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The key requirement for a portable store of natural gas is to maximize the amount of gas within the smallest possible space. The packing of methane (CH4) in a given storage medium at the highest possible density is, therefore, a highly desirable but challenging target. We report a microporous hydroxyl-decorated material, MFM-300(In) (MFM = Manchester Framework Material, replacing the NOTT designation), which displays a high volumetric uptake of 202 v/v at 298 K and 35 bar for CH4 and 488 v/v at 77 K and 20 bar for H2. Direct observation and quantification of the location, binding, and rotational modes of adsorbed CH4 and H2 molecules within this host have been achieved, using neutron diffraction and inelastic neutron scattering experiments, coupled with density functional theory (DFT) modeling. These complementary techniques reveal a very efficient packing of H2 and CH4 molecules within MFM-300(In), reminiscent of the condensed gas in pure component crystalline solids. We also report here, for the first time, the experimental observation of a direct binding interaction between adsorbed CH4 molecules and the hydroxyl groups within the pore of a material. This is different from the arrangement found in CH4/water clathrates, the CH4 store of nature.

A system for employing open-ended root chambers to measure in situ acetylene reduction rates under field conditions is described. Gas mixtures containing about 2 mbar acetylene were continuously flowed through the chambers providing a continuous record of acetylene reduction. These chambers have been used to measure acetylene reduction rates of soybeans during three growing seasons. The system has proved to be reliable with a high degree of precision. The large amount of plant-to-plant variability observed in N 2 fixation research has been confirmed by the data collected with this system. However, such variability in physiological studies can be reduced by using a non-destructive system to compare the response of an individual plant with its rates before treatment.

The crystal structure of (R)‐histidinium (2R,3R)‐tartrate, C6H10N3O2+·C4H5O6−, has been determined as part of an ongoing study into the fundamental effects of chirality on salt formation and hydration. Repeating layers of (R)‐histidinium and (2R,3R)‐tartrate interlink to form a three‐dimensional network through simple translational symmetry of the unit cell.

Anion-cation balances based on the ions Na+, K+, Ca2+, Mg2+, SO42-, Cl-, HCO3- and CO32- (in milli-equivalents per litre) for over 1500 analyses of natural waters have been examined. While most waters showed an ion balance which was within � 0.10 of the total of these ions, there was a lack of ion balance associated with and expected of acidic waters and waters with low ionic concentrations. In addition, waters which were alkaline and which contained soluble silica generally showed an excess of anions. The effects of added silica in various forms on the alkalinity titration of the carbonate-bicarbonate system have been investigated. The presence of silicate anions leads to an apparent excess of cations in the ion balance, while the presence of silicic acid or silica gel leads to an apparent excess of anions. These apparent ionic imbalances result from reactions between soluble and insoluble silica with carbonate/bicarbonate ions, which cannot be detected either by the alkalinity titration or by the determination of soluble silica.

Key indicatorsSingle-crystal X-ray study T = 295 K Mean '(C±C) = 0.002 A Ê R factor = 0.043 wR factor = 0.118 Data-to-parameter ratio = 15.3For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.# 2004 International Union of Crystallography Printed in Great Britain ± all rights reservedThe crystal structure of dl-histidine dl-tartrate, C 6 H 10 N 3 O 2 + ÁC 4 H 5 O 6 À , has been determined as part of an ongoing study of the fundamental effects of chirality on salt formation and hydrates. Discrete single-enantiomer chains of histidine are linked in two dimensions by hydrogen bonds to a racemic pair of tartrate molecules. CommentThis study was undertaken to identify the effects of chirality on the formation of salts, speci®cally the way chirality may affect hydration, as a result of interactions between a chiral drug and a chiral counter-ion. dl-Histidine and dl-tartrate samples were purchased from Fluka and used in the crystallization. The asymmetric unit of the title compound, (I), contains one molecule of histidine as a monocation (protonated at the amine and imidazole N atoms and deprotonated at the carboxylic acid) and the tartrate as a monoanion (Fig. 1).The histidines form chains of single enantiomers (Fig. 2) linked along the b axis by hydrogen bonds from the NH group of the imidazole ring to a carboxyl O atom of the next histidine, similar to those described by Suresh & Vijayan (1987). The tartrate anions form dimers containing one d-and one l-tartrate ion in each pair (Fig. 2). The dimers are formed by means of a carboxylic acid O atom bonding to a neighbouring tartrate utilizing a side OH group [2.817 (2) A Ê ]. Each histidine molecule in a chain is linked to the next chain below (viewed down the a axis in Fig. 2) by a single hydrogen bond from a carboxyl O atom to an NH group of the ammonium group [2.749 (2) A Ê ]. The tartrates link the chains of histidine in two dimensions to create a three-dimensional hydrogen-bond network. ExperimentalA 5 ml saturated aqueous solution of dl-histidine was mixed with a 5 ml saturated aqueous solution of dl-tartaric acid and the vial was covered with a pierced ®lm. This was placed in a larger glass vial containing 25 ml of methanol, sealed, and allowed to stand for three weeks at room temperature.

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