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1.
Nat Commun ; 10(1): 3033, 2019 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-31292442

RESUMO

Fiber nonlinearity is one of the major limitations to the achievable capacity in long distance fiber optic transmission systems. Nonlinear impairments are determined by the signal pattern and the transmission system parameters. Deterministic algorithms based on approximating the nonlinear Schrodinger equation through digital back propagation, or a single step approach based on perturbation methods have been demonstrated, however, their implementation demands excessive signal processing resources, and accurate knowledge of the transmission system. A completely different approach uses machine learning algorithms to learn from the received data itself to figure out the nonlinear impairment. In this work, a single-step, system agnostic nonlinearity compensation algorithm based on a neural network is proposed to pre-distort symbols at transmitter side to demonstrate ~0.6 dB Q improvement after 2800 km standard single-mode fiber transmission using 32 Gbaud signal. Without prior knowledge of the transmission system, the neural network tensor weights are constructed from training data thanks to the intra-channel cross-phase modulation and intra-channel four-wave mixing triplets used as input features.

2.
Cancer Sci ; 110(8): 2396-2407, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31148360

RESUMO

The tumor microenvironment offers favorable conditions for tumor progression, and activated fibroblasts, known as cancer-associated fibroblasts, play a pivotal role. TP53-deficient cancer cells are known to induce strong fibroblast activation. We aimed to elucidate the oncogenic role of exosomes derived from TP53-deficient colon cancer cells in fibroblast proliferation and tumor growth. Cancer cell-derived exosomes (CDEs) were isolated from the conditioned media of cancer cells using a sequential ultracentrifugation method. The effects of exosomes on tumor growth were evaluated using human cell lines (TP53-WT colon cancer, HCT116; TP53-mutant colon cancer, HT29; and fibroblasts, CCD-18Co and WI-38) and an immune-deficient nude mouse xenograft model. HCT116 (HCT116sh p53 ) cells deficient in TP53 accelerated cocultured fibroblast proliferation compared to TP53-WT HCT116 (HCT116sh control ) cells in vitro. Exosomes from HCT116sh p53 cells suppressed TP53 expression of fibroblasts and promoted their proliferation. Xenografts of HCT116sh p53 cells grew significantly faster than those of HCT116sh control cells in the presence of co-injected fibroblasts, but this difference was diminished by CDE inhibition. Microarray analysis identified upregulation of several microRNAs (miR-1249-5p, miR-6737-5p, and miR-6819-5p) in TP53-deficient CDEs, which were functionally proven to suppress TP53 expression in fibroblasts. Exosomes derived from TP53-mutant HT29 cells also suppressed TP53 expression in fibroblasts and accelerated their growth. The proliferative effect of HT29 on cocultured fibroblasts was diminished by inhibition of these miRNAs in fibroblasts. Our results suggest that CDEs play a pivotal role in tumor progression by fibroblast modification. Cancer cell-derived exosomes might, therefore, represent a novel therapeutic target in colon cancer.


Assuntos
Neoplasias do Colo/genética , Exossomos/genética , MicroRNAs/genética , Proteína Supressora de Tumor p53/genética , Animais , Fibroblastos Associados a Câncer/patologia , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/genética , Neoplasias do Colo/patologia , Progressão da Doença , Regulação Neoplásica da Expressão Gênica/genética , Células HCT116 , Células HT29 , Xenoenxertos/patologia , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Transdução de Sinais/genética , Microambiente Tumoral/genética , Regulação para Cima/genética
4.
Tissue Eng Part A ; 19(1-2): 24-9, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22839964

RESUMO

Regenerative therapy using stem cells is a promising approach for the treatment of stroke. Recently, we reported that dental pulp stem cells (DPSC) ameliorated ischemic tissue injury in the rat brain and accelerated functional recovery after middle cerebral artery occlusion (MCAO). In this study, we investigated the effects of stem cells from human exfoliated deciduous tooth (SHED)-derived conditioned medium (SHED-CM) on permanent MCAO (pMCAO). Adult male Sprague-Dawley rats were subjected to pMCAO. SHED-CM were then administered intranasally, and the motor function and infarct volume were evaluated. Neurogenesis and vasculogenesis were determined using immunochemical markers. The SHED-CM group had more positive signals than the Dulbecco's modified Eagle's medium group, with doublecortin (DCX), neurofilament H, neuronal nuclei, and rat endothelial cell antigen observed in the peri-infarct area. Migration of neuronal progenitor cells (NPC) with DCX from the subventricular zone to the peri-infarct area was observed on days 6 and 16, with migration on day 6 being the most prominent. In conclusion, SHED-CM promoted the migration and differentiation of endogenous NPC, induced vasculogenesis, and ameliorated ischemic brain injury after pMCAO as well as transplantation of DPSC.


Assuntos
Isquemia Encefálica/patologia , Isquemia Encefálica/cirurgia , Transplante de Células-Tronco/métodos , Dente Decíduo/citologia , Dente Decíduo/transplante , Animais , Humanos , Masculino , Ratos , Ratos Sprague-Dawley , Recuperação de Função Fisiológica , Resultado do Tratamento
5.
Phys Chem Chem Phys ; 13(40): 18031-7, 2011 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-21922093

RESUMO

Artificial photosynthesis is one of the chemists' dreams and the separation of charges with long lives is fundamental for achieving artificial photosynthesis. In actual photosynthesis, Z-scheme excitation separates electronic charge with high efficiency using solar light. Here we report that photo-excitation in Cr-tetraphenylporphyrin chroride (Cr-TPPCl)/Zr doped KTaO(3) (KTa(Zr)O(3)) is analogous to the Z-scheme in photosynthesis, and that we achieve complete charge separation at room temperature. Photovoltaic decay and transient fluorescence spectra measurements showed that the photo-excited charge in KTa(Zr)O(3) transferred to the HOMO of Cr-TPPCl within a few hundred pico-seconds on charge transfer. In contrast, the reduced state of the Cr-TPPCl species that was formed by the electronic injection from KTa(Zr)O(3) was observed for more than 0.5 s at room temperature in the transient decay of the absorption spectra change after the initial excitation of KTa(Zr)O(3). The formed reduced state of Cr-TPPCl was highly stable and was detected by static ESR measurements.


Assuntos
Óxidos/química , Fotossíntese , Porfirinas/química , Potássio/química , Tantálio/química , Água/química , Catálise , Cromo/química , Transporte de Elétrons , Zircônio/química
6.
Chemistry ; 15(46): 12862-70, 2009 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-19834939

RESUMO

The mechanism of photocatalytic splitting of H(2)O into H(2) and O(2) on Pt/KTa(Zr)O(3) modified with various porphyrinoids was investigated. The photocatalytic activity of KTaO(3) catalysts is improved by dye modification. Cyanocobalamin (vitamin B(12)) is the most effective for improving water-splitting activity, and the formation rates of H(2) and O(2) achieved values of 575 and 280 micromol g(cat.) (-1) h(-1), respectively. X-ray photoelectron spectroscopy spectra of KTa(Zr)O(3) photocatalysts showed that Pt loaded onto dye-modified KTaO(3) was slightly oxidized and had low catalytic activity for the H(2) oxidation reaction. Photoluminescence (PL) spectra of KTaO(3) catalysts suggested that excitation energy was transferred between KTaO(3), tetraphenylporphyrinatochromium(III) (Cr-TPP), and the Pt cocatalyst. The wavelength dependence of the activity of dye-modified KTa(Zr)O(3) photocatalysts indicated that excitation of both KTa(Zr)O(3) and the dye was essential for achieving increased photocatalytic activity. This result suggests that two-step excitation occurred in the dye-modified KTa(Zr)O(3) photocatalysts. Because the lifetime of the charge-separated state increased, this study reveals that modification with porphyrinoids is effective for increasing water-splitting activity.

7.
J Colloid Interface Sci ; 332(1): 136-44, 2009 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-19159895

RESUMO

SF(6) was selectively hydrolyzed to SO(3) over rare earth (RE) phosphates above 800 K. CePO(4) was the most active catalyst, followed by GdPO(4), YbPO(4), DyPO(4), ErPO(4), SmPO(4), PrPO(4), TbPO(4), NdPO(4), and LaPO(4). The middle RE phosphates were found to be more active than the light RE phosphates, but the reason for the high activity of CePO(4), which belongs to the light RE group, is not clear. The catalytic activity was independent of the specific surface area (SSA), acid amount, and acid concentration of the catalysts. RE phosphates were single-phase, and a broad inversely proportional relation was observed between the crystallite size and SSA, except in the case of CePO(4). The combination of highly active AlPO(4) and CePO(4) creates synergetic effects in the catalytic activity and SO(3) selectivity over all ranges of composition. Binary catalysts were a mixture of small crystalline AlPO(4) and CePO(4). The addition of Ce promoted the crystallization of AlPO(4), which was controlled to about 10 nm at 10-50% Ce content. The turnover frequency for SF(6) decomposition was proportional to the surface concentration of hydroxyls of binary catalysts. Therefore, synergy effects may come from the number of hydroxyl (OH) pair sites on which a bidentate intermediate of hydrolysis of SF(6) may be formed by the moderate crystallization of AlPO(4). The addition of Ce, Pr, or Y to AlPO(4) brings about a small promotion effect for SF(6) decomposition, but the addition of La, Nd > Gd > Yb diminishes the activity. The addition of Gd, Pr, or Nd greatly improved the SO(3) selectivity. A linear relationship between catalytic activity and the concentration of surface hydroxyls of the catalysts supports a reaction mechanism in which two F atoms of an SF(6) molecule interact with two surface hydroxyls to form a bidentate intermediate.

9.
Dalton Trans ; (5): 930-7, 2005 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-15726147

RESUMO

A nitrosylruthenium alkynyl complex of TpRuCl(C[triple bond]CPh)(NO)(1a) was reacted with PPh3 in the presence of HBF4.Et2O at room temperature to give a beta-phosphonio-alkenyl complex (E)-[TpRuCl{CH=C(PPh3)Ph}(NO)]BF4(2.BF4). On the other hand, for gamma-hydroxyalkynyl complexes TpRuCl{C[triple bond]CC(R)2OH}(NO)(R = Me (1b), Ph (1c), H (1d)), similar treatments with PPh3 were found to give gamma-phosphonio-alkynyl [TpRuCl{C[triple bond]CC(Me)2PPh3}(NO)]BF4(3.BF4),alpha-phosphonio-allenyl [TpRuCl{C(PPh3)=C=CPh2}(NO)]BF4(4.BF4), and a novel product of gamma-hydroxy-beta-phosphonio-alkenyl (E)-[TpRuCl{CH=C(PPh3)CH2OH}(NO)]BF4(5.BF4), respectively. Dominant factors for the selectivity in affording 3-5 were associated with the steric congestion and electronic properties at the gamma-carbons, along with those around the metal fragment. From the bis(alkynyl) complex TpRu(C[triple bond]CPh)2(NO)6, a bis(beta-phosphonio-alkenyl)(E,E)-[TpRu{CH=C(PPh3)Ph}2(NO)](BF4)2{7.(BF4)2} was produced at room temperature. However, similar reactions at 0 degrees C gave an alkynyl beta-phosphonio-alkenyl complex (E)-[TpRu(C[triple bondCPh){CH=C(PPh3)Ph}(NO)]BF4(8.BF4) as a sole product, of which additional hydration in the presence of HBF4.Et2O afforded a [small beta]-phosphonio-alkenyl ketonyl (E)-[TpRu{CH2C(O)Ph}{CH=C(PPh3)Ph}(NO)]BF(.9BF4). Five complexes, 2-5 and 7 were crystallographically characterized.


Assuntos
Alcadienos/química , Alcenos/química , Alquinos/química , Compostos de Boro/química , Nitrocompostos , Compostos Organofosforados/química , Rutênio/química , Cristalografia por Raios X , Modelos Químicos , Pirazóis/química
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