Interaction of Organic Additives With Ceramic Surfaces In Colloidal Slurries

1996 ◽  
Vol 432 ◽  
Author(s):  
W. M. Sigmund ◽  
L. Wang ◽  
J. Sindel ◽  
M. Rotov ◽  
F. Aldinger
Keyword(s):  
Aqueous Media ◽  
Aqueous System ◽  
Low Molecular Weight ◽  
Organic Additives ◽  
Rheological Measurements ◽  
Ceramic Surfaces ◽  
Carboxylate Anions ◽  
Repulsive Forces ◽  
Anchor Block ◽  
Polymer Block

AbstractThree different dispersants, a low molecular weight compound (aminoalkanol), a polymer (polyelectrolyte) and a block-co-polymer (block polyethylenoxide-polyacrylic acid) were investigated with AFM and rheology in an aqueous system in order to elucidate the influence of the size and structure of the molecule on the dispersion stabilization. The AFM studies indicate that the aminoalkanol gives repulsive forces due to electrostatic repulsion only. The polyelectrolyte seems to stabilize the dispersion with both steric and electrostatic repulsive forces. A new compound that was designed for pure steric stabilization in aqueous media a block-co-polymer consisting of a polar anchor block and a stabilizing neutral chain was investigated for its behavior. The AFM measurements show that it is likely that this compound causes repulsion of silicon nitride surfaces due to steric repulsion only. Rheological measurements of aqueous powder slurries show that the adsorption of the organic additives is of great importance. Due to a more silicon dioxide like acidic surface of the investigated Si3N4 - powder the carboxylate anions of the block-co-polymer adsorb badly. Therefore, no sterically repulsive forces can be built up. This then causes an increase in the slurry's viscosity.

Curcumin a colorimetric and fluorimetric cyanide probe in aqueous system and living cells

2019 ◽  
Vol 11 (40) ◽  
pp. 5169-5176 ◽  
Author(s):  
Yousef M. Hijji ◽  
Anas G. Elsafy ◽  
Hala Sultan Al-Easa ◽  
Bassam Attili ◽  
Mahmoud Abdelrasoul ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Living Cells ◽  
Aqueous System ◽  
Fluorometric Sensor

Curcumin is a visual, photometric and fluorometric sensor for cyanide in aqueous media.

scholarly journals Polythiophenes with Cationic Phosphonium Groups as Vectors for Imaging, siRNA Delivery, and Photodynamic Therapy

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1432
Author(s):  
Laure Lichon ◽  
Clément Kotras ◽  
Bauyrzhan Myrzakhmetov ◽  
Philippe Arnoux ◽  
Morgane Daurat ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Photodynamic Therapy ◽  
Photophysical Properties ◽  
Combined Therapy ◽  
Sirna Delivery ◽  
Aqueous Media ◽  
Low Molecular Weight ◽  
Oxygen Species ◽  
Cationic Polymers ◽  
Intracellular Location

In this work, we exploit the versatile function of cationic phosphonium-conjugated polythiophenes to develop multifunctional platforms for imaging and combined therapy (siRNA delivery and photodynamic therapy). The photophysical properties (absorption, emission and light-induced generation of singlet oxygen) of these cationic polythiophenes were found to be sensitive to molecular weight. Upon light irradiation, low molecular weight cationic polythiophenes were able to light-sensitize surrounding oxygen into reactive oxygen species (ROS) while the highest were not due to its aggregation in aqueous media. These polymers are also fluorescent, allowing one to visualize their intracellular location through confocal microscopy. The most promising polymers were then used as vectors for siRNA delivery. Due to their cationic and amphipathic features, these polymers were found to effectively self-assemble with siRNA targeting the luciferase gene and deliver it in MDA-MB-231 cancer cells expressing luciferase, leading to 30–50% of the gene-silencing effect. In parallel, the photodynamic therapy (PDT) activity of these cationic polymers was restored after siRNA delivery, demonstrating their potential for combined PDT and gene therapy.

scholarly journals Quick synthesis, functionalization and properties of uniform, luminescent LuPO4-based nanoparticles

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34517-34524 ◽  
Author(s):  
Ana I. Becerro ◽  
Manuel Ocaña
Keyword(s):  
Aqueous Media ◽  
Colloidal Suspensions ◽  
Organic Additives

Nanometric, luminescent Eu:LuPO4 particles quickly (30 min) synthesised in the absence of organic additives and able to form stable colloidal suspensions in aqueous media.

scholarly journals Synthesis of Lipophilic Esters of Tyrosol, Homovanillyl Alcohol and Hydroxytyrosol

Antioxidants ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 174 ◽  
Author(s):  
Roberta Bernini ◽  
Isabella Carastro ◽  
Francesca Santoni ◽  
Mariangela Clemente
Keyword(s):  
Circular Economy ◽  
Room Temperature ◽  
Dimethyl Carbonate ◽  
Low Cost ◽  
Aqueous Media ◽  
Low Molecular Weight ◽  
Health Promoting ◽  
Hydrophilic Character ◽  
Valuable Compounds ◽  
By Products

Low-molecular weight phenols such as tyrosol, homovanillyl alcohol and hydroxytyrosol are valuable compounds that exhibit a high number of health-promoting effects such as antioxidant, anti-inflammatory and anticancer activity. Despite these remarkable properties, their applications such as dietary supplements and stabilizers of foods and cosmetics in non-aqueous media are limited for the hydrophilic character. With the aim to overcome this limitation, the paper describes a simple and low-cost procedure for the synthesis of lipophilic esters of tyrosol, homovanillyl alcohol and hydroxytyrosol. The reactions were carried out under mild and green chemistry conditions, at room temperature, solubilizing the phenolic compounds in dimethyl carbonate, an eco-friendly solvent, and adding a little excess of the appropriate C2–C18 acyl chloride. The final products were isolated in good yields. Finally, according to the “circular economy” strategy, the procedure was applied to hydroxytyrosol-enriched extracts obtained by Olea europaea by-products to prepare a panel of lipophilic extracts that are useful for applications where solubility in lipid media is required.

scholarly journals Biotransformation of Phytosterols to Androst-1,4-Diene-3,17-Dione by Mycobacterium sp. ZFZ Expressing 3-Ketosteroid-Δ1-Dehydrogenase

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 663
Author(s):  
Xiangcen Liu ◽  
Ruijie Zhang ◽  
Zhiwei Bao ◽  
Chenyang Yuan ◽  
Huijin Cao ◽  
...  
Keyword(s):  
Theoretical Basis ◽  
Aqueous Media ◽  
Waste Cooking Oil ◽  
Aqueous System ◽  
Molar Ratio ◽  
Separation And Purification ◽  
Downstream Process ◽  
Promoter Sequences ◽  
Cooking Oil ◽  
System A

As an important hormone drug intermediate, androst-1,4-diene-3,17-dione can be bio-converted from phytosterols. However, separation and purification in the downstream process are very difficult due to the similarity in structure and physiological characteristics between ADD and androstenedione (AD). This phenomenon was correlated to the insufficient enzyme activity of 3-ketosteroid-Δ1-dehydrogenase (KSDD), which specifically catalyzes the C1,2 dehydrogenation of AD. In order to obtain a highly purified ADD from phytosterols, the dehydrogenation effect of different kinds of KSDDs and the transcription effect of four promoter sequences on ksdd were analyzed in Mycobacterium sp. ZFZ (ZFZ), the cell host that transform phytosterols to AD in the oil-aqueous system. A tandem KSDD expression cassette containing strain ZFZ-2111 yielded 2.06 ± 0.09 g L−1 ADD, with a molar ratio of ADD/AD at 41.47:1.00 in 120 h. In waste cooking oil-aqueous media, the proportion of ADD in the fermentation by ZFZ-2111 was 92%. The present study provides a reliable theoretical basis for the step-by-step transformation of phytosterols to ADD.

scholarly journals Adsorptive  removal  of  malachite  green  dye  from  aqueous  solution  onto activated carbon of Catha edulis stem as a low cost bio-adsorbent

2020 ◽  
Author(s):  
Gietu yirga Abate ◽  
Adugna Nigatu Alene ◽  
Adere Tarekegne Habte ◽  
Desiew Mekuanint Getahun
Keyword(s):  
Activated Carbon ◽  
Low Cost ◽  
Aqueous Media ◽  
Freundlich Isotherm ◽  
Industrial Effluents ◽  
Aqueous System ◽  
Isotherm Models ◽  
Synthetic Dyes ◽  
Order Kinetic ◽  
Catha Edulis

Abstract Background: The release of hazardous synthetic dyes into industrial effluents has emerged as an environmental problem requiring remediation. The present study focused on the preparation of a new and environmentally-friendly material (adsorbent) for the remediation of aqueous media containing dye. The low cost adsorbent was prepared from locally available khat (Catha edulis) stem which considered as waste and accumulated on waste disposal areas of woldia town, Ethiopia. Comprehensive characterization studies were carried out on the bio-adsorbent such as proximate analyses, specific surface area, and Fourier-Transform Infrared (FTIR) spectroscopy (which shows functional groups on adsorbents surface). Results: The proximate analysis shows the prepared adsorbent has very high fixed carbon content (83.65%), which refers to high quality of the adsorbent. The adsorption performance of the prepared activated carbon was optimize by varying operating parameters such as initial dye concentration (10 mg/L), pH (10), dosage (0.5 g), and contact time (60 min). The maximum removal efficiency of the prepared adsorbent at those optimum conditions was 98.8%. The experimental data was tested by most common kinetics and isotherm models. It was observed that the pseudo-second-order kinetic model fits better with good correlation coefficient and the equilibrium data fitted well with the Freundlich isotherm model. Conclusion: In summery this study demonstrated that the waste bio sorbent could be employed as an effective and eco-friendly alternative for the cleanup of dye-polluted aqueous system.

Stimuli-triggered reversible switching mechanism between H- and J-type supramolecular assemblies of cationic porphyrins adsorbed on tungsten(VI) oxide surface

2018 ◽  
Vol 22 (08) ◽  
pp. 658-669 ◽  
Author(s):  
Kenta Adachi ◽  
Yukimasa Ura ◽  
Naoya Kanetada
Keyword(s):  
Rational Design ◽  
Aqueous Media ◽  
Coupling Model ◽  
Aqueous System ◽  
Inorganic Materials ◽  
Oxide Surface ◽  
Neutral System ◽  
Stimuli Responsive ◽  
Adsorption Model ◽  
Face To Face

Supramolecular organic dye–inorganic semiconductor nanocrystal assemblies are potentially useful in a broad range of technologies and applications, including photovoltaic systems, but the molecular basis of the adsorption of dye molecules onto the semiconductor surfaces remains poorly understood. Herein, we investigated the pH-dependent adsorption and conformational change of two cationic porphyrin stereoisomers [5,10-diphenyl-15,20-di([Formula: see text]-methyl-4-pyridyl)porphyrin (cis-DMPyP) and 5,15-diphenyl-10,20-di([Formula: see text]-methyl-4-pyridyl)porphyrin (trans-DMPyP)] on the tungsten(VI) oxide (WO[Formula: see text] colloid nanoparticle in aqueous media by means of UV-vis absorption spectroscopy. In accordance with the combination of a modified Langmuir adsorption model and Kasha’s exciton coupling model, the molecular orientation and stacking arrangement of DMPyP derivatives on the WO[Formula: see text] colloid surface are discussed in detail. In the trans-DMPyP/WO[Formula: see text] aqueous system, trans-DMPyP molecules adopted flat-on orientation with respect to the WO[Formula: see text] colloid surface and eventually formed head-to-tail [Formula: see text]-dimers regardless of pH conditions. cis-DMPyP molecules in the acidic system also lay flat-on and mainly formed [Formula: see text]-dimers on the WO[Formula: see text] colloid surface, whereas ones in the neutral system exhibited a dominant edge-on orientation and had a higher tendency to form face-to-face [Formula: see text]-dimers. Additionally, we have also convincingly demonstrated the pH-triggered switchable [Formula: see text]-stacking geometry of cis-DMPyP molecules from [Formula: see text]- to [Formula: see text]-dimer and vice versa on the WO[Formula: see text] colloid surface. Such findings will undoubtedly provide a pertinent guideline for the rational design of stimuli-responsive organic-inorganic materials.

Influence of low-molecular-weight and macromolecular organic additives on the morphology of calcium carbonate

1993 ◽  
Vol 89 (15) ◽  
pp. 2891 ◽  
Author(s):  
Jon M. Didymus ◽  
Peter Oliver ◽  
Stephen Mann ◽  
Arthur L. DeVries ◽  
Peter V. Hauschka ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Calcium Carbonate ◽  
Low Molecular Weight ◽  
Organic Additives
Sign in / Sign up

Export Citation Format

Share Document