scholarly journals Niche separation between different functional types of mixoplankton: results from NPZ-style N-based model simulations

2019 ◽  
Vol 167 (1) ◽  
Author(s):  
Anna-A Anschütz ◽  
Kevin J. Flynn
Keyword(s):  
Empirical Evidence ◽  
Functional Groups ◽  
Fine Tuning ◽  
Niche Separation ◽  
Mixotrophic Growth ◽  
Model Simulations ◽  
Functional Types ◽  
Salient Features ◽  
Plankton Models

AbstractProtist plankton comprise phytoplankton (incapable of phagotrophy), protozooplankton (incapable of phototrophy) and mixoplankton (capable of phototrophy and phagotrophy). Of these, only phytoplankton and zooplankton are typically described in models. Over the last decade, however, the importance of mixoplankton across all marine biomes has risen to prominence. We thus need descriptions of mixoplankton within marine models. Here we present a simple yet flexible N-based model describing any one of the five basic patterns of protist plankton: phytoplankton, protozooplankton, and the three functional groups of mixoplankton: general non-constitutive mixoplankton (GNCM), specialist non-constitutive mixoplankton (SNCM), and constitutive mixoplankton (CM). By manipulation of a few input switch values, the same model can be used to describe any of these patterns, while adjustment of salient features, such as the percent of C-fixation required for mixotrophic growth, and the rate of phototrophic prey ingestion required to enable growth of GNCM and SNCM types, readily provides fine tuning. Example outputs are presented showing how the performance of these different protist configurations accords with expectations (set against empirical evidence). Simulations demonstrate clear niche separations between these protist functional groups according to nutrient, prey and light resource availabilities. This addition to classic NPZ plankton models provides for the exploration of the implications of mixoplankton activity in a simple yet robust fashion.

scholarly journals Synthesis and Applications of Porphyrin-Biomacromolecule Conjugates

2021 ◽  
Vol 9 ◽  
Author(s):  
Pravin Pathak ◽  
Mohammad Amin Zarandi ◽  
Xiao Zhou ◽  
Janarthanan Jayawickramarajah
Keyword(s):  
Nucleic Acid ◽  
Functional Groups ◽  
Self Assembly ◽  
De Novo ◽  
Solid Phase ◽  
Academic Research ◽  
Fine Tuning ◽  
Cancer Tissue ◽  
Site Specific ◽  
Synthetic Approaches

With potential applications in materials and especially in light-responsive biomedicine that targets cancer tissue selectively, much research has focused on developing covalent conjugation techniques to tether porphyrinoid units to various biomacromolecules. This review details the key synthetic approaches that have been employed in the recent decades to conjugate porphyrinoids with oligonucleotides and peptides/proteins. In addition, we provide succinct discussions on the subsequent applications of such hybrid systems and also give a brief overview of the rapidly progressing field of porphyrin-antibody conjugates. Since nucleic acid and peptide systems vary in structure, connectivity, functional group availability and placement, as well as stability and solubility, tailored synthetic approaches are needed for conjugating to each of these biomacromolecule types. In terms of tethering to ONs, porphyrins are typically attached by employing bioorthogonal chemistry (e.g., using phosphoramidites) that drive solid-phase ON synthesis or by conducting post-synthesis modifications and subsequent reactions (such as amide couplings, hydrazide-carbonyl reactions, and click chemistry). In contrast, peptides and proteins are typically conjugated to porphyrinoids using their native functional groups, especially the thiol and amine side chains. However, bioorthogonal reactions (e.g., Staudinger ligations, and copper or strain promoted alkyne-azide cycloadditions) that utilize de novo introduced functional groups onto peptides/proteins have seen vigorous development, especially for site-specific peptide-porphyrin tethering. While the ON-porphyrin conjugates have largely been explored for programmed nanostructure self-assembly and artificial light-harvesting applications, there are some reports of ON-porphyrin systems targeting clinically translational applications (e.g., antimicrobial biomaterials and site-specific nucleic acid cleavage). Conjugates of porphyrins with proteinaceous moieties, on the other hand, have been predominantly used for therapeutic and diagnostic applications (especially in photodynamic therapy, photodynamic antimicrobial chemotherapy, and photothermal therapy). The advancement of the field of porphyrinoid-bioconjugation chemistry from basic academic research to more clinically targeted applications require continuous fine-tuning in terms of synthetic strategies and hence there will continue to be much exciting work on porphyrinoid-biomacromolecule conjugation.

Emergence of Proactive Self-Initiated Self-Repair as an Indicator of L2 IC Development

2019 ◽  
Vol 41 (6) ◽  
pp. 901-921 ◽  
Author(s):  
Du Re Kim
Keyword(s):  
Second Language ◽  
Empirical Evidence ◽  
Oral Proficiency ◽  
Fine Tuning ◽  
Interactional Competence ◽  
Potential Problems ◽  
Self Repair

Abstract This article finds empirical evidence of second language (L2) interactional competence (IC) and its development by focusing on one of the interactional practices: self-repairing. Compared to prior repair IC studies which mainly have explored how L2 speakers deal with evident L2-related troubles in conversation, this study focuses on cases in which they deploy self-repair when there are no such linguistic problems in previous talk, taking Mauranen’s (2006) dichotomy between retroactive and proactive self-repairs. After analyzing the conversation by L2 speakers with different oral proficiency, this study discovers whereas novice and intermediate speakers self-repair for correcting what is lexically or grammatically problematic, advanced speakers deploy self-repair mostly for pre-empting possible misunderstandings. Advanced speakers replace the previous items into words that are specific in the meaning range by fine-tuning the level of ‘granularity’ (Schegloff 2000) to avoid ambiguity and further other-initiated repair. The findings suggest that the development of L2 IC involves speakers’ ability to detect potential problems in the eyes of the recipients and replace them in advance.

scholarly journals An Arctic Iceberg Deterioration Field Study and Model Simulations

1985 ◽  
Vol 6 ◽  
pp. 195-199 ◽  
Author(s):  
S. Venkatesh ◽  
M. El-Tahan ◽  
P. T. Mitten
Keyword(s):  
Field Study ◽  
Observational Data ◽  
Forced Convection ◽  
Water Wave ◽  
Model Simulations ◽  
Mass Losses ◽  
Salient Features ◽  
Wave Erosion ◽  
Good Agreement

This paper describes the details of a field study on the deterioration of two icebergs grounded outside St John’s harbour in Newfoundland, Canada. Observational data was collected during the period 10-25 June 1983, and included berg-related, meteorological and océanographie data. The study indicated the need for a stable observation platform to enable accurate measurements of iceberg profiles. The observed decay of the two icebergs is compared with simulations from a model that predicts mass losses due to insolation, buoyant vertical convection, forced convection in air and water, wave erosion and calving of the resulting overhanging ice slabs. There was good agreement between observations and model simulations with the model underestimating the mass losses by about ten percent. Other salient features noted during the field study are also discussed.

[3+2] Cycloaddition of N-Aminopyridines and Perfluoroalkynylphosphonates: Facile Synthesis of Perfluoroalkylated Pyrazolo[1,5-a]pyridines Containing a Phosphonate Moiety

Synthesis ◽  
2018 ◽  
Vol 50 (18) ◽  
pp. 3731-3737 ◽  
Author(s):  
Hui Zhang ◽  
Weiguo Cao ◽  
Qi Huang ◽  
Dong He ◽  
Jing Han ◽  
...  
Keyword(s):  
Functional Groups ◽  
Room Temperature ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
Good Tolerance ◽  
Phosphonate Group ◽  
Salient Features ◽  
Operational Simplicity

1,3-Zwitterions generated from N-aminopyridines in the presence of base are trapped by perfluoroalkynylphosphonates to yield a variety of perfluoroalkylated pyrazolo[1,5-a]pyridine derivatives bearing a phosphonate group. The salient features of these [3+2] cycloadditions include operational simplicity, good tolerance of functional groups, and good to excellent yields at room temperature.

Templated Crystallization of Calcite on Patterned Self-Assembled Monolayers

2000 ◽  
Vol 620 ◽  
Author(s):  
Joanna Aizenberg
Keyword(s):  
Functional Groups ◽  
Crystallographic Orientation ◽  
Crystallization Process ◽  
Inorganic Materials ◽  
Fine Tuning ◽  
Self Assembled Monolayers ◽  
Experimental Conditions ◽  
Wide Range ◽  
Assembled Monolayers ◽  
Self Assembled

ABSTRACTMicropatterned self-assembled monolayers (SAMs) that serve as substrates for nucleation provide a way of controlling various aspects of the crystallization process with a previously unreachable precision. We focus on crystallization of calcite (CaCO3) on SAMs of HS(CH2)nX (X = CO2H, CH3, SO3H, OH, N(CH3)3Cl) supported on Ag and Au. Fine-tuning of the crystallographic orientation of the forming crystals has been achieved by using different functional groups and metal substrates. By patterning SAMs with microregions having different nucleating activities and proper geometry, it is possible to confine crystallization to well defined, spatially delineated sites. This method provides means to fabricate arbitrarily patterned calcitic arrays with controlled density of nucleation, crystallographic orientation, and crystal sizes. The experimental conditions and the mechanisms discussed can be applied to the templated nucleation of a wide range of inorganic materials.

scholarly journals An Arctic Iceberg Deterioration Field Study and Model Simulations

1985 ◽  
Vol 6 ◽  
pp. 195-199
Author(s):  
S. Venkatesh ◽  
M. El-Tahan ◽  
P. T. Mitten
Keyword(s):  
Field Study ◽  
Observational Data ◽  
Forced Convection ◽  
Water Wave ◽  
Model Simulations ◽  
Mass Losses ◽  
Salient Features ◽  
Wave Erosion ◽  
Good Agreement

This paper describes the details of a field study on the deterioration of two icebergs grounded outside St John’s harbour in Newfoundland, Canada. Observational data was collected during the period 10-25 June 1983, and included berg-related, meteorological and océanographie data. The study indicated the need for a stable observation platform to enable accurate measurements of iceberg profiles.The observed decay of the two icebergs is compared with simulations from a model that predicts mass losses due to insolation, buoyant vertical convection, forced convection in air and water, wave erosion and calving of the resulting overhanging ice slabs. There was good agreement between observations and model simulations with the model underestimating the mass losses by about ten percent. Other salient features noted during the field study are also discussed.

scholarly journals Understory Plant Functional Types Alter Stoichiometry Correlations between Litter and Soil in Chinese Fir Plantations with N and P Addition

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 742 ◽  
Author(s):  
Junyi Xie ◽  
Haifu Fang ◽  
Qiang Zhang ◽  
Mengyun Chen ◽  
Xintong Xu ◽  
...  
Keyword(s):  
Functional Groups ◽  
Chinese Fir ◽  
Soil N ◽  
Element Cycling ◽  
Soil C ◽  
Understory Plants ◽  
Functional Types ◽  
Stoichiometric Ratios ◽  
Understory Plant ◽  
P Addition

Research Highlights: This study identifies the effect of nitrogen (N) and phosphorus (P) addition on stoichiometry correlations between understory plants and soil in subtropical Chinese fir plantations. Background and Objectives: Nitrogen and P are two nutrients limiting forest ecosystem production. To obtain more wood production, N and P are usually applied in plantation management. Changes in soil N and P will generally alter the stoichiometric characteristics of understory plants, which control carbon (C) and nutrient cycles between plants and soil. However, different correlations between plant and soil stoichiometry among functional groups of understory plants have not been investigated, which also impacted element cycling between plants and soil. Materials and Methods: Subtropical Chinese fir plantations were selected for N (100 kg ha−1 year−1) and P (50 kg ha−1 year−1) addition study. We collected fresh litter and the corresponding soil of four understory plants (Lophatherum gracile Brongn., Woodwardia japonica (L.f.) Sm., Dryopteris atrata (Kunze) Ching and Dicranopteris dichotoma (Thunb.) Berhn.) for study of C, N, and P stoichiometric ratios. Results: Nitrogen and P addition affected C, N, and P concentrations and stoichiometric ratios in litter and soil as well as correlations between litter and soil stoichiometric ratios. Understory plant species with different functional types impacted the correlations between plants and soil in C, N, and P stoichiometric ratios, especially correlations between litter C and soil C and N. Conclusions: Changes in soil N and P affect the stoichiometric ratios of understory plants. Functional groups impacted the correlation in C, N, and P stoichiometric ratios between plants and soil, indicating functional groups varied in their impacts on element cycling between plants and soil in plantations with exogenous nutrient addition, which should be considered in future management of plantations with intensive fertilization practice.

scholarly journals Niche Differentiation of Arsenic-Transforming Microbial Groups in the Rice Rhizosphere Compartments as Impacted by Water Management and Soil-Arsenic Concentrations

2021 ◽  
Vol 12 ◽  
Author(s):  
Anil C. Somenahally ◽  
Richard H. Loeppert ◽  
Jizhong Zhou ◽  
Terry J. Gentry
Keyword(s):  
Water Management ◽  
Functional Groups ◽  
Pore Water ◽  
Microbial Interactions ◽  
Niche Separation ◽  
Rice Grain ◽  
Rice Grains ◽  
Rice Rhizosphere ◽  
Microbial Functional Groups ◽  
Soil Interface

Arsenic (As) bioavailability in the rice rhizosphere is influenced by many microbial interactions, particularly by metal-transforming functional groups at the root-soil interface. This study was conducted to examine As-transforming microbes and As-speciation in the rice rhizosphere compartments, in response to two different water management practices (continuous and intermittently flooded), established on fields with high to low soil-As concentration. Microbial functional gene composition in the rhizosphere and root-plaque compartments were characterized using the GeoChip 4.0 microarray. Arsenic speciation and concentrations were analyzed in the rhizosphere soil, root-plaque, pore water, and grain samples. Results confirmed several As-biotransformation processes in the rice rhizosphere compartments, and distinct assemblage of As-reducing and methylating bacteria was observed between the root-plaque and rhizosphere. Results confirmed higher potential for microbial As-reduction and As-methylation in continuously flooded, long term As-contaminated fields, which accumulated highest concentrations of AsIII and methyl-As concentrations in pore water and rice grains. Water management treatment significantly altered As-speciation in the rhizosphere, and intermittent flooding reduced methyl-As and AsIII concentrations in the pore water, root-plaque and rice grain. Ordination and taxonomic analysis of detected gene-probes indicated that root-plaque and rhizosphere assembled significantly different microbial functional groups demonstrating niche separation. Taxonomic non-redundancy was evident, suggesting that As-reduction, -oxidation and -methylation processes were performed by different microbial functional groups. It was also evident that As transformation was coupled to different biogeochemical cycling processes (nutrient assimilation, carbon metabolism etc.) in the compartments and between treatments, revealing functional non-redundancy of rice-rhizosphere microbiome in response to local biogeochemical conditions and As contamination. This study provided novel insights on As-biotransformation processes and their implications on As-chemistry at the root-soil interface and their responses to water management, which could be applied for mitigating As-bioavailability and accumulation in rice grains.

Chemical Control over Cellular Uptake of Organic Nanoparticles by Fine Tuning Surface Functional Groups

ACS Nano ◽  
2015 ◽  
Vol 9 (10) ◽  
pp. 10227-10236 ◽  
Author(s):  
Yugang Bai ◽  
Hang Xing ◽  
Peiwen Wu ◽  
Xinxin Feng ◽  
Kevin Hwang ◽  
...  
Keyword(s):  
Functional Groups ◽  
Cellular Uptake ◽  
Chemical Control ◽  
Fine Tuning ◽  
Surface Functional Groups ◽  
Organic Nanoparticles

scholarly journals Conflict and Production: An Application to Natural Resources

2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Katharina Wick
Keyword(s):  
Growth Rate ◽  
Natural Resources ◽  
Empirical Evidence ◽  
Resource Curse ◽  
Income Growth ◽  
Resource Abundance ◽  
Resource Rents ◽  
Stackelberg Model ◽  
Salient Features ◽  
Conflict Intensity

Abstract I present a Stackelberg model of conflict, in which contestants have limited endowments to be put in two separate sectors, thus incorporating salient features of many conflicts. The model is applied to the case of conflict over natural resources. Consistent with amounting empirical evidence regarding a so-called "resource curse," I find that the relation between conflict intensity and resource rents is non-monotonous, and that the economy's income growth rate may be negatively affected by resource abundance.

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