Emergent <Emphasis Type=Italic>SO</Emphasis>(3) Symmetry of the Frictionless Shear Jamming Transition

We study the shear jamming of athermal frictionless soft spheres, and find that in the thermodynamic limit, a shear-jammed state exists with different elastic properties from the isotropically-jammed state. For example, shear-jammed states can have a non-zero residual shear stress in the thermodynamic limit that arises from long-range stress-stress correlations. As a result, the ratio of the shear and bulk moduli, which in isotropically-jammed systems vanishes as the jamming transition is approached from above, instead approaches a constant. Despite these striking differences, we argue that in a deeper sense, the shear jamming and isotropic jamming transitions actually have the same symmetry, and that the differences can be fully understood by rotating the six-dimensional basis of the elastic modulus tensor.     

BOLD responses to trigeminal nerve stimulation

The current study investigates a new model of barrel cortex activation using stimulation of the infraorbital branch of the trigeminal nerve. A robust and reproducible activation of the rat barrel cortex was obtained following trigeminal nerve stimulation. Blood oxygen level-dependent (BOLD) effects were obtained in the primary somatosensory barrel cortex (S1BF), the secondary somatosensory cortex (S2) and the motor cortex. These cortical areas were reached from afferent pathways from the trigeminal ganglion, the trigeminal nuclei and thalamic nuclei from which neurons project their axons upon whisker stimulation. The maximum BOLD responses were obtained for a stimulus frequency of 1 Hz, a stimulus pulse width of 100 μs and for current intensities between 1.5 and 3 mA. The BOLD response was nonlinear as a function of frequency and current intensity. Additionally, modeling BOLD responses in the rat barrel cortex from separate cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO₂) measurements showed good agreement with the shape and amplitude of measured BOLD responses as a function of stimulus frequency and will potentially allow to identify the sources of BOLD nonlinearities. Activation of the rat barrel cortex using trigeminal nerve stimulation will contribute to the interpretation of the BOLD signals from functional magnetic resonance imaging studies.     

Numbers,scale and symbols: the public understanding of nanotechnology

Nanotechnology will be an increasing part of the everyday lives of most people in the world. There is a general recognition that few people understand the implications of the technology, the technology itself or even the definition of the word. This lack of understanding stems from a lack of knowledge about science in general but more specifically difficulty in grasping the size scale and symbolism of nanotechnology. A potential key to informing the general public is establishing the ability to comprehend the scale of nanotechnology. Transitioning from the macro to the nanoscale seems to require an ability to comprehend scales of one-billion. Scaling is a skill not common in most individuals and tests of their ability to extrapolate size based upon scaling a common object demonstrates that most individuals cannot scale to the extent needed to make the transition to nanoscale. Symbolism is another important vehicle to providing the general public with a basis to understand the concepts of nanotechnology. With increasing age, individuals are able to draw representations of atomic scale objects, but these tend to be iconic and the different representations not easily translated. Ball and stick models are most recognized by the public, which provides an opportunity to present not only useful symbolism but also a reference point for the atomic scale.     

Zwei-Elemente-Erzeugung und Endlichkeit der Dimension von Divisionsalgebren

Ohne ZusammenfassungNorth Atlantic Treaty Organization (U.S.A.) Postdoctoral Fellow im Mathematischen Institut der Universität Heidelberg (Urlaub von Pennsylvania State University, University Park, Pa.).     

Optical rotatory dispersion studies—CIV Low-temperature circular dichroism behavior of various chromophoric derivatives of alcohols and amines

The low-temperature circular dichroism behavior of various cyclic and alicyclic systems containing the methyl xanthato-, N,N-diethyl-N′-acylthioureyl-, N-phthalimido-, nitrito- and dithio-carbalkoxy- chromophores is discussed. Rotational strength (R₀^T) values are reported where possible and changes in this parameter upon variation of the temperature are interpreted, where relevant, in terms of the degree of steric inhibition to free rotation about the various bonds connected to the asymmetric center bearing (or nearest to) the chromophore moiety.     

Anionic Graft Copolymers. ll. Styrene Grafts on EPT Rubbers

Rubbers containing a low level of unsaturation such as EPT may be metalated with a chelate made from s-butyllithium and N,N,N′- N′ -tetramethylethylethylenediamine. The lithiated polymers, reacted with styrene, result in polystyrene graft copolymers. The physical properties are affected by graft level and polystyrene content.     

Numerical analysis of nematic liquid crystal alignment on asymmetric surface grating structures

The influence of an asymmetric periodic grooved cell surface on the 2D static director configuration of a nematic liquid crystal has been investigated. The minimum in the Frank-Oseen free energy was solved numerically with the Rapini-Papoular form of the surface anchoring energy at the nematic-grating interface. Results are presented for the variation of pretilt angle in the tilted bulk director field as a function of the surface groove depth, pitch and asymmetry and the bulk parameters. The simulations demonstrate the existence of two energetically degenerate high and low pretilted bulk alignment configurations. The pretilt values in these two regimes and also for the low tilt regime with finite surface anchoring are consistent with experimental results. An effective increase in the resolution of the model is obtained by using an irregular grid to describe the surface profile.     

Polyethylene Glycol Backfilling Mitigates the Negative Impact of the Protein Corona on Nanoparticle Cell Targeting

In protein‐rich environments such as the blood, the formation of a protein corona on receptor‐targeting nanoparticles prevents target recognition. As a result, the ability of targeted nanoparticles to selectively bind to diseased cells is drastically inhibited. Backfilling the surface of a targeted nanoparticle with polyethylene glycol (PEG) molecules is demonstrated to reduce the formation of the protein corona and re‐establishes specific binding. The length of the backfilled PEG molecules must be less than the length of the ligand linker; otherwise, PEG interferes with the binding of the targeting ligand to its corresponding cellular receptor.     

A New Cationic Fluorescent Probe for HSO3− Based on Bisulfite Induced Aggregation Self-Assembly

In comparison with the numerous studies that have centered on developing molecular frameworks for the functionalization of fluorescent materials, less research has addressed the influence of the side chains, despite such appendages contributing significantly to the properties and applications of fluorescent materials. In this work, a new series of cationic fluorescent probes with AIE characteristics have been developed, which exhibit unique sensitivity for charge-diffusion anions, namely HSO₃⁻, via the interactions of ions and the cooperation of the controllable hydrophobicity. The impact of the alkyl chain length attached at the cationic probes suggested that the fluorescent intensity and sensitivity of the probes could be partially enhanced by adjusting their aggregation tendency through the action of the hydrophobic effect under aqueous conditions. DLS and SEM images indicated that different particle sizes and new morphologies of the probes were formed in the anion-recognition-triggered self-assembly process, which could be attributed to the composite effect of electrostatic actions, Van der Waals forces and π-π stacking.