Test Study on the Air Permeability of Remolded Q3 Malan Loess

Jia Liu,Xi’an Li,Zeze Guo,Quan Xue,Li Wang,Jinyang Liu 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.8

Gas permeability is an important parameter in the determination of the pore structure characteristics of loess, especially in engineering fields such as earthwork and landfill cover treatment. With an improved ZC-2015 air permeameter, the air permeability (ka) testing under different water contents (w), dry densities (ρd) and wetting paths was conducted on remolded Q3 Malan loess from the Chanhe River area in Xi’an, Shaanxi, China. The results indicate that the ka of the remolded loess decreased rapidly as ρd increased and exhibited a relatively complex pattern as w increased. When w was less than the plastic limit (wp) and ρdwas relatively low (1.35 g·cm−3, 1.45 g·cm−3), ka decreased as we increased. When ρd reached a certain value (1.50 g·cm−3, 1.65 g·cm−3), the ka–we curve exhibited a notable turning point. When ρd continued to increase 1.70 g·cm−3, ka decreased as we increased. The results of microscopic analysis, suggested that under the action of different water content and compaction, levels of aggregates and pore structures were formed. A Poulsen model was used to predict the ka and the test results were in relatively coincident with the calculation results, demonstrating that the Poulsen model is applicable.

소 뇌 조직으로부터 5'-Nucleotidase의 정제 및 특성규명

류희문,석대은 충남대학교 약학대학 의약품개발연구소 2002 藥學論文集 Vol.17 No.-

5'-Nucleotidase, bound to brain membranes as a glycosylphosphatidyl-inositol (GPI)-anchored protein, is responsible for the conversion of adenosine-5'-monophosphate into adenosine, which is an agonist in adenosine receptor signalling. Here, 5'-nucleotidase was isolated from bovine brain using PI-PLC treatment, and purified by concanavalin A sepharose chromatography, DEAE-sephacel chromatography, and finally AMP affinity chromatography. For higher yield of enzyme purification, Zn^2+ was Included in the elution buffer in DEAE-sephacel chromatography. Especially, NaCl was more favorable than MgCl_2 for the elution of 5'-nucleotidase, proper for inactivation study, from AMP affinity column. The purified 5'-nucleotidase was relatively pure on SDS-PAGE analysis, showing a specific activity of 30.27 μmole/min/㎎ (purification fold 19,000 fold). The purified enzyme, possessing a K_m value of 44μM and an optimum pH of 7.5, was inhibited competitively by ATP (K_i, 12 μM), and uncompetitively by cysteine (K_i, 0.32 mM). In addition, the enzyme was activated slighty (1.5-folds) by Mg^2+.

효소 Lipoxygenase의 신규기질 : Acylglycerol, acylethanolamide, lysophospholipids 및 phospholipids

황룡쌍,류희문,박천호,석대은 충남대학교 약학대학 의약품개발연구소 2007 藥學論文集 Vol.22 No.-

Lipoxygenase belongs to a diverse family of nonheme ferroproteins that oxygenate polyenoic fatty acids containing 1,4-pentadiene structure to form their corresponding hydroperoxy derivatives. Lipoxygenases (LOXs), widely distributed in animals and plants, have a key function in the formation of biologically active substances from pulyunsaturated fatty acids. Generally, free polyunsaturated fatty acids, liberated from membrane phospholipids via phospholipase-catalyzed hydrolysis, are used as substrates for LOXs. Although it is acknowledged that free polyunsaturated fatty acids are preferred to phospholipids or triglycerides as substrates, there have been recent reports that mammalian enzymes can oxidize certain phospholipids. Especially, reticulocyte LOX (15-LOX) leukocyte 15-LOX, leukocyte LOX (12-LOX) can oxygenate complex substrates such as phospholipids and biomembranes. In addition, acylglycerol and acylethanolamide are utilized by lipoxygeanse as well as cycoloxygenase; the latter enzyme contributes to generation of bioactive prostanoids derivative. Furthermore, lysophosphatidylcholine or lysophosphatidic acid containing linoleoyl or arachidonoyl moieties are known to be oxygenated by reticulocyte LOX, leukocyte 15-LOX or leukocyte-type 12-LOX; oxygenated lysophospholipids can play a carrier role in transporting oxygenated derivatives. Thus, the use of various lipid substrates as new substrates for lipoxygenase may extend the physiological roles of those lipids containing unsaturated fatty acyl chains.

Cumene hydroperoxide에 의한 paraoxonase 1의 산화적 불활성화에 대한 보호 방안

스, 위엥쥐,류희문,김주령,석대은 충남대학교 약학대학 의약품개발연구소 2003 藥學論文集 Vol.18 No.-

Paraoxonase 1 (PON1), an enzyme associated with high density lipoprotein (HDL), is known to protect low density lipoprotein (LDL) from lipid peroxidation involving copper ion. However, Paraoxonase 1 activity was observed to decrease during LDL oxidation. Here, the inactivation of PON1 by various peroxides was examined. Paraoxonase 1, purified from human plasma, was subjected to cumene hydroperoxide, hydrogen peroxide or tert-butyl hydroperoxide. PON activity, based on the hydrolysis of phenyl acetate, decreased by approximately 40 and 38 %, respectively, after the exposure to 2mM cumene hydroperoxide and hydrogen peroxide, while tert-butyl hydroperoxide had no remarkable inhibitory effect. Next, the compounds capable of preventing against cumene hydroperoxide-induced inactivation of PONl were screened. While quercetin or phenyl acetate failed to protect PON1, lauric acid or calcium chloride was found to protect PONl from cumene hydroperoxide-induced inactivation. Especially, lauric acid appeared to show the greater protection than the other fatty acids tested. In further study, lauric acid showed a dose-dependent protection with an E& value of around 35 μM. Based on these results, It is proposed that the alky hydroperoxide-induced inactivation of Paraoxonase 1 can be prevented by a proper fatty acid recipe.

인체 혈장 Paraoxonase의 산화적 불활성화

위엥쥐스,김주령,정태숙,류희문,석대은 충남대학교 약학대학 의약품개발연구소 2002 藥學論文集 Vol.17 No.-

Paraoxonase (PON), an enzyme associated with high density lipoprotein (HDL), is known to protect low density lipoprotein (LDL) from lipid peroxidation involving copper ion. However, PON activity was observed to decrease during LDL oxidation. Here, we attempted to elucidate the possible mechanism for the inactivation of PON. PON was partially purified from human plasma, and subjected to various oxidant systems. PON activity, based on the hydrolysis of phenyl acetate, decreased slightly after the exposure to H_2O_2 or ascorbate, while oxidants such as peroxynitrite or HOCl had no remarkable effect. Inclusion of Cu^2+ in the incubation with ascorbate (0.3∼1 mM) led to a rapid decrease of activity in a time-and concentration-dependent manner. In comparison, ascorbate/Cu^2+ system was much more effective than ascorbate/Fe^2+ system in inactivating PON. A further study indicates that general hydroxyl radical scavengers such as mannitol, ethanol or benzoate failed to prevent the PON inactivation. Based on these results, it is proposed that the PON inactivation during LDL oxidation may be ascribed mainly to the Cu^2+-catalyzed oxidation.

Genetic dissection of leaf-related traits using 156 chromosomal segment substitution lines

Xi Liu,Linglong Liu,Yinhui Xiao,Shijia Liu,Yunlu Tian,Liangming Chen,Zhiquan Wang,Ling Jiang,Zhigang Zhao,Jianmin Wan 한국식물학회 2015 Journal of Plant Biology Vol.58 No.6

A two-line super-hybrid rice (Oryza sativa L.) variety [Liangyoupei9 (LYP9)] demonstrated superiority over its both parents, viz. elite inbred lines 93-11 and Pei-ai64S (PA64S), as well as other conventional hybrids, and had long been exploited in China. However, the genetic basis of its leaf-related traits, supposed to be an important component for yield potential, remains elusive. Here, initially a set of chromosome segment substitution lines (CSSLs) was constructed, in which the genome of Pei-ai64S has been introgressed into the background of 93-11. This set was developed by marker aided selection, based on 123 polymorphic SSR markers. The introgressed chromosomal segments presented in the 156 CSSLs covered 96.46% of Pei-ai64S genome. Afterwards, the CSSLs were deployed to assess the genetic basis of leaf size (length and width) and chlorophyll content of top three leaves across five different environments. The CSSLs showed transgressive segregation for all of the traits, and significant correlations were detected among most of the traits. A total of 27 quantitative trait loci (QTL) were identified on ten chromosomes, and three QTL cluster affecting related traits were found on chromosome 3, 6, and 8, respectively. Remarkably, two key QTLs, qALW3-1 and qALW3-2, both controlling the antepenultimate leaf width, were identified in all five environments, and their effect were further validated by CSSLs harboring the two QTL alleles. Our results indicate that developing CSSLs is a powerful tool for genetic dissection of quantitative traits. Meanwhile, the QTLs controlling leaf-related traits uncovered here provide useful information for marker-assisted selection in improving the performance of leaf morphology and photosynthetic ability.

Role of Protein Disulfide Isomerase in Molecular Fate of Thyroglobulin and its Regulation by Endogenous Oxidants and Reductants

Liu, Xi-Wen,Sok, Dai-Eun The Pharmaceutical Society of Korea 2002 Archives of Pharmacal Research Vol.25 No.4

The molecular fate of thyroglobulin (Tg) is controlled by oligomerization, a means of storing Tg at high concentrations, and deoligomerization. The oligomerization of bovine Tg are intermolecular reactions that occur through oxidative processes, such as disulfide and dityrosine formation, as well as isopeptide formation; disulfide formation is primarily responsible for Tg oligomerization. Here, the protein disulfide isomerase (PDI) and/or peroxidase-induced oligomerization of unfolded thyroglobulins, which were prepared by treating bovine Tg with heat, urea or thiol/urea, was investigated using SDS-PAGE analyses. In addition, the enzymatic oligomerization was compared with non-enzymatic oligomerization. The thermally-induced oilgomerization of Tg, dependent on glutathione redox state, was affected by the ionic strength or the presence of a surfactant. Meanwhile, PDI-catalyzed oligomerization, time and pH-dependent, was the most remarkable with unfolded/reduced Tg, which was prepared from a treatment with urea/DTT, while the thermally-unfolded Tg was less sensitive. Similarly, the oligomerization of unfolded/reduced Tg was also mediated by peroxidase. However, PDI showed no remarkable effect on the peroxidase-mediated oligomerization of either the unfolded or unfolded/reduced Tg. Additionally, the reductive deoligomerization of oligomeric Tg was exerted by PDI in an excessively reducing state. Based on these results, it is proposed that PDI catalyzes the oligomerization of Tg through the disulfide linkage and its deoligomerization in the molecular fate, and this process may require a specific molecular form of Tg, optimally unfolded/reduced, in a proper redox state.

A Task Scheduling Based on Simulated Annealing Algorithm in Cloud Computing

Xi Liu,Jun Liu 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.6

Because the task scheduling problem is np-complete problem, it is hard to find a deterministic algorithm to solve the problem of task scheduling in the cloud computing platform. Therefore this paper presents a task scheduling mechanism based on simulated annealing algorithm. The algorithm is a modern heuristic algorithm and overcome the shortcoming of the local optimum search method. The algorithm uses a greedy algorithm to generate the initial value, and heat to a sufficiently high temperature and according to certain rules to generate a new value. If the new value is better than the original value or at a certain probability can be accepted, then replace the original value with the new value until cool. Experiments proved the feasibility and effectiveness of the algorithm. Compared with traditional algorithms, this task scheduling mechanism not only meets the needs of users and improves the performance of the system.

Ground-based Measurements of the Aerosol Optical Thickness at Xiamen Sea and Satellite Remote SensingTest

Xi Liu,Xiu-qing Hu 한국기상학회 2011 한국기상학회 학술대회 논문집 Vol.2011 No.10-2

Effect of Self-Regulatory Focus on Purchase Intentions of Foreign-owned Perceived Local Brands

Xi LIU 한국유통과학회 2023 The Journal of Industrial Distribution & Business( Vol.14 No.4

Purpose: This paper aims to investigate how self-regulatory focus (SRF) influences the relationship between perceived brand localness (PBL) and purchase intentions (PI). This research adopted both domestic and foreign-owned brands to examine the moderating effect of self-regulatory orientations and product types respectively to exclude the interference of brand origin. Research design, data, and methodology: This study surveyed Chinese consumers and collected data using social media applications. ANOVA analysis and PROCESS modeling were adopted to complete the empirical analysis. Results: This research demonstrates that brand origin does not inhibit the positive impact of PBL on purchase intentions regardless of whether it originates from mainland China or not. Study 1 proved that the effect of PBL on PI is more convincing among consumers with promotion focus orientations. In study 2, higher purchase intentions were found for hedonic perceived local brands among promotion-focused consumers while significant preferences were found for utilitarian perceived local brands among prevention-focused consumers. Conclusions: This research complements the literature about the potential psychological factors influencing PBL and contributes to marketers in developing effective marketing strategies and appropriate positioning decisions. Overall, this study has important theoretical and managerial contributions to international marketing, particularly in the context of the current recession.