Distribution of nitrogen and phosphorus in sediment cores and overlying water of Donghu Lake

In this study, the seasonal, vertical distribution of various phosphorus and nitrogen forms in the sediment and overlying water of Donghu Lake were investigated. The concentration of total nitrogen (TN) in overlying water was high in spring and autumn, but that of NO3--N reached its peak in autumn. From summer to autumn and from winter to spring, the concentration of phosphorus in overlying water decreased, while it increased from autumn to winter. Vertical characteristic forms of phosphorus in sediment cores are total phosphorus (TP), labile phosphorus (LP), Fe-P and Al-P, obviously enriched in the surface layer (0-10 cm), but their concentrations are observably reduced along with the depth of sediment. The research is of important theoretical and practical value to understand the status and to control the developmental trend of eutrophication in Donghu Lake.

Detection of extracellular phosphatases in natural spring phytoplankton of a shallow eutrophic lake (Donghu, China)

The species-specific production of extracellular phosphatases in phytoplankton of a subtropical polymictic take was investigated from March to May 2004. Phosphatase activity was detected directly at the site of enzyme action using the enzyme-labelled fluorescence (ELF) technique. Size fractionation of bulk phosphatase activity (PA), concentrations of soluble reactive phosphorus (SRP), chlorophyll a, and phytoplankton composition were determined in parallel. Phosphatase-positive cells were present in every phytoplankton sample; labelled cells were detected in 33 algal taxa, including many chlorophytes, dinoflagellates and some diatoms, but never among cyanobacteria. We recorded an unusual dinoflagellate bloom (Peridiniopsis sp.), of which similar to 25% of the cells were phosphatase-positive. Several populations were partly phosphatase-positive whenever present, while some other species never showed any activity. The production of extracellular phosphatases was not primarily regulated by ambient P concentrations; algae produced these enzymes even if SRP concentrations were high. Moreover, heterotrophic nanoflagellates most probably contributed to the pool of particle-bound PA in some samples.

The vertical microdistribution of cyanobacteria and green algae within desert crusts and the development of the algal crusts

Substantial amounts of algal crusts were collected from five different desert experimental sites aged 42, 34, 17, 8 and 4 years, respectively, at Shapotou ( China) and analyzed at a 0.1 mm microscale of depth. It was found that the vertical distribution of cyanobacteria and microalgae in the crusts was distinctly laminated into an inorganic-layer (ca. 0.00 - 0.02 mm, with few algae), an algae-dense-layer ( ca. 0.02 - 1.0 mm) and an algae-sparse-layer ( ca. 1.0 - 5.0 mm). It was interesting to note that in all crusts Scytonema javanicum Born et Flah ( or Nostoc sp., cyanobacterium), Desmococcus olivaceus (Pers ex Ach., green alga) Laundon and Microcoleus vaginatus Gom. ( cyanobacterium) dominated at the depth of 0.02 - 0.05, 0.05 - 0.1 and 0.1 - 1.0 mm, respectively, from the surface. Phormidium tenue Gom. ( or Lyngbya cryptovaginatus Schk., cyanobacterium) and Navicula cryptocephala Kutz.( or Hantzschia amphioxys (Ehr.) Grun. and N. cryptocephala together, diatom) dominated at the depth of 1.0 - 3.0 and 3.5 - 4.0 mm, respectively, of the crusts from the 42 and 34 year old sites. It was apparent that in more developed crusts there were more green algae and the niches of Nostoc sp., Chlorella vulgaris Beij., M. vaginatus, N. cryptocephala and fungi were nearer to the surface. If lichens and mosses accounted for less than 41.5% of the crust surface, algal biovolume was bigger when the crust was older, but the opposite was true when the cryptogams other than algae covered more than 70%. In addition to detailed species composition and biovolume, analyses of soil physicochemical properties, micromorphologies and mineral components were also performed. It was found that the concentration of organic matter and nutrients, electric conductivity, silt, clay, secondary minerals were higher and there were more micro-beddings in the older crusts than the less developed ones. Possible mechanisms for the algal vertical microdistribtion at different stages and the impact of soil topography on crust development are discussed. It is concluded that biomethods ( such as fine species distribution and biovolume) were more precise than mineralogical approaches in judging algal crust development and thus could be a better means to measure the potentiality of algal crusts in desert amelioration.

Vertical variations in kinetics of alkaline phosphatase and P species in sediments of a shallow Chinese eutrophic lake (Lake Donghu)

The vertical distribution of the variables relevant to P forms in sediments were studied in a shallow Chinese freshwater lake (Lake Donghu) in 1997, 1998, 1999 and 2000, to assess the contribution of enzyme to P availability in sediment cores. Sediment P was fractionationd into iron-bound P, calcium-bound P, acid soluble organic P (ASOP) and hot NaOH extractable residual organic P. The former two species made the largest contribution to the sediment P pool. All P species exhibited significantly higher concentrations in different depths at Station I, compared with those found at Station II, except for ASOP. Coupled with these lower ASOP concentrations, the V-max data of alkaline phosphatase, measured on the same samples, were significantly higher at station I. Taken together, ASOP were probably important in supplying the enzymatic substrate (Phosphatase Hydrolyzable Phosphorus, PHP) into interstitial water. Dissolved orthophosphate and PHP concentrations were highly heterogeneous , but peaked in subsurface, paralleled by higher V-max and lower K-m values of alkaline phosphatase, throughout the sediment core. Sediment in the eutrophic lake is not only enriched in available P (iron-bound P), or stores residual P, but also tends to release PHP, thereby inducing the production of alkaline phosphatase and releasing o-P into water column by enzymatic hydrolysis. The latter process may also occur in relatively deep sediment layers.

黄土高原石灰性土壤不同形态磷组分分布特征

以黄土高原自北向南采集的12个0～20 cm耕层土壤为供试土样,采用Tiessen和Moir修正的Hedley土壤有机无机磷分级方法研究了黄土高原石灰性土壤中不同形态磷组分的分布特征。结果表明:供试土壤各形态P总体分布特征为:HCl-P>Residual-P>NaHCO3-Po>NaHCO3-Pi>NaOH-Po>NaOH-Pi>H2O-P,以HCl-P和Residual-P为主,分别占土壤全磷的54.00%～88.96%和0～39.11%。黄土高原土壤磷含量总体分布表现为南高北低。在各土壤类型间,NaOH-Po、Residual-P和全磷平均含量表现为干润砂质新成土<黄土正常新成土<简育干润均腐土<土垫旱耕人为土,自北向南依次增加;H2O-P和HCl-P表现为简育干润均腐土<黄土正常新成土<干润砂质新成土<土垫旱耕人为土,自北向南先降后升,且上升幅度较大。黄土高原土壤全氮与全磷及各形态磷含量相关性均达显著水平,其中与NaOH-Pi、NaOH-Po、HCl-P及全磷含量达到极显著水平。C/N、pH及砂粒与全磷及各形态磷含量呈负相关关系,其中pH与NaHCO3-Po呈显著负相关,与H2O-P、NaHCO3-Pi...

Aspergillus sp136抗细菌耐药活性成分研究

基于广谱抗细菌耐药性这一思路，本研究中心建立了一套抗细菌耐药性化合物的筛选方法。由此从3000多种西南地区特殊生境的微生物和植物样品提取物中筛选获得17个抗细菌耐药性活性样品。对其中一株来自峨嵋山土样的微生物（Aspergillus sp136）进行了深入研究。通过TLC自显影等方法从其发酵产物中追踪分离得到抗耐药有效成分，并鉴定为烟曲霉酸。 采用多种方法对烟曲霉酸的体外抗细菌耐药活性进行评价。在平板扩散法中，烟曲霉酸表现出对青霉素（β-内酰氨抗生素）的协同抗耐药能力，其活性大约3倍于克拉维酸。在MIC的测试实验中，烟曲霉酸表现出对青霉素（β-内酰氨抗生素）以及非β-内酰氨抗生素如红霉素、四环素、氯霉素、链霉素、卡那霉素、庆大霉素的抗耐药能力。在棋盘格杀菌以及时间致死曲线的研究中，烟曲霉酸也表现出对青霉素、红霉素、四环素的协同抗细菌耐药活性。 在广泛的活性筛选中发现烟曲霉酸对LDLR基因具有上调活性，表明烟曲霉酸可能具有降血脂的活性。 在研究中发现，同空白对照相比，烟曲霉酸使耐药菌（Bacillus cereus NCPF63509）细胞外β-内酰胺酶酶活大幅度下降，而细胞内β-内酰胺酶酶活仅略有上升，这表明烟曲霉酸对β-内酰胺酶分泌过程具有抑制作用。 综述了β-内酰胺酶的研究进展。 A two-step agar diffusion method was established to screen wide spectrum synergistic antibacterial agents. By using this method, 17 active samples against antibiotic resistance were discovered from more than 3000 plants and microbes, which were collected from southwest china. One isolate Aspergillus sp136 collected from E-mei mountain area was selected for further studies. From the metabolites of this strain, a synergistic antibacterial compound was isolated by bioautographic TLC assay-guided fractionation and identified as helvolic acid. The synergistic effect of helvolic acid was confirmed by several methods in vitro. The synergistic effect of helvolic acid with penicillin (β-lactam antibiotics) was about 3 times as that of clavulanic acid with penicillin in agar diffusion assay. In MIC studies, helvolic acid exhibited synergistic effects with β-lactam antibiotics such as penicillin and non β-lactam antibiotics such as erythromycin, tetracycline, kanamycin, streptomycin and gentamycin. In checkerboard and time-kill studies, helvolic acid also exhibited synergistic effects with penicillin, erythromycin and tetracycline. In general screen of bioactivities, helvolic acid upregulate LDLR gene, which was indirectly determined by the activity of fluorescent enzyme. Therefore, helvolic acid might have the ability to lower lipid in blood. Compared with blank control, the extracellular β-lactamase activity decrease significantly and the intracellular β-lactamase activity increase slightly in Bacillus cereus NCPF63509 in the presence of helvolic acid, indicating that the secretion of β-lactamase was inhibited by helvolic acid. The research of β-lactamase was reviewed.

中药射干的化学成分研究

本学位论文由4章组成。第一章是论文的主体，报道了中药射干的化学成分研究。第二章是中药射干代用品川射干的化学成分研究，并附带报道了西番莲化学成分的研究结果。第三章是射干、川射干及西番莲提取物化学成分串联质谱分析的报道。第四章为综述，概述了射干及鸢尾属植物的化学成分和药理研究进展。 在第一和二章中分别报道了射干（Belamcanda chinensis (L.) DC.）、川射干 （Iris tectorum Maxim.）及西番莲（Passiflora incarnate L.）化学成分的分离纯化与结构鉴定。采用正、反相硅胶柱层析、凝胶柱层析、薄层制备及HPLC等各种分离方法，从三种药用植物中共分离出68个不同的化合物，其中61个的结构得 得以鉴定，另外4个化合物的结构正在鉴定中，3个由于量少且有点杂质未作进一步的鉴定。 中药射干（Rhizoma Belamcandae）为射干植物的干燥根茎，从中共分离出53个化合物，通过红外、质谱及核磁共振等波谱方法鉴定了包括12个新化合物在内的48个，结构类型分别属于iridal型三萜及其新颖的二聚体、异黄酮、黄酮及黄酮醇、香豆素、甾体、芳香酸和脂肪酸及其甘油酯等。新化合物中有两个异黄酮类化合物，其结构分别鉴定为5,7,8,4′-四羟基-6-甲氧基异黄酮和5,6-二羟基-4′-甲氧基异黄酮-7-O-β-D-吡喃葡萄糖苷；八个新的iridal型三萜化合物分别鉴定为鸢尾烯（L）、16-甲氧基鸢尾烯、16-去羟基鸢尾烯、2-(E)-16-去羟基鸢尾烯、16-去羟基鸢尾烯B、3-乙酰基-16-去羟基鸢尾烯、iristectoroneL和iristectoroneM；两个结构骨架新颖的双三萜，分别命名为射干素A和射干素B，其分离纯化的困难以及结构的新颖和复杂突显出该论文的科学意义。除这些新化合物外，还有9个已知化合物为首次从中药射干中分离得到。此外，从中药射干的代用品川射干中分离得到7个已知化合物，主要是黄酮类成分及iridal型三萜化合物，其中1个三萜化合物为从射干中分离鉴定的新成分。另外还从西番莲中分离出8个化合物，鉴定了其中的6个，主要为黄酮碳苷。 第三章是关于射干、川射干及西番莲提取物化学成分的ESI-MS-MS分析，在初步探讨了从这些植物中分离鉴定出的一些异黄酮及黄酮碳苷的质谱裂解规律基础上，通过质谱和串联质谱分析，定性和半定量地检测了射干和川射干中主要的异黄酮成分以及西番莲中的黄酮碳苷成分，为这些药材品质的快速鉴定提供了一种简便方法。 第四章概述了射干及鸢尾属药用植物的化学和药理研究进展，特别是对其中异黄酮及三萜类成分的研究进展进行了深入系统的综述。 This dissertation is composed by four chapters. The first and second chapter reports the phytochemical investigation of three medicine plants, Belamcanda chinensis (L.)DC., Iris tectorum Maxim. and Passiflora incarnate L. Sixty eight different compounds were isolated and sixty one of them were identified. The third chapter described rapid ESI-MS-MS analysis of B. chinensis, I. tectorum, and P. incarnate. The forth part is a review about the progress of studies on the chemical constituents from Belamcanda chinensis and Iris species. Fifty-three compounds were isolated from Rhizoma Belamcandae, the rhizomes of B. chinensis by the methods of column chromatography (normal and reversed phase silica gel, Sephadex LH-20), preparative TLC and HPLC. On the basis of spectroscopic methods including IR, ESI-MS, 1-D and 2-D NMR, forty eight of them were identified as seventeen flavonoids, seventeen tritepenoids, one cumarin, five steroids and some benzene derivative etc. Among them, the structures of twelve new compounds were elucidated as 6-methoxy-5,7,8,4′-tetrahydryoxyisoflavoe, 4′-methoxy-5,6-dihydroxyisoflavone-7-O-β-D-glucopyranoside, iristectorene L, 16-methoxyisoiridogermanal, 16-dehydroxyisoiridogermanal, 2-(E)-16-dehydroxy isoiridogermanal, 16-dehydroxyiristectorene B, 3-acetyl-16-dehydroxyisoiridoger- manal, iristectorone L, iristectorone M, belamcandene A and belamcandene B. Last two new compounds are dimer of triterpenoids with a novel carbon skeleton. Beside the new compounds, nine known ones were isolated from this plant for the first time. Isolation of I. tectorum yielded seven compounds. On the basis of spectroscopic methods including ESI-MS, NMR and the comparison with authentic samples, three of them were determined as isoflavone, two of them were triterpenoids, and other two were β-sitosterol and apocynin. All of them are known compounds except one of iridal type triterpenoid, 16-dehydroxyiristectorene B, which also obtained from B. chinensis as a new compound. Isolation of P. incarnate yielded eight compounds. Six of them were determined on the basis of spectroscopic methods including ESI-MS, NMR and the comparison with authentic samples. Four of them are flavone-C-gluconside, and two are steroids. The third chapter describes the tandem mass spectrometry (ESI-MS-MS) analysis of the isoflavonoids from B. chinensis and I. tectorum, as well as C-glycosyl-flavonoide from P. incarnate, in order to explore the rapid methodology of validating the quality of the herbs. In addition, the fractionation rules of some iosflavonoids and C-glycosyl-flavonoids were discussed. The fourth chapter summarizes the research development on chemistry and pharmacology of medicine plants of B.chinensis and Iris species.

千金子和暖地大叶藓的化学成分研究

本论文由三部分共4 章组成。第一部分阐述了大戟科大戟属传统中药千金子（Euphorbia lathyris L.）化学成分、生物学活性以及千金子化学成分的HPLC、UPLC-MS、GC-MS 分析成果。第二部分介绍了民族药材暖地大叶藓（Rhodobryum giganteum (Schwaegr.) Par.）的化学成分研究和结构鉴定。第三部分概述了大戟属 植物中大环二萜酯的研究进展。 第一章包括1－3 节。在第1, 2 节中报道了千金子（Euphorbia lathyris L.）95% 乙醇提取物的化学成分分离鉴定。我们采用正、反相硅胶柱层析、重结晶等各种分离方法，凭借MS、IR、NMR、X-ray 等现代仪器手段,从中共分离鉴定22 个化合物。其中8 个是高活性化合物前体-续随子烷型大环二萜及3 个巨大戟烷型二萜，还有香豆素、生物碱、甾体等类型，其中完成对5 个大环二萜酯构型的确认，对2 个二萜酯构型进行了修正。第3 节中介绍对千金子化学成分的细胞毒性、α-葡萄糖苷酶抑制活性、P-gp 表达抑制活性的模型筛选结果。 第二章包括3 节，第1 节报道不同产地千金子高效液相色谱定量分析结果。第2 节介绍了各大环二萜酯的HPLC-MS/MS 的分析结果，并且对其质谱裂解规律、UPLC-MS 快速鉴定方法做了进一步讨论。第3 节介绍了千金子挥发油成分分析。采用传统水蒸气蒸馏方法提取千金子中的挥发油，并经气相色谱－质谱联用（GC-MS）技术共分离鉴定出 49 个化合物，占挥发油总量的90.48％。 第三章包括1, 2 两节，第1 节报道了暖地大叶藓化学成分。采用正、反相硅胶，凝胶柱层析等各种分离方法和MS、IR、NMR 等解析手段，共分离鉴定10个化合物，其中一个环肽化合物为新化合物。第2 节介绍了暖地大叶藓挥发油成分分析，共分离鉴定出 52 个化合物，占其挥发油总量的85.67％。 第四章概述了大戟科大戟属植物中大环二萜酯的研究进展。 This dissertation consists of three parts. In the first part, it is elaborated that the phytochemical investigation from the traditional Chinese medicine: seeds of Euphorbia lathyris L.. Biological activity and constituents analysis by HPLC、UPLC-MS、GC-MS were reported. In the second part, it is discussed that the chemical constituents were isolated and identificated from minority nationalitical herb－Rhodobryum giganteum (Schwaegr.) Par.. The third part is a review about the progress of studies on macrocyclic diterpenes from Euphorbia. The first part is composed of 1－3 sections. The section 1and 2 is focused on the isolation and identification of chemical constituents from seeds of E. lathyris. 22 compounds were isolated from the seeds of E. lathyris. by isolation methods of column chromatography (silica gel, including reversed phase) and recrystallisation on the basis of spectroscopic methods including IR, MS, NMR and X-ray. In 8 macrocyclic and 3 ingenane diterpenes, the relative configuration of 5 macrocyclic diterpenes were confirmed, in which 2 were amended. In the third section, cell cytotoxic activity, restraining activity of α-Glucosidase and multidrug resistance (MDR) reversing activity about P-gp were tested. 5 potential revsering reagents were found. The second part is composed of 1－3 sections. In first section it is described that the quality of the chemical constituents of E. lathyris from 5 sources , which were analyzed by high-performance liquid chromatography. In addition, the fractionation rules of some macrocyclic diterpenes were discussed and Ultra Performance Liquid Chromatography/ electrospray ionization mass spectrometry (UPLC-MS) was applied for quick determination of compounds in the second section. In the third section, chemical analysis of the essential oil from seeds of E. lathyris by GC-MS were reported. The essential oil from the seeds of E. lathyris L. in Sichuan was extracted by steam distillation and 49 compounds were isolated and identified from the essential oil by gas chromatography-mass spectrometer (GC-MS). These compounds are accounted for 90.46% of the total essential oil. The second part, including section 4 and 5, is about the phytochemical investigation of R. giganteum. In the former section, ten compounds were isolated and identified. Among them, a new peptide was characterized by spectroscopic analysis including IR, MS and NMR. In the other section, 52 compounds were isolated and identified from the essential oil by gas chromatography-mass spectrometer (GC-MS). These compounds are accounted for 85.67% of the total essential oil. The third part is a review about the progress of studies on macrocyclic diterpenes from Euphorbia.

Systematic study of the pi(-)/pi(+) ratio in heavy-ion collisions with the same neutron/proton ratio but different masses

A systematic study of the pi(-)/pi(+) ratio in heavy-ion collisions with the same neutron/proton ratio but different masses can help single out effects of the nuclear mean field on pion production. Based on simulations using the IBUU04 transport model, it is found that the pi(-)/pi(+) ratio in head-on collisions of Ca-48 + Ca-48, Sn-124 + Sn-124, and Au-197 + Au-197 at beam energies from 0.25 to 0.6 GeV/nucleon increases with increasing the system size or decreasing the beam energies. A comprehensive analysis of the dynamical isospin fractionation and the pi(-)/pi(+) ratio as well as their time evolution and spatial distributions demonstrates clearly that the pi(-)/pi(+) ratio is an effective probe of the high-density behavior of the nuclear symmetry energy.

DETERMINING THE DENSITY DEPENDENCE OF THE NUCLEAR SYMMETRY ENERGY USING HEAVY-ION REACTIONS

We review recent progress in the determination of the subsaturation density behavior of the nuclear symmetry energy from heavy-ion collisions as well as the theoretical progress in probing the high density behavior of the symmetry energy in heavy-ion reactions induced by high energy radioactive beams. We further discuss the implications of these results for the nuclear effective interactions and the neutron skin thickness of heavy nuclei.

Isospin effects of the Skyrme potential and the momentum dependent interaction at intermediate energy heavy ion collisions

We improve the isospin dependent quantum molecular dynamical model by including isospin effects in the Skyrme potential and the momentum dependent interaction to obtain an isospin dependent Skyrme potential and an isospin dependent momentum interaction. We investigate the isospin effects of Skyrme potential and momentum dependent interaction on the isospin fractionation ratio and the dynamical mechanism in intermediate energy heavy ion collisions. It is found that the isospin dependent Skyrme potential and the isospin dependent momentum interaction produce some important isospin effects in the isospin fractionation ratio

Isospin effect in the nuclear reaction induced by neutron-halo nuclei

We study the average property of the isospin effect of reaction induced by halo-neutron nuclei He-8 and He-10 in the intermediate energy heavy ion collisions using the isospin-dependent quantum molecular dynamics model (IQMD). This study is based on the extended neutron density distribution for the halo-neutron nuclei, which includes the average property of the isospin effect-of reaction mechanism and loose inner structure. The extended neutron density distribution brings an important isospin. effect into the average property of reaction mechanism because the interaction potential and nucleon-nucleon(N-N) cross section in IQMD model depend sensitively on the density distribution of colliding system. In order to see clearly the average properties of reaction mechanism induced by halo-neutron nuclei we also compare the results for the neutron-halo colliding systems with those for the corresponding stable colliding systems under the same incident channel condition. We found that the extended density distribution for the neutron-halo projectile brings an important isospin effect to the reaction mechanism, which leads to the decrease of nuclear stopping R, yet induces obvious increase of the neutron-proton ratio of nucleon emissions and isospin fractionation ratio for all beam energies studied in this work, compared to the corresponding stable colliding system. In this case, nuclear stopping, the neutron-proton ratio of nucleon emissions and isospin fractionation ratio induced by halo-neutron nuclei can be used as possible probes for studying the average property of the isospin effect of reaction mechanism and extracting the information of symmetry potential and in-medium N-N cross section by the neutron-halo nuclei in heavy ion collisions.

Probing the symmetrical potential in nuclear reaction iinduced by neutron-halo nuclei

In terms of the isospin-dependent quantum molecular dynamics model (IQMD), important isospin effect in the halo-neutron nucleus induced reaction mechanism is. investigated, and consequently, the symmetrical potential form is extracted in the intermediate energy heavy ion collision. Because the interactive potential and in-medium nucleon-nucleon (N-N) cross section in the IQMD model sensitively depend on the density distribution of the colliding system, this type of study is much more based on the extended density distribution with a looser inner nuclear structure of the halo-neutron nucleus. Such a density distribution includes averaged characteristics of the isospin effect of the reaction mechanism and the looser inner nuclear structure. In order to understand clearly the isospin effect of the halo-neutron nucleus induced reaction mechanism, the effects caused by the neutron-halo nucleus and by the stable nucleus with the same mass are compared under the same condition of the incident channel. It is found that in the concerned beam energy region, the ratio of the emitted neutrons and protons and the ratio of the isospin fractionations in the neutron-halo nucleus case are considerably larger than those in the stable nucleus case. Therefore, the information of the symmetry potential in the heavy ion collision can be extracted through such a procedure.

Flipped symmetry potential in heavy-ion collisions

Within the IBUU transport model, flipping of the symmetry potential in heavy-ion collisions is studied. It is found that there exist flipping of the symmetry potential in the isospin fractionation, the single neutron to proton ratio, the double neutron to proton ratio and the neutron-proton differential flow from lower to higher incident energies. The flipping of the symmetry potential results from the change of the relative magnitude of the hard and soft symmetry energies at lower and higher densities. Future observations of the flipped symmetry potential in experiment will help the study of the density-dependent symmetry energy.