scholarly journals Technical note: CO<sub>2</sub> is not like CH<sub>4</sub> – limits of and corrections to the headspace method to analyse <i>p</i>CO<sub>2</sub> in fresh water

2021 ◽  
Vol 18 (5) ◽  
pp. 1619-1627
Author(s):  
Matthias Koschorreck ◽  
Yves T. Prairie ◽  
Jihyeon Kim ◽  
Rafael Marcé
Keyword(s):  
Fresh Water ◽  
Direct Method ◽  
Headspace Analysis ◽  
Ambient Air ◽  
Technical Note ◽  
High Pco2 ◽  
Experimental Conditions ◽  
Different Types ◽  
Chemical Equilibration ◽  
Carbonate Equilibrium

Abstract. Headspace analysis of CO2 frequently has been used to quantify the concentration of CO2 in fresh water. According to basic chemical theory, not considering chemical equilibration of the carbonate system in the sample vials will result in a systematic error. By analysing the potential error for different types of water and experimental conditions, we show that the error incurred by headspace analysis of CO2 is less than 5 % for typical samples from boreal systems which have low alkalinity (< 900 µmol L−1), with pH < 7.5, and high pCO2 (> 1000 µatm). However, the simple headspace calculation can lead to high error (up to −300 %) or even impossibly negative values in highly undersaturated samples equilibrated with ambient air, unless the shift in carbonate equilibrium is explicitly considered. The precision of the method can be improved by lowering the headspace ratio and/or the equilibration temperature. We provide a convenient and direct method implemented in an R script or a JMP add-in to correct CO2 headspace results using separately measured alkalinity.

scholarly journals Technical note: CO<sub>2</sub> is not like CH<sub>4</sub> – limits of and corrections to the headspace method to analyse <i>p</i>CO<sub>2</sub> in water

2020 ◽  
Author(s):  
Matthias Koschorreck ◽  
Yves T. Prairie ◽  
Jihyeon Kim ◽  
Rafael Marcé
Keyword(s):  
Systematic Error ◽  
Headspace Analysis ◽  
Technical Note ◽  
Simple Application ◽  
Carbonate System ◽  
Experimental Conditions ◽  
Potential Error ◽  
Chemical Theory ◽  
Different Types ◽  
Chemical Equilibration

Abstract. Headspace analysis of CO2 frequently has been used to quantify the concentration of CO2 in freshwater. According to basic chemical theory, not considering chemical equilibration of the carbonate system in the sample vials will result in a systematic error. In this paper we provide a method to quantify the potential error resulting from simple application of Henry's law to headspace CO2 samples. By analysing the potential error for different types of water and experimental conditions we conclude that the error incurred by headspace analysis of CO2 is less than 5 % for samples with pH 

Impact of Chromium on Lactate in different types of muscles of a fresh water fish, Labeorohita

2012 ◽  
Vol 3 (6) ◽  
pp. 483-484
Author(s):  
M. Cynthia Sailaja ◽  
◽  
G. Vijay Kumar ◽  
K. Jayantha Rao
Keyword(s):  
Fresh Water ◽  
Fresh Water Fish ◽  
Water Fish ◽  
Different Types

Early Spelling Acquisition: Does Writing Really Beat the Computer?

1992 ◽  
Vol 15 (3) ◽  
pp. 223-228 ◽  
Author(s):  
Sharon Vaughn ◽  
Jeanne Shay Schumm ◽  
Jane Gordon
Keyword(s):  
Learning Disabled ◽  
Primary Grade ◽  
Group Differences ◽  
Experimental Conditions ◽  
Spelling Acquisition ◽  
Instructional Activity ◽  
Study Results ◽  
Different Types ◽  
Computer Based ◽  
Based Instruction

This research evaluated the efficacy of handwriting, letter tiles, and computer-based instruction on the early spelling acquisition of normal achieving (NLD) and learning disabled (LD) elementary students. The study replicated and extended the Cunningham and Stanovich (1990) study. Forty-eight primary-grade students (24 non-learning disabled; 24 learning disabled) received spelling training under three experimental conditions that involved different types of instructional activity: writing, sorting letter tiles, or typing on the computer. Results indicated no significant differences between the LD and NLD groups on words spelled correctly for any of the three conditions. Since the number of spelling words learned was low across conditions and groups, the number of correctly learned bigrams was examined. No within-group differences emerged for condition (writing, tile, computer); however, significant differences between the groups were found on number of bigrams learned for writing, tile, and computer, with the NLD group outperforming the LD group on all three conditions. Statistically significant time effects for bigrams were also noted for all three conditions. Unlike the Cunningham and Stanovich (1990) study, results did not replicate the superiority of the handwriting condition for the NLD group, nor was the handwriting condition found to be significantly more effective for the LD group.

scholarly journals Combination of Autohydrolysis and Catalytic Hydrolysis of Biomass for the Production of Hemicellulose Oligosaccharides and Sugars

Reactions ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 30-46
Author(s):  
Léa Vilcocq ◽  
Agnès Crepet ◽  
Patrick Jame ◽  
Florbela Carvalheiro ◽  
Luis C. Duarte
Keyword(s):  
Agricultural Waste ◽  
Solid Acid Catalyst ◽  
Acid Catalyst ◽  
Energy Crop ◽  
Catalytic Hydrolysis ◽  
Experimental Conditions ◽  
Different Types ◽  
Hemicellulosic Sugars ◽  
Hydrolysis Of

Three different types of biomass sourced from forestry waste (eucalyptus residues), agricultural waste (wheat straw), and energy crop (miscanthus) were used as starting materials to produce hemicellulosic sugars, furans (furfural and hydroxymethylfurfural), and oligosaccharides. A two-step hybrid process was implemented; biomass was first autohydrolysed without any additive to extract hemicelluloses and dissolve it in water. Then, the hydrolysate was treated with a solid acid catalyst, TiO2-WOx, in order to achieve hydrolysis and produce monomeric sugars and furans. This article investigates the role of the biomass type, autohydrolysis experimental conditions, polymerisation degree and composition of hemicelluloses on the performance of the process coupling autohydrolysis and catalytic hydrolysis. The highest global yields of both oligosaccharides and monomeric sugars were obtained from Eucalyptus (37% and 18%, respectively).

scholarly journals Technical note: Stability of tris pH buffer in artificial seawater stored in bags

Ocean Science ◽  
2021 ◽  
Vol 17 (3) ◽  
pp. 819-831
Author(s):  
Wiley H. Wolfe ◽  
Kenisha M. Shipley ◽  
Philip J. Bresnahan ◽  
Yuichiro Takeshita ◽  
Taylor Wirth ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Technical Note ◽  
Artificial Seawater ◽  
Upper And Lower Bounds ◽  
Sensor Calibration ◽  
Time Data ◽  
Ph Change ◽  
Ph Measurements ◽  
Experimental Conditions ◽  
Initial Ph

Abstract. Equimolal tris (2-amino-2-hydroxymethyl-propane-1,3-diol) buffer in artificial seawater is a well characterized and commonly used standard for oceanographic pH measurements. We evaluated the stability of tris pH when stored in purportedly gas-impermeable bags across a variety of experimental conditions, including bag type and storage in air vs. seawater over 300 d. Bench-top spectrophotometric pH analysis revealed that the pH of tris stored in bags decreased at a rate of 0.0058±0.0011 yr−1 (mean slope ±95 % confidence interval of slope). The upper and lower bounds of expected pH change at t=365 d, calculated using the averages and confidence intervals of slope and intercept of measured pH change vs. time data, were −0.0042 and −0.0076 from initial pH. Analyses of total dissolved inorganic carbon confirmed that a combination of CO2 infiltration and/or microbial respiration led to the observed decrease in pH. Eliminating the change in pH of bagged tris remains a goal, yet the rate of pH change is lower than many processes of interest and demonstrates the potential of bagged tris for sensor calibration and validation of autonomous in situ pH measurements.

scholarly journals Laser filament-induced aerosol formation

2013 ◽  
Vol 13 (9) ◽  
pp. 4593-4604 ◽  
Author(s):  
H. Saathoff ◽  
S. Henin ◽  
K. Stelmaszczyk ◽  
M. Petrarca ◽  
R. Delagrange ◽  
...  
Keyword(s):  
Particle Production ◽  
Ambient Air ◽  
Particle Formation ◽  
Oxygen Mixture ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Experimental Conditions ◽  
Particle Yield ◽  
The Given ◽  
Terawatt Laser

Abstract. Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

scholarly journals Ocean acidification and high irradiance stimulate the photo-physiological fitness, growth and carbon production of the Antarctic cryptophyte <i>Geminigera cryophila</i>

2019 ◽  
Vol 16 (15) ◽  
pp. 2997-3008 ◽  
Author(s):  
Scarlett Trimborn ◽  
Silke Thoms ◽  
Pascal Karitter ◽  
Kai Bischof
Keyword(s):  
Ocean Acidification ◽  
Coastal Waters ◽  
High Irradiance ◽  
High Pco2 ◽  
Experimental Conditions ◽  
Phytoplankton Assemblages ◽  
Beneficial Effects ◽  
Carbon Production ◽  
Geminigera Cryophila ◽  
The Antarctic

Abstract. Ecophysiological studies on Antarctic cryptophytes to assess whether climatic changes such as ocean acidification and enhanced stratification affect their growth in Antarctic coastal waters in the future are lacking so far. This is the first study that investigates the combined effects of the increasing availability of pCO2 (400 and 1000 µatm) and irradiance (20, 200 and 500 µmol photons m−2 s−1) on growth, elemental composition and photophysiology of the Antarctic cryptophyte Geminigera cryophila. Under ambient pCO2, this species was characterized by a pronounced sensitivity to increasing irradiance with complete growth inhibition at the highest light intensity. Interestingly, when grown under high pCO2 this negative light effect vanished, and it reached the highest rates of growth and particulate organic carbon production at the highest irradiance compared to the other tested experimental conditions. Our results for G. cryophila reveal beneficial effects of ocean acidification in conjunction with enhanced irradiance on growth and photosynthesis. Hence, cryptophytes such as G. cryophila may be potential winners of climate change, potentially thriving better in more stratified and acidic coastal waters and contributing in higher abundance to future phytoplankton assemblages of coastal Antarctic waters.

scholarly journals Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

2017 ◽  
Vol 10 (5) ◽  
pp. 1911-1926 ◽  
Author(s):  
Caroline C. Womack ◽  
J. Andrew Neuman ◽  
Patrick R. Veres ◽  
Scott J. Eilerman ◽  
Charles A. Brock ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Reactive Nitrogen Species ◽  
Thermal Dissociation ◽  
Ambient Air ◽  
Reactive Nitrogen ◽  
Organic Nitrates ◽  
Nitrogen Species ◽  
Operating Characteristics ◽  
Experimental Conditions ◽  
Standard Additions

Abstract. The sum of all reactive nitrogen species (NOy) includes NOx (NO2 + NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at > 600 °C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400 °C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6 % and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650 °C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5–10 %) of NH3 to NO at 650 °C in the presence of representative (50 ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.

scholarly journals Facile Fabrication of Biochar from Palm Kernel Shell Waste and Its Novel Application to Magnesium-Based Materials for Hydrogen Storage

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 625 ◽  
Author(s):  
Martin Luther Yeboah ◽  
Xinyuan Li ◽  
Shixue Zhou
Keyword(s):  
Hydrogen Storage ◽  
Palm Kernel ◽  
Cost Effective ◽  
Ambient Air ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Palm Kernel Shell ◽  
Cost Effective Method ◽  
Facile Fabrication

In this investigation, an easily-operated and cost-effective method is utilized to synthesize biochar in ambient air, and the prepared biochar is used in a novel manner as a milling aid for fabricating Mg-biochar composites for hydrogen storage. X-ray diffractometry reveals that increasing the content of palm kernel shell biochar (PKSBC) from 5 wt.% to 20 wt.% enhances the hydrogen absorption performance by increasing the conversion of Mg into MgH2 from 83% to 93%. A 40 °C reduction in decomposition temperature of MgH2 is recorded from differential scanning calorimetry curves when the content of PKSBC is increased to 20 wt.%. Magnesium is milled and hydrided under the same experimental conditions and used as a reference material. It is proposed that these property enhancements can be attributed to the fact that PKSBC acts as an anti-sticking agent for elemental Mg powders, helping in the achievement of a more dispersed composite with reduced Mg particle size due to its layered-like carbon structure.

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