-on response;even the introduction of d-block metal cations(0.2 mm fe2+, 0.2 mm fe3+, 0.2 mm or 2 mm zn2+)did not trigger relaxivity noted that zn2+ is also known to replace gd3+ in transmetalation experiments;however, studies with analogous gd3+-do3a complexes demonstrated that this ligand is more kinetically inert to metal-ion exchange.66 to ensure the kinetic stability of the complex, we used ms to monitor [gd2(do3a)2bmpna] in the presence of 1 zn2+.no metal-ion exchange was observed at room temperature after 7 days(fig.s13†).relaxivity interference experiments for [gd2(do3a)2bmpna] in the presence of both cu2+(0.2 mm)and other biologically-relevant metal ions were also conducted;the results are shown as black bars in fig.2, indicating that these biologically-relevant metal ions(na+, k+, mg2+, ca2+, fe2+, fe3+, zn2+)had no interference on the cu2+-triggered relaxivity addition, we also tested the cu2+ response for [gd2(do3a)2bmpna] in the presence of physiologically-relevant concentrations of common biological anions to determine whether the cu2+-triggered relaxivity enhancement was affected by biological anions at physiological previously mentioned, cu2+ binding induced an enhancement in relaxivity from 6.40 mm1 s1 to 11.28 mm1 s1(a 76% increase).as shown in fig.3, in the presence of citrate(0.13 mm), lactate(0.9 mm), h2po4(0.9 mm), or hco3(10 mm), the cu2+-triggered relaxivity enhancement was approximately 61%(from 6.01 mm1 s1 to 9.66mm1 s1), 66%(from 6.13mm1 s1 to 10.16 mm1 s1), 20%(from 5.88 mm1 s1 to 7.02 mm1 s1), or 55%(from 6.15 mm1 s1 to 9.55 mm1 s1), onally, 100 mm nacl had almost no effect(an approximately 75% increase), and a simulated extracellular anion solution(eas, contain 30 mm nahco3, 100 mm nacl, 0.9 mm kh2po4, 2.3 mm sodium lactate, and 0.13 mm sodium citrate, ph =7),67 resulted in a cu2+-triggered relaxivity enhancement of approximately 26%(from 6.02 mm1 s1 to 7.56 mm1 s1).generally, the results revealed that lactate, citrate, and hco3 had slight impacts on the cu2+-triggered relaxivity enhancement, while h2po4 and eas influenced the enhancement to a greater shown in scheme 2, [gd2(do3a)2bmpna] possessed two water molecules after the addition of 1 cu2+.according to the work of dickins and coworkers, in lanthanide complexes with two water molecules, the waters can be partially displaced by phosphate, carbonate, acetate, carboxylate, lactate and citrate at different levels.68–70 the influence of these anions on the cu2+-triggered relaxivity enhancement may be attributed to the partial replacement of coordinated water molecules by these an relatively high concentration of phosphate could likely replace coordinated water molecules to reduce the increased number of water molecules surrounding the paramagnetic gd3+ centre induced by cu2+.as shown in table 1, we measured the number of water molecules in the rst coordination sphere of tb3+ in the presence of phosphate;the number of coordinated water molecules(q)decreased from 1.5 to nation features luminescence lifetime experiments were performed to explore the mechanism of the cu2+-triggered relaxivity scence lifetime measurements of lanthanide complexes have been widely used to quantify the number of inner-sphere water molecules.71 in particular, tb3+ and eu3+ have commonly been applied for lifetime measurements because their emission spectra are in the visible region when their 4f electrons are relaxed from higher energy levels to the lowest energy multiplets.72,73 therefore, the tb3+ analogue of [gd2(do3a)2bmpna], [tb2(do3a)2bmpna], was prepared according to a similar method, and the luminescence lifetimes of the tb3+ analogue in hepes-buffered h2o and d2o in the absence and presence of cu2+ were shown in fig.s9,† the luminescence decay curve of [tb2(do3a)2bmpna] was tted to obtain the luminescence lifetimes74(table 1), and the number of coordinated water molecules(q)was calculated by eqn(2).the analysis results(table 1)for [tb2(do3a)2bmpna] in hepes-bufferedh2oandd2o in the absence and presence of cu2+ indicated that q increased from 0.6 to 1.5 upon the addition of 1 cu2+;this result indicated that the cu2+-triggered relaxivity enhancement for [gd2(do3a)2bmpna] was most likely due to the increased number of coordinated water molecules around the gd3+ ion upon cu2+ binding to the pyrazole centre(scheme 2).aer the addition of cu2+, cu2+ removed the pyrazole centre n atom from the paramagnetic gd3+ ion to generate an open coordination site available for a water scence emission titrations of [tb2(do3a)2bmpna] towards cu2+ were also performed to investigate the binding properties of the contrast agent towards cu2+.upon addition of 1 2+, the luminescence of [tb2(do3a)2bmpna] at 545 nm decreased gradually and reached a minimum due to the quenching nature of the paramagnetic cu2+(fig.s10†).the titration data indicated a 1 : 1 binding stoichiometry(scheme 2)copper-responsive t1-weighted phantom mri in vitro to demonstrate the potential feasibility of this cu2+-responsive [gd2(do3a)2bmpna] for copper-imaging applications, t1-weighted phantom images of [gd2(do3a)2bmpna] were acquired in the absence and presence of copper phantom images depicted in fig.4 displayed distinct increases in image intensity in the presence of 1 2+ compared with those without cu2+(fig.4d).moreover, some of the other competing metal ions were also tested to further verify the selectivity of [gd2(do3a)2bmpna] towards cu2+.discernible differences were not observed upon the addition of mg2+(fig.4c), zn2+(fig.4e), or ca2+(fig.4f).in addition, we also tested the clinical contrast agent magnevist(fig.4g);the image intensity was a bit darker than that of our contrast sions

in conclusion, we designed and synthesized a novel bismacrocyclic do3a-type cu2+-responsive mri contrast agent, [gd2(do3a)2bmpna].the new cu2+-responsive mri contrast agent comprised two gd-do3a cores connected by a 2,6-bis(3-methyl-1h-pyrazol-1-yl)isonicotinic acid scaffold(bmpna)that functioned as a cu2+ receptor switch to induce a distinct relaxivity enhancement in response to cu2+;the relaxivity was increased up to 76%.importantly, the complex exhibited high selectivity for cu2+ over a range of other biologically-relevant metal ions at physiological scence lifetime experiment results showed that the number of inner-sphere water molecules(q)increased from 0.6 to 1.5 upon the addition of 1 2+.when cu2+ was coordinated in the central part of the complex, the donor n atom of the pyrazole centre was removed from the paramagnetic gd3+ ion and replaced by a water molecule(scheme 2).consequently, the cu2+-triggered relaxivity enhancement could be ascribed to the increase in the number of inner-sphere water designed contrast agent had a longitudinal relaxivity of 6.40 mm1 s1, which was higher than that of [gd(dota)(h2o)](4.2 mm1 s1, 20 mhz, 25 c)and gd(do3a)(h2o)2(4.8 mm1 s1, 20 mhz, 40 c).in addition, the visual change associated with the signicantly enhanced relaxivity from the addition of cu2+ was observed in t1-weighted phantom ledgements we are grateful to the state key laboratory of electroanalytical chemistry for nancial and references 1 and , ., 2002, 6, 171.2 , and , , ., 2009, 146, 1793.3 ff and a, iol., 1998, 28, 403.4 ski, a-klos, , li, in and in, coord.., 2009, 253, 2665.5 m, s and , discovery, 2004, 3, 205.6 er, kas and , ., 1999, 6, 221.7 ine and , .u.s.a., 2003, 100, 3617.8 , and and, ci., 2004, 27, 723.9 user, ., 2004, 37, 79.10 and ski, dalton trans., 2004, 1907.11 k, ., 1994, 27, 302.12 , ta, ti and roni, coord.., 2000, 205, 59.13 , , , and , ., 2008, 37, 1465.14 di, shan and t, nanoscale, 2011, 3, 3007.15 , magnetic resonance imaging, blackwell science, berlin, 4th edn, 2001, p.149.16 h and ´e.t´oth, the chemistry of contrast agents in medical magnetic resonance imaging, john wiley & sons, ltd., new york, 2001.17 , o, li and , ., 2010, 110, 3019.18 , and o, ., 1998, 27, 19.19 , er and , ., 2006, 35, 500.20 r, ., 1987, 87, 901.21 wski, and , ., 2005, 57, 42.22 n, ., 1955, 99, 559.23 ergen, ., 1957, 27, 572.24 ergen and , ., 1961, 34, 842.25 and , ., 2010, 39, 51.26 and ´e.t´oth, future ., 2010, 2, 367.27 , ta, ti and roni, coord.., 2000, 205, 59.28 , , , zana, ano and , ., 1999, 1577.29 , , , , er, and sousa, new ., 1998, 22, 627.30 and , ., 2000, 707.31 , , , and sousa, ., 1997, 119, 4767.32 , , and o, ., 2006, 128, 11326.33 , , , , , lano, io and rin, ., 2001, 123, 7601.34 d, d, and ess, .soc., perkin trans.2, 2001, 929.35 ´e.t´oth, r, , ´alez, , h, aman and , ., 2004, 127, 799.36 , and , ., 1999, 121, 1413.37 a, , ein, vski and etis, ., 2008, 3444.38 , to, io, u and , analyst, 2007, 132, 1153.39 le´on-rodr´ıguez, , j.a.l´opez, -de-riquer, do-monz´on and , medchemcomm, 2012, 3, 480.40 ski, , and , ., ., 2005, 44, 6920.41 , , and , dalton trans., 2012, 41, 9405.42 a, i, and , .soc., perkin trans.2, 2001, 1840.43 , and h, ., 2004, 842.44 ello, and , ., 2007, 4044.45 s, o, g and , dalton trans., 2010, 3407.46 and , ., 2011, 47, 4998.47 , and , ., ., 1997, 36, 726.48 , , , cher, , , and , hnol., 2000, 18, 321.49 and , ., 2006, 128, 14032.50 , , , , ov, and wski, ., 2006, 128, 13274.51 and , ., 2006, 128, 15942.52 , io, , , and , ., 2009, 131, 8527.53 , io, , and , dalton trans., 2010, 39, 469.54 , and , dalton trans., 2011, 484.55 , and , ., 2012, 3, 1829.56 s, o, g and , dalton trans., 2010, 3407.57 , , , , , and , dalton trans., 2011, 5018.58 , , , , and , biomaterials, 2011, 32, 1167.59 , , and ´ıguez-ubis, ., 2002, 1, 613.60 , , , , and , ctron., 2010, 26, 1043.61 mi, , and i, ., 2008, 130, 14376.62 ks and k, ., 1981, 14, 384.63 , ini, ni, i, li, a and lletti, ., 2005, 44, 529.64 n, n, y and , ., 1999, 99, 2293.65 ov, , , , on and s, ., 2000, 39, 1735.66 e, , , and , g, 1991, 9, 409.67 , coord.., 2000, 205, 109.68 s, ugsson, and k, ., 1998, 1643.69 , s, ock, ugsson, ki, , , k, , and , ., 2000, 122, 9674.70 s, , ov, , , , , , , k and ann, ., 2002, 124, 12697–12705.71 ks and k, ., 1981, 14, 384.72 and y, ., 1982, 54, 610.73 ans, ., 2009, 109, 4283.74 , ini, ni, i, li, a and lletti, ., 2005, 44, journal is © the royal society of chemistry 2014 rsc adv., 2014, 4, 34421–34427 | 34427