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1.
Planta ; 259(3): 64, 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38329576

RESUMO

MAIN CONCLUSION: The loss of TaMYB305 function down-regulated the expression of jasmonic acid synthesis pathway genes, which may disturb the jasmonic acid synthesis, resulting in abnormal pollen development and reduced fertility. The MYB family, as one of the largest transcription factor families found in plants, regulates plant development, especially the development of anthers. Therefore, it is important to identify potential MYB transcription factors associated with pollen development and to study its role in pollen development. Here, the transcripts of an R2R3 MYB gene TaMYB305 from KTM3315A, a thermo-sensitive cytoplasmic male-sterility line with Aegilops kotschyi cytoplasm (K-TCMS) wheat, was isolated. Quantitative real-time PCR (qRT-PCR) and promoter activity analysis revealed that TaMYB305 was primarily expressed in anthers. The TaMYB305 protein was localized in the nucleus, as determined by subcellular localization analysis. Our data demonstrated that silencing of TaMYB305 was related to abnormal development of stamen, including anther indehiscence and pollen abortion in KAM3315A plants. In addition, TaMYB305-silenced plants exhibited alterations in the transcriptional levels of genes involved in the synthesis of jasmonic acid (JA), indicating that TaMYB305 may regulate the expression of genes related to JA synthesis and play an important role during anther and pollen development of KTM3315A. These results provide novel insight into the function and molecular mechanism of R2R3-MYB genes in pollen development.


Assuntos
Aegilops , Infertilidade , Oxilipinas , Ciclopentanos , Citoplasma/genética , Genes myb , Pólen/genética , Triticum
2.
Plant Foods Hum Nutr ; 78(3): 590-596, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37566209

RESUMO

This study presents the metabolic profiling of potato powders obtained through various processing procedures and commercially available potato powders. The metabolic fingerprinting was conducted using 1H NMR-based metabolomics coupled with machine learning projections. The results indicate hot air-dried potatoes have higher fumarate, glucose, malate, asparagine, choline, gamma aminobutyric acid (GABA), alanine, lactate, threonine, and fatty acids. In comparison, steam-cooked potatoes have higher levels of phenylalanine, sucrose, proline, citrate, glutamate, and valine. Moreover, the contents of metabolites in processed potatoes in this study were higher than those found in commercial potato powders, regardless of the drying or cooking methods used. The results indicate that a new processing technique may be developed to improve the nutritional value of potatoes.


Assuntos
Solanum tuberosum , Solanum tuberosum/química , Pós , Quimiometria , Espectroscopia de Ressonância Magnética/métodos , Glucose , Metabolômica/métodos
3.
Molecules ; 27(15)2022 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-35897914

RESUMO

Allobetulin is structurally similar tobetulinic acid, inducing the apoptosis of cancer cells with low toxicity. However, both of them exhibited weak antiproliferation against several tumor cell lines. Therefore, the new series of allobetulon/allobetulin-nucleoside conjugates 9a-10i were designed and synthesized for potency improvement. Compounds 9b, 9e, 10a, and 10d showed promising antiproliferative activity toward six tested cell lines, compared to zidovudine, cisplatin, and oxaliplatin based on their antitumor activity results. Among them, compound 10d exhibited much more potent antiproliferative activity against SMMC-7721, HepG2, MNK-45, SW620, and A549 human cancer cell lines than cisplatin and oxaliplatin. In the preliminary study for the mechanism of action, compound 10d induced cell apoptosis and autophagy in SMMC cells, resulting in antiproliferation and G0/G1 cell cycle arrest by regulating protein expression levels of Bax, Bcl-2, and LC3. Consequently, the nucleoside-conjugated allobetulin (10d) evidenced that nucleoside substitution was a viable strategy to improve allobetulin/allobetulon's antitumor activity based on our present study.


Assuntos
Antineoplásicos , Cisplatino , Antineoplásicos/farmacologia , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Cisplatino/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Estrutura Molecular , Nucleosídeos/farmacologia , Oxaliplatina/farmacologia , Relação Estrutura-Atividade
4.
Micromachines (Basel) ; 15(2)2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38398910

RESUMO

Microwave components and devices are essential elements of many key communication, sensing, and monitoring systems [...].

5.
Eur J Med Chem ; 276: 116635, 2024 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-38964258

RESUMO

Fifteen betulonic/betulinic acid conjugated with nucleoside derivatives were synthesized to enhance antitumor potency and water solubility. Among these, the methylated betulonic acid-azidothymidine compound (8c) exhibited a broad-spectrum of antitumor activity against three tested tumor cell lines, including SMMC-7721 (IC50 = 5.02 µM), KYSE-150 (IC50 = 5.68 µM), and SW620 (IC50 = 4.61 µM) and along with lower toxicity (TC50 > 100 µM) estimated by zebrafish embryos assay. Compared to betulinic acid (<0.05 µg/mL), compound 8c showed approximately 40-fold higher water solubility (1.98 µg/mL). In SMMC-7721 cells, compound 8c induced autophagy and apoptosis as its concentration increased. Transcriptomic sequencing analysis was used to understand the potential impacts of the underlying mechanism of 8c on SMMC-7721 cells. Transcriptomic studies indicated that compound 8c could activate autophagy by inhibiting the PI3K/AKT pathway in SMMC-7721 cells. Furthermore, in the xenograft mice study, compound 8c significantly slowed down the tumor growth, as potent as paclitaxel treated group. In conclusion, methylated betulonic acid-azidothymidine compound (8c) not only increases water solubility, but also enhances the potency against hepatocellular carcinoma cells by inducing autophagy and apoptosis, and suppressing the PI3K/Akt/mTOR signaling pathway.

6.
Mater Today Bio ; 22: 100780, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37680585

RESUMO

Glioma is recognized as the most common and aggressive primary brain tumor in adults. Owing to the occurrence of drug resistance and the failure of drug to penetrate the blood-brain barrier (BBB), there is no effective strategy for the treatment of glioma. The main objective of this study was to develop a biomimetic glioma C6 cell membrane (C6M) derived nanovesicles (DOX-FN/C6M-NVs) loaded with doxorubicin (DOX) and ultra-small Fe nanoparticles (FN) for accomplishing the effective brain tumor-targeted delivery of DOX and improving anti-cancer efficacy via inducing collaborative apoptosis and ferroptosis. The findings revealed that employing C6M-NVs as a carrier significantly improved the therapeutic efficacy by enabling evasion of immune surveillance, facilitating targeted drug delivery to tumor sites, and minimizing cardiotoxicity and adverse effects associated with DOX. DOX-FN/C6M-NVs exhibited more potent anti-tumor effects as compared with free DOX by promoting DOX-mediated apoptosis and accelerating ferroptosis via the mediation of FN. This study suggested that DOX-FN/C6M-NVs as the potential inducer of ferroptosis and apoptosis conferred effective tumor suppression in the treatment of glioma.

7.
Environ Sci Pollut Res Int ; 29(30): 46357-46370, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35169945

RESUMO

Exploring and utilizing the agronomic potential of deep-underground is one of the ways to cope with the challenges of sudden environmental change on agriculture. Understanding the effects of environmental stresses on the morphological and physiological indicators of crop seeds after their storage deep-underground is crucial to developing and implementing strategies for agriculture in the deep-underground space. In this study, we stored canola seeds in tunnels with horizontal depths of 0, 240, 690, and 1410 m in a gold mine. Seeds in envelopes were retrieved at 42, 66, 90, and 227 days of storage, whereas seeds in sealed packages were retrieved at 66 and 227 days of storage. The germination tests were conducted to investigate the effects of storage depth, duration, and packing method on stored and non-stored seeds. Results showed that increased depth and duration reduced seed germination rate, with the germination and vigor indexes also descending to varying degrees. Increased hypocotyl length and biomass accumulation suggested that deep-underground environment had a more significant compensatory effect on seed germination. For all indicators, the performance of seeds sealed in packages was superior to those stored in envelopes. Regression analysis showed that it was difficult to obtain the optimal value of each indicator simultaneously. The successful germination experiment foreshadowed the possibilities of deep-underground agriculture in the future.


Assuntos
Brassica napus , Germinação , Agricultura , Brassica napus/fisiologia , Ouro/farmacologia , Sementes
8.
Plant Sci ; 323: 111377, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35820549

RESUMO

The thermo-sensitive cytoplasmic male-sterility line with Aegilops kotschyi cytoplasm (K-TCMS) is completely male sterile under low temperature (< 18 ℃) during Zadoks growth stages 45-52, whereas its fertility can be restored under hot temperature (≥ 20 ℃). The K-TCMS line may facilitate hybrid breeding and hybrid wheat production. Therefore, to elucidate the molecular mechanisms of its male sterility/fertility conversion, we conducted the association analysis of proteins and transcript expression to screen fertility related genes using RNA-seq, iTRAQ, and PRM-based assay. A gene encoding expansin protein in wheat, TaEXPB5, was isolated in K-TCMS line KTM3315A, which upregulated expression in the fertility anthers. Subcellular localization analysis suggested that TaEXPB5 protein localized to nucleus and cell wall. The silencing of TaEXPB5 displayed pollen abortion and the declination of fertility. Further, cytological investigation indicated that the silencing of TaEXPB5 induced the early degradation of tapetum and abnormal development of pollen wall. These results implied that TaEXPB5 may be essential for anther or pollen development and male fertility of KTM3315A. These findings provide a novel insight into molecular mechanism of fertility conversion for thermo-sensitive cytoplasmic male-sterility wheat, and contribute to the molecular breeding of hybrid wheat in the future.


Assuntos
Aegilops , Infertilidade Masculina , Aegilops/genética , Citoplasma/genética , Regulação da Expressão Gênica de Plantas , Humanos , Masculino , Melhoramento Vegetal , Infertilidade das Plantas/genética , Pólen/genética , Triticum/genética
9.
Curr Med Sci ; 42(4): 692-701, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35727418

RESUMO

OBJECTIVE: Cholesteryl esters (CEs) are composed of various fatty acyl chains attached to the hydroxyl groups of cholesterol, and abnormalities in their metabolism are related to many diseases. This study aimed to develop an ultrahigh-performance liquid chromatography-quadrupole exactive mass spectrometry (UPLC-Q-Exactive MS) method to identify the CEs in plasma. METHODS: First, the MS fragmentation patterns were investigated using seven commercial CE standards. Then, the CEs in plasma were characterized through the accurate mass data of precursor ions and characteristic product ions. A strategy of step-by-step m/z scans in a narrow range was proposed to identify more trace CEs by the full-scan data-dependent MS/MS (ddMS2) mode. RESULTS: A total of 50 CE species consisting of 55 regioisomers were identified in human plasma. Among them, two species were reported for the first time. CONCLUSION: This study is the most comprehensive identification of CE species in human plasma to date. These results will contribute to the in-depth profiling of CEs in human plasma and provide guidance for animal model selection when studying lipid-related diseases.


Assuntos
Ésteres do Colesterol , Espectrometria de Massas em Tandem , Animais , Ésteres do Colesterol/análise , Cromatografia Líquida/métodos , Humanos , Íons , Roedores , Espectrometria de Massas em Tandem/métodos
10.
Materials (Basel) ; 14(19)2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34640227

RESUMO

This paper presents a new modification of the nanostructure of CaSO4·2H2O crystals containing nanopores. This nanoporous structure was achieved in phosphogypsum samples that were modified by sodium carbonate and alum. The effects of sodium carbonate and alum on the properties of phosphogypsum were studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods were used to explore the micro-mechanism of the composite system. Subsequently, molecular dynamics simulations were used to study the nanopore structures of the modified CaSO4·2H2O. The results show that the addition of sodium carbonate and alum reduced the absolute dry density by 23.1% compared with the original phosphogypsum sample, with a bending strength of 2.1 MPa and compressive strength of 7.5 MPa. In addition, new hydration products, sodium sulfate and sodium aluminum sulfate, were formed in the sample doped with sodium carbonate and alum. A new nanostructure of CaSO4·2H2O crystal containing nanopores was formed. Molecular simulations show that the hydration products were responsible for the surface nanopore formation, which was the main factor leading to an increase in mechanical strength. The presented nanopore structure yields lightweight and high strength properties in the modified phosphogypsum.

11.
Artigo em Inglês | MEDLINE | ID: mdl-33857888

RESUMO

Sphingolipids (SLs) are endogenously bioactive molecules with diverse structures, and its metabolic disorders are involved in the progression of many diseases. In this study, an ultra-performance liquid chromatography quadrupole exactive mass spectrometry (UPLC-Q-Exactive-MS) method was established to comprehensively profile SLs in plasma. First, the fragment patterns of SL standards of each subclass were investigated. Then, the SL species in plasma were characterized based on the fragmentation rules. Finally, a total of 144 endogenous SL species consisting of 216 regioisomers were identified in plasma of human, golden hamster and C57BL/6 mice, which was the most comprehensive identification for SLs in plasma. In addition to the known species, 19 SL species that have never been reported were also identified. The profile of SLs in plasma of human and two rodent species was compared subsequently. It was worth noting that a total of 9 SL molecular species consisting of 11 regioisomers with low abundance were successfully identified in human plasma through comparison among species. Those findings contribute to a deeper understanding of SLs in human plasma and provide scientific basis for the selection of animal model. The established profile of SLs in plasma could be used for screening of lipid biomarkers of various diseases.

12.
Pharmaceuticals (Basel) ; 14(2)2021 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-33572935

RESUMO

Cisplatin and its analogues are widely used as chemotherapeutic agents in clinical practice. After being intravenously administrated, a substantial amount of platinum will bind with proteins in the blood. This binding is vital for the transport, distribution, and metabolism of drugs; however, toxicity can also occur from the irreversible binding between biologically active proteins and platinum drugs. Therefore, it is very important to study the protein-binding behavior of platinum drugs in blood. This review summarizes mass spectrometry-based strategies to identify and quantitate the proteins binding with platinum anticancer drugs in blood, such as offline high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC-ICP-MS) combined with electrospray ionization mass spectrometry (ESI-MS/MS) and multidimensional LC-ESI-MS/MS. The identification of in vivo targets in blood cannot be accomplished without first studying the protein-binding behavior of platinum drugs in vitro; therefore, relevant studies are also summarized. This knowledge will further our understanding of the pharmacokinetics and toxicity of platinum anticancer drugs, and it will be beneficial for the rational design of metal-based anticancer drugs.

13.
Chemosphere ; 208: 108-116, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29864701

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) not only present a risk to human health when released into the air, but also can be precursors to form particulate matter (PM) during sewage sludge pyrolysis. In this study, 16 EPA PAHs in PM (ΣPAHPM) during sewage sludge pyrolysis were investigated with increasing temperature (200oC-1000 °C) and holding time under different operation conditions [inert gas flow rate (IGFR) (200-800 mL/min) and heating rate (5-20 °C/min)]. ΣPAHPM varied with temperature, IGFR, and heating rate, and ranged from 597 (±41) µg/g to 3240 (±868) µg/g. ΣPAHPM decreased with increasing IGFR but increased with rapid heating rate. Among PAHs species in PM, naphthalene (Nap) was commonly detected at low temperature ranges in all tested conditions. Chrysene (CHR), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1,2,3-cd] pyrene (IND), and benzo[g,h,i]perylene (BghiP) in PM became abundant at high temperature with a low IGFR. At high temperature ranges with high volatile conditions (rapid heating rate and low IGFR), PAH formation and growth reactions were considerable, resulting in the formation of heavy PAHs in PM.


Assuntos
Incineração , Material Particulado , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/química , Esgotos/química , Humanos , Eliminação de Resíduos
14.
ACS Appl Mater Interfaces ; 9(33): 27745-27753, 2017 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-28759714

RESUMO

Excellent self-healability and renewability are crucial for the development of wearable/flexible energy-storage devices aiming for advanced personalized electronics. However, realizing low-temperature self-healing and harmless regeneration remains a big challenge for existing wearable/flexible energy-storage devices, which is fundamentally limited by conventional polymeric electrolytes that are intrinsically neither cryo-healable nor renewable. Here, we rationally design a multifunctional polymer electrolyte on the basis of the copolymer of vinylimidazole and hydroxypropyl acrylate, which exhibits all features solving the above-mentioned limitations. A supercapacitor comprising the electrolyte autonomously restores its electrochemical behaviors at temperatures ranging from 25 to -15 °C after multiple mechanical breakings. Interestingly, it is even able to regenerate for 5 cycles through a simple wetting process in the case of malfunction, while maintaining its capacitive properties and excellent self-healability. Our investigation provides a novel insight into designing smart and sustainable energy-storage devices that might be applied to intelligent apparel, electronic skin or flexible robot, and so on.

15.
Mol Cancer Res ; 15(12): 1644-1655, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28814453

RESUMO

Clinical observations have identified an association between psychologic stress and cancer relapse, suggesting that the sympathetic nervous system/norepinephrine (NE) plays a role in reactivation of dormant disseminated tumor cells (DTC) in the bone marrow niche. Here, the mechanism by which NE regulates prostate cancer DTCs in the marrow is explored. NE directly stimulated prostate cancer cell proliferation through ß2-adrenergic receptors (ADRB2). NE also altered prostate cancer proliferation in the marrow niche by indirectly downregulating the secretion of the dormancy inducing molecule growth arrest specific-6 (GAS6) expressed by osteoblasts. These observations were confirmed in cocultures of prostate cancer cells expressing the fluorescent ubiquitination-based cell-cycle reporters (FUCCI) and osteoblasts isolated from GAS6-deficient (GAS6-/-) animals. A novel ex vivo model system, using femurs harvested from GAS6+/+ or GAS6-/- mice, was used to confirm these results. As in coculture, when prostate cancer cells were injected into the marrow cavities of GAS6+/+ femurs, NE altered the prostate cancer cell cycle. However, NE had less of an impact on prostate cancer cells in femur explants isolated from GAS6-/- mice. Together, this study demonstrates that NE reactivates prostate cancer cell cycling through both a direct action on prostate cancer cells and indirectly on adjacent niche cells.Implications: Identification of mechanisms that target DTCs may provide novel therapeutic approaches to prevent or treat cancer metastases more effectively. Mol Cancer Res; 15(12); 1644-55. ©2017 AACR.


Assuntos
Peptídeos e Proteínas de Sinalização Intercelular/genética , Norepinefrina/genética , Neoplasias da Próstata/genética , Receptores Adrenérgicos beta 3/genética , Animais , Medula Óssea/metabolismo , Medula Óssea/patologia , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Camundongos , Camundongos Knockout , Norepinefrina/metabolismo , Osteoblastos/metabolismo , Osteoblastos/patologia , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Recidiva , Estresse Psicológico/genética , Sistema Nervoso Simpático/metabolismo , Sistema Nervoso Simpático/patologia
18.
Cancer Res ; 70(2): 471-80, 2010 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-20068185

RESUMO

Tumor and stromal interactions in the tumor microenvironment are critical for oncogenesis and cancer progression. Our understanding of the molecular events by which reactive stromal fibroblasts-myofibroblast or cancer-associated fibroblasts (CAF)-affect the growth and invasion of prostate cancer remains unclear. Laser capture microdissection and cDNA microarray analysis of CAFs in prostate tumors revealed strong upregulation of phosphoglycerate kinase-1 (PGK1), an ATP-generating glycolytic enzyme that forms part of the glycolytic pathway and is directly involved in CXCL12-CXCR4 signaling. Normal fibroblasts overexpressing PGK1 resembled myofibroblasts in their expression of smooth muscle alpha-actin, vimentin, and high levels of CXCL12. These cells also displayed a higher proliferative index and the capability to contribute to prostate tumor cell invasion in vitro, possibly through expression of MMP-2 and MMP-3 and activation of the AKT and ERK pathways. Coimplantation of PGK1-overexpressing fibroblasts with prostate tumor cells promoted tumor cell growth in vivo. Collectively, these observations suggest that PGK1 helps support the interactions between cancer and its microenvironment.


Assuntos
Fosfoglicerato Quinase/biossíntese , Neoplasias da Próstata/enzimologia , Actinas/metabolismo , Animais , Processos de Crescimento Celular/fisiologia , Linhagem Celular Tumoral , Quimiocina CXCL12/biossíntese , Quimiocina CXCL12/metabolismo , Fibroblastos/enzimologia , Fibroblastos/metabolismo , Fibroblastos/patologia , Humanos , Imuno-Histoquímica , Masculino , Camundongos , Camundongos SCID , Invasividade Neoplásica , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Células Estromais/enzimologia , Células Estromais/metabolismo , Células Estromais/patologia , Regulação para Cima
19.
Cancer Res ; 68(24): 10367-76, 2008 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-19074906

RESUMO

Previous studies show that the chemokine CXCL16 and its receptor CXCR6 are likely to contribute to prostate cancer (PCa). In this investigation, the role of the CXCR6 receptor in PCa was further explored. CXCR6 protein expression was examined using high-density tissue microarrays and immunohistochemistry. Expression of CXCR6 showed strong epithelial staining that correlated with Gleason score. In vitro and in vivo studies in PCa cell lines suggested that alterations in CXCR6 expression were associated with invasive activities and tumor growth. In addition, CXCR6 expression was able to regulate expression of the proangiogenic factors interleukin (IL)-8 or vascular endothelial growth factor (VEGF), which are likely to participate in the regulation of tumor angiogenesis. Finally, we found that CXCL16 signaling induced the activation of Akt, p70S6K, and eukaryotic initiation factor 4E binding protein 1 included in mammalian target of rapamycin (mTOR) pathways, which are located downstream of Akt. Furthermore, rapamycin not only drastically inhibited CXCL16-induced PCa cell invasion and growth but reduced secretion of IL-8 or VEGF levels and inhibited expression of other CXCR6 targets including CD44 and matrix metalloproteinase 3 in PCa cells. Together, our data shows for the first time that the CXCR6/AKT/mTOR pathway plays a central role in the development of PCa. Blocking the CXCR6/AKT/mTOR signaling pathway may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for PCa.


Assuntos
Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Proteínas Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de Quimiocinas/biossíntese , Receptores Virais/biossíntese , Animais , Linhagem Celular Tumoral , Quimiocina CXCL16 , Quimiocinas CXC/metabolismo , Citocinas/metabolismo , Progressão da Doença , Humanos , Masculino , Camundongos , Camundongos SCID , Invasividade Neoplásica , Neovascularização Patológica/metabolismo , Neovascularização Patológica/patologia , Neoplasias da Próstata/irrigação sanguínea , Receptores CXCR6 , Receptores Depuradores/metabolismo , Proteínas Quinases S6 Ribossômicas/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR
20.
J Am Chem Soc ; 127(25): 9255-9, 2005 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-15969606

RESUMO

This work investigated the nanoconfinement effect on the molecular dynamics and phase transition of confined benzene inside titanate nanotubes with a uniform inner diameter of approximately 5.3 nm. For 13C-enriched organics, the 13C nuclear spin-spin relaxation was demonstrated as a sensitive tool to differentiate molecular translational motion and reorientation and, thus, was shown to be advantageous over the commonly employed 1H and 2H NMR for studying complex phase diagram, specifically, for separating the phase behavior of translational motion and the phase behavior of molecular reorientation. In such an approach, the melting of translational motion of confined benzene was explicitly observed to take place in a broad temperature range below the bulk melting temperature. The abrupt change of the 13C nuclear spin-spin relaxation time of the confined liquid benzene at about 260 K suggested that nanoconfinement induced two topologically distinct liquid phases.


Assuntos
Benzeno/química , Espectroscopia de Ressonância Magnética/métodos , Nanotubos/química , Titânio/química , Isótopos de Carbono , Hidróxido de Sódio/química , Temperatura
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