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Your search keyword '"Ran, Yu"' showing total 4 results
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4 results on '"Ran, Yu"'

1. Mixotrophic Cultivation of Microalgae Using Biogas as the Substrate

Author

Xin Li, Yongze Lu, Na Li, Yongzhen Wang, Ran Yu, Guangcan Zhu, and Raymond Jianxiong Zeng

Subjects
Nitrogen, Biofuels, Microalgae, Environmental Chemistry, Biomass, General Chemistry, Biotechnology
Abstract

Biogas utilization through biotechnology represents a potential and novel technology. We propose the microalgal mixotrophic cultivation to convert biogas to microalgae-based biodiesel, in which methanotroph was co-cultured to convert CH

Published
2022

2. Seasonal Arsenic Accumulation in Stream Sediments at a Groundwater Discharge Zone

Author

Allison A. MacKay, Ran Yu, Ping Gan, and Barth F. Smets

Subjects
Geologic Sediments, Iron, Iron oxide, chemistry.chemical_element, Direct reduced iron, Arsenic, chemistry.chemical_compound, Rivers, Freezing, Spring (hydrology), New Hampshire, Environmental Chemistry, Groundwater discharge, Groundwater, geography, geography.geographical_feature_category, Sorption, General Chemistry, Biodegradation, Environmental, chemistry, Environmental chemistry, Adsorption, Seasons, Surface water, Water Pollutants, Chemical
Abstract

Seasonal changes in arsenic and iron accumulation rates were examined in the sediments of a brook that receives groundwater discharges of arsenic and reduced iron. Clean glass bead columns were deployed in sediments for known periods over the annual hydrologic cycle to monitor changes in arsenic and iron concentrations in bead coatings. The highest accumulation rates occurred during the dry summer period (July-October) when groundwater discharges were likely greatest at the sample locations. The intermediate flow period (October-March), with higher surface water levels, was associated with losses of arsenic and iron from bead column coatings at depths below 2-6 cm. Batch incubations indicated iron releases from solids to be induced by biological reduction of iron (oxy)hydroxide solids. Congruent arsenic releases during incubation were limited by the high arsenic sorption capacity (0.536 mg(As)/mg(Fe)) of unreacted iron oxide solids. The flooded spring (March-June) with high surface water flows showed the lowest arsenic and iron accumulation rates in the sediments. Comparisons of accumulation rates across a shoreline transect were consistent with greater rates at regions exposed above surface water levels for longer times and greater losses at locations submerged below surface water. Iron (oxy)hydroxide solids in the shallowest sediments likely serve as a passive barrier to sorb arsenic released to pore water at depth by biological iron reduction.

Published
2013

4. Mechanisms and Specific Directionality of Autotrophic Nitrous Oxide and Nitric Oxide Generation during Transient Anoxia.

Author

RAN YU, KAMPSCHREUR, MARLIES J., VAN LOOSDRECHT, MARK C. M., and CHANDRAN, KARTIK

Subjects
*MICROBIAL metabolism, *RESEARCH methodology, *CONTINUOUS culture (Microbiology), *HYPOXIA (Water), *DISSOLVED oxygen in water, *NITRIFYING bacteria, *NITROUS oxide, *NITRIC oxide, *BACTERIAL genetics
Abstract

The overall goal of this study was to determine the molecular and metabolic responses of chemostat cultures of model nitrifying bacteria to imposition of and recovery from transient anoxic conditions. Based on the study, a specific directionality in nitrous oxide (N2O) and nitric oxide (NO) production was demonstrated. N2O production was only observed during recovery to aerobic conditions after a period of anoxia and correlated positively with the degree of ammonia accumulation during anoxia. NO, on the other hand, was emitted mainly under anoxia. The production of NO was linked to a major imbalance in the expression of the nitrite reductase gene, which was overexpressed during transient anoxia. In contrast, genes coding for ammonia and hydroxylamine oxidation and nitric oxide reduction were generally under-expressed during transient anoxia. These results are different from the observed parallel expression and activity of nitrite and nitric oxide reductase in heterotrophic bacteria subjected to transient oxygen cycling. Unlike NO, the production of N2O could not be solely correlated to gene expression patterns and likely involved responses at the enzyme activity or metabolic levels. Based on experimental data, the propensity of the nitrifying cultures for N2O production is related to a shift in their metabolism from a low specific activity (q < qmax) toward the maximum specific activity (qmax). [ABSTRACT FROM AUTHOR]

Published
2010
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