Mol H2O Research Articles

New evidence for syntectonic fluid migration across the hinterland‐foreland transition of the Canadian Cordillera

Oxygen isotope data from syntectonic veins, thrust faults, and wall rocks suggest that fluids infiltrated the Western Ranges of the Rocky Mountain foreland from deeper rocks of the Dogtooth Range during Mesozoic contraction. This signifies the first such evidence for kilometer‐scale fluid migration at the hinterland‐foreland transition of the Canadian Cordillera. Fluid infiltration resulted in isotopic depletion in wall rocks and isotopic disequilibrium between veins (fluid) and their host rocks downstream of a lithologic, structural, and isotopic shift between predominantly siliciclastic (Dogtooth Range) and calcareous (Western Ranges) sequences. The shift corresponds with an average δ18O that is 3.0‰ higher in the Western Ranges. In the Dogtooth Range, atypically low carbonate values (15.6‰ ± 0.8‰ (VSMOW)), and the consistency with which vein signatures approach the average bulk rock δ18O of individual outcrops indicate fluid buffering by a siliciclastic reservoir and outcrop‐scale (10–100 m) fluid circulation. In contrast, rocks and veins in the Western Ranges exhibit a gradational increase in δ18O that extends ≥14 km eastward and up section from the isotopic shift and possess values that are below or at the low end of typical carbonate compositions (16.2–20.9‰ (VSMOW)). Furthermore, veins systematically exhibit lower oxygen values than their host rocks; this implies that the fluids that entered the Western Ranges were in modest disequilibrium with the rocks through which they flowed. We use a one‐dimensional reactive transport model to infer that rocks in the Western Ranges experienced a time‐integrated fluid flux of 1.1 × 105 mol H2O cm−2 (≈2.4 × 106 cm3 cm−2 ) and sluggish reaction kinetics during the flow event.

Physiological Ecology of Native and Alien Dry Forest Shrubs in Hawaii

Hawaii's dry forests are among the most endangered of all ecosystems in the archipelago. Invasion of alien plant species into these ecosystems is one of the most significant threats to on-going efforts to preserve and restore Hawaii's remaining dry forests. Comparing the physiological performance of alien and native species can offer causal explanations behind the relative success of alien plant invasions within Hawaiian dry forests and elsewhere. We compared maximum rates of net CO2 assimilation, water-use efficiency (WUE), daily carbon gain, and leaf morphology for three native and two alien shrubby species growing within 1-m2 plots under two natural light (sub-canopy shade relative to open full sunlight) treatments. Maximum rates of net CO2 assimilation were similar between alien and native species (8.15 vs. 7.12 μmol m−2 s−1, respectively), however, native plants exhibited lower stomatal conductance and higher instantaneous WUE than alien plants in all treatments (0.13 mol m−2 s−1 and 72.36 μmol CO2 mol H2O−1 against 0.23 and 58.78, respectively). Alien plants had approximately 65% more aboveground biomass than native plants. This result may reflect differential seed production and seed bank viability between native and alien species. We found an overall strong, positive correlation between species-specific physiological traits and final species aboveground biomass. Based on this type of information we can predict species-specific boundaries across light gradients, and focus restoration efforts accordingly.

The Contribution of Water to the Specific Heat Change at the Glass-to-Rubber Transition of the Ternary System BSA-Water-NaCl

ABSTRACT: We studied the glass-to-rubber transition of a BSA-water-NaCl system using DSC. The Tg was 178–187 K and decreased with increasing NaCl content from 1:9 to 6:4 NaCl:BSA. The specific heat change (ΔCp*, J/((g BSA)K)) at Tg increased as the weight ratio increased from 1:9 to 5:5 NaCl:BSA, as did the change in calculated unfrozen water (UFW). The UFW was also correlated with the amount of NaCl in the glassy region with a correlation coefficient of approx. 6 (mol H2O)/ (mol NaCl), which is comparable to the hydration number of Na+. These results suggest that UFW could contribute to the ΔC at Tg of the BSA-water system.

Diurnal variations of photosynthesis and dew absorption by leaves in two evergreen shrubs growing in Mediterranean field conditions

The effects of summer drought, dew deposition on leaves and autumn rainfall on plant water relations and diurnal variations of photosynthesis were measured in two evergreen shrubs, rosemary (Rosmarinus officinalis) and lavender (Lavandula stoechas), grown in Mediterranean field conditions. Withholding water for 40 d caused a similar decrease in predawn shoot water potential (ψpd) from c.−0.4 to c.−1.3 MPa in both species, but a 50% decrease in the relative leaf water content in L. stoechas compared with 22% in R. officinalis. A similar decrease in CO2 assimilation rates by c. 75% was observed in water‐stressed plants of both species, although L. stoechas showed smaller photosynthesis: stomatal conductance ratio than R. officinalis (35 vs 45 μmol CO2:mol H2O). The relative quantum efficiency of photosystem II photochemistry also decreased by c. 45% at midday in water‐ stressed plants of both species. Nevertheless, neither L. stoechas nor R. officinalis suffered drought‐induced damage to photosystem II, as indicated by the maintenance of the ratio Fv:Fm throughout the experiment, associated with an increase in the carotenoid content per unit of chlorophyll by c. 62% and c. 30%, respectively, in water‐stressed plants. Only L. stoechas absorbed dew by leaves. In this species the occurrence of 6 d of dew over a 15‐d period improved relative leaf water content by c. 72% and shoot water potential by c. 0.5 MPa throughout the day in water‐stressed plants, although the photosynthetic capacity was not recovered until the occurrence of autumn rainfall. The ability of leaves to absorb dew allowed L. stoechas to restore plant water status, which is especially relevant in plants exposed to prolonged drought.

Calorimetric, Viscosimetric, and Light Scattering Studies of the Aggregation of, and the Solubilization of Water by, Triton X-35 inn-Heptane

The behavior of a nonionic surfactant TX-35 in solution inn-heptane in the presence and absence of added water has been examined using the microcalorimetric, viscosimetric, and quasielastic light scattering experimental methods. In this paper, we were interested in the aggregation process of the poly(oxyethylene) glycol alkylphenyl ether inn-heptane and in the solubilization of water in the reverse micelle of the surfactant (micellar solubilization). The analysis of the differential molar enthalpies of dilution of TX-35 in driedn-heptane has shown the occurrence of a gradual exothermic aggregation process on a very wide range of concentration which takes place at particular concentration so-called “operational CMC”. This operational CMC value has been confirmed by viscosities measurements. The differential molar enthalpies of hydration of TX-35 were also measured and found to be exothermic. The maximal hydration ratio (w0) was found to be equal to 3.2 mol H2O per mole of TX-35 before the point of phase separation. The measurements of the variation of the amount of water contained in TX-35 solutions at different concentrations inn-heptane also show the occurence of a gradual aggregation process and confirm the value of the maximal hydration ratio already determined by microcalorimetry. In the absence of added water, from the quasielastic light scattering experiments, a mean diameter of the aggregates close to 45 Å has been determine, while in the presence of water, a mean diameter of 61 Å was detected and remained unchanged with increasing the hydration ratio indicating that the size of the aggregate is more influenced by the presence of water than by the amount. In the presence of water, it is relevant to discuss aggregates of lamellar or filament shape.

Physiological and morphological variation in Metrosideros polymorpha, a dominant Hawaiian tree species, along an altitudinal gradient: the role of phenotypic plasticity.

Metrosideros polymorpha, a dominant tree species in Hawaiian ecosystems, occupies a wide range of habitats. Complementary field and common-garden studies of M. polymorpha populations were conducted across an altitudinal gradient at two different substrate ages to ascertain if the large phenotypic variation of this species is determined by genetic differences or by phenotypic modifications resulting from environmental conditions. Several characteristics, including ecophysiological behavior and anatomical features, were largely induced by the environment. However, other characteristics, particularly leaf morphology, appeared to be mainly determined by genetic background. Common garden plants exhibited higher average rates of net assimilation (5.8 μmol CO2 m-2 s-1) and higher average stomatal conductance (0.18 mol H2O m-2 s-1) than their field counterparts (3.0 μmol CO2 m-2 s-1, and 0.13 mol H2O m-2 s-1 respectively). Foliar δ13C of most common-garden plants was similar among sites of origin with an average value of -26.9‰. In contrast, mean values of foliar δ13C in field plants increased substantially from -29.5‰ at low elevation to -24.8‰ at high elevation. Leaf mass per unit area increased significantly as a function of elevation in both field and common garden plants; however, the range of values was much narrower in common garden plants (211-308 g m-2 for common garden versus 107-407 g m-2 for field plants). Nitrogen content measured on a leaf area basis in common garden plants ranged from 1.4 g m-2 to 2.4 g m-2 and from 0.8 g m-2 to 2.5 g m-2 in field plants. Photosynthetic nitrogen use efficiency (PNUE) decreased 50% with increasing elevation in field plants and only 20% in plants from young substrates in the common garden. This was a result of higher rates of net CO2 assimilation in the common garden plants. Leaf tissue and cell layer thickness, and degree of leaf pubescence increased significantly with elevation in field plants, whereas in common garden plants, variation with elevation of origin was much narrower, or was entirely absent. Morphological characteristics such as leaf size, petiole length, and internode length decreased with increasing elevation in the field and were retained when grown in the common garden, suggesting a potential genetic basis for these traits. The combination of environmentally induced variability in physiological and anatomical characteristics and genetically determined variation in morphological traits allows Hawaiian M. polymorpha to attain and dominate an extremely wide ecological distribution not observed in other tree species.

Solubility of Ba-Acetate in Mixed Alcoholic Solutions and its Bearing on the Synthesis of Multi-Component Gels

The solubility of Ba-acetate in mixtures of alcohol (ethanol, n-propanol and iso-propanol) and H2O or acetic acid (CH3COOH) have been determined. In the ROH-H2O-Ba(OOCCH3)2 system a small region of miscibility was found. To a saturated solution of 4.8 mol% Ba(OOCCH3)2 in H2O for each additional mol H2O, 0.9 mol iso-propanol or 1.1 mol ethanol can be added without precipitation of Ba(OOCCH3)2. The solubility in alcohol/acetic acid mixtures is higher. For each mol CH3COOH, 2.2 mol iso-propanol, 3.2 mol n-propanol or 4.1 mol ethanol can be added without precipitation of Ba(OOCCH3)2. The results were applied to develop a procedure for the synthesis of gels in the system BaO-Al2O3-SiO2 from metal alkoxides and Ba-acetate. Acetic acid reacts with Al-sec-butoxide to give Al(O-sec-C4H9)3-x(CH3COO)x. Therefore, the solution of Ba-acetate was controlled only over the H2O/alcohol ratio.

Dehydration of -cyclodextrin: facts and opinions

The thermodynamics of dehydration of β-cyclodextrins, β-CD·nH2O, is discussed. Despite the presence of different types of water, the enthalpies of dehydration per mole of β-CD, (with n > 2) depend linearly upon n, yielding a slope of 23.5 kJ (mol H2O)−1. This value is substantially smaller than the isosteric heat of dehydration, as determined through DSC data, and estimated from dehydration isotherms at two different temperatures. This implies that the β-CD substrate contributes to dehydration by relaxing to an energetically favoured state; this relaxation ends with an endothermic transformation to a different crystalline structure, which is primarily driven by the loss of water, and occurs near n = 2. The enthalpies of dissolution, measured in a recent paper by Bilal et al., also have a linear dependence upon n. However, this linear law apparently covers also the range of the structural transformation and its slope of 10.50 kJ (mol H2O)−1 is not consistent with our data. The possible reasons for the discrepancy are discussed.

Effect of soil drying on growth, biomass allocation and leaf gas exchange of two annual grass species

Influence of short-term water stress on plant growth and leaf gas exchange was studied simultaneously in a growth chamber experiment using two annual grass species differing in photosynthetic pathway type, plant architecture and phenology:Triticum aestivum L. cv. Katya-A-1 (C3, a drought resistant wheat cultivar of erect growth) andTragus racemosus (L.) All. (C4, a prostrate weed of warm semiarid areas). At the leaf level, gas exchange rates declined with decreasing soil water potential for both species in such a way that instantaneous photosynthetic water use efficiency (PWUE, mmol CO2 assimilated per mol H2O transpired) increased. At adequate water supply, the C4 grass showed much lower stomatal conductance and higher PWUE than the C3 species, but this difference disappeared at severe water stress when leaf gas exchange rates were similarly reduced for both species. However, by using soil water more sparingly, the C4 species was able to assimilate under non-stressful conditions for a longer time than the C3 wheat did. At the whole-plant level, decreasing water availability substantially reduced the relative growth rate (RGR) ofT. aestivum, while biomass partitioning changed in favour of root growth, so that the plant could exploit the limiting water resource more efficiently. The change in partitioning preceded the overall reduction of RGR and it was associated with increased biomass allocation to roots and less to leaves, as well as with a decrease in specific leaf area. Water saving byT. racemosus sufficiently postponed water stress effects on plant growth occurring only as a moderate reduction in leaf area enlargement. For unstressed vegetative plants, relative growth rate of the C4T. racemosus was only slightly higher than that of the C3T. aestivum, though it was achieved at a much lower water cost. The lack of difference in RGR was probably due to growth conditions being relatively suboptimal for the C4 plant and also to a relatively large investment in stem tissues by the C4T. racemosus. Only 10% of the plant biomass was allocated to roots in the C4 species while this was more than 30% for the C3 wheat cultivar. These results emphasize the importance of water saving and high WUE of C4 plants in maintaining growth under moderate water stress in comparison with C3 species.

Thermoanalytical investigation of the synthesis of pyrazine and bipyrazine via the pyrolysis of the bis(pyrazinecarboxylate)copper(II) complex

The pyrolysis of hydrated bis(pyrazinecarboxylate)copper(II) under an argon atmosphere proceeds via the loss of the water molecules at 84–95°C, ΔH=40.4 kJ (mol H2O)−1 followed by the thermal decomposition of the complex at 284–325°C, ΔH=97.0 kJ·mol−1, yielding 0.72 mole of pyrazine, 0.28 mole of bipyrazine, and 2 mole of CO2 per mole of complex.

Ecophysiological comportment of the tropical CAM-tree Clusia in the field: II. Modes of photosynthesis in trees and seedlings.

Measurements were performed on leaves of Clusia rosea Jacq. trees in the moist central mountains (330 to 365 m above sea level) and at the dry south coast of St John Island (US Virgin Islands, Lesser Antilles). Seedlings of C. rosea were also studied in the central hills. During the study period (March 1989) all trees showed crassulacean acid metabolism (CAM), in which net CO2 uptake extended for a remarkably long time in the morning (phase II of CAM: until about 11 to 12 h) and contributed about 1/3 of total net CO2 -uptake. During the night (phase I of CAM) malic acid and citric acid were accumulated concurrently at a molar ratio of malic: citric acid of about 1.6. Internal recycling of respiratory CO2 was 20% of total CO2 fixed during the night. Water-use-efficiency (mol CO2 taken up: mol H2 O transpired) was 0.014 to 0.022. The pH of leaf-cell sap at the end of the dark period was 2.85. This would still allow an H+ -ATPase at the tonoplast to transport 2H+ into the vacuole per ATP hydrolysed when operating near thermodynamic equilibrium. Free sugars, glucose and fructose, and starch were used as precursors for the CO2 -acceptor phosphoenolpyruvate during the dark period; contributions of the two hexoses were about equal and together four-times that of starch. Xylem tensions showed increases of up to 8 bar during day-time. Leaf-sap osmotic pressures did not change significantly; the trend was a small decline during day-time. Among the seedlings, three different modes of photosynthesis were encountered, namely C3 -photosynthesis in terrestrial and in epiphytic seedlings, continuous stomatal opening and CO2 -uptake day and night in epiphytic seedlings, and CAM in seedlings growing in the tanks of Aechmea lingulata (L.) Baker.

Photosynthetic characteristics and water use efficiency of three coastal dune plants

AbstractTo clarify the ecophysiological characteristics of plants growing on a coastal dune, net photosynthetic rate (Pn) and leaf conductance (g1) of three perennial species in Japanese coastal regions, Ischaemum anthephoroides (C4), Carex kobomugi (C3) and Calystegia soldanella (C3), were compared under controlled environmental conditions and field conditions at the kado‐ori coast at Ohno Village, Ibaraki. I. anthephoroides achieved photosynthetic CO2 saturation at ca. 100 μll−1 intercellular CO2 concentration (C1), and its Pn was not light‐saturated at a high photosynthetically active photon flux density (PPFD) of 1000 μmol m−2s−1. This C4 species showed a high optimal leaf temperature for Pn (35°C) and a low g1 (0.1 mol H2O m−2s−1), permitting maintenance of the highest water use efficiency (WUE, the ratio of Pn to transpiration rate (Tr)) in the field among the three species. At light saturation, C. soldanella had the lowest Pn and g1 and a similar carboxylation efficiency related to C1 (Pn/C1 ratio) as Carex kobomugi. Calystegia soldanella also had a high optimal temperature for Pn (30°C), and achieved higher WUE than Carex kobomugi, as a result of efficient stomatal regulation. In contrast, at the optimum temperature C. kobomugi had a high Pn comparable to I. anthephoroides due to a high g1 of 0.3 mol H2O m−2s−1, but with high temperature treatments Pn and g1 were significantly decreased. C. kobomugi always had the lowest WUE among the three species in the field. It is therefore clear that I. anthephoroides is a heat‐resistant species, Calystegia soldanella is a heat‐enduring species and Carex kobomugi is a heat‐evading species due to its eraly phenology.

Metabolic mechanism of ethanol-isovaleric acid fermentation by a Clostridium saccharoperbutylacetonicum UV-mutant.

Mutant AS2-1, derived from Clostridium saccharoperbutylacetonicum N1-4 ATCC 13564, did not produce acetone, butanol, and acetic acid, but had enhanced ethanol production and newly produced isovaleric acid at the molar ratio of 1:1. The mutant was defective in thiolase (acetyl-CoA acetyltransferase) activity, while the parent N1-4 showed high thiolase activity (103.5 units/g protein). Addition of allyl alcohol into the mutant culture significantly decreased the production of both ethanol and isovaleric acid. AS2-1 mutant, therefore, had NAD+ — and NAD(P)+-dependent aldehyde dehydrogenase on the pathway to ethanol and isovaleric acid, respectively. It was suggested that an excess of electrons accumulated as the result of the deficiency in thiolase was consumed for the reductive formation of isovalerate from pyruvate. The equation of the novel ethanol–isovaleric acid fermentation was concluded as 1.5 mol glucose = 1 mol ethanol + 1 mol isovaleric acid + 2 mol CO2 + 2 mol H2O +1 mol H2.

Geochemical investigation of NaCl-KCl-MgCl2-CaCl2-FeCl2 solutions in Zechstein 2 salt, Suldrup Dome, Denmark. Microthermometry on fluid inclusions in halite

Large, irregular fluid inclusions with daughter bischofite, MgCl2 • 6H2O, in recrystallized halite from former brine pockets in grey Zechstein 2 rock salt from the Suldrup dome, Denmark, were studied by means of microthermometry. The test material consists of ca 3 kg cleavage pieces and a piece of core of extremely clean, colourles, limpid halite. Anhydrite and pyrrhotite are present as solid inclusions in trace amounts only. The irregular inclusions studied all contain daughter bischofite at room temperature. Optical, crystallographic, and chemical (melting) methods proved the daughter mineral to be bischofite. The mean dissolving temperature Tmhex = 56.5 ± 0.9°C, 95% confidence limit, of 117 measurements yields, from pertinent phase diagrams, a quantitative composition of the equilibrium solution: 114 mol MgCl2 + 1.2 mol K2Cl2 per 1000 mol H2O, saturated with NaCl (ca. 2 mol Na2Cl2 per 100 mol H2O). Exposed to the atmosphere, the equilibrium solution becomes orange yellowish after some days, thus proving the presence of FeCl2 (5-10 mol/1000 mol H2O). In one inclusion carnallite (KMgCl3 • 6H2O) was observed, the dissolving temperature Tmcar = 81.9°C of which is a minimum trapping temperature. The minimum trapping pressure is calculated at slightly higher than 65 MPa. The viscosity at 80°C is estimated at ca. 4 centipoise. Measurements of the homogenization temperature in fluid phase are meaningless due to the presence of compressed gas, possibly H2S. The following model is proposed concerning the formation of the studied halite: During the end of the diapiric penetration phase in Lower Cretaceous, a metamorphic lye mixed with concentrated sea water in NaCl facies in brine pockets within the grey Zechstein 2 rock salt, causing salting out of the studied halite. The metamorphic lye derived from a metamorphosed carnallitic potash zone. The carnallitic solution was mixed with an infiltrating rinneitic (3KC1 · NaCl · FeCl2) solution. The mixture was squeezed out from the potash zone during the diapiric penetration phase, leaving a trail of disseminated grains and fracture fillings of carnallite all the way up to the former brine pockets. The minerals bischofite and pyrrhotite, Fe1-xS, are reported from Denmark for the first time.

Water Use Efficiency and Dry Matter Distribution in Nitrogen‐ and Water‐Stressed Winter Wheat

AbstractWater use efficiency (WUE) and the distribution of dry matter to the roots in wheat (Triticum aestivum L.) are potential selection criteria for improving yield under water stress. The objectives of this research were (i) to compare methods of measuring WUE, and (ii) to determine the distribution of dry matter between shoots and roots in water‐ and N‐stressed wheat. Winter wheat was grown in a potting mixture for 6 wk in growth chambers with varying levels of N and water. Nitrogen applied to the mixture varied from 10 to 100 mg N per plant. Water supply was maintained at 15 to 35% of the mixture water holding capacity (stressed) to above 50% of capacity (well watered). Cumulative transpiration, steady‐state CO2 and H2O exchange rates, and dry matter were determined. The ratio of dry matter production (mmol C) to transpiration (mol H2O) averaged 1.39 and 1.94 mmol C mol−1 H2O for the 10 and 100 mg N treatments, respectively. The ratio of the steady state CO2 exchange rate to the H2O exchange rate was 1.97 and 4.24 mmol C mol−1 H20 for the 10 and 100 mg N treatments, respectively. The gas exchange WUE values tended to be higher than the gravimetric WUE values, but the two were correlated (r = 0.76**). Results supported the hypothesis that gas exchange WUE values could provide an accurate prediction of WUE values obtained from gravimetric analysis. Shootroot ratio was consistently reduced by N stress, but not by water stress. The results supported previous observations that optimal leaf N concentration promoted higher WUE. Mild water stress did not consistently affect WUE, but a more severe water stress consistently decreased WUE, especially under suboptimal N supply.

Ecophysiology of xerophytic and halophytic vegetation of a coastal alluvial plain in northern Venezuela

summaryA comparison of the performance of two epiphytes with crassulacean acid metabolism (CAM) was made during the rainy season and dry season at the Ciénega el Ostional, Chichiriviche in northern Venezuela. The epiphytic bromeliad, Tillandsia flexuosa has water‐retaining tanks and leaf trichomes, and propagates mainly vegetatively to produce large populations in the shrubby island vegetation. The epiphytic orchid, Schomburgkia humboldtiana formed smaller populations, and had large succulent leaves with uniform chlorenchyma and no distinct water‐storage parenchyma, unlike T. flexuosa. Both epiphytes were myrmecophilous.Leaf succulence (kg m−2) declined by ∼ 10% in the dry season for both plants. Both epiphytes showed reduced CO2 uptake during Phase I (dark period) and (dawn‐dusk) titratable acidity (ΔH+) in the dry season. Water‐use efficiency (WUE) was higher for S. humboldtiana (16.0 × 10−3 mol CO2 per mol H2O compared with 5.0 × 10 −3 for T. flexuosa) although WUE remained constant during rainy and dry season for each species.Sixty to seventy per cent of the dawn dusk titratable acidity was derived internally from respiratory CO2 (recycling) for both species, and in absolute terms, recycling decreased in the dry season, in contrast to the expected progression under drought stress. Recycling is an important facet of carbon balance for both species in both rainy and dry seasons.Leaf Na+ concentration was higher than values quoted for terrestrial salt stressed CAM plants. Fructose and glucose declined in leaf bases of T. flexuosa during the dark period, but not in the more distal regions of the leaf. S. humboldtiana showed a decrease in sucrose at night, and mannitol was also an important constituent of the leaves.Xylem sap tension maxima increased from 0.38 ± 0.09 MPa (rainy season) to only 0.55 ± 0.06 MPa (dry season) for T. flexuosa, these values being much lower than those found for terrestrial shrubs and herbs at the same site, the two epiphytes use CAM in conjunction with differing morphological adaptations to maintain growth throughout the year at the Ciénega el Ostional, but it would seem that T. flexuosa has better physiological characteristics for maintenance of carbon acquisition during the dry season.

Purification and properties of (S)-tetrahydroprotoberberine oxidase from suspension-cultured cells of Berberis wilsoniae.

A novel oxidase, catalyzing in the presence of oxygen the removal of four hydrogen atoms from a number of tetrahydroprotoberberines with simultaneous production of 1 mol H2O2 and H2O each, has been discovered and purified to homogeneity from Berberis wilsoniae cell cultures. This enzyme, (S)-tetrahydroprotoberberine oxidase, exhibited strict specificity for the (S)-enantiomer of tetrahydroprotoberberines and 1-benzylisoquinoline alkaloids, a pH optimum at 8.9, a molecular mass of 105 kDa and consisted of two subunits each of 53 kDa and covalently bound flavin. The Km values for (S)-scoulerine and (S)-norreticuline were 25 microM and 150 microM respectively. Concentration of the end-products, either protoberberines or H2O2, greater than 0.5 mM caused severe enzyme inhibition. This catalyst was responsible for the conversion of (S)-tetrahydrocolumbamine to the key intermediate, columbamine, in the metabolic pathway leading to berberine, jatrorrhizine and palmatine.

New method for determination of the equilibrium state in systems involving reactions of the type A(s)=B(s)+C(g)

A static method is described for measurement of the equilibrium values of temperature, pressure and composition of the solid phase, and determination of the number of degrees of freedom in heterogeneous systems containing a gaseous phase, including water vapour. With this method, it has been found that in the system formed in the thermal dehydration of CaC2O4·H2O a solid solution of monohydrate and anhydride coexists in equilibrium with water vapour. The composition of the solid solution changes with the temperature and the pressure of water vapour. The dehydration enthalpy of the solid solution referred to 1 mol H2O does not depend on its composition. It was found to be ΔHdeh=(69+-3) kJ·mol−1.

Hydration of NaDNA by neutron quasi-elastic scattering

Preliminary results of neutron quasi-elastic scattering experiments are reported for hydrated paracrystals of sodium deoxyribonucleic acid (NaDNA). The samples were investigated at two water contents: 3.5 +/- 1.0 and 9.5 +/- 1.5 mol H2O per mole nucleotide. The results of the scattering experiments were almost independent of whether the NaDNA fibers were oriented parallel or perpendicular to the momentum transfer. The data indicate that at the lower hydration the water molecules do not diffuse appreciably on the time scale of the neutron measurements (approximately 3 X 10(-10) s). At the higher hydration the water molecules diffuse isotropically in a sphere of 9 A in diameter with a diffusion coefficient of (5 +/- 2) X 10(-6) cm2 s-1.

Manometric and mass spectrometric analysis of fluids in geological meterials.

A procedure of volatile analysis in rocks which permits quantitative estimation of all the volatile species of any geological interest is presented and illustrated by several examples. Gas extraction is performed either by vacuum crushing or heating. A separation line using cold traps, oxidation (CO to CO2) and reduction (H2O to H2) furnaces permits to separate several fractions. At the end of each separation phase the pressure in the line is measured with a capacitance manometer before analysis of the gas mixture with a mass spectrometer. Calibration is done periodically using standard gases stored in gauged bottles. The detection limits are 0.5 to 1. × 10-7 mol H2O, 0.3 × 10-7 mol CO2 and about 0.2 × 10-7 mol for H2, N2, CO, CH4 and Ar. Further species like organic compounds, SO2 and H2S are detected but not determined. In the case of H2O and CO2 the reproducibility is better than 4%. The conjunction of vacuum crushing, stepwise heating and size fraction analysis permits to separate components like: dissolved, adsorbed and vesicle trapped. In particular, effects of adsorption have been evaluated: it is a serious problem for, species like CO2 and H2O with finely crushed material. H2 and CO detected after thermal extraction when organic compounds are present in the sample reflect organic decomposition rather than any thermodynamic equilibrium attained upon rock formation.