Novel Water-Air Circulation Quenching Process for AISI 4140 Steel

Liyun Zheng,Dawei Zheng1,Lixin Zhao,Lihui Wang,Kai Zhang 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6

AISI 4140 steel is usually used after quenching and tempering. During the heat treatment process in industry production, there are some problems, such as quenching cracks, related to water-cooling and low hardness due to oil quenching. A water-air circulation quenching process can solve the problems of quenching cracks with water and the high cost quenching with oil, which is flammable, unsafe and not enough to obtain the required hardness. The control of the water-cooling and air-cooling time is a key factor in the process. This paper focuses on the quenching temperature, water-air cycle time and cycle index to prevent cracking for AISI 4140 steel. The optimum heat treatment parameters to achieve a good match of the strength and toughness of AISI 4140 steel were obtained by repeated adjustment of the water-air circulation quenching process parameters. The tensile strength, Charpy impact energy at -10 °C and hardness of the heat treated AISI 4140 steel after quenching and tempering were approximately 1098 MPa, 67.5 J and 316 HB, respectively.

Effects of Root Pruning on Adventitious Root Formation, Enzyme Activities, and Hormone Levels in Paeonia suffruticosa ‘Fengdanbai’ Seedlings

Zheng Wang,Gege Su,Songlin He,Liyun Shi,Dan He,Wenqian Shang,Dajuan Yang 한국원예학회 2021 원예과학기술지 Vol.39 No.1

Root pruning during early root development can optimize the root structure of woody plants. To determine the effects of root pruning on tree peony (Paeonia suffruticosa), seedlings of the tree peony cultivar ‘Fengdanbai’ were subjected to varying degrees or different styles of root pruning. Various indexes were analyzed, including the anatomical structure of the root, root vitality, the activity levels of antioxidant enzymes, and the contents of endogenous hormones and their ratios. Comprehensive morphological observation showed that pruning freshly germinated roots that are 3 cm long by 1/3 (i.e., removing 1 cm) yielded the greatest rooting rate (90%), lateral root initiation (2.34 per seedling), and subsequent growth. Analysis of physiological and biochemical indicators during the critical rooting period (3-5 days after root pruning) showed that the levels of superoxide dismutase and abscisic acid (ABA) were decreased, while the oxidase activities of peroxidase, polyphenol oxidase, and indole acetate oxidase and the contents of the endogenous hormones indole acetic acid (IAA), gibberellin (GA3), and zeatin (ZT) were increased. IAA plays a key role in the process of adventitious root formation and the ratios of IAA/GA3, IAA/ABA, and IAA/ZT reflect endogenous hormone homeostasis during adventitious root formation. IAA/ABA and IAA/ZT showed higher values in the pruned roots compared to the control roots, which favor adventitious root induction and elongation. These results provide a basis for the study of adventitious root formation in tree peony.

Effect of drought stress on shoot growth and physiological response in the cut rose ‘charming black’ at different developmental stages

Liyun Shi,Zheng Wang,김완순 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.1

To investigate the responses of the cut rose ‘Charming Black’ to drought stress at diff erent growth stages, we defi ned fi vestages of fl owering and shoot development defi ned from initiation of the axillary bud to full complement of the fl oral parts. Drought stress was applied from earliest bud break (stage 1) to fl oral bud appearance (stage 5). After the stage of treatment,irrigation was restored to normal levels. Results showed that rose plant growth was not only infl uenced by the environmentbut also by diff erent stages of fl oral bud appearance. The stem length as well as the time it took to reach diff erent stages ofrose development was infl uenced by the applied irrigation and supplemental lighting conditions. Drought stress did not havenegative eff ects on the quality of the fl ower at stage 1. Drought stress reduced the vegetative growth phase and promotedfl owering in the early stages (2–3), and signifi cantly decreased shoot length, shoot weight and leaf area. However, at thestage prior to fl ower appearance (stage 5) drought stress was more severe. The most damage was accompanied by malformedfl oral buds that had shorter petal length and distorted petals. Furthermore, photosynthesis was negatively aff ected by droughtstress at stage 5, even after re-irrigation, for which this negative eff ect could not be compensated.

Influence of Nocturnal Supplemental Lighting and Different Irrigation Regimes on Vase Life and Vase Performance of the Hybrid Rose ‘Charming Black’

Liyun Shi,Songlin He,Zheng Wang,Wan Soon Kim 한국원예학회 2021 원예과학기술지 Vol.39 No.1

Preharvest conditions, including photoperiod and irrigation regime, affect the keeping quality of long stem roses (Rosa x hybrida). Rose plants of the cultivar ‘Charming Black’ were subjected to four different treatments to investigate how nocturnal supplemental lighting and different irrigation regimes influence post-harvest performance. Vase life, ornamental quality, water balance, petal color, vacuolar pH, soluble sugar content, and soluble protein content were investigated in this study. Treatment with nocturnal supplemental lighting extended the vase life and increased the daily ornamental value in cut roses. In addition, flowers grown under nocturnal supplemental lighting and without irrigation had significantly improved flower color and ornamental value and the highest values for soluble sugar content and soluble protein content. Withholding irrigation under supplemental lighting promoted maintenance of the water balance, which prolonged the vase life of the cut flowers. This study illustrates that supplemental lighting is helpful in extending the vase life of cut roses and that a non-irrigation regime under supplemental lighting results in the most promising physiological and biochemical responses.

The role of slab water content during supplemental lighting on shoot growth and physiological response of cut rose ‘Charming Black’

Liyun Shi,Zheng Wang,김완순 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.3

The critical water content in slab, and eff ects of drought on shoot growth and gas exchange characteristics of the cut rose‘Charming Black’ were investigated. Four diff erent irrigation regimes were applied to rose plants during supplementallighting (90 μmol m −2 s −1 PAR). Water content in slab was controlled as 80%, 60%, 40%, and 20% in T1, T2, T3, and T4,respectively. No signifi cant diff erence between T1 and T2 was found when water content in slab was above 60%. However,reduction in water use effi ciency has been observed with the decline of water content in slab. When the water content droppedbelow 60% in slab, the shoot growth rate decreased, and a signifi cant reduction of 30% and 38% in shoot growth, 44% and51% in shoot weight, and 34% and 56% in leaf area have been observed under T3 and T4 respectively. Also, petal lengthand diameter of fl oral buds were hampered due to the water defi cit. Lowest net CO 2 assimilation rate occurred at the lowestwater content in slab (20%). Besides, T3 (40%) also caused a signifi cant reduction (63%) in photosynthesis. Sigmoid functionwas simulated to fi nd the fraction of total available water that crop can extract from root zone without suff ering fromdrought stress: the fraction is 0.42. Meanwhile, critical water content was calculated as 46.6%. This study showed that whenthe water content in slab was below the critical water content, drought stress occurred.

Effects of Different Sucrose Concentrations in the Culture Medium on the Growth of Colored Zantedeschia In Vitro under CO2 Enrichment Conditions

Zheng Wang,Yinglong Song,Liyun Shi,Yuzhen Guo,Wenqian Shang,Dan He,Song Lin He 한국화훼학회 2016 화훼연구 Vol.24 No.2

Carbon source, an essential nutrient for plant growth, mainly includes exogenous sugar and CO2 of the environment in vitro. Therefore, the exogenous sugar and CO2 of the environment make the important roles in tissue culture. The aim of this study is to investigate the effects of different sugar concentrations (0, 10, 15 and 30 g·L-1) on the growth of colored Zantedeschia in vitro under certain CO2 concentration and explore the optimal sugar concentration. The plantlets in vitro of colored Zantedeschia had the largest root number, root weight, and root vigor under 0 g·L-1 (sugar-free culture) treatment. And they had the largest plant height, leaf length and leaf chlorophyll content, but p oor r oot v igor under 3 0 g·L-1 sugar. This study indicated that the optimal condition for proliferation and seedling culture of colored Zantedeschia plantlets in vitro was MS medium with 30 g·L-1 sugar, and the suitable medium for rooting culture and transplanting of colored Zantedeschia was MS medium with sugar-free culture under CO2 enrichment condition.

Protein Associated with Adventitious Root Induction Analysis of Tree Peony (Paeonia suffruticosa Andr.) Plantlets In Vitro by Two-dimensional Electrophoresis and Mass Spectrometry

Dandan Zhang,Zheng Wang,Liyun Shi,Wenqian Shang,Zhenzhu Fu,Dan He,Song Lin He 한국화훼학회 2016 화훼연구 Vol.24 No.2

In the present study, the plantlets in vitro of Paeonia suffruticosa ‘Wu Long Peng Sheng’ were used as laboratory materials. The proteome during adventitious root induction process was investigated to sift the related proteins by two-dimensional electrophoresis and mass spectrometry. The results indicated that the protein spots were concentrated in the acidity gel region (pH 4 - 7) and the spots number had a dynamic change ranged from 373 to 462 at the process of root induction (0 – 7 d). 8 spots significantly changed were analyzed with a mass spectrometer and identified using associated software and databases. The peptide information of the 8 spots was similar to the ATP synthase β-subunit of P. suffruticosa (Spots 1 - 4 and 8), P. tenuifolia (Spots 5), P. californica (Spot 6) and P. brownie ( Spots 7) r espectiv ely. T he expression levels of protein spots 1, 4, 5, 6 and 7 was dramatically downregulated, and that of protein spots 2 and 3 had a slightly opposite tendency on the 3rd day. The obviously decreased period is particularly interesting as it was consistent with the induction period of adventitious root primordial of tree peony plantlet in vitro. The ATP synthase β-subunit could be consumed for assembling the ATP synthase in order to supply energy to the rooting process. Therefore, we speculated that the ATP synthase β-subunit was involved in adventitious root initiation of tree peony plantlets in vitro and we expect that further studies should be carried out in order to export its action mechanism.

LED-Supplied Red and Blue Light Alters the Growth, Antioxidant Status, and Photochemical Potential of in Vitro-Grown Gerbera jamesonii Plantlets

Xinya Meng,Zheng Wang,Song Lin He,Liyun Shi,Yinglong Song,Xueyuan Lou,Dan He 한국원예학회 2019 원예과학기술지 Vol.37 No.4

Light is one of the most important environmental factors influencing plant growth and development. Light-emitting diodes (LEDs) are are a promising alternative to conventional light sources for planttissue cultures. Combined red (R) and blue (B) LEDs are suitable for the production of many plantspecies. However, few studies have examined the effects of different R:B ratios on Gerberajamesonii under controlled conditions. G. jamesonii plantlets were grown in controlled conditionsunder different ratios of discreet and blue light wavelengths provided by programmable LEDs. Theeffects of the different LED treatments on various morphological indices, photosynthetic parameters,soluble sugar and protein contents, and antioxidant enzyme activities were analyzed. Growth undermonochromatic red light resulted in the tallest plantlets and longest stomata, and most promotedsoluble content and intercellular CO2 concentration (Ci). Growth under monochromatic blue lightpromoted the highest levels of soluble protein, chlorophyll a (chlorophyll a (Chl a), and chlorophyllb (chlorophyll b (Chl b). An R:B ratio of 6:4 was the ideal LED treatment for enhancing leaf length,root length, and peroxidase activity. Growth under R:B = 7:3 promoted the number of leaves, leafwidth, number of roots, superoxide dismutase, and catalase activities, chlorophyll synthesis, and theaccumulation of Chl a and Chl b and led to the highest fluorescence parameters. With the exceptionof three physiological indicators, other indicators growth under R:B = 7:3 were better than underother tested ratios, implying that R:B = 7:3 represents the ideal LED treatment for improving G. jamesonii growth and photosynthetic activities under controlled conditions.

Endogenous hormone levels and activities of IAA-modifying enzymes during adventitious rooting of tree peony cuttings and grafted scions

Xinya Meng,Zheng Wang,Song Lin He,Liyun Shi,Yinglong Song,Xueyuan Lou,Dan He 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.2

During rooting of both cuttings and grafted scions of tree peony ( Paeonia suff ruticosa Andr.) cultivar ‘Fengdanbai’, the anatomicalstructure, the contents of endogenous hormones (indole acetic acid, IAA; zeatin, ZT; gibberellin, GA 3 ; and abscisicacid, ABA), and the activities of IAA oxidase (IAAO), peroxidase (POD), and polyphenol oxidase (PPO) were observed. Theresults showed that the rooting processes in cuttings and grafted scions were similar, but that the critical period of rootingin cuttings was earlier than in grafts (cuttings: 18–20 days; scions: 38–40 days). IAA content showed a direct correlationwith rooting, with the peak value appearing as the adventitious roots were breaking through the epidermis in both cuttingsand grafts (cuttings: 20 days; scions: 38 days). ZT and GA 3 promoted adventitious rooting, and ABA inhibited it. The peakvalues of the IAA:ABA and IAA:ZT ratios appeared at the same time as the IAA peak (cuttings: 20 days; scions: 38 days),which indicated that these values were closely related to the occurrence of adventitious roots. Changes in the activitiesof IAAO, POD, and PPO, which modify IAA levels, indicated that there were no direct relationships between these threeenzymes and adventitious root formation in cuttings or grafts. These results provide a basis for further study of adventitiousroot formation in the ornamental tree peony.

The Microstructure and Magnetic Properties of Melt-Spun CeFeB Ribbons with Varying Ce Content

Xuchao Wang,Minggang Zhu,Wei Li,Liyun Zheng,Dongliang Zhao,Xiao Du,An Du 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.1

The microstructural and magnetic properties of melt-spun ribbons with thecomposition (CexNd100-x)30FebalCo4Ga0.2B0.92 (where x = 50, 60, 70, 80, and 90)were investigated. The ribbons were examined with Scanning ElectronMicroscopy (SEM), Transmission Electron Microscopy (TEM), and VibratingSample Magnetometry (VSM). It was found that the grain size of the ribbons ison the nanometer scale, and the grain size decreases with decreasing Ce content. The magnetic hysteresis loops showed that the magnetic properties of theribbons gradually deteriorated with increasing Ce content. This is because themagnetic polarization (Js) and magnetocrystalline anisotropy field (HA) ofCe2Fe14B are smaller than those of Nd2Fe14B. Furthermore, from the initialmagnetization curve it was found that increasing the Ce content changes thecoercive force mechanism to the nucleation mechanism. When Ce contentaccounts for 90% of total rare earth metals, the coercive force mechanismmainly appears to be a nucleation mechanism.