Molecular and Clinicopathological Features of Gastrointestinal Stromal Tumors in Vietnamese Patients

Quoc Dat Ngo,Quoc Thang Pham,Dang Anh Thu Phan,Anh Vu Hoang,Thi Ngoc Ha Hua,Sao Trung Nguyen 대한병리학회 2019 Journal of Pathology and Translational Medicine Vol.53 No.6

Background: Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal neoplasms of the gastrointestinal tract. Management of GIST patients is currently based on clinicopathological features and associated genetic changes. However, the detailed characteristics and molecular genetic features of GISTs have not yet been described in the Vietnamese population. Methods: We first identified 155 patients with primary GIST who underwent surgery with primary curative intent between 2011 and 2014 at University Medical Center at Ho Chi Minh City, Vietnam. We evaluated the clinicopathological features and immunohistochemical reactivity to p53 and Ki-67 in these patients. Additionally, KIT genotyping was performed in 100 cases. Results: The largest proportion of GISTs was classified as high-risk (43.2%). Of the 155 GISTs, 52 (33.5%) were positive for Ki-67, and 58 (37.4%) were positive for p53. The expression of Ki-67 and p53 were correlated with mitotic rate, tumor size, risk assessment, and tumor stage. Out of 100 GIST cases, KIT mutation was found in 68%, of which 62 (91.2%) were found in exon 11, two (2.9%) in exon 9, and four (5.8%) in exon 17. No mutation in exon 13 was identified. Additionally, KIT mutations did not correlate with any clinicopathological features. Conclusions: The expression of Ki-67 and p53 were associated with high-risk tumors. Mutations in exon 11 were the most commonly found, followed by exon 17 and exon 9. Additionally, KIT mutation status was not correlated with any recognized clinicopathological features.

Reductive transformation of hexavalent chromium by ferrous ions in a frozen environment: Mechanism, kinetics, and environmental implications

Nguyen, Quoc Anh,Kim, Bomi,Chung, Hyun Young,Kim, Kitae 극지연구소 2022 극지연구소 초록집 Vol.- No.-

Enhanced reduction of hexavalent chromium by hydrogen sulfide in frozen solution

Nguyen, Quoc Anh,Kim, Bomi,Chung, Hyun Young,Kim, Kitae 극지연구소 2021 극지연구소 초록집 Vol.- No.-

Performance of Channel Estimation in Two-Dimensional Modulation System

Quoc Kien Nguyen,전태현 한국인터넷방송통신학회 2020 Journal of Advanced Smart Convergence Vol.9 No.3

Orthogonal time frequency space (OTFS) modulation is considered as one of the solutions to cope with high mobility channel environments. It converts the time-varying channel to the near-constant channel response in the delay-Doppler domain. This modulation scheme also benefits from the diversity in two-dimensional modulation. According to recent researches, this method outperforms the conventional OFDM modulation, especially in high-speed channel conditions. In this paper, to investigate the performance of OTFS in a practical system, channel estimation in the delay-Doppler domain is compared with the conventional method in the time-frequency domain at different mobile speeds. Simulation results confirm that the delay-Doppler domain channel estimation brings a better performance compared to the conventional one under the same overhead rate.

Performance of Iterative Equalizer for ISI channel

Quoc Kien Nguyen,전태현 한국인터넷방송통신학회 2020 Journal of Advanced Smart Convergence Vol.9 No.3

Iterative decision feedback equalizer (IDFE) is a recursive equalization technique that can help to achieve an additional performance gain for the system by combining iterative channel decoding and interference cancellation. In a single carrier-based system, the intersymbol interference (ISI) is a critical problem that must be resolved since it causes frequency selective fading. Based on the idea of sharing the estimated information in the process of iteration, IDFE is considered as an efficient solution to improve the robustness of the system performance on the ISI channel. In this paper, the IDFE is applied on single carrier FDMA (SC-FDMA) system to evaluate the performance under ISI channel. The simulation results illustrate that IDFE helps to improve the performance of the SC-FDMA system, especially with long delay spread channels.

Performance of Channel Estimation in Two-Dimensional Modulation System

Nguyen, Quoc Kien,Jeon, Taehyun The Institute of Internet 2020 International journal of advanced smart convergenc Vol.9 No.3

Orthogonal time frequency space (OTFS) modulation is considered as one of the solutions to cope with high mobility channel environments. It converts the time-varying channel to the near-constant channel response in the delay-Doppler domain. This modulation scheme also benefits from the diversity in two-dimensional modulation. According to recent researches, this method outperforms the conventional OFDM modulation, especially in high-speed channel conditions. In this paper, to investigate the performance of OTFS in a practical system, channel estimation in the delay-Doppler domain is compared with the conventional method in the time-frequency domain at different mobile speeds. Simulation results confirm that the delay-Doppler domain channel estimation brings a better performance compared to the conventional one under the same overhead rate.

Burned Area Detection After Wildfire Using Landsat 7 ETM+ SLC-off Images

Quoc, Khanh Le,Sy, Tan Nguyen,Nhat, Thanh Nguyen Thi,Thanh, Ha Le The Institute of Electronics and Information Engin 2013 IEIE Transactions on Smart Processing & Computing Vol.2 No.3

The increasing demand for monitoring wildfires and their impact on the land surface have prompted studies of burned area extraction and analysis. To differentiate burned and unburned area, the earlier method of the Moderate Resolution Imaging Spectro-radiometer (MODIS) Burned Area Detection Algorithm was proposed to estimate the change in land surface based on the reflectance energy. The energy, whose wavelengths are sensitive to burning, was selected to calculate the change parameter $Z_{score}$. This method was applied using the MODIS images to produce a MODIS Burned Area product. The approach was to simplify this algorithm to make it compatible with the Landsat 7 ETM+ SLC-off images. To extract the refined version of burned regions, post-processing was carried out by applying a median filter, dilation morphology algorithm, and finally a gap filling method. The experimental results showed that the detailed burned areas extracted from the proposed method exhibited more spatial details than those of the MODIS Burned products in the large U.S areas. The results also revealed the discontinuous distribution of burned regions in Vietnam forests.

3D hierarchical structure of MoS₂@G-CNT combined with post-film annealing for enhanced lithium-ion storage

Nguyen, Quoc Hai,Choi, Jin Seok,Lee, Young-Chul,Kim, Il Tae,Hur, Jaehyun THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2019 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.69 No.-

<P><B>Abstract</B></P> <P>We present a three-dimensional hierarchical structure of a ternary nanocomposite consisting of MoS<SUB>2</SUB>, graphite, and carbon nanotubes, as a new anode material for lithium-ion batteries. The 3D structure (3D MoS<SUB>2</SUB>@G-CNT), prepared by a simple and scalable high-energy ball milling process, contains 2D heterogeneous clusters between MoS<SUB>2</SUB> and graphite, which are effectively interconnected by 1D carbon nanotubes. During the formation of 2D heterogeneous clusters, the surface area of MoS<SUB>2</SUB> is significantly increased due to exfoliation driven by the solid lubrication effect from mechanical milling. The morphology and structural properties of 3D MoS<SUB>2</SUB>@G-CNT are analyzed by various techniques including XRD, Raman, SEM, TEM, and BET. At the optimal ratio of ingredients, 3D MoS<SUB>2</SUB>@G-CNT shows excellent electrochemical performance in terms of specific capacity, long-term cycle life, and rate capability. Specifically, at the best experimental conditions, 3D MoS<SUB>2</SUB>@G-CNT delivers ∼1600mAhg<SUP>−1</SUP> at 0.2Ag<SUP>−1</SUP> after 100 cycles and ∼1200mAhg<SUP>−1</SUP> at 0.5Ag<SUP>−1</SUP> after 450 cycles. To achieve these, we also introduce a post-film annealing step which induced rearrangement of the binder, thus improving the adhesion between the electrode material and current collector. Enhanced charge transport and mechanical integrity after this treatment are confirmed by FTIR, ex-situ SEM, and photographs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 3D hierarchical MoS<SUB>2</SUB>@graphite-CNT was prepared by a high energy ball milling. </LI> <LI> Solid lubrication-induced exfoliation of MoS<SUB>2</SUB> and graphite was investigated. </LI> <LI> Excellent cycle life and rate capability of MoS<SUB>2</SUB>@graphite-CNT was demonstrated. </LI> <LI> Post-film annealing that can enhance the performances was further studied. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A three-dimensional hierarchical structure of a ternary nanocomposite consisting of MoS<SUB>2</SUB>, graphite, and carbon nanotubes (CNTs) is prepared by a simple and scalable high-energy ball milling process, as a high performance anode material for lithium-ion batteries.</P> <P>[DISPLAY OMISSION]</P>

Robust Precoding and Postcoding for Multicell Multiuser Transmission using Imperfect CSI

Nguyen-Le, Hung,Nguyen-Duy-Nhat, Vien,Tang-Tan, Chien,Bao, Vo Nguyen Quoc The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.5

This paper studies the problem of precoding and post-coding design for multicell multiuser downlink transmissions in the absence of perfect channel state information (CSI). Using statistical information of imperfect CSI, an iterative multiuser multicell transceiver design is formulated by minimizing the mean squared error (MSE) cost function of signal and leakage interference under per-base station power constraint (PBPC). The convergence of the iterative precoding and postcoding algorithm is verified by analytical and empirical results. The proposed precoding and postcoding algorithm offers a low computational complexity and robustness against CSI imperfection.

Signal Energy-based Cyclostationary Spectrum Sensing for Wireless Sensor Networks

Quoc Kien Nguyen,전태현 사단법인 한국위성정보통신학회 2016 한국위성정보통신학회논문지 Vol.11 No.3

Feature detection is recognized as an accurate spectrum sensing approach when the information of the desired signal is partly known at the receiver. This type of detection was proposed to overcome large noise environment. Cyclostationary detection is an example of feature detection in spectrum sensing technique in cognitive radio. However, the cyclostationary process calculation requires a lot of processing time and information about the designed signals. On the other hand, energy detection spectrum sensing is widely known as a simple and compact spectrum sensing technique. However, energy detection is highly affected by large noise and lead to high detection error probability. In this paper, the combination of energy detection and cyclostationary is proposed in order to increase the accuracy and decrease the calculation and processing time. The two-layer threshold is utilized in order to reduce the complexity of computation and processing time in cyclostationary which can lead to the improved throughput of the system. The simulation result shows that the implementation of energy-based cyclostationary detector can help to improve the performance of the system while it can considerably reduce the required time for signal detection.