Study on the Effect of an Electrolyte on the Self-Aggregation and the Geometry of the Dye Aggregates of Methylene Blue in Aqueous Media

2016 ◽  
Vol 32 (1-2) ◽  
pp. 27
Author(s):  
Ng. Florence ◽  
H. Naorem
Keyword(s):  
Methylene Blue ◽  
Twist Angle ◽  
Aqueous Media ◽  
Least Square ◽  
The Self ◽  
Aggregation Process ◽  
Dimerization Constant ◽  
Sandwich Type ◽  
Linear Least Square ◽  
Self Aggregation

The self-aggregation of Methylene Blue (MB) dye in aqueous media has been investigated spectrophotometrically in presence of sodium chloride (NaCl) at 293.15, 303.15 and 313.15K. The dimerization constant (K<sub>D</sub>) of the MB dye in aqueous solution with or without the electrolyte has been computed using a non-linear least square regression technique. It is observed that presence of the electrolyte resulted into sharp increase in K<sub>D</sub> of MB indicating that presence of the electrolyte favours formation of dye aggregates. There is, however, a decrease in K<sub>D</sub> with increase in temperature. From the observed spectra of the dye, the twist (θ<sub>1</sub>) and the tilt (θ<sub>2</sub>) angles between the dipoles of MB molecules in the aggregates have been computed based on exciton model. Change in the monomeric fractions of the dye (α) in presence of the added electrolyte as a function of the dye concentration has also been computed. The results indicated that the dye aggregates formed is essentially of the sandwich type geometry (H-aggregates) with a slight deviation from an exact parallel stacking arrangement and reduced twist angle. The thermodynamic parameters of the aggregation process in presence of the electrolyte have been evaluated from the temperature dependence of K<sub>D</sub>. It is observed that the aggregation process is an enthalpy rather than entropy controlled one.

Derived chromatographic indices as effective tools to study the self-aggregation process of bile acids

2009 ◽  
Vol 50 (4) ◽  
pp. 613-621 ◽  
Author(s):  
Benedetto Natalini ◽  
Roccaldo Sardella ◽  
Emidio Camaioni ◽  
Antonio Macchiarulo ◽  
Antimo Gioiello ◽  
...  
Keyword(s):  
Bile Acids ◽  
The Self ◽  
Aggregation Process ◽  
Self Aggregation

New insights about the self-aggregation of benzoporphyrin derivatives: A theoretical and experimental investigation

2018 ◽  
Vol 22 (04) ◽  
pp. 342-354 ◽  
Author(s):  
Gabriel B. Cesar ◽  
Diogo S. Pellosi ◽  
Douglas Vanzin ◽  
Renato S. Gonçalves ◽  
Wilker Caetano ◽  
...  
Keyword(s):  
Sodium Dodecyl ◽  
Ester Group ◽  
The Self ◽  
Van Der Waals Interactions ◽  
Molecular Volume ◽  
Aggregation Process ◽  
New Development ◽  
Self Aggregation

The self-aggregation process and its overcoming remain a barrier for the employment of many molecules as photosensitizers (PS) in photodynamic therapy (PDT). The B-ring isomer co-produced during the synthesis of the Verteporfin[Formula: see text] (A-ring) is an example. Although both isomers possess similar in vitro/in vivo efficiency, the strong and not well-understood self-aggregation process of the B-ring derivative impairs its clinical use. This paper reports the use of theoretical calculus and its correlation with experimental analysis to find the main differences between the A and B-ring isomers. For that purpose, micelles of Pluronic[Formula: see text] P-123 and Sodium Dodecyl Sulfate were chosen as simple membrane models and possible drug delivery system, as in the case of P-123. At physiological pH, the main reason for the high self-aggregation tendency is associated with the higher (22%) molecular volume of the B ring, which increases the van der Waals interactions. However, at mildly acidic conditions, the B ring possesses a shallow dihedral angle between the methyl ester group and the tetrapyrrolic macrocycle that favors the approach of units in the aggregate. These discrepancies directly affect the binding and stability of the isomers in the micelles. However, P-123 micelles were able to readily incorporate and monomerize/stabilize both PS over long periods. NOESY experiments confirmed a deep location of both PS inside P-123 micelles, which justifies their efficiency in preventing the self-aggregation process. These findings may substantiate new studies involving the marginalized B-ring isomers and encourage new development in formulations for their use in PDT.

Hybrid surfactants decorated with copper ions: aggregation behavior, antimicrobial activity and anti-proliferative effect

2016 ◽  
Vol 18 (34) ◽  
pp. 23961-23970 ◽  
Author(s):  
Gurpreet Kaur ◽  
Sandeep Kumar ◽  
Neeraj Dilbaghi ◽  
Gaurav Bhanjana ◽  
Santosh Kumar Guru ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Biological Activity ◽  
Copper Ions ◽  
Aqueous Media ◽  
Aggregation Behavior ◽  
The Self ◽  
Proliferative Effect ◽  
Self Aggregation

In the present study, the emphasis is laid on the self aggregation behavior and biological activity of copper based inorganic–organic hybrids in aqueous media.

Temperature Dependence of the Self-Assembled Styrene Based Random Ionomers in Aqueous Solution

2003 ◽  
Vol 775 ◽  
Author(s):  
Sung-Hwa Oh ◽  
Ju-Myung Song ◽  
Joon-Seop Kim ◽  
Hyang-Rim Oh ◽  
Jeong-A Yu
Keyword(s):  
Partition Coefficients ◽  
Room Temperature ◽  
Aqueous Media ◽  
The Self ◽  
Spectroscopic Methods ◽  
Ion Content ◽  
Repeat Units ◽  
Notable Effect ◽  
Order Of Magnitude ◽  
Experimental Errors

AbstractSolution behaviors of poly(styrene-co-sodium methacrylate) were studied by fluorescence spectroscopic methods using pyrene as a probe. The mol% of methacrylate was in the range 3.6–9.4. Water and N,N-dimethylforamide(DMF) mixture was used as a solvent (DMF/water = 0.2 mol %). The critical micelle (or aggregation) concentrations of ionomers and the partition coefficients of pyrene were obtained the temperature range 10–80°C. At room temperature, the values of CMCs (or CACs) were in the range 4.7 ×10-6 5.3 ×10-6 g/mL and we could not find any notable effect of the content of ionic repeat units within the experimental errors. Unlike CMCs, as the ion content increased, partitioning of pyrene between the hydrophobic aggregates and an aqueous media decreased from 1.5 ×105 to 9.4 ×104. As the temperature increased from 10 to 80 °C, the values of CMCs increased less than one order of magnitude. While, the partition coefficients of pyrene decreased one order of magnitude and the effect of the ion content became negligible.

GPS-DERIVED SECULAR VELOCITY FIELD AROUND SANGIHE ISLAND AND ITS IMPLICATION TO THE MOLUCCA SEA SEISMICITY

GEOMATIKA ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 107
Author(s):  
Leni Sophia Heliani ◽  
Cecep Pratama ◽  
Parseno Parseno ◽  
Nurrohmat Widjajanti ◽  
Dwi Lestari
Keyword(s):  
Surface Displacement ◽  
Active Regions ◽  
Least Square ◽  
The Other ◽  
Gps Data ◽  
West Side ◽  
Active Deformation ◽  
Secular Motion ◽  
Small Change ◽  
Linear Least Square

<p><em>Sangihe-Moluccas region is the most active seismicity in Indonesia. Between 2015 to 2018 there is four M6 class earthquake occurred close to the Sangihe-Moluccas region. These seismic active regions representing active deformation which is recorded on installed GPS for both campaign and continuous station. However, the origin of those frequent earthquakes has not been well understood especially related to GPS-derived secular motion. Therefore, we intend to estimate the secular motion inside and around Sangihe island. On the other hand, we also evaluate the effect of seismicity on GPS sites. Since our GPS data were conducted on yearly basis, we used an empirical global model of surface displacement due to coseismic activity. We calculate the offset that may be contained in the GPS site during its period</em><em>. </em><em>We remove the offset and estimate again the secular motion using linear least square. Hence, in comparison with the secular motion without considering the seismicity, we observe small change but systematically shifting the motion. We concluded the seismicity in the Molucca sea from 2015 to 2018 systematically change the secular motion around Sangihe Island at the sub-mm level. Finally, we obtained the secular motion toward each other between the east and west side within 1 to 5.5 cm/year displacement. </em></p>

scholarly journals An Indoor Visible Light Positioning System Using Tilted LEDs with High Accuracy

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 920
Author(s):  
Neha Chaudhary ◽  
Othman Isam Younus ◽  
Luis Nero Alves ◽  
Zabih Ghassemlooy ◽  
Stanislav Zvanovec ◽  
...  
Keyword(s):  
Visible Light ◽  
Polynomial Regression ◽  
Power Level ◽  
Least Square ◽  
Line Of Sight ◽  
Received Power ◽  
Strength Based ◽  
Complex Linear ◽  
Linear Least Square ◽  
First Time

The accuracy of the received signal strength-based visible light positioning (VLP) system in indoor applications is constrained by the tilt angles of transmitters (Txs) and receivers as well as multipath reflections. In this paper, for the first time, we show that tilting the Tx can be beneficial in VLP systems considering both line of sight (LoS) and non-line of sight transmission paths. With the Txs oriented towards the center of the receiving plane (i.e., the pointing center F), the received power level is maximized due to the LoS components on F. We also show that the proposed scheme offers a significant accuracy improvement of up to ~66% compared with a typical non-tilted Tx VLP at a dedicated location within a room using a low complex linear least square algorithm with polynomial regression. The effect of tilting the Tx on the lighting uniformity is also investigated and results proved that the uniformity achieved complies with the European Standard EN 12464-1. Furthermore, we show that the accuracy of VLP can be further enhanced with a minimum positioning error of 8 mm by changing the height of F.

scholarly journals Self-Cleaning Polyester Fabric Prepared with TiOF2 and Hexadecyltrimethoxysilane

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 387
Author(s):  
Euigyung Jeong ◽  
Heeju Woo ◽  
Yejin Moon ◽  
Dong Yun Lee ◽  
Minjung Jung ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Contact Angle ◽  
Treatment Method ◽  
Polyester Fabric ◽  
Anatase Tio2 ◽  
The Self ◽  
Water Contact ◽  
Direct Fluorination ◽  
Tomato Ketchup ◽  
Self Cleaning

In this study, self-cleaning polyester (PET) fabrics were prepared using TiOF2 and hexadecyltrimethoxysilane(HDS) treatment. TiOF2 was synthesized via direct fluorination of a precursor TiO2 at various reaction temperatures. The prepared PET fabrics had superior photocatalytic self-cleaning properties compared with anatase TiO2/HDS-treated PET fabrics under UV and sunlight with 98% decomposition of methylene blue. TiOF2/HDS-treated PET fabrics also had superior superhydrophobic self-cleaning properties compared with anatase TiO2/HDS-treated PET fabrics with a 161° water contact angle and 6° roll-off angle. After the self-cleaning tests of the non-dyed TiOF2/HDS-treated PET fabrics, we prepared dyed TiOF2/HDS-treated PET fabrics to test practical aspects of the treatment method. These PET fabrics were barely stained by tomato ketchup; even when stained, they could be self-cleaned within 4 h. These results suggest that practical self-cleaning PET fabrics with superhydrophobicity and photocatalytic degradation could be prepared using TiOF2/HDS-treatment.

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