Theoretical Study on the Aggregation of Copper Clusters on a Liquid Surface.

The ground state structures of copper clusters with different sizes along with their aggregation have been systematic investigated using Amsterdam Density Functional (ADF) and Atomistix ToolKit (ATK) programs. On the basis of geometry optimization, some Cu clusters with more stable structures which were not reported previously have been revealed. In most cases, these Cu clusters prefer to adopt icosahedral structures which originate from the 13-atom icosahedron. It has also been demonstrated that the interaction between two Cu clusters is anisotropic, which is attributed to their charge distribution, especially the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of Cu clusters. Moreover, we have carried out the simulation of Cu clusters aggregation on the silicone oil substrate by means of Monte Carlo (MC) method, which shows good consistence with our previous experimental studies.

Effects of FSH and the weather during induced ovulation and timed artificial insemination to increase jenny conception rates.

Experiments were conducted to improve jenny conception rates through induced ovulation and timed insemination. Jennies in control, hCG and LH groups were injected intramuscularly with saline alone or saline containing hCG or LH, respectively, when the dominant follicle diameter reached 35 mm. Then, follicle development was checked every 8 h until the dominant follicle ovulated. While 76% of the hCG-treated jennies ovulated between 24 and 48 h, and 84% of the LH-treated ovulated between 24 and 40 h after injection, ovulations in control jennies scattered over an extended period after injection. Conception rates after insemination were significantly higher in LH- or hCG-treated jennies than in the conventionally-bred jennies. The LH preparation used in this study contained more FSH than the hCG preparation did, and supplementing the hCG treatment with FSH significantly improved ovulation synchronization. Ovulations in jennies treated on rainy days were significantly postponed and less synchronized compared to those in jennies treated on sunny days. Together, the results suggested that jenny conception could be significantly improved by inducing ovulation with LH or hCG treatment followed by timed insemination and that FSH and the weather during treatment had profound effects on ovulation induction of jennies.

Rapid development of tissue bank achieved by International Atomic Energy Agency (IAEA) Tissue Banking Programme in China.

Before 1986, the development of tissue banking in China has been slow and relatively uncoordinated. Under the support of International Atomic Energy Agency (IAEA), Tissue Banking in China experienced rapid development. In this period, China Institute for Radiation Protection tissue bank mastered systematic and modern tissue banking technique by IAEA training course and gradually developed the first regional tissue bank (Shanxi Provincial Tissue Bank, SPTB) to provide tissue allograft. Benefit from training course, SPTB promoted the development of tissue transplantation by ways of training, brochure, advertisement and meeting. Tissue allograft transplantation acquired recognition from clinic and supervision and administration from government. Quality system gradually is developing and perfecting. Tissue allograft transplantation and tissue bank are developing rapidly and healthy.

First-principles study on stability and magnetism of Ni m Al n (m = 1-3, n = 1-9) clusters.

The investigation on the structures, stabilities, and magnetism of Ni(m) Al(n) (m = 1-3, n = 1-9) clusters has been made by using first principles. We found some new ground-state structures which had not been found before. These mixed species prefer to adopt three-dimensional (3D) structures starting from four atoms. All the ground-state structures for the Ni-Al clusters are different from those of the corresponding pure Al clusters with the same number of atoms except for three atoms. The Mulliken population analysis shows that some charges transfer from the Al atoms to the Ni atoms. NiAl n (n = odd number) cations, Ni(2)Al(6) neutral, Ni(2)Al(1) and Ni(3)Al cations and anions, and Ni(3)Al(5) anion have the magnetic moments of 2 µ B. The magnetic moments of NiAl(4) and NiAl(6) cluster neutrals and cations are 2 µ B and 3 µ B, respectively. All the other cluster neutrals and ions do not have any nontrivial magnetic moments. The 3d electrons in Ni atoms are mainly responsible for the magnetism of the mixed Ni-Al clusters.

[Experimental study on tissue engineering platelet lysates in the promotion of bone reconstruction].

OBJECTIVE: To evaluate the effects of tissue engineered allogeneic platelet lysates (PL) upon bone reconstruction. METHODS: After preparation of recombinant material with PL, allogeneic decalcified bone granules (ADBG) and collagen type I (CG), 30 healthy Wistar rats were used to prepare the bilateral bone defects in femoral condyles. The defects were filled with equivalent PL/ADBG/CG, ADBG/CG and CG in different groups of A, B and C (with 10 rats each) respectively. At 4 weeks, the defect reconstruction was evaluated with radiology, histology, immunology and biomechanics. RESULTS: (1) The X-ray showed that bone density in group A (4.18 +/- 0.96) was close to that of normal bone and it was significantly higher than that in group B (2.36 +/- 0.87) and group C (1.09 +/- 0.55) (P < 0.01). (2) In comparisons with B and C, the histological assay revealed that there were markedly more activities of new bone formation and more implanted bone granules surviving without significant lymphocyte infiltration, as well as more osteoclastic bone resorption in group A. The bone histomorphometric assay showed the newly formed bone area in group A (286.73 +/- 17.22) was significantly higher than that in group B (94.34 +/- 33.56) and group C (19.12 +/- 14.53) (P < 0.01). (3) Anti-press mechanical measures showed that the destructive load in A, B, C and normal control group was 259.63 +/- 34.57, 187.90 +/- 21.07, 91.33 +/- 26.58 and 311.93 +/- 82.45 respectively. The destructive energy in A, B, C and normal control group was 10.82 +/- 1.44, 7.83 +/- 0.88, 3.81 +/- 1.11 and 12.97 +/- 3.43 respectively. These results showed either destructive load or destructive energy in group A was markedly higher than that in group B and group C with significant difference (P < 0.01), but still lower than that in normal controls (P < 0.01). (4) Three-color flow cytometry assay showed that the T lymphocyte subsets of CD3+CD4+CD8-, CD3+CD8+CD4- and the ratio of CD4/CD8 showed no significance difference within these three groups as well as normal controls. CONCLUSION: Tissue engineering PL (PL/ADBG/CG) is capable of accelerating the regenerative repair of bone defect and promoting the bone regeneration and osetointergretion of allograft bone after transplantation.

Vertebral plate regeneration induced by radiation-sterilized allogeneic bone sheets in sheep.

OBJECTIVE: To evaluate the effects and mechanism of radiation-sterilized allogeneic bone sheets in inducing vertebral plate regeneration after laminectomy in sheep. METHODS: Twelve adult male sheep (aged 1.5 years and weighing 27 kg on average) provided by China Institute for Radiation Protection underwent L3-4 and L4-5 laminectomy. Then they were randomly divided into two groups: Group A (n=6) and Group B (n=6). The operated sites of L4-5 in Group A and L3-4 in Group B were covered by "H-shaped" freeze-drying and radiation-sterilized allogeneic bone sheets (the experimental segments), while the operated sites of L3-4 in Group A and L4-5 in Group B were uncovered as the self controls (the control segments). The regeneration process of the vertebral plate and the adhesion degree of the dura were observed at 4, 8, 12, 16, 20 and 24 weeks after operation. X-ray and CT scan were performed in both segments of L3-4 and L4-5 at 4 and 24 weeks after operation. RESULTS: In the experimental segments, the bone sheets were located in the anatomical site of vertebral plate, and no lumbar spinal stenosis or compression of the dura was observed. The bone sheets were absorbed gradually and fused well with the regenerated vertebral plate. While in the control segments, the regeneration of vertebral plate was not completed yet, the scar was inserted into the spinal canal, compressing the dura and the spinal cord, and the epidural area almost disappeared. Compared with the control segments, the dura adhesion degree in the experimental regenerated segments was much milder (P less than 0.01), the internal volume of the vertebral canal had no obvious change and the shape of the dura sack remained well without obvious compression. CONCLUSIONS: Freeze-drying and radiation-sterilized allogeneic bone sheets are ideal materials for extradural laminoplasty due to their good biocompatibility, biomechanical characteristics and osteogenic ability. They can effectively reduce formation of post-laminectomy scars, prevent recurrence of post-laminectomy spinal stenosis, and induce regeneration of vertebral plates.

[Preparation of porous polylactic-acid/ bone matrix gelatin composite as scaffold materials for bone-tissue engineering].

OBJECTIVE: To develop a novel porous poly lactic-acid(PLA)/bone matrix gelatin (BMG) bioactive composite biomaterial with supercritical carbon dioxide (SC-CO2) extraction and determine the optimal proportion of the ingredients by evaluating the physical and chemical characteristics and cellular compatibility of the composites. METHODS: The PLA/BMG composite biomaterials with various PLA/BMG proportions were prepared with SC-CO2 technique and evaluated by macroscopic observation, porosity and mechanical assessment, and scanning electron micrograph (SEM). The optimal proportion of PLA/BMG was determined in conjunction with the results of cellular compatibility evaluation. RESULTS: BMG proportion in BLA/BMG composite biomaterials prepared with SC-CO2 technique was positively associated with the cellular compatibility and porosity, and inversely with the mechanics of the prepared composite. The results showed BMG content of 30% in PLA/BMG composite was optimal. CONCLUSION: The composite with PLA and BMG proportion of 7:3 possesses good physical and chemical characteristics and cellular compatibility, suggesting its potential as the bone implant biomaterial and bone-tissue engineering scaffold.