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Sample records for stalk forming diatoms

  1. ENVIRONMENTAL CONTROL OF STALK LENGTH IN THE BLOOM-FORMING, FRESHWATER BENTHIC DIATOM DIDYMOSPHENIA GEMINATA (BACILLARIOPHYCEAE)(1).

    Science.gov (United States)

    Kilroy, Cathy; Bothwell, Max

    2011-10-01

    Blooms of the freshwater stalked diatom Didymosphenia geminata (Lyngb.) M. Schmidt in A. Schmidt typically occur in oligotrophic, unshaded streams and rivers. Observations that proliferations comprise primarily stalk material composed of extracellular polymeric substances (EPS) led us to ask whether or not the production of excessive EPS is favored under nutrient-limited, high-light conditions. We conducted experiments in outdoor flumes colonized by D. geminata using water from the oligotrophic, D. geminata-affected Waitaki River, South Island, New Zealand, to determine the relationship between D. geminata stalk length, cell division rates, and light intensity under ambient and nutrient-enriched conditions. Stalk lengths were measured in situ, and cell division rates were estimated as the frequency of dividing cells (FDC). FDC responded positively to increasing light intensity and to nutrient additions (N+P and P). Under ambient conditions, stalk length increased as light level increased except at low ambient light levels and temperature. Nutrient enrichment resulted in decreased stalk length and negative correlations with FDC, with this effect most evident under high light. Our results are consistent with the hypothesis that extensive stalk production in D. geminata occurs when cell division rates are nutrient limited and light levels are high. Thus, photosynthetically driven EPS production in the form of stalks, under nutrient-limited conditions, may explain the development of very high biomass in this species in oligotrophic rivers. The responses of FDC and stalk length under nutrient-replete conditions are also consistent with occurrences of D. geminata as a nondominant component of mixed periphyton communities in high-nutrient streams. © 2011 Phycological Society of America.

  2. Molecular Characterisation and Co-cultivation of Bacterial Biofilm Communities Associated with the Mat-Forming Diatom Didymosphenia geminata.

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    Brandes, Josephin; Kuhajek, Jeanne M; Goodwin, Eric; Wood, Susanna A

    2016-10-01

    Didymosphenia geminata (Lyngbye) M. Schmidt is a stalked freshwater diatom that is expanding its range globally. In some rivers, D. geminata forms thick and expansive polysaccharide-dominated mats. Like other stalked diatoms, D. geminata cells attach to the substratum with a pad of adhesive extracellular polymeric substance. Research on D. geminata and other diatoms suggests that bacterial biofilm composition may contribute to successful attachment. The aim of this study was to investigate the composition and role of bacterial biofilm communities in D. geminata attachment and survival. Bacterial biofilms were collected at four sites in the main stem of a river (containing D. geminata) and in four tributaries (free of D. geminata). Samples were characterised using automated rRNA intergenic spacer analysis and high-throughput sequencing (HTS). Mat-associated bacteria were isolated and their effect on the early establishment of D. geminata cells assessed using co-culturing experiments. ARISA and HTS data showed differences in bacterial communities between samples with and without D. geminata at two of the four sites. Samples with D. geminata had a higher relative abundance of Sphingobacteria (p geminata reduced survival (p geminata. Attachment was enhanced by Micrococcus sp. and Pseudomonas sp. (p geminata, and may partly explain observed distribution patterns.

  3. Microstructure and nanomechanical properties of single stalks from diatom Didymosphenia geminata and their change due to adsorption of selected metal ions.

    Science.gov (United States)

    Zgłobicka, Izabela; Chlanda, Adrian; Woźniak, Michał; Łojkowski, Maciej; Szoszkiewicz, Robert; Mazurkiewicz-Pawlicka, Marta; Święszkowski, Wojciech; Wyroba, Elżbieta; Kurzydłowski, Krzysztof J

    2017-08-01

    We present topographical and nanomechanical characterization of single Didymosphenia geminata stalk. We compared the samples before and after adsorption of metal ions from freshwater samples. Transmission electron microscopy studies of single stalk cross-sections have shown three distinct layers and an additional thin extra coat on the external layer (called "EL"). Using scanning electron microscopy and atomic force microscopy (AFM), we found that topography of single stalks after ionic adsorption differed significantly from topography of pristine stalks. AFM nanoindentation studies in ambient conditions yielded elastic moduli of 214 ± 170 MPa for pristine stalks and 294 ± 108 MPa for stalks after ionic adsorption. Statistical tests showed that those results were significantly different. We conducted only preliminary comparisons between ionic adsorption of several stalks in air and in water. While the stalks with ions were on average stiffer than the pristine stalks in air, they became more compliant than the pristine stalks in water. We also heated the stalks and detected EL softening at 50°C ± 15°C. AFM nanoindentation in air on the softened samples yielded elastic moduli of 26 ± 9 MPa for pristine samples and 43 ± 22 MPa for stalks with absorbed metal ions. Substantial decrease of the EL elastic moduli after heating was expected. Significantly different elastic moduli for the samples after ionic adsorption in both cases (i.e., for heated and nonheated samples), as well as behavior of the stalks immersed in water, point to permanent structural EL changes due to ions. © 2017 Phycological Society of America.

  4. Taxonomic studies of centric diatoms (Diatomeae: unusual nanoplanktonic forms and new records for Brazil

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    Kaoli Pereira Cavalcante

    2013-06-01

    Full Text Available There have been few taxonomic studies of centric diatoms in lotic freshwater environments in Brazil, especially in terms of those including nanoplanktonic forms, which are often neglected in studies of local floras, because of their small size or confusing taxonomy. This is the first study focusing on centric diatoms in the flora of the state of Bahia, in northeastern Brazil. Plankton and periphyton attached to Eichornia crassipes were collected in the winter of 2009 in the Cachoeira River. The diatoms were analyzed and described under light and electron microscopies. Seventeen infrageneric taxa were identified. Cyclotella was represented by five taxa, and concerning of similarities between diacritical features of species in this genus, their descriptions were thoroughly detailed. This was the first time that Cyclotella atomus var. marina, previously recorded only in coastal areas of Japan and Korea, has been documented in a river in South America. We also identified two diatom taxa previously unrecorded in the flora of Brazil: C. cryptica and C. meduanae. Finally, we present a detailed light, transmission and scanning electron microscopy analysis of Skeletonema potamos, a diatom rarely found in the Brazilian literature.

  5. Electrophoretic protein profiles of mid-sized copepod Calanoides patagoniensis steadily fed bloom-forming diatoms

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    Victor M Aguilera

    2015-09-01

    Full Text Available Recent field and experimental evidence collected in the southern upwelling region off Concepción (36°5'S, 73°3'W showed an abrupt reduction (<72 h in the egg production rates (EPR of copepods when they were fed steadily and solely with the local bloom-forming diatom Thalassiosira rotula. Because diatoms were biochemically similar to dinoflagellate Prorocentrum minimum, a diet which supported higher reproductive outcomes, the fecundity reduction observed in copepod females fed with the diatom may have obeyed to post-ingestive processes, giving rise to resources reallocation. This hypothesis was tested by comparing feeding (clearance and ingestion rates, reproduction (EPR and hatching success and the structure of protein profiles (i.e., number and intensity of electrophoretic bands of copepods (adults and eggs incubated during 96 h with the two food conditions. The structure of protein profiles included molecular sizes that were calculated from the relative mobility of protein standards against the logarithm of their molecular sizes. After assessing the experimental conditions, feeding decreased over time for those females fed with T. rotula, while reproduction was higher in females fed with P. minimum. Electrophoretic profiles resulted similar mostly at a banding region of 100 to 89-kDa, while they showed partial differences around the region of 56-kDa band, especially in those females fed and eggs produced with T. rotula. Due to reproductive volume was impacted while larvae viability, a physiological processes with specific and high nutritional requirements, was independent on food type; post-ingestive processes, such as expression of stress-related proteins deviating resources to metabolic processes others than reproduction, are discussed under framework of nutritional-toxic mechanisms mediating copepod-diatoms relationships in productive upwelling areas.

  6. Grazer-induced transcriptomic and metabolomic response of the chain-forming diatom Skeletonema marinoi

    DEFF Research Database (Denmark)

    Amato, Alberto; Sabatino, Valeria; Nylund, Göran M.

    2018-01-01

    Diatoms and copepods are main actors in marine food webs. The prey-predator interactions between them affect bloom dynamics, shape marine ecosystems and impact the energy transfer to higher trophic levels. Recently it has been demonstrated that the presence of grazers may affect the diatom prey b...

  7. Stalking and Violence.

    Science.gov (United States)

    Ostermeyer, Britta; Friedman, Susan Hatters; Sorrentino, Renee; Booth, Brad D

    2016-12-01

    The three widely known stalker classifications assist in categorizing stalkers, which allows for better management of violence risk. Although 80% of stalking is done by men, women also engage in stalking, and their violence risk should not be underestimated. Juvenile stalkers do exist and juvenile stalking is also associated with violence. Clinicians can become a victim of stalking and may become victims of stalking by proxy, a special type of stalking behavior where the stalker involves other people or agencies to communicate with or track their victim. A careful stalking violence risk assessment is essential in the intervention and risk management process. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Adolescent stalking and risk of violence✩

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    Smith-Darden, Joanne P.; Reidy, Dennis E.; Kernsmith, Poco D.

    2018-01-01

    Stalking perpetration and the associated risk for violence among adolescents has generally been neglected. In the present study, 1236 youth completed surveys assessing empirically established stalking indicators, threats and aggression toward stalking victims, dating violence, and violent delinquency. Latent Profile Analysis identified 3 latent classes of boys: non-perpetrators (NP), hyper-intimate pursuit (HIP), and comprehensive stalking perpetrators (CSP) and, and 2 classes for girls: NP and HIP. Boys in the CSP class were the most violent youth on nearly all indices with boys in the HIP class demonstrating an intermediate level of violence compared to NP boys. Girls in the HIP class were more violent than NP girls on all indices. These findings suggest stalking in adolescence merits attention by violence prevention experts. In particular, juvenile stalking may signify youth at risk for multiple forms of violence perpetrated against multiple types of victims, not just the object of their infatuation. PMID:27641644

  9. Approaches for identifying change in the abundance and historical distribution of a freshwater diatom

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    Spaulding, S. A.; Pite, D.; Wolfe, A. P.; Sundareshwar, P. V.

    2011-12-01

    The diatom Didymosphenia geminata (Bacillariophyta) has been considered native to high latitudes of the Northern Hemisphere. In recent years, this species has expanded its range to New Zealand and South America, forming large, invasive blooms in rivers. In contrast, historical populations in Alaska (Katmai National Park) have remained unchanged, while those in at least one Montana site have declined. In addition to a complex distributional history, this diatom has proven its remarkable ability to produce high amounts of biomass in low nutrient rivers. The high biomass is composed of the diatom cytoplasm and silica cell wall, but the high amounts of organic mater are mostly composed of extracellular mucopolysaccaride stalks. For example, in a low nutrient river, Lake Creek in Grand Teton National Park, the biovolume of D. geminata was estimated to be 57 m3 / km of stream, containing nearly 400 μg P / g stalk (dry weight). We examine the recent pattern of expansion of this species, the geochemical processes associated with the stalk, and paleolimnological record to 10,000 ybp to access the ecological factors that relate to the geographic distribution of this microscopic species on a regional and global scale.

  10. Multicellular stalk-like structures in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Engelberg, D.; Mimran, A.; Martinetto, H.; Otto, J.; Simchen, G.; Karin, M.; Fink, G.R.

    1998-01-01

    Stalk formation is a novel pattern of multicellular organization. Yeast cells which survive UV irradiation form colonies that grow vertically to form very long (0.5 to 3.0 cm) and thin (0.5 to 4 mm in diameter) multicellular structures. We describe the conditions required to obtain these stalk-like structures reproducibly in large numbers. Yeast mutants, mutated for control of cell polarity, developmental processes, UV response, and signal transduction cascades were tested and found capable of forming stalk-like structures. We suggest a model that explains the mechanism of stalk formation by mechanical environmental forces. We show that other microorganisms (Candida albicans, Schizosaccharomyces pombe, and Escherichia coli) also form stalks, suggesting that the ability to produce stalks may be a general property of microorganisms. Diploid yeast stalks sporulate at an elevated frequency, raising the possibility that the physiological role of stalks might be disseminating spores

  11. A conceptual model for the growth, persistence, and blooming behavior of the benthic mat-forming diatom Didymosphenia geminata (Invited)

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    Cullis, J. D.; Gillis, C.; Bothwell, M.; Kilroy, C.; Packman, A. I.; Hassan, M. A.

    2010-12-01

    The nuisance diatom Didymosphenia geminata (didymo) presents an ecological paradox. How can this benthic algae produce such large amounts of biomass in cold, fast flowing, low nutrient streams? The aim of this paper is to present a conceptual model for the growth, persistence, and blooming behavior of this benthic mat-forming diatom that may help to explain this paradox. The conceptual model highlights the importance of distinguishing between mat thickness and cell growth. It presents evidence gathered from a range of existing studies around the world to support the proposed relationship between growth and light, nutrients and temperature as well as the importance of flood events and bed disturbance in mat removal. It is anticipated that this conceptual model will not only help in identifying the key controlling variables and set a framework for future studies but also support the future management of this nuisance algae. Summary of the conceptual model for didymo growth showing the proposed relationships for the growth of cells and mats with nutrients, radiation and water temperature and the dependence of removal on bed shear stress and the potential for physical bed disturbance.

  12. The prevalence of stalking in the Netherlands

    NARCIS (Netherlands)

    van der Aa, S.; Kunst, M.J.J.

    2009-01-01

    Over eight years after the enactment of the Dutch anti-stalking provisions there are still no figures detailing the prevalence of stalking in The Netherlands. This article aims to estimate the lifetime and annual prevalence of this form of victimization within the Dutch population. Questionnaires

  13. Stalking: Criminological and criminal law aspects

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    Dimovski Darko

    2016-01-01

    Full Text Available Starting from the historical aspects of stalking crime, the author first provides an overview of different definitions of this socially negative behavior in the legal documents of countries where such conduct was first criminalized. The author presents statistical data on the scope of stalking in the United States and Australia. The second part of the paper discusses different types of stalkers, whose distinctive features are analyzed in more detail. In particular, the author focuses on the causal link between the stalking crime and violence, as well as the victims' responses to their own victimization. In the next part of this article, the author provides a detailed analysis of a wide range of consequences of stalking crime. In some cases, the victim of stalking may become the perpetrator of a criminal act of murder, whereas the stalker becomes a victim of this serious form of homicide. Although these cases are not numerous, they call for further analysis and proposing new legal solutions related to the privileged forms of murder, which are aimed at improving the position of the victim of stalking who is the perpetrator of such homicide. Finally, the author argues in favour of incriminating a new type of felony - the crime of stalking (in line with the model envisaged in the criminal legislation of the Republic of Croatia, as well as a privileged homicide which may be designated as a murder of a stalker committed by a victim of stalking.

  14. Some thoughts on the neurobiology of stalking.

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    Meloy, J Reid; Fisher, Helen

    2005-11-01

    The authors examine the crime of stalking, including the cognitive traits, emotional reactions, attachment pathology, violence patterns and sex differences of samples of stalking offenders. They focus on two common types of stalkers: 1) those who sustain pursuit of a former sexual intimate who has rejected them; and 2) those who pursue a stranger or acquaintance who has failed to return the stalker's romantic overtures. The authors discuss data from neuroimaging (fMRI) studies of romantic love which suggest that these forms of stalking may be associated with heightened activity of subcortical dopaminergic pathways of the "Reward System" of the brain, perhaps in combination with low activity of central serotonin. The authors propose that this set of neural correlates may contribute to the stalker's focused attention, increased energy, following behaviors, obsessive thinking about and impulsivity directed toward the victim. To further explore the neural systems associated with stalking behavior, they also discuss several biopsychological phenomena associated with romantic rejection, including the "protest response," "frustration attraction," "abandonment rage" and "mate guarding." They illustrate the parallels between stalking and addiction. They conclude that stalking may be associated with a specific set of biological components and they offer suggestions for further research into this pathological emotional/motivational state.

  15. Stalking: a neurobiological perspective.

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    Marazziti, Donatella; Falaschi, Valentina; Lombardi, Amedeo; Mungai, Francesco; Dell'Osso, Liliana

    2015-01-01

    Nowadays stalking is becoming a real social emergency, as it may often fuel severe aggressive behaviours. No exhaustive aetiological hypothesis is still available regarding this complex phenomenon. However, the detailed descriptions of some of its peculiar features allow to draw with cautions some general suggestions. Probably stalking may arise from the derangement of those neural networks subserving the so-called social brain and the pair bonding formation, in particular the processes of attachment/separation, attraction/romantic love/reward. In addition, it seems to be modulated by excessive functioning of the dopamine system coupled with decreased serotonin tone. It is believed that the investigation and deepening of its possible neurobiological substrates may be helpful in the prevention of the severe consequences of stalking.

  16. Diatoms and the nanotechnology

    International Nuclear Information System (INIS)

    Toekesi, K.; Bereczky, R.J.; Lakatos, Gy.; Cserhati, C.

    2004-01-01

    Complete text of publication follows. During the last decade studies of interactions between highly charged ions (HCI) and solid surfaces are at the center of interest which is partly stimulated by potential future technical application such as nanofabrication. The investigation of the interactions of highly charged ions with internal surfaces recently become available due to the advances in the fabrication of micro- and nanocapillaries. These target materials offer the opportunity to observe 'hollow atom' formation in free space. Hollow atoms are an exotic form of matter where the atomic charge cloud resides in shells with large diameters while the core is virtually empty. In the past there has been an increasing amount of indirect evidence for the existence of this atomic state. Microcapillary transmission promises to provide direct evidence for the hollow atom formation for the first time. Our earlier theoretical descriptions rely on metallic microcapillaries which have proven to be quite successful in comparison with experimental data. However, since very detailed measurements have recently become available for insulator nanocapillaries, critical and precise tests of theory are only now being possible. We note, that the theoretical description of the interaction between the HCI and insulator nanocapillaries is far from being well understood. One of the key point of the experimental investigations is the preparation of the nanocapillaries. In this work we propose an alternative way to prepare insulator nanocapillaries. We take an advantage of the nature that during the evolution the cylindrical shape nanostructure was developed as a truss of diatoms. The truss of the diatoms contains roughly 99 % SiO 2 and in some cases of diatoms it form almost ideal cylindrical shape. As an example Fig. 1 shows the scanning electron micrograph of the diatom. The size of the holes in the truss are in the nanometer range (see Fig. 1a). On the basis of these properties the

  17. Pituitary stalk craniopharyngioma

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    Figueiredo, Eberval Gadelha; Welling, Leonardo Christiaan; de Faria, Jose Weber Vieira; Teixeira, Manoel Jacobsen

    2011-01-01

    Craniopharyngiomas are benign but aggressive neoplasms arising along the craniopharyngeal duct. It is frequently located in the suprasellar region. Primarily pituitary stalk craniopharyngioma is unusual and uncommonly early diagnosed, before it enlarges and extends to supra or parasselar region. This unusual location and the small size pose therapeutic dilemmas, since it has the ability to grow larger. Currently, no consensus exists regarding the optimal management. The authors have recommended complete resection. PMID:22715220

  18. Stalking Victimization in LGBTQ Adults: A Brief Report.

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    Langenderfer-Magruder, Lisa; Walls, N Eugene; Whitfield, Darren L; Kattari, Shanna K; Ramos, Daniel

    2017-03-01

    Stalking is often considered to be a form of interpersonal violence; yet, despite an increase in lesbian, gay, bisexual, transgender, and queer (LGBTQ)-specific research on other forms of interpersonal violence, such as intimate partner violence and sexual assault, there is a relative lack of literature on stalking victimization of LGBTQ individuals, particularly as it relates to gender identity. This is problematic given the results of numerous studies indicating LGBTQ individuals, and transgender individuals in particular, experience victimization in various forms and contexts at alarming rates. In the current study, we examined secondary data to determine the prevalence of lifetime stalking victimization and subsequent police reporting in a large community-based sample of LGBTQ individuals living in Colorado ( N = 1,116). In addition, using chi-square analyses, we examined independence of stalking experiences and police reporting by both gender identity ( transgender, cisgender male, cisgender female) and sexual orientation ( gay, lesbian, bisexual, heterosexual, queer, other). Approximately 15% of the total sample reported ever experiencing stalking; yet, only about one quarter of those who were stalked reported it to police. Although no statistically significant differences emerged by gender identity or sexual orientation, transgender, bisexual, and queer participants had the highest prevalence of lifetime stalking victimization. Moreover, these groups reported the lowest prevalence of reporting their victimization to the police. We provide suggestions to improve the development of research on this topic including a need for an inclusive definition of stalking and studies using larger, representative samples to better discern potential significant differences in stalking experiences of LGBTQ persons.

  19. A conceptual model for the blooming behavior and persistence of the benthic mat-forming diatom Didymosphenia geminata in oligotrophic streams

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    Cullis, James D. S.; Gillis, Carole-Anne; Bothwell, Max L.; Kilroy, Cathy; Packman, Aaron; Hassan, Marwan

    2012-06-01

    The benthic, mat-forming diatomDidymosphenia geminata has the unique ability to produce large amounts of algal biomass under oligotrophic conditions in cold, fast flowing streams and rivers. This presents an ecological paradox that challenges our current understanding of stream ecosystem dynamics. Our understanding of the drivers of D. geminata ecology is still limited. Here we present a conceptual model for the blooming behavior and persistence of this species to advance scientific understanding of strategies for life in fast flowing oligotrophic waters and support the design of future research and mitigation measures for nuisance algal blooms. The conceptual model is based on a synthesis of data and ideas from a range of disciplines including hydrology, geomorphology, biogeochemistry, and ecology. The conceptual model highlights the role of water chemistry, river morphology, and flow thresholds in defining the habitat window for D. geminata. We propose that bed disturbance is a primary control on accumulation and persistence of D. geminataand that the removal threshold can be determined by synthesizing site-specific information on hydrology and geomorphology. Further, we propose that a key to understanding the didymo paradox is the separation of cellular reproduction and mat morphology with specific controls acting in respect of the different processes.

  20. Biophotonics of diatoms

    DEFF Research Database (Denmark)

    Gössling, Johannes Wilhelm

    Diatoms are unicellular microalgae present in all aquatic environments on earth. Due to their high photosynthetic productivity and abundance, diatoms are main components of aquatic food webs and among the main contributors of global photosynthetic carbon fixation. A unique feature of diatoms...

  1. Stalking the ultimate particle

    CERN Multimedia

    2003-01-01

    If you missed the ARTE programme entitled "L'Ultime Particule" broadcast in February, you have another chance to catch it in CERN's Main Auditorium on 13 March. "L'Ultime Particule" is a documentary by the French director Michel Andrieu that seeks to explain particle physics through a contemplative quest for the research physicists of matter of today and yesteryear. Invariably kitted out in a red parka and a soft hat, the programme's investigator scours the planet and the archives in search of the research physicists who are stalking the ultimate particle, the Higgs boson, in their quest to understand the structure of matter. Naturally enough, CERN is an important stage of his journey where Michel Andrieu and his team spent several days last year. Both from the physics and metaphysical points of view, "L'Ultime Particule" is worth seeing. The film's director, Michel Andrieu, will introduce his documentary and answer questions from the audience after the documentary has been shown. L'Ultime Particule by Mic...

  2. Automated measurement of diatom size

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    Spaulding, Sarah A.; Jewson, David H.; Bixby, Rebecca J.; Nelson, Harry; McKnight, Diane M.

    2012-01-01

    Size analysis of diatom populations has not been widely considered, but it is a potentially powerful tool for understanding diatom life histories, population dynamics, and phylogenetic relationships. However, measuring cell dimensions on a light microscope is a time-consuming process. An alternative technique has been developed using digital flow cytometry on a FlowCAM® (Fluid Imaging Technologies) to capture hundreds, or even thousands, of images of a chosen taxon from a single sample in a matter of minutes. Up to 30 morphological measures may be quantified through post-processing of the high resolution images. We evaluated FlowCAM size measurements, comparing them against measurements from a light microscope. We found good agreement between measurement of apical cell length in species with elongated, straight valves, including small Achnanthidium minutissimum (11-21 µm) and largeDidymosphenia geminata (87–137 µm) forms. However, a taxon with curved cells, Hannaea baicalensis (37–96 µm), showed differences of ~ 4 µm between the two methods. Discrepancies appear to be influenced by the choice of feret or geodesic measurement for asymmetric cells. We describe the operating conditions necessary for analysis of size distributions and present suggestions for optimal instrument conditions for size analysis of diatom samples using the FlowCAM. The increased speed of data acquisition through use of imaging flow cytometers like the FlowCAM is an essential step for advancing studies of diatom populations.

  3. Soliton solutions in a diatomic lattice system

    International Nuclear Information System (INIS)

    Yajima, Nobuo; Satsuma, Junkichi.

    1979-04-01

    A continuum limit is considered for a diatomic lattice system with a cubic nonlinearity. A long wave equation describing the interaction of acoustic and optical modes is obtained. It reduces, in certain approximations, to equations having coupled wave solutions. The solutions exhibit trapping of an optical mode by an acoustic soliton. The form of the trapped optical wave depends on the mass ratio of adjacent particles in the diatomic lattice. (author)

  4. The toll of stalking: the relationship between features of stalking and psychopathology of victims.

    NARCIS (Netherlands)

    Blaauw, E.; Winkel, F.W.; Arensman, E.; Sheridan, L.; Freeve, A.

    2002-01-01

    Information on the psychological consequences of stalking on victims is scarce. The present study aimed to investigate whether stalking victims have a heightened prevalence of psychopathology and the extent to which symptom levels are associated with stalking features. Stalking victims (N = 241)

  5. Contribution to the discussion on the criminalization of stalking

    Directory of Open Access Journals (Sweden)

    Miladinović-Stefanović Dušica

    2016-01-01

    Full Text Available The serious and complex nature of stalking, as a social phenomenon, is reflected in diverse forms of this illicit act, the severity of consequences caused by its commission, and the likelihood of being turned into violence. Whereas it may be observed from different perspectives, in this paper stalking is examined from the aspect of substantive criminal law. In the first part of this article, the author provides an overview of legal provisions on the crime of stalking as envisaged in selected European legislations. In the second part of the paper, the author re-examines the capacity of the existing Serbian criminal legislation to respond to this problem, especially through the envisaged criminal offence of endangering safety of another. In conclusion, the author discusses the inadequacy of the existing legislation and the need for further legislative intervention in this area.

  6. Fouling diatom community with reference to substratum variability in tropical marine environment

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Desai, D.V.; Khandeparker, L.; Anil, A.C.; Wagh, A.B.

    form encountered. The paper deals with the qualitative and quantitative aspects of diatom colonization, their community structure, and correlation between the prevailing diatom population in the environment and that in the fouling community...

  7. Evaluation of cotton stalks destroyers

    OpenAIRE

    Bianchini, Aloisio; Borges, Pedro H. de M.

    2013-01-01

    The destruction of the cotton crop residues (cotton stalks) is a mandatory procedure in Brazil for prophylactic issues, but is a subject unexplored by the research and there are few studies that deal with this issue. However, this is not encouraged in recent decades, studies aimed at developing and evaluating equipment for this purpose. The present study had the objective to evaluate six methods for mechanical destruction of cotton crop residues. Each method was defined based on the principle...

  8. Transparent Exopolymeric Particles (TEP Selectively Increase Biogenic Silica Dissolution From Fossil Diatoms as Compared to Fresh Diatoms

    Directory of Open Access Journals (Sweden)

    Jordan Toullec

    2018-03-01

    Full Text Available Diatom production is mainly supported by the dissolution of biogenic silica (bSiO2 within the first 200 m of the water column. The upper oceanic layer is enriched in dissolved and/or colloidal organic matter, such as exopolymeric polysaccharides (EPS and transparent exopolymeric particles (TEP excreted by phytoplankton in large amounts, especially at the end of a bloom. In this study we explored for the first time the direct influence of TEP-enriched diatom excretions on bSiO2 dissolution. Twelve dissolution experiments on fresh and fossil diatom frustules were carried out on seawater containing different concentrations of TEP extracted from diatom cultures. Fresh diatom frustules were cleaned from the organic matter by low ash temperature, and fossil diatoms were made from diatomite powder. Results confirm that newly formed bSiO2 dissolved at a faster rate than fossil diatoms due to a lower aluminum (Al content. Diatom excretions have no effect on the dissolution of the newly formed bSiO2 from Chaetoceros muelleri. Reversely, the diatomite specific dissolution rate constant and solubility of the bSiO2 were positively correlated to TEP concentrations, suggesting that diatom excretion may provide an alternative source of dSi when limitations arise.

  9. Components of the Bond Energy in Polar Diatomic Molecules, Radicals, and Ions Formed by Group-1 and Group-2 Metal Atoms.

    Science.gov (United States)

    Yu, Haoyu; Truhlar, Donald G

    2015-07-14

    Although many transition metal complexes are known to have high multireference character, the multireference character of main-group closed-shell singlet diatomic molecules like BeF, CaO, and MgO has been less studied. However, many group-1 and group-2 diatomic molecules do have multireference character, and they provide informative systems for studying multireference character because they are simpler than transition metal compounds. The goal of the present work is to understand these multireference systems better so that, ultimately, we can apply what we learn to more complicated multireference systems and to the design of new exchange-correlation functionals for treating multireference systems more adequately. Fourteen main-group diatomic molecules and one triatomic molecule (including radicals, cations, and anions, as well as neutral closed-shell species) have been studied for this article. Eight of these molecules contain a group-1 element, and six contain a group-2 element. Seven of these molecules are multireference systems, and eight of them are single-reference systems. Fifty-three exchange-correlation functionals of 11 types [local spin-density approximation (LSDA), generalized gradient approximation (GGA), nonseparable gradient approximation (NGA), global-hybrid GGA, meta-GGA, meta-NGA, global-hybrid meta GGA, range-separated hybrid GGA, range-separated hybrid meta-GGA, range-separated hybrid meta-NGA, and DFT augmented with molecular mechanics damped dispersion (DFT-D)] and the Hartree-Fock method have been applied to calculate the bond distance, bond dissociation energy (BDE), and dipole moment of these molecules. All of the calculations are converged to a stable solution by allowing the symmetry of the Slater determinant to be broken. A reliable functional should not only predict an accurate BDE but also predict accurate components of the BDE, so each bond dissociation energy has been decomposed into ionization potential (IP) of the electropositive

  10. Stalking: Notion, characteristics and social responses

    Directory of Open Access Journals (Sweden)

    Nikolić-Ristanović Vesna

    2007-01-01

    Full Text Available In the last two decades stalking phenomenon is recognized and actualized in the world in professional, scientific circles, in media and the everyday talk. Recently, stalking is identified as specific and complex problem studied separately from domestic violence, workplace abuse, sexual harassment, threats, following, homicide, voyeurism and the other phenomenon to which stalking may or not be related. This paper is aimed to determine the notion of stalking and its relationship with similar phenomena, to review the research about the prevalence and nature of stalking, as well as to review the measures for its prevention, supporting victims and prosecution of offenders. Finally, the paper intend to contribute toward initiation of research and legal reforms regarding stalking victimisation in Serbia.

  11. The Fear Factor: Exploring Predictors of Fear among Stalking Victims throughout the Stalking Encounter

    Science.gov (United States)

    Reyns, Bradford W.; Englebrecht, Christine M.

    2013-01-01

    The crime of stalking has received much research attention, yet there are still important questions to be explored surrounding this behavior. One such question relates to definitions of stalking, including the requirement that victims must express fear to qualify as victims of stalking. The current study addresses this issue by exploring the…

  12. Comparative pulping of sunflower stalks

    Directory of Open Access Journals (Sweden)

    Valerii Barbash

    2016-03-01

    Full Text Available The procedure of holocellulose content determination in non-wood plant raw materials was developed. The strength properties of pulp obtained from sunflower stalks by neutral-sulphite, soda, alkaline sulphite-anthraquinone-ethanol and peracetic methods of delignification were studied. Methodology of comparison of plant materials delignification methods using new lignin-carbohydrate diagram was proposed. It was shown, that the alkaline sulphite-anthraquinone-ethanol method of pulping is characterized by the highest delignification degree and is the most efficient among the studied methods

  13. Utilization of enzyme supplemented Telfairia occidentalis stalk ...

    African Journals Online (AJOL)

    An eight (8) week feeding trial was carried out to assess the use of enzyme natuzyme supplemented Telfairia occidentalis stalk extract as growth inducer in the practical diet for Oreochromis niloticus fingerlings. Five isonitrogenous (35% crude protein) diets at 0 ml of stalk extract and enzyme (TRT 1), 15 ml (TRT 2) and 30 ...

  14. Coherent control of atoms and diatomic molecules with shaped ultrashort pulses; Manipulation coherente d'atomes et de molecules diatomiques avec des impulsions mises en forme

    Energy Technology Data Exchange (ETDEWEB)

    Degert, J

    2002-12-15

    This thesis deals with the theoretical and experimental study of coherent control of atomic and molecular systems with shaped pulses. At first, we present several experiments of control of coherent transients in rubidium. These transients appear when a two-level system is excited by a perturbative chirped pulse, and are characterized by oscillations in the excited state population. For a strong chirp, we show that a phase step in the spectrum modifies the phase of the oscillations. Then, by direct analogy with Fresnel zone lens, we conceive a chirped pulse with a highly modulated amplitude, allowing to suppress destructive contributions to the population transfer. In a second set of experiments, we focus on quantum path interferences in two-photon transitions excited by linearly chirped pulses. Owing to the broad bandwidth of ultrashort pulses, sequential and direct excitation paths contribute to the excited state population. Oscillations resulting from interferences between these two paths are observed in atomic sodium. Moreover, we show that they are observable whatever the sign of chirp. Theoretically, we study the control of the predissociation of a benchmark diatomic molecule: NaI. Predissociation leads to matter wave interferences in the fragments distribution. First, we show that a suitably chosen probe pulse allows the observation of theses interferences. Next, using a sequence of control pulse inducing electronic transition, we demonstrate the possibility to manipulate fragment energy distribution. (author)

  15. Stalking

    Science.gov (United States)

    ... Crime, Teens, and Trauma Assault Bullying and Harassment Child Sexual Abuse Dating Violence Sexual Assault Robbery and Property Crime ... and Victimization in the News Media Reporting on Child Sexual Abuse Reporting Do's and Don'ts Sandusky Criminal Trial & ...

  16. Lithotrophic iron-oxidizing bacteria produce organic stalks to control mineral growth: implications for biosignature formation

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Clara S; Fakra, Sirine C; Emerson, David; Fleming, Emily J; Edwards, Katrina J

    2011-07-01

    Neutrophilic Fe-oxidizing bacteria (FeOB) are often identified by their distinctive morphologies, such as the extracellular twisted ribbon-like stalks formed by Gallionella ferruginea or Mariprofundus ferrooxydans. Similar filaments preserved in silica are often identified as FeOB fossils in rocks. Although it is assumed that twisted iron stalks are indicative of FeOB, the stalk's metabolic role has not been established. To this end, we studied the marine FeOB M. ferrooxydans by light, X-ray and electron microscopy. Using time-lapse light microscopy, we observed cells excreting stalks during growth (averaging 2.2 {micro}m h(-1)). Scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy show that stalks are Fe(III)-rich, whereas cells are low in Fe. Transmission electron microscopy reveals that stalks are composed of several fibrils, which contain few-nanometer-sized iron oxyhydroxide crystals. Lepidocrocite crystals that nucleated on the fibril surface are much larger ({approx}100 nm), suggesting that mineral growth within fibrils is retarded, relative to sites surrounding fibrils. C and N 1s NEXAFS spectroscopy and fluorescence probing show that stalks primarily contain carboxyl-rich polysaccharides. On the basis of these results, we suggest a physiological model for Fe oxidation in which cells excrete oxidized Fe bound to organic polymers. These organic molecules retard mineral growth, preventing cell encrustation. This model describes an essential role for stalk formation in FeOB growth. We suggest that stalk-like morphologies observed in modern and ancient samples may be correlated confidently with the Fe-oxidizing metabolism as a robust biosignature.

  17. Influence of diatom diversity on the ocean biological carbon pump

    Science.gov (United States)

    Tréguer, Paul; Bowler, Chris; Moriceau, Brivaela; Dutkiewicz, Stephanie; Gehlen, Marion; Aumont, Olivier; Bittner, Lucie; Dugdale, Richard; Finkel, Zoe; Iudicone, Daniele; Jahn, Oliver; Guidi, Lionel; Lasbleiz, Marine; Leblanc, Karine; Levy, Marina; Pondaven, Philippe

    2018-01-01

    Diatoms sustain the marine food web and contribute to the export of carbon from the surface ocean to depth. They account for about 40% of marine primary productivity and particulate carbon exported to depth as part of the biological pump. Diatoms have long been known to be abundant in turbulent, nutrient-rich waters, but observations and simulations indicate that they are dominant also in meso- and submesoscale structures such as fronts and filaments, and in the deep chlorophyll maximum. Diatoms vary widely in size, morphology and elemental composition, all of which control the quality, quantity and sinking speed of biogenic matter to depth. In particular, their silica shells provide ballast to marine snow and faecal pellets, and can help transport carbon to both the mesopelagic layer and deep ocean. Herein we show that the extent to which diatoms contribute to the export of carbon varies by diatom type, with carbon transfer modulated by the Si/C ratio of diatom cells, the thickness of the shells and their life strategies; for instance, the tendency to form aggregates or resting spores. Model simulations project a decline in the contribution of diatoms to primary production everywhere outside of the Southern Ocean. We argue that we need to understand changes in diatom diversity, life cycle and plankton interactions in a warmer and more acidic ocean in much more detail to fully assess any changes in their contribution to the biological pump.

  18. Environmental investigations using diatom microfossils

    Science.gov (United States)

    Smith, Kathryn E.L.; Flocks, James G.

    2010-01-01

    Diatoms are unicellular phytoplankton (microscopic plant-like organisms) with cell walls made of silica (called a frustule). They live in both freshwater and saltwater and can be found in just about every place on Earth that is wet. The shape and morphology of the diatom frustule unique to each species are used for identification. Due to the microscopic size of diatoms, high-power microscopy is required for diatom identification. Diatoms are vital to life on Earth. They are photosynthetic primary producers, using sunlight to create oxygen and organic carbon from carbon dioxide and water. They are a significant source of the oxygen we breathe, have a major impact on the global carbon cycle (Smetacek, 1999), and are a food source for many aquatic organisms (Mann, 1993). Diatom abundance has even been demonstrated to have an influence on the diversity of larger marine mammals, including whales (Marx and Uhen, 2010). Data on diatom abundance and diversity are extremely useful in environmental studies.

  19. CHARACTERISTICS OF CORN STALK HEMICELLULOSE PYROLYSIS IN A TUBULAR REACTOR

    OpenAIRE

    Gao-Jin Lv; Shu-Bin Wu; Rui Lou

    2010-01-01

    Pyrolysis characteristics of corn stalk hemicellulose were investigated in a tubular reactor at different temperatures, with focus mainly on the releasing profiles and forming behaviors of pyrolysis products (gas, char, and tar). The products obtained were further identified using various approaches (including GC, SEM, and GC-MS) to understand the influence of temperature on product properties and compositions. It was found that the devolatilization of hemicellulose mainly occurred at low tem...

  20. Abundance of bacterial and diatom fouling on various surfaces

    Digital Repository Service at National Institute of Oceanography (India)

    PrabhaDevi

    Abundance of bacterial and diatom fouling on aluminium, fibreglass and stainless steel were studied from Dona Paula waters of the Zuari Estuary. Both these forms were reversibly attached in large numbers to surfaces during the initial 24 hr...

  1. Bioethanol production from dried sweet sorghum stalk

    Energy Technology Data Exchange (ETDEWEB)

    Almodares, A.; Etemadifar, Z.; Ghoreishi, F.; Yosefi, F. [Biology Dept. Univ. of Isfahan, Isfahan (Iran, Islamic Republic of)], e-mail: aalmodares@yahoo.com

    2012-11-01

    Bioethanol as a renewable transportation fuel has a great potential for energy and clean environment. Among crops sweet sorghum is one of the best feedstock for ethanol production under hot and dry climatic conditions. Because it has higher tolerance to salt and drought comparing to sugarcane and corn that are currently used for bio-fuel production in the world. Generally mills are used to extract the juice from sweet sorghum stalks. Three roller mills extract around nearly 50 percent of the juice and more mills is needed to extract higher percentage of the juice. More over under cold weather the stalks become dry and juice is not extracted from the stalk, therefore reduce harvesting period. In this study stalks were harvested, leaves were stripped from the stalks and the stalks were chopped to nearly 4 mm length and sun dried. The dry stalks were grounded to 60 mesh powder by a mill. Fermentation medium consists of 15-35% (w/w) sweet sorghum powder, micronutrients and active yeast inoculum from 0.5-1% (w/w) by submerge fermentation method. The fermentation time and temperature were 48-72 hours and 30 deg, respectively. The results showed the highest amount of ethanol (14.5 % w/w sorghum) was produced with 10% sweet sorghum powder and 1% of yeast inoculum, three day fermentation at 30 deg.

  2. Body Stalk Syndrome: A Curiosity

    Directory of Open Access Journals (Sweden)

    Anita Javalgi

    2014-07-01

    Full Text Available Limb body wall complex (LBWC /Body stalk syndrome anomaly refers to a rare complicated polymalformative fetal malformation syndrome of uncertain etiology firstly described by Van Allen et al in 1987. There are very few cases reported in literature and thus we report a rare case of LBWC. Twenty seven years female presented to labour room with 32 weeks of gestation with no prenatal care and delivered a low birth weight still born fetus weighing 1100gms. On fetal autopsy large abdominal wall defect was noted with difficulty in identifying abdomino-pelvic organs and ambiguous genitalia. Placenta weighed 250gms with attached short umbilical cord measuring 7cms, arising from periphery. A cyst noted attached to placental membrane measuring 9x5cms which on dissection retrieved partially maldeveloped organs. Post mortem radiological findings included Absence of right femur with short tibia and right fibula, Complex vestibral malformation, Craniosynostosis and Overcrowding of ribs.

  3. The consequences of coping with stalking

    DEFF Research Database (Denmark)

    Johansen, Katrine Bindesbøl Holm; Tjørnhøj-Thomsen, Tine

    2016-01-01

    OBJECTIVES: The purpose of this article is to explore: (1) how victims of stalking experience the phenomenon in their daily life, (2) how the nature of stalking informs the victim's internal coping strategies, and (3) how the victims' internal coping strategies negatively affect their daily life...... and well-being. METHODS: Qualitative semi-structured interviews were conducted with 25 victims of stalking. Thematic content analysis was employed, and themes were primarily identified inductively and broad into dialogue with concepts, such as Foucault's panopticism. RESULTS: The results of the study...

  4. Aggregate Formation During the Viral Lysis of a Marine Diatom

    Directory of Open Access Journals (Sweden)

    Yosuke Yamada

    2018-05-01

    Full Text Available Recent studies have suggested that the viral lysis of microbes not only facilitates the conversion of particulate organic matter into dissolved organic matter, but also promotes the formation of organic aggregates, which enhance the export of organic carbon from the surface ocean to the deep sea. However, experimental data supporting this proposition are limited. Here, we tested the hypothesis that the viral infection of marine diatoms enhances aggregate formation. We used a model system consisting of Chaetoceros tenuissimus, a bloom-forming diatom with an approximate cell size of 3–10 μm, and a DNA virus, CtenDNAV type II, which replicates in the nucleus of C. tenuissimus. The volume of large particles (50–400 μm in equivalent spherical diameters, determined from photographic images was measured over time (up to 15 days in the diatom-alone control and a virus-added diatom culture. We also determined the concentrations of Coomassie-stainable particles (CSP, proteinaceous particles and transparent exopolymeric particles (TEP, acid-polysaccharide-rich particles with colorimetric methods. The total volume of large particles was significantly higher (5–59 fold in the virus-added diatoms than in the diatom-alone control during the period in which the viral lysis of the diatoms proceeded. One class of large particles produced in the virus-added diatoms was flake-shaped. The flakes were tightly packed and dense, and sank rapidly, possibly playing an important role in the vertical delivery of materials from the surface to the deep sea. The bulk CSP concentrations tended to be higher in the virus-added diatoms than in the diatom-alone control, whereas the reverse was true for the TEP. These results suggest that proteinaceous polymers are involved in aggregate formation. Our data support the emerging notion that the viral lysis of microbes facilitates aggregate formation and the export of organic carbon in the ocean.

  5. Doping of magnetite nanoparticles facilitates clean harvesting of diatom oil as biofuel for sustainable energy

    Science.gov (United States)

    Kumar, Vikas; Singh, Ramesh; Thakur, Shipra; Ballabh Joshi, Khashti; Vinayak, Vandana

    2018-04-01

    Photosynthetic unicellular brown algae diatoms are considered as photobioreactors (PBRs) that synthesize and store oil in the form of lipid droplets and the much of the crude oil we use comes from fossil diatoms. The clean extraction of this crude oil from diatoms is difficult task. The construction of green chemical protocols for the clean separation of diatom oil from cells without killing or to harm the diatom cells is still in its primitive stage. In this report we would like to propose that facile doping of magnetite on diatoms can be used for clean oil separation in PBRs. We doped magnetite nanoparticles onto the surface of diatom Diadesmis confervaceae a diatom which oozes oil naturally. Doping magnetite onto diatoms can also facilitate easy separation of oil when cells are kept in an electromagnetic field. The cell wall of diatom besides having SiOH group has 281 amino acids of which 187–188 amino acids are conserved and are known for metal binding sites. The magnetite nanoparticles bind to the SiOH groups and metal binding sites of amino acids. The presence of appropriate amine functionalized linkers forming peptide aminosilane shells can further facilitate the binding of peptide/polypeptides which can be used in drug delivery. Besides this the magnetite doped diatoms have wide applications in removal of phosphates and chromium from waste water too.

  6. Photosynthetic Pigments in Diatoms

    OpenAIRE

    Kuczynska, Paulina; Jemiola-Rzeminska, Malgorzata; Strzalka, Kazimierz

    2015-01-01

    Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvestin...

  7. Photosynthetic Pigments in Diatoms.

    Science.gov (United States)

    Kuczynska, Paulina; Jemiola-Rzeminska, Malgorzata; Strzalka, Kazimierz

    2015-09-16

    Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvesting pigments such as chlorophyll a, chlorophyll c, and fucoxanthin, there is a group of photoprotective carotenoids which includes β-carotene and the xanthophylls, diatoxanthin, diadinoxanthin, violaxanthin, antheraxanthin, and zeaxanthin, which are engaged in the xanthophyll cycle. Additionally, some intermediate products of biosynthetic pathways have been identified in diatoms as well as unusual pigments, e.g., marennine. Marine algae have become widely recognized as a source of unique bioactive compounds for potential industrial, pharmaceutical, and medical applications. In this review, we summarize current knowledge on diatom photosynthetic pigments complemented by some new insights regarding their physico-chemical properties, biological role, and biosynthetic pathways, as well as the regulation of pigment level in the cell, methods of purification, and significance in industries.

  8. Photosynthetic Pigments in Diatoms

    Directory of Open Access Journals (Sweden)

    Paulina Kuczynska

    2015-09-01

    Full Text Available Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvesting pigments such as chlorophyll a, chlorophyll c, and fucoxanthin, there is a group of photoprotective carotenoids which includes β-carotene and the xanthophylls, diatoxanthin, diadinoxanthin, violaxanthin, antheraxanthin, and zeaxanthin, which are engaged in the xanthophyll cycle. Additionally, some intermediate products of biosynthetic pathways have been identified in diatoms as well as unusual pigments, e.g., marennine. Marine algae have become widely recognized as a source of unique bioactive compounds for potential industrial, pharmaceutical, and medical applications. In this review, we summarize current knowledge on diatom photosynthetic pigments complemented by some new insights regarding their physico-chemical properties, biological role, and biosynthetic pathways, as well as the regulation of pigment level in the cell, methods of purification, and significance in industries.

  9. Identification of metastases in the pituitary stalk

    Energy Technology Data Exchange (ETDEWEB)

    Schubiger, O

    1982-09-01

    Two cases of metastasis in the pituitary stalk are presented. In both cases, presenting with diabetes insipidus, the demonstration of a small (under 1 cm) metastasis in the pituitary stalk was possible using a current generation scanner. Patients with known primary tumors presenting with a diabetes insipidus should be examined by CT before therapy with antidiuretic hormone is initiated. In cases of visible metastasis, a specific therapy together with the hormone-substitution should be discussed.

  10. [Nurses' experiences of stalking: a narrative review].

    Science.gov (United States)

    Comparcini, Dania; Simonetti, Valentina; Lupo, Roberto; Cicolini, Giancarlo

    2015-01-01

    This narrative review aimed to synthetize the results of the main studies analysing nurses' experience of stalking in different clinical settings. We searched the electronic databases MEDLINE (through PubMed), CINAHL (through EBSCOhost) and the search engine "Google Scholar". Searches were limited to articles published in English and Italian, and published between 1999 and 2013. Stalking refers to a behavioural pattern characterized by persistent unwanted communications and contacts imposed to another person, which, consequently suffer from distress, fear, and anxiety. Several studies explored the risk of stalking in healthcare system, especially in doctors and psychiatrists. Some authors analysed nurses' experience of stalking with particular attention to mental health professionals as a group category with an increased risk of stalking by patients. Results of some studies carried out in different clinical settings (medical and surgical areas, and other healthcare settings) also revealed, even if in a minority, the presence of this phenomenon, showing the presence of staking's behaviours by patients and healthcare colleagues too. However, more researches with large sample size are needed to better understand the phenomenon of stalking in nurses working in different clinical areas.

  11. Controlling the invasive diatom Didymosphenia geminata: an ecotoxicity assessment of four potential biocides.

    Science.gov (United States)

    Jellyman, P G; Clearwater, S J; Clayton, J S; Kilroy, C; Blair, N; Hickey, C W; Biggs, B J F

    2011-07-01

    In 2004, an invasive mat-forming freshwater diatom, Didymosphenia geminata (didymo), was found in New Zealand causing concern with regard to potential consequences for local freshwater ecosystems. A four-stage research program was initiated to identify methods to control D. geminata. This article reports the results of Stage 2, in which four potential control compounds [Gemex™ (a chelated copper formulation), EDTA, Hydrothol®191, and Organic Interceptor™ (a pine oil formulation)] selected in Stage 1 were evaluated for their biocidal efficacy on D. geminata and effects on non-target organisms using both artificial stream and laboratory trials. Artificial stream trials evaluated the mortality rates of D. geminata and fishes to three concentrations of the four biocides, whereas laboratory toxicity trials tested the response of green alga and cladocera to a range of biocide concentrations and exposure times. In artificial stream trials, Gemex and Organic Interceptor were the most effective biocides against D. geminata for a number of measured indices; however, exposure of fishes to Organic Interceptor resulted in high mortality rates. Laboratory toxicity testing indicated that Gemex might negatively affect sensitive stream invertebrates, based on the cladoceran sensitivity at the proposed river control dose. A decision support matrix evaluated the four biocides based on nine criteria stipulated by river stakeholders (effectiveness, non-target species impacts, stalk removal, degradation profile, risks to health and safety, ease of application, neutralization potential, cost, and local regulatory requirements) and Gemex was identified as the product warranting further refinement prior to an in-river trial.

  12. Diatomic Metasurface for Vectorial Holography.

    Science.gov (United States)

    Deng, Zi-Lan; Deng, Junhong; Zhuang, Xin; Wang, Shuai; Li, Kingfai; Wang, Yao; Chi, Yihui; Ye, Xuan; Xu, Jian; Wang, Guo Ping; Zhao, Rongkuo; Wang, Xiaolei; Cao, Yaoyu; Cheng, Xing; Li, Guixin; Li, Xiangping

    2018-05-09

    The emerging metasurfaces with the exceptional capability of manipulating an arbitrary wavefront have revived the holography with unprecedented prospects. However, most of the reported metaholograms suffer from limited polarization controls for a restrained bandwidth in addition to their complicated meta-atom designs with spatially variant dimensions. Here, we demonstrate a new concept of vectorial holography based on diatomic metasurfaces consisting of metamolecules formed by two orthogonal meta-atoms. On the basis of a simply linear relationship between phase and polarization modulations with displacements and orientations of identical meta-atoms, active diffraction of multiple polarization states and reconstruction of holographic images are simultaneously achieved, which is robust against both incident angles and wavelengths. Leveraging this appealing feature, broadband vectorial holographic images with spatially varying polarization states and dual-way polarization switching functionalities have been demonstrated, suggesting a new route to achromatic diffractive elements, polarization optics, and ultrasecure anticounterfeiting.

  13. Pituitary gland and its stalk observed by high resolution CT

    International Nuclear Information System (INIS)

    Nakagawa, Yoshinobu; Fukami, Tsuneharu; Matsumoto, Keizo.

    1982-01-01

    It seemed to be important to recognize the CT findings of normal pituitary gland and the stalk for the acurate morphological diagnosis of pituitary microadenoma. In a consecutive series of normal 103 cases, the CT scans obtained by high resolution CT (CE-CT, Metrizamide CT) were analized and compared with 6 cases of microadenoma. The pituitary stalk demonstrated by the reconstructed coronal CT was examined and the inclination of the stalk was measured. The mean value of the inclination of pituitary stalk was 1.4 +- 1.7 0 in normal group and 9.3 +- 2.4 0 in microadenoma group. The form of the pituitary gland demonstrated by a reconstructed mid-saggital CT were classified into the following 3 types. Type I : The gland filling the whole pituitary fossa. Type II : The gland filled with small CSF space localized in the upper-anterior part in the pituitary fossa. Type III : The enlarged CSF space of more than half of the depth of pituitary fossa and the gland localized in the retro-lower part. As for the shape of pituitary gland, type I was revealed in 26 cases (7 cases in male and 19 cases in female), Type II was revealed in 31 cases (12 cases in male and 19 cases in female), Type III was revealed in 46 cases (25 cases in male and 21 cases in female). Type I was shown in female, especially in 10 years old young female. In 19 cases of 30 years to 40 years female, Type II was shown in 9 cases. In 44 male cases, Type I and Type II were shown in all ages. In the aged, Type III was shown in more than the other types. On the other hand, Type I was noted in 5 out of 6 cases of microadenoma group. (author)

  14. Diatomic gasdynamic lasers.

    Science.gov (United States)

    Mckenzie, R. L.

    1972-01-01

    Predictions from a numerical model of the vibrational relaxation of anharmonic diatomic oscillators in supersonic expansions are used to show the extent to which the small anharmonicity of gases like CO can cause significant overpopulations of upper vibrational states. When mixtures of CO and N2 are considered, radiative gain on many of the vibration-rotation transitions of CO is predicted. Experiments are described that qualitatively verify the predictions by demonstrating laser oscillation in CO-N2 expansions. The resulting CO-N2 gasdynamic laser displays performance characteristics that equal or exceed those of similar CO2 lasers.

  15. Diatomic gasdynamic lasers

    International Nuclear Information System (INIS)

    McKenzie, R.L.

    1971-12-01

    Predictions from a numerical model of the vibrational relaxation of anharmonic diatomic oscillators in supersonic expansions are used to show the extent to which the small anharmonicity of gases like CO can cause significant over-populations of upper vibrational states. When mixtures of CO and N 2 are considered, radiative gain on many of the vibration-rotation transitions of CO is predicted. Experiments are described that qualitatively verify the predictions by demonstrating laser oscillation in CO-N 2 expansions. The resulting CO-N 2 gasdynamic laser displays performance characteristics that equal or exceed those of similar CO 2 lasers

  16. Controlling dynamics in diatomic systems

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. Controlling molecular energetics using laser pulses is exemplified for nuclear motion in two different diatomic systems. The problem of finding the optimized field for maximizing a desired quantum dynamical target is formulated using an iterative method. The method is applied for two diatomic sys- tems, HF and OH.

  17. Diatoms - nature materials with great potential for bioapplications

    Directory of Open Access Journals (Sweden)

    Medarević Đorđe P.

    2016-01-01

    Full Text Available Diatoms are widespread unicellular photosynthetic algae that produce unique highly ordered siliceous cell wall, called frustule. Micro- to nanoporous structure with high surface area that can be easily modified, high mechanical resistance, unique optical features (light focusing and luminescence and biocompatibility make diatom frustule as a suitable raw material for the development of devices such as bio- and gas sensors, microfluidic particle sorting devices, supercapacitors, batteries, solar cells, electroluminescent devices and drug delivery systems. Their wide availability in the form of fossil remains (diatomite or diatomaceous earth as well as easy cultivation in the artificial conditions further supports use of diatoms in many different fields of application. This review focused on the recent achievements in the diatom bioapplications such as drug delivery, biomolecules immobilization, bio- and gas sensing, since great progress was made in this field over the last several years.

  18. [Stalking: From "romantic pursuit" to sexual predation].

    Science.gov (United States)

    Cailleau, Virginie; Harika-Germaneau, Ghina; Delbreil, Alexia; Jaafari, Nematollah

    2018-06-01

    Deriving from the English verb "to stalk", stalking denotes an unwelcome, repetitive, and intrusive harassing and/or threatening behavior directed toward a specific individual, and can result in physical and/or sexual offending - even leading to homicide. French harassment legislation has evolved over the years, and the last law closest to the international anti-stalking laws had been promulgated in 2014. According to a review, up to 16% of women and 7% of men are stalked in their life, and 80% of the stalkers are known to their victims. Stalkers are a heterogeneous population, either seeking an intimate relationship with someone the stalker knows or with a celebrity, or being revenge-motivated, or tracking their victims with the aim of offending them. Stalkers threat their victims in about half of the cases, and physically offend them in a third of the cases, violence being more often directed against ex-intimates. Sexual offending would be the consequence of harassment behavior for some stalkers, and would be the initial aim of the stalking for others. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  19. Stalking Behavior and the Cycle of Domestic Violence.

    Science.gov (United States)

    Coleman, Frances L.

    1997-01-01

    Refines the behavioral definition of stalking, investigates the role stalking plays in domestic violence, and develops demographic profiles of stalkers and their victims. Results based on information taken from 141 college women show that subjects who reported significantly more abuse during relationships were more likely to be stalked by former…

  20. Thermal Stress Analysis for Ceramics Stalk in the Low Pressure Die Casting Machine

    Science.gov (United States)

    Noda, Nao-Aki; Hendra, Nao-Aki; Takase, Yasushi; Li, Wenbin

    Low pressure die casting (LPDC) is defined as a net shape casting technology in which the molten metal is injected at high speeds and pressure into a metallic die. The LPDC process is playing an increasingly important role in the foundry industry as a low-cost and high-efficiency precision forming technique. The LPDC process is that the permanent die and filling systems are placed over the furnace containing the molten alloy. The filling of the cavity is obtained by forcing the molten metal by means of a pressurized gas in order to rise into a ceramic tube, which connects the die to the furnace. The ceramics tube called stalk has high temperature resistance and high corrosion resistance. However, attention should be paid to the thermal stress when the stalk is dipped into the molten aluminum. It is important to develop the design of the stalk to reduce the risk of fracture because of low fracture toughness of ceramics. In this paper, therefore, the finite element method is applied to calculate the thermal stresses when the stalk is dipped into the crucible by varying the dipping speeds and dipping directions. It is found that the thermal stress can be reduced by dipping slowly if the stalk is dipped into the crucible vertically, while the thermal stress can be reduced by dipping fast if it is dipped horizontally.

  1. STALKED BARNACLES CONCHODERMA AURITUM ON AN ...

    African Journals Online (AJOL)

    lower jaw, the palate and the penis of the sperm whale - Carke 1966). The occurrence of. C. auritum on the body skin of an elephant seal is therefore ... It can be inferred from Sorensen's remark that "barnacles up to an inch in length have been seen ... " that a stalked barnacle was involved, and Laws indeed refers to those.

  2. Vulture worries stalk activists on Uttarayan

    African Journals Online (AJOL)

    2007-03-01

    Mar 1, 2007 ... Vulture worries stalk activists on Uttarayan. Anon. Ahmedabad – When kites take to the skies on Uttarayan, animal activists will be biting their nails in apprehension. Their main concern is the White-rumped. Vulture, a highly endangered species, of which only 137 birds are left in the city, according to figures ...

  3. Enkele kanttekeningen bij de strafbaarstelling van stalking

    NARCIS (Netherlands)

    van Klink, B.M.J.; Royakkers, L.M.M.

    1998-01-01

    In dit artikel gaan wij nader in op het fenomeen stalking in het algemeen en het wetsvoorstel dienaangaande in het bijzonder. §2 biedt een conceptuele analyse van het begrip ¿belaging', dat door ons wordt opgevat als een vorm van geestelijke mishandeling. Beseft dient te worden dat het hierbij niet

  4. Bioactive glass 45S5 from diatom biosilica

    Directory of Open Access Journals (Sweden)

    Luqman A. Adams

    2017-12-01

    Full Text Available A major draw-back to large scale production of bioactive glasses is the high cost of the standard silica precursor, usually tetraethyl orthosilicate (TEOS. The current study describes a novel sol–gel preparation of 45S5 bioactive glass using diatom biosilica from cultured cells of the diatom, Aulacoseira granulata as substitute to TEOS. The glass formed was characterized using mechanical tester, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDX, X-ray diffraction (XRD and Fourier transform infrared (FTIR spectroscopy. Results showed that the glass possessed a compressive strength of 3.75 ± 0.18 and formed carbonated hydroxyapatite (HCA within 7 days in simulated body fluid (SBF, attributable to good surface chemistry. The performance of the glass was compared with that of those formed using TEOS. Diatom biosilica could be a potential economically friendly starting material for large scale fabrication of bioactive glasses.

  5. Entre les violences conjugales et le harcèlement moral : le stalking .

    Directory of Open Access Journals (Sweden)

    Nicolas Desurmont

    2007-09-01

    Full Text Available Ce livre de la criminologue Murielle Anteo est le premier publié en langue française sur le stalking si l’on excepte les travaux encore inédits de Virginie Léon (2004. Comme le rappelle l’auteure, le terme est emprunté à l’anglais to stalk (hanter, rôder, et désigne un comportement menaçant, initié par un individu dont l’objectif conscient ou inconscient est l’objectivation de sa victime à des fins de domination. L’agression prend différentes formes : ...

  6. Towards a representative periphytic diatom sample

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The need to acquire a representative periphytic diatom sample for river water quality monitoring has been recognised in the development of existing diatom indices, important in the development and employment of diatom monitoring tools for the Water Framework Directive. In this study, a nested design with replication is employed to investigate the magnitude of variation in diatom biomass, composition and Trophic Diatom Index at varying scales within a small chalk river. The study shows that the use of artificial substrates may not result in diatom communities that are typical of the surrounding natural substrates. Periphytic diatom biomass and composition varies between artificial and natural substrates, riffles and glides and between two stretches of the river channel. The study also highlights the existence of high variation in diatom frustule frequency and biovolume at the individual replicate scale which may have implications for the use of diatoms in routine monitoring.

  7. Adaptive significance of phytoplankton stickiness with emphasis on the diatom Skeletonema costatum

    DEFF Research Database (Denmark)

    Hansen, J.L.S.; Timm, U.; Kiørboe, Thomas

    1995-01-01

    Diatom aggregate formation was analyzed using coagulation theory. Population dynamics models show that coagulation has an important impact on species succession during diatom blooms. When different species collide and form mixed aggregates this process causes interspecific interference competitio...... was tested on field data, and the predicted dynamics of a spring bloom was very similar to that observed...

  8. Increase in nuisance blooms and geographic expansion of the freshwater diatom Didymosphenia geminata

    Science.gov (United States)

    Spaulding, S.A.; Elwell, E.

    2007-01-01

    The diatom Didymosphenia geminata (Lyngbye) Schmidt is emerging as an organism with an extraordinary capacity to impact stream ecosystems on a global scale. In recent years, streams in New Zealand, North America, Europe, and Asia have been colonized by unprecedented masses of “didymo” and its extracellular stalks (fig. 1). This diatom is able to dominate stream surfaces by covering up to 100 percent of substrate with thicknesses of greater than 20 cm, greatly altering physical and biological conditions within streams. This species is expanding its geographic range in North America and the rate that nuisance blooms are reported by the public and local media are increasing, yet little scientific investigation of the phenomenon in North America has been initiated.

  9. Transformation techniques for metabolic engineering of diatoms and haptophytes: current state and prospects.

    Science.gov (United States)

    Velmurugan, Natarajan; Deka, Deepi

    2018-05-01

    Diatoms and haptophytes represent a key segment of the dominant phytoplankton communities that frequently form massive blooms in the photic zone of the ocean and are considered indicators of global climate changes. Diatoms and haptophytes also play a vital role in the biological carbon fixation in the carbon cycles. Carbon partitioning within diatoms and haptophytes possesses a wide range of chemical compounds and storage materials, such as lipids, carbohydrates, and chlorophyll. Among the marine microorganisms, diatoms and haptophytes have been recognized as promising sources of long- and very long-chain polyunsaturated fatty acids (PUFA). So far, a variety of approaches have been employed for genetic modification in the nuclei of diatoms and haptophytes. Studies on transformation and metabolic engineering in various intracellular genomes, such as chloroplast and mitochondria, are scarce. Particle bombardment, Agrobacterium and PEG-mediated gene transfer, and electroporation have been reported for foreign gene transformation into the diatoms and haptophytes. Antibiotics (G418 and chloramphenicol) and herbicides (zeocin, hygromycin, and norflurazon) have been successfully demonstrated as the best selection markers. Despite the availability of a wide range of molecular tools for foreign gene expression in microalgae, very few promoters (lhcf1, nr, h4, ef2, fcp, and pds) have been reported for diatoms and haptophytes. Therefore, in this review, we first summarize the significant progress that has been achieved in transgene expression in diatoms and haptophytes and highlight the importance and availability of recently developed novel tools that are suitable for transgenic expression in diatoms and haptophytes.

  10. The effect of Cerasus avium stalk extract on albumin glycation reaction

    Directory of Open Access Journals (Sweden)

    Mohadeseh Abdoli

    2014-10-01

    Full Text Available Background: Non-enzymatic glycosylation of proteins is the major cause of diabetic complications. The inhibition of glycation process can reduce complications of diabetes. In the Iranian traditional medicine, the decoction (boiled extraction of Cerasus avium stalk is used as a hypoglycemic agent. The aim of this study was to investigate the in vitro inhibitory effects of decoction and ethanolic and aqueous extracts of Cerasus avium stalk on albumin glycation reaction. Methods: In this experimental study, first, the ethanolic, aqueous and decoction extracts of Cerasus avium stalk were prepared. Then, different concentrations of these extracts were prepared and added to albumin and glucose solutions. Finally, compared to control group that was not treated with any extracts, the albumin glycation rate in the groups treated with various concentrations of extracts was evaluated using TBA (thio-barbituric acid method. Results: The results showed that compared to control group, decoction of Cerasus avium stalk in the concentrations of 20, 10 and 2 mg/dl could reduce albumin glycation to 85.10±1.55, 72.35±1.75 and 51.25±1.22 %, respectively (P>0.001. Moreover, in the concentration of 20 mg/dl, the inhibitory effect of decoction of Cerasus avium stalk on the albumin glycation reaction was higher than those of aqueous (P=0.021 and ethanolic (P=0.009 extracts. Conclusion: The findings showed that the extracs of Cerasus avium stalk, in particular in the decoction form, could significantly reduce the rate of albumin glycation; therefore, it can be used for decreasing diabetes mellitus complications.

  11. Stalking: A Multidimensional Framework for Assessment and Safety Planning.

    Science.gov (United States)

    Logan, T K; Walker, Robert

    2015-09-03

    Despite the high prevalence of stalking and the risk of harm it poses to victims, arrest rates, prosecutions, and convictions for stalking continue to be low in the United States. The overall goal of this article is to introduce a multidimensional framework of stalking that adds to the current literature by (1) providing a conceptual framework consistent with legal elements of many stalking statutes to facilitate assessment, communication, documentation, and safety planning for stalking several victims; (2) introducing a more systematic way of assessing course of conduct and the context of fear in stalking situations in order to increase the understanding of cumulative fear for stalking victims; (3) emphasizing the aspects of stalking harm that go beyond violence and that show how harm from stalking accumulates over time including life sabotage; and (4) discussing 12 risk factors derived from the overall multidimensional framework that can be used to describe the big picture of stalking and to facilitate safety planning for victims. Implications for future research are discussed. © The Author(s) 2015.

  12. Lo stalking, un reato senza genere

    Directory of Open Access Journals (Sweden)

    Annamaria Iaccarino

    2015-09-01

    Full Text Available An individual who watches, follows, tracks and controls the victim with the aim of intervening, in a more or less violent way, in their private life is called a stalker or a “prowler always on the lookout”, because they commit repeated actions or attempted contacts or real communications, not desired by the victim, which may cause discomfort, anxiety, nuisance, concern and fear to the victim. Stalking is a term that may apply to any gender. To Lombroso’s “monster woman” and Hart’s “old maids’ madness” it is necessary to add the phenomenon of stalking committed by women whose modus operandi, without doubt, is more sly and subtle than the one of men. It refers to the retrospective act analysed by classic theories.

  13. Stalk-dependent and Stalk-independent Signaling by the Adhesion G Protein-coupled Receptors GPR56 (ADGRG1) and BAI1 (ADGRB1).

    Science.gov (United States)

    Kishore, Ayush; Purcell, Ryan H; Nassiri-Toosi, Zahra; Hall, Randy A

    2016-02-12

    The adhesion G protein-coupled receptors (aGPCRs) are a large yet poorly understood family of seven-transmembrane proteins. A defining characteristic of the aGPCR family is the conserved GAIN domain, which has autoproteolytic activity and can cleave the receptors near the first transmembrane domain. Several aGPCRs, including ADGRB1 (BAI1 or B1) and ADGRG1 (GPR56 or G1), have been found to exhibit significantly increased constitutive activity when truncated to mimic GAIN domain cleavage (ΔNT). Recent reports have suggested that the new N-terminal stalk, which is revealed by GAIN domain cleavage, can directly activate aGPCRs as a tethered agonist. We tested this hypothesis in studies on two distinct aGPCRs, B1 and G1, by engineering mutant receptors lacking the entire NT including the stalk (B1- and G1-SL, with "SL" indicating "stalkless"). These receptors were evaluated in a battery of signaling assays and compared with full-length wild-type and cleavage-mimicking (ΔNT) forms of the two receptors. We found that B1-SL, in multiple assays, exhibited robust signaling activity, suggesting that the membrane-proximal stalk region is not necessary for its activation. For G1, however, the results were mixed, with the SL mutant exhibiting robust activity in several signaling assays (including TGFα shedding, activation of NFAT luciferase, and β-arrestin recruitment) but reduced activity relative to ΔNT in a distinct assay (activation of SRF luciferase). These data support a model in which the activation of certain pathways downstream of aGPCRs is stalk-dependent, whereas signaling to other pathways is stalk-independent. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. The effect of antibiotics on diatom communities

    Digital Repository Service at National Institute of Oceanography (India)

    DeCosta, P.M.; Anil, A.C.

    Effect of antibiotics (penicillin (P), streptomycin (S) and chloramphenicol (C)) on benthic diatom communities was evaluated using a modified extinction–dilution method. The high antibiotic combinations (2PSC and PSC) reduced diatoms by 99...

  15. Diatom genomics: genetic acquisitions and mergers.

    Science.gov (United States)

    Nisbet, R Ellen R; Kilian, Oliver; McFadden, Geoffrey I

    2004-12-29

    Diatom algae arose by two-step endosymbiosis. The complete genome of the diatom Thalassiosira pseudonana has now been sequenced, allowing us to reconstruct the remarkable intracellular gene transfers that occurred during this convoluted cellular evolution.

  16. Briquetting of Charcoal from Sesame Stalk

    Directory of Open Access Journals (Sweden)

    Alula Gebresas

    2015-01-01

    Full Text Available Due to the easy availability of wood in Ethiopia, wood charcoal has been the main source fuel for cooking. This study has been started on sesame stalk biomass briquetting which can potentially solve the health problems and shortage of energy, which consequently can solve deforestation. The result of the data collection shows that, using 30% conversion efficiency of carbonizer, it was found that more than 150,000 tonnes of charcoal can be produced from the available sesame stalk in Humera, a place in north Ethiopia. The clay binders that are mixed with carbonized sesame stalk were found to have 69 liquid limits; thus, the optimum amount of clay that should be added as a binder is 15%, which results in better burning and heat holding capacity and better heating time. The developed briquetting machine has a capacity of producing 60 Kg/hr but the carbonization kiln can only carbonize 3.1 Kg in 2 : 40 hours; hence, it is a bottle neck for the briquette production. The hydrocarbon laboratory analysis showed that the calorific value of the charcoal produced with 15% clay content is 4647.75 Cal/gm and decreases as clay ratio increases and is found to be sufficient energy content for cooking.

  17. Do men and women differ in their perceptions of stalking: an exploratory study among college students.

    Science.gov (United States)

    Lambert, Eric G; Smith, Brad; Geistman, James; Cluse-Tolar, Terry; Jiang, Shanhe

    2013-01-01

    Stalking is a crime that can terrify its victims and ultimately take a severe emotional toll. Although a growing body of research has examined stalking experiences and reactions of victims, there has been far less research on whether men and women differ in their perceptions of stalking. Toward this end, a survey of college students at a large public 4-year Midwestern university was undertaken. We examined differences is how men and women view stalking and whether gender differences were moderated by prior stalking experience. Specifically, we examined whether there were gender differences in perceptions of the pervasiveness of stalking, the harm stalking does, who tends to be stalked, if stalking mainly involves former relational partners, possible motivations for stalking, the line between courtship and stalking, and notions of victim blaming. We found significant differences in stalking views between men and women on all the measures, except for perceptions of the line between courtship and stalking. Women tended to perceive stalking as more pervasive and harmful. Men were more likely to perceive stalking as involving strangers and to blame the victim for the stalking. Female and male respondents also differed in their perceptions of motivations for stalking. Prior victim stalking experience did not moderate the gender differences. Although being a prior stalking victim had a significant association with 4 of the 7 stalking perception variables, its effect sizes were smaller than that of gender.

  18. Effect of ageing on survival of benthic diatom propagules

    Digital Repository Service at National Institute of Oceanography (India)

    Anil, A.C.; Mitbavkar, S.; De; Hegde, S.; De; Meher, S.S.; Banerjee, D.

    unfavorable for vegetative growth, many diatoms form resting stages to survive cell degradation or death (Anderson, 1975; Malone, 1980; Hargraves and French, 1983; Fryxell, 1990). Various external factors like availability of nutrients (N, P, Fe, Si.... 128, 497-508. 15 Lewis, J., Harris, A.S.D., Jones, K.J., Edmonds, R.L., 1999. Long-term survival of marine planktonic diatoms and dinoflagellates in stored sediment samples. J. Plank. Res. 21, 343- 354. Malone, T.C., 1980. Algal size. In...

  19. Diatomic interaction potential theory applications

    CERN Document Server

    Goodisman, Jerry

    2013-01-01

    Diatomic Interaction Potential Theory, Volume 2: Applications discusses the variety of applicable theoretical material and approaches in the calculations for diatomic systems in their ground states. The volume covers the descriptions and illustrations of modern calculations. Chapter I discusses the calculation of the interaction potential for large and small values of the internuclear distance R (separated and united atom limits). Chapter II covers the methods used for intermediate values of R, which in principle means any values of R. The Hartree-Fock and configuration interaction schemes des

  20. Circular random motion in diatom gliding under isotropic conditions

    International Nuclear Information System (INIS)

    Gutiérrez-Medina, Braulio; Maldonado, Ana Iris Peña; Guerra, Andrés Jiménez; Rubio, Yadiralia Covarrubias; Meza, Jessica Viridiana García

    2014-01-01

    How cells migrate has been investigated primarily for the case of trajectories composed by joined straight segments. In contrast, little is known when cellular motion follows intrinsically curved paths. Here, we use time-lapse optical microscopy and automated trajectory tracking to investigate how individual cells of the diatom Nitzschia communis glide across surfaces under isotropic environmental conditions. We find a distinct kind of random motion, where trajectories are formed by circular arcs traveled at constant speed, alternated with random stoppages, direction reversals and changes in the orientation of the arcs. Analysis of experimental and computer-simulated trajectories show that the circular random motion of diatom gliding is not optimized for long-distance travel but rather for recurrent coverage of limited surface area. These results suggest that one main biological role for this type of diatom motility is to efficiently build the foundation of algal biofilms. (paper)

  1. Intensive aggregate formation with low vertical flux during an upwelling-induced diatom bloom

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Tiselius, P.; Mitchell-Innes, B.

    1998-01-01

    of turbulent shear in the ocean such stickiness coefficients predict very high specific coagulation rates (0.3 d(-1)). In situ video observation demonstrated the occurrence of abundant diatom aggregates with surface water concentrations between 1,000 and 3,000 ppm. Despite the very high concentration......The surfaces of most pelagic diatoms are sticky at times and may therefore form rapidly settling aggregates by physical coagulation. Stickiness and aggregate formation may be particularly adaptive in upwelling systems by allowing the retention of diatom populations in the vicinity of the upwelling...... center. We therefore hypothesized that upwelling diatom blooms are terminated by aggregate formation and rapid sedimentation. We monitored the development of a maturing diatom (mainly Chaetoceros spp.) bloom in the Benguela upwelling current during 7 d in February. Chlorophyll concentrations remained...

  2. Thermal Stress and Heat Transfer Coefficient for Ceramics Stalk Having Protuberance Dipping into Molten Metal

    Science.gov (United States)

    Noda, Nao-Aki; Hendra; Li, Wenbin; Takase, Yasushi; Ogura, Hiroki; Higashi, Yusuke

    Low pressure die casting is defined as a net shape casting technology in which the molten metal is injected at high speeds and pressure into a metallic die. The low pressure die casting process plays an increasingly important role in the foundry industry as a low-cost and high-efficiency precision forming technique. In the low pressure die casting process is that the permanent die and filling systems are placed over the furnace containing the molten alloy. The filling of the cavity is obtained by forcing the molten metal, by means of a pressurized gas, to rise into a ceramic tube having protuberance, which connects the die to the furnace. The ceramics tube, called stalk, has high temperature resistance and high corrosion resistance. However, attention should be paid to the thermal stress when the stalk having protuberance is dipped into the molten aluminum. It is important to reduce the risk of fracture that may happen due to the thermal stresses. In this paper, thermo-fluid analysis is performed to calculate surface heat transfer coefficient. The finite element method is applied to calculate the thermal stresses when the stalk having protuberance is dipped into the crucible with varying dipping speeds. It is found that the stalk with or without protuberance should be dipped into the crucible slowly to reduce the thermal stress.

  3. Luminescence properties of a nanoporous freshwater diatom.

    Science.gov (United States)

    Goswami, Bondita; Choudhury, Amarjyoti; Buragohain, Alak K

    2012-01-01

    Freshwater diatom frustules show special optical properties. In this paper we observed luminescence properties of the freshwater diatom Cyclotella meneghiniana. To confirm the morphological properties we present scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies were carried out to visualize the structural properties of the frustules, confirming that silica present in diatom frustules crystallizes in an α-quartz structure. Study of the optical properties of the silica frustules of diatoms using ultra-violet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy confirmed that the diatom C. meneghiniana shows luminescence in the blue region of the electromagnetic spectrum when irradiated with UV light. This property of diatoms can be exploited to obtain many applications in day-to-day life. Also, using time-resolved photoluminescence spectroscopy (TRPL) it was confirmed that this species of diatom shows bi-exponential decay. Copyright © 2011 John Wiley & Sons, Ltd.

  4. A diatom functional-based approach to assess changing environmental conditions in temporary depressional wetlands

    CSIR Research Space (South Africa)

    Riato, L

    2017-07-01

    Full Text Available is limited although important for the development of temporary wetland biological assessments. We assessed how diatom life-form and ecological guilds responded to a seasonal hydrological and hydrochemical gradient in three least human-disturbed, temporary...

  5. Antifungal properties of Musa paradisiaca (Plantain) peel and stalk ...

    African Journals Online (AJOL)

    Effect of plantain (Musa paradisiaca (L) AAB genomic group) peel and stalk extracts were investigated using percentage inhibition test. Complete inhibition of growth (100%) was observed for Aspergillusniger, Aspergillus oryzae and Rhizopus stolonifer at 1.0 mg/ml concentration of stalk extract. Peel extract inhibited A.

  6. Treatment of some Textile Industrial Effluents using Dry Corn Stalk ...

    African Journals Online (AJOL)

    Corn stalk ground to various mesh sizes was used to treat textile effluents obtained from three different industries. These effluents were first pretreated with alum and then charcoal; passing the water through a column, (20cm long and 5cm diameter) containing the ground corn stalk of size diameters of 300mm, 355mm ...

  7. Stalking als Straftatbestand : Neue Tendenzen in den EU-Mitgliedstaaten

    NARCIS (Netherlands)

    van der Aa, Suzanne; Bachman, Roland; Ortiz-Müller, Wolf

    2017-01-01

    Article 34 of the Council of Europe Convention on Preventing and Combating Violence against Women and Domestic Violence obliges signatory states to criminalize stalking. This article provides an inventory of criminal anti-stalking legislation in the 28 EU Member States in order to see whether they

  8. 78 FR 1125 - National Stalking Awareness Month, 2013

    Science.gov (United States)

    2013-01-07

    ... some point in their lives, 1 in 6 women and 1 in 19 men will be stalked, and many of these crimes will.... It can include implied or explicit threats; harassment; or nonconsensual communication through phone..., stalking tends to escalate over time, and it is sometimes followed by sexual assault or homicide. My...

  9. Bio-oil production from cotton stalk

    International Nuclear Information System (INIS)

    Zheng Jilu; Yi Weiming; Wang Nana

    2008-01-01

    Cotton stalk was fast pyrolyzed at temperatures between 480 deg. C and 530 deg. C in a fluidized bed, and the main product of bio-oil is obtained. The experimental result shows that the highest bio-oil yield of 55 wt% was obtained at 510 deg. C for cotton stalk. The chemical composition of the bio-oil acquired was analyzed by GC-MS, and its heat value, stability, miscibility and corrosion characteristics were determined. These results showed that the bio-oil obtained can be directly used as a fuel oil for combustion in a boiler or a furnace without any upgrading. Alternatively, the fuel can be refined to be used by vehicles. Furthermore, the energy performance of the pyrolysis process was analyzed. In the pyrolysis system used in our experiment, some improvements to former pyrolysis systems are done. Two screw feeders were used to prevent jamming the feeding system, and the condenser is equipped with some nozzles and a heat exchanger to cool quickly the cleaned hot gas into bio-oil

  10. [Mental health impact of stalking in men and women].

    Science.gov (United States)

    Kuehner, Christine; Gass, Peter; Dressing, Harald

    2006-08-01

    Using data from the Mannheim stalking study, the present report analyses gender differences with regard to various mental health indicators and potential mediator effects of stalking victimization. Furthermore, we were interested in whether the impact of stalking on mental health was comparable for men and women. The study included a postal survey of 675 community residents on the experience of intruding harassment and on mental health indicators. In the Patient Health Questionnaire (PHQ-D, Lowe et al. 2001), women scored higher on most of the subscales (depression, anxiety, somatic complaints, stress, psychosocial impairment) than men. Furthermore, more women fulfilled criteria for at least one threshold or subthreshold mental disorder syndrome according to DSM-IV, and more women were under psychotropic medication. However, the identified associations were completely mediated by the higher prevalence of stalking victims in women. In contrast, the associations of stalking victimization with poor mental health, psychosocial functioning, and use of medication were largely comparable across gender.

  11. [Anaerobic co-digestion of corn stalk and vermicompost].

    Science.gov (United States)

    Chen, Guang-yin; Zheng, Zheng; Zou, Xing-xing; Fang, Cai-xia; Luo, Yan

    2010-02-01

    The characteristics of corn stalk digested alone at different total solid (TS) loading rates and co-digestion of various proportions of corn stalk and vermicompost were investigated by batch model at 35 degrees C +/- 1 degrees C. The organic loading rates (OLRs) studied were in the range of 1.2%-6.0% TS and increasing proportions of vermicompost from 20% to 80% TS. A maximum methane yield of corn stalk digested alone was 217.60 mL/g obtained at the TS loading rate of 4.8%. However, when the TS loading rate was 6.0%, the anaerobic system was acidified and the lowest pH value was 5.10 obtained on day 4 and the biogas productivity decreased. Furthermore, co-digestion of vermicompost and corn stalk in varying proportions were investigated at constant of 6.0% TS. Co-digestion with vermicompost improved the biodegradability of corn stalk and the methane yield was improved by 4.42%-58.61%, and led to higher pH values, higher volatile fatty acids (VFAs) concentration and lower alkalinity content compared with corn stalk digested alone. The maximum biogas yield and methane yield of 410.30 mL/g and 259. 35 mL/g were obtained for 40% vermicompost and 60% corn stalk respectively. Compared with corn stalk digested alone, co-digested with vermicompost didn' t affect methane content and the fermentation type, but promoted the destruction of crystalline of cellulose and the highest destruction rate was 29.36% for 40% vermicompost and 60% corn stalk. Therefore, adding vermicompost was beneficial for the decomposition and increasing the biotransformation rate of corn stalk.

  12. Stability of the 'L12 stalk' in ribosomes from mesophilic and (hyper)thermophilic Archaea and Bacteria.

    Science.gov (United States)

    Shcherbakov, D; Dontsova, M; Tribus, M; Garber, M; Piendl, W

    2006-01-01

    The ribosomal stalk complex, consisting of one molecule of L10 and four or six molecules of L12, is attached to 23S rRNA via protein L10. This complex forms the so-called 'L12 stalk' on the 50S ribosomal subunit. Ribosomal protein L11 binds to the same region of 23S rRNA and is located at the base of the 'L12 stalk'. The 'L12 stalk' plays a key role in the interaction of the ribosome with translation factors. In this study stalk complexes from mesophilic and (hyper)thermophilic species of the archaeal genus Methanococcus and from the Archaeon Sulfolobus solfataricus, as well as from the Bacteria Escherichia coli, Geobacillus stearothermophilus and Thermus thermophilus, were overproduced in E.coli and purified under non-denaturing conditions. Using filter-binding assays the affinities of the archaeal and bacterial complexes to their specific 23S rRNA target site were analyzed at different pH, ionic strength and temperature. Affinities of both archaeal and bacterial complexes for 23S rRNA vary by more than two orders of magnitude, correlating very well with the growth temperatures of the organisms. A cooperative effect of binding to 23S rRNA of protein L11 and the L10/L12(4) complex from mesophilic and thermophilic Archaea was shown to be temperature-dependent.

  13. Sampler collection gadget for epilithic diatoms.

    Science.gov (United States)

    Salomoni, S E; Torgan, L C; Rocha, O

    2007-11-01

    This work present a new gadget for sampling epilithic diatoms from both lentic and lotic enviroments. The sampler consists of a polystyrene cylinder, left to float on the surface of the water, to which stone substrates are attached. This epilithic diatom sampler (EDS) can be used to detect spatial and temporal richness and density variation in the study of the diatom community, as well as in water quality monitoring.

  14. Sampler collection gadget for epilithic diatoms

    Directory of Open Access Journals (Sweden)

    SE. Salomoni

    Full Text Available This work present a new gadget for sampling epilithic diatoms from both lentic and lotic enviroments. The sampler consists of a polystyrene cylinder, left to float on the surface of the water, to which stone substrates are attached. This epilithic diatom sampler (EDS can be used to detect spatial and temporal richness and density variation in the study of the diatom community, as well as in water quality monitoring.

  15. Shared Epizoic Taxa and Differences in Diatom Community Structure Between Green Turtles (Chelonia mydas) from Distant Habitats.

    Science.gov (United States)

    Majewska, Roksana; de Vijver, Bart Van; Nasrolahi, Ali; Ehsanpour, Maryam; Afkhami, Majid; Bolaños, Federico; Iamunno, Franco; Santoro, Mario; De Stefano, Mario

    2017-11-01

    The first reports of diatoms growing on marine mammals date back to the early 1900s. However, only recently has direct evidence been provided for similar associations between diatoms and sea turtles. We present a comparison of diatom communities inhabiting carapaces of green turtles Chelonia mydas sampled at two remote sites located within the Indian (Iran) and Atlantic (Costa Rica) Ocean basins. Diatom observations and counts were carried out using scanning electron microscopy. Techniques involving critical point drying enabled observations of diatoms and other microepibionts still attached to sea turtle carapace and revealed specific aspects of the epizoic community structure. Species-poor, well-developed diatom communities were found on all examined sea turtles. Significant differences between the two host sea turtle populations were observed in terms of diatom abundance and their community structure (including growth form structure). A total of 12 and 22 diatom taxa were found from sea turtles in Iran and Costa Rica, respectively, and eight of these species belonging to Amphora, Chelonicola, Cocconeis, Navicula, Nitzschia and Poulinea genera were observed in samples from both locations. Potential mechanisms of diatom dispersal and the influence of the external environment, sea turtle behaviour, its life stage, and foraging and breeding habitats, as well as epibiotic bacterial flora on epizoic communities, are discussed.

  16. Architecture and material properties of diatom shells provide effective mechanical protection

    Science.gov (United States)

    Hamm, Christian E.; Merkel, Rudolf; Springer, Olaf; Jurkojc, Piotr; Maier, Christian; Prechtel, Kathrin; Smetacek, Victor

    2003-02-01

    Diatoms are the major contributors to phytoplankton blooms in lakes and in the sea and hence are central in aquatic ecosystems and the global carbon cycle. All free-living diatoms differ from other phytoplankton groups in having silicified cell walls in the form of two `shells' (the frustule) of manifold shape and intricate architecture whose function and role, if any, in contributing to the evolutionary success of diatoms is under debate. We explored the defence potential of the frustules as armour against predators by measuring their strength. Real and virtual loading tests (using calibrated glass microneedles and finite element analysis) were performed on centric and pennate diatom cells. Here we show that the frustules are remarkably strong by virtue of their architecture and the material properties of the diatom silica. We conclude that diatom frustules have evolved as mechanical protection for the cells because exceptional force is required to break them. The evolutionary arms race between diatoms and their specialized predators will have had considerable influence in structuring pelagic food webs and biogeochemical cycles.

  17. Nature & prevalence of stalking among New Zealand mental health clinicians.

    Science.gov (United States)

    Hughes, Frances A; Thom, Katey; Dixon, Robyn

    2007-04-01

    Stalking involves recurrent and persistent unwanted communication or contact that generates fear for safety in the victims. This pilot study evaluated the nature and prevalence of stalking among New Zealand nurses and physicians working in mental health services. An anonymous questionnaire asking respondents to describe their experiences with 12 stalking behaviors was distributed to 895 clinicians. Results indicated that regardless of discipline, women were more likely than men to have experienced one or more stalking behaviors, including receiving unwanted telephone calls, letters, and approaches; receiving personal threats: and being followed, spied on, or subject to surveillance. Women also reported higher levels of fearfulness as a consequence of stalking behaviors. Nearly half of the stalkers were clients; the remaining were former partners, colleagues, or acquaintances. In client-related cases, the majority of respondents told their colleagues and supervisors first, and the majority found them to be the most helpful resource. The results of this pilot study indicate a need for further research focused on the stalking of mental health clinicians in New Zealand and for development of workplace policies for adequate response to the stalking of mental health clinicians.

  18. Diatom-inspired templates for 3D replication: natural diatoms versus laser written artificial diatoms

    International Nuclear Information System (INIS)

    Belegratis, M R; Schmidt, V; Nees, D; Stadlober, B; Hartmann, P

    2014-01-01

    The diatoms are ubiquitous, exist in large numbers and show a great diversity of features on their porous silica structures. Therefore, they inspire the fabrication of nanostructured templates for nanoimprint processes (NIL), where large structured areas with nanometer precision are required. In this study, two approaches regarding the respective challenges and potential exploitations are followed and discussed: the first one takes advantage of a template that is directly made of natural occurring diatoms. Here, two replication steps via soft lithography are needed to obtain a template which is subsequently used for NIL. The second approach exploits the technical capabilities of the precise 3D laser lithography (3DLL) based on two-photon polymerization of organic materials. This method enables the fabrication of arbitrary artificial diatom-inspired micro- and nanostructures and the design of an inverse structure. Therefore, only one replication step is needed to obtain a template for NIL. In both approaches, a replication technique for true 3D structures is shown. (paper)

  19. The prevalence and nature of stalking in the Australian community.

    Science.gov (United States)

    Purcell, Rosemary; Pathé, Michele; Mullen, Paul E

    2002-02-01

    This study examines the extent and nature of stalking victimisation in a random community sample. A postal survey was distributed to 3700 adult men and women selected from the electoral roll in the State of Victoria. Outcome measures included the lifetime and annual cumulative incidence of stalking, the duration and methods of harassment, rates of associated violence and responses to victimisation. Almost one in four respondents (23.4%;432) had been stalked, the unwanted behaviour they were subjected to being both repeated and fear-provoking. One in 10 (197) had experienced a protracted course of stalking involving multiple intrusions spanning a period of at least one month. Women were twice as likely as men to report having been stalked at some time in their lives, though the rates of victimisation in the 12 months prior to the study did not differ significantly according to gender. Younger people were significantly more likely than older respondents to report having been stalked. Victims were pursued by strangers in 42% of cases. The most common methods of harassment involved unwanted telephone calls, intrusive approaches and following. Associated threats (29%) and physical assaults (18%) frequently arose out of the stalking. Significant social and economic disruption was created by the stalking for 63% of victims. Most sought assistance to manage their predicament (69%). The experience of being stalked is common and appears to be increasing. Ten percent of people have been subjected at some time to an episode of protracted harassment. Assaults by stalkers are disturbingly frequent. Most victims report significant disruption to their daily functioning irrespective of exposure to associated violence.

  20. Evaluation of elastic modulus and hardness of crop stalks cell walls by nano-indentation

    Science.gov (United States)

    Yan Wu; Siqun Wang; Dingguo Zhou; Cheng Xing; Yang Zhang; Zhiyong Cai

    2010-01-01

    Agricultural biomaterials such as crop stalks are natural sources of cellulosic fiber and have great potential as reinforced materials in bio-composites. In order to evaluate their potential as materials for reinforcement, the nano-mechanical properties of crop-stalk cell walls, i.e. those of cotton (Gossypium herbaceu) stalk, soybean (Glycine max) stalk, cassava (...

  1. The subcellular distribution of the human ribosomal "stalk" components: P1, P2 and P0 proteins

    DEFF Research Database (Denmark)

    Tchórzewski, Marek; Krokowski, Dawid; Rzeski, Wojciech

    2003-01-01

    The ribosomal "stalk" structure is a distinct lateral protuberance located on the large ribosomal subunit in prokaryotic, as well as in eukaryotic cells. In eukaryotes, this ribosomal structure is composed of the acidic ribosomal P proteins, forming two hetero-dimers (P1/P2) attached...

  2. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    Science.gov (United States)

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (paluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated aluminium. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Stalking: terrorism at our doors--how social workers can help victims fight back.

    Science.gov (United States)

    Spitz, Mary-Ann Leitz

    2003-10-01

    Stalking is a dangerous and devastating crime that irrevocably changes the lives of victims but is frequently misunderstood and minimized. Victims report that their lives are never the same after they have been stalked. Stalking is prevalent and gender-neutral and occurs across all socioeconomic lines and in all clinical settings. The prevalence of stalking provides many opportunities for social workers to intervene, but first they must recognize and understand the problem. This article explains common misconceptions about stalking, contains a brief discussion of the types of stalking, the elements necessary to criminally charge someone with stalking, strategies for the victims, and suggestions for future research.

  4. Relationship between diatom communities and environmental ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-30

    Nov 30, 2011 ... The relationship between diatom species and measured environmental variables was explored at different sites of Honghe wetland region located in northeastern China. Planktonic and epiphytic diatom assemblages in the wetland were identified from May to October of 2007 and 2008. Their relationships.

  5. Colloquium on diatom-copepod interactions

    DEFF Research Database (Denmark)

    Paffenhofer, G.A.; Ianora, A.; Miralto, A.

    2005-01-01

    in situ were also addressed. During the plenary session, the most recent advances on this topic were presented. The plenary session was followed by 3 working groups on (1) production of aldehydes by phytoplankton, (2) toxic and nutritional effects of diatoms on zooplankton, and (3) the chemistry of diatom...

  6. Relationship between diatom communities and environmental ...

    African Journals Online (AJOL)

    Abstract. The relationship between diatom species and measured environmental variables was explored at different sites of Honghe wetland region located in northeastern China. Planktonic and epiphytic diatom assemblages in the wetland were identified from May to October of 2007 and 2008. Their relationships with ...

  7. Selective silicate-directed motility in diatoms

    DEFF Research Database (Denmark)

    Bondoc, Karen Grace V.; Heuschele, Jan; Gillard, Jeroen

    2016-01-01

    the major sink in the global Si cycle. Dissolved silicic acid (dSi) availability frequently limits diatom productivity and influences species composition of communities. We show that benthic diatoms selectively perceive and behaviourally react to gradients of dSi. Cell speed increases under d...

  8. 75 FR 81085 - National Stalking Awareness Month, 2011

    Science.gov (United States)

    2010-12-27

    ... victimization than men. Stalking can be a difficult crime to recognize. The majority of survivors do not report... affects too many Americans to remain a hidden crime, and a strong stand is required in order to both...

  9. Stalking: The term, features and proposals de lege ferenda

    Directory of Open Access Journals (Sweden)

    Ranđelović Višnja M.

    2016-01-01

    Full Text Available In the paper author analyzes main features of stalking, which is recognized as a serious problem in many countries and provided as a criminal offense. There are presented comparative legela solutions of this criminal offense in the countries that have incriminated it firs, as well as in neighboring countries. In recent years in Republic of Serbia it has been indicated to prevalence of the stalking, especially among the former partners, and considering that there is a need for such behavior to be incriminated. Also, Serbia's ratification of the Council of Europe Convention on Preventing and Combating Violence against Women and Domestic Violence assumed an obligation to prescribe stalking as criminal offense. This paper proposes the possible way of prescribing stalking with analysis of certain elements of the legal description.

  10. Displacement functions for diatomic materials

    International Nuclear Information System (INIS)

    Panrkin, D.M.; Coulter, C.A.

    1979-01-01

    An extension of the methods of Lindhard et at. was used to calculate the total displacement function n/sub ij/(E) for a number of diatomic materials, where n/sub ij/(E) is defined to be the average number of atoms of type j which are displaced from their sites in a displacement cascade initiated by a PKA of type i and energy E. From the n/sub ij/(E) one can calculate the fraction n/sub ij/(E) of the displacements produced by a type i PKA with energy E which are of type j. Values of the n/sub ij/ for MgO, CaO, Al 2 O 3 , and TaO are presented. It is shown that for diatomic materials with mass ratios reasonably near one (e.g., MgO, Al 2 O 3 ) and equal displacement thresholds for the two species the n/sub ij/ become independent of the PKA type i at energies only a few times threshold. However, for larger mass ratios the n/sub ij/ do not become independent of i until much larger, energies are reached - e.g. > 10 5 eV for TaO. In addition, it is found that the n/sub ij/ depend sensitively on the displacement thresholds, with very dramatic charges occuring when the two thresholds become significantly different from one another

  11. Behavioral and Mental Health Correlates of Youth Stalking Victimization

    Science.gov (United States)

    Reidy, Dennis E.; Smith-Darden, Joanne P.; Kernsmith, Poco D.

    2018-01-01

    Introduction Although recognized as a public health problem, little attention has been paid to the problem of stalking among youth. Latent profile analysis was used to identify latent groups of adolescent stalking victims and their behavioral and mental health correlates. Methods A cross-sectional sample of 1,236 youths were randomly selected from 13 schools stratified by community risk level (i.e., low, moderate, and high risk) and gender. Students completed surveys assessing behavioral indicators of stalking victimization, as well as substance use, sexual behavior, dating violence, and psychiatric symptoms. Data were collected in 2013 and data analyses were performed in 2015. Results Analysis indicated the presence of a non-victim class, a minimal exposure class, and a victim class for boys and girls alike. Approximately 14% of girls and 13% of boys were in the stalking victim class. Adolescents in the victim class reported more symptoms of post-traumatic stress, mood disorder, and hopelessness, as well as more instances of alcohol use, binge drinking, and physical dating violence victimization. Girls in the victim class also reported engaging in sexting behaviors and oral sex with significantly more partners than their non-victim peers. Conclusions These findings provide valuable knowledge of the prevalence and pertinent health correlates of stalking victimization in adolescence. The data suggest a substantial proportion of adolescents are victims of stalking and are likewise at risk for a number of deleterious health outcomes. As such, this population merits further attention by prevention researchers and practitioners. PMID:27743623

  12. Stalk-length-dependence of the contractility of Vorticella convallaria

    Science.gov (United States)

    Gul Chung, Eun; Ryu, Sangjin

    2017-12-01

    Vorticella convallaria is a sessile protozoan of which the spasmoneme contracts on a millisecond timescale. Because this contraction is induced and powered by the binding of calcium ions (Ca2+), the spasmoneme showcases Ca2+-powered cellular motility. Because the isometric tension of V. convallaria increases linearly with its stalk length, it is hypothesized that the contractility of V. convallaria during unhindered contraction depends on the stalk length. In this study, the contractile force and energetics of V. convallaria cells of different stalk lengths were evaluated using a fluid dynamic drag model which accounts for the unsteadiness and finite Reynolds number of the water flow caused by contracting V. convallaria and the wall effect of the no-slip substrate. It was found that the contraction displacement, peak contraction speed, peak contractile force, total mechanical work, and peak power depended on the stalk length. The observed stalk-length-dependencies were simulated using a damped spring model, and the model estimated that the average spring constant of the contracting stalk was 1.34 nN µm-1. These observed length-dependencies of Vorticella’s key contractility parameters reflect the biophysical mechanism of the spasmonemal contraction, and thus they should be considered in developing a theoretical model of the Vorticella spasmoneme.

  13. Identification of sources of resistance to anthracnose stalk rot in maize

    Directory of Open Access Journals (Sweden)

    Alessandro Nicoli

    Full Text Available ABSTRACT: Adoption of resistant cultivars is the primary measure used to control anthracnose stalk rot. The goal of this study was to identify maize-resistant genotypes to anthracnose stalk rot, which are similar to the hybrid 2B710. Experiments were performed at Embrapa Maize and Sorghum experimental fields in Brazil. The first experimental trial evaluated 234 maize lines as well as two commercials hybrids, BRS1010 (susceptible and 2B710 (resistant. Artificial inoculations were performed with a strain at the blister (R2 phase, and evaluation of disease severity was performed after 30 days. The second experimental trial evaluated 48 maize lines and hybrids, inoculated with two Colletotrichum graminicola strains. In the first trial, eight resistance groups were formed, and the last lines were more resistant, as was the hybrid 2B710, with values between 11.50% and 23.0% of severity. In the second trial, there was an interaction between the two factors, lines and isolates, and the lines often showed the same reaction features as those obtained in the first trial. However, the disease severity was higher for most lines, even when using other isolates. These lines with effective levels of resistance could be used in future studies of inheritance, in programs to develop hybrids, and to identify molecular markers associated with resistance to anthracnose stalk rot in maize.

  14. A stalk of grain and light

    Directory of Open Access Journals (Sweden)

    Erín Moure

    2010-11-01

    Full Text Available "Stalk of Grain and Light" is an excerpt from O Resplandor (Toronto: Anansi, forthcoming 2010, a book of poetry that explodes notions of authorship and translation. In it, the heteronymic character Elisa Sampedrín translates from Nichita Stãnescu, though she knows no Romanian, and the orthonymic character Erín Moure translates Paul Celan, using not Celan but English transcreations from the language of Celan by Oana Avasilichioaei which she appropriates and reorganizes to create the true translation of a poem by Paul Celan, which exists only in her mind. In this world where corporations copyright human cells, where academics and libraries appropriate works of writers, and where writing itself - moreso than visual art - is limited by expanded notions of plagiarism and ownership, of continuity of copyright for decades that prevents works from influencing art's future, Moure refutes the idea that writing is inspired out of nowhere. Here it is rooted to human interaction, to love and loss, to the art of others, and is dedicated to creating a world where the free irruption of thought is possible, and lineages are acknowledged.

  15. A stalk of grain and light

    Directory of Open Access Journals (Sweden)

    Erín Moure

    2009-01-01

    Full Text Available http://dx.doi.org/10.5007/2175-8026.2009n56p33 "Stalk of Grain and Light" is an excerpt from O Resplandor (Toronto: Anansi, forthcoming 2010, a book of poetry that explodes notions of authorship and translation. In it, the heteronymic character Elisa Sampedrín translates from Nichita Stãnescu, though she knows no Romanian, and the orthonymic character Erín Moure translates Paul Celan, using not Celan but English transcreations from the language of Celan by Oana Avasilichioaei which she appropriates and reorganizes to create the true translation of a poem by Paul Celan, which exists only in her mind. In this world where corporations copyright human cells, where academics and libraries appropriate works of writers, and where writing itself - moreso than visual art - is limited by expanded notions of plagiarism and ownership, of continuity of copyright for decades that prevents works from influencing art's future, Moure refutes the idea that writing is inspired out of nowhere. Here it is rooted to human interaction, to love and loss, to the art of others, and is dedicated to creating a world where the free irruption of thought is possible, and lineages are acknowledged.

  16. Modeling of kinetics of Cr(VI) sorption onto grape stalk waste in a stirred batch reactor

    International Nuclear Information System (INIS)

    Escudero, Carlos; Fiol, Nuria; Poch, Jordi; Villaescusa, Isabel

    2009-01-01

    Recently, Cr(VI) removal by grape stalks has been postulated to follow two mechanisms, adsorption and reduction to trivalent chromium. Nevertheless, the rate at which both processes take place and the possible simultaneity of both processes has not been investigated. In this work, kinetics of Cr(VI) sorption onto grape stalk waste has been studied. Experiments were carried out at different temperatures but at a constant pH (3 ± 0.1) in a stirred batch reactor. Results showed that three steps take place in the process of Cr(VI) sorption onto grape stalk waste: Cr(VI) sorption, Cr(VI) reduction to Cr(III) and the adsorption of the formed Cr(III). Taking into account the evidences above mentioned, a model has been developed to predict Cr(VI) sorption on grape stalks on the basis of (i) irreversible reduction of Cr(VI) to Cr(III) reaction, whose reaction rate is assumed to be proportional to the Cr(VI) concentration in solution and (ii) adsorption and desorption of Cr(VI) and formed Cr(III) assuming that all the processes follow Langmuir type kinetics. The proposed model fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The proposed model would be helpful for researchers in the field of Cr(VI) biosorption to design and predict the performance of sorption processes.

  17. Diatomic molecule vibrational potentials: Accuracy of representations

    International Nuclear Information System (INIS)

    Engelke, R.

    1978-01-01

    A method is presented for increasing the radius of convergence of certain representations of diatomic molecule vibrational potentials. The method relies on using knowledge of the analytic structure of such potentials to the maximum when attempting to approximate them. The known singular point (due to the centrifugal and/or Coulomb potentials) at zero internuclear separation should be included in its exact form in an approximate representation. The efficacy of this idea is tested [using Peek's ''exact'' numerical Born-Oppenheimer potential for the (1ssigma/sub g/) 2 Σ + /sub g/ state of H + 2 as a test problem] when the representational form is the series of (1) Dunham, (2) Simons, Parr, and Finlan, (3) Thakkar, and (4) Ogilvie-Tipping, and also (5) when the form is a [2, 2] or a [3, 3] Pade approximant. Significant improvements in accuracy are obtained in some of these cases, particularly on the inner wall of the potential. A comparison of the effectiveness of the five methods is made both with and without the origin behavior being included exactly. This is useful in itself as no comprehensive accuracy comparison of the standard representations seems to have appeared in the literature. The Ogilvie-Tipping series, corrected at the origin for singular behavior, is the best representation presently available for states analogous to the (1ssigma/sub g/) 2 Σ + /sub g/ state of H + 2

  18. Fast pyrolysis product distribution of biopretreated corn stalk by methanogen.

    Science.gov (United States)

    Wang, Tipeng; Ye, Xiaoning; Yin, Jun; Jin, Zaixing; Lu, Qiang; Zheng, Zongming; Dong, Changqing

    2014-10-01

    After pretreated by methanogen for 5, 15 and 25 days, corn stalk (CS) were pyrolyzed at 250, 300, 350, 400, 450 and 500 °C by Py-GC/MS and product distribution in bio-oil was analyzed. Results indicated that methanogen pretreatment changed considerably the product distribution: the contents of sugar and phenols increased; the contents of linear carbonyls and furans decreased; the contents of linear ketones and linear acids changed slightly. Methanogen pretreatment improved significantly the pyrolysis selectivity of CS to phenols especially 4-VP. At 250 °C, the phenols content increased from 42.25% for untreated CS to 79.32% for biopretreated CS for 5 days; the 4-VP content increased from 28.6% to 60.9%. Increasing temperature was contributed to convert more lignin into 4-VP, but decreased its content in bio-oil due to more other chemicals formed. The effects of biopretreatment time on the chemicals contents were insignificant. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Kinetic control on Zn isotope signatures recorded in marine diatoms

    Science.gov (United States)

    Köbberich, Michael; Vance, Derek

    2017-08-01

    Marine diatoms dominate the oceanic cycle of the essential micronutrient zinc (Zn). The stable isotopes of zinc and other metals are increasingly used to understand trace metal micronutrient cycling in the oceans. One clear feature of the early isotope data is the heavy Zn isotope signature of the average oceanic dissolved pool relative to the inputs, potentially driven by uptake of light isotopes into phytoplankton cells and export to sediments. However, despite the fact that diatoms strip Zn from surface waters across the Antarctic polar front in the Southern Ocean, the local upper ocean is not isotopically heavy. Here we use culturing experiments to quantify the extent of Zn isotope fractionation by diatoms and to elucidate the mechanisms driving it. We have cultured two different open-ocean diatom species (T. oceanica and Chaetoceros sp.) in a series of experiments at constant medium Zn concentration but at bioavailable medium Fe ranging from limiting to replete. We find that T. oceanica can maintain high growth rates and Zn uptake rates over the full range of bioavailable iron (Fe) investigated, and that the Zn taken up has a δ66Zn that is unfractionated relative to that of the bioavailable free Zn in the medium. The studied representative of the genus Chaetoceros, on the other hand, shows more significantly reduced Zn uptake rates at low Fe and records more variable biomass δ66Zn signatures, of up to 0.85‰ heavier than the medium. We interpret the preferential uptake of heavy isotopes at extremely low Zn uptake rates as potentially due to either of the following two mechanisms. First, the release of extracellular polymeric substances (EPS), at low Fe levels, may preferentially scavenge heavy Zn isotopes. Second, the Zn uptake rate may be slow enough to establish pseudo-equilibrium conditions at the transporter site, with heavy Zn isotopes forming more stable surface complexes. Thus we find that, in our experiments, Fe-limitation exerts a key control that

  20. Diatom assemblage in a tropical lake of northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Lilian Rodrigues do Nascimento

    2010-02-01

    Full Text Available The composition and spatial variation of diatom assemblage in surface sediments of Caçó Lake (shallow, mesotrophic and weakly acid lake - Maranhão State, Brazil were analyzed in order to know the distribution pattern of the species along the lake during rainy season (April 1999. Four zones were established in the lake based on 21 diatoms species and habitat affinities. The first three zones (prime three meters deep to six meters deep were marked by the occurrence of Pinnularia gigas, Frustulia rhomboides, Encyonopsis krasskei, Eunotia camelus, E. femoriformis and E. monodon. Zone IV (seven to nine meters deep was inhabited mainly by Surirella biseriata and Fragilariforma floridana. During the beginning of the rainy season, the diatom assemblage in Caçó Lake was composed mainly by benthic and epiphytic forms that reflected the low lake levels and the abundance of littoral vegetation present in this lake.Com o objetivo de se conhecer a dinâmica espacial e a distribuição das diatomáceas contidas no sedimento superficial do lago Caçó, durante o período de chuvas (abril de 1999 foram realizadas coletas em um "transect" horizontal. A partir da observação destas coletas efetuadas a cada 1 metro pode-se observar que a distribuição das diatomáceas esteve fortemente ligada a ocorrência do banco de macrófitas da sua margem, com a ocorrência maciça das espécies epifíticas e bentônicas. A análise de agrupamento de dados permitiu uma melhor visualização, da sua distribuição a cada profundidade e também das associações específicas em cada zona. Os resultados deste estudo permitiram concluir que a ocorrência e distribuição das diatomáceas do Lago Caçó está fortemente ligada ao banco de macrófitas localizado em suas margens, definindo assim zonas características dentro do lago.

  1. Intracellular Nitrate of Marine Diatoms as a Driver of Anaerobic Nitrogen Cycling in Sinking Aggregates

    Directory of Open Access Journals (Sweden)

    Anja Kamp

    2016-11-01

    Full Text Available Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly in concentrations > 60 mmol L-1 both as free-living cells and associated to aggregates. Intracellular nitrate concentrations exceeded extracellular concentrations by three orders of magnitude. Intracellular nitrate was used up within 2-3 days after shifting diatom-bacteria aggregates to dark and anoxic conditions. Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before the aggregates have settled onto the seafloor could fuel benthic nitrogen transformations.

  2. Diatoms on the carapace of common snapping turtles: Luticola spp. dominate despite spatial variation in assemblages.

    Directory of Open Access Journals (Sweden)

    Shelly C Wu

    Full Text Available Filamentous algae are often visible on the carapaces of freshwater turtles and these algae are dominated by a few species with varying geographic distributions. Compared to filamentous algae, little is known about the much more speciose microalgae on turtles. Our objectives were to compare the diatom flora on a single turtle species (the common snapping turtle, Chelydra serpentina across part of its range to examine spatial patterns and determine whether specific diatom taxa were consistently associated with turtles (as occurs in the filamentous alga Basicladia spp.. Using preserved turtle specimens from museums, we systematically sampled diatoms on the carapaces of 25 snapping turtles across five states. The diverse diatom assemblages formed two groups-the southern Oklahoma group and the northern Illinois/Wisconsin/New York group, with Arkansas not differing from either group. Of the six diatom species found in all five states, four species are widespread, whereas Luticola cf. goeppertiana and L. cf. mutica are undescribed species, known only from turtles in our study. L. cf. goeppertiana comprised 83% of the diatom abundance on Oklahoma turtles and was relatively more abundant on southern turtles (Oklahoma and Arkansas than on northern turtles (where mean abundance/state was > 10%. L. cf. mutica was the most abundant species (40% on New York turtles. Some Luticola species are apparently turtle associates and results support a pattern of spatial variation in Luticola species, similar to that in Basicladia. Using museum specimens is an efficient and effective method to study the distribution of micro-epibionts.

  3. Diatoms on the carapace of common snapping turtles: Luticola spp. dominate despite spatial variation in assemblages

    Science.gov (United States)

    Wu, Shelly C.; Bergey, Elizabeth A.

    2017-01-01

    Filamentous algae are often visible on the carapaces of freshwater turtles and these algae are dominated by a few species with varying geographic distributions. Compared to filamentous algae, little is known about the much more speciose microalgae on turtles. Our objectives were to compare the diatom flora on a single turtle species (the common snapping turtle, Chelydra serpentina) across part of its range to examine spatial patterns and determine whether specific diatom taxa were consistently associated with turtles (as occurs in the filamentous alga Basicladia spp.). Using preserved turtle specimens from museums, we systematically sampled diatoms on the carapaces of 25 snapping turtles across five states. The diverse diatom assemblages formed two groups–the southern Oklahoma group and the northern Illinois/Wisconsin/New York group, with Arkansas not differing from either group. Of the six diatom species found in all five states, four species are widespread, whereas Luticola cf. goeppertiana and L. cf. mutica are undescribed species, known only from turtles in our study. L. cf. goeppertiana comprised 83% of the diatom abundance on Oklahoma turtles and was relatively more abundant on southern turtles (Oklahoma and Arkansas) than on northern turtles (where mean abundance/state was > 10%). L. cf. mutica was the most abundant species (40%) on New York turtles. Some Luticola species are apparently turtle associates and results support a pattern of spatial variation in Luticola species, similar to that in Basicladia. Using museum specimens is an efficient and effective method to study the distribution of micro-epibionts. PMID:28192469

  4. Biofilm and capsule formation of the diatom Achnanthidium minutissimum are affected by a bacterium.

    Science.gov (United States)

    Windler, Miriam; Leinweber, Katrin; Bartulos, Carolina Rio; Philipp, Bodo; Kroth, Peter G

    2015-04-01

    Photoautotrophic biofilms play an important role in various aquatic habitats and are composed of prokaryotic and/or eukaryotic organisms embedded in extracellular polymeric substances (EPS). We have isolated diatoms as well as bacteria from freshwater biofilms to study organismal interactions between representative isolates. We found that bacteria have a strong impact on the biofilm formation of the pennate diatom Achnanthidium minutissimum. This alga produces extracellular capsules of insoluble EPS, mostly carbohydrates (CHO), only in the presence of bacteria (xenic culture). The EPS themselves also have a strong impact on the aggregation and attachment of the algae. In the absence of bacteria (axenic culture), A. minutissimum did not form capsules and the cells grew completely suspended. Fractionation and quantification of CHO revealed that the diatom in axenic culture produces large amounts of soluble CHO, whereas in the xenic culture mainly insoluble CHO were detected. For investigation of biofilm formation by A. minutissimum, a bioassay was established using a diatom satellite Bacteroidetes bacterium that had been shown to induce capsule formation of A. minutissimum. Interestingly, capsule and biofilm induction can be achieved by addition of bacterial spent medium, indicating that soluble hydrophobic molecules produced by the bacterium may mediate the diatom/bacteria interaction. With the designed bioassay, a reliable tool is now available to study the chemical interactions between diatoms and bacteria with consequences for biofilm formation. © 2015 Phycological Society of America.

  5. Rapid stalk elongation in tulip (Tulipa gesneriana L. cv. Apeldoorn) and the combined action of cold-induced invertase and the water-channel protein gammaTIP.

    Science.gov (United States)

    Balk, P A; de Boer, A D

    1999-09-01

    Many bulbous plants need a low-temperature treatment for flowering. Cold, for example, affects the elongation of the stalk, thereby influencing the quality of the cut flower. How the elongation of the stalk is promoted by cold and which physiological and biochemical mechanisms are involved have remained obscure. As invertase has been shown to be involved in the cold-induced elongation of the flower stalks of tulips (Lambrechts et al., 1994, Plant Physiol 104: 515-520), we further characterized this enzyme by cloning the cDNA and analysing its expression in various tissues of the tulip (Tulipa gesneriana L. cv. Apeldoorn) stalk. In addition, the role of sucrose synthase was investigated. Since turgor pressure is an important force driving cell elongation, the role of a water-channel protein (gammaTIP) was studied in relation to these two enzymes. The mRNA level of the invertase found was substantially up-regulated as a result of cold treatment. Analysis of the amino acid sequence of this invertase revealed the presence of a vacuolar targeting signal. Two different forms of sucrose synthase were found, the expression of one of them appeared to be restricted to the vascular tissue while the other form was present in the surrounding tissue. Both sucrose synthases were present in the stalk during the entire period of bulb storage and after planting, but their activities declined during stalk elongation. The expression of the gammaTIP gene was restricted mainly to the vascular tissue and its expression profile was identical to that of invertase. Simultaneous expression of invertase and gammaTIP possibly leads to an increase in osmotic potential and vacuolar water uptake, thus providing a driving force for stretching the stalk cells.

  6. Large variation in the Rubisco kinetics of diatoms reveals diversity among their carbon-concentrating mechanisms

    Science.gov (United States)

    Young, Jodi N.; Heureux, Ana M.C.; Sharwood, Robert E.; Rickaby, Rosalind E.M.; Morel, François M.M.; Whitney, Spencer M.

    2016-01-01

    While marine phytoplankton rival plants in their contribution to global primary productivity, our understanding of their photosynthesis remains rudimentary. In particular, the kinetic diversity of the CO2-fixing enzyme, Rubisco, in phytoplankton remains unknown. Here we quantify the maximum rates of carboxylation (k cat c), oxygenation (k cat o), Michaelis constants (K m) for CO2 (K C) and O2 (K O), and specificity for CO2 over O2 (SC/O) for Form I Rubisco from 11 diatom species. Diatom Rubisco shows greater variation in K C (23–68 µM), SC/O (57–116mol mol−1), and K O (413–2032 µM) relative to plant and algal Rubisco. The broad range of K C values mostly exceed those of C4 plant Rubisco, suggesting that the strength of the carbon-concentrating mechanism (CCM) in diatoms is more diverse, and more effective than previously predicted. The measured k cat c for each diatom Rubisco showed less variation (2.1–3.7s−1), thus averting the canonical trade-off typically observed between K C and k cat c for plant Form I Rubisco. Uniquely, a negative relationship between K C and cellular Rubisco content was found, suggesting variation among diatom species in how they allocate their limited cellular resources between Rubisco synthesis and their CCM. The activation status of Rubisco in each diatom was low, indicating a requirement for Rubisco activase. This work highlights the need to better understand the correlative natural diversity between the Rubisco kinetics and CCM of diatoms and the underpinning mechanistic differences in catalytic chemistry among the Form I Rubisco superfamily. PMID:27129950

  7. Health Care Professionals as Victims of Stalking: Characteristics of the Stalking Campaign, Consequences, and Motivation in Italy.

    Science.gov (United States)

    Acquadro Maran, Daniela; Varetto, Antonella; Zedda, Massimo; Franscini, Monica

    2015-07-05

    Stalking is a phenomenon characterized by a set of repetitive behaviors, intrusive surveillance, control, communication, and search of contact with a victim who is afraid and/or worried and/or annoyed by such unwanted attention. Literature analysis shows that Health Care Professionals (HCPs) are at greater risk of being stalked than the general population. As described by Mullen, Pathé, Purcell, and Stuart, stalkers may have different motives: relational rejection, an infatuation, an inability to express their own emotions and recognize those of others, or a desire for revenge. The aim of this study was to explore stalkers' motivation as perceived by their victims, characteristics of stalking campaigns, and consequences. A copy of the Italian modified version of The Network for Surviving Stalking (NSS) Questionnaire on Stalking, the Beck Depression Inventory (BDI) and the State Trait Inventory (STAI) Y1-Y2 scales were distributed in six Italian state hospitals. Participants included 1,842 HCPs, 256 (13.9%) of which had been victims. The majority of victims reported that stalkers were Rejected (96, 37.5%), Intimacy seekers (41, 16%), Incompetent suitors (60, 23.4%), and/or Resentful (43, 16.8%; χ 2 = 163.3, p = .001). Stalking campaigns were characterized by several behaviors, principally contact (by telephone calls, text message) and following. The stalking campaign caused in victims both physical and emotional consequences, the most frequent being weight changes, sleep disorders, weakness, apprehension, anger, and fear. The most used coping strategies were moving away and moving toward, the less used was moving inward. Intervention programs and preventive measures (both individual and organizational) for HCP victims and those who could be considered at risk are also discussed. © The Author(s) 2015.

  8. Selective Predation of a Stalking Predator on Ungulate Prey.

    Directory of Open Access Journals (Sweden)

    Marco Heurich

    Full Text Available Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1 data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly's standardized selection ratio alpha and (2 data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males-the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates.

  9. Structural characterization of lignin from grape stalks (Vitis vinifera L.).

    Science.gov (United States)

    Prozil, Sónia O; Evtuguin, Dmitry V; Silva, Artur M S; Lopes, Luísa P C

    2014-06-18

    The chemical structure of lignin from grape stalks, an abundant waste of winemaking, has been studied. The dioxane lignin was isolated from extractive- and protein-free grape stalks (Vitis vinifera L.) by modified acidolytic procedure and submitted to a structural analysis by wet chemistry (nitrobenzene and permanganate oxidation (PO)) and spectroscopic techniques. The results obtained suggest that grape stalk lignin is an HGS type with molar proportions of p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) units of 3:71:26. Structural analysis by (1)H and (13)C NMR spectroscopy and PO indicates the predominance of β-O-4' structures (39% mol) in grape stalk lignin together with moderate amounts of β-5', β-β, β-1', 5-5', and 4-O-5' structures. NMR studies also revealed that grape lignin should be structurally associated with tannins. The condensation degree of grape stalks lignin is higher than that of conventional wood lignins and lignins from other agricultural residues.

  10. Radiation damage in diatomic materials at high doses

    International Nuclear Information System (INIS)

    Hobbs, L.W.; Hughes, A.E.

    1975-10-01

    Radiation effects in diatomic materials can differ structurally from those in metals because of the need to take into account different displacement rates on the two sublattices and the inevitable stoichiometric implications; in most diatomic insulators the anion species has the greater displacement cross section. Anion point defect stabilisation in heavily-irradiated (0.1 to 10 dpa) diatomic insulators has been studied using radiolysis of alkali and alkaline earth halides. A temperatures > 0.3 Tsub(m), all anion defects are mobile and can aggregate. Aggregation of anion interstitials results in creation of perfect dislocation loops without the need for primary cation displacements; simultaneous formation of substitutional anion molecular centres provides the necessary cation interstitials. Aggregation of anion vacancies leads to formation of metallic inclusions of the cation species, in some cases in an ordered array, which is the analogue, on a single sublattice, to the void lattice in metals. Availability of sinks for both anion interstitials and anion vacancies yields defect growth kinetics similar to those observed during formation of voids in irradiated metals, and a very high level of damage (approximately 10%) can be sustained in the lattice. The width of the temperature region concerned is much narrower, however, due to the possibility of recombination of aggregated or re-emitted anion vacancies with mobile or dispersed anion molecular defects; the latter can also aggregate to form fluid anion molecular inclusions and so complete the decomposition of the solid into separate phases of its constituent elements. (author)

  11. Diatom algae of the Guni river (Pamir)

    International Nuclear Information System (INIS)

    Kurbonova, P.A.; Hisoriev, H.H.

    2006-01-01

    There are presented the dates of the results of diatom algae (Bacillariophyta) of the Gunt river. There was found 107 species and 9 subspecies which belong to 3 classics, 12 ordos, 13 families and 28 genus

  12. Importance of sampling frequency when collecting diatoms

    KAUST Repository

    Wu, Naicheng; Faber, Claas; Sun, Xiuming; Qu, Yueming; Wang, Chao; Ivetic, Snjezana; Riis, Tenna; Ulrich, Uta; Fohrer, Nicola

    2016-01-01

    There has been increasing interest in diatom-based bio-assessment but we still lack a comprehensive understanding of how to capture diatoms’ temporal dynamics with an appropriate sampling frequency (ASF). To cover this research gap, we collected

  13. Analytic vibrational matrix elements for diatomic molecules

    International Nuclear Information System (INIS)

    Bouanich, J.P.; Ogilvie, J.F.; Tipping, R.H.

    1986-01-01

    The vibrational matrix elements and expectation values for a diatomic molecule, including the rotational dependence, are calculated for powers of the reduced displacement in terms of the parameters of the Dunham potential-energy function. (orig.)

  14. Oceanographic and Biogeochemical Insights from Diatom Genomes

    Science.gov (United States)

    Bowler, Chris; Vardi, Assaf; Allen, Andrew E.

    2010-01-01

    Diatoms are the most successful group of eukaryotic phytoplankton in the modern ocean and have risen to dominance relatively quickly over the last 100 million years. Recently completed whole genome sequences from two species of diatom, Thalassiosira pseudonana and Phaeodactylum tricornutum, have revealed a wealth of information about the evolutionary origins and metabolic adaptations that have led to their ecological success. A major finding is that they have incorporated genes both from their endosymbiotic ancestors and by horizontal gene transfer from marine bacteria. This unique melting pot of genes encodes novel capacities for metabolic management, for example, allowing the integration of a urea cycle into a photosynthetic cell. In this review we show how genome-enabled approaches are being leveraged to explore major phenomena of oceanographic and biogeochemical relevance, such as nutrient assimilation and life histories in diatoms. We also discuss how diatoms may be affected by climate change-induced alterations in ocean processes.

  15. Body Stalk Anomaly in a 9-Week Pregnancy

    Directory of Open Access Journals (Sweden)

    Fabio E. Quijano

    2014-01-01

    Full Text Available Body stalk anomaly is a rare and severe malformation syndrome in which the exact pathophysiology and trigger factors are still unknown. This is a case of a 30-year-old patient who underwent ultrasound at 9 weeks of gestation. It revealed an abnormal location of the inferior body of the embryo in the coelomic space. The findings suggested a short umbilical cord syndrome. In order to confirm the diagnosis, the patient was scheduled for a second ultrasonography at 11 weeks of gestation. The obtained images, confirmed the location of the inferior body in the coelomic space with no visible bladder, absence of the right leg, severe abdominal wall defect, consistent with an omphalocele, and a short 5 mm umbilical cord. These last ultrasonographic findings were consistent with body stalk anomaly. Because of severe malformation incompatible with life, the patient was offered termination of pregnancy. Pathologic examination confirmed the suspected pathology of body stalk anomaly.

  16. The C-terminal helix of ribosomal P stalk recognizes a hydrophobic groove of elongation factor 2 in a novel fashion.

    Science.gov (United States)

    Tanzawa, Takehito; Kato, Koji; Girodat, Dylan; Ose, Toyoyuki; Kumakura, Yuki; Wieden, Hans-Joachim; Uchiumi, Toshio; Tanaka, Isao; Yao, Min

    2018-04-06

    Archaea and eukaryotes have ribosomal P stalks composed of anchor protein P0 and aP1 homodimers (archaea) or P1•P2 heterodimers (eukaryotes). These P stalks recruit translational GTPases to the GTPase-associated center in ribosomes to provide energy during translation. The C-terminus of the P stalk is known to selectively recognize GTPases. Here we investigated the interaction between the P stalk and elongation factor 2 by determining the structures of Pyrococcus horikoshii EF-2 (PhoEF-2) in the Apo-form, GDP-form, GMPPCP-form (GTP-form), and GMPPCP-form bound with 11 C-terminal residues of P1 (P1C11). Helical structured P1C11 binds to a hydrophobic groove between domain G and subdomain G' of PhoEF-2, where is completely different from that of aEF-1α in terms of both position and sequence, implying that such interaction characteristic may be requested by how GTPases perform their functions on the ribosome. Combining PhoEF-2 P1-binding assays with a structural comparison of current PhoEF-2 structures and molecular dynamics model of a P1C11-bound GDP form, the conformational changes of the P1C11-binding groove in each form suggest that in response to the translation process, the groove has three states: closed, open, and release for recruiting and releasing GTPases.

  17. Diatom-Specific Oligosaccharide and Polysaccharide Structures Help to Unravel Biosynthetic Capabilities in Diatoms

    Directory of Open Access Journals (Sweden)

    Bruno Gügi

    2015-09-01

    Full Text Available Diatoms are marine organisms that represent one of the most important sources of biomass in the ocean, accounting for about 40% of marine primary production, and in the biosphere, contributing up to 20% of global CO2 fixation. There has been a recent surge in developing the use of diatoms as a source of bioactive compounds in the food and cosmetic industries. In addition, the potential of diatoms such as Phaeodactylum tricornutum as cell factories for the production of biopharmaceuticals is currently under evaluation. These biotechnological applications require a comprehensive understanding of the sugar biosynthesis pathways that operate in diatoms. Here, we review diatom glycan and polysaccharide structures, thus revealing their sugar biosynthesis capabilities.

  18. The genome of the diatom Thalassiosira pseudonana: Ecology,evolution, and metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Ambrust, E.V.; Berges, J.; Bowler, C.; Green, B.; Martinez, D.; Putnam, N.; Zhou, S.; Allen, A.; Apt, K.; Bechner, M.; Brzezinski, M.; Chaal, B.; Chiovitti, A.; Davis, A.; Goodstein, D.; Hadi, M.; Hellsten,U.; Hildebrand, M.; Jenkins, B.; Jurka, J.; Kapitonov, V.; Kroger, N.; Lau, W.; Lane, T.; Larimer, F.; Lippmeier, J.; Lucas, S.; Medina, M.; Montsant, A.; Obornik, M.; Parker, M. Schnitzler; Palenik, B.; Pazour,G.; Richardson, P.; Rynearson, T.; Saito, M.; Schwartz, D.; Thamatrakoln,K.; Valentin, K.; Vardi, A.; Wilkerson, F.; Rokhsar, D.; Vardi, A.; Wilkerson, F.P.; Rokhsar, D.S.

    2004-09-01

    Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for {approx}20% of global carbon fixation. We report the 34 Mbp draft nuclear genome of the marine diatom, Thalassiosira pseudonana and its 129 Kbp plastid and 44 Kbp mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, utilization of a range of nitrogenous compounds and a complete urea cycle, all attributes that allow diatoms to prosper in the marine environment. Diatoms are unicellular, photosynthetic, eukaryotic algae found throughout the world's oceans and freshwater systems. They form the base of short, energetically-efficient food webs that support large-scale coastal fisheries. Photosynthesis by marine diatoms generates as much as 40% of the 45-50 billion tonnes of organic carbon produced each year in the sea (1), and their role in global carbon cycling is predicted to be comparable to that of all terrestrial rainforests combined (2, 3). Over geological time, diatoms may have influenced global climate by changing the flux of atmospheric carbon dioxide into the oceans (4). A defining feature of diatoms is their ornately patterned silicified cell wall or frustule, which displays species-specific nano-structures of such fine detail that diatoms have long been used to test the resolution of optical microscopes. Recent attention has focused on biosynthesis of these nano-structures as a paradigm for future silica nanotechnology (5). The long history (over 180 million years) and dominance of diatoms in the oceans is reflected by their contributions to vast deposits of diatomite, most cherts and a significant fraction of current petroleum reserves (6). As photosynthetic heterokonts, diatoms reflect a fundamentally

  19. Pituitary stalk compression by the dorsum sellae: possible cause for late childhood onset growth disorders.

    Science.gov (United States)

    Taoka, Toshiaki; Iwasaki, Satoru; Okamoto, Shingo; Sakamoto, Masahiko; Nakagawa, Hiroyuki; Otake, Shoichiro; Fujioka, Masayuki; Hirohashi, Shinji; Kichikawa, Kimihiko

    2006-06-01

    The purpose of this study was to evaluate the relationship between pituitary stalk compression by the dorsum sellae and clinical or laboratory findings in short stature children. We retrospectively reviewed magnetic resonance images of the pituitary gland and pituitary stalk for 34 short stature children with growth hormone (GH) deficiency and 24 age-matched control cases. We evaluated the degree of pituitary stalk compression caused by the dorsum sellae. Body height, GH level, pituitary height and onset age of the short stature were statistically compared between cases of pituitary stalk compression with associated stalk deformity and cases without compression. Compression of the pituitary stalk with associated stalk deformity was seen in nine cases within the short stature group. There were no cases observed in the control group. There were no significant differences found for body height, GH level and pituitary height between the cases of pituitary stalk compression with associated stalk deformity and cases without compression. However, a significant difference was seen in the onset age between cases with and without stalk compression. Pituitary stalk compression with stalk deformity caused by the dorsum sellae was significantly correlated with late childhood onset of short stature.

  20. Energy transfer in diatom/diatom molecular collisions

    International Nuclear Information System (INIS)

    Sohlberg, K.W.

    1992-01-01

    In a collision of two molecules, the translational energy of the collision may be redistributed into internal energy of rotation, vibration, or electron motion, in one or both of the colliding partners. In addition, internal energy in one or more of these modes may be open-quotes quenchedclose quotes into translation, leading to a superelastic collision. Such energy transfer may take place by a number of mechanisms. This energy transfer is of fundamental importance in understanding chemical reaction dynamics. Nearly all chemical reactions take place through a bimolecular collision process (or multiple bimolecular collisions) and the quantum state specificity of the reaction can have a major role in determining the kinetics of the reaction, In particular, the author has investigated vibrational energy transfer in collisions between two diatomic molecules. In addition to serving as models for all molecular collision process, gas phase collisions of these species are ubiquitous in atmospheric phenomena which are of critical importance in answering the current questions about the human induced degradation of the earth's atmospheric. Classical trajectory methods have been used to explore the excitation of vibrations in gas-phase collisions of the nitrogen molecular ion with its parent molecule. The near symmetry of the reactants is shown to result in a high probability that the two molecules are excited by an equal amount of energy. This provides a possible explanation of the molecular beam measurements which show that the total number of vibrational energy quanta excited in the collision is, with a high probability that the two molecules are excited by an equal amount of energy. This provides a possible explanation of the molecular beam measurements which show that the total number of vibrational energy quanta excited in the collision is, with a high probability, even

  1. Diatom Stratigraphy of FA-1 Core, Qarun Lake, Records of Holocene Environmental and Climatic Change in Faiyum Oasis, Egypt

    Directory of Open Access Journals (Sweden)

    Zalat Abdelfattah A.

    2017-06-01

    Full Text Available This study evaluates changes in the environmental and climatic conditions in the Faiyum Oasis during the Holocene based on diatom analyses of the sediment FA-1 core from the southern seashore of the Qarun Lake. The studied FA-1 core was 26 m long and covered the time span ca. 9.000 cal. yrs BP. Diatom taxa were abundant and moderately to well-preserved throughout the core sediments. Planktonic taxa were most abundant than the benthic and epiphytic forms, which were very rare and sparsely distributed. The most dominant planktonic genera were Aulacoseira and Stephanodiscus followed by frequently distribution of Cyclostephanos and Cyclotella species. The stratigraphic distribution patterns of the recorded diatoms through the Holocene sediments explained five ecological diatom groups. These groups represent distinctive environmental conditions, which were mainly related to climatic changes through the early and middle Holocene, in addition to anthropogenic activity during the late Holocene. Comparison of diatom assemblages in the studied sediment core suggests that considerable changes occurred in water level as well as salinity. There were several high stands of the freshwater lake level during humid, warmer-wet climatic phases marked by dominance of planktonic, oligohalobous and alkaliphilous diatoms alternated with lowering of the lake level and slight increases in salinity and alkalinity during warm arid conditions evident by prevalence of brackish water diatoms.

  2. Complex dynamics in diatomic molecules. Part II: Quantum trajectories

    International Nuclear Information System (INIS)

    Yang, C.-D.; Weng, H.-J.

    2008-01-01

    The second part of this paper deals with quantum trajectories in diatomic molecules, which has not been considered before in the literature. Morse potential serves as a more accurate function than a simple harmonic oscillator for illustrating a realistic picture about the vibration of diatomic molecules. However, if we determine molecular dynamics by integrating the classical force equations derived from a Morse potential, we will find that the resulting trajectories do not consist with the probabilistic prediction of quantum mechanics. On the other hand, the quantum trajectory determined by Bohmian mechanics [Bohm D. A suggested interpretation of the quantum theory in terms of hidden variable. Phys. Rev. 1952;85:166-179] leads to the conclusion that a diatomic molecule is motionless in all its vibrational eigen-states, which also contradicts probabilistic prediction of quantum mechanics. In this paper, we point out that the quantum trajectory of a diatomic molecule completely consistent with quantum mechanics does exist and can be solved from the quantum Hamilton equations of motion derived in Part I, which is based on a complex-space formulation of fractal spacetime [El Naschie MS. A review of E-Infinity theory and the mass spectrum of high energy particle physics. Chaos, Solitons and Fractals 2004;19:209-36; El Naschie MS. E-Infinity theory - some recent results and new interpretations. Chaos, Solitons and Fractals 2006;29:845-853; El Naschie MS. The concepts of E-infinity. An elementary introduction to the cantorian-fractal theory of quantum physics. Chaos, Solitons and Fractals 2004;22:495-511; El Naschie MS. SU(5) grand unification in a transfinite form. Chaos, Solitons and Fractals 2007;32:370-374; Nottale L. Fractal space-time and microphysics: towards a theory of scale relativity. Singapore: World Scientific; 1993; Ord G. Fractal space time and the statistical mechanics of random works. Chaos, Soiltons and Fractals 1996;7:821-843] approach to quantum

  3. Characteristic and kinetics of corn stalk pyrolysis in a high pressure reactor and steam gasification of its char

    OpenAIRE

    Zhang, Guojie; Sun, Yinghui; Shi, Yuliang; Jia, Yong; Xu, Ying; Zhao, Peiyu; Zhang, Yongfa

    2016-01-01

    Pyrolysis characteristics of the corn stalk were investigated at different temperatures and pressures, with focus mainly on the releasing profiles and forming behaviors of gas. The results show that a higher pressure was conducive to the yield of H2 and CH4, and was not conducive to the generation of CO. Combustible gas components increase with the increase temperature. H2 concentration was affected significantly by temperature, was mainly released at higher temperatures (>500 °C). At 700 °C,...

  4. Shift of the pituitary stalk in intrasellar pituitary adenomas

    International Nuclear Information System (INIS)

    Ito, Jusuke; Tokiguchi, Susumu; Nakamori, Akitoshi; Watanabe, Akira; Yokoyama, Motoharu.

    1982-01-01

    Fifty-one patients from a group of 344 patients undergoing the evaluation of intrasellar or parasellar tumors were diagnosed on CT as having an intrasellar pituitary adenoma. Axial transverse sections were performed at -10 0 to Reid's basal line, using 1.5-mm-thick slices and sagittal and coronal reformation. Of these 51 patients, 17 showed a shift of the pituitary stalk. The area where a tumor was thought to be located within the sella turcica on preoperative CT became defective on CT after transsphenoidal surgery in all cases. Histological verification was obtained in all cases. Also, the shift of the pituitary stalk was normalized or markedly improved after surgery in all cases. In functioning tumors, all cases except two showed an endocrinologically normal state or a marked improvement after transsphenoidal surgery. On the basis of the above-mentioned facts, it was concluded that the shift of the pituitary stalk in intrasellar pituitary adenomas indicated the evidence of a mass and its location in the sella turcica. However, a shift of the pituitary stalk was also observed under other conditions, such as empty sella and tuberculum sellae meningioma, and so it is not a pathognomonic finding in intrasellar pituitary adenomas. (author)

  5. The Reliability and Predictive Validity of the Stalking Risk Profile.

    Science.gov (United States)

    McEwan, Troy E; Shea, Daniel E; Daffern, Michael; MacKenzie, Rachel D; Ogloff, James R P; Mullen, Paul E

    2018-03-01

    This study assessed the reliability and validity of the Stalking Risk Profile (SRP), a structured measure for assessing stalking risks. The SRP was administered at the point of assessment or retrospectively from file review for 241 adult stalkers (91% male) referred to a community-based forensic mental health service. Interrater reliability was high for stalker type, and moderate-to-substantial for risk judgments and domain scores. Evidence for predictive validity and discrimination between stalking recidivists and nonrecidivists for risk judgments depended on follow-up duration. Discrimination was moderate (area under the curve = 0.66-0.68) and positive and negative predictive values good over the full follow-up period ( Mdn = 170.43 weeks). At 6 months, discrimination was better than chance only for judgments related to stalking of new victims (area under the curve = 0.75); however, high-risk stalkers still reoffended against their original victim(s) 2 to 4 times as often as low-risk stalkers. Implications for the clinical utility and refinement of the SRP are discussed.

  6. Enhanced ethanol production from stalk juice of sweet sorghum by ...

    African Journals Online (AJOL)

    Sweet sorghum (sugar sorghum, Sorghum bicolor) is one kind of non-grain energy crops. As a novel green regenerated high-energy crop with high utility value, high yield of biomass, the sweet sorghum is widely used and developed in China. Stalk juice of sweet sorghum was used as the main substrate for ethanol ...

  7. Deactivation of tannins in raisin stalk by polyethylene glycol-600 ...

    African Journals Online (AJOL)

    6000) and urea on dry and organic matter digestibility (IVDMD and IVOMD, respectively) and gas production in vitro. Raisin stalk contained 8.6% crude protein, 85% dry matter, 7% ash, 13.95% total extractable phenol (TEPH) and 2.13% total ...

  8. Comparative Study of Root, Stalk and Leaf Essential Oils of ...

    African Journals Online (AJOL)

    MBI

    2017-03-03

    Mar 3, 2017 ... ABSTRACT. The root, stalk and leaf essential oils of Cymbopogon citratus grown in Kaduna, North Central Nigeria were extracted separately by hydrodistillation and characterized by GC-MS. The chemical composition analysis by. GC-MS of the oils allowed the identification of 34, 26 and 16 compounds ...

  9. Stalking on Campus: Ensuring Security with Rights and Liberties

    Science.gov (United States)

    Campbell, Julie; Longo, Peter J.

    2010-01-01

    College campuses are often perceived as idyllic communities. While there is much truth in such perceptions, not surprisingly there are many complicated issues on college campuses. Stalking is one such problem that seems to persist and thrive in the cloistered college setting. Campus safety efforts must temper security practices with civil rights…

  10. Evaluation of cotton stalk hydrolysate for xylitol production.

    Science.gov (United States)

    Sapcı, Burcu; Akpinar, Ozlem; Bolukbasi, Ufuk; Yilmaz, Levent

    2016-07-03

    Cotton stalk is a widely distributed and abundant lignocellulosic waste found in Turkey. Because of its rich xylose content, it can be a promising source for the production of xylitol. Xylitol can be produced by chemical or biotechnological methods. Because the biotechnological method is a simple process with great substrate specificity and low energy requirements, it is more of an economic alternative for the xylitol production. This study aimed to use cotton stalk for the production of xylitol with Candida tropicalis Kuen 1022. For this purpose, the combined effects of different oxygen concentration, inoculum level and substrate concentration were investigated to obtain high xylitol yield and volumetric xylitol production rate. Candida tropicalis Kuen 1022 afforded different concentrations of xylitol depending on xylose concentration, inoculum level, and oxygen concentration. The optimum xylose, yeast concentration, and airflow rate for cotton stalk hydrolysate were found as 10.41 g L(-1), 0.99 g L(-1), and 1.02 vvm, respectively, and under these conditions, xylitol yield and volumetric xylitol production rate were obtained as 36% and 0.06 g L(-1) hr(-1), respectively. The results of this study show that cotton stalk can serve as a potential renewable source for the production of xylitol.

  11. 77 FR 211 - National Stalking Awareness Month, 2012

    Science.gov (United States)

    2012-01-03

    ..., tragically, stalking can be a precursor to more violent offenses, including sexual assault and homicide. The... Federal agencies, we are promoting new tools to decrease the incidence of domestic violence, sexual... and harmful behavior. This month, let us come together to prevent abuse, violence, and harassment in...

  12. Fabrication of insulator nanocapillaries from diatoms

    International Nuclear Information System (INIS)

    Bereczky, R.J.; Tokesi, K.

    2006-01-01

    Complete text of publication follows. Diatoms are unicellular microscopic organisms with silicon-dioxide based skeleton enveloped with an organic material, which composes essentially polysaccharides and proteins (see Fig. 1a.). As it was shown, the valva of the diatoms build up almost from clean silicondioxide [1]. Therefore, removing the organic compounds from the diatom, we can have in our hand an ideal, about 100 μ m-sized, and almost cylindrical shaped insulating nanostructure. There are various techniques available to disembarrass the diatom from its organic compounds. We used the so called hydrogen peroxide method. The advantageous properties of this method are the followings: a) this is one of the fastest procedures among the possible methods, b) do not require special equipment, c) cheap, and last but not least it is less harmful for health compared to other methods. This procedure can be an alternative way of the fabrication of insulator nanocapillaries. In this case the preparation of the nanocapillaries is simple and quick. Moreover, we do not need to invest expensive special techniques, (like micromachining-, electrochemical etching technique, moulding process etc) as it was necessary for the case of previously developed method producing insulator nanocapillaries [2,3]. Fig. 1b and Fig. 1c. show the scanning electron micrograph of the skeleton of the diatoms. The size of the cylindrical holes are roughly 200 nm (see Fig. 1c). (author)

  13. Needle knife-assisted endoscopic polypectomy for a large inflammatory fibroid colon polyp by making its stalk into an omega shape using an endoloop.

    Science.gov (United States)

    Kim, Byung Chang; Cheon, Jae Hee; Lee, Sang Kil; Kim, Tae Il; Kim, Hoguen; Kim, Won Ho

    2008-08-30

    Colonic inflammatory fibroid polyp (IFP) is an uncommon benign polypoid lesion, which is composed of fibroblasts, numerous small vessels and edematous connective tissue with marked eosinophilic inflammatory cell infiltration. This condition is frequently detected in the stomach and small intestine, but uncommon in the colon. Although IFP is a benign lesion, surgical resections are performed in most colonic cases because the polyps are usually too large to resect endoscopically. Only three patients underwent endoscopic polypectomy in our literature reviews. Here, we present a case of IFP in the descending colon successful endoscopically resected using a novel technique of trapping its stalk with an endoloop, forming the stalk into an omega shape, and then dissecting the stalk with a needle knife.

  14. Two unusual causes of pituitary stalk thickening in children without clinical features of diabetes insipidus

    International Nuclear Information System (INIS)

    Andronikou, Savvas; Furlan, Gisella; Fieggen, Anthony G.; Wilmshurst, Jo

    2003-01-01

    Pituitary stalk thickening has a wide differential diagnosis, but almost all infundibular diseases present with diabetes insipidus (DI). We present a child with metastatic involvement of the pituitary stalk from a primary pontine tumour and a child with tuberculous infiltration of the pituitary stalk and associated meningeal inflammation. Neither child presented with DI. Even though both metastatic disease and tuberculous infiltration of the stalk have been reported in adults, these are the first reports with accompanying cross-sectional images of pituitary stalk involvement by these diseases in children. (orig.)

  15. Two unusual causes of pituitary stalk thickening in children without clinical features of diabetes insipidus

    Energy Technology Data Exchange (ETDEWEB)

    Andronikou, Savvas; Furlan, Gisella; Fieggen, Anthony G.; Wilmshurst, Jo [Department of Paediatric Neuroradiology, University of Cape Town, Klipfontein Road, 7700, Rondebosch, Cape Town (South Africa); Cross War Memorial Children' s Hospital, University of Cape Town, Klipfontein Road, 7700, Rondebosch, Cape Town (South Africa); School of Child and Adolescent Health, University of Cape Town, Klipfontein Road, 7700, Rondebosch, Cape Town (South Africa)

    2003-07-01

    Pituitary stalk thickening has a wide differential diagnosis, but almost all infundibular diseases present with diabetes insipidus (DI). We present a child with metastatic involvement of the pituitary stalk from a primary pontine tumour and a child with tuberculous infiltration of the pituitary stalk and associated meningeal inflammation. Neither child presented with DI. Even though both metastatic disease and tuberculous infiltration of the stalk have been reported in adults, these are the first reports with accompanying cross-sectional images of pituitary stalk involvement by these diseases in children. (orig.)

  16. Quantification of diatoms in biofilms: Standardisation of methods

    Digital Repository Service at National Institute of Oceanography (India)

    Patil, J.S.; Anil, A.C.

    of the difficulty in sampling and enumeration. Scraping or brushing are the traditional methods used for removal of diatoms from biofilms developed on solid substrata. The method of removal is the most critical step in enumerating the biofilm diatom community...

  17. 9 Records of Diatoms and Physicochemical.cdr

    African Journals Online (AJOL)

    Administrator

    between some physicochemical parameters and diatom species in these ponds. ..... Diversity and relative abundance (%) of diatoms species in selected seasonal ponds in Zaria, Nigeria ..... connection with reference conditions of the water.

  18. Preparation and method of study of fossil diatoms

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    Two methods of chemical concentration of diatoms occurring in fresh-water sediments, and one chemico-mechanical method of concentration for diatoms occurring in marine sediments are outlined, with emphasis on the extreme care that needs...

  19. Diatoms: a fossil fuel of the future.

    Science.gov (United States)

    Levitan, Orly; Dinamarca, Jorge; Hochman, Gal; Falkowski, Paul G

    2014-03-01

    Long-term global climate change, caused by burning petroleum and other fossil fuels, has motivated an urgent need to develop renewable, carbon-neutral, economically viable alternatives to displace petroleum using existing infrastructure. Algal feedstocks are promising candidate replacements as a 'drop-in' fuel. Here, we focus on a specific algal taxon, diatoms, to become the fossil fuel of the future. We summarize past attempts to obtain suitable diatom strains, propose future directions for their genetic manipulation, and offer biotechnological pathways to improve yield. We calculate that the yields obtained by using diatoms as a production platform are theoretically sufficient to satisfy the total oil consumption of the US, using between 3 and 5% of its land area. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Mediators and Moderators of the Association Between Stalking Victimization and Psychological Distress.

    Science.gov (United States)

    Fais, Connor R; Lutz-Zois, Catherine J; Goodnight, Jackson A

    2017-03-01

    The current study aims to understand mediators and moderators of the relationship between stalking victimization and depression. Based on the reformulated learned helplessness theory, which emphasizes the role of internal, global, and stable attributions for negative events in the development of depression, we predicted that the association between stalking victimization and depression would be mediated by attributions for the stalking and characterological self-blame. We predicted that the association between stalking victimization and helplessness attributions or characterological self-blame, in turn, would be moderated by gender, sex-role identity, and length of stalking. Specifically, we hypothesized that female victims, victims possessing a feminine sex-role identity, and victims experiencing longer stalking episodes would be more likely to experience depression in comparison with male victims, victims possessing a masculine sex-role identity, and victims experiencing shorter stalking episodes. The results indicated that global attributions for the cause of stalking significantly mediated the relationship between stalking victimization and depression. The results for stable attributions, internal attributions, and characterological self-blame were nonsignificant. Furthermore, gender, sex-role identity, and length of stalking did not moderate the association between stalking and attributional style or characterological self-blame. The implications of these findings and directions for future research are discussed.

  1. Stalking by patients: doctors' experiences in a Canadian urban area (Part II)--physician responses.

    Science.gov (United States)

    Abrams, Karen M; Robinson, Gail Erlick

    2013-07-01

    Stalking involves recurrent unwanted communication, harassment, and intrusive behaviors. The aim of this study was to examine physicians' experiences of being stalked by their patients, with particular attention to the emotional impact on the physicians and their actions taken. A questionnaire designed to study the nature and the impact of stalking experiences among physicians was sent to 3159 randomly chosen physicians in the Greater Toronto Area. Approximately 15% (14.9%) of the 1190 physicians who responded reported having been stalked. The physicians reported feeling angry, frustrated, anxious, frightened, lacking control, and helpless. The physicians coped in a number of ways including terminating the physician-patient relationship, but many just ignored the problem. Most had no previous knowledge about stalking. Physicians experience a range of emotions as a result of being a victim of stalking. In view of the prevalence and the impact, physicians may benefit from education to help prepare them for the possibility of being stalked.

  2. Relationship of the Williams-Poulios and Manning-Rosen Potential Energy Models for Diatomic Molecules

    Science.gov (United States)

    Jia, Chun-Sheng; Liang, Guang-Chuan; Peng, Xiao-Long; Tang, Hong-Ming; Zhang, Lie-Hui

    2014-06-01

    By employing the dissociation energy and the equilibrium bond length for a diatomic molecule as explicit parameters, we generate an improved form of the Williams-Poulios potential energy model. It is found that the negative Williams-Poulios potential model is equivalent to the Manning-Rosen potential model for diatomic molecules. We observe that the Manning-Rosen potential is superior to the Morse potential in reproducing the interaction potential energy curves for the {{a}3 Σu+} state of the 6Li2 molecule and the {{X}1 sum+} state of the SiF+ molecule.

  3. Diatoms in Liyu Lake, Eastern Taiwan

    Directory of Open Access Journals (Sweden)

    Liang-Chi Wang

    2010-09-01

    Full Text Available This study described the diatoms appeared in the sediments of Liyu Lake, a lowland natural lake situated at Hualen, eastern Taiwan. A total of 50 species was found in the sediments of this eutrophic lake. In them, 8 species were reported for the first time in Taiwan. They are: Cymbella thienemannii, Navicula absoluta, Navicula bacillum, Frustulia rhomboides var. crassinervia, Gyrosigma procerum, Nitzschia paleacea Epithemia smithii and Eunotia subarcuatioides. The ultrastructures of each species were described on the basis of observations under a scanning electron microscope. The ecological implications of the occurrence of these diatom species in this lake were inferred.

  4. Dinoflagellate blooms in upwelling systems: Seeding, variability, and contrasts with diatom bloom behaviour

    Science.gov (United States)

    Smayda, T. J.; Trainer, V. L.

    2010-04-01

    The influence of diatom bloom behaviour, dinoflagellate life cycles, propagule type and upwelling bloom cycles on the seeding of dinoflagellate blooms in eastern boundary current upwelling systems is evaluated. Winter-spring diatom bloom behaviour is contrasted with upwelling bloom behaviour because their phenology impacts dinoflagellate blooms. The winter-spring diatom bloom is usually sustained, whereas the classical upwelling diatom bloom occurs as a series of separate, recurrent mini-blooms intercalated by upwelling-relaxation periods, during which dinoflagellates often bloom. Four sequential wind-regulated phases characterize upwelling cycles, with each phase having different effects on diatom and dinoflagellate bloom behaviour: bloom “spin up”, bloom maximum, bloom “spin down”, and upwelling relaxation. The spin up - bloom maximum is the period of heightened diatom growth; the spin down - upwelling-relaxation phases are the periods when dinoflagellates often bloom. The duration, intensity and ratio of the upwelling and relaxation periods making up upwelling cycles determine the potential for dinoflagellate blooms to develop within a given upwelling cycle and prior to the subsequent “spin up” of upwelling that favours diatom blooms. Upwelling diatoms and meroplanktonic dinoflagellates have three types of propagules available to seed blooms: vegetative cells, resting cells and resting cysts. However, most upwelling dinoflagellates are holoplanktonic, which indicates that the capacity to form resting cysts is not an absolute requirement for growth and survival in upwelling systems. The long-term (decadal) gaps in bloom behaviour of Gymnodinium catenatum and Lingulodinium polyedrum, and the unpredictable bloom behaviour of dinoflagellates generally, are examined from the perspective of seeding strategies. Mismatches between observed and expected in situ bloom behaviour and resting cyst dynamics are common among upwelling dinoflagellates. This

  5. Response of the Ubiquitous Pelagic Diatom Thalassiosira weissflogii i>to Darkness and Anoxia

    DEFF Research Database (Denmark)

    Kamp, Anja; Stief, Peter; Knappe, Jan

    2013-01-01

    Thalassiosira weissflogii, an abundant, nitrate-storing, bloom-forming diatom in the world's oceans, can use its intracellular nitrate pool for dissimilatory nitrate reduction to ammonium (DNRA) after sudden shifts to darkness and anoxia, most likely as a survival mechanism. T. weissflogii cells ...

  6. Hundred years of genetic structure in a sediment revived diatom population

    DEFF Research Database (Denmark)

    Haernstroem, Karolina; Ellegaard, Marianne; Andersen, Thorbjørn Joest

    2011-01-01

    This paper presents research on the genetic structure and diversity of populations of a common marine protist and their changes over time. The bloom-forming diatom Skeletonema marinoi was used as a model organism. Strains were revived from anoxic discrete layers of a 210Pb-dated sediment core...

  7. The amino terminal end determines the stability and assembling capacity of eukaryotic ribosomal stalk proteins P1 and P2.

    Science.gov (United States)

    Camargo, Hendricka; Nusspaumer, Gretel; Abia, David; Briceño, Verónica; Remacha, Miguel; Ballesta, Juan P G

    2011-05-01

    The eukaryotic ribosomal proteins P1 and P2 bind to protein P0 through their N-terminal domain to form the essential ribosomal stalk. A mutational analysis points to amino acids at positions 2 and 3 as determinants for the drastic difference of Saccharomyces cerevisiae P1 and P2 half-life, and suggest different degradation mechanisms for each protein type. Moreover, the capacity to form P1/P2 heterodimers is drastically affected by mutations in the P2β four initial amino acids, while these mutations have no effect on P1β. Binding of P2β and, to a lesser extent, P1β to the ribosome is also seriously affected showing the high relevance of the amino acids in the first turn of the NTD α-helix 1 for the stalk assembly. The negative effect of some mutations on ribosome binding can be reversed by the presence of the second P1/P2 couple in the ribosome, indicating a stabilizing structural influence between the two heterodimers. Unexpectedly, some mutations totally abolish heterodimer formation but allow significant ribosome binding and, therefore, a previous P1 and P2 association seems not to be an absolute requirement for stalk assembly. Homology modeling of the protein complexes suggests that the mutated residues can affect the overall protein conformation. © The Author(s) 2011. Published by Oxford University Press.

  8. Epibiotic Diatoms Are Universally Present on All Sea Turtle Species

    Science.gov (United States)

    Majewska, Roksana; Lazo-Wasem, Eric A.; Nel, Ronel; Paladino, Frank V.; Rojas, Lourdes; Zardus, John D.; Pinou, Theodora

    2016-01-01

    The macro-epibiotic communities of sea turtles have been subject to growing interest in recent years, yet their micro-epibiotic counterparts are almost entirely unknown. Here, we provide the first evidence that diatoms are epibionts for all seven extant species of sea turtle. Using Scanning Electron Microscopy, we inspected superficial carapace or skin samples from a single representative of each turtle species. We distinguished 18 diatom taxa from these seven individuals, with each sea turtle species hosting at least two diatom taxa. We recommend that future research is undertaken to confirm whether diatom communities vary between sea turtle species and whether these diatom taxa are facultative or obligate commensals. PMID:27257972

  9. Electron transport through a diatomic molecule

    International Nuclear Information System (INIS)

    Imran, Muhammad

    2014-01-01

    Electron transport through a diatomic molecular tunnel junction shows wave like interference phenomenon. By using Keldysh non-equilibrium Green's function (NEGF) theory, we have explicitly presented current and differential conductance calculation for a diatomic molecular and two isolated atoms (two atoms having zero hybridization between their energy orbitals) tunnel junctions. In case of a diatomic molecular tunnel junction, Green's function propagators entering into current and differential conductance formula interfere constructively for a molecular anti-bonding state and destructively for bonding state. Consequently, conductance through a molecular bonding state is suppressed, and to conserve current, conductance through anti-bonding state is enhanced. Therefore, current steps and differential conductance peaks amplitude show asymmetric correspondence between molecular bonding and anti-bonding states. Interestingly, for a diatomic molecule, comprising of two atoms of same energy level, these propagators interfere completely destructively for molecular bonding state and constructively for molecular anti-bonding state. Hence under such condition, a single step or a single peak is shown up in current versus voltage or differential conductance versus voltage studies.

  10. Genetic and metabolic engineering in diatoms.

    Science.gov (United States)

    Huang, Weichao; Daboussi, Fayza

    2017-09-05

    Diatoms have attracted considerable attention due to their success in diverse environmental conditions, which probably is a consequence of their complex origins. Studies of their metabolism will provide insight into their adaptation capacity and are a prerequisite for metabolic engineering. Several years of investigation have led to the development of the genome engineering tools required for such studies, and a profusion of appropriate tools is now available for exploring and exploiting the metabolism of these organisms. Diatoms are highly prized in industrial biotechnology, due to both their richness in natural lipids and carotenoids and their ability to produce recombinant proteins, of considerable value in diverse markets. This review provides an overview of recent advances in genetic engineering methods for diatoms, from the development of gene expression cassettes and gene delivery methods, to cutting-edge genome-editing technologies. It also highlights the contributions of these rapid developments to both basic and applied research: they have improved our understanding of key physiological processes; and they have made it possible to modify the natural metabolism to favour the production of specific compounds or to produce new compounds for green chemistry and pharmaceutical applications.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

  11. Clinical and radiological features of pituitary stalk lesions in children and adolescents

    Directory of Open Access Journals (Sweden)

    Sung Chul Yoon

    2014-12-01

    Full Text Available PurposeThe diagnosis of pituitary stalk lesion has been based on clinical feature, radiologic assessment for its critical location and role. This study aimed to investigate clinical symptoms, endocrine disturbance, magnetic resonance imaging (MRI findings of pituitary stalk lesions in children and adolescents and to evaluate differences between neoplastic lesions with the others.MethodsWe performed a retrospective review of patients under 18 years old with pituitary stalk lesions diagnosed at the Seoul National University Children's Hospital between 2000 and 2013, by a text search for head MRI reports by using 'pituitary stalk', 'infundibulum', and 'infundibular stalk', as keywords.ResultsFor the 76 patients, sixteen patients (21.1% had congenital lesions, and 52 (68.4% had neoplasms. No inflammatory lesions were found. Diabetes insipidus (DI was the most common endocrine defect, diagnosed in 38 patients (50%. There was male predominance especially in neoplastic group. Thickened pituitary stalk was, but enhancement of lesion was not, associated with neoplasm. DI was more prevalent in neoplastic stalk lesions. Anterior pituitary dysfunction such as growth hormone and adrenocorticotropic hormone deficiencies were less prevalent in neoplastic lesions of pituitary stalk.ConclusionIn conclusion, the etiology of pituitary stalk lesions in children and adolescents is diverse and different from that in adults. Neoplastic pituitary stalk lesions can be differentiated from nonneoplastic lesions by systemic evaluation of clinical, hormonal, radiological findings.

  12. Phenolic Compounds Analysis of Root, Stalk, and Leaves of Nettle

    Directory of Open Access Journals (Sweden)

    Semih Otles

    2012-01-01

    Full Text Available Types of nettles (Urtica dioica were collected from different regions to analyze phenolic compounds in this research. Nettles are specially grown in the coastal part. According to this kind of properties, nettle samples were collected from coastal part of (Mediterranean, Aegean, Black sea, and Marmara Turkey. Phenolic profile, total phenol compounds, and antioxidant activities of nettle samples were analyzed. Nettles were separated to the part of root, stalk, and leaves. Then, these parts of nettle were analyzed to understand the difference of phenolic compounds and amount of them. Nettle (root, stalk and leaves samples were analyzed by using High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD to qualitative and quantitative determination of the phenolic compounds. Total phenolic components were measured by using Folin-Ciocalteu method. The antioxidant activity was measured by using DPPH (2,2-diphenyl-1-picrylhydrazyl which is generally used for herbal samples and based on single electron transfer (SET.

  13. Phenolic compounds analysis of root, stalk, and leaves of nettle.

    Science.gov (United States)

    Otles, Semih; Yalcin, Buket

    2012-01-01

    Types of nettles (Urtica dioica) were collected from different regions to analyze phenolic compounds in this research. Nettles are specially grown in the coastal part. According to this kind of properties, nettle samples were collected from coastal part of (Mediterranean, Aegean, Black sea, and Marmara) Turkey. Phenolic profile, total phenol compounds, and antioxidant activities of nettle samples were analyzed. Nettles were separated to the part of root, stalk, and leaves. Then, these parts of nettle were analyzed to understand the difference of phenolic compounds and amount of them. Nettle (root, stalk and leaves) samples were analyzed by using High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD) to qualitative and quantitative determination of the phenolic compounds. Total phenolic components were measured by using Folin-Ciocalteu method. The antioxidant activity was measured by using DPPH (2,2-diphenyl-1-picrylhydrazyl) which is generally used for herbal samples and based on single electron transfer (SET).

  14. Phenolic Compounds Analysis of Root, Stalk, and Leaves of Nettle

    Science.gov (United States)

    Otles, Semih; Yalcin, Buket

    2012-01-01

    Types of nettles (Urtica dioica) were collected from different regions to analyze phenolic compounds in this research. Nettles are specially grown in the coastal part. According to this kind of properties, nettle samples were collected from coastal part of (Mediterranean, Aegean, Black sea, and Marmara) Turkey. Phenolic profile, total phenol compounds, and antioxidant activities of nettle samples were analyzed. Nettles were separated to the part of root, stalk, and leaves. Then, these parts of nettle were analyzed to understand the difference of phenolic compounds and amount of them. Nettle (root, stalk and leaves) samples were analyzed by using High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD) to qualitative and quantitative determination of the phenolic compounds. Total phenolic components were measured by using Folin-Ciocalteu method. The antioxidant activity was measured by using DPPH (2,2-diphenyl-1-picrylhydrazyl) which is generally used for herbal samples and based on single electron transfer (SET). PMID:22593694

  15. [Effects of hot-NaOH pretreatment on Jerusalem artichoke stalk composition and subsequent enzymatic hydrolysis].

    Science.gov (United States)

    Wang, Qing; Qiu, Jingwen; Li, Yang; Shen, Fei

    2015-10-01

    In order to explore the possibility of Jerusalem artichoke stalk for bioenergy conversion, we analyzed the main composition of whole stalk, pitch, and core of the stalk. Meanwhile, these parts were pretreated with different NaOH concentrations at 121 degrees C. Afterwards, enzymatic hydrolysis was performed to evaluate the pretreatment efficiency. Jerusalem artichoke stalk was characterized by relatively high lignin content (32.0%) compared with traditional crop stalks. The total carbohydrate content was close to that of crop stalks, but with higher cellulose content (40.5%) and lower hemicellulose (19.6%) than those of traditional crop stalks. After pretreatment, the lignin content in the whole stalk, pitch, and core decreased by 13.1%-13.4%, 8.3%-13.5%, and 19.9%-27.2%, respectively, compared with the unpretreated substrates. The hemicellulose content in the whole stalk, pitch, and core decreased 87.8%-96.9%, 87.6%-95.0%, and 74.0%-90.2%, respectively. Correspondingly, the cellulose content in the pretreated whole stalk, pitch, and core increased by 56.5%-60.2%, 52.2%-55.4%, and 62.7%-73.2%, respectively. Moreover, increase of NaOH concentration for pretreatment could improve the enzymatic hydrolysis of the whole stalk and pitch by 2.3-2.6 folds and 10.3-18.5 folds, respectively. The hydrolysis of pretreated stalk core decreased significantly as 2.0 mol/L NaOH was employed, although the increased NaOH concentration can also improve its hydrolysis performance. Based on these results, hot-NaOH can be regarded as an option for Jerusalem artichoke stalk pretreatment. Increasing NaOH concentration was beneficial to hemicellulose and lignin removal, and consequently improved sugar conversion. However, the potential decrease of sugar conversion of the pretreated core by higher NaOH concentration suggested further optimization on the pretreatment conditions should be performed.

  16. Phenolic Compounds Analysis of Root, Stalk, and Leaves of Nettle

    OpenAIRE

    Otles, Semih; Yalcin, Buket

    2012-01-01

    Types of nettles (Urtica dioica) were collected from different regions to analyze phenolic compounds in this research. Nettles are specially grown in the coastal part. According to this kind of properties, nettle samples were collected from coastal part of (Mediterranean, Aegean, Black sea, and Marmara) Turkey. Phenolic profile, total phenol compounds, and antioxidant activities of nettle samples were analyzed. Nettles were separated to the part of root, stalk, and leaves. Then, these parts ...

  17. Enhancement of Cotton Stalks Composting with Certain Microbial Inoculations

    Directory of Open Access Journals (Sweden)

    Osama Abdel-Twab Seoudi

    2013-01-01

    Full Text Available Effect of inoculation with Phanerochaete chrysosporium and Azotobacter chrococcum microbes on cotton stalks composting was studied in an attempt to achieve rapid maturity and desirable characteristics of produced compost. Composting process was maintained for 16 weeks under aerobic conditions with proper moisture content and turning piles. The C/N ratio of the mixtures was adjusted to about 30:1 before composting using chicken manure. Temperature evolution and its profile were monitored throughout the composting period. Mineralization rates of organic matter and changes in nitrogen content during composting stages were evaluated. Total plate count of mesophilic and thermophilic bacteria, cellulose decomposers and Azotobacter were determined during composting periods. The treatment of cotton stalks inoculated with both P. chrysosporium and Azotobacter gave the most desirable characteristics of the final product with respect to the narrow C/N ratio, high nitrogen content and high numbers of Azotobacter. The phytotoxicity test of compost extracts was evaluated. The use of P. chrysosporium in composting accelerated markedly decomposition process, so that 16 weeks composting enough to produce a stable and mature compost suitable for use as fertilizer while the fertilizer obtained by composting cotton stalks mixed with chicken manure and inoculated with microorganisms is highest quality Compost.

  18. Influence of Fiber Bundle Morphology on the Mechanical and Bonding Properties of Cotton Stalk and Mulberry Branch Reconstituted Square Lumber

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2016-08-01

    Full Text Available The mechanical properties of natural fiber composites can be strengthened in the longitudinal direction if the fiber is formed in a parallel manner. Reconstituted cotton stalk lumber and mulberry branch lumber were fabricated using hot-press technology, and the effects of fiber morphology on their mechanical and bonding properties were investigated. The fiber bundle size had a great influence on the mechanical and bonding properties of the final products. The maximum specific modulus of rupture (MOR and specific modulus of elasticity (MOE of the reconstituted lumber were obtained for medium-size fiber bundles, and the maximum MOR and MOE of reconstituted cotton stalk lumber was 130.3 MPa·g-1·cm-3 and 12.9 GPa·g-1·cm-3, respectively. The maximum MOR and MOE of the mulberry branch lumber was 147.2 MPa·g-1·cm-3 and 14.7 GPa·g-1·cm-3, respectively. Mechanical interlocking structures in the lumber were observed via fluorescence microscopy, showing that phenol-formaldehyde adhesive had penetrated into several cell layers of the fiber bundle under heating and pressure. The adhesive penetration capacity was stronger when the fiber bundles were smaller in size and density. The reconstituted lumber fabricated from both materials exhibited excellent mechanical performance in the parallel direction. Therefore, reconstituted cotton stalk and mulberry branch lumber are attractive potential materials for the construction industry.

  19. Remote sensing techniques for monitoring the Rio Grande Valley cotton stalk destruction program

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, A.J.; Gerbermann, A.H.; Summy, K.R.; Anderson, G.L. (Department of Agriculture, Weslaco, TX (United States))

    1993-09-01

    Post harvest cotton (Gossypium hirsutum L.) stalk destruction is a cultural practice used in the Rio Grande Valley to suppress over wintering populations of boll weevils (Anthonomus grandis Boheman) without using chemicals. Consistent application of this practice could substantially reduce insecticide usage, thereby minimizing environmental hazards and increasing cotton production profits. Satellite imagery registered within a geographic information system was used to monitor the cotton stalk destruction program in the Rio Grande Valley. We found that cotton stalk screening procedures based on standard multispectral classification techniques could not reliably distinguish cotton from sorghum. Greenness screening for cotton plant stalks after the stalk destruction deadline was possible only where ground observations locating cotton fields were available. These findings indicate that a successful cotton stalk destruction monitoring program will require satellite images and earth referenced data bases showing cotton field locations.

  20. Summer Epiphytic Diatoms from Terra Nova Bay and Cape Evans (Ross Sea, Antarctica) - A Synthesis and Final Conclusions

    Science.gov (United States)

    Majewska, Roksana; Convey, Peter; De Stefano, Mario

    2016-01-01

    Despite recent advances in polar marine biology and related fields, many aspects of the ecological interactions that are crucial for the functioning of Antarctic shallow water habitats remain poorly understood. Although epiphytic diatoms play an essential role in the Antarctic marine food web, basic information regarding their ecology, biodiversity and biogeography is largely unavailable. Here, we synthesise studies on Ross Sea epiphytic diatoms collected during 11 summer Antarctic expeditions between the years 1989/90 and 2011/12, presenting a full list of diatom taxa associated with three macroalgal species (Iridaea cordata, Phyllophora antarctica, and Plocamium cartilagineum) and their epiphytic sessile fauna. Diatom communities found during the three summer months at various depths and sampling stations differed significantly in terms of species composition, growth form structure and abundances. Densities ranged from 21 to >8000 cells mm-2, and were significantly higher on the surface of epiphytic micro-fauna than on any of the macroalgal species examined. Generally, host organisms characterized by higher morphological heterogeneity (sessile microfauna, ramified Plocamium) supported richer diatom communities than those with more uniform surfaces (Iridaea). Differences between epiphytic communities associated with different macroalgae were reflected better in species composition than in growth form structure. The latter changed significantly with season, which was related strongly to the changing ice conditions. A general trend towards an increasing number of erect forms in deeper waters and tube-dwelling diatoms in the shallowest sites (2–5 m) was also observed. This study explores further important and largely previously unknown aspects of relationships and interactions between Antarctic epiphytic diatoms and their micro- and macro-environments. PMID:27078637

  1. Psychological Impact of Stalking on Male and Female Health Care Professional Victims of Stalking and Domestic Violence

    Directory of Open Access Journals (Sweden)

    Daniela Acquadro Maran

    2018-03-01

    Full Text Available The aim of this work was to investigate stalking experiences in a sample of Health Care Professionals, or HCPs, who experienced domestic violence in their previous relationships with an intimate romantic or non-romantic who had become their stalkers. A comparison between males and females was made to highlight the differences among the genders. The findings showed that, for the most part, the victims experienced stalking by a stalker that was not of the same gender. Moreover, the nature of the relationship was romantic, for the most part, for both female and male subjects, suggesting that the principal motivation of stalking is the disruption of an intimate relationship. Regarding domestic violence, females described the phenomenon from a different perspective, indicating verbal, physical, and sexual abuse, while males indicated only verbal abuse. Females tended to amplify, more than the males, depression, and state and trait anxiety. Even if all symptoms were expressed in both females and males, the males exhibited a lack of confidence in their bodies, and the emotional literacy made the expression of distress more difficult. At the same time, the expression of anxiety presented in the women permitted them to become progressively less victimized over time; depression and anxiety allow the recognition of these symptoms as signs of distress and to intervene to reduce them.

  2. Psychological Impact of Stalking on Male and Female Health Care Professional Victims of Stalking and Domestic Violence.

    Science.gov (United States)

    Acquadro Maran, Daniela; Varetto, Antonella

    2018-01-01

    The aim of this work was to investigate stalking experiences in a sample of Health Care Professionals, or HCPs, who experienced domestic violence in their previous relationships with an intimate romantic or non-romantic who had become their stalkers. A comparison between males and females was made to highlight the differences among the genders. The findings showed that, for the most part, the victims experienced stalking by a stalker that was not of the same gender. Moreover, the nature of the relationship was romantic, for the most part, for both female and male subjects, suggesting that the principal motivation of stalking is the disruption of an intimate relationship. Regarding domestic violence, females described the phenomenon from a different perspective, indicating verbal, physical, and sexual abuse, while males indicated only verbal abuse. Females tended to amplify, more than the males, depression, and state and trait anxiety. Even if all symptoms were expressed in both females and males, the males exhibited a lack of confidence in their bodies, and the emotional literacy made the expression of distress more difficult. At the same time, the expression of anxiety presented in the women permitted them to become progressively less victimized over time; depression and anxiety allow the recognition of these symptoms as signs of distress and to intervene to reduce them.

  3. Sedimentation of phytoplankton during a diatom bloom : Rates and mechanisms

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Hansen, J.L.S.; Alldredge, A.L.

    1996-01-01

    Phytoplankton blooms are uncoupled from grazing and are normally terminated by sedimentation. There are several potential mechanisms by which phytoplankton cells may settle out of the photic zone: sinking of individual cells or chains, coagulation of cells into aggregates with high settling...... velocities, settling of cells attached to marine snow aggregates formed from discarded larvacean houses or pteropod feeding webs, and packaging of cells into rapidly falling zooplankton fecal pellets. We quantified the relative significance of these different mechanisms during a diatom bloom in a temperate...... to marine snow aggregates formed from discarded larvacean houses, whereas settling of unaggregated cells was insignificant. Formation rates of phytoplankton aggregates by physical coagulation was very low, and losses by this mechanism were much less than 0.07 d(-1); phytoplankton aggregates were neither...

  4. Ant-plant symbioses: Stalking the chuyachaqui.

    Science.gov (United States)

    Davidson, D W; McKey, D

    1993-09-01

    According to Quechua-speaking peoples, orchard-like stands ('Supay Chacras') of two Amazonian ant-plant species are cultivated by the devil, or 'Chuyachaqui'. These "devil gardens" offer extreme examples of specializations that have evolved repeatedly in ant-plant associations. Numerous investigations are beginning to disclose the identity of the Chuyachaqui - the forces behind evolutionary specialization in ant-plant symbioses. These developments have important implications for our understanding of modes of coevolution in symbiotic mutualism, remarkable convergent similarities in the form of ant-plant symbioses on different continents, and pronounced intercontinental differences in the diversity and taxonomic composition of associates. Copyright © 1993. Published by Elsevier Ltd.

  5. [Research advances in heavy metals pollution ecology of diatom].

    Science.gov (United States)

    Ding, Teng-Da; Ni, Wan-Min; Zhang, Jian-Ying

    2012-03-01

    Diatom, due to its high sensitivity to environmental change, is one of the bio-indicators of aquatic ecosystem health, and some typical diatom species have been applied to indicate the heavy metals pollution of water body. With the focus on the surface water heavy metals pollution, this paper reviewed the research advances in the toxic effect of heavy metals pollution on diatom, biosorption and bioaccumulation of heavy metals by diatom, ecological adaptation mechanisms of diatom to heavy metals pollution, and roles of diatom as bio-indicator and in ecological restoration of heavy metals pollution. The growth tendency of diatom and the morphological change of frustule under heavy metals pollution as well as the differences in heavy metals biosorption and bioaccumulation by diatom, the ecological adaptation mechanisms of diatom on heavy metals surface complexation and ion exchange, and the roles of diatom as bio-indicator and in ecological restoration of heavy metals polluted water body were also discussed. This review could provide scientific evidences for the prevention of aquatic ecosystems heavy metals pollution and related early warning techniques.

  6. Do Identical Polar Diatomic Molecules Form Stacked or Linear ...

    Indian Academy of Sciences (India)

    ias

    tractive and repulsive Coulomb interactions balance and cancel. Of course ... life, carbon (group 14), i.e., carbon bonding, has been proposed based ... Medical Institute EXROP program. ..... Hughes Medical Institute for support of this work. CW.

  7. Yield survey and nutritional evaluation of garlic stalk for ruminant feed.

    Science.gov (United States)

    Lee, Y H; Kim, Y I; Oh, Y K; Ahmadi, F; Kwak, W S

    2017-01-01

    Very limited information exists on the ruminal degradation kinetics of nutrients in garlic stalk. The present study aimed to survey the annual yield of garlic stalk in Korea and determine its feed-nutritive value for ruminants. In Experiment 1, garlic stalk was incubated in situ in the rumen of two Hanwoo steers (360 ± 15 kg body weight) and removed after 12, 24, or 48 h to determine the ruminal degradation kinetics of DM and NDF. Rice straw was also included for comparison. In Experiment 2, In Experiment 2, six male Corriedale sheep were randomized to two dietary treatments to determine the apparent digestibility of nutrients in garlic stalk. Diets included a control ration without garlic stalk (60% concentrate mix +40% ryegrass) or a treatment ration (70% control diet +30% garlic stalk). The Korean national yield of garlic stalk (sun-dried basis) in 2016 was estimated to be 31,910 tons, with the southern coastal regions producing the highest quantity. Compared with rice straw, garlic stalk had lower NDF, higher ADF, and greater effective degradabilities of DM and NDF, resulting in a greater TDN value (56.3%), which was higher than that obtained for rice straw (43.7%). These results provide basic information on the ruminal DM and NDF degradation kinetics of garlic stalk, which would be helpful for the efficient utilization of this by-product in ruminant diets.

  8. Yield survey and nutritional evaluation of garlic stalk for ruminant feed

    Directory of Open Access Journals (Sweden)

    Y. H. Lee

    2017-10-01

    Full Text Available Abstract Background Very limited information exists on the ruminal degradation kinetics of nutrients in garlic stalk. The present study aimed to survey the annual yield of garlic stalk in Korea and determine its feed-nutritive value for ruminants. Methods In Experiment 1, garlic stalk was incubated in situ in the rumen of two Hanwoo steers (360 ± 15 kg body weight and removed after 12, 24, or 48 h to determine the ruminal degradation kinetics of DM and NDF. Rice straw was also included for comparison. In Experiment 2, In Experiment 2, six male Corriedale sheep were randomized to two dietary treatments to determine the apparent digestibility of nutrients in garlic stalk. Diets included a control ration without garlic stalk (60% concentrate mix +40% ryegrass or a treatment ration (70% control diet +30% garlic stalk. Results The Korean national yield of garlic stalk (sun-dried basis in 2016 was estimated to be 31,910 tons, with the southern coastal regions producing the highest quantity. Compared with rice straw, garlic stalk had lower NDF, higher ADF, and greater effective degradabilities of DM and NDF, resulting in a greater TDN value (56.3%, which was higher than that obtained for rice straw (43.7%. Conclusion These results provide basic information on the ruminal DM and NDF degradation kinetics of garlic stalk, which would be helpful for the efficient utilization of this by-product in ruminant diets.

  9. Diatomic infrared gas-dynamic laser

    International Nuclear Information System (INIS)

    Mckenzie, R.L.

    1971-01-01

    A laser is provided which utilizes the infrared vibration rotation transitions of a diatomic gas such as carbon monoxide. The laser action is produced by an active diatomic gas such as carbon monoxide mixed with a vibrationally resonant pumping gas such as nitrogen. In addition, a noble gas such as argon may be employed as a third gas in the mixture. The gas mixture contains from 1 to 80 vol percent of the active gas based on the pumping gas, and the third gas, if used, can constitute up to 90 percent of the total gas volume. A number of significantly different wavelengths can be produced by the laser. A single laser may contain several optical resonators at different locations, so that the desired wave length can be selected at will

  10. Silicon diatom frustules as nanostructured photoelectrodes.

    Science.gov (United States)

    Chandrasekaran, Soundarrajan; Sweetman, Martin J; Kant, Krishna; Skinner, William; Losic, Dusan; Nann, Thomas; Voelcker, Nicolas H

    2014-09-18

    In the quest for solutions to meeting future energy demands, solar fuels play an important role. A particularly promising example is photocatalysis since even incremental improvements in performance in this process are bound to translate into significant cost benefits. Here, we report that semiconducting and high surface area 3D silicon replicas prepared from abundantly available diatom fossils sustain photocurrents and enable solar energy conversion.

  11. Collision-induced dissociation of diatomic ions

    International Nuclear Information System (INIS)

    Los, J.; Govers, T.R.

    1978-01-01

    An attempt is made to illustrate how mass spectrometric studies of dissociation in diatomic molecular ions can provide information on the dynamics of these collisions and on the predissociative states involved. Restriction is made to primary beam energies of the order of at least keV. The review covers the dynamics of dissociation, experimental techniques, direct dissociation in heavy-particle collisions, and translational spectroscopy. 120 references

  12. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the molecules CO, HB, HF and LiH are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. It is discussed the possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment. (Author) [pt

  13. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the CO, HB, HF and LiH molecules are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. The possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment is discussed. (Author) [pt

  14. Removal of cadmium(II) from aqueous solution by corn stalk graft copolymers.

    Science.gov (United States)

    Zheng, Liuchun; Dang, Zhi; Zhu, Chaofei; Yi, Xiaoyun; Zhang, Hui; Liu, Congqiang

    2010-08-01

    Corn stalk was modified using graft copolymerization to produce absorbent (AGCS), which was characterized by elemental analysis, fourier transform infrared, X-ray diffraction, solid-state CP/MAS (13)C NMR spectra, thermogravimetric analysis and differential scanning calorimeter. AGCS, having cyano group (-CN) after grafted successfully, exhibits more high adsorption potential for Cd(II) than unmodified forms. The efficiency of AGCS for removal of cadmium ions was evaluated. Factors affecting Cd(II) adsorption such as pH value and adsorbent dosage were investigated. More than 90% removal was achieved at pH 3.0-7.0 and the adsorption increased from 16.0% to 99.2% with increase of adsorbent dose. In addition, two isotherm models, namely, Langmuir and Freunlich were also analyzed to determine the best fit equation for adsorption of Cd(II) on AGCS. (c) 2010 Elsevier Ltd. All rights reserved.

  15. Applications of Diatoms as Potential Microalgae in Nanobiotechnology

    OpenAIRE

    Ahmad Yari Khosroushahi; Miguel de la Guardia; Mohamad Moradi Ghorakhlu; Ali Akbar Jamali; Fariba Akbari

    2012-01-01

    Introduction: Diatoms are single cell eukaryotic microalgae, which present in nearly every water habitat make them ideal tools for a wide range of applications such as oil explora­tion, forensic examination, environmental indication, biosilica pattern generation, toxicity testing and eutrophication of aqueous ecosystems. Methods: Essential information on diatoms were reviewed and discussed towards impacts of diatoms on biosynthesis and bioremediation. Results: In this review, we present the ...

  16. Diatom flora in subterranean ecosystems: a review

    Directory of Open Access Journals (Sweden)

    Elisa Falasco

    2014-09-01

    Full Text Available In scarcity of light and primary producers, subterranean ecosystems are generally extremely oligotrophic habitats, receiving poor supplies of degradable organic matter from the surface. Human direct impacts on cave ecosystems mainly derive from intensive tourism and recreational caving, causing important alterations to the whole subterranean environment. In particular, artificial lighting systems in show caves support the growth of autotrophic organisms (the so-called lampenflora, mainly composed of cyanobacteria, diatoms, chlorophytes, mosses and ferns producing exocellular polymeric substances (EPSs made of polysaccharides, proteins, lipids and nucleic acids. This anionic EPSs matrix mediates to the intercellular communications and participates to the chemical exchanges with the substratum, inducing the adsorption of cations and dissolved organic molecules from the cave formations (speleothems. Coupled with the metabolic activities of heterotrophic microorganisms colonising such layer (biofilm, this phenomenon may lead to the corrosion of the mineral surfaces. In this review, we investigate the formation of biofilms, especially of diatom-dominated ones, as a consequence of artificial lighting and its impacts on speleothems. Whenever light reaches the subterranean habitat (both artificially and naturally a relative high number of species of diatoms may indeed colonise it. Cave entrances, artificially illuminated walls and speleothems inside the cave are generally the preferred substrates. This review focuses on the diatom flora colonising subterranean habitats, summarizing the information contained in all the scientific papers published from 1900 up to date. In this review we provide a complete checklist of the diatom taxa recorded in subterranean habitats, including a total of 363 taxa, belonging to 82 genera. The most frequent and abundant species recorded in caves and other low light subterranean habitats are generally aerophilic and

  17. Seasonal variations in fouling diatom communities on the Yantai coast

    Science.gov (United States)

    Yang, Cuiyun; Wang, Jianhua; Yu, Yang; Liu, Sujing; Xia, Chuanhai

    2015-03-01

    Fouling diatoms are a main component of biofilm, and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater, on the Yantai coast, northern Yellow Sea, China, using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3, 7, 14, and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca, Nitzschia, Navicula, Amphora, Gomphonema, and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions, we found that Cylindrotheca grew very fast, which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.

  18. Inorganic carbon availability in benthic diatom communities: photosynthesis and migration.

    Science.gov (United States)

    Marques da Silva, Jorge; Cruz, Sónia; Cartaxana, Paulo

    2017-09-05

    Diatom-dominated microphytobenthos (MPB) is the main primary producer of many intertidal and shallow subtidal environments, being therefore of critical importance to estuarine and coastal food webs. Owing to tidal cycles, intertidal MPB diatoms are subjected to environmental conditions far more variable than the ones experienced by pelagic diatoms (e.g. light, temperature, salinity, desiccation and nutrient availability). Nevertheless, benthic diatoms evolved adaptation mechanisms to these harsh conditions, including the capacity to move within steep physical and chemical gradients, allowing them to perform photosynthesis efficiently. In this contribution, we will review present knowledge on the effects of dissolved inorganic carbon (DIC) availability on photosynthesis and productivity of diatom-dominated MPB. We present evidence of carbon limitation of photosynthesis in benthic diatom mats and highly productive MPB natural communities. Furthermore, we hypothesize that active vertical migration of epipelic motile diatoms could overcome local depletion of DIC in the photic layer, providing the cells alternately with light and inorganic carbon supply. The few available longer-term experiments on the effects of inorganic carbon enrichment on the productivity of diatom-dominated MPB have yielded inconsistent results. Therefore, further studies are needed to properly assess the response of MPB communities to increased CO 2 and ocean acidification related to climate change.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

  19. Limits to gene flow in a cosmopolitan marine planktonic diatom.

    Science.gov (United States)

    Casteleyn, Griet; Leliaert, Frederik; Backeljau, Thierry; Debeer, Ann-Eline; Kotaki, Yuichi; Rhodes, Lesley; Lundholm, Nina; Sabbe, Koen; Vyverman, Wim

    2010-07-20

    The role of geographic isolation in marine microbial speciation is hotly debated because of the high dispersal potential and large population sizes of planktonic microorganisms and the apparent lack of strong dispersal barriers in the open sea. Here, we show that gene flow between distant populations of the globally distributed, bloom-forming diatom species Pseudo-nitzschia pungens (clade I) is limited and follows a strong isolation by distance pattern. Furthermore, phylogenetic analysis implies that under appropriate geographic and environmental circumstances, like the pronounced climatic changes in the Pleistocene, population structuring may lead to speciation and hence may play an important role in diversification of marine planktonic microorganisms. A better understanding of the factors that control population structuring is thus essential to reveal the role of allopatric speciation in marine microorganisms.

  20. A comparison of soda and soda-AQ pulps from cotton stalks | Akgül ...

    African Journals Online (AJOL)

    In this study, cotton stalks (Gossypium hirsutum L.) were cooked using soda and soda-anthraquinone (AQ) process. Nine soda cooks were conducted by changing cooking conditions including active alkali charge and pulping time. Soda-AQ cooks were obtained by adding 0.075, 0.10, 0.15, 0.2% AQ (based on o.d stalks) to ...

  1. study on the chopping and mixing of cotton stalks with soil | Sa glam ...

    African Journals Online (AJOL)

    -type, splined-type and vertical-blade rotating dredge). Field experiments were conducted with each type to determine the proportion of non-uprooted cotton stalks; mean “post-chopping height” of the stalks, measured from soil surface; and the ...

  2. Stalking Victimization among College Women and Subsequent Help-Seeking Behaviors

    Science.gov (United States)

    Buhi, Eric R.; Clayton, Heather; Surrency, Heather Hepler

    2009-01-01

    Objective: The authors examined the incidence of stalking victimization and subsequent help-seeking behaviors among college women. Participants and Methods: A stratified random sample of college women (N = 391) completed an anonymous Internet-based questionnaire in spring 2006. Results: One-fifth of women reported stalking victimization while…

  3. Radiation-induced grafting of sweet sorghum stalk for copper(II) removal from aqueous solution

    International Nuclear Information System (INIS)

    Dong, Jing; Hu, Jun; Wang, Jianlong

    2013-01-01

    Highlights: • Radiation-induced grafting was used to modify the stalk. • Cellulose, hemicellulose and lignin participated in grafting reaction. • Both the structure and composition of stalk had influence on grafting. • The sorption capacity of the grafted stalk increased about five times. -- Abstract: The influence of main components (cellulose, hemicellulose and lignin) of the sweet sorghum stalk on radiation-induced grafting reaction and adsorption of copper from aqueous solution was investigated. Sweet sorghum stalk was grafted with acrylic acid induced by γ-irradiation. The results showed that the grafted stalk contained 1.6 mmol/g carboxyl groups, and its maximal adsorption capacity was 13.32 mg/g. The cellulose, hemicellulose and lignin of the raw materials were confirmed to involve in grafting reaction through comparing the grafting yield and the structure of the grafted materials. Both the structure and the composition of the sweet sorghum stalk had influence on the grafting reaction and adsorption capacity. The adsorption capacity of the grafted sweet sorghum stalk increased about five times, and the adsorption isotherm of the grafted materials conformed to the Langmuir model. The main mechanism for copper adsorption involved in ion exchange

  4. Victims of stalking in India: A study of girl college students in Tirunelveli City

    Directory of Open Access Journals (Sweden)

    Jaishankar Karuppannan

    2007-01-01

    Full Text Available The word 'stalking' was not commonly known in India, until Priyadharshini Mattoo's case (1996 hit the headlines. Eve teasing, a colloquial word for gender harassment is popularly known and Tamil Nadu Prohibition of Eve-Teasing Act, 1998 on that was developed after the brutal killing of a girl named Sarika Shah in Chennai. Though, stalking is there in the past, it was not acknowledged with this terminology and it was always merged with Eve teasing. On the other hand, stalking is much graver than Eve teasing and it is an obsessive behaviour. After the Matoo's case, the Indian Criminal Justice System awoke and the National Commission for Women is ready with a draft Bill (Sexual Assault Prevention Bill to make the Indian Penal Code more effective against the menace of stalkers. Research studies related to stalking in India are sparse and there is a need to study this phenomenon in depth. This paper presents some results from a study of stalking victims among Girl College students at Tirunelveli City, Tamil Nadu, India. In-depth questionnaire data are drawn on to investigate the course and nature of prolonged stalking in 150 self-defined victims. Findings indicate a pattern of repeated intrusions, the stalking harassment methods, lack of reporting behaviour, and effects of stalking on the victims.

  5. Utilization of bio-waste cotton ( Gossypium hirsutum L.) stalks and ...

    African Journals Online (AJOL)

    ... three-layer particleboard containing different cotton (Gossypium hirsutum L.) stalks and underutilized paulownia (paulownia fortunie) wood particle ratios (30, 50 and 70%) using urea formaldehyde resin. Addition of cotton stalk and paulownia wood in particleboard improved mechanical properties of resulting composites ...

  6. Case of pituitary stalk transection syndrome ascertained after breech delivery.

    Science.gov (United States)

    Fukuta, Kaori; Hidaka, Takao; Ono, Yosuke; Kochi, Keiko; Yasoshima, Kuniaki; Arai, Takashi

    2016-02-01

    Pituitary stalk transection syndrome (PSTS) is a rare complication that can accompany breech delivery. Early diagnosis of this syndrome is difficult, and it may cause a serious delay in the diagnosis. We present a case of PSTS ascertained after breech delivery. A 20-year-old woman presented with primary amenorrhea. The patient was born by breech delivery and had a history of treatment for pituitary dwarfism. Her laboratory findings showed pituitary hypothyroidism, and hormone replacement therapy was initiated. At 28 years old, she became pregnant and had a normal delivery at 38 weeks' gestation. One year after delivery, her thyroid hormone level changed. Laboratory test showed adrenocortical insufficiency, and magnetic resonance imaging of the pituitary gland showed transection of the pituitary stalk and development of an ectopic posterior lobe. These findings were compatible with PSTS. When a patient who has been born by breech delivery presents with symptoms of pituitary deficiency, PSTS should be considered in the differential diagnosis. © 2015 Japan Society of Obstetrics and Gynecology.

  7. Pyrolysis Characteristics of Corn Stalk with Solid Heat Carrier

    Directory of Open Access Journals (Sweden)

    Min Guo

    2015-05-01

    Full Text Available Pyrolysis of corn stalk with a solid heat carrier was studied under temperatures ranging from 430 to 620 °C. The solid heat carrier used was high-temperature ash from a CFB boiler. The yields of three products and their characteristics were investigated. Moreover, the distributions of sulfur and nitrogen in the products were determined. The results indicate that with increasing temperature, the char yield decreased, gas yield increased, and calorific value of the gas increased from 10.13 to 16.65 MJ/m3. The yield of bio-oil reached a maximum, 14.24 wt.%, at 510 °C. Light-oil in the bio-oil accounted for more than 69.12 wt.%. The elemental composition of the char and char ash were analyzed. The distribution of sulfur and nitrogen in the char decreased to 60.44 and 46.52 wt.%, respectively, depending on the raw materials used. These results provide basic data for the possible industrial application of corn stalk.

  8. Diatom-Based Paleoenvironmental Reconstruction of Lake Telmen for the Last 6230 Years

    Directory of Open Access Journals (Sweden)

    N.Soninkhishig

    2003-06-01

    Full Text Available The preserved diatom flora in a 14C dated (0-6230 yBP, 343 cm long core sequence from Lake Telmen, Mongolia, was investigated to determine the nature of the lake-ecosystem and watershed response to Late Holocene climate change. Modern Lake Telmen is a slightly saline (presently 4 g L-1 closed- basin lake located along a N-S and E-W aridity ecotone in north-central Mongolia, making it sensitive to climate-driven changes in effective moisture balance. Diatoms were not preserved regularly in two areas of the Lake Telmen sediment record (5380-41 50 yBP and 1050-425 yBP possibly due to high carbonate preservation; however, diatom preservation between these areas was good to excellent. Diatom-based paleosalinity reconstruction using species-specific salinity optima from the Northern Great Plains of North America and community analysis suggests the following climate-lake response model during the Late Holocene. From 6230 to 5520 radiocarbon years ago, warm-dry climate resulted in a small salty (20 g L-1 lake in the Telmen basin that was dominated by high salinity indicator species (e.g. Cyclotella caspia, Navicellapusilla, Brachysira aponina. From 3 860 to 1200 radiocarbon yBP, Lake Telmen recorded a period of a modulating climate that resulted in regular fluctuations in paleosalinity from 2 to 4 g L-1 in conjunction with lake level changes. Dominance in the diatom flora fluctuated between the freshwater planktonic form Cyclotella bodanica var. affinis and the salinity-tolerant benthic taxon Anomoeoneis sphaerophora f. costata during this period characterized by generally more humid climatic periods interspersed with dry-as-present conditions. The most modern samples (0-250 yBP preserve floristic assemblages similar to those found between 3860 to 1200 radiocarbon yBP and indicate that as recently as 250 years ago Lake Telmen had lower salinity values than modern day.

  9. Diatom community structure on in-service cruise ship hulls.

    Science.gov (United States)

    Hunsucker, Kelli Zargiel; Koka, Abhishek; Lund, Geir; Swain, Geoffrey

    2014-10-01

    Diatoms are an important component of marine biofilms found on ship hulls. However, there are only a few published studies that describe the presence and abundance of diatoms on ships, and none that relate to modern ship hull coatings. This study investigated the diatom community structure on two in-service cruise ships with the same cruise cycles, one coated with an antifouling (AF) system (copper self-polishing copolymer) and the other coated with a silicone fouling-release (FR) system. Biofilm samples were collected during dry docking from representative areas of the ship and these provided information on the horizontal and vertical zonation of the hull, and intact and damaged coating and niche areas. Diatoms from the genera Achnanthes, Amphora and Navicula were the most common, regardless of horizontal ship zonation and coating type. Other genera were abundant, but their presence was more dependent on the ship zonation and coating type. Samples collected from damaged areas of the hull coating had a similar community composition to undamaged areas, but with higher diatom abundance. Diatom fouling on the niche areas differed from that of the surrounding ship hull and paralleled previous studies that investigated differences in diatom community structure on static and dynamically exposed coatings; niche areas were similar to static immersion and the hull to dynamic immersion. Additionally, diatom richness was greater on the ship with the FR coating, including the identification of several new genera to the biofouling literature, viz. Lampriscus and Thalassiophysa. These results are the first to describe diatom community composition on in-service ship hulls coated with a FR system. This class of coatings appears to have a larger diatom community compared to copper-based AF systems, with new diatom genera that have the ability to stick to ship hulls and withstand hydrodynamic forces, thus creating the potential for new problematic species in the biofilm.

  10. Stalking of psychiatrists: psychopathological characteristics and gender differences in an Italian sample.

    Science.gov (United States)

    Mastronardi, Vincenzo M; Pomilla, Antonella; Ricci, Serafino; D'Argenio, Alberto

    2013-05-01

    Research has indicated that medical doctors and paramedics are at higher risk of being stalked than the general population. In particular, mental health care professionals alone represent one third of the victims of harassment. Because of the lack of studies in this specific sector, especially in Italy, in this study, we examined the stalking of psychiatrists by their patients, considering gender differences and the incidence of stalking in private practice and public mental health clinics in Rome. We found that the rate of stalking in private mental health settings is higher than that in public settings and that the perpetrators of stalking are mainly women who mostly target mental health professionals working in private practice. Implications of the findings are noted and discussed.

  11. Harassment, stalking, threats and attacks targeting New Zealand politicians: A mental health issue.

    Science.gov (United States)

    Every-Palmer, Susanna; Barry-Walsh, Justin; Pathé, Michele

    2015-07-01

    Due to the nature of their work, politicians are at greater risk of stalking, harassment and attack than the general population. The small, but significantly elevated risk of violence to politicians is predominantly due not to organised terrorism or politically motivated extremists but to fixated individuals with untreated serious mental disorders, usually psychosis. Our objective was to ascertain the frequency, nature and effects of unwanted harassment of politicians in New Zealand and the possible role of mental illness in this harassment. New Zealand Members of Parliament were surveyed, with an 84% response rate (n = 102). Quantitative and qualitative data were collected on Parliamentarians' experiences of harassment and stalking. Eighty-seven percent of politicians reported unwanted harassment ranging from disturbing communications to physical violence, with most experiencing harassment in multiple modalities and on multiple occasions. Cyberstalking and other forms of online harassment were common, and politicians felt they (and their families) had become more exposed as a result of the Internet. Half of MPs had been personally approached by their harassers, 48% had been directly threatened and 15% had been attacked. Some of these incidents were serious, involving weapons such as guns, Molotov cocktails and blunt instruments. One in three politicians had been targeted at their homes. Respondents believed the majority of those responsible for the harassment exhibited signs of mental illness. The harassment of politicians in New Zealand is common and concerning. Many of those responsible were thought to be mentally ill by their victims. This harassment has significant psychosocial costs for both the victim and the perpetrator and represents an opportunity for mental health intervention. © The Royal Australian and New Zealand College of Psychiatrists 2015.

  12. Hormonal regulation of the growth of leaves and inflorescence stalk in Muscari armeniacum Leichtl.

    Directory of Open Access Journals (Sweden)

    Marian Saniewski

    2016-04-01

    Full Text Available It is known that chilling of Muscari bulbs is necessary for the growth of the inflorescence stalk and flowering, but not for the growth of leaves. Gibberellic acid (GA accelerated stem growth and flowering in chilled Muscari bulbs. In the present experiment it was shown that in unchilled derooted Muscari bulbs the growth of leaves, but not the growth of the inflorescence stalk, was observed when bulbs were stored in water, GA at a concentration of 50 and 100 mg/L, benzyladenine (BA at a concentration of 25 and 50 mg/L, or a mixture of GA+BA (50+25 mg/L, but abscisic acid (ABA at a concentration of 10 mg/L greatly inhibited the growth of leaves. In chilled derooted Muscari bulbs the growth of leaves and inflorescence stalk was observed when bulbs were stored in water or GA, but BA and GA+BA treatments totally inhibited the growth of the inflorescence stalk without an effect on the growth of leaves. These results clearly showed that the growth of leaves and inflorescence stalk in Muscari bulbs are controlled by plant growth regulators in different ways. ABA totally inhibited the growth of leaves and inflorescence stalk in chilled derooted Muscari bulbs. It was shown that after the excision of the inflorescence bud in cultivated chilled Muscari bulbs, the inflorescence stalk died, but application of indole-3-acetic acid (IAA 0.5% in the place of the removed inflorescence bud induced the growth of the inflorescence stalk. IAA applied under the inflorescence bud inhibited the development of flowers (flower-bud blasting and induced the growth of the inflorescence stalk below the treatment site. These results are discussed with reference to hormonal regulation of stem (stalk growth in tulip, narcissus, hyacinth, and Hippeastrum.

  13. Role of Diatoms in marine biofouling

    Digital Repository Service at National Institute of Oceanography (India)

    Anil, A; Patil, J.S..; Mitbavkar, S.; DeCosta, P.M.; DeSilva, S.; Hegde, S.; Naik, R.

    . Ltd., New Delhi, pp. 293-6. de Nys, R., Leya, T., Maximilien, R., Afsar, A., Nair, P. S. R. & Steinberg, P. D. 1996. The need for standardized broad scale bioassay testing: a case study using the red alga Laurencia rigida. Biofouling 10:213-24. de...-1 Content-Type text/plain; charset=ISO-8859-1 Recent Advances on Applied Aspects of Indian Marine Algae with Reference to Global Scenario, Volume 1, A. Tewari (Ed.), 2006 Central Salt & Marine Chemicals Research Institute Role of Diatoms...

  14. Digitisation of the South African diatom collection

    CSIR Research Space (South Africa)

    Van

    2008-06-01

    Full Text Available stream_source_info van der Molen_2008.pdf.txt stream_content_type text/plain stream_size 1285 Content-Encoding UTF-8 stream_name van der Molen_2008.pdf.txt Content-Type text/plain; charset=UTF-8 Digitisation... of the South African Diatom Collection Johan van der Molen, CSIR Background ➲ Since 1950 ➲ Properly curated ➲ In dis-use since ~1990 ➲ Renewed interest since ~2004 ➲ Water bodies in Southern Africa, mostly rivers ➲ Supports taxonomic work and biological...

  15. Ecology and Evolution of Diatom-Associated Cyanobacteria Through Genetic Analyses

    OpenAIRE

    Hilton, Jason Andrew

    2014-01-01

    Primary production in a large fraction of the surface ocean communities is limited by the availability of nitrogen (N). Heterocyst-forming cyanobacteria associated with diatoms of the genera Hemiaulus, Rhizosolenia, and Chaetoceros can dominate surface communities throughout the global oceans, and are an important source of N to these communities. Additionally, these unique associations are directly linked to a highly efficient carbon export system. In order to study the nature and evolution ...

  16. Eco-biology of marine diatoms with emphasis on the influence of physico-chemical parameters

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.

    cell abundance of epipelic diatoms was high only during the morning low tide whereas in winter it was found to be the highest during the mid-morning high tide and continued to be so even during the following evening low tide. This ability... of microphytobenthos to migrate vertically within the surface sediment when their requirements are fulfilled may be considered as a form of behavioral photoacclimation, allowing cells to avoid potentially 166 damaging irradiance and temperature conditions (Kromkamp...

  17. The relevance of diatoms for water quality assessment in South ...

    African Journals Online (AJOL)

    Water quality assessment protocols based on the use of diatoms are now well developed and their value substantiated at an international level. The use of diatoms is not designed or intended to be a “rapid” technology. The detailed level of information generated from the procedure outweighs perceived disadvantages of ...

  18. Epiphytic Diatoms along Environmental Gradients in Western European Shallow Lakes

    NARCIS (Netherlands)

    Blanco, Saul; Cejudo-Figueiras, Cristina; Alvarez-Blanco, Irene; van Donk, Ellen|info:eu-repo/dai/nl/069838593; Gross, Elisabeth M.; Hansson, Lars-Anders; Irvine, Kenneth; Jeppesen, Erik; Kairesalo, Timo; Moss, Brian; Noges, Tiina; Becares, Eloy

    Diatom-based assays have been successfully associated worldwide with the tropic status of lakes. Several studies have demonstrated a correlation between epiphytic diatoms and nutrient load in shallow lakes and wetlands. We examine the relative importance of environmental factors in explaining the

  19. Colonization of diatom aggregates by the dinoflagellate Noctiluca scintillans

    DEFF Research Database (Denmark)

    Tiselius, P.; Kiørboe, Thomas

    1998-01-01

    coagulation of diatom cells and not by mucus feeding behavior of N. scintillans. N. scintillans can be positively buoyant, and estimates of encounter rates between N. scintillans and diatom aggregates during ascent demonstrates that this mechanism is sufficient to account for the observed colonization...

  20. Diatom-based water quality monitoring in southern Africa ...

    African Journals Online (AJOL)

    The purpose of this review is to summarise the challenges and future prospects associated with biological water quality monitoring using diatoms with special focus on southern Africa. Much work still needs to be carried out on diatom tolerances, ecological preferences and ecophysiology. It is recommended that past ...

  1. Diatom distribution in the surficial sediments of Lake Fuxian, Yunnan ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-30

    Nov 30, 2011 ... The diatom abundances per gram dry weight sediment vary between 18.4 × 106 and 66.9 × 106 valves (Figure 2). Abundances per gram dry weight of the eight most abundant diatom taxa are shown in Figure 3. The DCA diagram shows centroids of ecoregions in the ordination space of the first axes.

  2. Interference patterns and extinction ratio of the diatom Coscinodiscus granii

    DEFF Research Database (Denmark)

    Maibohm, Christian; Friis, Søren Michael Mørk; Ellegaard, M.

    2015-01-01

    We report experimental and theoretical verification of the nature and position of multiple interference points of visible light transmitted through the valve of the centric diatom species Coscinodiscus granii. Furthermore, by coupling the transmitted light into an optical fiber and moving...... the diatom valve between constructive and destructive interference points, an extinction ratio of 20 dB is shown...

  3. The health of benthic diatom assemblages in lower stretch

    Indian Academy of Sciences (India)

    This study examines the ecological state of epilithic diatom assemblages along the lower stretch of Mandakini, a glacier-fed Himalayan river. The diatoms were sampled at four stations during winter and summer, only once in each season. Valve counts were obtained from Naphrax mounts prepared from each sample.

  4. Isolation of diatom Navicula cryptocephala and characterization of ...

    African Journals Online (AJOL)

    sjce

    synthesis to the storage of neutral lipids (Qiang et al.,. 2008). Diatoms were shown ... chemical analysis of the oil inside diatom oil droplets, a method for separating ... 120°C for 20 min. 0.1 mg.L. −1. Thiamine, 0.5 μg.L. −1. Biotin and 0.5 μg.L−1.

  5. Applications of Diatoms as Potential Microalgae in Nanobiotechnology

    Directory of Open Access Journals (Sweden)

    Ahmad Yari Khosroushahi

    2012-05-01

    Full Text Available Introduction: Diatoms are single cell eukaryotic microalgae, which present in nearly every water habitat make them ideal tools for a wide range of applications such as oil explora­tion, forensic examination, environmental indication, biosilica pattern generation, toxicity testing and eutrophication of aqueous ecosystems. Methods: Essential information on diatoms were reviewed and discussed towards impacts of diatoms on biosynthesis and bioremediation. Results: In this review, we present the recent progress in this century on the application of diatoms in waste degradation, synthesis of biomaterial, biomineraliza­tion, toxicity and toxic effects of mineral elements evaluations. Conclusion: Diatoms can be considered as metal toxicity bioindicators and they can be applied for biomineralization, synthesis of biomaterials, and degradation of wastes.

  6. Isolation and biochemical characterization of underwater adhesives from diatoms.

    Science.gov (United States)

    Poulsen, Nicole; Kröger, Nils; Harrington, Matthew J; Brunner, Eike; Paasch, Silvia; Buhmann, Matthias T

    2014-01-01

    Many aquatic organisms are able to colonize surfaces through the secretion of underwater adhesives. Diatoms are unicellular algae that have the capability to colonize any natural and man-made submerged surfaces. There is great technological interest in both mimicking and preventing diatom adhesion, yet the biomolecules responsible have so far remained unidentified. A new method for the isolation of diatom adhesive material is described and its amino acid and carbohydrate composition determined. The adhesive materials from two model diatoms show differences in their amino acid and carbohydrate compositions, but also share characteristic features including a high content of uronic acids, the predominance of hydrophilic amino acid residues, and the presence of 3,4-dihydroxyproline, an extremely rare amino acid. Proteins containing dihydroxyphenylalanine, which mediate underwater adhesion of mussels, are absent. The data on the composition of diatom adhesives are consistent with an adhesion mechanism based on complex coacervation of polyelectrolyte-like biomolecules.

  7. Epibiotic Diatoms Are Universally Present on All Sea Turtle Species.

    Directory of Open Access Journals (Sweden)

    Nathan J Robinson

    Full Text Available The macro-epibiotic communities of sea turtles have been subject to growing interest in recent years, yet their micro-epibiotic counterparts are almost entirely unknown. Here, we provide the first evidence that diatoms are epibionts for all seven extant species of sea turtle. Using Scanning Electron Microscopy, we inspected superficial carapace or skin samples from a single representative of each turtle species. We distinguished 18 diatom taxa from these seven individuals, with each sea turtle species hosting at least two diatom taxa. We recommend that future research is undertaken to confirm whether diatom communities vary between sea turtle species and whether these diatom taxa are facultative or obligate commensals.

  8. Carbon content and C:N ratio of transparent exopolymeric particles (TEP) produced by bubbling exudates of diatoms

    DEFF Research Database (Denmark)

    Mari, Xavier

    1999-01-01

    The carbon content of transparent exopolymeric particles (TEP) was measured in the laboratory in particles produced by bubbling exudates of the diatom Thalassiosira weissflogii, grown under nitrogen non-limited conditions (N:P = 7). The carbon content of these particles (TEP-C) appears to vary...... a coastal area (Kattegat, Denmark), TEP carbon concentration in the surface mixed layer was on the order of 230 ± 150 µg C l-1. This is high relative to other sources of particulate organic carbon (e.g. phytoplankton) and depending on TEP turnover rates, suggests that TEP is an important pathway...... for dissolved organic carbon in coastal seas. The carbon to nitrogen ratio of TEP was measured from particles formed by bubbling exudates of the diatoms T. weissflogii, Skeletonema costatum, Chaetoceros neogracile and C. affinis. Each of these diatom species was grown under various N:P ratios, from N...

  9. 玉米秸秆生物炭对稻田土壤砷、镉形态的影响%Effects of waterlogging and application of bio-carbon from corn stalks on the physico-chemical properties and the forms of arsenic and cadmium in arsenic and cadmium-contaminated soils

    Institute of Scientific and Technical Information of China (English)

    张燕; 铁柏清; 刘孝利; 张淼; 叶长城; 彭鸥; 许蒙

    2018-01-01

    Effects of corn stover biechar (1% addition) prepared at different temperatures (300,400 and 500 ℃) on pH,oxidation-reduction potential and arsenic and cadmium contents in arsenic-cadmium polluted paddy soil under waterlogged conditon were investigated by indoor soil incubation.The corn stover biochar prepared at 300,400 and 500 ℃ were designated as CB-300,CB-400 and CB-500,respectively,with no addition of CB as blank control.The results showed that pyrolysis temperature has a significant effect on physical and chemical properties of corn straw.Increasing the pyrolysis temperature from 300 ℃ to 500 ℃ resulted in increases in aromaticity (corresponding to decrease in hydrophilicity and polarity),ash content and pH in corn stalks.Addition of corn straw biocoke increased The soil pH increased from 0.2 to 1.24 after addition of corn straw biocoke in soil,compared with CK and followed the order:CB-500>CB-400>CB-300>CK,and the pH reached equilibrium with prolongation of culture.The redox potential of soil under flooded condition decreased rapidly,and there was significant difference among different treatments.The higher the temperature of biocarbon preparation,the more obvious decreases in redox potential.The redox potential decreased to the lowest at 96th day.The percentage of extractable Cd in CK,CB-300,CB-400 and CB-500 decreased from 73.55% to 63.46%,57.73%,54.50% and 53.94%,respectively,and the cadmium changed from extractable and oxidizablestate to the residual and reducible state,with the extension of culture time.Soil pH exhibited a significant negative correlation with weak acid extractable cadmium.The content of exchangeable arsenic in the soil under waterlogged condition increased,and the exchangeable arsenic,calcium arsenic,aluminum arsenic and iron arsenic in the soil were increased by 75.68%,20.92% and 13.49% and 48.66%,respectively,however,residuestate arsenic dereased.There was a significant positive correlation between

  10. Coupled states approximation for scattering of two diatoms

    International Nuclear Information System (INIS)

    Heil, T.G.; Green, S.; Kouri, D.J.

    1978-01-01

    The coupled states (CS) approximation is developed in detail for the general case of two colliding diatomic molecules. The high energy limit of the exact Lippmann-Schwinger equation is used to obtain the CS equations so that the sufficiency conditions of Kouri, Heil, and Shimoni apply. In addition, care is taken to ensure correct treatment of parity in the CS, as well as correct labeling of the CS by an effective orbital angular momentum. The analysis follows that given by Shimoni and Kouri for atom-diatom collisions where the coupled rotor angular momentum j 12 and projection lambda 12 replace the single diatom angular momentum j and projection lambda. The result is an expression for the differential scattering amplitude which is a generalization of the highly successful McGuire-Kouri differential scattering amplitude for atom-diatom collisions. Also, the opacity function is found to be a generalization of the Clebsch-Gordon weight atom-diatom expression of Shimoni and Kouri. The diatom-diatom CS body frame T matrix T/sup J/(j 1 'j 2 'j 12 'lambda 12 'vertical-bar j 1 j 2 j 12 lambda 12 ) is also found to be nondiagonal in lambda' 12 ,lambda 12 , just as in the atom-diatom case. The parity and identical molecule interchange symmetries are also considered in detail in both the exact close coupling and CS approximations. Symmetrized expressions for all relevant quantities are obtained, along with the symmetrized coupled equations one must solve. The properly labeled and symmetrized CS equations have not been derived before this present work. The present correctly labeled CS theory is tested computationally by applications to three different diatom-diatom potentials. First we carry out calculations for para-para, ortho-ortho, and ortho-para H 2 -H 2 collisions using the experimental potential of Farrar and Lee

  11. Variation partitioning of diatom species data matrices: Understanding the influence of multiple factors on benthic diatom communities in tropical streams

    Energy Technology Data Exchange (ETDEWEB)

    Bere, Taurai, E-mail: tbere2015@gmail.com; Mangadze, Tinotenda; Mwedzi, Tongai

    2016-10-01

    Elucidating the confounding influence of multiple environmental factors on benthic diatom communities is important in developing water quality predictive models for better guidance of stream management efforts. The objective of this study was to explore the relative impact of metal pollution and hydromorphological alterations in, addition to nutrient enrichment and organic pollution, on diatom taxonomic composition with the view to improve stream diatom-based water quality inference models. Samples were collected twice at 20 sampling stations in the tropical Manyame Catchment, Zimbabwe. Diatom, macroinvertebrate communities and environmental factors were sampled and analysed. The variations in diatom community composition explained by different categories of environmental factors were analysed using canonical correspondence analysis using variance partitioning (partial CCA). The following variations were explained by the different predictor matrices: nutrient levels and organic pollution - 10.4%, metal pollution - 8.3% and hydromorphological factors - 7.9%. Thus, factors other than nutrient levels and organic pollution explain additional significant variation in these diatom communities. Development of diatom-based stream water quality inference models that incorporate metal pollution and hydromorphological alterations, where these are key issues, is thus deemed necessary. - Highlights: • Confounding influences of multiple environmental factors on diatom communities are elucidated. • Variation explained: nutrients + organic pollution - 10.4%, metals - 8.3% and hydromorphological factors - 7.9%. • Calibration of existing or development of new indices may be necessary.

  12. Variation partitioning of diatom species data matrices: Understanding the influence of multiple factors on benthic diatom communities in tropical streams

    International Nuclear Information System (INIS)

    Bere, Taurai; Mangadze, Tinotenda; Mwedzi, Tongai

    2016-01-01

    Elucidating the confounding influence of multiple environmental factors on benthic diatom communities is important in developing water quality predictive models for better guidance of stream management efforts. The objective of this study was to explore the relative impact of metal pollution and hydromorphological alterations in, addition to nutrient enrichment and organic pollution, on diatom taxonomic composition with the view to improve stream diatom-based water quality inference models. Samples were collected twice at 20 sampling stations in the tropical Manyame Catchment, Zimbabwe. Diatom, macroinvertebrate communities and environmental factors were sampled and analysed. The variations in diatom community composition explained by different categories of environmental factors were analysed using canonical correspondence analysis using variance partitioning (partial CCA). The following variations were explained by the different predictor matrices: nutrient levels and organic pollution - 10.4%, metal pollution - 8.3% and hydromorphological factors - 7.9%. Thus, factors other than nutrient levels and organic pollution explain additional significant variation in these diatom communities. Development of diatom-based stream water quality inference models that incorporate metal pollution and hydromorphological alterations, where these are key issues, is thus deemed necessary. - Highlights: • Confounding influences of multiple environmental factors on diatom communities are elucidated. • Variation explained: nutrients + organic pollution - 10.4%, metals - 8.3% and hydromorphological factors - 7.9%. • Calibration of existing or development of new indices may be necessary.

  13. Importance of sampling frequency when collecting diatoms

    KAUST Repository

    Wu, Naicheng

    2016-11-14

    There has been increasing interest in diatom-based bio-assessment but we still lack a comprehensive understanding of how to capture diatoms’ temporal dynamics with an appropriate sampling frequency (ASF). To cover this research gap, we collected and analyzed daily riverine diatom samples over a 1-year period (25 April 2013–30 April 2014) at the outlet of a German lowland river. The samples were classified into five clusters (1–5) by a Kohonen Self-Organizing Map (SOM) method based on similarity between species compositions over time. ASFs were determined to be 25 days at Cluster 2 (June-July 2013) and 13 days at Cluster 5 (February-April 2014), whereas no specific ASFs were found at Cluster 1 (April-May 2013), 3 (August-November 2013) (>30 days) and Cluster 4 (December 2013 - January 2014) (<1 day). ASFs showed dramatic seasonality and were negatively related to hydrological wetness conditions, suggesting that sampling interval should be reduced with increasing catchment wetness. A key implication of our findings for freshwater management is that long-term bio-monitoring protocols should be developed with the knowledge of tracking algal temporal dynamics with an appropriate sampling frequency.

  14. Diuron causes sinking retardation and physiochemical alteration in marine diatoms Thalassiosira pseudonana and Skeletonema marinoi-dohrnii complex.

    Science.gov (United States)

    Khanam, Mst Ruhina Margia; Shimasaki, Yohei; Hosain, Md Zahangir; Mukai, Koki; Tsuyama, Michito; Qiu, Xuchun; Tasmin, Rumana; Goto, Hiroshi; Oshima, Yuji

    2017-05-01

    The present research investigated the effect of diuron on sinking rate and the physiochemical changes in two marine diatoms, Thalassiosira pseudonana (single-celled species) and Skeletonema marinoi-dohrnii complex (chain-forming species). The results revealed that the sinking rate of both diatoms exposed to diuron at a level of 50% effective concentration for growth (EC50) decreased significantly compared with the control. Photosynthetic performance (Fv/Fm and PI ABS ) of both diatoms also decreased significantly with diuron exposure. The number of cells per chain in S. marinoi-dohrnii decreased significantly with diuron treatment, but T. pseudonana cell diameter remained stable. Neutral lipid concentration per cell was significantly higher compared with control at 72 h in both diatom species exposed to EC50 level diuron. And water-soluble protein concentration per cell at 72 h was lower than control in the T. pseudonana EC50 group only. These biochemical changes may decrease specific gravity of cells and seems to cause a decreased sinking rate in diatoms. The positive significant correlation between the numbers of cells per chain and sinking rate in S. marinoi-dohrnii indicated that chain length is also an important factor in sinking rate regulation for chain-forming diatoms. Thus, our present study suggested that suppression of photosynthetic performance and the resultant physiochemical changes induced the decreased sinking rate that may inhibit the normal survival strategy (avoidance from the surface layer where strong light either causes photo-inhibition or interrupts resting cell formation). Therefore, the use of antifouling agents should be considered for the sustainable marine environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Effect of Banana Stalk Organic Fertilizer on the Growth of Chinese Cabbage

    Institute of Scientific and Technical Information of China (English)

    Zheli; DING; Lina; HAN; Zhiqiang; JIN; Bizun; WANG; Huicai; ZENG; Wei; ZHENG; Yingdui; HE; Xiaoping; ZANG

    2016-01-01

    In order to solve the problem of waste disposal after banana harvest,we use banana stalk to produce banana stalk organic fertilizer,through a plot experiment. We compare the influence of normal organic fertilizer( Wanlubao) and banana stalk organic fertilizer as base fertilizers on Chinese cabbage growth,and evaluate the economic benefits of banana stalk organic fertilizer. The results show that organic fertilizer has little effect on water content and nutrient content of Chinese cabbage,but has significant effect on plant height and leaf width. Using organic fertilizer can increase the production of Chinese cabbage by 22. 50%- 43. 10%. With 6750 kg / ha normal organic fertilizer,Chinese cabbage gets the highest yield,which reaches 30135 kg / ha,followed by the treatment of 6750 kg / ha stalk organic fertilizer. At farmers’ conventional fertilization level( 4500 kg / ha),stalk organic fertilizer can increase the yield by more than 3. 50% in comparison with the normal organic fertilizer,and the economic benefit increases by 1800 yuan / ha. As a kind of banana waste cycling product,banana stalk organic fertilizer is of low cost and good effect,and can be used instead of normal organic fertilizer.

  16. Victims of stalking in India: A study of girl college students in Tirunelveli City

    OpenAIRE

    Jaishankar Karuppannan; Kosalai Puthisigamani

    2007-01-01

    The word 'stalking' was not commonly known in India, until Priyadharshini Mattoo's case (1996) hit the headlines. Eve teasing, a colloquial word for gender harassment is popularly known and Tamil Nadu Prohibition of Eve-Teasing Act, 1998 on that was developed after the brutal killing of a girl named Sarika Shah in Chennai. Though, stalking is there in the past, it was not acknowledged with this terminology and it was always merged with Eve teasing. On the other hand, stalking is much graver t...

  17. Distribution and abundance of diatom species from coastal waters of Karachi, Pakistan

    International Nuclear Information System (INIS)

    Khokhar, F. N.; Burhan, Z.; Iqbal, P.; Abbasi, J.; Siddiqui, P.

    2016-01-01

    This is the first comprehensive study on the distribution and abundance of diatom species from the coastal and nearshore waters of Karachi, Pakistan, bordering northern Arabian Sea. A total of 20 genera are recorded in high abundance (Cerataulina, Chaetoceros, Coscinodiscus, Cylindrotheca, Eucampia, Guinardia, Haslea, Hemiaulus, Lauderia, Lennoxia, Leptocylindrus, Navicula, Nitzschia, Trieres, Planktoniella, Pleurosigma, Pseudo-nitzschia, Rhizosolenia, Thalassionema and Thalassiosira). The most abundant genera were observed Guinardia, Chaetoceros, Leptocylindrus, Nitzschia and Lennoxia at all stations. Manora coastal station (MI-1) had high abundance corresponding with high Chlorophyll a (130 meu gL- l) values. Minimum abundance and low chlorophyll a value (0.05μgL-l) were observed at Mubarak Village coastal station (MV-1). Diatom abundance showed significant correlation with Chlorophyll a. In present study 12 centric and 8 pennate forms were recorded and similarly high diversity of centric taxa was observed compared to pennate forms. A total of 134 species are recorded of which 40 species were observed at four stations, 31species at three stations, 23 at two stations and 40 species only at one station. The total phytoplankton and diatom peak abundance was observed during NE monsoon (winter season) associated with nutrient loading through up-sloping of nutrient rich water upwelled off of Oman during South West monsoon. Overall higher diversity was observed at Manora coastal and nearshore stations (MI-1, MI-2) indicating the influence of organic pollution loading from Layari and Malir rivers. (author)

  18. Diatoms from a peat bog on the Pešter plateau (southwestern Serbia: New records for diatom flora of Serbia

    Directory of Open Access Journals (Sweden)

    Vidaković Danijela

    2016-01-01

    Full Text Available The distribution of diatoms was studied in three types of diatom communities (epiphytes, benthos and plankton of a peat bog on the Pešter plateau. The observed diatom flora inhabited all investigated communities, comprising in total 250 taxa in 53 genera. Among them, 45 taxa were new records for the Serbian diatom flora. Identified taxa belonged to different groups of algae, however alkaliphile diatoms were dominant. New ecological data for Encyonopsis minuta, Pinnularia isostauron and P. marchica are presented here. All the diatoms were documented by light micrographs, and brief notes on their morphology, distribution and ecology are provided. [Projekat Ministarstva nauke Republike Srbije, br. TR 037009

  19. Codon adaptation and synonymous substitution rate in diatom plastid genes.

    Science.gov (United States)

    Morton, Brian R; Sorhannus, Ulf; Fox, Martin

    2002-07-01

    Diatom plastid genes are examined with respect to codon adaptation and rates of silent substitution (Ks). It is shown that diatom genes follow the same pattern of codon usage as other plastid genes studied previously. Highly expressed diatom genes display codon adaptation, or a bias toward specific major codons, and these major codons are the same as those in red algae, green algae, and land plants. It is also found that there is a strong correlation between Ks and variation in codon adaptation across diatom genes, providing the first evidence for such a relationship in the algae. It is argued that this finding supports the notion that the correlation arises from selective constraints, not from variation in mutation rate among genes. Finally, the diatom genes are examined with respect to variation in Ks among different synonymous groups. Diatom genes with strong codon adaptation do not show the same variation in synonymous substitution rate among codon groups as the flowering plant psbA gene which, previous studies have shown, has strong codon adaptation but unusually high rates of silent change in certain synonymous groups. The lack of a similar finding in diatoms supports the suggestion that the feature is unique to the flowering plant psbA due to recent relaxations in selective pressure in that lineage.

  20. Effect of the Silica Content of Diatoms on Protozoan Grazing

    Directory of Open Access Journals (Sweden)

    Shuwen Zhang

    2017-06-01

    Full Text Available This study examined the effect that silica content in diatom cells has on the behavior of protists. The diatoms Thalassiosira weissflogii and T. pseudonana were cultured in high or low light conditions to achieve low and high silica contents, respectively. These cells were then fed to a heterotrophic dinoflagellate Noctiluca scintillans and a ciliate Euplotes sp. in single and mixed diet experiments. Our results showed that in general, N. scintillans and Euplotes sp. both preferentially ingested the diatoms with a low silica content rather than those with a high silica content. However, Euplotes sp. seemed to be less influenced by the silica content than was N. scintillans. In the latter case, the clearance and ingestion rate of the low silica diatoms were significantly higher, both in the short (6-h and long (1-d duration grazing experiments. Our results also showed that N. scintillans required more time to digest the high silica-containing cells. As the high silica diatoms are harder to digest, this might explain why N. scintillans exhibits a strong preference for the low silica prey. Thus, the presence of high silica diatoms might limit the ability of the dinoflagellate to feed. Our findings suggest that the silica content of diatoms affects their palatability and digestibility and, consequently, the grazing activity and selectivity of protozoan grazers.

  1. Diatom feeding across trophic guilds in tidal flat nematodes, and the importance of diatom cell size

    Science.gov (United States)

    Moens, Tom; Vafeiadou, Anna-Maria; De Geyter, Ellen; Vanormelingen, Pieter; Sabbe, Koen; De Troch, Marleen

    2014-09-01

    We examine the capacity of nematodes from three feeding types (deposit feeder, epistrate feeder, predator) to utilize microphytobenthos (MPB), and assess whether diatom cell size and consumer body size are important drivers of their feeding. We analyzed natural stable isotope ratios of carbon and nitrogen in abundant nematode genera and a variety of carbon sources at an estuarine intertidal flat. All nematodes had δ13C indicating that MPB is their major carbon source. δ15N, however, demonstrated that only one deposit and one epistrate feeder genus obtained most of their carbon from direct grazing on MPB, whereas other deposit feeders and predators obtained at least part of their carbon by predation on MPB grazers. We then performed a microcosm experiment in which equal cell numbers of each of three differently sized strains of the pennate diatom Seminavis were offered as food to four, one and one genera of deposit feeders, epistrate feeders and predators, respectively. Previous studies have shown that all but the epistrate feeder ingest whole diatoms, whereas the epistrate feeder pierces cells and sucks out their contents. Most genera showed markedly higher carbon absorption from medium and large cells than from small ones. When considering the number of cells consumed, however, none of the nematodes which ingest whole cells exhibited a clear preference for any specific diatom size. The epistrate feeder was the smallest nematode taxon considered here, yet it showed a marked preference for large cells. These results highlight that the feeding mechanism is much more important than consumer size as a driver of particle size selection in nematodes grazing MPB.

  2. The expression, purification, crystallization and preliminary X-ray analysis of a subcomplex of the peripheral stalk of ATP synthase from bovine mitochondria

    International Nuclear Information System (INIS)

    Silvester, Jocelyn A.; Kane Dickson, Veronica; Runswick, Michael J.; Leslie, Andrew G. W.; Walker, John E.

    2006-01-01

    A recombinant subcomplex of the peripheral stalk or stator domain of the ATP synthase from bovine mitochondria has been crystallized and a native data set has been collected to 2.8 Å resolution. A subcomplex of the peripheral stalk or stator domain of the ATP synthase from bovine mitochondria has been expressed to high levels in a soluble form in Escherichia coli. The subcomplex consists of residues 79–184 of subunit b, residues 1–124 of subunit d and the entire F 6 subunit (76 residues). It has been purified and crystallized by vapour diffusion. The morphology and diffraction properties of the crystals of the subcomplex were improved by the presence of thioxane or 4-methylpyridine in the crystallization liquor. With a synchrotron-radiation source, these crystals diffracted to 2.8 Å resolution. They belong to the monoclinic space group P2 1

  3. Comparing optical properties of different species of diatoms

    DEFF Research Database (Denmark)

    Maibohm, Christian; Friis, Søren Michael Mørk; Su, Y.

    2015-01-01

    species dependent with huge variety in size, shape, and micro- structure. We have experimentally investigated optical properties of frustules of several species of diatoms to further understand light harvesting properties together with commo n traits, effects and differences between the different...... analysis software. The software uses parameters which are extracted from experimental im ages as basis for simulation and allows us to extract the influence of the different elements of the frustule. The information could be used both for predicting optical properties of diatoms and by changing frustule...... parameters, maybe by altering growth conditions of the diatoms tailor their optical properties....

  4. A Zeeman slower for diatomic molecules

    Science.gov (United States)

    Petzold, M.; Kaebert, P.; Gersema, P.; Siercke, M.; Ospelkaus, S.

    2018-04-01

    We present a novel slowing scheme for beams of laser-coolable diatomic molecules reminiscent of Zeeman slowing of atomic beams. The scheme results in efficient compression of the one-dimensional velocity distribution to velocities trappable by magnetic or magneto-optical traps. We experimentally demonstrate our method in an atomic testbed and show an enhancement of flux below v = 35 m s‑1 by a factor of ≈20 compared to white light slowing. 3D Monte Carlo simulations performed to model the experiment show excellent agreement. We apply the same simulations to the prototype molecule 88Sr19F and expect 15% of the initial flux to be continuously compressed in a narrow velocity window at around 10 m s‑1. This is the first experimentally shown continuous and dissipative slowing technique in molecule-like level structures, promising to provide the missing link for the preparation of large ultracold molecular ensembles.

  5. Cationic amino acids specific biomimetic silicification in ionic liquid: a quest to understand the formation of 3-D structures in diatoms.

    Directory of Open Access Journals (Sweden)

    Rajesh Ramanathan

    Full Text Available The intricate, hierarchical, highly reproducible, and exquisite biosilica structures formed by diatoms have generated great interest to understand biosilicification processes in nature. This curiosity is driven by the quest of researchers to understand nature's complexity, which might enable reproducing these elegant natural diatomaceous structures in our laboratories via biomimetics, which is currently beyond the capabilities of material scientists. To this end, significant understanding of the biomolecules involved in biosilicification has been gained, wherein cationic peptides and proteins are found to play a key role in the formation of these exquisite structures. Although biochemical factors responsible for silica formation in diatoms have been studied for decades, the challenge to mimic biosilica structures similar to those synthesized by diatoms in their natural habitats has not hitherto been successful. This has led to an increasingly interesting debate that physico-chemical environment surrounding diatoms might play an additional critical role towards the control of diatom morphologies. The current study demonstrates this proof of concept by using cationic amino acids as catalyst/template/scaffold towards attaining diatom-like silica morphologies under biomimetic conditions in ionic liquids.

  6. Discovery of dense aggregations of stalked crinoids in Izu-Ogasawara trench, Japan.

    Science.gov (United States)

    Oji, Tatsuo; Ogawa, Yujiro; Hunter, Aaron W; Kitazawa, Kota

    2009-06-01

    Stalked crinoids are recognized as living fossils that typically inhabit modern deep-water environments exceeding 100 m. Previous records of stalked crinoids from hadal depths (exceeding 6000 m) are extremely rare, and no in-situ information has been available. We show here that stalked crinoids live densely on rocky substrates at depths over 9000 m in the Izu-Ogasawara Trench off the eastern coast of Japan, evidenced by underwater photos and videos taken by a remotely operated vehicle. This is the deepest in-situ observation of stalked crinoids and demonstrates that crinoid meadows can exist at hadal depths close to the deepest ocean floor, in a fashion quite similar to populations observed in shallower depths.

  7. The Intersection of Stalking and the Severity of Intimate Partner Abuse.

    Science.gov (United States)

    Brady, Patrick Q; Hayes, Brittany E

    2018-04-01

    Using data from the Chicago Women's Health Risk Study (N = 464), this study examined the intersection of stalking and the severity of intimate partner abuse while controlling for previously identified risk factors of intimate partner homicide. Findings indicate that (a) victims of life-threatening abuse by an intimate partner were significantly more likely to experience stalking than victims of nonlethal abuse; (b) after controlling for key risk factors, stalking increased the risk of life-threatening abuse; and (c) threats to kill the victim if she left was the only significant stalking-related behavior that increased the risk for life-threatening abuse. In addition, an offender's prior record and a higher number of previous abusive incidents increased the risk of life-threatening abuse. Implications for prevention and future directions for research are discussed.

  8. Study of Nutrient Content Variation in Bulb And Stalk of Onions ...

    African Journals Online (AJOL)

    acer

    Keywords: Onion bulbs and stalks, proximate, nutrient elements, vitamins A and C; oxalate. ... application of fertilizers, manure, compost and ..... iron products, the use of natural source of Fe such .... in Fish and Sediment from Kubanni River,.

  9. Colonization of habitat islands in the deep sea: recruitment to glass sponge stalks

    Science.gov (United States)

    Beaulieu, Stace E.

    2001-04-01

    Biogenic structures in the deep sea often act as hard substratum 'islands' for the attachment of encrusting fauna. At an abyssal station in the NE Pacific, stalks of hexactinellid sponges in the genus Hyalonema are habitat islands for species-rich epifaunal communities. An experimental study was conducted to (1) determine the colonization rates of artificial Hyalonema stalks, (2) compare the species composition and diversity of recruits to newly available substrata to that of the natural communities, and (3) examine the vertical distribution of recruits. Four sets of six artificial sponge stalks, constructed of Hyalonema spicules, were deployed at 4100 m depth for 3- to 5-month periods. There was no difference in net colonization or immigration rate among the four deployments. Colonization rates were similar to those reported for other deep-sea, hard substratum recruitment experiments. The taxa that recruited to the artificial stalks were a subset of the taxa found in natural communities. However, several taxa important in structuring natural communities did not recruit to the artificial stalks. The two taxa with the highest invasion rates, a calcareous foraminiferan ( Cibicides lobatulus) and a serpulid polychaete ( Bathyvermilia sp.), also were the two taxa with greatest relative abundance in natural communities. Vertical distributions of Cibicides and an agglutinated foraminiferan ( Telammina sp.) were skewed towards the top of the artificial stalks, potentially because of active habitat selection. These results have several implications for natural Hyalonema stalk communities. Most importantly, species composition and abundance of individuals in the stalk communities appear to be maintained by frequent recruitment of a few common taxa and infrequent recruitment of many rare taxa. An argument is presented for temporal-mosaic maintenance of diversity in these deep-sea, hard substratum communities.

  10. Sequence Identification, Recombinant Production, and Analysis of the Self-Assembly of Egg Stalk Silk Proteins from Lacewing Chrysoperla carnea.

    Science.gov (United States)

    Neuenfeldt, Martin; Scheibel, Thomas

    2017-06-13

    Egg stalk silks of the common green lacewing Chrysoperla carnea likely comprise at least three different silk proteins. Based on the natural spinning process, it was hypothesized that these proteins self-assemble without shear stress, as adult lacewings do not use a spinneret. To examine this, the first sequence identification and determination of the gene expression profile of several silk proteins and various transcript variants thereof was conducted, and then the three major proteins were recombinantly produced in Escherichia coli encoded by their native complementary DNA (cDNA) sequences. Circular dichroism measurements indicated that the silk proteins in aqueous solutions had a mainly intrinsically disordered structure. The largest silk protein, which we named ChryC1, exhibited a lower critical solution temperature (LCST) behavior and self-assembled into fibers or film morphologies, depending on the conditions used. The second silk protein, ChryC2, self-assembled into nanofibrils and subsequently formed hydrogels. Circular dichroism and Fourier transform infrared spectroscopy confirmed conformational changes of both proteins into beta sheet rich structures upon assembly. ChryC3 did not self-assemble into any morphology under the tested conditions. Thereby, through this work, it could be shown that recombinant lacewing silk proteins can be produced and further used for studying the fiber formation of lacewing egg stalks.

  11. Effect of Mowing Cotton Stalks and Preventing Plant Re-Growth on Post-Harvest Reproduction of Meloidogyne incognita

    Science.gov (United States)

    Davis, Richard F.; Kemerait, Robert C.

    2010-01-01

    The southern root-knot nematode (Meloidogyne incognita) is a major parasite of cotton in the U.S., and management tactics for this nematode attempt to minimize population levels. We compared three post-harvest practices for their ability to reduce nematode population levels in the field, thereby reducing initial nematode population for the next year's crop. The three practices tested were: 1) chemical defoliation before harvest plus cutting cotton stalks after harvest, 2) chemical defoliation plus applying a herbicide to kill plants prior to cutting the stalks, and 3) chemical defoliation without cutting stalks. Experiments were conducted in both the greenhouse and in the field. The greenhouse experiments demonstrated that M. incognita reproduction (measured as egg counts and root gall rating indices) was significantly greater when stalks were not cut. Cutting stalks plus applying herbicide to kill cotton roots did not significantly reduce nematode reproduction compared to cutting stalks alone. In field experiments, cutting stalks reduced egg populations and root galling compared to defoliation without stalk cutting. In a greenhouse bioassay which used soil from the field plots, plants grown in soil from the defoliation only treatment had greater root gall ratings and egg counts than in the stalk cutting plus herbicide treatment. Therefore, we conclude that cutting cotton stalks immediately after harvest effectively reduces M. incognita reproduction, and may lead to a lower initial population density of this nematode in the following year. PMID:22736845

  12. Isolation and Characterization of Silaffin that Catalyze Biosilica Formation from Marine Diatom Chaetoceros gracilis

    Directory of Open Access Journals (Sweden)

    AGNES IMELDA MANURUNG

    2007-09-01

    Full Text Available The method of making silica in industries requires extreme conditions. The finding of proteins involved in the formation of biosilica from diatoms, has opened up an alternative way of production. Chaetoceros gracilis is one of the diatoms, which is potential in producing silaffin protein. This study aimed to isolate and to characterize the protein. We also analyzed the protein activity toward tetraethoxyorthosilicate (TEOS substrate in in vitro reaction. Diatom biomass was harvested and further kept in 2% SDS/100 mM EDTA solution. Protein isolation was conducted by dissolving the silica and separating the protein by soaking in 2 M HF/8 M NH4F. Protein concentration was analyzed using Bradford method and the molecular weight was estimated through SDS-PAGE. Protein activity was observed by reacting it with TEOS substrate to form silica polymer and measured by colorimetric molibdate assay. Protein concentration was 1.20 mg/ml and appeared filamentous. The apparent molecular weights consisted of 12, 23, 42, 44 kDa. These protein was able to polymerize the silica at room temperature within 10 min. As much as 85.65 μmol TEOS was polymerized per 1.4 × 106 silaffin protein per min. SEM analysis showed the formation of spherical, aggregate biosilica.

  13. Isolation and Characterization of Silaffin that Catalyze Biosilica Formation from Marine Diatom Chaetoceros gracilis

    Directory of Open Access Journals (Sweden)

    AGNES IMELDA MANURUNG

    2007-09-01

    Full Text Available The method of making silica in industries requires extreme conditions. The finding of proteins involved in the formation of biosilica from diatoms, has opened up an alternative way of production. Chaetoceros gracilis is one of the diatoms, which is potential in producing silaffin protein. This study aimed to isolate and to characterize the protein. We also analyzed the protein activity toward tetraethoxyorthosilicate (TEOS substrate in in vitro reaction. Diatom biomass was harvested and further kept in 2% SDS/100 mM EDTA solution. Protein isolation was conducted by dissolving the silica and separating the protein by soaking in 2 M HF/8 M NH4F. Protein concentration was analyzed using Bradford method and the molecular weight was estimated through SDS-PAGE. Protein activity was observed by reacting it with TEOS substrate to form silica polymer and measured by colorimetric molibdate assay. Protein concentration was 1.20 mg/ml and appeared filamentous. The apparent molecular weights consisted of 12, 23, 42, 44 kDa. These protein was able to polymerize the silica at room temperature within 10 min. As much as 85.65 mol TEOS was polymerized per 1.4 x 106 silaffin protein per min. SEM analysis showed the formation of spherical, aggregate biosilica.

  14. Cytoplasmic inheritance of parent-offspring cell structure in the clonal diatom Cyclotella meneghiniana.

    Science.gov (United States)

    Shirokawa, Yuka; Shimada, Masakazu

    2016-11-16

    In cytoplasmic inheritance, structural states of a parent cell could be transmitted to offspring cells via two mechanisms. The first is referred to as the hangover of parent structure, where the structure itself remains and faithfully transmits within offspring cells; the second is structural inheritance, wherein the parent structure functions as a template for development of new offspring structure. We estimated to what extent the parent structure affects the development of offspring structure by structural inheritance, using a clone of the diatom Cyclotella meneghiniana The cell has two siliceous valves (a cell wall part at both cell poles): one is inherited from the parent and the other is newly formed. We estimated cytoplasmic heritability by comparing valve traits (central fultoportulae (CTFP), striae, central area, and cell diameter) of parent and new offspring valves, using single-cell isolation and valve labelling. Parent-offspring valve trait regressions showed that all traits, except CTFP, were significantly correlated. We formulated a quantitative genetic model considering the diatom inheritance system and revealed short-term rapid evolution compared with other inheritance systems. Diatom structural inheritance will have evolved to enable clonal populations to rapidly acquire and maintain suitable structures for temporal changes in environments and life-cycle stages. © 2016 The Author(s).

  15. FRET Response of a Modified Ribose Receptor Expressed in the Diatom Thalassiosira pseudonana

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Hanna

    2011-08-26

    The ability to insert complex proteins into silica has many applications including biosensing. Previous research has demonstrated how to direct proteins to the biosilica of diatoms [1]. Here, we show that a complex fusion protein that includes an enzyme, a bacterial ribose periplasmic binding protein, flanked by fluorescent proteins constituting a FRET pair can remain functional in the frustules of living diatoms. A Sil3 tag is attached to the N-terminal end to localize the fusion protein to frustules of the diatom Thalassiosira pseudonana. When ribose was applied, a larger decrease in FRET response was seen in transformed cells than in untransformed cells. Multiple forms of the expression vector were tested to find the optimal system; specifically, a one-vector system was compared to a two-vector system and the gDNA version of the Sil3 localization tag was compared to the cDNA version. The optimal system was found to be a one-vector system with the genomic version of the Sil3 tag to direct the protein to the frustules. Localization of the enzyme to the frustules was further confirmed through cell fluorescence imaging.

  16. Time Course of Resolution of Hyperprolactinemia After Transsphenoidal Surgery Among Patients Presenting with Pituitary Stalk Compression.

    Science.gov (United States)

    Zaidi, Hasan A; Cote, David J; Castlen, Joseph P; Burke, William T; Liu, Yong-Hui; Smith, Timothy R; Laws, Edward R

    2017-01-01

    Primary lactotroph disinhibition, or stalk effect, occurs when mechanical compression of the pituitary stalk disrupts the tonic inhibition by dopamine released by the hypothalamus. The resolution of pituitary stalk effect-related hyperprolactinemia postoperatively has not been studied in a large cohort of patients. We performed a retrospective review to investigate the time course of recovery of lactotroph disinhibition after transsphenoidal surgery. Medical records were retrospectively reviewed for all patients undergoing transsphenoidal surgery with the senior author from April 2008 to November 2014. Of 556 pituitary adenomas, 289 (52.0%) were eliminated: 77 (13.9%) had an immunohistochemically confirmed prolactinoma, 119 (21.4%) patients had previous surgery, 93 (16.7%) had incomplete medical records, leaving 267 patients (48.0%) for final analysis. Of these patients, 72 (27.0%) had increased serum prolactin levels (≥23.3 ng/mL), suggestive of pituitary stalk effect (maximum prolactin level = 148.0 ng/mL). Patients with stalk effect were more likely than those with normal serum prolactin levels to present with menstrual dysfunction (29.7% vs. 19.4%; P Transsphenoidal surgery can provide durable normalization of serum prolactin levels and related symptoms caused by pituitary stalk compression-related lactotroph disinhibition. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Behavioral and Mental Health Correlates of Youth Stalking Victimization: A Latent Class Approach.

    Science.gov (United States)

    Reidy, Dennis E; Smith-Darden, Joanne P; Kernsmith, Poco D

    2016-12-01

    Although recognized as a public health problem, little attention has been paid to the problem of stalking among youth. Latent profile analysis was used to identify latent groups of adolescent stalking victims and their behavioral and mental health correlates. A cross-sectional sample of 1,236 youths were randomly selected from 13 schools stratified by community risk level (i.e., low, moderate, and high risk) and gender. Students completed surveys assessing behavioral indicators of stalking victimization, as well as substance use, sexual behavior, dating violence, and psychiatric symptoms. Data were collected in 2013 and data analyses were performed in 2015. Analysis indicated the presence of a non-victim class, a minimal exposure class, and a victim class for boys and girls alike. Approximately 14% of girls and 13% of boys were in the stalking victim class. Adolescents in the victim class reported more symptoms of post-traumatic stress, mood disorder, and hopelessness, as well as more instances of alcohol use, binge drinking, and physical dating violence victimization. Girls in the victim class also reported engaging in sexting behaviors and oral sex with significantly more partners than their non-victim peers. These findings provide valuable knowledge of the prevalence and pertinent health correlates of stalking victimization in adolescence. The data suggest a substantial proportion of adolescents are victims of stalking and are likewise at risk for a number of deleterious health outcomes. As such, this population merits further attention by prevention researchers and practitioners. Published by Elsevier Inc.

  18. Enzymatic saccharification of high pressure assist-alkali pretreated cotton stalk and structural characterization.

    Science.gov (United States)

    Du, Shuang-kui; Su, Xia; Yang, Weihua; Wang, Yanqin; Kuang, Meng; Ma, Lei; Fang, Dan; Zhou, Dayun

    2016-04-20

    Cotton stalk is a potential biomass for bioethanol production, while the conversion of direct saccharification or biotransformation of cotton stalk is extremely low due to the recalcitrant nature of lignocellulose. To enhance the enzymatic conversion of cotton stalks, the enzymatic saccharification parameters of high pressure assist-alkali pretreatment (HPAP) cotton stalk were optimized in the present study. Results indicated that a maximum reducing sugar yield of 54.7g/100g dry biomass cellulose was achieved at a substrate concentration of 2%, 100rpm agitation, 0.6g/g enzyme loading, 40°C hydrolysis temperature, 50h saccharification time, and pH 5.0. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used to identify structural changes in native, pretreated biomass and hydrolyzed residues. Structural analysis revealed large part of amorphous cellulose and partial crystalline cellulose in the HPAP cotton stalk were hydrolyzed during enzymatic treatment. HPAP cotton stalk can be used as a potential feed stock for bioethanol production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Automated Diatom Classification (Part A: Handcrafted Feature Approaches

    Directory of Open Access Journals (Sweden)

    Gloria Bueno

    2017-07-01

    Full Text Available This paper deals with automatic taxa identification based on machine learning methods. The aim is therefore to automatically classify diatoms, in terms of pattern recognition terminology. Diatoms are a kind of algae microorganism with high biodiversity at the species level, which are useful for water quality assessment. The most relevant features for diatom description and classification have been selected using an extensive dataset of 80 taxa with a minimum of 100 samples/taxon augmented to 300 samples/taxon. In addition to published morphological, statistical and textural descriptors, a new textural descriptor, Local Binary Patterns (LBP, to characterize the diatom’s valves, and a log Gabor implementation not tested before for this purpose are introduced in this paper. Results show an overall accuracy of 98.11% using bagging decision trees and combinations of descriptors. Finally, some phycological features of diatoms that are still difficult to integrate in computer systems are discussed for future work.

  20. A Simplified Quantum Mechanical Model of Diatomic Molecules

    Science.gov (United States)

    Nielsen, Lars Drud

    1978-01-01

    Introduces a simple one-dimensional model of a diatomic molecule that can explain all the essential features of a real two particle quantum mechanical system and gives quantitative results in fair agreement with those of a hydrogen molecule. (GA)

  1. Studies on new antifreeze protein from the psychrophilic diatom ...

    African Journals Online (AJOL)

    Studies on new antifreeze protein from the psychrophilic diatom, Fragilariopsis cylindrus. ... African Journal of Biotechnology. Journal Home · ABOUT THIS ... The predicted gene product, AfpA, had a molecular mass of 27 kDa. Expression of ...

  2. Analytic vibration-rotational matrix elements for diatomic molecules

    International Nuclear Information System (INIS)

    Bouanich, J.P.

    1987-01-01

    The vibration-rotational matrix elements for infrared or Raman transitions vJ → v'J' of diatomic molecules are calculated for powers of the reduced displacement X from parameters of the Dunham potential-energy function. (orig.)

  3. Acidification counteracts negative effects of warming on diatom silicification

    KAUST Repository

    Coello-Camba, Alexandra

    2016-10-24

    Diatoms are a significant group contributing up to 40 % of annual primary production in the oceans. They have a special siliceous cell wall that, acting as a ballast, plays a key role in the sequestration of global carbon and silica. Diatoms dominate primary production in the Arctic Ocean, where global climate change is causing increases in water temperature and in the partial pressure of CO2 (pCO2). Here we show that as water temperature increases diatoms become stressed, grow to smaller sizes, and decrease their silicification rates. But at higher pCO2, as the pH of seawater decreases, silica incorporation rates are increased. In a future warmer Arctic ocean diatoms may have a competitive advantage under increased ocean acidification, as increased pCO2 counteracts the adverse effects of increasing temperature on silicification and buffers its consequences in the biogeochemical cycles of carbon and silica.

  4. Acidification counteracts negative effects of warming on diatom silicification

    KAUST Repository

    Coello-Camba, Alexandra; Agusti, Susana

    2016-01-01

    Diatoms are a significant group contributing up to 40 % of annual primary production in the oceans. They have a special siliceous cell wall that, acting as a ballast, plays a key role in the sequestration of global carbon and silica. Diatoms dominate primary production in the Arctic Ocean, where global climate change is causing increases in water temperature and in the partial pressure of CO2 (pCO2). Here we show that as water temperature increases diatoms become stressed, grow to smaller sizes, and decrease their silicification rates. But at higher pCO2, as the pH of seawater decreases, silica incorporation rates are increased. In a future warmer Arctic ocean diatoms may have a competitive advantage under increased ocean acidification, as increased pCO2 counteracts the adverse effects of increasing temperature on silicification and buffers its consequences in the biogeochemical cycles of carbon and silica.

  5. Modified Ribose Receptor Response in Isolated Diatom Frustules

    Energy Technology Data Exchange (ETDEWEB)

    Fairbanks, Carly R.

    2011-08-26

    Diatoms are a distinctive group of microalgae with the unique ability to produce a highly-ordered biosilica matrix, known as the frustule. Diatoms hold significant potential in the biotechnology field as a silica scaffold for embedding proteins. In this study, we analyzed the funtionalization of biosilica with a receptor complex through genetic modification of the diatom, Thalassiosira pseudonana. Through the use of Foerster Resonance Energy Transfer (FRET), the receptor was shown to remain active in transformed frustules after the inner cellular contents were removed. In addition to protein functionality, growth conditions for T. pseudonana were optimized. Untransformed cultures receiving aeration grew more rapidly than stagnant untransformed cultures. Surprisingly, transformed cultures grew more quickly than untransformed cultures. This study demonstrates isolated diatom frustules provide an effective scaffold for embedded receptor complexes. Through this research, we provide the groundwork for the development of new biosensors for use in diagnostics and environmental remediation.

  6. Pliocene diatoms from the Bryce Canyon Area, Utah

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    habitat. The fragmentary condition of these indicated agitation during sedimentation. The ratio between the planktonic and benthonic diatoms indicated near-shore deposition. The two extinct species (?), @iSurirella craticula@@ (= @iStictodesmis craticula...

  7. Enhanced adsorption of trivalent arsenic from water by functionalized diatom silica shells.

    Directory of Open Access Journals (Sweden)

    Jianying Zhang

    Full Text Available The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino groups to effectively remove arsenic in its toxic As(III form (arsenite predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film and internal (intraparticle diffusion can be rate-determining for As(III adsorption. Fourier transform infrared spectroscopy (FTIR indicated that the thiol and amino groups potentially responsible for As(III adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III and thiol groups, and through the surface complexation between As(III and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III adsorption capacity holds promise for the treatment of As(III containing wastewater.

  8. Biogenic silica dissolution in diatom aggregates: insights from reactive transport modelling

    KAUST Repository

    Moriceau, B

    2014-12-15

    © Inter-Research 2014. Diatom aggregates contribute significantly to the vertical sinking flux of particulate matter in the ocean. These fragile structures form a specific microhabitat for the aggregated cells, but their internal chemical and physical characteristics remain largely unknown. Studies on the impact of aggregation on the Si cycle led to apparent inconsistency. Despite a lower biogenic silica (bSiO2) dissolution rate and diffusion of the silicic acid (dSi) being similar in aggregates and in sea-water, dSi surprisingly accumulates in aggregates. A reaction-diffusion model helps to clarify this incoherence by reconstructing dSi accumulation measured during batch experiments with aggregated and non-aggregated Skeletonema marinoi and Chaetoceros decipiens. The model calculates the effective bSiO2 dissolution rate as opposed to the experimental apparent bSiO2 dissolution rate, which is the results of the effective dissolution of bSiO2 and transport of dSi out of the aggregate. In the model, dSi transport out of the aggregate is modulated by alternatively considering retention (decrease of the dSi diffusion constant) and adsorption (reversible chemical bonds between dSi and the aggregate matrix) processes. Modelled bSiO2 dissolution is modulated by the impact of dSi concentration inside aggregates and diatom viability, as enhanced persistence of metabolically active diatoms has been observed in aggregates. Adsorption better explains dSi accumulation within and outside aggregates, raising the possible importance of dSi travelling within aggregates to the deep sea (potentially representing 20% of the total silica flux). The model indicates that bSiO2 dissolution is effectively decreased in aggregates mainly due to higher diatom viability but also to other parameters discussed herein.

  9. Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms.

    Science.gov (United States)

    Graff van Creveld, Shiri; Rosenwasser, Shilo; Levin, Yishai; Vardi, Assaf

    2016-10-01

    Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered "ocean deserts" due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom's response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (chronic (>5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment. © 2016 American Society of Plant Biologists. All Rights Reserved.

  10. Effects of thidiazuron and paclobutrazol on regeneration potential of tulip flower stalk explants in vitro and subsequent shoot multiplication

    Directory of Open Access Journals (Sweden)

    Małgorzata Podwyszyńska

    2011-01-01

    Full Text Available The effects of TDZ and paclobutrazol on the primary regeneration on tulip flower stalk explants of six cultivars and subsequent shoot multiplication were examined. Explants, flower stalk slices, were excised from cooled and subsequently forced bulbs. The explants were incubated for two months in darkness on medium containing NAA and cytokinins, 2iP and BAP, as control, or TDZ (0.5-4 mg l-1 and paclobutrazol (0.05-0.4 mg l-1. Then, the regenerating explants were subcultured on medium with TDZ and NAA applied at low concentrations. Different regeneration capabilities were found depending on cultivar and growth regulators. The percentage of explants forming leaf-like structures ranged, on the control medium, from 80% in 'Blue Parrot' and 'Prominence' to below 30% in 'Apeldoorn' and 'Mirjoran'. TDZ, applied at optimum for each cultivar concentration, greatly increased the regeneration potential up to 70-100%. Paclobutrazol, added to the TDZ-containing medium, significantly enhanced the response of explants, resulting in high numbers of leaf-like structures formed per explant (13.7-22.8. The structures developed gradually into characteristic forms: the growing up cotyledonary leaf, the probable root primordium formed at its base, the growing downwards stolon and the shoot meristem developed finely on its tip. It is suggested that such primary regeneration may have a nature of somatic embryogenesis. Then, the adventitious shoots developed and formed clusters, which were divided into 2-3 smaller ones every two months. The growth regulators, used at initial stage, markedly influenced subsequent shoot multiplication. Thus, the most intensive shoot formation was noted with TDZ at concentrations of 0.5-2 mg l-1 and paclobutrazol of 0.05-0.1 mg l-1.

  11. Resonant inelastic collisions of electrons with diatomic molecules

    International Nuclear Information System (INIS)

    Houfek, Karel

    2012-01-01

    In this contribution we give a review of applications of the nonlocal resonance theory which has been successfully used for treating the nuclear dynamics of low-energy electron collisions with diatomic molecules over several decades. We give examples and brief explanations of various structures observed in the cross sections of vibrational excitation and dissociative electron attachment to diatomic molecules such as threshold peaks, boomerang oscillations below the dissociative attachment threshold, or outer-well resonances.

  12. Resonant inelastic collisions of electrons with diatomic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Houfek, Karel, E-mail: karel.houfek@gmail.com [Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague 8 (Czech Republic)

    2012-05-15

    In this contribution we give a review of applications of the nonlocal resonance theory which has been successfully used for treating the nuclear dynamics of low-energy electron collisions with diatomic molecules over several decades. We give examples and brief explanations of various structures observed in the cross sections of vibrational excitation and dissociative electron attachment to diatomic molecules such as threshold peaks, boomerang oscillations below the dissociative attachment threshold, or outer-well resonances.

  13. Epibiotic Diatoms Are Universally Present on All Sea Turtle Species

    OpenAIRE

    Robinson, Nathan J.; Majewska, Roksana; Lazo-Wasem, Eric A.; Nel, Ronel; Paladino, Frank V.; Rojas, Lourdes; Zardus, John D.; Pinou, Theodora

    2016-01-01

    The macro-epibiotic communities of sea turtles have been subject to growing interest in recent years, yet their micro-epibiotic counterparts are almost entirely unknown. Here, we provide the first evidence that diatoms are epibionts for all seven extant species of sea turtle. Using Scanning Electron Microscopy, we inspected superficial carapace or skin samples from a single representative of each turtle species. We distinguished 18 diatom taxa from these seven individuals, with each sea turtl...

  14. Radiational and energetic characteristics of diatomic molecules (data base)

    International Nuclear Information System (INIS)

    Kuznetsova, L.A.; Pazyuk, E.A.; Stolyarov, A.V.

    1993-01-01

    Data base on radiational and energetic characteristics of diatomic molecules was created. The base consists of two parts: reference system and recommended data system. The reference system contains the information about studies of radiational and energetic parameters of more than 1500 electronic states and 1700 electron transfers for ∼ 350 diatomic molecules and their ions. The base bibliography includes ∼ 3000 publications. 11 refs., 1 figs

  15. THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).

    Science.gov (United States)

    Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene

    2011-12-01

    Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] macrophyte, nutrient-limited lakes (BiomEpiV macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance. © 2011 Phycological Society of America.

  16. Current trends to comprehend lipid metabolism in diatoms.

    Science.gov (United States)

    Zulu, Nodumo Nokulunga; Zienkiewicz, Krzysztof; Vollheyde, Katharina; Feussner, Ivo

    2018-04-01

    Diatoms are the most dominant phytoplankton species in oceans and they continue to receive a great deal of attention because of their significant contributions in ecosystems and the environment. Due to triacylglycerol (TAG) profiles that are abundant in medium-chain fatty acids, diatoms have emerged to be better feed stocks for biofuel production, in comparison to the commonly studied green microalgal species (chlorophytes). Importantly, diatoms are also known for their high levels of the essential ω3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and are considered to be a promising alternative source of these components. The two most commonly exploited diatoms include Thalassiosira pseudonana and Phaeodactylum tricornutum. Although obvious similarities between diatoms and chlorophytes exist, there are some substantial differences in their lipid metabolism. This review provides an overview on lipid metabolism in diatoms, with P. tricornutum as the most explored model. Special emphasis is placed on the synthesis and incorporation of very long chain ω3 fatty acids into lipids. Furthermore, current approaches including genetic engineering and biotechnological methods aimed at improving and maximizing lipid production in P. tricornutum are also discussed. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. Extraction and Hydrophobic Modification of Cotton Stalk Bark Fiber

    Directory of Open Access Journals (Sweden)

    Ya-Yu Li

    2016-01-01

    Full Text Available Cotton stalk bark fiber (CSBF was extracted at high temperature and under high pressure, under the condition of the alkali content of 11 wt%. Experimental results proved that the extraction yield of CSBF was 27.3 wt%, and the residual alkali concentration was 2.1 wt%. Then five kinds of modifiers including methyl methacrylate (MMA, MMA plus initiator, epoxy propane, copper ethanolamine, and silane coupling agent were chosen to modify the surface of CSBF. It was found by measuring water retention value (WRV that these five kinds of modifiers were all effective and the silane coupling agent was best modifier among all. The optimal modifying conditions of silane coupling agent were obtained: modifier concentration was 5%, the mixing temperature was 20°C, the mixing time was 1 h, and vacuum drying time was 1 h. Under the optimal condition, the WRV of the modified CSBF was 89%. It is expected that these modified CSBF may be a filler with strengthening effect in wood plastic composites (WPC fields.

  18. Gonadotrophic status in adolescents with pituitary stalk interruption syndrome.

    Science.gov (United States)

    Rottembourg, Diane; Linglart, Agnès; Adamsbaum, Catherine; Lahlou, Najiba; Teinturier, Cécile; Bougnères, Pierre; Carel, Jean-Claude

    2008-07-01

    Pituitary stalk interruption syndrome (PSIS) is a frequent cause of GH deficiency (GHD) and is commonly associated with other PH deficiencies (PHDs). Although previous reports have correlated multiple PHDs with severe anatomical lesions, the status of the gonadotrophic axis has not yet been thoroughly analysed. We retrospectively reviewed the medical records of 27 patients (15 males, 12 females) with GHD and PSIS defined by MRI findings. The status of the gonadotrophic axis was evaluated in children who were at least 14.5 years (boys) or 13 years (girls). Out of 27 patients, five displayed spontaneous full pubertal development with normal hormonal values at the final evaluation, whereas 22 of 27 patients (81%) had complete (n = 18) or partial pubertal deficiency. Three girls had primary amenorrhoea with normal gonadotrophin values, raising the possibility of subtle disturbances of gonadotrophin pulsatility. Of the 21 patients with TSH or ACTH deficiency, 17 (81%) had complete gonadotrophin deficiency. Two of our six patients with apparently isolated GHD during childhood had gonadotrophin deficiency. Cryptorchidism was present at birth in six boys (40%). Of these six boys, one had normal pubertal development. Ten of 11 boys with micropenis at birth had gonadotrophin deficiency. Gonadotrophin deficiency is a common finding in adolescents with PSIS and is frequently associated with other PHDs. However its severity is variable, ranging from complete gonadotrophin deficiency to normogonadotrophic amenorrhoea. The occurrence of gonadotrophin deficiency in 33% of children with apparently isolated GHD and PSIS has important implications for the counselling and follow-up of these patients.

  19. Light absorption of organic aerosol from pyrolysis of corn stalk

    Science.gov (United States)

    Li, Xinghua; Chen, Yanju; Bond, Tami C.

    2016-11-01

    Organic aerosol (OA) can absorb solar radiation in the low-visible and ultra-violet wavelengths thereby modifying radiative forcing. Agricultural waste burning emits a large quantity of organic carbon in many developing countries. In this work, we improved the extraction and analysis method developed by Chen and Bond, and extended the spectral range of OC absorption. We examined light absorbing properties of primary OA from pyrolysis of corn stalk, which is a major type of agricultural wastes. Light absorption of bulk liquid extracts of OA was measured using a UV-vis recording spectrophotometer. OA can be extracted by methanol at 95%, close to full extent, and shows polar character. Light absorption of organic aerosol has strong spectral dependence (Absorption Ångström exponent = 7.7) and is not negligible at ultra-violet and low-visible regions. Higher pyrolysis temperature produced OA with higher absorption. Imaginary refractive index of organic aerosol (kOA) is 0.041 at 400 nm wavelength and 0.005 at 550 nm wavelength, respectively.

  20. Cytotoxic Triterpenoids from the Stalks of Microtropis triflora.

    Science.gov (United States)

    Zhang, Xiao-Wei; Wang, Kui-Wu; Zhou, Man-Qing

    2017-07-01

    Bioassay-guided phytochemical investigation of the stalks of Microtropis triflora Merr. & F.L. Freeman led to the isolation of ten triterpenes 1 - 10, including one novel compound 3,24-epoxy-2α,24-dihydroxyfriedelan-29-oic acid (1). Their chemical structures were identified on the basis of spectroscopic analysis, including HR-ESI mass spectrometry, 1D- and 2D-NMR ( 1 H, 13 C, 1 H, 1 H-COSY, HSQC, HMBC, and NOESY), and by comparison with the data reported. The cytotoxicities of compounds 1 - 10 against a panel of cultured human tumor cell lines (Bcap37, SMMC7721, HeLa, CNE) were evaluated. The new compound 1 showed moderate anti-tumor activities with IC 50 values of 39.22, 29.24, 23.28, and 68.81 μm/ml, respectively. These results might be helpful for explaining the use of M. triflora in traditional medicine. Triterpenes are characteristic of Microtropis genus and could be useful as potential chemotaxonomic markers. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  1. Responses of diatom communities to hydrological processes during rainfall events

    Science.gov (United States)

    Wu, Naicheng; Faber, Claas; Ulrich, Uta; Fohrer, Nicola

    2015-04-01

    The importance of diatoms as a tracer of hydrological processes has been recently recognized (Pfister et al. 2009, Pfister et al. 2011, Tauro et al. 2013). However, diatom variations in a short-term scale (e.g., sub-daily) during rainfall events have not been well documented yet. In this study, rainfall event-based diatom samples were taken at the outlet of the Kielstau catchment (50 km2), a lowland catchment in northern Germany. A total of nine rainfall events were caught from May 2013 to April 2014. Non-metric multidimensional scaling (NMDS) revealed that diatom communities of different events were well separated along NMDS axis I and II, indicating a remarkable temporal variation. By correlating water level (a proxy of discharge) and different diatom indices, close relationships were found. For example, species richness, biovolume (μm3), Shannon diversity and moisture index01 (%, classified according to van Dam et al. 1994) were positively related with water level at the beginning phase of the rainfall (i.e. increasing limb of discharge peak). However, in contrast, during the recession limb of the discharge peak, diatom indices showed distinct responses to water level declines in different rainfall events. These preliminary results indicate that diatom indices are highly related to hydrological processes. The next steps will include finding out the possible mechanisms of the above phenomena, and exploring the contributions of abiotic variables (e.g., hydrologic indices, nutrients) to diatom community patterns. Based on this and ongoing studies (Wu et al. unpublished data), we will incorporate diatom data into End Member Mixing Analysis (EMMA) and select the tracer set that is best suited for separation of different runoff components in our study catchment. Keywords: Diatoms, Rainfall event, Non-metric multidimensional scaling, Hydrological process, Indices References: Pfister L, McDonnell JJ, Wrede S, Hlúbiková D, Matgen P, Fenicia F, Ector L, Hoffmann L

  2. Cyber stalking victimisation of women: Evaluating the effectiveness of current laws in India from restorative justice and therapeutic jurisprudential perspectives

    Directory of Open Access Journals (Sweden)

    Halder Debarati

    2015-01-01

    Full Text Available Victimisation of women through cyber stalking is one of the most serious crimes against women. Many countries including India have developed laws regulating cyber stalking. This article argues that since both, restorative justice (RJ and therapeutic jurisprudence (TJ are victim oriented, the issue of cyber stalking of women may be dealt with by RJ process and the laws in this regard must be analysed by the legal actors with a background in RJ and TJ philosophy. India had earlier taken up therapeutic punishment policy to enforce rights of the accused. But the modern principles of TJ have still not been considered in the RJ background in cyber stalking cases. This article therefore examines whether RJ and TJ principles can replace retributive principles for cyber stalking victimisation. It also examines the Indian cyber stalking law from RJ and TJ perspectives to assess its effectiveness for victims.

  3. [Stalking: clinical and criminological considerations through the results of a research contribution].

    Science.gov (United States)

    Pomilla, Antonella; D'Argenio, Alberto; Mastronardi, Vincenzo

    2012-01-01

    Among the extensive results supplied by the psychiatric literature on the subject of stalking, few studies focus on the analysis of persecutory behaviors carried out against mental health professionals, who also identified as one of the most affected sample of victims. Particularly, for studies conducted in this way, further examination requires differentiation according to gender type into the social and personal characteristics of the authors' behavior patterns displayed towards the victims. Aim. To obtaine results by an epidemiological survey conducted in public and private psychiatric care structures in the city of Rome, to assess the incidence of the phenomenon as well as gender differences in behavior patterns practised out by the author for the two sample considered. Methods. Administration of a questionnaire to a sample make up by psychiatrists working in out-patient services for the Departments of Mental Health (ASL) of Rome and to a sample of psychiatrists who practise their professional activity in the private sector. Results. Regarding the incidence of the phenomenon, an increased presence has been found in private mental health care settings in comparison to the public service; regarding to the distribution of the phenomenon according to the sexual identity of the authors among the two samples analyzed, a statistical prevalence of female authors has been found in the sample of private sector. Discussion. The health's professionals, so much liable of victimization, are poorly formed on the phenomenon. So it's urgent to operate with integrated approaches (informative trainings; strengthening of administrative and clinical policies of the profession; multidimensional assessment).

  4. DIATOMS (BACILLARIOPHYCEAE IN RIVERS AND STREAMS AND ON CULTIVATED SOILS OF THE PODKARPACIE REGION IN THE YEARS 2007–2011

    Directory of Open Access Journals (Sweden)

    Teresa Noga

    2014-01-01

    Full Text Available Diatoms Bacillariophyceae are a specialized, systematic group of algae, living in different types of ecosystems, and they are very good indicators of water quality. Recently, detailed studies have been carried out in the territory of the Podkarpacie Province on the diversity of diatoms in running waters. The area of study covers mostly the catchment of the biggest rivers of the province (mainly the River Wisłok and cultivated soils. Running waters in the Podkarpacie Province are characterized by a huge species richness of diatoms, 738 different taxa have been found so far. The highest number of taxa was noted in the Wisłok River (400, while the Żołynianka and Różanka streams and the Mleczka were also characterized by huge diversity (from 200 to over 350 taxa. In the majority of studied sites diatoms of alkaline (pH>7 and nutrient rich (eutrophic waters dominated: Navicula lanceolata, N. gregaria, N. capitatoradiata, Nitzschia palea, N. dissipata ssp. dissipata, Achnanthidium minutissimum var. minutissimum, A. pyrenaicum, Amphora pediculus, Diatoma vulgaris, Rhoicosphenia abbreviata, Planothidium lanceolatum, Cocconeis pediculus and C. placentula var. lineata. About 150 taxa were indentified on cultivated soils, among which the largest populations were formed by Hantzschia amphioxys, Mayamaea atomus, Nitzschia palea, N. pusilla, Pinnularia obscura and Stauroneis thermicola.

  5. Rotation harmonics for a numerical diatomic potential

    International Nuclear Information System (INIS)

    Kobeissi, H.; Korek, M.

    1983-01-01

    The problem of the determination of the rotation harmonics phi 1 , phi 2 , ... for the case of a numerical diatomic potential is considered. These harmonics defined in a recent work by psisub(vJ) = psisub(vO) + lambda 2 phi 2 + ... (where psisub(vJ) is the wave function of the vibration level v and the rotation level J, and lambda = J(J+1)) are studied for the case of the Dunham potential and for a numerical potential defined by the coordinates of its turning points with polynomial interpolations and extrapolations. It is proved that the analytical expressions of the harmonics phi 1 , phi 2 , ... reduce to polynomials where the coefficients are simply related to those of the potential in the case of the Dunham potential, and to the coordinates of the turning points in the case of the numerical potential. The numerical application is simple. The examples presented show that the vibration-rotation wave function psisub(vJ) calculated by using two harmonics only is ''exact'' up to eight significant figures

  6. Experimental co-digestion of corn stalk and vermicompost to improve biogas production

    International Nuclear Information System (INIS)

    Chen Guangyin; Zheng Zheng; Yang Shiguan; Fang Caixia; Zou Xingxing; Luo Yan

    2010-01-01

    Anaerobic co-digestion of corn stalk and vermicompost (VC) as well as mono-digestion of corn stalk were investigated. Batch mono-digestion experiments were performed at 35 ± 1 o C and initial total solid loading (TSL) ranged from 1.2% to 6.0%. Batch co-digestion experiments were performed at 35 ± 1 o C and initial TSL of 6% with VC proportions ranged from 20% to 80% of total solid (TS). For mono-digestion of corn stalk, a maximum methane yield of 217.60 ± 13.87 mL/g TS added was obtained at initial TSL of 4.8%, and acidification was found at initial TSL of 6.0% with the lowest pH value of 5.10 on day 4. Co-digestion improved the methane yields by 4.42-58.61% via enhancing volatile fatty acids (VFAs) concentration and pH value compared with mono-digestion of corn stalk. The maximum biogas yield of 410.30 ± 11.01 mL/g TS added and methane yield of 259.35 ± 13.85 mL/g TS added were obtained for 40% VC addition. Structure analysis by X-ray diffractometry (XRD) showed that the lowest crystallinity of 35.04 of digested corn stalk was obtained from co-digestion with 40% VC, which decreased 29.4% compared to 49.6 obtained from un-treated corn stalk. It is concluded that co-digestion with VC is beneficial for improving biodigestibility and methane yield from corn stalk.

  7. Perceptual advertisement by the prey of stalking or ambushing predators.

    Science.gov (United States)

    Broom, Mark; Ruxton, Graeme D

    2012-12-21

    There has been previous theoretical explorations of the stability of signals by prey that they have detected a stalking or ambush predator, where such perceptual advertisement dissuades the predator from attacking. Here we use a game theoretical model to extend the theory to consider some empirically-motivated complexities: (i) many perceptual advertisement signals appear to have the potential to vary in intensity, (ii) higher intensity signals are likely to be most costly to produce, and (iii) some high-cost signals (such as staring directly at the predator) can only be utilised if the prey is very confident of the existence of a nearby predator (that is, there are reserved or unfakable signals). We demonstrate that these complexities still allow for stable signalling. However, we do not find solutions where prey use a range of signal intensities to signal different degrees of confidence in the proximity of a predator; with prey simply adopting a binary response of not signalling or always signalling at the same fixed level. However this fixed level will not always be the cheapest possible signal, and we predict that prey that require more certainty about proximity of a predator will use higher-cost signals. The availability of reserved signals does not prohibit the stability of signalling based on lower-cost signals, but we also find circumstances where only the reserved signal is used. We discuss the potential to empirically test our model predictions, and to develop theory further to allow perceptual advertisement to be combined with other signalling functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current

    Science.gov (United States)

    Assmy, Philipp; Smetacek, Victor; Montresor, Marina; Klaas, Christine; Henjes, Joachim; Strass, Volker H.; Arrieta, Jesús M.; Bathmann, Ulrich; Berg, Gry M.; Breitbarth, Eike; Cisewski, Boris; Friedrichs, Lars; Fuchs, Nike; Herndl, Gerhard J.; Jansen, Sandra; Krägefsky, Sören; Latasa, Mikel; Peeken, Ilka; Röttgers, Rüdiger; Scharek, Renate; Schüller, Susanne E.; Steigenberger, Sebastian; Webb, Adrian; Wolf-Gladrow, Dieter

    2013-01-01

    Diatoms of the iron-replete continental margins and North Atlantic are key exporters of organic carbon. In contrast, diatoms of the iron-limited Antarctic Circumpolar Current sequester silicon, but comparatively little carbon, in the underlying deep ocean and sediments. Because the Southern Ocean is the major hub of oceanic nutrient distribution, selective silicon sequestration there limits diatom blooms elsewhere and consequently the biotic carbon sequestration potential of the entire ocean. We investigated this paradox in an in situ iron fertilization experiment by comparing accumulation and sinking of diatom populations inside and outside the iron-fertilized patch over 5 wk. A bloom comprising various thin- and thick-shelled diatom species developed inside the patch despite the presence of large grazer populations. After the third week, most of the thinner-shelled diatom species underwent mass mortality, formed large, mucous aggregates, and sank out en masse (carbon sinkers). In contrast, thicker-shelled species, in particular Fragilariopsis kerguelensis, persisted in the surface layers, sank mainly empty shells continuously, and reduced silicate concentrations to similar levels both inside and outside the patch (silica sinkers). These patterns imply that thick-shelled, hence grazer-protected, diatom species evolved in response to heavy copepod grazing pressure in the presence of an abundant silicate supply. The ecology of these silica-sinking species decouples silicon and carbon cycles in the iron-limited Southern Ocean, whereas carbon-sinking species, when stimulated by iron fertilization, export more carbon per silicon. Our results suggest that large-scale iron fertilization of the silicate-rich Southern Ocean will not change silicon sequestration but will add carbon to the sinking silica flux. PMID:24248337

  9. Mass transfer effect of the stalk contraction-relaxation cycle of Vorticella convallaria

    Science.gov (United States)

    Zhou, Jiazhong; Admiraal, David; Ryu, Sangjin

    2014-11-01

    Vorticella convallaria is a genus of protozoa living in freshwater. Its stalk contracts and coil pulling the cell body towards the substrate at a remarkable speed, and then relaxes to its extended state much more slowly than the contraction. However, the reason for Vorticella's stalk contraction is still unknown. It is presumed that water flow induced by the stalk contraction-relaxation cycle may augment mass transfer near the substrate. We investigated this hypothesis using an experimental model with particle tracking velocimetry and a computational fluid dynamics model. In both approaches, Vorticella was modeled as a solid sphere translating perpendicular to a solid surface in water. After having been validated by the experimental model and verified by grid convergence index test, the computational model simulated water flow during the cycle based on the measured time course of stalk length changes of Vorticella. Based on the simulated flow field, we calculated trajectories of particles near the model Vorticella, and then evaluated the mass transfer effect of Vorticella's stalk contraction based on the particles' motion. We acknowlege support from Laymann Seed Grant of the University of Nebraska-Lincoln.

  10. Cultural Models Shaping Stalking From a Content Analysis of Italian Newspapers

    Directory of Open Access Journals (Sweden)

    Andrea Caputo

    2013-08-01

    Full Text Available The increasing spread of stalking in recent years has captured the community’s and media’s interest and highlighted complex legal, clinical and cultural issues. This phenomenon, far from being an individual problem, can be considered as a product of a growing culture that seems to reveal the crisis of current rules of social coexistence. This work aims at detecting the cultural repertoires that organise the stalking discourse, from an analysis of Italian newspaper articles, within a socio-constructivist paradigm. Emotional text analysis was conducted on a corpus of headlines and subheadings derived from 496 articles. These articles were published in major national newspapers and helped to identify four cultural repertoires (clusters that characterise the social representation of stalking: gender violence and women’s social independence (Cluster 1, psychological violence and control as illusion of intimacy (Cluster 2, anomic violence and intolerant individualism (Cluster 3, domestic violence and women’s marital obligation (Cluster 4. These repertoires are conceived along three latent dimensions which respectively refer to the cultural functions of stalking (Factor 1, representations of the victim (Factor 2, and gender inequalities (Factor 3. The paper offers a key to a social contextualisation of stalking in Italy, in order to re-think work practices within institutional agencies that deal with this phenomenon.

  11. Chromium sorption and Cr(VI) reduction to Cr(III) by grape stalks and yohimbe bark.

    Science.gov (United States)

    Fiol, Núria; Escudero, Carlos; Villaescusa, Isabel

    2008-07-01

    In this work, two low cost sorbents, grape stalks and yohimbe bark wastes were used to remove Cr(VI) and Cr(III) from aqueous solutions. Batch experiments were designed to obtain Cr(VI) and Cr(III) sorption data. The mechanism of Cr(III) and Cr(VI) removal and Cr(VI) reduction to Cr(III) by the two vegetable wastes, has been investigated. Fourier transform infrared rays (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis on solid phase were performed to determine the main functional groups that might be involved in metal uptake and to confirm the presence of Cr(III) on the sorbent, respectively. Results put into evidence that both sorbents are able to reduce Cr(VI) to its trivalent form.

  12. Mechanisms of carbon dioxide acquisition and CO2 sensing in marine diatoms: a gateway to carbon metabolism.

    Science.gov (United States)

    Matsuda, Yusuke; Hopkinson, Brian M; Nakajima, Kensuke; Dupont, Christopher L; Tsuji, Yoshinori

    2017-09-05

    Diatoms are one of the most successful marine eukaryotic algal groups, responsible for up to 20% of the annual global CO 2 fixation. The evolution of a CO 2 -concentrating mechanism (CCM) allowed diatoms to overcome a number of serious constraints on photosynthesis in the marine environment, particularly low [CO 2 ] aq in seawater relative to concentrations required by the CO 2 fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), which is partly due to the slow diffusion rate of CO 2 in water and a limited CO 2 formation rate from [Formula: see text] in seawater. Diatoms use two alternative strategies to take up dissolved inorganic carbon (DIC) from the environment: one primarily relies on the direct uptake of [Formula: see text] through plasma-membrane type solute carrier (SLC) 4 family [Formula: see text] transporters and the other is more reliant on passive diffusion of CO 2 formed by an external carbonic anhydrase (CA). Bicarbonate taken up into the cytoplasm is most likely then actively transported into the chloroplast stroma by SLC4-type transporters on the chloroplast membrane system. Bicarbonate in the stroma is converted into CO 2 only in close proximity to RubisCO preventing unnecessary CO 2 leakage. CAs play significant roles in mobilizing DIC as it is progressively moved towards the site of fixation. However, the evolutionary types and subcellular locations of CAs are not conserved between different diatoms, strongly suggesting that this DIC mobilization strategy likely evolved multiple times with different origins. By contrast, the recent discovery of the thylakoid luminal θ-CA indicates that the strategy to supply CO 2 to RubisCO in the pyrenoid may be very similar to that of green algae, and strongly suggests convergent coevolution in CCM function of the thylakoid lumen not only among diatoms but among eukaryotic algae in general. In this review, both experimental and corresponding theoretical models of the diatom CCMs are

  13. Semiclassical series solution of the generalized phase shift atom--diatom scattering equations

    International Nuclear Information System (INIS)

    Squire, K.R.; Curtiss, C.F.

    1980-01-01

    A semiclassical series solution of the previously developed operator form of the generalized phase shift equations describing atom--diatom scattering is presented. This development is based on earlier work which led to a double series in powers of Planck's constant and a scaling parameter of the anisotropic portion of the intermolecular potential. The present solution is similar in that it is a double power series in Planck's constant and in the difference between the spherical radial momentum and a first order approximation. The present series solution avoids difficulties of the previous series associated with the classical turning point

  14. The special neuraminidase stalk-motif responsible for increased virulence and pathogenesis of H5N1 influenza A virus.

    Directory of Open Access Journals (Sweden)

    Hongbo Zhou

    Full Text Available The variation of highly pathogenic avian influenza H5N1 virus results in gradually increased virulence in poultry, and human cases continue to accumulate. The neuraminidase (NA stalk region of influenza virus varies considerably and may associate with its virulence. The NA stalk region of all N1 subtype influenza A viruses can be divided into six different stalk-motifs, H5N1/2004-like (NA-wt, WSN-like, H5N1/97-like, PR/8-like, H7N1/99-like and H5N1/96-like. The NA-wt is a special NA stalk-motif which was first observed in H5N1 influenza virus in 2000, with a 20-amino acid deletion in the 49(th to 68(th positions of the stalk region. Here we show that there is a gradual increase of the special NA stalk-motif in H5N1 isolates from 2000 to 2007, and notably, the special stalk-motif is observed in all 173 H5N1 human isolates from 2004 to 2007. The recombinant H5N1 virus with the special stalk-motif possesses the highest virulence and pathogenicity in chicken and mice, while the recombinant viruses with the other stalk-motifs display attenuated phenotype. This indicates that the special stalk-motif has contributed to the high virulence and pathogenicity of H5N1 isolates since 2000. The gradually increasing emergence of the special NA stalk-motif in H5N1 isolates, especially in human isolates, deserves attention by all.

  15. Species interactions within a fouling diatom community: Roles of nutrients, initial inoculum and competitive strategies

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Anil, A

    Diatoms constitute an important component of the fouling community. Although a lot of work has dealt with the fouling diatom community structure, work on the species interactions within the community is still meager. In this regard, a study...

  16. Genotoxicity of cadmium in marine diatom Chaetoceros tenuissimus using the alkaline Comet assay

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, S.R.; Verlecar, X.N.; Nagarajappa; Goswami, U.

    of Cd increased growth of the diatom decreased. Alkaline single-cell gel electrophoresis (Comet assay) method, which is highly sensitive in detection of DNA damage in eukaryotic cells, was used to observe genomic changes in marine diatom cells. DNA...

  17. Diatom community dynamics in a tropical, monsoon-influenced environment: West coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    DeCosta, P.M.; Anil, A.C.

    Diatom communities are influenced by environmental perturbations, such as the monsoon system that impact the niche opportunities of species. To discern the influence of the monsoon system on diatom community structure, we sampled during two...

  18. Growth inhibition of periphytic diatoms by methanol extracts of sponges and holothurians

    Digital Repository Service at National Institute of Oceanography (India)

    Mokashe, S.S.; Garg, A; Anil, A; Wagh, A

    Crude methanol extracts of a holothurian Holothuria leucospilota, and two sponges Craniella sp. and Ircinia ramosa were tested for their inhibitory effects on the growth of two marine diatoms, Navicula subinflata and N. crucicula, by diatom plating...

  19. The application and testing of diatom-based indices of stream water ...

    African Journals Online (AJOL)

    The application and testing of diatom-based indices of stream water quality in Chinhoyi Town, Zimbabwe. ... PROMOTING ACCESS TO AFRICAN RESEARCH ... test the applicability of foreign diatom-based water quality assessment indices to ...

  20. Epipsammic diatoms in streams influenced by urban pollution, São Carlos, SP, Brazil

    Directory of Open Access Journals (Sweden)

    T. Bere

    Full Text Available Epipsammic diatoms have important implications for ecosystem processes in lotic environments. Most of the studies on benthic diatoms concentrate on epilithic diatoms and very little is known about epipsammic diatoms. The objective of this study was to assess epipsammic diatom communities in streams in relation to environmental conditions. Epipsammic diatoms and water quality sampling was done at 7 sites during summer base flow period (2008. Forward stepwise multiple regression and canonical correspondence analysis (CCA were used to determine environmental gradients along which species vary with physical and chemical variables. A total of 112 diatom species distributed among 44 genera were recorded. Altitude and the process of eutrophication played a significant role in structuring diatom communities in the study region.

  1. Using biodiversity of diatoms to identify hydrological connectivity in the hillslope-riparian zone-stream system

    Science.gov (United States)

    Wetzel, C. E.; Martínez-Carreras, N.; Ector, L.; Hlubikova, D.; Frentress, J.; McDonnell, J. J.; Hoffmann, L.; Pfister, L.

    2012-04-01

    very intense rainfall events cause a single-tailed rather small rise of the hydrograph in the Weierbach. Mixing diagrams suggest a very brief and intense switch from groundwater to soil water contribution. Almost simultaneously to incoming precipitation, terrestrial diatom abundance increases to 20-30% inside the stream. Species composition was also seasonally structured. During winter season (November 2010 and January 2011 events) the diatom drift was characterized and dominated by colony forming species (e.g. Fragilaria nevadensis Linares-Cuesta & Sánchez-Castillo and Fragilariforma virescens (Ralfs) Williams & Round), while summer events were characterized by a large number of small aerophytic species (i.e. Chamaepinnularia evanida (Hustedt) Lange-Bertalot, Eolimna tantula (Hustedt) Lange-Bertalot, Navicula obsoleta Hustedt, Navicula parsura Hustedt and Stauroneis thermicola (Petersen) Lund). Chemical tracers suggest a substantial role of soil water contributions to storm hydrographs in the Weierbach, regardless of the season, with overland flow playing no prominent role at all. Meanwhile, terrestrial diatom abundance in drift samples strongly increases during precipitation events, suggesting a rapid onset of connectivity between the soil surface and the stream. We assume the terrestrial diatoms to be mobilized during precipitation and eventually flushed to the stream through a subsurface network of macropores in the shallow soils and cracks in the fractured and weathered schistose bedrock.

  2. Magnetic resonance imaging of thickened pituitary stalk proceeding to langerhans cell histiocytosis in a child

    International Nuclear Information System (INIS)

    Halefoglu, A.M.

    2006-01-01

    Magnetic resonance imaging has shown isolated pituitary stalk thickening in certain cases of idiopathic or secondary central diabetes insipidus (Dl) due to infiltrative processes. We present a 4-year-old boy who was initially diagnosed as having central Dl. The MRI showed isolated pituitary stalk thickening with prominent homogeneous contrast enhancement. The remaining findings on MRI were within normal limits. The patient's personal and family history and laboratory and clinical findings were unremarkable; therefore, he was initially diagnosed as having idiopathic Dl. Since central Dl and isolated pituitary stalk thickening may be considered to be the first manifestations of Langerhans cell histiocytosis, we decided to follow up the patient. After 5 months, following the initial diagnosis, on skeletal X-ray survey, the patient did indeed develop multiple lytic skull lesions which, on biopsy, were histologically typical bone lesions of Langerhans cell histiocytosis. Copyright (2006) Blackwell Science Pty Ltd

  3. The complete mitochondrial genome of the Antarctic stalked jellyfish, Haliclystus antarcticus Pfeffer, 1889 (Staurozoa: Stauromedusae

    Directory of Open Access Journals (Sweden)

    Hsing-Hui Li

    2016-06-01

    Full Text Available In present study, the complete mitogenome sequence of the Antarctic stalked jellyfish, Haliclystus antarcticus Pfeffer (Staurozoa: Stauromedusae has been sequenced by next-generation sequencing method. The assembled mitogenome comprises of 15,766 bp including 13 protein coding genes, 7 transfer RNAs, and 2 ribosomal RNA genes. The overall base of Antarctic stalked jellyfish constitutes of 26.5% for A, 19.6% for C, 19.8% for G, 34.1% for T and show 90% identity to Sessile Jelly, Haliclystus sanjuanensis, in the northeastern Pacific Ocean. The complete mitogenome of the Antarctic stalked jellyfish, contributes fundamental and significant DNA molecular data for further phylogeography and evolutionary analysis for seahorse phylogeny. The complete sequence was deposited in DBBJ/EMBL/GenBank under accession number KU947038.

  4. Computation of diatomic molecular spectra for selected transitions of aluminum monoxide, cyanide, diatomic carbon, and titanium monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Parigger, Christian G., E-mail: cparigge@tennessee.edu [The University of Tennessee/University of Tennessee Space Institute, Center for Laser Applications, 411 B.H. Goethert Parkway, Tullahoma, TN 37388-9700 (United States); Woods, Alexander C.; Surmick, David M.; Gautam, Ghaneshwar; Witte, Michael J. [The University of Tennessee/University of Tennessee Space Institute, Center for Laser Applications, 411 B.H. Goethert Parkway, Tullahoma, TN 37388-9700 (United States); Hornkohl, James O. [Hornkohl Consulting, Tullahoma, TN 37388 (United States)

    2015-05-01

    Laser ablation studies with laser-induced breakdown spectroscopy (LIBS) typically emphasize atomic species yet fingerprints from molecular species can occur subsequently or concurrently. In this work, selected molecular transitions of aluminum monixide (AlO), diatomic carbon (C{sub 2}), cyanide (CN), and titanium monoxide (TiO) are accurately computed. Line strength tables are used to describe the radiative transitions of diatomic molecules primarily in the visible, optical region. Details are elaborated of the computational procedure that allows one to utilize diatomic spectra as a predictive and as a diagnostic tool. In order to create a computed spectrum, the procedure requires information regarding the temperature of the diatomic transitions along with other input such as the spectral resolution. When combined with a fitting algorithm to optimize such parameters, this procedure is used to infer information from an experimentally obtained spectrum. Furthermore, the programs and data files are provided for LIBS investigations that also reveal AlO, C{sub 2}, CN, and TiO diatomic spectra. - Highlights: • We present a program for fitting of molecular spectra. • This includes data base for AlO, C{sub 2}, CN, and TiO. • We discuss the details of the program including fitting. • We show computed examples and reference current work.

  5. Third version of a program for calculating the static interaction potential between an electron and a diatomic molecule

    International Nuclear Information System (INIS)

    Raseev, G.

    1980-01-01

    This program calculates the one-centre expansion of a two-centre wave function of a diatomic molecule and also the multipole expansion of its static interaction with a point charge. It is an extension to some classes of open-shell targets of the previous versions and it provides both the wave function and the potential in a form suitable for use in an electron-molecule scattering program. (orig./HSI)

  6. A new cell primo-culture method for freshwater benthic diatom communities

    OpenAIRE

    Debenest, Timothée; Silvestre, Jérôme; Coste, Michel; Delmas, François; Pinelli, Eric

    2009-01-01

    A new cell primo-culture method was developed for the benthic diatom community isolated from biofilm sampled in rivers. The approach comprised three steps: (1) scraping biofilm from river pebbles, (2) diatom isolation from biofilm, and (3) diatom community culture. With a view to designing a method able to stimulate the growth of diatoms, to limit the development of other microorganisms, and to maintain in culture a community similar to the original natural one, different factors were test...

  7. Short-term Lost Productivity per Victim: Intimate Partner Violence, Sexual Violence, or Stalking.

    Science.gov (United States)

    Peterson, Cora; Liu, Yang; Kresnow, Marcie-Jo; Florence, Curtis; Merrick, Melissa T; DeGue, Sarah; Lokey, Colby N

    2018-05-15

    The purpose of this study is to estimate victims' lifetime short-term lost productivity because of intimate partner violence, sexual violence, or stalking. U.S. nationally representative data from the 2012 National Intimate Partner and Sexual Violence Survey were used to estimate a regression-adjusted average per victim (female and male) and total population number of cumulative short-term lost work and school days (or lost productivity) because of victimizations over victims' lifetimes. Victims' lost productivity was valued using a U.S. daily production estimate. Analysis was conducted in 2017. Non-institutionalized adults with some lifetime exposure to intimate partner violence, sexual violence, or stalking (n=6,718 respondents; survey-weighted n=130,795,789) reported nearly 741 million lost productive days because of victimizations by an average of 2.5 perpetrators per victim. The adjusted per victim average was 4.9 (95% CI=3.9, 5.9) days, controlling for victim, perpetrator, and violence type factors. The estimated societal cost of this short-term lost productivity was $730 per victim, or $110 billion across the lifetimes of all victims (2016 USD). Factors associated with victims having a higher number of lost days included a higher number of perpetrators and being female, as well as sexual violence, physical violence, or stalking victimization by an intimate partner perpetrator, stalking victimization by an acquaintance perpetrator, and sexual violence or stalking victimization by a family member perpetrator. Short-term lost productivity represents a minimum economic valuation of the immediate negative effects of intimate partner violence, sexual violence, and stalking. Victims' lost productivity affects family members, colleagues, and employers. Published by Elsevier Inc.

  8. Cenozoic planktonic marine diatom diversity and correlation to climate change

    Science.gov (United States)

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂18O (climate) and carbon cycle records (∂13C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p2 were only moderately higher than today. Diversity is strongly correlated to both ∂13C and pCO2 over the last 15 my (for both: r>.9, detrended r>.6, all p<.001), but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  9. Cenozoic planktonic marine diatom diversity and correlation to climate change.

    Directory of Open Access Journals (Sweden)

    David Lazarus

    Full Text Available Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂(18O (climate and carbon cycle records (∂(13C, and 20-0 Ma pCO2. Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p.9, detrended r>.6, all p<.001, but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  10. Ecological and physiological aspects of aestivation-diapause in the larvae of two Pyralid stalk borers of maize in Kenya

    NARCIS (Netherlands)

    Scheltes, P.

    1978-01-01

    Stalk borers are highly destructive to a large number of important graminaceous crops all over the world. Some examples of economically important stalk borers and a general description of their life-cycle are mentioned in chapter 1. In the same chapter difficulties in controlling the insects are

  11. Body stalk anomaly in Denmark during 20 years (1970-1989)

    DEFF Research Database (Denmark)

    Bugge, Merete

    2012-01-01

    Body stalk anomaly is a severe defect of the abdominal wall with uncovered thoracic and/or abdominal organs. The umbilical cord is absent or very short. Here I present epidemiological and clinical data on 16 infants with body stalk anomaly. The 16 infants represent 3.4% of the 469 infants...... ascertained in an almost complete nationwide data set of live- and stillborn infants born with abdominal wall defects during the two decades 1970-1989 in Denmark. The prevalence was 0.12 per 10,000 live- and stillborn. Nine of the infants were stillbirths, seven were live births, and they all died shortly...

  12. Diatom Assemblage in the Lake of Gaber Oun, Southern Libya

    Directory of Open Access Journals (Sweden)

    Abdelkader Elzen

    2012-07-01

    Full Text Available The lake of Gaber Oun in the southern district of Libya was studied to assess the diatom community composition in the littoral zone. Planktic and attached diatoms were listed and information on the constituent species made known (images are shown. Some criteria of the water characteristics are also given such as the pH, which is an average of 8.3, electrical conductivity which accounted for 1.4 µSim/cm1- and total dissolved salts (TDS of 189.0 mg/L1-.

  13. Biological monitoring of lotic ecosystems: the role of diatoms

    Directory of Open Access Journals (Sweden)

    T. Bere

    Full Text Available Increasing anthropogenic influence on lotic environments as a result of civilisation has captured public interest because of the consequent problems associated with deterioration of water quality. Various biological monitoring methods that provide a direct measure of ecological integrity by using the response of biota to environmental changes have been developed to monitor the ecological status of lotic environments. Diatoms have been used extensively in this regard and this review attempts to summarise the basic concepts associated with biological monitoring using benthic diatoms. Where possible, examples from work carried out in Brazil are used.

  14. Biological monitoring of lotic ecosystems: the role of diatoms.

    Science.gov (United States)

    Bere, T; Tundisi, J G

    2010-08-01

    Increasing anthropogenic influence on lotic environments as a result of civilisation has captured public interest because of the consequent problems associated with deterioration of water quality. Various biological monitoring methods that provide a direct measure of ecological integrity by using the response of biota to environmental changes have been developed to monitor the ecological status of lotic environments. Diatoms have been used extensively in this regard and this review attempts to summarise the basic concepts associated with biological monitoring using benthic diatoms. Where possible, examples from work carried out in Brazil are used.

  15. The UV filtering potential of drop-casted layers of frustules of three diatom species

    DEFF Research Database (Denmark)

    Su, Yanyan; Lenau, Torben Anker; Gundersen, Emil

    2018-01-01

    Diatoms are in focus as biological materials for a range of photonic applications. Many of theseapplications would require embedding a multitude of diatoms in a matrix (e.g. paint, crème or lacquer); however, most studies on the photonic and spectral properties of diatoms frustules (silica walls)...

  16. Fluxes of diatoms in the Dona Paula Bay, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Garg, A.; Bhaskar, P.V.

    of POC and diatom carbon was 251 and 0.39 mg C m sup(-2) day sup(-1), respectively. The diatom carbon accounted for 0.15% of the POC flux. Mass flux of diatoms showed significant negative correlation with the concentration of nitrate and phosphate...

  17. Diatomic-molecule vibrational potentials. II. New representationsa)

    International Nuclear Information System (INIS)

    Engelke, R.

    1979-01-01

    Two new representations of diatomic-molecule vibrational potentials are presented. One of these includes most of the previously employed series approximations as special cases. The new representations are tested against older ones by using Peek's ''exact'' numerical Born--Oppenheimer potentials for the 1ssigma/sub g/, 2pπ/sub u/, and 3dsigma/sub g/ states of H 2 + as test problems. Accuracy comparisons are made with Dunham, Thakkar, Ogilvie--Tipping, Coulomb-subtracted Ogilvie--Tipping, and Pade representations. A central idea of the new treatment is that it is not necessary to use a global representation of the potential over the region 0 or =1 and then match them smoothly to each other and to the Dunham expansion at R/R/sub e/=1. Attention is focused on finding improved approximations for R/R/sub e/>1, since this region exerts strong control on the vibrational eigenvalue spectrum and it is here, perhaps, where the older techniques are at their weakest. Known properties of the exact potential such as the R→infinity behavior and the dissociation energy can be built into the new forms a priori. If the dissociation energy is not known, the new methods allow it to be estimated with better accuracy then could be done previously. If one knows only Dunham coefficients, the Coulomb-subtracted Ogilvie--Tipping series is the superior representation. If one knows, in addition, the dissociation energy, the new representations are superior and give more accurate results on the interval R/R/sub e/> or =1

  18. Diatom-induced silicon isotopic fractionation in Antarctic sea ice

    Science.gov (United States)

    Francois, F.; Damien, C.; Jean-Louis, T.; Anthony, W.; Luc, A.

    2006-12-01

    We measured silicon-isotopic composition of dissolved silicon and biogenic silica collected by sequential melting from spring 2003 Antarctic pack ice (Australian sector). Sea ice is a key ecosystem in the Southern Ocean and its melting in spring has been often thought to have a seeding effect for the surface waters, triggering blooms in the mixed layer. This work is the first investigation of the silicon isotopes' proxy in sea ice and allows to estimate the activity of sea-ice diatoms in the different brine structures and the influence of sea- ice diatoms on the spring ice edge blooms. The relative use of the dissolved silicon pool by sea-ice diatoms is usually assessed by calculating nutrient:salinity ratios in the brines. However such an approach is biased by difficulties in evaluating the initial nutrient concentrations in the different brines structures, and by the impossibility to account for late sporadic nutrient replenishments. The silicon-isotopic composition of biogenic silica is a convenient alternative since it integrates an average Si utilization on all generations of diatoms. Measurements were performed on a MC-ICP-MS, in dry plasma mode using external Mg doping. Results are expressed as delta29Si relative to the NBS28 standard. From three sea ice cores with contrasted physico-chemical characteristics, we report significant isotopic fractionations linked to the diatoms activity, with distinct silicon biogeochemical dynamics between different brine structure. The diatoms in snow ice and in brine pockets of frazil or congelation ice have the most positive silicon-isotopic composition (+0.53 to +0.86 p.mil), indicating that they grow in a closed system and use a significant part of the small dissolved silicon pool. In the brine channels and skeletal layer, diatoms display a relatively less positive Si-isotopic composition (+0.41 to +0.70 p.mil), although it is still heavier compared to equilibrium fractionation (+0.38 p.mil). This suggests that they have

  19. Preparation of nitrogen-doped cotton stalk microporous activated carbon fiber electrodes with different surface area from hexamethylenetetramine-modified cotton stalk for electrochemical degradation of methylene blue

    Directory of Open Access Journals (Sweden)

    Kunquan Li

    Full Text Available Cotton-stalk activated carbon fibers (CSCFs with controllable micropore area and nitrogen content were prepared as an efficient electrode from hexamethylenetetramine-modified cotton stalk by steam/ammonia activation. The influence of microporous area, nitrogen content, voltage and initial concentration on the electrical degradation efficiency of methylene blue (MB was evaluated by using CSCFs as anode. Results showed that the CSCF electrodes exhibited excellent MB electrochemical degradation ability including decolorization and COD removal. Increasing micropore surface area and nitrogen content of CSCF anode leaded to a corresponding increase in MB removal. The prepared CSCF-800-15-N, which has highest N content but lowest microporous area, attained the best degradation effect with 97% MB decolorization ratio for 5 mg/L MB at 12 V in 4 h, implying the doped nitrogen played a prominent role in improving the electrochemical degradation ability. The electrical degradation reaction was well described by first-order kinetics model. Overall, the aforesaid findings suggested that the nitrogen-doped CSCFs were potential electrode materials, and their electrical degradation abilities could be effectively enhanced by controlling the nitrogen content and micropore surface area. Keywords: Cotton stalk, Nitrogen content, Electrode, Surface area, Methylene blue

  20. Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms1

    Science.gov (United States)

    Graff van Creveld, Shiri; Rosenwasser, Shilo; Vardi, Assaf

    2016-01-01

    Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered “ocean deserts” due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom’s response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment. PMID:27503604

  1. Suggestions for diatom-based monitoring in intermittent streams

    Directory of Open Access Journals (Sweden)

    Falasco Elisa

    2016-01-01

    Full Text Available Over the last decades, river lentification processes and droughts have been dramatically spreading worldwide, due to global and local drastic changes due to human activities. Under this scenario, the evaluation of physical disturbance caused by intermittency and droughts has become more and more relevant. In this research, we compare samples collected in Mediterranean streams following both traditional and experimental approaches with the aim of understanding if diatom indices calculated from a new sampling strategy could provide additional information for the physical disturbance assessment. Moreover, we also evaluated the response of functional metrics. Our results demonstrated that even though an enhanced sampling method better reflects hydrological disturbance than the traditional one, diatom indices do not detect it. Conversely, functional traits proved to be important metrics for the hydrological disturbance assessment. In particular, benthic diatom chlorophyll a showed significantly lower values in sections more subject to droughts. With respect to ecological guilds, the motile taxa proved to be linked to depositional areas, which resulted important microhabitats (MHs to be explored in rivers affected by lentification. Including different MHs in the sampling process improves the information we can obtain from the analysis of the diatom community and presents important implications in documenting species distribution and autecology.

  2. Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus

    KAUST Repository

    Mock, Thomas; Otillar, Robert P.; Strauss, Jan; McMullan, Mark; Paajanen, Pirita; Schmutz, Jeremy; Salamov, Asaf; Sanges, Remo; Toseland, Andrew; Ward, Ben J.; Allen, Andrew E.; Dupont, Christopher L.; Frickenhaus, Stephan; Maumus, Florian; Veluchamy, Alaguraj; Wu, Taoyang; Barry, Kerrie W.; Falciatore, Angela; Ferrante, Maria I.; Fortunato, Antonio E.; Glö ckner, Gernot; Gruber, Ansgar; Hipkin, Rachel; Janech, Michael G.; Kroth, Peter G.; Leese, Florian; Lindquist, Erika A.; Lyon, Barbara R.; Martin, Joel; Mayer, Christoph; Parker, Micaela; Quesneville, Hadi; Raymond, James A.; Uhlig, Christiane; Valas, Ruben E.; Valentin, Klaus U.; Worden, Alexandra Z.; Armbrust, E. Virginia; Clark, Matthew D.; Bowler, Chris; Green, Beverley R.; Moulton, Vincent; Oosterhout, Cock van; Grigoriev, Igor V.

    2017-01-01

    The Southern Ocean houses a diverse and productive community of organisms. Unicellular eukaryotic diatoms are the main primary producers in this environment, where photosynthesis is limited by low concentrations of dissolved iron and large seasonal fluctuations in light, temperature and the extent of sea ice. How diatoms have adapted to this extreme environment is largely unknown. Here we present insights into the genome evolution of a cold-adapted diatom from the Southern Ocean, Fragilariopsis cylindrus, based on a comparison with temperate diatoms. We find that approximately 24.7 per cent of the diploid F. cylindrus genome consists of genetic loci with alleles that are highly divergent (15.1 megabases of the total genome size of 61.1 megabases). These divergent alleles were differentially expressed across environmental conditions, including darkness, low iron, freezing, elevated temperature and increased CO2. Alleles with the largest ratio of non-synonymous to synonymous nucleotide substitutions also show the most pronounced condition-dependent expression, suggesting a correlation between diversifying selection and allelic differentiation. Divergent alleles may be involved in adaptation to environmental fluctuations in the Southern Ocean.

  3. Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus

    KAUST Repository

    Mock, Thomas

    2017-01-17

    The Southern Ocean houses a diverse and productive community of organisms. Unicellular eukaryotic diatoms are the main primary producers in this environment, where photosynthesis is limited by low concentrations of dissolved iron and large seasonal fluctuations in light, temperature and the extent of sea ice. How diatoms have adapted to this extreme environment is largely unknown. Here we present insights into the genome evolution of a cold-adapted diatom from the Southern Ocean, Fragilariopsis cylindrus, based on a comparison with temperate diatoms. We find that approximately 24.7 per cent of the diploid F. cylindrus genome consists of genetic loci with alleles that are highly divergent (15.1 megabases of the total genome size of 61.1 megabases). These divergent alleles were differentially expressed across environmental conditions, including darkness, low iron, freezing, elevated temperature and increased CO2. Alleles with the largest ratio of non-synonymous to synonymous nucleotide substitutions also show the most pronounced condition-dependent expression, suggesting a correlation between diversifying selection and allelic differentiation. Divergent alleles may be involved in adaptation to environmental fluctuations in the Southern Ocean.

  4. Functionalized diatom silica microparticles for removal of mercury ions

    International Nuclear Information System (INIS)

    Yu Yang; Addai-Mensah, Jonas; Losic, Dusan

    2012-01-01

    Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH 2 ) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g -1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.

  5. Effect of Industrial Effluent on the Growth of Marine Diatom ...

    African Journals Online (AJOL)

    The marine centric diatom,Chaetoceros simplex (Ostenfeld, 1901) was exposed to five different concentrations of industrial effluent for 96 hrs to investigate the effect on growth. The physico-chemical parameters viz. colour, odour, temperature, salinity, dissolved oxygen, turbidity, pH, alkalinity, hardness, ammonia, nitrite, ...

  6. Copepod reproduction is unaffected by diatom aldehydes or lipid composition

    DEFF Research Database (Denmark)

    Dutz, Jörg; Koski, Marja; Jonasdottir, Sigrun

    2008-01-01

    We investigated whether reduced reproductive success of copepods fed with diatoms was related to nutritional imbalances with regard to essential lipids or to the production of inhibitory aldehydes. In 10-d laboratory experiments, feeding, egg production, egg hatching success, and fecal pellet...

  7. Colonisation and community structure of benthic diatoms on artificial ...

    African Journals Online (AJOL)

    This was undertaken using tiles as artificial substrates so that we could study how the communities developed after the flood disturbance. The diatom community structure was assessed over a 28-day period following a flood event in October 2012. The Mann Whitney test indicated that there was a statistically significant ...

  8. Diatom distribution in the surficial sediments of Lake Fuxian, Yunnan ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-30

    Nov 30, 2011 ... (18.2%); there were some phosphorus post-mines which led to higher total phosphorus concentration than that in southern part. The most outstanding characteristic of diatom ... (212 km2 in surface area) is located in the central Yunnan. Province; it is a oligotrophic freshwater lake. It is the second deepest ...

  9. Mercury-induced genotoxicity in marine diatom (Chaetoceros tenuissimus)

    Digital Repository Service at National Institute of Oceanography (India)

    Sarker, S.; Desai, S.R.; Verlecar, X.N.; Sarker, M.S.; Sarkar, A.

    In this paper, we present an evaluation of genotoxic responses in marine diatom, Chaetoceros tenuissimus, isolated from Kandla Creek (lat 23.03° N, long 70.22° E), Gujarat, India, in terms of impairment of DNA integrity as a function...

  10. Temperature affects the silicate morphology in a diatom

    NARCIS (Netherlands)

    Javaheri, N.; Dries, R; Burson, A.; Stal, L.J.; Sloot, P.M.A.; Kaandorp, J.A.

    2015-01-01

    Silica deposition by diatoms, a common component of the phytoplankton, has attracted considerable interest given the importance in ecology and materials science. There has recently been a great deal of research into the biological control of biosilicifcation, yet the in vivo physical and chemical

  11. Temperature affects the silicate morphology in a diatom

    NARCIS (Netherlands)

    Javaheri, N.; Dries, R.; Burson, A.; Stal, L.J.; Sloot, P.M.A.; Kaandorp, J.A.

    2015-01-01

    Silica deposition by diatoms, a common component of the phytoplankton, has attracted considerable interest given the importance in ecology and materials science. There has recently been a great deal of research into the biological control of biosilicifcation, yet the in vivo physical and

  12. Enhancement of the reactive iron pool by marine diatoms

    NARCIS (Netherlands)

    Rijkenberg, Micha J. A.; Gerringa, Loes J. A.; Timmermans, Klaas R.; Fischer, Astrid C.; Kroon, Koos J.; Buma, Anita G. J.; Wolterbeek, Bert Th.; de Baar, Hein J. W.

    2008-01-01

    Short term (2 days) laboratory experiments were performed to study the change in irradiance induced production of Fe(II) in seawater in the presence of two open oceanic Southern Ocean diatom species, Thalassiosira sp. and Chaetoceros brevis. Three irradiance conditions were applied: 1) UVB+UVA+VIS,

  13. The Phaeodactylum genome reveals the evolutionary history of diatom genomes

    Czech Academy of Sciences Publication Activity Database

    Bowler, Ch.; Allen, A. E.; Badger, J. H.; Grimwood, J.; Jabbari, K.; Kuo, A.; Maheswari, U.; Martens, C.; Maumus, F.; Otillar, R. P.; Rayko, E.; Salamov, A.; Vandepoele, K.; Beszteri, B.; Gruber, A.; Heijde, M.; Katinka, M.; Mock, T.; Valentin, K.; Verret, F.; Berges, J. A.; Brownlee, C.; Cadoret, J.-P.; Chiovitti, A.; Choi, Ch. J.; Coesel, S.; De Martino, A.; Detter, J. Ch.; Durkin, C.; Falciatore, A.; Fournet, J.; Haruta, M.; Huysman, M. J. J.; Jenkins, B. D.; Jiroutová, Kateřina; Jorgensen, R. E.; Joubert, Y.; Kaplan, A.; Kröger, N.; Kroth, P. G.; La Roche, J.; Lindquist, E.; Lommer, M.; Martin–Jézéquel, V.; Lopez, P. J.; Lucas, S.; Mangogna, M.; McGinnis, K.; Medlin, L. K.; Montsant, A.; Oudot–Le Secq, M.-P.; Napoli, C.; Oborník, Miroslav; Schnitzler Parker, M.; Petit, J.-L.; Porcel, B. M.; Poulsen, N.; Robison, M.; Rychlewski, L.; Rynearson, T. A.; Schmutz, J.; Shapiro, H.; Siaut, M.; Stanley, M.; Sussman, M. R.; Taylor, A. R.; Vardi, A.; von Dassow, P.; Vyverman, W.; Willis, A.; Wyrwicz, L. S.; Rokhsar, D. S.; Weissenbach, J.; Armbrust, E. V.; Green, B. R.; Van de Peer, Y.; Grigoriev, I. V.

    2008-01-01

    Roč. 456, 13-11-2008 (2008), s. 239-244 ISSN 0028-0836 Institutional research plan: CEZ:AV0Z60220518 Keywords : Phaeodactylum * genome * evolution * diatom Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 31.434, year: 2008

  14. Models for calculation of dissociation energies of homonuclear diatomic molecules

    International Nuclear Information System (INIS)

    Brewer, L.; Winn, J.S.

    1979-08-01

    The variation of known dissociation energies of the transition metal diatomics across the Periodic Table is rather irregular like the bulk sublimation enthalpy, suggesting that the valence-bond model for bulk metallic systems might be applicable to the gaseous diatomic molecules and the various intermediate clusters. Available dissociation energies were converted to valence-state bonding energies considering various degrees of promotion to optimize the bonding. The degree of promotion of electrons to increase the number of bonding electrons is smaller than for the bulk, but the trends in bonding energy parallel the behavior found for the bulk metals. Thus using the established trends in bonding energies for the bulk elements, it was possible to calculate all unknown dissociation energies to provide a complete table of dissociation energies for all M 2 molecules from H 2 to Lr 2 . For solids such as Mg, Al, Si and most of the transition metals, large promotion energies are offset by strong bonding between the valence state atoms. The main question is whether bonding in the diatomics is adequate to sustain extensive promotion. The most extreme example for which a considerable difference would be expected between the bulk and the diatomics would be that of the Group IIA and IIB metals. The first section of this paper which deals with the alkaline earths Mg and Ca demonstrates a significant influence of the excited valence state even for these elements. The next section then expands the treatment to transition metals

  15. Diatoms in peat – dominant producers in a changing environment?

    DEFF Research Database (Denmark)

    Kokfelt, Ulla; Struyf, Eric; Randsalu, Linda

    2009-01-01

    to another, the old vegetation may be suppressed, die out or start to decay, and some time may pass until a new mire vegetation is fully established. Here, we demonstrate that diatoms may thrive during such transitions, creating isolated and shallow peat layers with significantly elevated biogenic silica...

  16. Molecular basis of chromatic adaptation in pennate diatom Phaeodactylum tricornutum

    Czech Academy of Sciences Publication Activity Database

    Herbstová, Miroslava; Bína, David; Koník, P.; Gardian, Zdenko; Vácha, František; Litvín, Radek

    2015-01-01

    Roč. 1847, 6-7 (2015), s. 534-543 ISSN 0005-2728 R&D Projects: GA ČR GBP501/12/G055 Institutional support: RVO:60077344 Keywords : Chromatic adaptation * Diatom * Heterokonta * Light harvesting antenna Subject RIV: CE - Biochemistry Impact factor: 4.864, year: 2015

  17. The effects of phosphorus limitation on carbon metabolism in diatoms.

    Science.gov (United States)

    Brembu, Tore; Mühlroth, Alice; Alipanah, Leila; Bones, Atle M

    2017-09-05

    Phosphorus is an essential element for life, serving as an integral component of nucleic acids, lipids and a diverse range of other metabolites. Concentrations of bioavailable phosphorus are low in many aquatic environments. Microalgae, including diatoms, apply physiological and molecular strategies such as phosphorus scavenging or recycling as well as adjusting cell growth in order to adapt to limiting phosphorus concentrations. Such strategies also involve adjustments of the carbon metabolism. Here, we review the effect of phosphorus limitation on carbon metabolism in diatoms. Two transcriptome studies are analysed in detail, supplemented by other transcriptome, proteome and metabolite data, to gain an overview of different pathways and their responses. Phosphorus, nitrogen and silicon limitation responses are compared, and similarities and differences discussed. We use the current knowledge to propose a suggestive model for the carbon flow in phosphorus-replete and phosphorus-limited diatom cells.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Authors.

  18. A comparison of soda and soda-AQ pulps from cotton stalks

    African Journals Online (AJOL)

    STORAGESEVER

    2009-11-16

    Nov 16, 2009 ... Duzce University, Faculty of Forestry, Konuralp Campus, 81620 Düzce, Turkey. ... two in Latin America and three in Africa and Middle East. (Casey, 1990). ... After that the cotton stalks were dried in the laboratory atmosphere, ...

  19. Gene duplication, tissue-specific gene expression and sexual conflict in stalk-eyed flies (Diopsidae).

    Science.gov (United States)

    Baker, Richard H; Narechania, Apurva; Johns, Philip M; Wilkinson, Gerald S

    2012-08-19

    Gene duplication provides an essential source of novel genetic material to facilitate rapid morphological evolution. Traits involved in reproduction and sexual dimorphism represent some of the fastest evolving traits in nature, and gene duplication is intricately involved in the origin and evolution of these traits. Here, we review genomic research on stalk-eyed flies (Diopsidae) that has been used to examine the extent of gene duplication and its role in the genetic architecture of sexual dimorphism. Stalk-eyed flies are remarkable because of the elongation of the head into long stalks, with the eyes and antenna laterally displaced at the ends of these stalks. Many species are strongly sexually dimorphic for eyespan, and these flies have become a model system for studying sexual selection. Using both expressed sequence tag and next-generation sequencing, we have established an extensive database of gene expression in the developing eye-antennal imaginal disc, the adult head and testes. Duplicated genes exhibit narrower expression patterns than non-duplicated genes, and the testes, in particular, provide an abundant source of gene duplication. Within somatic tissue, duplicated genes are more likely to be differentially expressed between the sexes, suggesting gene duplication may provide a mechanism for resolving sexual conflict.

  20. A rare cause of hyperprolactinemia: persistent trigeminal artery with stalk-section effect

    International Nuclear Information System (INIS)

    Ekinci, G.; Baltacioglu, F.; Cimsit, C.; Akpinar, I.; Erzen, C.; Kilic, T.; Pamir, N.

    2001-01-01

    The primitive trigeminal, otic, hypoglossal, and proatlantal intersegmental arteries are fetal anastomoses between the carotid and vertebrobasilar systems. Persistent trigeminal artery (PTA) is the most frequent embryonic communication between the vertebrobasilar and carotid systems in adults. We report a case of PTA compressing the left side of the pituitary gland and stalk, in a patient with elevated blood prolactin level. (orig.)

  1. Synergistic effect on co-pyrolysis of capsicum stalks and coal | Niu ...

    African Journals Online (AJOL)

    With the depletion of fossil fuel and the concern about environmental issues, the utilization of biomass resources has attracted increasing worldwide interest. The pyrolysis behavior of capsicum stalks and Baoji coal mixtures was investigated by TG-DSC. Results show that the thermal degradation temperature range of ...

  2. Biochemical response and host-pathogen relation of stalk rot fungi ...

    African Journals Online (AJOL)

    Stalk rot is a destructive disease in maize caused by Fusarium and Macrophomina species. A study was carried out to understand the mode of infection, host biochemical response and comparison of inoculation techniques in Fusarium verticillioides and Macrophomina phaseolina in maize. In seed inoculation experiment, ...

  3. Stalking. Part II: Victims' problems with the legal system and therapeutic considerations.

    Science.gov (United States)

    Abrams, K M; Robinson, G E

    1998-06-01

    This paper is the second of 2 parts reviewing the topic of stalking. It focuses on victims difficulties with the legal system and the psychotherapeutic tasks for victims and therapists. Computerized literature searches were used to identify relevant papers from psychiatric and legal journals. Publications by victims' and women's organizations provided additional information. Victims suffer emotional consequences from being stalked. Additional stress is caused by the legal system's lack of understanding of the causes and consequences of stalking and inadequate and unenforced laws. The treatment of victims requires a comprehensive approach, including education, supportive psychotherapy, and discussion of practical measures. Therapists may overidentify with the patient's powerlessness or hesitate to take on a case out of fear of the stalker. Female therapists may protect themselves against the realization of their own vulnerability by blaming the victim, while male therapists may feel defensive or overprotective. Stalking is a crime with major mental health consequences which is often poorly understood by society. Therapists need to be aware of the victim's emotional reactions, the types of legal and practical supports available, and the possible biases of society. Further education and research should be encouraged.

  4. Transection of the pituitary stalk: evaluation of two cases by computerized tomography and magnetic resonance

    International Nuclear Information System (INIS)

    Amaral, L.L.F. do; Mendonca, R.A.; Natal, M.R.C.

    1992-01-01

    The authors present two cases of pituitary dwarfism where the study by high resolution computed tomography and by magnetic resonance imaging show transection of the pituitary stalk as the cause of the endocrine disturb. The importance of these methods on the investigation of disturbs of the hypothalamus-hypophyseal axis is stressed. (author)

  5. A study on the chopping and mixing of cotton stalks with soil

    African Journals Online (AJOL)

    USER

    2010-07-26

    Jul 26, 2010 ... INTRODUCTION ... porating plant residues into soil reduces the risk of soil ... stalks into soil increases the productivity of the field. ... producers were asked about the total area of their agricultural fields .... are made of forged steel in one piece. ... maintenance works such as thinning, weeding and irrigation.

  6. Status of maize stalk rot complex in western belts of Nepal and its integrated management

    Directory of Open Access Journals (Sweden)

    Subash Subedi

    2016-12-01

    Full Text Available Maize stalk rot complex is becoming a serious threat for maize growing areas of Nepal. A field monitoring for maize stalk rot complex was done during crop season (August, 2016 covering 10 farmers field each of Surkhet, Banke, Dang, Chitwan and Nawalparasi districts. Maize crop showed highly susceptible reaction to the disease at western belts of Dang and susceptible reaction was marked in Chitwan and Nawalparasi districts while the disease effect was mild at Banke and Surkhet district. Most of the plant diseases managed successfully through the application of bio-control agents, host resistance, chemicals and other different cultural control methods. The result of field experiment conducted at Dang showed that all the treatments had significant (P≤0.05 effect on percent disease index (PDI and crop yield over farmers practice to control maize stalk rot. The higher percent disease control (52.36% and yield increase (40.29% were recorded from the plot sprayed with streptocyclin @ 2 g L-1 and insecticide (cypermethrin + chloropyrifos @ 2.5 ml L-1 of water during knee height and subsequent spray after 15 days interval as compared to farmers practice. Out of 30 genotypes, Rampur composit, Arun 2, Rampur 34, RamS03F08, TLBRS07F16 and Rampur 24 were found resistant against stalk rot complex with higher yield at Rampur Chitwan.

  7. Continuous ethanol production using yeast immobilized on sugar-cane stalks

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, J.N. de [Alagoas Univ., Maceio, AL (Brazil). Dept. de Engenharia Quimica]. E-mail: jnunes@ctec.ufal.br; Lopes, C.E. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Antibioticos; Franca, F.P. de [Universidade Federal, Rio de Janeiro, RJ (Brazil). Escola de Quimica. Dept. de Engenharia Bioquimica

    2004-09-01

    Sugar-cane stalks, 2.0 cm long, were used as a support for yeast immobilization envisaging ethanol production. The assays were conducted in 38.5 L fermenters containing a bed of stalks with 50% porosity. The operational stability of the immobilized yeast, the efficiency and stability of the process, as well as the best dilution rate were evaluated. Molasses from demerara sugar production was used in the medium formulation. It was diluted to obtain 111.75 {+-} 1.51 g/L without any further treatment. Sulfuric acid was used to adjust the pH value to around 4.2. Every two days Kamoran HJ (10 ppm) or with a mixture containing penicillin (10 ppm) and tetracycline (10 ppm), was added to the medium. Ethanol yield and efficiency were 29.64 g/L.h and 86.40%, respectively, and the total reducing sugars conversion was 74.61% at a dilution rate of 0.83 h{sup -1}. The yeast-stalk system was shown to be stable for over a 60 day period at extremely variable dilution rates ranging from 0.05 h{sup -1} to 3.00 h{sup -1}. The concentration of immobilized cell reached around 109 cells/gram of dry sugar-cane stalk when the fermenter was operating at the highest dilution rate (3.00 h{sup -1}). (author)

  8. Effects of fistular onion stalk extract on the level of NO and ...

    African Journals Online (AJOL)

    user

    2011-03-28

    Mar 28, 2011 ... In this study, we investigated the effects of fistular onion stalk extracts on nitric oxide ... and flavonoids in onion (Knekt et al., 1996). ... cells lie between blood flow and smooth muscle cells. ... strated by a reduction in the blood vessel dilation factors .... raw onion inhibits platelet-mediated thrombosis in dogs.

  9. Wet Oxidation Pretreatment of Tobacco Stalks and Orange Waste for Bioethanol Production. Preliminary results

    DEFF Research Database (Denmark)

    Martin, Carlos; Fernandez, Teresa; Garcia, Ariel

    2009-01-01

    Wet oxidation (WO) was used as a pretreatment method prior to enzymatic hydrolysis of tobacco stalks and orange waste. The pretreatment, performed at 195 degrees C and an oxygen pressure of 1.2 MPa, for 15 min, in the presence of Na2CO3, increased the cellulose content of the materials and gave c...

  10. Organics and mineral fertilizers and biological control on the incidence of stalk rot and corn yield

    Directory of Open Access Journals (Sweden)

    Elena Blume

    2014-06-01

    Full Text Available The expansion of area under maize (Zea mays L. and the use of no tillage have favored the incidence of stalk rot on this crop. The study aimed to evaluate the organic fertilizers and the treatment of corn seeds with Trichoderma spp. on the production of dry matter (DM of shoot, incidence of stalk rot and corn yield. The experiment consisted in a factorial with split-plot in strips, on the randomized block design with four replicates, and the fertilization treatments (pig slurry; swine deep bedding; cattle slurry; mineral fertilizer; control treatment were applied to the plots and the seeds treatment (with and without Trichoderma spp. in the subplots. At the flowering stage, three corn plants per subplot were collected for the assessment of DM production. At physiological maturity stage, the incidence of stalk rot was assessed, and the ears of corn harvested for productivity assessment. The organic and mineral fertilizers increased the production of DM and productivity of corn. Trichoderma spp. increased the production of DM of corn, but had no reflection on productivity. The incidence of stalk rot in corn was higher in treatments with organic and mineral fertilization. Organic fertilizers increase dry matter production of shoot and corn yield, and Trichoderma spp. provides an increase in dry matter production of shoot.

  11. Carbohydrate Status of Tulip Bulbs during Cold-Induced Flower Stalk Elongation and Flowering.

    Science.gov (United States)

    Lambrechts, H.; Rook, F.; Kolloffel, C.

    1994-01-01

    The effect of a cold treatment on the carbohydrate status of the scales and flower stalk of Tulipa gesneriana L. cv Apeldoorn bulbs during growth after planting was studied and compared with bulbs not given cold treatment. Bulbs were stored dry for 12 weeks at 5[deg]C (precooled) or 17[deg]C (noncooled). Only the 5[deg]C treatment led to rapid flower stalk elongation and flowering following planting at higher temperatures. Precooling enhanced mobilization of starch, fructans, and sucrose in the scales. The cold-stimulated starch breakdown was initially accompanied by increased [alpha]-amylase activity per scale. In noncooled bulbs, [alpha]-amylase activity slightly decreased or remained more or less constant. Cold-induced flower stalk elongation was partially accompanied by a decrease in the sucrose content and an increase in the glucose content and invertase activity per g dry weight. The starch content in internodes initially decreased and subsequently increased; [alpha]-amylase activity per g dry weight of the lowermost internode showed a peak pattern during starch breakdown and increased thereafter. The internodes of noncooled bulbs, on the contrary, accumulated sucrose. Their glucose content and invertase activity per g dry weight remained low. Starch breakdown was not found and [alpha]-amylase activity per g dry weight of the lowermost internode remained at a low level. Precooling of tulip bulbs thus favors reserve mobilization in the scales and flower stalk and glucose accumulation in the elongating internodes. PMID:12232100

  12. Colchicine affects cell motility, pattern formation and stalk cell differentiation in Dictyostelium by altering calcium signaling.

    Science.gov (United States)

    Poloz, Yekaterina; O'Day, Danton H

    2012-04-01

    Previous work, verified here, showed that colchicine affects Dictyostelium pattern formation, disrupts morphogenesis, inhibits spore differentiation and induces terminal stalk cell differentiation. Here we show that colchicine specifically induces ecmB expression and enhances accumulation of ecmB-expressing cells at the posterior end of multicellular structures. Colchicine did not induce a nuclear translocation of DimB, a DIF-1 responsive transcription factor in vitro. It also induced terminal stalk cell differentiation in a mutant strain that does not produce DIF-1 (dmtA-) and after the treatment of cells with DIF-1 synthesis inhibitor cerulenin (100 μM). This suggests that colchicine induces the differentiation of ecmB-expressing cells independent of DIF-1 production and likely through a signaling pathway that is distinct from the one that is utilized by DIF-1. Depending on concentration, colchicine enhanced random cell motility, but not chemotaxis, by 3-5 fold (10-50 mM colchicine, respectively) through a Ca(2+)-mediated signaling pathway involving phospholipase C, calmodulin and heterotrimeric G proteins. Colchicine's effects were not due to microtubule depolymerization as other microtubule-depolymerizing agents did not have these effects. Finally normal morphogenesis and stalk and spore cell differentiation of cells treated with 10 mM colchicine were rescued through chelation of Ca2+ by BAPTA-AM and EDTA and calmodulin antagonism by W-7 but not PLC inhibition by U-73122. Morphogenesis or spore cell differentiation of cells treated with 50 mM colchicine could not be rescued by the above treatments but terminal stalk cell differentiation was inhibited by BAPTA-AM, EDTA and W-7, but not U-73122. Thus colchicine disrupts morphogenesis and induces stalk cell differentiation through a Ca(2+)-mediated signaling pathway involving specific changes in gene expression and cell motility. Copyright © 2011 International Society of Differentiation. Published by Elsevier B

  13. Growth of wheat and lettuce and enzyme activities of soils under garlic stalk decomposition for different durations.

    Science.gov (United States)

    Han, Xu; Cheng, Zhihui; Meng, Huanwen

    2017-07-01

    Garlic (Allium sativum L.) stalk is a byproduct of garlic production that is normally thought of as waste but is now considered a useful biological resource. It is necessary to utilize this resource efficiently and reasonably to reduce environmental pollution and achieve sustainable agricultural development. The effect of garlic stalk decomposed for different durations was investigated in this study using wheat (Triticum aestivum L.) and lettuce (Lactuca sativa var. crispa L.) as test plants. Garlic stalk in early stages of decomposition inhibited the shoot and root lengths of wheat and lettuce, but it promoted the shoot and root lengths in later stages; longer durations of garlic stalk decomposition significantly increased the shoot and root fresh weights of wheat and lettuce, whereas shorter decomposing durations significantly decreased the shoot and root fresh weights; and garlic stalk at different decomposition durations increased the activities of urease, sucrase and alkaline phosphatase in soil where wheat or lettuce was planted. Garlic stalk decomposed for 30 or 40 days could promote the growth of wheat and lettuce plants as well as soil enzyme activities. These results may provide a scientific basis for the study and application of garlic stalk. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  14. [Effects of cotton stalk biochar on microbial community structure and function of continuous cropping cotton rhizosphere soil in Xinjiang, China].

    Science.gov (United States)

    Gu, Mei-ying; Tang, Guang-mu; Liu, Hong-liang; Li, Zhi-qiang; Liu, Xiao-wei; Xu, Wan-li

    2016-01-01

    In this study, field trials were conducted to examine the effects of cotton stalk biochar on microbial population, function and structural diversity of microorganisms in rhizosphere soil of continuous cotton cropping field in Xinjiang by plate count, Biolog and DGGE methods. The experiment was a factorial design with four treatments: 1) normal fertilization with cotton stalk removed (NPK); 2) normal fertilization with cotton stalk powdered and returned to field (NPKS); 3) normal fertilization plus cotton stalk biochar at 22.50 t · hm⁻² (NPKB₁); and 4) normal fertilization plus cotton stalk biochar at 45.00 t · hm⁻² (NPKB₂). The results showed that cotton stalk biochar application obviously increased the numbers of bacteria and actinomycetes in the rhizospheric soil. Compared with NPK treatment, the number of fungi was significantly increased in the NPKB₁treatment, but not in the NPKB₂ treatment. However, the number of fungi was generally lower in the biochar amended (NPKB₁, NPKB₂) than in the cotton stalk applied plots (NPKS). Application of cotton stalk biochar increased values of AWCD, and significantly improved microbial richness index, suggesting that the microbial ability of utilizing carbohydrates, amino acids and carboxylic acids, especially phenolic acids was enhanced. The number of DGGE bands of NPKB₂ treatment was the greatest, with some species of Gemmatimonadetes, Acidobacteria, Proteobacteria and Actinobacteria being enriched. UPGMC Cluster analysis pointed out that bacterial communities in the rhizospheric soil of NPKB₂ treatment were different from those in the NPK, NPKS and NPKB₁treatments, which belonged to the same cluster. These results indicated that application of cotton stalk biochar could significantly increase microbial diversity and change soil bacterial community structure in the cotton rhizosphere soil, thus improving the health of soil ecosystem.

  15. Response of the ubiquitous pelagic diatom Thalassiosira weissflogii to darkness and anoxia.

    Directory of Open Access Journals (Sweden)

    Anja Kamp

    Full Text Available Thalassiosira weissflogii, an abundant, nitrate-storing, bloom-forming diatom in the world's oceans, can use its intracellular nitrate pool for dissimilatory nitrate reduction to ammonium (DNRA after sudden shifts to darkness and anoxia, most likely as a survival mechanism. T. weissflogii cells that stored 4 mM (15N-nitrate consumed 1.15 (±0.25 fmol NO3 (- cell(-1 h(-1 and simultaneously produced 1.57 (±0.21 fmol (15NH4 (+ cell(-1 h(-1 during the first 2 hours of dark/anoxic conditions. Ammonium produced from intracellular nitrate was excreted by the cells, indicating a dissimilatory rather than assimilatory pathway. Nitrite and the greenhouse gas nitrous oxide were produced at rates 2-3 orders of magnitude lower than the ammonium production rate. While DNRA activity was restricted to the first few hours of darkness and anoxia, the subsequent degradation of photopigments took weeks to months, supporting the earlier finding that diatoms resume photosynthesis even after extended exposure to darkness and anoxia. Considering the high global abundance of T. weissflogii, its production of ammonium and nitrous oxide might be of ecological importance for oceanic oxygen minimum zones and the atmosphere, respectively.

  16. Response of the ubiquitous pelagic diatom Thalassiosira weissflogii to darkness and anoxia.

    Science.gov (United States)

    Kamp, Anja; Stief, Peter; Knappe, Jan; de Beer, Dirk

    2013-01-01

    Thalassiosira weissflogii, an abundant, nitrate-storing, bloom-forming diatom in the world's oceans, can use its intracellular nitrate pool for dissimilatory nitrate reduction to ammonium (DNRA) after sudden shifts to darkness and anoxia, most likely as a survival mechanism. T. weissflogii cells that stored 4 mM (15)N-nitrate consumed 1.15 (±0.25) fmol NO3 (-) cell(-1) h(-1) and simultaneously produced 1.57 (±0.21) fmol (15)NH4 (+) cell(-1) h(-1) during the first 2 hours of dark/anoxic conditions. Ammonium produced from intracellular nitrate was excreted by the cells, indicating a dissimilatory rather than assimilatory pathway. Nitrite and the greenhouse gas nitrous oxide were produced at rates 2-3 orders of magnitude lower than the ammonium production rate. While DNRA activity was restricted to the first few hours of darkness and anoxia, the subsequent degradation of photopigments took weeks to months, supporting the earlier finding that diatoms resume photosynthesis even after extended exposure to darkness and anoxia. Considering the high global abundance of T. weissflogii, its production of ammonium and nitrous oxide might be of ecological importance for oceanic oxygen minimum zones and the atmosphere, respectively.

  17. Diatom, cyanobacterial and microbial mats as indicators of hydrocarbon contaminated Arctic streams and waters

    Energy Technology Data Exchange (ETDEWEB)

    Ziervogel, H.; Selann, J.; Adeney, B. [EBA Engineering Consultants Ltd., Edmonton, AB (Canada); Nelson, J.A. [J.B. Services, Sarnia, ON (Canada); Murdock, E. [Nunavut Power, Iqaluit (Canada)

    2003-07-01

    An environmental assessment conducted at Repulse Bay, Nunavut in the summer of 2001 revealed a recent diesel spill flowing from the groundwater into a creek. The spill had not been reported. When Arctic surface waters mix with hydrocarbon impacted groundwater and sediments, distinctive mats of diatom, cyanobacteria and other bacteria are formed. These mats have the potential for phytoremediation of hydrocarbons. This paper explained the apparent dominance of mats in contaminated Arctic waters and why they promote biodegradation of hydrocarbons. Hydrocarbon-contaminated soils and groundwater are generally anaerobic. The higher dissolved carbon dioxide in polluted soils and groundwater can benefit photosynthetic cyanobacteria and diatom found in oligotrophic, lower alkalinity Arctic waters. The anaerobic and aerobic bacteria can potentially take advantage of the hydrogen substrate and the nitrogen fixing abilities of the cyanobacteria. Zooplankton predators may be killed off by the toxicity of the polluted groundwater. The paper provides examples where a microbial mat reduced the sulfate content of a hydrocarbon-impacted Arctic stream by 100 ppm, and where a pond covered in a benthic microbial mat showed no evidence of hydrocarbons in the water overlying sediments contaminated with hydrocarbons at concentrations measured at 30,000 ppm. 19 refs., 3 tabs., 8 figs.

  18. Effect of diatom morphology on the small-scale behavior of the copepod Temora stylifera (Dana, 1849)

    KAUST Repository

    Mahadik, Gauri A.; Castellani, Claudia; Mazzocchi, Maria Grazia

    2017-01-01

    We explored the small-scale behavior of the calanoid copepod Temora stylifera in relation to the diatoms Chaetoceros socialis, Leptocylindrus aporus, Leptocylindrus danicus and Pseudo-nitzschia calliantha offered as monospecific diets at similar carbon concentrations. These four diatoms are characterized by distinct size, shape and colony forming ability and are important components of the autumnal bloom co-occurring with the seasonal peak of T. stylifera abundance in Mediterranean coastal waters. High-speed video recordings showed that T. stylifera acquired cells in a suspension feeding mode while creating feeding currents. Copepod behavior was quantified in terms of feeding, motion, and grooming activities. T. stylifera spent more time in hovering than cruising in presence of all diets. The solitary L. aporus and P. calliantha elicited longer feeding bouts, lower appendage beat frequency and shorter grooming events compared to the colonial L. danicus and C. socialis. Overall the present results indicate that the behavioral responses of T. stylifera to different diatom diets were species-specific. The observed behavioral plasticity may help T. stylifera to adjust rapidly to changes in the food environment and this can be advantageous in exploiting short-lived phytoplankton blooms.

  19. Effect of diatom morphology on the small-scale behavior of the copepod Temora stylifera (Dana, 1849)

    KAUST Repository

    Mahadik, Gauri A.

    2017-05-12

    We explored the small-scale behavior of the calanoid copepod Temora stylifera in relation to the diatoms Chaetoceros socialis, Leptocylindrus aporus, Leptocylindrus danicus and Pseudo-nitzschia calliantha offered as monospecific diets at similar carbon concentrations. These four diatoms are characterized by distinct size, shape and colony forming ability and are important components of the autumnal bloom co-occurring with the seasonal peak of T. stylifera abundance in Mediterranean coastal waters. High-speed video recordings showed that T. stylifera acquired cells in a suspension feeding mode while creating feeding currents. Copepod behavior was quantified in terms of feeding, motion, and grooming activities. T. stylifera spent more time in hovering than cruising in presence of all diets. The solitary L. aporus and P. calliantha elicited longer feeding bouts, lower appendage beat frequency and shorter grooming events compared to the colonial L. danicus and C. socialis. Overall the present results indicate that the behavioral responses of T. stylifera to different diatom diets were species-specific. The observed behavioral plasticity may help T. stylifera to adjust rapidly to changes in the food environment and this can be advantageous in exploiting short-lived phytoplankton blooms.

  20. Contrasting Photo-physiological Responses of the Haptophyte Phaeocystis Antarctica and the Diatom Pseudonitzschia sp. in the Ross Sea (Antarctica

    Directory of Open Access Journals (Sweden)

    Sasha Tozzi

    2017-05-01

    Full Text Available The Antarctic is a unique environment in which substantial variations in irradiance occur over a number of time scales, and as a result phytoplankton need to acclimate and adapt to these changes. We conducted field and laboratory manipulations in the Ross Sea, Antarctica to examine photophysiological differences between Phaeocystis antarctica and Pseudonitzschia sp. a diatom that commonly occurrs in the Ross Sea, since these are the two functional groups that dominate abundance and productivity. Both exhibited reduced quantum yields due to high irradiances. P. antarctica, a haptophyte, displays a distinct photophysiological response to irradiance when compared to diatoms. P. antarctica showed a rapid recovery from high light exposure, as indicated by the rapid return to initial, high quantum yields, in contrast to diatoms, which responded more slowly. Absorption cross sections were high in both forms, but those in P. antarctica were significantly higher. Both organisms recovered within 24 h to initial quantum yields, suggesting that high irradiance exposure does not have a permanent effect on these organisms. Among all micronutrient additions (iron, cobalt, zinc and vitamin B12, only iron additions resulted in rapid impacts on quantum yields. Iron limitation also can result in reduced photosynthetic efficiency. Understanding these photophysiologial responses and the impact of oceanographic conditions provides constraints on modeling efforts of photosynthesis and primary productivity in the Antarctic.

  1. Diatom diet selectivity by early post-larval abalone Haliotis diversicolor supertexta under hatchery conditions

    Science.gov (United States)

    Zhang, Yuyu; Gao, Yahui; Liang, Junrong; Chen, Changping; Zhao, Donghai; Li, Xuesong; Li, Yang; Wu, Wenzhong

    2010-11-01

    Benthic diatoms constitute the primary diet of abalone during their early stages of development. To evaluate the dietary preferences of early post-larval abalone, Haliotis diversicolor supertexta, we analyzed the gut contents of post-larvae that settled on diatom films. We compared the abundance and species diversity of diatom assemblages in the gut to those of the epiphytic diatom assemblages on the attachment films, and identified 40 benthic diatom species in the gut contents of post-larvae 12 to 24 d after settlement. The most abundant taxa in the gut contents were Navicula spp., Amphora copulate, and Amphora coffeaeformis. Navicula spp. accounted for 64.0% of the cell density. In the attachment films, we identified 110 diatom species belonging to 38 genera. Pennate diatoms were the dominant members including the species Amphiprora alata, Cocconeis placentula var. euglypta, Cylindrotheca closterium, Navicula sp. 2, and A. coffeaeformis. Nano-diatoms (abalone seed. The difference of the composition and abundance of diatoms between in the guts and on the biofilms suggests that early post-larval grazing was selective. An early post-larval abalone preferred nano-diatoms and the genera Navicula and Amphora during the month after settlement.

  2. Momentum autocorrelation function of a classic diatomic chain

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ming B., E-mail: mingbyu@gmail.com

    2016-10-23

    A classical harmonic diatomic chain is studied using the recurrence relations method. The momentum autocorrelation function results from contributions of acoustic and optical branches. By use of convolution theorem, analytical expressions for the acoustic and optical contributions are derived as even-order Bessel function expansions with coefficients given in terms of integrals of elliptic functions in real axis and a contour parallel to the imaginary axis, respectively. - Highlights: • Momentum autocorrelation function of a classic diatomic chain is studied. • It is derived as even-order Bessel function expansion using the convolution theorem. • The expansion coefficients are integrals of elliptic functions. • Addition theorem is used to reduce complex elliptic function to complex sum of real ones.

  3. Diatom. A potential bio-accumulator of gold

    International Nuclear Information System (INIS)

    Chakraborty, N.; Pal, R.; Ramaswami, A.; Nayak, D.; Lahiri, S.

    2006-01-01

    The bioaccumulation of gold in trace concentration by Nitzschia obtusa and Navicula minima, two members of bacillariophyceae, has been studied. It has been observed that Nitzschia obtusa showed better accumulation of gold in acidic pH in comparison to neutral and basic pH. Maximum accumulation was observed with 1 mg x kg -1 or less gold concentration. However, the accumulation by the living cells was reduced when the matrix concentration was higher. Navicula minima, on the other hand, found to be a better accumulator of gold in wide ranges of pH and substrate concentration of the media. It was also inferred that the gold accumulation by diatom was mainly due to adsorption by biosilica (siliceous frustules of dead diatom cells). Accumulated gold was recovered with conc. HNO 3 . (author)

  4. Hypothalamic-pituitary vascularization in pituitary stalk transection syndrome: is the pituitary stalk really transected? The role of gadolinium-DTPA with spin-echo T1 imaging and turbo-FLASH technique

    Energy Technology Data Exchange (ETDEWEB)

    Genovese, E. [Dept. of Radiology, IRCCS Policlinico S. Matteo, Pavia (Italy); Maghnie, M. [Dept. of Pediatrics, Univ. of Pavia (Italy); Beluffi, G. [Dept. of Radiodiagnosis, Section of Pediatric Radiology, IRCCS Policlinico S. Matteo, Pavia (Italy); Villa, A. [Dept. of Radiology, IRCCS Policlinico S. Matteo, Pavia (Italy); Sammarchi, L. [Dept. of Radiology, IRCCS Policlinico S. Matteo, Pavia (Italy); Severi, F. [Dept. of Pediatrics, Univ. of Pavia (Italy); Campani, R. [Dept. of Radiology, IRCCS Policlinico S. Matteo, Pavia (Italy)

    1997-01-01

    We examined 14 patients, aged 10-25 years, with idiopathic hypopituitarism. All presented an ectopic posterior pituitary at the median eminence with a hypoplastic anterior pituitary on magnetic resonance imaging (MRI). Eight patients had isolated growth hormone deficit (IGHD) and six had multiple hormone deficits (MPHD). Unenhanced MRI showed the pituitary stalk, which was extremely thin, in only three patients, while T1-weighted images obtained after intravenous injection of gadopentetate dimeglumine (Gd-DTPA) showed a thin pituitary stalk in seven patients (six with IGHD and one with MPHD), demonstrating a preserved vascular component of the stalk. MRI with Gd-DTPA was more sensitive than unenhanced MRI in detecting the pituitary stalk in patients with hypopituitarism with an ectopic posterior pituitary: the stalk was demonstrated in 50 % of the cases (seven patients), versus 21.4 % (three patients) by unenhanced MRI. The dynamic study of the hypothalamo-hypophyseal axis performed with turbo-FLASH sequences after bolus injection of Gd-DTPA showed the residual anterior pituitary to have arterial enhancement times, which suggests that an arterial system compensates for the absent or diminished blood supply from the portal system, independent of stalk detection. (orig.). With 5 figs., 1 tab.

  5. Hypothalamic-pituitary vascularization in pituitary stalk transection syndrome: is the pituitary stalk really transected? The role of gadolinium-DTPA with spin-echo T1 imaging and turbo-FLASH technique

    International Nuclear Information System (INIS)

    Genovese, E.; Maghnie, M.; Beluffi, G.; Villa, A.; Sammarchi, L.; Severi, F.; Campani, R.

    1997-01-01

    We examined 14 patients, aged 10-25 years, with idiopathic hypopituitarism. All presented an ectopic posterior pituitary at the median eminence with a hypoplastic anterior pituitary on magnetic resonance imaging (MRI). Eight patients had isolated growth hormone deficit (IGHD) and six had multiple hormone deficits (MPHD). Unenhanced MRI showed the pituitary stalk, which was extremely thin, in only three patients, while T1-weighted images obtained after intravenous injection of gadopentetate dimeglumine (Gd-DTPA) showed a thin pituitary stalk in seven patients (six with IGHD and one with MPHD), demonstrating a preserved vascular component of the stalk. MRI with Gd-DTPA was more sensitive than unenhanced MRI in detecting the pituitary stalk in patients with hypopituitarism with an ectopic posterior pituitary: the stalk was demonstrated in 50 % of the cases (seven patients), versus 21.4 % (three patients) by unenhanced MRI. The dynamic study of the hypothalamo-hypophyseal axis performed with turbo-FLASH sequences after bolus injection of Gd-DTPA showed the residual anterior pituitary to have arterial enhancement times, which suggests that an arterial system compensates for the absent or diminished blood supply from the portal system, independent of stalk detection. (orig.). With 5 figs., 1 tab

  6. Interface states in a class of heterojunctions between diatomic semiconductors

    International Nuclear Information System (INIS)

    Kandilarov, B.D.; Detcheva, V.

    1979-09-01

    The theory of interface state in heterojunctions between diatomic semiconductors is developed in the framework of the S-matrix approach and on the basis of a one-dimensional model. The condition for the existence of interface states is explicitly derived for undeformed and deformed herterojunctions. Numerical analysis is performed and several particular cases are discussed in order to clarify the general features of the problem. (author)

  7. Novel sex cells and evidence for sex pheromones in diatoms.

    Science.gov (United States)

    Sato, Shinya; Beakes, Gordon; Idei, Masahiko; Nagumo, Tamotsu; Mann, David G

    2011-01-01

    Diatoms belong to the stramenopiles, one of the largest groups of eukaryotes, which are primarily characterized by a presence of an anterior flagellum with tubular mastigonemes and usually a second, smooth flagellum. Based on cell wall morphology, diatoms have historically been divided into centrics and pennates, of which only the former have flagella and only on the sperm. Molecular phylogenies show the pennates to have evolved from among the centrics. However, the timing of flagellum loss--whether before the evolution of the pennate lineage or after--is unknown, because sexual reproduction has been so little studied in the 'araphid' basal pennate lineages, to which Pseudostaurosira belongs. Sexual reproduction of an araphid pennate, Pseudostaurosira trainorii, was studied with light microscopy (including time lapse observations and immunofluorescence staining observed under confocal scanning laser microscopy) and SEM. We show that the species produces motile male gametes. Motility is mostly associated with the extrusion and retrieval of microtubule-based 'threads', which are structures hitherto unknown in stramenopiles, their number varying from one to three per cell. We also report experimental evidence for sex pheromones that reciprocally stimulate sexualization of compatible clones and orientate motility of the male gametes after an initial 'random walk'. The threads superficially resemble flagella, in that both are produced by male gametes and contain microtubules. However, one striking difference is that threads cannot beat or undulate and have no motility of their own, and they do not bear mastigonemes. Threads are sticky and catch and draw objects, including eggs. The motility conferred by the threads is probably crucial for sexual reproduction of P. trainorii, because this diatom is non-motile in its vegetative stage but obligately outbreeding. Our pheromone experiments are the first studies in which gametogenesis has been induced in diatoms by cell

  8. Bacterial colonization of the freshwater planktonic diatom Fragilaria crotonensis

    Czech Academy of Sciences Publication Activity Database

    Znachor, Petr; Šimek, Karel; Nedoma, Jiří

    2012-01-01

    Roč. 66, č. 1 (2012), s. 87-94 ISSN 0948-3055 R&D Projects: GA ČR(CZ) GA206/08/0015; GA ČR(CZ) GAP504/11/2177; GA ČR(CZ) GAP504/11/2182 Institutional research plan: CEZ:AV0Z60170517 Keywords : PDMPO * bacterial colonization * diatoms * Fragilaria crotonensis * flood * reservoir Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.037, year: 2012

  9. Novel sex cells and evidence for sex pheromones in diatoms.

    Directory of Open Access Journals (Sweden)

    Shinya Sato

    Full Text Available BACKGROUND: Diatoms belong to the stramenopiles, one of the largest groups of eukaryotes, which are primarily characterized by a presence of an anterior flagellum with tubular mastigonemes and usually a second, smooth flagellum. Based on cell wall morphology, diatoms have historically been divided into centrics and pennates, of which only the former have flagella and only on the sperm. Molecular phylogenies show the pennates to have evolved from among the centrics. However, the timing of flagellum loss--whether before the evolution of the pennate lineage or after--is unknown, because sexual reproduction has been so little studied in the 'araphid' basal pennate lineages, to which Pseudostaurosira belongs. METHODS/PRINCIPAL FINDING: Sexual reproduction of an araphid pennate, Pseudostaurosira trainorii, was studied with light microscopy (including time lapse observations and immunofluorescence staining observed under confocal scanning laser microscopy and SEM. We show that the species produces motile male gametes. Motility is mostly associated with the extrusion and retrieval of microtubule-based 'threads', which are structures hitherto unknown in stramenopiles, their number varying from one to three per cell. We also report experimental evidence for sex pheromones that reciprocally stimulate sexualization of compatible clones and orientate motility of the male gametes after an initial 'random walk'. CONCLUSIONS/SIGNIFICANCE: The threads superficially resemble flagella, in that both are produced by male gametes and contain microtubules. However, one striking difference is that threads cannot beat or undulate and have no motility of their own, and they do not bear mastigonemes. Threads are sticky and catch and draw objects, including eggs. The motility conferred by the threads is probably crucial for sexual reproduction of P. trainorii, because this diatom is non-motile in its vegetative stage but obligately outbreeding. Our pheromone experiments

  10. Interactions of bacteria with diatoms: Influence on natural marine biofilms.

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, L.; DeCosta, P.M.; Anil, A.C.; Sawant, S.S.

    therein). In fact, biofilms are considered a reservoir and source of dissemination for V. cholerae (Shikuma & Hadfield 2010). Nutrient concentrations in the surrounding waters also affect the progression of the biofilm community (Qian et al. 2007... to render diatom monocultures near axenic (Patil & Anil 2005c). The following diluents were used – Aged Sea Water (ASW; unenriched control), ASW+streptomycin (ASW+S), ASW+chloramphenicol (ASW+C), f/2 medium (Guillard and Ryther, 1962) prepared in ASW [f...

  11. Recombinational laser employing electron transitions of diatomic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Biriukov, A S; Prokhorov, A M; Shelepin, L A; Shirokov, N N

    1974-12-01

    Conditions are established for obtaining laser action in the visible and uv regions of the spectrum, using transitions between electronic states of diatomic molecules during recombination of a dissociated gas. The mechanism of population inversion was studied for the oxygen molecule, and gain estimates were obtained for laser action at a wavelength of 4881 A. The feasibility of laser action at other wavelengths was examined.

  12. Single ionization of diatomic molecules by bare ion impact

    International Nuclear Information System (INIS)

    Purkait, M; Mandal, C R

    2014-01-01

    The molecular three-Coulomb wave model (M3CW) has been extensively used to study the double-differential ionization cross sections (DDCS) of diatomic molecules by the impact of bare ions at intermediate and high energies. In this model, the distortion of the initial channel by the incoming projectile is also included. The present DDCS results are found to be in good accord both with the experiment of Baran et al 2008 as well as with other theory

  13. Thermodynamics properties of diatomic molecules with general ...

    Indian Academy of Sciences (India)

    In this paper, the energy spectra of the general molecular potential are obtained using the asymptotic iteration method within the framework of non-relativistic quantum mechanics.With the energy spectrum obtained, the vibrational partition function is calculated in a closed form and is used to obtain an expression for other ...

  14. A Rapid Method for the Determination of Fucoxanthin in Diatom

    Directory of Open Access Journals (Sweden)

    Li-Juan Wang

    2018-01-01

    Full Text Available Fucoxanthin is a natural pigment found in microalgae, especially diatoms and Chrysophyta. Recently, it has been shown to have anti-inflammatory, anti-tumor, and anti-obesityactivity in humans. Phaeodactylum tricornutum is a diatom with high economic potential due to its high content of fucoxanthin and eicosapentaenoic acid. In order to improve fucoxanthin production, physical and chemical mutagenesis could be applied to generate mutants. An accurate and rapid method to assess the fucoxanthin content is a prerequisite for a high-throughput screen of mutants. In this work, the content of fucoxanthin in P. tricornutum was determined using spectrophotometry instead of high performance liquid chromatography (HPLC. This spectrophotometric method is easier and faster than liquid chromatography and the standard error was less than 5% when compared to the HPLC results. Also, this method can be applied to other diatoms, with standard errors of 3–14.6%. It provides a high throughput screening method for microalgae strains producing fucoxanthin.

  15. Models of the delayed nonlinear Raman response in diatomic gases

    International Nuclear Information System (INIS)

    Palastro, J. P.; Antonsen, T. M. Jr.; Pearson, A.

    2011-01-01

    We examine the delayed response of a diatomic gas to a polarizing laser field with the goal of obtaining computationally efficient methods for use with laser pulse propagation simulations. We demonstrate that for broadband pulses, heavy molecules such as O 2 and N 2 , and typical atmospheric temperatures, the initial delayed response requires only classical physics. The linear kinetic Green's function is derived from the Boltzmann equation and shown to be in excellent agreement with full density-matrix calculations. A straightforward perturbation approach for the fully nonlinear, kinetic impulse response is also presented. With the kinetic theory a reduced fluid model of the diatomic gas' orientation is derived. Transport coefficients are introduced to model the kinetic phase mixing of the delayed response. In addition to computational rapidity, the fluid model provides intuition through the use of familiar macroscopic quantities. Both the kinetic and the fluid descriptions predict a nonlinear steady-state alignment after passage of the laser pulse, which in the fluid model is interpreted as an anisotropic temperature of the diatomic fluid with respect to motion about the polarization axis.

  16. Nature engineered diatom biosilica as drug delivery systems.

    Science.gov (United States)

    Uthappa, U T; Brahmkhatri, Varsha; Sriram, G; Jung, Ho-Young; Yu, Jingxian; Kurkuri, Nikita; Aminabhavi, Tejraj M; Altalhi, Tariq; Neelgund, Gururaj M; Kurkuri, Mahaveer D

    2018-05-14

    Diatoms, unicellular photosynthetic algae covered with siliceous cell wall, are also called frustule. These are the most potential naturally available materials for the development of cost-effective drug delivery systems because of their excellent biocompatibility, high surface area, low cost and ease of surface modification. Mesoporous silica materials such as MCM-41 and SBA-15 have been extensively used in drug delivery area. Their synthesis is challenging, time consuming, requires toxic chemicals and are energy intensive, making the entire process expensive and non-viable. Therefore, it is necessary to explore alternative materials. Surprisingly, nature has provided some exciting materials called diatoms; biosilica is one such a material that can be potentially used as a drug delivery vehicle. The present review focuses on different types of diatom species used in drug delivery with respect to their structural properties, morphology, purification process and surface functionalization. In this review, recent advances along with their limitations as well as the future scope to develop them as potential drug delivery vehicles are discussed. Copyright © 2018. Published by Elsevier B.V.

  17. Exploring of Agro Waste (Pineapple Leaf, Corn Stalk, and Napier Grass) by Chemical Composition and Morphological Study

    OpenAIRE

    Angzzas Sari Mohd Kassim; Halizah Awang; Ashuvila Mohd Aripin

    2013-01-01

    Malaysia is a country that is a rich source of agricultural waste material. Three different crops were studied here, including pineapple (Ananas comosus) leaf, corn (Zea mays) stalk, and Napier grass (Pennisetum purpureum). These crops are characterized as agricultural waste materials in Malaysia and have a high potential to be used as alternative fibers for the paper making industry. The objective of this work was to analyze the chemical composition of pineapple leaf, corn stalk, and Napier ...

  18. Effect of Preserving the Pituitary Stalk During Resection of Craniopharyngioma in Children on the Diabetes Insipidus and Relapse Rates and Long-Term Outcomes.

    Science.gov (United States)

    Cheng, Jing; Fan, Yanqin; Cen, Bo

    2017-09-01

    The objective of this study was to investigate the effect of preserving an infiltrated pituitary stalk during the resection of craniopharyngioma of pituitary stalk origin on postoperative outcomes and thus provide a theoretical basis for microsurgical treatment and prognosis. We screened the clinical data of all 103 pediatric patients with craniopharyngioma undergoing surgical treatment at our department between January 2006 and January 2013 and conducted a retrospective analysis of 82 patients with craniopharyngioma originating in the pituitary stalk. The patients were followed up from 12 months to 8 years. We analyzed the effect of preserving the pituitary stalk on the early and persistent diabetes insipidus rates, postoperative relapse rate, and mortality. In the total resection group (n = 67), the early and persistent diabetes insipidus rates were significantly lower in the 46 patients (68.7%) with a pituitary stalk than in those whose pituitary stalk was removed (P  0.05). In the subtotal resection group (n = 15), a significant difference was observed in the early and persistent diabetes insipidus rates (P  0.05). For children with craniopharyngioma of pituitary stalk origin, preserving the pituitary stalk has a significant effect on the early and persistent diabetes insipidus rates. When intraoperative exploration showed excessive adhesion between the tumor and pituitary stalk, we opted to preserve the pituitary stalk, which significantly reduced the early and persistent postoperative diabetes insipidus rates, without significantly increasing the relapse or mortality rate.

  19. Stalk yield of sugarcane cultivars under different water regimes by subsurface drip irrigation

    Directory of Open Access Journals (Sweden)

    Aderson S. de Andrade Junior

    Full Text Available ABSTRACT This study aimed to evaluate the stalk yield of ten sugarcane cultivars (RB962962, RB931011, RB931530, RB98710, RB92579, RB867515, RB863129, SP791011, RB72545 and VAT90212 subjected to water deficit, full irrigation and water surplus by subsurface drip irrigation, during three cropping seasons (2011-2014. The experiment was conducted at the Experimental Field of Embrapa Meio-Norte, Teresina, Piauí State, Brazil, in dystrophic Red Yellow Argisol. The cultivars RB962962 (162.3 Mg ha-1 and RB867515 (158.5 Mg ha-1 have better stalk yield compared with other cultivars in all water regimes and cropping seasons.

  20. Adsorption of hexavalent chromium on modified corn stalk using different cross-linking agents

    Science.gov (United States)

    Chen, Suhong; Zhu, Yi; Han, Zhijun; Feng, Gao; Jia, Yuling; Fu, Kaifang; Yue, Qinyan

    2017-12-01

    In this study, four different types of adsorbents modified from corn stalk were synthesized after the reaction with epichlorohydrin, N,N-dimethylformamide, triethylamine and different cross-linking agents. The surface functional groups and thermal stability of modified corn stalk (MCSs) were characterized using FTIR and TG analysis, respectively. The feasibility of using MCSs to remove Cr(VI) were evaluated. Adsorption isotherms were determined and modeled with Langmuir, Freundlich and Temkin equations. The experimental results showed that MCS modified using diethylenetriamine (DETA) had the best modification effect, and the adsorption capacity of Cr(VI) reached as high as 227.27 mg/g at 323 K. Thermodynamic study showed that the Cr(VI) adsorption onto MCSs was endothermic processes. As a result, MCS by using DETA as cross-linking agent has good potential for the removal of Cr(VI) from aqueous solutions.

  1. Mesoporous activated carbon from corn stalk core for lithium ion batteries

    Science.gov (United States)

    Li, Yi; Li, Chun; Qi, Hui; Yu, Kaifeng; Liang, Ce

    2018-04-01

    A novel mesoporous activated carbon (AC) derived from corn stalk core is prepared via a facile and effective method which including the decomposition and carbonization of corn stalk core under an inert gas atmosphere and further activation process with KOH solution. The mesoporous activated carbon (AC) is characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) measurements. These biomass waste derived from activated carbon is proved to be promising anode materials for high specific capacity lithium ion batteries. The activated carbon anode possesses excellent reversible capacity of 504 mAh g-1 after 100 cycles at 0.2C. Compared with the unactivated carbon (UAC), the electrochemical performance of activated carbon is significantly improved due to its mesoporous structure.

  2. Thermogravimetric kinetics of corn stalk pretreated by oleaginous fungi Cunninghamella echinulata.

    Science.gov (United States)

    Wu, Jianguo; Gao, Shi; Wan, Jilin; Zeng, Yelin; Ma, Fuying; Zhang, Xiaoyu

    2011-04-01

    The thermogravimetric and composition of corn stalk pretreated by oleaginous fungi Cunninghamella echinulata had been studied in this paper. Results indicated that pretreatment by oleaginous fungi C. echinulata could decrease the activation energy and make the pyrolysis more efficient and energy-saving. By bio-pretreatment, the contents of elements agreed with the weight loss, sugar content, and oil contents, especially the sulfur content was greatly decreased, greatly eliminating the inventory of gas contamination such as the emission of SOx and making the pyrolysis more environmentally friendly. Therefore, corn stalk with sugar pretreated by oleaginous fungi C. echinulata should be a good pyrolysis material to obtain high quality bio-oil. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Delayed diagnosis of pituitary stalk interruption syndrome with severe recurrent hyponatremia caused by adrenal insufficiency

    Directory of Open Access Journals (Sweden)

    Kyung Mi Jang

    2017-09-01

    Full Text Available Pituitary stalk interruption syndrome (PSIS involves the occurrence of a thin or absent pituitary stalk, hypoplasia of the adenohypophysis, and ectopic neurohypophysis. Diagnosis is confirmed using magnetic resonance imaging. Patients with PSIS have a variable degree of pituitary hormone deficiency and a wide spectrum of clinical manifestations. The clinical course of the disease in our patient is similar to that of a syndrome of inappropriate antidiuretic hormone secretion. This is thought to be caused by failure in the suppression of vasopressin secretion due to hypocortisolism. To the best of our knowledge, there is no case report of a patient with PSIS presenting with hyponatremia as the first symptom in Korean children. Herein, we report a patient with PSIS presenting severe recurrent hyponatremia as the first symptom, during adolescence and explain the pathophysiology of hyponatremia with secondary adrenal insufficiency.

  4. A simple digestion method with a Lefort aqua regia solution for diatom extraction.

    Science.gov (United States)

    Wang, Huipin; Liu, Yan; Zhao, Jian; Hu, Sunlin; Wang, Yuzhong; Liu, Chao; Zhang, Yanji

    2015-01-01

    Presence of diatoms in tissues has been considered as a significant sign of drowning. However, there are limitations in the present extraction methods. We developed a new digestion method using the Lefort aqua regia solution (3:1 nitric acid to hydrochloric acid) for diatom extraction and evaluated the digestive capability, diatom destruction, and diatoms' recovery of this new method. The kidney tissues from rabbit mixed with water rich in diatoms were treated by the Lefort aqua regia digestion method (n = 10) and the conventional acid digestion method (n = 10). The results showed that the digestive capability of Lefort aqua regia digestion method was superior to conventional acid digestion method (p 0.05). The Lefort aqua regia reagent is an improvement over the conventional acid digestion for recovery of diatoms from tissue samples. © 2014 American Academy of Forensic Sciences.

  5. Measurement of the heat of smoldering combustion in straws and stalks by means of simultaneous thermal analysis

    Energy Technology Data Exchange (ETDEWEB)

    He, Fang; Yi, Weiming; Zha, Jianwen [School of Light Industry and Agricultural Engineering, Shandong University of Technology, Zibo, Shandong 255049 (China)

    2009-01-15

    In order to investigate reaction heat of agro-stalks smoldering, wheat straw, corn stalk, cotton stalk, millet straw, sorghum stalk and sweet potato rattan powder were smoldered and pyrolyzed in a simultaneous thermal analyzer (STA). The samples were placed in a platinum crucible (5 mm x 5 mm) with a lid (with a 1 mm hole) on a high-accuracy differential scanning calorimetry-heat capacity (DSC-cp) holder in the furnace of an STA and heated from 303 to 1073 K at a heating rate of 10 K min{sup -1}. Sweeping gas with a flow rate of 25 ml min{sup -1} was air and nitrogen during smoldering and pyrolysis, respectively. Results showed that the heat emission characteristic of the smoldering process differed remarkably from the pyrolysis process. Based on the analysis of the DSC curves, oxidative polymer degradation heat and char oxidation heat were obtained from experimental data. It showed that the oxidative polymer degradation heat of the agro-stalks is more than 6.92 MJ kg{sup -1} consumed matter, higher than that of cellulose paper. And char oxidation heat is around 23 MJ kg{sup -1} consumed matter, similar to that of cellulose paper, but higher than that of cigarette. Total net heat emission of smoldering in STA was also obtained. These data can be used as reference data in analyzing smoldering of agro-stalks under similar conditions. (author)

  6. Size reduction of high- and low-moisture corn stalks by linear knife grid system

    Energy Technology Data Exchange (ETDEWEB)

    Igathinathane, C. [Agricultural and Biological Engineering Department, 130 Creelman Street, Mississippi State University, Mississippi State, Mississippi 39762 (United States); Womac, A.R. [Department of Biosystems Engineering and Soil Science, 2506 E. J. Chapman Drive, The University of Tennessee, Knoxville, Tennessee 37996 (United States); Sokhansanj, S. [Oak Ridge National Laboratory, Environmental Sciences Division, Oak Ridge, P. O. Box 2008, Tennessee 37831 (United States); Narayan, S. [First American Scientific Company, 100 Park Royal South West Vancouver, British Columbia, V7T 1A2 (Canada)

    2009-04-15

    High- and low-moisture corn stalks were tested using a linear knife grid size reduction device developed for first-stage size reduction. The device was used in conjunction with a universal test machine that quantified shearing stress and energy characteristics for forcing a bed of corn stalks through a grid of sharp knives. No published engineering performance data for corn stover with similar devices are available to optimize performance; however, commercial knife grid systems exist for forage size reduction. From the force-displacement data, mean and maximum ultimate shear stresses, cumulative and peak mass-based cutting energies for corn stalks, and mean new surface area-based cutting energies were determined from 4-5 refill runs at two moisture contents (78.8% and 11.3% wet basis), three knife grid spacings (25.4, 50.8, and 101.6 mm), and three bed depths (50.8, 101.6, and 152.4 mm). In general, the results indicated that peak failure load, ultimate shear stress, and cutting energy values varied directly with bed depth and inversely with knife grid spacing. Mean separation analysis established that high- and low-moisture conditions and bed depths {>=} 101.6 mm did not differ significantly (P < 0.05) for ultimate stress and cutting energy values, but knife grid spacing were significantly different. Linear knife grid cutting energy requirements for both moisture conditions of corn stalks were much smaller than reported cutting energy requirements. Ultimate shear stress and cutting energy results of this research should aid the engineering design of commercial scale linear knife gird size reduction equipment for various biomass feedstocks. (author)

  7. Corn stalk as matrix in decomposting toilet for treating urine and feces

    Science.gov (United States)

    Sintawardani, N.; Nilawati, D.; Astuti, J. T.

    2017-03-01

    Bio-Toilet technology (BT) which is appropriate for the habits of Indonesian people has been studied and developed. BT is a dry toilet technology commonly uses ligno-cellulosic waste materials as matrix to facilitate the growth of natural microbes. In aerobic condition, microbes degrade feces and urine. Mineral as the leftover of feces and urine, such as nitrogen (N), phosphorus (P), and potassium (K) remain in the rest of matrix waste. After certain period. matrix can be harvested and used as soil conditioner. BT uses much less water, mobile, and very useful to be applied in areas where water availability is limited. BT type with different capacities, user amounts and mixing systems has been developed using sawdust for matrix. Since corn stalk is categorized as useless and priceless waste, its application in BT is challenging. Performance of BT with corn stalk as matrix to degrade feces and urine of carnivore imitating the human waste was observed. BT M-15 manual mixing type with paddle was filled with chopped corn stalk as much as 45% of total volume. This BT was designed for 15 person as users per day if 80% reactor volume was filled with ligno-cellulosic matrix. It is assumed that 150 g of feces are discharged once per person/day and 1000 mL of urine 6-8 times per day. Start up process was made in the beginning to initialize the needed microbes in the reactor (matrix). The discharge of feces and urine were increased slowly and gradually the users were increased from 1 to 4 users per day. Performance of BT was indicated by the change in the pile that showed by moisture content, temperature and pH. C/N ratio in matrix decreased significantly from 43 to 17. This result showed that the corn stalk could be used as matrix in BT.

  8. Is nectar reabsorption restricted by the stalk cells of floral and extrafloral nectary trichomes?

    Science.gov (United States)

    Cardoso-Gustavson, P; Davis, A R

    2015-01-01

    Reabsorption is a phase of nectar dynamics that occurs concurrently with secretion; it has been described in floral nectaries that exude nectar through stomata or unicellular trichomes, but has not yet been recorded in extrafloral glands. Apparently, nectar reabsorption does not occur in multicellular secretory trichomes (MST) due to the presence of lipophilic impregnations - which resemble Casparian strips - in the anticlinal walls of the stalk cells. It has been assumed that these impregnations restrict solute movement within MST to occur unidirectionally and exclusively by the symplast, thereby preventing nectar reflux toward the underlying nectary tissues. We hypothesised that reabsorption is absent in nectaries possessing MST. The fluorochrome lucifer yellow (LYCH) was applied to standing nectar of two floral and extrafloral glands of distantly related species, and then emission spectra from nectary sections were systematically analysed using confocal microscopy. Passive uptake of LYCH via the stalk cells to the nectary tissues occurred in all MST examined. Moreover, we present evidence of nectar reabsorption in extrafloral nectaries, demonstrating that LYCH passed the stalk cells of MST, although it did not reach the deepest nectary tissues. Identical (control) experiments performed with neutral red (NR) demonstrated no uptake of this stain by actively secreting MST, whereas diffusion of NR did occur in plasmolysed MST of floral nectaries at the post-secretory phase, indicating that nectar reabsorption by MST is governed by stalk cell physiology. Interestingly, non-secretory trichomes failed to reabsorb nectar. The role of various nectary components is discussed in relation to the control of nectar reabsorption by secretory trichomes. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  9. LOFT reactor vessel 290/sup 0/ downcomer stalk instrument penetration flange stress analysis

    Energy Technology Data Exchange (ETDEWEB)

    Finicle, D.P.

    1978-06-06

    The LOFT Reactor Vessel 290/sup 0/ Downcomer Stalk Instrument Penetration Flange Stress Analysis has been completed using normal operational and blowdown loading. A linear elastic analysis was completed using simplified hand analysis techniques. The analysis was in accordance with the 1977 ASME Boiler and Pressure Vessel Code, Section III, for a Class 1 component. Loading included internal pressure, bolt preload, and thermal gradients due to normal operating and blowdown.

  10. Diatoms in acid mine drainage and their role in the formation of iron-rich stromatolites

    Energy Technology Data Exchange (ETDEWEB)

    Brake, S.S.; Hasiotis, S.T.; Dannelly, H.K. [Indiana State University, Terre Haute, IN (United States)

    2004-08-01

    Adverse conditions in the acid mine drainage (AMD) system at the Green Valley mine, Indiana, limit diatom diversity to one species, Nitzschia tubicola. It is present in three distinct microbial consortia: Euglena mutabilis-dominated biofilm, diatom-dominated biofilm, and diatom-exclusive biofilm. E. mutabilis dominates the most extensive biofilm, with lesser numbers of N. tubicola, other eukaryotes, and bacteria. Diatom-dominated biofilm occurs as isolated patches containing N. tubicola with minor fungal hyphae, filamentous algae, E. mutabilis, and bacteria. Diatom-exclusive biofilm is rare, composed entirely of N. tubicola. Diatom distribution is influenced by seasonal and intraseasonal changes in water temperature and chemistry. Diatoms are absent in winter due to cool water temperatures. In summer, isolated patchy communities are present due to warmer water temperatures. In 2001, the diatom community expanded its distribution following a major rainfall that temporarily diluted the effluent, creating hospitable conditions for diatom growth. After several weeks when effluent returned to preexisting conditions, the diatom biofilm retreated to isolated patches, and E. mutabilis biofilm flourished. Iron-rich stromatolites underlie the biofilms and consist of distinct laminae, recording spatial and temporal oscillations in physicochemical conditions and microbial activity. The stromatolites are composed of thin, wavy laminae with partially decayed E. mutabilis biofilm, representing microbial activity and iron precipitation under normal AMD conditions. Alternating with the wavy layers are thicker, porous, spongelike laminae composed of iron precipitated on and incorporated into radiating colonies of diatoms. These layers indicate episodic changes in water chemistry, allowing diatoms to temporarily dominate the system.

  11. Studies on fouling diatoms from the Zuari Estuary, Goa (west coast of India)

    Digital Repository Service at National Institute of Oceanography (India)

    Redekar, P.D.; Wagh, A.B.

    from offshore waters of Bombay High area using aluminium panels and recorded 58 species of fouling diatoms Of these Navicula Coscinodiscus Rhizosolenia and Chaetoceros were found to be common The dominance of Centrales over Pennales in water column... on fouling diatoms from the Zuari estuary, Goa (West coast of India) 119 Pangu (1993) used mild steel, aluminium, fiberglass and glass test panels and the immersion period of panels was long (1 month to 11 months) The fouling diatoms from Waghotana...

  12. Thermal Decomposition Properties of Materials from Different Parts of Corn Stalk

    Directory of Open Access Journals (Sweden)

    Siwei Huang

    2015-02-01

    Full Text Available To help better utilize corn stalk (CS, pyrolysis behavior of materials from different parts of the CS including corn stalk without pith, corn root, and corn leaf were analyzed using thermogravimetric analysis (TGA at heating rates of 5, 10, 20, and 25 °C/min. The apparent activation energies determined by the Friedman method for corn stalk without pith, corn root, and corn leaf were in the range of 26.4 to 103.6 kJ/mol, 37.6 to 69.5 kJ/mol, and 35.0 to 103.9 kJ/mol, respectively, depending on the conversion. The main thermal decomposition occurred within a temperature range of 200 to 350 °C (±10 °C. Most of the volatile materials decomposed at less than a 0.8 conversion rate. At greater than a 0.8 conversion rate, the remaining material was mainly char, and the decomposition of char proceeded at higher conversion rates. Different pyrolysis characteristics in the CS indicated that different treatments should be chosen according to different parts for achieving the optimum conversion rate in practical applications.

  13. Diatom Attachment at Aquatic Interfaces: Molecular Interactions, Mechanisms, and Physiology of Adhesion

    National Research Council Canada - National Science Library

    Gretz, Michael

    1997-01-01

    .... those more hydrophobic and that bacterial 'preconditioning' has variable effects on adhesion; (3) developed methodology for mass culture of fouling diatoms and isolation of adhesive components; (4...

  14. Comparison between sedimentary and living diatoms in Lago Maggiore (N. Italy: implications of using transfer functions

    Directory of Open Access Journals (Sweden)

    Simona MUSAZZI

    2001-02-01

    Full Text Available We compared the recent history of living planktonic diatom assemblages in Lago Maggiore with the remains found in the topmost section of 14 sediment cores taken from the lake. Sediment samples showed a marked domination of planktonic taxa, but a significant proportion of benthic taxa was found in cores collected close to river mouths. Between-core variability in diatom assemblage and in diatom-inferred total phosphorus concentration was also estimated. The implications of our results for calibration data sets relating environmental variables to diatom assemblages are also discussed.

  15. Crystal Structure of the 23S rRNA Fragment Specific to r-Protein L1 and Designed Model of the Ribosomal L1 Stalk from Haloarcula marismortui

    Directory of Open Access Journals (Sweden)

    Azat Gabdulkhakov

    2017-02-01

    Full Text Available The crystal structure of the 92-nucleotide L1-specific fragment of 23S rRNA from Haloarcula marismortui (Hma has been determined at 3.3 Å resolution. Similar to the corresponding bacterial rRNA fragments, this structure contains joined helix 76-77 topped by an approximately globular structure formed by the residual part of the L1 stalk rRNA. The position of HmaL1 relative to the rRNA was found by its docking to the rRNA fragment using the L1-rRNA complex from Thermus thermophilus as a guide model. In spite of the anomalous negative charge of the halophilic archaeal protein, the conformation of the HmaL1-rRNA interface appeared to be very close to that observed in all known L1-rRNA complexes. The designed structure of the L1 stalk was incorporated into the H. marismortui 50S ribosomal subunit. Comparison of relative positions of L1 stalks in 50S subunits from H. marismortui and T. thermophilus made it possible to reveal the site of inflection of rRNA during the ribosome function.

  16. Recovery from diabetes insipidus and preservation of thyroid function after craniopharyngioma removal and pituitary stalk sectioning.

    Science.gov (United States)

    Ogawa, Yoshikazu; Niizuma, Kuniyasu; Tominaga, Teiji

    2017-11-01

    Craniopharyngioma is a slow-growing tumor, but long-term tumor control with maintenance of quality of life is sometimes very difficult to achieve, and hypothalamic disturbance should be strictly avoided in the treatment. However, management of the pituitary gland and/or pituitary stalk varies among surgeons and institutions. This retrospective review identified 44 patients, 24 males and 20 females with craniopharyngiomas who were initially treated by surgery through the extended transsphenoidal approach with pituitary stalk sectioning at a single institute. If the tumor bed involved the posterior lobe of the pituitary gland, pituitary stalk, anterior and/or mid portion of the third ventricle floor, these structures were removed en-bloc together with the tumor. The closest attention was paid to preserve fine arteries running along the surface of optic chiasm and the lateral walls of the third ventricle. Surgical outcome and changes in postoperative endocrinological status were investigated. Gross total removal was achieved in 40 of 44 patients (91%), and all patients could discharge without autonomic and/or thermal disturbances. Tumor remnants were identified with tight adhesion to the perforating arteries in 2 cases, tight adhesion to mammillary bodies in 1, and optic chiasm in 1. Administration of anti-diuretic hormone could be discontinued in 23 of 44 patients (52.3%) with improved diabetes insipidus (DI), although no patient could discontinue glucocorticoid administration. Preservation of thyroid function was achieved in another 23 of 44 patients (52.3%), and recovery from DI was correlated with preservation of thyroid function (p=0.016). Pituitary dysfunction is partially reversible even with pituitary stalk sectioning. Regrowth of tumor in the anterior and/or mid portion of the third ventricle floor including pituitary stalk can possibly be prevented by aggressive tumor removal, and co-achievement of long-term tumor control with maintenance of quality of life

  17. Innovative Prototype for Separate Harvesting of Cynara Cardunculus Achenes and Stalks

    Energy Technology Data Exchange (ETDEWEB)

    Pari, L.; Fedrizzi, M.; Pansini, L. (Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Unita di Ricerca per l' Ingegneria Agraria, Monterotondo, RM (Italy))

    2008-10-15

    The CRA-ING took part to the Cynara cardunculus harvesting tests organized in Spain in 2007, where UPM has experimental cultivations in the Instituto Madrileno de Investigacion y Desarrollo Rural, Agrario y Alimentario (IMIDRA) de la Consejeria de Economia y Innovacion Tecnologica de la Comunidad de Madrid in El Encin, near Alcala De Henarez. The harvesting tests were carried out in week 33 (August 13th-17th); the cultivation was found part in good condition of maturity, part still not ready for harvesting. The test was carried out on the dried part of the crops. The tests aimed at evaluating a new mechanical equipment (head) working connected to a selfpropelled combine for separated harvesting of the different fractions obtainable by the cultivation assigned to different transformation: oil extraction from seeds and energy production from epigeous biomass combustion. During the tests carried out in 2006 in Portugal and Spain, it was observed how a combine harvester with a maize head was able to separate the seed with good accuracy. Likewise the difficulty of collecting the lignocellulosic fraction after its passage was highlighted. A combine with a wheat head could cut the stalk in an appropriate height range, but could not separate the head from the stalk. A sunflower head cut the capitula, but not the stalk. The project concept, supplied to a Firm that already builds heads for maize, wheat, sunflowers, soybean and so on, included the upper devices of a maize head and a classic wheat head (without the paddle wheel) in the lower part, to obtain capitula detachment and effective threshing and, at the same time, the stalk cut. Some modifications were specified to allow the cut of the stalk next to the ground and its successive tier in the space between the front wheels, where the discharge system of the threshing device would then provide to drop the remains of the capitula threshing. The basic concept of the machine, to separate and thresh the capitula and to drop

  18. Neuraminidase stalk length and additional glycosylation of the hemagglutinin influence the virulence of influenza H5N1 viruses for mice.

    Science.gov (United States)

    Matsuoka, Yumiko; Swayne, David E; Thomas, Colleen; Rameix-Welti, Marie-Anne; Naffakh, Nadia; Warnes, Christine; Altholtz, Melanie; Donis, Ruben; Subbarao, Kanta

    2009-05-01

    Following circulation of avian influenza H5 and H7 viruses in poultry, the hemagglutinin (HA) can acquire additional glycosylation sites, and the neuraminidase (NA) stalk becomes shorter. We investigated whether these features play a role in the pathogenesis of infection in mammalian hosts. From 1996 to 2007, H5N1 viruses with a short NA stalk have become widespread in several avian species. Compared to viruses with a long-stalk NA, viruses with a short-stalk NA showed a decreased capacity to elute from red blood cells and an increased virulence in mice, but not in chickens. The presence of additional HA glycosylation sites had less of an effect on virulence than did NA stalk length. The short-stalk NA of H5N1 viruses circulating in Asia may contribute to virulence in humans.

  19. Neuraminidase Stalk Length and Additional Glycosylation of the Hemagglutinin Influence the Virulence of Influenza H5N1 Viruses for Mice▿

    Science.gov (United States)

    Matsuoka, Yumiko; Swayne, David E.; Thomas, Colleen; Rameix-Welti, Marie-Anne; Naffakh, Nadia; Warnes, Christine; Altholtz, Melanie; Donis, Ruben; Subbarao, Kanta

    2009-01-01

    Following circulation of avian influenza H5 and H7 viruses in poultry, the hemagglutinin (HA) can acquire additional glycosylation sites, and the neuraminidase (NA) stalk becomes shorter. We investigated whether these features play a role in the pathogenesis of infection in mammalian hosts. From 1996 to 2007, H5N1 viruses with a short NA stalk have become widespread in several avian species. Compared to viruses with a long-stalk NA, viruses with a short-stalk NA showed a decreased capacity to elute from red blood cells and an increased virulence in mice, but not in chickens. The presence of additional HA glycosylation sites had less of an effect on virulence than did NA stalk length. The short-stalk NA of H5N1 viruses circulating in Asia may contribute to virulence in humans. PMID:19225004

  20. Comparative study of wet and dry torrefaction of corn stalk and the effect on biomass pyrolysis polygeneration.

    Science.gov (United States)

    Wang, Xianhua; Wu, Jing; Chen, Yingquan; Pattiya, Adisak; Yang, Haiping; Chen, Hanping

    2018-06-01

    Wet torrefaction (WT) possesses some advantages over dry torrefaction (DT). In this study, a comparative analysis of torrefied corn stalk from WT and DT was conducted along with an investigation of their pyrolysis properties under optimal conditions for biomass pyrolysis polygeneration. Compared with DT, WT removed 98% of the ash and retained twice the amount of hydrogen. The impacts of DT and WT on the biomass macromolecular structure was also found to be different using two-dimensional perturbation correlation infrared spectroscopy (2D-PCIS). WT preserved the active hydroxyl groups and rearranged the macromolecule structure to allow cellulose to be more ordered, while DT removed these active hydroxyl groups and formed inter-crosslinking structures in macromolecules. Correspondingly, the bio-char yield after WT was lower than DT but the bio-char quality was upgraded due to high ash removal. Furthermore, higher bio-oil yield, higher sugar content, and higher H 2 generation, were obtained after WT. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Direct fit of spectroscopic data of diatomic molecules by using genetic algorithms: II. The ground state of RbCs

    International Nuclear Information System (INIS)

    Almeida, Marcos M; Prudente, Frederico V; Fellows, Carlos E; Marques, Jorge M C; Pereira, Francisco B

    2011-01-01

    We extend our previous methodology based on genetic algorithms (Marques et al 2008 J. Phys. B: At. Mol. Opt. Phys. 41 085103) to carry out the challenging fit of the RbCs potential curve to spectroscopic data. Specifically, we have fitted an analytic functional form to line positions of the high-resolution Fourier transform spectrum of RbCs obtained by a laser-induced fluorescence technique. The results for the ground electronic state of RbCs show that the present method provides an efficient way to obtain diatomic potentials with great accuracy.

  2. Automated Diatom Analysis Applied to Traditional Light Microscopy: A Proof-of-Concept Study

    Science.gov (United States)

    Little, Z. H. L.; Bishop, I.; Spaulding, S. A.; Nelson, H.; Mahoney, C.

    2017-12-01

    Diatom identification and enumeration by high resolution light microscopy is required for many areas of research and water quality assessment. Such analyses, however, are both expertise and labor-intensive. These challenges motivate the need for an automated process to efficiently and accurately identify and enumerate diatoms. Improvements in particle analysis software have increased the likelihood that diatom enumeration can be automated. VisualSpreadsheet software provides a possible solution for automated particle analysis of high-resolution light microscope diatom images. We applied the software, independent of its complementary FlowCam hardware, to automated analysis of light microscope images containing diatoms. Through numerous trials, we arrived at threshold settings to correctly segment 67% of the total possible diatom valves and fragments from broad fields of view. (183 light microscope images were examined containing 255 diatom particles. Of the 255 diatom particles present, 216 diatoms valves and fragments of valves were processed, with 170 properly analyzed and focused upon by the software). Manual analysis of the images yielded 255 particles in 400 seconds, whereas the software yielded a total of 216 particles in 68 seconds, thus highlighting that the software has an approximate five-fold efficiency advantage in particle analysis time. As in past efforts, incomplete or incorrect recognition was found for images with multiple valves in contact or valves with little contrast. The software has potential to be an effective tool in assisting taxonomists with diatom enumeration by completing a large portion of analyses. Benefits and limitations of the approach are presented to allow for development of future work in image analysis and automated enumeration of traditional light microscope images containing diatoms.

  3. All New Faces of Diatoms: Potential Source of Nanomaterials and Beyond

    Directory of Open Access Journals (Sweden)

    Meerambika Mishra

    2017-07-01

    Full Text Available Nature’s silicon marvel, the diatoms have lately astounded the scientific community with its intricate designs and lasting durability. Diatoms are a major group of phytoplanktons involved in the biogeochemical cycling of silica and are virtually inherent in every environment ranging from water to ice to soil. The usage of diatoms has proved prudently cost effective and its handling neither requires costly materials nor sophisticated instruments. Diatoms can easily be acquired from the environment, their culture requires ambient condition and does not involve any costly media or expensive instruments, besides, they can be transported in small quantities and proliferated to a desirable confluence from that scratch, thus are excellent cost effective industrial raw material. Naturally occurring diatom frustules are a source of nanomaterials. Their silica bio-shells have raised curiosity among nanotechnologists who hope that diatoms will facilitate tailoring minuscule structures which are beyond the capabilities of material scientists. Additionally, there is a colossal diversity in the dimensions of diatoms as the frustule shape differs from species to species; this provides a scope for the choice of a particular species of diatom to be tailored to an exacting requisite, thus paving the way to create desired three dimensional nanocomposites. The present article explores the use of diatoms in various arenas of science, may it be in nanotechnology, biotechnology, environmental science, biophysics or biochemistry and summarizes facets of diatom biology under one umbrella. Special emphasis has been given to biosilicification, biomineralization and use of diatoms as nanomaterials’, drug delivery vehicles, optical and immune-biosensors, filters, immunodiagnostics, aquaculture feeds, lab-on-a-chip, metabolites, and biofuels.

  4. Diatom species abundance and morphologically-based dissolution proxies in coastal Southern Ocean assemblages

    Science.gov (United States)

    Warnock, Jonathan P.; Scherer, Reed P.

    2015-07-01

    Taphonomic processes alter diatom assemblages in sediments, thus potentially negatively impacting paleoclimate records at various rates across space, time, and taxa. However, quantitative taphonomic data is rarely included in diatom-based paleoenvironmental reconstructions and no objective standard exists for comparing diatom dissolution in sediments recovered from marine depositional settings, including the Southern Ocean's opal belt. Furthermore, identifying changes to diatom dissolution through time can provide insight into the efficiency of both upper water column nutrient recycling and the biological pump. This is significant in that reactive metal proxies (e.g. Al, Ti) in the sediments only account for post-depositional dissolution, not the water column where the majority of dissolution occurs. In order to assess the range of variability of responses to dissolution in a typical Southern Ocean diatom community and provide a quantitative guideline for assessing taphonomic variability in diatoms recovered from core material, a sediment trap sample was subjected to controlled, serial dissolution. By evaluating dissolution-induced changes to diatom species' relative abundance, three preservational categories of diatoms have been identified: gracile, intermediate, and robust. The relative abundances of these categories can be used to establish a preservation grade for diatom assemblages. However, changes to the relative abundances of diatom species in sediment samples may reflect taphonomic or ecological factors. In order to address this complication, relative abundance changes have been tied to dissolution-induced morphological change to the areolae of Fragilariopsis curta, a significant sea-ice indicator in Southern Ocean sediments. This correlation allows differentiation between gracile species loss to dissolution versus ecological factors or sediment winnowing. These results mirror a similar morphological dissolution index from a parallel study utilizing

  5. Joint approach based on clinical and imaging features to distinguish non-neoplastic from neoplastic pituitary stalk lesions.

    Directory of Open Access Journals (Sweden)

    Ji Ye Lee

    Full Text Available Distinguishing non-neoplastic pituitary stalk lesions (non-NPSLs from neoplastic pituitary stalk lesions (NPSLs is a major concern in guiding treatment for a thickened pituitary stalk. Our study aimed to aid provide preoperative diagnostic assistance by combining clinical and magnetic resonance imaging (MRI findings to distinguish non-NPSLs from NPSLs.We recruited 158 patients with thickened pituitary stalk lesions visible on MRI. Laboratory findings included hypopituitarism, diabetes insipidus (DI, and hyperprolactinemia. MR images were assessed for anterior-posterior thickness (mm, diffuse pituitary stalk thickening, cystic changes, a high T1 signal, and glandular or extrasellar involvement. A diagnostic model was developed using a recursive partitioning logistic regression analysis. The model was validated in an independent dataset comprising 63 patients, and its diagnostic performance was compared with that of the original radiological reports.A univariate analysis found significant associations of DI (P = 0.006, absence of extrasellar involvement (P = 0.002, and lower stalk thickness (P = 0.031 with non-NPSLs. A diagnostic model was created using the following parameters (in order of priority: 1 lack of extrasellar involvement, 2 stalk thickness < 5.3 mm, and 3 presence of DI. The diagnostic performance (area under the curve; AUC of this model in the independent set was 0.813, representing a significant improvement over the original radiological reports (AUC: 0.713, P = 0.029.The joint diagnostic approach based on clinical and imaging-based factors robustly distinguished non-NPSLs from NPSLs. This approach could guide treatment strategies and prevent unnecessary surgery in patients with non-NPSL.

  6. Diatom Communities and Metrics as Indicators of Urbanization Effects on Streams and Potential Moderation by Landscape Green Infrastructure

    Science.gov (United States)

    Diatoms are very useful and important indicators of anthropogenic impacts on streams because they are the foundation of primary production and are responsive to nutrients, conductivity, and habitat conditions. We characterized relationships of diatom assemblages with water chemis...

  7. Growth inhibition of fouling bacteria and diatoms by extract of terrestrial plant, @iDerris scandens@@ (Dicotyledonae:Leguminocae)

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Sonak, S.; Garg, A.

    Methanol extract of terrestrial plant, @iDerris scandens@@ Benth, was found to inhibit growth of four diatoms and 7 bacterial species of fouling community. The concentrations required to bring about 100% inhibition of growth of the diatoms ranged...

  8. Growth inhibition of fouling bacteria and diatoms by extract of terrestrial plant, Derris scandens (Dicotyledonae:Leguminocae)

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Sonak, S.; Garg, A.

    Methanol extract of terrestrial plant, Derris scandens Benth, was found to inhibit growth of four diatoms and 7 bacterial species of fouling community. The concentrations required to bring about 100% inhibition of growth of the diatoms ranged...

  9. Action Spectrum of Photoinhibition in the Diatom Phaeodactylum tricornutum.

    Science.gov (United States)

    Havurinne, Vesa; Tyystjärvi, Esa

    2017-12-01

    Light-dependent electron transfer is necessary for photosynthesis, but light also damages PSII. Light-induced damage to PSII is called photoinhibition, and the damaging reactions of photoinhibition are still under debate. Diatoms possess an exotic combination of light-harvesting pigments, Chls a/c and fucoxanthin, making them an interesting platform for studying the photoreceptors of photoinhibition. We first confirmed the direct proportionality of photoinhibition to the photon flux density of incident light in the diatom Phaeodactylum tricornutum. Phaeodactylum is known for its efficient non-photochemical quenching, and the effect of this photoprotective mechanism on photoinhibition was tested. Photoinhibition proceeded essentially at the same rate in blue-light-grown Phaeodactylum cells that are capable of non-photochemical quenching and in red-light-grown, non-photochemical quenching-deficient cells. To obtain more insight into how the pigment composition of diatoms affects photoinhibition, we measured the action spectrum of photoinhibition in Phaeodactylum. In visible light, the action spectrum resembled the absorption spectrum of Phaeodactylum, and UV radiation caused much more photoinhibition than visible light. Comparison of the action spectrum of photoinhibition with the absorption spectrum and the excitation spectrum of 77 K PSII fluorescence emission confirmed that photosynthetic pigments are involved in photoinhibition, but the photoinhibitory efficiency of red light is weak, suggesting that the role of light-harvesting pigments as light receptors of photoinhibition is secondary. Finally, we compared photoinhibition in Phaeodactylum with that in other photosynthetic organisms, and our data indicate that the PSII reaction centers of Phaeodactylum are not particularly well protected against the primary damage of photoinhibition. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights

  10. Optimizing CRISPR/Cas9 for the Diatom Phaeodactylum tricornutum

    Directory of Open Access Journals (Sweden)

    Daniel Stukenberg

    2018-06-01

    Full Text Available CRISPR/Cas9 is a powerful tool for genome editing. We constructed an easy-to-handle expression vector for application in the model organism Phaeodactylum tricornutum and tested its capabilities in order to apply CRISPR/Cas9 technology for our purpose. In our experiments, we targeted two different genes, screened for mutations and analyzed mutated diatoms in a three-step process. In the end, we identified cells, showing either monoallelic or homo-biallelic targeted mutations. Thus, we confirm that application of the CRISPR/Cas9 system for P. tricornutum is very promising, although, as discussed, overlooked pitfalls have to be considered.

  11. Seasonal effects of cadmium accumulation in periphytic diatom communities of freshwater biofilms

    International Nuclear Information System (INIS)

    Thi Thuy Duong; Morin, Soizic; Herlory, Olivier; Feurtet-Mazel, Agnes; Coste, Michel; Boudou, Alain

    2008-01-01

    The relationships between diatom species and cadmium (Cd) accumulated in biofilms of the Riou-Mort River (SW, France) were studied in July 2004 and March 2005. Biofilms were sampled from artificial substrates immersed along a metallic pollution gradient during 20 days. Dynamics of diatom communities and cadmium accumulation were followed by collecting samples after 4, 7, 14 and 20 days of biofilm colonization. Cd accumulation in biofilms during experiment was significantly higher in Cd polluted station (Joanis) than in reference station (Firmi) for both seasons. Periphytic diatom composition varied between sites and seasons. At Firmi station, seasonal dynamics of diatom communities were stable with the dominance of Cyclotella meneghiniana and Melosira varians in July and Surirellabrebissonnii and Navicula gregaria in March. At Joanis station, diatom communities mainly responded to high levels of metal by a high proportion of small, adnate species. Positive correlations between Eolimna minima, Nitzschia palea, Encyonema minutum, Surirella angusta, and Gomphonema parvulum and cadmium accumulation were observed, indicating that these species are tolerant to high levels of cadmium. On the other hand, negative correlations of C. meneghiniana, N. gregaria, Navicula lanceolata, M. varians and Nitzschia dissipata with cadmium qualify them as sensitive diatom species. Periphytic diatom composition through the presence of specific species highlight metal tolerant indicator diatom groups which will be meaningful for biomonitoring pollution in natural aquatic systems

  12. The influence of land use on water quality and diatom community ...

    African Journals Online (AJOL)

    Epilithic diatom communities offer a holistic and integrated approach for assessing water quality as they remain in one place for a number of months and reflect an ecological memory of water quality over a period of time. The objective of this study is to use diatom assemblages to distinguish between particular land types ...

  13. Rotation-vibrational spectra of diatomic molecules and nuclei with Davidson interactions

    CERN Document Server

    Rowe, D J

    1998-01-01

    Complete rotation-vibrational spectra and electromagnetic transition rates are obtained for Hamiltonians of diatomic molecules and nuclei with Davidson interactions. Analytical results are derived by dynamical symmetry methods for diatomic molecules and a liquid-drop model of the nucleus. Numerical solutions are obtained for a many-particle nucleus with quadrupole Davidson interactions within the framework of the microscopic symplectic model. (author)

  14. Influence of land-use patterns on benthic diatom communities and ...

    African Journals Online (AJOL)

    The objective of this study was to determine the effects of land-use patterns on both diatom community composition and water quality in tropical streams during the dry season. Benthic diatom collections and water quality sampling were done 4 times at 10 sites. A suite of environmental variables that varied with human ...

  15. A stress surveillance system based on calcium and nitric oxide in marine diatoms

    NARCIS (Netherlands)

    Vardi, A.; Formiggini, F.; Casotti, R.; De Martino, A.; Ribalet, F.; Miralto, A.; Bowler, C.

    2006-01-01

    Diatoms are an important group of eukaryotic phytoplankton, responsible for about 20% of global primary productivity. Study of the functional role of chemical signaling within phytoplankton assemblages is still in its infancy although recent reports in diatoms suggest the existence of chemical-based

  16. A stress surveillance system based on calcium and nitric oxide in marine diatoms.

    NARCIS (Netherlands)

    Vardi, A.; Formiggini, F.; Casotti, R.; De Martino, A.; Ribalet, F.; Miralto, A.; Bowler, C.

    2006-01-01

    Diatoms are an important group of eukaryotic phytoplankton, responsible for about 20% of global primary productivity. Study of the functional role of chemical signaling within phytoplankton assemblages is still in its infancy although recent reports in diatoms suggest the existence of chemical-based

  17. Contribution to the Study of the flora diatomic Nahr Yahfufah (Lebanon)

    International Nuclear Information System (INIS)

    SLIM, K.; ALOUF, N.

    1984-01-01

    Contribution to the study of Diatomic flora on Nahr Yahfufah Lebanon. From October 1980 to June 1982 a hydrobiologic study has taken place on the river of Yahfufah situated to the west of anti Lebanon. From the diatomic population 52 species and varieties were designated. Further more the physico-chemical parameters were followed and studied. (author).

  18. Impact of marine influence and cultivation on the diatom flora of ...

    African Journals Online (AJOL)

    During a limnological and palaeolimnological study of the western part of the Great Coast of Senegal, an analysis of diatoms was carried out in Thiaroye Pond in the suburbs of Dakar. Current diatom flora in the water and on floating plants, and subfossil flora in two cores were sampled in 1996 and 2003. A total of 104 ...

  19. Seasonal effects of cadmium accumulation in periphytic diatom communities of freshwater biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Thi Thuy Duong [Institute of Environmental Technology, Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi (Viet Nam); Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)], E-mail: duongthuy0712@yahoo.com; Morin, Soizic [Cemagref, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex (France); Herlory, Olivier [Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France); Feurtet-Mazel, Agnes [Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)], E-mail: a.feurtet-mazel@epoc.u-bordeaux1.fr; Coste, Michel [Cemagref, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex (France); Boudou, Alain [Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)

    2008-10-20

    The relationships between diatom species and cadmium (Cd) accumulated in biofilms of the Riou-Mort River (SW, France) were studied in July 2004 and March 2005. Biofilms were sampled from artificial substrates immersed along a metallic pollution gradient during 20 days. Dynamics of diatom communities and cadmium accumulation were followed by collecting samples after 4, 7, 14 and 20 days of biofilm colonization. Cd accumulation in biofilms during experiment was significantly higher in Cd polluted station (Joanis) than in reference station (Firmi) for both seasons. Periphytic diatom composition varied between sites and seasons. At Firmi station, seasonal dynamics of diatom communities were stable with the dominance of Cyclotella meneghiniana and Melosira varians in July and Surirellabrebissonnii and Navicula gregaria in March. At Joanis station, diatom communities mainly responded to high levels of metal by a high proportion of small, adnate species. Positive correlations between Eolimna minima, Nitzschia palea, Encyonema minutum, Surirella angusta, and Gomphonema parvulum and cadmium accumulation were observed, indicating that these species are tolerant to high levels of cadmium. On the other hand, negative correlations of C. meneghiniana, N. gregaria, Navicula lanceolata, M. varians and Nitzschia dissipata with cadmium qualify them as sensitive diatom species. Periphytic diatom composition through the presence of specific species highlight metal tolerant indicator diatom groups which will be meaningful for biomonitoring pollution in natural aquatic systems.

  20. Paleoceanographic, and paleoclimatic constraints on the global Eocene diatom and silicoflagellate record

    Science.gov (United States)

    Barron, John A.; Stickley, Catherine E.; Bukry, David

    2015-01-01

    Eocene diatom and silicoflagellate biostratigraphy are summarized and correlated with the most recent geologic time scale as well as with the global oxygen isotope and eustatic sea level curves. The global distribution of Eocene diatom/silicoflagellate-bearing sediments varies considerably, reflecting changing oceanic gateways and paleoceanography with changing patterns that are punctuated by four major depositional events.

  1. An integrated analysis of molecular acclimation to high light in the marine diatom Phaeodactylum tricornutum

    DEFF Research Database (Denmark)

    Nymark, Marianne; Valle, Kristin C; Brembu, Tore

    2009-01-01

    Photosynthetic diatoms are exposed to rapid and unpredictable changes in irradiance and spectral quality, and must be able to acclimate their light harvesting systems to varying light conditions. Molecular mechanisms behind light acclimation in diatoms are largely unknown. We set out to investiga...

  2. Diatoms as water quality indicators in the upper reaches of the Great ...

    African Journals Online (AJOL)

    All index scores showed the Great Fish River to be impacted, and showed significant correlations of diatom species abundance with pH, NO3-N, electrical conductivity, NH4-N and CaCO3. Analysis revealed EC and NO3-N as the main environmental drivers affecting diatom commnity composition, followed by pH and ...

  3. Fossil diatoms imply common cometary origin of space-dust and the Polonnaruwa meteorite

    Science.gov (United States)

    Miyake, N.; Wallis, M. K.; Wickramasinghe, N. C.

    2013-09-01

    IDPs collected in 2001 at 40km altitude by cryosamplers studied via scanning electron microscopy and EDX were found to contain siliceous fibres and whiskers, some isolated but often embedded in a mineral matrix. The newly-arrived Polonnaruwa meteorite gives strong evidence for the hypothesis that they are fragments of diatoms agglomerating on solar system icy bodies. Diatom frustules and even whole diatom skeletons are identifiable within the meteorite. Specimens of a siliceous exoskeleton with multiple spines/whiskers have also been found, thought to be freshwater diatoms. As diatoms are dependent on a source of nitrogenous organics, the siliceous whiskers within IDPs would be an indicator of a photosynthesizing ecosystem, probably on a comet.

  4. Growth of fouling diatoms from the Zuari estuary, Goa (west coast of India) under different salinities in the laboratory

    Digital Repository Service at National Institute of Oceanography (India)

    Redekar, P.D.; Wagh, A.B.

    Diatoms take part in the initial process of fouling i.e. primary film formation. In order to understand the growth of the diatoms under different salinity conditions in the laboratory, this work was undertaken. Fouling diatoms on glass slides were...

  5. Pituitary stalk interruption syndrome in Chinese people: clinical characteristic analysis of 55 cases.

    Directory of Open Access Journals (Sweden)

    Qinghua Guo

    Full Text Available OBJECTIVE: Pituitary stalk interruption syndrome (PSIS is characterized by the absence of pituitary stalk, pituitary hypoplasia, and ectopic posterior pituitary. Due to the rarity of PSIS, clinical data are limited, especially in Chinese people. Herein, we analyzed the clinical characteristics of patients diagnosed with PSIS from our center over 10 years. PATIENTS AND METHODS: We retrospectively analyzed the clinical manifestations and laboratory and MRI findings in 55 patients with PSIS. RESULTS: Of the 55 patients with PSIS, 48 (87.3% were male. The average age was 19.7±6.7 years and there was no familial case. A history of breech delivery was documented in 40 of 45 patients (88.9% and 19 of 55 patients (34.5% had a history of dystocia. Short stature was found in 47 of 55 patients (85.5% and bone age delayed 7.26±5.37 years. Secondary sex characteristics were poor or undeveloped in most patients. The prevalence of deficiencies in growth hormone, gonadotropins, corticotropin, and thyrotropin were 100%, 95.8%, 81.8%, 76.3%, respectively. Hyperprolactinemia was found in 36.4% of patients. Three or more pituitary hormone deficiencies were found in 92.7% of the patients. All patients had normal posterior pituitary function and absent pituitary stalk on imaging. The average height of anterior pituitary was 28 mm, documented anterior pituitary hypoplasia. Midline abnormalities were presented in 9.1% of patients. CONCLUSIONS: The clinical features of our Chinese PSIS patients seem to be different from other reported patients in regarding to the higher degree of hypopituitarism and lower prevalence of midline defects. In addition, our patients were older at the time of case detection and the bone age was markedly delayed. We also had no cases of familial PSIS.

  6. Ribosomal Stalk Protein Silencing Partially Corrects the ΔF508-CFTR Functional Expression Defect.

    Directory of Open Access Journals (Sweden)

    Guido Veit

    2016-05-01

    Full Text Available The most common cystic fibrosis (CF causing mutation, deletion of phenylalanine 508 (ΔF508 or Phe508del, results in functional expression defect of the CF transmembrane conductance regulator (CFTR at the apical plasma membrane (PM of secretory epithelia, which is attributed to the degradation of the misfolded channel at the endoplasmic reticulum (ER. Deletion of phenylalanine 670 (ΔF670 in the yeast oligomycin resistance 1 gene (YOR1, an ABC transporter of Saccharomyces cerevisiae phenocopies the ΔF508-CFTR folding and trafficking defects. Genome-wide phenotypic (phenomic analysis of the Yor1-ΔF670 biogenesis identified several modifier genes of mRNA processing and translation, which conferred oligomycin resistance to yeast. Silencing of orthologues of these candidate genes enhanced the ΔF508-CFTR functional expression at the apical PM in human CF bronchial epithelia. Although knockdown of RPL12, a component of the ribosomal stalk, attenuated the translational elongation rate, it increased the folding efficiency as well as the conformational stability of the ΔF508-CFTR, manifesting in 3-fold augmented PM density and function of the mutant. Combination of RPL12 knockdown with the corrector drug, VX-809 (lumacaftor restored the mutant function to ~50% of the wild-type channel in primary CFTRΔF508/ΔF508 human bronchial epithelia. These results and the observation that silencing of other ribosomal stalk proteins partially rescue the loss-of-function phenotype of ΔF508-CFTR suggest that the ribosomal stalk modulates the folding efficiency of the mutant and is a potential therapeutic target for correction of the ΔF508-CFTR folding defect.

  7. Digenic Inheritance of PROKR2 and WDR11 Mutations in Pituitary Stalk Interruption Syndrome.

    Science.gov (United States)

    McCormack, Shana E; Li, Dong; Kim, Yeon Joo; Lee, Ji Young; Kim, Soo-Hyun; Rapaport, Robert; Levine, Michael A

    2017-07-01

    Pituitary stalk interruption syndrome (PSIS, ORPHA95496) is a congenital defect of the pituitary gland characterized by the triad of a very thin/interrupted pituitary stalk, an ectopic (or absent) posterior pituitary gland, and hypoplasia or aplasia of the anterior pituitary gland. Complex genetic patterns of inheritance of this disorder are increasingly recognized. The objective of this study was to identify a genetic cause of PSIS in an affected child. Whole exome sequencing (WES) was performed by using standard techniques, with prioritized genetic variants confirmed via Sanger sequencing. To investigate the effects of one candidate variant on mutant WDR11 function, Western blotting and coimmunofluorescence were used to assess binding capacity, and leptomycin B exposure along with immunofluorescence was used to assess nuclear localization. We describe a child who presented in infancy with combined pituitary hormone deficiencies and whose brain imaging demonstrated a small anterior pituitary, ectopic posterior pituitary, and a thin, interrupted stalk. WES demonstrated heterozygous missense mutations in two genes required for pituitary development, a known loss-of-function mutation in PROKR2 (c.253C>T;p.R85C) inherited from an unaffected mother, and a WDR11 (c.1306A>G;p.I436V) mutation inherited from an unaffected father. Mutant WDR11 loses its capacity to bind to its functional partner, EMX1, and to localize to the nucleus. WES in a child with PSIS and his unaffected family implicates a digenic mechanism of inheritance. In cases of hypopituitarism in which there is incomplete segregation of a monogenic genotype with the phenotype, the possibility that a second genetic locus is involved should be considered. Copyright © 2017 Endocrine Society

  8. A caveat regarding diatom-inferred nitrogen concentrations in oligotrophic lakes

    Science.gov (United States)

    Arnett, Heather A.; Saros, Jasmine E.; Mast, M. Alisa

    2012-01-01

    Atmospheric deposition of reactive nitrogen (Nr) has enriched oligotrophic lakes with nitrogen (N) in many regions of the world and elicited dramatic changes in diatom community structure. The lakewater concentrations of nitrate that cause these community changes remain unclear, raising interest in the development of diatom-based transfer functions to infer nitrate. We developed a diatom calibration set using surface sediment samples from 46 high-elevation lakes across the Rocky Mountains of the western US, a region spanning an N deposition gradient from very low to moderate levels (phosphorus, and hypolimnetic water temperature were related to diatom distributions. A transfer function was developed for nitrate and applied to a sedimentary diatom profile from Heart Lake in the central Rockies. The model coefficient of determination (bootstrapping validation) of 0.61 suggested potential for diatom-inferred reconstructions of lakewater nitrate concentrations over time, but a comparison of observed versus diatom-inferred nitrate values revealed the poor performance of this model at low nitrate concentrations. Resource physiology experiments revealed that nitrogen requirements of two key taxa were opposite to nitrate optima defined in the transfer function. Our data set reveals two underlying ecological constraints that impede the development of nitrate transfer functions in oligotrophic lakes: (1) even in lakes with nitrate concentrations below quantification (<1 μg L−1), diatom assemblages were already dominated by species indicative of moderate N enrichment; (2) N-limited oligotrophic lakes switch to P limitation after receiving only modest inputs of reactive N, shifting the controls on diatom species changes along the length of the nitrate gradient. These constraints suggest that quantitative inferences of nitrate from diatom assemblages will likely require experimental approaches.

  9. In vivo exposure to northern diatoms arrests sea urchin embryonic development.

    Science.gov (United States)

    Gudimova, Elena; Eilertsen, Hans C; Jørgensen, Trond Ø; Hansen, Espen

    2016-01-01

    There are numerous reports indicating that marine diatoms may act harmful to early developmental stages of invertebrates. It is believed that the compounds responsible for these detrimental effects are oxylipins resulting from oxidized polyunsaturated fatty acids, and that they may function as grazing deterrents. Most studies reporting these effects have exposed test organisms to diatom extracts or purified toxins, but data from in vivo exposure to intact diatoms are scarce. We have conducted sea urchin egg incubation and plutei feeding experiments to test if intact diatom cells affected sea urchin embryo development and survival. This was done by exposing the common northern sea urchins Strongylocentrotus droebachiensis and Echinus acutus to northern strains of the diatoms Chaetoceros socialis, Skeletonema marinoi, Chaetoceros furcellatus, Attheya longicornis, Thalassiosira gravida and Porosira glacialis. The intact diatom cell suspensions were found to inhibit sea urchin egg hatching and embryogenesis. S. marinoi was the most potent one as it caused acute mortality in S. droebachiensis eggs after only four hours exposure to high (50 μg/L Chla) diatom concentrations, as well as 24 h exposure to normal (20 μg/L Chla) and high diatom concentrations. The second most potent species was T. gravida that caused acute mortality after 24 h exposure to both diatom concentrations. A. longicornis was the least harmful of the diatom species in terms of embryo development arrestment, and it was the species that was most actively ingested by S. droebachiensis plutei. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Symmetries and rotational line intensities in diatomic molecules

    International Nuclear Information System (INIS)

    Veseth, L.

    1986-02-01

    The general theory of angular momenta and the full rotation group is used to reconsider the theory of the intensity factors of rotational lines in the spectra of diatomic molecules (Hoenl-London factors). It is shown that the use of the rotational symmetry (rotation matrices) leads to compact derivations of the symmetry properties of the molecular wave functions, as well as the matrix elements of the transitions operator. The present work is restricted to spin-allowed electric dipole transitions, and the general sum rule characteristic of this type of transitions is rederived by use of the general angular momentum theory. A main purpose of the present work has been to provide a unified theoretical basis for exact numerical computations of Hoenl-London factors for all types of spin-allowed electric dipole transitions in diatomic molecules. The computed Hoenl-London factors are then in the next step intended to be the basis for construction of synthetic molecular band spectra, with particular applications to upper atmosperic emissions (aurora)

  11. Toxic Diatom Aldehydes Affect Defence Gene Networks in Sea Urchins.

    Directory of Open Access Journals (Sweden)

    Stefano Varrella

    Full Text Available Marine organisms possess a series of cellular strategies to counteract the negative effects of toxic compounds, including the massive reorganization of gene expression networks. Here we report the modulated dose-dependent response of activated genes by diatom polyunsaturated aldehydes (PUAs in the sea urchin Paracentrotus lividus. PUAs are secondary metabolites deriving from the oxidation of fatty acids, inducing deleterious effects on the reproduction and development of planktonic and benthic organisms that feed on these unicellular algae and with anti-cancer activity. Our previous results showed that PUAs target several genes, implicated in different functional processes in this sea urchin. Using interactomic Ingenuity Pathway Analysis we now show that the genes targeted by PUAs are correlated with four HUB genes, NF-κB, p53, δ-2-catenin and HIF1A, which have not been previously reported for P. lividus. We propose a working model describing hypothetical pathways potentially involved in toxic aldehyde stress response in sea urchins. This represents the first report on gene networks affected by PUAs, opening new perspectives in understanding the cellular mechanisms underlying the response of benthic organisms to diatom exposure.

  12. Diatom diversity in chronically versus episodically acidified adirondack streams

    Science.gov (United States)

    Passy, S.I.; Ciugulea, I.; Lawrence, G.B.

    2006-01-01

    The relationship between algal species richness and diversity, and pH is controversial. Furthermore, it is still unknown how episodic stream acidification following atmospheric deposition affects species richness and diversity. Here we analyzed water chemistry and diatom epiphyton dynamics and showed their contrasting behavior in chronically vs. episodically acidic streams in the Adirondack region. Species richness and diversity were significantly higher in the chronically acidic brown water stream, where organic acidity was significantly higher and the ratio of inorganic to organic monomeric aluminum significantly lower. Conversely, in the episodically acidic clear water stream, the inorganic acidity and pH were significantly higher and the diatom communities were very species-poor. This suggests that episodic acidification in the Adirondacks may be more stressful for stream biota than chronic acidity. Strong negative linear relationships between species diversity, Eunotia exigua, and dissolved organic carbon against pH were revealed after the influence of non-linear temporal trends was partialled out using a novel way of temporal modeling. ?? 2006 WILEY-VCH Verlag GmbH & Co. KGaA.

  13. Study on the excited diatomic molecules of rare gas

    International Nuclear Information System (INIS)

    Kasama, Kunihiko; Arai, Shigeyoshi

    1981-01-01

    The study on the excited diatomic molecules of rare gas is presented. The absorption spectra, the mechanism of formation and attenuation and the reactions with other molecules are described. The excitation of rare gas was made by using a pulsed electron beam generator. The absorption of excited diatomic molecules was measured as the functions of time. Two absorption peaks were observed. The electron states of rare gases were estimated. The observed and calculated transition values were given for each peak. The absorption spectra of Ne change with time. The spectra of Ar do not change with time. Four and eleven absorption maxima were seen in the spectra of Kr and Xe, respectively. In the case of Ar, the thermal equilibrium existed. The constants of the production and attenuation rates were obtained as the functions of Ar gas pressure. In the case of Ne, there wad definitely the time dependence of absorption spectra. The attenuation constant was obtained for each transition between various vibration levels. It is necessary to consider the relaxation from high vibrational levels. The energy transfer between vibrational levels hardly occurred in Ne because the intervals are large. When there are other molecules, the attnuation was accelerated. (Kato, T.)

  14. Fragmentation patterns in the diatom genus Rouxia and their potential for identifying latent depositional hiatuses in the early Pliocene diatomite of the ANDRILL AND-1B core

    Science.gov (United States)

    Konfirst, M. A.; Scherer, R. P.; Winter, D.; Sjunneskog, C.; Warnock, J.; Kuhn, G.; Niessen, F.; Helling, D.; Magens, D.

    2009-04-01

    Diatom genera have traditionally been split into two primary groupings based upon the symmetry of the siliceous frustule. Diatoms symmetric about a point are classified as centrics, while those symmetric about a line are classified as pennates. This fundamental difference in shape has consequences for preservation in ice proximal settings, where an overriding ice sheet can create shearing in the upper meters of the sediment column. This leads to preferential breakage in pennate forms, and results in a higher ratio of undamaged centric to pennate frustules (Scherer et al., 2004). Similarly, an ice sheet grounded over highly porous diatomite results in significant diatom fragmentation resulting from normal load compaction. The diatom genus Rouxia is a pennate form with a relatively wide raphe, making it particularly susceptible to breakage during ice advance and retreat, and offering the opportunity to evaluate ice advance stages in sedimentary units where glacial erosion may have removed upper depositional units. In the ANDRILL AND-1B core, a long interval of nearly pure diatomite was recovered from 382.98-459.24 mbsf. Construction of an age model during this interval has relied primarily on age ranges provided by presence or absence of key diatom species. However, questions still remain as to the continuity of deposition. In this study, samples were collected at an average of 50-cm spacing for the length of the long diatom unit as well as for 20 meters of the silica-rich diamictite unit directly overlaying the diatomite. Fragments of specimens from the genus Rouxia were counted and classified into categories based on the size of the fragment in relation to total frustule length. These data were then used to develop a quantitative index, which was examined for changes in fragmentation through time. Preliminary data are presented that indicate increased fragmentation at the top of the section under study, which we interpret to indicate evidence for increased glacial

  15. Fracture line index of fibular stalk and the ankle joint bone in the classification of the ankle joint trauma

    International Nuclear Information System (INIS)

    Wu Jun; Zhang Qiang

    2003-01-01

    Objective: To evaluate the fracture line index of fibular stalk and the ankle joint bone in the classification of the ankle joint trauma. Methods: Measure fracture line index of fibular stalk and the ankle joint in 217 adult cases of fracture and dislocation of ankle joint. And the cases were classified by the results of the measurement. Results: Measurement was unavailable in 9 cases of tearing fracture. In 31 cases, the lesions could not be particularly classified. And in the rest 176 cases the trauma were precisely classified. The over all successful rate was 81.6%. Conclusion: Fracture line index of fibular stalk and the ankle joint bone are valuable in classification of the trauma of the angle joint. While the specificity of this method is low in differentiating the adducting and abducting fracture of the medial angle, in which a combined investigation is recommended

  16. Processing and characterization of diatom nanoparticles and microparticles as potential source of silicon for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Le, Thi Duy Hanh [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Bonani, Walter [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Interuniversity Consortium for Science and Technology of Materials, Trento Research Unit, Trento (Italy); Speranza, Giorgio [Center for Materials and Microsystems, PAM-SE, Fondazione Bruno Kessler, Trento (Italy); Sglavo, Vincenzo; Ceccato, Riccardo [Department of Industrial Engineering, University of Trento, Trento (Italy); Maniglio, Devid; Motta, Antonella [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Interuniversity Consortium for Science and Technology of Materials, Trento Research Unit, Trento (Italy); Migliaresi, Claudio, E-mail: claudio.migliaresi@unitn.it [Department of Industrial Engineering, University of Trento, Trento (Italy); BIOtech Research Center and European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Trento (Italy); Interuniversity Consortium for Science and Technology of Materials, Trento Research Unit, Trento (Italy)

    2016-02-01

    Silicon plays an important role in bone formation and maintenance, improving osteoblast cell function and inducing mineralization. Often, bone deformation and long bone abnormalities have been associated with silica/silicon deficiency. Diatomite, a natural deposit of diatom skeleton, is a cheap and abundant source of biogenic silica. The aim of the present study is to validate the potential of diatom particles derived from diatom skeletons as silicon-donor materials for bone tissue engineering applications. Raw diatomite (RD) and calcined diatomite (CD) powders were purified by acid treatments, and diatom microparticles (MPs) and nanoparticles (NPs) were produced by fragmentation of purified diatoms under alkaline conditions. The influence of processing on the surface chemical composition of purified diatomites was evaluated by X-ray photoelectron spectroscopy (XPS). Diatoms NPs were also characterized in terms of morphology and size distribution by transmission electron microscopy (TEM) and Dynamic light scattering (DLS), while diatom MPs morphology was analyzed by scanning electron microscopy (SEM). Surface area and microporosity of the diatom particles were evaluated by nitrogen physisorption methods. Release of silicon ions from diatom-derived particles was demonstrated using inductively coupled plasma optical emission spectrometry (ICP/OES); furthermore, silicon release kinetic was found to be influenced by diatomite purification method and particle size. Diatom-derived microparticles (MPs) and nanoparticles (NPs) showed limited or no cytotoxic effect in vitro depending on the administration conditions. - Highlights: • Diatomite is a natural source of silica and has a potential as silicon-donor for bone regenerative applications. • Diatom particles derived from purified diatom skeletons were prepared by fragmentation under extreme alkaline condition. • Dissolution of diatom particles derived from diatom skeletons in DI water depend on purification method

  17. Ecophysiological and biochemical variation of the surf zone diatom asterionellopsis glacialis sensu lato from Santa Catarina, Southern Brazil

    Directory of Open Access Journals (Sweden)

    Leonardo Rubi Rörig

    Full Text Available Abstract Patches formed by dense accumulations of diatoms in the surf zone (surf diatoms are common on sandy beaches with intermediate to dissipative morphodynamic states. Their appearances are correlated with environmental factors such as the passage of cold fronts when onshore winds increase beach hydrodynamics, resuspending epibenthic stocks and accumulating them through the inner surf zone. In Santa Catarina state, Southern Brazil, two beaches are known to have frequent occurrence of accumulations of the surf diatom Asterionellopsis glacialis sensu lato: Rincão Beach (28°50' S and Navegantes Beach (26°52' S. The high biomass of this alga and its central importance in the trophic structure of the coastal ecosystems suggest studies about its potential applications. In the present study, strains of A. glacialis were isolated, cultured under different conditions and evaluated for ecophysiological aspects: growth rate under different conditions, potential biological activities of exudates, biomass and lipid content, and fatty acid profile. A. glacialis cells in culture showed deformation, which were ameliorated by using agitation and silicon and phosphorus enriched culture media. Exudates of the strains showed no allelopathic effects, although previous studies have indicated activity. Lipid content showed variation depending on the strain and culture media. Values ranged from 9% to 13.6% by dry weight. In all strains saturated fatty acids and polyunsaturated fatty acids were identified. Some hypotheses were proposed to explain the variation of the lipid contents, fatty acid profiles and physiological features between strains of the same species. We believe that the fatty acids profile of this primary producer has important consequences in the sandy beach ecology.

  18. C5 glycolipids of heterocystous cyanobacteria track symbiont abundance in the diatom Hemiaulus hauckii across the tropical North Atlantic

    Science.gov (United States)

    Bale, Nicole J.; Villareal, Tracy A.; Hopmans, Ellen C.; Brussaard, Corina P. D.; Besseling, Marc; Dorhout, Denise; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2018-03-01

    Diatom-diazotroph associations (DDAs) include marine heterocystous cyanobacteria found as exosymbionts and endosymbionts in multiple diatom species. Heterocysts are the site of N2 fixation and have thickened cell walls containing unique heterocyst glycolipids which maintain a low oxygen environment within the heterocyst. The endosymbiotic cyanobacterium Richelia intracellularis found in species of the diatom genus Hemiaulus and Rhizosolenia makes heterocyst glycolipids (HGs) which are composed of C30 and C32 diols and triols with pentose (C5) moieties that are distinct from limnetic cyanobacterial HGs with predominantly hexose (C6) moieties. Here we applied a method for analysis of intact polar lipids to the study of HGs in suspended particulate matter (SPM) and surface sediment from across the tropical North Atlantic. The study focused on the Amazon plume region, where DDAs are documented to form extensive surface blooms, in order to examine the utility of C5 HGs as markers for DDAs as well as their transportation to underlying sediments. C30 and C32 triols with C5 pentose moieties were detected in both marine SPM and surface sediments. We found a significant correlation between the water column concentration of these long-chain C5 HGs and DDA symbiont counts. In particular, the concentrations of both the C5 HGs (1-(O-ribose)-3,27,29-triacontanetriol (C5 HG30 triol) and 1-(O-ribose)-3,29,31-dotriacontanetriol (C5 HG32 triol)) in SPM exhibited a significant correlation with the number of Hemiaulus hauckii symbionts. This result strengthens the idea that long-chain C5 HGs can be applied as biomarkers for marine endosymbiotic heterocystous cyanobacteria. The presence of the same C5 HGs in surface sediment provides evidence that they are effectively transported to the sediment and hence have potential as biomarkers for studies of the contribution of DDAs to the paleo-marine N cycle.

  19. Evidence of the most stretchable egg sac silk stalk, of the European spider of the year Meta menardi.

    Directory of Open Access Journals (Sweden)

    Emiliano Lepore

    Full Text Available Spider silks display generally strong mechanical properties, even if differences between species and within the same species can be observed. While many different types of silks have been tested, the mechanical properties of stalks of silk taken from the egg sac of the cave spider Meta menardi have not yet been analyzed. Meta menardi has recently been chosen as the "European spider of the year 2012", from the European Society of Arachnology. Here we report a study where silk stalks were collected directly from several caves in the north-west of Italy. Field emission scanning electron microscope (FESEM images showed that stalks are made up of a large number of threads, each of them with diameter of 6.03 ± 0.58 µm. The stalks were strained at the constant rate of 2 mm/min, using a tensile testing machine. The observed maximum stress, strain and toughness modulus, defined as the area under the stress-strain curve, are 0.64 GPa, 751% and 130.7 MJ/m(3, respectively. To the best of our knowledge, such an observed huge elongation has never been reported for egg sac silk stalks and suggests a huge unrolling microscopic mechanism of the macroscopic stalk that, as a continuation of the protective egg sac, is expected to be composed by fibres very densely and randomly packed. The Weibull statistics was used to analyze the results from mechanical testing, and an average value of Weibull modulus (m is deduced to be in the range of 1.5-1.8 with a Weibull scale parameter (σ(0 in the range of 0.33-0.41 GPa, showing a high coefficient of correlation (R(2 = 0.97.

  20. Evidence of the most stretchable egg sac silk stalk, of the European spider of the year Meta menardi.

    Science.gov (United States)

    Lepore, Emiliano; Marchioro, Andrea; Isaia, Marco; Buehler, Markus J; Pugno, Nicola M

    2012-01-01

    Spider silks display generally strong mechanical properties, even if differences between species and within the same species can be observed. While many different types of silks have been tested, the mechanical properties of stalks of silk taken from the egg sac of the cave spider Meta menardi have not yet been analyzed. Meta menardi has recently been chosen as the "European spider of the year 2012", from the European Society of Arachnology. Here we report a study where silk stalks were collected directly from several caves in the north-west of Italy. Field emission scanning electron microscope (FESEM) images showed that stalks are made up of a large number of threads, each of them with diameter of 6.03 ± 0.58 µm. The stalks were strained at the constant rate of 2 mm/min, using a tensile testing machine. The observed maximum stress, strain and toughness modulus, defined as the area under the stress-strain curve, are 0.64 GPa, 751% and 130.7 MJ/m(3), respectively. To the best of our knowledge, such an observed huge elongation has never been reported for egg sac silk stalks and suggests a huge unrolling microscopic mechanism of the macroscopic stalk that, as a continuation of the protective egg sac, is expected to be composed by fibres very densely and randomly packed. The Weibull statistics was used to analyze the results from mechanical testing, and an average value of Weibull modulus (m) is deduced to be in the range of 1.5-1.8 with a Weibull scale parameter (σ(0)) in the range of 0.33-0.41 GPa, showing a high coefficient of correlation (R(2) = 0.97).

  1. An improved coupled-states approximation including the nearest neighbor Coriolis couplings for diatom-diatom inelastic collision

    Science.gov (United States)

    Yang, Dongzheng; Hu, Xixi; Zhang, Dong H.; Xie, Daiqian

    2018-02-01

    Solving the time-independent close coupling equations of a diatom-diatom inelastic collision system by using the rigorous close-coupling approach is numerically difficult because of its expensive matrix manipulation. The coupled-states approximation decouples the centrifugal matrix by neglecting the important Coriolis couplings completely. In this work, a new approximation method based on the coupled-states approximation is presented and applied to time-independent quantum dynamic calculations. This approach only considers the most important Coriolis coupling with the nearest neighbors and ignores weaker Coriolis couplings with farther K channels. As a result, it reduces the computational costs without a significant loss of accuracy. Numerical tests for para-H2+ortho-H2 and para-H2+HD inelastic collision were carried out and the results showed that the improved method dramatically reduces the errors due to the neglect of the Coriolis couplings in the coupled-states approximation. This strategy should be useful in quantum dynamics of other systems.

  2. High-resolution heavily T2-weighted magnetic resonance imaging for evaluation of the pituitary stalk in children with ectopic neurohypophysis

    Energy Technology Data Exchange (ETDEWEB)

    Sanharawi, Imane El; Tzarouchi, Loukia [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Cardoen, Liesbeth [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Universite Paris Diderot, Paris (France); Martinerie, Laetitia; Leger, Juliane; Carel, Jean-Claude [Universite Paris Diderot, Paris (France); Inserm U1141, DHU PROTECT, Paris (France); Hopital Robert Debre, APHP, Service d' Endocrinologie Pediatrique, Paris (France); Elmaleh-Berges, Monique [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Inserm U1141, DHU PROTECT, Paris (France); Alison, Marianne [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Universite Paris Diderot, Paris (France); Inserm U1141, DHU PROTECT, Paris (France)

    2017-05-15

    In anterior pituitary deficiency, patients with non visible pituitary stalk have more often multiple deficiencies and persistent deficiency than patients with visible pituitary stalk. To compare the diagnostic value of a high-resolution heavily T2-weighted sequence to 1.5-mm-thick unenhanced and contrast-enhanced sagittal T1-weighted sequences to assess the presence of the pituitary stalk in children with ectopic posterior pituitary gland. We retrospectively evaluated the MRI data of 14 children diagnosed with ectopic posterior pituitary gland between 2010 and 2014. We evaluated the presence of a pituitary stalk using a sagittal high-resolution heavily T2-weighted sequence and a 1.5-mm sagittal T1-weighted turbo spin-echo sequence before and after contrast medium administration. A pituitary stalk was present on at least one of the sequences in 10 of the 14 children (71%). T2-weighted sequence depicted the pituitary stalk in all 10 children, whereas the 1.5-mm-thick T1-weighted sequence depicted 2/10 (20%) before contrast injection and 8/10 (80%) after contrast injection (P=0.007). Compared with 1.5-mm-thick contrast-enhanced T1-weighted sequences, high-resolution heavily T2-weighted sequence demonstrates better sensitivity in detecting the pituitary stalk in children with ectopic posterior pituitary gland, suggesting that contrast injection is unnecessary to assess the presence of a pituitary stalk in this setting. (orig.)

  3. High-resolution heavily T2-weighted magnetic resonance imaging for evaluation of the pituitary stalk in children with ectopic neurohypophysis.

    Science.gov (United States)

    El Sanharawi, Imane; Tzarouchi, Loukia; Cardoen, Liesbeth; Martinerie, Laetitia; Leger, Juliane; Carel, Jean-Claude; Elmaleh-Berges, Monique; Alison, Marianne

    2017-05-01

    In anterior pituitary deficiency, patients with non visible pituitary stalk have more often multiple deficiencies and persistent deficiency than patients with visible pituitary stalk. To compare the diagnostic value of a high-resolution heavily T2-weighted sequence to 1.5-mm-thick unenhanced and contrast-enhanced sagittal T1-weighted sequences to assess the presence of the pituitary stalk in children with ectopic posterior pituitary gland. We retrospectively evaluated the MRI data of 14 children diagnosed with ectopic posterior pituitary gland between 2010 and 2014. We evaluated the presence of a pituitary stalk using a sagittal high-resolution heavily T2-weighted sequence and a 1.5-mm sagittal T1-weighted turbo spin-echo sequence before and after contrast medium administration. A pituitary stalk was present on at least one of the sequences in 10 of the 14 children (71%). T2-weighted sequence depicted the pituitary stalk in all 10 children, whereas the 1.5-mm-thick T1-weighted sequence depicted 2/10 (20%) before contrast injection and 8/10 (80%) after contrast injection (P=0.007). Compared with 1.5-mm-thick contrast-enhanced T1-weighted sequences, high-resolution heavily T2-weighted sequence demonstrates better sensitivity in detecting the pituitary stalk in children with ectopic posterior pituitary gland, suggesting that contrast injection is unnecessary to assess the presence of a pituitary stalk in this setting.

  4. Interference between vibration-to-translation and vibration-to-vibration energy transfer modes in diatomic molecules at high collision energies

    International Nuclear Information System (INIS)

    Shin, H.K.

    1983-01-01

    An explicit time dependent approach for simultaneous VT and VV energy transfer in diatom--diatom collisions is explored using the exponential form of ladder operators in the solution of the Schroedinger equation of motion. The collision of two hydrogen molecules is chosen to illustrate the extent of interference between VT and VV modes among various vibrational states. While vibrational energy transfer processes of nominally VT type can be treated with pure VT mode at low collision energies, the intermode coupling is found to be very important at collision energies of several hω. The occurrence of the coupling appears to be nearly universal in vibrational transitions at such energies. Exceptions to the coupling have been discussed

  5. Effect of Piper betel leaf stalk extract on protein metabolism in reproductive tissues of male albino rats

    OpenAIRE

    V Vengaiah; A Govardhan Naik; C Changamma

    2015-01-01

    Objective: To know the impact of Piper betel leaf stalk (P. betel) extract on Protein and energy metabolism and its role in male albino rats. Methods: Healthy adult (3-4 months old) male Wistar strain albino rats were administered with betel leaf stalk extract, at the dose of 50 mg/kg/day through oral gavages for 15 days. Twenty four hours after the last dose, the animals were autopsied. In order to assess antifertility effect in testis, epididymis, seminal vesicle and prostate gland, esti...

  6. [Phenolic foam prepared by lignin from a steam-explosion derived biorefinery of corn stalk].

    Science.gov (United States)

    Wang, Guanhua; Chen, Hongzhang

    2014-06-01

    To increase the integral economic effectiveness, biorefineries of lignocellulosic materials should not only utilize carbohydrates hydrolyzed from cellulose and hemicellulose but also use lignin. We used steam-exploded corn stalk as raw materials and optimized the temperature and alkali concentration in the lignin extraction process to obtain lignin liquor with higher yield and purity. Then the concentrated lignin liquor was used directly to substitute phenol for phenolic foam preparation and the performances of phenolic foam were characterized by microscopic structure analysis, FTIR, compression strength and thermal conductivity detection. The results indicated that, when steam-exploded corn stalk was extracted at 120 degrees C for 2 h by 1% NaOH with a solid to liquid ratio of 1:10, the extraction yield of lignin was 79.67%. The phenolic foam prepared from the concentrated lignin liquor showed higher apparent density and compression strength with the increasing substitution rate of lignin liquor. However, there were not significant differences of thermal conductivity and flame retardant properties by the addition of lignin, which meant that the phenolic foam substituted by lignin liquor was approved for commercial application. This study, which uses alkali-extracted lignin liquor directly for phenolic foam preparation, provides a relatively simple way for utilization of lignin and finally increases the overall commercial operability ofa lignocellulosic biorefinery derived by steam explosion.

  7. Effect of thermal and high pressure processing on stability of betalain extracted from red beet stalks.

    Science.gov (United States)

    Dos Santos, Cláudia Destro; Ismail, Marliya; Cassini, Aline Schilling; Marczak, Ligia Damasceno Ferreira; Tessaro, Isabel Cristina; Farid, Mohammed

    2018-02-01

    Red beet stalks are a potential source of betalain, but their pigments are not widely used because of their instability. In the present work, the applicability of high pressure processing (HPP) and high temperature short time (HTST) thermal treatment was investigated to improve betalain stability in extracts with low and high concentrations. The HPP was applied at 6000 bar for 10, 20 and 30 min and HTST treatment was applied at 75.7 °C for 80 s, 81.1 °C for 100 s and 85.7 °C for 120 s, HPP treatment did not show any improvement in the betalain stability. In turn, the degradation rate of the control and the HTST thermal treatment at 85.7 °C for 120 s of the sample with high initial betalain concentration were 1.2 and 0.4 mg of betanin/100 ml of extract per day respectively. Among the treatments studied, HTST was considered the most suitable to maintain betalain stability from red beet stalks.

  8. Rhamnolipid Biosurfactant against Fusarium verticillioides to Control Stalk and Ear Rot Disease of Maize

    Directory of Open Access Journals (Sweden)

    Siddhartha Narayan Borah

    2016-09-01

    Full Text Available Antifungal activity of rhamnolipids (RLs has been widely studied against many plant pathogenic fungi, but not against Fusarium verticillioides, a major pathogen of maize (Zea mays L.. F. verticillioides causes stalk and ear rot of maize or asymptomatically colonizes the plant and ears resulting in moderate to heavy crop loss throughout the world. F. verticillioides produces fumonisin mycotoxins, reported carcinogens, which makes the contaminated ears unsuitable for consumption. In this study, the RL produced using glucose as sole carbon source was characterized by FTIR and LCMS analyses and its antifungal activity against F. verticillioides was evaluated in vitro on maize stalks and seeds. Further, the effect of RL on the mycelia of F. verticillioides was investigated by scanning electron microscopy which revealed visible damage to the mycelial structure as compared to control samples. In planta, treatment of maize seeds with a RL concentration of 50 mg l-1 resulted in improved biomass and fruiting compared to those of healthy control plants and complete suppression of characteristic disease symptoms and colonization of maize by F. verticillioides. The study highlights the potential of RLs to be used for an effective biocontrol strategy against colonization of maize plant by F. verticillioides.

  9. Modification of Sorghum Starch-Cellulose Bioplastic with Sorghum Stalks Filler

    Directory of Open Access Journals (Sweden)

    Yuli Darni

    2017-05-01

    Full Text Available This study evaluated the feasibility of bioplastics production by various ratio of sorghum starch and cellulose from red seaweed Eucheuma spinossum, and the use of glycerol as plasticizer and sorghum stalks as filler. Solid-liquid matrix transition should be far over the operating temperature of gelatinization and extracted at 95oC in order to avoid the loss of conductivity. The analyzed variables were starch and cellulose seaweed Eucheuma spinossum and the addition of variation of filler. Sorghum stalk could be expected to affect the mechanical and physical properties of bioplastics. A thin sheet of plastic (plastic film was obtained as a result that have been tested mechanically to obtain the best condition for the formulation of starch-cellulose 8.5:1.5 (g/g. From the result of morphological studies, the fillers in the mixture composites were more randomly in each product and the addition of filler can increase mechanical properties of bioplastics. Chemical modification had a major effect on the mechanical properties. The phenomena of degradation and thermoplasticization were visible at chemical changes that can be observed in FTIR spectrum test results.

  10. Ethanol production from concentrated food waste hydrolysates with yeast cells immobilized on corn stalk

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shoubao [Huainan Normal Univ., Anhui (China). School of Life Science; Chen, Xiangsong; Wu, Jingyong; Wang, Pingchao [Chinese Academy of Sciences, Hefei (China). Key Lab. of Ion Beam Bio-engineering of Inst. of Plasma Physics

    2012-05-15

    The aim of the present study was to examine ethanol production from concentrated food waste hydrolysates using whole cells of S. cerevisiae immobilized on corn stalks. In order to improve cell immobilization efficiency, biological modification of the carrier was carried out by cellulase hydrolysis. The results show that proper modification of the carrier with cellulase hydrolysis was suitable for cell immobilization. The mechanism proposed, cellulase hydrolysis, not only increased the immobilized cell concentration, but also disrupted the sleek surface to become rough and porous, which enhanced ethanol production. In batch fermentation with an initial reducing sugar concentration of 202.64 {+-} 1.86 g/l, an optimal ethanol concentration of 87.91 {+-} 1.98 g/l was obtained using a modified corn stalk-immobilized cell system. The ethanol concentration produced by the immobilized cells was 6.9% higher than that produced by the free cells. Ethanol production in the 14th cycle repeated batch fermentation demonstrated the enhanced stability of the immobilized yeast cells. Under continuous fermentation in an immobilized cell reactor, the maximum ethanol concentration of 84.85 g/l, and the highest ethanol yield of 0.43 g/g (of reducing sugar) were achieved at hydraulic retention time (HRT) of 3.10 h, whereas the maximum volumetric ethanol productivity of 43.54 g/l/h was observed at a HRT of 1.55 h. (orig.)

  11. Stalk and sucrose yield in response to nitrogen fertilization of sugarcane under reduced tillage

    Directory of Open Access Journals (Sweden)

    Caio Fortes

    2013-01-01

    Full Text Available The objective of this work was to evaluate the agroindustrial production of sugarcane (millable stalks and sucrose yield after successive nitrogen fertilizations of plant cane and ratoons in a reduced tillage system. The experiment was carried out at Jaboticabal, SP, Brazil, on a Rhodic Eutrustox soil, during four consecutive crop cycles (March 2005 to July 2009. Plant cane treatments consisted of N-urea levels (control, 40, 80, and 120 kg ha-1 N + 120 kg ha-1 P2O5 and K2O in furrow application. In the first and second ratoons, the plant cane plots were subdivided in N-ammonium nitrate treatments (control, 50, 100, and 150 kg ha-1 N + 150 kg ha-1 K2O as top dressing over rows. In the third ratoon, N fertilization was leveled to 100 kg ha-1 in all plots, including controls, to detect residual effects of previous fertilizations on the last crop's cycle. Sugarcane ratoon was mechanically harvested. A weighing truck was used to evaluate stalk yield (TCH, and samples were collected in the field for analysis of sugar content (TSH. Increasing N doses and meteorological conditions promote significant responses in TCH and TSH in cane plant and ratoons, in the average and accumulated yield of the consecutive crop cycles.

  12. Maize Cob Rot in Kenya and Its Association with Stalk Borer Damage

    International Nuclear Information System (INIS)

    Ajanga, S.I.

    2002-01-01

    Cob rots are a major cause of crop loss in areas such as western Kenya that experience prolonged rainfall during the period of crop maturation. Cob rot fungi cause spoilage of the grain and some of them produce mycotoxins which can pose a health risk to humans and animals consuming foods prepared from contaminate grain. survey conducted in western Kenya in 1998 showed that cob rot incidence exceeded 20%. In the following year when rainfall was greater around the harvest period, cob rot fungi affected 68% of cobs. in 1998 stalk borer larvae (mainly Busseola fusca) damaged 20% of the cobs and there was a strong correlation (R= 0.87) between cob rot incidence and borer damage. In 1999 almost half of the cobs sampled showed evidence of borer damage. The result indicate that the high cob rot incidence in this pert of Kenya is due to stalk bore damage, which predisposes the cobs to fungal infection, and that management of the borer would greatly decrease cob rot incidence

  13. Saccharification of sunflower stalks using lignocellulases from a fungal consortium comprising Pholiota adiposa and Armillaria gemina.

    Science.gov (United States)

    Ramachandran, Priyadharshini; Kim, Tae-Su; Dhiman, Saurabh Sudha; Li, Jinglin; Park, Ji-Hyun; Choi, Joon-Ho; Kim, Jae Young; Kim, Dongwook; Lee, Jung-Kul

    2015-09-01

    Lignocellulases from Armillaria gemina and Pholiota adiposa are efficient in hydrolyzing aspen and poplar biomass, respectively. In the present study, lignocellulosic enzymes obtained from a fungal consortium comprising P. adiposa and A. gemina were used for the saccharification of sunflower stalks. Sunflower stalks were thermochemically pretreated using 2 % NaOH at 50 °C for 24 h. The saccharification process parameters including substrate concentration, enzyme loading, pH, and temperature were optimized using response surface methodology to improve the saccharification yield. The highest enzymatic hydrolysis (84.3 %) was obtained using the following conditions: enzyme loading 10 FPU/g-substrate, substrate 5.5 %, temperature 50 °C, and pH 4.5. The hydrolysis yield obtained using the enzymes from the fungal consortium was equivalent to that obtained using a mixture of commercial enzymes Celluclast and Novozyme β-glucosidase. Addition of up to 500 ppm of heavy metal ions (As, Cu, Fe, Mn, Ni, Pb, and Zn) during saccharification did not significantly affect the saccharification yield. Thus, the biomass grown for phytoremediation of heavy metals can be used for the production of reducing sugars followed by ethanol fermentation.

  14. What if the Diatoms of the Deep Chlorophyll Maximum Can Ascend?

    Science.gov (United States)

    Villareal, T. A.

    2016-02-01

    Buoyancy regulation is an integral part of diatom ecology via its role in sinking rates and is fundamental to understanding their distribution and abundance. Numerous studies have documented the effects of size and nutrition on sinking rates. Many pelagic diatoms have low intrinsic sinking rates when healthy and nutrient-replete (deep chlorophyll maximum. The potential for ascending behavior adds an additional layer of complexity by allowing both active depth regulation similar to that observed in flagellated taxa and upward transport by some fraction of deep euphotic zone diatom blooms supported by nutrient injection. In this talk, I review the data documenting positive buoyancy in small diatoms, offer direct visual evidence of ascending behavior in common diatoms typical of both oceanic and coastal zones, and note the characteristics of sinking rate distributions within a single species. Buoyancy control leads to bidirectional movement at similar rates across a wide size spectrum of diatoms although the frequency of ascending behavior may be only a small portion of the individual species' abundance. While much remains to be learned, the paradigm of unidirectional downward movement by diatoms is both inaccurate and an oversimplification.

  15. Diatoms dominate the eukaryotic metatranscriptome during spring in coastal 'dead zone' sediments.

    Science.gov (United States)

    Broman, Elias; Sachpazidou, Varvara; Dopson, Mark; Hylander, Samuel

    2017-10-11

    An important characteristic of marine sediments is the oxygen concentration that affects many central metabolic processes. There has been a widespread increase in hypoxia in coastal systems (referred to as 'dead zones') mainly caused by eutrophication. Hence, it is central to understand the metabolism and ecology of eukaryotic life in sediments during changing oxygen conditions. Therefore, we sampled coastal 'dead zone' Baltic Sea sediment during autumn and spring, and analysed the eukaryotic metatranscriptome from field samples and after incubation in the dark under oxic or anoxic conditions. Bacillariophyta (diatoms) dominated the eukaryotic metatranscriptome in spring and were also abundant during autumn. A large fraction of the diatom RNA reads was associated with the photosystems suggesting a constitutive expression in darkness. Microscope observation showed intact diatom cells and these would, if hatched, represent a significant part of the pelagic phytoplankton biomass. Oxygenation did not significantly change the relative proportion of diatoms nor resulted in any major shifts in metabolic 'signatures'. By contrast, diatoms rapidly responded when exposed to light suggesting that light is limiting diatom development in hypoxic sediments. Hence, it is suggested that diatoms in hypoxic sediments are on 'standby' to exploit the environment if they reach suitable habitats. © 2017 The Author(s).

  16. Seasonal and daily fluctuation of diatoms during spring tide periods in Kerkennah Islands

    Directory of Open Access Journals (Sweden)

    Mounir Ben brahim

    2015-06-01

    Full Text Available Objective: To study seasonal and the daily distribution of diatoms in the three tidal periods (flood, slack and ebb period during the spring tide. Methods: Water samples were taken and environmental variables were measured three times in each tidal period during 10 days of spring tide. Sampling was done in 2007 in Cercina station located in the western coast of Kerkennah (34°41'27'' N; 11°07'45'' E (Southern Tunisia. Results: Nutrients showed significant variation between seasons, increasing in spring and decreasing noticeably in autumn and winter. About 36 diatom species were found. Results revealed a remarkable abundance increase in spring and summer. Irregular differences in diatom abundances were revealed over the tidal periods, with the highest rates being detected during the flood and the ebb period, while the abundance rate was lowest during the slack period. This could presumably be attributed to the increase of nutrient supply of suspended particulate matter during water motion. The results revealed a correlation between diatom abundance and temperature, NO2 - , NO3 - , Si(OH4 and PO4 3 . Temperature seemed to be the most important factors which may influence the distribution and diatom abundance. Conclusions: Tide has various effects on the nutrients status and diatoms community (in terms of species composition, succession and abundance between different tidal periods. Fluctuation of diatoms was correlated with changes in the circulation of water bodies and changes in nutrient regime.

  17. Review--Interactions between diatoms and stainless steel: focus on biofouling and biocorrosion.

    Science.gov (United States)

    Landoulsi, J; Cooksey, K E; Dupres, V

    2011-11-01

    There is a considerable body of information regarding bacterially enhanced corrosion, however, this review focuses on diatoms (unicellular algae) whose contribution to biocorrosion is less well studied. The reasons why diatoms have been neglected in studies of biocorrosion in natural waters are discussed and the question whether diatoms should be considered as inert with respect of electrochemical processes is considered. A particular focus is given to the case of stainless steels (SS), which are widely used in variety of applications in natural waters. Basic information on the cell biology of diatoms is included in the review, particularly with respect to their ability to 'sense' and adhere to surfaces. Investigations at the nanoscale are reviewed as these studies provide information about the behavior of cells at interfaces. Recent advances include the use of atomic force microscopy (AFM), although only a few studies have been applied to diatoms. Regarding the electrochemical behavior of SS, the mechanisms by which diatoms influence the potential ennoblement process is discussed. Such studies reveal the association of diatoms, in addition to bacteria, with biocorrosion processes.

  18. Investigation of the hydrodynamic behavior of diatom aggregates using particle image velocimetry.

    Science.gov (United States)

    Xiao, Feng; Li, Xiaoyan; Lam, Kitming; Wang, Dongsheng

    2012-01-01

    The hydrodynamic behavior of diatom aggregates has a significant influence on the interactions and flocculation kinetics of algae. However, characterization of the hydrodynamics of diatoms and diatom aggregates in water is rather difficult. In this laboratory study, an advanced visualization technique in particle image velocimetry (PIV) was employed to investigate the hydrodynamic properties of settling diatom aggregates. The experiments were conducted in a settling column filled with a suspension of fluorescent polymeric beads as seed tracers. A laser light sheet was generated by the PIV setup to illuminate a thin vertical planar region in the settling column, while the motions of particles were recorded by a high speed charge-coupled device (CCD) camera. This technique was able to capture the trajectories of the tracers when a diatom aggregate settled through the tracer suspension. The PIV results indicated directly the curvilinear feature of the streamlines around diatom aggregates. The rectilinear collision model largely overestimated the collision areas of the settling particles. Algae aggregates appeared to be highly porous and fractal, which allowed streamlines to penetrate into the aggregate interior. The diatom aggregates have a fluid collection efficiency of 10%-40%. The permeable feature of aggregates can significantly enhance the collisions and flocculation between the aggregates and other small particles including algal cells in water.

  19. Pituitary stalk interruption syndrome presenting as short stature: a case report.

    Science.gov (United States)

    Ram, Nanik; Ali, Syed Ahsan; Hussain, Syed Zubair

    2014-12-19

    Pituitary stalk interruption syndrome is a rare congenital abnormality of the pituitary that is responsible for anterior pituitary deficiency. It is characterized by a classic triad of interrupted pituitary stalk, absent or ectopic posterior pituitary, and anterior pituitary hypoplasia or aplasia. Clinical presentation varies according to age. In adults it presents as short stature and anterior pituitary deficiency. Without early diagnosis and treatment, mortality and morbidity in these patients is high. Early diagnosis and treatment of this rare disease can prevent permanent short statue of the patient. We report the first case of pituitary stalk interruption syndrome from Pakistan. A 17-year-old Pakistani young man presented with short stature and underdeveloped secondary sexual characters. His siblings and parents were healthy, with normal height. An examination showed his blood pressure was 90/60 mmHg, and his height, weight, and body mass index were 142 cm, 34.5 kg, and 17.10 kg/m2, respectively. He had no hair growth on his face, axilla, or pubis. His testes were between 1 and 2 mL in size, with a 4 cm-at-stretch micropenis. His lab investigations showed that his thyroid stimulating hormone (TSH) was 8.58 uIU/mL (0.4 to 4.2), his free thyroid hormone level FT4 was 0.46 ng/dL (0.89 to 1.76), his prolactin was 21.1 ng/mL (3.0 to 14.7), and his baseline cortisol was 0.30 ug/dL (4.3 to 22.4). His cortisol level after 60 minutes of cosyntropin injection was 3.5 ug/dL (4.3 to 22.4), his insulin like growth factor IGF-1 was 31.56 ng/mL (247.3 to 481.7), his testosterone level was under 2.5 ng/dL (2 to 800), his follicle stimulating hormone FSH was 0.41 uIU/mL (0.0 to 10.0), and his leutinizing hormone LH was under 0.1 uIU/mL (1.2 to 7.8). His bone age was 10 years according to the Greulich and Pyle method, as shown by X-rays. The results from his pituitary magnetic resonance imaging scan were consistent with pituitary stalk interruption syndrome. We describe a young

  20. Diatom Transcriptional and Physiological Responses to Changes in Iron Bioavailability across Ocean Provinces

    Directory of Open Access Journals (Sweden)

    Natalie R. Cohen

    2017-11-01

    Full Text Available Changes in iron (Fe bioavailability influence diatom physiology and community composition, and thus have a profound impact on primary productivity and ecosystem dynamics. Iron limitation of diatom growth rates has been demonstrated in both oceanic and coastal waters of the Northeast Pacific Ocean and is predicted to become more pervasive in future oceans. However, it is unclear how the strategies utilized by phytoplankton to cope with low Fe bioavailability and resupply differ across these ocean provinces. We investigated the response of diatom communities to variable Fe conditions through incubation experiments performed in the Fe mosaic of the California Upwelling Zone and along a natural Fe gradient in the Northeast Pacific Ocean. Through coupling gene expression of two dominant diatom taxa (Pseudo-nitzschia and Thalassiosira with biological rate process measurements, we provide an in-depth examination of the physiological and molecular responses associated with varying Fe status. Following Fe enrichment, oceanic diatoms showed distinct differential expression of gene products involved in nitrogen assimilation, photosynthetic carbon fixation, and vitamin production compared to diatoms from low-Fe coastal sites, possibly driven by the chronic nature of Fe stress at the oceanic site. Genes of interest involved in Fe and N metabolism additionally exhibited divergent expression patterns between the two diatom taxa investigated, demonstrating that diverse diatoms may invoke alternative strategies when dealing with identical changes in their environment. We report here several mechanisms used distinctly by coastal or oceanic diatom communities as well as numerous taxa-specific strategies for coping with Fe stress and rearranging nutrient metabolism following Fe enrichment.

  1. Diatoms as an indicator for tile drainage flow in a German lowland catchment.

    Science.gov (United States)

    Wu, Naicheng; Faber, Claas; Ulrich, Uta; Fohrer, Nicola

    2018-01-01

    The separation of runoff components within a model simulation is of great importance for a successful implementation of management measures. Diatoms could be a promising indicator for tile drainage flow due to their diverse preferences to different aquatic habitats. In this study, we collected diatom samples of 9 sites (4 tile drainage, TD, and 5 river sites, Ri) in a German lowland catchment at a weekly or biweekly time step from March to July 2013 with the aim of testing the suitability of diatoms for tile drainage flow, which is typical for lowland catchment. Planothidium lanceolatum , Ulnaria biceps , and Navicula gregaria dominated in TD sites with relative abundances of 22.2, 21.5, and 10.9%, respectively. For Ri sites, the most abundant species was Navicula lanceolata (20.5%), followed by Ulnaria biceps (12.9%), Cyclotella meneghiniana (9.5%), and Planothidium lanceolatum (9.3%). Compared with Ri sites, TD had a lower diatom density, biomass, species richness, and percentage of Aquatic/Riparian diatoms (AqRi%). However, the proportion of Riparian diatoms (RiZo%) increased at TD. Indicator value method (IndVal) revealed that the two groups (Ri and TD) were characterized by different indicator species. Fifteen taxa, including Cocconeis placentula , Cyclotella meneghiniana , N. lanceolata , and U. biceps , were significant indicators for Ri sites. Planothidium lanceolatum , Achnanthidium minutissimum , and Navicula gregaria were significant indicators for TD sites. A pronounced variation was found in the species lists of diatom community between Ri and TD water body types associated with different indicator species. With respect to hydrograph separation, these findings highlight the suitability of diatoms as an indicator for tile drainage flow. However, spatial and temporal variations of diatoms should be considered in future surveys.

  2. Extraction of Glucuronoarabinoxylan from Quinoa Stalks (Chenopodium quinoa Willd.) and Evaluation of Xylooligosaccharides Produced by GH10 and GH11 Xylanases.

    Science.gov (United States)

    Salas-Veizaga, Daniel Martin; Villagomez, Rodrigo; Linares-Pastén, Javier A; Carrasco, Cristhian; Álvarez, María Teresa; Adlercreutz, Patrick; Nordberg Karlsson, Eva

    2017-10-04

    Byproducts from quinoa are not yet well explored sources of hemicellulose or products thereof. In this work, xylan from milled quinoa stalks was retrieved to 66% recovery by akaline extraction using 0.5 M NaOH at 80 °C, followed by ethanol precipitation. The isolated polymer eluted as a single peak in size-exclusion chromatography with a molecular weight of >700 kDa. Analysis by Fourier transform infrared spectroscopy and nuclear magnetic resonance (NMR) combined with acid hydrolysis to monomers showed that the polymer was built of a backbone of β(1 → 4)-linked xylose residues that were substituted by 4-O-methylglucuronic acids, arabinose, and galactose in an approximate molar ratio of 114:23:5:1. NMR analysis also indicated the presence of α(1 → 5)-linked arabinose substituents in dimeric or oligomeric forms. The main xylooligosaccharides (XOs) produced after hydrolysis of the extracted glucuronoarabinoxylan polymer by thermostable glycoside hydrolases (GHs) from families 10 and 11 were xylobiose and xylotriose, followed by peaks of putative substituted XOs. Quantification of the unsubstituted XOs using standards showed that the highest yield from the soluble glucuronoarabinoxylan fraction was 1.26 g/100 g of xylan fraction, only slightly higher than the yield (1.00 g/100 g of xylan fraction) from the insoluble fraction (p 0.05). This study shows that quinoa stalks represent a novel source of glucuronoarabinoxylan, with a substituent structure that allowed for limited production of XOs by GH10 or GH11 enzymes.

  3. THE RESPONSE OF THE PERIPHYTIC DIATOM COMMUNITY TO ACID MINE DRAINAGE POLLUTION

    Directory of Open Access Journals (Sweden)

    Andreea Ciorba

    2004-01-01

    Full Text Available This paper proposes to relate the principal characteristics of diatom community (species richness, biodiversity, community biomass, diatom indices to the stress induced by acidification and high levels of metal. The study was done in a mine drainage affected area in Galicia (NW Spain by comparing periphytic diatom communities from polluted streams to ones in supposedly clean waters. The change in the dominant species was the clearest response to AMD pollution while species richness and diversity were sensitive only to high levels of pollution.

  4. Do diatoms percolate through soil and can they be used for tracing the origin of runoff?

    Science.gov (United States)

    De Graaf, Lenka; Cammeraat, Erik; Pfister, Laurent; Wetzel, Carlos; Klaus, Julian; Hissler, Christophe

    2015-04-01

    Tracers are widely used to study the movement of water in a catchment. Because of depletion of scientific possibilities with most common tracer types, we proposed the use of diatoms as a natural tracer. Paradoxical results on the contribution of surface runoff to the storm hydrograph were obtained in pioneer research on this idea. Diatom transport via the subsurface flow to the stream would explain this paradox. Prerequisite for this is vertical transport of diatoms through soils, which is the topic of this study. Emphasis is on percolation behavior (speed of percolation, speed of percolation over time, and species distribution) of Pseudostaurosira sp. and Melosira sp. (Bacillariophyceae) through undisturbed soil columns of contrasting substrates. Co-objective is to study the flowpaths of water through the soil columns. Natural undisturbed soil columns were sampled in the Attert basin (Luxembourg) on schist, marl and sandstone substrates. Rain simulation experiments were performed to study vertical diatom transport. Rhodamine dye experiments were carried out to gain insight in the active flowpaths of water, and breakthrough experiments were performed to study the responses of the soil columns to applied water. Diatoms were transported through the soil columns of the three substrates. A vast majority of diatom percolation took place within the first 15 minutes, percolation hereafter was marginal but nevertheless present. Peaks in diatom percolation corresponded with a high flux caused by the addition of the diatom culture, but seepage of diatoms along the sides is unlikely according to the species distribution and the rhodamine dye experiment. Pseudostaurosira sp. percolated significantly better than Melosira sp. Significantly more diatoms percolated through the marl columns compared to the schist columns and variance within the sandstone group was very high. Absolute differences between substrates however, were marginal. Most preferential flowpaths were observed in

  5. Sorption of 237Pu by the diatom Asterionella formosa

    International Nuclear Information System (INIS)

    Conway, H.L.; Wahlgren, M.A.; Peterson, N.; Nelson, D.M.

    1976-01-01

    Knowledge of the behavior of the man-made radionuclide plutonium within aquatic environments is of fundamental importance in assessing its potential hazards and ecological impact. The sorption of plutonium by phytoplankton and other algae is the dominant factor in the biological transport of plutonium in the aquatic environment, and it has been suggested that sorption by phytoplankton may be responsible for the seasonal loss of plutonium from the epilimnion of Lake Michigan. A unialgal diatom culture was spiked with 237 Pu tracer solution in an attempt to simulate the behavior of fallout plutonium observed in field studies. The results were encouraging in that the 237 Pu in the filtered lake water medium exhibited strongly anionic properties similar to fallout plutonium in Lake Michigan, with limited sorption on container walls. The purpose of the present study was to extend the investigations of the sorption of plutonium by phytoplankton in a controlled environment using continuous culture techniques

  6. TRIGLYCERIDE COMPOSITION OF SIXTEEN STRAINS OF MARINE DIATOM

    Directory of Open Access Journals (Sweden)

    Lily M.G. Panggabean

    2013-07-01

    Full Text Available Trigliceride or triacylglicerol (TAG composition in crude oil of sixteen strain of marine diatom has been detected by spectra analyses on an Electrospray - Ion Trap – Mass Spectrometry (ESI-IT-MS HCT Bruker-Daltonic GmbH instrument with AgNO3 used as coordination ionization agent. Biomass samples of each microalga strain were taken from early and late stationary cultures in f/2 enriched seawater and algal oils were extracted according to Bligh and Dyer. Results from spectra analysis showed that P-Pt-P (C16:0-C16:1-C16:0 were distinguished in TAG from diatom strains Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.1, Thalasiossira sp.2, Thalasiossira sp.3, Navicula sp. 1, Navicula sp. 2, Navicula sp. 3, Navicula sp. 4, Nitzschia sp. 2 and Amphora sp. In contrast, TAGs in Melosira sp. included P-P-P (C16:0-C16:0-C16:0 and P-P-O (C16:0-C16:0-C18:1 were identified. TAGs from Chaetoceros sp. were the most varies among samples, i.e. P-Pt-P (C16:0-C16:1-C16:0, A-P-M (C20:4-C16:0-C14:0, P-Pt-Lt (C16:0-C16:1-C18:3, P-Pt-A (C16:0-C16:1-C20:4, D-P-P (C22:6-C16:0-C16:0, A-Ln-P (C20:4-C18:2-C16:0. Various TAGs were also detected in Nitzschia sp.2, i.e. P-Pt-M (C16:0-C16:1-C14:0, P-Pt-P (C16:0-C16:1-C16:0, P-Pt-S (C16:0-C16:1-C18:0, P-Pt-A (C16:0-C16:1-C20:4. TAGs composition in Skeletonema strains that similar to those in Nitzschia sp.1 has longer carbon, i.e. P-P-O (C16:0-C16:0-C18:1, P-O-O (C16:0-C18:1-C18:1 and O-O-O (C18:1-C18:1-C18:1. TAGs with longer carbon chain and more double bond including highly unsaturated fatty acid C20:4 were increased with culture age in diatoms Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.2, Navicula sp.1 and Nitzschia sp. 2.Keywords: diatom, TAG, ESI-IT-MS, f/2, early and late stationary

  7. Quantum work distribution for a driven diatomic molecule

    International Nuclear Information System (INIS)

    Leonard, Alison; Deffner, Sebastian

    2015-01-01

    Highlights: • A method for calculating the time-dependent solution for a driven system is proposed. • These solutions are used to compute the quantum work distribution. • This distribution is calculated for the Morse potential mimicking a diatomic molecule. • Due to bound and scattering states distribution exhibits continuous and discrete part. • Result is compared with that of a harmonic approximation. - Abstract: We compute the quantum work distribution for a driven Morse oscillator. To this end, we solve the time-dependent dynamics for a scale-invariant process, from which the exact expressions for the transition probabilities are found. Special emphasis is put on the contributions to the work distribution from discrete (bound) and continuous (scattering) parts of the spectrum. The analysis is concluded by comparing the work distribution for the exact Morse potential and the one resulting from a harmonic approximation

  8. Shedding light on diatom photonics by means of digital holography.

    Science.gov (United States)

    Di Caprio, Giuseppe; Coppola, Giuseppe; De Stefano, Luca; De Stefano, Mario; Antonucci, Alessandra; Congestri, Roberta; De Tommasi, Edoardo

    2014-05-01

    Diatoms are among the dominant phytoplankters in the world's oceans, and their external silica investments, resembling artificial photonic crystals, are expected to play an active role in light manipulation. Digital holography allowed studying the interaction with light of Coscinodiscus wailesii cell wall reconstructing the light confinement inside the cell cytoplasm, condition that is hardly accessible via standard microscopy. The full characterization of the propagated beam, in terms of quantitative phase and intensity, removed a long-standing ambiguity about the origin of the light confinement. The data were discussed in the light of living cell behavior in response to their environment. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Nonlinear quantum dynamics in diatomic molecules: Vibration, rotation and spin

    International Nuclear Information System (INIS)

    Yang, Ciann-Dong; Weng, Hung-Jen

    2012-01-01

    Highlights: ► This paper reveals the internal nonlinear dynamics embedded in a molecular quantum state. ► Analyze quantum molecular dynamics in a deterministic way, while preserving the consistency with probability interpretation. ► Molecular vibration–rotation interaction and spin–orbital coupling are considered simultaneously. ► Spin is just the remnant angular motion when orbital angular momentum is zero. ► Spin is the “zero dynamics” of nonlinear quantum dynamics. - Abstract: For a given molecular wavefunction Ψ, the probability density function Ψ ∗ Ψ is not the only information that can be extracted from Ψ. We point out in this paper that nonlinear quantum dynamics of a diatomic molecule, completely consistent with the probability prediction of quantum mechanics, does exist and can be derived from the quantum Hamilton equations of motion determined by Ψ. It can be said that the probability density function Ψ ∗ Ψ is an external representation of the quantum state Ψ, while the related Hamilton dynamics is an internal representation of Ψ, which reveals the internal mechanism underlying the externally observed random events. The proposed internal representation of Ψ establishes a bridge between nonlinear dynamics and quantum mechanics, which allows the methods and tools already developed by the former to be applied to the latter. Based on the quantum Hamilton equations of motion derived from Ψ, vibration, rotation and spin motions of a diatomic molecule and the interactions between them can be analyzed simultaneously. The resulting dynamic analysis of molecular motion is compared with the conventional probability analysis and the consistency between them is demonstrated.

  10. Structure-based optics of centric diatom frustules: modulation of the in vivo light field for efficient diatom photosynthesis.

    Science.gov (United States)

    Goessling, Johannes W; Su, Yanyan; Cartaxana, Paulo; Maibohm, Christian; Rickelt, Lars F; Trampe, Erik C L; Walby, Sandra L; Wangpraseurt, Daniel; Wu, Xia; Ellegaard, Marianne; Kühl, Michael

    2018-07-01

    The optical properties of diatom silicate frustules inspire photonics and nanotechnology research. Whether light interaction with the nano-structure of the frustule also affects diatom photosynthesis has remained unclear due to lack of information on frustule optical properties under more natural conditions. Here we demonstrate that the optical properties of the frustule valves in water affect light harvesting and photosynthesis in live cells of centric diatoms (Coscinodiscus granii). Microscale cellular mapping of photosynthesis around localized spot illumination demonstrated optical coupling of chloroplasts to the valve wall. Photonic structures of the three-layered C. granii valve facilitated light redistribution and efficient photosynthesis in cell regions distant from the directly illuminated area. The different porous structure of the two sides of the valve exhibited photon trapping and forward scattering of blue light enhancing photosynthetic active radiation inside the cell. Photonic structures of diatom frustules thus alter the cellular light field with implications on diatom photobiology. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  11. Teaching Form as Form

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    understanding of form per se, or, to use an expression from this text, of form as form. This challenge can be reduced to one question: how can design teaching support students in achieving not only the ability to recognize and describe different form-related concepts in existing design (i.e. analytical...

  12. Prediction of postoperative diabetes insipidus using morphological hyperintensity patterns in the pituitary stalk on magnetic resonance imaging after transsphenoidal surgery for sellar tumors.

    Science.gov (United States)

    Hayashi, Yasuhiko; Kita, Daisuke; Watanabe, Takuya; Fukui, Issei; Sasagawa, Yasuo; Oishi, Masahiro; Tachibana, Osamu; Ueda, Fumiaki; Nakada, Mitsutoshi

    2016-12-01

    Diabetes insipidus (DI) remains a complication of transsphenoidal surgery (TSS) for sellar and parasellar tumors. Antidiuretic hormone (ADH) appears as hyper intensity (HI) in the pituitary stalk and the posterior lobe of the pituitary gland on T1-weighted magnetic resonance (MR) imaging. Its disappearance from the posterior lobe occurs with DI, indicating a lack of ADH. The appearance of HI in the pituitary stalk indicates disturbances in ADH transport. This retrospective study included 172 patients undergoing TSS for sellar tumors at our institute from 2006 to 2014. Sequential T1-weighted MR images without enhancement were evaluated for HI in the pituitary stalk and the posterior lobe to assess the localization of ADH before and at intervals after TSS. DI was assessed pre- and postoperatively. HI in the pituitary stalk showed the following morphology: (1) ovoid in the distal end of the pituitary stalk (group A), (2) linear in the distal part of the pituitary stalk (group B), (3) linear in the whole pituitary stalk (group C). Preoperative DI occurred in 6 patients (3.5 %) with no HI observed in the posterior lobe. Postoperative DI was transient in 82 patients (47.7 %), and permanent in 11 (6.4 %). One week after surgery, HI was absent in the posterior lobe in 74 patients (43.0 %), and present in the pituitary stalk in 99 patients (57.6 %); both were significantly correlated with postoperative DI (p < 0.001). The absence of HI in the posterior lobe (A, 48.9 %; B, 68.3 %; C, 92.3 %), persistence of DI (A, 3.7 days; B, 45.9 days; C, 20.5 months), and duration until HI recovery in the posterior lobe (A, 3.6 months; B, 6.8 months; C, 22.9 months) were greatest in group C, followed by group B, and then group A. Fourteen group A patients did not have postoperative DI despite having HI in the pituitary stalk and the posterior lobe. Four group C patients developed permanent DI with persistence HI in the pituitary stalk. HI in the pituitary stalk and its

  13. Production of charcoal briquettes from cotton stalk in malawi: methodology for feasibility studies using experiences in Sudan

    NARCIS (Netherlands)

    Onaji, P.B.; Siemons, R.V.

    1993-01-01

    The feasibility of charcoal production from cotton stalks in Malawi was studied based on experience from Sudan. The country relies considerably on biomass fuels. Of the total energy consumption in Malawi of 2.376 MTOE in 1989, 92% was met by biomass (fuelwood: 83.6% and charcoal: 8.3% Petroleum

  14. Registration of an oilseed sunflower germplasm line HA-BSR1 highly tolerant to Sclerotinia basal stalk rot

    Science.gov (United States)

    Basal stalk rot (BSR) caused by Sclerotinia sclerotiorum (Lib.) de Bary is a devastating disease that causes a significant damage to worldwide sunflower (Helianthus annuus L.) production by reducing seed yield and quality. The objective of this research was to develop highly BSR tolerant sunflower g...

  15. 24 CFR 5.2005 - Protection of victims of domestic violence, dating violence, and stalking in public and Section 8...

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Protection of victims of domestic violence, dating violence, and stalking in public and Section 8 housing. 5.2005 Section 5.2005 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development GENERAL HUD PROGRAM REQUIREMENTS; WAIVERS Protection for...

  16. Determining the minimum conditions for soda-anthraquinone pulping of kenaf bast, core, and whole stalk fibers

    Science.gov (United States)

    James S. Han; Thomas A. Rymsza

    1999-01-01

    Chemical pulping of kenaf fiber is comparatively new. In this study, bast, core, and whole stalk kenaf fibers were pulped using a soda-AQ pulping process and various pulping conditions. Handsheets were evaluated for density, Canadian standard freeness, brightness, opacity, smoothness, and tensile, burst, and tear indexes and strength. The results indicate that...

  17. Shea meal and cotton stalk as potential fuels for co-combustion with coal.

    Science.gov (United States)

    Munir, S; Nimmo, W; Gibbs, B M

    2010-10-01

    The efficient management of waste biomass is an important environmental problem in agricultural countries. Often land-fill is the main disposal route with ramifications including CH(4) release having 21 times greater global warming potential per molecule than CO(2). Biomasses are considered to be CO(2)-neutral fuels when combusted. Moreover, they are renewable and covered by the renewable obligation scheme and eligible for certificates in the UK. The overall objective of the investigation is to assess the performance of selected biomass and coal co-firing under two different modes of operation, air-staging and fuel-staging with the benefit of reduced-NO(x) and SO(2) emissions in power plant. The biomasses chosen for the study, shea meal (SM) and cotton stalk (CS) have very different cellulose/lignin compositions and different reported thermal behaviour. A series of experiments have been carried out in a 20 kW, down fired combustor using coal, shea meal-coal and cotton stalk-coal blends under un-staged, air-staged and fuel-staged co-combustion configurations. For air-staging, an optimum value of primary zone stoichiometry SR(1)=0.9 was found. Keeping it fixed, the shea meal and cotton stalk content in the coal-biomass blends was set to 5%, 10% and 15% on thermal basis. NO reductions of 51% and 60% were achieved using SM and CS, respectively, with an optimum thermal biomass blending ratio (BBR) of 10%. The results obtained were compared with un-staged and air-staged results for coal without the addition of biomass. Similarly for fuel-staging, keeping the length of the reburn and burnout zone fixed, SM and CS were evaluated as reductive fuel using different reburn fuel fractions (R(ff)) of 5%, 10%, 15% and 20%. NO reductions of 83% and 84% were obtained with an optimum R(ff) of 15% with an optimum reburn zone stoichiometry of SR(2)=0.8 for both SM and CS, respectively. SO(2) reduction and char burnout efficiency were also evaluated. It was found that addition of

  18. Antifertility effect of betal leaf stalk (Tambul patrabrint): a preliminary experimental study.

    Science.gov (United States)

    Tewari, P V; Chaturvedi, C; Dixit, S N

    1970-01-01

    This study was undertaken to determine possible antifertility properties of the stalk of the betel plant, Piper betle, which is extensively cultivated in warm moist parts of India for its leaves. The thin stalks were dried, powdered, and extracted with alcohol; the residue was used in the study and named betel leaf stalk extract (BLSE). It was macerated with gum acacia, suspended in distilled water, and diluted to 25 mg/ml. The drug was fed by oral intubation. Initially 20 rats were used in 2 groups, one receiving BLSE 50 mg/kg body weight for 10 days and the other vehicle only. Both were caged with males for 15 days. Only 2 of 10 rats receiving BLSE gave birth to litters while 9 of 10 controls delivered. Number of pups was also reduced. In another experiment using 60 female rats to 30 while BLSE at 50 mg/100 gm body weight was fed for 3 days during diestrus to 30 while 30 controls received vehicle only. Successful mating was confirmed by sperm in vaginal smears. 8 of 30 treated rats delivered 3.5 pups each while 29 of 30 controls delivered 7 pups per rat. In a third experiment 10 female rats were given BLSE 50mg/100 gm body weight, 10 vehicle only, and 10 neoclinesterol 150 mcg/100 gm body weight for 4 consecutive days. On Day 5 the animals were sacrificed and weights of uterus and ovaries recorded. Antiestrogenic properties were studied in oophorectomized rats given stilbestrol 150 mcg/100 gm body weight by injection, then fed 150 mcg/100 gm body weight of neoclinesterol or BLSE, 50 mg/100 gm, but the neoclinesterol. Vaginal smears were examined for cornification on Days 2, 3, and 4. Progestational activity was studied in 12 immature female rabbits injected with stilbestrol then treated with BLSE or leutocycline. Tests for estrogenic and antiestrogenic activity of BLSE were negative. A mild progestational activity was found in immature estrogen-primed rabbits but some follicle depressant type action was noted as several graffian follicles were seen in their

  19. Ribosomal RNA analysis indicates a benthic pennate diatom ancestry for the endosymbionts of the dinoflagellates Peridinium foliaceum and Peridinium balticum (Pyrrhophyta).

    Science.gov (United States)

    Chesnick, J M; Kooistra, W H; Wellbrock, U; Medlin, L K

    1997-01-01

    The establishment of chloroplasts as cellular organelles in the dinoflagellate, heterokont (stramenopile), haptophyte, and cryptophyte algae is widely accepted to have been the result of secondary endosymbiotic events, that is, the uptake of a photosynthetic eukaryote by a phagotrophic eukaryote. However, the circumstances that promote such associations between two phylogenetically distinct organisms and result in the integration of their genomes to form a single functional photosynthetic cell is unclear. The dinoflagellates Peridinium foliaceum and Peridinium balticum are unusual in that each contains a membrane-bound eukaryotic heterokont endosymbiont. These symbioses have been interpreted, through data derived from ultrastructural and biochemical investigations, to represent an intermediate stage of secondary endosymbiotic chloroplast acquisition. In this study we have examined the phylogenetic origin of the P. foliaceum and P. balticum heterokont endosymbionts through analysis of their nuclear small subunit ribosomal RNA genes. Our analyses clearly demonstrate both endosymbionts are pennate diatoms belonging to the family Bacillariaceae. Since members of the Bacillariaceae are usually benthic, living on shallow marine sediments, the manner in which establishment of a symbiosis between a planktonic flagellated dinoflagellate and a bottom-dwelling diatom is discussed. In particular, specific environmentally-associated life strategy stages of the host and symbiont, coupled with diatom food preferences by the dinoflagellate, may have been vital to the formation of this association.

  20. Epiphytic diatoms in lotic and lentic waters - diversity and representation of species complexes

    Czech Academy of Sciences Publication Activity Database

    Kollár, J.; Fránková, Markéta; Hašler, P.; Letáková, M.; Poulíčková, A.

    2015-01-01

    Roč. 15, č. 2 (2015), s. 259-271 ISSN 1802-5439 Institutional support: RVO:67985939 Keywords : diatoms * epiphyton * species comlexes * lotic and lentic waters Subject RIV: EF - Botanics Impact factor: 2.026, year: 2015

  1. Relationships between diatoms and tidal environments in Oregon and Washington, USA

    Science.gov (United States)

    Sawai, Yuki; Horton, Benjamin P.; Kemp, Andrew C.; Hawkes, Andrea D.; Nagumo, Tamostsu; Nelson, Alan R.

    2016-01-01

    A new regional dataset comprising 425 intertidal diatom taxa from 175 samples from 11 ecologically diverse Oregon and Washington estuaries illustrates the importance of compiling a large modern dataset from a range of sites. Cluster analyses and detrended correspondence analysis of the diatom assemblages identify distinct vertical zones within supratidal, intertidal and subtidal environments at six of the 11 study sites, but the abundance of some of the most common species varies widely among and within sites. Canonical correspondence analysis of the regional dataset shows relationships between diatom species and tidal exposure, salinity and substratum (grain size and organic content). Correspondence analyses of local datasets show higher values of explained variation than the analysis of the combined regional dataset. Our results emphasize that studies of the autecology of diatom species require many samples from a range of modern environments to adequately characterize species–environment relationships.

  2. Seasonal variations in the fouling diatom community structure from a monsoon influenced tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Anil, A.C.

    Seasonal variations in the fouling diatom community from a monsoon influenced tropical estuary were investigated. The community composition did not differ significantly between stainless steel and polystyrene substrata due to dominance by Navicula...

  3. Morphometry and cell volumes of diatoms from a tropical estuary of India

    Digital Repository Service at National Institute of Oceanography (India)

    RaviKumar, M.S.; Ramaiah, N.; Tang, D.

    Cell volumes and per cell carbon contents of different diatoms (10 centric, 14 pennate and 1 dinoflagellate) collected from Dona Paula Bay in the central west coast of India have been analyzed. Morphometric information on the phytoplankton types...

  4. Effect of holothurian and zoanthid extracts on growth of some bacterial and diatom species

    Digital Repository Service at National Institute of Oceanography (India)

    Gonsalves, C.

    The antifouling properties of the extracts from two zoanthids, viz. Zoanthus sp, Protopalythoa sp and one holothurian species, viz. Holothuria leucospilota occurring in the coastal waters off Goa were tested against 5 bacteria and 2 diatom species...

  5. Effect of chlorination on the development of marine biofilms dominated by diatoms

    Digital Repository Service at National Institute of Oceanography (India)

    Patil, J.S.; Jagadeesan, V.

    , and Thalassionema did not increase in density after chlorine treatment. It was also demonstrated that diatoms can colonize, grow and photosynthesize on chlorine-treated surfaces. Under pulse chlorination (treatment every 6 h), irrespective of chlorine concentration...

  6. An integrative analysis of post-translational histone modifications in the marine diatom Phaeodactylum tricornutum

    KAUST Repository

    Veluchamy, Alaguraj; Rastogi, Achal; Lin, Xin; Lombard, Bé rangè re; Murik, Omer; Thomas, Yann; Dingli, Florent; Rivarola, Maximo; Ott, Sandra; Liu, Xinyue; Sun, Yezhou; Rabinowicz, Pablo D.; McCarthy, James; Allen, Andrew E.; Loew, Damarys; Bowler, Chris; Tirichine, Leï la

    2015-01-01

    in global biogeochemical cycles. Dissecting chromatin-mediated regulation of genes in diatoms will help understand the ecological success of these organisms in contemporary oceans. Results: Here, we use high resolution mass spectrometry to identify a full

  7. Tidal Channel Diatom Assemblages Reflect within Wetland Environmental Conditions and Land Use at Multiple Scales

    Science.gov (United States)

    We characterized regional patterns of the tidal channel benthic diatom community and examined the relative importance of local wetland and surrounding landscape level factors measured at multiple scales in structuring this assemblage. Surrounding land cover was characterized at ...

  8. Influence of land-use patterns on benthic diatom communities and ...

    African Journals Online (AJOL)

    2010-03-01

    Mar 1, 2010 ... for management of Brazilian and other tropical lotic systems. The objective of this ... ity, floods and inundations, which affect diatom development, especially ...... Sociedade Brasileira de Ficologia, CETESB, São Paulo. 34-55.

  9. Phenotypic plasticity of southern ocean diatoms: key to success in the sea ice habitat?

    Directory of Open Access Journals (Sweden)

    Olivia Sackett

    Full Text Available Diatoms are the primary source of nutrition and energy for the Southern Ocean ecosystem. Microalgae, including diatoms, synthesise biological macromolecules such as lipids, proteins and carbohydrates for growth, reproduction and acclimation to prevailing environmental conditions. Here we show that three key species of Southern Ocean diatom (Fragilariopsis cylindrus, Chaetoceros simplex and Pseudo-nitzschia subcurvata exhibited phenotypic plasticity in response to salinity and temperature regimes experienced during the seasonal formation and decay of sea ice. The degree of phenotypic plasticity, in terms of changes in macromolecular composition, was highly species-specific and consistent with each species' known distribution and abundance throughout sea ice, meltwater and pelagic habitats, suggesting that phenotypic plasticity may have been selected for by the extreme variability of the polar marine environment. We argue that changes in diatom macromolecular composition and shifts in species dominance in response to a changing climate have the potential to alter nutrient and energy fluxes throughout the Southern Ocean ecosystem.

  10. New and interesting small-celled naviculoid diatoms (Bacillariophyta) from the Maritime Antarctic Region

    Czech Academy of Sciences Publication Activity Database

    Van de Vijver, B.; Kopalová, Kateřina; Zidarova, R.; Cox, E. J.

    2013-01-01

    Roč. 97, 1-2 (2013), s. 189-208 ISSN 0029-5035 Institutional support: RVO:67985939 Keywords : Bacillariophyta * Diatoms * Maritime Antarctic Region Subject RIV: EF - Botanics Impact factor: 0.989, year: 2013

  11. Identification automatique des diatomées de la Merja fouarate : Une ...

    African Journals Online (AJOL)

    SARAH

    30 sept. 2015 ... Automatic identification of Fouarate Merja diatoms: An alternative to manual determination and classification .... 21 genres, avec une erreur de 4% car plusieurs organismes .... Electronic, Technologies of Information and.

  12. Intracellular nitrate of marine diatoms as a driver of anaerobic nitrogen cycling in sinking aggregates

    DEFF Research Database (Denmark)

    Kamp, Anja; Stief, Peter; Bristow, Laura A.

    2016-01-01

    % was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before...... store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom......-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly...

  13. Autofluorescence imaging system to discriminate and quantify the distribution of benthic cyanobacteria and diatoms

    DEFF Research Database (Denmark)

    Carreira, Cátia; Staal, Marc Jaap; Middelboe, Mathias

    2015-01-01

    successfully to (mixed) laboratory cultures as well as natural photosynthetic microbial mats. Cultures of the diatom Nitzschia capitellata and the cyanobacterium Geitlerinema sp. showed close correlation between autofluorescence and cell abundance. This simple and cheap imaging system allows fast observations...

  14. Aulacoseira kruegeriana (Bacillariophyta, Coscinodiscophyceae): a new centric diatom from high-elevation Andean streams of Bolivia

    Czech Academy of Sciences Publication Activity Database

    Morales, E. A.; Rivera, S. F.; Rubin, S. D. C.; Vis, M. L.; Houk, Václav

    2015-01-01

    Roč. 30, č. 3 (2015), s. 269-277 ISSN 0269-249X Institutional support: RVO:67985939 Keywords : centric diatoms * taxonomy * valve ultrastructure Subject RIV: EF - Botanics Impact factor: 1.868, year: 2015

  15. Diatom species composition in the Raška river (Southwestern Serbia

    Directory of Open Access Journals (Sweden)

    Vidaković Danijela P.

    2015-01-01

    Full Text Available The paper presents data on the composition of epilithic diatoms in the Raška River. Samples were collected by scraping stone surfaces with a brush from 5 localities along the Raška River in April, June, August and November 2011 and March and May 2012. Diatom frustules were cleaned using cold acid method, and mounted on permanent slides. An investigation of the Raška River resulted in description of 106 diatom taxa. The most species rich genera are Navicula (10, Gomphonema (10 and Nitzschia (9, while other genera are presented with one or more species. Detailed floristic analysis of the benthic diatom flora in this river has not been conducted before. Therefore, this paper provides a groundwork for future researches. [Projekat Ministarstva nauke Republike Srbije, br. TR 037009

  16. Diatom production in the marine environment : implications for larval fish growth and condition

    DEFF Research Database (Denmark)

    St. John, Michael; Clemmesen, C.; Lund, T.

    2001-01-01

    To test the effects of diatom production on larval fish growth and condition. laboratory experiments were performed with larval North Sea cod reared on different algal food chains. These food chains were based on cultures of (a) the diatoms Skeletonema costatum and Thalassiosira weissflogii: (b....../omega6 fatty acids in the algal source had no significant effect. The highest and lowest growth rates were observed in food chains based on H. triquetra and T. weissflogii. respectively (means for days 14-16 of 4.0 and - 4.7). The mixed diatom/dinoflagellate diet resulted in inter- mediate growth rates...... and condition. Regressions of growth rates against EPA and DHA content indicated no inhibitory effect of diatom production on growth in larval cod...

  17. Molecular fossils of diatoms. Applications in petroleum geochemistry and palaeoenvironmental studies

    Energy Technology Data Exchange (ETDEWEB)

    Rampen, S.W.

    2009-06-11

    Diatoms are one of the major groups of algae which originated relatively recently and evolved in the Late Jurassic/Cretaceous. This thesis presents the results of a comprehensive study of diatom lipids in cultures and in the environment and their applications in the age determination of petroleum and in palaeoenvironmental studies. Diatom DNA sequences were analyzed in order to relate the phylogenetic positions of diatoms to the lipid chemotaxonomy. Forty four different sterols were identified in diatoms, with 24-methylcholesta-5,24(28)-dien-3-beta-ol being most common. 24-Methylcholesta-5,22E-dien-3-beta-ol, previously described as a diatom biomarker, was only the fifth most common sterol and absent in some major diatom groups. All identified sterols have been reported in other algae, but within the diatoms, some sterols and sterol compositions seem to be specific for specific phylogenetic clusters. Sterol compositions confirmed the separate phylogenetic position of the genus Attheya, as also indicated by molecular phylogeny and microscopy. 23-Methyl and 23,24-dimethyl sterols, often associated with dinoflagellate algae, were present in a substantial number of diatoms, suggesting that diatoms may also be a major source. Their phylogenetic position suggests that these diatoms originated from a single common ancestor which evolved in the late Jurassic. In addition to 23-methyl and 23,24-dimethyl sterols, the unusual sterol gorgosterol was found in two diatom cultures of the genus Delphineis. 24-Norsterols were found in the diatom species Thalassiosira aff. antarctica and in dinoflagellate cultures. The evolutionary history of dinoflagellates and diatoms explains the stepwise increases of 24-norsterane concentrations, diagenetic products of 24-norsterols, in petroleum. Long-chain 1,14-diols and 12-hydroxy methyl alkanoates were detected in Proboscia diatoms and may be used as indicators for high-nutrient conditions and upwelling. Their distributions varied between

  18. Deep carbon export from a Southern Ocean iron-fertilized diatom bloom

    Digital Repository Service at National Institute of Oceanography (India)

    Smetacek, V.; Klaas, C.; Strass, V.H.; Assmy, P.; Montresor, M.; Cisewski, B.; Savoye, N.; Webb, A.; d’Ovidio, F.; Arrieta, J.M.; Bathmann, U.; Bellerby, R.; Berg, G.M.; Croot, P.; Gonzalez, S.; Henjes, J.; Herndl, G.J.; Hoffmann, L.J.; Leach, H.; Losch, M.; Mills, M.M.; Neill, C.; Peeken, I.; Rottgers, R.; Sachs, O.; Sauter, E.; Schmidt, M.M.; Schwarz, J.; Terbruggen, A.; Wolf-Gladrow, D.

    Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately...

  19. Photophysiological variability of microphytobenthic diatoms after growth in different types of culture conditions

    NARCIS (Netherlands)

    Forster, R.M.; Martin-Jézéquel, V.R.

    2005-01-01

    Microphytobenthic diatoms have great ecological importance in estuarine and coastal marine ecosystenis, yet many aspects of their physiology have not been investigated under controlled conditions. This work describes patterns in growth rates and photosynthesis in different types of culture for

  20. The reponse of epilithic diatom assemblages to sewage pollution in mountain streams of the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Moravcová, A.; Rauch, Ota; Lukavský, Jaromír; Nedbalová, Linda

    2013-01-01

    Roč. 146, č. 2 (2013), s. 153-166 ISSN 2032-3913 Institutional support: RVO:67985939 Keywords : epilitic diatoms * mountain streams * sewage polllution Subject RIV: EH - Ecology, Behaviour Impact factor: 0.960, year: 2013