scholarly journals Effect of Blends of Benzotriazole and Thiourea on the Anodic Dissolution of Copper

2002 ◽  
Vol 20 (5) ◽  
pp. 485-494 ◽  
Author(s):  
E.A. Ashour ◽  
H.S. Hegazy ◽  
B.G. Ateya
Keyword(s):  
Free Energy ◽  
Anodic Dissolution ◽  
Hydrogen Sulphide ◽  
Copper Surface ◽  
Antagonistic Effect ◽  
Adsorption Behaviour ◽  
Free Energy Of Adsorption ◽  
Antagonistic Effects ◽  
Low Concentrations ◽  
The Individual

The blending of benzotriazole (BTAH) and thiourea (TU) was shown to exert synergistic or antagonistic effects on the anodic dissolution of copper at pH ≈ 1.8 depending on their concentrations in the blend. While synergism was observed in blends with low concentrations of TU and BTAH, antagonism was observed in blends containing higher, i.e. ≥ 10−2 M, concentrations of TU to an extent which increased with the concentration of TU. The antagonistic effect of TU was discussed in the light of its tendency to produce hydrogen sulphide which promotes the anodic dissolution of copper. Analysis of the adsorption behaviour of the individual compounds using the Langmuir isotherm revealed stronger interaction of the copper surface with BTAH than with TU, as judged by free energy of adsorption values of −18.8 and −8.7 kJ/mol for BTAH and TU, respectively.

scholarly journals Butylidenephthalide Blocks Potassium Channels and Enhances Basal Tension in Isolated Guinea-Pig Trachea

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hsin-Te Hsu ◽  
You-Lan Yang ◽  
Wan-Chen Chen ◽  
Chi-Ming Chen ◽  
Wun-Chang Ko
Keyword(s):  
Guinea Pig ◽  
Calcium Channel Blockers ◽  
Relaxation Curve ◽  
Antagonistic Effect ◽  
Channel Blockers ◽  
Krebs Solution ◽  
Antagonistic Effects ◽  
Individual Effects ◽  
Isolated Trachea ◽  
The Individual

Butylidenephthalide (Bdph, 30~300 μM), a constituent ofLigusticum chuanxiongHort., significantly enhanced tension in isolated guinea-pig trachea. In this study, we investigate the mechanism(s) of Bdph-induced contraction in the tissue. Isolated trachea was bathed in 5 mL of Krebs solution containing indomethacin (3 μM), and its tension changes were isometrically recorded. Cromakalim (3 μM), an ATP-dependent K+channel opener, significantly antagonized the Bdph-induced enhancement of baseline tension. Bdph (300 μM) also significantly antagonized cromakalim-induced relaxation. Bdph (300 μM) did not significantly influence the antagonistic effects of glibenclamide (GBC, 1 μM) and tetraethylammonium (TEA, 8 mM) against the cromakalim-induced relaxation. However, Bdph (300 μM) and 4-aminopiridine (4-AP, 5 mM), a blocker of Kv1 family of K+channels, in combination significantly rightward shifted the log concentration-relaxation curve of cromakalim. The antagonistic effect of the combination almost equals the sum of the individual effects of Bdph and 4-AP, suggesting that the antagonistic mechanism of Bdph may be similar to that of 4-AP. All calcium channel blockers influenced neither the baseline tension nor antagonistic effect of Bdph against cromakalim. In conclusion, Bdph may be similar to 4-AP, a blocker of Kv1 family of K+channels, to enhance the baseline tension of guinea-pig trachea.

scholarly journals Adsorption of Tributyl Phosphate on Silica Gel

2001 ◽  
Vol 19 (3) ◽  
pp. 211-217 ◽  
Author(s):  
V.F. Sazonova ◽  
M.A. Kojemyak ◽  
O.V. Perlova
Keyword(s):  
Free Energy ◽  
Silica Gel ◽  
Tributyl Phosphate ◽  
Physical Nature ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Water Molecules ◽  
Adsorption Behaviour ◽  
Free Energy Of Adsorption ◽  
Adsorption Layers

The adsorption behaviour of tributyl phosphate (TBP) on silica gel was studied. It was found that the adsorption isotherm shapes were complicated, being considered as S- and L-type isotherms according to the Giles classification. Adsorption itself was polymolecular and of a physical nature, the first adsorptive layer involving hydrogen bonding between the protons of surface silanol groups and the electron-donating oxygen atom of the adsorbate molecule. Subsequent adsorption layers were formed via van der Waals interaction. The free energy of adsorption of the system lay between −22.1 kJ/mol and −23.8 kJ/mol. The enthalpy change was negative and very small, i.e. −6.3 kJ/mol, while the entropy change was positive and in the range 53.9 J/(mol K) to 55.4 J/(mol K). The increase in entropy was explained in terms of the mobility of the TBP molecules in the adsorptive layer arising from their replacement on the silica gel surface by water molecules derived from the aqueous medium.

In vivo Experiments of Natural Products Protection of Antagonistic Effects of Lead on Iron

2018 ◽  
Vol 68 (12) ◽  
pp. 2747-2751
Author(s):  
Marioara Nicula ◽  
Nicolae Pacala ◽  
Lavinia Stef ◽  
Ioan Pet ◽  
Dorel Dronca ◽  
...  
Keyword(s):  
Aquatic Environment ◽  
Iron Homeostasis ◽  
Iron Concentration ◽  
Antagonistic Effect ◽  
Tissue Samples ◽  
Antagonistic Effects ◽  
In Vivo Experiments ◽  
Living Organisms ◽  
Toxic Potential

Living organisms take nutrients from the environment, and together with them, substances with toxic potential � such as heavy metals. Lead is one common metal pollutant especially in aquatic environment, from where the fish can be intoxicated very easily. Bioavailability, distribution, toxic action, synergistic and antagonistic effects are characteristics which can alter the fish health. Our experimental study followed the effects of lead overload in water on iron distribution, in different tissues sample Carassius gibelio Bloch fish. We performed the experiment in four different fish groups: control C; lead � Pb (administration of lead in water 0.075mg/mL of water, as Pb(NO3)2 x � H2O); lead (the same dose) and 2% of freeze-dry garlic incorporated into fishes� food � Pb+garlic; lead (the same dose) and 2% chlorella incorporated into fishes� food � Pb+chlorella, for 21 consecutive days. The iron concentration was analysed with AAS (Atomic Absorption Spectroscopy) from gills, muscle, skin (and scales), intestine, liver, heart, brain, ovary, testicles, and kidney. The obtained data presented a significantly decrease of iron content in all tested tissue samples that demonstrated, alteration of iron homeostasis, explained by a strong antagonistic effect of lead on iron. Our experiment showed that biologic active principles from garlic and chlorella act like natural protectors, and potentiate the iron deficiency even in the case of lead overload in aquatic environment, for fish.

GC-MS, HPLC, TLC of Dorycnium herbaceum Tincture Species and Synergistic / Antagonist Effect Testing in Combination with Antibiotics

2017 ◽  
Vol 68 (2) ◽  
pp. 228-231 ◽  
Author(s):  
Renata Maria Varut ◽  
Luciana Teodora Rotaru
Keyword(s):  
Chemical Composition ◽  
Clavulanic Acid ◽  
Carboxylic Acids ◽  
Therapeutic Effect ◽  
Antagonistic Effect ◽  
Hydroalcoholic Extract ◽  
Low Concentrations ◽  
Amoxicillin Clavulanic Acid ◽  
Reference Strains ◽  
Antagonist Effect

The study objectives were to determine the chemical composition and the synergistic / antagonistic effect of the association between hydroalcoholic extract from the Dorycnii pentaphylli herba (DPH) and the antibiotics of choice, on five reference strains. The tincture contains flavonoids and polyphenol carboxylic acids in low concentrations. DPH has an antagonistic effect on three of the drugs tested (amoxicillin + clavulanic acid, levofloxacin, amikacin), the therapeutic effect being completely canceled and has no significant effect on two of them (ceftazidime, cefotaxime).

Microtox evaluation of industrial wastewaters

1994 ◽  
Vol 30 (10) ◽  
pp. 97-106 ◽  
Author(s):  
Cheng-Fang Lin ◽  
Oliver J. Hao ◽  
Fu-Tien Jeng
Keyword(s):  
Treatment Process ◽  
Antagonistic Effect ◽  
Industrial Wastes ◽  
Activated Sludge Process ◽  
Industrial Parks ◽  
Close Relationship ◽  
Microtox Assay ◽  
Microtox Toxicity ◽  
The Individual ◽  
Final Effluent

The main purpose of this study was to establish an inhibitory database using the Microtox assay for different wastes. The waste samples included 19 pretreated industrial wastes from two different industrial parks, 11 other industrial wastes outside industrial parks, and different treatment process effluents. The following is a brief summary of the findings from this study: (1) COD and BOD had a close relationship among different wastes; (2) Microtox data did not correlate with the conventional parameters of BOD, COD and SS; (3) many wastes did not meet the pretreatment standards and exhibited high Microtox toxicity; (4) some wastes exhibited high Microtox toxicity, although they met the pretreatment standards; (5) the mixture of the individual wastes exhibited an antagonistic effect; (6) the activated sludge process removed 60-75% of influent toxicity; and (7) the final effluent sometimes showed an increase in Microtox toxicity.

scholarly journals Synergistic and Antagonistic Effects of Sodium Molybdate-Zn2+System

2012 ◽  
Vol 9 (4) ◽  
pp. 1746-1752 ◽  
Author(s):  
J. Wilson Sahayaraj ◽  
A. John Amalraj ◽  
Susai Rajendran ◽  
N. Vijaya
Keyword(s):  
Aqueous Solution ◽  
Weight Loss ◽  
Inhibition Efficiency ◽  
Sodium Molybdate ◽  
Antagonistic Effect ◽  
Protective Film ◽  
Antagonistic Effects ◽  
Polarization Study ◽  
Weight Loss Method ◽  
Loss Method

The inhibition efficiency (IE) of sodium molybdate (SM) in controlling corrosion of carbon steel in an aqueous solution containing 120 ppm of Cl-, in the absence and presence of Zn2+has been evaluated by weight-loss method. A synergistic effect exists between SM and Zn2+when the concentration of Zn2+is 25 ppm and above. Inhibition efficiencies obtained are greater than 85%. Antagonistic effect exists between SM and Zn2+when the concentration of Zn2+is 10 ppm and below. The SM-Zn2+system shows excellent IE up to third day. Above third day IE decreases. Acceleration of corrosion takes place. Excellent IE is shown at pH 5,7 and 12. At pH 9, IE decreases since Zn2+is precipitated as Zn(OH)2in the bulk of the solution. Polarization study reveals that SM-Zn2+system functions as a mixed inhibitor. FTIR spectra reveal that the protective film consists of Fe2+-SM complex and Zn(OH)2.

Examining sharp restart in a Monte Carlo method for the linearized Poisson–Boltzmann equation

2020 ◽  
Vol 26 (3) ◽  
pp. 223-244
Author(s):  
W. John Thrasher ◽  
Michael Mascagni
Keyword(s):  
Monte Carlo ◽  
Free Energy ◽  
Monte Carlo Algorithm ◽  
Significant Bias ◽  
Poisson Boltzmann ◽  
Electrostatic Free Energy ◽  
Poisson Boltzmann Equation ◽  
The Stability ◽  
Potential Methods ◽  
The Individual

AbstractIt has been shown that when using a Monte Carlo algorithm to estimate the electrostatic free energy of a biomolecule in a solution, individual random walks can become entrapped in the geometry. We examine a proposed solution, using a sharp restart during the Walk-on-Subdomains step, in more detail. We show that the point at which this solution introduces significant bias is related to properties intrinsic to the molecule being examined. We also examine two potential methods of generating a sharp restart point and show that they both cause no significant bias in the examined molecules and increase the stability of the run times of the individual walks.

scholarly journals The maintenance of polygenic sex determination depends on the dominance of fitness effects which are predictive of the role of sexual antagonism

2021 ◽  
Author(s):  
Richard P Meisel
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
House Fly ◽  
Sexual Antagonism ◽  
Antagonistic Effects ◽  
Fitness Effects ◽  
Y Chromosomes ◽  
Sexually Antagonistic Selection ◽  
The Individual ◽  
Polygenic Sex Determination

Abstract In species with polygenic sex determination, multiple male- and female-determining loci on different proto-sex chromosomes segregate as polymorphisms within populations. The extent to which these polymorphisms are at stable equilibria is not yet resolved. Previous work demonstrated that polygenic sex determination is most likely to be maintained as a stable polymorphism when the proto-sex chromosomes have opposite (sexually antagonistic) fitness effects in males and females. However, these models usually consider polygenic sex determination systems with only two proto-sex chromosomes, or they do not broadly consider the dominance of the alleles under selection. To address these shortcomings, I used forward population genetic simulations to identify selection pressures that can maintain polygenic sex determination under different dominance scenarios in a system with more than two proto-sex chromosomes (modeled after the house fly). I found that overdominant fitness effects of male-determining proto-Y chromosomes are more likely to maintain polygenic sex determination than dominant, recessive, or additive fitness effects. The overdominant fitness effects that maintain polygenic sex determination tend to have proto-Y chromosomes with sexually antagonistic effects (male-beneficial and female-detrimental). In contrast, dominant fitness effects that maintain polygenic sex determination tend to have sexually antagonistic multi-chromosomal genotypes, but the individual proto-sex chromosomes do not have sexually antagonistic effects. These results demonstrate that sexual antagonism can be an emergent property of the multi-chromosome genotype without individual sexually antagonistic chromosomes. My results further illustrate how the dominance of fitness effects has consequences for both the likelihood that polygenic sex determination will be maintained as well as the role sexually antagonistic selection is expected to play in maintaining the polymorphism.

Electrochemical Measurement of the Free Energy of Adsorption ofn-Alkanethiolates at Ag(111)

1998 ◽  
Vol 120 (5) ◽  
pp. 1062-1069 ◽  
Author(s):  
David W. Hatchett ◽  
Rory H. Uibel ◽  
Keith J. Stevenson ◽  
Joel M. Harris ◽  
Henry S. White
Keyword(s):  
Free Energy ◽  
Electrochemical Measurement ◽  
Free Energy Of Adsorption

The effect of fungal colonization on the morphine production of poppy (Papaver somniferum L.) capsules

1982 ◽  
Vol 98 (3) ◽  
pp. 679-687 ◽  
Author(s):  
J. C. Laughlin ◽  
D. Munro
Keyword(s):  
Field Experiment ◽  
Papaver Somniferum ◽  
Fungal Colonization ◽  
Capsule Wall ◽  
Surface Cover ◽  
Morphine Concentration ◽  
Commercial Harvest ◽  
Low Concentrations ◽  
The Individual

SUMMARYAbnormally low concentrations of morphine in capsules of poppy (Papaver somniferum L.) in the 1970–1 season were associated with heavy fungal colonization. The effect of fungal colonization on the morphine production of capsules was later studied in a series of field, glasshouse and in vitroexperiments.In a field experiment morphine concentration of severely colonized (> 30% surface cover) intact capsules was 20% less (P <0·01) than slightly colonized (< 10% surface cover) capsules. Colonization of these field-grown capsules was generally localized in the top half and the morphine concentration of the top half was about 20% less than the bottom half for all colonization categories. In contrast, glasshouse-grown capsules were free of fungal colonization and the top and bottom halves had similar morphine concentrations.In a field experiment studying the effect of fungicides, 2 kg benomyl (50% a.i.) + 2 kg mancozeb (80% a.i.)/ha were applied as a spray at 10-day intervals from flowering till 1 month after commercial harvest and plants were harvested at weekly intervals from 10 days after full bloom. The mean dry-matter yield of sprayed capsules was 11% greater (P <0·01) than non-sprayed with a similar trend for morphine concentration and morphine yield. In addition, the sprayed treatment significantly reduced the area covered by sporulating lesions on the surface of the capsule after dry maturity. This superficial fungal cover had a NNE orientation in both sprayed and non-sprayed capsules.In an in vitroexperiment using capsules from the field fungicide study, fungi were isolated from the interior of green capsule wall tissue as early as 17 days after flowering. Colonization increased with successive harvests and culturing of fungi from the interior of capsule wall tissue showed the presence of fungi in both sprayed and non-sprayed capsules with no difference in the degree of colonization.Two of the major fungi isolated from the field experiment were identified as Dendryphion penidllatum (Corda) Fr. and Alternaria alternata (Fr.) Keissler and the individual effect of these was assessed in an in vitro experiment using ground capsule material. D. penidllatuvi and A. alternata reduced the morphine concentration of ground capsules in 24 days to 7 and 11% respectively of non-inoculated controls.

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