VNU-UET Repository: No conditions. Results ordered -Date Deposited. 2024-03-28T09:19:05ZEPrintshttp://eprints.uet.vnu.edu.vn/images/sitelogo.pnghttps://eprints.uet.vnu.edu.vn/eprints/2022-10-26T21:59:46Z2022-10-26T21:59:46Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4164This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41642022-10-26T21:59:46ZFormation and Study of Nanostructured M-Monolayers and LS-Films of TriphenylcorroleThao T. VuLarissa A. MaiorovaDmitrii B. BerezinOskar I. Koifman2020-12-13T15:49:19Z2022-10-26T21:59:50Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4163This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41632020-12-13T15:49:19ZThermal stability of meso-substituted metal corroles in inert and oxidative mediaVu Thi ThaoD. R. KarimovS. S. GuseinovE. V. BalantsevaD. B. Berezin2018-11-15T09:20:10Z2018-11-15T09:20:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3145This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31452018-11-15T09:20:10ZTrue nature of active layers in organic solar cells fabricated by sequential casting of donor and acceptor layersThe operation characteristics of nominal bilayer (BL) organic solar cells (OSCs), the active layers (ALs) of which consisted of sequentially casted bottom P3HT donor and top ICBA acceptor layers, resembled those of OSCs with bulk heterojunction (BHJ) ALs. Optical analysis and device simulations showed that such resemblance can be attributed to a similarity in the micromorphology of ALs; as‐deposited BL‐type ALs transformed spontaneously into BHJ‐type ALs. The inclusion of P3HT nanowires (NWs) in the donor layers resulted in different AL micromorphology and consequently a larger power conversion efficiency. Separate assessment of the exciton generation and charge–carrier transport and/or extraction showed that the contribution of P3HT NWs was more prominent in optical effects.Jong Hyuk YimSung‐yoon JoeDuc Cuong Nguyencuongnd@vnu.edu.vnShin Young RyuNa Young HaY. H. AhnJi‐Yong ParkSoonil Leesoonil@ajou.ac.kr2018-11-15T09:20:01Z2018-11-15T09:20:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3144This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31442018-11-15T09:20:01ZHole‐extraction layer dependence of defect formation and operation of planar CH3NH3PbI3 perovskite solar cellsThree planar CH3NH3PbI3 (MAPbI3) solar cells having the same structure except a hole‐extraction layer (HEL) showed distinctive difference in operation characteristics. Analysis of frequency‐dependent capacitance and dielectric‐loss spectra of the three MAPbI3 devices showed two types of recombination‐loss channels with different time constants that we attributed respectively to interface and bulk defects. Discrepancy in defect formation among the three devices with a HEL of PEDOT:PSS, NiOx, or Cu‐doped NiOx was not surprising because grain‐size distribution and crystalline quality of MAPbI3 can be affected by surface energy and morphology of underlying HELs. We were able to quantify interface and bulk defects in these MAPbI3solar cells based on systematic and simultaneous simulations of capacitance and dielectric‐loss spectra, and current–voltage characteristics by using the device simulator SCAPS.Duc Cuong Nguyencuongnd@vnu.edu.vnSung‐yoon JoeNa Young HaHui Joon ParkJi‐Yong ParkY. H. AhnSoonil Leesoonil@ajou.ac.kr2018-11-15T09:19:47Z2018-11-15T09:19:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3019This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30192018-11-15T09:19:47ZSolution-Processible Crystalline NiO Nanoparticles for High-Performance Planar Perovskite Photovoltaic CellsIn this work, we report on solution-based p-i-n-type planar-structured CH3NH3PbI3 perovskite
photovoltaic (PV) cells, in which pre-crystallized NiO nanoparticles (NPs) without post-treatment are
used to form a hole transport layer (HTL). X-ray diffraction and high-resolution transmission electron
microscopy showed the crystallinity of the NPs, and atomic force microscopy and scanning electron
microscopy confirmed the uniform surfaces of the resultant NiO thin film and the subsequent perovskite
photoactive layer. Compared to the conventional poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, the NiO HTL had excellent energy-level alignment with that of CH3NH3PbI3
and improved electron-blocking capability, as analyzed by photoelectron spectroscopy and diode
modeling, resulting in Voc ~0.13 V higher than conventional PEDOT:PSS-based devices. Consequently, a
power conversion efficiency (PCE) of 15.4% with a high fill factor (FF, 0.74), short-circuit current density
(Jsc, 20.2 mA·cm−2), and open circuit voltage (Voc, 1.04 V) having negligible hysteresis and superior air
stability has been achieved.Uisik KwonBong-Gi KimDuc Cuong Nguyencuongnd@vnu.edu.vnJong-Hyeon ParkNa Young HaSeung-Joo KimSeung Hwan KoSoonil Leesoonil@ajou.ac.krDaeho Leedhl@gachon.ac.krHui Joon Parkhuijoon@ajou.ac.kr2018-10-09T09:58:45Z2018-10-09T09:58:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3089This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30892018-10-09T09:58:45ZFabrication of Ferrite-Based Integrated Micro-Inductors onto Silicon WaferIn this work, the technology for fabricating integrated micro-inductors onto silicon is
developed. The paper will report the experimental process and technology development to
fabricate the micro-inductor on-to silicon substrates with the hybrid integration approach.
Copper is used for the fabrication of the conductor windings and vias. Electro-deposition is
chosen for depositing copper. Via is electro-deposited to make the connection between bottom
tracks and top tracks. The ferrite core is fabricated and sintered from in-house ferrites or
commercial ferrite films.Yen Mai Nguyenmainty85@gmail.comMagali Brunet2017-11-16T04:33:06Z2017-11-16T04:33:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2661This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26612017-11-16T04:33:06ZPOLYESTER KNIT-FABRICS TREATED WITH CATIONIC DIRECT DYES USING PLASMA -INDUCED GRAFT-POLYMERIZATIONPolyester knit-fabrics were treated by argon-helium plasma at room temperature and ambient pressure, subsequently graft-polymerized with acrylic acid in vapor. Plasma interaction to the polyester fibres and graft-polymerization of carboxyl functional groups were investigated. Finally, the polyester knit-fabric grafted with carboxyl groups were treated with cationic direct dyes at around 800C and ambient pressure. Results obtained show that grafted surface of the knit fabrics was dyed with the red color, and then their color surface becomes dark pink while their untreated surface has pinkish white. The graft polymerization of the carboxyl groups and the absorption of cationic direct dyes will be discussed in details.
Keywords: plasma-induced graft-polymerization, polyester-fiber knit-fabrics, cationic direct dyes, polyesterKien Cuong Nguyencuongnk@vnu.edu.vnSeiichi Kataoka2017-11-16T04:26:31Z2017-11-16T04:26:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2633This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26332017-11-16T04:26:31ZSTUDY ON ITO THIN FILMS PREPARED BY
MULTI-ANNEALING TECHNIQUEIndium tin oxide (ITO) thin films have been successfully prepared by a solution process
followed by a multi-annealing method. In this study, we focus on the use of multi-annealing
method, for which each layer was annealed at a suitable temperature, instead of a conventional
annealing way, by means of a rapid thermal annealing system, in order to improve the film
quality. The crystalline structure and surface morphology of the ITO thin films were investigated
by using X-ray diffraction (XRD) spectrometer, atomic force microscope (AFM) and scanning
electron microscope (SEM). It has been obtained that all of ITO films exhibit a single phase with
(200)- and (444)-preferred orientations. The AFM and SEM observations show that the particle
size of ITO films was about 10 nm and the ITO film thickness was 180 nm, respectively. In
sequence, the electrical properties of ITO thin films were evaluated by using four-point probe
and Hall effect measurement methods, and the optical properties were investigated by UV/VIS
spectrometer. The achievement results show that the optimum ITO films possessed electrical
resistivity of 2.6 × 10-3 Ωcm and transparency higher than 90%, which strongly supports to the
application of electrode in solar cell, LED or transistor devices from viewpoints of low-cost
production and low-energy consumption.Quang Hoa NguyenThi Xuyen NguyenQuoc Viet VuongThi Huyen Trang VuHa HoangThi Thanh Tam HoangThi Dung VuVan Dung TranNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vn2017-11-16T04:26:10Z2017-11-16T04:26:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2632This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26322017-11-16T04:26:10ZINVESTIGATION ON STRUCTURAL AND FERROELECTRIC PROPERTIES OF Bi3.25La0.75Ti3O12 THIN FILMSLanthanum doped bismuth titanate (Bi3.25La0.75Ti3O12 abbreviated as BLT) has been known
as one of typical materials for Bi-layered perovskite structure which possess several unique
properties such as good fatigue with metal electrode and stable remanent polarization, hence it
has potential applications in ferroelectric random access memory. In this work, the BLT thin
films were fabricated on Pt/TiO2/SiO2/Si substrates by using a solution process, and then their
features including crystal structure, surface morphology, and electrical properties were
characterized by using X-ray diffraction system (XRD), scanning electron microscopy (SEM),
and electrical measurement system (Radiant Precision LC 10), respectively. The obtained results
point out that the BLT thin film annealed at 725oC is mostly optimum from a viewpoint of film
quality and ferroelectricity. In particular, the optimum BLT thin film having a thickness of 200
nm does not contain any cracks on the sample surface, and the grain size is closed to 400 nm from
SEM observation. XRD patterns imply that the BLT thin film had stoichiometric structure with
preferred orientations of (117) and (006), when annealed at temperatures higher than 725oC. In
addition, we found the influence of La (0.75) dopping on c-axis-oriented growth of BLT thin
films is clear from the structural analysis. The remanent polarization of optimum BLT thin film is
approximately 10 µC/cm2, but the ferroelectric hysteresis loops are not saturated at low applied
voltages.Van Dung TranHa HoangThi Thanh Tam HoangThi Dung VuVan Dung NguyenHong Minh DoThi Huyen Trang VuQuang Hoa NguyenNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vn2017-11-16T02:41:03Z2017-11-16T02:41:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2637This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26372017-11-16T02:41:03ZPhotoluminescence and I -V Characteristics of
Blended Conjugated Polymers/ZnO NanoparticlesAbstract: The investigation of photoluminescence and current-voltage (I-V) characteristics of the
MEH-PPV/PVK blended polymers doped with ZnO nanoparticles (ZnO NPs). First, PVK polymers were mixed with MEH-PPV in respect to the mass-ratio of 100:15, respectively. And
then the MEH-PPV/PVK composites were doped with ZnO NPs with the mass-ratio of 10 wt%, 15 wt% and 20 wt% of total weight blended polymers. Polymer light-emitting diodes (PLEDs), based on a hybrid composite, having structure of ITO/ MEH-PPV/PVK/ZnO/Al were made by spincoated,and subsequently vacuum-thermally evaporated.
UV-Vis absorption, photoluminescence properties, SEM micrographs of the hybrid compositelayer as well as I -V characteristics of the PLED based on the MEH-PPV/ZnO-and PVK/ZnOheterojunction were investigated. Results obtained show that the turn-on voltage of the polymers/ZnO-based PLED is lower than that of the polymers-based PLED without doped ZnO NPs. This is due to the Auger-assisted energy up-conversion process occurring at the polymers/ZnO-heterojunction that could enhance the luminescence efficiency of the PLED.
Keywords: PLED, photoluminescence efficiency, MEH-PPV, PVK, SEM, spin coating, thermal
vacuum evaporationKien Cuong Nguyencuongnk@vnu.edu.vn2017-11-09T03:21:27Z2017-11-09T03:21:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2624This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26242017-11-09T03:21:27ZLow-temperature PZT thin-film ferroelectric memories fabricated on SiO2/Si and glass substratesIn a ferroelectric-gate thin film transistor memory (FGT) type structure, the gate-insulator layer is
extremely important for inducing the charge when accumulating or depleting. We concentrated on the
application of low-temperature PZT films crystallized at 450, 500 and 550 �C, instead of at conventional
high temperatures (�600 �C). Investigation of the crystalline structure and electrical properties indicated
that the PZT film, crystallized at 500 �C, was suitable for FGT fabrication because of a high (111) orientation,
large remnant polarization of 38 mC/cm2 on SiO2/Si substrate and 17.8 mC/cm2 on glass, and low
leakage current of 10�6 A/cm2. In sequence, we successfully fabricated FGT with all processes below
500 �C on a glass substrate, whose operation exhibits a memory window of 4 V, ON/OFF current ratio of
105, field-effect mobility of 0.092 cm2 V�1 s�1, and retention time of 1 h.Hong Minh DoVan Loi NguyenHuu Duc Nguyenducnh@vnu.edu.vnNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vn2017-06-10T11:28:30Z2017-06-10T11:28:30Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2469This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24692017-06-10T11:28:30ZPolymer dẫn và điôt phát quang hữu cơTrong gần 15 năm lại đây nhóm chúng tôi đã tiến hành các nghiên cứu khoa học về vật liệu và linh kiện trên cơ sở polymer dẫn và tổ hợp nanô polymer với ôxit kim loại. Các loại linh kiện được tập thể khoa học tập trung nghiên cứu và triển khai ứng dụng là OLED, pin mặt trời hữu cơ (OSC) và sensor màng mỏng hữu cơ (OTFS). Nhằm phần nào đáp ứng nhu cầu người đọc về vật liệu polymer và linh kiện vi điện tử hữu cơ đầy triển vọng ứng dụng này, tác giả tập trung biên soạn sách chuyên khảo “Polymer dẫn và điôt phát quang hữu cơ”. Sách được biên soạn một cách chọn lọc, cập nhật phân tích các công trình khoa học của nhiều tác giả trên thế giới và một phần đáng kể từ các công trình khoa học, luận án tiến sĩ của các thành viên trong Nhóm. Sách này có thể làm tài liệu học tập, tra cứu, tham khảo trong lĩnh vực chuyên sâu về polymer dẫn và OLED.
Sách gồm Phần mở đầu, 5 chương và Kết luận. Các chương là:
CHƯƠNG I. POLYMER DẪN ĐIỆN VÀ LINH KIỆN PHÁT QUANG HỮU CƠ
CHƯƠNG 2. CÁC KĨ THUẬT SỬ DỤNG TRONG CÔNG NGHỆ CHẾ TẠO VÀ ĐẶC TRƯNG TÍNH CHẤT VẬT LIỆU VÀ LINH KIỆN OLED
CHƯƠNG 3. TÍNH CHẤT CỦA VẬT LIỆU VÀ LINH KIỆN OLED THUẦN KHIẾT POLYMER
CHƯƠNG 4. VẬT LIỆU TỔ HỢP CẤU TRÚC NANÔ KHỐI VÀ LINH KIỆN OLED
CHƯƠNG 5. VẬT LIỆU VÀ LINH KIỆN OLED PHÁT XẠ NGƯỢCNang Dinh Nguyendinhnn@vnu.edu.vn2017-01-05T02:42:24Z2017-01-05T02:42:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2353This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23532017-01-05T02:42:24ZHigh accuracy electronic compass for detecting azimuth direction based on a novel magnetoelectric effectMost navigation systems today use compass to determine heading direction based on determining the earth’s magnetic fields in a horizontal plane. There are several types of electronic compasses based on different effects such as fluxgate, magnetoresistive, and magnetoinductive. This paper presents a novel electronics compassing for navigation system, a modification of the conventional magnetic compass, which based on magnetoelectric effect. Recent researches have shown that thanks to enhancement of shape magnetic anisotropy of Metglas ribbon, an high magnetic sensitivity (~Voltage/Tesla), and extremely high accurary (1 nanoTesla) geomagnetic sensors based on Metglas/PZT magnetoelectric laminate were built [1]. By intergrating 2-axis sensor with an electronic circuit and 12-bit ADC (Fig. 1), a high resolution magnetoelectric compass containing anplifcation, automatic degaussing, offset cancellation that enables 0.1 degree compass heading accuracy. This kind of magnetoelectric compass would contribute to the most sensitive and high accuracy electronic compass available in the industry todayThi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vn2016-12-31T14:34:59Z2016-12-31T14:34:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2339This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23392016-12-31T14:34:59ZThe mechanical effect and physics properties of ZnO nanoparticles in nanocomposite organic solar cell P3HT:PCBMDoping particles into composite materials can mechanically stabilize these structure. At nanoscale, doping nanoparticles not only strengthen the material structure but also improve some mechanical and physical properties of materials. In this work, we will investigate the role of ZnO nanoparticles (NPs) doping into the nanocompsite multilayer organic solar cell (OSC) with the active layer composed of P3HT:PCBM. ZnO NPs is an economical ingredient for some applications in organic solar cell devices. They not only enhance significantly the absorption of the incident light but also make the composite nanostructure in OSC more durable. The absorption properties such as the absorption intensity can be explained by Mie scattering theory and studied numerically using finite element method (FEM). The mechanical effects can be illustrated by Young and Bulk modulus.Dinh Long Dangddlong@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2016-12-31T14:30:59Z2016-12-31T14:30:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2336This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23362016-12-31T14:30:59ZThe Physics of Spin-1/2 XY Model with Four-Site Exchange Interaction on the Kagome LatticeThe quantum spin liquid (QSL) state, proposed more than three decades ago by Fazekas and Anderson remains surprisingly elusive. Although recent experiments provide a strong evidence of their existence in the frustrated spin systems, the microscopic model for this state is still rare. The extensive theoretical framework, developed over decades, continues to extend further motivated by these and other discoveries from large-scale computer simulations of a relatively small number of models. In this work, we discuss the physics of the ground-state phase diagram of a two- dimensional Kagome lattice spin-1/2 XY model with a four-site ring-exchange interaction using quantum Monte Carlo simulation. We found the second order phase transition from superfluid state to a Z2 quantum spin liquid phase driven by the four-site ring exchange interaction. We have characterized the QSL by its vanishing order parameters such as the spin-spin structure factor, the plaquette-plaquette structure factor. Moreover, we have found the large anomalous exponent ηXY* ≈ 1.325 which belongs to a different universality class other than 3D XY universality class. There is no signal of supersolid phase intervening between the superfluid state and QSL state.Thi Kim Oanh NguyenThanh Dai PhamDinh Long Dangddlong@vnu.edu.vn2016-12-31T14:28:29Z2016-12-31T14:28:29Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2334This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23342016-12-31T14:28:29ZElectric-field Control of a Spin “bit” Configuration in MERAM Model: A Monte Carlo StudyMagnetoelectric (ME) effect can be realized in multiferroic composites composed of the alternative ferromagnetic (FM) and ferroelectric (FE) multilayer such as FM layer grown on top of FE layer (FM/FE). In this work, we have shown that the spin orientation in FM layer can be controlled by using the electrical field indirectly via the elastic mechanism between these layers. There is a critical electric field for each FM layer such as Fe, Fe3O4, which is the minimum electric field to switch the spin to the different directions in space. The Monte Carlo simulation has been applied for the anisotropy model taken into account the magnetocrystalline anisotropy and shape anisotropy as well as the effective anisotropy field. The particular spin switching, i.e. an angle of 90 degree switching, corresponding to bit “0” and “1” switching in magnetoelectric random access memory (MERAM) will be discussed.Long Dangddlong@vnu.edu.vn2016-12-31T14:23:03Z2016-12-31T14:23:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2269This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22692016-12-31T14:23:03ZMeasurement of Iron-Oxide Fluids Using a Magnetoelectric SensorIron oxide fluids have been measured by using a magnetoelectric (ME) effect - based magnetic sensor with a long-type sandwiched composite of Metglass/PZT/Meglass laminates of 1×15 mm2 in dimension. In homogeneous magnetic fields, the sensor exhibits a sensitivity of 307.453 mV/Oe. The minimum measurable signal (i.e. noise level) of this experimental setup was found as small as 0.782 mV, which reveals a possible detection limit of 3×10−8 emu . Our report presents the simulation and the measurement of magnetic fluids of various magnetic Fe3O4 nanoparticle concentrations. The results open a possibility of using this sensor for medical and bioengineering applications.Xuan Toan NguyenThi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vn2016-12-31T14:20:18Z2016-12-31T14:20:18Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2335This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23352016-12-31T14:20:18ZPreparation and characterization of nanorod-like TiO2 and ZnO films used for charge- transport buffer layers in P3HT based organic solar cellsWith the aim of findingout the appropriate buffer layers for organic solar cells (OSC), TiO2 and ZnO on ITO/glass were prepared as nanorod-like thin films. The TiO2 films were crystallyzed in the anatase phase and the ZnO films, in the wurtzite structure. The nanorods in both the fims have a similar size of 15 to 20 nm in diameter and 30 to 50 nm in length. The nanorods have an orientation nearly perpendicular to the ITO-substrate surface. From UV-Vis data the bandgap of the TiO2 and ZnO films were determined tobe 3.26 eV and 3.42 eV, respectively. The laminar organic solar cells with added TiO2 and ZnO, namely ITO/TiO2/P3HT:PCBM/LiF/Al (TBD) and ITO/ZnO/P3HT:PCBM/LiF/Al (ZBD)were made for characterization of the energy conversion performance. As a result, comparing to TiO2,the nanorod-likeZnO filmwas found to be a much better buffer layer that made the fill factor improve from a value of 0.60 for TBD to 0.82 for ZBD, and consequently thePCE was enhanced from 0.84 for TBD to 1.17% for ZBD.Thi Thao Tranthaott@vnu.edu.vnDinh Long Dangddlong@vnu.edu.vnVan Truong VoNang Dinh Nguyendinhnn@vnu.edu.vn2016-12-31T10:22:45Z2016-12-31T10:22:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2380This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23802016-12-31T10:22:45ZLipid biosynthesis of ten Thraustochyrid strains isolated from mangrove Xuan Thuy, Nam DinhThe features of polyunsaturated fatty acid-PUFA structures were corresponded to each separate functions as adjusting the cellular physiology and gene expression. Therefore, lack of PUFA could lead to abnormalities in skin, kidney, neural networks, immune responses and inflammation; cardiovascular, endocrine, respiratory and reproductive systems. In fish oil, PUFA content were low, thus it was difficult to produce on a large scale. Therefore, the exploration of PUFA sources particularly as arachidonic acid-AA, eicosapentaenoic acid EPA, docosapentaenoic acid-DPA/DHA attracted many researches. Heterotrophic microalgae Thraustochytrids were capable of producing high amounts of DHA and PUFA composition varied. DHA can be synthesized by the metabolism of AA, EPA and DPA. The different types of PUFA reflected relationships in classification. Ten heterotrophic microalgae thraustochytrids isolated from mangrove Xuan Thuy, Nam Dinh contain fatty acid composition varied from C12 to C28. Especially, they had two important fatty acids of PUFA as EPA and DPA. Polyunsaturated fatty acids - PUFA content of ten thraustochytrid strains were from 28.95 to 49.62% total lipid. DPA compared to other PUFA were high for all thraustochytrid strains studied, accounting 20.22 to 39.35% TFA. Ten thraustochytrid strains had the highest growth with carbon source as glucose, total lipid reached 7 to 12.35 % dry weight biomass after 72 hours. Growth rate and lipid biosynthesis in organic nitrogen source were higher than in inorganic nitrogen sources. The best source of nitrogen for growth and lipid biosynthesis of ten thraustochytrid strains is yeast extract, total lipid were 8.57 to 18.87% dry weight biomass after 72 hours.Thi Bich Dao PhamDinh Tuan NguyenDang Khoa Trankhoatd@vnu.edu.vnThi Huyen ChuHoang Thanh DoThi Hoai Ha Nguyen2016-12-31T10:21:25Z2016-12-31T10:21:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2211This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22112016-12-31T10:21:25ZDetection of magnetic nanoparticles using simple AMR sensors in Wheatstone bridgeWheatstone bridges incorporating a serially connected ensemble of simple AMR elements of Ni80Fe20 film were produced, targeting an application of a pinned magnetic field along the sensing magnetoresistor length. For the optimal dimension, the magnetoresistive element with length l 4 µm, width 150 µm and thickness 5 nm still shows a rather modest AMR ratio (of about 0.85% only). However, the resulting bridge exhibits a sensitivity as large as 2.15 mV/Oe. This is according to a standard sensitivity of 1.80 mV/V/Oe and a detection limit better than 10_6 emu, which is almost doubled with respect to that in the typical commercial AMR devices and is comparable with Permalloy based PHE sensor. This is suitable to detect the superparamagnetic fluid of 50 nm-Fe3O4-chitosan.Khac Quynh LeDinh Tu Buibuidinhtu@vnu.edu.vnXuan Dang DangQuoc Viet DongThi Hien Lelehien@vnu.edu.vnThi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vn2016-12-31T10:18:46Z2016-12-31T10:18:46Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2212This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22122016-12-31T10:18:46ZDetection of magnetically labeled DNA by a magnetic sensor
operating with a disposable cardDisposable cards with immobilized bioreceptors are being increasingly investigated and developed in biomedical analysis systems because they have significant advantages. In our work, a biosensor system consisting of an anisotropic magnetoresistive (AMR) sensor operating with a disposable card was developed for magnetically labeled DNA detection. The SPA/SAA/APTES/PDMS/Si as-prepared disposable card involves DNA probes specific for the 16S rRNA gene of Streptococcus suis. A single-stranded target DNA was hybridized with the DNA probe on the disposable card, which was subsequently magnetically labeled with superparamagnetic beads for detection using the AMR sensor. An almost linear response between the output signal of the AMR sensor and amount of single-stranded target DNA varied from 4.5 to 18 pmol was identified. This novel approach opens up new possibilities for the development of a sensitive, easy to use and low-cost DNA biosensor system.Thi Hien Lelehien@vnu.edu.vnKhac Quynh LeThi Huyen VuThi Yen NguyenDinh Tu Buibuidinhtu@vnu.edu.vnHong Nhung PhamThi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vn2016-12-31T10:14:37Z2016-12-31T10:14:37Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2352This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23522016-12-31T10:14:37ZAspects of nondestructive detections using a magnetoelectric sensorThis article deals with the state-of-the-art techniques in the field of nondestructive (and/or distance) detections. Illustrations are described for a wide range of applications from local evaluations of magnetic nanoparticles at a depth of several centimeters in the body during clinical interventions to blood pulse analysis and pipe and cable monitoring. Developments are implemented using a magnetoelectric based magnetic sensor with a long type sandwich Metglas/PZT/Meglas laminate composite of 1×15 mm2 dimension. In the resonant mode, the sensor exhibits a sensitivity better than 200 mV/Oe and a detection limit of 3×10−8 emu. This method can detect a spot with at least 50 µg iron oxide magnetic nanoparticles at a distance of about 10 mm from the skin surface. For the radial pulse analysis, thanks to the disturbance created by blood flowing through a localized magnetic field, not only the information of the heard rate, but also the radial blood flow waveforms are monitored (fig. 1), which strongly supports the traditional Chinese medicine. Moreover, this universal detector type can also be performed for locating wood, metal, copper, iron and live wires in the walls. It is indispensable tools for any contractors in the building who have to drill holes into walls as well as building inspectors who want to making a report on a site. The magnetoelectric sensors, thus, exhibit a high potential of applications.Thi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vn2016-12-31T10:06:32Z2016-12-31T10:06:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2201This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22012016-12-31T10:06:32ZLight Absorption And Luminescence Properties of the Blend Pol(N-Vinylcarbazole)/Poly(N-Hexylthiophene)We have investigated the enhancement of light absorption and luminescence properties of the blend conducting polymers using poly(N-vinylcarbazole) and poly(N-hexylthiophene). The optimizedmaterial showed a broad absorption in the region from ultra violet to near infra-red and the better of luminescence ability than the pristine conducting polymers. The remarkable improvements in photoluminescence of the blends provide useful information to the application of this material in fabrication of optical – electronic devices.Phuong Hoai Nam Nguyennamnph@vnu.edu.vnMai Ha HoangTrinh Tung NgoDinh Long Dangddlong@vnu.edu.vnKhac Quan NguyenDuy Lien Vu2016-12-27T07:27:52Z2016-12-27T07:27:52Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2268This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22682016-12-27T07:27:52ZDNA-magnetic bead detection using disposable cards and the anisotropic magnetoresistive sensorA disposable card incorporating specific DNA probes targeting the 16 S rRNA gene of
Streptococcus suis was developed for magnetically labeled target DNA detection. A singlestranded
target DNA was hybridized with the DNA probe on the SPA/APTES/PDMS/Si asprepared
card, which was subsequently magnetically labeled with superparamagnetic beads for
detection using an anisotropic magnetoresistive (AMR) sensor. An almost linear response
between the output signal of the AMR sensor and amount of single-stranded target DNA varied
from 4.5 to 18 pmol was identified. From the sensor output signal response towards the mass of magnetic beads which were directly immobilized on the disposable card surface, the limit of detection was estimated about 312 ng ferrites, which corresponds to 3.8 μemu. In comparison with DNA detection by conventional biosensor based on magnetic bead labeling, disposable cards are featured with higher efficiency and performances, ease of use and less running cost with respects to consumables for biosensor in biomedical analysis systems operating with immobilized bioreceptorThi Hien Lelehien@vnu.edu.vnKhanh Quynh LeThi Huyen VuDinh Tu Buibuidinhtu@vnu.edu.vnPhuong DMNhung PHThi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vn2016-12-14T08:29:23Z2016-12-14T08:29:23Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2027This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20272016-12-14T08:29:23ZSelection of lactic acid bacteria producing bacteriocinIn this work, lactic acid bacteria were isolated from 10 samples of the traditionally fermented foods (5 samples of Vietnamese fermented pork roll and 5 samples of the salted field cabbage) and 5 samples of fresh cow milks. These samples were collected from households in Vietnam. 22 strains of lactic acid bacteria were isolated for inhibition to Lactobacillus plantarum JCM 1149. Of these, only 2 strains including DC1.8 and NC1.2 have rod shape, the others have coccus shape. There were 7 strains showing higher antibacterial activity and selected forchecking spectrum of antibacteria with indicator bacteria consistting of Bacillus subtilis ATCC 6633, Enterococcus faecium JCM 5804 and Staphylococcus aureus TLU. . . By which, 3 strains including NC3.5 (from Vietnamese fermented pork roll), DC1.8 (from salted field cabbage) and MC3.19 (from fresh cow milk) were selected because of their higher antibacterial ability. However, the antibacterial activity of the lactic acid bacteria can be based on disposable compounds of them and some other antibacterial compounds produced during of their growth (such as lactic acid, H2O2, bacteriocins, …). For seeking lactic acid bacteria with capability of producing bacteriocins, antibacterial compounds with protein nature, , 3 above strains were checked sensitive to proteases (including protease K, papain, α – chymotrypsin and trypsin). Because bacteriocins are proteinaceous antibacterial compounds, so their antibacterial activity will be reduced if proteases are added. The result showed DC1.8 and MC3.19 were capable of producing bacteriocin during culture process. These two strains were classified to species based on analysis chemical characterisitcs by standard API 50 CHL kit and phylogeny relationship by 16s rRNA sequences. DC1.8 was identified as Lactobacillus acidophilus and MC3.19 as Lactococcus lactis.Thi Quyen Haquyenht@vnu.edu.vnThi Minh Tu Hoahoaminhtu@gmail.com2016-12-12T03:52:24Z2016-12-12T03:52:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2005This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20052016-12-12T03:52:24ZSynthesis of Gold Nanoparticles Capped with Quaterthiophene
for Transistor and Resistor Memory DevicesMai Ha HoangThanh Toan DaoThi Thu Trang NguyenPhuong Hoai Nam Nguyennamnph@vnu.edu.vnTrinh Tung Ngo2016-12-08T03:46:19Z2016-12-08T03:46:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2023This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20232016-12-08T03:46:19ZPreparation and characterization of La0.67-xLi3xTiO3 solid-state electrolyte used for electrochromic mirrorsWith the aim of producing all-solid-state electrochromic mirrors, La0.67-xLi3xTiO3 (LLTO) and the WO3 were prepared by electron beam deposition. The LLTO (with x = 0.11) powder was synthesized by thermally ball-grinding method and the Li+ ionic conductivity of the LLTO ceramic targets was found to be of ca. 3.25 10-3 S/cm. Using LLTO targets for e-beam evaporation, 300 nm – thick films with the Li+ ionic conductivity of 5.50 10-5 S/cm were deposited. Combining LLTO films with WO3/ITO and LiMn2O4 layers, all-solid-state electrochromic mirrors with a laminar structure of Al/LiMn2O4/LLTO/WO3/ITO were prepared. The reversible reflectance of the mirrors was well controlled by applying polarized potentials onto the ITO electrode. The obtained results suggest useful applications for electrochromic windows working as a smart reflectance mirror that can be used for auto rear-view mirrors.Dinh Trong LeNang Dinh Nguyendinhnn@vnu.edu.vnHong Thanh Do2016-12-08T03:40:11Z2016-12-08T03:40:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2004This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20042016-12-08T03:40:11ZSynthesis and Characterization of Polymeric Graphene-Quantum-Dots based Nanocomposites for Humidity SensingGraphene quantum dots (GQDs) were synthesized and incorporated with polyethylenedioxythiophene: poly(4-styrenesulfonate) (PEDOT:PSS) and carbon nanotube (CNT) to form a composite that can be used for humidity sensors. The 600 nm-thick composite films contained bulk heterojunctions of CNT/GQD and CNT/PEDOT:PSS. The sensors made from the composites responded well to humidity in a range from 60 to 80% at room temperature and atmospheric pressure. With a CNT content of 0.4 wt.% (GPC-1) to 0.8 wt.% (GPC-2) and 1.2 wt.% (GPC-3), the sensitivity of the humidity sensing devices based on CNT-doped graphene quantum dot-PEDOT:PSS composites was increased from 4.5% (GPC-1) to 9.0 % (GPC-1) and 11.0 % (GPC-2), respectively. The fast response time of the GPC sensors was about 20 s and it was much improved due to CNTs doping in the composites. The best value of the recovery time was found to be of 40 s, for the GPC composite film doped with 1.2 wt.% CNT content.Minh Long LamNang Dinh Nguyendinhnn@vnu.edu.vnQuang Trung Tran2016-12-07T08:26:35Z2016-12-07T08:27:20Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2022This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20222016-12-07T08:26:35ZCharacterization of Electrochromic Properties of Polyaniline Thin Films Electropolymerized in H2SO4 SolutionPolyaniline (PANI) onto indium-doped tin-oxide (ITO)-coated glass samples were prepared by electroopolymerization in 0.5 M H2SO4 solution. Structure and morphology characterization of the PANI films demonstrated that the films were grown onto ITO substrates in the form of polycrystalline microbelts separated by micropores. By analysing the UV-Vis absorption spectra of the PANI films, the energy bandgap was found to be approximately 2.75 eV. The PANI/ITO films exhibited a good reversible electrochromic display (ECD) performance when cycled in 0.1 M LiClO4 + pro-pylene carbonate. The response time of the ECD coloration was found to be as small as 15 s and the coloration efficiency was found to be 8.85 cm2 C-1. After 100 cycles of the ECD performance, the cyclic voltammetry curve of the working electrode maintained unchanged. This demonstrates that the electropolymerized PANI films can be served as a good candidate for ECD applications, taking advantage of their excellent properties in terms of chemical stability.Hai Ninh DangThi Thao Tranthaott@vnu.edu.vnDuy Long PhamNang Dinh Nguyendinhnn@vnu.edu.vn2016-12-04T13:44:22Z2017-01-17T02:46:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2062This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20622016-12-04T13:44:22ZThe 2016 Annual Scientific Report of VNU University of Engineering and TechnologyThe University of Engineering and Technology (UET) was founded in 2004 as a member university of Vietnam National University, Hanoi (VNU).
The last only five years have seen immense progresses in the development of our university in various aspects of its activities thanks to the great efforts put in by the government with strong financial supports, by the VNU with steering leadership and administration, by the national and international educational institutions and corporations in fruitful collaborations and advices, and by all the staff and students of the UET with determination, hard work and patience.
Today, our university has built up a solid foundation for a sustainable and dynamic development in coming years. This solid foundation consists of a completed system of well-designed programs at both undergraduate and graduate levels, renovated teaching and learning facilities, a just limited but strong and advanced research infrastructure with state-of-the-art and completed equipment systems, a sustainable and fruitful collaboration with leading research and educational institutions in the country, and a bright, young, well-educated and welltrained faculty who are eager to take on advanced research and studies. All these have made our university a prestigious institution and firmly established its education and research capabilities. This is proved by the facts that only in the last four years our university has established close and solid ties and cooperation with prestigious foreign universities, just to name a few, the University Paris-Sud 11 (France), Japan Advanced Institute of Science and Technology, the National University of Singapore, Nanyang Technological University (Singapore), University of New South Wales and with famous international industrial and technological corporations such as Samsung, Toshiba, NEC, Mitani, Human Resocia, IBM, and other well-known institutions in the region and around the world. This is also proved in a convincing way by the facts that only in the last two years, our university has been granted several significant research projects from various national research programs. Our university has become an attractive destination for talented students at all training levels. We are proud that our university is the only Vietnamese higher-education institution that has one among the 100 best student’s teams all over the world participating the World Final of the ACM International Collegiate Programming Contest (rank #29 in 2015). We are also proud that in this year, our faculty has won an award in the National Contest in Information Technology entitled “Vietnamese Talent Award” and three awards in the VNU Science & Technology Award for the period of 2011-2015. In the coming period, we shall put our great efforts to solidify our strength and prestige. We shall widen our training scope while paying significant attention to further improvement on the education quality. We shall strongly enhance our concentrated research activity by exploring efficiently and effectively our well established foundation for a further dynamic development and, thus, contributing our crucial part to the socio-economic development of our nation and fulfilling our great missions clearly assigned by the government in the decision on the establishment of our university. To do that, innovative thinking and acting by all faculty, administrative staff and students are of deciding role and of crucial importance.Xuan Tu Trantutx@vnu.edu.vnAnh Cuong Lecuongla@vnu.edu.vnDuc Tan Trantantd@vnu.edu.vnManh Thang Phamthangpm@vnu.edu.vnThi Huong Giang Dogiangdth@vnu.edu.vn2016-12-02T06:51:59Z2016-12-02T06:51:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2024This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20242016-12-02T06:51:59ZSynthesis and Characterization of Ag/PEDOT:PSS films used for NH3 selective sensingNano-Ag/PEDOT-PSS films were prepared by spin-coating technique. SEM surface morphology, Raman spectra and gas sensing of methanol, humidity and NH3 were studied. The obtained results showed that the resistance of Ag/PEDOT:PSS sheets exposed to gases related to the generation of electrons from the gases adsorption that eliminated holes as the major carriers in PEDOT:PSS. For NH3 gas the largest change of the resistance of Ag/PEDOT:PSS was observed. The less sensitivity of humidity and ethanol sensing was explained due to less dedoping reaction between H2O and ethanol vapor with Ag/PEDOT:PSS, recpectively. This suggests a potential application of the nano-Ag/PEDOT-PSS sensors for the selective monitoring NH3 gas in environment.Minh Long LamNang Dinh Nguyendinhnn@vnu.edu.vnQuang Trung Tran2016-07-11T12:40:48Z2016-07-11T12:41:42Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1811This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/18112016-07-11T12:40:48ZMEH-PPV: PCBM Solution for Screen-printing Technique in Polymer Solar Cell FabricationThe fabrication and property characterization of bulk heterojunction photoactive layer made of blend of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM) and fabricated by screen-printing technique was carried out. Effects of the photoactive solid concentration, temperatures at 15, 25 and 35°C and shear rate ranging from 100-104 sec–1 on the viscosity was investigated and shows that 1, 3 and 5% solid concentrated solutions are possible for using as ink in this technique in term of rheological property. Thickness of the films fabricated from different solid concentrated solutions at different print speed was measured and show a dependency of film thickness on print speed as well as exponential law dependence on solid concentration of the solution. Surface morphology and absorption coefficient of the films was also carried out and confirms that the films formed by the screen printer is well-adapted for fabricate photovoltaic devices.Van Chau Dinhdinhchau@vnu.edu.vnVan Thuong Dinh2016-07-11T12:28:23Z2016-12-10T10:59:26Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1803This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/18032016-07-11T12:28:23ZLight Absorption and Luminescence Quenching Properties of Hybrid Bulk Heterojunction Materials Based on the Blend Conducting PolymersWe have investigated the enhancement absorption light and luminescence quenching properties of the hybrid bulk heterojunction systems which were fabricated using poly[2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV); poly(3-hexylthiophene) (P3HT); fullerene derivative 1-(3-methoxycarbonyl) propyl-1-phenyl-[6,6] C61 (PCBM) and TiO2 nanocrystals. The optimized material showed a broad absorption in the region of 350 to 670 nm and the luminescence quenching higher 85%. The obtained results provide further insight into photophysics of the heterojunction system and device performance improvement by using this system as an active layer.Phuong Hoai Nam Nguyennamnph@vnu.edu.vnNang Dinh Nguyendinhnn@vnu.edu.vnThu Ha LeTrinh Tung Ngo2016-05-27T03:13:37Z2016-05-27T03:14:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1757This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/17572016-05-27T03:13:37ZFabrication and characterization of PZT string based MEMS devicesString based MEMS devices recently attract world technology development thanks to their advantages over cantilever ones. Approaching to this direction, the paper reports on the micro-fabrication and characterization of free-standing doubly clamped piezoelectric beams based on heterostructures of Pd/FeNi/Pd/PZT/LSMO/STO/Si. The displacement of strings is investigated in both static and dynamic mode. The static response exhibits a bending displacement as large as 1.2 μm, whereas the dynamic response shows a strong resonance with a high quality factor of 40 depending on the resonant mode at atmospheric pressure. These findings are comparable with those observed in large dimension membrane and cantilever based MEMS devices, which exhibit high potentials in variety of sensor and resonant actuator applications.Thi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vnG. AgnusT. MaroutianPhilippe Lecoeur2016-05-23T02:17:06Z2016-05-23T02:19:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1565This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/15652016-05-23T02:17:06ZSub-100nm ferroelectric-gate thin film transistor fabricated by two-step patterning methodFerroelectric-gate thin film transistor (FGT) which uses an active oxide-semiconductor channel and a ferroelectric-gate insulator has attracted wide attention for the application of a new nonvolatile memory because of its prominent features such as simple device structure, high-speed operation and low power consumption. Recently, we have reported on demonstration of the of FGTs operation. However, the FGTs developed have channel lengths (LDS) more than 100 nm, which should be reduced for high-density storage in integration circuits.1-2) In this paper, we will present a new method to fabricate the sub-100 nm FGT, of which the source-drain gap would be surely created, in principle, comparing with the conventional patterning method. Electrical properties and memory functionalities of the fabricated sub-100nm FGTs will be investigated and discussed in detail.Hong Minh DoDuc Thang Phampdthang@vnu.edu.vnNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vn2016-05-23T01:28:55Z2016-05-23T01:31:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1568This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/15682016-05-23T01:28:55ZResearch, manufacturing optimal structure sensor measure the low magnetic field structure Wheatstone bridge base on anistropic magnetoresistance effectsFabrication and study of sensors applied to measure low magnetic fields whose the Wheatstone structure basing on anisotropic magnetoresistance effects. The configuration optimatization of sensors was conducted by varying the thickness of NiFe layers (5, 10, 15 nm) as well as the structure of resistive bars. Two types of sensor with the sizes of 50×250 μm and 10×250 μm were examined. The results revealed the significant dependence of sensor signals on sensor shape anisotropy. The resistivie difference (ΔR), the sensitity (SH) and the shape anisotropy were observed to increase as decreasing the thickness of NiFe layer. The highest values (ΔR and SH were obtained to be 10Ω and 0.88 Ω/Oe (~ 0,88 mV/Oe), respectively) were found in the sensor with the size of 10×250 μm and 5 nm-thickness. The function of the output voltage versus the Earth's magnetic field and the sensor axis was fitted to be V = A + B*cosα (A, B are empirical constants), and Sα = 8.8 (μV/deg.)Khac Quynh LeDinh Tu Buibuidinhtu@vnu.edu.vnQ. Viet D.T. Thuy N.Xuan Toan NguyenMau Danh TranHuu Duc Nguyenducnh@vnu.edu.vnThi Huong Giang Dogiangdth@vnu.edu.vn2016-05-23T01:25:57Z2016-05-23T01:26:56Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1569This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/15692016-05-23T01:25:57ZChế tạo, nghiên cứu cấu trúc và tính chất của một số hệ màng mỏng hợp kim AuFeCông nghệ cấy ion bằng máy gia tốc hiện nay là một trong những phương pháp rất hiện đại trong việc chế tạo và nghiên cứu tính chất của vật liệu, đặc biệt trong việc chế tạo các vật liệu khó hòa tan như H, C ...vào các màng mỏng kim loại. Màng mỏng hợp kim AuFe được chế tạo bằng phương pháp bốc bay nhiệt trong chân không. Sau đó, bằng máy gia tốc pelletron 5SDH-2 chúng tôi đã cấy ion C để tạo nên 5 hệ mẫu AuFe+C với nồng độ C khác nhau. Các hình thái cấu trúc, các tính chất điện, từ, quang học cũng đã được chúng tôi khảo sát. Các kết quả cho thấy rằng, màng mỏng AuFe được hình thành với tỉ lệ 1:3 và tương đối đồng đều. Các màng mỏng AuFe+C đã có sự thay đổi kích thước ô mạng, đặc biệt độ dẫn tương đối của màng này lớn hơn với màng AuFe gốc và thể hiện tính dẫn điện khá tốt, đỉnh hấp thụ cực đại nằm trong vùng ánh sáng tím và đặc biệt là sự xuất hiện của đỉnh phát xạ ở khoảng 415nm. Ngoài ra, chúng tôi còn khảo sát thêm một số tính chất khác của màng mỏng này như tính chất từ tại vùng nhiệt độ từ 80K đến 1000K.Khac Thuan NguyenNam Nhat Hoangnhathn@vnu.edu.vn2016-05-23T01:16:42Z2016-05-23T01:18:11Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1571This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/15712016-05-23T01:16:42ZNonlinear Dynamic Response and Vibration of Imperfect Shear Deformable Functionally Graded Plates Subjected to Blast and Thermal LoadsBased on Reddy’s higher-order shear deformation plate theory, this paper presents an analysis of the nonlinear dynamic response and vibration of imperfect functionally graded material (FGM) thick plates subjected to blast and thermal loads resting on elastic foundations. The material properties are assumed to be temperature-dependent and graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. Numerical results for the dynamic response and vibration of the FGM plates with two cases of boundary conditions are obtained by the Galerkin method and fourth-order Runge- Kutta method. The results show the effects of geometrical parameters, material properties, imperfections, temperature increment, elastic foundations and boundary conditions on the nonlinear dynamic response and vibration of FGM plates.Duc Tuan NgoPhuong TranQuoc Quan TranDinh Duc Nguyenducnd@vnu.edu.vn2016-05-23T01:14:46Z2016-05-23T01:23:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1572This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/15722016-05-23T01:14:46ZPhát hiện lượng hạt từ kích thước nano bằng cảm biến từ trường siêu nhạyPhát hiện các hạt siêu thuận từ kích thước nano đòi hỏi phải có một cảm biến từ trường với độ nhạy cao, độ phân giải lớn và tỷ số tín hiệu/nhiễu cao. Chúng tôi đã chế tạo thành công cảm biến dựa trên hiệu ứng từ-điện (ME - magnetoelectric) trên vật liệu tổ hợp Metglas/PZT đạt độ phân giải trong khoảng nanoTesla. Báo cáo này trình bày các kết quả đo đạc thực nghiệm trên dung dịch chứa các hạt siêu thuận từ Fe3O4 kích thước 20 nm ở các nồng độ khác nhau sử dụng cảm biếm tự chế tạo. Kết quả đo đạc thực nghiệm với cảm biến tự chế tạo đã phát hiện được lượng rất nhỏ (~100 nanogram) các hạt siêu thuận từ mà các phương pháp đo không tiếp xúc thông thường không phát hiện được. Các kết quả nghiên cứu này mở ra khả năng chế tạo các cảm biến sinh học dùng trong các bộ KIT nhận biết và đo đạc định lượng các phần tử sinh học có đánh dấu từ rất nhỏ với độ chính xác và độ tin cậy cao.Xuan Toan NguyenXuan Dang DangKhac Quynh LeDinh Tu Buibuidinhtu@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vnThi Huong Giang Dogiangdth@vnu.edu.vn2016-05-23T01:09:24Z2016-05-23T01:12:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1573This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/15732016-05-23T01:09:24ZOptical Property and Photoelectrical Performance of a Low-Bandgap Conducting Polymer Incorporated With Quantum Dots Used for Organic Solar CellsBy using spin-coating technique, a low bandgap conjugated polymer, poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopen-ta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and its composite thin films have been prepared. The optical absorption and photoconductive properties with over a wide spectral range, from 350 to 950 nm, were characterized. The obtained results showed that PCPDTBT:10 wt% CdSe composite is the most suitable for efficient light-harvesting in polymer-based photovoltaic cells. The photoelectrical conversion efficiency (PCE) of the device with a multilayer structure of ITO/PEDOT/ PCPDTBT:CdSe /LiF/Al reached a value as large as 1.34% with an open-circuit voltage (Voc) = 0.57 V, a short-circuit current density (Jsc) = 4.29 mA/cm2, and a fill factor (FF) = 0.27. This suggests a useful application in further fabrication of quantum dots/polymers based solar cells.Thi Thao TranQuang Trung TranVan Truong VoNang Dinh Nguyendinhnn@vnu.edu.vn2016-05-20T09:05:44Z2016-05-20T09:06:56Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1510This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/15102016-05-20T09:05:44ZNghiên cứu cố định protein BSA lên bề mặt polymer PDMS chức năng định hướng ứng dụng trong chế tạo cảm biến sinh họcThi Ngoc TranHong Nhung LuongThi Hien Lelehien@vnu.edu.vnThi Huyen Vu