| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 2. |
- Wang, Zhaoming, et al.
(författare)
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Imputation and subset-based association analysis across different cancer types identifies multiple independent risk loci in the TERT-CLPTM1L region on chromosome 5p15.33
- 2014
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:24, s. 6616-6633
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have mapped risk alleles for at least 10 distinct cancers to a small region of 63 000 bp on chromosome 5p15.33. This region harbors the TERT and CLPTM1L genes; the former encodes the catalytic subunit of telomerase reverse transcriptase and the latter may play a role in apoptosis. To investigate further the genetic architecture of common susceptibility alleles in this region, we conducted an agnostic subset-based meta-analysis (association analysis based on subsets) across six distinct cancers in 34 248 cases and 45 036 controls. Based on sequential conditional analysis, we identified as many as six independent risk loci marked by common single-nucleotide polymorphisms: five in the TERT gene (Region 1: rs7726159, P = 2.10 × 10(-39); Region 3: rs2853677, P = 3.30 × 10(-36) and PConditional = 2.36 × 10(-8); Region 4: rs2736098, P = 3.87 × 10(-12) and PConditional = 5.19 × 10(-6), Region 5: rs13172201, P = 0.041 and PConditional = 2.04 × 10(-6); and Region 6: rs10069690, P = 7.49 × 10(-15) and PConditional = 5.35 × 10(-7)) and one in the neighboring CLPTM1L gene (Region 2: rs451360; P = 1.90 × 10(-18) and PConditional = 7.06 × 10(-16)). Between three and five cancers mapped to each independent locus with both risk-enhancing and protective effects. Allele-specific effects on DNA methylation were seen for a subset of risk loci, indicating that methylation and subsequent effects on gene expression may contribute to the biology of risk variants on 5p15.33. Our results provide strong support for extensive pleiotropy across this region of 5p15.33, to an extent not previously observed in other cancer susceptibility loci.
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| 3. |
- Chen, Geng, et al.
(författare)
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Experimental Test of the State Estimation-Reversal Tradeoff Relation in General Quantum Measurements
- 2014
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Ingår i: Physical Review X. - 2160-3308. ; 4:5, s. 021043-
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Tidskriftsartikel (refereegranskat)abstract
- When a measurement has limited strength, only partial information, regarding the initial state, is extracted, and, correspondingly, there is a probability to reverse its effect on the system and retrieve the original state. Recently, a clear and direct quantitative description of this complementary relationship, in terms of a tradeoff relation, was developed by Y. K. Cheong and S. W. Lee. [Phys. Rev. Lett. 109, 150402 (2012)]. Here, this tradeoff relation is experimentally verified using polarization-encoded single photons from a quantum dot. Measurement operators representing a complete range, from not affecting the system to a projection to a single polarization state, are realized. In addition, for each measurement operator, an optimal reversal operator is also implemented. The upper bound of the tradeoff relation is mapped to experimental parameters representing the measurement strength. Our results complement the theoretical work and provide a hands-on characterization of general quantum measurements.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Zhang, Xingxing, et al.
(författare)
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Socio-economic performance of a novel solar photovoltaic/loop-heat-pipe heat pump water heating system in three different climatic regions
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 135, s. 20-34
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Tidskriftsartikel (refereegranskat)abstract
- This paper aimed to study the socio-economic performance of a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump water heating system for application in three different climatic regions, namely, cold area represented by London, warm area represented by Shanghai, and hot (subtropical) area represented by Hong Kong. This study involved prediction of the annual fossil-fuel energy saving, investment return period and carbon emission reduction of the new system against the traditional gas-fired and electrical boilers based water heating systems. An established dynamic model developed by the authors was utilised to predict the system’s energy performance throughout a year in the three climatic regions. A life-cycle analytical model was further developed to analyse the economic and environmental benefits of the new system relative to the traditional systems. Analyses of the modelling results drew out several conclusive remarks: (1) the system could achieve the highest energy efficiency when operating at the hot (subtropical) climatic region (represented by Hong Kong), enabling the heat output of as high as 922 kW h/m2 yr and water temperature of above 45 °C, while the grid power input is only 59 kW h/m2 yr; (2) the system is worth for investment when operating at the high energy charging tariff area (represented by London), with the cost payback periods of 8 and 5 years relative to the traditional gas-fired and electrical boilers based systems, respectively; (3) the system could obtain the most promising environmental benefits when operating in Shanghai where the energy quality (embodied carbon volume of per kW h energy) is relatively poor, enabling reduction in life-cycle carbon emissions of around 4.08 tons/m2 and 17.87 tons/m2 respectively, relative to the gas-fired and electrical boilers. Answer to such a question on which area is most suitable for the system application is highly dependent upon the priority order among the three dominating factors: (1) energy efficiency, (2) economic revenue, and (3) environmental benefit, which may vary with the users, local concerns and policy influence, etc. The research results will be able to assist in decision making in implementation of the new PV/thermal technology and analyses of the associated economic and environmental benefits, thus contributing to realisation of the regional and global targets on fossil fuel energy saving and environmental sustainability.
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| 9. |
- Abazov, V. M., et al.
(författare)
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High mass exclusive diffractive dijet production in p(p)over-bar collisions at root s=1.96 TeV
- 2011
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 705:3, s. 193-199
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Tidskriftsartikel (refereegranskat)abstract
- We present evidence for diffractive exclusive dijet production with an invariant dijet mass greater than 100 GeV in data collected with the DO experiment at the Fermilab Tevatron Collider. A discriminant based on calorimeter information is used to measure a significant number of events with little energy (typically less than 10 GeV) outside the dijet system, consistent with the diffractive exclusive dijet production topology. The probability for these events to be explained by other dijet production processes is 2 x 10(-6), corresponding to a 4.7 standard deviation significance.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Duan, Chen, et al.
(författare)
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Comparative analysis of gene expression profiles between primary knee osteoarthritis and an osteoarthritis endemic to Northwestern China, Kashin-Beck disease.
- 2010
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Ingår i: Arthritis and Rheumatism. - : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 62:3, s. 771-780
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the differences in gene expression profiles of adult articular cartilage from patients with Kashin-Beck disease (KBD) versus those with primary knee osteoarthritis (OA).METHODS: The messenger RNA expression profiles of articular cartilage from patients with KBD, diagnosed according to the clinical criteria for KBD in China, were compared with those of cartilage from patients with OA, diagnosed according to the Western Ontario and McMaster Universities OA Index. Total RNA was isolated separately from 4 pairs of the KBD and OA cartilage samples, and the expression profiles were evaluated by Agilent 4x44k Whole Human Genome density oligonucleotide microarray analysis. The microarray data for selected transcripts were confirmed by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) amplification.RESULTS: For 1.2 x 10(4) transcripts, corresponding to 58.4% of the expressed transcripts, 2-fold changes in differential expression were revealed. Expression levels higher in KBD than in OA samples were observed in a mean + or - SD 6,439 + or - 1,041 (14.6 + or - 2.4%) of the transcripts, and expression levels were lower in KBD than in OA samples in 6,147 + or - 1,222 (14.2 + or - 2.8%) of the transcripts. After application of the selection criteria, 1.85% of the differentially expressed genes (P < 0.001 between groups) were detected. These included 233 genes, of which 195 (0.4%) were expressed at higher levels and 38 (0.08%) were expressed at lower levels in KBD than in OA cartilage. Comparisons of the quantitative RT-PCR data supported the validity of our microarray data.CONCLUSION: Differences between KBD and OA cartilage exhibited a similar pattern among all 4 of the pairs examined, indicating the presence of disease mechanisms, mainly chondrocyte matrix metabolism, cartilage degeneration, and apoptosis induction pathways, which contribute to cartilage destruction in KBD.
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| 14. |
- Gao, Ying, et al.
(författare)
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Optical Multi-Level Signal Generation Using Four-Wave-Mixing
- 2011
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 29:14, s. 2166-2172
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Tidskriftsartikel (refereegranskat)abstract
- We propose and demonstrate a novel optical method to generate multi-level signals with reduced driving voltage through degenerate four-wave mixing processes. With the present approach, it is possible to extend the size of the signal constellations and at the same time reduce the modulator driving voltage without bandwidth degradations. In our experiments, one amplitude shift keying (ASK) signal and one differential phase shift keying (DPSK) signal are used to generate one ASK-DPSK signal with clearly opened eye-diagrams and error-free demodulation results. Our numerical simulations show that the proposed method is applicable for generating several 8-ary and 16-ary quadrature amplitude modulation (QAM) signals with silicon waveguides at a higher modulation baud rate.
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| 15. |
- Lei, Ying, et al.
(författare)
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Enhanced airway smooth muscle cell thromboxane receptor signaling via activation of JNK MAPK and extracellular calcium influx.
- 2011
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 650:2-3, s. 629-638
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Tidskriftsartikel (refereegranskat)abstract
- Thromboxane is a key inflammatory mediator and potent airway constrictor. It acts on thromboxane A(2) (TP) receptors and contributes to airway inflammation and airway hyperresponsiveness that is the characteristic feature of asthma. The present study was designed to study TP receptor signaling in airway smooth muscle cells by using an organ culture model and a set of selective pharmacological inhibitors for mitogen-activated protein kinase (MAPK) and calcium signal pathways. Western-blot, immunohistochemistry, myograph and a selective TP receptor agonist U46619 were used for examining TP receptor signal proteins and function. Organ culture of rat bronchial segments for up to 48h induces a time-dependently increased airway contractile response to U46619. This indicates that organ culture increases TP receptor signaling in the airway smooth muscle cells. The enhanced bronchial contraction was attenuated by the inhibition of c-Jun N-terminal kinase (JNK) MAPK activity, chelation of extracellular calcium and calcium channel blocker nifedipine, suggesting that JNK MAPK activity and elevated intracellular calcium level are required for the TP receptor signaling. In conclusion, airway smooth muscle cell TP receptor signaling occurs via JNK MAPK activity and the elevation of extracellular calcium influx, which may provide knowledge for understanding the signaling pathway responsible for the modulation of TP receptor mediated airway hyperresponsiveness to thromboxane.
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| 16. |
- Lei, Ying, et al.
(författare)
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Up-regulation of bradykinin receptors in rat bronchia via IkappaB kinase-mediated inflammatory signaling pathway.
- 2010
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 634:1-3, s. 149-161
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Tidskriftsartikel (refereegranskat)abstract
- IkappaB kinase (IKK)-mediated intracellular signaling mechanisms may be involved in airway hyperresponsiveness through up-regulation of bradykinin receptors. This study was designed to examine if organ culture of rat bronchial segments induces airway hyperresponsiveness to bradykinin and if inhibition of IKK can abrogate the airway hyperresponsiveness to bradykinin via suppressing the expression of bradykinin B(1) and B(2) receptors. Rat bronchi were isolated and cut into ring segments. The segments were then organ cultured in the presence or absence of IKK inhibitors, BMS-345541 or TPCA-1. des-Arg(9)-bradykinin (B(1) receptor agonist) - and bradykinin (B(2) receptor agonist) - induced contractions of the segments were monitored by a sensitive organ bath system. The expression of bradykinin B(1) and B(2) receptors, inflammatory mediators and phosphorylated IKK were studied by a real-time PCR and/or by immunohistochemistry using confocal microscopy. Organ culture of the bronchial segments induced a time-dependent up-regulation of bradykinin B(1) and B(2) receptors. The IKK inhibitors abolished the organ culture-induced up-regulation of bradykinin B(1) and B(2) receptor-mediated contractions in a concentration-dependent manner. This was paralleled with inhibition of IKK activity (phosphorylation), reduced mRNA and protein expressions of bradykinin B(1) and B(2) receptors and decreased mRNA expression of inflammatory mediators (interleukin-6, inducible nitric oxide synthase, cyclooxygenase 2 and matrix metalloproteinase 9). Our results show that organ culture induces IKK-mediated inflammatory changes in airways which subsequently results in airway hyperresponsiveness to bradykinin via the up-regulated bradykinin receptors. Thus, IKK inhibition might be a promising approach for treatment of airway inflammation and airway hyperresponsiveness that are often seen in asthmatic patients.
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| 17. |
- Li, Li, et al.
(författare)
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Reversible Modification of CdSe-CdS/ZnS Quantum Dot Fluorescence by Surrounding Ca2+ Ions
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:19, s. 10424-10433
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Tidskriftsartikel (refereegranskat)abstract
- It has been known for a long time that the fluorescence intensity of colloidal quantum dots (QDs) becomes modified when free ions are added to the QD solution. The consequences of removing free ions from the QD solution, however, have not been closely investigated. In this work we studied fluorescence from 3-mercaptopropionic acid (3-MPA) coated CdSe-CdS/ZnS core-multishell QDs when free Ca2+ ions were added to and subsequently removed from the QD solution. It was found that QD fluorescence intensity was reduced when Ca2+ ions were added to the QD solution, while the wavelength of the QD fluorescence peak remained unchanged. QD fluorescence recovered when the concentration of free Ca2+ ions in the QD solution was reduced by adding Ca2+ chelator (ethylene glycol tetraacetic acid, EGTA). It was further observed that the time of single QD fluorescence at on-state and QD fluorescence lifetimes were also reduced after adding Ca2+ and then recovered when EGTA was added. Theoretical study shows that a free Ca2+ ion can attach stably to the system of [QD + surface ligand], attract the photoexcited electron, and repel the photoexcited hole inside the QD core, leading to the reduction of the radiative recombination between the electron and hole, thereafter decreasing the QD fluorescence intensity, on-state time, and fluorescence lifetimes, as observed experimentally. To the best of our knowledge, this is a first study to show that the changes of QD optical properties are reversible under the influence of Ca2+ ions. We further estimated the equilibrium association constant pK(a) of our QDs with Ca2+, which is much larger than QDs with Mg2+, Na+, and K+, indicating the feasibility of developing a QD-based Ca2+ sensor.
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| 18. |
- Li, Shu-Ming, et al.
(författare)
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Microwave-assisted method for the synthesis of cellulose-based composites and their thermal transformation to Mn2O3
- 2013
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Ingår i: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 43, s. 751-756
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the synthesis of inorganic materials using cellulose as a template by thermal treatment of the precursor. Cellulose-based composites have been successfully fabricated by an efficient microwave-assisted method. The influences of heating time on the phases and shape of the precursor were investigated. Mn2O3 materials were obtained by thermal treatment of the precursor at 600 degrees C for 3 h in air. The morphology of cellulose composites was preserved after thermal transformation to form Mn2O3. The products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FTIR), energy-dispersive X-ray spectra (EDS). scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). A rapid microwave-assisted method with the thermal post-treatment provides a promising route for the fabrication of inorganic materials using natural polymer as a template.
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| 19. |
- Paton, Nicholas I, et al.
(författare)
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Chloroquine for influenza prevention : a randomised, double-blind, placebo controlled trial
- 2011
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Ingår i: The Lancet - Infectious diseases. - : Elsevier. - 1473-3099 .- 1474-4457. ; 11:9, s. 677-683
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Chloroquine has in-vitro activity against influenza and could be an ideal candidate for worldwide prevention of influenza in the period between onset of a pandemic with a virulent influenza strain and the development and widespread dissemination of an effective vaccine. We aimed to assess the efficacy of such an intervention. METHODS: In this randomised, double-blind, placebo-controlled trial done at a single centre in Singapore, we randomly assigned (1:1) healthy adults to receive chloroquine phosphate (500 mg/day for 1 week, then once a week to complete 12 weeks) or matching placebo by use of a computer-generated randomisation list. Participants filled an online symptom diary every week, supplemented by daily diaries and self-administered nasal swabs when unwell. Haemagglutination-inhibition assays for influenza A (H1N1, H3N2) and B were done on blood samples taken at baseline and after 12 weeks. The primary outcome was laboratory-confirmed clinical influenza defined by specific symptoms accompanied by influenza RNA on nasal swabs or a four-fold increase in haemagglutination-inhibition titres over the 12-week study period. Analysis was by intention to treat. This trial was registered with ClinicalTrials.gov, number NCT01078779. FINDINGS: From November, 2009, to February, 2010, we recruited 1516 eligible participants. 1496 (96%) returned at week 12 and were included in the efficacy analysis. Adherence to study intervention was 97%, and 94% of the scheduled weekly diaries were completed. Eight (1%) of 738 participants had laboratory-confirmed clinical influenza in the placebo group and 12 (2%) of 724 in the chloroquine group (relative risk 1·53, 95% CI 0·63-3·72; p=0·376). 29 (4%) of 738 had laboratory-confirmed influenza infection (symptomatic or asymptomatic) in the placebo group and 38 (5%) of 724 in the chloroquine group (1·34, 0·83-2·14; p=0·261). 249 (33%) of 759 participants reported adverse events (mostly mild) in the placebo group and 341 (45%) of 757 in chloroquine group (p<0·0001). Headache, dizziness, nausea, diarrhoea, and blurred vision were more common in the chloroquine group, but rarely resulted in treatment discontinuation. One serious adverse event (hepatitis) was possibly related to chloroquine. INTERPRETATION: Although generally well tolerated by a healthy community population, chloroquine does not prevent infection with influenza. Alternative drugs are needed for large-scale prevention of influenza. FUNDING: National Medical Research Council, Singapore.
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| 20. |
- Qiu, Feng, et al.
(författare)
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A new IQ detection method for LLRF
- 2012
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 675, s. 139-143
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Tidskriftsartikel (refereegranskat)abstract
- Digital LLRF technology has been widely used in new generation particle accelerators. IF quadrature sampling is a common method for amplitude and phase detection. Many strategies, which obey the same rule of f(sample) = (M/N)f(IF) (M/N is a rational number), have been proposed to reduce the effects of spectrum aliasing. However, we found that M/N does not need to be a rational number according to Shannon's theorem. Therefore, we propose a new IQ detection method in this paper. This method is based on a special IIR filter which is derived from an RLC circuit. The unique characteristic of the method is that the value of f(IF) is independent of the value of, f(sample). We have set up an experimental platform to verify our method. A 122.88 MHz sampling clock is used to sample a 3 MHz IF signal. The DOS and PI control techniques are used to realize the closed-loop control. Results show that the stability of the system is within +/- 0.05% (peak to peak) for the amplitude, and with +/- 0.03 degrees (peak to peak) for the phase in 5 h. (C) 2012 Elsevier B.V. All rights reserved.
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| 21. |
- Schoch, Conrad L., et al.
(författare)
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Finding needles in haystacks: linking scientific names, reference specimens and molecular data for Fungi
- 2014
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Ingår i: Database: The Journal of Biological Databases and Curation. - : Oxford University Press (OUP). - 1758-0463. ; 2014:bau061, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- DNA phylogenetic comparisons have shown that morphology-based species recognition often underestimates fungal diversity. Therefore, the need for accurate DNA sequence data, tied to both correct taxonomic names and clearly annotated specimen data, has never been greater. Furthermore, the growing number of molecular ecology and microbiome projects using high-throughput sequencing require fast and effective methods for en masse species assignments. In this article, we focus on selecting and re-annotating a set of marker reference sequences that represent each currently accepted order of Fungi. The particular focus is on sequences from the internal transcribed spacer region in the nuclear ribosomal cistron, derived from type specimens and/or ex-type cultures. Re-annotated and verified sequences were deposited in a curated public database at the National Center for Biotechnology Information (NCBI), namely the RefSeq Targeted Loci (RTL) database, and will be visible during routine sequence similarity searches with NR_prefixed accession numbers. A set of standards and protocols is proposed to improve the data quality of new sequences, and we suggest how type and other reference sequences can be used to improve identification of Fungi.
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| 22. |
- Tan, Ying, et al.
(författare)
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On Reference Governor in Iterative Learning Control for Dynamic Systems with Input Saturation
- 2011
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Ingår i: Automatica. - : Elsevier. - 0005-1098 .- 1873-2836. ; 47:11, s. 2412-2419
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Tidskriftsartikel (refereegranskat)abstract
- Input saturation is inevitable in many engineering applications. Most existing iterative learning control (ILC) algorithms that can deal with input saturation require that the reference signal is realizable within the saturation bound. For engineering systems without precise models, it is hard to verify this requirement. In this note, a "reference governor" (RG) is introduced and is incorporated with the available ILC algorithms (primary ILC algorithms). The role of the RG is to re-design the reference signal so that the modified reference signal is realizable. Two types of the RG are proposed: one modifies the amplitude of the reference signal and the other modifies the frequency. Our main results provide design guidelines for two RGs. Moreover, a design trade-off between the convergence speed and tracking performance is also discussed. A simple simulation result verifies the effectiveness of the proposed methods.
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| 23. |
- Tong, Lianpeng, et al.
(författare)
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Water Oxidation Catalysis : Influence of Anionic Ligands upon the Redox Properties and Catalytic Performance of Mononuclear Ruthenium Complexes
- 2012
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 51:6, s. 3388-3398
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Tidskriftsartikel (refereegranskat)abstract
- Aiming at highly efficient molecular catalyts for water oxidation, a mononuclear ruthenium complex Ru-II(hqc)(pic)(3) (1; H(2)hqc = 8-hydroxyquinoline-2-carboxylic acid and plc = 4-picoline) containing negatively charged carboxylate and phenolate donor groups has been designed and synthesized. As a comparison, two reference complexes, Ru-II(pdc)(pic)(3) (2; H(2)pdc = 2,6-pyridine-dicarboxylic acid) and Ru-II(tpy)(pic)(3) (3; tpy = 2,2':6',2 ''-terpyridine), have also been prepared. All three complexes are fully characterized by NMR, mass spectrometry (MS), and X-ray crystallography. Complex 1 showed a high efficiency toward catalytic water oxidation either driven by chemical oxidant (Ce-IV in a pH 1 solution) with a initial turnover number of 0.32 s(-1), which is several orders of magnitude higher than that of related mononuclear ruthenium catalysts reported in the literature, or driven by visible light in a three-component system with [Ru(bpy)(3)](2+) types of photosensitizers. Electrospray ionization MS results revealed that at the Rum state complex 1 undergoes ligand exchange of 4-picoline with water, forming the authentic water oxidation catalyst in situ. Density functional theory (DFT) was ernployed to explain how anionic ligands (hqc and pdc) facilitate the 4-picoline dissociation compared with a neutral ligand (tpy). Electrochemical measurements show that complex 1 has a much lower E(Ru-III/Ru-II) than that of reference complex 2 because of the introduction of a phenolate ligand. DFT was further used to study the influence of anionic ligands upon the redox properties of mononuclear aquaruthenium species, which are postulated to be involved in the catalysis cycle of water oxidation.
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| 24. |
- Xu, Cang-Bao, et al.
(författare)
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Cigarette Smoke Extracts Promote Vascular Smooth Muscle Cell Proliferation and Enhances Contractile Responses in the Vasculature and Airway.
- 2010
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - : Wiley. - 1742-7843 .- 1742-7835. ; 107, s. 940-948
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Tidskriftsartikel (refereegranskat)abstract
- Cigarette smoke exposure is a strong risk factor for cardiovascular and respiratory diseases. However, the knowledge about how cigarette smoke induces damage to vasculature and airway is limited. The present study was designed to examine the effects of cigarette smoke particles extracted by heptane (heptane-soluble smoke particles, HSP), by water (water-soluble smoke particles, WSP) and by DMSO (DMSO-soluble smoke particles, DSP), which represent lipophilic, hydrophilic and ambiphoteric constituents from the cigarette smoke, respectively. Human aortic smooth muscle cell (HASMC) proliferation was assessed in cell culture. Rat resistance artery and airway contractile responses to serotonin, U46619, phenylephrine, noradrenaline, acetylcholine, des-Arg(9)-bradykinin, bradykinin, sarafotoxin 6c and endothelin-1 were monitored by a sensitive myograph system. Immunocytochemistry and cell-based phosphoELISA assay were used to demonstrate activation of extracellular signal-regulated kinases 1/2 (ERK1/2). For the first time, our results demonstrate that although all the three extracts promote HASMC proliferation, the HSP and DSP effects occur earlier. HSP and DSP, but not WSP, increase the contractile responses to sarafotoxin 6c, U46619 or bradykinin in rat mesenteric artery and/or in bronchi. ERK1/2 is activated by HSP and DSP in HASMCs and inhibition of ERK1/2 abrogated the smoke extracts-induced HASMC proliferation, while blockage of nicotinic receptors had no effects, suggesting that the toxic effects of the smoke extracts occur via activation of intracellular ERK1/2 signalling, but not nicotinic receptors.
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| 25. |
- Xu, Hao, et al.
(författare)
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Modulated fluorescence of colloidal quantum dots embedded in a porous alumina membrane
- 2013
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 177:45, s. 14151-14156
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Tidskriftsartikel (refereegranskat)abstract
- The fluorescence spectrum of CdSe core-CdS/ZnS shell colloidal quantum dots (QDs) embedded in porous alumina membrane was studied. Small peaks, superimposed on the principal QD fluorescence spectrum, were observed. Finite-difference time-domain simulation indicates that the QD point radiation emitting from within the membrane is strongly modulated by the photonic band structure introduced by the membrane pores, leading to the observed fine spectral features. Moreover, the principal QD fluorescence peak red-shifted when the optical excitation power was increased, which is attributed to QD material heating due to emitted phonons when the photoexcited electron and hole relax nonradiatively from high-energy states to the ground exciton state before fluorescence.
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| 26. |
- Xue-Jian, Xu, et al.
(författare)
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Enhanced Performance and Stability in Polymer Photovoltaic Cells Using Ultraviolet-Treated PEDOT:PSS
- 2013
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Ingår i: Chinese Physics Letters. - : Institute of Physics. - 0256-307X .- 1741-3540. ; 30:7
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effects of ultraviolet (UV) irradiation treatment with varying irradiation intensities for different treatment times of poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film on the performance and stability of polymer solar cells (PSCs) based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) blend. Ultraviolet-visible transmission spectra, x-ray photoelectron spectroscopy, contact angle measurement, atomic force microscopy and the Kelvin probe method are conducted to characterize the UV-treated PEDOT:PSS film. The results demonstrate that UV treatment can improve the power conversion efficiency (PCE) and stability of PSCs effectively. The best performance is achieved under 1200 mu W/cm(2) UV treatment for 50 min. Compared to the control device, the optimized device exhibits enhanced performance with a V-OC of 0.59 V, J(SC) of 12.3 mA/cm(2), fill factor of 51%, and PCE of 3.64%, increased by 3.5%, 33%, 8.7% and 50%, respectively. The stability of the PSCs is enhanced by 2.5 times simply through the UV treatment on the PEDOT:PSS buffer layer. The improvement in the device performance and stability is attributed to the improvement in the wettability property and the increase in the work function of the PEDOT:PSS film by UV treatment, while the impact of UV treatment on the transparency of the PEDOT:PSS film is negligible. The strategy of using UV treatment to improve device performance and stability is attractive due to its simplicity, cost-effectiveness, and because it is suitable for large-scale commercial production.
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| 27. |
- Yan, Ying, et al.
(författare)
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Measurement of linewidths and permanent electric dipole moment change of the Ce 4f-5d transition in Y2SiO5 for qubit readout scheme in rare-earth ion based quantum computing
- 2013
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 87:18
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Tidskriftsartikel (refereegranskat)abstract
- In this work the inhomogeneous (zero-phonon line) and homogeneous linewidths and the permanent electric dipole moment change (averaged value of all dipole orientations) for the Ce 4f-5d transition in Y2SiO5 were measured in order to investigate the possibility for using Ce as a sensor to detect the hyperfine state of a spatially close-lying Pr or Eu ion. The experiments were carried out on Ce doped or Ce-Pr co-doped single Y2SiO5 crystals. The homogeneous linewidth is essentially limited by the excited state lifetime. Based on the linewidth measurements, the oscillator strength, absorption cross section, and saturation intensity were calculated to be about 6.2(+/- 1.7) x 10(-7), 4.5(+/- 1.3) x 10(-19) m(2), and 1.4(+/- 0.4) x 10(7) W/m(2), respectively. The difference in permanent dipole moment, Delta mu(Ce), between the ground and excited states of the Ce ion was measured as 9.6(+/- 5.3) x 10(-30) C m. These measurements indicate that Ce is a promising readout ion to probe a single-ion qubit state for the quantum computing scheme using rare-earth ions.
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| 28. |
- You, Fengzhi, et al.
(författare)
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Maternal mortality in Henan Province, China: changes between 1996 and 2009.
- 2012
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 7:10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Maternal deaths occur mostly in developing countries and the majority of them are preventable. This study analyzes changes in maternal mortality and related causes in Henan Province, China, between 1996 and 2009, in an attempt to provide a reliable basis for introducing effective interventions to reduce the maternal mortality ratio (MMR), part of the fifth Millennium Development Goal. Methods and Findings: This population-based maternal mortality survey in Henan Province was carried out from 1996 to 2009. Basic information was obtained from the health care network for women and children and the vital statistics system, from specially trained monitoring personnel in 25 selected monitoring sites and by household survey in each case of maternal death. This data was subsequently reported to the Henan Provincial Maternal and Child Healthcare Hospital. The total MMR in Henan Province declined by 78.4%, from 80.1 per 100 000 live births in 1996 to 17.3 per 100 000 live births in 2009. The decline was more pronounced in rural than in urban areas. The most common causes of maternal death during this period were obstetric hemorrhage (43.8%), pregnancy-induced hypertension (15.8%), amniotic fluid embolism (13.9%) and heart disease (8.0%). The MMR was higher in rural areas with lower income, less education and poorer health care. Conclusion: There was a remarkable decrease in the MMR in Henan Province between 1996 and 2009 mainly in the rural areas and MMR due to direct obstetric causes such as obstetric hemorrhage. This study indicates that improving the health care network for women, training of obstetric staff at basic-level units, promoting maternal education, and increasing household income are important interventional strategies to reduce the MMR further.
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| 29. |
- Zhang, Igor Ying, et al.
(författare)
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Accurate Bond Dissociation Enthalpies by Using Doubly Hybrid XYG3 Functional
- 2011
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Ingår i: Journal of Computational Chemistry. - : Wiley. - 0192-8651 .- 1096-987X. ; 32:9, s. 1824-1838
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we examine the performance of XYG3, a newly developed doubly hybrid density functional (Zhang, Xu, and Goddard III, Proc Natl Acad Sci USA 2009, 106, 4963), to calculate covalent bond dissociation enthalpy (BDE). We use 5 atoms, 32 molecular radicals, and 116 closed-shell molecules to set up 142 bond dissociation reactions. For the total of 148 heats of formation (HOFs) and 142 BDEs, XYG3 leads to mean absolute deviations (MADs) of 1.45 and 1.87 kcal/mol, respectively. In comparison with some other functionals, MADs for HOFs are 2.31 (M06-2X), 2.98 (B2PLYP-D), 3.04 (BMK), 3.96 (B3LYP), 4.47 (B2PLYP), 5.42 (B2GP-PLYP), 6.46 (PBE0), and 29.93 kcal/mol (B3P86), and the corresponding errors for BDEs are 2.06 (M06-2X), 2.25 (BMK), 2.51 (B2PLYP-D), 2.89 (B2GP-PLYP), 3.30 (B3P86), 3.44 (B2PLYP), 3.87 (PBE0), and 6.14 kcal/mol (B3LYP). (C) 2011 Wiley Periodicals, Inc. J Comput Chem 32: 1824-1838, 2011
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| 30. |
- Zhang, Igor Ying, et al.
(författare)
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Basis set dependence of the doubly hybrid XYG3 functional
- 2010
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 133:10, s. 104105-
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we investigated the basis set dependence of XYG3, a newly developed doubly hybrid functional [Y. Zhang, X. Xu, and W. A. Goddard III, Proc. Natl. Acad. Sci. U.S.A. 106, 4963 (2009)], in prediction of (1) heats of formation (HOFs), (2) bond dissociation enthalpies (BDEs), (3) reaction barrier heights (RBHs), and (4) nonbonded interactions (NBIs). We used basis sets of triple-zeta quality starting from 6-311+G(d,p) with increasing completeness of the polarization functions to the largest Pople-type basis set 6-311++G(3df,3pd) and found that there was a continued improvement with larger basis sets. We showed that while HOF predictions were prone to basis set deficiencies, the basis set dependences in calculating BDEs, RBHs, and NBIs were mild. All of them converged fast with the increase of basis set size. We extended XYG3 to propose the XYG3o functional which was specifically optimized for a particular basis set in order to enhance its performance when using basis set of moderate size. With the 6-311+G(2df,p) basis set, XYG3o led to MADs of 2.56 kcal/mol for HOFs of the G3/99 set, 1.17 kcal/mol for BDEs of the BDE92/07 set, 1.11 kcal/mol for RBHs of the NHTBH38/04 and HTBH38/04 sets, and 0.40 kcal/mol for NBIs of the NCIE31/05 set, being comparable to those obtained by using XYG3/6-311++G(3df,3pd).
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| 31. |
- Zhang, Igor Ying, et al.
(författare)
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RRS-PBC : a molecular approach for periodic systems
- 2014
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Ingår i: Science China Chemistry. - : Springer Science and Business Media LLC. - 1674-7291 .- 1869-1870. ; 57:10, s. 1399-1404
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Tidskriftsartikel (refereegranskat)abstract
- Technically, when dealing with a perfect crystal, methods in k-(reciprocal) space that impose periodic boundary conditions (PBC) in conjunction with plane-wave basis sets are widely used. Chemists, however, tend to think of a solid as a giant molecule, which offers a molecular way to describe a solid by using a finite cluster model (FCM). However, FCM may fail to simulate a perfect crystal due to its inevitable boundary effects. We propose an RRS-PBC method that extracts the k-space information of a perfect crystalline solid out of a reduced real space (RRS) of an FCM. We show that the inevitable boundary effects in an FCM are eliminated naturally to achieve converged high-quality band structures.
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| 32. |
- Zhang, Igor Ying, et al.
(författare)
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Trends in R-X Bond Dissociation Energies (R-center dot = Me, Et, i-Pr, t-Bu, X-center dot = H, Me, Cl, OH)
- 2010
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Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 6:5, s. 1462-1469
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Tidskriftsartikel (refereegranskat)abstract
- Trends for R X bond dissociation energies have been examined with density functional methods of B3LYP, BMK, M06-2X, MC3MPW, B2PLYP, MCG3-MPW, and XYG3, as well as 03, MCG3/3, G3X, and 04 theories as functions of alkylation (i.e., IT = Me, Et, i-Pr, (-Bu) and X' substitution (i.e., X' = H, Me, Cl, OH). The results highlight the physical origin of success or failure of each method and demonstrate the good agreement with experimental results for G4, MCG3-MPW, and XYG3. The last holds great promise as a reliable method that is applicable to larger systems.
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| 33. |
- Zhang, Igor Ying, et al.
(författare)
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XYG3s : Speedup of the XYG3 fifth-rung density functional with scaling-all-correlation method
- 2010
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 132:19, s. 194105-
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Tidskriftsartikel (refereegranskat)abstract
- Recently, we proposed a new version of doubly hybrid functional, XYG3 [Y. Zhang, X. Xu, and W. A. Goddard III, Proc. Natl. Acad. Sci. U.S.A. 106, 4963 (2009)], which not only has a nonlocal orbital-dependent component in the exchange term (Hartree-Fock-like exchange), but also contains information about the unoccupied Kohn-Sham orbitals in the correlation part (PT2 double excitation). In the present work, we examine the frozen-core approximation and Truhlar's scaling-all-correlation (SAC) method in order to accelerate the PT2 evaluations. We adopt the SAC idea and extend XYG3 to propose XYG3s that uses a uniform scaling parameter for the PT2 correlation. We conclude that XYG3s is both fast and accurate for thermochemistry, bond dissociation enthalpies, reaction barrier heights, and nonbonded interactions of main group molecules. In addition, the accuracy remains nearly constant with system size.
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| 34. |
- Zhang, Wei, et al.
(författare)
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Activation of nuclear factor-kappa B pathway is responsible for tumor necrosis factor-a-induced up-regulation of endothelin B2 receptor expression in vascular smooth muscle cells in vitro
- 2012
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Ingår i: Toxicology Letters. - : Elsevier BV. - 1879-3169 .- 0378-4274. ; 209:2, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- The endothelin B2 (ETB2) receptors are induced in vascular smooth muscle cells (VSMCs) in cardiovascular diseases. We tested if in vitro short-term exposure to the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) could up-regulate ETB2 receptors in rat mesenteric arteries, and if this effect is through activation of intracellular nuclear factor-kappa B (NF-kappa B) pathway. The mesenteric arteries were dissected from male Sprague-Dawley rats and the endothelium was removed. The arteries were co-incubated with TNF-alpha in serum-free Dulbecco's modified Eagle's medium. Real-time reverse transcription-PCR, Western blot and immunohistochemical staining were employed to assess the mRNA/protein expression of ETB2 receptors and activation of NF-kappa B pathway. The results showed that, during organ culture. TNF-alpha concentration-dependently enhanced ET52 receptors expression at both mRNA and protein levels, paralleled with activation of NF-kappa B pathway in VSMC. The up-regulated ETB2 receptor expression and NF-kappa B activation could be effectively suppressed by general transcriptional inhibitor actinomycin D, or either of the selective I kappa B kinase inhibitors wedelolactone and IMD-0354. Conclusively, the activation of intracellular NF-kappa B pathway is responsible for the up-regulation of ETB2 receptors induced by short-term exposure to TNF-alpha. This could partly explain the toxic effects of TNF-alpha on VSMCs that account for cardiovascular diseases. (C) 2011 Elsevier Ireland Ltd. All rights reserved.
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| 35. |
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