Short-Lived Trace Gases in the Surface Ocean and the Atmosphere

The two-way exchange of trace gases between the ocean and the atmosphere is important for both the chemistry and physics of the atmosphere and the biogeochemistry of the oceans, including the global cycling of elements. Here we review these exchanges and their importance for a range of gases whose lifetimes are generally short compared to the main greenhouse gases and which are, in most cases, more reactive than them. Gases considered include sulphur and related compounds, organohalogens, non-methane hydrocarbons, ozone, ammonia and related compounds, hydrogen and carbon monoxide. Finally, we stress the interactivity of the system, the importance of process understanding for modeling, the need for more extensive field measurements and their better seasonal coverage, the importance of inter-calibration exercises and finally the need to show the importance of air-sea exchanges for global cycling and how the field fits into the broader context of Earth System Science

Comparative Phytochemical Screening And Antioxidant Activities of Calligonum Comosum And Calligonum Crjnitum

Medicinal plants are vital source of present day prescription and the majority of the recommended modern medications contain their subsidiaries. Calligonum comosum and Calligonum crinitum are perennial shrub plants growing in the United Arab Emirates, and are being utilized as a part of traditional medicinal system of UAE. The aims of proposed study were to evaluate and compare the phytochemical and antioxidant properties of these two plants. The extraction and fractionation were conducted by using petroleum ether, chloroform, ethyl acetate, acetone and methanol. The extracts were tested for their antioxidant activity. Phytochemical studies with total phenolics and flavonoid contents were analyzed by following standard methods. Along with this, proximate analysis with micro and macro elements were also estimated. In vitro antioxidant analysis were done by different methods. The results exhibited a positive linear correlation between these phytochemicals such as saponins, flavonoids, tannins, and terpenes and the free radical scavenging activities. Our results confirm that the extracts have potential antioxidants and this legitimizes their use in folkloric medicine. Hence, scientific validation of traditional knowledge can be accomplished in a preparatory level

Effect of fuel nitrogen and hydrogen content on emissions in hydrocarbon combustion

How the emissions of nitrogen oxides and carbon monoxide are affected by: (1) the decreased hydrogen content and (2) the increased organic nitrogen content of coal derived fuels is investigated. Previous CRT experimental work in a two stage flame tube has shown the effectiveness of rich lean two stage combustion in reducing fuel nitrogen conversion to nitrogen oxides. Previous theoretical work gave preliminary indications that emissions trends from the flame tube experiment could be predicted by a two stage, well stirred reactor combustor model using a detailed chemical mechanism for propane oxidation and nitrogen oxide formation. Additional computations are reported and comparisons with experimental results for two additional fuels and a wide range of operating conditions are given. Fuels used in the modeling are pure propane, a propane toluene mixture and pure toluene. These give hydrogen contents 18, 11 and 9 percent by weight, respectively. Fuel bound nitrogen contents of 0.5 and 1.0 percent were used. Results are presented for oxides of nitrogen and also carbon monoxide concentrations as a function of primary equivalence ratio, hydrogen content and fuel bound nitrogen content

Laboratory studies on the production of alpha-pinene-derived organic nitrates and their atmospheric fate

Currently, the formation yields of organic nitrates from the oxidation of biogenic volatile organic compounds, such as α-pinene, is highly uncertain, negatively impacting our knowledge on tropospheric ozone production and the fate of atmospheric NOx. To lower this uncertainty, we quantified the organic nitrate yield from the OH radical oxidation of α-pinene under high NOx conditions. The α-pinene- derived nitrates created in chamber experiments readily partitioned to the aerosol phase and underwent particle phase hydrolysis, indicating that these processes are likely a sink for atmospheric NOx. The hydrolysis of organic nitrates was found to be specific acid-catalyzed and proceeded via unimolecular mechanisms under acidic conditions. The hydrolysis lifetime of a synthesized α-pinene nitrate standard was well within the lifetime of an atmospheric particle. Previously unreported α-pinene oxidation products from chamber studies were identified using mass spectrometry, and, for the first time, individual α-pinene-derived nitrates were identified in a complex mixture. In addition, paper spray ionization was adapted for the direct detection of organosulfates from filter samples and a Raman technique was developed to directly measure the pH of single aerosol particles, for the first time

Role of WNT1-inducible signaling pathway protein-1 (WISP1) in liver injury

Liver diseases are a global burden and a better understanding of factors controlling disease progression is required. In the last decade, much progress has been achieved in understanding the relevance of the extracellular matrix. Alterations in this dynamic structure can either facilitate or impair the repair of damaged liver tissue. Therefore, matricellular proteins of the CCN family, have emerged as new targets in liver pathophysiology. These highly conserved secreted proteins specifically interact with and signal through various extracellular partners, like integrins, which enable them to play crucial roles in various processes including development, wound healing and diseases such as cancer and fibrosis. We have discovered that WISP1 (Wnt1-inducible signaling pathway protein-1) also named CCN4, is induced upon CCl4-induced liver damage and may play an important role in the remodeling process of the extracellular matrix. Therefore, the aims were to identify the cell type that produces WISP1, to study its influence in cell migration and to use WISP1 KO mice to understand its role in the pathogenesis of liver fibrosis. Isolation of individual liver cell types and quantification of WISP1 expression and secretion showed a higher mRNA expression and TGF-β-induced secretion of WISP1 in non-parenchymal cells, especially in stellate cells compared to hepatocytes. Furthermore, WISP1 facilitated the migration of isolated mouse hepatic stellate cells through collagen lattices, suggesting the interaction of WISP1 with one of the main components of the extracellular matrix and affecting its architecture. Additionally, gene expression analysis and Sirius Red staining showed differences in the development of CCl4-induced fibrosis between WISP1 wild type and knockout mice. Upregulation of collagen type I and α-SMA is reduced in WISP1 KO mice and less collagen deposition is also observed. In conclusion, WISP1 is mainly expressed and secreted by stellate cells which may influence their migration upon liver injury and consequently, ameliorating the degree of liver fibrosis

The Atmospheric Effects of Stratospheric Aircraft: a First Program Report

Studies have indicated that, with sufficient technology development, high speed civil transport aircraft could be economically competitive with long haul subsonic aircraft. However, uncertainty about atmospheric pollution, along with community noise and sonic boom, continues to be a major concern; and this is addressed in the planned 6 yr HSRP begun in 1990. Building on NASA's research in atmospheric science and emissions reduction, the AESA studies particularly emphasizing stratospheric ozone effects. Because it will not be possible to directly measure the impact of an HSCT aircraft fleet on the atmosphere, the only means of assessment will be prediction. The process of establishing credibility for the predicted effects will likely be complex and involve continued model development and testing against climatological patterns. Lab simulation of heterogeneous chemistry and other effects will continue to be used to improve the current models

Atmosphere, ocean, and land: Critical gaps in Earth system models

We briefly review current knowledge and pinpoint some of the major areas of uncertainty for the following fundamental processes: (1) convection, condensation nuclei, and cloud formation; (2) oceanic circulation and its coupling to the atmosphere and cryosphere; (3) land surface hydrology and hydrology-vegetation coupling; (4) biogeochemistry of greenhouse gases; and (5) upper atmospheric chemistry and circulation

Nitric oxide modulates the expression of matricellular genes involved in fibrosis in renal glomerular mesangial cells

By means of their proliferative and secretory potential glomerular mesangial cells are thought to be important mediators of glomerular inflammation and fibrosis. Recent studies have established a direct role for NO in the regulation of gene expression in different cell types including mesangial cells. Representational difference analysis was used to investigate changes in gene expression elicited by the treatment of S-Nitroso-L-glutathione in rat mesangial cells. We identified 7 upregulated and 11 downregulated genes. Four out of 11 downregulated genes, connective tissue growth factor, thrombospondin-1, collagen type I alpha 1 and collagen type I alpha 2, are matricellular genes linked to inflammation and fibrosis of different organs including the kidney. Results were verified by using Northern blot analysis, quantitative real time PCR and protein analysis methods in human mesangial cells treated with a series of NO donors. We validated our findings by inducing endogenous NO production by cytokine stimulation. Real time PCR analysis showed that two additional matrix related genes, biglycan and collagen type IV alpha 2 are also downregulated by NO. Connective tissue growth factor promoter studies in mesangial cells demonstrated that NO acts at the transcriptional level to suppress gene expression. These results reveal a complex role of NO in regulating gene expression in mesangial cells and suggest an antifibrotic potential for NO