Study of co-excited green emission of Tb3+, Ce3+ and Gd3+ in yttrium aluminum garnet

Fei Huang,Limin Dong,Hao Wang,Weimin Wang,Yucheng Wang,Zhengyi Fu 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6

YAG : Tb3+, Ce3+, Gd3+ nano-phosphors derived from a sol-gel chemistry have been successfully synthesized and characterized by TG/DTA, XRD, SEM, and spectrometer. The results show that the phosphors have a uniform particle size distribution ranging 30-50 nm. The value of the lattice constant increased with an increase of the Gd3+ content. Tb3+ →Ce3+, Ce3+ →Tb3+ and Gd3+ →Ce3+ energy transfer existed in the co-excited system. The luminescence intensity was controlled by the concentration and ratio of the co-dopants. A small quantity of Gd3+ and Ce3+ evidently increased the green emission (5D4→7F5) of Tb3+. YAG : Tb3+, Ce3+, Gd3+ nano-phosphors derived from a sol-gel chemistry have been successfully synthesized and characterized by TG/DTA, XRD, SEM, and spectrometer. The results show that the phosphors have a uniform particle size distribution ranging 30-50 nm. The value of the lattice constant increased with an increase of the Gd3+ content. Tb3+ →Ce3+, Ce3+ →Tb3+ and Gd3+ →Ce3+ energy transfer existed in the co-excited system. The luminescence intensity was controlled by the concentration and ratio of the co-dopants. A small quantity of Gd3+ and Ce3+ evidently increased the green emission (5D4→7F5) of Tb3+.

Dynamic optimization design of the suspension parameters of car bodymounted equipment via analytical target cascading

Jie Chen,Yangjun Wu,Limin Zhang,Xiaolong He,Shijie Dong 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5

Under dynamic conditions, the dynamic force between the suspended equipment and the car body is substantially increased. This increase not only affects the ride comfort but also substantially raises the likelihood of fatigue damage to the suspended equipment. A multiobjective analytical target cascading (ATC) optimization is proposed to improve the ride comfort of high-speed trains and reduce the vibration of the suspended equipment. A mathematical simulation model of the vehicle equipment system is established, and the acceleration frequency-response function expression of the car body and the suspension system is obtained. The comfort index of the car body and the acceleration root mean square (RMS) of the suspended equipment are calculated by combining the German vertical irregular track spectrum and the comfort filter function. Meanwhile, the ATC method is used to optimize the car body comfort index and the acceleration RMS of the underframe suspended equipment. Then, the availability of the optimization method is evaluated via numerical simulation. Compared with the original suspension scheme of the underframe equipment, when the running speed of the vehicle is 300 km/h, the RMS value of the vibrational acceleration of the underframe equipment after optimization decreases by 19.9 %, and the ride comfort indexes at the car body center and above the front and rear bogies are improved by 6.4 %, 0.1 %, and 1.1 %, respectively. Simulation results demonstrate that ATC optimization can improve the railway vehicle ride comfort and reduce the vibration of the suspended equipment. This paper provides a new approach to the suspension parameter design of equipment.

Study on the Recycling of Nuclear Graphite after Micro-Oxidation

Juan Liu,Chen Wang,Limin Dong,Tongxiang Liang 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.1

In this paper, a feasible strategy for the recycling of nuclear graphite is reported, based onthe formation mechanism and the removal of carbon-14 by micro-oxidation. We investigatedwhether ground micro-oxidation graphite could be used as a filler to make newrecycled graphite and which graphite/pitch coke ratio will give the recycled graphiteoutstanding properties (e.g., apparent density, flexural strength, compressive strength,and tensile strength). According to the existing properties of nuclear graphite, the ratio ofgraphite to pitch coke should not exceed 3. The recycled reactor graphite has been provensuperior in density, strength, and thermal conductivity. The micro-oxidation processenhances the strength of the recycled graphite because there are more pores andunsmooth surfaces on the oxidized graphite particles, which is beneficial for the access ofthe pitch binder and leads to efficient joint adhesion among the graphite particles.

Study on the Recycling of Nuclear Graphite after Micro-Oxidation

Liu, Juan,Wang, Chen,Dong, Limin,Liang, Tongxiang Korean Nuclear Society 2016 Nuclear Engineering and Technology Vol.48 No.1

In this paper, a feasible strategy for the recycling of nuclear graphite is reported, based on the formation mechanism and the removal of carbon-14 by micro-oxidation. We investigated whether ground micro-oxidation graphite could be used as a filler to make new recycled graphite and which graphite/pitch coke ratio will give the recycled graphite outstanding properties (e.g., apparent density, flexural strength, compressive strength, and tensile strength). According to the existing properties of nuclear graphite, the ratio of graphite to pitch coke should not exceed 3. The recycled reactor graphite has been proven superior in density, strength, and thermal conductivity. The micro-oxidation process enhances the strength of the recycled graphite because there are more pores and unsmooth surfaces on the oxidized graphite particles, which is beneficial for the access of the pitch binder and leads to efficient joint adhesion among the graphite particles.

Piezo-activated guided wave propagation and interaction with damage in tubular structures

Ye Lu,Lin Ye,Dong Wang,Limin Zhou,Li Cheng 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.7

This study investigated propagation characteristics of piezo-activated guided waves in an aluminium rectangular-section tube for the purpose of damage identification. Changes in propagating velocity and amplitude of the first wave packet in acquired signals were observed in the frequency range from 50 to 250 kHz. The difference in guided wave propagation between rectangular- and circular-section tubes was examined using finite element simulation, demonstrating a great challenge in interpretation of guided wave signals in rectangular-section tubes. An active sensor network, consisting of nine PZT elements bonded on different surfaces of the tube, was configured to collect the wave signals scattered from through-thickness holes of different diameters. It was found that guided waves were capable of propagating across the sharp tube curvatures while retaining sensitivity to damage, even that not located on the surfaces where actuators/sensors were attached. Signal correlation between the intact and damaged structures was evaluated with the assistance of a concept of digital damage fingerprints (DDFs). The probability of the presence of damage on the unfolded tube surface was thus obtained, by which means the position of damage was identified with good accuracy.

Effects of sweetener sucralose on diet preference, growth performance and hematological and biochemical parameters of weaned piglets

Zhang, Wenwei,He, Holden,Gong, Limin,Lai, Wenqing,Dong, Bing,Zhang, Liying Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.5

Objective: Two experiments were conducted to investigate the effects of dietary sucralose on diet preference and growth performance of weaned piglets, and a third experiment was a 28-d safety study to examine if high-dose sucralose could affect the health state of weaned piglets. Methods: In experiment one, 48 piglets had free access to a corn-soybean based diet and the same diet supplemented with 150 mg/kg sucralose for 15 d. In experiment two, 180 piglets were blocked into 5 treatments with 6 replications. They were fed basal diets supplemented with 0, 75, 150, 225, and 300 mg/kg sucralose for 28 days. In experiment three, 108 piglets were randomly assigned to 3 treatments and fed diets supplemented with 0, 150 (suitable level), and 1,500 (ten-fold suitable level) mg/kg sucralose for 28 d. Results: The experiment 1 showed that piglets preferred (p<0.05) diets containing sucralose during experimental period. In experiment 2, piglets fed a diet supplemented with 150 mg/kg sucralose had a higher average daily gain (ADG) and average daily feed intake (ADFI) than pigs in the control group and other treatment groups during the experiment period. The concentrations of sucralose over 150 mg/kg may decrease feed intake. However, no difference in feed conversion ratio was observed. In experiment 3, piglets fed diet supplemented with 150 mg/kg sucralose had a higher ADG and ADFI than that of pigs in the control group and 1,500 mg/kg treatment groups during the experiment period. Clinical blood metabolites, organ index and histological morphology were not significantly different between sucralose treatments. Conclusion: Sucralose can promote feed intake and thereby improve growth performance of weaned piglets. Moreover, inclusion of 1,500 mg/kg sucralose was demonstrated to have no observed adverse effects. Supplementing 150 mg/kg sucralose for weaned piglets is recommended in this study.

Piezo-activated guided wave propagation and interaction with damage in tubular structures

Lu, Ye,Ye, Lin,Wang, Dong,Zhou, Limin,Cheng, Li Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.7

This study investigated propagation characteristics of piezo-activated guided waves in an aluminium rectangular-section tube for the purpose of damage identification. Changes in propagating velocity and amplitude of the first wave packet in acquired signals were observed in the frequency range from 50 to 250 kHz. The difference in guided wave propagation between rectangular- and circular-section tubes was examined using finite element simulation, demonstrating a great challenge in interpretation of guided wave signals in rectangular-section tubes. An active sensor network, consisting of nine PZT elements bonded on different surfaces of the tube, was configured to collect the wave signals scattered from through-thickness holes of different diameters. It was found that guided waves were capable of propagating across the sharp tube curvatures while retaining sensitivity to damage, even that not located on the surfaces where actuators/sensors were attached. Signal correlation between the intact and damaged structures was evaluated with the assistance of a concept of digital damage fingerprints (DDFs). The probability of the presence of damage on the unfolded tube surface was thus obtained, by which means the position of damage was identified with good accuracy.

Thermal shock resistance of porous alumina ceramics with different internal and external porosity

Maochang Cao,Xinxin Jin,Le Chen,Limin Dong,Bo Li,Xianyou Zhang 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4

Porous alumina ceramics with porosity of 24.42-41.10% were prepared by gel casting process with polymethylmethacrylatemicrosphere(PMMA) as pore-forming agent. The mechanical/thermal properties and porosity of the obtained ceramic areinfluenced by two structures that composed of spherical shaped micro pores(external pores) depending on PMMA content andirregular sub-micro pores(internal pores) formed by the stacking of ceramic particles. Mechanical properties and thermalconductivity decreased as the porosity increased. The thermal shock resistance of the samples was excellent when the porositywas 33.45%. This phenomenon caused by the matching of external and internal pores is inconsistent with the trend of thermalshock fracture resistance and thermal shock damage resistance varying with porosity in previous researches. In the case of thesame total porosity, the introduction of external pores improved the mechanical properties and critical temperature difference,reduced the thermal conductivity and fracture surface energy that affected the thermal stability of the material.

Effects of supplemented culture media from solid-state fermented Isaria cicadae on performance, serum biochemical parameters, serum immune indexes, antioxidant capacity and meat quality of broiler chickens

Liu, Shaoshuai,Yan, Wenjuan,Ma, Chang,Liu, Yajing,Gong, Limin,Levesque, Crystal,Dong, Bing Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.4

Objective: The objective of this study was to investigate effects of supplementation of culture media from solid-state fermented Isaria cicadae (I. cicadae) on performance, serum biochemical parameters, serum immune indexes, antioxidant capacity and meat quality of broiler chickens. Methods: A total of 648 Arbor Acres male broiler chickens(1 d; average body weight, 42.93±0.47 g) were randomly assigned to 6 treatments, each with six replicates and 18 broiler chickens per replicate. Broiler chickens were fed phase I (d 1 to 21) and phase II (d 22 to 42) diets. The phase I diets were corn and soybean-meal based diets supplemented with 0%, 2%, 4%, 6%, 8%, or 10% culture media from solid-state fermented I. cicadae respectively. The phase II diets were corn and soybean-meal based diets supplemented with 0%, 1.33%, 2.67%, 4.00%, 5.32%, or 6.67% culture media from solid-state fermented I. cicadae respectively. Results: In phase I, the broiler chickens with the supplementation of culture media had increased body weight gain and feed intake (linear and quadratic, p<0.05) with increasing inclusion of culture media. The levels of serum total antioxidant capacity (T-AOC), glutathione (GSH) and superoxide dismutase (SOD) increased linearly (p<0.05). In phase II, levels of serum T-AOC and interleukin-1β increased linearly (p<0.05), and GSH increased (p<0.05). In the kidney, GSH and glutathione peroxidase (GSH-Px) concentrations increased (linear and quadratic, p<0.05) and SOD concentration increased linearly (p<0.05). Compared to the control, shear force and drip loss of breast muscle decreased (linear and quadratic, p<0.05). Drip loss of leg muscle decreased linearly and quadratically (p<0.05). Conclusion: Dietary supplementation of culture media from solid-state fermented I.cicadae which was enriched in both wheat and residual bioactive components of I. cicadae enhanced the growth performance of broiler chickens. It also improved body anti-oxidative status and contributed to improve broiler meat quality.

Risk Factors for Poor Outcomes Following Minimally Invasive Discectomy: A Post Hoc Subgroup Analysis of 2-Year Follow-up Prospective Data

Zihao Chen,Lei He,Lijun Huang,Zhongyu Liu,Jianwen Dong,Bin Liu,Ruiqiang Chen,Liangming Zhang,Peigen Xie,Limin Rong 대한척추신경외과학회 2022 Neurospine Vol.19 No.1

Objective: A post hoc subgroup analysis of prospectively collected data from a randomized controlled trial was conducted to identify risk factors related to poor outcomes in patients who underwent minimally invasive discectomy. Methods: Patients were divided into satisfied and dissatisfied subgroups based on Oswestry Disability Index (ODI), visual analogue scale (VAS) back pain score (VAS-back) and leg pain score (VAS-leg) at short-term and midterm follow-up according to the patient acceptable symptom state threshold. Demographic characteristics, radiographic parameters, and clinical outcomes between the satisfied and dissatisfied subgroups were compared using univariate and multivariate analysis. Results: A total of 222 patients (92.1%) completed 2-year follow-up, and the postoperative ODI, VAS-back, and VAS-leg were significantly improved after surgery as compared to preoperatively. Multivariate analysis indicated older age (p = 0.026), lateral recess stenosis (p = 0.046), and lower baseline ODI (p = 0.027) were related to poor short-term functional improvement. Higher baseline VAS-back (p = 0.048) was associated with poor short-term relief of back pain, while absence of decreased sensation (p = 0.019) and far-lateral disc herniation (p = 0.004) were associated with poorer short-term relief of leg pain. Lumbar facet joint osteoarthritis was identified as a risk factor for poor functional improvement (p = 0.003) and relief of back pain (p = 0.031). Disc protrusion (p = 0.036) predicted poorer relief of back pain at midterm follow-up. Conclusion: In this study, several factors were identified to be predictive of poor surgical outcomes following minimally invasive discectomy. (ClinicalTrials.gov number: NCT01997086).