Shear strength of match-cast-free dry joint in precast girders

Haibo Jiang,Jiahui Feng,Jie Xiao,Mingzhu Chen,Weibin Liang 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.2

Shear keys in precast concrete segmental bridges (PCSBs) are usually match-casting which is very labour intensive. In this research, an innovative match-casting-free construction was proposed by leaving small gap between the convex and the concave castellated shear keys in the joints of PCSBs. Specimen experiment, shear strength analysis and numerical simulation were conducted, investigating the loading performance of this new type of dry joints, the gap dry joints. Compared with matchcasting joint specimens, it has been found from experiment that shear capacity of gap joint specimens significantly decreased ranging from 17.75% to 42.43% due to only partially constrained and contacted in case of gap dry joints. Through numerical simulation, the effects of bottom contacting location, the heights of the gap and the shear key base were analyzed to investigate strength reduction and methods to enhance shear capacity of gap joint specimens. Numerical results proved that shear capacity of gap dry joints under full contact condition was higher than that under partial contact. In addition, left contact destroyed the integrity of shear keys, resulting in significant strength reduction. Larger shear key base remarkably increased shear capacity of the gap joint. Experimental tests indicated that AASHTO provision underestimated shear capacity of the match-casting dry joint specimens, while the numerical results for the gap dry joint showed that AASHTO provision underestimated shear capacity of full contact specimens, but overestimated that of left contact specimens.

Naphthobistriazole-based wide bandgap donor polymers for efficient non-fullerene organic solar cells: Significant fine-tuning absorption and energy level by backbone fluorination

Tang, Dongsheng,Wan, Jiahui,Xu, Xiaopeng,Lee, Young Woong,Woo, Han Young,Feng, Kui,Peng, Qiang Elsevier 2018 Nano energy Vol.53 No.-

<P><B>Abstract</B></P> <P>In this work, two wide bandgap polymers of PDTT-TZNT and PDTF-TZNT were developed by Stille-coupling of naphtho[1,2-c:5,6-c]bis(2-octyl-[1,2,3]triazole) (TZNT) acceptor unit with bithiophene (DTH) and fluorinated bithiophene (DTF), respectively. These polymers exhibited a wide bandgap over 1.84 eV. The fluorinated PDTF-TZNT had lower highest occupied molecular orbital HOMO level (− 5.24 eV), higher molar absorption coefficient (1.28 × 10<SUP>5</SUP> M<SUP>−1</SUP> cm<SUP>−1</SUP>), and higher molecular packing order. Using a low bandgap 3,9-bis(2-methylene-(5&6-methyl-(3-(1,1-dicyanomethylene)-indanone)))−5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene (IT-M) as the electron acceptor, the PDTF-TZNT:IT-M devices generated a higher power conversion efficiency (PCE) of 10.05%. To make up the weak absorption of above binary blend of PDTF-TZNT:IT-M in the short wavelength region and increase the device performance further, a large bandgap small molecular acceptor of 5,5,10,10,15,15-hexabutyl-2,7,12-tri(4-(3-ethylhexyl-4-oxothiazolidine-2-yl)dimalononitrile-benzothiadiazole)-truxene (meta-TrBRCN) was added as the second acceptor material to fabricate ternary blend PSCs. The meta-TrBRCN could not only expand the absorption range but also fine-tune the blend morphology by stepwise changing its content. When 0.2 of meta-TrBRCN was added, the PCE of PDTF-TZNT:IT-M devices was improved to 11.48%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two novel naphthobistriazole-based wide bandgap donor polymers were successfully synthesized and characterized. </LI> <LI> The introduced fluorine atoms enabled the PDTF-TZNT:IT-M devices to obtain a higher PCE of 10.05%. </LI> <LI> The ternary blend strategy boosted the PCE up to 11.48% in the PDTF-TZNT<SUB>x</SUB>:IT-M<SUB>y</SUB>:meta-TrBRCN<SUB>z</SUB> devices. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Two novel naphthobistriazole-based wide bandgap polymers, PDTH-TZNT and PDTF-TZNT, has been developed for non-fullerene polymer solar cells. The fluorinated PDTF-TZNT exhibited a higher PCE of 10.05% in binary PDTT-FTAZ:IT-M devices. By adding 0.2 of meta-TrBRCN as the second acceptor, the related ternary blend devices exhibited a significantly improved PCE of 11.48%.</P> <P>[DISPLAY OMISSION]</P>

Horizontal Shear Behaviors of Normal Weight and Lightweight Concrete Composite T‑Beams

Zhuangcheng Fang,Haibo Jiang,Airong Liu,Jiahui Feng,Yuanhang Chen 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.5

This paper presents the results of recent research on the interface shear behavior of normal weight and lightweight concrete composite T-beams. In the experimental program 12 beams and necessary control cylinders were tested to provide experimental cases with the variables of interface preparation, clamping stress and lightweight slab concrete strength. Compared with 7 equations developed previously, it has been found that those formulas, especially the ones from current AASHTO and ACI design codes, give a conservative theoretical prediction of horizontal shear capacity of composite T-beams. Based on the experimental results, a more accurate equation was developed to predict the interface shear transfer strength of composite concrete T-beam. By comparing the experimental results of previous beam tests and shear-friction push-off tests for different types of concrete with both rough and smooth interface published in literature, it has been found that the proposed formula is reliable in predicting the horizontal shear strength of concrete composite T-beams.

Effects of dietary marigold extract supplementation on growth performance, pigmentation, antioxidant capacity and meat quality in broiler chickens

Wang, Shuhao,Zhang, Lin,Li, Jiaolong,Cong, Jiahui,Gao, Feng,Zhou, Guanghong Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.1

Objective: This experiment was conducted to investigate the effects of dietary supplementation with marigold extract on growth performance, pigmentation, antioxidant capacity and meat quality in broiler chickens. Methods: A total of 320 one-day-old Arbor Acres chickens were randomly divided into 5 groups with 8 replicates of 8 chickens each. The chickens of control group were fed with basal diet and other experimental groups were fed with basal diet supplemented with 0.075%, 0.15%, 0.30%, and 0.60% marigold extract respectively (the corresponding concentrations of lutein were 15, 30, 60, and 120 mg/kg). Results: The results showed that marigold extract supplementation increased the yellowness values of shank, beak, skin and muscle and the redness ($a^*$) value of thigh muscle (linear, p<0.01). Marigold extract supplementation significantly increased the total antioxidant capacity, and the activities of superoxide dismutase in liver and thigh muscle (linear, p<0.01) and significantly decreased the malondialdehyde contents of liver and thigh muscle (linear, p<0.01). Marigold extract supplementation significantly decreased the drip loss and shear force of thigh muscles (linear, p<0.01). There was no significant effect on growth performance with marigold extract supplementation. Conclusion: In conclusion, dietary supplementation of marigold extract significantly increased the yellowness values of carcass, antioxidant capacity and meat quality in broiler chickens.

Transcriptomic and proteomic profiling revealed global changes in Streptococcus thermophilus during pH-controlled batch fermentations

Yali Qiao,Cong Leng,Gefei Liu,Yanjiao Zhang,Xuepeng Lv,Hongyu Chen,Jiahui Sun,Zhen Feng 한국미생물학회 2019 The journal of microbiology Vol.57 No.9

Understanding global changes of physiological processes at the molecular level during the growth of Streptococcus thermophilus is essential for the rational design of cultivation media and the optimization of bioprocesses. Transcriptomics and proteomics were combined to investigate the global changes at the transcript and protein level during the growth of S. thermophilus. The expression of 1396 genes (FDR ≤ 0.001) and 876 proteins (P < 0.05) changed significantly over time. The most remarkable growth phase dependent changes occurred in the late-lag phase and were related to heterofermentation, glycolysis, peptidoglycan biosynthesis, conversion between amino acids and stress response. The present results could provide theoretical guidance for high-cell-density culture, help design cultivation media, and help attain a high biomass of S. thermophilus.