scholarly journals Polyelectrolyte Complexation versus Ionotropic Gelation for Chitosan-Based Hydrogels with Carboxymethylcellulose, Carboxymethyl Starch, and Alginic Acid

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Elizabeth Henao ◽  
Ezequiel Delgado ◽  
Héctor Contreras ◽  
Germán Quintana
Keyword(s):  
Alginic Acid ◽  
Major Influence ◽  
Ionotropic Gelation ◽  
Polyelectrolyte Complexation ◽  
Anionic Charge ◽  
Polymeric Compounds ◽  
Distribution Parameters ◽  
Charge Interaction ◽  
Gel Preparation ◽  
Physical Changes

The preparation of gels by charge interaction methods has been extensively studied, but it is not yet clear how these methods influence gel characteristics. The objective of this work was to study differences in morphology and surface charge of hydrogels prepared by ionotropic gelation, polyelectrolyte complexation, and a combination of both methods. Thus, the anionic charge was provided by carboxymethylcellulose (CMC), carboxymethylated starch (CMS), and alginic acid (AA); calcium chloride (CaCl2) and chitosan (CS) were used for the ionotropic gelation and polyelectrolyte complexation, respectively. Those materials are commercially available, have low toxicity, and are widely used in the area. These compounds interact through physical crosslinks, which are affected by physical changes of the medium. Our results showed that these two methods produced changes in the morphology of the hydrogels. CMC gels exhibited larger pores in the presence of CaCl2. In polyelectrolyte complexation, CMS produced an increased agglomeration of particles, while the addition of CaCl2 to AA generated dispersed particles of size in the order of millimeters. Mixing both ionotropic gelation and polyelectrolyte complexation methods yielded gels of varied charge (568 mV for CMC, 502 mV for CMS, and 1713 mV for AA). FTIR spectra of the hydrogels showed interactions between the different polymeric compounds, being the greatest changes between 1250 and 1600 cm−1, due possibly to the replacement of Na by Ca at crosslinking points. Therefore, the method of gel preparation employed had a major influence on the size and pore distribution, parameters which in turn influence encapsulation and drug delivery in these systems.

scholarly journals Effect of Experimental Parameters on the Formation of Hydrogels by Polyelectrolyte Complexation of Carboxymethylcellulose, Carboxymethyl Starch, and Alginic Acid with Chitosan

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Elizabeth Henao Mejía ◽  
Héctor Contreras ◽  
Ezequiel Delgado ◽  
Germán Quintana
Keyword(s):  
Zeta Potential ◽  
Electric Charge ◽  
Alginic Acid ◽  
Gelation Time ◽  
Three Dimensional ◽  
Anionic Polymer ◽  
Carboxymethyl Starch ◽  
Polyelectrolyte Complexation ◽  
Experimental Parameters ◽  
Negative Zeta Potential

Differences in morphology, pH, and electric charge of chitosan (CS) based hydrogels prepared by complexation with carboxymethylcellulose (CMC), carboxymethylated starch (CMS), and alginic acid (AA) at different polymers ratios and changing the order of addition were studied. CMC/CS and AA/CS hydrogels were amorphous and porous three-dimensional networks, with smaller pores at higher anionic polymer/CS ratios. Gelation time increased the agglomeration in the case of CMC/CS and CMS/CS gels. CMC/CS gels showed negative zeta potential values around −372 mV to −51 mV and CMS/CS gels in the range of −526 mV and −158 mV.

scholarly journals PENGARUH BEBERAPA CARA KEMATIAN IKAN TERHADAP MUTU IKAN KAKAP (Lutjanus sp.)

2010 ◽  
Vol 6 (3) ◽  
pp. 145 ◽  
Author(s):  
Albert R Reo
Keyword(s):  
Storage Temperature ◽  
Raw Materials ◽  
Major Influence ◽  
Processing Plant ◽  
Rigor Mortis ◽  
Manner Of Death ◽  
Research Results ◽  
Fitness Level ◽  
Dead Fish ◽  
Physical Changes

The handling of fishery products play an important role in exploiting fisheries production, which began handling the treatment of fish caught, on board, when landed, the market-the market, retailers get to the processing plant.  Storage temperature of fish plays an important role when the fish die. the use of low temperatures around 0oC after dead fish can extend the seizures (rigor mortis), lower enzymatic activity, bacterial, chemical and physical changes that can prolong the durable power of fish. How to fish death during arrest have a major influence on the process begins and the end of rigor mortis is consequential to the quality and durable power of fish.  This study aims to determine the influence of how the death of fish on fish lasting power during cold storage. benefits of this research can provide information on the manner of death a good fish. Research results snapper fitness level based on organoleptic testing with scores ranging between 4.8 to 50 with an average rating of 50, 45.7, 38.5, 26.2 for treated fish were injected / gancu, 50, 38.1, 10, 5.4 for fish a dead flounder.  Research results snapper fitness level based on the value-K test is: 25.78% injection treatment / gancu, 48.99% hit with a wood treatment on the head and the dead fish flounder 50.34%.  Fish snapper (Lutjanus sp.) who was arrested dikaramba Likupang waters, the organoleptic and value-K is still suitable for consumption and for processing raw materials.

scholarly journals Hole in One: an element reduction approach to modeling bone porosity in finite element analysis

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8112
Author(s):  
Beatriz L. Santaella ◽  
Z. Jack Tseng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Trabecular Bone ◽  
Material Properties ◽  
Major Influence ◽  
Mathematical Approach ◽  
Element Analysis ◽  
Physical Element ◽  
Physical Changes ◽  
Reduction Approach

Finite element analysis has been an increasingly widely applied biomechanical modeling method in many different science and engineering fields over the last decade. In the biological sciences, there are many examples of FEA in areas such as paleontology and functional morphology. Despite this common use, the modeling of trabecular bone remains a key issue because their highly complex and porous geometries are difficult to replicate in the solid mesh format required for many simulations. A common practice is to assign uniform model material properties to whole or portions of models that represent trabecular bone. In this study we aimed to demonstrate that a physical, element reduction approach constitutes a valid protocol for addressing this problem in addition to the wholesale mathematical approach. We tested a customized script for element reduction modeling on five exemplar trabecular geometry models of carnivoran temporomandibular joints, and compared stress and strain energy results of both physical and mathematical trabecular modeling to models incorporating actual trabecular geometry. Simulation results indicate that that the physical, element reduction approach generally outperformed the mathematical approach: physical changes in the internal structure of experimental cylindrical models had a major influence on the recorded stress values throughout the model, and more closely approximates values obtained in models containing actual trabecular geometry than solid models with modified trabecular material properties. In models with both physical and mathematical adjustments for bone porosity, the physical changes exhibit more weight than material properties changes in approximating values of control models. Therefore, we conclude that maintaining or mimicking the internal porosity of a trabecular structure is a more effective method of approximating trabecular bone behavior in finite element models than modifying material properties.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

“Where is Dementia?” A Systematic Literature Review Exploring Neuroanatomical Aspects of Dementia

2017 ◽  
Vol 2 (15) ◽  
pp. 9-23 ◽  
Author(s):  
Chorong Oh ◽  
Leonard LaPointe
Keyword(s):  
English Language ◽  
Signs And Symptoms ◽  
Behavioral Symptoms ◽  
Journal Articles ◽  
People With Dementia ◽  
Different Types ◽  
Precise Diagnosis ◽  
Physical Changes ◽  
The Brain ◽  
Language Literature

Dementia is a condition caused by and associated with separate physical changes in the brain. The signs and symptoms of dementia are very similar across the diverse types, and it is difficult to diagnose the category by behavioral symptoms alone. Diagnostic criteria have relied on a constellation of signs and symptoms, but it is critical to understand the neuroanatomical differences among the dementias for a more precise diagnosis and subsequent management. With this regard, this review aims to explore the neuroanatomical aspects of dementia to better understand the nature of distinctive subtypes, signs, and symptoms. This is a review of English language literature published from 1996 to the present day of peer-reviewed academic and medical journal articles that report on older people with dementia. This review examines typical neuroanatomical aspects of dementia and reinforces the importance of a thorough understanding of the neuroanatomical characteristics of the different types of dementia and the differential diagnosis of them.

A Stochastic Study on the Distribution Parameters of Random Individual Walking Excitations

AEI 2017 ◽  
2017 ◽  
Author(s):  
Zhiqiang Zhang ◽  
Bill Zhang ◽  
Jieqiang Wei ◽  
Peng Luo ◽  
Changhui Cui
Keyword(s):  
Distribution Parameters ◽  
Random Individual

From Trinidad and Tobago to the World: Determining the role of Calypso in a new Era

2020 ◽  
Vol 5 ◽  
pp. 7-11
Author(s):  
Malek Abdel-Shehid
Keyword(s):  
Trinidad And Tobago ◽  
Regional Integration ◽  
West African ◽  
Major Influence ◽  
New Era ◽  
Transatlantic Slave Trade ◽  
Cultural Sovereignty ◽  
Caribbean Culture ◽  
Musical Cultures

Calypso is a popular Caribbean musical genre that originated in the island nation of Trinidad and Tobago. The genre was developed primarily by enslaved West Africans brought to the region via the transatlantic slave trade during the seventeenth and eighteenth centuries. Although West-African Kaiso music was a major influence, the genre has also been shaped by other African genres, and by Indian, British, French, and Spanish musical cultures. Emerging in the early twentieth century, Calypso became a tool of resistance by Afro-Caribbean working-class Trinbagonians. Calypso flourished in Trinidad due to a combination of factors—namely, the migration of Afro-Caribbean people from across the region in search of upward social mobility. These people sought to expose the injustices perpetrated by a foreign European and a domestic elite against labourers in industries such as petroleum extraction. The genre is heavily anti-colonial, anti-imperial, and anti-elitist, and it advocated for regional integration. Although this did not occur immediately, Calypsonians sought to establish unity across the region regardless of race, nationality, and class through their songwriting and performing. Today, Calypso remains a unifying force and an important part of Caribbean culture. Considering Calypso's history and purpose, as well as its ever-changing creators and audiences, this essay will demonstrate that the goal of regional integration is not possible without cultural sovereignty.

Modeling cetacean habitat use in an urban coastal area in southeastern Brazil

2020 ◽  
Vol 642 ◽  
pp. 227-240
Author(s):  
L Lodi ◽  
R Tardin ◽  
G Maricato
Keyword(s):  
Habitat Use ◽  
Protected Areas ◽  
Linear Models ◽  
Anthropogenic Activities ◽  
Buffer Zone ◽  
Humpback Whales ◽  
Southeastern Brazil ◽  
Major Influence ◽  
Cetacean Species ◽  
Few Data

Most studies of cetacean habitat use do not consider the influence of anthropogenic activities. We investigated the influence of environmental and anthropogenic variables on habitat use by humpback Megaptera novaeangliae and Bryde’s whales Balaenoptera brydei off the coast of the Brazilian city of Rio de Janeiro. Although there are 2 marine protected areas (MPAs) in this area, few data are available on cetacean habitat use or on the overlap of different cetacean species within these MPAs. Our aim was to evaluate the effectiveness of the MPAs and propose a buffer zone to better protect the biodiversity of the study area. We conducted systematic surveys and developed spatial eigenvector generalized linear models to characterize habitat use by the species in the study area. Habitat use by humpback whales was influenced only by depth, whereas for Bryde’s whales there was the additional influence of anthropogenic variables. For Bryde’s whales, which use the area for feeding, sea surface temperature and the distance to anchorages had a major influence on habitat use. We also showed that neither of the MPAs in the study area adequately protects the hotspots of either whale species. Most of the humpback whale grid cells with high sighting predictions were located within 2 km of the MPAs, while areas of high sighting prediction of Bryde’s whales were located up to 5 km from the MPAs, closer to beaches. Our findings provide important insights for the delimitation of protected areas and zoning of the MPAs.

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