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Achieving tolerant CO<sub>2</sub> electro-reduction catalyst in real water matrix
Won, Da Hye,Shin, Hyeyoung,Chung, Min Wook,Jung, Hyejin,Chae, Keun Hwa,Oh, Hyung-Suk,Hwang, Yun Jeong,Min, Byoung Koun Elsevier 2019 Applied Catalysis B Vol.258 No.-
<P><B>Abstract</B></P> <P>In order to achieve practical application of electrochemical CO<SUB>2</SUB> conversion technologies, the development of durable catalyst in real water matrix is essential because the use of catalysts only showing high performance within a well-refined environment cannot guarantee their feasibility in realistic conditions. Here, we report a design strategy for a catalyst, which shows excellent tolerance to deactivation factors, using a carbon-based material under more practical condition implemented by real tap water. Screening analyses on various components in tap water elucidated that the impurity group, which can be deposited on the catalyst surface and impede the active sites, such as copper, zinc, and especially iron are the main factors responsible for deactivation. Based on these findings, the structural modified nitrogen-doped carbon nanotube (denoted as ball mill N-CNT) was adopted as a catalyst design to secure durability. Consequently, the ball mill N-CNT revealed tolerance to the disclosed deactivation factors and showed stable performance during unprecedented long-time of 120 h in tap water media.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electro-reduction of CO<SUB>2</SUB> was performed in real water matrix (tap water) conditions. </LI> <LI> Iron was found to be the most detrimental element in silver catalyzed CO<SUB>2</SUB> electro-reduction. </LI> <LI> Nitrogen doped carbon based material was designed to be a stable model catalyst in real water. </LI> <LI> Stable performance was tested for an unprecedented long-time of 120 h in tap water media. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Effect of Ion-Pair Formation with Bile Salts on the In Vitro Cellular Transport of Berberine
Hye-Won Chae,김인화,진효언,김대덕,정석재,심창구 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.1
The objective of this study was to examine the effect of ion-pair complexation with endogenous bile salts on the transport of a quarternary ammonium organic cationic (OC) drug, berberine, across the Caco-2 and LLC-PK1 cell monolayers. The basolateral-to-apical (BL-AP) transport of berberine in Caco-2 cells was temperature dependent and 10-fold higher than that of the apical-to-basolateral (AP-BL) transport. Similar results were observed for the transport of berberine across the LLC-PK1 cells. Moreover, the BL-AP transport in the Caco-2 cells was significantly reduced by the cis-presence of P-glycoprotein (P-gp) inhibitors such as cyclosporine A, verapamil, and digoxin. These results suggest that an efflux transporter, probably P-gp, is involved in the Caco-2 cell transport. The Km and Vmax values for the carrier-mediated transport were estimated to be 83.4 mM and 7640 pmole/h/cm2, respectively. The apparent partition coefficient (APC) of berberine between n-octanol and a phosphate buffer (pH 7.4) was increased by the presence of an organic anion (OA), taurodeoxycholate (TDC, a bile salt), suggesting the formation of a lipophilic ion-pair complex between an OC (berberine) and an OA (TDC). Despite the ion-pair complexation, however, the BL-AP transport of berberine across the Caco-2 and LLC-PK1 cells was not altered by the cis-presence of bile salts or the rat bile juice. This is consistent with the reportedly unaltered secretory transport of a quarternary ammonium compound, tributylmethylammonium (TBuMA), across the Caco-2 cell monolayers in the cis-presence of bile salts or the rat bile juice, but not with our previous report in which the secretory transport of TBuMA across the LLC-PK1 cell was increased in the cis-presence of TDC. Therefore, the effect of ion-pair formation with the bile components or bile salts on the secretory transport of OCs appears to depend on the molecular properties of OCs (e.g., molecular weight, lipophilicity and affinity to relevant transporters) and the characteristics of cell strains (e.g., expression and contribution of responsible transporters to the transport).
( Hye Sung Won ),( Lee So Maeng ),( Hiun Suk Chae ),( Hyung Keun Kim ),( Young Suk Cho ),( Jin Hyoung Kang ),( Hong Seok Jang ),( Mi Ryeong Ryu ) 대한소화기학회 2012 Gut and Liver Vol.6 No.2
Background/Aims: The purpose of this study was to investigate the malignant potential of aberrant crypt foci (ACF) by measuring the multiplicity of crypts and lectin expression in the early and late stages of 1,2-dimethylhydrazine (DMH)- induced colon carcinogenesis. Methods: Six-week-old Wistar rats were injected subcutaneously with DMH for 27 weeks. We classified ACF according to the number of crypts per ACF as a few crypts (≤3 crypts, FC ACF) or numerous crypts (≥4 crypts, NC ACF). Immunohistochemistry was used to evaluate lectin expression. Results: In the early stage, FC ACF (590/1,902, 31.0%) occurred more frequently than NC ACF (35/449, 7.8%); whereas in the late stage, NC ACF (176/449, 39.2%) occurred more frequently than FC ACF (324/1,902, 17.0%). The number of ACF peaked at 15 to 20 weeks. The ratio of NC/FC ACF increased gradually during carcinogenesis. The expression of both UEA1 and PNA was higher in NC ACF than FC ACF. Lectin expression increased in the late stage compared with the early stage. Conclusions: The expression of lectin was higher in NC ACF and ACF in the late stage. Therefore, ACF with higher multiplicities in the late stage may have more malignant potential in DMH-induced colon carcinogenesis. (Gut Liver 2012;6:229-234)
Chae, Sun Young,Jang, Jun Ho,Im, Geun Ho,Jeong, Ji-Hyun,Jung, Won-Beom,Ko, Sukjin,Jie, Hyesoo,Kim, Ji Hye,Chang, Yun Sil,Chung, Seungsoo,Kim, Ki-Soo,Lee, Jung Hee Elsevier 2019 NeuroImage Vol.188 No.-
<P><B>Abstract</B></P> <P>Neuroplasticity is considered essential for recovery from brain injury in developing brains. Recent studies indicate that it is especially effective during early postnatal development and during the critical period. The current study used functional magnetic resonance imaging (fMRI) and local field potential (LFP) electrophysiological recordings in rats that experienced neonatal hypoxic-ischemic (HI) injury during the critical period to demonstrate that physical exercise (PE) can improve cortical plasticity even when performed during adulthood, after the critical period. We investigated to what extent the blood oxygen level-dependent (BOLD)-fMRI responses were increased in the contralesional spared cortex, and how these increases were related to the LFP electrophysiological measurements and the functional outcome. The balance of excitation and inhibition was assessed by measuring excitatory and inhibitory postsynaptic currents in stellate cells in the primary somatosensory (S1) cortex, which was compared with the BOLD-fMRI responses in the contralesional S1 cortex. The ratio of inhibitory postsynaptic current (IPSC) to excitatory postsynaptic current (EPSC) at the thalamocortical (TC) input to the spared S1 cortex was significantly increased by PE, which is consistent with the increased BOLD-fMRI responses and improved functional outcome. Our data clearly demonstrate in an experimental rat model of HI injury during the critical period that PE in adulthood enhances neuroplasticity and suggest that enhanced feed-forward inhibition at the TC input to the S1 cortex might underlie the PE-induced amelioration of the somatosensory deficits caused by the HI injury. In summary, the results of the current study indicate that PE, even if performed beyond the critical period or during adulthood, can be an effective therapy to treat neonatal brain injuries, providing a potential mechanism for the development of a potent rehabilitation strategy to alleviate HI-induced neurological impairments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Physical exercise (PE) enhances cortical plasticity in hypoxic-ischemic (HI) injury. </LI> <LI> Cortical plasticity can be monitored by fMRI and electrophysiological recordings. </LI> <LI> Enhanced feed-forward inhibition improves the somatosensory deficits in HI injury. </LI> <LI> PE can be a therapeutic method for brain injuries in newborns and infants. </LI> </UL> </P>
Error Correction for Korean Speech Recognition using a LSTM-based Sequence-to-Sequence Model
Hye-won Jin(진혜원),A-Hyeon Lee(이아현),Ye-Jin Chae(채예진),Su-Hyun Park(박수현),Yu-Jin Kang(강유진),Soowon Lee(이수원) 한국컴퓨터정보학회 2021 韓國컴퓨터情報學會論文誌 Vol.26 No.10
현재 대부분의 음성인식 오류 교정에 관한 연구는 영어를 기준으로 연구되어 한국어 음성인식에 대한 연구는 미비한 실정이다. 하지만 영어 음성인식에 비해 한국어 음성인식은 한국어의 언어적인 특성으로 인해 된소리, 연음 등의 발음이 있어, 비교적 많은 오류를 보이므로 한국어 음성인식에 대한 연구가 필요하다. 또한, 기존의 한국어 음성인식 연구는 주로 편집 거리 알고리즘과 음절 복원 규칙을 사용하기 때문에, 된소리와 연음의 오류 유형을 교정하기 어렵다. 본 연구에서는 된소리, 연음 등 발음으로 인한 한국어 음성인식 오류를 교정하기 위하여 LSTM을 기반으로 한 인공 신경망 모델 Sequence-to-Sequence와 Bahdanau Attention을 결합하는 문맥 기반 음성인식 후처리 모델을 제안한다. 실험 결과, 해당 모델을 사용함으로써 음성인식 성능은 된소리의 경우 64%에서 77%, 연음의 경우 74%에서 90%, 평균 69%에서 84%로 인식률이 향상되었다. 이를 바탕으로 음성인식을 기반으로 한 실제 응용프로그램에도 본 연구에서 제안한 모델을 적용할 수 있다고 사료된다. Recently, since most of the research on correcting speech recognition errors is based on English, there is not enough research on Korean speech recognition. Compared to English speech recognition, however, Korean speech recognition has many errors due to the linguistic characteristics of Korean language, such as Korean Fortis and Korean Liaison, thus research on Korean speech recognition is needed. Furthermore, earlier works primarily focused on editorial distance algorithms and syllable restoration rules, making it difficult to correct the error types of Korean Fortis and Korean Liaison. In this paper, we propose a context-sensitive post-processing model of speech recognition using a LSTM-based sequence-to-sequence model and Bahdanau attention mechanism to correct Korean speech recognition errors caused by the pronunciation. Experiments showed that by using the model, the speech recognition performance was improved from 64% to 77% for Fortis, 74% to 90% for Liaison, and from 69% to 84% for average recognition than before. Based on the results, it seems possible to apply the proposed model to real-world applications based on speech recognition.
Efficient Production of Fatty Acids and Fuels by Metabolically Engineered Rhodococcus opacus Strains
Hye Mi KIM,Tong Un CHAE,So Young CHOI,Won Jun KIM,Sang Yup LEE 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Microbial production of free fatty acids (FFAs) and derivatives is of great interest. We report the development of engineered Rhodococcus opacus strains producing FFAs, fatty acid ethyl esters (FAEEs) and long-chain hydrocarbons (LCHCs). An engineered strain with acyl-CoA synthetases deleted, overexpressing three lipases produces 50.2 g/L of FFAs. Another engineered strain with acyl-CoA dehydrogenases deleted, overexpressing lipases, foldase, acyl-CoA synthetase, and heterologous aldehyde/alcohol dehydrogenase and wax ester synthase produces 21.3 g/L of FAEEs. A third engineered strain with acyl-CoA dehydrogenases and alkane-1 mono-oxygenase deleted, overexpressing lipases, foldase, acyl-CoA synthetase, and heterologous acyl-CoA reductase, acyl-ACP reductase and aldehyde deformylating oxygenase produces 5.2 g/L of LCHCs. Engineered strains developed here will help establish oleaginous biorefinery platform.