A Study of the Comets with Large Perihelion Distances C/2019 L3(ATLAS)and C/2019 O3(Palomar)

This work analyzes the photometric data of the Oort spike comets C/2019 L3(ATLAS)and C/2019 O3(Palomar)obtained between 2016 and 2023 by the ATLAS network and the Belgian Olmen Observatory.The comets Palomar and ATLAS have a typical and unusually high activity level,respectively,based on the Afρparameter corrected to phase angle zero at perihelion.The absolute magnitude of comets ATLAS and Palomar in the o-band is 4.71±0.05 and 4.16±0.02 respectively.The cometary activity of comets ATLAS and Palomar probably began at r>13 au before perihelion and will end at r>14 au after perihelion,which means that they could remain active until the second half of 2026.The nucleus of comet ATLAS has a minimum radius of 7.9 km,and the nucleus of comet Palomar could be a little larger.The c-o colors of the comets ATLAS and Palomar are redder and bluer,respectively,at perihelion than the solar twin YBP 1194.These comets showed a bluish trend in the coma color with decreasing heliocentric distance.Comet Palomar probably had two outbursts after its perihelion,each releasing about 10^(8)kg of dust.The slopes of the photometric profile of the comae of these comets were between 1and 1.5,indicating a steady state during the observation campaign.

Petrographic and Geochemical Characteristics of the Pouni Palaeoproterozoic Formations North of the Léo Square Degree (Burkina Faso, West Africa)

The Pouni area is made up of basalts belonging to the Boromo belt, lamprophyres and granitoids. These geological formations are similar to geological formations of the same type in other regions of the Palaeoproterozoic domain of the Man/Leo shield. This study, which focused on the petrographic and geochemical characteristics of these geological formations, led to the following main conclusions: The lamprophyres are basic plutonic rocks that cut through other geological formations. The basalt belongs to the northern part of the Borormo belt and is thought to be a relic of overthickened oceanic plateaus. There are two groups of granitoid rocks. The granodiorite has a geochemical signature close to that of Archean TTGs and is metaluminous in character. It has a low potassium content. The minor element and rare earth element spectra indicate that it could be derived from partial melting of basic magmatic rocks. Biotite granites are peraluminous and highly potassic. Minor element contents and rare earth spectra indicate that they could be derived from partial melting of felsic materials. Geotectonic diagrams show that the granitoids identified in the Pouni zone were emplaced in an active tectonic context, similar to that of present-day subduction zones.

RAFM与316L钢等离子喷涂Al_2O_3电绝缘涂层研究

在液态金属冷却、磁约束聚变反应堆中,磁流体动力学(MHD)压降是一个不容忽视的问题,包层结构材料内壁涂敷电绝缘涂层是降低MHD压降的最有效方法。本文利用大气等离子喷涂(APS)工艺分别在316L钢和一种新的低活化铁素体/马氏体(RAFM)钢上制备Al2O3电绝缘涂层,研究结果表明:氧化铝涂层表面质量好;涂层的显微硬度较高、致密度较好;涂层与RAFM钢和316L钢基体结合较好,平均结合强度值分别为33.7和27.8 MPa;RAFM钢上涂层抗热震性优良,其原因在于RAFM钢的热膨胀系数与氧化铝陶瓷很好地匹配;两种钢基体上涂层的常温电阻率均为8.0×1012Ω.cm左右。

3Al_2O_3·2SiO_(2f)/ZL107复合材料和ZL107基体在不同温度下的高温蠕变行为

研究了过时效状态的ZL10 7基体和体积分数为 16 % 3Al2 O3.2SiO2f/ZL10 7复合材料在 30 0℃的蠕变断裂行为。结果表明 ,二者都表现出较高的蠕变应力指数和蠕变激活能 。

花生油酸/亚油酸(O/L)比值的AFLP分子标记筛选

通过采用不同的酶切组合,即EcoRⅠ/MseⅠ组合240对引物、PstⅠ/MseⅠ组合96对引物、PstⅠ/TaqⅠ组合96对引物,分别对花生高油酸品种Sunoleic95R和低油酸品种汕油162进行AFLP分析。分析了两亲本之间的差异,回收了72条AFLP多态性条带,在所选定高和低O/L比值亲本材料之间建立了AFLP片段序列数据库。

基于COCA语料库的英语近义词研究——以careful和cautious为例

大量的英语近义词一直困扰着中国英语学习者和教师。本文选取careful和cautious这对形容词近义词作为研究对象,以COCA语料库为研究工具,探讨两词在语域,类联结以及搭配上的不同说明在教学中如何利用语料库辨析近义词。文章以careful和cautious这对形容词为例说明在教学中如何运用语料库能更准确地把握同义词的区别从而实现更贴近本族语者的表达。

HETERONUCLEAR COMPLEX CONTAINING COPPER-LANTHANIDE ARRAYS: THE SYNTHESIS AND CRYSTAL STRUCTURE OF Ln_2Cu_4L_8 (HL)_4(OH)_2(CIO_4)_4(H_2O)_(10)·2CH_3COCH_3 (Ln = Tb (1), Y (2); HL = 2-Pyridone C_5H_5NO)

Reaction of 2-pyridone, copper acetate and terbium(or yttrium) perchlorate in acetone with the mole ratio 6: 2: 1 results in the formation of heteronuclear complex Ln_2Cu_4L_8 (HL)_4 (OH)_2 (ClO_4)_4 (H_20)_(10) 2CH_3COCH_3(Ln = Tb (1), Y (2)). By recrystallizing (1) in CHCl_3 single crystals were obtained and the structure was determined by four-circle diffractometer. Data showed that the crystal is in space group C2/m with a=27. 454(9)A, b=13, 608A, c=30. 556(11)A, β=99. 89(3)°, v=11245. 7(7. 5)A^3. The structure was solved by a combination of Patterson method and Fourier technique. The final R value is 0. 103. In the structure, four copper and two terbium ions are bridged by 2-pyridone anions to form an essentially octahedral Cu_4Tb_2 core. The terbium atoms are each eight-coordinate and the copper atoms are five-coordinate.

W/O乳液电纺Poloxamer188■复合聚L-乳酸纤维的表征

目的探究Poloxamer188■复合聚乳酸W/O乳液在电纺纤维中的形态特征和材料复合性能。方法利用Poloxamer188■作为乳化剂,以Poloxamer188■和聚L-乳酸的二氯甲烷溶液作为油相,纯水作为水相,在水相与油相体积比为1∶10的条件下,通过超声波乳化技术制备出W/O型乳液,随后进行静电纺丝。通过光学显微镜观察纺丝所得产品的形态,并采用红外光谱、差示热分析、X-射线衍射和络合显色-分光光度法等技术手段,对释放出的Poloxamer188■进行测定,并绘制出时间-释放百分率曲线,以此对材料复合物进行详细表征。结果获取超细纤维,并随着Poloxamer188■复合量增加,红外光谱、差示热分析曲线和X-射线衍射图谱逐渐展现出Poloxamer188■的特征峰。Poloxamer188■从纤维中的释放表现出明显突释现象,随后是约48 h的缓释阶段,之后进入平台期。随着Poloxamer188■复合量提升,其突释量和平台期的释放量也随之增加,并呈现出线性关系。结论通过W/O乳液静电纺丝技术,可以制备出超细纤维。随着Poloxamer188■比例的调整,其与聚L-乳酸的复合程度也会相应改变。

以水稻雄性不育系为母本不经幼胚培养获得Oryza sativa×O.officinalis杂种的研究

利用亚洲栽培稻(Oryza sativa L.)的核质互作型和光敏感型雄性不育系为母本,药用野生稻(O.officinalis Wall)为父本进行杂交,首次在未经幼胚培养的条件下得到了杂种种子。杂种F_1生长优势强,分蘖力和发根力等超过双亲,并具有父本的植株散生、高位分蘖、小穗具芒、穗分枝散生、落粒性和感光性强等特性。其酯酶同工酶谱中含有双亲的全部酶带。花粉母细胞中染色体数为2n=24,在减数分裂中期Ⅰ。基本上全部为单价体。杂种自交不孕。本研究结果表明,利用雄性不育系进行异源种间的远缘杂交具有简化杂交过程以便大量配组、增加异源遗传物质导入机会和杂种可靠、便于鉴定等优点。本研究不但对探讨水稻远缘杂交的新途径有一定意义,而且为雄性不育系的利用展开了新的视野。

Effects of exogenous salicylic acid on growth and H_2O_2-metabolizing enzymes in rice seedlings under lead stress

Salicylic acid （SA） was an essential component of the plant resistance to pathogens and also plays an important role in mediating plant response to some abiotic stress. The possible effects of SA on the growth and H2O2-metabolizing enzymes in rice seedlings under lead stress were studied. When rice seedlings grown in nutrient solution containing Pb^2＋ （0, 0.05, 0.15, 0.25 mmol/L） for 18 d, the plant biomass as well as the chlorophyll content of leaves decreased with increasing Pb concentration. The pre-treatment with SA （treated with 0.1 mmol/L SA for 48 h before Pb stress） partially protected seedlings from Pb toxicity. The chlorophyll contents were significant higher in leaves of Pb-exposed with SA pre-treatment seedlings than in Pb-exposed plants at the same Pb intensity. SA pre-treated alone could significantly increase the length of shoot and root of seedlings but the vigour difference was not marked under long-term exposure to Pb toxicity. SA pre-treated influence the H2O2 level in leaves of seedlings by up-regulating the activity of superoxide dismutase （SOD）, repressing the activity of catalase （CAT） and ascorbate peroxidase （APX） depending on the concentrations of Pb^2＋ in the growth medium. The results supported the conclusion that SA played a positive role in rice seedlings against Pb toxicity.

Synthesis,Characterization and Antibacterial Properties of Rare Earth (Ce^(3+) ,Pr^(3+) ,Nd^(3+) ,Sm^(3+) ,Er^(3+) ) Complexes with L-Aspartic Acid and o-Phenanthroline

Five novel ternary complexes of rare earth ions with L-Aspartic acid (Asp) and o-phenanthroline (Phen) were synthesized in ethanol aqueous solution. Their compositions were characterized by elemental analysis, molar conductance, FT-IR, Raman, UV-VIS and TG-DTA. The compositions of the complexes were confirmed to be: RE( Asp)3PhenCl3·3H2O (RE: Ce3+ , Pr3+ , Nd3+ , Sm3+ , Er3+ ). The antibacterial activity test shows that all these complexes exhibit excellent antibacterial ability against Escherichia coli, Staphylococcus aureus and Candida albicans. The antimicrobial spectrum of the complexes are broad.

Using an image segmentation and support vector machine method for identifying two locust species and instars

Locusts are agricultural pests around the world. To cognize how locust distribution density and community structure are related to the hydrothermal and vegetation growth conditions of their habitats and thereby providing rapid and accurate warning of locust invasions, it is important to develop efficient and accurate techniques for acquiring locust information. In this paper, by analyzing the differences between the morphological features of Locusta migratoria manilensis and Oedaleus decorus asiaticus, we proposed a semi-automatic locust species and instar information detection model based on locust image segmentation, locust feature variable extraction and support vector machine(SVM) classification. And we subsequently examined its applicability and accuracy based on sample image data acquired in the field. Locust image segmentation experiment showed that the proposed GrabCut-based interactive segmentation method can be used to rapidly extract images of various locust body parts and exhibits excellent operability. In a locust feature variable extraction experiment, the textural, color and morphological features of various locust body parts were calculated. Based on the results, eight feature variables were selected to identify locust species and instars using outlier detection, variable function calculation and principal component analysis. An SVM-based locust classification experiment achieved a semi-automatic detection accuracy of 96.16% when a polynomial kernel function with a penalty factor parameter c of 2 040 and a gamma parameter g of 0.5 was used. The proposed detection model exhibits advantages such as high applicability and accuracy when it is used to identify locust instars of L. migratoria manilensis and O. decorus asiaticus, and it can also be used to identify other species of locusts.

Genetic Diversity Analysis of Wild Tea Plants in Yunnan Province Using EST-SSR Markers

In this study, 27 pairs of EST-SSR primers were employed to analyze the genetic diversity and genetic relationship of 100 wild tea plant germplasm re- sources and 22 cultivars, according to the results, a total of 88 polymorphic bands were amplified with 27 pairs of primers; the variation of effective alleles accounted for 69.01% ; a total of 183 genotypes were detected, with a variation range of 4 -11 ; averagely 6.78 genotypes were amplified with each primer pair; Shannon index （I） of 27 primer pairs ranged from 0.32 to I. 35, with an average of 0.88 ; the observed heterozygosity （0.52） was basically consistent with the expected het- erozygosity （0.52） ; the average polymorphism heterozygosity was 0.48, which was very close to 0.50 ; the average Nei＇s index was 0.51, which was higher than 0. 50 ; the average polymorphism information content （PIC） was 0.52, which was higher than 0.50, indicating high genetic diversity among wild tea germplasm resources in Yuunan Province. According to the clustering results, based on geographical origins and genetic backgrounds, 122 materials were clustered into 14 categories. Dendrogram based on Nei＇s genetic distance revealed complex genetic relationships among wild tea germplasm resources in Yunnan Province. This study provided certain reference for subsequent preservation, development and research of wild tea germplasm resources in China.

Chemical constituents from Schisandra sphenanthera

The chemical constituents of the stems of Schisandra sphenanthera are described for the first time. This investigation has resulted in the isolation of a new phenolic glycoside （1）, along with seven known compounds. The structure of 1 was assigned by using spectroscopic techniques, including 2D NMR spectra.

Genotypic Analysis of Heading Time on an Indica Rice Cultivar,Nanjing 11

In this paper, the genotype of heading time in Nanjing 11, an indica variety, was analyzed by crossing with tester varieties, Akihikari (e1e1e2e2e3e3SeleSele), Koshihikari (E1E1E2E2 e3e3 SeleSele), Nipponbare(E1E1e2e2e3e3Se1Se1 )and HinohikarKEjE^ E2E2 e3e3 SelSel), of which the genotypes of heading time were well known. The results showed genotype of heading time in Nanjing 11 was E1E1 e2e2 E3E3 SelSel and also included a recessive inhibitor i-Sel for photoperiod-sensitivity as well. Meanwhile, the two photoperiod-sensitive genes, E1 and Sel, in Nanjing 11 were also identified by crossing with QTL nearly isogenic lines of Nipponbare, NIL(Hdl )and NIL(Hd4)which have complementary effects.

A novel antimicrobial flavonoidic glycoside from the leaves of Alstonia macrophylla Wall ex A.DC(Apocynaceae)

A new flavonoidic glycoside,tricin-4’-O-β-L-arabinoside(1) was isolated from the leaves of Alstonia macrophylla along with two known flavonoids,vitexin and myricetin-3′-rhamnoside-3-O-galactoside.Their structures were established by chemical and spectral evidences.The known compounds were reported for the first time from this plant.Moreover compound 1 was tested for antifungal and antibacterial activities.

Gnetifolin L and O, Two Dimeric Stilbenes from Gnetum Montanum

Two new dimeric stilbenes, named gnetifolin L and gnetifolin O, were isolated from the alcoholic extract of lianas of Gnetum montanum. Their structures were elucidated mainly on the basis of spectroscopic data including 2D-NMR studies on peracetate derivatives.

Promoter methylation status of hMLH1,MGMT,and CDKN2A/p16 in colorectal adenomas

AIM:To investigate aberrant DNA methylation of CpG islands and subsequent low-or high-level DNA microsatellite instability(MSI)which is assumed to drive colon carcinogenesis. METHODS:DNA of healthy individuals,adenoma(tu-bular or villous/tubulovillous)patients,and colorectal carcinoma patients who underwent colonoscopy was used for assessing the prevalence of aberrant DNA methylation of human DNA mismatch repair gene mutator L homologue 1(hMLH1),Cyclin-dependent kinase inhibitor 2A(CDKN2A/p16),and O-6-methylguanine DNA methyltransferase(MGMT),as well as their rela- tion to MSI. RESULTS:The frequency of promoter methylation for each locus increased in the sequence healthy tissue/adenoma/carcinoma.MGMT showed the highest frequency in each group.MGMT and CDKN2A/p16 presented a statistically significant increase in promoter methylation between the less and more tumorigenic forms of colorectal adenomas(tubular vs tubullovillous and villous adenomas).All patients with tubulovillous/villous adenomas,as well as all colorectal cancer patients,showed promoter methylation in at least one of the examined loci.These findings suggest a potentially crucial role for methylation in the polyp/adenoma to cancer progres- sion in colorectal carcinogenesis.MSI and methylation seem to be interdependent,as simultaneous hMLH1, CDKN2A/p16,and MGMT promoter methylation was present in 8/9 colorectal cancer patients showing the MSI phenotype. CONCLUSION:Methylation analysis of hMLH1,CD- KN2A/p16,and MGMT revealed specific methylation profiles for tubular adenomas,tubulovillous/villous adenomas,and colorectal cancers,supporting the use of these alterations in assessment of colorectal tumorigenesis.

Two New Flavonol Glycosides from Bridelia tomentosa

Two new flavonol glycosides, tamarixetin 3-O-β-D-xylopyranosyl-（1-2）-α-L-ribopyranoside （1） and tamarixetin 3-O-α-L-ribopyranoside （2） were isolated from the leaves of Bridelia tomentosa. Their structures were elucidated by 1D and 2D NMR analysis, as well as MS and IR spectra.

Response of nitrogen mineralization dynamics and biochemical properties to litter amendments to soils of a poplar plantation

Understanding the impact of plant litters on soil nitrogen （N） dynamics could facilitate development of management strategies that promote plantation ecosystem function. Our objective was to evaluate the effects of different litter types on N mineralization and availability, microbial biomass, and activities of L-asparaginase and odiphenol oxidase （o-DPO） in soils of a poplar （Populus deltoides） plantation through 24 weeks of incubation experiments. The tested litters included foliage （F）, branch （B）, or root （R） of poplar trees, and understory vegetation （U） or a mixture of F, B, and U （M）. Litter amendments led to rapid N immobilization during the first 4 weeks of incubation, while net N mineralization was detected in all tested soils from 6 to 24 weeks of incubation, with zero-order reaction rate constants （k） ranging from 7.7 to 9.6 mg N released kg-1 soil wk-1. Moreover, litter addition led to increased （C） 49-128% and increased microbial biomass carbon MBC：MBN ratio by 5-92%, strengthened activities of L-aspaxaginase and o-DPO by 14-74%; Up to about 37 kg N ha-1 net increase in mineralized N in litter added soils during 24 weeks of incubation suggests that adequate poplar and understory litter management could lead to reduced inputs while facilitate sustainable and economic viable plantation production.