Recrystallization in Model Ice Cream Solutions as Affected by Stabilizer Concentration

Ice recrystallization rates in simple aqueous solutions comprising fructose and a hydrocolloid stabilizer were measured. The stabilizers were an enzyme-modified guar and a non-gelling high methoxy pectin. The stabilizer concentration dependence of the recrystallization rates for both materials was similar in that increasing the concentration resulted in decreasing rates until a point is reached where further addition had no additional effect. That recrystallization rates were reduced by both gelling and non-gelling stabilizers was strongly suggestive that gelation was not a requirement for recrystallization inhibition and another more specific mechanism applies, for example a weak interfacial effect such as adsorption or blocking. This behavior was also seen with locust bean gum and guar and provided further empirical evidence to support the hypothesis that stabilizers adsorb to ice crystal surfaces.     

甲苯—正庚烷—庚烯-(3)三元系统的气液平衡

测定了庚烯-（3）的蒸气压。用Gillespie型平衡器测定了甲苯—庚烯-（3）、正庚烷—庚烯-（3）二元系及甲苯—正庚烷—庚烯-（3）三元系统的平衡数据,并分别用Spinner及White方法验证了这些数据,计算结果与实验结果是符合的。三元系统气液平衡的数据不论在工程中或是实验工作上都很重要,过去对三元系统气液平衡的研究虽然有一些,但对甲苯—正庚烷—庚烯-（3）三元系统气液平衡至今在文献上尚未有记载。 由于庚烯-（3）的蒸气压数据不见于文献,我们测定了它的蒸气压数据。正庚烷—甲苯二元系统前人已有许多结果发表,我们进行了一些校核,结果与文献记载符合。甲苯—庚烯-（3）二元系统文献上没有,我们倣效了并用Spinner方法及White方法整理。至于正庚烷—庚烯-（3）二元系统,因为此两组分的性质（如沸点、n_D~（20）等）极其接近,分析误差较大,我们将其当作理想溶液处理,误差当在允许误差以内。 三元系统的分析较为繁难,误差也较大,故希望从理论和实验材料找出其规律性,以校核实验数据和推算未知三元系统。本工作利用三个二元系统的数据,用Spinner以及White的方法推算三元系统的气液平衡,与实验数据相比较,是相互符合的。     

On some models for developmental systems Part I. Organism structure on the basis of elementary transformations

A great number of organism development processes can be accounted for by the elementary mechanisms of cell partition and cell transformation. In the present article an analytical method is presented which emphasizes the link that exists between the generating word of an organism (in the language consisting of the possible cell transformations) and the successive structures of the developmental process. The viewpoints of analysis (types of structures generated by a given type of word) and of synthesis (type of word generating a given type of structure) are considered. As an illustration of the method models of development are constructed which have already been proposed empirically to account for two types of plant development.     

On some models for developmental systems Part IX. Generalized generating word and genetic code

The model for developmental systems used by the present authors in the foregoing eight parts is generalized and compared to biological facts concerning DNA.     

HPLC determination of polycyclic aromatic hydrocarbons (PAHs) in the littoral urban sewage area of cortiou (Marseille,France)

A selective method for determining polycyclic aromatic hydrocarbons (PAHs) in sediments using solid‐phase extraction and RP‐HPLC with fluorescence and UV detection is described. The complete analytical method is used to surface sediments from the creek of Cortiou (France). Sewage from the urban area of Marseille is delivered to the creek. PAH levels in sediments (µg/g) range between 2.251 µg/g (for the benzo(a)anthracene) and 相似文献   

DESIGNING 2 POLE AND 2/4 POLE WINDINGS BY THE SIMULATED ANNEALING METHOD

ABSTRACT

The object of the present paper is to explore the possibility of using simulated annealing procedures to determine multi-speed three phase windings. It is limited to the very simple case of p/2p polarities. The program has yielded the very well known solutions; thus, research may proceed towards more difficult problems.     

Evolution in the composition of human skin surface lipids during their accumulation on scalp and hair

Qualitative examination of human surface lipids collected using a surfactant solution shows that there are no significant differences between individuals when the samples are collected after one day, starting from clean hair and scalp. On the contrary, samples collected after 4 days reveal discrepancies within the population, related to the oily hair symptom.
An evolution in the composition of the recovered mixture occurs during the 1–4 days accumulation period, which mainly results in an increased unsaturation of the total (free + glycerides) fatty acids fraction isolated after saponification.
A two-step mechanism is proposed to account for the observed evolution: in a first step, free fatty acids are cleaved from glycerides by the well known enzymatic hydrolysis. Analytical determinations show that this process is structure dependant, the straight chain saturated acids being more readily hydrolyzable than the unsaturated and branched chain species. In a second step, free fatty acids are immobilized on the keratinic fibers, by a process which involves the formation of Ca salts.
This evolution results in a decreased viscosity of the skin surface lipids and in an increase of the low temperature melting fraction of the mixture. Its extent is more or less pronounced, depending upon the individuals. Subjects who exhibit extensive evolution are affected by the oily hair symptom.
Evolution de la composition des lipides superficiels humains durant leur accumulation sur le scalp et les cheveux     

Valeur d'un test in vitro d'incorporation de glucose marque pour l'estimation de l'activité antiseborrheique

Deux methodes d'estimation de l'activité antiséborrhéique, l'une in vitro , l'autre in vivo , ont été comparées en étudiant l'action de deux produits différents: le metbufen et la N-sébaçoylméthionine. Le test in vitro d'incorporation de glucose marqué est pratiqué sur la glande préputiale de rat isolée. In vivo , sur la peau de rat castré et supplémenté par l'énanthate de testortérone, l'effet de traitement topique est suivi par l'étude histologique des glandes sébacées.
Les résultats obtenus avec les deux produits essayés présentent un parallélisme permettant de conclure à la validité du test in vitro dans le screening de molécules à activité antiséborrhéique.
An in vitro test for the evaluation of antiseborrheic activity     

AGGREGATION,EMERGENCE AND IMMERGENCE IN HIERARCHICALLY ORGANIZED SYSTEMS

Abstract

The aim of this work is to show that couplings between fast micro-dynamics and slow macro-dynamics can make emerge global properties. Emergence corresponds to a bottom-up coupling, that is to the effect exerted by a micro-level at a macro-level. Immergence corresponds to the inverse process, that is to an up-down coupling. As an example, we present a prey-predator model with different time scales in a heterogeneous environment. A fast time scale is associated to the migration process on spatial patches and a slow time scale is associated to growth and interactions between the populations. Preys go on spatial patches where resources are located and where predators can attack them. The efficiency of predators is patch-dependent. Perturbation theory is used in order to aggregate the initial system of ordinary differential equations for patch sub-populations into a macro-system of two differential equations governing total populations. First, we study a case of density-independent migrations, for which no emergence occurs. Then, we study some examples of density-dependent migrations. In this case, emerging properties appear at the population level.