Surface Water Film Research Articles

Attachment of Salmonella on Modified Poultry Skin Surface

ABSTRACTPoultry skin was treated with formalin, trisodium phosphate, lipase, and papain before attachment. No treatment affected ultimate attachment level. Attachment using different cell suspension concentrations showed that there was a limitation in attachment level for each cell suspension concentration. Total numbers of Salmonella cells on poultry skin including cells in the surface water film were compared with numbers of irreversibly attached cells that remained after washing. At 107 CFU/mL inoculation, irreversibly attached cells accounted for 93% of the total surface cell population after 60 min exposure and at 108 level, it was 38%.

The influence of water content and leaf anatomy on carbon isotope discrimination and photosynthesis in Sphagnum

ABSTRACTThe relative effect of diffusional resistance due to water films (rwf) and leaf anatomy (rp) on rates of net photosynthesis and on‐line measures of carbon isotope discrimination (Δ=Δδ13C) was investigated in Sphagnum. Sphagnum species differ in the exposure of photosynthetic cells at the leaf surface. In S. affine, photosynthetic cells are widely exposed at the surface, whereas in S. magellanicum, photo‐synthetic cells are enclosed within water‐filled hyaline cells. This difference is expected to lead to variation in diffusive resistance within leaves (rp). Net photosynthesis and on‐line Δ were measured at two water contents: greenhouse water content (wet) and blotted dry (dry). Without correcting for respiration, on‐line Δ values differed significantly between wet (23.7%o) and dry (30.9%o) plants. However, there was no significant difference between species means and no species × water content interaction. Corrections for respiration lowered Δ values by approximately 8.1%o and reduced the mean difference to 3.1%o, but did not alter the rank order of treatments. Net photosynthesis also decreased by 16% in wet plants, but there was no significant difference between the two species. In addition, five populations of S. affine and S. magellanicum grown in a common garden were analysed for their organic matter carbon isotope composition (δ13C). These values varied more within each species (0.9–1.2%o) than between the two species (0.6%o). Therefore, we conclude that variation in surface water films leads to a greater difference in resistance to CO2 uptake and carbon isotope discrimination than that due to variation in leaf anatomical properties in Sphagnum.

Cladistic inference and evolutionary scenarios: Locomotory structure, function, and performance in water striders

A research methodology that aims to reveal how historical changes in environmental conditions (or selective regimes) have shaped the adaptive evolution of clades is applied to the adaptive evolution of water striders and their allies (Hemiptera-Heteroptera, Gerromorpha), a group of semiaquatic insects which includes species that are conspicuously adapted to life on the surface film of water. Based upon reconstructed phylogenies for the higher gerromorphan taxa, the hypothesis that the hygropetric zone is the ancestral one is confirmed for the Mesoveliidae, Hebridae and the clade comprising the Paraphrynoveliidae, Macroveliidae and Hydrometridae, but not for the Hermatobatidae and Veliidae. There is no support for the hypothesis that the intersection zone was a sort of transitional zone during the ecological evolution of pleustonic bugs. It is shown that the unique morphological and behavioural traits of the most derived members of this group evolved after inferred historical changes in environmental conditions and therefore qualify as adaptations in the sense of Gould and Vrba (1982), Coddington (1988) and Baum and Larson (1991). Other predictions about the adaptive evolution of gerromorphan bugs do not pass the cladistic test. The study illustrates that cladistic inference is a valuable tool in clarifying and sharpening retrospective explanations of complex evolutionary scenarios.

CLADISTIC INFERENCE AND EVOLUTIONARY SCENARIOS: LOCOMOTORY STRUCTURE, FUNCTION, AND PERFORMANCE IN WATER STRIDERS.

— A research methodology that aims to reveal how historical changes in environmental conditions (or selective regimes) have shaped the adaptive evolution of clades is applied to the adaptive evolution of water striders and their allies (Hemiptera‐Heteroptera, Gerromorpha), a group of semiaquatic insects which includes species that are conspicuously adapted to life on the surface film of water. Based upon reconstructed phylogenies for the higher gerromorphan taxa, the hypothesis that the hygropetric zone is the ancestral one is confirmed for the Mesoveliidae, Hebridae and the clade comprising the Paraphrynoveliidae, Macroveliidae and Hydrometridae, but not for the Hermatobatidae and Veliidae. There is no support for the hypothesis that the intersection zone was a sort of transitional zone during the ecological evolution of pleustonic bugs. It is shown that the unique morphological and behavioural traits of the most derived members of this group evolved after inferred historical changes in environmental conditions and therefore qualify as adaptations in the sense ofGould and Vrba (1982),Coddington (1988) andBaum and Larson (1991). Other predictions about the adaptive evolution of gerromorphan bugs do not pass the cladistic test. The study illustrates that cladistic inference is a valuable tool in clarifying and sharpening retrospective explanations of complex evolutionary scenarios.

Free Fatty Acids of Surface Film of Water in the Sydinsky Bay of the Krasnoyarsk Reservoir

AbstractDuring the summer of 1990 composition and concentrations of free fatty acids (FFA) in the surface film of water were investigated. 23 FFA species were identified. Using cluster analysis in conjunction with ANOVAR correspondence of FFA contents in the surface film with seasonal patterns of pelagic plankton was proved. Three different groups of FFA were revealed, acids of every group had similar seasonal dynamics and presumably were of similar origination. Data obtained gave a chance to suppose that main part of FFA were originated by exudation of living cells of phytoplankton as well as postmortal exudation of bacterioplankton. On the basis of FFA contents in a single sample from the surface film identification of sign of derivatives of phytoplankton biomass was suggested. This express‐assay may be useful for monitoring.

Vapor‐phase partitioning of volatile organic compounds: A regression approach

AbstractPartitioning of 15 volatile organic compounds (VOCs) between the vapor phase and dry and moist Al2O3 samples was measured using a headspace technique. The best predictors of partition coefficients (K′p) from the vapor phase varied with the three Al2O3 moisture contents (MCs) used; these variations may reflect alternate sorption mechanisms. For instance, sorption of chlorinated hydrocarbons at 1.9% MC was best explained by the hydrogen bond acceptor parameter β, suggesting hydrogen bonding between the —Cl group and surface groups or water films. However, sorption on humic acid‐coated Al2O3 at approximately 45% MC was best explained by the log of the aqueous solubility and Henry's law constant. The importance of aqueous solubility and Henry's law constant suggested that dissolution of organic compounds in interstitial water is a primary sorption mechanism for VOCs at high Al2O3 MCs. Sorption of the relatively insoluble hydrocarbons such as n‐alkanes occurred in excess of that explained by dissolution in the interstitial water and may reflect the importance of partitioning into the organic matter provided by the humic acid coating.

Nesting behavior of the semi-aquatic spider wasp,Anoplius eous, which transports its prey on the surface film of water (Hymenoptera, Pompilidae)

Anoplius eous Yasumatsu (Hymenoptera, Pompilidae) exhibits some outstanding nesting behavior. Females excavate a unicellular or multicellular nest in wet ground, or dig a single-celled nest in rotten wood, or build clustered mud cells in narrow spaces between walls of such substances as wood or vinyl sheets. The latter nest-type has been unknown within the subfamily Pompilinae. Females prepare a nest-cell before hunting, and construct it further after hunting, leaving the prey near the nest (behavior-formula: IVPTIOC). They transport their prey backward on the ground, grasping it in their mandibles by any part of the legs, and forward on the surface film of water or on the ground, grasping it by the middle part of the 1st or 2nd legs. Their only prey is the adult female semi-aquatic spider,Pardosa pseudoannulata (Lycosidae). These nesting and provisioning behavior patterns are compared with those of other pompilids. The position of the present species in the behavioral evolution of the Pompilidae is suggested.

Observations on the feeding biology ofAlgophagus pennsylvanicus(Astigmata: Algophagidae), a mite restricted to water-filled treeholes

ABSTRACT Morphological as well as biological evidence indicates that Algophagus pennsylvanicus, an obligate inhabitant of water-filled treeholes in eastern North America, is a “scraper” (= grazer) and feeds by shearing fungal hyphae from the surface of decomposing leaves. In addition, it is probable that this species filters fine particulate organic matter from the water surface film and is therefore a filtering “collector” as well.

Impedance Measurement of Thallus Moisture Content in Lichens

AbstractThe indirect determination of water content in lichen thalli by means of impedance measurement is described. This technique applies an alternating current between small clips placed at the margins of lichen thalli. Two zones of sensitivity were apparent in measurements with the foliose lichen Xanthoparmelia chlorochroa. Ready discrimination was provided between fully saturated thalli and thalli with standing surface water films. Similarly, this technique proved highly accurate as a measurement of thallus moisture content at water potentials of –2·5 MPa and less (between 0 and 40% water content by weight in X. chlorochroa). Resolution was lower at intermediate water contents (c. 60–100Δ water content by weight), although general trends were still clearly evident. This technique is ideally suited for unattended measurements of water potential in lichens using currently available data–logger technology and provides high resolution within the range of water potentials crucial to the control of physiological activity in lichens

Comparative Functional Morphology of the Mouth Brushes of Mosquito Larvae (Diptera: Culicidae)

Structural and morphological features of the feeding brushes of fourth instars of four species of mosquitoes were studied using light and scanning electron microscopes. The fine structure of the elements of the lateral palatal brushes, anteromedian palatal brushes, mandibular brushes and combs, and maxillary brushes of each species was investigated and related to feeding behavior. The movement of the mouth brushes in living larvae was observed by stereomicroscopy under laboratory conditions. Mouth brush function and morphology varied among the species studied. The brushes of Culex quinquefasciatus Say, Cx. tarsalis Coquillett, and Aedes aegypti L. were more complex than those of Anopheles albimanus Wiedemann. The main role of the filaments of the lateral palatal brushes (LPB) was to generate and maintain water and particle flow around the larval head. In Ae. aegypti, most of the LPB filaments were provided with stout pointed teeth at the tips which were useful in the brushing of food material. In An. albimanus, the LPB filaments were simple and very closely packed and were used to stir the water surface film to direct the floating materials into the area of the mouth opening. The filaments of the anteromedian palatal brush (APBr) in the Culex species were branched. In Ae. aegypti, the APBr contained long bladelike filaments and short teethlike elements, whereas in An. albimanus, the APBr filaments were all long and bladelike. The morphological structure of the spicules and setae of the mandibular brushes and combs and the maxillary brushes are described. The main function of these brushes is to direct and concentrate particle flow.

A numerical study of a structure protected by water film from an incident heat flux

A finite difference method is adopted to investigate the heat transfer mechanisms of thermal protection problem. This problem concerns with a structure protected by water film suffering a severe heat flux by thermal radiation from sorrounding. The heat transfer mechanisms consist mainly of the sensible and evaporative heat transfer of the water film and sensible heat transfer of the structure. In the process of analysis, the amount of heat absorbed by the water film is calculated by Beer's law, and evaporation occurring on the water film surface is considered. In order to compare the contributions of the heat transfer mechanisms, the variations of temperature distribution of the structure and the water film are examined in detail and the results show that the temperature of structure decreases effectively due to the protection of the water film.

Aqueous Diffusion Coefficients in Unsaturated Materials

ABSTRACTSimple diffusion coefficients, D(θ), in most unsaturated media were found to be primarily a function of water content and not material characteristics except where the characteristics affect or determine water content. At high water contents, D(θ) gradually declines as water content decreases, from 10−5 cm2/sec at a volumetric water content of about 50% to 10−7 cm2/sec at a volumetric water content of about 5%, followed by a sharp decline as surface water films become thin and discontinuous and pendular water elements become very small, from 10−7 cm2/sec at a volumetric water content of about 5% to 10−9 cm2/sec at a volumetric water content of about 0.5% to 1%.

An evaluation of some myths concerning the culture of daphnids

Contrary to established beliefs, this paper indicates: (1) that daphnids can, without suffering damage, be dropped through the surface film of water, (2) that an increase in the hardness of culture water does not result in healthier daphnids as measured by body growth, survival or reproduction and (3) that the fecundity of healthy female daphnids does not decrease with age. Finally, it is pointed out that there has never been a demonstration of a Lansing effect for any species in the genus Daphnia and, therefore, there is no reason to believe that the vitality of neonates decreases as the age of their mother increases.

ADAPTIVE RELATIONSHIP BETWEEN LEAF WATER REPELLENCY, STOMATAL DISTRIBUTION, AND GAS EXCHANGE

Although numerous studies have considered the functional significance of the terrestrial plant leaf surface, the importance of water repulsion for enhancing photosynthetic carbon uptake (CO2) has not been recognized and appears to involve an array of structural adaptations. The large majority of species tested had leaf surfaces that repelled water to such an extent that varying degrees of water‐bead formation occurred. On more wettable leaves, the formation of a water surface film (dewfall) severely curtailed photosynthetic CO, uptake in the field, most likely because CO2 diffuses 104 times slower in water than air. Water bead formation not only enabled maintenance of high photosynthetic rates but also increased water use efficiency several fold. In 3 of 5 species tested in the field, water bead formation after artificial wetting resulted in greater stomatal opening and increases in photosynthesis of up to 34%. The most nonwettable leaf surface on a given leaf also had all or the majority of the leaf's stomata in 50 of the 57 species tested, indicating a potentially strong adaptive relationship between leaf surface wettability, stomatal occurrence, and photosynthetic performance.

Spectroscopic Evaluation on Photosensitive Langmuir Films Using Multichannel Spectrophotometer

The UV and visible (VB) transmission spectra of monolayers of some materials having long hydrocarbon chains on a water surface (Langmuir (L) film) were obtained by the real time direct measurement using a multichannel spectrophotometer during surface pressure-area isotherm measurements. It was found that the change of surface pressure as a function of area (Π-A curve) does not always agree with that of optical absorption as a function of area, and therefore the Π-A curve does not always reflect the molecular arrangement of molecules in the L film. The rates of photochemical reaction of the L films can be studied in relation to the molecular arrangement of the monolayers using this method. The spectra of the L film which were obtained by a reflection method using polarized light were further proven to be valid in studying the molecular arrangement in the L film.

Nitrogen Fixation on a Tropical Volcano, La Soufrière (Guadeloupe): The Interaction of Temperature, Moisture, and Light with Net Photosynthesis and Nitrogenase Activity in Stereocaulon Virgatum and Response to Periods of Insolation Shock

AbstractThe response of net photosynthesis, dark respiration and acetylene reduction to temperature, moisture and light intensity were examined for Stereocaulon virgatum growing in the cloud/shroud zone on the tropical volcano La Soufrière, Guadeloupe, French West Indies. Rates for both acetylene reduction and net photosynthesis were maximal at saturating water contents, a pattern attributed to the finely branched nature of the phyllocladoid branchlets and the exposed position of spherical cephalodia, both of which minimize the formation of surface and interhyphal water films. Under conditions typical of those during cloud/shroud periods (13–16°C), thalli of S. virgatum exhibit many characteristics seen in other shade-tolerant lichen species. Net photosynthesis was light saturated at 300 μmol m−2 s−1 PAR, while the photocompensation point was less than 25 µmol m−2 s−1 PAR. Net photosynthetic uptake of carbon dioxide was optimal at 27–34°C, at which point light saturation was near 700 µmol m−2 s−1 PAR and the photocompensation point between 50 and 100 µmol m−2 s−1 PAR. Thalli of S. virgatin exhibited temperature-dependent sensitivity to high insolation. Only at 20°C were thalli able to tolerate high light exposure without reduction of apparent quantum yield. Exposure to high light intensity at 40°C inhibited the apparent quantum yield by almost 40% and acetylene reduction by 95%. This suggests brief periods of insolation shock may exert an influence disproportionately higher than either their frequency or duration. Thalli are normally exposed to cloud/shroud conditions but net photosynthetic uptake was maximal only during periods of elevated thallus temperature experienced at the onset of an insolation shock. However, with prolonged high insolation exposure and further elevation of thallus temperatures and thallus desiccation, severe impairment of subsequent photosynthetic activity ensues. S. virgatum may be characterized as a shade-tolerant species but its physiology is more adapted in some respects to conditions experienced during rare periods of full insolation.

The incidence of bdellovibrios in an artificial environment: the national aquarium in Baltimore

The presence of bdellovibrios was established in three aquatic tanks in the National Aquarium in Baltimore and the incidence of the predators was studied. Each of three tanks differed in physical and chemical properties and in the kinds of animal inhabitants. Samples of water, sediment, and bioring surface film were collected from various tanks and were cultured for bdellovibrios and heterotrophic bacteria. The total number of bacteria in the samples was estimated by the direct count method. At the time of sampling, measurements were taken of the water temperature and salinity. Of 12 samples collected periodically from each of two tanks over a 12-month period, bdellovibrios were recovered from 8 samples. In a third tank the predators were recovered from 7 of the 12 samples. Of samples collected daily over a 10-day period from two tanks, bdellovibrios were recovered from one tank each day, but the organisms were not recovered from the second tank during the 10-day period. The predators were recovered more often from water and sediment samples than from samples of the surface film of biorings. With few exceptions, a greater number of the predators were recovered from sediment samples than from samples of water and bioring surface film. From each tank the number of bdellovibrios recovered was observed to fluctuate greatly. The basis for the observed fluctuations was not determined. The incidence of recovery of bdellovibrios from aquarium tanks in this study suggests that the organisms are capable of becoming established as resident flora in an artificial environment such as an aquarium. An aquarium with suitable environmental conditions presents great opportunities to conduct carefully selected studies on the ecology of bdellovibrios in an environment in which certain chemical and physical factors are controlled. Studies of bdellovibrios in controlled environments may lead to a greater understanding of the activities and role of these predators.

Surface Heat Transfer Distribution in a Weir Type Pressurized Water Retort for Processing Foods in Flexible Retort Pouches

A method for measuring water surface (film) heat transfer coefficients in a retort for processing foods in flexible retort pouches was developed. The retort which was studied employs horizontally flowing water between stacked trays which contain the food pouches during the thermal sterilization cycle. The method was used to measure the distribution of the surface heat transfer coefficients throughout the retort during the heating and cooling cycles. Film coefficient values obtained at various temperatures were found to vary considerably according to test location, and processing phase (whether heating or cooling). The average values observed at 120°C varied between 1100 and 2400 W/(m2· °C) for heating and between 1800 and 4100 W/(m2·C°) for cooling. These values were found to be much smaller than film coefficient values for steam-air mixtures obtained by others under laboratory test conditions. The measured surface coefficient values were used in a computer simulation to determine the transient heat transfer response of beef and potato in pouches subjected to thermal processes of various process times. This study revealed that the observed variation in the film coefficient produces large relative variations in total integrated centre point lethality.

Experiences with bacteriological monitoring of pool water.

A bacteriological study was completed on pools and whirlpools operated by hotels and private health clubs in the metropolitan area of Toronto, Ontario, Canada. Coliform bacteria, fecal coliform bacteria, and fecal streptococci were found only when other indices showed a drastic deterioration in water quality. Aerobic plate counts were higher, and staphylococci and Pseudomonas aeruginosa occurred more often in whirlpools than in swimming pools. There was a correlation between aerobic plate counts and the presence of staphylococci and P. aeruginosa. P. aeruginosa was rare in swimming pools in the absence of staphylococci; however, in whirlpools the organism was often found in the absence of staphylococci, and when aerobic plate counts were low. P. aeruginosa and plate counts in excess of 3,000 per ml occurred more frequently in whirlpools when the free chlorine residual was less than one part per million. The surface film showed concentrations of staphylococci far greater than the pool water. Whirlpools appear to present a different ecosystem that favors the establishment of P. aeruginosa. Staphylococci, but not Staphylococcus aureus, are useful in indicators of pool water quality but better laboratory methodology is required. Additional attention should be directed to the bacteriology of the water surface film, which presents a more direct hazard to bathers.

The Fate of Pentachlorophenol in the Bay of Quinte, Lake Ontario

Unfiltered water, surface film, sediment, and biota samples were collected from the Bay of Quinte between May and September 1978 and analyzed for chlorophenols (CPs). Sectioned sediment cores were dated using 210Pb and 137Cs analyses. Pentachlorophenol (PCP) was found at high concentrations adjacent to a point source and was detected in all compartments examined throughout the bay (a bioaccumulation factor of 10 4 was observed for PCP in fish). The ratio of 2,3,4,6- and 2,3,5,6-tetrachlorophenols (TTCPs) to PCP increased with distance from the source in the water column and surface film. Photochemical reduction was proposed to account for the phenomenon. CP concentrations in sectioned cores suggested that settling particles adsorb CPs in similar proportion to that observed in the water column and little further change occurs after burial.