Surface-enhanced Raman scattering using monolayer graphene-encapsulated Ag nanoparticles as a substrate for sensitive detection of 2,4,6-trinitrotoluene

Chen, Z.,Qiu, L.,Tian, Y.,Lee, Y. I.,Hou, X.,Wu, L. Royal Society of Chemistry 2017 Analytical methods Vol.9 No.21

<P>We developed a surface-enhanced Raman scattering (SERS)-active substrate based on chemical vapor deposition (CVD)-grown monolayer graphene-encapsulated silver nanoparticles (Ag NPs) and used it for the detection of 2,4,6-trinitrotoluene (TNT). Monolayer graphene-encapsulated Ag NPs can be used as a stable substrate for up to 2 months under aerobic exposure. The single layer of graphene can effectively stabilize the Ag NPs against oxidation and corrosion in the presence of H2O2, Na2S and HNO3. Due to the combination of the Ag NPs with graphene, the Raman signals of probe molecules were dramatically enhanced. This platform exhibits extraordinarily high sensitivity and excellent stability for the detection of TNT, with a limit of detection as low as 6.6 x 10(-10) mol L-1. This work provides a simple approach to fabricate graphene-encapsulated Ag NPs for sensitive SERS sensing of TNT after Fenton oxidation degradation.</P>

<Retraction> INVESTIGATION OF HIGH-COERCIVITY FePt-C NANOGRANULAR FILMS FOR PERPENDICULAR MAGNETIC RECORDING (PMR) MEDIA

JIEGANG PENG,S. XUE,Z. YAN,X. WU,L. ZHAN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.6

In this work, we studied FePt-C nanogranular films were fabricated for ultrahigh density perpendicular recording media towards 1 Tbits/in^2. For the optimized growth conditions, we achieved a Fe_(52)Pt_(48)-C50% granular film with uniform grain size of 6.4 ± 1.5 nm, shown in the TEM image. It also has an excellent MH loop shape with a perpendicular coercivity of 20 kOe, and squareness of 1.We studied the thermal stability of the optimized film and obtained the energy barrier Eb of 340 k_BT at room temperature, meaning that excellent thermal stability as magnetic recording media.

Derivatization reaction-based surface-enhanced Raman scattering (SERS) for detection of trace acetone

Zheng, Y.,Chen, Z.,Zheng, C.,Lee, Y.I.,Hou, X.,Wu, L.,Tian, Y. Pergamon Press ; Elsevier Science Ltd 2016 Talanta Vol.155 No.-

<P>A facile method was developed for determination of trace volatile acetone by coupling a derivatization reaction to surface-enhanced Raman scattering (SERS). With iodide modified Ag nanoparticles (Ag IMNPs) as the SERS substrate, acetone without obvious Raman signal could be converted to SERS-sensitive species via a chemical derivatization reaction with 2,4-dinitrophenylhydrazine (2,4-DNPH). In addition, acetone can be effectively separated from liquid phase with a purge-sampling device and then any serious interference from sample matrices can be significantly reduced. The optimal conditions for the derivatization reaction and the SERS analysis were investigated in detail, and the selectivity and reproducibility of this method were also evaluated. Under the optimal conditions, the limit of detection (LOD) for acetone was 5 mg L-1 or 0.09 mM (3 sigma). The relative standard deviation (RSD) for 80 mg L-1 acetone (n=9) was 1.7%. This method was successfully used for the determination of acetone in artificial urine and human urine samples with spiked recoveries ranging from 92% to 110%. The present method is convenient, sensitive, selective, reliable and suitable for analysis of trace acetone, and it could have a promising clinical application in early diabetes diagnosis. (C) 2016 Elsevier B.V. All rights reserved.</P>

Investigation of the correlation between mechanical chip morphology and surface residual stress for Ti6Al4V alloy

Z. R. Wu,K. K. Zhu,L. Pan,L. Fang,Y. D. Song 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.10

A numerical simulation analysis of mechanical chip morphology and residual stress for Ti6Al4V alloy was conducted under different cutting speed and feed rate. Johnson-Cook constitutive model and shear failure model were selected in the simulation procedure. The correlations between the mechanical chip morphology and surface residual stress were detailed. The results show that the chip morphology characterized with the degree of serration Gs and the serrated frequency f has a direct impact on residual stress distribution. With the increase of the degree of serration Gs, the maximum residual tensile stress decreases, while with the increase of the serrated frequency f, the maximum residual compressive stress increases on the surface. The research of the present paper provides a new way to understand and evaluate residual stress distribution for titanium alloy mechanical process.

Acanthoic acid, a diterpene in Acanthopanax koreanum, protects acetaminophen-induced hepatic toxicity in mice

Wu, Y.-L.,Jiang, Y.-Z.,Jin, X.-J.,Lian, L.-H.,Piao, J.-Y.,Wan, Y.,Jin, H.-R.,Joon Lee, J.,Nan, J.-X. G. Fischer 2010 Phytomedicine Vol.17 No.6

The protective effect of a diterpenoid acanthoic acid (AA) isolated from Acanthopanax koreanum Nakai was investigated in acetaminophen (APAP)-induced hepatic toxicity. Drug-induced hepatotoxicity induced by an intraperitoneal (i.p.) injection of 300mg/kg (sub-lethal dose) of APAP. Pretreatment with AA (50 and 100mg/kg) orally 2h before the APAP administration attenuated the APAP-induced acute increase in serum aspartate aminotransferase (AST), and alanine aminotransferase (ALT) activites, replenished the depleted hepatic glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) activities, decreased malondialdehyde (MDA) level and considerably reduced the histopathological alterations in a manner similar to silymarin (Sily). Immunohistochemical analyses also demonstrated that AA could reduce the appearance of necrosis regions as well as caspase-3 and hypoxia inducible factor-1α (HIF-1α) expression in liver tissue. Our results indicated that AA protected liver tissue from the oxidative stress elicites by APAP-induced liver damage and suggestes that the hepatic protection mechanism of AA would relate to antioxidation and hypoxia factor on APAP-induced hepatotoxicity.

Marker-Assisted Mating Applied in In-Situ Conservation of Indigenous Animals in Small Populations : (1) Choosing Mating Schemes for Maximum Heterozygosity

Wu, X.L.,Liu, R.Z.,Shi, Q.S.,Liu, X.C.,Li, X.,Wu, M.S. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.4

Maintaining maximum genetic variability is of critical importance with in-situ conservation of animal species in small populations. Marker-assisted mating (MAM) was suggested to achieve maximum heterozygosity in offspring populations. The aims of this research was to investigate and decide the effectiveness and promising types of MAM to achieve this goal. Analysis of variance with simulation data revealed that the heterozygosity in offspring populations was significantly determined by sire heterozygosity from mating of non-inbred parent animals, and significantly by sire heterozygosity and percent parental difference in offspring reproduced by inbred parents. Seven types of marker-assisted mating schemes were examined, in which offspring exhibited heterozygosity that was -0.01 to 7.37% below or above that from random mating of non-inbred parent animals, and 0.00 to 16.39% above that from random mating of inbred parent animals. The great increase in offspring heterozygosity was observed with mating by tandem maximizing sire heterozygosity, percent parental difference, and dam heterozygosity. Random mating resulted in fluctuation of offspring heterozygosity. These results suggested that MAM was a promising method for maintaining maximum offspring variability in in-situ conservation of animal species in small populations.

True Digestibility of Phosphorus in Different Resources of Feed Ingredients in Growing Pigs

Wu, X.,Ruan, Z.,Zhang, Y.G.,Hou, Y.Q.,Yin, Y.L.,Li, T.J.,Huang, R.L.,Chu, W.Y.,Kong, X.F.,Gao, B.,Chen, L.X. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.1

To determine the true digestible phosphorus (TDP) requirement of growing pigs, two experiments were designed with the experimental diets containing five true digestible P levels (0.16%, 0.20%, 0.23%, 0.26% and 0.39%) and the ratio of total calcium to true digestible P (TDP) kept at 2:1. In Experiment 1, five barrows (Duroc${\times}$Landrace${\times}$Yorkshire) with an average initial body weight of 27.9 kg were used in a $5{\times}5$ Latin-square design to evaluate the effect of different dietary P levels on the digestibility and output of P and nitrogen. In Experiment 2, sixty healthy growing pigs (Duroc${\times}$Landrace${\times}$Yorkshire) with an average body weight (BW) of 21.4 kg were assigned randomly to one of the five dietary treatments (12 pigs/diet), and were used to determine the true digestible phosphorus (TDP) requirement of growing pigs on the basis of growth performance and serum biochemical indices. The results indicated that the true digestibility of P increased (p<0.05) linearly with increasing dietary TDP level below 0.26%. The true P digestibility was highest (56.6%) when dietary TDP was 0.34%. Expressed as g/kg dry matter intake (DMI), fecal P output increased (p<0.05) linearly with increasing P input. On the basis of g/kg fecal dry matter (DM), fecal P output was lowest for Diet 4 and highest (p<0.05) for Diet 5. The apparent digestibility of crude protein (CP) did not differ (p>0.05) among the five diets, with the average nitrogen output of 12.14 g/d and nitrogen retention of 66% to 74% (p>0.05), which suggested that there was no interaction between dietary P and CP protein levels. During the 28-d experimental period of Experiment 2, the average daily gain (ADG) of pigs was affected by dietary TDP levels as described by Eq. (1): $y=-809,532x^4+788,079x^3-276,250x^2+42,114x-1,759$; ($R^2=0.99$; p<0.01; y = ADG, g/d; x = dietary TDP, %), F/G for pigs by Eq. (2): $y=3,651.1x^4-3,480.4x^3+1,183.8x^2-172.5x+10.9$ ($R^2=0.99$; p<0.01; y = F/G; x = dietary TDP, %), and Total P concentrations in serum by Eq. (3): $y=-3,311.7x^4+3,342.7x^3-1,224.6x^2+195.6x-8.7$ (R2 = 0.99; p<0.01; y = total serum P concentration and x = dietary TDP, %). The highest ADG (782 g/d), the lowest F/G (1.07) and the highest total serum P concentration (3.1 mmol/L) were obtained when dietary TDP level was 0.34%. Collectively, these results indicate that the optimal TDP requirement of growing pigs is 0.34% of the diet at a total Ca to TDP ratio of 2:1.

Incorporating Hysteresis in One-dimensional Seepage Modeling in Unsaturated Soils

L. Z. Wu,R. Q. Huang,Q. Xu 대한토목학회 2012 KSCE JOURNAL OF CIVIL ENGINEERING Vol.16 No.1

To understand better the influence of soil-water characteristic hysteresis on rainfall infiltration and pore-water pressure distributions in unsaturated soils, an analytical solution to the one-dimensional governing partial differential equation considering hysteresis is derived using a Fourier integral transformation. The analytical solution considers time-dependent and arbitrary initial pore-water pressure distributions, as well as a time-varying rainfall flux process at the ground surface. An exponential function is used to represent the hysteretic Soil-Water Characteristic Curve (SWCC) and the relationship between hydraulic conductivity and pore-water pressure. The calculated results demonstrate that the critical point, the intersection between wetting and drying domains in one-dimensional unsaturated seepage, is influenced by many factors. The hysteresis in soil-water characteristics is an important factor in infiltration process influencing the pore-water pressure profiles in unsaturated soils. The effects of hysteretic parameters on pore-water pressure profiles are also analyzed. The value of α in the hysteresis model is found to be the most significant factor influencing the pore pressure distributions.

DESIGN OF A SOFT SWITCHING BIDIRECTIONAL DC-DC POWER CONVERTER FOR ULTRACAPACITOR-BATTERY INTERFACES

Z. W. WU,Z. L. ZHANG,C. L. YIN,Z. ZHAO 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.2

One solution to the low specific power of hybrid electric vehicular batteries is a hybrid energy storage system (HESS) that takes advantage of the high specific power performance of ultra-capacitors. The design of a type of zero current transition (ZCT) soft switching bidirectional direct current-direct current (DC-DC) power converter that can be used as an ultra-capacitor-battery interface in an active parallel schema of a HESS is described. The circuit operation of the ZCT DC-DC power converter is depicted in detail. The HESS controller is designed as a two-layered hierarchical control structure: the first layer is responsible for working mode control of the HESS, and the second layer is responsible for DC-DC power converter control in which a fuzzy logic PID algorithmis employed. Simulation results indicate that this design is a potential solution to the problem of the low specific power of batteries, especially for regenerative braking and electric motor assist. The proposed active parallel schema with ZCT exhibits a significant advantage in power and energy decoupling. HESS with ZCT achieves better efficiency compared to the battery only operation. The experimental results validates the idea that the ultra-capacitor cooperates with the battery in acceleration mode.

High-frequency fall-off of source spectra of deep-focus earthquakes from Wigner - distribution estimation

(Z . L . Wu),(S . G . Kim),(Y . T . Chen) 한국지진연구소 1997 Physics of the Earth and Planetary Interiors Vol.99 No.-