RESUMO
The dissociation of H2O is a crucial aspect for the water-gas shift reaction, which often occurs on the vacancies of a reducible oxide support. However, the vacancies sometimes run off, thus inhibiting H2O dissociation. After high-temperature treatment, the ceria supports were lacking vacancies because of sintering. Unexpectedly, the in situ generation of surface oxygen vacancies was observed, ensuring the efficient dissociation of H2O. Due to the surface reconstruction of ceria nanorods, the copper species sustained were highly dispersed on the sintered support, on which CO was adsorbed efficiently to react with hydroxyls from H2O dissociation. In contrast, no surface reconstruction occurred in ceria nanoparticles, leading to the sintering of copper species. The sintered copper species were averse to adsorb CO, so the copper-ceria nanoparticle catalyst had poor reactivity even when surface oxygen vacancies could be generated in situ.
RESUMO
A facile spray pyrolysis method is introduced to construct the hollow CeO2-Al2O3 spheres with atomically dispersed Fe. Only nitrates and ethanol were involved during the one-step preparation process using the ultrasound spray pyrolysis approach. Detailed explorations demonstrated that differences in the pyrolysis temperature of the precursors and heat transfer are crucial to the formation of the hollow nanostructure. In addition, iron species were in situ atomically dispersed on the as-formed CeO2-Al2O3 hollow spheres via this strategy, which demonstrated promising potential in transferring syn-gas to valuable gasoline products.
RESUMO
Copper manganese composite (hopcalite) catalyst has been widely explored for low-temperature CO oxidation reactions. However, the previous reports on the stabilization of such composite catalysts have shown that they deactivated severely under moist conditions. Herein, we developed an α-MnO2 nanorod-supported copper oxide catalyst that is very active and stable for the conditions with or without moisture by the deposition precipitation (DP) method. Incredibly, the CuO/MnO2 DP catalyst (with 5 wt % copper loading) achieves superior activity with a reaction rate of 9.472 µmol-1·gcat-1·s-1 even at ambient temperatures, which is at least double times of that for the reported copper-based catalyst. Additionally, the CuO/MnO2 DP catalyst is significantly more stable than the copper manganese composite catalysts reported in the literature under the presence of 3% water vapor as well as without moisture. A correlation between the catalytic CO oxidation activity and textural characteristics was derived via multitechnique analyses. The results imply that the superior activity of the CuO/MnO2 DP catalyst is associated with the proper adsorption of CO on partially reduced copper oxide as Cu(I)-CO and more surface oxygen species at the interfacial site of the catalyst.
RESUMO
The construction of stable active site in nanocatalysts is of great importance but is a challenge in heterogeneous catalysis. Unexpectedly, coordination-unsaturated and atomically dispersed copper species were constructed and stabilized in a sintered copper-ceria catalyst through air-calcination at 800 °C. This sintered copper-ceria catalyst showed a very high activity for CO oxidation with a CO consumption rate of 6100 µmolCO·gCu-1·s-1 at 120 °C, which was at least 20 times that of other reported copper catalysts. Additionally, the excellent long-term stability was unbroken under the harsh cycled reaction conditions. Based on a comprehensive structural characterization and mechanistic study, the copper atoms with unsaturated coordination in the form of Cu1O3 were identified to be the sole active site, at which both CO and O2 molecules were activated, thus inducing remarkable CO oxidation activity with a very low copper loading (1 wt %).
RESUMO
Idiopathic nonobstructive azoospermia (INOA) is one of the most severe forms of male infertility, yet its pathophysiology remains unclear. WT1 (Wilms' tumor 1) regulates the polarity of Sertoli cells, thereby playing a critical, indirect role in spermatogenesis. Here, we evaluated WT1 gene variation associates with INOA by assessing its promoter and coding regions in 200 patients diagnosed with INOA and 200 proven-fertile men. Three novel variants in the WT1 coding region were detected only in INOA patients, including two synonymous variants and one missense variant, p.Phe435Leu (p.F435L), which was predicted to be deleterious to protein function. The results of dual luciferase reporter showed that the WT1 p.F435L variant decreases transcription of COL4A1 and WNT4 promoters through a dominant-negative effect. Furthermore, chromatin immunoprecipitation assays revealed that COL4A1 and WNT4 promoter is directly bound by wild-type WT1 protein, but not the p.F435L WT1 variant. Thus, we identified a novel functional variant of WT1 functionally associated with INOA. Mol. Reprod. Dev. 84: 222-228, 2017. © 2017 Wiley Periodicals, Inc.
Assuntos
Azoospermia , Mutação de Sentido Incorreto , Proteínas WT1 , Adulto , Substituição de Aminoácidos , Azoospermia/genética , Azoospermia/metabolismo , Azoospermia/patologia , Colágeno Tipo IV/biossíntese , Colágeno Tipo IV/genética , Humanos , Masculino , Transcrição Gênica/genética , Proteínas WT1/genética , Proteínas WT1/metabolismo , Proteína Wnt4/biossíntese , Proteína Wnt4/genéticaRESUMO
This study sought to establish archives of genetic copy number variation (CNV) in human embryonic stem cell (hESC) lines that are associated with known diseases. We collected patients' fresh, discarded zygotes from in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) protocols. A total of 208 fresh, tripronuclear, discarded zygotes were also collected in this study from patients on the third day of their treatment cycle, prior to transfer. The blastula-formation rates were 13.51% (26/192) and 26.7% (4/15) while the high-quality blastocyst formation rates were 5.8% (11/192) and 20% (3/15) in the IVF and ICSI groups, respectively. The inner cell mass (ICM) from each embryo was mechanically separated, and then grown on feeder layers consisting of mouse embryonic fibroblasts and human foreskin fibroblasts (a 1:1 mixture). The hESC karyotype was determined by traditional G-banding; analysis of the results for the Zh19P25 and Zh20P24 cell lines showed that both were 46 XY. CNV and loss-of-heterozygosity analysis of hESC gDNA was performed to assess the genetic characteristics associated with molecular diseases using the high-resolution Infinium High-Density HumanCytoSNP-12 DNA chip. Seven CNVs in Zh19P25 and Zh20P24 were deletions, and a region that corresponds to Potocki-Shaffer disease, 11p11.2-11p11.12 in Zh20P24, showed a 2.98-Mb loss. These data together suggest that single-nucleotide polymorphism (SNP) microarray analysis for molecular cytogenetic features can help to distinguish hESC lines with a normal karyotype from tripronuclear zygotes with known, disease-related characteristics.
Assuntos
Técnicas de Cultura de Células/métodos , Variações do Número de Cópias de DNA , Células-Tronco Embrionárias Humanas/citologia , Perda de Heterozigosidade , Zigoto/citologia , Animais , Diferenciação Celular , Núcleo Celular/genética , Células Cultivadas , Diploide , Técnicas de Cultura Embrionária/métodos , Fertilização in vitro , Células-Tronco Embrionárias Humanas/fisiologia , Humanos , Cariotipagem , Camundongos , Injeções de Esperma Intracitoplásmicas , Zigoto/metabolismoRESUMO
Computer-based procedures (CBPs) are expected to improve operator performance in nuclear power plants (NPPs), but they may reduce the openness of interaction between team members and harm teamwork consequently. To support teamwork in the main control room of an NPP, this study proposed a team-level integrated CBP that presents team members' operation status and execution histories to one another. Through a laboratory experiment, we compared the new integrated design and the existing individual CBP design. Sixty participants, randomly divided into twenty teams of three people each, were assigned to the two conditions to perform simulated emergency operating procedures. The results showed that compared with the existing CBP design, the integrated CBP reduced the effort of team communication and improved team transparency. The results suggest that this novel design is effective to optim team process, but its impact on the behavioural outcomes may be moderated by more factors, such as task duration. PRACTITIONER SUMMARY: The study proposed and evaluated a team-level integrated computer-based procedure, which present team members' operation status and execution history to one another. The experimental results show that compared with the traditional procedure design, the integrated design reduces the effort of team communication and improves team transparency.
Assuntos
Redes de Comunicação de Computadores , Processos Grupais , Centrais Nucleares/organização & administração , Simplificação do Trabalho , Local de Trabalho/psicologia , Adolescente , Adulto , China , Humanos , Masculino , Adulto JovemRESUMO
PURPOSE: To evaluate basal testosterone (T) levels in women undergoing in vitro fertilization (IVF) cycles and examine the association between basal T levels and ovarian response or IVF pregnancy outcome. METHODS: We retrospectively analyzed 1413 infertile Chinese women undergoing their first IVF treatment at our institution's reproductive center from March 2011 to May 2013. The basal testosterone (T) levels in women undergoing in vitro fertilization (IVF) and the relationship between basal T levels and ovarian response or IVF pregnancy outcome were determined. These patients did not have polycystic ovary syndrome (PCOS) or endometriosis, and were treated with a long luteal down-regulation protocol. Subjects were divided into 2 groups according to basal testosterone (T) levels: Group 1, basal T values <20 ng/dl (n = 473), and Group 2, basal T values >20 ng/dl (n = 940). We evaluated the association of basal T levels with ovarian response and IVF outcome in the two groups. RESULTS: In this study, BMI, basal follicle-stimulating hormone (FSH) levels, basal luteinizing hormone (LH) levels, antral follicle count (AFC), days of stimulation, total gonadotrophin dose, basal FSH/LH ratio, and the number of follicles >14 mm were significantly different (P < 0.05) between the two groups. Basal T level positively correlated with ovarian reserve function, number of follicles >14 mm on human chorionic gonadotrophin (HCG) day, and total gonadotropin dose. However, basal T levels play no role in predicting IVF pregnancy outcome. CONCLUSION: Basal T level can be used as a good predictor for ovarian response and the number of large follicles on HCG day. Additionally, we may use basal T level as a marker to predict FSH dosage. In general women, lower level of T might relate with potential poor ovarian response. However, based on our data, basal T levels do not predict pregnancy outcome.
Assuntos
Fertilização in vitro/métodos , Folículo Ovariano/crescimento & desenvolvimento , Resultado da Gravidez , Testosterona/sangue , Adulto , Gonadotropina Coriônica/administração & dosagem , Transferência Embrionária , Feminino , Humanos , Hormônio Luteinizante/administração & dosagem , Folículo Ovariano/efeitos dos fármacos , Indução da Ovulação/métodos , Síndrome do Ovário Policístico/sangue , Síndrome do Ovário Policístico/patologia , GravidezRESUMO
PURPOSE: To explore the effect of group culture on the developmental potential of discarded embryos in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles and establish the human embryonic stem cell lines for future research. METHORDS: Fresh discarded embryos were collected from the IVF/ICSI-ET program in the reproductive medical center of the first affiliated hospital of Zhengzhou university in this study. All zygotes were individually cultured from Day 1 to Day 3. On Day 3, discard embryos were then cultured in group of 1-4 embryos per droplet (30 µl/droplets) with a constant culture medium until Day 5 or 6. Mechanical method was used to isolate the inner cell mass (ICM) of blastocyst from the embryo. Then we inoculated the ICM on feeder layer. After identification of those cells, the human embryonic stem cell lines (hESCs) were established. RESULTS: In this study, we collected 1,223 fresh discarded embryos and they were sequential cultured to the blastocysts (18.07 %, 221/1,223), in which good quality blastocysts were 61(4.98 %, 61/1,223). There was no significant difference in the patients. The embryos from 1PN, 2PN, 3PN were sequential cultured to the blastocyst s(39.31 %,92/234;12.87 %,64/497;13.21 %,65/492),in which good quality blastocysts was 13.6 %(32/92),2.61 %(13/64), 3.04 %(15/65).1PN embryo's blastulation rate and quality embryo formation rate was significantly higher than the 2PN and 3PN embryos' (P <0.05). Three embryos group cultivation has the highest blastulation rate and quality embryo formation rate (P <0.05). In total, we successfully established 4 hESCs lines. CONCLUSION: The group culture of human discard embryos can improve the blastulation rate and blastocyst quality to some extent. Three embryos group cultivate is the better culture number. Human discard embryos are good source for establishment of hESCs.
Assuntos
Blastocisto/fisiologia , Técnicas de Cultura Embrionária/métodos , Desenvolvimento Embrionário/fisiologia , Células-Tronco Embrionárias/fisiologia , Adulto , Linhagem Celular , Meios de Cultura/metabolismo , Células Alimentadoras/fisiologia , Feminino , Fertilização in vitro/métodos , Humanos , Injeções de Esperma Intracitoplásmicas/métodos , Adulto Jovem , Zigoto/fisiologiaRESUMO
Currently, cisplatin resistance remains a primary clinical obstacle in the successful treatment of non-small cell lung cancer. Here, we designed, synthesized, and characterized two novel cyclometalated Ru(II) complexes, [Ru(bpy)2(1-Ph-7-OCH3-IQ)] (PF6) (bpy = 2,2'-bipyridine, IQ = isoquinoline, RuIQ7)and [Ru(bpy)2(1-Ph-6,7-(OCH3)2-IQ)] (PF6) (RuIQ8). As experimental controls, we prepared complex [Ru(bpy)2(1-Ph-IQ)](PF6) (RuIQ6) lacking a methoxy group in the main ligand. Significantly, complexes RuIQ6-8 displayed higher in vitro cytotoxicity when compared to ligands, precursor cis-[Ru(bpy)2Cl2], and clinical cisplatin. Mechanistic investigations revealed that RuIQ6-8 could inhibit cell proliferation by downregulating the phosphorylation levels of Akt and mTOR proteins, consequently affecting the rapid growth of human lung adenocarcinoma cisplatin-resistant cells A549/DDP. Moreover, the results from qRT-PCR demonstrated that these complexes could directly suppress the transcription of the NF-E2-related factor 2 gene, leading to the inhibition of downstream multidrug resistance-associated protein 1 expression and effectively overcoming cisplatin resistance. Furthermore, the relationship between the chemical structures of these three complexes and their anticancer activity, ability to induce cell apoptosis, and their efficacy in overcoming cisplatin resistance has been thoroughly examined and discussed. Notably, the toxicity test conducted on zebrafish embryos indicated that the three Ru-IQ complexes displayed favorable safety profiles. Consequently, the potential of these developed compounds as innovative therapeutic agents for the efficient and low-toxic treatment of NSCLC appears highly promising.
Assuntos
2,2'-Dipiridil/análogos & derivados , Antineoplásicos , Carcinoma Pulmonar de Células não Pequenas , Complexos de Coordenação , Neoplasias Pulmonares , Compostos Organometálicos , Rutênio , Animais , Humanos , Cisplatino/farmacologia , Cisplatino/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/patologia , Rutênio/química , Fator 2 Relacionado a NF-E2/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias Pulmonares/patologia , Peixe-Zebra/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Antineoplásicos/química , Linhagem Celular Tumoral , Complexos de Coordenação/farmacologia , Complexos de Coordenação/uso terapêuticoRESUMO
Tubulin beta 8 class VIII (TUBB8) is a ß-tubulin isotype that is specifically expressed in human oocytes and early embryos. It has been identified as a disease-causing gene in primary female infertility by affecting oocyte maturation arrest. This study investigated the genetic cause of female infertility in five patients from four families. Five women with primary infertility were recruited. Medical-exome sequencing and Sanger sequencing were performed on the patients, and their family members to identify candidate genes that explained infertility. Additionally, the morphology of oocytes and zygotes from the patients and controls were assessed. We observed recurrent oocytes MI arrest, oocytes abnormal fertilization, uncleaved embryos, and embryo transfer failure in the patients. Heterozygous missense variants in TUBB8, c.538G > A (p.V180M), c.527C > G (p.S176W), c.124C > G (p.L42V), and c.628A > C (p.I210L), were verified in four unrelated families. This study expanded the mutational spectrum of TUBB8 by identifying three novel heterozygous missense variants. Screening for TUBB8 mutation demonstrated the diagnostic utility of female infertility.
Assuntos
Infertilidade Feminina , Humanos , Feminino , Infertilidade Feminina/genética , Oócitos , Oogênese , Mutação , Fenótipo , Tubulina (Proteína)/genéticaRESUMO
Two new ruthenium(II) complexes [Ru(dip)2(PPßC)]PF6 (Ru1, dip = 4,7-diphenyl-1,10-phenanthroline, PPßC = N-(1,10-phenanthrolin-5-yl)-1-phenyl-9H-pyrido[3,4-b]indole-3-carboxamide) and [Ru(phen)2(PPßC)]PF6 (Ru2, phen = 1, 10-phenanthroline) with ß-carboline derivative PPßC as the primary ligand, were designed and synthesized. Ru1 and Ru2 displayed higher antiproliferative activity than cisplatin against the test cancer cells, with IC50 values ranging from 0.5 to 3.6 µM. Moreover, Ru1 and Ru2 preferentially accumulated in mitochondria and caused a series of changes in mitochondrial events, including the depolarization of mitochondrial membrane potential, the damage of mitochondrial DNA, the depletion of cellular ATP, and the elevation of intracellular reactive oxygen species levels. Then, it induced caspase-3/7-mediated A549 cell apoptosis. More importantly, both complexes could act as topoisomerase I catalytic inhibitors to inhibit mitochondrial DNA synthesis. Accordingly, the developed Ru(II) complexes hold great potential to be developed as novel therapeutics for cancer treatment.
Assuntos
Antineoplásicos , Complexos de Coordenação , Rutênio , Humanos , Células A549 , Rutênio/farmacologia , Rutênio/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/metabolismo , Mitocôndrias/metabolismo , Apoptose , DNA Mitocondrial/metabolismo , DNA Mitocondrial/farmacologia , Complexos de Coordenação/farmacologia , Complexos de Coordenação/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Linhagem Celular TumoralRESUMO
The unique layered structure and high conductivity of MXene materials make them highly promising for microwave absorption. However, the finite loss mechanism and severe agglomeration present challenging obstacles for ideal microwave absorbers, which could be effectively improved by constructing a three-dimensional (3D) porous structure. This study reports a 3D honeycomb MXene using a straightforward template method. The 3D MXene framework offers ample cavities to anchor the Prussian blue microcubes and their derivatives including Fe microboxes and Fe clusters by a simple annealing process. Based on the superiority of the 3D honeycomb architecture and magnetic-dielectric synergistic effects, the Fe/MXene absorbers demonstrate outstanding microwave absorption capabilities with the optimum reflection loss value of -40.3 dB at 2.00 mm in the low-frequency range from 4.2 to 5.6 GHz. The absorber also manifests superior radar wave attenuation by finite element analysis and exhibits great potential to be a flexible and thermal insulation material in a wide range of temperatures. This work proposes a useful reference for the design of 3D MXene-based porous architectures, and the synergistic magnetic-dielectric strategy further expands the potential of MXene-based absorbers, enabling them to be used as flexible and highly efficient microwave absorbers.
RESUMO
Natural products and metals play a crucial role in cancer research and the development of antitumor drugs. We designed and synthesized three new carboline-based cyclometalated iridium complexes [Ir(C-N)2(PPßC)](PF6), where PPßC = N-(1,10-phenanthrolin-5-yl)-1-phenyl-9H-pyrido[3,4-b]indole-3-carboxamide, C-N = 2-phenylpyridine (ppy, Ir1), 2-(2,4-difluorophenyl) pyridine (dfppy, Ir2), 7,8-benzoquinoline (bzq, Ir3), by combining iridium with ß-carboline derivative. These iridium complexes exhibited high potential antitumor effects after being promptly taken up by A549 cells. Accumulating in mitochondria rapidly and preferentially, Ir1-3 caused a series of changes in mitochondrial events, including the loss of mitochondrial membrane potential, the depletion of cellular ATP, and the elevation of reactive oxygen species, leading to significant death of A549 cells. Moreover, the activation of intracellular caspase pathway and apoptosis was further validated to contribute to iridium complexes-induced cytotoxicity. These novel iridium complexes exerted a prominent inhibitory effect on tumor growth in a three-dimensional multicellular tumor spheroid model.
Assuntos
Antineoplásicos , Carcinoma Pulmonar de Células não Pequenas , Complexos de Coordenação , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/patologia , Irídio/farmacologia , Neoplasias Pulmonares/patologia , Antineoplásicos/metabolismo , Carbolinas/farmacologia , Carbolinas/metabolismo , Apoptose , Mitocôndrias/metabolismo , Complexos de Coordenação/farmacologia , Complexos de Coordenação/uso terapêutico , Complexos de Coordenação/metabolismo , Linhagem Celular Tumoral , Espécies Reativas de Oxigênio/metabolismo , Proliferação de CélulasRESUMO
The quality and safety of human embryonic stem cells (hESCs) in clinical application depend on gene stability. Two Chinese hESC lines, Zh1 and Zh21, were incubated over a long period. We observed and compared the gene stability in the passage numbers 20, 17 for Zh1 cell line and passage numbers 27, 60, 68 for Zh21 cell line. Single nucleotide polymorphisis analysis indicated that hESCs in early passages had relative gene stability; and with the increase in passage number, gene instability became strong. We also found that there were copy number variations (CNVs) in both Zh21 and Zh1. We analyzed the CNVs of Chinese Han Beijing man (CHB; normal Chinese people) and found that the all CNV forms were the loss in Zh21, Zh1, and CHB. We also analyzed and compared the related pathways of the mutant genes. We propose three steps to ensure hESC safety. Firstly, besides the conventional methods such as pluripotent genes, chromosome G-banding and teratoma, high-resolution DNA chip analysis should also be adopted; secondly, chromosomal properties are monitored every 10 passages in less than passage 50 and every 5 passages in more than passage 50; thirdly, the related pathways of mutant genes should be observed because only the mutant genes with variations of their related pathways may affected cell functions.
Assuntos
Povo Asiático/genética , Cromossomos Humanos/genética , Variações do Número de Cópias de DNA , Células-Tronco Embrionárias/metabolismo , Perda de Heterozigosidade , Polimorfismo de Nucleotídeo Único , Técnicas de Cultura de Células , Linhagem Celular , Bandeamento Cromossômico , Cromossomos Humanos/química , Embrião de Mamíferos , Células-Tronco Embrionárias/citologia , Fertilização in vitro , Instabilidade Genômica , Heterozigoto , Humanos , Cariotipagem , Análise de Sequência com Séries de Oligonucleotídeos , Teratoma/diagnóstico , Teratoma/patologiaRESUMO
For high-temperature catalytic reaction, it is of significant importance and challenge to construct stable active sites in catalysts. Herein, we report the construction of sufficient and stable copper clusters in the copperâceria catalyst with high Cu loading (15 wt.%) for the high-temperature reverse water gas shift (RWGS) reaction. Under very harsh working conditions, the ceria nanorods suffered a partial sintering, on which the 2D and 3D copper clusters were formed. This partially sintered catalyst exhibits unmatched activity and excellent durability at high temperature. The interaction between the copper and ceria ensures the copper clusters stably anchored on the surface of ceria. Abundant in situ generated and consumed surface oxygen vacancies form synergistic effect with adjacent copper clusters to promote the reaction process. This work investigates the structure-function relation of the catalyst with sintered and inhomogeneous structure and explores the potential application of the sintered catalyst in C1 chemistry.
RESUMO
To explore the heterogeneity of spatial distribution and particle size distribution (PSD) in the main underlying surface soil in the source area of the Yangtze River, we used the fractal theory to describe the soil particle size distribution of alpine steppe and alpine meadow, and analyzed the difference of fractal dimension characteristics of soil of two different underlying surface and its relationship with soil particle composition. The results showed that soil particle size in the study area was mainly concentrated in 100-800 µm. The single fractal dimension (DV) of alpine steppe soil was 2.429-2.508, and that of alpine meadow soil was 2.697-2.743. The soil texture of alpine steppe was coarse, while that of alpine meadow soil was fine. Soil texture was the finest in the 20-30 cm depth, and the coarsest in the 0-10 cm layer. The multi-fractal dimension (capacity dimension D0, information entropy dimension D1, correlation dimension D2) of alpine steppe (0.896-0.961, 0.828-0.887, 0.725-0.819) was higher than that of alpine meadow (0.890-0.914, 0.693-0.744, 0.540-0.603). Compared with the alpine meadow, the alpine steppe had wider soil PSD, more complex soil structure, and higher soil heterogeneity. DV was positively correlated to clay and silt contents, and negatively correlated to sand content. D1 and D2 were negatively correlated with clay and silt contents, and positively correlated with sand content. Sand content was the main factor accounting for the non-uniform distribution of PSD and the changes of fractal dimension.
Assuntos
Rios , Solo , China , Pradaria , Tamanho da PartículaRESUMO
Exploring the state-of-the-art heterogeneous catalysts has been a general concern for sustainable and clean energy. Here, Pt-embedded CuO x-CeO2 multicore-shell (Pt/CuO x-CeO2 MS) composites are fabricated at room temperature via a one-pot and template-free procedure for catalyzing CO oxidation, a classical probe reaction, showing a volcano-shaped relationship between the composition and catalytic activity. We experimentally unravel that the Pt/CuO x-CeO2 MS composites are derived from an interfacial autoredox process, where Pt nanoparticles (NPs) are in situ encapsulated by self-assembled ceria nanospheres with CuO x clusters adhered through deposition/precipitation-calcination process. Only Cu-O and Pt-Pt coordination structures are determined for CuO x clusters and Pt NPs in Pt/CuO x-CeO2 MS, respectively. Importantly, the close vicinity between Pt and CeO2 benefits to more oxygen vacancies in CeO2 counterparts and results in thin oxide layers on Pt NPs. Meanwhile, the introduction of CuO x clusters is crucial for triggering synergistic catalysis, which leads to high resistance to aggregation of Pt NPs and improvement of catalytic performance. In CO oxidation reaction, both Ptδ+-CO and Cu+-CO can act as active sites during CO adsorption and activation. Nonetheless, redundant content of Pt or Cu will induce a strongly bound Pt-O-Ce or Cu-[O x]-Ce structures in air-calcinated Pt/CuO x-CeO2 MS composites, respectively, which are both deleterious to catalytic reactivity. As a result, the composition-dependent catalytic activity and superior durability of Pt/CuO x-CeO2 MS composites toward CO oxidation reaction are achieved. This work should be instructive for fabricating desirable multicomponent catalysts composed of noble metal and bimetallic oxide composites for diverse heterogeneous catalysis.
RESUMO
In situ morphological transition and turn-on fluorescence of self-assembled NDI derivatives driven by hydrazine hydrate are realized through H-bonding and charging of aromatic building blocks, demonstrating a stimuli-responsive supramolecular system useful for visual detection of hydrazine hydrate.
RESUMO
In vitro differentiation of human embryonic stem cells (hESCs) into endometrium-like cells may provide a useful tool for clinical treatment. The aim of the present study was to investigate the differentiation potential of hESCs into endometrium-like cells using three methods, which included induction by feeder cells, co-culture with endometrial stromal cells and induction with embryoid bodies. Following differentiation, the majority of cells positively expressed cytokeratin and epithelial cell adhesion molecule (EPCAM). Factors associated with endometrium cell function, namely the estrogen and progesterone receptors (ER and PR), were also detected. At day 21 following the induction of differentiation, the expression levels of cytokeratin, EPCAM, ER and PR were significantly increased in the co-culture method group, as compared with the other two methods. Furthermore, these cells became decidualized in response to progesterone and prolactin. In addition, the number of cytokeratin-positive or EPCAM-positive cells significantly increased following the induction of differentiation using the co-culture method, as compared with the other two methods. The mRNA expression levels of Wnt members that are associated with endometrial development were subsequently examined, and Wnt5a was found to be significantly upregulated in the differentiated cells induced by feeder cells and co-culture with endometrial stromal cells; however, Wnt4 and Wnt7a expression levels were unaffected. Additionally, the mRNA expression levels of Wnt5a in the differentiated cells co-cultured with endometrial stromal cells were higher when compared with those induced by feeder cells. In conclusion, the present findings indicated that the co-culture system is the optimal protocol for the induction of hESC differentiation into endometrium-like cells, and Wnt5a signaling may be involved in this process.