Synthesis of Gemini‐Like Methyl Acrylate‐Acrylic Acid‐Methyl Acrylate Triblock Copolymers Surfactants by RAFT Polymerization in Solution and Investigation of their Behavior at the Air–Water Interface

A series of methyl acrylate‐acrylic acid amphiphilic triblock copolymers (PMA‐PAA‐PMA) were prepared by solution polymerization using S,S′‐bis (α,α‐dimethy1acetic acid) trithiocarbonate (BDAT) as a reversible addition fragmentation chain transfer (RAFT) agent and methyl acrylate (MA) as the first monomer. The triblock copolymers and their common MA homopolymer precursors were characterized in terms of their compositions, molecular weights and behavior at the air–water interface using ¹H‐NMR spectroscopy, thermogravimetric analysis, gel permeation chromatography, surface tension, transmission electron microscopy (TEM) and dynamic light scattering respectively. The results indicated that PMA‐PAA‐PMA was successfully synthesized through RAFT polymerization. The polydispersity index (PDI) decreased when the molar ratio [n(MA)/n(AA)] increased, the lowest PDI was obtained at 5.23 wt% RAFT and the molecular weights were consistent with the theoretical value as the RAFT agent percentage varied. The polymer neutralized by sodium hydroxide solution shows a low critical micelle concentration (CMC), which was <10^?2 mol L^?1 in water. The A_min values increased and showed a maximum with decreased AA chain length. TEM showed that the neutralized polymer formed a special vesicle structure with large pore structure which led to a low CMC and surface tension of water.     

Study of the growth and structural properties of InMnAs dots grown on high-index surfaces by MOVPE

The growth of InMnAs quantum dots by low pressure MOVPE technique on patterned (1 0 0) GaAs substrates was studied. The patterning in the form of ridges with sidewalls having (2 1 1) and (3 1 1) facets was prepared by wet chemical etching via a GaAs/AlAs sacrificial etching mask structure. AFM studies showed that the dots formation and distribution were very similar for both types of facets under study. InMnAs dot density on the (3 1 1) plane is about 5–7 times lower in comparison to that on the (1 0 0) planar substrate. The dots on sidewalls are larger in comparison to average dots formatted on planar GaAs (1 0 0) substrate. The lateral dimensions of these dots are in the interval 100–180 nm. In addition, dot distribution along the sidewall (from top to bottom) is not uniform. A higher dot concentration was observed close to the intersection of (3 1 1) facets with concave bottom part of the valleys between ridges. Finally, no dots were grown on the (1 0 0) plane created by self-faceting on the top of the triangular ridges. This is probably a consequence of the high quality of the (1 0 0) facet formed by lateral overgrowth.     

2,2’-亚甲基双(4-甲基-6-α-甲基苄基苯酚)的合成与性能评价

以单苯乙烯化对甲酚(单酚)为底物,与35%~37%的甲醛水溶液在酸催化的条件下进行反应,合成了一种酚羟基邻位取代具有活泼α-H原子的双酚类抗氧剂2,2’-亚甲基双(4-甲基-6-α-甲基苄基苯酚)。最佳工艺条件:n(单酚)∶n(甲醛)=1∶3,80℃回流反应5 h,产率85%。测定加抗氧剂的润滑油油样的过氧化值(POV)表明,合成双酚抗氧剂具有比抗氧剂2246更好的抗氧性。     

Fuzzy multicriteria selection of alternatives: The worst‐case method

In this article, we propose the method of the multicriteria alternative selection under uncertainty. The basis of the method is the principle of the Bellman–Zadeh fuzzy measures intersection and nine‐point linguistic rating scale of Saaty. The novelty of the method presented here consists of the fact that it does not require labor‐intensive procedures, requiring arraying and array processing of paired comparisons matrix. Instead, special correlations are used, which are based on the comparison with the worst alternative and the least important criterion. As an example for the utilization of our method, we use the problem for choosing cars. © 2010 Wiley Periodicals, Inc.     

Implicit and explicit preferences for physical attractiveness in a romantic partner: A double dissociation in predictive validity.

Five studies develop and examine the predictive validity of an implicit measure of the preference for physical attractiveness in a romantic partner. Three hypotheses were generally supported. First, 2 variants of the go/no-go association task revealed that participants, on average, demonstrate an implicit preference (i.e., a positive spontaneous affective reaction) for physical attractiveness in a romantic partner. Second, these implicit measures were not redundant with a traditional explicit measure: The correlation between these constructs was .00 on average, and the implicit measures revealed no reliable sex differences, unlike the explicit measure. Third, explicit and implicit measures exhibited a double dissociation in predictive validity. Specifically, explicit preferences predicted the extent to which attractiveness was associated with participants' romantic interest in opposite-sex photographs but not their romantic interest in real-life opposite-sex speed-daters or confederates. Implicit preferences showed the opposite pattern. This research extends prior work on implicit processes in romantic relationships and offers the first demonstration that any measure of a preference for a particular characteristic in a romantic partner (an implicit measure of physical attractiveness, in this case) predicts individuals' evaluation of live potential romantic partners. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Giant carbon solubility in Au nanoparticles

Variable temperature transmission electron microscopy of individual 5 nm Au nanoparticles shows a striking increase in the particle size on raising the temperature from room temperature to 500 °C in the presence of carbon from amorphous carbon support. Using the assembly of ordered graphene shells on the surface of individual nanoparticles at elevated temperatures—and the high pressures induced by such shells—as an experimental tool to study the origins of this swelling, we find that the volume increase is associated with the uptake of carbon to concentrations exceeding the bulk solubility by more than four orders of magnitude. The formation of stable metal–carbon nanostructures that have no bulk equivalent may have important implications on the functional properties of metal nanoparticles.     

An on-line combined linear–nonlinear fatigue crack detection technique

To monitor the structural health during fatigue tests, classical nondestructive tests (ultrasonic inspection, liquid penetration, eddy current, etc.) are usually performed at regular time instances. Unfortunately, the fatigue tests should be interrupted to use these techniques. In addition, a large amount of user interaction is required.In this article, vibration features are used to detect cracks on-line with the execution of a fatigue test. To perform this task, an experimental strategy is developed to simultaneously estimate static and dynamic as well as linear and nonlinear vibration features. By means of these features the sensitivity of static versus dynamic and linear versus nonlinear damage detection techniques will be qualified.Finally, it will be shown that by using nonlinear identification techniques, additional information on the damage scenario can be extracted.The validation will be done on a steel beam with a propagating fatigue crack.     

A Proof of the Security of Quantum Key Distribution

We prove the security of theoretical quantum key distribution against the most general attacks which can be performed on the channel, by an eavesdropper who has unlimited computation abilities, and the full power allowed by the rules of classical and quantum physics. A key created that way can then be used to transmit secure messages such that their security is also unaffected in the future.     

Effect of stochastically anisotropic morphology on the mechanical behavior of microbeams

In many Micro-Electro-Mechanical-Systems (MEMS) applications such as polysilicon microstructures, the size of the basic element (grain), compared with the structure’s scale, is not negligible. In these cases, the random microstructure causes statistical dispersion of its response to load, experimentally observed by many researchers. The accompanying calculations, which generally treat the material as homogeneous and isotropic, do not model the structures properly. In this work, we analytically study the relations between morphological properties and the generalized displacements of statically determinate beams, frequently used in MEMS. The analysis includes shear deformation effects, material and structural couplings such as shear and bending deformations due to normal forces, and nonisotropic effects. The governing equations are presented in a special tensorial form, which enables finding analytical expressions for the mean and covariance matrix of the generalized deflections in terms of well defined morphological parameters and their statistics.     

Relative importance of informational units and their role in long-term recall by closed-head-injured patients and control groups.

Applied qualitative analysis to the information recalled by control Ss and closed-head-injured (CHI) patients. The Logical Memory subtest of the Wechsler Memory Scale (WMS) was administered to 40 CHI and 40 control Ss. Recall was tested immediately after administration, 40 min later, and 24 hrs later. The analysis took into account the importance of recalled information as determined by a prior rating according to 3 levels of importance. Results suggest that CHI patients have difficulty selectively retrieving the most important information after a long delay. (PsycINFO Database Record (c) 2010 APA, all rights reserved)