Responses of Percid Fishes and Their Habitats to Eutrophication

1977 ◽  
Vol 34 (10) ◽  
pp. 1964-1971 ◽  
Author(s):  
J. H. Leach ◽  
M. G. Johnson ◽  
J. R. M. Kelso ◽  
J. Hartmann ◽  
W. Nümann ◽  
...  
Keyword(s):  
Physicochemical Characteristics ◽  
Habitat Modification ◽  
Trophic Conditions ◽  
Relative Level ◽  
Cultural Eutrophication ◽  
Fish Yield ◽  
Species Dominance ◽  
Wide Range ◽  
Selective Mechanism ◽  
The Continuum

Percid fishes are found in lakes that cover a wide range of trophic conditions. The responses of percids and their habitats to progressive cultural eutrophication are predictable. Alterations in physicochemical characteristics of habitats precipitate changes in phytoplankton, macrophytes, zooplankton, and benthos that are ultimately deleterious. Enrichment can lead to favorable responses in percids, but somewhere in the continuum of trophic conditions the responses become unfavorable. The relative level at which the response becomes negative varies with the species according to tolerances to altered environment, adaptabilities to new habitat and forage base, and reproductive behavior. Progressive eutrophication acts as a selective mechanism that leads to a predictable sequence of fish species. Other perturbations, such as exploitation and habitat modification, can act synergistically with cultural eutrophication in accelerating the sequence. As eutrophication proceeds, the succession of species may not lead to increased fish yield because part of the nutrient load may be channeled through unharvestable food chains. Key words: Percidae, habitat, eutrophication, species dominance, food habits, parasitism, disease

Pharmaceutical Co-Crystals - Design, Development and Applications

2020 ◽  
Vol 10 (3) ◽  
pp. 169-184
Author(s):  
Rachna Anand ◽  
Arun Kumar ◽  
Arun Nanda
Keyword(s):  
Physicochemical Properties ◽  
Crystal Engineering ◽  
Pharmacological Action ◽  
Physicochemical Characteristics ◽  
Research Area ◽  
Dissolution Profile ◽  
Design Development ◽  
Drug Molecule ◽  
Wide Range ◽  
Major Factors

Background: Solubility and dissolution profile are the major factors which directly affect the biological activity of a drug and these factors are governed by the physicochemical properties of the drug. Crystal engineering is a newer and promising approach to improve physicochemical characteristics of a drug without any change in its pharmacological action through a selection of a wide range of easily available crystal formers. Objective: The goal of this review is to summarize the importance of crystal engineering in improving the physicochemical properties of a drug, methods of design, development, and applications of cocrystals along with future trends in research of pharmaceutical co-crystals. Co-crystallization can also be carried out for the molecules which lack ionizable functional groups, unlike salts which require ionizable groups. Conclusion: Co-crystals is an interesting and promising research area amongst pharmaceutical scientists to fine-tune the physicochemical properties of drug materials. Co-crystallization can be a tool to increase the lifecycle of an older drug molecule. Crystal engineering carries the potential of being an advantageous technique than any other approach used in the pharmaceutical industry. Crystal engineering offers a plethora of biopharmaceutical and physicochemical enhancements to a drug molecule without the need of any pharmacological change in the drug.

scholarly journals Continuum modeling perspectives of non-Fourier heat conduction in biological systems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ákos Sudár ◽  
Gergely Futaki ◽  
Róbert Kovács
Keyword(s):  
Biological Systems ◽  
Phase Lag ◽  
Dual Phase ◽  
Continuum Modeling ◽  
Biological Origin ◽  
Ultrasound Surgery ◽  
Thermal Models ◽  
Wide Range ◽  
Fourier Heat Conduction ◽  
The Continuum

Abstract The thermal modeling of biological systems is increasingly important in the development of more advanced and more precise techniques such as ultrasound surgery. One of the primary barriers is the complexity of biological materials: the geometrical, structural, and material properties vary in a wide range. In the present paper, we focus on the continuum modeling of heterogeneous materials of biological origin. There are numerous examples in the literature for non-Fourier thermal models. However, as we realized, they are associated with a few common misconceptions. Therefore, we first aim to clarify the basic concepts of non-Fourier thermal models. These concepts are demonstrated by revisiting two experiments from the literature in which the Cattaneo–Vernotte and the dual phase lag models are utilized. Our investigation revealed that these non-Fourier models are based on misinterpretations of the measured data, and the seeming deviation from Fourier’s law originates from the source terms and boundary conditions.

scholarly journals Chromosomal Locus That Affects Pathogenicity of Rhodococcus fascians

2002 ◽  
Vol 184 (4) ◽  
pp. 1112-1120 ◽  
Author(s):  
Danny Vereecke ◽  
Karen Cornelis ◽  
Wim Temmerman ◽  
Mondher Jaziri ◽  
Marc Van Montagu ◽  
...  
Keyword(s):  
Krebs Cycle ◽  
Malate Synthase ◽  
Habitat Modification ◽  
Signal Molecules ◽  
In Planta ◽  
Chromosomal Locus ◽  
Physiological Alterations ◽  
Rhodococcus Fascians ◽  
Wide Range ◽  
Symptomatic Tissue

ABSTRACT The gram-positive plant pathogen Rhodococcus fascians provokes leafy gall formation on a wide range of plants through secretion of signal molecules that interfere with the hormone balance of the host. Crucial virulence genes are located on a linear plasmid, and their expression is tightly controlled. A mutant with a mutation in a chromosomal locus that affected virulence was isolated. The mutation was located in gene vicA, which encodes a malate synthase and is functional in the glyoxylate shunt of the Krebs cycle. VicA is required for efficient in planta growth in symptomatic, but not in normal, plant tissue, indicating that the metabolic requirement of the bacteria or the nutritional environment in plants or both change during the interaction. We propose that induced hyperplasia on plants represents specific niches for the causative organisms as a result of physiological alterations in the symptomatic tissue. Hence, such interaction could be referred to as metabolic habitat modification.

scholarly journals Blocking of Bacterial Biofilm Formation by a Fish Protein Coating

2008 ◽  
Vol 74 (11) ◽  
pp. 3551-3558 ◽  
Author(s):  
Rebecca Munk Vejborg ◽  
Per Klemm
Keyword(s):  
Biofilm Formation ◽  
Fish Muscle ◽  
Physicochemical Characteristics ◽  
Economic Problem ◽  
Bacterial Attachment ◽  
Bacterial Biofilm ◽  
Adhesive Properties ◽  
Muscle Extract ◽  
Wide Range ◽  
Inert Surfaces

ABSTRACT Bacterial biofilm formation on inert surfaces is a significant health and economic problem in a wide range of environmental, industrial, and medical areas. Bacterial adhesion is generally a prerequisite for this colonization process and, thus, represents an attractive target for the development of biofilm-preventive measures. We have previously found that the preconditioning of several different inert materials with an aqueous fish muscle extract, composed primarily of fish muscle α-tropomyosin, significantly discourages bacterial attachment and adhesion to these surfaces. Here, this proteinaceous coating is characterized with regards to its biofilm-reducing properties by using a range of urinary tract infectious isolates with various pathogenic and adhesive properties. The antiadhesive coating significantly reduced or delayed biofilm formation by all these isolates under every condition examined. The biofilm-reducing activity did, however, vary depending on the substratum physicochemical characteristics and the environmental conditions studied. These data illustrate the importance of protein conditioning layers with respect to bacterial biofilm formation and suggest that antiadhesive proteins may offer an attractive measure for reducing or delaying biofilm-associated infections.

The Supportive–Expressive Continuum

2019 ◽  
pp. 52-61
Author(s):  
Brian A. Sharpless
Keyword(s):  
Psychodynamic Therapy ◽  
Expressive Therapies ◽  
Clinical Indicators ◽  
Negative Patient ◽  
Wide Range ◽  
The Continuum

Psychodynamic therapy can be flexibly applied to a wide range of psychopathology. However, different patient problems imply different techniques. If inappropriate interventions are used, therapy progress could stall or negative patient events could occur. A useful tool for selecting the best mix of psychodynamic techniques is the supportive–expressive continuum. When patients are properly situated on this continuum, it is far easier to choose interventions. After the different intentions of the more purely supportive or expressive therapies are described, the clinical indicators for each approach are listed. Finally, patient transitions along the continuum (i.e., they require a different mix of supportive and expressive techniques) are discussed with suggestions on how to make these changes while minimizing therapy disruptions.

scholarly journals Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece

Hydrology ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 22
Author(s):  
Konstantinos Stefanidis ◽  
Anna Latsiou ◽  
Theodora Kouvarda ◽  
Anastasia Lampou ◽  
Nektarios Kalaitzakis ◽  
...  
Keyword(s):  
Habitat Modification ◽  
Ecological Quality ◽  
Cross Sectional ◽  
Habitat Features ◽  
Wide Range ◽  
Cross Sectional Profile ◽  
Sectional Profile ◽  
Main Components ◽  
The Individual ◽  
River Habitat Survey

The Water Framework Directive (WFD) requires from member states to monitor hydromorphological features of rivers in order to assess their ecological quality. Thus, numerous hydromorphological assessment methods have been developed with most of them focusing on the dynamics of hydrology, geomorphology and riparian zone extent. Within the scope of this study, we assessed the hydromorphological features of 106 river reaches distributed among thirteen WFD River Basin Districts (RBDs) to identify the main drivers of hydromorphological perturbation at a national scale. The studied reaches reflect a wide range of natural variability as they include various types of watercourses extending from lowlands to mid-altitude and mountainous systems. We employed the River Habitat Survey (RHS), and we recorded hydromorphological features and modifications in both banks and the channel bed along 500 m for each reach. Then, the Habitat Modification Score (HMS) and the individual sub-scores that indicate the extent of specific modifications (e.g., bridges, fords, weirs, bank reprofiling, bank reinforcement, etc.) were calculated in order to a) assess the severity of the total artificial modification and b) to highlight the most common and severe causes of overall alteration. The results showed that alterations such as reprofiling and reinforcement of banks contributed the most to the total HMS followed by the presence of fords and bridges. Particularly, the bank alterations indicate a serious deterioration of the longitudinal profile of the reaches, while the occurrence of many fords and bridges is the main cause for perturbations that affect locally the stream cross-sectional profile. Overall, these results compile a first nationwide assessment of the hydromorphological status of Greek rivers in line with the WFD and set the basis for further research that will focus on the diversity of stream habitat features as a measure for the overall ecological quality.

scholarly journals CO2 Hydrogenation over Nanoceria-Supported Transition Metal Catalysts: Role of Ceria Morphology (Nanorods versus Nanocubes) and Active Phase Nature (Co versus Cu)

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1739 ◽  
Author(s):  
Michalis Konsolakis ◽  
Maria Lykaki ◽  
Sofia Stefa ◽  
Sόnia A. C. Carabineiro ◽  
Georgios Varvoutis ◽  
...  
Keyword(s):  
Specific Activity ◽  
Active Phase ◽  
Physicochemical Characteristics ◽  
Co2 Hydrogenation ◽  
Transition Metal Catalysts ◽  
Co2 Conversion ◽  
Reverse Water Gas Shift ◽  
Wide Range ◽  
Combined Impact

In this work we report on the combined impact of active phase nature (M: Co or Cu) and ceria nanoparticles support morphology (nanorods (NR) or nanocubes (NC)) on the physicochemical characteristics and CO2 hydrogenation performance of M/CeO2 composites at atmospheric pressure. It was found that CO2 conversion followed the order: Co/CeO2 > Cu/CeO2 > CeO2, independently of the support morphology. Co/CeO2 catalysts demonstrated the highest CO2 conversion (92% at 450 °C), accompanied by 93% CH4 selectivity. On the other hand, Cu/CeO2 samples were very selective for CO production, exhibiting 52% CO2 conversion and 95% CO selectivity at 380 °C. The results obtained in a wide range of H2:CO2 ratios (1–9) and temperatures (200–500 °C) are reaching in both cases the corresponding thermodynamic equilibrium conversions, revealing the superiority of Co- and Cu-based samples in methanation and reverse water-gas shift (rWGS) reactions, respectively. Moreover, samples supported on ceria nanocubes exhibited higher specific activity (µmol CO2·m−2·s−1) compared to samples of rod-like shape, disclosing the significant role of support morphology, besides that of metal nature (Co or Cu). Results are interpreted on the basis of different textural and redox properties of as-prepared samples in conjunction to the different impact of metal entity (Co or Cu) on CO2 hydrogenation process.

scholarly journals Cellulose Nanocrystals/Graphene Hybrids—A Promising New Class of Materials for Advanced Applications

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1523 ◽  
Author(s):  
Djalal Trache ◽  
Vijay Kumar Thakur ◽  
Rabah Boukherroub
Keyword(s):  
Cellulose Nanocrystals ◽  
Renewable Resources ◽  
Food Packaging ◽  
Environmental Concern ◽  
Physicochemical Characteristics ◽  
Great Promise ◽  
New Class ◽  
Wide Range ◽  
Key Features ◽  
Basic Concepts

With the growth of global fossil-based resource consumption and the environmental concern, there is an urgent need to develop sustainable and environmentally friendly materials, which exhibit promising properties and could maintain an acceptable level of performance to substitute the petroleum-based ones. As elite nanomaterials, cellulose nanocrystals (CNC) derived from natural renewable resources, exhibit excellent physicochemical properties, biodegradability and biocompatibility and have attracted tremendous interest nowadays. Their combination with other nanomaterials such as graphene-based materials (GNM) has been revealed to be useful and generated new hybrid materials with fascinating physicochemical characteristics and performances. In this context, the review presented herein describes the quickly growing field of a new emerging generation of CNC/GNM hybrids, with a focus on strategies for their preparation and most relevant achievements. These hybrids showed great promise in a wide range of applications such as separation, energy storage, electronic, optic, biomedical, catalysis and food packaging. Some basic concepts and general background on the preparation of CNC and GNM as well as their key features are provided ahead.

Squeeze Film Damping Models Compared With Tests on Microsystems

2006 ◽  
Author(s):  
Hartono (Anton) Sumali ◽  
David S. Epp
Keyword(s):  
Experimental Data ◽  
Damping Ratio ◽  
Laser Doppler Vibrometer ◽  
Squeeze Film ◽  
Parallel Plates ◽  
Squeeze Film Damping ◽  
Wide Range ◽  
Oscillation Frequencies ◽  
Oscillating Plate ◽  
The Continuum

This paper compares three models for computing forces caused by gas film squeezed between parallel plates. The models are used to calculate damping forces on an oscillating plate at different oscillation frequencies. The damping forces are then used to calculate nondimensional damping ratios. The damping ratios are used in making comparisons among the models and with experimental data. The experiment used an oscillating MEMS plate suspended by folded springs. The substrate (base) was shaken with a piezoelectric transducer. The plate vibrated as a result, especially at the resonant frequency. The velocities of the suspended plate and of the substrate were measured with a laser Doppler vibrometer and a microscope. Experimental modal analysis gave the damping ratio. To achieve a wide range of squeeze numbers, the experiment was repeated under several different pressures. The measurement was also repeated on an array of plates. Experimental data indicate that, for atmospheric and higher pressures, squeeze-film damping forces can be modeled accurately with a very simple model. For lower pressures in the continuum regime, a more complete model by Veijola (2004) predicts the damping ratio very well.

scholarly journals Synthesis and Physicochemical Characteristics of Chitosan Extracted from Pinna deltoides

2021 ◽  
Vol 11 (4) ◽  
pp. 4061-4070
Keyword(s):  
Physicochemical Characteristics ◽  
Common Species ◽  
Ftir Analysis ◽  
Aliphatic Compound ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Wide Range ◽  
Pen Shell ◽  
Crystalline Nature ◽  
By Catch

Chitosan, a naturally produced polysaccharide that has a wide range of uses in biological, pharmacological, industrial, and commercial settings. The pen shell Pinna deltoides is a common species found along the coast of Thondi, and it is often collected as by-catch by fishermen. These species contain a high amount of chitin, which may be converted into chitosan. The goal of this research is to extract chitosan from P. deltoides and characterize it utilizing techniques like Fourier Transform Infrared Spectroscopy (FTIR), Micro Raman Spectroscopy, X-ray Powder Diffractometry (XRD), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). The existence of C-O-C glycosidic connection (1156 cm-1), NHCO group (1216 cm-1), aliphatic compound, -CH2 bend (1418 cm-1), and asymmetric CH2 stretching were verified by FTIR analysis (1204 cm-1). Chitosan extract exhibited a greater degree of deacetylation of 55.17%, which is consistent with prior studies. The highest peaks in the Micro Raman Spectra were 2937 cm-1, 1106 cm-1, and 1376 cm-1. The crystallinity of the chitosan at 2θ was anticipated using X-ray Powder Diffractometry (XRD) data at about 20°-25°. SEM micrograms verified the crystalline nature of the chitosan by revealing its soft and crystal-like arrangement of the chitosan. TGA was used to assess the sample's thermal constancy, and the chitosan's stability was found to be consistent with that of prior research.

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