Dynamic Mechanical Performance of Self-compacting Concrete Containing Crumb Rubber under High Strain Rates

Guo Yang,Xudong Chen,Shengshan Guo,Weihong Xuan 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.8

The parameters of dynamic mechanical performance at high strain rates are of significant importance in the structural designs and numerical simulations. The aim of this paper is to study the strain rate sensitivity of self-compacting rubberized concrete (SCRC) in the dynamic compressive, splitting tensile and bending tests by using the split Hopkinson pressure bar (SHPB) technique. The failure modes, stress-strain curves and dynamic strength changes of SCRC under various loading conditions were also observed. The specific energy absorption, dynamic tensile-compressive strength ratios, and dynamic constitutive model of SCRC with different rubber content were also analyzed. The results indicate that SCRC can exhibit stronger strain rate sensitivity compared to SCC when strain rate is enough high, while the strain rate sensitivity of SCRC is lower than that of SCC at when strain rate is less than a critical value. To understand the strain rate sensitivity of SCRC, dynamic constitutive model (ZWT model) based on nonlinear viscoelastic theory was proposed. For impact toughness, although the specific energy absorption decreases with increasing rubber content, the ratios of tensile strength to compressive strength of SCRC have an increasing tendency when rubber content increases.

Association Between Nasal Colonization of Staphylococcus aureus and Eczema of Multiple Body Sites

Guo Yang,Dou Xia,Chen Xiao-Fan,Huang Cong,Zheng Ying-Jie,Yu Bo 대한천식알레르기학회 2023 Allergy, Asthma & Immunology Research Vol.15 No.5

Purpose: Staphylococcus aureus is the critical pathogenic bacterium of eczema. The relationship between nasal colonization by S. aureus and eczema has not been well studied. We aimed to evaluate the associations between nasal colonization by S. aureus and eczema of multiple body sites, including persistent and ever-reported eczema. We further examined the associations between eczema and different subtypes of S. aureus, that is, methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA). Methods: The real-world data from the US National Health and Nutrition Examination Survey were used. The associations were calculated using survey-weighted multinomial logistic regression models and further calculated in subgroups stratified by demographic factors. Results: In total, 2,941 adults were included. The prevalence rate of S. aureus nasal carriage was significantly higher in adults with persistent hand eczema (51.0%) than in those with ever-reported hand eczema (23.3%) and never eczema (26.9%). S. aureus nasal colonization was associated with an approximately two-fold increased risk of persistent hand eczema (odds ratios ranges in different models: 2.86–3.06) without significant heterogeneity in the association by demographic factors. No significant associations between S. aureus nasal colonization and persistent eczema of other body sites or ever-reported eczema of multiple body sites (including hands) were observed. Furthermore, similar significant association between nasal colonization of MSSA and persistent hand eczema was seen; the association was much stronger (odds ratios ranges in different models: 4.64–6.54) for MRSA, although with borderline significant. Conclusions: Nasal colonization of S. aureus was associated with increased risk of persistent hand eczema. Our findings imply that preventive measures targeting S. aureus for the anterior nares should be considered in preventing and treating eczema.

Simultaneous detection of Salmonella spp., Pseudomonas aeruginosa, Bacillus cereus, and Escherichia coli O157:H7 in environmental water using PMA combined with mPCR

Xie Guoyang,Yu Shuang,Li Wen,Mu Dan,Aguilar Zoraida P.,Xu Hengyi 한국미생물학회 2020 The journal of microbiology Vol.58 No.8

A multiplex polymerase chain reaction (mPCR) with propidium monoazide (PMA) and internal amplification control (IAC) for the simultaneous detection of waterborne pathogens Salmonella spp., Pseudomonas aeruginosa, Bacillus cereus, and Escherichia coli O157:H7, was developed. This PMA-IAC-mPCR assay used four new specific primers based on the genes for invA, ecfX, cesB, and fliC, respectively. A 16S rRNA primer was chosen for IAC to eliminate false negative results. The photosensitive dye, propidium monoazide (PMA) was used to exclude signals from dead bacteria that could lead to false positive results. In pure culture, the limits of detection (LOD) were 101 CFU/ml for P. aeruginosa, 102 CFU/ml for both Salmonella spp. and E. coli O157:H7, and 103 CFU/ml for B. cereus, respectively. In addition, with a 6–8 h enrichment of all four bacteria that were combined in a mixture that was spiked in water sample matrix, the LOD was 3 CFU/ml for Salmonella spp., 7 CFU/ml for E. coli O157:H7, 10 CFU/ml for B. cereus and 2 CFU/ml for P.aeruginosa. This PMA-IAC-mPCR assay holds potential for application in the multiplex assay of waterborne pathogens.

Terahertz Spectral Characteristics of Electrolyte Solutions under Different Magnetic Fields

Siyu Shao,Haiyun Huang,Bo Peng,Guoyang Wang,Ping Ye,Jiahui Wang,Bo Su,Hailin Cui,Cunlin Zhang 한국광학회 2022 Current Optics and Photonics Vol.6 No.3

Microfluidic chips are new devices that can manipulate liquids at the micrometer level, and terahertz (THz) time-domain spectroscopy has good applicability in biochemical detection. The combination of these two technologies can shorten the distance between sample and THz wave, reduce THz wave absorption by water, and more effectively analyze the kinetics of biochemical reactions in aqueous solutions. This study investigates the effects of different external magnetic field intensities on the THz transmission characteristics of deionized water, CuSO 4 , CuCl 2 , (CH 3 COO) 2 Cu, Na 2 SO 4 , NaCl, and CH 3 COONa; the THz spectral intensity of the sample solutions decrease with increasing intensity of the applied magnetic field. Analysis shows that the magnetic field leads to a change in the dipole moment of water molecules in water and electrolyte solutions, which enhances not only the hydrogen-bond networking ability of water but also the hydration around ions in electrolyte solutions, increasing the number of hydrogen bonds. Increasing the intensity of this magnetic field further promotes the hydrogen-bond association between water molecules, weakening the THz transmission intensity of the solution.

Study on fractal model of activated carbon for pore formation

Wang Junzhe,Zhou Anning,Liu Guoyang,Song Zongxing,Ma Chao,Wang Dan 한국탄소학회 2022 Carbon Letters Vol.32 No.3

In view of the activated carbon pore-forming mechanism, the fractal hypothesis of pore interior growth was proposed by optimizing the structure of Sierpinski sponge. Based on the hypothesis and the definition of fractal dimension, the function relationship between the reaction degree, reaction step length, specific surface area and pore volume was deduced, and the pore fractal growth model of activated carbon activation process was established. Semi-coke, apple charcoal and lychee charcoal were used to prepare activated carbon. The pore size distributions of the activated carbons are in accordance with the fractal growth hypothesis. Further, the reaction degree and reaction step length can be determined by the experimental data of pore and surface structure, which verified the feasibility of the pore fractal growth model.

VEGF Promoter Polymorphism Confers an Increased Risk of Pulmonary Arterial Hypertension in a Chinese Population

Yufeng Zhuo,Qingchun Zeng,Peng Zhang,Guoyang Li,Qiang Xie,Ying Cheng 연세대학교의과대학 2017 Yonsei medical journal Vol.58 No.2

Purpose: Evidence on the contribution of genes to the hereditary predisposition to pulmonary arterial hypertension (PAH) is limited. Materials and Methods: In this study, we hypothesized that single nucleotide variants in vascular endothelial growth factor (VEGF) gene may alter gene function and expression and may be associated with PAH risk. Five putatively functional loci (rs699947C>A and rs833061T>C in the promoter, rs3025040C>T, rs10434G>A and rs3025053G>A in the 3’-UTR) in the VEGF gene were genotyped and analyzed in a retrospective study of 587 patients with PAH and 736 healthy subjects from southern China. Results: We found that the rs833061T>C polymorphism was significantly associated with PAH risk, while the other single nucleotidepolymorphisms were not. Compared to carriers with TT genotype, those with rs833061C variant genotype (CT/CC) had an increased risk of PAH (odds ratio=1.47, 95% confidence interval=1.18–1.83, p=0.001). Functional assays indicated that CT/CC variant genotype had significantly higher mRNA levels of VEGF in peripheral blood mononuclear cells than TT genotype (p=0.021). Luciferase reporter assay indicated that having a C allele conferred a significantly higher transcription activity than that with a T allele. Conclusion: Our findings suggest that the functional polymorphism rs833061T>C in VEGF gene promoter modulates VEGF expressionand may be a valuable biomarker for predicting PAH susceptibility.