Real Dimensions of the Drug Ions from Conductometric Studies of Drugs (Present as Salts) in Acetonitrile

2004 ◽  
Vol 218 (5) ◽  
pp. 551-562 ◽  
Author(s):  
R. Mandal ◽  
J. Gangopadhyay ◽  
S. C. Lahiri
Keyword(s):  
Aqueous Solutions ◽  
Association Constants ◽  
Pharmacological Agents ◽  
The Real ◽  
Large Size ◽  
Low Concentrations ◽  
Lipid Layers ◽  
Ionic Forms

AbstractThe Λ0 and association constants of salts of some widely used drugs (pharmacological agents) in acetonitrile have been determined. The division of Λ0 into single ion values λ0+ and λ0− has been made using λ0Na⁺ and λ0Cl⁻ values from the literature. The λ0+ and λ0− values have been found to be considerable in acetonitrile. The results suggest that many of the drugs can be present both as dissociated ions as well as associated molecules which are capable of absorption, dissociation and conduction (of ionic forms) in the lipid layers at very low concentrations. The phenomenon of unsolvation has been utilized to calculate the real dimensions of the drug ions (cations or anions) which are difficult to calculate from bond distances due to their large size and coiled configuration in aqueous solutions.

Flow Behaviors of High Acyl Gellan Aqueous Solutions as Affected by Temperature, and Calcium and Gellan Concentrations

2008 ◽  
Vol 4 (5) ◽  
Author(s):  
Yiqun Huang ◽  
Pawan Singh Takhar ◽  
Juming Tang ◽  
Barry G Swanson
Keyword(s):  
Shear Rate ◽  
Aqueous Solutions ◽  
Apparent Viscosity ◽  
Flow Resistance ◽  
Effect Of Temperature ◽  
Temperature Changes ◽  
Influence Of Temperature ◽  
Rheological Behaviors ◽  
Low Concentrations ◽  
Influence Of Temperature On

Rheological behaviors of high acyl (HA) gellan are not well understood partially because of its relatively late commercialization compared to low acyl gellan. The objective of this study was to investigate the effect of temperature (5-30 °C), calcium (0, 1 and 10 mM) and gellan concentrations (0.0044-0.1000% w/v) on the flow behaviors of high acyl gellan aqueous solutions using rheological tests. Gellan solutions with 0 or 1 mM added Ca++ exhibited shear thinning behavior at gellan concentrations above 0.0125%. The influence of temperature on apparent viscosity (shear rate, 100 s-1) of gellan solutions can be described with an Arrhenius relationship. The apparent viscosity of gellan solution at low concentrations was more sensitive to temperature changes. The addition of Ca++ led to a decrease in flow resistance for a dilute gellan solution (<0.0125%), but an increased resistance for a relatively concentrated gellan solution (>0.0125%).

scholarly journals Growth and Characterization of Epsomite Single Crystals Doped with KCl from low Temperature Aqueous Solutions

1970 ◽  
Vol 33 (1) ◽  
pp. 47-54 ◽  
Author(s):  
S Ferdous ◽  
J Podder
Keyword(s):  
Aqueous Solutions ◽  
Single Crystals ◽  
Optical Quality ◽  
Dielectric Studies ◽  
Slow Cooling ◽  
Large Size ◽  
Isothermal Evaporation ◽  
Academy Of Sciences

Highly transparent and well faceted large size epsomite single crystals have been grown in pure form and doped with KCl from aqueous solutions by slow cooling and isothermal evaporation method. The optical quality of the epsomite improves on doping by KCl. Mass growth rates were found to increase with doping of lower concentrations of KCl and then decreases with the higher concentration of KCl. KCl doped epsomite crystal reveals that structures are slightly distorted due to adsorption of Cl- ion into the crystal lattice. DC conductivity along the growth axis for all of the grown crystals increases with temperature in the range of 25 to 70ºC and also increases with the KCl concentration. Dielectric constant is found to be almost independent of frequency up to range of 106Hz. The dielectric studies show the suitability of these grown crystals for optoelectronic applications. DOI: 10.3329/jbas.v33i1.2949 Journal of Bangladesh Academy of Sciences, Vol. 33, No. 1, 47-54, 2009

scholarly journals Role of cAMP in the Short-Term Modulation of a Neuromuscular System in Aplysia

2000 ◽  
Vol 83 (3) ◽  
pp. 1567-1579 ◽  
Author(s):  
Lyle E. Fox ◽  
Philip E. Lloyd
Keyword(s):  
Motor Neurons ◽  
Second Messenger ◽  
Neuromuscular System ◽  
Short Term ◽  
Pharmacological Agents ◽  
Camp Pathway ◽  
Low Concentrations ◽  
Excitatory Junction Potentials ◽  
Second Messenger Pathways ◽  
Short Term Effects

Neuromuscular synapses in buccal muscle I3a of Aplysia are modulated by the small cardioactive peptide (SCP), a peptide cotransmitter that is intrinsic to the motor neurons, and by serotonin (5-HT) released from modulatory neurons that are extrinsic to the motor circuit. Although the modulation of excitatory junction potentials (EJPs) and contractions by 5-HT and SCP has been studied extensively in this muscle, little is known about the mechanisms that underlie the modulation. 5-HT and SCP, at 1 μM, were found to potently increase the level of cAMP in I3a. Therefore we investigated whether the activation of the cAMP pathway was sufficient to modulate EJPs and contractions. The direct activation of adenylyl cyclase with forskolin increased the level of cAMP, facilitated EJPs, and potentiated contractions. Indeed, the short-term effects of forskolin were very similar to all aspects of the short-term effects of 5-HT and SCP. Membrane-permeable cAMP analogues also mimicked the effects of 5-HT and SCP on EJPs and contractions. However, it seems likely that some effects of 5-HT are also mediated through other second-messenger pathways because low concentrations of 5-HT modulate EJPs and contractions but do not significantly increase cAMP levels in I3a. It is possible that lower concentrations of 5-HT function through receptors linked to protein kinase C (PKC) because phorbol, an activator of PKC, modulated EJPs and contractions without increasing the levels of cAMP. In conclusion, we provide evidence that pharmacological agents that activate the cAMP pathway mimicked most of the effects of 5-HT or SCP and that more than one second-messenger system appears to be involved in the modulation of the I3a neuromuscular system.

Absorption of Herbicides by Soybean Seeds and Their Influence on Emergence and Seedling Growth

Weed Science ◽  
1972 ◽  
Vol 20 (5) ◽  
pp. 506-510 ◽  
Author(s):  
R. E. Phillips ◽  
D. B. Egli ◽  
L. Thompson
Keyword(s):  
Acetic Acid ◽  
Aqueous Solutions ◽  
Potassium Salt ◽  
Soybean Seeds ◽  
Experimental Procedure ◽  
Low Concentrations ◽  
High Concentrations ◽  
Shoot Weight ◽  
Total Oil ◽  
Dichlorophenoxy Acetic Acid

The total quantity and concentration of six herbicides, isopropylm-chlorocarbanilate (chlorpropham), 2-chloro-4-(ethylamino)-6-(isopropylamino-s-triazine (atrazine), 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron), 2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide (alachlor), 3-amino-2,5-dichlorobenzoic acid (chloramben), and (2,4-dichlorophenoxy)acetic acid (2,4-D), in unaerated, aqueous solutions absorbed by seeds of 11 soybean(Glycine max(L.) Merr.) strains were measured. Mechanism of movement of the herbicides from the aqueous solutions to the seeds in the experimental procedure employed was diffusion. Total quantity and concentration of herbicide found in the seeds differed significantly for both herbicides and soybean strains. Total quantity of herbicide absorbed was determined by total oil and percent oil of the seeds. The capacity of the seeds to absorb a given herbicide was more closely related to percent oil of the seeds than to total oil of the seeds. The emergence and seedling shoot weight of ‘Cutler’ soybeans were not affected appreciably by concentrations of linuron, atrazine, and chloramben (potassium salt) but were reduced by high concentrations of chlorpropham and alachlor and relatively low concentrations of 2,4-D (potassium salt) in the seeds.

Highly efficient absorption of nitric oxide by RuIII(edta) aqueous solutions at low concentrations

2019 ◽  
Vol 41 (21) ◽  
pp. 2705-2715 ◽  
Author(s):  
Wenjin Xu ◽  
Chao Xu ◽  
Jun Deng ◽  
Guomeng Zhang ◽  
Guangxu Zhang
Keyword(s):  
Nitric Oxide ◽  
Aqueous Solutions ◽  
Highly Efficient ◽  
Low Concentrations

The Absorption of Low Concentrations of Sulphur Dioxide into Aqueous Solutions

Tellus ◽  
1974 ◽  
Vol 26 (1-2) ◽  
pp. 272-276 ◽  
Author(s):  
P. BRIMBLECOMBE ◽  
D. J. SPEDDING
Keyword(s):  
Aqueous Solutions ◽  
Sulphur Dioxide ◽  
Low Concentrations

scholarly journals Desalting protein ions in native mass spectrometry using supercharging reagents

The Analyst ◽  
2014 ◽  
Vol 139 (19) ◽  
pp. 4810-4819 ◽  
Author(s):  
Catherine A. Cassou ◽  
Evan R. Williams
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solutions ◽  
Electrospray Ionization ◽  
Native Mass Spectrometry ◽  
Large Proteins ◽  
Measuring Accuracy ◽  
Low Concentrations ◽  
Protein Ions

Low concentrations of supercharging reagents m-NBA (1.5%) and sulfolane (2.5%) effectively desalt protein ions produced by electrospray ionization from aqueous solutions, improving mass measuring accuracy for large proteins.

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