Study of Reaction Between a Low Molecular Weight,Highly Functionalized Polyethylene and Hexamethylenediamine

Reactions were carried out between a low molecular weight, highly functionalized maleic anhydride‐grafted polyethylene and hexamethylenediamine in a melt blender at 150 °C for various stoichiometric ratios of functional groups. For all compositions, two peaks were observed in the mixing torque data. The appearance of the first peak, observed soon after the introduction of the reactive mixture to the melt blender, was independent of composition. The second peak was composition‐dependent. Gel content and FTIR analyses suggest that the first peak is a result of melting functionalized polyethylene and a reaction of the anhydride and amine functionalities, while the second was mainly a result of crosslinking. The time between the first and second peak defines a processing window, in which the reaction mixture is thermoplastic. Higher temperature melt processing of the thermoplastic reaction products converted these materials to thermosets. During this conversion, the progress of the anhydride–amine reaction was studied using FTIR, as well as by measuring the generation of the insoluble crosslinked material. The FTIR results reveal that the reaction between anhydride and amine moieties results in the formation of an amide intermediate, which then converts to cyclic imide at higher temperatures. The analysis suggests that the use of the FTIR anhydride absorption to assess the degree of reaction is misleading in these reactions.

     

Macroscopic Properties of Restacked,Redox‐Liquid Exfoliated Graphite and Graphite Mimics Produced in Bulk Quantities

The excellent properties exhibited by monolayer graphene have spurred the development of exfoliation techniques using bulk graphite to produce large quantities of pristine monolayer sheets. Development of simple chemistry to exfoliate and intercalate graphite and graphite mimics in large quantities is required for numerous applications. To determine the macroscopic behavior of restacked, exfoliated bulk materials, a systematic approach is presented using a simple, redox‐liquid sonication process along to obtain large quantities of 2D and 3D hexagonally layered graphite, molybdenum disulfide, and boron nitride, which are subsequently characterized to observe chemical and structural changes. For MoS₂ sonicated with the antioxidant sodium bisulfite, results from Raman spectroscopy, X‐ray diffraction, and electron microscopy indicate the presence of distorted phases from different polymorphs, and apparent nanotube structures in the bulk, restacked powder. Furthermore, using thermograviemtric analysis, the antioxidant enhances the resistance to oxidative degradation of MoS₂, upon thermal treatment up to 900 °C. The addition of the ionic antioxidant decreased dispersion stability in non‐polar solvent, suggesting decreased compatibility with non‐polar systems. Using simple chemical methods, the ability to generate tailored multidimensional layered materials with unique macroscopic properties is critical for numerous applications, including electrical devices, reinforced polymer composites, lithium–ion capacitors, and chemical sensing.     

Electrolytic preparation of Al3Ni fibers from the eutectic alloy,AlAl3Ni

An electrolytic procedure was developed to remove the trialuminum nickel fibers from the aluminum matrix in the eutectic alloy, AlAl₃Ni. The procedure consists of electrolyzing the aluminum matrix at potentials ranging from ?0.8 to +0.5 volts (vs S.C.E.) in a 1$\text{M}$ potassium hydroxide electrolyte. Scanning electron photomicrographs showed that the separated Al₃Ni fibers are intact. Anodic polarization studies with aluminum-nickel alloys illustrated that the presence of nickel protects aluminum from oxidation. Studies with a special fabricated platinum electrode demonstrated that the Al₃Ni fibers are not oxidized within the potential range of ?0.8 to +0.5 (vs. S.C.E.) in a 1$\text{M}$ potassium hydroxide electrolyte. This decreased rate of oxidation of aluminum in the Al₃Ni fibers is correlated with the low rate of diffusion of the aluminum in the Al₃Ni orthorhombic crystals.     

The thermal sensitivity of nitrification as a function of the concentration of nitrogen substrate

The joint influence of substrate concentration and temperature upon the rates of microbially mediated ammonia oxidation and nitrite oxidation is analyzed using rate laws reported in the literature. This analysis shows that (1) a family of substrate isoconcentrates is required to describe the thermal sensitivity of each oxidation step; (2) the optimum temperature of each step increases as the logarithm of its substrate concentration; and (3) the thermal rate-maximum of each step increases as its substrate concentration raised to a fractional power. From these relations and published parameter values, the progressions of optimum temperature and maximum rate with substrate concentration are calculated for each step. The thermal sensitivity of ammonia oxidation is thus seen to differ substantially from that of nitrite oxidation. The limits of validity and two potential applications of these results are discussed.     

Ego development and female delinquency: a cognitive-developmental approach

On 16 specimens of sheep of either sex the connections of the lumbo-sacral portion of the synpathetic trunk and of the spinal cord with the pelvic plexus were investigated bilaterally. On the basis of the studies it was found that the sympathetic branches proceed from the ganglia L3-L7 and S1-S4 of the sympathetic trunk, including in the lumbar portion 62.5% from L3-L6, 18.7% from L3-L5, 12.5% from L4-L6 and 6.2% from L4-L7, while in the sacral portion 56.2% from S1-S4, 31.2% from S2-S4 and 12.5% from S1S2S4. The parasympathetic branches proceed from the abdominal branches of the sacral spinal nerves (n. pudendus et n. haemorrhoidalis, fig. 3) at the height of S2-S4, including 75% from S3-S4 and 25% from S2S3S4.     

Induction of Decision Trees

The technology for building knowledge-based systems by inductive inference from examples has been demonstrated successfully in several practical applications. This paper summarizes an approach to synthesizing decision trees that has been used in a variety of systems, and it describes one such system, ID3, in detail. Results from recent studies show ways in which the methodology can be modified to deal with information that is noisy and/or incomplete. A reported shortcoming of the basic algorithm is discussed and two means of overcoming it are compared. The paper concludes with illustrations of current research directions.     

Working memory, attention, and communication disturbances in schizophrenia.

The authors hypothesized that schizophrenic communication disturbances reflect specific cognitive deficits in the areas of working memory and attention. They examined the cognitive correlates of communication disturbances, as measured by linguistic reference performance, in schizophrenic (n?=?48), bipolar (n?=?24), and nonpsychiatric control (n?=?23) individuals. Reference performance ratings in the schizophrenic patients were associated with scores on tests of working memory and attention and were not related to performance on concept formation or verbal fluency tests. In contrast, in the bipolar and nonpsychiatric individuals, reference performance was associated with concept formation and verbal fluency test scores but was not related to performance on tests of working memory. Implications with respect to the processes underlying schizophrenic communication disturbances are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex roles and gender differences in the experience of depression.

Studied sex differences and sex role correlates of depressive experiences in 82 female and 39 male college students. Gender differences in depressive experiences were found. These differences were consistent with societal sex role expectations. The level of depression on the Zung Self-Rating Depression Scale was negatively associated with sex role congruence, as assessed by the Sex-Role Stereotype Questionnaire, scored for Competency and Warmth–Expressiveness. Degree of sex role congruence within the male and female samples was also associated with different depressive experiences on the Depressive Experiences Questionnaire. The sex differences and the different intrasex correlations indicated that experiences of depression are associated with different facets of sex role stereotypes. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The C terminus of E1A regulates tumor progression and epithelial cell differentiation

The E1A gene of adenovirus has been considered both a dominant oncogene and a tumor suppressor. It has been reported to induce epithelial cell but to prevent myoblast differentiation. E1A enables oncogenes that are unable to transform primary cells on their own to do so, yet suppresses tumor progression toward invasion and metastasis. To try to reconcile the seemingly, conflicting E1A phenotypes, we examined the expression of epithelial cell specific and characterizing proteins in immortalized or tumorigenically transformed primary epithelial cells expressing wild-type E1A or a C-terminal mutant that has lost tumor suppressive abilities. All the cell types continued to express cytokeratin. Epithelial cell morphology, social behavior, and growth characteristics were retained by cells expressing wild-type E1A, even in the presence of an activated ras oncogene. Mutant E1A-expressing cells were less well differentiated even in the absence of ras. They were specifically defective in cell-cell junctional complexes, such as tight and adherens junctions and desmosomes. There was also a preference for those actin structures prominent in fibroblasts: stress fibers and filopodia, while in the wild-type E1A expressing cells, cortical actin and circumferential actin filaments were dominant. Thus the E1A-mutant-expressing cells were already predisposed to a more advanced tumor stage even when they were only immortalized and not transformed. The results suggest the possibility that the C terminus of E1A may be involved in regulating epithelial mesenchymal transitions, which have previously been linked to tumor progression.     

Garner and congruence effects in the speeded classification of bimodal signals.

The role of attention in speeded Garner classification of concurrently presented auditory and visual signals was examined in 4 experiments. Within-trial interference (i.e., congruence effects) occurred regardless of the attentional demands of the task. Between-trials interference (i.e., Garner interference) occurred only under conditions of divided attention when making judgments about auditory signals. Of importance, the data show congruence effects in the absence of Garner interference. Such a pattern has been rarely reported in studies of the classification of purely visual stimuli and contradicts theoretical accounts asserting that the effects share a common locus. The data question the notion that Garner classification reveals fundamental insights about the nature of the perceptual processing of bimodal stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)