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941.
MicroRNAs are a recently identified class of small regulatory RNAs that target more than 30% protein-coding genes. Elevating evidence shows that miRNAs play a critical role in many biological processes, including developmental timing, tissue differentiation, and response to chemical exposure. In this study, we applied a computational approach to analyze expressed sequence tags, and identified 32 miRNAs belonging to 22 miRNA families, in three earthworm species Eisenia fetida, Eisenia andrei, and Lumbricus rubellus. These newly identified earthworm miRNAs possess a difference of 2-4 nucleotides from their homologous counterparts in Caenorhabditis elegans. They also share similar features with other known animal miRNAs, for instance, the nucleotide U being dominant in both mature and pre-miRNA sequences, particularly in the first position of mature miRNA sequences at the 5' end. The newly identified earthworm miRNAs putatively regulate mRNA genes that are involved in many important biological processes and pathways related to development, growth, locomotion, and reproduction as well as response to stresses, particularly oxidative stress. Future efforts will focus on experimental validation of their presence and target mRNA genes to further elucidate their biological functions in earthworms. 相似文献
942.
Copper-catalyzed cross dehydrogenative coupling reactions of tertiary amines with ketones or indoles
A novel cross dehydrogenative coupling (CDC) reaction of N,N-dimethylanilines with methyl ketones by cooperative copper and aminocatalysis has been developed, which leads to the formation of β-arylamino ketones in 42-73% yields. Moreover, the copper-catalyzed alkylation of free (NH) indoles with N,N-dimethylanilines via CDC reaction is also presented, affording alkylated indoles in 52-78% yields. 相似文献
943.
Qingxiang Zhou Jinli Mao Junping Xiao Guohong Xie 《Journal of separation science》2010,33(9):1288-1293
This paper describes a new method for the direct separation of paraquat and diquat by CZE with ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate employed as reliable electrolyte. Several factors that affect the separation efficiency were investigated in detail. The experimental results indicated that the optimal running buffer consisted of 50 mM 1‐butyl‐3‐methylimidazolium hexafluorophosphate and 10% ethanol (pH 5.0), applied voltage was 15 kV, and temperature was kept at 30°C and baseline‐separation was achieved within 18 min for the analytes. The proposed method would be very useful and have wide use to monitor the residual level of such pollutants when combined with high‐sensitive detector and an excellent sample preconcentration technique with high enrichment factor in the future. 相似文献
944.
Yuqin Yao Zhihui Cheng Haoyu Ye Yongmei Xie Jing He Minghai Tang Tao Shen Jiangman Wang Yan Zhou Zejun Lu Feng Luo Lijuan Chen Luoting Yu Jin‐Liang Yang Aihua Peng Yuquan Wei 《Journal of separation science》2010,33(9):1331-1337
Ansamitocin P‐3 is a potent anti‐tumor maytansinoid found in Actinosynnema pretiosum. However, due to the complexity of the fermentation broth of Actinomycete, how to effectively separate ansamitocin P‐3 is still a challenge. In this study, both analytical and preparative high‐performance counter‐current chromatography were successfully used to separate and purify ansamitocin P‐3 from fermentation broth. A total of 28.8 mg ansamitocin P‐3 with purity of 98.4% was separated from 160 mg crude sample of fermentation broth in less than 80 min with the two‐phase solvent system of hexane–ethyl acetate–methanol–water (0.6:1:0.6:1, v/v/v/v). The purity and structural identification were determined by HPLC, 1H NMR, 13C NMR and mass spectroscopy. 相似文献
945.
Yunrui Huang Qingxiang Zhou Junping Xiao Guohong Xie 《Journal of separation science》2010,33(14):2184-2190
This article described a new method for the sensitive determination of organophosphorus pesticides in water samples using SPE in combination with GC‐flame photometric detection. In the procedure of method development, TiO2 nanotubes were used as SPE adsorbents for the enrichment of organophosphorus pesticides from water samples. Several factors, such as eluent and its volume, sample pH, sample volume, sample flow rate, and concentration of humic acid, were optimized. Under the optimal conditions, the proposed method had good linear ranges as 0.1–40 μg/L for each of them, LOD of 0.11, 0.014, and 0.0025 μg/L, and LOQs of 0.37, 0.047, and 0.0083 μg/L for chlorpyrifos, phorate, and methyl parathion, respectively. The proposed method was validated with real environmental water samples and the spiked recoveries were over the range of 86.5–115.1%. All these results indicated that TiO2 nanotubes, as a new SPE adsorbent, would be used widespread for the preconcentraiton and determination of environmental pollutants in the future. 相似文献
946.
Biyang Deng Fang Xie Linqiu Li Aihong Shi Yang Liu Huihui Yin 《Journal of separation science》2010,33(15):2356-2360
A novel method for the determination of galanthamine (GAL) in Bulbus Lycoridis Radiatae has been developed based on coupling CE with an end‐column tris(2,2′‐bipyridyl)ruthenium(II) electrochemiluminescence (ECL). Parameters affecting CE separation and ECL detection were investigated and optimized. Baseline separation of GAL from other components in the Bulbus Lycoridis Radiatae sample was achieved with an 18 mmol/L phosphate running buffer at pH 9.0. Under the optimized conditions: 12 kV CE‐separation voltage, ECL detection potential at 1.25 V with 5 mmol/L and 50 mmol/L phosphate buffer at pH 7.5 in the detection reservoir, the linear range of GAL concentration was from 0.8 ng/mL to 2 μg/mL, whereas the detection limit was 0.25 ng/mL (S/N=3). The proposed method was successfully demonstrated for the determination of GAL in Bulbus Lycoridis Radiatae. 相似文献
947.
Nα-tert-Butoxycarbonyl-L-trans-4-hydroxyproline allyl ester (Boc-Hyp-OAll) was glycosylated with 2,3,5-tri-O-benzyl-L-arabinose p-cresylthioglycoside in 60% yield with 4:1 β:α stereoselectivity. Deprotection of N- and C-terminii independently gave a prolyl amine and prolyl carboxylate respectively that were coupled under standard conditions with 1-[bis-(dimethylamino)methylene]-1H-1,2,3-triazolo-[4,5,b]-pyridininium hexafluorophosphate 3-oxide (N-HATU) to give the dimer 1 in 46% yield. These results represent the first steps toward the production of homogeneous oligomers to determine the minimal epitope of the Art v 1 allergen. 相似文献
948.
Sun Z Wang H Xie Y King RB Schaefer HF 《Dalton transactions (Cambridge, England : 2003)》2010,39(44):10702-10711
Azulene is reported to react with Mn(2)(CO)(10) to give trans-C(10)H(8)Mn(2)(CO)(6), which has been shown by X-ray crystallography to have a bis(pentahapto) structure with no metal-metal bond. This structure is found by density functional theory to be the lowest energy C(10)H(8)Mn(2)(CO)(6) structure. However, a corresponding bis(pentahapto) cis-C(10)H(8)Mn(2)(CO)(6) structure, also without an Mn···Mn bond, lies within ~1 kcal mol(-1) of this global minimum. The lowest energy C(10)H(8)Mn(2)(CO)(5) structure is singlet cis-η(5),η(5)-C(10)H(8)Mn(2)(CO)(5) with an Mn→Mn dative bond from the Mn(CO)(3) group to the Mn(CO)(2) group. However, a singlet cis-η(6),η(4)-C(10)H(8)Mn(2)(CO)(5) structure with a normal Mn-Mn single bond lies within ~6 kcal mol(-1) of this global minimum. The lowest energy structures of the more highly unsaturated C(10)H(8)Mn(2)(CO)(n) (n = 4, 3, 2) systems all have cis geometries and manganese-manganese bonds of various orders. The corresponding global minima are triplet cis-η(5),η(3)-C(10)H(8)Mn(2)(CO)(3)(η(2)-μ-CO) for the tetracarbonyl with a four-electron donor bridging carbonyl group, singlet cis-η(5),η(5)-C(10)H(8)Mn(2)(CO)(3) for the tricarbonyl, and triplet cis-η(6),η(4)-C(10)H(8)Mn(2)(CO)(η(2)-μ-CO) for the dicarbonyl. 相似文献
949.
The geometries and electronic properties of six polymers based on furo[3,4-b]pyridine-type heterocyclics were studied using
density functional theory (DFT) at the B3LYP/6-31G(d) level. Bond lengths, bond critical point (BCP) properties, nucleus-independent
chemical shift (NICS), and Wiberg bond indexes (WBIs) are analyzed and correlated with conduction properties. The changes
of bond length, BCP properties, NICS, and WBIs all show that the conjugational degree is increased with main chain extension.
The changes of NICS also show that the conjugation is stronger in the central section than in the outer section. And the HOMO–LUMO
energy gap (E
g) is decreased steadily upon chain elongation. The results suggest that the six polymers all have lower energy gaps (in the
range of 0.39–0.58 eV), which indicate that these proposed polymers are good candidates for the conductive materials. 相似文献
950.
Limin Han Guangbin Zhang Ning Zhu Ruijun Xie Quanling Suo Meihua Luo Linhong Weng 《Journal of Cluster Science》2010,21(4):789-801
Two novel bimetallic complexes, [Cr(CO)3(η
6-C6H5)–C≡C–C6H4–Fc] (Fc = C5H5FeC5H4] (1) and [Cr(CO)3(η
6-C6H5)–C ≡ C–Fc–C(CH3)2–Fc] (3), were synthesized by the Sonogashira coupling reaction. By using of (1) and (3) as ligands to react with Co2(CO)8, two others novel polymetallic complexes, [Cr(CO)3(η
6-C6H5){Co2(CO)6-η
2-μ
2-C≡C–}–C6H4–Fc] (2) and [Cr(CO)3(η
6-C6H5){Co2(CO)6-η
2-μ
2-C≡C–}Fc–C(CH3)2–Fc] (4) were obtained. Four carbonyl complexes were characterized by elemental analysis, FT-IR, NMR and MS. The molecular structures
of complexes (1), (2) and (4) were determined by single crystal X-ray diffraction. The interactions among the ferrocenyl,
Cr(CO)3 and Co2(CO)6-η
2-μ
2-C≡C– units were investigated by cyclic voltammetry. 相似文献