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Structure and Function of Chloroplasts

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889457137 Year: Pages: 279 DOI: 10.3389/978-2-88945-713-7 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Botany
Added to DOAB on : 2019-01-23 14:53:43
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Chloroplasts are plant cell organelles that convert light energy into relatively stable chemical energy via the photosynthetic process. By doing so, they sustain life on Earth. Chloroplasts also provide diverse metabolic activities for plant cells, including the synthesis of fatty acids, membrane lipids, isoprenoids, tetrapyrroles, starch, and hormones. The biogenesis, morphogenesis, protection and senescence of chloroplasts are essential for maintaining a proper structure and function of chloroplasts, which will be the theme of this Research Topic. Chloroplasts are enclosed by an envelope of two membranes which encompass a third complex membrane system, the thylakoids, including grana and lamellae. In addition, starch grains, plastoglobules, stromules, eyespots, pyrenoids, etc. are also important structures of chloroplasts. It is widely accepted that chloroplasts evolved from a free-living photosynthetic cyanobacterium, which was engulfed by a eukaryotic cell. Chloroplasts retain a minimal genome, most of the chloroplast proteins are encoded by nuclear genes and the gene products are transported into the chloroplast through complex import machinery. The coordination of nuclear and plastid genome expressions establishes the framework of both anterograde and retrograde signaling pathways. As the leaf develops from the shoot apical meristem, proplastids and etioplastids differentiate into chloroplasts. Chloroplasts are divided by a huge protein complex, also called the plastid-dividing (PD) machinery, and their division is also regulated by many factors to get an optimized number and size of chloroplasts in the cell. These processes are fundamental for the biogenesis and three-dimensional dynamic structure of chloroplasts.During the photosynthesis, reactive oxygen species (ROS) and other cellular signals can be made. As an important metabolic hub of the plant cell, the chloroplast health has been found critical for a variety of abiotic and biotic stresses, including drought, high light, cold, heat, oxidative stresses, phosphate deprivation, and programmed cell death at sites of infection. Therefore, a better understanding the responses of chloroplasts to these stresses is part of knowing how the plant itself responds. Ultimately, this knowledge will be necessary to engineer crops more resistant to common stresses.With the current global environment changes, world population growth, and the pivotal role of chloroplasts in carbon metabolism, it is of great significance to represent the advancement in this field, for science and society. Tremendous progresses have been made in the field of chloroplast biology in recent years. Through concerted efforts from the community, greater discoveries definitely will emerge in the future.

The Bacterial Cell: Coupling between Growth, Nucleoid Replication, Cell Division and Shape

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198177 Year: Pages: 324 DOI: 10.3389/978-2-88919-817-7 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2016-01-19 14:05:46
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Bacterial Physiology was inaugurated as a discipline by the seminal research of Maaløe, Schaechter and Kjeldgaard published in 1958. Their work clarified the relationship between cell composition and growth rate and led to unravel the temporal coupling between chromosome replication and the subsequent cell division by Helmstetter et al. a decade later. Now, after half a century this field has become a major research direction that attracts interest of many scientists from different disciplines. The outstanding question how the most basic cellular processes - mass growth, chromosome replication and cell division - are inter-coordinated in both space and time is still unresolved at the molecular level. Several particularly pertinent questions that are intensively studied follow: (a) what is the primary signal to place the Z-ring precisely between the two replicating and segregating nucleoids? (b) Is this coupling related to the structure and position of the nucleoid itself? (c) How does a bacterium determine and maintain its shape and dimensions? Possible answers include gene expression-based mechanisms, self-organization of protein assemblies and physical principles such as micro-phase separations by excluded volume interactions, diffusion ratchets and membrane stress or curvature. The relationships between biochemical reactions and physical forces are yet to be conceived and discovered. This e-book discusses the above mentioned and related questions. The book also serves as an important depository for state-of-the-art technologies, methods, theoretical simulations and innovative ideas and hypotheses for future testing. Integrating the information gained from various angles will likely help decipher how a relatively simple cell such as a bacterium incorporates its multitude of pathways and processes into a highly efficient self-organized system. The knowledge may be helpful in the ambition to artificially reconstruct a simple living system and to develop new antibacterial drugs.

Energy and Seismic Renovation Strategies for Sustainable Cities

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ISBN: 9783038979449 / 9783038979456 Year: Pages: 250 DOI: 10.3390/books978-3-03897-945-6 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Arts in general --- Architecture
Added to DOAB on : 2019-06-26 09:16:44
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The principle of sustainability should be strictly connected with safety, since both aim to conserve resources: in the case of sustainability, the resources are typically thought of as environmental, while in the case of safety, the resources are basically human. In spite of this common ground, discussions on sustainability usually give insufficient attention to safety. In the last years the EU has made large investments to increase the energy efficiency of the existing building stock, paving the way for a low-carbon future; however, less effort has been made to enhance its seismic resilience. Therefore, the safety and, consequently, the sustainability of towns situated in earthquake-prone countries remain inadequate. In such countries, energy renovation actions should be combined with seismic retrofitting. However, a number of barriers considerably limit the real possibility of extensively undertaking combined retrofit actions, especially for multi-owner housing and high-rise buildings. These barriers are of different kinds: technical (e.g., unfeasibility and/or ineffectiveness of conventional retrofit solutions), financial (e.g., high renovation costs, insufficient incentives/subsidies), organizational (e.g., occupants’ disruption and relocation, renovation consensus by condominium ownerships), and cultural/social (insufficient information and skills, lack of adequate policy measures for promoting renovation actions). This book aims to overcome these barriers and to bridge the gap between sustainability and safety, so to conserve both human and environmental resources.

Asymmetric Planetary Nebulae VII

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ISBN: 9783038976400 Year: Pages: 204 DOI: 10.3390/books978-3-03897-641-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Physics (General) --- Astronomy (General)
Added to DOAB on : 2019-03-21 14:08:22
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This book contains the best and most up-to-date contributions in the field of late stage stellar evolution, as presented at the APNVII conference in Hong Kong in December 2017. A total of 60 scientists from 20 countries gathered to present, listen, interact and discuss the most current issues and problems in planetary nebulae and related objects research. The emphasis of this influential series of meetings, which was the seventh occasion over the last 20 years, has always been on the hypothesized and observed physical shaping mechanisms of the ejected nebulae that have such wonderful and intriguing forms. This special Galaxies conference issue of fully refereed contributions brings together a representative compilation of the meeting presentations in paper form. It captures the current “snap shot” status of this research field in some real sense. Such proceedings are well received and can be used as a reference material by both participants and all others working in the field for years to come.

Keywords

planetary systems --- planetary nebulae --- stars: binaries --- stars: AGB and post-AGB --- stars: variables: general --- stars: abundances --- stars: AGB and post-AGB --- stars: atmospheres --- stars: individual: WD 0044–121 --- stars: individual: WD 2134+25 --- stars: individual: WD 1751+106 --- planetary nebulae --- asymptotic giant branch stars --- mass loss --- infra-red --- planetary nebulae --- integral field spectroscopy --- stellar evolution --- binarity --- planetary nebulae --- stellar mass loss --- stellar evolution --- planetary nebulae --- circumstellar dust --- planetary nebulae --- mass-loss --- stellar evolution --- X-rays --- stellar evolution --- late stage stellar evolution --- binarity: transients: planetary nebulae --- planetary nebulae --- stars: AGB and post-AGB --- late stage stellar evolution --- planetary nebulae --- stars: binaries --- central stars of planetary nebulae --- proto-planetary nebulae --- binaries: spectroscopic --- stars: atmospheres --- stars: abundances --- supernovae --- late stage stellar evolution --- planetary nebulae --- binarity --- stellar evolution --- AGB and post-AGB stars --- circumstellar matter --- winds and outflows --- mass-loss --- jets --- binaries: close --- stars: AGB and post-AGB --- stars: winds, outflows --- ISM: jets and outflows --- binary stars --- post-AGB --- discs --- planetary nebula --- X-ray --- stellar evolution --- AGB stars --- post-AGB stars --- planetary nebulae --- planetary nebulae --- fullerenes --- planetary nebulae --- AGB and post-AGB stars --- binarity --- accretion disks --- jets --- mass-loss --- circumstellar matter --- (sub)millimeter interferometry --- ultraviolet radiation, X-rays --- infrared interferometry --- AGB stars --- stellar evolution --- observations --- aperture masking --- planetary nebulae --- binarity --- abundances --- stellar evolution --- post-AGB stars --- pre-PN hydrodynamic models --- planetary nebulae: Common Envelope --- planetary nebulae: individual (OH231+8+04.2) --- astrochemistry --- planetary nebulae --- UIE bands --- normal modes --- displacement vectors --- late-stage stellar evolution --- planetary nebulae --- multi-wavelength photometry --- radial velocity --- stellar evolution --- pulsation --- shock wave --- late stage stellar evolution --- planetary nebulae --- theory and observation --- planetary nebulae --- AGB and post-AGB --- interstellar medium --- radio continuum --- winds --- outflows --- dust --- extinction --- ISM: abundances --- planetary nebulae: individual (NGC 6781)

Recent Advances in Urban Ventilation Assessment and Flow Modelling

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ISBN: 9783038978060 9783038978077 Year: Pages: 448 DOI: 10.3390/books978-3-03897-807-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General)
Added to DOAB on : 2019-04-25 16:37:17
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This book contains twenty-one original papers and one review paper published by internationally recognized experts in the Atmosphere Special Issue ""Recent Advances in Urban Ventilation Assessment and Flow Modelling"", years 2017–2019. The Special Issue includes contributions on recent experimental and modelling works, techniques, and developments mainly tailored to the assessment of urban ventilation on flow and pollutant dispersion in cities. The study of ventilation is of critical importance, as it addresses the capacity with which a built urban structure is capable of replacing the polluted air with ambient fresh air. Here, ventilation is recognized as a transport process that improves local microclimate and air quality and closely relates to the term “breathability”. The efficiency with which street canyon ventilation occurs depends on the complex interaction between the atmospheric boundary layer flow and the local urban morphology.The individual contributions to this Issue are summarized and categorized into four broad topics: (1) outdoor ventilation efficiency and application/development of ventilation indices, (2) relationship between indoor and outdoor ventilation, (3) effects of urban morphology and obstacles to ventilation, and (4) ventilation modelling in realistic urban districts. The results and approaches presented and proposed will be of great interest to experimentalists and modelers, and may constitute a starting point for the improvement of numerical simulations of flow and pollutant dispersion in the urban environment, for the development of simulation tools, and for the implementation of mitigation strategies.

Keywords

street canyon --- seasonal variation --- air flow --- pollutant dispersion --- pollutant removal --- natural ventilation --- residential wind environments --- building arrangements --- space pattern --- ventilation efficiency --- CFD simulation --- air change rate (ACH) --- flow and turbulence profiles --- hypothetical urban areas --- street-level ventilation --- ventilation assessment --- wind-tunnel dataset --- street vegetation --- CFD --- aerodynamic and deposition --- tree scenarios --- urban planning --- indoor-outdoor --- mass concentration --- nanoparticles --- particle number concentration (PNC) --- PM10 --- PM2.5 --- sampling --- Total Suspended Particles (TSP) --- ultrafine particles (UFP) --- urban street canyon --- wind enhancement --- architectural intervention --- water channel experiment --- CFD simulation --- passive ventilation --- street canyon --- computational fluid dynamics (CFD) --- ventilation effectiveness --- the age of air --- convective boundary layer --- LES --- street-level ventilation --- small open space --- air change rate per hour (ACH) --- concentration decay method --- urban age of air --- computational fluid dynamic (CFD) simulation --- natural ventilation --- residential building --- climate zone --- thermal comfort --- natural ventilation hour --- Japan cities --- building energy use --- inter-building effect --- highly-reflective building envelope --- BEopt analysis --- source apportionment --- data assimilation --- urban air quality modelling --- wind environment --- Natural Ventilation Potential (NVP) --- PM2.5 --- building–tree grouping patterns --- Computational Fluid Dynamics (CFD) --- LES --- ventilation --- urban planning --- dispersion --- air quality --- street canyon --- traffic tidal flow --- numerical simulation --- vehicular pollution --- non-uniform distribution of the pollution source --- on-road air quality --- traffic composition --- high emitting vehicles --- street canyon --- mobile laboratory --- CFD model --- heat loss --- optimisation --- residential building --- air quality --- carbon dioxide concentration --- ventilation system --- wind pressure coefficient --- airflow network --- multiple linear regression --- natural ventilation --- urban layout --- surrogate model --- schematic urban environment --- wind tunnel --- LES --- validation --- street canyon --- coherent structures --- road tunnel --- natural ventilation --- wind catcher --- intake fraction --- street canyon --- CFD --- Large Eddy Simulation (LES) --- urban air quality --- pedestrian exposure --- concentration fluctuation --- outdoor ventilation --- urban morphology --- building site coverage --- ventilation efficiency --- n/a

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