scholarly journals Electrokinetic properties of chemically modified jute fabrics

2020 ◽  
pp. 69-69
Author(s):  
Aleksandra Ivanovska ◽  
Mirjana Kostic
Keyword(s):  
Zeta Potential ◽  
Isoelectric Point ◽  
Carboxyl Groups ◽  
Chemical Modifications ◽  
Electrokinetic Properties ◽  
Chemically Modified ◽  
Ph Values ◽  
Electrochemical Double Layer ◽  
Jute Fabrics ◽  
Oxidatively Modified

This work aims to study the alkali and oxidatively modified jute fabrics? electrokinetic properties. In contrast to control fabric, chemically modified jute fabrics have a small positive zeta potential in a basic pH range which can be attributed to the presence of sodium cations (originating from mentioned chemical modifications) on their surfaces. At lower pH values, samples modified under milder alkali and oxidative conditions have about 2.2-3.5 times lower zeta potential since the protonation process leads to the formation of higher positive charge in the electrochemical double layer causing higher adsorption of Cl- ions (originating from the electrolyte). On the other hand, more intensive chemical modifications increased the zeta potential at lower pH values due to the increased amount of carboxyl groups and fibers? ability for water retention and hence swelling. The isoelectric point of fabrics having lower zeta potential than control fabric was shifted toward higher pH values pointing out lower contribution of fabrics? surface acidic groups. In the case of extensive oxidation conditions (60 and 90 min), the isoelectric point was shifted toward lower pH values as a result of lignina removal and mentioned higher availability of newly formed carboxyl groups.

scholarly journals Relationship between isoelectric point of native and chemically modified insulin and liposomal fusion

1989 ◽  
Vol 264 (1) ◽  
pp. 285-287 ◽  
Author(s):  
R N Farías ◽  
A E López Viñals ◽  
E Posse ◽  
R D Morero
Keyword(s):  
Methyl Ester ◽  
Isoelectric Point ◽  
Carboxyl Groups ◽  
Amino Groups ◽  
Chemically Modified ◽  
Glycine Methyl Ester ◽  
Native Insulin ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Fusion Ability

Native insulin causes fusion of negatively charged liposomes in the pH range from 3.0 to 5.5. In marked contrast, insulin with all three amino groups succinylated did not show fusion ability at any pH. On the other hand, insulin amidated with glycine methyl ester with all six carboxyl groups blocked shifted its activity to higher pH, showing a pH range of activity from 3.0 to 7.4. When the carboxyl groups were recovered by hydrolysis of methoxyl groups from glycine methyl ester-treated insulin, the protein obtained (glycyl-insulin with six free carboxyl groups) behaved as native insulin. A good correlation between the isoelectric point values of insulin and its derivatives and their fusion properties was found.

Agglomerate formation during drying

2003 ◽  
Vol 18 (2) ◽  
pp. 495-506 ◽  
Author(s):  
Alejandro Vertanessian ◽  
Andrew Allen ◽  
Merrilea J. Mayo
Keyword(s):  
Zeta Potential ◽  
Isoelectric Point ◽  
Direct Consequence ◽  
Ph Values ◽  
Diffusion Limited ◽  
X Ray Scattering ◽  
Primary Particles ◽  
Small Primary ◽  
Ph Range ◽  
Size Scales

The evolution of agglomerate structure during drying of particles from suspension has been studied for a nanocrystalline Y2O3 (8% mol fraction)-stabilized ZrO2 powder. Agglomerates in drying and dried suspensions were examined at the smallest size scales (1 nm to 1 μm) using ultra-small angle x-ray scattering (USAXS) and at the largest size scales (100 nm to 10 μm) using scanning electron microscopy. The results were correlated with the degree of particle dissolution in each suspension (measured by flame absorption spectroscopy of the suspension filtrate) and the zeta potential of the particles in suspension prior to drying. Results show that large agglomerates readily form across a pH range from 2 to 9. The fact that Y+3 ion dissolution varies by over four orders of magnitude in this range leads to the conclusion that there is little direct correlation between the degree of Y dissolution and agglomeration in this system (Zr ion dissolution was below the detection limit at all pH values studied). The observation of large agglomerates well before the introduction of air-water interfaces into the drying mass likewise leads to the conclusion that capillary forces are not essential to agglomerate formation. Instead, agglomerates appear to form as a direct consequence of increasing suspension concentration. Zeta potential also plays a role. Specifically, there was a notable change in agglomerate morphology as the isoelectric point was approached, at approximately pH 8. Here USAXS shows the particles in suspension to have a layered interior structure, with small primary particles aggregated in sheets to form each blocky particle. This is in contrast to the more rounded agglomerates formed away from the isoelectric point, which appear to be composed of the same primary particles arranged in chainlike structures. USAXS of powders from the dried suspensions confirms that the structures seen after drying are the same as those present in suspension. The two structural morphologies are attributed to diffusion-limited (sheets) versus reaction-limited (chains) aggregation, respectively.

Effect of Zein Concentration on the Formation of Pectin-Zein Complexes

2012 ◽  
Vol 506 ◽  
pp. 319-322 ◽  
Author(s):  
Maneerat Juttulapa ◽  
Pornsak Sriamornsak
Keyword(s):  
Aqueous Solution ◽  
Zeta Potential ◽  
Physicochemical Properties ◽  
Isoelectric Point ◽  
Globular Proteins ◽  
Ph Values ◽  
Anionic Polysaccharides ◽  
Formation Of Complexes

Biopolymeric particles can be formed by electrostatic complexes of globular proteins and anionic polysaccharides mixtures at pH values above pKa of anionic polysaccharide and under the isoelectric point of protein. The purpose of this study was to investigate the effect of protein (i.e., zein) concentration on the formation of complexes between zein and polysaccharide (i.e., amidated low methoxy pectin) in aqueous solution. The zeta potential, turbidity and morphology under different conditions were observed to provide insights into the physicochemical properties of zein-pectin complexes. The biopolymeric particles were obtained at pH 4 and concentration of zein and pectin of 0.001 and 1% w/w, respectively. As the zein concentration increased, the turbidity of zein-pectin solutions increased, resulting from the formation of zein-pectin complexes. The zeta potential of the systems became less negative when the zein concentration increased. The results suggested that concentration of zein primarily influenced the formation of zein-pectin complexes.

Electrokinetic Potential for Characterization of Nanosctructured Solid Flat Surfaces

2013 ◽  
Vol 25 ◽  
pp. 31-39 ◽  
Author(s):  
Zdeňka Kolská ◽  
Nikola Slepičková Kasálková ◽  
Jakub Siegel ◽  
Václav Švorčík
Keyword(s):  
Zeta Potential ◽  
Isoelectric Point ◽  
Electrokinetic Potential ◽  
Characteristic Parameter ◽  
Metal Nanostructures ◽  
Gold Deposition ◽  
Fast Analysis ◽  
Flat Surfaces ◽  
Acceptable Method ◽  
Point Determination

Electrokinetic potential (zeta potential) is a characteristic parameter for description of the surface chemistry of solid flat materials and it can be used for a fast analysis of materials modified by different chemical or physical methods. Due to its sensitivity, zeta potential is able to distinguish surface modified by coating with monolayers of various materials or nanostructures created after plasma treatment. Also metal nanostructures deposited on surfaces can be characterized by zeta potential. It can also be used for isoelectric point determination of materials. We present data on zeta potential in 0.001 mol/dm3 KCl at constant pH7.0 and also in pH range (2.5-7.0) for isoelectric point determination for pristine polymers PET, PTFE, PS, LDPE, HDPE, PLLA, PVF, PVDF, PMP and polyimides (Upilex R, Upilex S, Kapton). The zeta potential of selected polymers, modified by plasma and by chemical coatings (e.g. by biphenyldithiol or polyethyleneglycol) or by gold deposition was measured too. Zeta potentials of these modified materials were also studied to confirmation that electrokinetic analysis is acceptable method for their fast description.

The interaction of ligands with chemically modified phosphorylase b

1976 ◽  
Vol 54 (5) ◽  
pp. 494-499
Author(s):  
D. Brooks ◽  
S. J. W. Busby ◽  
J. R. Griffiths ◽  
G. K. Radda ◽  
O. Avramovic-Zikic
Keyword(s):  
Conformational Changes ◽  
Spin Label ◽  
Native Enzyme ◽  
Carboxyl Groups ◽  
Chemically Modified ◽  
Allosteric Effector ◽  
Spin Resonance ◽  
Label Probe ◽  
Glycine Ethyl Ester ◽  
Modified Enzyme

Phosphorylase b which had been inactivated with 5-diazo-1H-tetrazole was specifically labelled with 4-iodoacetamidosalicylic acid (a fluorescent probe) or with N-(1-oxyl-2,2,6,6,-tetramethyl-4-piperidinyl)iodoacetamide (a spin label probe) so that the binding of ligands and accompanying conformational changes could be determined by fluorescence or electron spin resonance changes, respectively. The allosteric effector, AMP, causes conformational changes similar to those caused in the native enzyme. The affinity of binding of phosphate or AMP to the inhibited protein is the same as for the unmodified protein. The heterotropic interactions between glucose-1-phosphate or glycogen and AMP are much less in the inactivated enzyme than in unmodified phosphorylase. Using a light scattering assay, it is shown that the modified enzyme binds to glycogen less strongly than the native protein.Phosphorylase b which had been inactivated by carbodiimide in the presence of glycine ethyl ester, resulting in the modification of one or more carboxyl groups, was labelled with the spin label probe described above. The modified enzyme has an affinity for AMP similar to that of the native enzyme. AMP binding to the modified enzyme is tightened by glycogen, weakened by glucose-6-phosphate and is unaffected by glucose- 1-phosphate.The actions of 5-diazo-1H-tetrazole and carbodiimide on phosphorylase are discussed in the light of the above observations.

Adsorption of Organic Compounds on Refined Latvian Clay

2018 ◽  
Vol 788 ◽  
pp. 83-88
Author(s):  
Oskars Leščinskis ◽  
Ruta Švinka ◽  
Visvaldis Švinka
Keyword(s):  
Methyl Orange ◽  
Zeta Potential ◽  
Adsorption Capacity ◽  
Clay Minerals ◽  
Organic Compounds ◽  
Clay Mineral ◽  
Rhodamine B ◽  
Ph Value ◽  
Ftir Spectra ◽  
Ph Values

Clays are materials consisting of clay minerals and non-clay minerals. Clay mineral fraction is considered to be a nanofraction. Clay minerals can be used for water purification and treatment. Description and characterization of 3 different Latvian clay nanosized minerals from 3 different geological periods (clay Liepa from Devonian period, clay Vadakste from Triassic period and clay Apriki from Quaternary period) as well as their adsorption capacity concerning organic compounds such as methyl orange and rhodamine B are summarized. Nanosized clay mineral particles were obtained using sedimentation method. Particle size distribution, zeta potential and FTIR spectra is given. The adsorption tests of above mentioned organic compounds were carried out in water solutions at 3 different pH values. The adsorption values were determined by means of UV-spectrophotometric technique. Zeta potential values for clay minerals Apriki, Liepa and Vadakste are -40.9 mV, -49.6 mV and -43.0 mV, respectively. FTIR spectra show similar tendencies for all 3 clay minerals. The best adsorption capacity concerning methyl orange and rhodamine B were in solutions with a pH value of 2, whereas at neutral and alkaline pH values adsorption in 24 hours was not observed.

scholarly journals RNA Chemistry for RNA Biology

2019 ◽  
Vol 73 (5) ◽  
pp. 368-373 ◽  
Author(s):  
Pascal Röthlisberger ◽  
Christian Berk ◽  
Jonathan Hall
Keyword(s):  
Chemical Synthesis ◽  
Nucleic Acids ◽  
Chemical Biology ◽  
Rna Synthesis ◽  
Intrinsic Properties ◽  
Chemical Modifications ◽  
Chemically Modified ◽  
Wide Range ◽  
Rna Biology ◽  
Modified Nucleic Acids

Advances in the chemical synthesis of RNA have opened new possibilities to address current questions in RNA biology. Access to site-specifically modified oligoribonucleotides is often a pre-requisite for RNA chemical-biology projects. Driven by the enormous research efforts for development of oligonucleotide therapeutics, a wide range of chemical modifications have been developed to modulate the intrinsic properties of nucleic acids in order to fit their use as therapeutics or research tools. The RNA synthesis platform, supported by the NCCR RNA & Disease, aims to provide access to a large variety of chemically modified nucleic acids. In this review, we describe some of the recent projects that involved work of the platform and highlight how RNA chemistry supports new discoveries in RNA biology.

scholarly journals PHYSICOCHEMICAL CHARACTERIZATION OF PROPRANOLOL-LOADED CHITOSAN NANOPARTICLES FOR A BUCCAL DRUG DELIVERY SYSTEM

2020 ◽  
pp. 243-247
Author(s):  
SIRIPORN KITTIWISUT ◽  
PAKORN KRAISIT
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Zeta Potential ◽  
Drug Delivery System ◽  
Delivery System ◽  
Chitosan Nanoparticles ◽  
Particle Sizes ◽  
Zeta Potentials ◽  
Ph Values ◽  
Buccal Drug Delivery

Objective: This study aimed to characterize the physicochemical properties, including pH, zeta potential, and particle size of propranolol-loaded nanoparticles that were incorporated into a buccal transmucosal drug-delivery system. Methods: An ionotropic gelation technique was used to formulate propranolol-loaded chitosan nanoparticles. Chitosan used as the nanoparticle base, using tripolyphosphate (TPP) as a cross-linking agent. The effects on nanoparticle physical properties, including pH, zeta potential, and particle size were examined when various chitosan [0.150-0.300 % (w/v)] and propranolol contents (0-40 mg) were used during the preparation. The effects of using chitosan solutions with different pH values on nanoparticle properties were also determined. Results: The pH values of all nanoparticles ranged between 4.14–4.55. The zeta potentials of the prepared nanoparticles ranged between 22.6–52.6 mV, with positive charges. The nanoparticle sizes ranged from 107–140 nm, which are within the range of suitable particle sizes for transmucosal preparations. Conclusion: The pH values, zeta potentials, and particle sizes of the nanoparticle formulations were influenced by the concentrations of chitosan and propranolol and by the pH of the initial chitosan solution. The relationships between nanoparticle properties and all factors primarily depended on the ionic charges of the components, especially chitosan. Our study provides beneficial physicochemical knowledge for the further development of chitosan-based nanoparticles containing propranolol for buccal drug delivery systems.

Use of Malonic Acid in Chemical-Mechanical Polishing ( CMP ) of Tungsten

1997 ◽  
Vol 477 ◽  
Author(s):  
L. Zhang ◽  
S. Raghavan
Keyword(s):  
Zeta Potential ◽  
Malonic Acid ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Small Scale ◽  
Ph Values ◽  
Particulate Contamination ◽  
Principal Objective ◽  
Alumina Particles ◽  
Negative Zeta Potential

ABSTRACTThe use of malonic acid as an additive in alumina slurries used for the chemical mechanical polishing ( CMP ) of tungsten has been explored for the reduction of particulate contamination. The principal objective of this work was to delineate conditions under which alumina contamination on polished surfaces could be reduced.The interaction between malonic acid and alumina particles has been investigated through electrokinetic and adsorption measurements. At suitable malonic acid concentrations and pH values, tungsten and alumina surfaces develop a negative zeta potential resulting in conditions conducive to reduced particulate contamination. Small scale polishing experiments have been carried out to relate electrokinetic results to the level of particulate contamination after polishing.

Sign in / Sign up

Export Citation Format

Share Document