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In recent years, 64Cu has received extensive attention along with its growing application in nuclear medicine positron emission tomography (PET) diagnosis. A 64Cu automatic separation apparatus adapted to the Cyclone-30 cyclotron was developed to realize the process automation from target dissolution to nuclide separation and purification for stable 64Cu production at large scale. The apparatus consists of a tank for target dissolution and a system for separation and purification. The operation interface, programming language and specific programming instructions were determined by programming design. Based on the established separation and purification process of 64Cu, the apparatus was designed followed by assembling and testing. After the process parameters of the apparatus were confirmed through a series of conditional experiments, the hot verification experiments at small-scale and three batches of mass production process verification were carried out consecutively, showing that this self-developed apparatus has steady function and can realize distant control. The whole separation process could be finished in 3 h. The radiochemical recovery of 64Cu (after calibration) is greater than 90%, which meets the expected goal of the design. The 64Cu product was tested with over 95% of radiochemical purity, higher than 99.9% of radio nuclidic purity. The contents of impurities such as iron, copper and zinc were less than 1.5 μg/GBq, while cobalt, gold and nickel were less than 0.5 μg/GBq, which meets the requirements of group standard and can be used for preparation of 64Cu radiopharmaceuticals. In conclusion, this self-developed apparatus has low cost and independent intellectual property rights, and its performance and the product quality of 64Cu are comparable to other competitive foreign products. Compared with the manual separation process, the automatic one has significant advantages in terms of the stability of product quality, the process controllability, the time-consuming and the radiation protection of operators. At present, the apparatus has already been used in 64Cu production routinely.

Two styryl pyrimidine derivatives substituted by p-tosyloxymethyl, Boc-SPm2-OTs and Boc-SPm5-OTs, were designed and successful synthesized, which were labeled by 18F to prepared 18F-SPm2 and 18F-SPm5 by nucleophilic substitution. The radiochemical purities of both 18F-SPm2 and 18F-SPm5 were more than 99%. Both 18F-SPm2 and 18F-SPm5 had ideal lipophilicity (LogP=1-2.5) and can maintaining stability in normal saline for over 3 h and can bind to Aβ selectively, but both 18F-SPm2 and 18F-SPm5 displayed less binding affinity (the Ki values were 246.6 nmol/L and 318.2 nmol/L, respectively). The results of biodistribution in mice demonstrated that both 18F-SPm2 and 18F-SPm5 showed relatively high initial brain uptake, with slow washout from normal brain and obvious defluorination in vivo. In conclusion, both 18F-SPm2 and 18F-SPm5 might not be ideal Aβ imaging agents, and further modifications were needed to improve the disadvantages.

In order to study the mechanical response of long-span curved cable-stayed bridge caused by cable breaking, Xigu Chaijiaxia cable-stayed bridge in Cansu Province was taken as an engineering example, the finite element model was established by using the beam lattice method, and 15 typical cable breaking conditions were selected to analyze the changes of residual cable force, main beam deflection, main beam stress and tower top offset before and after cable breaking at different positions and different numbers. The results showed that single cable breaking would only produce local effects, the peak value of the change occurred near the broken cable anchorage zone and decreased to the surrounding. The combined fracture condition had a greater impact than the single cable fracture condition. Long cable fracture had the greatest impact, followed by medium cable and short cable. The impact of cable fracture in the middle span was greater than that in the side span. The influence of cable fracture on the broken span was greater than that of non broken span, and the influence on the broken cable surface was greater than that of non broken cable surface. The effect of cable breaking on the peak stress of the main beam and the stress distribution of the whole bridge was very small, but only on the main beam stress near the anchorage zone. [ABSTRACT FROM AUTHOR]

To evaluate the influences of the joint clearances, including the joint radial clearances nd the rack moving direction inclination to lateral direction of vehicle, on the steering errors of a rack and pinion steering mechanism, the joint radial clearances in the steering mechanisms were treated as joint clearance link or variable length link, and then the kinematic model of the spatial steering mechanisms with the joint clearances and the analytical relationship between the rotation angles of kingpin axis and steering wheel were deduced by using the screw theory. An optimization model for the steering mechanisms was established by aiming at minimizing steering errors and taking the maximum values of pressure angles and the minimum value of the maximum steering angle as the constrained conditions. The kinematic analysis of an example shows that the forward and the return steering processes f the steering mechanisms with joint clearances have different steering errors and the return steering errors are larger than that of the forward steering; the steering errors at the moment of revering operation increase sharply; the increase of the joint clearance or the inclination of the rack may increase the minimum steering radius of the vehicle. Steering accuracy of the steering mechanisms with joint clearances may be improved by the optimal design considering the joint clearances. [ABSTRACT FROM AUTHOR]

Joint development of marine resources resulted from the international practice, with the characteristic of temporality and functionality. The fundamental principles of international cooperation and peaceful settlement of international disputes consist of the international law basis of joint development of marine resources, as well as the concerned provisions of the Convention on the Law of the Sea and numerous bilateral delimitation agreements between coastal states. Many international judicial precedents have focused on and affirmed the joint development, which provided strong legal supports for joint development. Although the joint development of marine resources has not bloomed into international custom with binding force, it has increasingly played a most significant role in resolving the oceanic delimitation disputes and utilizing transboundary marine resources. [ABSTRACT FROM AUTHOR]

The article discusses Chinese oral history and the scientific career of physicist Tsung-dao Lee. The author reflects on oral history collections at Columbia University and their use as research materials. The article focuses on the document "Reminiscences of Tsung-dao Lee: Oral History" based on an interview from 1963. It notes Lee's experience in scientific collaboration with scientist Chen Ning Yang and helps to elucidate how interpersonal cooperation and social structure contribute to scientific discoveries.

The minor bioactive saponins of the total saponin from the leaves of Panax notoginseng (Burk.) F. H. Chen. were separated and purified by column chromatographies on silica gel and thin layer gel. Four compounds were identified as: ginsenoside C-K (I) [20 (S) -protopanaxadiol 20-O-beta-D-glucopyranoside], ginsenoside-Rh1 (II) [20 (S) -protopanaxatriol-6-O-beta-D-glucopyranoside], ginsenoside-Mc (III) [20 (S)-protopanaxadiol 20-O-alpha-L-arabinofuranosyl (1 --> 6) -D-glucopyranoside] and notoginsenoside-Fe (IV) [20(S) -protopanaxadiol-3-O-beta-D-glucopyranosido-20-O-alpha-L-arabinofuranosyl(1 --> 6)-beta-D-glucopyranoside]. Compound I was isolated from the leaves of Panax notoginseng for the first time.