Indigenous vegetation in the foreland of river oases at the extremely arid southern margin of the Taklimakan Desert in Xinjiang,NW China,is dominated by a few perennial phreatophytes,primarily Alhagi sparsifolia Shap.,Tamarix ramosissima Ledeb.and Karelinia caspica Less.Water is well known as a limiting factor for plant growth in deserts,availability of nutrients has also been determined as a critical factor limiting plant growth in arid regions.Water source for plants is groundwater at the southern fringe of the Taklimakan Desert.So nutrients are the most important resource for plant growth in the same groundwater depth.When the soil N content or the nitrogen validity are low,plants with the ability to fix N2 might have an advantage and be capable of taking in more N than plants without this ability.Leaf N content correlates strongly with photosynthesis as most of the leaf N is allocated to photosynthesis.So some people considered that the nitrogen fixing plants might have higher Pmax than the nitrogen non-fixing ones living in the same habitat.However,in our previous research,we found that nitrogen non-fixing species had higher photosynthetica capacity.In order to answer this question,nitrogen fixing species A.sparsifolia and nitrogen non-fixing species K.caspica and T.ramosissima were compared in their typical habitat at the southern fringe of the Taklimakan Desert.The diurnal variations of net photosynthetic rate,indexs of light and CO2 to net photosynthetic rate(Pn),Chl content,leaf nitrogen content of nitrogen fixing and non-fixing species were investigated in June,July and August 2008.The results showed that from 08∶00 to 20∶00 the diurnal variations of Pn showed double peak curve both nitrogen fixing and non-fixing species in June and July.In August,the curve changed into a single peak.The order of average photosynthetic rate of three months: K.caspicaT.ramosissimaA.sparsifolia.It also showed that nitrogen non-fixing species had higher Pn than nitrogen fixing species.The maximum net photosynthetic rate(Pmax),apparent quantum requirement(AQY),CO2 saturation point(CSP),dark respiration rate(Rday) of nitrogen non-fixing species were higher than nitrogen fixing species,the difference was significant(P0.05),respectively.Carboxylation efficiency(Vcmax) and electron transport rate(Jmax) were not significantly different between nitrogen fixing and non-fixing species(P0.05).The nitrogen fixing species had significantly higher light compensation point(LCP),light saturation point(LSP),CO2 compensation point(CCP),Chl content and leaf nitrogen content than nitrogen non-fixing species(P0.05).Through correlative analysis,we found that there was no obviously relationship between Pmax and Chl,leaf nitrogen content in A.sparsifolia.There was no obviously relationship between Pmax and Chl in K.caspica and T.ramosissima.Pmax of T.ramosissima was negatively correlated with leaf nitrogen content.But Pmax of K.caspica was positively correlated with leaf nitrogen content.In despite of higher leaf nitrogen content in nitrogen fixing species,nitrogen non-fixing species had higher photosynthetic capacity.The higher leaf nitrogen content not always bring higher photosynthetic rate in nitrogen fixing and non-fixing species.
The massive emission of CO2 has caused a series of environmental problems, including global warming, which exacerbates natural disasters and human health. Cu-based catalysts have shown great activity in the reduction of CO2, but the mechanism of CO2 activation remains ambiguous. In this work, we performed density functional theory (DFT) calculations to investigate the hydrogenation of CO2 on Cu(211)-Rh, Cu(211)-Ni, Cu(211)-Co, and Cu(211)-Ru surfaces. The doping of Rh, Ni, Co, and Ru was found to enhance CO2 hydrogenation to produce COOH. For CO2 hydrogenation to produce HCOO, Ru plays a positive role in promoting CO dissociation, while Rh, Ni, and Co increase the barriers. These results indicate that Ru is the most effective additive for CO2 reduction in Cu-based catalysts. In addition, the doping of Rh, Ni, Co, and Ru alters the electronic properties of Cu, and the activity of Cu-based catalysts was subsequently affected according to differential charge analysis. The analysis of Bader charge shows good predictions for CO2 reduction over Cu-based catalysts. This study provides some fundamental aids for the rational design of efficient and stable CO2-reducing agents to mitigate CO2 emission.
The Ordovician reservoir of the Tahe oil field went through many tectonic reconstructions, and was characterized by multiple hydrocarbon chargings. The aim of this study was to unravel the complex charging histories. Systematic analysis of fluid inclusions was employed to complete the investigation. Fluorescence observation of oil inclusions under UV light, and microthermometry of both oil and aqueous inclusions in 105 core samples taken from the Ordovician reservoir indicated that the Ordovician reservoir underwent four oil chargings and a gas charging. The hydrocarbon chargings occurred at the late Hercynian, the Indo-Sinian and Yanshan, the early Himalaya, the middle Himalaya, and the late Himalaya, respectively. The critical hydrocarbon charging time was at the late Hercynian.
There is little detailed information regarding benign asbestos pleural effusion (BAPE). It is frequently misdiagnosed because of lack of a standardized diagnostic approach and criteria. The present study aimed to better characterize BAPE and outline a diagnostic approach for this disease.Complete clinical data of 11 consecutive patients with BAPE were prospectively collected and analysed. A multidisciplinary team (MDT) was involved in discussing the suspected cases of BAPE. The team was comprised of thoracic physicians, radiologists and pathologists. A multidisciplinary practical diagnostic approach for BAPE was introduced.Six patients had respiratory symptoms, but another 5 were asymptomatic. All the patients had an asbestos exposure and the median duration was 23.9 years (rang, 12-36 years). The median level of lactate dehydrogenase (LDH), adenosine deaminase (ADA), proteins and carcinoembryonic antigen (CEA) in the pleural fluid (PF) were 221.4 U/L (range, 189.8-11,325 U/L), 21 U/L (rang, 14-247 U/L), 48.3 g/dL (range, 35.2-53.2 g/dL) and 3.46 mg/mL (range, 0.84-4.54 mg/mL), respectively. Five patients had pleural plaques, 2 had diffuse pleural thickening (DPT), 1 had asbestosis, and 1 had round atelectasis. The pleural biopsy specimens showed a benign fibrotic pleura in all case. The symptoms and pleural pulmonary radiologic findings remained stable during the follow-up.BAPE is diagnosed by exclusion. A suspected diagnosis of BAPE with an asbestos exposure should be considered, especially with the presence of pleural plaques, and/or DPT, and rounded atelectasis. The MDT-based diagnostic approach may reduce misdiagnosis.
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