Study on Calcium Phosphate Cement for Bone Reconstruction

Liming, Hu,Changsheng, Liu,Wei, Shen,Yanfang, Gu 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.1 No.2

In this paper the prepartation of calcium phosphate salts, the setting technology, the mechanism of hydration and hardening and the biocompatibility of CPC are studied systematically. The results show that using ultrafine HAP and CaCo$_{3}$ as starting materials can greatly shorten the reaction time for the prepartation of pure TECP(only 9 hour needed) : the existence of HAP seed may cut down the setting time, bu lower the compressive strength ; the proper powder-to-liquid ratio is 4 : 1 ; the rate of hydration is comparatively rapid initially, controlled by dissolution of the reactants surfaces, however, eventually becomes diffusion nally controlled ; during the hydration and hardening process of CPC, the paste changes from viscoplasticity to viscoelasticity and to elasticity ; the initial structure is net-work fromed by Van der Waals' forces, which gradually strengthens, eventually connected by chemical bondings. The final product of CPC is acicular HAP, which has high biocompatibility including no toxicity, no carcinogenicity, no mutagenicity and no deformity. When CPC is implanted, it is highly compatible with soft tissue, and close connection between CPC and adjacent bone will occur one month later.

Polymorphisms of Inflammatory Cytokine Genes and Risk for Intracranial Aneurysm: A Systematic Review and Meta-Analysis

Liming Hu,Bingyang Li,Xin Liao,Junxia Yan 연세대학교의과대학 2020 Yonsei medical journal Vol.61 No.5

Purpose: Inflammatory cytokines are thought to be involved in the pathogenesis of intracranial aneurysm (IA), although results among studies in the literature are inconsistent. This article sought to review studies on the associations among polymorphisms in inflammatory cytokine genes and IA risk and to provide recommendations for future research. Materials and Methods: A systematic search of PubMed, Embase, and Web of Science was conducted up to August 4, 2019. The associations between polymorphisms of inflammatory cytokine genes and IA risk were estimated by pooled odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses were performed according to race. Qualitative systematic review was conducted for variants that were studied in only one study. All analyses were performed using STATA 12.0. Results: 13 studies investigating the associations between polymorphisms in five inflammatory cytokine genes (TNF-α, IL-1α, IL-1β, IL6, and IL-12B) and IA were reviewed. Combined results showed that the A allele of TNF-α rs1800629 polymorphism has a protective effect against IA (dominant model: OR=0.65, 95% CI=0.47–0.89, p=0.007). No associations were identified between polymorphisms in IL-1α rs1800587, IL-1β rs16944, IL6 rs1800795 and rs1800796, or IL-12B rs3212227 and IA risk. Conclusion: This review demonstrated an association between TNF-α rs1800629 polymorphism and IA in Caucasians, illustrating the potentially important role of genes involved in inflammation in IA.

Spatial Distribution Patterns of Soil Salinity in the Heavy Salinization Zone at Different Scales in Yinchuan Plain

Anping Yun,Kelin Hu,Yongping Wei,Liming Liu,De Zhou 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Preparation and Oxidation resistance of Nanometre-sized Copper Powders

Liu, Zhijie,Zhao, Bin,Zhang, Zongtao,Hu, Liming 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.2 No.4

Using chemical reduction emthod in aqueous solutions, ultrafine copper powders with mean diameter about 50nm were prepared and the stability of nanometre-sized copper powders stored in deionic water was studied. The oxidation resistance of nanometre-sized copper powders was greatly improved by using silver-coating method and surface phosphazition. The oxidizing temperatures were beyond 25$0^{\circ}C$.

Testicular Characteristics and the Block to Spermatogenesis in Mature Hinny

Han, Hongmei,Wang, Aihong,Liu, Liming,Zhao, Gaoping,Su, Jie,Wang, Biao,Li, Yunxia,Zhang, Jindun,Wu, Baojiang,Sun, Wei,Hu, Shuxiang,Li, Shuyu,Zhao, Lixia,Li, Xihe Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.6

Most hinnies (female donkey${\times}$male horse) and mules (female horse${\times}$male donkey) are sterile with few reports of equine fertile hybrids. The main cause of this sterility is thought to be a meiotic block to spermatogenesis and oogenesis. This study compared the developmental features of the testes and a histological analyses of spermatogenesis in a male hinny with those of a normal, fertile stallion and Jack donkey. Hinny testes showed a thicker tunica albuginea, fewer blood vessels and more connective tissue in the testis parenchyma than those of the stallion and Jack donkey. Although the mean number of seminiferous tubules was significantly higher in stallion and hinny than Jack donkey (p<0.01), the mean proportion of seminiferous tubules was lower in the hinny (p<0.01) which resulted in a smaller diameter of seminiferous tubules. The mean number of spermatogonia and spermatocytes per unit area were significantly lower in hinny testis (p<0.01) and no spermatids or mature spermatozoa cells were found during immunofluorescent analyses. These results indicated that defects in seminiferous tubule development and structure occur in the testis of hinnies. Furthermore, most spermatogonia and spermatocytes cease development in synapsis during mid-meiosis of spermatocytes, which results in a block to spermatogenesis that prevents the formation of spermatids and matured spermatozoa during meiosis in male hinnies.

Optimal Area and Intrinsic Coherent Resonance of Neurons due to Ion Channel Noise under an external Stimulus

Zhengzhen Zhang,Shaowen Zeng,Wenyan Tang,Jinlin Hu,Rongfeng Wang,Liming Zhou,Shangyou Zeng 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.1

In this paper, we study the intrinsic coherence resonance of neurons due to ion channel noise under an external stimulus. We find that the external stimulus cannot only increase the spiking coherence of neurons but also increase the optimal area of neuronal membrane for maximal spiking coherence. The optimal membrane area is approximately 3 μm² without the external stimulus. However, when the external stimulus is 6 μA/cm², the optimal membrane area is approximately 400 μm². Because 400 μm² is the area of a common neuronal soma, our finding has a realistic meaning. Under the external stimulus, common neurons have an optimized conformation to guarantee maximal spiking coherence and the best sub-threshold signal encoding.

The multidirectional vibration and coupling dynamics of drill string and its influence on the wellbore trajectory

Lin Yang,Jia-lin Tian,Qingyou Liu,Liming Dai,Zhichao Hu,Jurui Li 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.7

For improving the accuracy of wellbore trajectory prediction in complex wellbore structures, especially in the kick-off section, a longitudinal, torsional and radial coupled drill string dynamics model is proposed. At the same time, the coupling dynamics model is solved based on the energy method, and the torque, weight on bit (WOB), the longitudinal displacement and velocity, the torsional angular displacement and angular velocity of the drill bit are obtained during the normal drilling and the stick-slip vibration phase. Combining the numerical example and experimental test, the differences between different models and actual drilling trajectories are compared and analyzed. The research results indicate that the torsional vibration and the longitudinal vibration have a great influence on each other in the coupling model, and the longitudinal vibration displacement increases, which can effectively reduce the torque variation range of the torsional vibration. The operation of the bit stagnation is weakened, maintaining a relatively stable rotational angular velocity of rotation. The calculation results of the wellbore trajectory are more consistent with the experimental results, and can accurately reflect the real situation of the drilling process. The theoretical model has an important reference for predicting the new well structure, especially the judgment of wellbore trajectory of complex wellbore structures such as extended reach wells, horizontal wells, deep wells and high deep wells of coalbed methane, and the prediction of downhole dynamics results.

Sub-surface Damage of Ultra-Thin Monocrystalline Silicon Wafer Induced by Dry Polishing

Xundi Zhang,Chenlin Yang,Yumei Zhang,Anmin Hu,Ming Li,Liming Gao,Huiqin Ling,Tao Hang 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.4

Ultra-thin wafer fabrication has become a hot spot in recent years with the growing demand for small size and high performance electronic devices. However, far less research focused on the damage behavior in ultra-thin wafer. In this work, 300 mm diameter silicon wafer was thinned to 6 µm thick by grinding plus ultra-precision dry polishing. The damage behavior before and after the dry polishing was discussed. Mechanical and surface analysis showed that the dry polishing process can help improve the strength and surface uniformity of ultra-thin wafer by removing high pressure phase and micro cracks. Series of nano beam diffraction patterns revealed the stress induced by the thinning process only existed in surface. High resolution transmission electron microscopy images analyzed by geometric phase approach indicated that surface dislocations can move across the wafer and reached bottom device layers during the dry polishing, increasing the risk of electrical deterioration. The findings are of great significance to the study on process optimization of ultra-thin wafer and provide insights into the reliability of advanced electronic packaging.

NUCLEATION AND GRAIN-GROWTH MODEL FOR REDUCTION OF ACICULATE ULTRAFINE ${alpha}$-$Fe_2O_3$ PARTICLES

Li, Chunzhong,Hong, Zhifu,Zhu, Yihua,Hu, Liming 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.2 No.4

By use of temperature programmed reduction technology, the kinetics of aciculate ultrafine ${alpha}$-F${e_2}{O_3}$</T powder are studied and the optimum conditions of the reduction process are investigated. From this study the kinetic equation can be written as $rac{d{alpha}}{d1}$=9.003${ imes}{10^3}$ exp($rac{-72.66{ imes}{10^3}}{RT}$)(1-${alpha}$)${alpha}^{0.54}$ this equation fits well with experiment results at 570-720K, and the reduction rate of oxide at the surface of the particles increases and the reduction rate of oxide inner the particles decreases with increasing the degree of ${alpha}$-F${e_2}{O_3}$</T eduction. The optimum temperature for magnetic powder preparation is 630-670K.

Effect of Bond Linkage on In vitro Drug Release and Anti-HIV Activity of Chitosan-Stavudine Conjugates

Rong Zeng,Renzhong Qiao,Zehu Wang,Hongran Wang,Liqiang Chen,Lin Yang,Liming Hu,Zelin Li 한국고분자학회 2012 Macromolecular Research Vol.20 No.4

Two kinds of chitosan-stavudine (d4T) conjugates, chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate (Cs-P-d4T) with a phosphoramide linkage and chitosan-5'-O-succinyl-d4T conjugate (Cs-S-d4T) with a succinic spacer, were synthesized using an Atherton-Todd reaction and carbodiimide coupling reaction, respectively, and then structurally characterized. Their in vitro drug release behaviors and anti-human immunodeficiency virus (HIV) activity were investigated and compared. Both of the chitosan-d4T conjugates more strongly prefer to release corresponding d4T derivatives rather than free d4T in a prolonged manner but have different hydrolysis routes. The anti-HIV activity and cytotoxicity evaluated in the MT4 cell line revealed that the anti-HIV selectivity index was in the following order: Cs-P-d4T > d4T >> Cs-S-d4T since the released d4T-5'-(O-isopropyl) monophosphate from Cs-P-d4T can bypass the rate-limiting bottleneck of nucleoside phosphorylation, while the released 5'-O-succinyl-d4T from Cs-Sd4T has to be hydrolyzed to d4T and then successively phosphorylated to its active form to exert antiviral activity. The results suggested that constructing a chitosan-nucleoside reverse transcriptase inhibitor (NRTI) conjugate with a phosphoramide linkage may be an efficient approach for improving NRTI therapy efficacy in antiretroviral treatment.