Crop responses to CO2 enrichment

Carbon dioxide is rising in the global atmosphere, and this increase can be expected to continue into the foreseeable future. This compound is an essential input to plant life. Crop function is affected across all scales from biochemical to agro-ecosystem. An array of methods (leaf cuvettes, field chambers, free-air release systems) are available for experimental studies of CO₂ effects. Carbon dioxide enrichment of the air in which crops grow usually stimulates their growth and yield. Plant structure and physiology are markedly altered. Interactions between CO₂ and environmental factors that influence plants are known to occur. Implications for crop growth and yield are enormous. Strategies designed to assure future global food security must include a consideration of crop responses to elevated atmospheric CO₂. Future research should include these targets: search for new insights, development of new techniques, construction of better simulation models, investigation of belowground processes, study of interactions, and the elimination of major discrepancies in the scientific knowledge base.     

Direct resolution of enantiomers of basic imidazol-2-yl-substituted alcohols by gas chromatography on chirasil-val

The direct resolution of enantiomers of a series of imidazol-2-yl-substituted alcohols has been achieved by gas chromatography on a well-deactivated fused-silica capillary column, coated with L -Chirasil-Val as the chiral stationary phase. The separation of these basic compounds is accomplished without exaggerated peak tailing. Compared to simpler alcohols the resolution factors (α) observed are extraordinarily large. While the imidazolyl substituent may contribute to the mechanism of the chiral discrimination, the crucial interaction is assumed to be through the hydroxy group, based on the observation that the resolution factors for the corresponding O-acetyl derivatives are markedly reduced. © 1993 Wiley-Liss, Inc.     

Benzoylcellulose derivatives as chiral stationary phases for open tubular column chromatography

The application of cellulose-based stationary phases for chiral separations has been extended to open tubular column chromatography. Efficient columns were obtained by coating the capillaries with mixtures of chiral cellulose materials and conventional achiral stationary phases for gas chromatography. In this study, various siloxane and polyethylene glycol polymers were used as achiral components and mixed with different substituted benzoylcellulose derivatives as chiral components. Systematic investigations were carried out to determine the optimal ratio for the components of the stationary phase. Depending on the chromatographic mode—gas chromatography (GC) or supercritical fluid chromatography (SFC)—the stationary phases were found to behave differently. The applicability of the technique was demonstrated by the resolution of various racemic compounds. © 1993 Wiley-Liss, Inc.     

High-Resolution Performance of Polycaprolactone Functionalized with Guanidinium Ionic Liquid for Gas Chromatography

This work firstly reported a new polycaprolactone based material functionalized with guanidinium ionic liquid (PCL-GIL) as the stationary phase with high resolution performance for capillary gas chromatography (GC). It is composed of polycaprolactone (PCL) and guanidinium ionic liquid (GIL) with amphiphilic conformation. The PCL-GIL capillary column coated by static method exhibited high column efficiency of 3942 plates/m and moderate polarity. As a result, the PCL-GIL column exhibited high-resolution capability. For a mixture of 27 analytes with a wide ranging polarity and outperformed the PCL-2OH and HP-35 columns, showing its advantageous separation capability for analytes of diverse types. Moreover, the PCL-GIL column showed high resolving capability for various positional isomers and cis-/trans-isomers, including alkylbenzenes, chlorobenzenes, naphthalenes, bromonitrobenzenes, chloronitrobenzenes, benzaldehydes, phenols, alcohols, respectively. In a word, PCL derivatized by GIL units as a new type of stationary phase has a promising future in GC separations.     

Simplified methods for monitoring petroleum‐contaminated ground water and soil vapor

Portable meters and simplified gas Chromatographic (GC) techniques were investigated for monitoring volatile hydrocarbon (HC), CO₂, and O₂, concentrations in groundwater, exhaust gases, and soil vapor during in situ remediation using soil vapor extraction (SVE) and air sparging (AS). Results of groundwater samples analyzed in‐house using a headspace technique compared well to split samples analyzed by a certified analytical laboratory (r² = 0.94). SVE exhaust gas HC and CO₂ concentrations measured using a GT201 portable HC/O₂ meter and a RA‐411A meter (GasTech), respectively, were highly correlated with in‐house laboratory GC analyses (r² = 0.91). O₂ concentrations fell in a small range and meter analyses were not well correlated with laboratory analyses. Results of soil gas monitoring were not as well correlated as those for exhaust gases for HC, CO₂, or O₂, perhaps due to environmental conditions such as changes in relative humidity or the wider range of soil gas values. Overall, the meters were good indicators of vapor contamination, they greatly simplified estimates of total HC mass removal, and they allowed estimates of the biological contribution to contaminant removal during the remediation process.     

Integrated membrane systems for gas separation in biotechnology: potential and prospects

Integrated non-porous membrane systems were applied for microbial combustible gas separation processes. Methane/CO₂ mixtures of various concentrations from methane fermentation processes (biogas) were separated using a membrane-separation complex of permabsorber type into individual components of technical grade (more than 95% purity). In experiments with three-component mixtures, using a selective membrane valve with various liquid carriers, all the gases of interest (H₂, CH₄ and CO₂) were obtained at greater than 90% purity in one separation step. The perspectives for the further application of non-porous membrane separating devices for various gaseous mixtures from different microbial processes are discussed.V. Teplyakov and E. Sostina are with the A.V. Topchiev institute of Petrochemical Synthesis, Russian Academy of Sciences, Membrane Research Center, Moscow 117912, Russia. E. Sostina is also, and A. Netrusov is with the Microbiology Department, Moscow University, Moscow 119899, Russia. I. Beckman is with the Chemistry Department, Moscow University, Moscow 119899, Russia.     

The glycoprotein 71 of ecotropic Friend murine leukemia virus. Structure of the oligosaccharides linked to asparagine-12

The glycoprotein from Friend murine leukemia virus was digested with protease from Staphylococcus aureus V8. A glycopeptide comprising the N-terminal glycosylation site (Asn-12) was isolated from the mixture of fragments and analyzed by amino acid sequencing and methylation-capillary gas chromatography-mass spectrometry before and after treatment with sialidase from Vibrio cholerae. Asn-12 was thus found to be substituted by a family of partially sialylated, fucosylated, and intersected glycoprotein N-glycans of the hybrid type.