Water-soluble cellulose derivatives with tertiary amino groups up to substitution degree 0.8 (4.2% of coupled nitrogen) were
prepared in a controlled manner by the interaction of cellulose acetate with N,N-diethylepoxypropylamine. It was shown that two reactions take place simultaneously, i.e., hydrolysis of acetyl groups and
aminoalkylation of free hydroxyl groups of cellulose. The amino groups coupled to the cellulose are of middle basicity with
pKα ~9.5. Solubility of the products was found to be determined by the chemical composition of the cellulose derivative. 相似文献
We present some necessary and some sufficient conditions for a family of multifunctions generated by two families of real functions to be a collapsing, an expanding family or an iteration semigroup. Some properties of set-valued iteration groups generated by commuting homeomorphisms not embeddable in an iteration group are given. 相似文献
Four compounds showing moderate antituberculostatic activity have been studied to test the hypothesis that the planarity of the 2‐[amino(pyrazin‐2‐yl)methylidene]dithiocarbazate fragment is crucial for activity. N′‐Anilinopyrazine‐2‐carboximidamide, C11H11N5, D1, and diethyl 2,2′‐[({[amino(pyrazin‐2‐yl)methylidene]hydrazinylidene}methylidene)bis(sulfanediyl)]diacetate, C14H19N5O4S2, B1, maintain planarity due to conjugation and attractive intramolecular hydrogen‐bond contacts, while methyl 3‐[amino(pyrazin‐2‐yl)methylidene]‐2‐methyldithiocarbazate, C8H11N5S2, C1, and benzyl 3‐[amino(pyrazin‐2‐yl)methylidene]‐2‐methyldithiocarbazate, C14H15N5S2, C2, are not planar, due to methylation at one of the N atoms of the central N—N bond. The resulting twists of the two molecular halves (parts) of C1 and C2 are indicated by torsion angles of 116.5 (2) and −135.9 (2)°, respectively, compared with values of about 180° in the crystal structures of nonsubstituted compounds. As the methylated derivatives show similar activity against Mycobacterium tuberculosis to that of the nonsubstituted derivatives, maintaining planarity does not seem to be a prerequisite for activity. 相似文献
An isocratic high performance liquid chromatographic method, with the application of C18 and C30 reverse-phase column and fluorescence detection, is described for the analysis of plastochromanol, tocotrienols and tocopherols in plant seed oils. The solvent systems have been optimized to obtain high resolution for all tocochromanols and relatively short analysis time. The use of reverse-phase columns for plastochromanol analysis, previously not reported, enables very sensitive and selective detection of plastochromanol which under the described separation conditions did not interfere with tocochromanols or any other compounds. The sample extraction method is fast, simple and highly efficient. The obtained results show that plastochromanol was present in most of the investigated seed oils. Its level was the highest in flax (17–30 mg/100 g oil), rape (8.5–9), camelina (4.3), peanut (1.95), corn (1.69) and grape (1.31) seed oils. Its level in the other investigated oils was below 1 mg/100 g oil, and only in sesame and coconut oils it was not detected. Tocotrienols were found in most of the oils but their content was usually very low (<<1 mg/100 g oil) with the exception of grape, milk thistle and corn oils where it reached >1 mg/100 g oil. Tocopherol content and isomer composition was within the earlier reported literature values for the investigated oils.
In the paper anomalous diffusion appearing in a porous medium composed of two porous components of considerably different diffusion characteristics is examined. The differences in diffusivities are supposed to result either from two medium types being present or from variations in pore size (double porosity media). The long-tail effect is predicted using the homogenization approach based on the application of multiple scale asymptotic developments. It is shown that, if the ratio of effective diffusion coefficients of two porous media is of the order of magnitude smaller or equal O(
2), where is a homogenization parameter, then the macroscopic behaviour of the composite may be affected by the presence of tail-effect. The results of the theoretical analysis were applied to a problem of diffusion in a bilaminate composite. Analytical calculations were performed to show the presence of the long-tail effect in two particular cases.Notations
ci
the concentration of chemical species in water within the medium i
-
Di
the effective diffusion coefficient for the medium i
-
Dijeff
the macroscopic (or effective) diffusion tensor in the composite
-
ERV
the elementary representative volume
-
h
the thickness of the period
-
l
a chracteristic length of the ERV or the periodic cell
-
L
a characteristic macroscopic length
-
n
the volumetric fraction of the material 2
- 1–n
the volumetric fraction of the material 1
-
N
the unit vector normal to
-
t
the time variable
-
x
the macroscopic (or slow) space variable
-
y
the microscopic (or fast) space variable
-
c1c,C2c,D1c,D2c
the characteristic quantities
-
T,T1L,T2L,T1l,T2l
the characteristic times
-
c1*
,c2*
,D1*
,D2*
,t*
the non-dimensional variables
-
the homogenization parameter
- 1
the domain occupied by the material 1
- 2
the domain occupied by the material 2
-
the interface between the domains 1 and 2
-
the total volume of the periodic cell
-
/xi
the gradient operator
-
the gradient operator 相似文献
Ionic liquid based microemulsions were characterized by absorption solvatochromic shifts, (1)H NMR and kinetic measurements in order to investigate the properties of the ionic liquid within the restricted geometry provided by microemulsions and the interactions of the ionic liquid with the interface. Experimental results show a significant difference between the interfaces of normal water and the new ionic liquid microemulsions. Absorption solvatochromic shift experiments and kinetic studies on the aminolysis of 4-nitrophenyl laurate by n-decylamine show that the polarity at the interface of the ionic liquid in oil microemulsions (IL/O) is higher than at the interface of water in oil microemulsions (W/O) despite the fact that the polarity of [bmim][BF(4)(-)] is lower than the polarity of water. (1)H NMR experiments showed that an increase in the ionic liquid content of the microemulsion led to an increase in the interaction between [bmim][BF(4)(-)] and TX-100. The reason for the higher polarity of the microemulsions with the ionic liquid can be explained in terms of the incorporation of higher levels of the ionic liquid at the interface of the microemulsions, as compared to water in the traditional systems. 相似文献
The synthesis and evaluation as 5‐HT1A and 5‐HT7 serotonin receptor ligands of the two sets of O‐substituted hydroxybenzamides, structurally related to 2‐{3‐[4‐(2‐methoxyphenyl)piperazin‐1‐yl]propoxy}benzamide ( 1 ), (Ki 5‐HT1A = 21 nM, 5‐HT7 = 234 nM) are reported. To affect the affinity for 5‐HT1A and 5‐HT7 receptors, an amide moiety ( 2 , 3 , 4 , 5 , 6 ) and a hydrocarbon chain length ( 7 , 8 , 9 , 10 ) were modified. The serotonergic activity of compounds 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 was generally higher in the case of 5‐HT1A receptors compared with 5‐HT7 ones; the most active 5‐HT1A ligands being meta‐isomer 2 (Ki = 7 nM) and both analogs of 1 with the longest spacer, i.e., penta‐ and hexa‐methylene derivatives 9 and 10 (Ki = 4 and 3 nM, respectively). The observed biological properties of compounds 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 were elucidated using molecular modeling procedures. J. Heterocyclic Chem., (2010). 相似文献
Titania layers obtained by a sol-gel technique doped with redox mediator, Meldola’s Blue, were employed for construction of
a new NADH senor. Optimization of preparation process as well as experimental conditions affecting the response of the sensor
were examined. Under optimal conditions NADH could be determined in the wide linear range from 90 to 2300 μM with detection
limit 12 μM and a high sensitivity 12.5 nA μM−1. The usefulness of developed sensor was preliminarily checked in determination of NADH forming during enzymatic oxidation
of ethanol catalyzed by alcohol dehydrogenase (ADH).
相似文献
JPC – Journal of Planar Chromatography – Modern TLC - The lipophilicity of twenty-one N-benzyl-2-azaspiro[4.4]nonaneand [4.5]decane-1,3-dione derivatives, fifteen of which (1–15)... 相似文献