Yu Zhang
Best match
All
Pubmeds
(6K+)
Pubmed
Journal: Physical review letters
October/29/2016
Abstract
Pristine graphene is strongly diamagnetic. However, graphene with single carbon atom defects could exhibit paramagnetism. Theoretically, the π magnetism induced by the monovacancy in graphene is characteristic of two spin-split density-of-states (DOS) peaks close to the Dirac point. Since its prediction, many experiments have attempted to study this π magnetism in graphene, whereas only a notable resonance peak has been observed around the atomic defects, leaving the π magnetism experimentally elusive. Here, we report direct experimental evidence of π magnetism by using a scanning tunneling microscope. We demonstrate that the localized state of the atomic defects is split into two DOS peaks with energy separations of several tens of meV. Strong magnetic fields further increase the energy separations of the two spin-polarized peaks and lead to a Zeeman-like splitting. Unexpectedly, the effective g factor around the atomic defect is measured to be about 40, which is about 20 times larger than the g factor for electron spins.
Pubmed
Journal: Soft matter
October/10/2017
Abstract
Understanding the morphological transition dynamics related to the hydrophilic-hydrophobic interface has been a challenge due to the lack of an effective evaluation method. Herein, nuclear magnetic resonance spectroscopy was employed to study the morphological transition related chain collapse of poly(N,N'-diethylaminoethylmethacrylate)-b-poly(N-isopropylacrylamide) (PDEAEMA133-b-PNIPA322) and poly(N,N'-dimethylaminoethylmethacrylate)-b-poly(N-isopropylacrylamide) (PDMAEMA95-b-PNIPA228) and was proved to be a powerful technique in morphological transition mechanism studies once combined with dynamic light scattering and transmission electron microscopy. Unlike the cooperative coil collapse of two blocks in the PDMAEMA95-b-PNIPA228 alkaline solution upon heating which induces the assembly of a nanostructure (∼200 nm) with a hydrophobic core containing both collapsed PDMAEMA and PNIPA segments and a hydrophilic surface part consisting of un-shrunk PDMAEMA and PNIPA segments, PDEAEMA133-b-PNIPA322 with a low-temperature core-shell micelle structure showed a micelle-vesicle transition due to temperature-induced inhomogeneous-collapse of PNIPA. The PNIPA segments in the shell sequentially collapse outside (starting at the core-shell interface), accompanied by a gradual decrease in micelle size. Above the critical temperature, the residual hydrophilic PNIPA segments become too short to stabilize the micelle structure, the micelles then transform into vesicles of a slightly larger size, instead of micelle aggregation and precipitation as normally expected.
Related with
Pubmed
Journal: Guang pu xue yu guang pu fen xi = Guang pu
August/5/2018
Abstract
The pulsed plasma thruster(PPT) is suited for various applications, e. g., attitude control, station keeping and formation flying due to its significant advantage with regard to the related savings of wet system mass,small volume and high specific impulse. In order to elaborate the mechanism of PPT operation process, the optical emission spectrum was conducted on a breech-fed PPT with tongue electrodes. The results show that plasma plume mainly consists of C, F, C+, F+ and C2+, besides Cu+ and Cu2+ were detected in plasma which were produced by electrodes ablation. The plasma distribution is asymmetric in the discharge channel, the maximum of plasma density of plasma appears at the central axis of discharge channel and the plasma density nearby the anode is much higher than that nearby the cathode. The composition of plasma is not symmetric and not uniform. The distribution of F+ and neutral particle concentrate close to the anode. The electron temperature is about 6.67 eV derived from the optical emission spectra by Boltzmann linear fitting. Evolution of plasma emission spectrum was derived at the fourth measurement point, the results show that there is much difference between different discharge stages for the composition of plume and the proportion of each component.
Related with
Pubmed
Journal: Developmental biology
December/27/2004
Abstract
Gata2 is an essential hematopoietic transcriptional factor that is also expressed prominently in the nervous system. The early lethality of knockout mice due to severe anemia has largely precluded studies of gata2 neural regulation and function. In this report, we describe the identification of zebrafish Pur alpha and Sp8 orthologs as two factors that function to regulate neuronal expression of gata2. During embryogenesis, Pur alpha is expressed widely, whereas Sp8 has an overlapping pattern of expression with gata2 in the nervous system. Knockdown and ectopic expressions of Pur alpha and Sp8 indicate that these factors function, respectively, as a repressor and an activator of gata2 gene expression in the nervous system. With consideration given to the previously established roles for these factors, we propose a model for how the transcriptional regulation of neural gata2 expression may be involved in controlling cellular proliferation in the nervous system.
Pubmed
Journal: Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie
August/8/2017
Abstract
In current study, we aimed to reveal the potential antifibrotic effects of oligomeric proanthocyanidin (OPC) from grape seeds on lipopolysaccharide (LPS)-activated, HSC-T6, a rat hepatic stellate cell line. HSC-T6 cells were treated with OPC 1h prior to LPS, and then incubated for indicated time. OPC inhibited cells viability of HSC-T6 cells and decrease protein expression of collagen I, α-smooth muscle actin (α-SMA), tissue inhibitors of metalloproteinases I (TIMP-1) on LPS-induced HSC-T6 cells. OPC also significantly inhibited phosphorylation of LPS-stimulated phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). Furthermore, OPC pretreatment blocked LPS-triggered nuclear factor-kappa B (NF-κB) translocation from cytosol to nuclear. OPC, as well as specific inhibitors of NF-κB, PI3K and JNK could effectively inhibited α-SMA and collagen I expression. In conclusion, we demonstrated that the anti-fibrotic mechanism of OPC might be involved the inhibition of HSC activation and transdifferentiation by suppressing NF-κB activation through JNK/ERK MAPK and PI3K/Akt phosphorylation. Thus, OPC possesses the potential inhibitory property of HSC activation through NF-κB modulation involving MAPK-PI3K/AKT pathways.
Pubmed
Journal: Biochimica et biophysica acta. General subjects
September/19/2018
Abstract
Protein misfolding and aggregation are associated with amyloidosis. The toxic aggregation of amyloid-β 1-42 (Aβ42) may disrupt cell membranes and lead to cell death and is thus regarded as a contributing factor in Alzheimer's disease (AD). 1,4-naphthoquinone (NQ) has been shown to exhibit strong anti-aggregation effects on amyloidogenic proteins such as insulin and α-synuclein; however, its high toxicity and poor solubility limit its clinical application. Menadione sodium bisulfite (MSB, also known as vitamin K3), is used clinically in China to treat hemorrhagic diseases caused by vitamin K deficiency and globally as a vitamin K supplement. We hypothesized that MSB could inhibit amyloid formation since its backbone structure is similar to NQ. To test our hypothesis, we first investigated the effects of MSB on Aβ42 amyloid formation in vitro. We found that MSB inhibited Aβ42 amyloid formation in a dose dependent manner, delayed the secondary structural conversion of Aβ42 from random coil to ordered β-sheet, and attenuated the ability of Aβ42 aggregates to disrupt membranes; moreover, the quinone backbone rather than lipophilicity is esstial for the inhibitory effects of MSB. Next, in cells expressing a pathogenic APP mutation (Osaka mutation) that results in the formation of intraneuronal Aβ oligomers, MSB inhibited the intracellular aggregation of Aβ. Moreover, MSB treatment significantly extended the life span of Caenorhabditis elegans CL2120, a strain that expresses human Aβ42. Together, these results suggest that MSB and its derivatives may be further explored as potential therapeutic agents for the prevention or treatment of AD.
Related with
Pubmed
Journal: Journal of affective disorders
July/15/2017
Abstract
To explore the associated factors of late-onset post-stroke depression (PSD).
A total of 251 patients with acute ischemic stroke were recruited. The evaluation of depression was performed 2 weeks after ischemia. 206 patients showing no depression in 2 weeks were followed up. They were divided into late-onset PSD group and non-depressed group by clinical interview with Hamilton depression scale score 3 months after stroke. On the first day following hospitalization, the clinical data including age, gender, educational level and vascular risk factors were recorded. The severity, etiological subtype and location of stroke were evaluated. The inflammatory mediators, glucose and lipid levels were recorded on the day of admission. The association between clinical factors and late-onset PSD was explored by logistic regression analysis. The ROC analysis was performed to evaluate the predicting power of the clinical factors.
187 of 206 patients completed the assessment 3 months after stroke. 19 (10.16%) patients were diagnosed as late onset PSD. Diabetes mellitus was an independent risk factor for late-onset PSD (OR 2.675, p = 0.047). ROC analysis demonstrated that glucose and HbA1C could predict late-onset PSD with specificity of 84.4%.
The sample of our study was small. The results should be further confirmed in a larger cohort of patients with acute ischemic stroke.
The acute ischemic stroke patients with diabetes mellitus were more tendered to suffer late-onset PSD.
Pubmed
Journal: Environmental science & technology
November/6/2012
Abstract
A full-scale biosystem consisting of two anaerobic reactors (HA and BF1) and four aerobic ones (BF2-BF4 and OD) in succession and receiving antibiotic-bearing (mainly streptomycin) wastewater was used for studying the impacts of antibiotics on microbial community structures. Significant decreases of streptomycin (from 3955 ± 1910 to 23.1 ± 4.7 μg L(-1)) and COD(Cr) were observed along the treatment process. Cloning results show that the anaerobic reactors (HA and BF1) were dominated with Deltaproteobacteria (51%) mainly affiliated with sulfate-reducing bacteria (SRB), while the aerobic BF2 receiving streptomycin of 408.6 ± 59.7 μg L(-1) was dominated with Betaproteobacteria (34%), Deltaproteobacteria (31%) and Bacteroidetes (14%). Gammaproteobacteria (15.9-22.4%), Betaproteobacteria (10.0-20.3%), and Bacteroidetes (4.5-29.7%) became the major bacterial groups in aerobic BF3-OD receiving streptomycin of ≤83 ± 13 μg L(-1). Archaea affiliated with Methanomethylovorans hollandica-like methylotroph was abundant in HA and BF1 (archaea/bacteria, 0.54-0.40; based on specific gene copy number), suggesting the coexistence of SRB and methanogens in degrading pollutants. Fungi were abundant (fungi/bacteria, 0.15; based on specific gene copy number) with the dominance of Ascomycota (clone ratio of Ascomycota/eukarya, 25.5%) in BF2, suggesting that fungi could be an important player in pollutant removal under high levels of antibiotics. This study demonstrates that under high antibiotic levels, wastewater treatment communities may maintain system stability through adjusting bacterial, archaeal, and eukaryal compositions.
Pubmed
Journal: The American journal of clinical nutrition
November/19/2017
Pubmed
Journal: Journal of the American Chemical Society
June/25/2007
Abstract
The asymmetric catalytic aziridination reaction (AZ reaction) of N-dianisylmethylimines (N-DAM-imines) with ethyl diazoacetate is developed with chiral catalysts prepared from triphenylborate and both the vaulted binaphthol (VANOL) and vaulted biphenanthrol (VAPOL) ligands. Catalysts derived from both ligands were equally effective in terms of asymmetric induction, but the VANOL catalyst was slightly faster. Up to 400 turnovers could be achieved with the VANOL catalyst while still maintaining>or=90% ee in the aziridine product. The ligand could be recovered in 95% yield with no loss in optical purity. Excellent asymmetric inductions were observed with arylimines, and although slightly lower inductions were observed for alkyl-substituted imines, the optical purity of the aziridines from all of the imine substrates could be enhanced to>or=99% ee with a single crystallization. Methods were developed for deprotection of the N-DAM-aziridines under acidic conditions without causing an acid-promoted opening of the ring. Excellent yields of the N-H-aziridines could be obtained with both alkyl- and aryl-substituted aziridines. Finally, activation of the N-H-aziridines was achieved with Boc, tosyl, and Fmoc groups. The activated aziridines can be converted to beta3-amino esters, and unexpectedly, the N-Boc-protected aziridine-2-carboxylate 16b with a phenyl substituent in the 3-position cis to the ester group was found to undergo ring expansion to a mixture of cis- and trans-oxazolidinones.
Pubmed
Journal: Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica
September/24/2017
Abstract
The present study aims to investigate the effects of Xuesaitong (XST)injection on inflammation induced by OGD/reoxygenation in BV2 microglia cell and explore the underlying mechanisms.The effects of XST injection were evaluated in terms of cell viability, secretion of TNF-α, IL-1β, IL-6 and IL-10 into culture media, protein expression of p-ERK1/2, p-JNK and p-p38, and nuclear translocation of NF-κB p65. The results showed that XST injection significantly increased cell viability, suppressed release of TNF-α, IL-1β, IL-6 and IL-10 and down-regulated p-JNK1/2 and p-p38 MAPK expression in BV2 microglia cells induced by OGD/R injury, whereas it had no effect on p-ERK1/2 expression. Furthermore, XST injection suppressed nuclear translocation of NF-κB p65 in BV2 microglia after OGD/R injury. These data indicate that the neuroprotective effects of XST injection on OGD/R injury are associated with its inhibition of pro-inflammatory mediator production, down-regulation of JNK1/2 and p38 MAPK activation, and suppression of NF-κB p65 nuclear translocation in BV2 microglia cells.
Pubmed
Journal: Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences
October/16/2017
Abstract
OBJECTIVE
To analyze the results and follow up data of screening for newborn organic aciduria in Zhejiang province.
METHODS
The results and follow-up data of 1 861 262 newborns from Zhejiang province undergoing screening for organic aciduria during January 2009 and December 2016 were retrospectively analyzed. The acylcarnitine spectrum in urine samples was detected by tandem mass spectrum (MS/MS) and the positive patients were confirmed by urine gas chromatography mass spectrometry and/or gene analysis.
RESULTS
Ninety two cases of organic aciduria were confirmed with a prevalence of 1:20 200. Among 40 cases of methylmalonic academia (MMA), 13 (32.5%) were of MMA simple type and 27 (67.5%) were combined type. Genetic analysis showed 6 cases of MUT type and 1 case of CblB type out of 7 patients with MMA simple type, 10 cases of CblC and 1 case of CblF out of 11 patients with combined type, respectively. Six patients had propionic academia with a prevalence of 1:310 200, 7 had isovaleric academia (1:265 900), 6 had glutaric academia type 1 (1:310 200), 27 had 3-methylcrotonyl-CoA carboxylase deficiency (MCC, 1:68 900), 1 had 3-hydroxy-3-methylglutaric aciduria (1:1 861 300), 2 had β-ketothiolase deficiency (1:960 600), and 3 had biotinidase deficiency/holocarboxylase synthetase deficiency (1:620 400). Thirty-one patients had a disease onset at neonatal period, and 15 at post-neonatal period. Thirty-three patients had brain involvements or cranial imaging disorders. Three patients with MMA had kidney diseases or heomlytic uremic syndrome, and 3 had myocardial impairments. Twenty patients died during the follow-up.
CONCLUSIONS
MMA is the most common newborn organic aciduria in Zhejiang province. Except MCC, most organic aciduria may lead to metabolism decompensation, complications or even death.
Pubmed
Journal: The lancet. HIV
July/1/2017
Pubmed
Journal: NeuroRehabilitation
September/25/2013
Abstract
OBJECTIVE
To explore the role of rs11053646 polymorphism of oxidized low-density lipoprotein receptor 1 (OLR-1) gene in the susceptibility and prognosis of ischemic stoke (IS).
METHODS
A total of 304 IS patients and 377 age and sex-matched healthy controls were recruited. Patients were followed up for 6 months for recovery evaluation of stroke. Genotyping analyses of the rs11053646 G > C polymorphisms of OLR1 gene were performed.
RESULTS
The genotype frequencies and alleles frequencies at rs11053646 were significantly differed between stroke subjects and control subjects (both P < 0.001). The presence of CC genotype was significantly higher in IS subjects than in controls (38% vs. 25%, P = 0.001). Similarly, the C allele carriage in IS was significantly higher than controls (59% vs. 49%, P < 0.001). Regression analysis showed the CC homozygote had a significantly increased risk for stroke (adjusted OR = 2.080; P = 0.001). The genotype of rs11053646 were not associated with the IS subtype and severity at admission, but determine the clinical outcome at 6 months after discharge from hospital.
CONCLUSIONS
The rs11053646 polymorphism of OLR1 gene be used as a molecular marker for the susceptibility and prognosis of IS in Chinese population.
Pubmed
Journal: Environmental science and pollution research international
November/8/2017
Abstract
Inland rivers play a key role in supplying water for domestic and agricultural purposes in Asian arid inland basin. This paper investigates the chemical composition of precipitation, river water, and groundwater, providing evidence for the influencing factors the water composition in the Shiyang River Basin. Water samples were collected and analyzed to determine the content of major cations (Ca2+, Mg2+, Na+, K+, and NH+ 4) and anions (HCO- 3, Cl-, NO- 3, NO- 2, F-, and SO2-4), total solid solubility, and pH values. The results showed that precipitation, surface water, and groundwater were mildly alkaline. Ca2+ and SO2-4 were the predominant ions. The content of inorganic ions varied largely in the different seasons, with the highest ion concentration observed in spring and the lowest in summer. The seasonal variations in groundwater were less considerable than those in surface water. Furthermore, anion concentrations increased substantially from upstream to downstream. Regional weathering of carbonates and evaporation were established as the major sources of these ions. In addition, we discovered that anthropogenic inputs had led to light pollution of water in some residential districts.
Pubmed
Journal: Journal of chromatography. A
October/16/2014
Abstract
In this work, we proposed a simple co-mixing method to fabricate magnetic molecularly imprinted polymers (magnetic MIPs). MIPs were commercial products while magnetic nanoparticles (MNPs) were prepared by chemical oxidation and solvothermal methods. When MNPs and MIPs (with mass ratio 1:1) were co-mixed and vortexed evenly in methanol, they could assemble into magnetic composites spontaneously and thus be magnetically separable. To testify the feasibility of the magnetic composites in sample preparation, the resultant magnetic MIPs were applied as sorbents for magnetic solid-phase extraction (MSPE) of fluoroquinolones (FQs) in milk samples. Under optimized conditions, a rapid, convenient, and efficient method for the determination of three FQs in milk samples was established by magnetic MIPs based MSPE coupling with high performance liquid chromatography with ultraviolet detector (HPLC-UV). The limits of detection (LODs) for three FQs were found to be 1.8-3.2ng/g. The intra- and inter-day relative standard deviations (RSDs) were less than 9.5% and 12.5%, respectively. The recoveries of FQs for two spiked milk samples were in the range from 94.0% to 124.4% with the RSDs less than 11.6%.
Pubmed
Journal: International immunopharmacology
April/24/2011
Abstract
The type-1 insulin-like growth factor receptor (IGF-1R) is one member of tyrosine protein kinase receptor family. It is a causal factor for tumor initiation, development and frequently overactivated in a variety of human malignancies, including endometrial carcinoma. To investigate its possibility as a therapeutic target for endometrial carcinoma, we adopted RNA interference technology to down-regulate IGF-1R expression in endometrial carcinoma and analyzed its apoptosis inductive effect and tumorigenicity in vivo. Results showed that RNAi mediated down-regulation of IGF-1R expression in endometrial carcinoma significantly induced apoptosis, reduced downstream protein phosphorylation and decreased tumorigenicity in vivo accompanied with lower proliferation index in tumor tissue, Which implied the therapeutic potential of RNAi in the treatment of endometrial carcinoma by targeting IGF-1R and IGF-1R may be a potential therapeutic target for human endometrial carcinoma.
Pubmed
Journal: The journal of physical chemistry. A
September/23/2010
Abstract
The difference of the properties between the blue-shifting halogen bond and the blue-shifitng hydrogen bond has been investigated at the M06/6-311++G(d,p) theory level. It was found that the three lone electron pairs on the halogen atom play an important role for the difference of the properties between the blue-shifting halogen bond and the blue-shifitng hydrogen bond. The additional electron-density transfer from the three lone electron pairs on the halogen atom to the remote part of the halogen atom donor (i.e., the antibonding orbitals of the bonds other than X-Hal) makes the blue-shifting halogen bond much more ubiquitous in the halogen-bonded complexes than the blue-shifitng hydrogen bond in the hydrogen-bonded complexes, and it also makes the values of the X-Hal bond contraction generally much larger than the values of the X-H bond contraction. The difference of the properties between the X-Cl...Y blue-shifting halogen bond and the X-Br...Y blue-shifting halogen bond was also discussed.
Pubmed
Journal: Journal of molecular modeling
September/19/2012
Abstract
Theoretical studies of a new ion-pair receptor, meso-octamethylcalix[4]pyrrole (OMCP), and its interactions with the halide anions F(-), Cl(-), and Br(-) and the cesium halides CsF, CsCl, and CsBr have been performed. Geometries, binding energies, and binding enthalpies were evaluated with the restricted hybrid Becke three-parameter exchange functional (B3LYP) method using the 6-31+G(d) basis set and relativistic effective core potentials. The optimized geometric structures were used to perform natural bond orbital (NBO) analysis. The two typical types of hydrogen bonds, N-H…X(-) and C-H…X(-), were investigated. The results indicate that hydrogen bonding interactions are dominant, and that the halide anions (F(-), Cl(-), and Br(-)) offer lone pair electrons to the σ*(N-H) or σ*(C-H) antibonding orbitals of OMCP. In addition, electrostatic interactions between the lone pair electrons of the halide anion and the LP* orbitals of Cs(+) as well as cation-π interactions between the metal ion and π-orbitals of the pyrrole rings have important roles to play in the Cs(+)•OMCP•X(-) complexes. The current study further demonstrates that this easy-to-make OMCP host compound functions as not only an anion receptor but also an ion-pair receptor.
Pubmed
Journal: Wei sheng wu xue bao = Acta microbiologica Sinica
November/7/2013
Abstract
OBJECTIVE
In order to study the role of porcine CD151 in infection of porcine cells by porcine reproductive and respiratory syndrome virus (PRRSV), we established a porcine CD151 transgenic PK-15 cell line.
METHODS
The full-length complementary DNA (cDNA) for porcine CD151 was amplified from porcine alveolar macrophages by reverse transcription-polymerase chain reaction (RT-PCR), and subcloned into eukaryotic expression vector pcDNA3. The recombinant vector pcDNA-CD151 was transfected into PK-15 cells and the transgenic cell line was generated after G418 selection. Transcription of the CD151 cDNA in transgenic cell line was detected by RT-PCR and immunofluorescence. The cell line, together with control cell lines PK-15, 3D4-CD163 and MARC-145, was infected with PRRSV, and the viral RNA genome or antigens in the infected cells was detected by RT-PCR or immunofluorescence. At different time points post-infection, the virus was harvested and titrated on MARC-145 cells.
RESULTS
The expected size of porcine CD151 cDNA was amplified with a sequence identity of 99.7% to the published sequence. From the pcDNA-CD151-transfected cell culture, a transgenic cell line PK15-CD151 was generated and correct expression of porcine CD151 was confirmed. After PRRSV infection, the viral RNA genome and antigens were detected in the cell-line. Although apparent cytopathic effect was not observed in the virally infected cell line, the infectious virus with a high viral title was detected. The cell line had been passed for more than 30 generations and no significant difference in viral title was observed among generations 10, 20 and 30 after PRRSV infection.
CONCLUSIONS
Transfection of non-permissive PK-15 cells with porcine CD151 cDNA conferred the susceptibility to PRRSV infection, indicating an important role of the porcine CD151 in PRRSV infection of porcine cells.
Pubmed
Journal: Phytochemistry
June/20/2012
Abstract
Four vobasinyl-ibogan type bisindole alkaloids, ervachinines A-D (1-4), along with 12 known terpenoid indole alkaloids, were isolated from the whole plant of Ervatamia chinensis. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR, and the absolute configurations of 1-4 were determined by CD exciton chirality method. All of the compounds were evaluated for in vitro cytotoxicity against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480. Bisindole alkaloids 1-6 exhibited inhibitory effects, with IC(50) values comparable to those of cisplatin.
Pubmed
Journal: Analytical and bioanalytical chemistry
June/18/2012
Abstract
In this paper we describe a multiplex time-reducing quantitative polymerase chain reaction (qPCR) method for determination of telomere length. This multiplex qPCR assay enables two pairs of primers to simultaneously amplify telomere and single copy gene (albumin) templates, thus reducing analysis time and labor compared with the previously established singleplex assay. The chemical composition of the master mix and primers for the telomere and albumin were systematically optimized. The thermal cycling program was designed to ensure complete separation of the melting processes of the telomere and albumin. Semi-log standard curves of DNA concentration versus cycle threshold (C (t)) were established, with a linear relationship over an 81-fold DNA concentration range. The well-performed intra-assay (RSD range 2.4-4.7%) and inter-assay (RSD range: 3.1-5.0%) reproducibility were demonstrated to ensure measurement stability. Using wild-type, Lewis lung carcinoma and H22 liver carcinoma C57BL/6 mouse models, significantly different telomere lengths among different DNA samples were not observed in wild-type mice. However, the relative telomere lengths of the tumor DNA in the two strains of tumor-bearing mice were significantly shorter than the lengths in the surrounding non-tumor DNA of tumor-bearing mice and the tissue DNA of wild-type mice. These results suggest that the shortening of telomere lengths may be regarded as an important indicator for cancer control and prevention. Quantification of telomere lengths was further confirmed by the traditional Southern blotting method. This method could be successfully used to reduce the time needed for rapid, precise measurement of telomere lengths in biological samples.
Pubmed
Journal: Organic letters
June/28/2009
Abstract
A new alkaloid, daphenylline (1), with an unprecedented rearranged 22-nor-calyciphylline skeleton, was isolated from the fruits of Daphniphyllum longeracemosum. Its structure and stereochemistry were elucidated on the basis of spectroscopic and computational approaches. A plausible biosynthetic pathway of 1 was also proposed.
Pubmed
Journal: The journal of physical chemistry. B
September/9/2007
Abstract
An ultrathin poly(tetrafluoroethylene) (PTFE)-reinforced multilayer self-humidifying composite membrane (20 microm, thick) is developed. The membrane is composed of Nafion-impregnated porous PTFE composite as the central layer, and SiO2 supported nanosized Pt particles (Pt-SiO2) imbedded into the Nafion as the two side layers. The proton exchange membrane (PEM) fuel cell employing the self-humidifying membrane (Pt-SiO2/NP) turns out a peak power density of 1.40 W cm(-2) and an open circuit voltage (OCV) of 1.032 V under dry H2/O2 condition. The excellent performance is attributed to the combined result of both the accelerated water back-diffusion in the thin membrane and the adsorbing/releasing water properties of the Pt-SiO2 catalyst in the side layers. Moreover, the inclusion of the hygroscopic Pt-SiO2 catalyst inside the membrane results in an enhanced anode self-humidification capability and also the decreased cathode polarization (accordingly an improved cell OCV). Several techniques, such as transmission electronic microscopy, scanning electronic microscopy, energy dispersive spectroscopy, thermal analysis and electrochemical impedance spectroscopy etc., are employed to characterize the Pt-SiO2/NP membrane. The results are discussed in comparison with the plain Nafion/PTFE membrane (NP). It is established that the reverse net water drag (from the cathode to the anode) across the Pt-SiO2/NP membrane reaches 0.16 H2O/H+. This implies a good hydration of the Pt-SiO2/NP membrane and thus ensures an excellent PEM fuel cell performance under self-humidification operation.
load more...