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  • Author: Xinpeng Wang x
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Abstract

Objective

To evaluate the therapeutic effect of platelet lysate (PL)/vancomycin/nano-hydroxyapatite sustained-release material on treating staphylococcus aureus-induced infectious bone defects.

Methods

40 New Zealand white rabbits were inoculated with staphylococcus aureus to construct the chronic tibial infectious bone defect model. After incision, debridement and washing, control group 1 was not given any filling, control group 2 was filled with PL/nano-hydroxyapatite sustained release material, control group 3 was filled with vancomycin/ nano-hydroxyapatite sustained release material, and the treatment group was filled with PL/vancomycin/nano-hydroxyapatite sustained-release material. Afterwards, the drug release profiles were determined in vitro and in vivo. Then, X-rays and bone specimens were used to evaluate the efficacy of the treatments.

Results

TGF-β and PDGF were effectively released for 28 days in vitro. In addition, results of the inhibition zone experiment of the composite material proved that vancomycin had favorable antibacterial activity, which effectively suppressed bacteria for as long as 43 days, thus achieving the sustained-release antibacterial effect. The drug release profiles in vitro also demonstrated that the vancomycin concentration within the lesion region was the highest in composite material, and the infection in experimental rabbits was markedly alleviated. The original backbone deformity regained the normal shape, the normal bone marrow structure began to recover 6 weeks later, and the nano-hydroxyapatite transformed into the trabecula structure. By contrast, the inflammation in the control group still existed, with no obvious new bone formation.

Conclusion

The PL/vancomycin/nano-hydroxyapatite sustained-release material effectively treats chronic infectious bone defects.

Abstract

Bis(2-ethylhexyl)phosphoric acid (HDEHP) is one of the most intensively used extractants in solvent extraction, and its particular interest lies in the its application in nuclear fuel cycle as an extractant supported by macroporous silica-based polymeric resins in solid phase extraction technique. In this study, HDEHP/SiO2-P was synthesized by impregnation and immobilization, and we mainly focused on its radiation-resistant properties against γ-rays. It was found that HDEHP/SiO2-P still had good adsorption and separation properties after γ-irradiation by batch experiment. The uptake capacity of Gd(III) towards HDEHP/SiO2-P decreased slightly after irradiation. HDEHP/SiO2-P did not show any changes in the characterization of infrared spectroscopy and thermogravimetric analysis before and after irradiation. UPLC-Q-TOF-MS was employed to investigate the reaction mechanism in radiolysis of HDEHP in irradiated filter liquor. HDEHP/SiO2-P had a satisfactory radiation-resistance and chemical stability, even though it was exposed to the high absorbed dose of 500 kGy by γ-rays.

Abstract

To separate the long-lived minor actinides (MA = Am, Cm) from high level liquid waste (HLLW), we have been studying a partitioning technology named “MAREC” (Minor Actinides Recovery from HLLW by Extraction Chromatography) process which consists of two separation columns packed with silica-based adsorbents. In this work, we prepared the silica-based 2,6-bis(5,6-diisohexyl-1,2,4-triazin-3-yl)pyridine (isohexyl-BTP/SiO2-P) adsorbent used in the second column (0.01 ∼ 0.1 mol dm3 HNO3) in the MAREC process for the separation of trivalent minor actinides (MA(III)) from trivalent rare earth elements (RE(III)) which are contained in HLLW. The content of extracting agent isohexyl-BTP in isohexyl-BTP/SiO2-P was as high as 33.3% of the total mass of the adsorbent. The adsorbent exhibited high affinity and selectivity for Am(III) over RE(III) not only in nitric acid solution but also in nitrate solution. Investigation showed that only a small part of isohexyl-BTP molecules inside isohexyl-BTP/SiO2-P leaked into 0.01 mol dm3 HNO3 with or without γ-irradiation. The adsorption performance of isohexyl-BTP/SiO2-P did not evidently change after 120 d of contact with 0.01 mol dm3 nitric acid. Furthermore, after γ-irradiated in 0.01 mol dm3 HNO3 under the experimental conditions, isohexyl-BTP/SiO2-P exhibited higher adsorption for RE(III) than before γ-irradiation.

Abstract

There is extremely strict precision requirement for the lateral breakthrough error of long immersed tunnel in the offshore island and tunnel project, but the point location layout range of the outer plane control network is limited in the artificial island, and the space inside the tunnel is long and narrow, which is not conducive to high-precision through-measurement control. In order to further reduce the influence of the error of the plane control network on the lateral breakthrough error of the immersed tunnel, a mathematical model of the influence of the lateral breakthrough error caused by the orientation direction of the outer control point and the position of the breakthrough point has been established through the theoretical analysis in this study, and the favorable orientation directions and the favorable penetration point are analyzed. It is suggested through simulation analysis that the direction that is as consistent with that from the entrance (outlet) point to the penetration point as possible is as the advantageous orientation, which could minimize the lateral penetration error and ensure high-precision rendezvous and docking of the immersed tunnel. This study is instructive for similar engineering practices.