Relevant bibliographies by topics / Sieve elements

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Sieve elements'

Author: Grafiati
Published: 4 June 2021
Last updated: 24 February 2023

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Journal articles on the topic "Sieve elements"

1

Rajput, Kishore S., and K. S. Rao. "Occurrence of Sieve Elements in Phloem Rays." IAWA Journal 18, no. 2 (1997): 197–201. http://dx.doi.org/10.1163/22941932-90001479.

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Solitary sieve elements or groups of sieve elements were encountered in the rays of secondary phloem of Erythrina indica, Guazuma tomentosa, Acacia nilotica, Azadirachta indica, and Tectona grandis trees. These elements were short and possessed simple and compound sieve plates on their transverse to slightly oblique end walls. Each sieve tube element was associated with a single companion cell at their comers. Like axial sieve tube elements, the sieve tube elements of the rays showed slime (P-protein) plugs and cytoplasmic strands when functional and massive deposition of callose on sieve plates in nonfunctional sieve tube elements. The distribution pattern of these ray sieve elements differed among the species studied. The detailed structure and possible significance of these elements are discussed.
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Thorsch, Jennifer, and Katherine Esau. "Ultrastructural Aspects of Primary Phloem. Sieve Elements in Poinsettia (Euphorbia Pulcherrima. Euphorbiaceae)." IAWA Journal 9, no. 4 (1988): 363–73. http://dx.doi.org/10.1163/22941932-90001097.

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Certain developmental changes of sieve elements in the primary phloem of Euphorbia pulcherrima Willd. ex Klotsch (Poinsettia) were examined in the leaf blade, petiole and young stem. The sieve elements have simple sieve plates and, as seen in transection, each is associated with a single companion cell . Since, as expected, our fixed material showed a deposition of callose in sieve plates and in the sieve areas joining the sieve elements with the companion cells, the course of development and distribution of this callose was recorded. The sieve elements contain two types of proteinaceous inclusions, both cytoplasmic in origin. One is the typical form of P-protein composed initially of tubular units; later, the tubules become striated fibrils by stretching. The second inclusion is a nondispersing protein body, the first distinct feature identifying the differentiating sieve elements as such. It persists during the differentiation of the cell and is present in mature sieve elements. Aggregated endoplasmic reticulum is rather sparse in sieve elements, but the typical stacked form is occasionally observed in mature cells.
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Hines, P. J. "Removing the nucleus in sieve elements." Science 345, no. 6199 (2014): 886–88. http://dx.doi.org/10.1126/science.345.6199.886-m.

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Hines, P. J. "Removing the Nucleus in Sieve Elements." Science Signaling 7, no. 340 (2014): ec230-ec230. http://dx.doi.org/10.1126/scisignal.2005820.

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van Bel, Aart J. E., Katrin Ehlers, and Michael Knoblauch. "Sieve elements caught in the act." Trends in Plant Science 7, no. 3 (2002): 126–32. http://dx.doi.org/10.1016/s1360-1385(01)02225-7.

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Pizzolato, Thompson Demetrio. "Vascular system of the floret of Phleum pratense." Canadian Journal of Botany 66, no. 9 (1988): 1818–29. http://dx.doi.org/10.1139/b88-248.

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Two bundles occur in the rachilla at the floret base. The anterior bundle supplies the vascular tissue for the lemma median trace, and the posterior supplies that for its two extreme laterals. The intermediate laterals of the lemma connect at the anterior bundle, and the two palea traces join near the posterior bundle to the traces for the extreme lemma laterals. Near these connections sieve elements of the two rachilla bundles link, forming the lower component of the sieve-element plexus. The xylem discontinuity begins above the anterior bundle. An upper, circular component of the sieve-element plexus surrounds the discontinuity. The sieve elements of the lodicules join the anterior of the upper plexus. The upper plexus becomes trilobed as it merges with the stamen traces. Three pistil bundles including sieve elements and tracheary elements of the xylem discontinuity join the upper plexus. These pistil bundles unite into a circular pistil plexus surrounding the discontinuity. The anterior sieve tube of the pistil joins the anterior of the pistil plexus. Sieve elements emerge from the posterolateral portions of the plexus toward the styles and leave a placental bundle of sieve elements and tracheary elements of the xylem discontinuity in the pistil posterior.
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van Bel, Aart J. E., and Michael Knoblauch. "Sieve element and companion cell: the story of the comatose patient and the hyperactive nurse." Functional Plant Biology 27, no. 6 (2000): 477. http://dx.doi.org/10.1071/pp99172.

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Sieve elements and companion cells constitute the modules of the conducting elements in the phloem ofAngiosperms. Consequently, phloem transport basically relies on the concerted action of the sieve element/companion cell complexes. Sieve elements and companion cells are highly interactive units and show an extreme division of labour as exemplified by their state of life. Whereas the sieve element is almost ‘clinically’ dead, the companion cell is a paragon of bubbling activity. In the course of evolution, the sieve element has sacrificed all of its genetic and most of its metabolic equipment to serve photoassimilate translocation. A small part of the structural and metabolic outfit has been retained for a proper accomplishment of its function. In contrast, the cells bordering the sieve element have gained metabolic weight during evolution. With reference to their evolutionary descent, the peculiarities of sieve elements and companion cells are discussed in the light of recent cell-biological and molecular-biological findings. Emphasis is focused on their interaction, which is the secret of the success of the sieve element/companion cell complex.
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Cronshaw, James. "The Fine Structure of Phloem Cells." Proceedings, annual meeting, Electron Microscopy Society of America 43 (August 1985): 632–35. http://dx.doi.org/10.1017/s0424820100119867.

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Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.
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ELEFTHERIOU, E. P. "Microtubules and Sieve Plate Development in Differentiating Protophloem Sieve Elements ofTriticum aestivumL." Journal of Experimental Botany 41, no. 12 (1990): 1507–15. http://dx.doi.org/10.1093/jxb/41.12.1507-a.

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Kalmbach, Lothar, and Ykä Helariutta. "Sieve Plate Pores in the Phloem and the Unknowns of Their Formation." Plants 8, no. 2 (2019): 25. http://dx.doi.org/10.3390/plants8020025.

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Sieve pores of the sieve plates connect neighboring sieve elements to form the conducting sieve tubes of the phloem. Sieve pores are critical for phloem function. From the 1950s onwards, when electron microscopes became increasingly available, the study of their formation had been a pillar of phloem research. More recent work on sieve elements instead has largely focused on sieve tube hydraulics, phylogeny, and eco-physiology. Additionally, advanced molecular and genetic tools available for the model species Arabidopsis thaliana helped decipher several key regulatory mechanisms of early phloem development. Yet, the downstream differentiation processes which form the conductive sieve tube are still largely unknown, and our understanding of sieve pore formation has only moderately progressed. Here, we summarize our current knowledge on sieve pore formation and present relevant recent advances in related fields such as sieve element evolution, physiology, and plasmodesmata formation.
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Dissertations / Theses on the topic "Sieve elements"

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Barnes, Alan Jeffery. "Characterisation of phloem proteins expressed in response to phloem feeding insects." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273995.

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Cayla, Thibaud. "Organisation du phloème et analyse fonctionnelle des protéines PP2." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00856147.

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Le phloème est un tissu complexe composé de plusieurs types cellulaires, dont les cellules compagnes et les tubes criblés. Il permet le transport et l'allocation à longue distance de nombreux métabolites et de macromolécules. Il existe dans les tubes criblés des structures très spécifiques dont la fonction est inconnue. Par exemple le rôle des protéines phloémiennes PP2 (Phloem Protein 2) qui ont été de longue date décrite dans les tubes criblés, reste à définir. Les protéines PP2 présentent une activité de lectine et d'interaction avec des protéines de sève phloémienne, suggérant un rôle dans le transport de macromolécules dans le phloème.Nous avons étudié la fonction de deux membres de la famille, PP2-A1 et PP2-A2, chez l'espèce modèle Arabidopsis thaliana. Plusieurs approches ont été mises en œuvre pour étudier ces protéines ; une approche cytologique, la recherche de partenaire protéiques et la création de lignées dérégulées pour l'expression des gènes PP2. L'étude de la localisation de PP2-A1 avec des étiquettes fluorescentes dérivées de la GFP a été réalisée par microscopie confocale, dans les cellules compagnes et dans les tubes criblés ; elle a montré que cette protéine présente une localisation nucléo- cytoplasmique dans les cellules compagnes tandis qu'elle forme des agrégats fixés dans les tubes criblés. Ceci suggère que PP2-A1 est ancrée dans les tubes criblés, à la membrane plasmique ou à certains organites. Des résultats similaires ont été obtenus pour PP2-A2. Sur la base de cette première étude, nous permettant d'identifier in vivo avec précision les cellules compagnes et les tubes criblés, et en utilisant plusieurs marqueurs subcellulaires fluorescents de référence, nous avons réalisé une cartographie subcellulaire fine des cellules compagnes et des tubes criblés in vivo. Cette approche a permis de décrire in vivo l'organisation subcellulaire de ces cellules. Elle a révélé la présence de nombreux organites présents à la périphérie des tubes criblés et de nature énigmatique, suggérant une activité importante dans ces cellules, en accord avec des données récentes de protéome des tubes criblés. L'étude de lignées surexprimant des versions étiquetées de PP2-A1 et PP2-A2 nous a permis de mettre en évidence un phénotype altéré avec des plantes qui présentent un retard de floraison et une biomasse plus importante. Ces observations suggèrent que PP2-A1 et PP2-A2 pourraient avoir un rôle dans la signalisation à longue distance. Ces travaux, qui illustrent la complexité des cellules du phloème, apportent ainsi des éléments nouveaux sur les voies de signalisation à longue distance utilisées par les végétaux pour coordonner leur croissance et leur développement.
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Alva, Huayaney Miguel Ernesto. "Peligros de origen natural y los elementos esenciales en la ciudad de Huaraz y áreas en expansión en siete distritos aledaños al río Santa, provincias Carhuaz y Huaraz, departamento Áncash – aplicación de la geomática." Master's thesis, Universidad Nacional Mayor de San Marcos, 2020. https://hdl.handle.net/20.500.12672/11678.

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La presente investigación centra sus aportes en el estudio de los niveles de peligro de origen natural como aluviones e inundaciones que amenazan a los elementos esenciales localizados en la ciudad de Huaraz (puentes y recintos como hospitales, colegios, bomberos) y áreas de expansión (puentes, carreteras y el aeropuerto de Anta). Esos elementos son considerados esenciales porque tienen que ver con el normal desarrollo del área urbana. El área de estudio no es ajena a esta situación, ya que históricamente se ha visto afectada por el impacto de eventos geológico-geomorfológicos, tales como aluviones e inundaciones. Es decir, desastres constituidos por cuantiosos daños materiales y la pérdida de vidas humanas, que cambiaron la configuración territorial. La ciudad de Huaraz fue reconstruida en gran parte, sin embargo, en la actualidad viene creciendo en zonas de peligro muy alto a ser de impactada por fenómenos de origen natural.Entre los principios consensuados en la cumbres mundiales sobre la gestión de riesgos de desastres se precisa que la infraestructura y los elementos esenciales deben tenerse en cuenta en los procesos de reducción de riesgos de desastres. Por tal razón, este trabajo será un aporte al esfuerzo que en el país se viene llevando a cabo. La investigación se enmarca en el contexto de la prevención, porque aporta en el análisis de la exposición de los elementos esenciales ante el impacto de los fenómenos de origen natural. Se ha determinado que los puentes y el aeropuerto son los elementos esenciales por ser medios de transporte y rutas de evacuación vitales ante la ocurrencia de desastres.<br>Tesis
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Books on the topic "Sieve elements"

1

Behnke, H. D., and R. D. Sjolund, eds. Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7.

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-D, Behnke H., and Sjolund R. D, eds. Sieve elements: Comparative structure, induction, and development. Springer-Verlag, 1990.

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Thompson, Gary A., and Aart Jan Eeuwe van Bel. Phloem: Molecular cell biology, systemic communication, biotic interactions. Wiley-Blackwell, 2012.

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Guidice, Anthony. Los siete elementos básicos de la carpintería. Edimat Libros, 2001.

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Short, Matthew B. Evaluation of Illinois sieved stream sediment data, 1982-1995: Staff report. State of Illinois, Illinois Environmental Protection Agency, Division of Water Pollution Control, Planning Section, Springfield Monitoring Unit, 1998.

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Wolff, Christian, Freiherr von, 1679-1754, ed. De officiis et virtutibus Christianorum libri tres sive theologiae moralis elementa. G. Olms, 2009.

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Meza Carvajalino, Carlos Arturo, ed. Econometría fundamental. Universidad de La Salle. Ediciones Unisalle, 2014. http://dx.doi.org/10.19052/9789588844213.

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Siempre se ha considerado que por más difícil que les parezca a los estudiantes formalizar los modelos econométricos, mayor es el reto del educador de conseguir que esta técnica sea lo más entendible posible, con el objetivo de despertar en ellos el interés por el conocimiento de lo complejo para comprender lo simple. Por ello, una de las razones principales para escribir este texto fue la de poner a disposición de los alumnos un texto de fácil comprensión del lenguaje formal y brindarles en su proceso algunos elementos fundamentales. El texto está organizado en siete partes y trece capítulos, y está escrito en un lenguaje comprensible, con ejemplos resueltos paso a paso, para que pueda ser consultado por estudiantes de un curso de econometría básica, de econometría intermedia o por aquellos interesados en el tema del análisis econométrico e instrumentos de política y social. De igual manera, va dirigido a los docentes que deseen conocer las diferentes metodologías aplicadas en la formalización econométrica y las formas funcionales de los modelos que se aplican en la investigación económica y social.
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Behnke, H. D., and R. D. Sjolund. Sieve Elements: Comparative Structure, Induction and Development. Springer, 2011.

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Behnke, H. D., and R. D. Sjolund. Sieve Elements: Comparative Structure, Induction and Development. Springer London, Limited, 2012.

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Behnke, H. D. Sieve Elements: Comparative Structure, Induction, and Development. Springer, 1990.

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Book chapters on the topic "Sieve elements"

1

Schmitz, Klaus. "Algae." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_1.

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Schulz, Alexander. "Wound-Sieve Elements." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_10.

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Kollmann, Rainer, and Christl Glockmann. "Sieve Elements of Graft Unions." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_11.

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Dörr, Inge. "Sieve Elements in Haustoria of Parasitic Angiosperms." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_12.

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Cronshaw, James, and Dinkar D. Sabnis. "Phloem Proteins." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_13.

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Taylor, Edith L. "Phloem Evolution: An Appraisal Based on the Fossil Record." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_14.

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Scheirer, Daniel C. "Mosses." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_2.

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Evert, Ray F. "Seedless Vascular Plants." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_3.

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Schulz, Alexander. "Conifers." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_4.

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Behnke, H. Dietmar. "Cycads and Gnetophytes." In Sieve Elements. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-74445-7_5.

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Conference papers on the topic "Sieve elements"

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A.A., Matrosov, Velibekov D.V., and Khara R.I. "NUMERICAL SIMULATION OF COMB OF UPPER GRILL OF COMBINE HARVESTER." In "INNOVATIVE TECHNOLOGIES IN SCIENCE AND EDUCATION". ДГТУ-Принт, 2021. http://dx.doi.org/10.23947/itno.2021.138-139.

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In order to increase strength characteristics of elements of the combine harvester, a comparative calculation of the serial comb of the upper sieve with a similar comb with increased rigidity was made. It is proposed to use another grade of steel, which gives a significant increase in the safety factor in yield strength.
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He, Jian Wen, and Ying Min Low. "Probabilistic Assessment of the Clashing Between Flexible Marine Risers." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20046.

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Flexible marine risers are compliant to external forces from waves, current and platform motions, and clashing between risers is an important concern. In deepwater developments where the number of connected risers is large, it is not economical to space them too far apart. In this regard, it is necessary to establish the probability of riser clashing throughout the service life; however, at present there appears to be no systematic procedure for assessing this risk. This paper presents a novel procedure for estimating the probability of riser clashing based on post-processing results obtained from time domain simulations of flexible risers subjected to random wave loads. First, an efficient technique is employed to sieve out critical pairs among riser elements. From these element pairs, the time history of a normalized clearance parameter is derived from the nodal displacements of the elements. Subsequently, the mean up-crossing rate of this parameter is extracted and extrapolated to the threshold of clashing using extreme value theory. As this method is still in its early developmental stage, critical effects such as vortex-induced vibrations and wake interference will not be considered in the present work.
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Hidayat, Danny, Rantoe Marindha, Triantoro Ade Nugroho, Reyhan Hidayat, and Runi Kusumaning Rusdi. "Hanging Screen Evaluation to Unlock Marginal Sandy Reservoir: Case Study of Peciko Gas Field, Indonesia." In SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205790-ms.

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Abstract Peciko Field currently produces gas from multilayer sand-prone shallow reservoirs. Therefore, it needs sand control method to unlock these marginal reservoirs through low-cost intervention. Hanging screen has been reviewed as an alternative solution to minimize sand control cost while maintaining its robustness to maximize the recovery. This paper will present and evaluate the hanging screen installation and performance from subsurface to surface elements in Peciko field. Hanging screen implementation in Peciko will be evaluated in terms of ease of installation to its performance during production phase. Peciko wells are equipped with real-time monitoring system including Acoustic Sand Detector. Therefore, sand problems could be easily identified. Any indication of screen failure will be confirmed by checking the surface equipment like chokes and intrusive probes. Further intervention to retrieve the screen and perform visual check at surface can be executed to extend the verification. Filter size, placement method, clean-up, and sand sieve result will be gathered to identify the root cause and determine the best method to apply hanging screen as reliable sand control method. Nine installations in 2019 conclude that screen plugging, liquid loading, and combination of both are main issues in production phase. With three plugging cases from well Fx and E2x, it was found that excessive drawdown pressure triggers high gas velocity in perforation tunnel and causing excessive sand production that plugged the screen. These cases also prove that self-unloading by choke movement can lead to plugging if the drawdown pressure and gas rate are not monitored carefully. Commingle production in Ax becomes an issue in lifting performance when reservoir pressure declines and liquid was produced from several reservoirs. Limiting drawdown pressure gives smaller gas rate to lift the liquid and make the well died from liquid loading easily. Massive sand production in well E2x and E2y cause an increase in Top of Sediment (TOS) and lead to inaccessible screen even with multiple bailing attempts. A series of screen design, choke configuration, proper clean-up and continuous monitoring are critical steps to be performed prior and after screen installation to maintain production lifetime. With average stakes of 0.2 Bcf per well, hanging screen has proven to produce 67% of the well reserves in shallow reservoirs. This value creation led to the conclusion that hanging screen is an economically-feasible-sand control method to be implemented in Peciko.
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Jiang, Cong, and Yanhao Chen. "The experiment of the elemental mercury was removed from natural gas by 4A molecular sieve." In ADVANCES IN MATERIALS, MACHINERY, ELECTRONICS II: Proceedings of the 2nd International Conference on Advances in Materials, Machinery, Electronics (AMME 2018). Author(s), 2018. http://dx.doi.org/10.1063/1.5033592.

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Ortiz, Albert R., Juan M. Caicedo, and Dimitris Rizos. "Finite Element Model of High Strength Reduced Modulus High Performance Concrete." In 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5834.

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High Performance Concrete (HPC) with early strength development is the material of choice in the fabrication of prestressed concrete railroad ties. The higher strength of HPC results in significantly higher values of the Elastic Modulus and increases the brittleness and the rigidity of the material, leading to premature cracking and the deterioration of the railroad ties. A High-Strength Reduced-Modulus High Performance Concrete (HSRM-HPC) material has been developed by the authors and used in the fabrication of prototype concrete ties. Detailed models based on the Finite Element Method of the HSRM-HPC have been developed to simulate the ASTM-C469 tests for elastic modulus. The HSRM-HPC constituent materials, i.e. aggregates and cement mortar, have been explicitly modeled and assigned properties determined experimentally. Aggregates size and distribution is modeled using a combination of probabilistic distributions consistent with the results of an experimental sieve analysis. Details of the development of each model are discussed. The models are verified with experimental data. Assessment studies have been performed in order to optimize the models with respect to efficiency, the quality of the results and computational times.
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Liu, Zhong, Wei-Ping Yan, Li Zhao, and Xiao-Min Wang. "Volatiles and Elements Release Characters of Micronized Coal at High Temperature." In ASME 2005 Power Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pwr2005-50338.

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Volatiles and elements release characters are key factors that affect NO reduction efficiency and coal burnout at high temperature. The tested coal was directly taken from the bunkers in a power plant where combusts Shenhua bituminous and Zhunge’er lignite blends (mass ratio is 1:1), the coal blends were re-sieved mechanically and four sizes of them were taken as experimental coals. We designed and constructed char-preparation systems ourselves. The coal and char quality analysis were conducted by Vario el III coal element analyzer, and volatiles release characters under high temperature were analyzed. More volatiles can be released from finer coal under the same conditions. Ash was taken as tracer, volatiles yield in the case of high heating rate in entrained flow reactor is much more that gotten from conventional proximate analysis. Various elements yield increase with the decrease of coal size. Therefore, when finer micronized coal is used as reburning fuel, not only more hydrocarbon roots are produced, but also the combustion characters are improved so that the burnout is improved.
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Seipp, Trevor G. "Case Study: Failure Analysis of a BFJ in Cyclic Service." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28956.

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A bolted flange joint was in cyclic temperature and pressure service in a natural gas dehydrator (mole sieve) vessel. The flange joint suffered from multiple failures on a frequent (9 month) basis. This paper details the investigation into the failure and highlights the most probable cause of failure. A finite element analysis of the pressure and temperature transients in the bolted flange joint pointed to the temperature cycle as tending to unload the joint. Then, a parametric study was undertaken to evaluate the effectiveness of potential solutions. The bolted flange joint was placed back into service and has been operating for more than three times the prior mean time between failures.
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Mahmud, S. M. Naziur, and Debakanta Mishra. "Development of ‘Coarse to Fine Ratio’ As a New Gradation Parameter to Study Ballast Packing." In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6125.

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The Unified Soil Classification System (USCS) uses the 4.75 mm sieve opening size (#4 sieve) as the boundary between ‘coarse’ and ‘fine’ particles. Particles larger than 4.75 mm are classified as ‘coarse’, whereas particles smaller than 4.75 mm are classified as ‘fine’. However, applying these definitions to railroad ballast can be erroneous, as most particles in a ballast material are larger than 4.75 mm (often as large as 63 mm in size), therefore indicating the absence of any ‘fine’ particles. However, depending on relative distribution of particle sizes within a granular matrix, certain particles serve to create voids (coarse fraction), and certain particles serve to fill the voids (fine fraction). Accordingly, rather than using the standard definitions of ‘coarse’ and ‘fine’ particles, as has been done in the literature, the analysis of packing conditions in a ballast matrix may be better served by studying the relative packing between different size fractions. This paper focuses on the development of a new gradation parameter, termed as the “Coarse-to-Fine (C/F) Ratio”, which can shed some light on the importance of different size fractions in a ballast matrix. Changing the ‘coarse’ and ‘fine’ fractions within a particular gradation specification, the resulting effect on ballast shear strength was studied through simulated Direct Shear Strength Tests. A commercially available threedimensional Discrete Element Modeling (DEM) package (PFC3D®) was used for this purpose. Details of the numerical modeling effort are be presented, and inferences are drawn concerning the implications of simulation results on the design and construction of railroad ballast layers.
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Álvarez Gallego, Isabel, and Silvia Blanco Agüeira. "Estrellas sobre fondos cambiantes: convocando la luz." In LC2015 - Le Corbusier, 50 years later. Universitat Politècnica València, 2015. http://dx.doi.org/10.4995/lc2015.2015.980.

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Resumen: Tras crear y desarrollar durante siete años diecinueve poemas manuscritos, que hoy en día son considerados síntesis de su pensamiento, Le Corbusier publicó en 1955 su Poème de l´Angle Droit. Al estudiar este poema reconocemos en él los principales temas presentes en su trayectoria, así como algunos elementos —la espada, la nube y la estrella— que aparecen en su obra pictórica y arquitectónica. La presente comunicación pretende desvelar las conexiones que se establecen entre uno de estos elementos en concreto, como es la imagen de la estrella, y su incorporación al proceso de proyecto lecorbusieriano. Se trata de analizar cómo este tema, que se repite de forma obsesiva, configura imágenes que permanecen en las estrategias arquitectónicas que llevó a cabo el maestro suizo. La estrella habla de faro, de guía, de motor dentro de un proceso de viaje. Es el elemento que representa la movilidad del cosmos, que rige ese carácter de repetición ligado al arte; una señal que guía al viajero y define el itinerario que deben seguir sus pasos, que nos hace pensar en una brillante luz y en la distancia entre lo real y lo imaginado. Y, sobre todo, es la referencia presente en edificios, que condensaban así reflexiones que daban coherencia y unidad a las distintas opciones del proyecto. Abstract: Following a seven year period dedicated to the creation and development of nineteen manuscript poems, which today are considered a synthesis of his thinking, in 1955 Le Corbusier published his Poème de l´Angle Droit. The study of this poem reveals the principal themes that dominated his trajectory, as well as a series of elements, namely the sword, the cloud and the star, which appear in his pictorial and architectural work. This paper aims to shed light on the connections established between one of these elements in particular —the star— and its incorporation into Lecorbuserian method of architectural design. It seeks to analyse how this item is repeated obsessively, forming images which remain rooted in the architectural strategies developed by the Swiss architect. The star speaks of a lighthouse, a guide, a driving force that spurs on the journey. It is the element that represents the mobility of the cosmos, which governs the nature of repetition linked to art; a signal that guides the traveler and traces the route their steps must take them, leading us to think of a bright light and the distance that separates the real and the imagined. And above all, it is the reference in those buildings that condensed the reflections that gave coherence and unity to the various project options. Palabras clave: estrella; cosmos; proyecto; mirada; símbolo; proceso creativo. Keywords: star; cosmos; project; gaze, symbol; creative process. DOI: http://dx.doi.org/10.4995/LC2015.2015.980
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Hussain, Maaruf, Abduljamiu Amao, Khalid Al-Ramadan, Lamidi Babalola, and Hasan Kesserwan. "A Novel Method to Obtain Grain Size Distributions of Intact Rock Samples Using X-Ray Fluorescence Spectra." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-21876-ea.

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Abstract X-ray fluorescence (XRF) is one of the most preferred method preferent methods for elemental analysis and the recent rapid development in spectroscopy has ushered in new ways to look at data generated by most XRF setups beyond the current conventional usage. We hypothesized that particle size and morphology of rock samples can influence fluorescence spectra acquisition. Such interference if analyzed, can unravel new usage for XRF spectra. In this study, we propose the use of raw XRF spectra data for the determination of grain size by superimposition and multiple spectra-cross plots technique. The other known methods of measuring grain size (GS) depending on whether samples are loose or consolidated, include laser granulometry, sieve, and image analyses. Most of these methods have known limitations in their application on an intact rock. The proposed method is designed to address these individual challenges.
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Reports on the topic "Sieve elements"

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Knight, R. D., and B. A. Kjarsgaard. Comparative pXRF and Lab ICP-ES/MS methods for mineral resource assessment, Northwest Territories. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331239.

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The Geological Survey of Canada undertook a mineral resource assessment for a proposed national park in northern Canada (~ 33,500 km2) spanning the transition from boreal forest to barren lands tundra. Bedrock geology of this region is complex and includes the Archean Slave Craton, the Archean and Paleoproterozoic Rae domain of the Churchill Province, the Paleoproterozoic Thelon and Taltson magmatic-tectonic zones, and the Paleoproterozoic East Arm sedimentary basin. The area has variable mineral potential for lode gold, kimberlite-hosted diamonds, VMS, vein uranium and copper, SEDEX, as well as other deposit types. A comparison of analytical methods was carried out after processing the field collected samples to acquire both the &amp;amp;lt; 2 mm and for the &amp;amp;lt; 0.063 mm size fractions for 241 surficial sediment (till) samples, collected using a 10 x 10 km grid. Analytical methods comprised: 1) aqua regia followed by ICP-MS analysis, 2) 4-acid hot dissolution followed by ICP-ES/MS analysis, 3) lithium metaborate/tetraborate fusion methods followed by ICP-ES for major elements and ICP-MS for trace elements and, 4) portable XRF on dried, non-sieved sediment samples subjected to a granular segregation processing technique (to produce a clay-silt proxy) for seventeen elements (Ba, Ca, Cr, Cu, Fe, K, Mn, Ni, Pb, Rb, Sr, Th, Ti, U, V, Zn, and Zr) Results indicate that pXRF data do not replicate exactly the laboratory 4-acid and fusion data (in terms of precision and accuracy), but the relationship between the datasets is systematic as displayed in x-y scattergrams. Interpolated single element plots indicate that till samples with anomalies of high and low pXRF concentration levels are synonymous with high and low laboratory-based analytical concentration levels, respectively. The pXRF interpolations thus illustrate the regional geochemical trends, and most importantly, the significant geochemical anomalies in the surficial samples. These results indicate that pXRF spectrometry for a subset of elements is comparable to traditional laboratory methods. pXRF spectrometry also provides the benefit of rapid analysis and data acquisition that has a direct influence on real time sampling designs. This information facilitates efficient and cost-effective field projects (i.e. where used to identify regions of interest for high density sampling), and to prioritize samples to be analyzed using traditional geochemical methods. These tactics should increase the efficiency and success of a mineral exploration and/or environmental sampling programs.
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Pichon-Riviere, Andrés, Michael Drummond, Sebastián García Martí, and Federico Augustovski. Aplicación de la evidencia económica en la evaluación de tecnologías sanitarias y la toma de decisiones sobre asignación de recursos sanitarios en América Latina: siete temas clave y una propuesta preliminar de implementación. Inter-American Development Bank, 2021. http://dx.doi.org/10.18235/0003649.

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Esta nota técnica discute la aplicación de la evidencia económica en la evaluación de tecnologías sanitarias y la toma de decisiones sobre asignación de recursos sanitarios. En América Latina ya hay hoy un reconocimiento de que las dimensiones económicas de las intervenciones sanitarias, como la costo-efectividad y el impacto presupuestario, son dimensiones críticas que siempre deberían ser tenidas en cuenta al momento de tomar decisiones sobre la cobertura o inclusión de tecnologías en los paquetes de beneficios. Sin embargo, existen barreras y limitaciones que impiden que la evaluación de la evidencia económica en la región sea parte integral de todos los procesos de toma de decisiones, lo que tiene importantes implicancias sobre la equidad y la eficiencia con que son asignados los recursos sanitarios. El objetivo de esta nota técnica es proveer elementos y herramientas que contribuyan, en forma práctica, a superar estas barreras, respondiendo a las preguntas que se hacen los sistemas de salud que están comenzando a aplicar la evidencia económica en sus procesos de evaluación y toma de decisión: ¿Cómo saber si una tecnología o intervención resulta costo-efectiva en mi contexto? ¿Qué umbral de costo-efectividad aplicar? ¿De qué forma podrían influir en mi umbral de costo-efectividad criterios y dimensiones no económicos? ¿Cuál es el límite para considerar que una tecnología representa un alto impacto presupuestario en mi sistema de salud en particular? Dadas las dificultades existentes para generar evidencia económica local, ¿Qué puede decirnos la evidencia económica generada en otras jurisdicciones? ¿Cómo tener en cuenta la evidencia económica en un sistema de salud fragmentado? La consideración de estos aspectos resulta clave para asegurar una asignación más justa y transparente de los recursos sanitarios, y alcanzar así sistemas de salud más eficientes y equitativos en América Latina.
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Wolf, Shmuel, and William J. Lucas. Involvement of the TMV-MP in the Control of Carbon Metabolism and Partitioning in Transgenic Plants. United States Department of Agriculture, 1999. http://dx.doi.org/10.32747/1999.7570560.bard.

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The function of the 30-kilodalton movement protein (MP) of tobacco mosaic virus (TMV) is to facilitate cell-to-cell movement of viral progeny in infected plants. Our earlier findings have indicated that this protein has a direct effect on plasmodesmal function. In addition, these studies demonstrated that constitutive expression of the TMV MP gene (under the control of the CaMV 35S promoter) in transgenic tobacco plants significantly affects carbon metabolism in source leaves and alters the biomass distribution between the various plant organs. The long-term goal of the proposed research was to better understand the factors controlling carbon translocation in plants. The specific objectives were: A) To introduce into tobacco and potato plants a virally-encoded (TMV-MP) gene that affects plasmodesmal functioning and photosynthate partitioning under tissue-specific promoters. B) To introduce into tobacco and potato plants the TMV-MP gene under the control of promoters which are tightly repressed by the Tn10-encoded Tet repressor, to enable the expression of the protein by external application of tetracycline. C) To explore the mechanism by which the TMV-MP interacts with the endogenous control o~ carbon allocation. Data obtained in our previous project together with the results of this current study established that the TMV-MP has pleiotropic effects when expressed in transgenic tobacco plants. In addition to its ability to increase the plasmodesmal size exclusion limit, it alters carbohydrate metabolism in source leaves and dry matter partitioning between the various plant organs, Expression of the TMV-MP in various tissues of transgenic potato plants indicated that sugars and starch levels in source leaves are reduced below those of control plants when the TMV-MP is expressed in green tissue only. However, when the TMV-MP was expressed predominantly in PP and CC, sugar and starch levels were raised above those of control plants. Perhaps the most significant result obtained from experiments performed on transgenic potato plants was the discovery that the influence of the TMV-MP on carbohydrate allocation within source leaves was under developmental control and was exerted only during tuber development. The complexity of the mode by which the TMV-MP exerts its effect on the process of carbohydrate allocation was further demonstrated when transgenic tobacco plants were subjected to environmental stresses such as drought stress and nutrients deficiencies, Collectively, these studies indicated that the influence of the TMV-MP on carbon allocation L the result of protein-protein interaction within the source tissue. Based on these results, together with the findings that plasmodesmata potentiate the cell-to-cell trafficking of viral and endogenous proteins and nucleoproteins complexes, we developed the theme that at the whole plant level, the phloem serves as an information superhighway. Such a long-distance communication system may utilize a new class of signaling molecules (proteins and/or RNA) to co-ordinate photosynthesis and carbon/nitrogen metabolism in source leaves with the complex growth requirements of the plant under the prevailing environmental conditions. The discovery that expression of viral MP in plants can induce precise changes in carbon metabolism and photoassimilate allocation, now provide a conceptual foundation for future studies aimed at elucidating the communication network responsible for integrating photosynthetic productivity with resource allocation at the whole-plant level. Such information will surely provide an understanding of how plants coordinate the essential physiological functions performed by distantly-separated organs. Identification of the proteins involved in mediating and controlling cell-to-cell transport, especially at the companion cell-sieve element boundary, will provide an important first step towards achieving this goal.
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