Integrated Stopped-Flow Device for the Study of Porous Materials Using Hyperpolarized Xe NMR.

A simple, low-cost, and efficient device is proposed for the study of porous materials via NMR using small gas probes. Mainly built through additive manufacturing and being equipped with a radiofrequency solenoid microcoil, it only requires tiny quantities of sample and/or gas and is particularly suited for hyperpolarized xenon. The performances of this device have been accessed on a commercial sample of MCM-41 exhibiting multiporosity.

In vivo detection of carnosine and its derivatives using chemical exchange saturation transfer.

Purpose: To detect carnosine, anserine and homocarnosine in vivo with chemical exchange saturation transfer (CEST) at 17.2 T.

Methods: CEST MR acquisitions were performed using a CEST-linescan sequence developed in-house and optimized for carnosine detection.

Study of and Xenon-Cryptophanes Complexes Decorated with Aromatic Amine Groups: Chemical Platforms for Accessing New Cryptophanes.

We report the synthesis of -symmetric cryptophanes decorated with three aromatic amine groups on the same CTB cap and their interaction with xenon. The relative stereochemistry of these two stereoisomers and was assessed thanks to the determination of the X-ray structure of an intermediate compound. As previously observed with the tris-aza-cryptophanes analogs - and - (.

Xe ultra-fast Z spectroscopy enables micromolar detection of biosensors on a 1 T benchtop spectrometer.

The availability of a benchtop nuclear magnetic resonance (NMR) spectrometer, of low cost and easily transportable, can allow detection of low quantities of biosensors, provided that hyperpolarized species are used. Here we show that the micromolar threshold can easily be reached by employing laser-polarized xenon and cage molecules reversibly hosting it. Indirect detection of caged xenon is made via chemical exchange, using ultra-fast Z spectroscopy based on spatio-temporal encoding.

Effects of Low Doses of Herbicides on Different Endpoints in the Life Cycle of Nontarget Terrestrial Plants.

Herbicide drift may cause adverse effects on natural and seminatural plant communities, and it has been debated whether the current ecological risk assessments are adequate to protect nontarget terrestrial plant species. In the present study, 9 nontarget terrestrial plant species with different lifespans (3 annual/6 perennial) belonging to 6 different plant families were exposed to 4 herbicides with different modes of action at the vegetative (6-8 leaf) and reproductive (bud) stages separately. The plant tests were conducted under controlled conditions in 2 greenhouses, 1 located in Denmark and 1 in Canada.

Use of dissolved hyperpolarized species in NMR: Practical considerations.

Hyperpolarization techniques that can transiently boost nuclear spin polarization are generally carried out at low temperature - as in the case of dynamic nuclear polarization - or at high temperature in the gaseous state - as in the case of optically pumped noble gases. This review aims at describing the various issues and challenges that have been encountered during dissolution of hyperpolarized species, and solutions to these problems that have been or are currently proposed in the literature. During the transport of molecules from the polarizer to the NMR detection region, and when the hyperpolarized species or a precursor of hyperpolarization (e.

Effects of Herbicides on Flowering.

Herbicides have been shown to reduce flower production and to delay flowering, with results varying among herbicides and tested plant species. We investigated the effects of herbicides on flowering in an extensive greenhouse study conducted in Canada and Denmark. The effects of low doses of 5 different herbicides (bromoxynil, ioxynil + bromoxynil, metsulfuron-methyl, clopyralid, and glyphosate), simulating realistic drift scenarios (1 and 5% recommended field rates), on plant flowering were examined using 9 wild plant species exposed at either the seedling (6- to 8-leaf) or flower bud stage.

Synthesis of Cryptophane-223-Type Derivatives with Dual Functionalization.

In this article, we present the synthesis of new cryptophane-type hosts capable of binding xenon in aqueous media and that may be useful for the development of xenon-based magnetic resonance imaging derivatives. The synthetic route proposed was chosen to facilitate both the introduction of water-solubilizing substituents and the functionalization of the host with a single arm showing recognition properties that constitute two crucial steps. This was made possible by preparing new cryptophane-223 derivatives bearing two different chemical functions that can be easily modified at a later stage.

Effects of Sublethal Doses of Herbicides on the Competitive Interactions Between 2 Nontarget Plants, Centaurea cyanus L. and Silene noctiflora L.

Plant competitive interactions influence the effect of herbicides, and the effect of competitive interactions on plant responses may be important to include in the ecological risk assessment of herbicides. In the present study the effect of competitive interactions and sublethal doses of 2 herbicides on plant species was investigated in competition experiments and fitted to empirical competition models. Two nontarget species commonly found in agroecosystems (Centaurea cyanus L.

Bimodal Detection of Proteins by Xe NMR and Fluorescence Spectroscopy.

A full understanding of biological phenomena involves sensitive and noninvasive detection. Herein, we report the optimization of a probe for intracellular proteins that combines the advantages of fluorescence and hyperpolarized Xe NMR spectroscopy detection. The fluorescence detection part is composed of six residues containing a tetracysteine tag (-CCXXCC-) genetically incorporated into the protein of interest and of a small organic molecule, CrAsH.

Ecological risk assessment of cerium for tropical agroecosystems.

Cerium (Ce) is present in high technology materials and in mineral P fertilizers and the use and discharge of such resources may change the natural status of Ce in the soil environment. Brazilian soils in farming areas are significantly exposed to increased levels of unintentionally-added Ce through intensive input of phosphate fertilizers. The aims of this study were to evaluate the ecotoxicological risk to plants growing in tropical soils contaminated with Ce, as well as to create a database to support future legislation regulating the limits of this element in Brazilian and conceivably other tropical soils.

Bimodal fluorescence/Xe NMR probe for molecular imaging and biological inhibition of EGFR in Non-Small Cell Lung Cancer.

Although Non-Small Cell Lung Cancer (NSCLC) is one of the main causes of cancer death, very little improvement has been made in the last decades regarding diagnosis and outcomes. In this study, a bimodal fluorescence/Xe NMR probe containing a xenon host, a fluorescent moiety and a therapeutic antibody has been designed to target the Epidermal Growth Factor Receptors (EGFR) overexpressed in cancer cells. This biosensor shows high selectivity for the EGFR, and a biological activity similar to that of the antibody.

Role of the Methoxy Groups in Cryptophanes for Complexation of Xenon: Conformational Selection Evidence from Xe- H NMR SPINOE Experiments.

We report the laser-polarized Xe and H NMR spectra of a series of cryptophane derivatives that differ only by the number of methoxy groups attached on their benzene rings and the syn or anti arrangement of the linkers (compounds 6 a-s, 9 a-s, 12 a-s). All these compounds bind xenon even though the characteristic signal of the gas encapsulated in the cavity of the cage-molecule cannot always be detected. Interestingly, the exchange dynamics of xenon strongly depends on the degree of substitution and is different from that of the cryptophane derivatives studied previously.

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project.

The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.

Predicting bee community responses to land-use changes: Effects of geographic and taxonomic biases.

Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa.

Uptake and Effects of Six Rare Earth Elements (REEs) on Selected Native and Crop Species Growing in Contaminated Soils.

Rare earth elements (REEs) have become increasingly important metals used in modern technology. Processes including mining, oil refining, discarding of obsolete equipment containing REEs, and the use of REE-containing phosphate fertilizers may increase the likelihood of environmental contamination. However, there is a scarcity of information on the toxicity and accumulation of these metals to terrestrial primary producers in contaminated soils.

Synthesis of Cryptophanes with Two Different Reaction Sites: Chemical Platforms for Xenon Biosensing.

We report the synthesis of new water-soluble cryptophane host molecules that can be used for the preparation of (129)Xe NMR-based biosensors. We show that the cryptophane-223 skeleton can be modified to introduce a unique secondary alcohol to the propylenedioxy linker. This chemical functionality can then be exploited to introduce a functional group that is different from the six chemical groups attached to the aromatic rings.

Herbicide impact on the growth and reproduction of characteristic and rare arable weeds of winter cereal fields.

The decline of arable species characteristic of winter cereal fields has often been attributed to different factors related to agricultural intensification but most importantly to herbicide use. Herbicide phytotoxicity is most frequently assessed using short-term endpoints, primarily aboveground biomass. However, short-term sensitivity is usually not sufficient to detect actual effects because plants may or may not recover over time following sublethal herbicide exposures.

Determining in situ periphyton community responses to nutrient and atrazine gradients via pigment analysis.

Agrochemicals, including fertilizers and herbicides, are significant contributors of non-point source pollution to surface waters and have the potential to negatively affect periphyton. We characterized periphyton communities using pigment markers to assess the effects of nutrient enrichment and the herbicide atrazine with in situ experimental manipulations and by examining changes in community structure along existing agrochemical gradients. In 2008, the addition of nutrients (20 mg/L nitrate and 1.

Cerium chloride heptahydrate (CeCl3 · 7H2O) induces muscle paralysis in the generalist herbivore, Melanoplus sanguinipes (Fabricius) (Orthoptera: Acrididae), fed contaminated plant tissues.

Of increasing economic importance are the rare earth elements (REEs). Pollution from mining and processing activity is expected to rise with industrial demand. Plants are known to accumulate REEs, although levels vary with species and soil content.

Rim-functionalized cryptophane-111 derivatives via heterocapping, and their xenon complexes.

Capping of cyclotriphenolene (3a) by the more available cyclotriguaiacylene (3c) or trisbromocyclotriphenolene (3b) gives the first rim-functionalized cryptophane-111 derivatives. Crystal structures of the xenon complexes reveal high cavity packing coefficients and unprecedentedly short Xe···C contacts.

Understanding a host-guest model system through ¹²⁹Xe NMR spectroscopic experiments and theoretical studies.

Gaining an understanding of the nature of host-guest interactions in supramolecular complexes involving heavy atoms is a difficult task. Described herein is a robust simulation method applied to complexes between xenon and members of a cryptophane family. The calculated chemical shift of xenon caged in a H2O2 probe, as modeled by quantum chemistry with complementary-orbital, topological, and energy-decomposition analyses, is in excellent agreement with that observed in hyperpolarized (129)Xe NMR spectra.

(1)H high resolution magic-angle coil spinning (HR-MACS) μNMR metabolic profiling of whole Saccharomyces cervisiae cells: a demonstrative study.

The low sensitivity and thus need for large sample volume is one of the major drawbacks of Nuclear Magnetic Resonance (NMR) spectroscopy. This is especially problematic for performing rich metabolic profiling of scarce samples such as whole cells or living organisms. This study evaluates a (1)H HR-MAS approach for metabolic profiling of small volumes (250 nl) of whole cells.