Geobiology of Andean Microbial Ecosystems Discovered in Salar de Atacama, Chile

The Salar de Atacama in the Chilean Central Andes harbors unique microbial ecosystems due to extreme environmental conditions, such as high altitude, low oxygen pressure, high solar radiation, and high salinity. Combining X-ray diffraction analyses, scanning electron microscopy and molecular diversity studies, we have characterized twenty previously unexplored Andean microbial ecosystems in eight different lakes and wetlands from the middle-east and south-east regions of this salt flat. The mats and microbialites studied are mainly formed by calcium carbonate (aragonite and calcite) and halite, whereas the endoevaporites are composed predominantly of gypsum and halite. The carbonate-rich mats and microbialites are dominated by Bacteroidetes and Proteobacteria phyla. Within the phylum Proteobacteria, the most abundant classes are Alphaproteobacteria, Gammaproteobacteria and Deltaproteobacteria. While in the phylum Bacteroidetes, the most abundant classes are Bacteroidia and Rhodothermia. Cyanobacteria, Chloroflexi, Planctomycetes, and Verrucomicrobia phyla are also well-represented in the majority of these systems. Gypsum endoevaporites, on the contrary, are dominated by Proteobacteria, Bacteroidetes, and Euryarchaeota phyla. The Cyanobacteria phylum is also abundant in these systems, but it is less represented in comparison to mats and microbialites. Regarding the eukaryotic taxa, diatoms are key structural components in most of the microbial ecosystems studied. The genera of diatoms identified were Achnanthes, Fallacia, Halamphora, Mastogloia, Navicula, Nitzschia, and Surirella. Normally, in the mats and microbialites, diatoms form nano-globular carbonate aggregates with filamentous cyanobacteria and other prokaryotic cells, suggesting their participation in the mineral precipitation process. This work expands our knowledge of the microbial ecosystems inhabiting the extreme environments from the Central Andes region, which is important to ensure their protection and conservation.

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Microbial Ecosystems in Central Andes Extreme Environments

10.1007/978-3-030-36192-1 ◽

2020 ◽

Keyword(s):

Extreme Environments ◽

Central Andes ◽

Microbial Ecosystems

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Socioeconomic Conditions and Landowners’ Perception Affect the Intention to Restore Polylepis Forests in the Central Andes of Peru

Forests ◽

10.3390/f12020118 ◽

2021 ◽

Vol 12 (2) ◽

pp. 118

Author(s):

Lunel Joseph ◽

Raúl Marino Yaranga Cano ◽

Marco Arizapana-Almonacid ◽

Marcela Venelli Pyles ◽

Flávia Freire de Siqueira ◽

...

Keyword(s):

Rural Communities ◽

Mixed Model ◽

Linear Mixed Model ◽

Negative Impact ◽

Positive Impact ◽

Central Andes ◽

Socioeconomic Conditions ◽

Native Flora ◽

The Family ◽

Andes Region

Research Highlights: Families more dependent on crops as the main source of income of properties have a greater intention of restoring Polylepis forest areas. However, this intention reduces with the increase of family dependence on subsistence products supplied by Polylepis forests. Properties where the chances of restoration of Polylepis forests are greater are those where the educational and technical level is better. Objectives: We aimed to comprehend which socioeconomic factors of rural properties and families’ perception were determinant for the intention to restore Polylepis forests in the Central Andes region of Peru. Material and Methods: We collected data through visits and the application of questionnaires. We selected 13 rural communities in the Tulumayo River Basin. We randomly sampled 10 to 20 families in each community, depending on its size, totaling 200 families. We used generalized linear mixed model (GLMM) to test which variables affect the intention to restore the forest. Results: When crops are the main source of income in the property, the families have more intention to restore Polylepis areas, on the other hand, when Polylepis forests are an important source of products for the family subsistence, the intention to restore forests reduces, indicating that higher technological status has a positive impact on restoration. The perception that Polylepis forests are important for the existence of water sources had a positive impact on the families’ intention to restore the areas. However, the perception that Polylepis forests are important for native flora persistence had a negative impact on the intention to restore their areas. Conclusions: Our results showed that investment in improving the productivity of the properties and in the education of their landowners should increase the success of eventual programs for restoration of Polylepis forests.

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The effect of NADH and low oxygen pressure on the hepatic microsomal ethylmorphine N-demethylase activity of the male rat.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(20)81903-6 ◽

1983 ◽

Vol 258 (9) ◽

pp. 5400-5404

Author(s):

J L Holtzman ◽

J E Gander ◽

R R Erickson

Keyword(s):

Oxygen Pressure ◽

Male Rat ◽

Low Oxygen ◽

Demethylase Activity ◽

Low Oxygen Pressure

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Enhanced Water Solubility and Oral Bioavailability of Paclitaxel Crystal Powders through an Innovative Antisolvent Precipitation Process: Antisolvent Crystallization Using Ionic Liquids as Solvent

Pharmaceutics ◽

10.3390/pharmaceutics12111008 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1008 ◽

Cited By ~ 1

Author(s):

Qilei Yang ◽

Chang Zu ◽

Wengang Li ◽

Weiwei Wu ◽

Yunlong Ge ◽

...

Keyword(s):

Oral Bioavailability ◽

High Performance ◽

Water Solubility ◽

Water Soluble ◽

Precipitation Process ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Antisolvent Precipitation ◽

Antisolvent Crystallization ◽

Artificial Gastric Juice

Paclitaxel (PTX) is a poor water-soluble antineoplastic drug with significant antitumor activity. However, its low bioavailability is a major obstacle for its biomedical applications. Thus, this experiment is designed to prepare PTX crystal powders through an antisolvent precipitation process using 1-hexyl-3-methylimidazolium bromide (HMImBr) as solvent and water as an antisolvent. The factors influencing saturation solubility of PTX crystal powders in water in water were optimized using a single-factor design. The optimum conditions for the antisolvent precipitation process were as follows: 50 mg/mL concentration of the PTX solution, 25 °C temperature, and 1:7 solvent-to-antisolvent ratio. The PTX crystal powders were characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, high-performance liquid chromatography–mass spectrometry, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Raman spectroscopy, solid-state nuclear magnetic resonance, and dissolution and oral bioavailability studies. Results showed that the chemical structure of PTX crystal powders were unchanged; however, precipitation of the crystalline structure changed. The dissolution test showed that the dissolution rate and solubility of PTX crystal powders were nearly 3.21-folds higher compared to raw PTX in water, and 1.27 times higher in artificial gastric juice. Meanwhile, the bioavailability of PTX crystal increased 10.88 times than raw PTX. These results suggested that PTX crystal powders might have potential value to become a new oral PTX formulation with high bioavailability.

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Oxidation of Fe-24%Cr-11%Mo at room temperature and low oxygen pressure

Surface Science Letters ◽

10.1016/0167-2584(89)90952-3 ◽

1989 ◽

Vol 214 (3) ◽

pp. A267

Author(s):

C. Palacio ◽

H.J. Mathieu ◽

D. Landolt

Keyword(s):

Oxygen Pressure ◽

Room Temperature ◽

Low Oxygen ◽

Low Oxygen Pressure

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On the vacancy formation and diffusion on the Si(111)7×7 surfaces under exposures of low oxygen pressure studied by in situ reflection electron microscopy

Surface Science ◽

10.1016/s0039-6028(87)81046-4 ◽

1987 ◽

Vol 191 (1-2) ◽

pp. 28-44 ◽

Cited By ~ 37

Author(s):

N. Shimizu ◽

Y. Tanishiro ◽

K. Takayanagi ◽

K. Yagi

Keyword(s):

Electron Microscopy ◽

Oxygen Pressure ◽

Vacancy Formation ◽

Low Oxygen ◽

Reflection Electron Microscopy ◽

And Diffusion ◽

Low Oxygen Pressure

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TEM and X-Ray Examinations of Intermetallic Phases and Carbides Precipitation in an Fe-Ni Superalloy during Prolonged Ageing

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.212.15 ◽

2013 ◽

Vol 212 ◽

pp. 15-20

Author(s):

Kazimierz J. Ducki ◽

Jacek Mendala ◽

Lilianna Wojtynek

Keyword(s):

Heat Treatment ◽

Solution Heat Treatment ◽

Intermetallic Phase ◽

Intermetallic Phases ◽

Precipitation Process ◽

Secondary Phases ◽

X Ray Diffraction ◽

Solid Samples ◽

Structural Investigations ◽

X Ray

The influence of prolonged ageing on the precipitation process of the secondary phases in an Fe-Ni superalloy of A-286 type has been studied. The samples were subjected to a solution heat treatment at 980°C for 2 h and water quenched, and then aged at temperatures of 715, 750 and 780°C at holding times from 0.5 to 500 h. Structural investigations were conducted using TEM and X-ray diffraction methods. The X-ray phase analyses performed on the isolates were obtained by anodic dissolution of the solid samples. After solution heat treatment the alloy has the structure of twinned austenite with a small amount of undissolved precipitates, such as carbide TiC, carbonitride TiC0.3N0.7, nitride TiN0.3, carbosulfide Ti4C2S2, Laves phase Ni2Si, and boride MoB. The application of ageing causes precipitation processes of γ-Ni3(Al,Ti), G (Ni16Ti6Si7), η (Ni3Ti), β (NiTi) and σ (Cr0.46Mo0.40Si0.14) intermetallic phases, as well as the carbide M23C6. It was found that the main phase precipitating during alloy ageing was the γ intermetallic phase.

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Purification, Crystallization and Preliminary X-Ray Diffraction Studies on Goat (Capra hircus) Hemoglobin - A Low Oxygen Affinity Species

Protein and Peptide Letters ◽

10.2174/092986609787847992 ◽

2009 ◽

Vol 16 (4) ◽

pp. 454-456 ◽

Cited By ~ 1

Author(s):

Ponnuraj Moorthy ◽

Kamariah Neelagandan ◽

Moovarkumudalvan Balasubramanian ◽

Mondikalipudur Ponnuswamy

Keyword(s):

Oxygen Affinity ◽

Capra Hircus ◽

Low Oxygen ◽

X Ray Diffraction ◽

X Ray ◽

Hemoglobin A ◽

Low Oxygen Affinity

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Zirconium Titanate: Synthesis and Processing of Fine Powders Prepared by Chemical Route

Materials Science Forum ◽

10.4028/www.scientific.net/msf.530-531.683 ◽

2006 ◽

Vol 530-531 ◽

pp. 683-688 ◽

Cited By ~ 1

Author(s):

Valter Ussui ◽

Dolores Ribeiro Ricci Lazar ◽

Nelson Batista de Lima ◽

Ana Helena A. Bressiani ◽

José Octavio A. Pascoal

Keyword(s):

Metal Salt ◽

Ceramic Powder ◽

Ammonium Hydroxide ◽

Molar Ratio ◽

Precipitation Process ◽

Zirconium Titanate ◽

X Ray Diffraction ◽

Chemical Route ◽

Synthesis And Processing ◽

Cylindrical Samples

A process for synthesis of fine zirconium titanate powders by chemical route is described. Zirconium/titanium molar ratio was varied from 0.67 to 1.5 and the powders produced were analyzed. The precipitation process comprises the mixture of zirconium and titanium metal salt solutions to ammonium hydroxide solution, followed by washing of the precipitate, calcination and grinding to result in zirconium titanate. The ceramic powder is then uniaxially pressed as cylindrical samples and sintered at 1400°C for 5 hours. The microstructure of fractured and thermally etched ceramic was observed by scanning electron microscopy, and crystal phase identifications were done by X-ray diffraction. At least two different zirconium titanate phases, ZrTiO4 and Zr5Ti7O24, were identified. Ceramic hardness was measured by Vickers indentation.

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