Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-32186363

RESUMO

In this paper, we demonstrate that cell adhesion and neuron maturation can be guided by patterned oxide surfaces functionalized with organic molecular layers. It is shown that the difference in the surface potential of various oxides (SiO2, Ta2O5, TiO2, and Al2O3) can be increased by functionalization with a silane, (3-aminopropyl)-triethoxysilane (APTES), which is deposited from the gas phase on the oxide. Furthermore, it seems that only physisorbed layers (no chemical binding) can be achieved for some oxides (Ta2O5 and TiO2), whereas self-assembled monolayers (SAM) form on other oxides (SiO2 and Al2O3). This does not only alter the surface potential but also affects the neuronal cell growth. The already high cell density on SiO2 is increased further by the chemically bound APTES SAM, whereas the already low cell density on Ta2O5 is even further reduced by the physisorbed APTES layer. As a result, the cell density is ∼8 times greater on SiO2 compared to Ta2O5, both coated with APTES. Furthermore, neurons form the typical networks on SiO2, whereas they tend to cluster to form neurospheres on Ta2O5. Using lithographically patterned Ta2O5 layers on SiO2 substrates functionalized with APTES, the guided growth can be transferred to complex patterns. Cell cultures and molecular layers can easily be removed, and the cell experiment can be repeated after functionalization of the patterned oxide surface with APTES. Thus, the combination of APTES-functionalized patterned oxides might offer a promising way of achieving guided neuronal growth on robust and reusable substrates.

2.
Fertil Steril ; 112(4): 663-669.e1, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31371041

RESUMO

OBJECTIVE: To evaluate the affect of the duration of donor sperm storage on pregnancy success among women undergoing assisted reproduction. DESIGN: Retrospective cross-sectional study. SETTING: Sperm bank. PATIENT(S): A total of 119,558 specimens retrieved using a clinical information database of young adult men who were qualified sperm donors at the Hunan Province Human Sperm Bank of China from 2001 to 2016. INTERVENTION(S): Analysis of semen samples and clinical outcomes after semen use. MAIN OUTCOME MEASURE(S): Clinical information included semen parameters before and after freezing, clinical pregnancy, abortion and live birth rates after semen use. RESULT(S): The sperm's frozen-thaw survival rate decreased from 85.72% to 73.98% after 15 years of cryopreservation (P<.01). The clinical pregnancy rate of women undergoing artificial insemination with donor sperm was 23.09%, 22.36% and 22.32%, the clinical abortion rate was 10.06%, 10.02% and 12.00% and the live birth rate was 82.17%, 80.21% and 80.00% in the groups with 0.5-5, 6-10 and 11-15 storage years, respectively. The clinical pregnancy rate of women undergoing in vitro fertilization was 64.29%, 64.94% and 53.48%, the clinical abortion rate was 12.26%, 11.38% and 17.39% and the live birth rate was 81.63%, 79.11% and 73.91%, in the groups with 0.5-5, 6-10 and 11-15 years, respectively. CONCLUSION(S): The long-term cryostorage of semen in a human sperm bank does not affect clinical outcomes. However, cryopreservation longer than 5 years negatively influenced the quality of frozen-thawed donor sperm samples.

3.
Nanoscale ; 11(24): 11765-11773, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31184359

RESUMO

Effective oxygen evolution reaction (OER) catalysts composed of Earth-abundant transition metals are crucial for sustainable energy conversion and storage. Metal-organic frameworks (MOFs) with tunable compositions are promising precursors for the fabrication of hollow and porous electrocatalysts. However, pulverous MOFs usually suffer from agglomeration during pyrolysis, greatly reducing the activity of their derived catalysts. In this work, Prussian blue analogue (PBA) arrays with hierarchical multidimensional architecture were directly grown on nickel foam (NF) using a template-oriented method. The subsequent calcination in air allowed for obtaining NixCo3-xO4 nanoplate arrays consisting of porous and hollow nanocubes. The derived bimetallic NixCo3-xO4/NF required only an overpotential of 287 mV to achieve a current density of 10 mA cm-2 in 1.0 M KOH solution, which is much lower than that of the monometallic NiO and the RuO2 benchmark. The 3D intersectional architecture of the NixCo3-xO4 nanoplates and the porous and hollow nanocube subunits contributed to the large specific surface area and reduced charge-transfer resistance of the NixCo3-xO4/NF electrode. Density functional theory (DFT) calculations and post-OER characterization revealed that the incorporated Co was the active sites and electrochemical active CoOOH intermediates were in situ formed during the OER. Our study provides a facile and efficient strategy for the rational design of MOF-derived materials towards effective and low-cost electrocatalysis.

4.
Langmuir ; 35(25): 8183-8190, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31144819

RESUMO

Although organosilanes, especially 3-aminopropyltriethoxysilane (APTES), are commonly used to functionalize oxide substrates for a variety of applications ranging from molecular/biosensors and electronics to protective layers, reliable and controlled deposition of these molecules remains a major obstacle. In this study, we use surface potential analyses to record and optimize the gas-phase deposition of APTES self-assembled monolayers (SAMs) and to determine the resulting change of the electrokinetic potential and charge at the solid?liquid interface when the system is exposed to an electrolyte. Using a gas-phase molecular layer deposition setup with an in situ molecule deposition sensor, APTES is deposited at room temperature onto ozone-activated SiO2. The resulting layers are characterized using various techniques ranging from contact angle analysis, ellipsometry, fluorescence microscopy, X-ray photoelectron spectroscopy, and electrokinetic analysis to AFM. It turns out that adequate postdeposition treatment is crucial to the formation of perfect molecular SAMs. We demonstrate how a thick layer of APTES molecules is initially adsorbed at the surface; however, the molecules do not bind to SiO2 and are removed if the film is exposed to an electrolyte. Only if the film is kept in a gaseous environment (preferable at low pressure) for a long enough time do APTES molecules start to bind to the surface and form the SAM layer. During this time, superfluous molecules are removed. The resulting modification of the electrokinetic potential at the surface is analyzed in detail for different states.

5.
Materials (Basel) ; 11(11)2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30469387

RESUMO

The electronic structure and spin polarization properties of pentagonal structure PdSe2 doped with transition metal atoms are studied through first- principles calculations. The theoretical investigations show that the band gap of the PdSe2 monolayer decreases after introducing Cr, Mn, Fe and Co dopants. The projected densities of states show that p-d orbital couplings between the transition metal atoms and PdSe2 generate new spin nondegenerate states near the Fermi level which make the system spin polarized. The calculated magnetic moments, spin density distributions and charge transfer of the systems suggest that the spin polarization in Cr-doped PdSe2 will be the biggest. Our work shows that the properties of PdSe2 can be modified by doping transition metal atoms, which provides opportunity for the applications of PdSe2 in electronics and spintronics.

6.
Nanomaterials (Basel) ; 8(11)2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30469395

RESUMO

The electronic structure and the optical properties of Graphene/MoS2 heterostructure (GM) are studied based on density functional theory. Compared with single-layer graphene, the bandgap will be opened; however, the bandgap will be reduced significantly when compared with single-layer MoS2. Redshifts of the absorption coefficient, refractive index, and the reflectance appear in the GM system; however, blueshift is found for the energy loss spectrum. Electronic structure and optical properties of single-layer graphene and MoS2 are changed after they are combined to form the heterostructure, which broadens the extensive developments of two-dimensional materials.

7.
Sci Total Environ ; 618: 1529-1538, 2018 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-29054613

RESUMO

Increasing atmospheric nitrogen (N) deposition may affect plant biodiversity, subsequently altering ecosystem stability. While a few studies have explored how simulated N deposition affects community stability and its underlying mechanisms, the experimental levels of N addition used are usually higher than current and future N deposition rates. Thus, their results could produce highly uncertain predictions of ecosystem function, especially if the responses to N deposition are nonlinear. We conducted a manipulative experiment that simulated elevated atmospheric N deposition with several N addition levels to evaluate the effect of N deposition on ecosystem stability and its underlying mechanisms in a semiarid grassland in northern China. Here we show that N addition altered community diversity, reducing species richness, evenness, diversity and dominance. In addition, we found that N addition at current N deposition levels had no significant impact on community stability. In contrast, N addition at levels from 4.6 to 13.8gNm-2yr-1 significantly decreased community stability, although community stability for the 13.8gNm-2yr-1 treatment was higher than that for the 4.6gNm-2yr-1 treatment. These results indicate that the response of community stability to N enrichment is nonlinear. This nonlinear change in community stability was positively correlated with species asynchrony, species richness, and species diversity as well as the stability of dominant species and the stability of the grass functional group. Our data suggest a need to re-evaluate the mechanisms responsible for the effects of N deposition on natural ecosystem stability across multiple levels of N enrichment and that additional experimentation with gradients of N loads more similar to future atmospheric N deposition rates is needed.

8.
Open Biol ; 8(12): 180158, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30977704

RESUMO

Histone acetylation is a specific type of chromatin modification that serves as a key regulatory mechanism for many cellular processes in mammals. However, little is known about its biological function in invertebrates. Here, we identified 12 members of histone deacetylases (NlHDACs) in the brown planthopper (BPH), Nilaparvata lugens. RNAi-mediated silencing assay showed that NlHdac1, NlHdac3 and NlHdac4 played critical roles in female fertility via regulating ovary maturation or ovipositor development. Silencing of NlHdac1 substantially increased acetylation level of histones H3 and H4 in ovaries, indicating NlHDAC1 is the main histone deacetylase in ovaries of BPH. RNA sequencing (RNA-seq) analysis showed that knockdown of NlHdac1 impaired ovary development via multiple signalling pathways including the TOR pathway. Acoustic recording showed that males with NlHdac1 knockdown failed to make courtship songs, and thus were unacceptable to wild-type females, resulting in unfertilized eggs. Competition mating assay showed that wild-type females overwhelmingly preferred to mate with control males over NlHdac1-knockdown males. These findings improve our understanding of reproductive strategies controlled by HDACs in insects and provide a potential target for pest control.


Assuntos
Hemípteros/fisiologia , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Análise de Sequência de RNA/métodos , Acetilação , Animais , Corte , Feminino , Fertilidade , Inativação Gênica , Hemípteros/genética , Histonas/metabolismo , Proteínas de Insetos/metabolismo , Masculino , Família Multigênica , Ovário , Transdução de Sinais
9.
Insect Biochem Mol Biol ; 93: 19-26, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29241845

RESUMO

The brown planthopper Nilaparvata lugens is one of the most destructive insect pests in Asia, demonstrating high fertility and causing huge crop losses by sucking sap of rice as well as transmitting viruses. However, functional genomic studies on N. lugens are seriously constrained by lack of genetic tools. Here, we employed two eye pigmentation genes to generate germ-line mutations in N. lugens using the CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated) system. We showed that injection of single guide RNA of the cinnabar gene of N. lugens (Nl-cn) into pre-blastoderm eggs induced insertion and deletion (indels) in the founder generation (G0), which were heritably transmitted to the following G1 generation, leading to bright red compound eyes and ocelli. Mutations of N. lugens white (Nl-w) generated a high mutant rate of up to 27.3%, resulting in mosaic eyes consisting of white and lightly pigmented ommatidia in both G0 and G1 individuals. The specificity of CRISPR/Cas9-mediated mutagenesis was further bolstered by PCR and RNA interference-based knockdown analysis. These results show that CRISPR/Cas9-mediated gene editing is achievable in a hemipteran insect, offering a valuable tool for the study of functional genomics and pest management in this planthopper species.


Assuntos
Sistemas CRISPR-Cas , Olho Composto de Artrópodes/fisiologia , Hemípteros/fisiologia , Proteínas de Insetos/genética , Pigmentação , Animais , Sequência de Bases , Cor de Olho/genética , Feminino , Técnicas de Inativação de Genes , Hemípteros/genética , Proteínas de Insetos/metabolismo , Masculino
10.
ACS Appl Mater Interfaces ; 9(34): 29265-29272, 2017 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-28783310

RESUMO

Modifying the surfaces of oxides using self-assembled monolayers offers an exciting possibility to tailor their surface properties for various applications ranging from organic electronics to bioelectronics applications. The simultaneous use of different molecules in particular can extend this approach because the surface properties can be tuned via the ratio of the chosen molecules. This requires the composition and quality of the monolayers to be controlled on an organic level, that is, on the nanoscale. In this paper, we present a method of modifying the surface and surface properties of silicon oxide by growing self-assembled monolayers comprising various compositions of two different molecules, (3-aminopropyl)-triethoxysilane and (3-glycidyloxypropyl)-trimethoxysilane, by means of in situ controlled gas-phase deposition. The properties of the resulting mixed molecular monolayers (e.g., effective thickness, hydrophobicity, and surface potential) exhibit a perfect linear dependence on the composition of the molecular layer. Finally, coating the mixed layer with poly(l-lysine) proves that the density of proteins can be controlled by the composition as well. This indicates that the method might be an ideal way to optimize inorganic surfaces for bioelectronics applications.

11.
Zhonghua Nan Ke Xue ; 23(3): 231-236, 2017 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-29706044

RESUMO

Objective: To investigate whether in vitro culture medium (IVCM) for sparse spermatozoa can improve human sperm motility for the purpose of helping clinicians, laboratorians and patients choose a better strategy of assisted reproduction. METHODS: Semen samples were obtained from 178 males for routine semen examination from March to August 2016, including 151 cases of asthenozoospermia and 27 cases of normal sperm motility. A total of 200 µl was collected from each sample and divided into two equal portions and equal volumes of IVCM (experimental group) and F10 (1×) (control group) were added to the two portions, respectively, followed by 30-minute incubation at 37℃ in an incubator with 5% CO2. Sperm concentration, motility and viability and the percentages of progressively motile, non-progressively motile and immotile sperm were recorded before and after incubation. RESULTS: After activated with IVCM, neither the samples with asthenozoospermia nor those with normal sperm motility showed any statistically significant difference in sperm viability from the baseline or the control group (P>0.05). The rates of progressively and non-progressively motile sperm from the asthenozoospermia males were increased by 14.02% and 4.86% respectively, while that of immotile sperm decreased by 19.01% in the experimental group (P >0.01), and similar results were observed in the semen samples from the men with normal sperm motility. The percentage of reduced immotile viable sperm was positively correlated with that of immotile viable sperm in both the asthenozoospermia patients (r = 0.260, P <0.01) and the men with normal sperm motility (r = 0.679, P <0.01). CONCLUSIONS: IVCM can increase sperm motility without affecting sperm viability in men with either asthenozoospermia or normal sperm motility. The larger the proportion of immotile viable sperm, the higher the percentages of progressively and non-progressively motile sperm in the semen after IVCM activation, and this correlation is more significant in men with normal sperm motility than in asthenozoospermia patients.


Assuntos
Astenozoospermia/fisiopatologia , Análise do Sêmen/métodos , Motilidade Espermática , Espermatozoides/fisiologia , Astenozoospermia/terapia , Meios de Cultura , Técnicas de Cultura , Humanos , Masculino , Sêmen , Contagem de Espermatozoides
12.
Environ Int ; 49: 18-23, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-22944358

RESUMO

Fish consumption is considered as the primary pathway of human methylmercury (MeHg) exposure. However, recent studies highlighted that, rice, rather than fish, is the main route of human MeHg exposure in Guizhou, inland China. China is considered as the largest anthropogenic source of mercury (Hg) emission in the world, which has led to serious environmental Hg pollution. But there are no comprehensive studies regarding this environmental health problem to evaluate human Hg exposure and associated health effects. This study aimed to estimate daily MeHg intake and health risk in 7 provinces in southern China, and to assess the relative contribution from rice and fish consumption. The average levels of total mercury (THg) and MeHg in rice samples were generally low at 10.1 ng·g⁻¹ and 2.47 ng·g⁻¹, respectively. But a total of 36 rice samples (12.7%) had THg concentration exceeding the national limit (20 ng·g⁻¹). Generally, rural population had significantly higher Probable Daily Intakes (PDIs) of MeHg than urban population from rice consumption and its relative contribution to MeHg exposure increased significantly from coastal to inland area. The averages of PDIs of MeHg were 0.020 µg·kg⁻¹·d⁻¹ and 0.028 µg·kg⁻¹·d⁻¹ for urban and rural population in southern China, respectively. Despite the serious environmental Hg pollutions in China, the general population in southern China had low risk of MeHg exposure. But rice is an important route of human MeHg exposure in southern China, especially for the rural population in inland area. The findings indicate that rice consumption should be considered when evaluating MeHg exposure in rice eating population in southern China.


Assuntos
Dieta/estatística & dados numéricos , Exposição Ambiental/análise , Poluentes Ambientais/análise , Contaminação de Alimentos/análise , Compostos de Metilmercúrio/análise , Oryza/química , China , Exposição Ambiental/estatística & dados numéricos , Poluição Ambiental/estatística & dados numéricos , Contaminação de Alimentos/estatística & dados numéricos , Humanos , Compostos de Metilmercúrio/metabolismo , Medição de Risco
13.
Environ Pollut ; 159(5): 1283-9, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21349615

RESUMO

In China, total Hg (HgT) and methylmercury (MeHg) were quantified in rice grain grown in three sites using water-saving rice cultivation methods, and in one Hg-contaminated site, where rice was grown under flooded conditions. Polished white rice concentrations of HgT (water-saving: 3.3±1.6 ng/g; flooded: 110±9.2 ng/g) and MeHg (water-saving 1.3±0.56 ng/g; flooded: 12±2.4 ng/g) were positively correlated with root-soil HgT and MeHg contents (HgT: r2=0.97, MeHg: r2=0.87, p<0.05 for both), which suggested a portion of Hg species in rice grain was derived from the soil, and translocation of Hg species from soil to rice grain was independent of irrigation practices and Hg levels, although other factors may be important. Concentrations of HgT and other trace elements were significantly higher in unmilled brown rice (p<0.05), while MeHg content was similar (p>0.20), indicating MeHg infiltrated the endosperm (i.e., white rice) more efficiently than inorganic Hg(II).


Assuntos
Endosperma/metabolismo , Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Oryza/metabolismo , Agricultura , China , Conservação dos Recursos Naturais , Endosperma/química , Mercúrio/análise , Compostos de Metilmercúrio/análise , Oryza/química , Água
14.
Drug Alcohol Depend ; 98(1-2): 30-4, 2008 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-18538955

RESUMO

Previously we reported the results of Wave One of a genome-wide search for heroin dependence susceptibility loci in Han Chinese families from Yunnan Province, China, near Asia's "Golden Triangle". Our initial analysis of 194 independent affected sibling-pairs from 192 families identified two regions with nonparametric linkage (NPL) Z-scores greater than 2.0, which were suggestive of linkage. Presently we have supplemented our sample with additional individuals and families, bringing the total number of genotyped individuals to 1513 and the number of independent sibling-pairs to 397. Upon repeating our analyses with this larger sample, we found that the evidence for linkage at our most strongly implicated locus from Wave One (marker D17S1880; 53.4cM on 17q11.2; NPL Z=2.36; uncorrected p=0.009) was completely abolished (Z=-1.13; p=0.900). In contrast, the evidence for linkage at the second-most strongly implicated locus from Wave One (D4S1644; 143.3cM on 4q31.21; NPL Z=2.19; uncorrected p=0.014) increased in its magnitude and significance (Z=2.64; uncorrected p=0.004), becoming the most strongly implicated locus overall in our full sample. Other loci on chromosomes 1, 2, 4, 12, 16, and X also displayed nominally significant evidence for linkage (p< or =0.05). These loci appear to be entirely distinct from opioid-linked loci reported by other groups; however, meta-analyses of all available linkage data may reveal common sites of interest and promising candidate genes that can be further evaluated as risk factors for the illness.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Mapeamento Cromossômico , Marcadores Genéticos/genética , Estudo de Associação Genômica Ampla , Dependência de Heroína/genética , Adolescente , Adulto , Fatores Etários , Alelos , Grupo com Ancestrais do Continente Asiático/estatística & dados numéricos , China , Cromossomos Humanos Par 17/genética , Cromossomos Humanos Par 4/genética , Feminino , Frequência do Gene/genética , Predisposição Genética para Doença/genética , Genética Populacional , Genótipo , Dependência de Heroína/epidemiologia , Humanos , Escore Lod , Masculino , Fatores Sexuais , Irmãos , Adulto Jovem
15.
Am J Med Genet B Neuropsychiatr Genet ; 141B(6): 648-52, 2006 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-16856125

RESUMO

The contribution of genes to the etiology of heroin dependence is greater than for any other illicit drug. The specific genes mediating this effect remain unknown, despite several candidate gene association studies of the condition. Here we report the results of a genome-wide search for heroin dependence susceptibility loci using multipoint linkage analysis. In phase I, we ascertained 207 independent affected sibling pairs from 202 Han Chinese families from Yunnan Province, China (near Asia's "Golden Triangle"). After data-cleaning, 194 fully independent sibling pairs (i.e., with no overlapping individuals) from 192 families were genotyped on 404 short tandem-repeat markers spaced at an average inter-marker distance of 9 cM. Although none of our findings achieved genome-wide significance, we found two regions with non-parametric linkage (NPL) Z-scores greater than 2.0. An NPL Z-score of 2.19 (uncorrected P-value = 0.014) was observed at D4S1644, located at 143.3 cM on chromosomal region 4q31.21. The highest NPL Z-score of 2.36 (uncorrected P-value = 0.009) was observed at 53.4 cM on chromosomal region 17q11.2 at marker D17S1880. This is among the first published reports of a genome-wide linkage analysis of heroin dependence. Forthcoming results from other groups and from two additional waves of ascertainment (one planned, one currently ongoing) for our own study should be able to support or refute the putative susceptibility loci we have identified, after which positional candidate genes can be further evaluated as risk factors for the illness.


Assuntos
Ligação Genética , Genoma Humano , Dependência de Heroína/genética , China , Cromossomos Humanos Par 17 , Cromossomos Humanos Par 4 , Feminino , Dependência de Heroína/etnologia , Humanos , Masculino
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA