Bathyal records of enhanced silicate erosion and weathering on the exposed Luzon shelf during glacial lowstands and their significance for atmospheric CO₂ sink

Xu, Zhaokai,Li, Tiegang,Clift, Peter D.,Wan, Shiming,Qiu, Xiaohua,Lim, Dhongil Elsevier 2018 Chemical geology Vol.476 No.-

<P><B>Abstract</B></P> <P>We present a new high-resolution multiproxy data set of mass accumulation rates, Sr-Nd isotopes, as well as major and trace elements for the siliciclastic sediment fraction from International Marine Global Change Study Core MD06-3052, located on the continental slope of the western Philippine Sea. We integrate our new data with published grain sizes and sea surface temperatures from the same core, as well as with Equatorial Pacific sea level, and East Asian summer monsoon precipitation, in order to constrain at high-resolution changes in physical erosion and chemical weathering intensities on Luzon, and sediment source-to-sink processes. We assess the potential significance of chemical weathering of arc silicates in regulating global atmospheric CO<SUB>2</SUB> since 156kyr BP. Sr-Nd isotopes show that the siliciclastic sediments were dominantly sourced from volcanic rocks exposed on Luzon (~68–100%), with a lesser contribution from Asian dust (~0–32%). Different indices indicate that stronger physical erosion and chemical weathering occurred during Marine Isotope Stage (MIS) 6 (130–156kyr BP), as well as in the latter stage of MIS 3 and MIS 2 (14–40kyr BP). The large sea-level lowstands and associated significant exposure of continental shelf in the western Philippine Sea during these two cold periods should favor physical erosion and chemical weathering of unconsolidated sediments on the exposed shelf. Furthermore, we notice the relatively good coherence between chemical weathering intensities on Luzon and global atmospheric CO<SUB>2</SUB> concentrations over these cold intervals. We suggest that strengthening of chemical weathering of silicates on Luzon and other tropical arcs (within 20° of the Equator) during the Quaternary glacial sea-level lowstands may significantly contribute to the lowering of atmospheric CO<SUB>2</SUB> concentrations during ice ages. We estimate that a significant fraction, up to ~16% (i.e., ~8ppmv), of all atmospheric CO<SUB>2</SUB> ultimately sequestered by silicate weathering may be processed through an area corresponding to only ~1% of the exorheic drainage area worldwide.</P> <P><B>Highlights</B></P> <P> <UL> <LI> First high-resolution silicate weathering study of the western Philippine Sea. </LI> <LI> Glacial sea-level lowstands favored silicate weathering of sediments on exposed shelf. </LI> <LI> Enhanced weathering on tropical arcs significantly sequestered atmospheric CO2. </LI> </UL> </P>

Comparative Analysis of Flavonoids and Polar Metabolite Profiling of Tanno-Original and Tanno-High Rutin Buckwheat

Li, Xiaohua,Kim, Jae Kwang,Park, Soo-Yun,Zhao, Shicheng,Kim, Yeon Bok,Lee, Sanghyun,Park, Sang Un American Chemical Society 2014 Journal of agricultural and food chemistry Vol.62 No.12

<P>Rutin is an important indicator for evaluating the quality of buckwheat. In this study, flavonoid biosynthesis was compared between two common cultivars (an original and a high-rutin line) of buckwheat, <I>Fagopyrum esculentum</I> Moench. Transcriptional levels of the main flavonoid biosynthetic genes were analyzed by real-time PCR, and main flavonoid metabolites were detected by high-performance liquid chromatography (HPLC); levels of gene expression varied among organs of the two cultivars. Significantly higher transcription levels of most flavonoid biosynthetic genes, except <I>FeFLS1</I>, were detected in stems of the high-rutin line than in stems of the original line. <I>FeCHI</I> and <I>FeFLS2</I> genes also showed higher expression levels in seeds of the high-rutin cultivar. In contrast, <I>FePAL</I>, <I>FeC4H</I>, <I>Fe4CL1</I>, <I>FeCHS</I>, <I>FeF3H</I>, <I>FeF3</I>′<I>H</I>, <I>FeFLS2</I>, and <I>FeDFR</I> were highly detected in the roots of the original line. The HPLC results indicated 1.73-, 1.62-, and 1.77-fold higher accumulation of rutin (the primary flavonoid compound) in leaves, stems, and mature seeds of the high-rutin cultivar (24.86, 1.46, and 1.36 μg/mg, respectively) compared with the original cultivar (14.40, 0.90, and 0.77 μg/mg, respectively). A total of 46 metabolites were identified from seeds by gas chromatography–time-of-flight mass spectrometry. The metabolite profiles were subjected to principal component analysis (PCA). PCA could clearly differentiate the original and high-rutin cultivars. Our results indicate that the high-rutin cultivar could be an excellent alternative for buckwheat culture, and we provide useful information for obtaining this cultivar.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2014/jafcau.2014.62.issue-12/jf4049534/production/images/medium/jf-2013-049534_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jf4049534'>ACS Electronic Supporting Info</A></P>

Ethephon-induced Phenylpropanoid Accumulation and Related Gene Expression in Tartary Buckwheat Hairy Root

Xiaohua Li,Aye Aye Thwe,Nam Il Park,Sang Un Park 한국약용작물학회 2014 한국약용작물학술대회 발표집 Vol.2014 No.10

Cloning of Flavonoid Biosynthesis Genes in Fagopyrum esculentum

Xiaohua Li,Nam Il Park,Hui Xu,Sang Un Park 한국작물학회 2010 한국작물학회 학술발표대회 논문집 Vol.2010 No.04

Buckwheat (Fagopyrum esculentum Moench.) is an alternative crop belonging to the Polygonaceae family. Buckwheat has been well known as a plant source of rutin, quercetin, kaempferol-3-rutinoside and other phenolic compounds. Buckwheat contains more rutin than most of the other plants, which exhibits antioxidative, antihemorrhagic and blood vessel protecting properties. Phenylalanin ammonia-lyase (PAL), chalcone synthase (CHS), flavone 3-hydroxylase (F3H), and anthocyanidin synthase (ANS) were important enzymes involved in the flavonoid biosynthesis in buckwheat. In this study, we have purified full-length PAL, CHS, F3H and ANS from buckwheat using RACE PCR with degenerated primers targeted to conserved regions of orthologous sequences PAL, CHS, F3H and ANS available. The open reading frame of FePAL was 2112 nucleotides long, encodes for 704 amino acids. FePAL gene shares 80-81% identity and 88-90% similarity with Arabidopsis thaliana PAL1, Capsicum annuum PAL, Lactuca sativa PAL, and Populus trichocarpa PAL2. The cDNA of FeCHS has 1179 nucleotides open reading frame, encoding for 393 amino acids. FeCHS has identities and similarities ranging 84-86% and 92-95%, respectively, with other CHSs from P. trichocarpa, Citrus sinensis, Gerbera hybrid, and Vitis rotundifolia, whereas this gene shares 93% identity and 98% similarity with Polygonum cuspidatum. The cDNA of FeF3H has 1101 nucleotides open reading frame, encoding for 367 amino acids. FeF3H has identities and similarities ranging 76-81% and 92-97%, respectively, with other F3Hs from Gossypium hirsutum, Dimocarpus longan, Garcinia mangostana, Camellia sinensis, Vitis vinifera, Rubus coreanus, Pyrus communis, Glycine max, and Actinidia chinensis. The open reading frame of FeANS was 1074 nucleotides long, encodes for 358 amino acids. FeANS gene shares 74-76% identity and 94-96% similarity with Gypsophila elegans, C. sinensis and G. hirsutum. These result provieded the theoretical basis for the metabolic engineering on buckwheat.

Synthesis of Polyamine Grafted Chitosan Copolymer and Evaluation of Its Corrosion Inhibition Performance

Li, Heping,Li, Hui,Liu, Yi,Huang, Xiaohua Korean Chemical Society 2015 대한화학회지 Vol.59 No.2

Two new chitosan derivatives, polyamine grafted chitosan copolymers have been synthesized for corrosion protection of carbon steel in acidic medium. First, methyl acrylate graft chitosan copolymer (CS-MAA) was prepared by the reaction of chitosan (CS) and methyl acrylate (MAA) via the Michael addition reaction. Then, CS-MAA was reacted with ethylene diamine (EN) and triethylene tetramine (TN) respectively to synthesize ethylene diamine grafted chitosan copolymer (CS-MAA-EN) and triethylene tetramine grafted chitosan copolymer (CS-MAA-TN), and the structures were characterized by Fourier-transform infrared spectroscopy (FT-IR). At last, the corrosion inhibition activities on Q235 carbon steel were investigated by using gravimetric measurements, metallographic microscope, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The compounds CS-MAA-EN and CS-MAA-TN show an appreciable corrosion inhibition property against corrosion of Q235 carbon steel in 5% HCl solution at $25^{\circ}C$. It has been observed that CS-MAA-EN shows greater corrosion inhibition efficiency than CS-MAA-TN. The inhibition efficiency of CS-MAA-EN was close to 90% when the mass fraction concentration was 0.2%~0.3%; the inhibition efficiency of CS-MAA-TN was close to 85% when the mass fraction concentration was 0.02%. The present work provided very promising results in the preparation of green corrosion inhibitors.

Influence of Light on the Free Amino Acid Content and γ-Aminobutyric Acid Synthesis in Brassica juncea Seedlings

Li, Xiaohua,Kim, Yeon Bok,Uddin, Md Romij,Lee, Sanghyun,Kim, Sun-Ju,Park, Sang Un American Chemical Society 2013 Journal of agricultural and food chemistry Vol.61 No.36

<P>Glutamate decarboxylase (GAD; EC 4.1.1.15) is an important enzyme in γ-aminobutyric acid (GABA) biosynthesis. Here we report the influence of light on amino acid accumulation and investigate the molecular mechanism by which light influences GABA biosynthesis at the seedling stage of two mustard (Brassica juncea) cultivars (green-leaf and purple-leaf). Gene expression profiles of four GAD-encoding genes (<I>GAD1</I>, <I>GAD2</I>, <I>GAD4a</I>, and <I>GAD4b</I>) and their impact on GABA biosynthesis were analyzed. Light exerted an obvious influence on amino acid accumulation in mustard seedlings. <I>GAD</I> gene expression was also significantly regulated by light/dark or dark treatment, which differentially regulated GABA biosynthesis in B. juncea seedlings. High-performance liquid chromatography (HPLC) revealed that the seeds of purple cultivars contain a higher amount of free amino acids and GABA than do the seeds of green cultivars. After seed germination, however, the accumulation of free amino acids peaked in dark-treated seedlings on day 9 in both cultivars, whereas GABA synthesis peaked at 9 days under light conditions. This study may provide a foundation for understanding the effect of light on amino acids, particularly GABA biosynthesis in Brassica plants.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2013/jafcau.2013.61.issue-36/jf401956v/production/images/medium/jf-2013-01956v_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jf401956v'>ACS Electronic Supporting Info</A></P>

Preview Repetitive Control for Linear Continuous-time System

Li Li,Xiaohua Meng,Yonglong Liao 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

This paper presents a preview repetitive control for linear continuous-time systems when a periodic reference signal is previewed. First, an augmented two-dimensional (2D) system is constructed by state augmentation technique and a 2D model approach. Then, the preview repetitive control laws are proposed for the augmented 2D system, which transforms the preview repetitive control problem into a stabilization problem. Using Lyapunov functions, sufficient conditions for asymptotic stability of the 2D continuous-discrete system are derived in the form of linear matrix inequalities (LMIs). The design of a preview repetitive controller is proposed through the LMI approach. Finally, the developed design techniques are applied to two examples. The simulation results demonstrate the validity of the proposed method.

Microwave-Enhanced Reduction of Cr (vi) in Contaminated Soil

Li Lin,Xiaohua Lu,Qingyun Li 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Ethephon-induced Phenylpropanoid Accumulation and Related Gene Expression in Tartary Buckwheat Hairy Root

Xiaohua Li,Aye Aye Thwe,Nam Il Park,Sang Un Park 한국약용작물학회 2014 한국약용작물학회 학술대회논문집 Vol.2014 No.2

Ethephon-induced Phenylpropanoid Accumulation and Related Gene Expression in Tartary Buckwheat Hairy Root

Xiaohua Li(이소화),Sang Un Park(박상언) 한국약용작물학회 2015 한국약용작물학회 학술대회논문집 Vol.2015 No.1