Thermal analysis of montmorillonites modified with quaternary phosphonium and ammonium surfactants

The thermal stability of seven organically modified montmorillonites (‘organoclays’) has been investigated using differential thermal analysis, differential scanning calorimetry, and thermogravimetry in conjunction with X-ray diffractometry. Six organoclays were synthesised by replacing the interlayer inorganic cations, initially present, with quaternary phosphonium and ammonium surfactant cations. The samples modified with tetrabutylphosphonium (TBP), and butyltriphenylphosphonium (BTPP) ions have an appreciably higher thermal stability than the octadecyltrimethylammonium (ODTMA)-modified clays. Thus, in the case of TBP- and BTPP-modified montmorillonites, the onset temperature of decomposition is close to 300 °C. Samples modified with hexadecyltributylphosphonium (HDTBP) ions have a lower onset temperature of decomposition of 225 °C. In comparison, the onset temperature for ODTMA-montmorillonites (obtained at different concentrations of ODTMA-bromide) ranges from 158 to 222 °C, being highest where the concentration of intercalated surfactant is lowest. The onset temperature for a commercial alkylsilane-treated quaternary ammonium-modified organoclay (S-BEN N-400FP) is 207 °C. The basal spacing of the TBP- and BTPP-modified clays is 1.7–1.8 nm, indicating a monolayer arrangement of quaternary phosphonium ions in the interlayer space, while the value of 2.5 nm for HDTBP-montmorillonite indicates a more open structure. The ODTMA-modified samples have basal spacings ranging from 1.9 to 2.1 nm, indicative of a bilayer to pseudo-trilayer arrangement. The exceptionally high basal spacing of 3.4 nm for the S-BEN N-400FP organoclay might be due to interlayer penetration of organosilane hydrolysis products during synthesis. The thermal properties of organoclays are apparently related to the nature of the surfactants and their arrangement in the interlayer space of montmorillonite.     

Structure Processing of Web-Based Menus

Grounded in cognitive load theory, levels of processing theory, modes of learning research, and the facets of working memory (WM) framework, the primary goal of this investigation was to seek empirical evidence for a structure processing mechanism in WM that facilitates the coordination of associations made into coherent structures and the role this mechanism might play in performance and retention. This goal was motivated by a gap in the understanding of mental model production and encoding processes in WM. To carry out this goal, two usability studies were conducted to investigate retention, error, and time performance of Web-based menus created with structured or unstructured design. Relationships between these measures and coordination ability in WM, as well as storage and supervision ability, were also assessed. In Study 1, which tested simple Web-based menus, correlations of .28, ?.56, and ?.54 were detected between coordination (CC) and retention scores, CC and errors, and CC and time; in Study 2, which tested commercial Web-based menus, correlations of .46, ?.45, and ?.25 were detected. For Studies 1 and 2, differences in favor of structured design for retention, error, and time performance were highly significant (p < .001).     

夹层玻璃用粘合剂胶膜性能研究

以Ｐ（ＭＭＡ－ＭＡＡ）共聚物作为夹层玻璃粘合剂，考察了胶膜的拉伸强度、伸长率及胶膜的表面形态，讨论了影响膜性能的因素及规律。     

Let’s play together: Effects of video-game play on intergenerational perceptions among youth and elderly participants

In this paper, we report on a longitudinal study that investigates the effects of video-game play on intergenerational perceptions amongst youths and the elderly after participating in a program involving regular interaction sessions over two months. Each pair of participants, consisting of one youth and one elderly, was randomly assigned to either the video-game condition (n = 38, 19 from each age group) or the non-video-game condition (n = 36, 18 each). Attraction, intergroup anxiety, attitudes, and game enjoyment were measured through pre-test and post-test surveys to investigate changes in perceptions. Results showed that participants in the video-game condition reported more positive changes in intergroup anxiety and attitudes, compared to participants in the non-video-game condition. Mediation analyses showed that specific attraction towards their interaction partner mediated the effects of video-game play on attitudes and intergroup anxiety towards the general members of the other age group. In addition, the results showed that game enjoyment played an important role in developing positive intergenerational perceptions only for the elderly, but not for the youth participants in the video-game condition. We discuss implications with respect to options to enhance intergenerational perceptions and communication for youth and elderly cohorts in today’s hyper-ageing society.     

Interactions of Clay Minerals with Organic Monomers

The role of clay minerals in influencing the polymerization of organic monomers can be ascribed to a charge transfer between the clay and the adsorbed species. Polymerization may be either initiated or inhibited by the clays.     

Clay-activated transformation of humic acid at high pressure and temperature

The hydrothermal transformation of humic acid in the presence of montmorillonite has been investigated. At a pressure of 100 MPa and a temperature of 300°C, humic acid was transformed into a coal-like macromolecule after 10 days. Besides being enriched in hydrogen and aromatic rings, the product showed regions of long-range structural order. Hydrothermal treatment in the absence of clay led to extensive decomposition of the humic acid.     

Properties of (K,Na)NbO3-based lead-free piezoelectric films prepared by pulsed laser deposition

To investigate the properties of (K,Na)NbO₃-based lead-free piezoelectric films at the morphotropic phase boundary composition, we fabricated epitaxial [(K_0.5Na_0.5)_0.97Li_0.03] (Nb_0.8Ta_0.2)O₃ films on (001), (110) and (111)-oriented single crystal SrTiO₃ substrates by pulsed laser deposition. The structure and electrical properties of the films were studied. Dielectric constants of 540, 390 and 300 and remnant polarizations of 4.00, 1.05, and 0.35 μC/cm² were observed for the (001), (110) and (111) oriented films, respectively.