Unusual Two-Step Assembly of a Minimalistic Dipeptide-Based Functional Hypergelator

Self-assembled peptide hydrogels represent the realization of peptide nanotechnology into biomedical products. There is a continuous quest to identify the simplest building blocks and optimize their critical gelation concentration (CGC). Herein, a minimalistic, de novo dipeptide, Fmoc-Lys(Fmoc)-Asp, as an hydrogelator with the lowest CGC ever reported, almost fourfold lower as compared to that of a large hexadecapeptide previously described, is reported. The dipeptide self-assembles through an unusual and unprecedented two-step process as elucidated by solid-state NMR and molecular dynamics simulation. The hydrogel is cytocompatible and supports 2D/3D cell growth. Conductive composite gels composed of Fmoc-Lys(Fmoc)-Asp and a conductive polymer exhibit excellent DNA binding. Fmoc-Lys(Fmoc)-Asp exhibits the lowest CGC and highest mechanical properties when compared to a library of dipeptide analogues, thus validating the uniqueness of the molecular design which confers useful properties for various potential applications.     

Method for Preparation of Semiconductor Quantum‐Rod Lasers in a Cylindrical Microcavity

An efficient method for preparation of semiconductor quantum rod films for robust lasing in a cylindrical microcavity is reported. A capillary tube, serving as the laser cavity, is filled with a solution of nanocrystals and irradiated with a series of intense nanosecond laser pulses to produce a nanocrystal film on the capillary surface. The films exhibit intense room‐temperature lasing in whispering‐gallery modes that develop at the film–capillary interface as corroborated from the spacing detected for the lasing modes. Good lasing stability is observed at moderate pump powers. The method was applied successfully to several quantum‐rod samples of various sizes.     

Kinetic Basicities of Aqueous Binary Mixtures: A Surprisingly Good Linear Correlation with the Gas Phase Basicity of the Organic Cosolvent

A remarkably good correlation between the rate of proton transfer from excited protonated 1-aminopyrene and the gas phase basicities of the organic component in water: organic solvent binary mixtures has been found. We suggest that use of anilinium acids minimizes the effect of anion solvation and Coulomb interactions and enables the influence of the organic cosolvent on the proton transfer to be clearly observed. The model proposed is one in which the proton is always transferred to a water molecule and a concerted proton transfer to a water molecule solvated by the organic cosolvent also occurs. The cosolvent influence is then on this latter species via hydrogen bond interactions. The correlation holds in pure water but not in pure organic solvents where, clearly, the proton must be transferred to the organic molecule.     

Multiway merge with constant delay in Concurrent Prolog

Multiway dynamic mergers with constant delay are an essential component of a parallel logic programming language. Previous attempts to defined efficient mergers have required complex optimising compilers and run-time support. This paper proposes a simple technique to implement mergers efficiently. The technique requires an additional data type and the definition of an operation on it. The operation allows multiple processes to access a stream without incurring the cost of searching for the end of stream. It is specified in Concurrent Prolog and is used to define multiple assignment variables using a monitor. The technique forms the basis for stream merging in Logix, a practical programming environment written in Flat Concurrent Prolog.     

Compiling OR-parallelism into AND-parallelism

This paper suggests a general method for compiling OR-parallelism into AND-parallelism. An interpreter for an AND/OR-parallel language written in the AND-parallel subset of the language induces a source-to-source transformation from the full language into the AND-parallel subset. This transformation can be identified and implemented as a special purpose compiler or applied using a general purpose partial evaluator. The method is demonstrated to compile a variant of Concurrent Prolog into an AND-parallel subset of the language called Flat Concurrent Prolog (FCP). It is also shown applicable to the compilation of OR-parallel Prolog to FCP. The transformation identified is simple and efficient. The performance of the method is discussed in the context of programming examples. These compare well with conventionally compiled Prolog programs.     

Amyloidogenic Properties of Peptides Derived from the VHL Tumor Suppressor Protein

The von Hippel-Lindau tumor suppressor protein (pVHL) is involved in maintaining cellular oxygen homeostasis through the regulated degradation of HIF-α. The intrinsically disordered nature of pVHL makes it prone to aggregation that impairs its function, and this is further aggravated in mutant versions of the protein, thus promoting tumor development. By using in silico analysis, we predicted six peptide fragments from pVHL to be amyloidogenic. This was verified for two of the peptides by biophysical approaches, which demonstrated self-assembly and formation of β-sheet-rich aggregates, which, under transmission electron microscopy, atomic force microscopy, and X-ray diffraction, displayed typical fibrillar amyloid characteristics. These motifs may serve as proxies for exploring the nature of pVHL aggregation.     

Solvent-Polymeric Membranes for Separation of Li+ From Other Alkali Metal and Alkaline Earth Ions

Lithium may be recovered from the Dead Sea brines by a process which combines membrane separation with ion-exchange. Solvent-polymeric membranes based on alkyl-arylphosphates cause selective permeation of lithium ions with Br⁻₃ as counter ions. Addition of the derivatives of neutral “crown” ethers did not improve their performance and an adverse effect, due to the decrease in the fluidity of the membrane system, was observed. Incorporation of ionizable “crown” ethers compatible with the system may, however, be advantageous; pH gradients could act as a driving force for transport of lithium in such systems. Membranes prepared with (2-ethylhexyl)-diphenyl phosphate (Santicizer 141) gave the best results from the point of view of selectivity of Li⁺ transport vs. Mg²⁺ and Ca²⁺. Maintenance of ca. 10⁻³ M concentrations of Br₂ in the end-brine solutions gives optimal membrane performance. No significant change in membrane permeability and selectivity occurred during six months of their operation. Lithium ions in the product solution of the membrane separation process may be further separated from the residual Mg²⁺ and Ca²⁺ ions and concentrated up to 1 M by ion exchange processes. Lithium may be precipitated from such solutions, free from alkaline earth ions, as Li₂CO₃.     

Robust real-time unusual event detection using multiple fixed-location monitors

We present a novel algorithm for detection of certain types of unusual events. The algorithm is based on multiple local monitors which collect low-level statistics. Each local monitor produces an alert if its current measurement is unusual, and these alerts are integrated to a final decision regarding the existence of an unusual event. Our algorithm satisfies a set of requirements that are critical for successful deployment of any large-scale surveillance system. In particular it requires a minimal setup (taking only a few minutes) and is fully automatic afterwards. Since it is not based on objects' tracks, it is robust and works well in crowded scenes where tracking-based algorithms are likely to fail. The algorithm is effective as soon as sufficient low-level observations representing the routine activity have been collected, which usually happens after a few minutes. Our algorithm runs in realtime. It was tested on a variety of real-life crowded scenes. A ground-truth was extracted for these scenes, with respect to which detection and false-alarm rates are reported.