| 25931. |
- Ding, Linfang, et al.
(författare)
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Towards the next generation of the LinkedGeoData project using virtual knowledge graphs
- 2021
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Ingår i: Journal of Web Semantics. - : Elsevier. - 1570-8268 .- 1873-7749. ; 71
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Tidskriftsartikel (refereegranskat)abstract
- With the advancement of Semantic Technologies, large geospatial data sources have been increasingly published as Linked data on the Web. The LinkedGeoData project is one of the most prominent such projects to create a large knowledge graph from OpenStreetMap (OSM) with global coverage and interlinking of other data sources. In this paper, we report on the ongoing effort of exposing the relational database in LinkedGeoData as a SPARQL endpoint using Virtual Knowledge Graph (VKG) technology. Specifically, we present two realizations of VKGs, using the two systems Sparqlify and Ontop. In order to improve compliance with the OGC GeoSPARQL standard, we have implemented GeoSPARQL support in Ontop v4. Moreover, we have evaluated the VKG-powered LinkedGeoData in the test areas of Italy and Germany. Our experiments demonstrate that such system supports complex GeoSPARQL queries, which confirms that query answering in the VKG approach is efficient.
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| 25932. |
- Ding, Pengjia, et al.
(författare)
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NiCo2O4 hollow microsphere–mediated ultrafast peroxymonosulfate activation for dye degradation
- 2021
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Ingår i: Chinese Chemical Letters. - : Elsevier. - 1001-8417 .- 1878-5964. ; 32:8, s. 2495-2498
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Tidskriftsartikel (refereegranskat)abstract
- Morphology and dispersity are key factors for activating peroxymonosulfate (PMS). In this study, we designed a recyclable open-type NiCo2O4 hollow microsphere via a simple hydrothermal method with the assistance of an NH3 vesicle. The physical structure and chemical properties were characterized using techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), N2 adsorption and X-ray photoelectron spectroscopy (XPS). The test results confirm that the inner and outer surfaces of open-type NiCo2O4 hollow-sphere can be efficiently utilized because of the hole on the surface of the catalyst, which can minimize the diffusion resistance of the reactants and products. Under optimized conditions, the total organic carbon (TOC) removal efficiency of rhodamine B (RhB) can reach up to 80% in 40 min, which is almost 50% shorter than the reported values. The reactive radicals were identified and the proposed reaction mechanism was well described. Moreover, the disturbances of HCO3−, NO3−, Cl− and H2PO4− were further investigated. As a result, HCO3− and NO3− suppressed the reaction while Cl− and H2PO4− had a double effect on reaction.
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| 25933. |
- Ding, Wen-Hong, et al.
(författare)
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Early and long-term survival after aortic valve replacement in septuagenarians and octogenarians with severe aortic stenosis.
- 2010
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Ingår i: International Journal of Cardiology. - : Elsevier. - 0167-5273 .- 1874-1754. ; 141:1, s. 24-31
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the predictors for mortality following aortic valve replacement (AVR) in elderly patients with aortic stenosis (AS).METHODS: 112 consecutive elderly AS patients (aged 77+/-2 years) with AVR between 1998 and 2003 were studied. Clinical and echocardiographic data of LV function were recorded before and 46 months after AVR. Results were compared with 72 younger patients (aged 60+/-1 years). Outcome measures were 30-day and long-term all cause mortalities.RESULTS: Elderly patients had higher NYHA class, more frequent atrial fibrillation, coronary artery disease, emergency operation and use of bioprosthetic valves. They also had shorter E-wave deceleration time (DT) and larger left atria (p<0.05 for all). 30-day mortality was 12% vs 4% (Log Rank x(2)=3.02, p=0.08) and long term mortality was 18% vs 7% (Log Rank x(2)=4.38, p=0.04) in two groups respectively. Age was not related to mortality after adjustment for other variables. Among all variables, anemia (OR 4.20, CI: 1.02-6.86, p=0.04), cardiopulmonary bypass (CPB) time (OR 1.02, CI 1.01-1.04, p<0.01), significant prosthesis patient mismatch (PPM) (OR 5.43, CI 1.04-18.40, p<0.05) were associated with 30-day mortality in elderly patients. Their long-term mortality was related to CBP time (OR 1.02, CI 1.00-1.05, p=0.04), PPM (OR 4.64, CI 1.33-16.11, p=0.02) and raised left atrial pressure: DT (OR 0.94, CI 0.84-0.99, p=0.03) and pulmonary arterial systolic pressure (OR 1.12, CI 1.03-1.19, p<0.001).CONCLUSION: Peri-operative AVR survival is encouraging. While pre-operative anemia and a longer CBP time determine early mortality, long term mortality is related to PPM, LV diastolic dysfunction and secondary pulmonary hypertension.
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| 25934. |
- Ding, Wen-hong, et al.
(författare)
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Echocardiographic predictors of left ventricular functional recovery following valve replacement surgery for severe aortic stenosis.
- 2008
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 128:2, s. 178-84
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We aimed to identify the most sensitive echocardiographic measurements that predict recovery of left ventricular function following valve replacement surgery in patients with severe aortic stenosis (AS) and LV dysfunction.METHODS: We studied 66 patients (mean age 70+/-2 years, 53 male) who underwent AVR for severe AS with concurrent LV dysfunction between 1998 and 2003 at the Royal Brompton Hospital. Clinical symptoms, co-morbidities and echocardiographic measurements of LV function were recorded before and at a median follow-up of 46 months after AVR. Pre-operative LV systolic dysfunction was defined as LV ejection fraction (EF) <50% and the post-op LV recovery as an increase of EF >10%.RESULTS: Following AVR peak aortic pressure gradient decreased and aortic valve area index increased (64+/-3 to 19+/-1 mm Hg and 0.30+/-0.01 to 0.89+/-0.03 cm(2)/m(2), p<0.001 for both). LV EF increased (from 45+/-1 to 54+/-2%; p<0.001) and the LV dimensions fell (LVEDD index: from 33+/-1 to 30+/-1 mm/m(2); and LVESD index: from 27+/-1 to 20+/-1 mm/m(2); p<0.01 for both). LV diastolic dysfunction improved as evidenced by the fall in E/A ratio (from 2.6+/-0.2 to 1.9+/-0.4) and prolongation of total filling time; (from 29.2+/-0.6 to 31.4+/-0.5 s/min, p=0.01 for both). Among all echocardiographic variables, LV dimensions (LVEDD index, OR 0.70, CI 0.52-0.97, p<0.05; LVESD index, OR 0.57, CI 0.40-0.85, p=0.005) were the two independent predictors of post-operative LV functional recovery on multivariate analysis. A cut off value of pre-operative LVESD index=or<27.5 mm/m(2) was 85% sensitive and 72% specific in predicting intermediate-term recovery of LV function after AVR (AUC, 0.72, p=0.002).CONCLUSION: LV functional recovery was evident in majority of aortic stenotic patients with LV dysfunction after aortic valve replacement. A lower prevalence of LV functional recovery in patients with large pre-operative LV end systolic dimension index might signify the loss of contractile reserve and thus predict post-operative functional recovery.
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| 25935. |
- Ding, Wen-Hong, et al.
(författare)
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Predictors of survival after aortic valve replacement in patients with low-flow and high-gradient aortic stenosis
- 2009
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Ingår i: European Journal of Heart Failure. - : Oxford University Press. - 1388-9842 .- 1879-0844. ; 11:9, s. 897-902
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To identify predictors of survival following aortic valve replacement (AVR) in patients with low-flow and high-gradient aortic stenosis (AS).METHODS AND RESULTS: Eighty-six patients (aged 71 +/- 10 years) with severe AS [aortic valve mean pressure gradient >40 mmHg or valve area <1.0 cm(2)] and left ventricular (LV) dysfunction [ejection fraction (EF) <50%] underwent AVR. Cox proportional hazards were used to identify independent clinical and echocardiographic predictors of mortality. Operative (30-day) mortality was 10%. Peri-operative mortality was associated with lower mean LVEF, higher mitral E:A ratio, peak systolic pulmonary artery pressure (PSPAP), and serum creatinine (by 12%, 2.3, 28 mmHg, and 74 mmol/L, respectively, all P < 0.001), NYHA class III-IV (100 vs. 65%), concomitant CABG (89 vs. 55%), urgent surgery (78 vs. 35%), and longer bypass-time (by 28 min, all P < 0.05). Mortality at 4 years was 17%. Univariate predictors [hazard ratio (HR)] of 4-year mortality were: lower EF (HR 0.68 per % increase, P < 0.001), presence of restrictive LV filling (HR: 3.52, P < 0.001), raised PSPAP (HR: 1.07, P < 0.001), and CABG (HR: 4.93, P = 0.037). However, only low EF (<40%, HR 0.74, P = 0.030), the presence of restrictive filling (HR 1.77, P = 0.033), and raised PSPAP (>45 mmHg, HR 2.71, P = 0.010) remained as independent predictors after multivariate analysis. CONCLUSION: The severity of pre-operative systolic and diastolic LV dysfunction is the major predictor of mortality following AVR for low-flow and high-gradient AS.
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| 25936. |
- Ding, Xiangbin, et al.
(författare)
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Identification of fluoride and phosphate binding sites at FeOOH surfaces
- 2012
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:41, s. 21939-21947
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Tidskriftsartikel (refereegranskat)abstract
- Iron oxyhydroxide minerals occur widely in nature and play important roles in environmental and industrial processes. Owing to their high reactivity, these minerals can act as sinks and/or transformation centers for a variety of inorganic and organic ions. Interfacial reactions are often mediated by surface (hydr)oxo groups. These groups can be singly, doubly, or triply coordinated with respect to underlying Fe atoms. In order to investigate the reactivity of these differently coordinated groups, Fourier transform infrared (FTIR) spectroscopy was used to examine adsorption products formed on iron oxyhydroxide surfaces. The absence of water was required to probe the O-H stretching region after initial reactions in aqueous media. This work was specifically focused on synthetic, submicrometer-sized lepidocrocite and goethite particles reacted with aqueous solutions of sodium fluoride and monosodium phosphate. Langmuir-Freundlich adsorption isotherms were calibrated on adsorption data in aqueous media at various pH values to obtain the maximum sorption densities for these ions under these conditions. FTIR measurements of the resulting solids dried under N-2(g) show that fluoride and phosphate ions preferentially exchange with singly coordinated hydroxyls. Doubly coordinated groups can, however, be exchanged with fluoride ions at relatively high loading densities. Triply coordinated groups remain, in contrast, resilient to exchange. They may, however, stabilize phosphate species by hydrogen bonding. These findings add further constraints to our understanding of adsorption reactions and to the formulation of molecularly adequate thermodynamic models.
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| 25937. |
- Dingeldein, Artur Peter Günther, et al.
(författare)
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Apoptotic Bax at Oxidatively Stressed Mitochondrial Membranes : Lipid Dynamics and Permeabilization
- 2017
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 112:10, s. 2147-2158
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondria are crucial compartments of eukaryotic cells because they function as the cellular power plant and play a central role in the early stages of programmed cell death (apoptosis). To avoid undesired cell death, this apoptotic pathway is tightly regulated by members of the Bcl-2 protein family, which interact on the external surface of the mitochondria, i.e., the mitochondrial outer membrane (MOM), and modulate its permeability to apoptotic factors, controlling their release into the cytosol. A growing body of evidence suggests that the MOM lipids play active roles in this permeabilization process. In particular, oxidized phospholipids (OxPls) formed under intracellular stress seem to directly induce apoptotic activity at the MOM. Here we show that the process of MOM pore formation is sensitive to the type of OxPls species that are generated. We created MOM-mimicking liposome systems, which resemble the cellular situation before apoptosis and upon triggering of oxidative stress conditions. These vesicles were studied using P-31 solid-state magic-angle-spinning nuclear magnetic resonance spectroscopy and differential scanning calorimetry, together with dye leakage assays. Direct polarization and cross-polarization nuclear magnetic resonance experiments enabled us to probe the heterogeneity of these membranes and their associated molecular dynamics. The addition of apoptotic Bax protein to OxPls-containing vesicles drastically changed the membranes' dynamic behavior, almost completely negating the previously observed effect of temperature on the lipids' molecular dynamics and inducing an ordering effect that led to more cooperative membrane melting. Our results support the hypothesis that the mitochondrion-specific lipid cardiolipin functions as a first contact site for Bax during its translocation to the MOM in the onset of apoptosis. In addition, dye leakage assays revealed that different OxPls species in the MOM-mimicking vesicles can have opposing effects on Bax pore formation.
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| 25938. |
- Dingeldein, Artur Peter Günther, et al.
(författare)
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Bax to the future : A novel, high-yielding approach for purification and expression of full-length Bax protein for structural studies
- 2019
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Ingår i: Protein Expression and Purification. - : Elsevier. - 1046-5928 .- 1096-0279. ; 158, s. 20-26
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondria-mediated apoptosis (programmed cell death) involves a sophisticated signaling and regulatory network that is regulated by the Bcl-2 protein family. Members of this family have either pro- or anti-apoptotic functions. An important pro-apoptotic member of this family is the cytosolic Bax. This protein is crucial for the onset of apoptosis by perforating the mitochondrial outer membrane (MOM). This process can be seen as point of no return, since disintegration of the MOM leads to the release of apotogenic factors such as cytochrome c into the cytosol triggering the activation of caspases and subsequent apoptotic steps. Bax is able to interact with the MOM with both its termini, making it inherently difficult to express in E. coli. In this study, we present a novel approach to express and purify full-length Bax with significantly increased yields, when compared to the commonly applied strategy. Using a double fusion approach with an N-terminal GST-tag and a C-terminal Intein-CBD-tag, we were able to render both Bax termini inactive and prevent disruptive interactions from occurring during gene expression. By deploying an Intein-CBD-tag at the C-terminus we were further able to avoid the introduction of any artificial residues, hence ensuring the native like activity of the membrane-penetrating C-terminus of Bax. Further, by engineering a His6-tag to the C-terminus of the CBD-tag we greatly improved the robustness of the purification procedure. We report yields for pure, full-length Bax protein that are increased by an order of magnitude, when compared to commonly used Bax expression protocols.
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| 25939. |
- Dingeldein, Artur P G, et al.
(författare)
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BCL-2 Family Proteins Effect on Mitochondrial-Mimicking Membrane Structure by Solid State NMR
- 2015
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Ingår i: Biophysical Journal. - : Cell Press. - 0006-3495 .- 1542-0086. ; 108:2, s. 251A-252A
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Mitochondria are not only the cells' powerhouse, but also involved in their suicide via apoptosis. Key regulators of this pathway are members of the Bcl-2 protein family which interact with the outer mitochondrial membrane to modulate permeability and enable the release of apoptotic stimuli like cytochrome c. For a long time the mitochondrial membrane forming lipids have been seen as merely structural building units with proteins doing the actual work. This view changed in recent years, since lipids were shown to be also directly involved in apoptotic events e.g. under intracellular oxidative stress. Oxidized phospholipids (OxPls) generated under these stress conditions might trigger mitochondria-mediated apoptosis. Their presence in mitochondrial membranes can severely alter the properties of these membranes with yet unknown consequences regarding the formation of pores through membrane-mediated interplay with apoptotic Bax protein. We therefore devised a model system that embodies oxidative stress conditions by incorporating OxPls into mitochondria mimicking model membranes composed of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and cardiolipin (CL) to study the impact of OxPls on apoptotic Bax-membrane interactions. To obtain molecular insight into hydrophobic fatty acid regions of membranes and their hydrophilic interface which is responsible for first protein-membrane contacts, we used differential scanning calorimetry (DSC) and solid state NMR spectroscopy. Upon incorporating OxPls with carboxyl (PoxnoPC) or aldehyde (PazePC) groups at their truncated sn-2-chains into our mitochondria model membranes, calorimetric and NMR measurements showed dramatic changes. 31P NMR experiments revealed major perturbation effects in these membranes; an effect which presumably elevates the membrane binding of apoptotic Bax to the charged membranes and its partial penetration, being a prerequisite for its final formation of pores which enable cytochrome c release from the mitochondrial interior. Currently structural studies of various Bax-lipid assemblies are ongoing.
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| 25940. |
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