Drying dissipative structure of sodium dextran sulfate in aqueous solution

Drying dissipative patterns were observed at room temperature on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous solution of sodium salts of dextran sulfate (NaDSS) having molecular weights of 5000, 36,000 ~ 50,000 and 500,000. These biopolyelectrolytes are one of the typical polysaccharides. The influences of the hexose units upon the macroscopic and microscopic drying patterns are studied. Formation of some ordered structure is observed for NaDSS in high polymer concentrations especially on a cover glass. Broad ring size decreased as polymer concentration decreased and/or its molecular weight increased. Drying patterns are clarified to be formed by the successive and cooperative pattern formation of convection, sedimentation, and solidification.     

Drying dissipative structures of arrowroot starch

Macroscopic and microscopic drying patterns of arrowroot starch (ARS) in diluted aqueous solution and gel state were investigated on a cover glass in order to know the molecular information of ARS and their interaction with the substrate. Thickness profiles of the dried film showed coexistence of the rather sharp broad ring and the very broad accumulation at the outside edge and the inner region, respectively. The sharpness parameters, S values from the outside peaks decreased sharply from 100 to 3 as initial concentration increased from 0.04 to 3 wt%. Furthermore, very low S values between one and two originating from the round hills were also observed at low concentrations, 0.04 to 0.2 wt%. The results support that stable gelation of ARS molecules does not take place at the ARS concentrations lower than ca. 2 wt% at 20 °C. It is highly plausible that ARS molecules existing near the substrate surface are adsorbed strongly on the substrate. Gelation of ARS molecules took place rapidly above 2 wt%. The S values increased sharply from 3 to 15 with increasing temperature from 5 to 20 °C, and kept constant around 15 at the higher temperatures up to 50 °C. Convectional diffusion of ARS decreased in the order of ARS > gelatin > poly (N-butyl acrylate), when comparison was made at the same weight percent at the lower concentrations than ca. 2 wt%. Above the concentration, stable gel structures of ARS were formed.     

Drying dissipative structures of the aqueous suspensions of palygorskite and tungstic acid particles

Macroscopic and microscopic dissipative structural patterns during dryness of the aqueous suspensions of palygorskite (PGK, needle-like shaped) and tungstic acid (TA, plate-like) have been studied on a cover glass. The coexistence of the broad ring of the hill accumulated with the particles and the round hills is observed around the outside edges of the dried film and in the center, respectively. These patterns differ from those of the suspensions of spherical particles. Furthermore, the spoke-like patterns, which have been observed for the suspensions of the spherical particles so often, are not observed at all for PGK and TA suspensions. These characteristic macroscopic patterns of PGK and TA are quite similar to those of the fractionated and monodispersed bentonites (plate-like) reported previously Yamaguchi et al. (Colloid Polymer Sci 283:1123, 2005). Wrinkled and/or branch-like fractal patterns are observed in the microscopic scale, which are quite similar to those of bentonites. “Shape information” of the colloidal particles is clarified to be “transferred” to the drying patterns via the convectional and sedimentary patterns during the course of dryness.     

Acidimetric determination of sodium salts of methyl sulfamic acid

A procedure for the determination of sodium salts of methyl sulfamic acid as tertiary amines by acidimétrie titration in glacial acetic acid was developed. The total error of the procedure did not exceed 1%. The procedure is simple and can be carried out under ordinary laboratory conditions.     

酸量滴定法测定N-取代氨基磺酸钠

ＨＥＴＳ和ＨＦＴＳ作为醇胺类化合物、硝胺类化合物、叠氮类化合物[2 ] 等中间体 ,在医药、染料工业上具有重要的意义。在研究它们的制备工艺、除杂提纯过程中 ,常需对它们进行定量测定。近二十多年来 ,对于Ｎ 取代氨基磺酸盐类化合物的定量测定 ,除偶见用质谱法、核磁共振谱法、高效液相色谱法[3] 进行测定外 ,还没有发现相关的化学测定方法的报导。而质谱法、核磁共振谱法、高效液相色谱法 ,都有仪器昂贵、操作要求高、相对误差较大 ( 2 %～ 4% ) [4] 等缺点。本文深入研究了用酸量滴定法定量测定ＨＥＴＳ和ＨＦＴＳ的方法。1　实验部分1…     

Drying dissipative patterns of biological polyelectrolyte solutions

Drying dissipative structural patterns of aqueous solutions of biological polyelectrolytes, sodium poly (α, L-glutamate; NaPGA) and poly (-L-lysine hydrobromide; PLL.HBr), were studied on a cover glass. Below the critical polymer concentration, m* (ca. 0.003 and ca. 0.01 monoM for NaPGA and PLL.HBr, respectively), the dried patterns shrank only around the center of the initial solution area wetted on a cover glass. Above the m* values, on the other hand, the drying pattern extended throughout the initial solution area. The m* values agreed excellently with the critical polymer concentrations, where the surface tensions started to decrease sharply as the polymer concentrations increased. The broad rings were always observed in the drying patterns of any solutions examined. The spoke-like cracks appeared at the polymer concentrations above the m* values and only in the area of the broad rings. Microscopic structures such as cross-like, rod-like, and block-like patterns formed irrespective of polymer concentrations. Especially, the city-road-like microscopic pattern was observed for PLL.HBr solutions, which strongly supports the formation of crystal structures of PLL.HBr that remain in the whole processes of dryness. These patterns were correlated deeply with the crystal-like orientation of the biological polyelectrolytes at the air–solution interfaces.     

Phase behaviour of lithium and sodium salts of phenylstearic acid

Phenylstearic acid, prepared from oleic acid and benzene, using the Friedel-Crafts reaction, has been confirmed to be a reproducible mixture of twelve positional isomers. Lithium and sodium salts of this acid are semi-crystalline solids which behave in many ways like pure single substances. The thermotropic polymorphism of these soaps has been studied using DSC and polarizing microscopy (as well as X-ray diffraction and ⁷Li NMR spectroscopy for the former soap). Both soaps exhibit characteristic stepwise melting behaviour and form stable reversed hexagonal mesophases at elevated temperatures, in contrast to the lamellar phases exhibited by the unsubstituted soaps.     

Investigation of the thermal behaviour of fatty acid sodium salts

The thermal and thermo-electrical behaviour and properties, as well as the type structure and appearance of the liquid crystalline phases of the sodium salts of saturated, non-branching fatty acids were investigated. The measurements were carried out with a derivatograph, a DTA apparatus and a simultaneous DTA-electrical conductivity meter.Relationships were found between the different thermal and electrical properties and the chain-length of the compounds.

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Zusammenfassung Das thermische und thermo-elektrische Verhalten bzw. die Eigenschaften, sowie Typ, Struktur und Erscheinung der flüssigen kristallinen Phasen der Natriumsalze gesÄttigter unverzweigter FettsÄuren wurden untersucht. Die Messungen wurden mit Hilfe eines Derivatographen, einer DTA-Apparatur und einer simultanen DTA-LeitfÄhigkeitsme\-Anordnung durchgeführt.ZusammenhÄnge wurden zwischen den verschiedenen thermischen und elektrischen Eigenschaften und der KettenlÄnge der Verbindungen gefunden.

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Résumé On a étudié le comportement et les propriétés thermiques et thermoélectriques, ainsi que le type, la structure et l'aspect des phases cristallines liquides de sels de sodium d'acides gras saturés, non ramifiés.Des corrélations entre les diverses propriétés thermiques et électriques et la longueur de la chaine des composés étudiés ont été trouvées.

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Reaction of sodium salts of dialkylphosphorous acids with carboxylic acid nitriles

Conclusions The reaction of the Na salts of dialkylphosphorous acids with nitriles leads to the dialkyl esters of N-(1-dialkylphosphonylalkyl) amidophosphoric acids, whose formation proceeds via the aminophosphonate-amidophosphate rearrangement of the sodium derivatives of bis(dialkylphosphonyl)alkylamines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 499–500, February, 1978.     

Drying dissipative structures of nonionic surfactants in aqueous solution

Macroscopic and microscopic dissipative structural patterns form in the course of drying a series of aqueous solutions of polyoxyethylenealkyl ethers. The shift from the single round hill with accumulated surfactant molecules to the broad ring patterns of the hill in a macroscopic scale occurs as the HLB (hydrophile-liophile balance) of the surfactant molecules increases. The patterns correlate intimately with the HLB values of the surfactants. Microscopic patterns of small blocks, starlike patterns, and branched strings are formed. The size and shape of the surfactant molecules themselves influence the drying patterns in part. The pattern area and the time to dryness have been discussed as a function of surfactant concentration and HLB of the surfactants. The convection flow of water accompanying the surfactant molecules, the change in the contact angles at the drying frontier between solution and substrate in the course of dryness, and interactions among the surfactants and substrate are important for the macroscopic pattern formation. Microscopic patterns are determined in part by the shape and size of the molecules, translational Brownian movement of the surfactant molecules, and the electrostatic and hydrophobic interactions between surfactants and/or between the surfactant and substrate in the course of solidification.     

Drying dissipative structures of poly(N-isopropylacrylamide) homopolymer

Drying dissipative patterns of the linear-type thermosensitive homopolymer poly(N-isopropylacrylamide) lpNIPAm in deionized aqueous solution and suspension were observed on a cover glass, a watch glass, and a Petri glass dish at 22 and 50 °C, respectively. The size and ζ potential of the globule aggregates of lpNIPAm at 47.5 °C were 140 nm in diameter and ?22 mV from the electrophoretic light-scattering measurements. A single broad ring formed in the inner region (on a cover glass and a watch glass) and near the outside edge (in a glass dish) in the macroscopic drying pattern at 22 °C. On the other hand, two to three kinds of broad rings were observed at the outside edge and inner region at 50 °C. Microscopic drying structures of ordered rings, flickering ordered spoke-lines, and net structures of the agglomerated particles were observed. Formation of the similar-sized agglomerates and their ordered arrays were observed during the course of dryness. These results of lpNIPAm at 50 °C are quite similar to the agglomeration and the ordering of the thermosensitive gel spheres of poly(N-isopropylacrylamide), pNIPAm. The surface structures of the similar-sized agglomerates of lpNIPAm will be similar to those of pNIPAm gel spheres, since the chemical components of the homopolymers and the gels are almost the same. The role of the electrical double layers around the agglomerates and their interaction with the substrates are important for the ordering. Dendritic large aggregates (from 50 to 600 μm in size) formed in the presence of sodium chloride.     

Inclusional association as studied by the drying dissipative structure. Part 2. Drying pattern of n-alkyltrimethylammonium bromide

Macro- and microscopic drying patterns were observed on a cover glass and a watch glass during the course of dryness of aqueous solutions of a series of n-alkyltrimethylammonium bromides (alkyl: n-decyl, n-dodecyl, n-tetradecyl, and n-hexadecyl). The broad rings formed at the outside edges of the macroscopic patterns. Size of the initial liquid on the substrates, d _i, that of the final broad ring, d _f, and the ratio, d _f/d _i, changed as the surfactant concentration changed, and there appeared a bending point in each curve, which was found to correspond to the critical micelle concentration (cmc) of the surfactant. The cmc values evaluated from the d _i, d _f, and d _f/d _i values agreed well with the reference values reported previously. Cooperative drying processes of the convection, sedimentation, and solidification were supported. Microscopic drying patterns such as rod-like, dendritic, and granule-like patterns were observed, and they changed as a function of the carbon number of the alkyl groups, surfactant concentration, and the distance from the center of the pattern.     

Thermal behavior of glutamic acid and its sodium,lithium and ammonium salts

Glutamic acid (H2_glu) and its lithium, sodium and ammonium monosalts were submitted to thermal analysis using thermogravimetry (TG) and differential thermal analysis (DTA). The main goal of these studies was to compare the relative thermal stability and to evaluate the effect of the counter ion in the thermal decomposition pathways. Salts were obtained by direct neutralization of the purified acid with LiOH, NaOH or NH₄OH and were characterized by elemental analysis (C, H and N) and IR spectroscopy. Decomposition occurred after conversion to the pyroglutamic acid or the respective pyroglutamates and ammonium salt loosing NH₃ being converted to H₂glu before decomposition.     

Fluctuation structure of solutions of polyamic acid salts in mixed solvents

Structural organization is studied for dilute solutions of the comblike N,N-dimethylhexadecylammonium salt of polyamic acid based on 3,3′,4,4′-diphenyltetracarboxylic dianhydride and o-tolidine by the method of polarized light scattering in mixed dimethylacetamide-benzene and N-methylpyrrolidone-benzene solvents. The statistical structural parameters of the solutions are calculated according to the Debye-Stein theory. The dimensions of ordered scattering fluctuation-type formations are shown to be much greater than the molecular dimensions and to depend on the chemical nature and composition of the mixed solvent. At polymer concentrations below 0.2 g/dl, the corresponding concentration dependences of the statistical structural parameters are characterized by extreme patterns for all systems under study.     

Molecular structure and morphology of biomineral composites based on nanohydroxyapatite and hyaluronic acid

New biocomposites based on hydroxyapatite and hyaluronic acid are obtained, and their structural and morphological characteristics are studied. With the use of a set of physicochemical methods, the effect of hyaluronic acid as an active medium in the synthesis of hydroxyapatite used to produce synthetic biocomposites close in structure to native hydroxyapatite is investigated.     

Dawson结构钼砷杂多酸(盐)的合成与性质研究

采用酸化-回流-乙醚萃取法合成了二十种Dawson结构钼砷杂多酸及其盐, 元素分析确定了它们的组成, 其通式为MwAs2Mo18Oe2.nH2O, 酸碱及电导滴定确定了碱度, 系统地研究了它们的红外光谱, 紫外光谱, 极谱, 循环伏安, 热重-差热分析等性质, 给出了杂多阴离子As2Mo18O62^6^-在水溶液中的氧化还原机理,讨论并指认了紫外吸收为e→*和e→b2的荷移跃迁谱带, 考察了抗衡离子M^n^+对主要红外振动光谱, 热分解温度及其分解产物的影响。     

Drying dissipative structures of the aqueous suspensions of monodisperse bentonite particles

Macroscopic and microscopic dissipative structural patterns formed in the course of drying the fractionated and monodisperse bentonite particles (plate-like in their shape) in aqueous deionized suspension and in the presence of NaCl have been studied on a cover glass. The patterns coexisted with the broad ring of the hill accumulated with the particles and with the round hills are formed around the outside edges of the film and in the center, respectively, in the macroscopic scale. By the addition of NaCl the pattern shifts from the broad ring to the round hill in the center. The spoke-like cracks, which have been observed for the suspensions of the spherical particles so often hitherto, are not observed at all for the bentonite suspensions. The characteristic convection flow of the particles and the interactions among the particles and substrate are important for the macroscopic pattern formation. Wrinkled, branch-like and/or star-like fractal patterns are observed in the microscopic scale. These patterns are determined mainly by the electrostatic and polar interactions between the particles and/or between the particle and the substrate in the course of drying.