Analytical and Experimental Studies on All-Steel Buckling Restrained Brace with Double Steel Tubes

Jinhe Gao,Jiahuan Xi,Jiajun Ding,Yuwen Xu,Junwen Zhu,Yi Chang 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

This study proposes a new type of all-steel buckling restrained brace with double steel tubes composed of an inner round steel tube and an outer square steel tube, the inner core adopting a cruciform section and an H-section. These two types of cross-sectional inner cores have larger cross-sectional stiff ness than round bars and better meet the requirement that inner core should be easy to yield but not easy to buckle. In this study, a theoretical design method for designing the proposed BRB in a simplifi ed and optimal way is presented. The assembly scheme, constraint system, and overall structure are defi ned. The quasi-static tests of two brace specimens under a cyclic load are carried out to verify the brace's mechanical performance, axial strain distribution, and energy dissipation capacity. These results show that, relying on these two types of cross-sections, the hysteresis curves of all-steel buckling restrained braces with double-steel tubes are overall in good shape and stable. In addition, its energy dissipation performance is stable without any widespread instability phenomena. Also, the inner core has a stable plastic deformation capacity even after yielding, based on the comparative analysis of axial strain response of each components. Both specimens can meet the requirements of seismic design.

Engineering tumor-specific catalytic nanosystem for NIR-II photothermal-augmented and synergistic starvation/chemodynamic nanotherapy

Shuixiu Zhou,Jiahuan Xu,Yanfei Dai,Yan Wei,Liang Chen,Wei Feng,Yu Chen,Xuejun Ni 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4

Background: As an emerging therapeutic modality, chemodynamic therapy (CDT), converting hydrogen peroxide (H2O2) into highly toxic reactive oxygen species (ROS), has been developed for tumor-specific therapy. However, the deficiency of endogenous H2O2 and high concentration of glutathione (GSH) in the tumor microenvironment (TME) weaken the CDT-based tumor-therapeutic efficacy. Herein, a photothermal-enhanced tumor-specific cascade catalytic nanosystem has been constructed on the basis of glucose oxidase (GOD)-functionalized molybdenum (Mo)-based polyoxometalate (POM) nanoclusters, termed as GOD@POMs. Methods: GOD@POMs were synthesized by a facile one-pot procedure and covalently conjugation. Then, its structure was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). In addition, ultraviolet-visiblenear-infrared (UV-vis-NIR) absorption spectrum and infrared thermal camera were applied to evaluate the catalytic and photothermal performance, respectively. Moreover, to confirm the therapeutic effects in vitro, cell counting kit-8 (CCK-8) assay, live/dead staining and ROS staining were performed. Furthermore, the biosafety of GOD@POMs was investigated via blood routine, blood biochemistry and hematoxylin and eosin (H&E) staining in Kunming mice. Besides, the C6 glioma tumor-bearing mice were constructed to evaluate its anti-tumor effects in vivo and its photoacoustic (PA) imaging capability. Notably, RNA sequencing, H&E, TdT-mediated dUTP nick end labeling (TUNEL) and Ki-67 staining were also conducted to disclose its underlying anti-tumor mechanism. Results: In this multifunctional nanosystem, GOD can effectively catalyze the oxidation of intratumoral glucose into gluconic acid and H2O2, achieving the cancer starvation therapy. Meanwhile, the generated gluconic acid decreases the pH in TME resulting in POM aggregation, which enables PA imaging-guided tumor-specific photothermal therapy (PTT), especially in the second near-infrared (NIR-II) biological window. Importantly, the Mo (VI) sites on POM can be reduced to Mo (V) active sites in accompany with GSH depletion, and then the post-produced Mo (V) transforms in situ overproduced H2O2 into singlet oxygen (1O2) via Russell mechanism, achieving self-enhanced CDT. Moreover, the PTT-triggered local tumor temperature elevation augments the synergistic nanocatalytic-therapeutic efficacy. Conclusions: Consequently, the integration of GOD-induced starvation therapy, H2O2 self-supply/GSH-depletion enhanced Mo-based CDT, and POM aggregation-mediated PTT endow the GOD@POMs with remarkable synergistic anticancer outcomes with neglectable adverse effects.

Effect of surface quality on hydrogen/helium irradiation behavior in tungsten

Hongyu Chen,Qiu Xu,Jiahuan Wang,Peng Li,Julong Yuan,Binghai Lyu,Jinhu Wang,Kazutoshi Tokunaga,Gang Yao,Laima Luo,Yucheng Wu 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6

As the plasma facing material in the nuclear fusion reactor, tungsten has to bear the irradiation impact ofhigh energy particles. The surface quality of tungsten may affect its irradiation resistance, and even affectthe service life of fusion reactor. In this paper, tungsten samples with different surface quality werepolished by mechanical processing, subsequently conducted by D2þ implantation and thermal desorption. D2þ implantation was performed at room temperature (RT) with the irradiation dose of 1 1021D2þ/m2 by 5 keV D2þ ions, and thermal desorption spectroscopy measurements were done from RT to900 K. In addition, He irradiation was also performed by 50 eV Heþ ions energy with the fluxes of5.5 1021 m2s1 and 1.5 1022 m2s1, respectively. Results reveal that the hydrogen/helium irradiation behavior are both related to surface quality. Samples with high surface quality has superior D2þretention behavior with less D2 retained after implantation. However, such samples are more likely togenerate fuzzes on the surface after helium irradiation. Different morphologies (smooth, wavy, pyramids)after helium irradiati

N-Acyl-Homoserine Lactone Quorum Sensing Switch from Acidogenesis to Solventogenesis during the Fermentation Process in Serratia marcescens MG1

( Wensong Jin ),( Hui Lin ),( Huifang Gao ),( Zewang Guo ),( Jiahuan Li ),( Quanming Xu ),( Shujing Sun ),( Kaihui Hu ),( Jung-kul Lee ),( Liaoyuan Zhang ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.4

N-acyl-homoserine lactone quorum sensing (AHL-QS) has been shown to regulate many physiological behaviors in Serratia marcescens MG1. In the current study, the effects of AHL-QS on the biosynthesis of acid and neutral products by S. marcescens MG1 and its isogenic ΔswrI with or without supplementing exogenous N-hexanoyl-L-homoserine lactone (C₆-HSL) were systematically investigated. The results showed that swrI disruption resulted in rapid pH drops from 7.0 to 4.8, which could be restored to wild type by supplementing C₆-HSL. Furthermore, fermentation product analysis indicated that ΔswrI could lead to obvious accumulation for acidogenesis products such as lactic acid and succinic acid, especially excess acetic acid (2.27 g/l) produced at the early stage of fermentation, whereas solventogenesis products by ΔswrI appeared to noticeably decrease by an approximate 30% for acetoin during 32-48 h and by an approximate 20% for 2,3-butanediol during 24-40 h, when compared to those by wild type. Interestingly, the excess acetic acid produced could be removed in an AHL-QS-independent manner. Subsequently, quantitative real-time PCR was used to determine the mRNA expression levels of genes responsible for acidogenesis and solventogenesis and showed consistent results with those of product synthesis. Finally, by close examination of promoter regions of the analyzed genes, four putative luxI box-like motifs were found upstream of genes encoding acetyl-CoA synthase, lactate dehydrogenase, α-acetolactate decarboxylase, and Lys-like regulator. The information from this study provides a novel insight into the roles played by AHL-QS in switching from acidogenesis to solventogenesis in S. marcescens MG1.