| 1. |
- Dong, Jingfeng, et al.
(författare)
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Promoting Effect of Electrostatic Interaction between a Cobalt Catalyst and a Xanthene Dye on Visible-Light-Driven Electron Transfer and Hydrogen Production
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:30, s. 15089-15096
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Tidskriftsartikel (refereegranskat)abstract
- The readily obtained noble-metal-free molecular catalyst systems, with xanthene dyes (Rose Bengal, RB(2-); Eosin Y, EY(2-); and Eosin B, EB(2-)) as photosensitizers, [Co(bpy)(3)]Cl(2) as catalyst, and triethylamine as sacrificial electron donor, are highly active for visible-light-driven (lambda > 450 nm) hydrogen production from water. The turnover frequency is up to 54 TON/min versus RB(2-) with a RB(2-)/[Co(bpy)(3)]Cl(2) molar ratio of 1:10 in CH(3)CN/H(2)O under optimal conditions in the first half hour of irradiation (lambda > 450 rim), and the turnover number is up to 2076 versus RB(2-). Comparative studies show the following: (1) The photocatalytic H(2)-evolving activity of the cationic cobalt complex [Co(bpy)(3)]Cl(2), is apparently higher than the neutral cobaloxime complexes with xanthene dyes as potosensitizers, and also much higher than the analogous system of [Ru(bpy)(3)]Cl(2)/[Co(bpy)(3)]Cl(2). (2) The UV-vis absorptions of xanthene dyes are red shifted to different extents upon addition of [Co(bpy)(3)]Cl(2) to the aqueous or CH(3)CN/H(2)O solutions of these dyes, while no change was observed in UV-vis absorptions of photosensitizer with addition of the cobaloximes to the aqueous solution of RB(2-) or addition of [Co(bpy)(3)]Cl(2) to the aqueous solution of [Ru(bpy)(3)]Cl(2). (3) The fluorescence of RB(2-) is significantly quenched by [Co(bpy)(3)]Cl(2), but not by the cobaloximes. These special performances of [Co(bpy)(3)]Cl(2) are attributed to the electrostatically attractive interaction between the anionic organic dyes and the cationic cobalt catalyst. The probable mechanism for photoinduced hydrogen production catalyzed by the system of RB(2-), [Co(bpy)(3)]Cl(2), and triethylamine is discussed in detail on the basis of fluorescence. fand transient absorption spectroscopic studies. "
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| 2. |
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| 3. |
- Li, Xueqiang, et al.
(författare)
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Photocatalytic Water Reduction and Study of the Formation of FeIFe0 Species in Diiron Catalyst Sytems
- 2012
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631. ; 5:5, s. 913-919
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Tidskriftsartikel (refereegranskat)abstract
- Noble-metal-free systems with bio-inspired diiron dithiolate mimics of the [FeFe]-hydrogenase active site, namely, [(mu-pdt)Fe2(CO)5L] [pdt=propanedithiolate; L=P(CH2OH)3 (1), P(CH3)3 (2)], as water reduction catalysts with xanthene dyes as photosensitizers and triethylamine as a sacrificial electron donor were studied for visible-light-driven water reduction to hydrogen. These systems display good catalytic activities with the efficiencies in hydrogen evolution of up to 226 turnovers for 1, if Eosin Y was used as the photosensitizer in an environmentally benign solvent (EtOH/H2O) after 15 h of irradiation (?>450 nm) under optimal conditions. Under all of the conditions adopted, 1 that has a water soluble phosphine ligand, P(CH2OH)3 displayed a higher efficiency than 2, which bears a PMe3 ligand. The photoinduced electron transfer in the systems was studied using fluorescence, transient absorption, time-resolved UV/Vis, and in situ electron paramagnetic resonance (EPR) spectroscopy. A new electron-transfer mechanism is proposed for hydrogen evolution by these iron-based photocatalytic systems.
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| 4. |
- Liu, Zhengtao, et al.
(författare)
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Clear mortality gap caused by graft macrosteatosis in Chinese patients after cadaveric liver transplantation
- 2020
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Ingår i: Hepatobiliary surgery and nutrition. - : AME Publishing Company. - 2304-3881 .- 2304-389X. ; 9:6, s. 739-758
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Tidskriftsartikel (refereegranskat)abstract
- Background: Liver transplantation (LT) is one of the most effective surgical treatment for patients with end-stage liver disease. Steatosis is a contributor for inferior graft quality. But its impact and safety on transplantation was less assessed in Chinese patients. Methods: Graft steatosis and related information involved in recipients, donors and surgical procedures were retrospectively collected from 239 patients. Results: Donor macrosteatosis (MaS) caused about 2.14 and 2.80 folds of increment on patient and graft mortality. Dose-response analysis revealed prominent risk of grafts on overall patient/organ mortality when MaS content exceeded 10% (P<0.05). Noteworthy, deaths were only observed in MaS group when concurrent with extremely higher post-transplant alanine aminotransferase (ALT, 64%). However, microsteatosis (MiS) grafts didn't affect outcomes after LT. In a cohort of Chinese patients, MaS had comprehensive effects on post-transplant outcomes with relatively lower safety threshold at 10%. Mortality gap caused by MaS grafts was observed in patients with severer ischemia reperfusion injury. Conclusions: Our study revealled the graft MaS affected the post-transplant outcomes in lower risk cutoff in Chinese patients. Further study is worthy to validate these results and investigate inner mechanism under the phenomenon.
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| 5. |
- Sun, Huaiwei, et al.
(författare)
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Assessment of long-term water stress for ecosystems across China using the maximum entropy production theory-based evapotranspiration product
- 2022
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 349
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Tidskriftsartikel (refereegranskat)abstract
- Water demand growth coupled with its high spatial-temporal mismatch of water resources will lead to an increasing water scarcity worldwide. In order to investigate a robust long-term water stress for ecosystems and regions across China, the improved maximum entropy production (MEP) method was utilized to obtain a reliable evapotranspiration (ET) product during 1982–2015. Afterwards four water stress indices were constructed based on the MEP, Penman, Priestley-Taylor and complementary relationship model. The MEP estimated ET showed a close agreement with measurements at eddy covariance sites, with R2 = 0.89 and RMSE ranged from 5 to 12 mm/month. All ecosystems were indicated to suffer from a high risk of water stress, and were ranked by desert (0.67–0.93), grassland (0.60–0.78), settlement (0.49–0.63), farmland (0.48–0.63), and forest ecosystem (0.45–0.58) with four indices. Patterns of water stress at the provincial levels were revealed. Provinces including Xinjiang, Qinghai, Inner Mongolia, and Gansu in the northern regions displayed the highest water stress, and months from December to February were most vulnerable to extreme water stress. Overall, results revealed that the MEP model-based water stress index can well characterize the water stress footprints for all ecosystems and regions in China. This study can support the policy-making for improving water use efficiency and optimizing water resource management to alleviate water stress on large scales.
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| 6. |
- Sun, Huaiwei, et al.
(författare)
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Drivers of the water use efficiency changes in China during 1982–2015
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 799
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the drivers of water use efficiency (WUE), a key metric of water resources management, and its changes over eight regions across China from 1982 to 2015 based on gross primary production (GPP) and actual evapotranspiration (AET) datasets. The order of seasonal change of WUE from large to small is autumn, summer, spring and winter. The drivers include seven variables, air temperature, specific humidity, precipitation, short-wave radiation, Normalized Difference Vegetation Index (NDVI), soil moisture and CO2. Our analysis suggests that the sensitivity of annual average NDVI to WUE changes was high nationwide, but there were some differences in seasonal scales. The annual average contribution of air temperature and CO2 affecting WUE change was relatively high in China's largest area (SW, SE, E, NP). Other influencing factors were only relatively high in the local area. Seasonally, NDVI is the driving factor with the highest contribution rate in summer and autumn for NC and NW region. The seasonal contribution rates of driving factors in other regions are significantly different. For the study period (1982–2015), the shrubland ecosystem had the highest annual WUE followed by forest and cropland. The WUE of the farmland ecosystem was higher than that of the grassland ecosystem in most areas.
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| 7. |
- Sun, Huaiwei, et al.
(författare)
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Revisiting the role of transpiration in the variation of ecosystem water use efficiency in China
- 2023
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923. ; 332
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Tidskriftsartikel (refereegranskat)abstract
- Efforts to develop effective climate strategies necessitate a better understanding of the relationship between terrestrial water and carbon cycles. Water use efficiency (WUE) has been often used to characterize this relationship, while the role of transpiration (T) in the variation of ecosystem WUE has been less investigated. Here, we partitioned WUEET (the ratio of gross primary productivity (GPP) to evapotranspiration (ET)) into a two-component process, i.e., the ratio of gross primary productivity to plant transpiration, GPP/T, that is WUET, and the ratio of plant transpiration to evapotranspiration, T/ET. Based on two GPP datasets (i.e., GPP based on the light use efficiency model or the vegetation index- NIRv) and the GLEAM ET dataset, this study investigated the role of T in the variation of WUE in the ecosystem level and how the role is affected by drought. We found that drought can lead to the change of ET partitioning, thus affecting the variability of WUE. The variability of WUEET was dominated by WUET. In general, the proportion of T increased gradually from humid to arid areas. To adapt to drought conditions, vegetation in arid areas tend to have a high stress resistance by increasing their WUE. We further found that WUET has stronger seasonal stability than WUEET. GPP dominated WUEET variability in humid/sub humid areas, while ET and GPP jointly dominated WUEET variability in semi-arid/arid areas. GPP dataset based on light use efficiency (LUE) could better reflect the impact of drought on vegetation. This study contributes to a better understanding of the change mechanism of ecosystem WUE and emphasizes the critical role of physiological process components in water-carbon cycling.
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| 8. |
- Zhang, Pan, et al.
(författare)
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Photocatalytic Hydrogen Production from Water by Noble-Metal-Free Molecular Catalyst Systems Containing Rose Bengal and the Cobaloximes of BFx-Bridged Oxime Ligands
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:37, s. 15868-15874
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen evolution was observed from the noble-metal-free catalyst systems, comprising Rose Bengal, BFx-bridged cobaloximes, and triethylamine, in an aqueous solution under irradiation of visible light. Two types of BFx-bridged cobaloximes namely, the annulated cobaloximes [Co(dmgBF(2))(2)(H2O)(2)] (1, dmgBF(2) = (difluoroboryl)dimethylglyoximate anion) and [Co(dpgBF(2))(2)(H2O)(2)] (2, dpgBF(2) =(difluoroboryl)diphenylglyoximate anion), and the clathrochelated cobaloximes [Co(dmg(BF)(2/3))(3)](BF4) (3) and [Co(dpg(BF)(2/3))(3)](BF4) (4)-were used as catalysts. Among the four cobalt complexes, complex 1 displayed the highest hydrogen-evolving efficiency, with turnovers up to 327. Complexes 2 and 4 that bear the diphenylglyoximate ligands exhibited much lower efficiencies as compared with their analogues 1 and 3 that have the dimethylglyoximate ligands. The hydrogen-evolving efficiency of the annulated cobalt(II) complex 1 that contains two labile axial ligands is more than three times as high as that of the encapsulated cobalt(III) complex 3 that has a single macrobicyclic ligand. The different pathways for formation of the cobalt(I) species from these two types of cobaloximes are discussed on the basis of the results obtained from fluorescence and laser flash photolysis spectroscopic studies.
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| 9. |
- Zhang, Pan, et al.
(författare)
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Photochemical H-2 production with noble-metal-free molecular devices comprising a porphyrin photosensitizer and a cobaloxime catalyst
- 2010
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 46:46, s. 8806-8808
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Tidskriftsartikel (refereegranskat)abstract
- Among three noble-metal-free molecular devices (1-3) containing a porphyrin photosensitizer and a cobaloxime catalyst, the one with a zinc porphyrin unit displayed apparently higher efficiency for photoinduced H-2 production than complex 2 with a magnesium porphyrin and 3 with a free-base porphyrin, possibly due to the formation of a TEA center dot center dot center dot ZnPor-Co triad in solution.
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| 10. |
- Zhang, Pan, et al.
(författare)
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Photochemical hydrogen production with molecular devices comprising a zinc porphyrin and a cobaloxime catalyst
- 2012
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Ingår i: Science China Chemistry. - : Springer Science and Business Media LLC. - 1674-7291 .- 1869-1870. ; 55:7, s. 1274-1282
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Tidskriftsartikel (refereegranskat)abstract
- Two new noble-metal-free molecular devices, [{Co(dmgH)(2)Cl}{Zn(PyTPP)}] (1, dmgH = dimethyloxime, PyTPP = 5-(4-pyridyl)-10,15,20-triphenylporphyrin) and [{Co(dmgH)(2)Cl}{Zn(apPyTPP)}] (2, apPyTPP = 5-[4-(isonicotinamidyl)phenyl]-10,15,20-triphenylporphyrin), for light-driven hydrogen generation were prepared and spectroscopically characterized. The zinc porphyrin photosensitizer and the Co-III-based catalyst unit are linked by axial coordination of a pyridyl group in the periphery of zinc-porphyrin to the cobalt centre of catalyst with different lengths of bridges. The apparent fluorescence quenching and lifetime decays of 1 and 2 were observed in comparison with their reference chromophores, Zn(PyTPP) (3) and Zn(apPyTPP) (4), suggesting a possibility for an intramolecular electron transfer from the singlet excited state of zinc porphyrin unit to the cobalt centre in the molecular devices. Photochemical H-2-evolving studies show that complexes 1 and 2 are efficient molecular photocatalysts for visible light-driven H-2 generation from water with triethylamine as a sacrificial electron donor in THF/H2O, with turnover numbers up to 46 and 35 for 1 and 2, respectively. In contrast to these molecular devices, the multicomponent catalyst of zinc porphyrin and [Co(dmgH)(2)PyCl] did not show any fluorescence quenching and as a consequence, no H-2 gas was detected by GC analysis in the presence of triethylamine with irradiation of visible light. The plausible mechanism for the photochemical H-2 generation with these molecular devices is discussed.
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