Search

Cryogenic system working at 2 K is crucial for superconducting accelerator. A 70 W@2 K cryogenic system was developed for the testing of superconducting cavities used in the China Initiative Accelerator Driven System (CiADS). There will be more than 257 superconducting radio frequency (SRF) cavities to be vertically tested in the next three years. The system is designed with 2 testing dewars and the cool down/warm up processes of two dewars can be conducted simultaneously, so that the interval between each test can be reduced to minimum. The system process was designed and heat loads were analyzed under practical conditions. The parameters’ calculation and design of the core equipment, such as sub-atmospheric heat exchanger, valve box, vertical testing dewar, and vacuum pump set, are described in detail. First cooling down experiment was carried out successfully, realizing a continuous cooling down process from 300 K to 4.5 K in 30 h, and then reaching 2 K in another 2.5 h.

Multilingual abstracts in the six official working languages of the United Nations. (PDF 415Â kb)

A stable hydrosol of graphene was synthesized by oxidation reduction and then a flow assembly of this graphene was used to form a graphene-based membrane by vacuum extraction filtering method. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, particle size analysis, and scanning probe microscopy (SPM) were used to characterize the crystal structure, granularity, and characteristic change of the molecular spectrum of the samples in the reaction. FTIR tests show that the structural layer of graphite during the oxidation process bonds to a large number of functional groups and parts of these stable functional groups remain on the reduced structural layer of graphene. X-ray diffraction results show that the peaks of the graphite oxide shift to lower angles, become broader and the original graphite peak disappears. Suspensions of graphene oxide form condensed matter and graphene flocculating constituent during film deposition. Particle size analysis and SPM tests show that the particle sizes of the graphene oxide sheets that are dispersed in water show a tailing peak and a broad distribution while the graphene sheets show a singlet, narrower distribution, and smaller dimensions. Raman results show that during oxidation and reduction, the D peak and G peak of the samples gradually extend, ID/IG increases gradually and the degree of sample disorder increases. On the basis of the above analyses, the structural characteristics of the samples in the reaction are summarized.

Objective: To investigate the efficacy of specific point acupuncture and manipulative adjustment on muscle strength of the knee osteoarthritis. Method: One hundred and five patients were randomly allocated to two groups. Sixty-eight cases in the treatment group were treated by specific point acupuncture and manipulative adjustment on muscle strength of the knee joint. While 37 cases in the control group were treated with specific point acupuncture alone. Result: The total effective rate was significantly higher in the treatment group than in the control group (P＜0.05). Conclusion: Specific point acupuncture and manipulative adjustment on muscle strength of the knee joint has a satisfactory curative effect on knee osteoarthritis.

The soil infiltrability of hill-slope is important to such studies and practices as hydrological process, crop water supply, irrigation practices, and soil erosion. A new method for measuring soil infiltrability on hill-slope under rainfall condition with run off-on-out was advanced. Based on water (mass) balance, the mathematic models for soil infiltrability estimated from the advances of runoff on soil surface and the water running out of the slope were derived. Experiments of 2 cases were conducted. Case I was done under a rainfall intensity of 20 mm/h, at a slope gradient of about 0° with a runoff/on length (area) ratio of 1 : 1. Case II was under a rainfall intensity of 60 mm/h and a slope of 20° with a runoff/on length (area) ratio of 1 : 1. Double ring method was also used to measure the infiltrability for comparison purposes. The experiments were done with soil moisture of 10%. Required data were collected from laboratory experiments. The infiltrability curves were computed from the experimental data. The results indicate that the method can well conceptually represent the transient infiltrability process, with capability to simulate the very high initial soil infiltrability. The rationalities of the method and the models were validated. The errors of the method for the two cases were 1.82%/1.39% and 4.49%/3.529% (Experimental/Model) respectively, as estimated by comparing the rainfall amount with the infiltrated volume, to demonstrate the accuracy of the method. The transient and steady infiltrability measured with double ring was much lower than those with this new method, due to water supply limit and soil aggregates breaking down at initial infiltration stage. The method can overcome the short backs of the traditional sprinkler method and double ring method for soil infiltraility. It can be used to measure the infiltrability of sloped surface under rainfall-runoff-erosion conditions, in the related studies.

The interfacial behavior of HDEHP at various diluents/0.05M (H2,Na2)SO4 interfaces was examined using the Drop Volume Method. Different adsorption isotherms such as the Gibbs and Szyszkowski were found as fits well to the experimental interfacial tension isotherms. The values of surface excess at saturated interface,calculated according to them by using the concentration of individual species (e.g. organic monomeric species),increase in the order: MIBK

The synergic extraction of uranium(VI) from nitric acid solution with a mixture of bis(octylsulfinyl)ethane (BOSE) and petroleum sulfoxides (PSO) in 1,1,2,2- tetrachloroethane has been studied. The composition of the complex of the synergic extraction is UO2(NO3)2·BOSE·PSO. The formation constant of the complex is KPT = 4.44±0.23. The effect of extractant concentration, nitric acid concentration, salting-out agent concentration and temperature on the extraction equilibrium of uranium(VI) is also studied and the enthalpy of the extraction reaction is calculated. It has been found that the maximum synergic extraction effect occurs if the molar ratio of PSO to BOSE is one to one.

The synergic extraction of uranium(VI) from nitric acid solution with petroleum sulfoxides (PSO) and tri-n-butyl phosphate (TBP) mixture has been studied. It has been found that maximum synergic extraction effect occurs if the molar ratio of PSO to TBP is two to three. The composition of the complex of synergic extraction is UO2(NO3)(2). TBP . PSO. The formation constant of the complex is K-PT = 8.19. The effect of extractant concentration, nitric acid concentration, salting-out agent concentration and temperature on the extraction equilibrium of uranium(VI) was also studied.

The liquid-liquid extraction behavior of uranium(VI) from aqueous nitric acid with bis(octylsulfinyl)ethane (BOSE) in 1,1,2,2-tetrachloroethane has been studied over a wide range of conditions. The extracted species appears to be UO2(NO3)(2). 2BOSE. It was found that the extraction increases with increasing nitric acid concentration up to 7 mol/l and then decreased. Extraction also increases with increasing extractant concentration. The influence of temperature and salting-out agent concentration on the extraction equilibrium and stripping of uranium(VI) was also investigated and the enthalpy of the extraction reaction was obtained.

The effect of diluents on the extraction of uranium(VI) with petroleum sulfoxides (PSO) was studied. The decreasing order of extraction ability of PSO is as follows: benzene, toluene, cyclohexane, heptane, kerosene, carbon tetrachloride and chloroform. The effect of temperature on the extraction equilibrium was also investigated and enthalpy of the extraction was obtained. The relationship between the extraction equilibrium constants K-ex and the physical parameters of diluents can be derived.

The synergistic extraction of uranium(VI) from sulfuric acid solution with primary amine N1923 and tri-octylphosphine oxide (TOPO) inn-heptane was studied. When the mole ratio of primary amine N1923 and TOPO is about 2∶1, the distribution coefficient will be the maximum. This result shows that primary amine N1923 and TOPO could exhibit the distinct synergistic effect for extraction of uranium(VI) from sulfuric acid solution. From the results of the extraction, it was suggested that the composition of synergistic extraction species is (RNH3)UO2(SO4)2·TOPO. The equilibrium constant (K 12) of synergistic extraction reaction has been evaluated, to be 1.07·109. In addition, the integration phenomenon of N1923 and TOPO have been discussed, the integration constant (K 3) is 1.60·102.

The liquid-liquid extraction of uranium(VI) from aqueous nitric acid with bis(octylsulfinyl)methane (BOSM) has been studied over a wide range of conditions. The extracted species appear to be UO2(NO3)(2). 2BOSM. It was found that the extraction increased with increasing nitric acid concentration up to 8.5 mol/l and then decreased. Extraction also increased with increasing extractant concentration. The influence of temperature and salting-out agent concentration on the extraction equilibrium has also been investigated, and the enthalpy of the extraction reaction was estimated.

The extraction of uranium(VI) from sulfuric acid medium with tri-octylphosphine oxide (TOPO) in n-heptane was studied. Accompanied with the increase in the concentration of H2SO4, the distribution coefficient of uranium(VI) increased in the region of dilute sulfuric acid. When the concentration of H2SO4 surpassed 3.5 mol·dm−3, the distribution coefficient of uranium(VI) was at maximum. This result was due to the competition extraction between uranium(VI) and H2SO4. From the data, the composition of extracted species and the equilibrium constant of extraction reaction have been evaluated, which were (TOPOH)2UO2(SO4)2 (TOPO) and 107.6±0.15, respectively.

A study on solvent extraction of sulfuric acid by tri-octylphosphine oxide (TOPO) in n-heptane has been made. Extraction coefficients of H2SO4 as a function of H2SO4 concentration in aqueous phase, and extractant concentrations in organic phase have been studied. The composition of extracted species, equilibrium constants of extraction reaction have been evaluated. These results are important for interpreting extraction equilibrium data of uranium(VI) or other metal ions with TOPO in sulfuric acid media.

A study on extraction of uranium(VI) from sulfuric acid media by the primary amine N1923 in chloroform is described. Extraction coefficients of uranium(VI) as a function of aqueous H2SO4 concentration, extractant concentration and temperature have been studied. From the data, the compositions of extracted species, equilibrium constants and enthalpies of extraction reaction have been evaluated. A new extraction mechanism of amine has been suggested, that is the formation of reversed micelle as a result of the aggregation of ammonium salt in the organic phase of the extraction. This assumption may be used for interpreting extraction data satisfactorily, which can not be explained by the slope analysis method.