Economic policy uncertainty and overinvestment: evidence from Korea

( Wenwen Jiang ),( Hwa-sung Kim ) 한국파생상품학회 2021 선물연구 Vol.29 No.4

The authors show that there is a negative relationship between economic policy uncertainty (EPU) and firm overinvestment using Korean data from2007 to 2016. Since Jensen (1986) shows that a firm’s free cash flow is an important factor of overinvestment, the authors examine how free cash flow influences the sensitivity of overinvestment to EPU. The authors find that a high level of free cash flow attenuates the negative effect of EPU on overinvestment. The authors find that there is no significant difference in the effect of EPU on overinvestment between Chaebol (Korean family-run conglomerates) and non-Chaebol firms, which is consistent with the literature that the features of Chaebol are weakening.

Secular Change in the Value of Cash: Evidence in Korea

Wenwen Jiang 충남대학교 경영경제연구소 2021 경영경제연구 Vol.43 No.4

본 논문에서는 한국 기업의 보유현금 가치의 시계열적 변동을 탐구한다. 미국 시장의 연구 결과와 일관되게, 한국 기업들의 보유현금 가치가 1990년부터 2019년까지 증가하는 추세를 보였다. 그 결과 현금 1달러의 평균 가치는 1990년대 0.678달러, 2000년대 1.199달러, 2010년대 1.440달러인 것으로 나타났다. 한편, 이러한 추세는 특별한 특징을 가진 기업군이나 IPO 효과에 의해 주도되는 것이 아니라 시장의 전반적인 현상임을 확인하였다. 2000년대의 보유현금 가치의 증가는 금융제약과 기업 수준의 불확실성에 대한 예비적 동기, 기업지배구조 및 투자자 심리에 의해 부분적으로 설명될 수 있다. 2010년대에는 기업 수준의 불확실성, 기업지배구조 및 투자자 심리만 부분적으로 설명할 수 있다. 미국 시장과 달리, 신규 상장기업과 투자 기회가 2000년대와 2010년대의 변화를 설명할 수 없음을 발견하였다. This paper studies the secular change in the value of cash in Korean firms. Consistent with the findings in the US market, we find that the cash value in Korean firms has been increasing from 1990 to 2019. The result shows that the average value of a dollar in cash is $0.678 in the 1990s, $1.199 in the 2000s, and $1.440 in the 2010s. The increase in cash value can be partially explained by precautious motivations for financial constraint and firm-level uncertainty, corporate governance, and investor sentiment in the 2000s. As for the 2010s, only firm-level uncertainty, corporate governance, and investor sentiment can partially explain. In contrast to the US market, we find that the new listed firms and investment opportunities cannot explain the change in both 2000s and 2010s.

Antiviral Effect of Retro-2.1 against Herpes Simplex Virus Type 2 In Vitro

( Wenwen Dai ),( Yu Wu ),( Jinpeng Bi ),( Jingyu Wang ),( Shuai Wang ),( Wei Kong ),( Julien Barbier ),( Jean-christophe Cintrat ),( Feng Gao ),( Zhengran Jiang ),( Daniel Gillet ),( Weiheng Su ),( Ch 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.6

Herpes simplex virus type 2 (HSV-2) infection has been a public health concern worldwide. It is the leading cause of genital herpes and a contributing factor to cervical cancer and human immunodeficiency virus (HIV) infection. No vaccine is available yet for the treatment of HSV-2 infection, and routinely used synthetic nucleoside analogs have led to the emergence of drug resistance. The small molecule Retro-2^cycl has been reported to be active against several pathogens by acting on intracellular vesicle transport, which also participates in the HSV-2 lifecycle. Here, we showed that Retro-2.1, which is an optimized, more potent derivative of Retro-2^cycl, could inhibit HSV-2 infection, with 50% inhibitory concentrations of 5.58 μM and 6.35 μM in cytopathic effect inhibition and plaque reduction assays, respectively. The cytotoxicity of Retro-2.1 was relatively low, with a 50% cytotoxicity concentration of 116.5 μM. We also preliminarily identified that Retro-2.1 exerted the antiviral effect against HSV-2 by a dual mechanism of action on virus entry and late stages of infection. Therefore, our study for the first time demonstrated Retro-2.1 as an effective antiviral agent against HSV-2 in vitro with targets distinct from those of nucleoside analogs.

The potential of therapeutic strategies targeting mitochondrial biogenesis for the treatment of insulin resistance and type 2 diabetes mellitus

Wenwen Ding,Xiaoxue Yang,Kaiyi Lai,Yu Jiang,Ying Liu 대한약학회 2024 Archives of Pharmacal Research Vol.47 No.3

Type 2 diabetes mellitus (T2DM) is a persistent metabolic disorder marked by defi ciencies in insulin secretion and/orfunction, aff ecting various tissues and organs and leading to numerous complications. Mitochondrial biogenesis, the processby which cells generate new mitochondria utilizing existing ones plays a crucial role in energy homeostasis, glucosemetabolism, and lipid handling. Recent evidence suggests that promoting mitochondrial biogenesis can alleviate insulinresistance in the liver, adipose tissue, and skeletal muscle while improving pancreatic β -cell function. Moreover, enhancedmitochondrial biogenesis has been shown to ameliorate T2DM symptoms and may contribute to therapeutic eff ects for thetreatment of diabetic nephropathy, cardiomyopathy, retinopathy, and neuropathy. This review summarizes the intricate connectionbetween mitochondrial biogenesis and T2DM, highlighting the potential of novel therapeutic strategies targetingmitochondrial biogenesis for T2DM treatment and its associated complications. It also discusses several natural productsthat exhibit benefi cial eff ects on T2DM by promoting mitochondrial biogenesis.

p53 overexpression represses androgen-mediated induction ofNKX3.1 in a prostate cancer cell line

Anli Jiang,Chunxiao Yu,Pengju Zhang,Weiwen Chen,Wenwen Liu,Xiaoyan Hu,Jianye Zhang 생화학분자생물학회 2006 Experimental and molecular medicine Vol.38 No.6

Prostate cancer is a disease involving complicated multiple-gene alterations. Both NKX3.1 and p53 are related to prostate cancer and play crucial roles in prostate cancer progression. However, little is known about the relationships and interactions between p53 and NKX3.1 in prostate cancer. We found that NKX3.1 expression is down-regulated by over-expression of wild type (wt) p53 in prostate cancer LNCaP cells. NKX3.1 is down-regulated at both the mRNA and protein levels by p53 overexpression due to either transient transfection of exogenous p53 or induction of endogenous p53. p53 over-expression represses androgen-induced transactivation of NKX3.1 by inhibiting the promoter of the androgen acceptor (AR) gene and by blocking AR-DNA binding activity. In addition, transfection with the p21 expression vector (pPSA-p21) showed that p21 does not reduce NKX3.1 expression, indicating that NKX3.1 expression is not the result of nonspecific effects of cell growth arrest. Our results provide biochemical and cellular biologic evidence that NKX3.1 is down-regulated by p53 over-ex - pression in prostate cancer cells.

Ultrasound-Guided Radiofrequency Ablation in Tertiary Hyperparathyroidism: A Prospective Study

Deng Erya,Jiang Tingting,Chai Huihui,Weng Ning,He Hongfeng,Zhang Zhengxian,Peng Chengzhong,Yue Wenwen,Xu Huixiong 대한영상의학회 2024 Korean Journal of Radiology Vol.25 No.3

Objective: To prospectively evaluate the outcomes of ultrasound (US)-guided radiofrequency ablation (RFA) in tertiary hyperparathyroidism (THPT). Materials and Methods: Patients with THPT underwent RFA between September 2017 and January 2022. Laboratory parameters, including serum intact parathyroid hormone (iPTH) levels, were monitored for 48 months after RFA and compared with the levels at baseline. Complications related to RFA and changes in hyperparathyroidism-related clinical symptoms were recorded before and after RFA. Results: A total of 42 patients with THPT were recruited for this study. Ultimately, 36 patients with renal failure and 2 patients who underwent successful renal transplantation (male:female, 17:21; median age, 54.5 years) were enrolled. The follow-up time was 21.5 ± 19.0 months in the 36 patients with renal failure. In these 36 patients, iPTH levels were significantly decreased to 261.1 pg/mL at 48 months compared with the baseline value of 1284.9 pg/mL (P = 0.012). Persistent hyperparathyroidism, defined as iPTH levels maintained at > 585.0 pg/mL for 6 months after treatment, occurred in 4.0% of patients (1/25). Recurrent hyperparathyroidism, defined as iPTH levels > 585.0 pg/mL after 6 months, were 4.0% (1/25) and 0.0% (0/9) at 6 months and 4 years after treatment, respectively. In two patients with THPT after successful renal transplantation, iPTH decreased from the baseline value of 242.5 and 115.9 pg/mL to 171.0 and 62.0 pg/mL at 6 months after treatment. All complications resolved within 6 months of ablation without medical intervention, except in 10.5% (4/38) patients with permanent hypocalcemia. The overall symptom recovery rate was 58.8% (10/17). The severity scores for bone pain, arthralgia, and itchy skin associated with hyperparathyroidism improved after treatment (P < 0.05). Conclusion: US-guided RFA is an effective and safe alternative to surgery in the treatment of patients with TPTH and improves hyperparathyroidism-related clinical symptoms.

The Review of New NDT Methods of Metal Material Fatigue Monitoring

Jingwei Dong,Qijian Wu,Wenwen Jiang,Qi Xu 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.8

Non-destructive testing (NDT) techniques have been employed in all kinds of fields successfully for many years. Newly developed and applied NDT methods of detecting and monitoring fatigue crack in metal material are reviewed in this paper. Some methods based on machine vision technique and image recognition techniques are introduced for at or near surface visible crack testing. As a newborn offspring of acoustic emission technique, electromagnetically induced acoustic emission methods also introduced for both visible and invisible fatigue cracks on metal structure. Nonlinear ultrasonic method and some other NDT methods presently available are mentioned, too. The principles, applied testing fields, data processing algorithms, advantages and disadvantages of these methods are discussed.

Non-thermal plasma coupled liquid-phase catalysis /Fe2+ for VOCs removal: Enhanced mechanism of protocatechuic acid

Caihong Qin,Rongrong Liu,Chaochao Jiang,Mengke Guo,Rui Yu,Jiayu Huang,Wenwen Bai,Xiaoqing Dang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-

Non-thermal plasma coupling Fe2+ containing liquid-phase catalysis (NTP-LC/ Fe2+) can effectively reusethe byproduct ozone (O3) of NTP in LC/ Fe2+ for volatile organic compounds (VOCs) degradation. However,the low recycling rate of Fe2+/Fe3+ resulted in poor catalytic effect of the coupling system. In this study,the chelator protocatechuic acid (PCA) was added to LC/Fe2+ to enhance the removal of representativeVOC acetone. The results showed that adding PCA increased the acetone removal efficiency to 91% andkept O3 100% removed within 180 min. The mechanism of PCA-enhanced acetone degradation was thatPCA accelerated the Fe3+/Fe2+ cycle by generating PCA-Fe3+ chelates, which prevented the Fe3+ from precipitationand promoted the production of OH and O2 - for acetone oxidation.

The Theoretical Calculations of Kinetic and Thermodynamics Parameters and Anharmonic Correction for the Related Reactions of NO₃

Yu, Hongjing,Liu, Yancheng,Xia, Wenwen,Wang, Li,Jiang, Meiyi,Hu, Wenye,Yao, Li Korean Chemical Society 2021 대한화학회지 Vol.65 No.6

According to the transition state (TS) theory, Gaussian software and Yao and Lin (YL) method, the thermodynamics and kinetic data respectively were calculated, and anharmonic effect was considered for related reactions of NO₃. The methods of calculating and fitting kinetic and thermodynamics parameters were provided by least square method and related equations in this paper. Notably, the fitted E of Arrhenius equation was close to the calculated barrier of related reaction by QCISD(T) method. Therefore, the kinetic fitting result can well express the physical meaning of E in Arrhenius equation. Besides, the conversion process and the reaction mechanism of NO₃ were researched. For NO₃, it seemed that its instability results from its easy reaction with other substances rather than the decompose reaction of itself.

AN ULTRA-LUMINOUS QUASAR AT <i>z</i> = 5.363 WITH A TEN BILLION SOLAR MASS BLACK HOLE AND A METAL-RICH DLA AT <i>z</i> ∼ 5

Wang, Feige,Wu, Xue-Bing,Fan, Xiaohui,Yang, Jinyi,Cai, Zheng,Yi, Weimin,Zuo, Wenwen,Wang, Ran,McGreer, Ian D.,Ho, Luis C.,Kim, Minjin,Yang, Qian,Bian, Fuyan,Jiang, Linhua IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.807 No.1

<P>We report the discovery of an ultra-luminous quasar J030642.51+185315.8 (hereafter J0306+1853) at redshift 5.363, which hosts a supermassive black hole with M-BH = (1.07 +/- 0.27) x 10(10) M-circle dot. With an absolute magnitude M-1450 = -28.92 and a bolometric luminosity L-bol similar to 3.4 x 10(14) L-circle dot, J0306+1853 is one of the most luminous objects in the early universe. It is not likely to be a beamed source based on its small flux variability, low radio loudness, and normal broad emission lines. In addition, a z = 4.986 damped Ly alpha system (DLA) with [M/H] = -1.3 +/- 0.1, among the most metal-rich DLAs at z greater than or similar to 5, is detected in the absorption spectrum of this quasar. This ultra-luminous quasar puts strong constraints on the bright end of the quasar luminosity function and massive end of the black hole mass function. It will provide a unique laboratory for the study of BH growth and the co-evolution between a BH and the host galaxy with multi-wavelength follow-up observations. The future high-resolution spectra will give more insight into the DLA and other absorption systems along the line of sight of J0306+1853.</P>