Fe₃O₄ magnetic nanoparticles provide a novel alternative strategy for Staphylococcus aureus bone infection

Youliang, Ren,Jin, Yang,Jinghui, Zhang,Xiao, Yang,Lei, Shi,Dajing, Guo,Yuanyi, Zheng,Haitao, Ran,Zhongliang, Deng,Lei, Chu Techno-Press 2022 Advances in nano research Vol.13 No.6

Due to its biofilm formation and colonization of the osteocyte-lacuno canalicular network (OLCN), Staphylococcus aureus (S.aureus) implant-associated bone infection (SIABI) is difficult to cure thoroughly, and may occur recurrently subsequently after a long period dormant. It is essential to explore an alternative therapeutic strategy that can eradicate the pathogens in the infected foci. To address this, the polymethylmethacrylate (PMMA) bone cement and Fe3O4 nanoparticles compound cylinder were developed as implants based on their size and mechanical properties for the alternative magnetic field (AMF) induced thermal ablation, The PMMA mixed with optimized 2% Fe₃O₄ nanoparticles showed an excellent antibacterial efficacy in vitro. It was evaluated by the CFU, CT scan and histopathological staining on a rabbit 1-stage transtibial screw model. The results showed that on week 7, the CFU of infected soft tissue and implants, and the white blood cells (WBCs) of the PMMA+2% Fe₃O₄+AMF group decreased significantly from their controls (p<0.05). PMMA+2% Fe₃O₄+AMF group did not observe bone resorption, periosteal reaction, and infectious reactive bone formation by CT images. Further histopathological H&E and Gram Staining confirmed there was no obvious inflammatory cell infiltration, neither pathogens residue nor noticeably burn damage around the infected screw channel in the PMMA+2% Fe₃O₄+AMF group. Further investigation of nanoparticle distributions in bone marrow medullary and vital organs of heart, liver, spleen, lung, and kidney. There were no significantly extra Fe₃O₄ nanoparticles were observed in the medullary cavity and all vital organs either. In the current study, PMMA+2% Fe₃O₄+AMF shows promising therapeutic potential for SIABI by providing excellent mechanical support, and promising efficacy of eradicating the residual pathogenic bacteria in bone infected lesions.

Damage detection of bridge structures under moving loads based on CEEMD and PSD sensitivity analysis

Youliang Fang,Jie Xing,Xueting Liu,Danyang Liu,Ying Zhang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

This study proposes a new damage identification method based on a combination of complete ensemble empirical mode decomposition (CEEMD) and power spectrum density (PSD) sensitivity analysis to analyze the acceleration signals of bridge structures under moving loads and achieve damage detection of bridge structures. This paper has achieved the ability to accurately identify the location of cracks and the extent of the damage along a girder with only one acceleration sensor arrangement. The measured data is processed by the CEEMD method. The damage location is revealed by directly examining the first-order intrinsic mode function corresponding to the highest-order pseudo-frequency component, which presents an abrupt change at the damage location. Secondly, after determining the damage location of the bridge, only the power spectrum sensitivity analysis of the crack parameters at the damage location is required to obtain the damage level, avoiding the need to blindly solve the power spectrum for all elements. Finally, the identification method is validated by considering environmental noise, damage locations, and crack depths. The numerical simulation results and experiments for various working conditions show that the method adopted in this paper has good identification capability in identifying cracks in bridge structures.

Life Estimation Correction Model for Offshore Wind Power Transformer Based on Fault Tree Theory

Zhong Hui,Wang Runze,Zhang Li,Sun Youliang 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

The occurrence of fault would greatly afect the remaining life of ofshore wind power transformer. In this paper, the fault events during the operation of the ofshore power transformer were analyzed based on the fault tree theory and the structure function of the transformer fault event was established with considering the operation environment to propose the risk model of transformer fault events. The Monte Carlo method was used to sample the risk model, and the fault risk coefcient of the operation for the ofshore transformer was obtained. Taking the infuence of fault events into the remaining life of the transformer, a Life estimation correction model for ofshore wind power transformer was established, which provides guidance for the optimal design and early fault warning of ofshore transformers.

APPLICATIONS OF CALCIUM PHOSPHATE NANOPARTICLES IN POROUS HARD TISSUE ENGINEERING SCAFFOLDS

ZHE WANG,ZHURONG TANG,FANGZHU QING,YOULIANG HONG,XINGDONG ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.4

To repair bone defects, an important approach is to fabricate tissue engineering sca®olds as substitutions to replace auto-/allologous bones. Currently, processing a biomaterial into threedimensional porous sca®olds and incorporating the calcium phosphate (Ca?P) nanoparticles into sca®olds pro¯le two main characteristics of bone tissue engineering sca®olds. Based on this fact, in this paper we describe the design principles of the Ca?P nanoparticle-based and porous bone tissue engineering sca®olds. Then we summarize a variety of the Ca?P nanoparticle-based sca®olds, including discussion of the integration of the Ca?P nanoparticles with ceramics and polymers, followed by introduction of safety of the Ca?P nanoparticles in scaffolds.

Microstructure of Gear Steels Treated by Shot Peening by X-Ray Line Profile Analysis Method

Pengfei Zhu,Hongzhi Yan,Jibo Zhou,Youliang Zhou,Yin Zhang,Zhi Chen 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

Shot peening is a common surface strengthening process of gears. It can induce compressive residual stress, refine grain size and increase dislocation density. However, there are limited reports on the quantitative analysis of dislocation substructures (type, fraction and arrangement), crystallite size and micro-strain in different crystal planes. To further reveal the microstructure strengthening mechanism of gears during shot peening, X-ray diffraction line profile analysis (XRDLPA) method is applied to study the effect of coverage on the microstructure of the gear steels. The results show that with increasing coverage, the dislocation density is increased from 2.62 × 1016 to 3.37 × 1016 m−2 in the form of screw-edge-mixed type as determined from the dislocation characteristic parameter q. The fraction of edge dislocation increases, whereas the fraction of screw dislocation decreases. The dislocation arrangement parameter M is decreased from 7.1 to 5.6, indicating that the formation of dislocation dipoles or dislocation cells in the surface layer can be further enhanced by increasing coverage. Due to the different degrees of atomic slip, the (200) crystallographic plane exhibits the smallest crystallite size and highest micro-strain, whereas the (222) plane shows the smallest micro-strain and the largest crystallite size. In addition, during shot peening, the enhancement of surface hardness of the gear steels is attributed to the phase transformation strengthening, grain-boundary hardening and dislocation hardening. The surface compressive stress of the gear steels induced by shot peening is affected not only by phase transformation, but also by Bauschinger effect, surface topography, grain refinement and so on.

Numerical Study of Anisotropic Weakening Mechanism and Degree of Non-persistent Open Joint Set on Rock Strength with Particle Flow Code

Jie Cui,Quan Jiang,Shaojun Liu,Xiating Feng,Youliang Zhang,Ying-en Shi 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.3

The strength of a rock cut by non-persistent open joint set is controlled by complex interactions of the joint network and intact rock bridges. An extensive series of uniaxial numerical tests of the particle models are carried out under different joint fabrics and rock compression-tension strength ratios. The test results show joint dip angle is the main factor controlling the overall anisotropic strength characteristics. With joint dip angle increasing, the main failure modes successively appear as splitting failure, block rotation failure, step-path failure, planar failure, and splitting failure. Accordingly, the strength generally shows a trend of decreasing first and then increasing, and the joint dip angle corresponding to the minimum strength is biased towards 0°, usually at 15° − 30°. The damage of rock bridges is mainly controlled by tensile failure, except in planar failure mode. Joint spacing has an impact on the local anisotropic strength characteristics. The joint spacing and persistence ratio jointly control the degree of penetration difficulty of the rock bridges. The compression-tension strength ratio of intact rock uniformly affects the absolute magnitude of the jointed rock strength and does not affect its anisotropic characteristics. Based on the weakening mechanism, an empirical strength formula is established to realize the practical equivalent characterization of the anisotropic weakening degrees of the non-persistent open joint set on the rock strength.

Chemical processing of water-soluble species and formation of secondary organic aerosol in fogs

Kim, Hwajin,Collier, Sonya,Ge, Xinlei,Xu, Jianzhong,Sun, Yele,Jiang, Wenqing,Wang, Youliang,Herckes, Pierre,Zhang, Qi Elsevier 2019 Atmospheric environment Vol.200 No.-

<P><B>Abstract</B></P> <P>A field study on fog chemistry and aqueous-phase processing of aerosol particles was conducted in Fresno, California's San Joaquin Valley (SJV) during wintertime. Fog droplets were collected while interstitial submicron aerosol was characterized in real time using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS). The fog samples were later analyzed using HR-AMS, ion chromatography (IC), and total organic carbon analyzer (TOC). Compared to interstitial aerosol, dissolved solutes in fog waters were composed of higher fractions of ammonium, nitrate, sulfate, methanesulfonic acid, and oxygenated organic compounds, likely due to aqueous formation of secondary species as well as enhanced gas-to-particle partitioning of water-soluble gases under humid conditions. The low-volatility dissolved organic matter in fog water (F-OA) was moderately oxidized with an average oxygen-to-carbon (O/C) ratio of 0.42. The chemical composition of F-OA appeared to be overall similar to that of oxygenated organic component in interstitial aerosol (OOA) and the HR-AMS mass spectra of F-OA and OOA are highly similar (r<SUP>2</SUP> > 0.95). However, there are also significant chemical differences as F-OA appeared to contain a larger fraction of carboxylic functional groups than OOA, indicating enhanced organic acid formation through aqueous-phase reactions. In addition, F-OA was composed of substantially more nitrogen-containing compounds, with an average N/C ratio ∼4 times that of OOA. Most strikingly was that the F-OA spectra showed substantial enhancements of the C<SUB>x</SUB>H<SUB>y</SUB>N<SUB>2</SUB> <SUP>+</SUP> (x ≥ 0; y ≥ 0) ions, which were likely contributed by imidazole- and/or pyrazine-based compounds formed from the aqueous reactions of aldehydes with amino compounds. The results of this study demonstrated that aqueous reactions in atmospheric droplets can significantly modify aerosol composition and contribute to the formation of oxygenated and nitrogen-containing organic compounds in atmospheric aerosol particles. This finding is important for understanding aerosol's effects on human health, air quality, and climate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> HR-AMS study of fog processing of PM1 in San Joaquin Valley of CA during winter. </LI> <LI> Fog waters are enriched of secondary inorganic and organic aerosol species. </LI> <LI> Organic residuals in fog waters (FOM) is moderately oxidized (average O/C = 0.42). </LI> <LI> FOM has more abundant carboxylic acid and organic nitrogen compounds than OOA. </LI> <LI> This is evidence for forming imidazole- or pyrazine-based compounds in fog waters. </LI> </UL> </P>