Micro-/Nanocombined Gas Sensors With Functionalized Mesoporous Thin Film Self-Assembled in Batches Onto Resonant Cantilevers

Haitao Yu,Pengcheng Xu,Xiaoyuan Xia,Dong-Weon Lee,Xinxin Li IEEE 2012 IEEE transactions on industrial electronics Vol.59 No.12

<P>This paper reports a novel top-down/bottom-up combined resonant microcantilever chemical sensor, where the nanosensing material of a functionalized mesoporous thin film (MTF) is directly self-assembled on the sensing region of the integrated microcantilever. By using the batch-producible nano-on-micro construction technique, a large number of such sensors can be batch fabricated with uniform performance and low cost. More importantly, the sensing molecule terminals can be simultaneously constructed at the pore inner surface when the MTF is directly grown on the cantilever. With -NH<SUB>2</SUB>-group-functionalized MTF directly grown onto the surface of the cantilever free end, the micro-/nanocombined gravimetric sensor has experimentally exhibited quick response and highly sensitive detection of CO<SUB>2</SUB> gas.</P>

Mechanical Behavior of 3D Woven Variable Thickness Composite Plate under Tensile Loading

Yu Zhou,Haitao Cui,Weidong Wen 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3

As a directly net-shaped structure, 3D woven variable thickness composite plate is different from the constantthickness structure in terms of the changing weft yarn sizes and resulting various warp yarn direction. To investigate themechanical behavior of this structure, a finite element (FE) model was proposed in this paper on the basis of author’sprevious geometric model illustrating the characterized details. Mesh convergence was studied to determine the size ofelement in compromise of accuracy and efficiency. Linear displacement rather than periodic boundary conditions wereapplied due to the thickness change. For the validation of presented FE model, a sample variable thickness plate in 3D layerto layer weave style was tested under tensile load in warp direction whose thickness was changed in this direction by thechange of weft yarn size. The strain was monitored with the help of Digital Image Correlation (DIC) system. The resultsshowed that the predicted homogenized stiffness in warp direction decreased with the thickness increasing, in agreement withthe observation from experiments. The maximum error between the predicted stiffness and the measurements of typicalsegment (TS) in variable thickness region of the plate is 12.05 % while the minimum error is 0.7 %.

Effect of branched alumina on thermal conductivity of epoxy resin

Yu Long,Lirui Shi,Qingyu Wang,Haitao Qu,Chuncheng Hao,Qingquan Lei 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-

Composites prepared by using epoxy resin (EP) as matrix had limited practical applications owing to theirpoor thermal conductivity. The thermal conductivity of composites can be enhanced by doping inorganicfillers. However, it could not be significantly enhanced owing to the saturation of inorganic fillers. In thisstudy, we prepared branched alumina (b-Al2O3) by using high-temperature sintering and doped it as afiller to obtain b-Al2O3/EP composites. The results shown that the thermal conductivity of the EP compositeswith 70 wt% b-Al2O3 was 1.13 Wm1K1, which was seven times higher than that of pure EP. Thiscould be attributed to the overlapping of b-Al2O3 for the formation of a continuous mesh structure thatresults in thermal conduction channels inside the EP, which reduced the interfacial thermal resistanceand improved the thermal conductivity of the composite. The resistivity of b-Al2O3/EP was 9.64 1014Xm and that of pure EP was 2.08 1014 Xm. The dielectric constant of the b-Al2O3/EP compositesincreased with the increase in b-Al2O3 content, while the dielectric loss factor decreases. This was significantfor the application of EP composites in the field of electrical insulation.

Magnetic properties of Bi-doped Y3Fe5O12 nanoparticles

Haitao Xu,Hua Yang,Wei Xu,Lianxiang Yu 한국물리학회 2008 Current Applied Physics Vol.8 No.1

Bi³+ substituted garnet nanoparticles Y₃. xBiχFe5O₁₂ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 and 1.3) were fabricated by a solgel methodand their crystalline structures and magnetic properties were investigated by using X-ray diraction (XRD), IR spectroscopy, thermalgravity analysisdierential thermal analysis (TG-DTA), transmission electron microscope (TEM), Mo¨ssbauer spectroscopy and vibrat-3. xBixFe5O12 have only peaks of the garnet structure.

Poorly Differentiated Colorectal Cancers : Correlation of Microsatellite Instability With Clinicopathologic Features and Survival

Xiao, Haitao,Yoon, Yong Sik,Hong, Seung-Mo,Roh, Seon Ae,Cho, Dong-Hyung,Yu, Chang Sik,Kim, Jin Cheon American Society for Clinical Pathology 2013 American journal of clinical pathology Vol.140 No.3

<P><B>Objectives:</B></P><P>To evaluate the association of microsatellite instability (MSI) with clinicopathologic features and oncologic outcomes in patients with poorly differentiated colorectal cancer (PD).</P><P><B>Methods:</B></P><P>Study patients were divided into well-differentiated colorectal cancer (WD) and PD, which were compared according to histologic differentiation and MSI status.</P><P><B>Results:</B></P><P>Among 1,941 patients, PD was more frequent among microsatellite-unstable tumors (23.6%) than among microsatellite-stable (MSS) tumors (4.2%, <I>P</I> < .001). Patients with PD had worse 4-year overall survival rates than patients with WD (78.6% vs 88.2%, <I>P</I> = 0.010). Compared with MSS-PD tumors, MSI-PD tumors were characterized by right-colon predilection, larger size, and infrequent lymph node metastasis (<I>P</I> < .001 to <I>P</I> = .007).</P><P><B>Conclusions:</B></P><P>The clinicopathologic characteristics of PD were closely associated with those of MSI. The outcomes of MSI-PD tumors were better than those of MSS-PD tumors, but this finding did not reach statistical significance.</P>

Analysis on Climate Change Trend in Guangzhou Area in Recent 65 Years

Wenzheng Yu,Haitao Liu,Jin Wang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.12

Based on the climate data and the social statistics of Guangzhou observatory from 1952 to 2014,this paper used Linear trend analysis, Morlet wavelet transform analysis, Mann-Kendall mutation test etc, to analyze the trend of climate change in Guangzhou nearly 65 years. The results showed that climatic conditions in Guangzhou in recent 65 years showed a warming and drying trend and this trend had become increasingly apparent since the 1990s. The average temperature increased at the rate of 0.153 ℃ / 10a , at the same time, the warming rate of average minimum temperature was higher than the average maximum temperature (0.15 ℃ / 10a> 0.14 ℃ / 10a). The annual precipitation had a slight increase at the rate of 37.77 mm / 10a. Under the effect of urban dry-island, the average relative humidity had a decreasing trend at the rate of 0.94% / 10a and the sunshine hours showed a decreasing trend with fluctuation.

Initial Position Estimation of Permanent Magnet Synchronous Motors Based on Variation Behavior of Winding Inductances

Gaojun Meng,Haitao Yu,MinQiang Hu,Lei Huang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

An estimation method of initial rotor position is a difficult research branch in permanent magnet synchronous motors(PMSM), it is also an important research branch in sensorless technique. In PMSM with a saliency pole structured rotor, influenced by saliency effects, the self-inductance and mutual-inductance present periodicity variation, Starting from this feature,Firstly, the method of injecting high frequency low voltage pulses is utilized for identifying the line inductance and then the influence of winding current to line inductance are thorough analyzed by Fourier series decomposition. Secondly, using the rotational coordinate transformation, the fundamental harmonic and third harmonic can be eliminated to some extent, and then the inductance can be presented by a sine function, then the position vs. inductance characteristics are modeled for estimating the rotor position. The experimental results show that the proposed method estimates the initial rotor position reliably and efficiently.

Hyper-branched sensing polymer directly constructed on a resonant micro-cantilever for the detection of trace chemical vapor

Liu, Yongjing,Xu, Pengcheng,Yu, Haitao,Zuo, Guomin,Cheng, Zhenxing,Lee, D.-W.,Li, Xinxin The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.34

<P>A hyper-branched polymer is layer-by-layer self-assembled on a resonant micro-cantilever and, then, functionalized with sensing-terminals for the specific detection of the trace chemical vapor of dimethyl methylphosphonate (DMMP, a typical simulant for nerve agents). The hyper-branched polymer is directly constructed on the SiO<SUB>2</SUB> surface of the cantilever <I>via</I> an A<SUB>2</SUB> + B<SUB>4</SUB> layer-by-layer route, where A<SUB>2</SUB> and B<SUB>4</SUB> are complementary interacting groups which undergo coupled linking. After modification with 4-(2-(4-(allyloxy)phenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenol (APHFPP) groups specific to DMMP, the high specific-surface-area hyper-branched polymer provides very dense sensing sites to adsorb a great number of DMMP molecules for micro-gravimetric detection. Moreover, the sensing polymer possesses a “more branches but fewer roots” configuration on the cantilever surface to depress the cross-talk effect caused by adsorption induced cantilever spring-stiffening. Experimental results indicate that, self-assembled with the hyper-branched sensing polymer, the resonant cantilevers exhibit rapid and reproducible detection of trace DMMP (with the detection limit lower than 7.2 ppb) and effectively depressed parasitic frequency-shift from the cantilever spring stiffening effect. In addition, the sensor features satisfactory selectivity in the presence of water and organic solvents. When an alternative sensing-group of 2-allylhexafluoroisopropanol (AHFIP) is modified on the hyper-branched architecture, the cantilever becomes specifically sensitive to trace explosive vapor. Therefore, the developed technique for the functionalization of hyper-branched polymer directly grown on a cantilever provides a widely usable micro/nano sensing-platform for the detection of trace chemical vapors.</P> <P>Graphic Abstract</P><P>A hyperbranched polymer is directly grafted onto a resonant micro-cantilever surface. The polymer is functionalized with sensing terminal groups and it exhibits the selective, rapid and reproducible detection to trace dimethyl methylphosphonate, with the detection limit lower than 7.2 ppb. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm33202g'> </P>

Self-assembly and sensing-group graft of pre-modified CNTs on resonant micro-cantilevers for specific detection of volatile organic compound vapors

Xu, Pengcheng,Li, Xinxin,Yu, Haitao,Liu, Min,Li, Jungang IOP 2010 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.20 No.11

<P>This paper reports MWCNT (multi-wall carbon nano-tube)-modified resonant micro-cantilever chemical sensors for detection of trinitrotoluene (TNT) vapor. The MWCNTs are pre-modified and then area-selectively self-assembled at the free-end gold pad of a micro-cantilever, in which a resonance-exciting heater and a signal-readout piezoresistive Wheatstone bridge are integrated. Featuring a high specific surface area, the MWCNTs are further functionalized with TNT-sensitive groups by grafting onto the sidewalls of the MWCNTs. To lower the non-specific absorption of water and other small organic molecules, the SiO<SUB>2</SUB> surface of the micro-cantilever was also pre-treated for hydrophobicity and oleophobicity by self-assembling a monolayer of heptadecafluorodecyltrimethoxysilane. The results of our sensing experiments have shown a capability to rapidly detect ppb-level TNT vapor, and a high specificity of the functionalized groups to TNT molecules. The experiment has also confirmed a good long-term stability in detecting sensitivity.</P>

TiO2 nanoparticles anchored on graphene oxide nanosheets as a highly active photocatalyst for decabromodiphenyl ether degradation

Man Yang,Yilun Zou,Lei Ding,Yang Yu,Jinai Ma,Lei Li,Ande Fudja Rafryanto,Jing Zou,Arramel,Haitao Wang 한국탄소학회 2023 Carbon Letters Vol.33 No.5

Decabromodiphenyl ether (BDE209) is a persistent aromatic compound widely associated with environmental pollutants. Given its persistence and possible bioaccumulation, exploring a feasible technique to eradicate BDE209 efficiently is critical for today’s environmentally sustainable societies. Herein, an advanced nanocomposite is elaborately constructed, in which a large number of titanium dioxide ( TiO2) nanoparticles are anchored uniformly on two-dimensional graphene oxide (GO) nanosheets ( TiO2/GO) via a modified Hummer’s method and subsequent solvothermal treatment to achieve efficient photocatalytic degradation BDE209. The obtained TiO2/ GO photocatalyst has excellent photocatalytic due to the intense coupling between conductive GO nanosheets and TiO2 nanoparticles. Under the optimal photocatalytic degradation test conditions, the degradation efficiency of BDE209 is more than 90%. In addition, this study also provides an efficient route for designing highly active catalytic materials.