scholarly journals On the Determination of Magnesium Degradation Rates under Physiological Conditions

Materials ◽  
2016 ◽  
Vol 9 (8) ◽  
pp. 627 ◽  
Author(s):  
Eshwara Nidadavolu ◽  
Frank Feyerabend ◽  
Thomas Ebel ◽  
Regine Willumeit-Römer ◽  
Michael Dahms
Keyword(s):  
Physiological Conditions ◽  
Degradation Rates

Influence of various sterilization methods on hardness, grain size and corrosion rate of a Mg6Ag-alloy

2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Frank Feyerabend ◽  
Martin Johannisson ◽  
Zhidan Liu ◽  
Regine Willumeit-Römer
Keyword(s):  
Grain Size ◽  
Corrosion Rate ◽  
Optimum Ratio ◽  
Corrosion Properties ◽  
Corrosion Morphology ◽  
Materials Properties ◽  
Physiological Conditions ◽  
Alloying System ◽  
Dry Heat

AbstractSterilization is a necessary step for all implant materials. Different methods can influence the materials properties. Especially important for magnesium as degradable materials is the determination of the corrosion properties. In this study the influence of 70% ethanol, glutaraldehyde, autoclaving, dry heat, UV-, gamma- and electron beam-irradiation on mechanical and corrosion parameters were analyzed. As mechanical parameters hardness and grain size were determined. The corrosion rate under physiological conditions, weight of the corrosion layer and corrosion morphology was determined. It could be demonstrated that irradiation treatments and 70% ethanol are suitable methods, as they decrease the corrosion rate. Heat-introducing methods (autoclaving and dry heat) acted as incomplete ageing treatments on this alloy and therefore increased the corrosion rate. Furthermore, osmolality showed a better correlation to the actual corrosion rate than the pH. Therefore an optimum ratio between alloying system, implant and sterilization method has to be established, depending on the intended application.

scholarly journals Copper(I)-Catalyzed Click Chemistry as a Tool for the Functionalization of Nanomaterials and the Preparation of Electrochemical (Bio)Sensors

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2379 ◽  
Author(s):  
P. Yáñez-Sedeño ◽  
A. González-Cortés ◽  
S. Campuzano ◽  
J. M. Pingarrón
Keyword(s):  
Electrochemical Sensors ◽  
Functional Integration ◽  
Future Directions ◽  
Physiological Conditions ◽  
Electrode Surfaces ◽  
Wide Range ◽  
High Yields ◽  
By Products ◽  
Powerful Strategy

Proper functionalization of electrode surfaces and/or nanomaterials plays a crucial role in the preparation of electrochemical (bio)sensors and their resulting performance. In this context, copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been demonstrated to be a powerful strategy due to the high yields achieved, absence of by-products and moderate conditions required both in aqueous medium and under physiological conditions. This particular chemistry offers great potential to functionalize a wide variety of electrode surfaces, nanomaterials, metallophthalocyanines (MPcs) and polymers, thus providing electrochemical platforms with improved electrocatalytic ability and allowing the stable, reproducible and functional integration of a wide range of nanomaterials and/or different biomolecules (enzymes, antibodies, nucleic acids and peptides). Considering the rapid progress in the field, and the potential of this technology, this review paper outlines the unique features imparted by this particular reaction in the development of electrochemical sensors through the discussion of representative examples of the methods mainly reported over the last five years. Special attention has been paid to electrochemical (bio)sensors prepared using nanomaterials and applied to the determination of relevant analytes at different molecular levels. Current challenges and future directions in this field are also briefly pointed out.

scholarly journals KINETIKA DEGRADASI SELULOSA ASETAT DARI SABUT PINANG

2018 ◽  
Vol 1 (1) ◽  
pp. 24
Author(s):  
Intan Syahbanu ◽  
Annisa Anugraini ◽  
Husna Amalya Melati
Keyword(s):  
Polymer Solution ◽  
Cellulose Acetate ◽  
Intrinsic Viscosity ◽  
Degradation Kinetics ◽  
Molecular Size ◽  
Ultrasonic Waves ◽  
Degradation Rates ◽  
Wide Range ◽  
Degradation Rate Constant

Cellulose Acetate is a material with wide range in applications. Cellulose acetate may obtain from natural resources, such as areca fiber. Polymers should have uniform molecular weight for the applications and could be modify by ultrasonic waves. Ultrasonic treatment on polymer entangled with polymer degradation. In this research, degradation kinetics of cellulose acetate in acetone had been studied. Analysis was performed by determination of intrinsic viscosity in polymer solution system.  Intrinsic viscosity was successfully obtained by fitting data using Huggins equation, indicate molecular interaction in polymer solution should not be neglected.  Increasing in sonication time reducing the intrinsic viscosities as well as molecular size in solutions.  Degradation rate constant and reaction order were obtained 5,975x10-3(g.mL-1)0,1.min-1 and 1,0616, respectively.  Kinetics model was successful to determine the degradation rates of cellulose acetate on acetone by correlation coefficient (R2) at 0,966.

PREPARATION OF PROTEASE FROM MIXED RUMEN MICROORGANISMS AND ITS USE FOR THE IN VITRO DETERMINATION OF THE DEGRADABILITY OF TRUE PROTEIN IN FEEDSTUFFS

1987 ◽  
Vol 67 (1) ◽  
pp. 55-64 ◽  
Author(s):  
S. MAHADEVAN ◽  
F. D. SAUER ◽  
J. D. ERFLE
Keyword(s):  
Proteolytic Activity ◽  
Rumen Fluid ◽  
Streptomyces Griseus ◽  
Potassium Phosphate ◽  
Canola Meal ◽  
Rumen Microorganisms ◽  
Degradation Rates ◽  
Feed Protein

Mixed rumen microorganisms present in bovine rumen fluid were extracted with butanol-acetone to provide a dry powder which retained 75–80% of the proteolytic activity of strained rumen fluid (SRF). Sixty percent of the proteolytic activity of the powder was extracted with water and concentrated on an Amicon XM-300 filter to give a protease preparation which had about 30% of the activity present in the SRF. The protease preparation was used for the determination of the rates of feed protein degradation in vitro by incubating at pH 6.8 in 0.1 M potassium phosphate buffer and measuring the rate of amino acid (and ammonia) production by the ninhydrin method. The relative degradation rates of the true proteins from feedstuffs tested were: soybean meal > fish meal > linseed meal and blood meal > canola meal > corn gluten meal. Substituting Streptomyces griseus protease for the rumen protease gave results which were very different from those obtained with the rumen enzyme. The advantages of using the rumen protease over other in vitro methods and the practical applicability of the procedure are discussed. Key words: Rumen, protease, preparation, in vitro, feed protein degradability

Determination of domestic water meter accuracy degradation rates in Uganda

2015 ◽  
Vol 64 (4) ◽  
pp. 486-492 ◽  
Author(s):  
Deanroy Mbabazi ◽  
Noble Banadda ◽  
Nicholas Kiggundu ◽  
Harrison Mutikanga ◽  
Mohammed Babu
Keyword(s):  
Domestic Water ◽  
Degradation Rates ◽  
Water Meter

scholarly journals Hormetic and Mitochondria-Related Mechanisms of Antioxidant Action of Phytochemicals

Antioxidants ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 373 ◽  
Author(s):  
Franco ◽  
Navarro ◽  
Martínez-Pinilla
Keyword(s):  
Electron Transport ◽  
Health Benefit ◽  
Well Being ◽  
Antioxidant Action ◽  
Direct Role ◽  
Physiological Conditions ◽  
Technical Developments ◽  
Transport Chain ◽  
Living Being

Antioxidant action to afford a health benefit or increased well-being may not be directly exerted by quick reduction-oxidation (REDOX) reactions between the antioxidant and the pro-oxidant molecules in a living being. Furthermore, not all flavonoids or polyphenols derived from plants are beneficial. This paper aims at discussing the variety of mechanisms underlying the so-called “antioxidant” action. Apart from antioxidant direct mechanisms, indirect ones consisting of fueling and boosting innate detox routes should be considered. One of them, hormesis, involves upregulating enzymes that are needed in innate detox pathways and/or regulating the transcription of the so-called vitagenes. Moreover, there is evidence that some plant-derived compounds may have a direct role in events taking place in mitochondria, which is an organelle prone to oxidative stress if electron transport is faulty. Insights into the potential of molecules able to enter into the electron transport chain would require the determination of their reduction potential. Additionally, it is advisable to know both the oxidized and the reduced structures for each antioxidant candidate. These mechanisms and their related technical developments should help nutraceutical industry to select candidates that are efficacious in physiological conditions to prevent diseases or increase human health.

Ion-transfer voltammetric determination of folic acid at meso-liquid–liquid interface arrays

The Analyst ◽  
2015 ◽  
Vol 140 (8) ◽  
pp. 2823-2833 ◽  
Author(s):  
Xuheng Jiang ◽  
Kui Gao ◽  
Daopan Hu ◽  
Huanhuan Wang ◽  
Shujuan Bian ◽  
...  
Keyword(s):  
Folic Acid ◽  
Detection Method ◽  
Liquid Interface ◽  
Water Soluble ◽  
Voltammetric Determination ◽  
Ion Transfer ◽  
Physiological Conditions ◽  
Voltammetric Studies ◽  
B Vitamin

Voltammetric studies on the simple ion transfer (IT) behaviors of an important water-soluble B-vitamin, folic acid (FA), at the liquid–liquid (L–L) interface were firstly performed and applied as a novel detection method for FA under physiological conditions. This work provides a new and attractive strategy for the detection of FA− and other biological anions.

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