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Heterocyclic Aromatic Amines in Meat Products Consumed in China
Han Pan,Zhenyu Wang,Haitao Guo,Na Ni,Dequan Zhang 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.6
Heterocyclic aromatic amines (HAAs) formedin cooked muscle foods are recognized as mutagenic andcarcinogenic compounds. A total of 9 nine HAAs wereanalyzed in 34 meat products consumed in China. The totalHAAs content in all meat products ranged from 4.14 to108.80 ng/g. Dry and sauced meats contained higherconcentration of total HAAs than other kinds of meatproducts. Samples from East and Northwest China showedhigher concentrations of total HAAs than samples fromother regions. The most common specific HAAs, harmanand norharman, were detected in all meat samples at levelsof 1.09-63.97 and 1.19-62.30 ng/g, respectively. Concentrationsof MeIQx, PhIP, 4, 8-DiMeIQx, and AαC were muchlower. MeAαC (n=8), IQ (n=15), and Trp-P-2 (n=23) weredetected in some samples.
Tuning the Pd-catalyzed electroreduction of CO<sub>2</sub> to CO with reduced overpotential
Han, Zishan,Choi, Changhyeok,Tao, Hengcong,Fan, Qun,Gao, Yuannan,Liu, Shizhen,Robertson, Alex W.,Hong, Song,Jung, Yousung,Sun, Zhenyu The Royal Society of Chemistry 2018 Catalysis Science & Technology Vol.8 No.15
<P>Developing selective and efficient catalysts is highly desirable for electrochemical CO2 reduction (ECR) to fuels and chemicals. Pd can strongly bind *COOH but weakly bind *CO, thus resulting in CO as a product. However, proton reduction also occurs severely on the surface of Pd, leading to low CO selectivity. Here we found that the ECR to CO can be greatly enhanced by controlling the Pd-ceria interface and doping with tellurium atoms. Notably, a very high mass activity of 92 mA mgPd<SUP>−1</SUP> (at 1.0 V <I>vs.</I> reversible hydrogen electrode) for CO formation was achieved, significantly surpassing previously reported Pd catalysts (35 mA mgPd<SUP>−1</SUP> at −1.0 V). The Pd catalysts comprising CeOx displayed more positive onset potentials than the Pd catalysts in the absence of CeOx, enabling ECR to CO at −0.6 V (<I>vs.</I> RHE). The modified Pd catalyst also afforded an unprecedented CO faradaic efficiency of over 84% at a low Pd loading (@@<@@3 wt%). Density functional theory calculations revealed that the Pd atoms located between the Te dopant and CeO2 promoted CO formation, thus improving CO2 conversion efficiency.</P>
Novel chemical route for atomic layer deposition of MoS2 thin film on SiO2/Si substrate.
Jin, Zhenyu,Shin, Seokhee,Kwon, Do Hyun,Han, Seung-Joo,Min, Yo-Sep RSC Pub 2014 Nanoscale Vol.6 No.23
<P>Recently MoS2 with a two-dimensional layered structure has attracted great attention as an emerging material for electronics and catalysis applications. Although atomic layer deposition (ALD) is well-known as a special modification of chemical vapor deposition in order to grow a thin film in a manner of layer-by-layer, there is little literature on ALD of MoS2 due to a lack of suitable chemistry. Here we report MoS2 growth by ALD using molybdenum hexacarbonyl and dimethyldisulfide as Mo and S precursors, respectively. MoS2 can be directly grown on a SiO2/Si substrate at 100 C via the novel chemical route. Although the as-grown films are shown to be amorphous in X-ray diffraction analysis, they clearly show characteristic Raman modes (E(1)2g and A1g) of 2H-MoS2 with a trigonal prismatic arrangement of S-Mo-S units. After annealing at 900 C for 5 min under Ar atmosphere, the film is crystallized for MoS2 layers to be aligned with its basal plane parallel to the substrate.</P>
Haitao Guo,Zhenyu Wang,Han Pan,Xin Li,Li Chen,Weili Rao,Yuan Gao,Dequan Zhang 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.3
Different amounts of the potent mutagenic and/or carcinogenic heterocyclic aromatic amines (HAAs) areformed in muscle-based foods under different cookingmethods. HAAs (9 varieties) in lamb patties cooked usingtraditional Chinese cooking methods (roasting, frying, panfrying,and stewing in seasonings) were investigated. Thetotal HAAs contents in roasted, fried, pan-fried, and stewedpatties were 4.39-123.15 ng/g, 3.59-43.24 ng/g, 0.71-10.05ng/g, and 51.07-120.32 ng/g, respectively. Amounts of HAAsincreased as cooking time increased. 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) was the dominantHAAs in deep roasted and fried samples, while 1-methyl-9H-pyrido [3,4-b] indole (Harman) and 9H-pyrido [3,4-b]indole (Norharman) were the main HAAs in pan-fried andstewed samples. Types and contents of HAAs formed atdifferent cooking times using different methods are unique. Stewing in seasoning generated a higher HAAs contentthan the high-temperature cooking methods roasting,frying, and pan-frying.
Yue Yin,Xinyu Che,Zhenyu Li,Jinlong Li,Qinghua Han 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.6
Two micromechanical fracture models, void growth model (VGM) and stress modifi ed critical strain (SMCS) model, were adopted to distinguish the failure mechanism of welded hollow spherical (WHS) joints under axial load based on FE analysis. Ductile fracture was successfully predicted for WHS joints under axial tension. The predicted fracture location is at the weld toe between WHS joints and circular hollow section members, which is consistent with corresponding test results. The predicted fracture load is lower than the peak load on the load–displacement curve, which indicates that the failure mechanism of WHS joints under axial tension is fracture due to inadequate strength and the fracture load should be taken as the ultimate load bearing capacity of the joints. A simplifi ed SMCS model was proposed and verifi ed for ductile fracture prediction of WHS joints under axial tension. Micromechanical fracture analysis was also conducted on WHS joints under axial compression. It was obtained by both VGM and SMCS model that no fracture would occur before the load reached its peak value, the reason of which was discussed by tracing the variation of the equivalent plastic stain and stress triaxiality at the potential location of fracture. Therefore, the failure mechanism of WHS joints under axial compression is losing stability with the depression of the sphere cap and the peak load on the load–displacement curve should be taken as the ultimate load bearing capacity of WHS joints.
Choudhury, Aaheli Roy,Ju, Zhenyu,Djojosubroto, Meta W,Schienke, Andrea,Lechel, Andre,Schaetzlein, Sonja,Jiang, Hong,Stepczynska, Anna,Wang, Chunfang,Buer, Jan,Lee, Han-Woong,von Zglinicki, Thomas,Gans Nature Pub. Co 2007 Nature genetics Vol.39 No.1
Telomere shortening limits the proliferative lifespan of human cells by activation of DNA damage pathways, including upregulation of the cell cycle inhibitor p21 (encoded by Cdkn1a, also known as Cip1 and Waf1)) (refs. 1–5). Telomere shortening in response to mutation of the gene encoding telomerase is associated with impaired organ maintenance and shortened lifespan in humans and in mice. The in vivo function of p21 in the context of telomere dysfunction is unknown. Here we show that deletion of p21 prolongs the lifespan of telomerase-deficient mice with dysfunctional telomeres. p21 deletion improved hematolymphopoiesis and the maintenance of intestinal epithelia without rescuing telomere function. Moreover, deletion of p21 rescued proliferation of intestinal progenitor cells and improved the repopulation capacity and self-renewal of hematopoietic stem cells from mice with dysfunctional telomeres. In these mice, apoptotic responses remained intact, and p21 deletion did not accelerate chromosomal instability or cancer formation. This study provides experimental evidence that telomere dysfunction induces p21-dependent checkpoints in vivo that can limit longevity at the organismal level.
Ferroptosis: A Novel Anti-tumor Action for Cisplatin
Jipeng Guo,Bingfei Xu,Qi Han,Hongxia Zhou,Yun Xia,Chongwen Gong,Xiaofang Dai,Zhenyu Li,Gang Wu 대한암학회 2018 Cancer Research and Treatment Vol.50 No.2
Purpose Ferroptosis is a new mode of regulated cell death, which is completely distinct from other cell death modes based on morphological, biochemical, and genetic criteria. This study evaluated the therapeutic role of ferroptosis in classic chemotherapy drugs, including the underlying mechanism. Materials and Methods Cell viability was detected by using the methylthiazoltetrazlium dye uptake method. RNAi was used to knockout iron-responsive element binding protein 2, and polymerase chain reaction, western blot was used to evaluate the efficiency. Intracellular reduced glutathione level and glutathione peroxidases activity were determined by related assay kit. Intracellular reactive oxygen species levels were determined by flow cytometry. Electron microscopy was used to observe ultrastructure changes in cell. Results Among five chemotherapeutic drugs screened in this study, cisplatin was found to be an inducer for both ferroptosis and apoptosis in A549 and HCT116 cells. The depletion of reduced glutathione caused by cisplatin and the inactivation of glutathione peroxidase played the vital role in the underlying mechanism. Besides, combination therapy of cisplatin and erastin showed significant synergistic effect on their anti-tumor activity. Conclusion Ferroptosis had great potential to become a new approach in anti-tumor therapies and make up for some classic drugs, which open up a new way for their utility in clinic.
Tao, Hengcong,Sun, Xiaofu,Back, Seoin,Han, Zishan,Zhu, Qinggong,Robertson, Alex ,W.,Ma, Tao,Fan, Qun,Han, Buxing,Jung, Yousung,Sun, Zhenyu Royal Society of Chemistry 2018 Chemical Science Vol.9 No.2
<▼1><P>The doping of Pd with a small amount of Te can selectively convert CO<SUB>2</SUB> to CO with a low overpotential.</P></▼1><▼2><P>Designing highly selective and energy-efficient electrocatalysts to minimize the competitive hydrogen evolution reaction in the electrochemical reduction of aqueous CO<SUB>2</SUB> remains a challenge. In this study, we report that doping Pd with a small amount of Te could selectively convert CO<SUB>2</SUB> to CO with a low overpotential. The PdTe/few-layer graphene (FLG) catalyst with a Pd/Te molar ratio of 1 : 0.05 displayed a maximum CO faradaic efficiency of about 90% at –0.8 V (<I>vs.</I> a reversible hydrogen electrode, RHE), CO partial current density of 4.4 mA cm<SUP>–2</SUP>, and CO formation turnover frequency of 0.14 s<SUP>–1</SUP> at –1.0 V (<I>vs.</I> a RHE), which were 3.7-, 4.3-, and 10-fold higher than those of a Pd/FLG catalyst, respectively. Density functional calculations showed that Te adatoms preferentially bind at the terrace sites of Pd, thereby suppressing undesired hydrogen evolution, whereas CO<SUB>2</SUB> adsorption and activation occurred on the high index sites of Pd to produce CO.</P></▼2>