Crystallization path of salts from brine in Zabuye Salt Lake, Tibet, during isothermal evaporation

Zabuye Salt Lake in Tibet, China is a carbonate-type lake, rich in Li, B, K and other useful trace elements that are of great economic value. We studied the concentration behavior of these elements and the crystallization paths of salts in the brine at 25 C, based on an isothermal evaporation experiment. The crystallization sequence of the primary salts from the brine is halite - aphthitalite - zabuyelite - sylvite - trona and thermonatrite in accordance with the metastable phase diagram. In the experiment, zabuyelite was precipitated in the early stage in the brine at 25 degrees C. Potassium was precipitated as sphthitalite in the intermediate stage and as sylvite in the late stage, while boron was concentrated in the early and intermediate stages and precipitated as borax in the late stage

Effect of H2S content on relative permeability and capillary pressure characteristics of acid gas/brine/rock systems: A review

Geological storage of acid gas has been identified as a promising approach to reduce atmospheric carbon dioxide (CO2) and hydrogen sulfide (H2S) and alleviate public concern resulting from sour gas production. A good understanding of the relative permeability and capillary pressure characteristics is crucial to predict the process of acid gas injection and migration. The prediction of injection and redistribution of acid gas is important to determine storage capacity, formation pressure, plume extent and shape, and leakage potential. Herein, we reviewed existing experimental data and theoretical models used to gain a better understanding of how the H2S content affects gas density, gas viscosity, interfacial tension, wettability, relative permeability and capillary pressure characteristics of acid gas/brine/rock systems. The densities and viscosities of acid gas with different H2S mole fractions are of both temperature and pressure dependence, which vary among the gas, liquid and supercritical phases. Water/acid gas interfacial tension decreases strongly with increasing H2S content. For mica and clean quartz, water contact angle increases with increasing H2S mole fraction. In particular, wettability reversal of mica to a H2S-wet behavior occurs in the presence of dense H2S. Capillary pressure increases with decreasing contact angle. At a given saturation, the relative permeability of a fluid is higher when the fluid is nonwetting. The capillary pressure decreases with decreasing interfacial tension at a given saturation. However, existing data sets do not show a consistent link between capillary number and relative permeability. The capillary pressure decreased with increasing H2S mole fraction. However, there is no consensus on the effect of the H2S content on relative permeability curves. This may be due to the limited availability of relative permeability and capillary pressure data for acid gas/brine/rock systems; thus, more experimental measurements are required

Tetra­kis(1,3,4,6,7,9-hexa­aza-1H-phen­alen-6-ium) sodium(I) penta­kis(tetra­fluorido­borate)

In the title compound, Na+·4C7H5N6 +·5BF4 −, the Na+ ion lies on a fourfold rotation axis and one of the tetra­fluoridoborate ions lies on a site of symmetry . Each Na+ ion is surrounded by four symmetry-related tetra­fluoridoborate ions, and is eight-coordinated by F atoms, the Na⋯F separation being 2.3956 (15) or 2.4347 (17) Å. The hexa­azaphenalenium ring system is essentially planar. In the crystal structure, the cations and anions are linked into a three-dimensional network by N—H⋯N and C—H⋯F hydrogen bonds

Differential expressed genes in ECV304 Endothelial-like Cells infected with Human Cytomegalovirus

Background: Human cytomegalovirus (HCMV) is a virus which has the potential to alter cellular gene expression through multiple mechanisms.Objective: With the application of DNA microarrays, we could monitor the effects of pathogens on host-cell gene expression programmes in great depth and on a broad scale.Methods: Changes in mRNA expression levels of human endothelial-like ECV304 cells following infection with human cytomegalovirus AD169 strain was analyzed by a microarray system comprising 21073 60-mer oligonucleotide probes which represent 18716 human genes or transcripts.Results: The results from cDNA microarray showed that there were 559 differential expressed genes consisted of 471 upregulated genes and 88 down-regulated genes. Real-time qPCR was performed to validate the expression of 6 selected genes (RPS24, MGC8721, SLC27A3, MST4, TRAF2 and LRRC28), and the results of which were consistent with those from the microarray. Among 237 biology processes, 39 biology processes were found to be related significantly to HCMV-infection. The signal transduction is the most significant biological process with the lowest p value (p=0.005) among all biological process which involved in response to HCMV infection.Conclusion: Several of these gene products might play key roles in virus-induced pathogenesis. These findings may help to elucidate the pathogenic mechanisms of HCMV caused diseases.Keywords: Human cytomegalovirus, microarray, Gene expression profiling; infectomicsAfrican Health Sciences 2013; 13(4): 864 - 87

Fluorine speciation and origin of Early-Middle Triassic bentonite deposits in Sichuan Basin, South China

Fluorine (F) is one of the most important environmentally harmful elements released by volcanic activity, and the bentonite deposits that formed from volcanic ashes are potentially harmful to the environment. However, the mechanisms governing F-rich bentonite formation and its F speciation composition remain enigmatic. The F-rich bentonite deposits are widely distributed in the Early-Middle Strata of the Sichuan Basin, South China. Detailed mineralogical and geochemical studies were conducted on the bentonite deposits from five sections of the Sichuan Basin. X-ray diffraction (XRD) analyses indicate that the F-rich bentonites mainly contain quartz, carbonates (calcite and dolomite) or gypsum, and clay minerals, while the clay minerals are dominated by illite and illite/smectite (I/S). Clay mineralogical studies suggest that bentonites were transformed from volcanic ashes during diagenesis by smectite illitization. The major and trace element distribution in F-rich bentonite deposits altered from volcanic ashes is most likely derived from felsic magmas, and alteration of the parent rocks (e.g., rhyolites) to bentonite is associated with leaching and subsequent removal of F. The total fluorine content (FTOT) of the bentonite samples ranged from 1,162 mg/kg to 2,604 mg/kg (average = 1773 mg/kg), well above the average FTOT contents of soils in the world. The results of the sequential extraction experiments show that the highest content is residual-fluorine (Fres), followed by carbonate-fluorine (Fcar) with a mean value of 1,556 mg/kg and 186 mg/kg, indicating carbonate is an important F sink in bentonite deposits. The average fluorine value of organic fluorine (For), Fe/Mn oxide-fluorine (Ffm) and exchangeable fluorine (Fex) are relatively low with an average value of 17.5 mg/kg, 6.8 mg/kg and 4.1 mg/kg, respectively. However, water-soluble fluorine (Fws) has a mean value of 4.0 mg/kg, which is higher than the corresponding average value in soils in an area susceptible to endemic fluorosis in China. Based on the characteristic of fluorine speciation, the fluorine in bentonite deposits may pose a risk to the environment. This study makes an important contribution to a better understanding of the characteristic of fluorine speciation in bentonites and the formation mechanism that governs fluorine enrichment in bentonites

Expression of Robo4 in the fibrovascular membranes from patients with proliferative diabetic retinopathy and its role in RF/6A and RPE cells

Purpose: Robo4, a member of the roundabout (Robo) family, acts as a neuronal guidance receptor and plays some role in vasculogenesis and angiogenesis. This study investigated the effect of Robo4 on the formation of fibrovascular membranes (FVMs) from patients with proliferative diabetic retinopathy and its roles in choroid-retina endothelial (RF/6A) and human retinal pigment epithelial (RPE) cells. Methods: RT-PCR and immunohistochemistry were used to determine the levels of mRNA and the presence and distribution of Robo4 in FVMs. Small interfering RNA (siRNA) technology was used to knock down Robo4 expression and to study its effects on RF/6A and RPE cells in vitro. Cell proliferation, migration, spreading, cycling, and apoptosis were assessed with MTT assay, Boyden chamber assay, immunocytochemistry, and flow cytometry. Tube formation by RF/6A on Matrigel was also analyzed. Results: The level of Robo4 mRNA was high in FVMs. Robo4 was expressed in the vessels and fibrous-like tissue co-immunostained for CD31 and GFAP, respectively. Robo4 siRNA knockdown inhibited cell proliferation and migration. Tube formation by RF/6A cells was also disturbed. Under hypoxic conditions, more apoptotic cells were evident among the knockdown cells than among the control cells (p < 0.01). Conclusions: Robo4 may play a role in the formation of FVMs. Silencing the expression of Robo4 in RF/6A and RPE cells inhibited their proliferation and reduced their tolerance of hypoxic conditions, suggesting physiologic functions of Robo4 in the cells of the retina.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000267136400001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Biochemistry & Molecular BiologyOphthalmologySCI(E)PubMed15ARTICLE112-131057-10691