Search results for "CONST"

Speciation of trialkyltin(IV) cations in natural fluids

2004

The hydrolysis of (CH(3))(3)Sn(+), (C(2)H(5))(3)Sn(+) and (C(3)H(7))(3)Sn(+) has been studied in a Synthetic Seawater (SSW) ionic medium simulating the major composition of natural seawater, at different salinities (5 less than or equal to S less than or equal to 45), and at t = 25 degreesC. Interactions with anionic components of SSW, considered as single sea salt, are determined by means of a complex formation model. By potentiometric measurements (ISE-H(+) and ISE-F(-) electrodes), the model has been extended to also consider interactions of organotins with carbonate and fluoride ions, which are other important components of seawater. Literature and new values of hydrolysis constants in …

Bovine lactoferrin pepsin hydrolysate exerts inhibitory effect on angiotensin I-converting enzyme-dependent vasoconstriction

2007

Abstract The inhibitory effect of a pepsin hydrolysate of bovine lactoferrin (LFH) on angiotensin I-converting enzyme (ACE) has been examined using in vitro and ex vivo functional assays. In vitro assays showed a LFH inhibitory effect on ACE activity with an IC 50 value of 0.95±0.06 mg mL −1 . Ex vivo functional assays using rabbit carotid artery segments showed a LFH inhibitory effect on ACE-dependent angiotensin I-induced contraction, but not on angiotensin II-induced contraction, suggesting that the effect of LFH is not due to antagonism of receptors for angiotensin II. LFH was shown to possess ACE inhibitory effect with potential to modulate hypertension, although the possible inhibitor…

From Food Map to FODMAP in Irritable Bowel Sindrome.

2016

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal diseases in the general population, with a prevalence ranging from 12 % to 30 %, mainly affecting younger patients (i.e., <50 years of age) and women [1]. As in other chronic functional gastrointestinal disorders, abdominal discomfort or pain, abnormal bowel habits, and often bloating and abdominal distension are the main clinical features. Their diagnosis is based on symptom patterns (i.e., the Rome III criteria), which also allow categorization in diarrhea-predominant (D-IBS), constipation-predominant (C-IBS), mixed diarrhea and constipation (M-IBS), and unclassified (U-IBS) IBS [2]. Symptom severity ranges from tol…

Intrinsic Viscosities of Polyelectrolytes: Determination and Modeling of the Effects of Extra Salt

2011

Based on early measurements of J. J. Hermans and co-workers (D. T. F. Pals, J. J. Hermans, Recl. Trav. Chim. Pays-Bas 1952, 71, 513-520; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1950, 5, 733-734; D. T. F. Pals, J. J. Hermans, J. Polym. Sci. 1948, 3, 897-898), the present contribution demonstrates how primary data should be evaluated in order to obtain reliable intrinsic viscosities. This procedure yields detailed information on the changes of the intrinsic viscosities and of the corresponding viscometric interaction parameters caused by an increasing salinity of water. Both quantities decline from a maximum value in the pure solvent to a minimum value, which is approached in the limit o…

Kinetische untersuchungen zur reaktionsfähighkeit von chlormethylgruppen in methylendiphenolen

1984

The chloromethyl derivatives of 16 differently substituted methylenediphenols were synthesized for the first time. To compare their reactivity, the solvolysis in methanol and the animolysis with an excess of p-nitroaniline in dimethyl sulfoxide were studied kinetically at 25°C. The rate constants for the methanolysis do not differ very much, beside of the fact that para-chloromethyl derivatives react about 100 times faster than ortho-chloromethyl derivatives. However, for the aminolysis a large acceleration up to 103 was found for compounds having both hydroxyl groups in ortho-position to the methylene bridge. Obviously, the cleavage of the OH bond, which occurs in the rate determining step…

Influence of hydrogen peroxide on the kinetics of phenol photodegradation in aqueous titanium dioxide dispersion

1990

Abstract The influence of hydrogen peroxide on the phenol photodegradation rate under near UV radiation was investigated in homogeneous and heterogeneous systems: the heterogeneous systems were aqueous dispersions of titanium dioxide (anatase). The hydrogen peroxide photodecomposition reaction was also investigated for all the systems used. The highest rate of phenol photodegradation was observed in the heterogeneous system for the contemporary presence of hydrogen peroxide and oxygen. The rate equations for phenol photodegradation and hydrogen peroxide photodecomposition for both systems were obtained. A mechanistic model able to explain the main experimental results is also proposed.

1974

1978

A newly designed automatically controlled stirred reactor suitable for kinetic measurements of reactions with half lives ≥2s has been applied to follow the anionic polymerization of methyl methacrylate in THF with Na+ as a counter ion in the presence of an excess of NaB(C6H5)4. As initiators were used: benzylsodium reacted with α-methylstyrene (I), fluorenylsodium (II), and 9-methylfluorenylsodium (III). With I the initiation is fast as compared with the polymerization reaction which is first order in monomer concentration. Within the range of −50°C to −100°C an almost unperturbed “living” polymerization is observed. The Arrhenius plot of the rate constants results in a straight line with a…

Binding of acrylic and sulphonic polyanions by open-chain polyammonium cations

2000

Abstract The interactions between some acrylic and sulphonic polyanions and some protonated amines (diamines NH 2 -(CH 2 ) x -NH 2 , x =2,…,10; linear tri-, tetra-, penta- and hexa-amines) were studied potentiometrically in aqueous solution, at 25°C. For both types of polyanions AL 2 H i (L − , monomer of polyanion, A, amine) species are formed, with i =1,…, n ( n =number of amino groups in the amine). The stability of these species is strictly dependent on the polyammonium cation charge, and fairly independent of the type of amine (in diamine species maximum stability is observed for x =4, 5). Acrylic and sulphonic polyanion complexes are considerably stronger than analogous species formed…

A bis-exTTF macrocyclic receptor that associates C60 with micromolar affinity

2010

An exTTF-based macrocyclic receptor that associates C(60) with a binding constant10(6) M(-1) in chlorobenzene at room temperature is described. This represents an improvement of 3 orders of magnitude with respect to the previous examples of exTTF-based receptors and one of the highest binding constants toward C(60) reported to date.