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41 results on '"Liu, Tiantian"'

20. Influence of layered skull modeling on the frequency sensitivity and target accuracy in simulations of transcranial current stimulation

Author

Wang, Heng, primary, Sun, Weiqian, additional, Zhang, Jianxu, additional, Yan, Zilong, additional, Wang, Chenyu, additional, Wang, Luyao, additional, Liu, Tiantian, additional, Li, Chunlin, additional, Chen, Duanduan, additional, Shintaro, Funahashi, additional, Wu, Jinglong, additional, and Yan, Tianyi, additional

Published
2021
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33. Solution-Mediated Phase Transformation of a Hydrate to its Anhydrous Form of Donepezil Hydrochloride

Author

Weibing Dong, Junbo Gong, Liu Tiantian, and Bochao Wang

Subjects
Chromatography, Chemistry, General Chemical Engineering, Enthalpy, Nucleation, Analytical chemistry, General Chemistry, Industrial and Manufacturing Engineering, law.invention, Differential scanning calorimetry, law, Anhydrous, Solubility, Crystallization, Hydrate, Dissolution
Abstract

The solubility of form I (hydrate) and form III (anhydrous form) of donepezil hydrochloride (DHCl) in methanol/isopropyl ether mixtures was determined at different temperatures by a synthetic method with laser monitoring observation. The experimental data were correlated with the modified Apelblat equation. Dissolution enthalpy and entropy were predicted by this equation. The mechanisms involved in solution-mediated transformation of a hydrate (form I) to its anhydrous form (form III) was investigated and characterized by in situ and offline measurement technologies, such as focused-beam reflectance measurement (FBRM), powder X-ray diffraction (PXRD), differential scanning calorimetry analysis (DSC), and moisture analyzer. The transformation involves nucleation of the metastable solid (form I), dissolution of the metastable solid, self-recognition of the molecular units to nucleate a more stable solid phase (form III), and growth of the stable phase. The results indicate that the rate of transformation increases with increasing temperature and driving force.

Published
2013

38. Enantiomerization and enantioselective bioaccumulation of diclofop-methyl in tubifex worms.

Author

Liu T and Duan X

Subjects
Animals, Stereoisomerism, Bioaccumulation, Water chemistry, Halogenated Diphenyl Ethers chemistry, Oligochaeta chemistry, Oligochaeta metabolism
Abstract

In this study, the hydrolysis of diclofop-methyl (DM) in aqueous system and the bioaccumulation of its main metabolite, Diclofop (DA), in the tubifex worms were investigated using enantioselective high-performance liquid chromatography. With the addition of tubifex, rapid hydrolysis was observed for DM. It is revealed that the hydrolysis of DM in the water and the accumulation of DA in the worms were both enantioselective. Meanwhile, either the hydrolysis amount or the levels of enantioselectivity were influenced by the tubifex. After incubated for 24 h, about 94.6% of the DM was hydrolyzed and the enantiomer fraction of metabolite (DA) deviated from 0.5 with R-DA significantly higher than S-DA. The enantiopure S-DM and R-DM and S-DA and R-DA were incubated, and enantiomerizations were detected between the two DM enantiomers with S-form inversing into R-form and vice versa. It was found that the S-DM exhibited a higher tendency to invert than the R-DM., (© 2023 Wiley Periodicals LLC.)

Published
2024
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39. Individual functional parcellation revealed compensation of dynamic limbic network organization in healthy ageing.

Author

Liu T, Shi Z, Zhang J, Wang K, Li Y, Pei G, Wang L, Wu J, and Yan T

Subjects
Humans, Magnetic Resonance Imaging methods, Neural Pathways diagnostic imaging, Brain diagnostic imaging, Brain Mapping, Healthy Aging
Abstract

Using group-level functional parcellations and constant-length sliding window analysis, dynamic functional connectivity studies have revealed network-specific impairment and compensation in healthy ageing. However, functional parcellation and dynamic time windows vary across individuals; individual-level ageing-related brain dynamics are uncertain. Here, we performed individual parcellation and individual-length sliding window clustering to characterize ageing-related dynamic network changes. Healthy participants (n = 637, 18-88 years) from the Cambridge Centre for Ageing and Neuroscience dataset were included. An individual seven-network parcellation, varied from group-level parcellation, was mapped for each participant. For each network, strong and weak cognitive brain states were revealed by individual-length sliding window clustering and canonical correlation analysis. The results showed negative linear correlations between age and change ratios of sizes in the default mode, frontoparietal, and salience networks and a positive linear correlation between age and change ratios of size in the limbic network (LN). With increasing age, the occurrence and dwell time of strong states showed inverted U-shaped patterns or a linear decreasing pattern in most networks but showed a linear increasing pattern in the LN. Overall, this study reveals a compensative increase in emotional networks (i.e., the LN) and a decline in cognitive and primary sensory networks in healthy ageing. These findings may provide insights into network-specific and individual-level targeting during neuromodulation in ageing and ageing-related diseases., (© 2022 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.)

Published
2023
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40. TERT promoter mutation as an early genetic event activating telomerase in follicular thyroid adenoma (FTA) and atypical FTA.

Author

Wang N, Liu T, Sofiadis A, Juhlin CC, Zedenius J, Höög A, Larsson C, and Xu D

Subjects
Adult, Aged, Cysteine, Enzyme Activation, Female, GTP Phosphohydrolases genetics, Humans, Male, Membrane Proteins genetics, Middle Aged, Promoter Regions, Genetic genetics, Real-Time Polymerase Chain Reaction, Telomerase genetics, Threonine, Adenoma enzymology, Adenoma genetics, Mutation, Telomerase metabolism, Thyroid Neoplasms enzymology, Thyroid Neoplasms genetics
Abstract

Background: The telomerase reverse transcriptase (TERT) promoter mutations C228T and C250T have been found in many malignancies, including in thyroid carcinomas. However, it is unclear how early these mutations occur in thyroid tumorigenesis., Methods: The study included primary tumors from 58 patients initially diagnosed with follicular thyroid adenoma (FTA), a benign entity, 18 with atypical FTA (AFTA) having an uncertain malignant potential, and 52 with follicular thyroid carcinoma (FTC). Sanger sequencing was used to investigate the mutational status of the TERT promoter. Telomere length and TERT messenger RNA (mRNA) expression were determined using quantitative polymerase chain reaction (PCR). Telomerase activity was assessed using a Telomerase PCR enzyme-linked immunosorbent assay kit., Results: The C228T mutation was identified in 1 of 58 FTA (2%) and 3 of 18 AFTA (17%) samples. These 4 tumors all expressed TERT mRNA and telomerase activity, whereas the majority of C228T-negative adenomas lacked TERT expression (C228T versus wild-type, P = .008). The C228T mutation was associated with NRAS gene mutations (P = .016). The patient with C228T-mutated FTA later developed a scar recurrence and died of FTC, whereas none of the remaining 57 patients with FTA had recurrence. No recurrence occurred in 3 patients with AFTA who carried C228T during the follow-up period (36-285 months). Nine of the 52 FTCs (17%) exhibited the TERT mutation (8 of 9 C228T and 1 of 9 C250T), and the presence of the mutation was associated with shorter patient survival., Conclusions: TERT promoter mutations may occur as an early genetic event in thyroid follicular tumors that have not developed malignant features on routine histopathological workup., (© 2014 American Cancer Society.)

Published
2014
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41. Enantioselective bioaccumulation and dissipation of soil-associated metalaxyl enantiomers in tubifex.

Author

Di S, Liu T, Lu Y, Zhou Z, and Diao J

Subjects
Alanine chemistry, Animals, Chromatography, High Pressure Liquid, Fungicides, Industrial chemistry, Molecular Structure, Stereoisomerism, Water chemistry, Alanine analogs & derivatives, Oligochaeta chemistry, Soil Pollutants chemistry
Abstract

Many pesticides are chiral compounds and stereochemistry is an important factor for any reaction of chiral structures in biological systems. In this study, experiment about bioaccumulation of the two metalaxyl enantiomers in Tubifex (Oligochaeta, Tubificida) was conducted in laboratory aquatic ecosystems. Terrestrial soil spiked with two dose levels of metalaxyl was employed as the artificial bottom substrate. A method of determination of metalaxyl enantiomers in tubifex tissue, soil and overlying water were developed by HPLC. During a 14-day exposure, concentrations of metalaxyl in tubifex increased with the of soil concentration, however, the enantioselective bioaccumulation was only detected at high-dose exposure group, with the preferential accumulation of (-)-(R)-metalaxyl. The bioturbation activity of tubifex decreased water clarity and released soil-associated metalaxyl to overlying water. In those experiments where tubifex was exposed to metalaxyl from soil, pore water and overlying water, each route contributed to the total body burden, and our results indicated the pore water and soil are the primary exposure routes for high-dose exposure concentration treatment., (© 2013 Wiley Periodicals, Inc.)

Published
2014
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