Qubit Systems Inc. » CO2 analysis

MCGES – Multichannel Gas Exchange System

admin — Mon, 26 Jul 2010 20:57:53 +0000

MCGES – Multichannel Gas Exchange System allows studies of metabolism and physiology of living organisms via measurements of gas exchange. Qubit Systems can provide Gas Exchange Systems customized to your specifications and needs, to study photosynthesis, respiration, transpiration, N2-fixation and other processes.

MCGES-Multichannel Gas Exchange System may be controlled by the C950 Multichannel Gas Exchange Software to measure the flow of gases to the samples, through the sample chambers and to the gas analyzers. The C950 software controls all data acquisition from the sensors and analyzers, graphically displays the data and calculates gas exchange rates as required. Please Contact QUBIT with your specifications and we will design your gas exchange system.

In a MCGES the reference gas may be supplied to the system from an air pump or from compressed gas tanks or an air compressor. If several gas mixtures are to be used then a gas mixing system is included (G400). Gasses can be humidified and dehumidified using a humidity controller.

In a multichannel system the gas enters the flow controller where it is split between sample channels, the flow in each channel being controlled by needle valves and measured by separate mass flow monitor. Gas Flow Controllers are available for any number of channels in multiples of four (4 (G248), 8 (G245) channels etc).

Gas enters each sample chamber which may or may not be temperature controlled. The structure of the chamber will depend on the organism. At Qubit, we can build chambers to your specifications. The effluent gas from each chamber enters a Gas Switcher (4 channel - G243, 8 channel – G244) that selects one of the channels for analysis, and vents the others to the atmosphere. Alternatively, the gas flow through the non-selected channels may be stopped, sealing that channel.

Gas from the selected channel is analyzed by one or several analyzers that may be arranged in a series or in parallel. Qubit supplies a wide range of analyzers for measuring CO2, O2, water vapor, H2, CH₄, N2O and other gases. Different analyzers are available across a wide range of gas concentrations and offer various features such as on board data acquisitions, rapid response times etc. We also offer gas conditioning columns, such as scrubbers for water and CO2 (A382).

Qubit Systems personnel have been designing gas exchange systems for over 30 years, and have published extensively on the physiology of respiration, photosynthesis and nitrogen fixation. We are committed to providing researchers with the most appropriate gas exchange system for a particular application at the best possible price, and we are always available to provide expert advice freely without obligation. Contact QUBIT for furhter information.

References:

M. R. Odiere, K. G. Koski, H. A. Weiler and M. E. Scott. Concurrent nematode infection and pregnancy induce physiological responses that impair linear growth in the murine foetus. Parasitology Vol 137, p991-1002 (2010).

Jumbo-Lucioni P, Ayroles JF, Chambers MM, Jorday KW, Leips J, Mackay TFC, DeLuca M. Systems Genetics analysis of body weight and energy metabolism traits in Drosophila melanogaster. BMC Genomics:11 p297- 309 (2010)

S147 Rapid Response O2/CO2 Analyzer

MK — Mon, 26 Jul 2010 20:11:11 +0000

The S147 Rapid Response O2/CO2 Analyzer combines both a laser diode O2 sensor and an infrared CO2 detector. This analyzer is designed for measurements of rapid changes in O2 and CO2 such as those occurring during O2 uptake and CO2 production from breath by breath measurements of human respiration. Please check Qubit’s BBB1LP Breath by Breath Respirometry Package

The S147 Rapid Response O2/CO2 Analyzer has a built in pump which is set at 400 mL/min to draw samples in through the “Gas In” port located on the front of the analyzer. Gases exit the analyzer from the front panel from the “Exhaust” port. There are controls for calibrating the O2 and CO2 sensors on the front panel including the “Zero” and “Span”. You should only adjust the “Span” for CO2 and O2 if you have calibration gases at hand to perform the calibration. Also located on the front panel of the analyzer are an “On/Off” switch with an indicating LED Light and a pump On/Off” switch with an indicating LED Light. The pump speed control should not need adjustment.

The back panel of the S147 Rapid Response Analyzer contains the power jack (115/220 VAC, 115W), an exhaust port for the fan and an Analog Outputs jack. To this jack you should connect the included data collection cable which connects to a data acquisition system. We recommend the C901 LoggerPro data acquisition software for data collection.

The S147 Rapid Response O2/CO2 Analyzer is supplied with F250 Flow meter and asorted connectors and tubing.

Sample of resting breath O2 and CO2 data:

Specifications:

CO2 sensor:

Operating Principle: Infrared Spectroscopy
CO2 Range: 0-13%
Accuracy: +/-2 mm Hg @ < 5.0% CO2, < 10% of reading @ > 5.0% CO2
Operating Temperature: 5o°C to 55°C
Power Consumption: 335 mW
Response Time: Detector: 28 ms , System: 100 ms (typical)
Breath Rate: 2 – 150 bpm

O2 sensor:

Operating Principle: Laser Diode – Optical Absorption
Range: 5% to 100%
Resolution: 0.01 Vol.% O2
Accuracy: 0.1%
Noise (80 ms average): 0.1%
Linearity: 0.2 Vol.%
Drift (2 hrs): 0.1 Vol.%
Response time (T90): 130 ms @ 200 mL/min flow
Operating Temperature: 0^oC to 50^oC
Relative Humidity: 5 to 95%
Operating Pressure: 25 to 115 kPa

S500 – METABOX Metabolic Analyzer

MK — Thu, 06 May 2010 13:03:45 +0000

S500 Metabolic Analyzer (Metabox) is the first combined O2 and CO2 analysis system that allows you to take both your lab and your office into the field. This system is customized to your O2 and CO2 range of analysis. The system can be provide with only O2 or CO2 analyzer. The integrated Tough-book hybrid PC provides hours of operation and comes with Qubit’s C950 gas exchange software that may be customized for your specific requirements ( Contact Qubit). View all your data graphically as they are collected, not just a digital display of values, and use whatever additional programs you wish to crunch numbers and prepare reports. The S500 Metabox gives you perfect flexibility and unsurpassed accuracy packaged in a rugged, easy to carry, waterproof case. Use it in the field (battery pack A247 or A248 optional) or in the lab for your gas exchange measurements.

Features:

Combined O2 and CO2 Measurements
Open and Closed System Gas Analysis
Integrated Gas Pumps
integrated data acqusition interface
Integrated Mass Flow Monitors
Includes Panasonic Tough-book PC
rugged, waterproof case

Applications:

Plant photosynthesis and respiration
Insect Respirometry
Animal Respirometry
Soil Respiration
Atmospheric Monitoring
Gas Exchange Quotient

S158 CO2 Analyzer (0-10%)

MK — Thu, 06 May 2010 12:21:01 +0000

S158 CO2 Analyzer is a single channel non-dispersive infrared CO2 analyzer that measures CO2 in 0 to 10% range with better than 0.01% accuracy. It is ideal for CO2 exchange measurements in larger or more active animals and in situations where high CO2 fluxes may occur, such as fermentation processes. The S158 shares the same infrared technology and modular design as the S157 CO2 Analyzer. The analyzer may be used in a flow-through gas exchange configuration for instantaneous and continuous measurements of CO2 exchange. It can also be used in stop flow or closed system modes. The S158 may also be used as part of Qubit Systems’ carbon dioxide control system for regulating pCO2 in growth cabinet. We recommend using S158 with our C950 Gas Exchange Software or other data acquisitions software.

Features:

Switchable ranges of 0 – 5% and 0 – 10% CO2
0.01% CO2 on digital display, better resolution in software.
Non-dispersive infrared technology
Modulated infrared light source = no moving parts
0 – 5 V analog output at both range settings
Optional battery pack for field use
Compact and portable
Weatherproof case

Applications :

Respirometry in mammals
Exhaled air analysis in humans
Compost monitoring
Monitoring of anaerobic metabolism in yeast colonies
environmental monitoring

Specifications:

Operating principle: Non-dispersive infrared
Gas sampling mode: Flowing gas stream, sealed chamber
Maximum gas flow rate: 650 mL/min
Measurement range (LCD display): 0 – 10.00%
Analog output, low sensitivity: 0 – 10%
Analog output, high sensitivity: 0 – 5%
Accuracy: Better than ± 0.5% of full scale
Repeatability: Better than ±1% of reading
Response time (@ 250 mL/min; to 95% of final value): ca. 30 sec
Warm up time (@ 22^oC): ca. 5 min
Output (linear) for Low Sensitivity setting: 0 – 5 VDC for 0 – 10%
Output (linear) for High Sensitivity setting: 0 – 5 VDC for 0 – 5%
Calibration adjustments: Zero and Span
Operating temperature range: 0 to 50^oC
Storage temperature range: -40 to 70^oC
Humidity range: 5 to 95% RH, non-condensing (recommend drying gas stream)
Pressure dependence: +0.19% reading per mm Hg
Power requirements: 12 VDC via 120 VAC/60 Hz adapter or
Current requirements: 175 mA average, 450 mA peak
Dimensions (cm): (H x W x D: 25.4 x 10.2 x 15.2)
Weight: 2.2 kg
Warranty: 1 year limited

Specifications subject to change without notice

S157 CO2 Analyzer (0-2000ppm)

MK — Wed, 05 May 2010 17:28:58 +0000

The S157 CO2 Analyzer is a single channel non-dispersive infrared CO2 analyzer that measures CO2 in 0 to 2000 ppm range with 1 ppm resolution. This CO2 Analyzer is ideal for CO2 exchange measurements with leaves, insects, small animals or organisms with a low metabolic rate. It is also excellent for measuring soil respiratory activity in the lab and field. The analyzer may be used in a flow-through gas exchange configuration for instantaneous and continuous measurements of CO2 exchange. It can also be used in stop flow or closed system modes for measurements at extremely low activity levels. The S157 CO2 Analyzer shares the same infrared technology and modular design as the S158 CO2 Analyzer. The S157 CO2 Analyzer may also be used as part of Qubit Systems’ carbon dioxide control system for regulating pCO2 in growth cabinet. We recommend using S157 with our C950 Gas Exchange Software or other data acquisitions software.

Features :

Switchable ranges of 0 – 500 ppm and 0 – 2000 ppm CO2
1 ppm carbon dioxide resolution on digital display
Non-dispersive infrared technology
Modulated infrared light source = no moving parts
0 – 5 V analog output at both range settings
Optional battery pack for field use
Compact and portable
Weatherproof case

Applications :

Photosynthetic measurements
Respiration of roots and soil samples
Respirometry of insects and other invertebrates
Head space analysis of cell cultures
Atmospheric monitoring and control
Respiration of small amphibians

Specifications:

Operating principle: Non-dispersive infrared
Gas sampling mode: Flowing gas stream, sealed chamber
Maximum gas flow rate: 650 mL/min
Measurement range (LCD display): 0 – 1999 ppm
Analog output, low sensitivity: 0 – 2000 ppm
Analog output, high sensitivity: 0 – 500 ppm
Accuracy: Better than ± 2% of full scale
Repeatability: Better than ±1% of reading
Maximum drift: (per year) ±100 ppm
Response time : (@ 250 mL/min; to 95% of final value) ca. 45 sec Warm up time (@ 22^oC) ca. 5 min
Output (linear) for Low Sensitivity setting: 0 – 5 VDC for 0 – 2000 ppm
Output (linear) for High Sensitivity setting: 0 – 5 VDC for 0 – 500 ppm
Calibration adjustments : Zero and Span
Operating temperature range: 0 to 50^oC
Storage temperature range: -40 to 70^oC
Operating pressure range: ±1.5% local mean pressure
Humidity range: 5 to 95% RH, non-condensing (recommend drying gas stream)
Pressure dependence: +0.19% reading per mm Hg
Power requirements: 12 VDC via 120 VAC/60 Hz adapter
Current requirements: 175 mA average, 450 mA peak
Dimensions: (cm) (H x W x D: 25.4 x 10.2 x 15.2)
Weight: 2.2 kg
Warranty: 1 year limited

Specifications subject to change without notice

References:

Jumbo-Lucioni P, Ayroles JF, Chambers MM, Jorday KW, Leips J, Mackay TFC, DeLuca M. Systems Genetics analysis of body weight and energy metabolism traits in Drosophila melanogaster. BMC Genomics:11 p297- 309 (2010)

R. F. Krachler, R. Krachler, A. Stojanovic, B. Wielander, and A. Herzig. Effects of pH on aquatic biodegradation Processes. Biogeosciences Discuss.:6, p491–514 ( 2009).

Scarpeci TE, Valle EM. Rearrangement of carbon metabolism in Arabidopsis thaliana subjected to oxidative stress condition: an emergency survival strategy. Plant Growth Regul. 54: 133-142 (2008)

Busi MV, Maliandi MV, Valdez H, Clemente M, Zabaleta EJ, Araya A, Gomez-Casati DF. Deficiency of Arabidopsis thaliana Frataxin alters activity of mitochondrial Fe-S proteins and incudes oxidative stress. The Plant Journal 48: 873-882 (2006)

Q-S153 CO2 Analyzer (0-10%)

MK — Wed, 05 May 2010 17:18:10 +0000

Q-S153 CO2 Analyzer is a single channel non-dispersive infrared CO2 analyzer which measures CO2 in 0 to 5% an 0 to 10% range with 0.01% resolution. Q-S153 replaces our S153 CO2 Analyzer. The same dependable technology has been improved, made more rugged and modular for easy fit in our NEW Q-Box Packages. Q-S153 CO2 analyzer is ideal for CO2 exchange measurements in larger or more active animals and in situations where high CO2 fluxes may occur, such as fermentation processes, human respirometry. Q-S153 may be used in a flow-through gas exchange configuration for instantaneous and continuous measurements of CO2 exchange or as part of Qubit Systems’ carbon dioxide control system for regulating pCO2 in growth cabinets and rooms.

Features :

Switchable ranges of 0 – 5% and 0 – 10% CO2
0.01% CO2 resolution on digital display
Non-dispersive infrared technology
Modulated infrared light source = no moving parts
0 – 5 V analog output at both range settings
Optional battery pack for field use
Compact and portable

Applications :

Respirometry in mammals
Exhaled air analysis in humans
Compost monitoring
Monitoring of anaerobic metabolism in yeast colonies

The Q-S153 CO2 analyzer is included in the following Qubit laboratory packages:

Specifications:

Operating principle: Non-dispersive infrared
Gas sampling mode: Flowing gas stream, sealed chamber
Maximum gas flow rate: 650 mL/min
Measurement range (LCD display): 0 – 10%
Analog output, low sensitivity: 0 – 10%
Analog output, high sensitivity: 0 – 5%
Accuracy: ± 5% of reading or 0.2%
Repeatability: Better than ±1%
Maximum drift (per year): ±0.5%
Response time (@ 250 mL/min; to 95% of final value): ca. 20 sec
Warm up time (@ 22^oC): ca. 5 min
Output (linear) for Low Sensitivity setting: 0 – 5 VDC for 0 –10%
Output (linear) for High Sensitivity setting: 0 – 5 VDC for 0 – 5%
Calibration adjustments: Zero and Span
Operating temperature range: 0 to 50^oC
Storage temperature range: -40 to 70^oC
Operating pressure range: ±1.5% local mean pressure
Humidity range: 5 to 95% RH, non-condensing (recommend drying gas stream)
Pressure dependence: +0.19% reading per mm Hg
Power requirements: 12 VDC via 120 VAC/60 Hz adapter
Current requirements: 175 mA average, 450 mA peak
Dimensions (cm): (H x W x D: 5.5 to 9.5 x 9.5 x 17)
Weight: 1 kg
Warranty: 1 year limited

Specifications subject to change without notice

References:

Mathew B. Sonier and Harold G. Weger. Plasma membrane ferric reductase activity of iron-limited algal cells is inhibited by ferric chelators. Biometals (Online May 2010).

Nikki L. Wirtz, Ron G. Treble and Harold G. Weger. Siderophore-Independent Iron Uptake By Iron-Limited Cells Of The Cyanobacterium Anabaena Flos-Aquae. Journal of Phycology Vol 46, Issue 5, p947–957 (2010).

Christine E. Cooper and Philip C. Withers. Comparative physiology of Australian quolls (Dasyurus; Marsupialia). Journal Of Comparative Physiology B: Biochemical, Systemic, And Environmental Physiology Vol 180, Number 6, p857-868 (2010).

Weger, Harold G.; Lam, Jackie; Wirtz, Nikki L.; Walker, Crystal N.; Treble, Ron G. High stability ferric chelates result in decreased iron uptake by the green alga Chlorella kessleri owing to decreased ferric reductase activity and chelation of ferrous iron. Botany, Vol 87, Number 10, p922-931 (2009).

Christine Elizabeth Cooper and Ariovaldo P. Cruz-Neto. Metabolic, hygric and ventilatory physiology of a hypermetabolic marsupial, the honey possum (Tarsipes rostratus). Journal Of Comparative Physiology B: Biochemical, Systemic, And Environmental Phys Vol 179, Number 6, p773-781 (2009).

Harold G. Weger, Crystal N. Walker and Michael B. Fink. Ferric and cupric reductase activities by iron-limited cells of the green alga Chlorella kessleri: quantification via oxygen electrode. Physiologia Plantarum Vol 131, Issue 2, p322–331 (2007).

Sophie de Seigneux, Hans Malte, Henrik Dimke, Jørgen Frøkiær, Søren Nielsen, and Sebastian Frische. Renal compensation to chronic hypoxic hypercapnia: downregulation of pendrin and adaptation of the proximal tubule. Am J Physiol Renal Physiol Vol 292 Number 4, p1256-1266 (2007).

Yinghao Yu, Juliana A. Ramsay and Bruce A. Ramsay. On-line estimation of dissolved methane concentration during methanotrophic fermentations. Biotechnology and Bioengineering Vol 95, Issue 5, p788–793 (2006).

Stephen E. MacAvoy, Lynne S. Arneson and Ethan Bassett. Correlation of metabolism with tissue carbon and nitrogen turnover rate in small mammals. Oecologia Vol 150, Number 2, p190-201 (2006).

Cameron R. Ralph, Richard D. Reina, Bryan P. Wallace, Paul R. Sotherland, James R. Spotila and Frank V. Paladino . Effect of egg location and respiratory gas concentrations on developmental success in nests of the leatherback turtle, Dermochelys coriacea Australian Journal of Zoology Vol 53, Issue 5, p289–294 (2005).

R. W. Gusztak, R. A. MacArthur and K. L. Campbell. Bioenergetics and thermal physiology of American water shrews ( Sorex palustris). Journal Of Comparative Physiology B: Biochemical, Systemic, And Environmental Phys Vol 175, Number 2, p87-95 (2005).

Hoffmann, Eric J.; Miller, James R. Reassessment of the Role and Utility of Wind in Suppression of Mosquito (Diptera: Culicidae) Host Finding: Stimulus Dilution Supported Over Flight Limitation. Journal of Medical Entomology, Vol 40, Number 5, p607-614 (2003).

Q-S151 CO2 Analyzer (0-2000ppm)

MK — Wed, 05 May 2010 16:45:28 +0000

Q-S151 Infrared CO2 Analyzer is non-dispersive infrared CO2 analyzer that measures CO2 in 0 to 2000 ppm range with 1 ppm resolution. Q-S151 replaces our S151 CO2 Analyzer. The same dependable technology has been improved, made more rugged and modular for easy fit in our NEW Q-Box Packages. Q-S151 is ideal for CO2 exchange measurements with leaves, insects, small animals or organisms with a low metabolic rate. It is also excellent for measuring soil respiratory activity in situ in the field and in the lab. This CO2 analyzer may be used in a flow-through system configuration for instantaneous and continuous measurements of CO2 exchange. It can also be used in a closed system mode for measurements at extremely low activity levels. The Q-S151 is also ideal as part of Qubit Systems’ carbon dioxide control system for regulating pCO2 in growth cabinet or rooms. Contact Qubit for more information on such systems.

Features

Switchable ranges of 0 – 500 ppm and 0 – 2000 ppm CO2
1 ppm CO2 resolution on digital display
Non-dispersive infrared technology
Modulated infrared light source = no moving parts
0 – 5 V analog output at both range settings
Optional battery pack for field use
Compact and portable

Applications:

Photosynthetic measurements
Respiration of roots and soil samples
Respirometry of insects and other invertebrates
Head space analysis of cell cultures
Atmospheric monitoring and control

The Q-S151 CO2 analyzer is included in the following Qubit Research and Teaching Packages:

Specifications:

Operating principle - Non-dispersive infrared
Gas sampling mode - Flowing gas stream, sealed chamber
Maximum gas flow rate - 650 mL/min
Measurement range (LCD display)- 0 – 1999 ppm
Analog output, low sensitivity- 0 – 2000 ppm
Analog output, high sensitivity- 0 – 500 ppm
Accuracy - ± 1 ppm
Repeatability (at stable atm press and temp)- Better than ±1 ppm
Maximum drift (per year) - ±100 ppm
Response time (@ 250 mL/min; to 95% of final value) - ca. 25 sec
Warm up time (@ 22^oC) – ca. 5 min
Output (linear) for Low Sensitivity setting – 0 – 5 VDC for 0 – 2000 ppm
Output (linear) for High Sensitivity setting – 0 – 5 VDC for 0 – 500 ppm
Calibration adjustments – Zero and Span
Operating temperature range – 0 to 50^oC
Storage temperature range - -40 to 70^oC
Operating pressure range - ±1.5% local mean pressure
Humidity range - 5 to 95% RH, non-condensing (recommend drying gas stream)
Pressure dependence – +0.19% reading per mm Hg
Power requirements- 12 VDC via 120 VAC/60 Hz adapter
Current requirements – 125 mA average, 450 mA peak
Dimensions (cm) – (H x W x D: 5.5 to 9.5 x 9.5 x 17)
Weight - 1kg
Warranty - 1 year limited

Specifications subject to change without notice

References:

J. B. Ries, A. L. Cohen and D. C. McCorkle. A nonlinear calcification response to CO₂-induced ocean acidification by the coral Oculina arbuscula. CORAL REEFS Vol 29, Number 3, p661-674 (2010).

Nann A. Fangue, Michael J. O’Donnell, Mary A. Sewell, Paul G. Matson, Anna C. MacPherson, and Gretchen E. Hofmann. A laboratory-based, experimental system for the study of ocean acidification effects on marine invertebrate larvae. Limnol. Oceanogr.: Methods 8, p441–452 (2010).

Scott Carver, Ben D. Bell, and Bruce Waldman. Does Chytridiomycosis Disrupt Amphibian Skin Function? Copeia Vol. 2010, No. 3, p487-495 (2010).

Simone E. Kolb, Kevin J. Fermanich and Mathew E. Dornbush. Effect of Charcoal Quantity on Microbial Biomass and Activity in Temperate Soils. SSSAJ: Vol 73, Number 4, p1173-1181. (2009).

Salvador Nogués, Iker Aranjuelo, Antoni Pardo and Joaquim Azcón-Bieto. Assessing the stable carbon isotopic composition of intercellular CO₂ in a CAM plant using gas chromatography-combustion-isotope ratio mass spectrometry. Rapid Communications in Mass Spectrometry; Vol 22, Issue 7, p1017–1022 (2008).

Stephen D. LeDuc and David E. Rothstein. Initial recovery of soil carbon and nitrogen pools and dynamics following disturbance in jack pine forests: A comparisonof wildfire and clearcut harvesting. Soil Biology & Biochemistry Vol 39 p2865–2876 (2007).

Nuria Gomez-Casanovas, Elena Blanc-Betes, Miquel A. Gonzalez-Meler and Joaquim Azcon-Bieto. Changes in Respiratory Mitochondrial Machinery and Cytochrome and Alternative Pathway Activities in Response to Energy Demand Underlie the Acclimation of Respiration to Elevated CO₂ in the Invasive Opuntia ficus-indica. Plant Physiology Vol 145 p49-61 (2007).

U. Rascher, E. G. Bobich, C. B. Osmond. The Kluge-Lüttge Kammer: A Preliminary Evaluation of an Enclosed, Crassulacean Acid Metabolism (CAM) Mesocosm that Allows Separation of Synchronized and Desynchronized Contributions of Plants to Whole System Gas Exchange. Plant biol (Stuttg) Vol. 8, number 1, p167-174 (2006).

Jean E.T. McLain and Dean A. Martens. N₂O production by heterotrophic N transformations in a semiarid soil. Applied Soil Ecology Vol 32, Issue 2 p253-263 (2006).

J.E.T McLain and D.A. Martens. Moisture controls on trace gas fluxes in semiarid riparian soils. Science Society of America journal. Vol 70, Number 2, p.367-377 (2006).

Jean E.T. McLain and Dean A. Martens. Nitrous oxide flux from soil amino acid mineralization. Soil Biology and Biochemistry. Vol 37, Issue 2, p289-299 (2005).

Mark O. Baerlocher, Douglas A. Campbell, and Robert J. Ireland. Developmental progression of photosystem II electron transport and CO₂ uptake inSpartina alterniflora, a facultative halophyte, in a northern salt marsh. Can. J. Bot. Vol. 82, Number 3, p365–375 (2004)

L.H. Ziska, J.A. Bunce and E.W. Goins. Characterization of an urban-rural CO ₂/temperature gradient and associated changes in initial plant productivity during secondary succession. OECOLOGIA Volume 139, Number 3, p454-458 (2004).

Y.P. Cen and D. B. Layzell. Does oxygen limit nitrogenase activity in soybean exposed to elevated CO₂? Plant, Cell & Environment Vol 27, Issue 10, p1229–1238 (2004).

Lewis H. Ziska, PhD, Dennis E. Gebhard, David A. Frenz, MD, Shaun Faulkner Benjamin D. Singerd and James G. Straka, PhD. Cities as harbingers of climate change: Common ragweed, urbanization, and public health. J ALLERGY CLIN IMMUNOL, Vol 111, Number 2, p290-294 (2003).

Colette A. Sacksteder and David M. Kramer. Dark-interval relaxation kinetics (DIRK) of absorbance changes as a quantitative probe of steady-state electron transfer. P HOTOSYNTHESIS RESEARCH Vol 66, Numbers 1-2, p145-158 (2000).