Lei Zhang
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Lei Zhang
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Origin of Enhanced Hole Injection in Organic Light-Emitting Diodes with an Electron-Acceptor Doping Layer: p-Type Doping or Interfacial Diffusion?
Journal: ACS applied materials & interfaces
September/14/2015
Description

The electrical doping nature of a strong electron acceptor, 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN), is investigated by doping it in a typical hole-transport material, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine (NPB). A better device performance of organic light-emitting diodes (OLEDs) was achieved by doping NPB with HATCN. The improved performance could, in principle, arise from a p-type doping effect in the codeposited thin films. However, physical characteristics evaluations including UV-vis absorption, Fourier transform infrared absorption, and X-ray photoelectron spectroscopy demonstrated that there was no obvious evidence of charge transfer in the NPB:HATCN composite. The performance improvement in NPB:HATCN-based OLEDs is mainly attributed to an interfacial modification effect owing to the diffusion of HATCN small molecules. The interfacial diffusion effect of the HATCN molecules was verified by the in situ ultraviolet photoelectron spectroscopy evaluations.

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Polymer microfiber rings for high-sensitivity optical humidity sensing.
Journal: Applied optics
March/18/2012
Description

We demonstrate microrings assembled with polyacrylamide (PAM) microfibers for high-sensitivity relative humidity (RH) sensing. When exposed to moisture, the PAM microfiber absorbs water molecules and inflates monotonically with the increasing humidity, resulting in evident spectral shifts of the resonance peaks of the microring. By measuring the spectral shifts, the microring shows sensitivity as high as 490 pm/%RH and a response time of about 120 ms, within a dynamic range from 5% to 71% RH.

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Effects of Herba epimedii and Fructus ligustri lucidi on the transcription factors in hypothalamus of aged rats.
Journal: Chinese journal of integrative medicine
March/18/2012
Description

OBJECTIVE

To comparatively analyze the difference in the expression of 54 transcription factors in the hypothalamus using protein chips following the medication of Chinese drugs for Shen-tonification, Herba Epimedii, and Fructus Ligustri lucidi (FL) to aged rats.

METHODS

Wistar rats, aged 15 months of SPF grade, were randomized into three groups, three males and three females in each group. They were medicated with Herba Epimedii decoction (HED, 0.14 g/kg), Fructus Ligustri lucidi decoction (FLD, 0.12 g/kg), and distilled water, respectively, twice a day for 15 days. The rats were sacrificed at the morning of the 16th day 1 h after medication, and their hypothalamus was taken and made into homogenate under an ice-bath for detecting the expression of transcription factors with chip technique.

RESULTS

The expressions of signal transduction and transcription activation factor-6 (Stat-6) and androgen receptor (AR) were up-regulated, and those of pre-B transcription factor1 (Pbx-1), stat-1 and AP-2 were down-regulated in both HED and FLD treated groups, but these changes occurred mainly in female rats in the former while mainly in males in the latter.

CONCLUSIONS

Chinese drugs for Shen-tonification could impact the expression of transcription factors in the hypothalamus of aged rats, dominantly on the neuro-endocrine factors responsible for the growth and development. The effects of drugs for tonifying Shen-yang and for tonifying Shen-yin are different, which is probably one of the pharmacological mechanisms of the Shen-tonifying drugs.

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Pubmed
Prognostic Value of Inflammatory and Nutritional Scores in Renal Cell Carcinoma After Nephrectomy.
Journal: Clinical genitourinary cancer
September/29/2017
Description

We compared the prognostic significance of inflammatory and nutritional scores, including the prognostic nutritional index (PNI), neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and lymphocyte-to-monocyte ratio in patients with renal cell carcinoma (RCC) undergoing nephrectomy.

We retrospectively analyzed the data from 1360 patients with RCC undergoing nephrectomy from 2001 to 2010. The PNI was calculated as the serum albumin level (g/L) + 5 × lymphocyte count (109/L). The receiver operating characteristic (ROC) curve analysis was used to determine the cutoff values. The areas under the ROC curve (AUCs) were calculated to compare the predictive ability of the indexes. Univariate and multivariate analyses were used to identify the prognostic factors for overall survival (OS) and progression-free survival (PFS).

The median follow-up period after surgery was 67 months (range, 2-108 months). The PNI had the largest AUC for both OS and PFS. On univariate analysis, each index was associated with OS and PFS. On multivariate analysis, PNI, rather than other inflammatory and nutritional scores, remained as a risk factor for OS (hazard ratio [HR], 1.645; 95% confidence interval [CI], 1.153-2.348; 2P = .006) and PFS (HR, 1.705; 95% CI, 1.266-2.296; 2P < .001).

The preoperative PNI might be a good prognostic factor for both OS and PFS in RCC patients undergoing nephrectomy.

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Alteration of circulating mitochondrial DNA concentration after irradiation.
Journal: Advances in experimental medicine and biology
December/10/2012
Description

Mitochondrial DNA (mtDNA) is maternally inherited and controls the oxygen-related production of adenosine-5'-triphosphate, which is transported from the mitochondria to other cellular compartments and used as energy for cellular activities. The mtDNA is physically separated from nuclear DNA (nDNA). Ionizing radiation (IR) causes the release of both mtDNA and nDNA into circulation. Our previous study demonstrated that nDNA has potential to be a biodosimeter. In this study, branched DNA technology was used to explore the alteration pattern of mtDNA after IR. C57BL/6 mice were exposed to 0, 1.5, 3, 6, 8, or 10 Gy total body irradiation; thereafter, plasma mtDNA was assessed with samples collected at 3, 6, 9, 15, 24, 48, 72, or 168 h. We found that: (1) the designed probesets were specific for mtDNA extracted from the liver, and they recognized the small amount of mtDNA mixed in the nDNA; (2) plasma mtDNA exhibited a statistically significant increase only at 6 h after 8 Gy irradiation. The alteration of mtDNA was not dose-dependent or time-dependent; hence, it is unlikely to be an effective biodosimeter.

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Pubmed
Breaking the mirror: pH-controlled chirality generation from a meso ligand to a racemic ligand.
Journal: Chemistry (Weinheim an der Bergstrasse, Germany)
February/23/2009
Description

To study the conversion from a meso form to a racemic form of tetrahydrofurantetracarboxylic acid (H(4)L), seven novel coordination polymers were synthesized by the hydrothermal reaction of Zn(NO(3))(2)6 H(2)O with (2S,3S,4R,5R)-H(4)L in the presence of 1,10-phenanthroline (phen), 2,2'-bipyridine (2,2'-bpy), or 4,4'-bipyridine (4,4'-bpy): [Zn(2){(2S,3S,4R,5R)-L}(phen)(2)(H(2)O)]2 H(2)O (1), [Zn(4){(2S,3R,4R,5R)-L}{(2S,3S,4S,5R)-L}(phen)(2)(H(2)O)(2)] (2), [Zn(2){(2S,3S,4R,5R)-L}(H(2)O)(2)]H(2)O (3), [Zn(4){(2S,3R,4R,5R)-L}{(2S,3S,4S,5R)-L} (2,2'-bpy)(2)(H(2)O)(2)]2 H(2)O (4), [Zn(2) {(2S,3S,4R,5R)-L}(2,2'-bpy)(H(2)O)] (5), [Zn(4){(2S,3R,4R,5R)-L}{(2S,3S,4S,5R)-L} (4,4'-bpy)(2)(H(2)O)(2)] (6), and [Zn(2) {(2S,3S,4R,5R)-L}(4,4'-bpy)(H(2)O)] 2 H(2)O (7). These complexes were obtained by control of the pH values of reaction mixtures, with an initial of pH 2.0 for 1, 2.5 for 2, 4, and 6, and 4.5 for 3, 5, and 7, respectively. The expected configuration conversion has been successfully realized during the formation of 2, 4, and 6, and the enantiomers of L, (2S,3R,4R,5R)-L and (2S,3S,4S,5R)-L, are trapped in them, whereas L ligands in the other four complexes retain the original meso form, which indicates that such a conversion is possibly pH controlled. Acid-catalyzed enol-keto tautomerism has been introduced to explain the mechanism of this conversion. Complex 1 features a simple 1D metal-L chain that is extended into a 3D supramolecular structure by pi-pi packing interactions between phen ligands and hydrogen bonds. Complex 2 has 2D racemic layers that consist of centrosymmetric bimetallic units, and a final 3D supramolecular framework is formed by the interlinking of these layers through pi-pi packing interactions of phen. Complex 3 is a 3D metal-organic framework (MOF) involving meso-L ligands, which can be regarded as (4,6)-connected nets with vertex symbol (4(5).6)(4(7).6(8)). Complexes 4 and 5 contain 2D racemic layers and (6,3)-honeycomb layers, respectively, both of which are combined into 3D supramolecular structures through pi-pi packing interactions of 2,2'-bpy. The structure of complex 6 is a 2D network formed by 4,4'-bpy bridging 1D tubes, which consist of metal atoms and enantiomers of L. These layers are connected through hydrogen bonds to give the final 3D porous supramolecular framework of 6. Complex 7 is a 3D MOF with novel (3,4,5)-connected (6(3))(4(2).6(4))(4(2).6(6).8(2)) topology. The thermal stability of these compounds was also investigated.

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Self-assembling peptide for co-delivery of HIV-1 CD8+ T cells epitope and Toll-like receptor 7/8 agonists R848 to induce maturation of monocyte derived dendritic cell and augment polyfunctional cytotoxic T lymphocyte (CTL) response.
Journal: Journal of controlled release : official journal of the Controlled Release Society
July/29/2016
Description

Peptide based vaccine that incorporates one or several highly conserved CD8+ T cells epitopes to induce potent cytotoxic T lymphocyte (CTL) response is desirable for some infectious diseases, such as HIV-1 (human immunodeficiency virus-1), and cancers. However, the CD8+ T cells epitope is often weakly immunogenic, and thus requires a specific adjuvant or delivery system to enhance the efficiency. Here we investigated the use of self-assembling peptide EAK16-II based platform to achieve the co-delivery of CD8+ T cells epitope and TLR7/8 agonists (R848 or R837) for augmenting DCs maturation and HIV-1 specific CTL response. HIV-1 CTL epitope SL9 was conjugated with EAK16-II to obtain SL9-EAK16-II, which further spontaneously co-assembled with R848 or R837 in aqueous solution, forming co-assembled nanofibers. Fluorescence spectra and calorimetrical titration revealed the interaction between SL9-EAK16-II assemblies and R848 or R837 via hydrogen bonding and hydrophobic interaction, with the binding affinity (dissociation constant Kd) of 0.62μM or 0.53μM, respectively. Ex vivo generated DCs from HIV-1+ patients pulsed with the SL9-EAK16-II/R848 nanofibers stimulated significantly more polyfunctional SL9 specific CTLs, compared to the DCs pulsed with SL9 alone or the mixture of SL9 and TLR agonist. Furthermore, the nanofibers elicited stronger SL9 specific CTL response in vaccinated mice. Our findings suggest the self-assembling peptide EAK16-II might be used as a new delivery system for peptide based vaccines.

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Aqueous solution-processed GeO2: an anode interfacial layer for high performance and air-stable organic solar cells.
Journal: ACS applied materials & interfaces
June/15/2014
Description

A simple and cheap method for depositing solution-processed GeO2 (sGeO2) film is proposed utilizing the weak solubility of GeO2 in water. X-ray photoelectron spectroscopy analysis reveals that a pure GeO2 thin film can be formed by casting its aqueous solution. This method can avoid the difficulty of vacuum evaporation by its high melting point. The sGeO2 film has been used successfully as an anode interfacial layer in poly(3-hexylthiophene) (P3HT) and indene-C60 bisadduct (IC60BA)-based bulk heterojunction organic solar cells with improved power conversion efficiency and device stability compared with that using conventional poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS); the improvement of the power conversion efficiency and the device stability are estimated to be 9% and 50%, respectively. The calculations of optical intensity in a whole cell demonstrate that a thin layer of sGeO2 could function as an optical spacer in the based bulk heterojunction (BHJ) organic solar cells (OSCs) for enhancing the light harvesting in the active layer. Interfacial evaluation by impedance spectroscopy shows that the sGeO2-based cell exists less charge carrier recombination and lower contact resistance. More importantly, the sGeO2 film processing is very simple and environmentally friendly, which has potential applications in green and low-cost organic electronics in the future.

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Preparation and in vitro evaluation of strontium-doped calcium silicate/gypsum bioactive bone cement.
Journal: Biomedical materials (Bristol, England)
May/10/2015
Description

The combination of two or more bioactive components with different biodegradability could cooperatively improve the physicochemical and biological performances of the biomaterials. Here we explore the use of α-calcium sulfate hemihydrate (α-CSH) and calcium silicate with and without strontium doping (Sr-CSi, CSi) to fabricate new bioactive cements with appropriate biodegradability as bone implants. The cements were fabricated by adding different amounts (0-35 wt%) of Sr-CSi (or CSi) into the α-CSH-based pastes at a liquid-to-solid ratio of 0.4. The addition of Sr-CSi into α-CSH cements not only led to a pH rise in the immersion medium, but also changed the surface reactivity of cements, making them more bioactive and therefore promoting apatite mineralization in simulated body fluid (SBF). The impact of additives on long-term in vitro degradation was evaluated by soaking the cements in Tris buffer, SBF, and α-minimal essential medium (α-MEM) for a period of five weeks. An addition of 20% Sr-CSi to α-CSH cement retarded the weight loss of the samples to 36% (in Tris buffer), 43% (in SBF) and 54% (in α-MEM) as compared with the pure α-CSH cement. However, the addition of CSi resulted in a slightly faster degradation in comparison with Sr-CSi in these media. Finally, the in vitro cell-ion dissolution products interaction study using human fetal osteoblast cells demonstrated that the addition of Sr-CSi improved cell viability and proliferation. These results indicate that tailorable bioactivity and biodegradation behavior can be achieved in gypsum cement by adding Sr-CSi, and such biocements will be of benefit for enhancing bone defect repair.

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Control of growth and beyond: a special issue on Hippo signaling.
Journal: Acta biochimica et biophysica Sinica
September/7/2015
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