Peroxide-Modified Titanium Dioxide: a Chemical Analog of Putative Martian Soil Oxidants

Hydrogen peroxide chemisorbed on titanium dioxide (peroxide-modified titanium dioxide) is investigated as a chemical analog to the putative soil oxidants responsible for the chemical reactivity seen in the Viking biology experiments. When peroxide-modified titanium dioxide (anatase) was exposed to a solution similar to the Viking labeled release (LR) experiment organic medium, CO2 gas was released into the sample cell headspace. Storage of these samples at 10 °C for 48 hr prior to exposure to organics resulted in a positive response while storage for 7 days did not. In the Viking LR experiment, storage of the Martian surface samples for 2 sols (49 hr) resulted in a positive response while storage for 141 sols essentially eliminated the initial rapid release of CO2. Heating the peroxide-modified titanium dioxide to 50 °C prior to exposure to organics resulted in a negative response. This is similar to, but not identical to, the Viking samples where heating to approximately 46 °C diminished the response by 54–80% and heating to 51.5 apparently eliminated the response. When exposed to water vapor, the peroxide-modified titanium dioxide samples release O2 in a manner similar to the release seen in the Viking gas exchange experiment (GEx). Reactivity is retained upon heating at 50 °C for three hours, distinguishing this active agent from the one responsible for the release of CO2 from aqueous organics. The release of CO2 by the peroxide-modified titanium dioxide is attributed to the decomposition of organics by outer-sphere peroxide complexes associated with surface hydroxyl groups, while the release of O2 upon humidification is attributed to more stable inner-sphere peroxide complexes associated with Ti4+ cations. Heating the peroxide-modified titanium dioxide to 145 °C inhibited the release of O2, while in the Viking experiments heating to this temperature diminished but did not eliminated the response. Although the thermal stability of the titanium-peroxide complexes in this work is lower than the stability seen in the Viking experiments, it is expected that similar types of complexes will form in titanium containing minerals other than anatase and the stability of these complexes will vary with surface hydroxylation and mineralogy.     

Smectite clays in Mars soil: Evidence for their presence and role in Viking biology experimental results

Summary Various chemical, physical and geological observations indicate that smectite clays are probably the major components of the Martian soil. Satisfactory ground-based chemical simulation of the Viking biology experimental results was obtained with the smectite clays nontronite and montmorillonite when they contained iron and hydrogen as adsorbed ions. Radioactive gas was released from the medium solution used in the Viking Labeled Release (LR) experiment when interacted with the clays, at rates and quantities similar to those measured by Viking on Mars. Heating of the active clay (mixed with soluble salts) to 160°C in CO₂ atmosphere reduced the decomposition activity considerably, again, as was observed on Mars. The decomposition reaction in LR experiment is postulated to be iron-catalyzed formate decomposition on the clay surface. The main features of the Viking Pyrolytic Release (PR) experiment were also simulated recently (Hubbard, 1979) which the iron clays, including a relatively low 1st peak and significant 2nd peak.The accumulated observations on various Martian soil properties and the results of simulation experiments, thus indicate that smectite clays are major and active components of the Martian soil. It now appears that many of the results of the Viking biology experiments can be explained on the basis of their surface activity in catalysis and adsorption.     

Mars exopaleontology

The search for ancient life on Mars is detailed. Results of the Viking missions are examined and goals for the Global Surveyor Program are outlined.     

Full Cycle

Making Things: The Handbook of Creative Discovery: Little, Brown and Co. List Price $6.95. Reviewed by Ann Wiseman

Selling your Art Work: A. S. Barnes &; Co., Inc. List Price $8.95. Reviewed by Milton K. Berlye

American Pieced Quilts: The Viking Press, Inc. List Price $5.95. Reviewed by Jonathan Holstein

The Art Crowd: David McKay Co., Inc. List Price $8.95. Reviewed by Sophy Burnham

Off the Loom: Creating with Fibre: The Viking Press, Inc. List Price $8.95. Reviewed by Shirley Marein

Grammar of Ornament: Van Nostrand Reinhold Company List Price $35.00. Reviewed by Owen Jones

Few Comforts or Surprises: The Arkansas Delta: The MIT Press List Price $9.95. Reviewed by Eugene Richards

Clay and Glazes For the Potter (revised edition): Chilton Book Co. List Price $1 2.50. Reviewed by Daniel Rhodes

The Inspector: The Viking Press, Inc. List Price $10.00. Reviewed by Saul Steinberg     

General constraints on the Viking biology investigation

The Viking biological investigation will be conducted in the face of a number of constraints. Problems are created because of the inherent engineering of the instrument, communication constraints and other factors.     

亚麻原生质体培养及植株再生

Shoot protoplasts of four fiber flax (Linum usitatissimum) varieties (7309, 948, Belinka and Viking) were isolated and cultured. The optimal condition for higher protoplast yield 1.8 x 10(6)/gFW and activity 85.5% (c.v. 948) were from 10 day old seedings. Culture in V-KM Agroase-island medium led to first divisions after 3 days (c. v. 948), and after twenty days with an efficiency of 36% of divided cells and 5.2% in plating efficiency. Plant regeneration was obtained in 7309 and Belinka on agar media B5-2, MS3 containing 0.6 mg/L 6-BA and 0.1 mg/L NAA. Roots and leaves regeneration were observed in Viking and 948 respectively.     

Across the North Sea and beyond

Increasing numbers of ancient genomes from the Viking period retrieved across the North Sea regions are revealing a complex layer of genetic ancestries and a past cosmopolitanism that was triggered by different mobility patterns.     

Valkyries: Was gender equality high in the Scandinavian periphery since Viking times? Evidence from enamel hypoplasia and height ratios

Scandinavian countries currently have very high values of female autonomy. Was this already the case in Viking Times? In this study, we trace the roots of gender equality in the Scandinavian periphery over the past two millennia. We evaluate and recommend a new measure of early gender equality: relative enamel hypoplasia values of males and females. This new indicator allows us to trace relative health and nutritional equality, using archaeological evidence. We find that Scandinavian women in the rural periphery already had relatively good health and nutritional values during the Viking era and the medieval period thereafter. The corresponding value is 0.8 equality advantage for Scandinavian women, whereas in the rest of Europe most values fall in a band around 1.2 ratio units. This suggests that the currently high gender equality had a precedence during the Middle Ages.     

Entertainment!

Abstract

Robertson Davies, The Lyre of Orpheus. New York: Viking Penguin, 1988. 472 pages. $19.95 hardback.     

Did Viking Discover Life on Mars?

A major argument in the claim that life had been discovered during the Viking mission to Mars is that the results obtained in the Labeled Release (LR) experiment are analogous to those observed with terrestrial microorganisms. This assertion is critically examined and found to be implausible.     

The viking biology experiments: Epilogue and prologue

In looking ahead to possibe new attempts to search for extant life on Mars, the history of the Viking biological investigations is reviewed here. Scientific considerations that led to the selection of specific experimental approaches for life detection are discussed, as well as the overall results obtained from that mission. Despite extensive preflight testing of the concepts that were to be used, unanticipated artefacts arose in the actual mission. These almost certainly reflect the fact that, at that time, there were many gaps in our understanding of the physical and chemical characteristics of the Martian environment. After Viking, many of these issues still remain unresolved, and future attempts to search for extant biology should be restrained until adequate new information about potential habitable microenvironments is obtained.Presented at the International Symposium on the Biological Exploration of Mars, October 26–27, 1990, Tallahasee, Fla., U.S.A.     

Population Changes and Persistence of Rhizobium phaseoli in Soil and Rhizospheres

The impact of legume cultivation on the establishment and persistence of an inoculant strain of Rhizobium phaseoli and its ability to compete with a resident population of R. phaseoli for nodule occupancy was examined utilizing strain-specific fluorescent antibodies. The soil (Hubbard loamy sand) was inoculated homogeneously with 5 × 10⁵ cells per g of soil and confined in plastic cylinders kept in field plots. Inoculated and uninoculated cylinders were either left fallow or planted to two seeds of legumes. Two hosts, navy bean (Phaseolus vulgaris L.) cv. Seafarer and snap bean cv. Picker, as well as a nonhost, soybean (Glycine max (L.) Merr.) cv. Wilkin, were used. Inoculant Viking 1 was highly stimulated in all three rhizospheres sampled at 6 (flowering), 10 (podfill), and 17 (decay) weeks and in the following spring, whereas counts in fallow soil decreased rapidly. Although the overwintering population remained highest in the vicinity of decaying host roots, Viking 1 persisted, even in fallow soil, to produce abundant nodulation of host plants the following spring. Viking 1 was an excellent competitor for nodulation sites on the roots of the hosts; it thoroughly outcompeted the resident population of R. phaseoli, occupying virtually 100% of the nodules under inoculated conditions in all experiments.     

Report of the Seventh International Art Congress

Creative Collage with Shells and Dried Flowers Taplinger Publishing Co., Inc., New York List Price $5.50. Reviewed by Elizabeth Russell.

An Introduction to Lettering The Viking Press, Inc. List Price $5.95. Reviewed by Alan and Rita Greer.

Designing in Stitching and Applique Davis Publications, Inc. List Price $10.95. Reviewed by Nancy Belfer.

Design is Where you Find it Iowa State University Press List Price $6.95. Reviewed by Orville Chatt.

All Kinds of Papercrafts Viking Press List Price $8.95. Reviewed by john Portchmouth.

Crafting with Nature's Materials Sterling Publishing Co., Inc., New York List Price $2.95. Reviewed by Chester Jay Alkema.

Cathedral Architecture Russak &; Company, Inc. List Price $1 2.50. Reviewed by Hugh Braun Crane.

Victorian Ornamental Design St. Martin's Press, New York List Price $10.00 cloth $4.95 paperback. Reviewed by Stuart Durant.     

Plant Tissue 2

A new five-element electrical model was proposed recently (Zhang,Stout, and Willison, 1990; Zhang and Willison, 1991) to representplant tissues. In previous studies on the relationship betweenelectrical impedance and cold-hardiness, one of us had analyseddata in relation to a simpler three-element electrical model.Here, we have re-analysed these data in relation to the morecomplex model. F-tests showed that the new model always fittedmeasured impedance spectra significantly better (P<0·005)than the earlier model. The previously reported increase inintracellular resistance during cold acclimation was found tobe related to increased resistance of both the cytoplasm andvacuole In the species trial of birdsfood trefoil and alfalfa, coldacclimation was accompanied by an increase in extracellularresistance and a decrease in capacitances of both the plasmamembrane and tonoplast. In the cultivar trial of birdsfoot trefoil,cold acclimation did not affect plasma membrane capacitancein Viking and extracellular resistance in both Leo and Viking.In the species and growth time trial, cold acclimation was accompaniedby a decrease in plasma membrane capacitance in alfalfa butnot in birdsfoot trefoil Key words: Electrical impedance, cold acclimation, equivalent electrical circuit     

The viking biological investigations: Review and status

The three experimental approaches incorporated into the Viking biology instrument have yielded results that are most readily explained as nonbiological phenomena. The predominant view among investigators trying to simulate the Mars results is that the surface material of Mars contains strongly oxidizing compounds which would account for many of the more intense reactions seen on Mars. Other mechanisms are also currently being proposed and studied.     

Book Review Section: Reviewer's Choice

Design for the Real Word Pantheon Books: List price $8.95 Reviewed by Victor Papanek.

Graphic History of Architecture. Viking Press, List price $9.95. Reviewed by John Mansbridge.

Plastics as Design Form: Chilton Book Co., List price $17.95. Reviewed by Thelma R. Newman.     

BOOK REVIEWS

Book reviewed in this article:
All 48 pp., illustrated in colour. Collins, London in association with ICI Products
A Monographic Study of the Genus Rosdaria (Crassnlaceae). Urs Eggli. 119pp., 5 colour plates, 61 monochrome figs
Clematis. Christopher Lloyd (revised by Tom Bennett). 2 16 pp., 45 colour plates. Viking, London     

Factors affecting the field infection of potato tubers of different cultivars by blight (Phytophthora infestans)

The relationships between rain and blight (Phytophthora infestans) were studied in unsprayed crops of cultivars differing widely in foliage and tuber susceptibility. The occasions when tubers were infected depended on rain and not cultivar, but numbers of tubers infected after rain was affected by the blight susceptibility of the cultivar. Infected tubers were first found when less than 5 % (BMS key) of the potato foliage was infected but few fresh infections occurred when 50–75% of the foliage had been destroyed. Some tubers were infected after 8 mm rain (tubers near the surface with even less) but large increases in numbers of tubers infected usually occurred only after 25 mm or more had increased soil moisture to above ‘field capacity’ around the tuber for at least 24 h. The most susceptible cultivars Ulster Ensign and Arran Banner had all plants with some tuber blight, and some plants with all tubers affected and often many lesions per tuber. Cultivars of intermediate susceptibility, King Edward and Up-to-Date, had some plants without blighted tubers, many with a few and very few with all. The more resistant cultivars Majestic and Arran Viking had many plants without infected tubers and many lesions that aborted while still necrotic threads, so that the fungus did not spread. Most infections occurred through tuber eyes, lenticels or sometimes growth cracks. The distribution of blight lesions on tubers differed in the different seasons, for example, lenticels were most commonly infected on Arran Banner and Ulster Ensign and eyes on King Edward, Majestic and Arran Viking. In late or slowly developing attacks, lesions on stems became more numerous and larger than in fast, early attacks and were prolific sources of spores on King Edward and Up-to-Date but not on Majestic and Arran Viking. Because much rain water runs down the stems of Up-to-Date and King Edward, stem lesions can provide an important source of inoculum for tubers.     

Laboratory investigations of mars: Chemical and spectroscopic characteristics of a suite of clays as Mars Soil Analogs

Two major questions have been raised by prior explorations of Mars. Has there ever been abundant water on Mars? Why is the iron found in the Martian soil not readily seen in the reflectance spectra of the surface? The work reported here describes a model soil system of Mars Soil Analog Materials, MarSAM, with attributes which could help resolve both of these dilemmas. The first set of MarSAM consisted of a suite of variably iron/calcium-exchanged montmorillonite clays. Several properties, including chemical composition, surface-ion composition, water adsorption isotherms, and reflectance spectra, of these clays have been examined. Also, simulations of the Viking Labeled Release Experiment using the MarSAM were performed. The results of these studies show that surface iron and adsorbed water are important determinants of clay behavior as evidenced by changes in reflectance, water absorption, and clay surface reactions. Thus, these materials provide a model soil system which reasonably satisfies the constraints imposed by the Viking analyses and remote spectral observations of the Martian surface, and which offers a sink for significant amounts of water. Finally, our initial results may provide insights into the mechanisms of reactions that occur on clay surfaces as well as a more specific approach to determining the mineralogy of Martian soils.     

Microbiological profiles of the Viking spacecraft.

Planetary quarantine requirements associated with the launch of two Viking spacecraft necessitated microbiological assessment during assembly and testing at Cape Canaveral and the Kennedy Space Center. Samples were collected from selected surface of the Viking Lander Capsules (VLC), Orbiters, (VO), and Shrouds at predetermined intervals during assembly and testing. Approximately 7,000 samples were assayed. Levels of bacterial spores per square meter on the VLC-1 and VLC-2 were 1.6 x 10(2) and 9.7 x 10(1), respectively, prior to dry-heat sterilization. The ranges of aerobic mesophilic microorganisms detected on the VO-1 and VO-2 at various sampling events were 4.2 x 10(2) to 4.3 x 10(3) and 2.3 x 10(2) to 8.9 x 10(3)/m2, respectively. Approximately 1,300 colonies were picked from culture plates, identified, lypholipized, and stored for future reference. About 75% of all isolates were microorganisms considered indigenous to humans; the remaining isolates were associated with soil and dust in the environment. The percentage of microorganisms of human origin was consistent with results obtained with previous automated spacecraft but slightly lower than those observed for manned (Apollo) spacecraft.