Changes in the ways that group trainees structure their knowledge of group members with training.

Multidimensional scaling (MDS) and Pathfinder were used to examine changes in the knowledge structures of 9 group therapy trainees, and to examine convergence in the trainees' knowledge structures with one experienced group leader. Participants (experienced group therapist and group therapy trainees) judged the similarity of each pair of group members in an ongoing interpersonal process group early and late in a semester of group therapy training. As in previous research, MDS and Pathfinder analyses of these similarity judgments were used to infer the cognitive structure of the trainees and of the experienced group leader. These analyses suggested that (a) the dimensions used by the trainees to conceptualize group members increased in complexity with training, and (b) trainees' knowledge structures became more similar to the experienced leader's knowledge structure with training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ratchetting limits for cracked bodies subjected to cyclic loads and temperatures

This paper describes a methodology capable of directly evaluating the ratchetting limits in cracked bodies, subjected to cyclic loads and temperatures, for an elastic-perfectly plastic material. The foundation behind the adopted numerical procedures, the Linear Matching Method (LMM), is described. This is then followed by the application of the method to the cracked Bree problem, under variations in cyclic loading histories and structural geometries. The results from the ensuing analyses revealed the method’s ability in coping with the effect of the elastic singularity at the crack tip. The applicability of such procedures is further examined, with additional solutions to an industrial problem considered in R5 the design and life assessment procedures used by British Energy in the UK.     

Carrier Type Control of WSe2 Field‐Effect Transistors by Thickness Modulation and MoO3 Layer Doping

Control of the carrier type in 2D materials is critical for realizing complementary logic computation. Carrier type control in WSe₂ field‐effect transistors (FETs) is presented via thickness engineering and solid‐state oxide doping, which are compatible with state‐of‐the‐art integrated circuit (IC) processing. It is found that the carrier type of WSe₂ FETs evolves with its thickness, namely, p‐type (<4 nm), ambipolar (≈6 nm), and n‐type (>15 nm). This layer‐dependent carrier type can be understood as a result of drastic change of the band edge of WSe₂ as a function of the thickness and their band offsets to the metal contacts. The strong carrier type tuning by solid‐state oxide doping is also demonstrated, in which ambipolar characteristics of WSe₂ FETs are converted into pure p‐type, and the field‐effect hole mobility is enhanced by two orders of magnitude. The studies not only provide IC‐compatible processing method to control the carrier type in 2D semiconductor, but also enable to build functional devices, such as, a tunable diode formed with an asymmetrical‐thick WSe₂ flake for fast photodetectors.     

Effect of polymethylmethacrylate–montmorillonite nanocomposite on the release of some biologically active 1,2,4‐triazine derivatives

Methylmethacrylate chloromethylstyrene copolymer–montmorillonite (PMMA–MMT) intercalated nanocomposite was prepared by bulk copolymerization of methylmethacrylate (MMA) and chloromethylstyrene (2 wt%) followed by phosphonium salt formation. The intercalation of polymeric phosphonium salt into montmorillonite was achieved through an ion exchange process between sodium cations in MMT and phosphonium groups attached to the copolymer. Thermogravimetric analysis (TGA) showed improved thermal stability for the intercalated nanocomposite in comparison with the pure PMMA. Biologically active compounds including 4‐amino‐6‐methyl‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐ 5‐one (I), 4‐amino‐6‐methyl‐3,4‐dihydro‐2H‐[1,2,4]triazin‐3,5‐dithione (II), 4‐amino‐6‐(4‐methoxystyryl)‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐5‐one (III), and 4‐amino‐6‐styryl‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐5‐one (IV) have been prepared and reacted with PMMA–MMT intercalates and ion exchanged with sodium montmorillonite (MMT) in the presence of HCl. Infrared spectra (IR) show bands characteristic to amide linkage between triazine derivatives and PMMA. These nanocomposites have been characterized by X‐ray diffraction (XRD) and transmission electron microscope (TEM). The release of biologically active compounds intercalated layered silicates is controllable and these materials have a great potential as a delivery host in the pharmaceutical field. The effect of temperature and presence of saline solution on the release was studied. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Cadmium-induced functional and ultrastructural alterations in roots of two transgenic cotton cultivars

The toxic effect of cadmium (Cd) at increasing concentrations was studied with special attention being given to the root morphological and ultrastructural changes in two transgenic cotton cultivars viz. BR001 and GK30 and their wild relative viz. Coker 312. In comparison to their respective controls, low concentration (10 and 100microM) of Cd greatly stimulated seed germination, while it was inhibited by highest concentration of Cd (1000microM) in case of two transgenic cultivars. However, in Coker 312 the seed germination percentage progressively decreased over the control at all Cd levels. Various physiological and morphological parameters of the root and whole plant in both transgenic cotton cultivars and their relative wild cotton genotype respond differently towards the Cd toxicity. Bioavailability of Cd was concentration-dependent where seedling root captured more Cd as compared to shoot. BR001 accumulated more Cd followed by GK30, while Coker 312 was less Cd accumulator. The ultrastructural modifications in the root tip cells of both the transgenic cotton cultivars and their wild relative were also dose-dependent. With the increase in Cd levels, the fine structures of their root cells also invariably changed. Increase in plasmolysis of the plasma membrane, greater number of nucleoli and vacuoles and enlarged vacuoles could be observed in both transgenic cotton cultivars. In comparison to them, Coker 312 showed relatively well developed ultrastructures of the root tips except enlarged vacuoles and greater number of mitochondria. Moreover, the accumulation of Cd in the form of electron dense granules and crystals both in vacuoles and attached to cell walls were visible in both transgenic cotton cultivars and their wild relative. These results suggest that both transgenic cotton cultivars and their wild relative cotton genotype responded positively towards Cd stress at seedling stage, the internal Cd-detoxification might be through apoplastic and symplastic binding. Moreover, as a whole BR001 proved to be sensitive whereas; GK30 and Coker 312 were found as tolerant.     

Switching Energy of Ferromagnetic Logic Bits

Power dissipation in switching devices is believed to be the single most important roadblock to the continued downscaling of electronic circuits. There is a lot of experimental effort at this time to implement switching circuits based on magnets and it is important to establish power requirements for such circuits and their dependence on various parameters. This paper analyzes switching energy that is dissipated in the switching process of single-domain ferromagnets used as cascadable logic bits. We obtain generic results that can be used for comparison with alternative technologies or guide the design of magnet-based switching circuits. Two central results are established. One is that the switching energy drops significantly if the ramp time of an external pulse exceeds a critical time. This drop occurs more rapidly than what is normally expected of adiabatic switching for a capacitor. The other result is that under the switching scheme that allows for logic operations, the switching energy can be described by a single equation in both fast and slow limits. Furthermore, these generic results are used to discuss the practical consideration such as dissipation versus speed, increasing the switching speed and scaling. It is further explained that nanomagnets can have scaling laws similar to CMOS technology.     

Synthesis and antimicrobial activity of the Schiff base from polyoxyalkylene‐montmorillonite nanocomposites and aldehydes

Vanillin (4‐hydroxy‐3‐methoxy benzaldehyde) and 5‐formylamino salicylic acid microbicides were reacted with polyoxyalkylene‐montmorillonite (D_230–2000‐MMT) nanocomposites. The microstructure of these Schiff base nanocomposites was characterized by TEM and XRD. D_230–2000‐MMT nanocomposites were prepared by an ion exchange process of sodium montmorillonite (Na‐MMT) and NH₃ ⁺ groups in polyoxyalkylene amine hydrochloride with three different molecular masses of D₂₃₀, D₄₀₀, and D₂₀₀₀. Wide‐angle X‐ray diffraction confirms the intercalation of the polymer between the silicate layers. Electrostatic interaction between the positively charged NH₃ ⁺ groups and the negatively charged surface of MMT was observed. The nanocomposites were tested for antimicrobial activity against the Gram‐negative bacteria (Escherichia coli NCIM 2065), Gram‐positive bacteria (Bacillus subtillus ATCC), and fungi (Candida albicans SC5314 and Cryptococcus neoformans). The D₂₀₀₀‐MMT/vanillin Schiff base nanocomposite strongly inhibited the growth of all microorganisms that can be used in different applications. The amount of loaded polymer and the structure of the nanocomposite play an important role in inhibiting the bacterial and fungal strains. It is found that the Schiff base nanocomposite affect the morphology, oxygen consumption, and the release of cytoplasmic constituents such as potassium (K⁺), sodium (Na⁺), and calcium (Ca²⁺) ions leading to death of the cells. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers