Enhancing electrical properties of high-Curie temperature piezoelectric ceramics BNT-PZT and their mechanism

Wanwan Ji,Bijun Fang,Xiangyong Zhao,Shuai Zhang,Xiaolong Lu,Xiaolong Lu 한국물리학회 2019 Current Applied Physics Vol.19 No.12

Due to the urgent demands for high-Curie temperature (TC/Tm) piezoelectric materials in geothermal exploration, aerospace and related fields, high-TC/Tm ferroelectrics have attracted booming research attention. The high-Tm 0.25Bi(Ni1/2Ti1/2)O3-0.75 Pb(Zr1/2Ti1/2)O3 (0.25BNT-0.75PZT) ceramics were prepared by solid-state sintering method and via partial oxalate route, where the 0.25BNT-0.75PZT ceramics prepared via the partial oxalate route exhibit better electrical properties (Tm=232 °C (10 kHz), εm=10963, Pr=26.14 μC/cm2, Ec=15.61 kV/cm, d33=521 pC/N, d33* = 553.3 pm/V, Kp=47.1%, and Qm=21.6). The nano-scale domain configuration of the ceramics was revealed by piezoelectric force microscopy (PFM), and the relationship between the micro-structure and macro-electrical properties was analyzed. The ferroelectric phase transition mechanism was studied by temperature dependent Raman spectroscopy. The reduction of energy barrier of lattice distortion and polarization deflection is caused by nanometer-sized domain structure, low symmetric polar nano-regions and/or coexistence of multi-ferroelectric phases, contributing to the excellent electrical properties of the 0.25BNT-0.75PZT ceramics prepared via the partial oxalate route.

Effect of Perforating an Intake Pipe on the Interior Noise of a Passenger Car

Zhu Yawei,Lu Chihua,Liu Zhien,Xie Liping,Li Xiaolong 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.4

The intake pipes designed by some experienced engineers have small holes. However, the role of these small holes is yet to be fully understood by most engineers. At present, the only research on this issue is also controversial. This work aims to reveal the effect of perforating an intake pipe on the interior noise and provide some suggestions to automotive engineers when applying this method. First, the effect of these small holes on the source strength of the intake nozzle and perforated region is theoretically analyzed. Thereafter, the noise transfer functions of the intake nozzle and perforated region to the target response point in the cab are measured on the basis of the reciprocity principle. Finally, the effect of perforating the intake pipe on the interior noise is studied by simulating the intake noise of the experimental car with an external sound source. Results show that perforating the intake pipe can increase the order noise component of the intake noise and reduce the mid-high frequency noise in the cab, thereby improving the powerful sound quality and reducing the feeling of noisy.

Optimization of Nutrients for Dinactin Production by a Marine Streptomyces sp. from the High Latitude Arctic

Jiao Zhou,Hao He,Xiaolong Wang,Jian Lu,Xiangshan Zhou,Menghao Cai,YuanXingZhang 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.4

Streptomyces sp. R-527F, which produces the macrotetrolide antibiotic dinactin, was isolated from the sediments of the Arctic Ocean. In this work, optimization of the nutrients required for dinactin production including medium development and precursor stimulation, were investigated. Optimization of the medium and replacement of polar sea water were achieved using a one factor at a time experiment in conjunction with statistical analysis using methods covering Plackett–Burman design, the steepest descent method and central composite design. Dinactin production in the optimized medium was 160.8 mg/L, which was 47 fold higher than the control. Supplementation of the fermentation with exogenous acetate (1.5 mmol/L), succinate (6 mmol/L), malonate (24 mmol/L) and citrate (6 mmol/L) further enhanced dinactin biosynthesis by 42.7, 122.3, 66.7, and 62.1%, respectively. The precursors, in particular succinate, facilitated sugar use and also increased pH levels. Furthermore, a six-pulse feeding of total 6 mmol/L succinate in a 5 L bioreactor fermentation yielded a maximal production of 279.0 mg/L dinactin, 124.1% higher than that without precursor stimulation. This nutritional regulation process is easy to scale up and holds the potential for adaptation to industrial use. Keywords: arctic actinomycete, fermentation, dinactin

Long-Term Outcomes of Stenting on Non-Acute Phase Extracranial Supra-Aortic Dissections

Jiang, Yeqing,Di, Ruoyu,Lu, Gang,Huang, Lei,Wan, Hailin,Ge, Liang,Zhang, Xiaolong The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.3

Objective : Extracranial supra-aortic dissections (ESADs) with severe stenosis, occlusion and/or pseudoaneurysm presents potential risk of stroke. Endovascular stenting to reconstruct non acute phase ESADs (NAP-ESADs) is an alternative to anticoagulant or antiplatelet therapy. However, its feasibility, safety and efficacy of stenting in NAP-ESADs is unclear. This study aims to investigate the long-term outcomes of the feasibility, safety and efficacy of stenting in NAP-ESADs. Methods : Seventy-four patients with 91 NAP-ESAD vessels with severe stenosis, occlusion and/or pseudoaneurysm presents potential risk of stroke who underwent stent remodeling were enrolled into this respective study from December 2008 to March 2020. Technical success rate, complications, clinical and angiographic results were harvested and analyzed. Results : Success rate of stent deployment was 99% (90/91) with no procedural mortality or morbidity. Transient ischemic attack occurred in three patients during operation (4.1%, 3/74). Asymptomatic embolisms of distal intracranial vessels were found in two patients (2.7%, 2/74). One hundred and forty-two stents deployed at 85 carotid (135 stents) and six vertebral (seven stents) vessels. Six stent types (Wingspan, 28/135, 20.7%; Solitaire, 10/135, 7.4%; Neuroform, 8/135, 5.9%; LVIS, 2/135, 1.5%; Precise, 75/135, 55.6%; Acculink, 12/135, 8.9%) were deployed at carotid arterial dissection while two types (Wingspan, 5/7, 71.4%; Solitaire 2/7, 28.6%) at vertebral arterial dissection. Digital subtracted angiography (56%, 51/91), computational tomography angiography (41.8%, 38/91) and high resolution magnetic resonance imaging (2.2%, 2/91) were adopted for follow up, with a mean time of 17.2±15.4 months (5-77). All patient modified Rankin Scale scores showed no increase at discharge or follow-up. Angiographically, dissections in 86 vessels in 69 patients (94.5%, 86/91) were completely reconstructed with only minor remnant dissections in four vessels in four patients (4.4%, 4/91). Severe re-stenosis in the stented segment required re-stenting in one patient (1.1%, 1/91). Conclusion : Stent remodeling technique provides feasible, safe and efficacious treatment of ESADs patients with severe stenosis, occlusion and/or pseudoaneurysm.

Progressive Collapse Behavior of Large-span Truss String Structures Subjected to Cable Failure

Haiying Zhang,JinYu Lu,Xiaolong Wu,Na Li 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.4

Cables play an important role in truss string structures, and their sudden failure can lead to massive damage and even collapse of the structures. This paper studies the dynamic response of a 72 m span truss string structure, the progressive collapse numerical simulation of the structure is carried out under different load conditions, the displacement and force responses of the structure after cable failure are investigated, the dynamic amplification factor is calculated, and the collapse mechanism is revealed. The effect of individual factor changes on the structural response is analyzed and compared. Results showed that after cable failure, the stress state of the upper truss changed from an arch to a simply supported beam, when reaching collapse load, the structure collapsed within 5s instead of reaching new equilibrium positions. Moreover, the structure with stiffer elastic support exhibited higher resistance to collapse. The critical member of the truss, which first buckled under compression, shifted from the mid-span to the lower chord at the end, leading to rapid structural collapse. Increasing the cable's cross-sectional area can hardly reduce the structure's dynamic response. However, when the instantaneous failure time of the cable exceeded 0.1s, a significant alleviation of the structure's dynamic response was observed.

Experimental study on vortex-induced motions of a semi-submersible with square columns and pontoons at different draft conditions and current incidences

Liu, Mingyue,Xiao, Longfei,Lu, Haining,Xiao, Xiaolong The Society of Naval Architects of Korea 2017 International Journal of Naval Architecture and Oc Vol.9 No.3

The Vortex-induced Motions (VIM) phenomenon of semi-submersibles is relevant for the fatigue life of moorings and risers. Model tests regarding the VIM behavior of a semi-submersible with four square columns were conducted in order to investigate the effects of the current incidence and the aspect ratio of the immerged column. The experimental results show that the largest transverse amplitudes are around 70% of the column width at $30^{\circ}$ and $45^{\circ}$ incidences in a range of reduced velocities from 5 to 8 when the aspect ratio of the immerged column is 1.90. The largest yaw motion occurs at $0^{\circ}$ incidence with the peak value around $4.5^{\circ}$. Similar characteristics of the VIM response are observed for the semi-submersible with aspect ratios of 1.90 and 1.73. When the aspect ratio decreases 50% to 0.87, 30% decrease in the peak transverse amplitudes can be seen.

Infection of Oligochaetes, Limnodrilus hoffmeisteri (Annelida: Oligochaeta), in the Nasal Cavity of a Chinese Man

Hongbin Liu,Zhenming Zhang,Guangping Huang,Xiaolong Gu,Chunmiao Wang,Yan Wang,Zhimin Lu 대한기생충학열대의학회 2017 The Korean Journal of Parasitology Vol.55 No.1

Increased Wall Enhancement Extent Representing Higher Rupture Risk of Unruptured Intracranial Aneurysms

Jiang, Yeqing,Xu, Feng,Huang, Lei,Lu, Gang,Ge, Liang,Wan, Hailin,Geng, Daoying,Zhang, Xiaolong The Korean Neurosurgical Society 2021 Journal of Korean neurosurgical society Vol.64 No.2

Objective : This study aims to investigate the relationship between aneurysm wall enhancement and clinical rupture risks based on the magnetic resonance vessel wall imaging (MR-VWI) quantitative methods. Methods : One hundred and eight patients with 127 unruptured aneurysms were prospectively enrolled from Feburary 2016 to October 2017. Aneurysms were divided into high risk (≥10) and intermediate-low risk group (<10) according to the PHASES (Population, Hypertension, Age, Size of aneurysm, Earlier SAH history from another aneurysm, Site of aneurysm) scores. Clinical risk factors, aneurysm morphology, and wall enhancement index (WEI) calculated using 3D MR-VWI were analyzed and compared. Results : In comparison of high-risk and intermediated-low risk groups, univariate analysis showed that neck width (4.5±3.3 mm vs. 3.4±1.7 mm, p=0.002), the presence of wall enhancement (100.0% vs. 62.9%, p<0.001), and WEI (1.6±0.6 vs. 0.8±0.8, p<0.001) were significantly associated with high rupture risk. Multivariate regression analysis revealed that WEI was the most important factor in predicting high rupture risk (odds ratio, 2.6; 95% confidence interval, 1.4-4.9; p=0.002). The receiver operating characteristic (ROC) curve analysis can efficiently differentiate higher risk aneurysms (area under the curve, 0.780; p<0.001) which have a reliable WEI cutoff value (1.04; sensitivity, 0.833; specificity, 0.67) predictive of high rupture risk. Conclusion : Aneurysms with higher rupture risk based on PHASES score demonstrate increased neck width, wall enhancement, and the enhancement intensity. Higher WEI in unruptured aneurysms has a predictive value for increased rupture risk.

Preparation and properties of Nd-doped BCTH lead-free ceramics by solid-phase twin crystal method

He Xiyue,Fang Bijun,Zhang Shuai,Lu Xiaolong,Ding Jianning 한국물리학회 2022 Current Applied Physics Vol.38 No.-

0.5 mol% Nd-doped (Ba0.85Ca0.15)(Ti0.9Hf0.1)O3 (BCTH-Nd) lead-free ceramics were prepared by a solid-phase twin crystal method, where the effects of sintering condition on structure, electrical and optical properties were studied. All the sintered BCTH-Nd ceramics exhibit pure perovskite structure, dense microstructure with several micron grain size, which tends to increase with elevating sintering temperature. All synthesized ceramics have complex dielectric behavior, which presents normal ferroelectrics characteristic with slight dispersion phenomenon. The BCTH-Nd ceramics exhibit excellent piezoelectric and ferroelectric properties and acceptable dielectric performance when sintered at 1480 ◦C for 2 h. Under 269 nm light excitation, several fluorescent emission peaks are excited with a whole indigo fluorescence, where the strongest emission peak is emitted at 473 nm, corresponding to the 4G3/2 → 4I9/2 energy level transition of Nd3+. Multifunctional performance is fulfilled in the lead-free BCTH ceramics via rare earth doping, which can broaden the application fields of piezoelectricbased materials.

Experimental study on vortex-induced motions of a semi-submersible with square columns and pontoons at different draft conditions and current incidences

Mingyue Liu,Longfei Xiao,Haining Lu,Xiaolong Xiao 대한조선학회 2017 International Journal of Naval Architecture and Oc Vol.9 No.3

The Vortex-induced Motions (VIM) phenomenon of semi-submersibles is relevant for the fatigue life of moorings and risers. Model tests regarding the VIM behavior of a semi-submersible with four square columns were conducted in order to investigate the effects of the current incidence and the aspect ratio of the immerged column. The experimental results show that the largest transverse amplitudes are around 70% of the column width at 30 and 45 incidences in a range of reduced velocities from 5 to 8 when the aspect ratio of the immerged column is 1.90. The largest yaw motion occurs at 0 incidence with the peak value around 4.5. Similar characteristics of the VIM response are observed for the semi-submersible with aspect ratios of 1.90 and 1.73. When the aspect ratio decreases 50% to 0.87, 30% decrease in the peak transverse amplitudes can be seen.