Lead halide perovskite nanowires stabilized by block copolymers for Langmuir-Blodgett assembly

The rapid development of solar cells based on lead halide perovskites (LHPs) has prompted very active research activities in other closely-related fields. Colloidal nanostructures of such materials display superior optoelectronic properties. Especially, one-dimensional (1D) LHPs nanowires show anisotropic optical properties when they are highly oriented. However, the ionic nature makes them very sensitive to external environment, limiting their large scale practical applications. Here, we introduce an amphiphilic block copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-P4VP), to chemically modify the surface of colloidal CsPbBr₃ nanowires. The resulting core-shell nanowires show enhanced photoluminescent emission and good colloidal stability against water. Taking advantage of the stability enhancement, we further applied a modified Langmuir-Blodgett technique to assemble monolayers of highly aligned nanowires, and studied their anisotropic optical properties.

     

Is the Strategic Asset Seeking Investment Proclivity of Chinese MNEs Different to that of Developed Market MNEs? A Comparative Analysis of Location Choice and Orientation

Do emerging market MNEs acquire strategic assets in psychically distant developed markets to augment the firm-specific advantages they lack? This question is central to current conceptual discussion of their FDI strategies. To date, however, empirical testing has focused on emerging market MNE FDI location choices in isolation to indirectly infer facts about strategic asset seeking orientation. There are two weaknesses with this approach. First, comparative analysis with developed market MNEs is limited. Second, the focus on geographical location choices does not account for important direct, firm-level evidence on the strategic assets found in foreign subsidiaries. To address these gaps, we first undertake a comparative location choice study of Chinese MNE and developed market MNE FDI in the US. Second, we test corresponding firm-level US subsidiary data using logit modelling to explore whether there are differences between Chinese and developed market MNEs. Our results indicate similarities, rather than differences, in the strategic asset seeking behavior of Chinese and developed market MNEs. This calls into question whether theoretical extension is necessary to explain the behavior of emerging market MNEs as well as the value of indirect, location choice approaches to the analysis of strategic asset seeking FDI.     

Jamming Skins that Control System Rigidity from the Surface

Numerous animals adapt their stiffness during natural motions to increase efficiency or environmental adaptability. For example, octopuses stiffen their tentacles to increase efficiency during reaching, and several species adjust their leg stiffness to maintain stability when running across varied terrain. Inspired by nature, variable-stiffness machines can switch between rigid and soft states. However, existing variable-stiffness systems are usually purpose-built for a particular application and lack universal adaptability. Here, reconfigurable stiffness-changing skins that can stretch and fold to create 3D structures or attach to the surface of objects to influence their rigidity are presented. These “jamming skins” employ vacuum-powered jamming of interleaved, discrete planar elements, enabling 2D stretchability of the skin in its soft state. Stretching allows jamming skins to be reversibly shaped into load-bearing, functional tools on-demand. Additionally, they can be attached to host structures with complex curvatures, such as robot arms and portions of the human body, to provide support or create a mold. We also show how multiple skins can work together to modify the workspace of a continuum robot by creating instantaneous joints. Jamming skins thus serve as a reconfigurable approach to creating tools and adapting structural rigidity on-demand.     

Concept drift detection and adaptation for federated and continual learning

Smart devices, such as smartphones, wearables, robots, and others, can collect vast amounts of data from their environment. This data is suitable for training machine learning models, which can significantly improve their behavior, and therefore, the user experience. Federated learning is a young and popular framework that allows multiple distributed devices to train deep learning models collaboratively while preserving data privacy. Nevertheless, this approach may not be optimal for scenarios where data distribution is non-identical among the participants or changes over time, causing what is known as concept drift. Little research has yet been done in this field, but this kind of situation is quite frequent in real life and poses new challenges to both continual and federated learning. Therefore, in this work, we present a new method, called Concept-Drift-Aware Federated Averaging (CDA-FedAvg). Our proposal is an extension of the most popular federated algorithm, Federated Averaging (FedAvg), enhancing it for continual adaptation under concept drift. We empirically demonstrate the weaknesses of regular FedAvg and prove that CDA-FedAvg outperforms it in this type of scenario.

     

Miscible blends of biobased poly(lactide) with poly(methyl methacrylate): Effects of chopped glass fiber incorporation

Poly(lactide) (PLA) and poly(methyl methacrylate) (PMMA) are melt compounded with chopped glass fiber using laboratory scale twin‐screw extrusion. Physical properties are examined using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA), tensile testing, impact testing, X‐ray computed tomography (CT) scanning, and field emission scanning electron microscopy (FE‐SEM). Molecular weight is determined using gel permeation chromatography (GPC). Miscibility of the blends is implied by the presence of a single glass transition temperature and homogeneous morphology. PLA/PMMA blends tend to show positive deviations from a simple linear mixing rule in their mechanical properties (e.g., tensile toughness, modulus, and stress at break). The addition of 40 wt % glass fiber to the system dramatically increases physical properties. Across all blend compositions, the tensile modulus increases from roughly 3 GPa to roughly 10 GPa. Estimated heat distortion temperatures (HDTs) are also greatly enhanced; the pure PLA sample HDT increases from 75 °C to 135 °C. Fiber filled polymer blends represent a sustainable class of earth abundant materials which should prove useful across a range of applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44868.     

Change of intensity fails to produce an irrelevant sound effect: Implications for the representation of unattended sound.

Sequences of changing sounds that are irrelevant to the task at hand disrupt serial recall appreciably even though participants are instructed to ignore the sounds. Three experiments, which compared the effect of changing token identity with that of changing intensity in the 55- to 85-dB(A) range, were conducted. Although serial recall was impaired by changes in token identity, no disruptive effects of a change in intensity were found. This was replicated using speech and nonspeech. Overall, the absence of a changing intensity effect was based on an analysis of the performance of 115 participants in a design whose power was .98. This outcome suggests that the representation of intensity in preattentive processing of auditory stimuli is somewhat different from that of other acoustic features. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organizational factors in selective attention: The interplay of acoustic distinctiveness and auditory streaming in the irrelevant sound effect.

A series of studies further explored the way in which irrelevant sound disrupts the serial recall of visually presented verbal sequences. The hypothesis that distinctiveness (stimulus mismatch) within auditory irrelevant sequences is a critical determinant of disruption of serial recall was tested. Experiment 1 showed that the degree of disruption was related to the degree of mismatch between successive stimuli. However, in Experiment 2, changes in 2 attributes of a stimulus produced less disruption than when only 1 was changed, suggesting mismatch alone was not the key factor. These results were reconciled with the changing-state hypothesis in Experiment 3 in which change and disruption were monotonically related up to the point at which mismatch created 2 streams. Object-based theories are able to explain this pattern of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Explaining the irrelevant-sound effect: Temporal distinctiveness or changing state?

Task-irrelevant background sound disrupts serial recall. One account of this effect assumes that irrelevant events close to or during the presentation of a to-be-remembered list will interfere by disrupting temporal codes. A second account predicts that disruption will be greatest when the burden on rehearsal is high, as order cues in the auditory sequence interfere with those in the memory set. The authors tested these predictions by restricting the sound to different phases of the serial recall task. Sound presented just before the list and sound presented early in list presentation did not disrupt recall, but sound presented late in the list or after list presentation produced significant disruption. Sound presented after the list was more disruptive of recall for early list items than sound presented at the same time as those items. An account based on disruption of serial rehearsal, not the disruption of temporal codes, is supported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Insights into the Genetic Variations of Human Cytochrome P450 2C9: Structural Analysis,Characterization and Comparison

Cytochromes P450 (CYP) are one of the major xenobiotic metabolizing enzymes with increasing importance in pharmacogenetics. The CYP2C9 enzyme is responsible for the metabolism of a wide range of clinical drugs. More than sixty genetic variations have been identified in CYP2C9 with many demonstrating reduced activity compared to the wild-type (WT) enzyme. The CYP2C9*8 allele is predominantly found in persons of African ancestry and results in altered clearance of several drug substrates of CYP2C9. The X-ray crystal structure of CYP2C9*8, which represents an amino acid variation from arginine to histidine at position 150 (R150H), was solved in complex with losartan. The overall conformation of the CYP2C9*8-losartan complex was similar to the previously solved complex with wild type (WT) protein, but it differs in the occupancy of losartan. One molecule of losartan was bound in the active site and another on the surface in an identical orientation to that observed in the WT complex. However, unlike the WT structure, the losartan in the access channel was not observed in the *8 complex. Furthermore, isothermal titration calorimetry studies illustrated weaker binding of losartan to *8 compared to WT. Interestingly, the CYP2C9*8 interaction with losartan was not as weak as the CYP2C9*3 variant, which showed up to three-fold weaker average dissociation constant compared to the WT. Taken together, the structural and solution characterization yields insights into the similarities and differences of losartan binding to CYP2C9 variants and provides a useful framework for probing the role of amino acid substitution and substrate dependent activity.     

TAAR1 Expression in Human Macrophages and Brain Tissue: A Potential Novel Facet of MS Neuroinflammation

TAAR1 is a neuroregulator with emerging evidence suggesting a role in immunomodulation. Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system. Here, we investigate TAAR1 expression in human primary monocytes, peripherally-derived macrophages, and MS brain tissue. RT-qPCR was used to assess TAAR1 levels in MS monocytes. Using a previously validated anti-human TAAR1 antibody and fluorescence microscopy, TAAR1 protein was visualized in lipopolysaccharide-stimulated or basal human macrophages, as well as macrophage/microglia populations surrounding, bordering, and within a mixed active/inactive MS lesion. In vivo, TAAR1 mRNA expression was significantly lower in MS monocytes compared to age- and sex-matched healthy controls. In vitro, TAAR1 protein showed a predominant nuclear localization in quiescent/control macrophages with a shift to a diffuse intracellular distribution following lipopolysaccharide-induced activation. In brain tissue, TAAR1 protein was predominantly expressed in macrophages/microglia within the border region of mixed active/inactive MS lesions. Considering that TAAR1-mediated anti-inflammatory effects have been previously reported, decreased mRNA in MS patients suggests possible pathophysiologic relevance. A shift in TAAR1 localization following pro-inflammatory activation suggests its function is altered in pro-inflammatory states, while TAAR1-expressing macrophages/microglia bordering an MS lesion supports TAAR1 as a novel pharmacological target in cells directly implicated in MS neuroinflammation.