scholarly journals Application of the Zimm-Bragg Model to the Removal of Azo Dyes with Pectin

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Juan Antonio Lozano-Álvarez ◽  
Juan Jáuregui-Rincón ◽  
Iliana E. Medina-Ramírez ◽  
Rogelio Salinas-Gutiérrez ◽  
Jorge Martín Alférez Chávez ◽  
...  
Keyword(s):  
Azo Dyes ◽  
Hydrophobic Interactions ◽  
Molecular Surface ◽  
High Tendency ◽  
Aqueous Effluents ◽  
Two Parameters ◽  
First Time ◽  
Cooperativity Parameter ◽  
Dye Molecule ◽  
Model Fits

In this work, the ability of pectin (Pec) to remove direct red 80 (DR80), Congo red (CR), methyl orange (MO), and methyl red (MR) was studied. The removal percentages under adequate pH and ionic strength conditions were as follows: DR80 (99.5%), CR (99.8%), MO (88.6%), and MR (68%), showing that this methodology is efficient to remove azo dyes. The proposed method included the addition of native Pec to the dye aqueous solution and the formation of a gel that occurred when a calcium salt solution was added. This gel retains the molecules adsorbed onto the molecular surface of Pec through hydrogen bonds and electrostatic and hydrophobic interactions. To our knowledge, it is the first time that the Zimm-Bragg model is used to describe the removal of azo dyes with native Pec. This model includes two parameters: K u (nucleation constant), which is related to the tendency exerted by a dye molecule attached to the Pec to bind to other molecules present in the aqueous phase, and U (cooperativity parameter), which determines the aggregation capacity of the dye molecules already attached to the Pec. This model fits the experimental isotherms very well, suggesting that Pec binds single molecules and dye aggregates. The obtained results in the values of K u ranged from 922 mol/kg (MR) to 1,157,462 mol/kg (CR), and U varied from 2.51 (MR) to 169.19 (MO). These results suggest that the use of Pec is a viable option to remove azo dyes from aqueous effluents and that the Zimm-Bragg model fits adequately the isotherms of dyes that have a high tendency to form aggregates.

A MODIFIED GENERALIZED LORENZ-TYPE SYSTEM AND ITS CANONICAL FORM

2009 ◽  
Vol 19 (06) ◽  
pp. 1931-1949 ◽  
Author(s):  
QIGUI YANG ◽  
KANGMING ZHANG ◽  
GUANRONG CHEN
Keyword(s):  
Special Form ◽  
Topological Structure ◽  
Complex Dynamics ◽  
Type System ◽  
Chaotic Attractors ◽  
Hopf Bifurcations ◽  
Compound Structure ◽  
Two Parameters ◽  
First Time ◽  
New System

In this paper, a modified generalized Lorenz-type system is introduced, which is state-equivalent to a simple and special form, and is parameterized by two parameters useful for chaos turning and system classification. More importantly, based on the parameterized form, two classes of new chaotic attractors are found for the first time in the literature, which are similar but nonequivalent in topological structure. To further understand the complex dynamics of the new system, some basic properties such as Lyapunov exponents, Hopf bifurcations and compound structure of the attractors are analyzed and demonstrated with careful numerical simulations.

Solvent Polarity Studies of the Water+t-Butyl Alcohol and Water+t-Butylamine Binary Systems With the Solvatochromic Dyes Nile Red and Pyridinium-N-phenoxide Betaine, Refractometry and Permittivity Measurements

1994 ◽  
Vol 47 (9) ◽  
pp. 1771 ◽  
Author(s):  
PK Kipkemboi ◽  
AJ Easteal
Keyword(s):  
Binary Systems ◽  
Hydrophobic Interactions ◽  
Nile Red ◽  
Solvent Polarity ◽  
Butyl Alcohol ◽  
Linear Functions ◽  
Non Linear ◽  
Organic Cosolvent ◽  
Two Parameters ◽  
Polarity Parameters

The empirical solvent polarity parameters ENR and ET for the solvatochromic compounds Nile Red (1) and pyridinium-N-phenoxide betaine (2), respectively, have been determined as a function of composition for water+t -butyl alcohol and water+t-butylamine binary mixtures, over the whole composition range at 298 K. For both systems the two parameters vary with composition in a strongly non-linear fashion, and the polarity of the mixture decreases with increasing proportion of the organic cosolvent. The non-linear variation of the polarity parameters is attributed to water-cosolvent hydrophobic interactions at low cosolvent contents, and hydrogen-bonding interactions at higher cosolvent contents. Permittivity and refractive index have also been measured at 298 K for both systems, and both properties are strongly non-linear functions of composition.

scholarly journals Exactly separable version of the Bohr Hamiltonian with the Davidson potential

2020 ◽  
Vol 16 ◽  
pp. 121
Author(s):  
D. Bonatsos ◽  
E. A. McCutchan ◽  
N. Minkov ◽  
R. F. Casten ◽  
P. Yotov ◽  
...  
Keyword(s):  
Dynamical Symmetry ◽  
Transition Rates ◽  
Stiffness Parameter ◽  
Oscillator Potential ◽  
Harmonic Oscillator Potential ◽  
Boson Model ◽  
Two Parameters ◽  
Almost All ◽  
First Time ◽  
Davidson Potential

An exactly separable version of the Bohr Hamiltonian, is obtained by using a potential of the form V (β, γ) = u(β) + u(γ)/β2, with a Davidson potential for u(β) and a stiff harmonic oscillator potential centered around γ = 0o, for u(γ).Using two parameters (β0 and the γ-stiffness parameter) the band features and B(E2) transition rates of almost all well-deformed rare-earth and actinide nuclei are reproduced, while the spectrum of the SU(3) dynamical symmetry of the Interacting Boson Model can be obtained, for the first time using the Bohr Hamiltonian.

scholarly journals Bone Morphogenetic Protein 2 (BMP-2) Aggregates Can be Solubilized by Albumin—Investigation of BMP-2 Aggregation by Light Scattering and Electrophoresis

Pharmaceutics ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1143
Author(s):  
Julius Sundermann ◽  
Holger Zagst ◽  
Judith Kuntsche ◽  
Hermann Wätzig ◽  
Heike Bunjes
Keyword(s):  
Light Scattering ◽  
Bone Morphogenetic Protein ◽  
Electrostatic Interactions ◽  
Hydrophobic Interactions ◽  
Pharmaceutical Research ◽  
Bone Morphogenetic Protein 2 ◽  
Growth Factor Delivery ◽  
Surface Charges ◽  
High Tendency ◽  
Morphogenetic Protein

Bone morphogenetic protein 2 (BMP-2) has a high tendency to aggregate at physiological pH and physiological ionic strength, which can complicate the development of growth factor delivery systems. The aggregation behavior in differently concentrated BMP-2 solutions was investigated using dynamic and static light scattering. It was found that at higher concentrations larger aggregates are formed, whose size decreases again with increasing dilution. A solubilizing effect and therefore less aggregation was observed upon the addition of albumin. Imaged capillary isoelectric focusing and the simulation of the surface charges of BMP-2 were used to find a possible explanation for the unusually low solubility of BMP-2 at physiological pH. In addition to hydrophobic interactions, attractive electrostatic interactions might be decisive in the aggregation of BMP-2 due to the particular distribution of surface charges. These results help to better understand the solubility behavior of BMP-2 and thus support future pharmaceutical research and the development of new strategies for the augmentation of bone healing.

scholarly journals Association between homocysteine, vitamin B12, folic acid and erectile dysfunction: a cross-sectional study in China

BMJ Open ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. e023003 ◽  
Author(s):  
Yang Chen ◽  
Jie Li ◽  
Tianyu Li ◽  
Jianxiong Long ◽  
Jinling Liao ◽  
...  
Keyword(s):  
Erectile Dysfunction ◽  
Folic Acid ◽  
Multinomial Logistic Regression ◽  
Cross Sectional Study ◽  
Living Alone ◽  
Sectional Study ◽  
Cross Sectional ◽  
Two Parameters ◽  
First Time ◽  
The Relationship

ObjectivesErectile dysfunction (ED) affects up to 53.4% of men aged 30–80 years. In this study, we aimed to examine the association between homocysteine (HCY), vitamin B12(B12), folic acid (FA) and ED.DesignCross-sectional study.SettingGuangxi, China.ParticipantsA total of 1381 participants who completed questionnaires were included, between September 2009 and December 2009.MeasuresED was evaluated by the International Index of Erectile Function scores. Also, the values of HCY, B12 and FA were acquired. Then, regression and between-group analyses were performed.ResultsNo association between FA and ED was found. Significant correlations between HCY and ED were found—the relationships between these two parameters were most notable in men aged over 60 years and in men living alone (bachelors or bachelorhood). B12 levels were higher in men with ED (718.53±234.37 pg/mL vs 688.74±229.68, p=0.015). Using multinomial logistic regression analyses, B12 levels were related to mild ED (multivariate adjusted analysis: OR 1.620, 95% CI 1.141 to 2.300, p=0.007), especially among men aged 40–49 years (OR 2.907, 95% CI 1.402 to 6.026, p=0.004).ConclusionsWe report, for the first time, a relationship between B12 levels and ED. We also found specific cohorts of men for whom the relationship between HCY levels and ED is most prominent. Further studies are required to elucidate the mechanisms underlying these relationships—these may ultimately result in new therapies for ED.

Decontamination of the Special Drainage System at NPP A-1

2001 ◽  
Author(s):  
Ján Rezbárik ◽  
Dušan Majerský ◽  
Stanislav Sekely
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Specific Activity ◽  
Drainage System ◽  
Solid Particles ◽  
Technological Systems ◽  
Solid Product ◽  
High Tendency ◽  
First Time

Abstract The first Czecho-slovak nuclear power plant A-1 was shut down after an accident in 1977 and it is now under decommissioning. In spite of that, some technological systems in nuclear power plant must remain in operation. The planned service life of these systems has already been exceeded and their technical design is not suitable for present requirements. These operated technological systems must be repaired and reconstructed. The special drainage system is one of the technological systems that must be in operation during the decommissioning process. After twenty-nine-year’-s of operation it became necessary to carry out the repairs, adaptations and replacements of some parts of this system with the aim to ensure more reliable operation and higher safety. Radioactive sludge from the bottom of the collecting tank and drain pit was pumped out using an ejector and it was caught in drums. The fixed contamination on the inner surface of the collecting tank was removed by the chemical loop decontamination method using an external circulating decontamination device. The surface of the drain pit was decontaminated with evenly spread decontamination gel that disrupted the fixed contamination. The contamination was then washed down using a water jet system with attached rotary brushes. At NPP A-1, an immobilisation method for the treatment of radioactive sludge and solid particles based on the addition of silicates was successfully used by AllDeco for the first time. This sludge is often sticky with the high tendency to settle out the liquid and has a specific activity three orders of magnitude higher than are the limits for the Conditioning Centre (with high content of alpha radionuclides) and because it is not sound and effective to treat it by technologies generally used for another type of wastes. The immobilisation of the sludge was performed at room temperature. The resulting solid product has suitable properties for temporary storage. Procedures for the verification of the treatment of further sludge from NPP A-1 have been started.

scholarly journals Capacitative Ca2+ Entry Is Closely Linked to the Filling State of Internal Ca2+ Stores: A Study Using Simultaneous Measurements of ICRAC and Intraluminal [Ca2+]

1998 ◽  
Vol 140 (2) ◽  
pp. 325-334 ◽  
Author(s):  
Aldebaran M. Hofer ◽  
Cristina Fasolato ◽  
Tullio Pozzan
Keyword(s):  
Intact Cells ◽  
Soluble Factors ◽  
Intrinsic Kinetics ◽  
Simultaneous Measurements ◽  
Store Depletion ◽  
Cell Recording ◽  
Two Parameters ◽  
First Time ◽  
Kinetics Of ◽  
Filling State

ICRAC (the best characterized Ca2+ current activated by store depletion) was monitored concurrently for the first time with [Ca2+] changes in internal stores. To establish the quantitative and kinetic relationship between these two parameters, we have developed a novel means to clamp [Ca2+] within stores of intact cells at any level. The advantage of this approach, which is based on the membrane-permeant low-affinity Ca2+ chelator N,N,N′,N′-tetrakis (2-pyridylmethyl)ethylene diamine (TPEN), is that [Ca2+] within the ER can be lowered and restored to its original level within 10–15 s without modifications of Ca2+ pumps or release channels. Using these new tools, we demonstrate here that Ca2+ release–activated Ca2+ current (ICRAC) is activated (a) solely by reduction of free [Ca2+] within the ER and (b) by any measurable decrease in [Ca2+]ER. We also demonstrate that the intrinsic kinetics of inactivation are relatively slow and possibly dependent on soluble factors that are lost during the whole-cell recording.

Optimised photocatalytic degradation of a mixture of azo dyes using a TiO2/H2O2/UV process

2012 ◽  
Vol 65 (8) ◽  
pp. 1392-1398 ◽  
Author(s):  
Soraya Moreno Palácio ◽  
Fernando Rodolfo Espinoza-Quiñones ◽  
Aparecido Nivaldo Módenes ◽  
Diego Ricieri Manenti ◽  
Cláudio Celestino Oliveira ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Azo Dyes ◽  
Irradiation Time ◽  
Optimum Conditions ◽  
Order Model ◽  
Kinetic Rate Constant ◽  
Kinetic Rate ◽  
Full Factorial Experimental Design ◽  
Two Parameters ◽  
Full Factorial

The aim of the present study was to optimise the photocatalytic degradation of a mixture of six commercial azo dyes, by exposure to UV radiation in an aqueous solution containing TiO2-P25. Response surface methodology, based on a 32 full factorial experimental design with three replicates was employed for process optimisation with respect to two parameters: TiO2 (0.1–0.9 g/L) and H2O2 (1–100 mmol/L). The optimum conditions for photocatalytic degradation were achieved at concentrations of 0.5 g TiO2/L and 50 mmol H2O2/L, respectively. Dye mineralisation was confirmed by monitoring TOC, conductivity, sulfate and nitrate ions, with a sulfate ion yield of 96% under optimal reactor conditions. Complete decolorisation was attained after 240 min irradiation time for all tested azo-dyes, in a process which followed a pseudo-first kinetic order model, with a kinetic rate constant of approximately 0.018 min−1. Based on these results, this photocatalytic process has promise as an alternative for the treatment of textile effluents.

Wiener Indices and Molecular Surfaces

1995 ◽  
Vol 50 (7) ◽  
pp. 669-671 ◽  
Author(s):  
Ivan Gutmana ◽  
Tamás Körtvélyesi
Keyword(s):  
Volume Ratio ◽  
Wiener Index ◽  
Molecular Surface ◽  
Molecular Volume ◽  
Saturated Hydrocarbons ◽  
Molecular Surfaces ◽  
Physico Chemical ◽  
First Time

A correlation between the Wiener index (W) and the molecular surface of the respective alkane is established for the first time. This correlation is curvilinear and not particularly good. W is only weakly correlated to molecular volume of saturated hydrocarbons and does not reflect at all their surface-to-volume ratio. By this a long-existing controversy concerning the physico-chemical interpretation of W is resolved.

Association Behavior of the Synthetic Protein-Lipid Complex Analogues

2012 ◽  
Vol 506 ◽  
pp. 134-137
Author(s):  
P. Punyamoonwongsa ◽  
B.J. Tighe
Keyword(s):  
Conformational Transition ◽  
Hydrophobic Interactions ◽  
Analytical Techniques ◽  
Lipid Phase ◽  
Aqueous Environment ◽  
Lipid Complex ◽  
Synthetic Protein ◽  
Association Behavior ◽  
Pharmaceutical Industries ◽  
First Time

Hypercoiling poly (styrene-alt-maleic anhydride) (PSMA) is known to undergo conformational transition in response to environmental stimuli. This behavior allows it to associate with the phospholipid,2-dilauryl-sn-glycero-3-phosphocholine (DLPC) to produce nanostructures analogous to lipoproteins. The complex represents a new bio-mimetic delivery vehicle with applications in the cosmetic and pharmaceutical industries. This study investigates, for the first time, the association behavior of PSMA and DLPC through the combination of different analytical techniques. The results indicate that the association is primarily driven by hydrophobic interactions and depends on various factors including the polymer/lipid ratio, the polymer molecular weight and the pH of the aqueous environment. The conformational transition of PSMA leads to the formation of discrete micellar complexes involving anisotropic-to-isotropic lipid phase transformation. As the number of hydrophobic moieties in the polymer is increased, the pH-dependent conformational transition of the polymer plays less important part in achieving this phase transition of the lipid.

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