HUHU: The Hebrew University Hebrew Understander

This paper describes a system of morphological and syntactic parsing of the Hebrew language. It contains an extensive morphological analyzer and an augmented transition network-based syntactic parser. The system has been written in the YLISP dialect of Lisp. A parallel effort for English (different grammars that use the same parsing software) has also been developed.     

On Fitting Empirical Data under Interval Error

This paper is devoted to the problem of fitting input-output data by a modeling function, linear in its parameters, in the presence of interval-bounded errors in output variable. A method for outlier detection is proposed. Another issue under consideration is the comparative simulation study of the well-known statistical point estimates (least squares, maximum likelihood) and point estimates calculated as the center of interval hull of uncertainty set. The results of the study allow us to draw the conclusion that non-statistical interval based estimation is a competitive alternative to statistical estimation in some cases.     

An easy way to Pd–Zn nanoalloy with defined composition from a heterobimetallic Pd(μ–OOCMe)4Zn(OH2) complex as evidenced by XAFS and XRD

The heterobimetallic lantern complex Pd(μ-OOCMe)₄Zn(OH₂) was found to be readily reduced with H₂ under fairly mild conditions (150–250 °C, 5–10% H₂/He) both in the carbon-supported and crystalline states to afford a Pd–Zn nanoalloy as evidenced by the ICP elemental analysis, EXAFS, XANES and XRD data.      

Formation Energies of Antiphase Boundaries in GaAs and GaP: An ab Initio Study

Electronic and structural properties of antiphase boundaries in group III-V semiconductor compounds have been receiving increased attention due to the potential to integration of optically-active III-V heterostructures on silicon or germanium substrates. The formation energies of {110}, {111}, {112}, and {113} antiphase boundaries in GaAs and GaP were studied theoretically using a full-potential linearized augmented plane-wave density-functional approach. Results of the study reveal that the stoichiometric {110} boundaries are the most energetically favorable in both compounds. The specific formation energy γ of the remaining antiphase boundaries increases in the order of γ_{113} ≈ γ_{112} < γ_{111}, which suggests {113} and {112} as possible planes for faceting and annihilation of antiphase boundaries in GaAs and GaP.     

Electrorheological behavior of low filled suspensions of highly anisometric montmorillonite particles

The electrorheological (ER) behavior of modified montmorillonite (MMT) suspensions in polydimethylsiloxane is studied. As established by rotational viscometry, the samples with a dispersed phase concentration from 1 to 8 wt % reveal viscous Newtonian behavior and dramatically change their properties to elastic when electric field is applied. The rheological characteristics of the suspensions over 0–7 kV mm⁻¹ range of electric field strengths are also studied. Novel X-ray diffraction method is developed to evaluate the suspension of the filler in a siloxane medium and to calculate the degree of its exfoliation. The dependence of exfoliation degree, dielectric, and ER characteristics on the type of modifier in the MMT structure is considered. Based on the obtained data, a new model of system behavior with the various types of fillers is proposed and the prospects of utilizing MMT as a filler for ER fluids are demonstrated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47678.     

Graphene oxide conversion into controllably carboxylated graphene layers via photoreduction process in the inert atmosphere

Abstract

The one-step method for graphene oxide (GO) simultaneous reduction and carboxylation via ultraviolet irradiation in the inert atmosphere has been reported. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) data revealed that the proposed approach allows to obtain reduced graphene oxide (rGO) films, containing up to 10 at.% of carboxyl groups. The carboxyl groups concentration can be tuned within the range of 3 to 10 at.% by controlling the oxidation degree of the irradiated GO via the preliminary low-temperature air heating. Furthermore, no carboxylation effect is observed in the case of irradiation of the completely reduced GO films. This coincides with our previous results, validating the proposed model of GO carboxylation based on photoinduced conversion of basal-plane hydroxyl groups and ketones into carboxyl ones. Despite a different degree of carboxylation, all the obtained samples demonstrate almost complete elimination of basal plane groups and restoration of the graphene flakes aromatic structure. This fact is emphasized by the sheet resistance measurements, demonstrating that the obtained C-xy graphene exhibits high electrical conductivity. As a net result, the material obtained by the presented method shows promising applications in the manufacturing of biosensor transducers owing to both its conductive nature and presence of carboxyl groups, playing the role of the anchoring points for biomolecules.     

A low-wavenumber-extended confocal Raman microscope with very high laser excitation line discrimination

We describe the simple modification of a confocal Raman imaging microscope to incorporate two ultra-narrow holographic notch filters. The modified microscope rejects the laser excitation line (Rayleigh peak) by a discrimination factor of ～10(11) and allows simultaneous measurements of Stokes/anti-Stokes Raman shifts as close as ～10/20 cm(-1) to the Rayleigh line. The extremely high rejection ratio of the Rayleigh peak results in its intensity becoming comparable to typical Raman scattering signals. This is essential for micro-Raman spectroscopy and imaging in the low-wavenumber region. We illustrate the resulting performance with measurements on silicon/silica, sapphire, sulfur, L-cystine, as well as on single-walled carbon nanotubes (SWNTs). We find that both aggregated (bulk) and individual (deposited on substrate) SWNTs demonstrate strong and broad characteristic Raman features below ～100 cm(-1)-in a region which has remained essentially unexplored in measurements of bulk SWNT samples and which has so far been inaccessible for Raman spectroscopy of individual SWNTs.     

Synergistic Use of Pyridine and Selenophene in a Diketopyrrolopyrrole‐Based Conjugated Polymer Enhances the Electron Mobility in Organic Transistors

To achieve semiconducting materials with high electron mobility in organic field‐effect transistors (OFETs), low‐lying energy levels (the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO)) and favorable molecular packing and ordering are two crucial factors. Here, it is reported that the incorporation of pyridine and selenophene into the backbone of a diketopyrrolopyrrole (DPP)‐based copolymer produces a high‐electron‐mobility semiconductor, PDPPy‐Se. Compared with analogous polymers based on other DPP derivatives and selenophene, PDPPy‐Se features a lower LUMO that can decrease the electron transfer barrier for more effective electron injection, and simultaneously a lower HOMO that, however, can increase the hole transfer barrier to suppress the hole injection. Combined with thermal annealing at 240 °C for thin film morphology optimization to achieve large‐scale crystallite domains with tight molecular packing for effective charge transport along the conducting channel, OFET devices fabricated with PDPPy‐Se exhibit an n‐type‐dominant performance with an electron mobility (μ_e) as high as 2.22 cm² V^?1 s^?1 and a hole/electron mobility ratio (μ_h/μ_e) of 0.26. Overall, this study demonstrates a simple yet effective approach to boost the electron mobility in organic transistors by synergistic use of pyridine and selenophene in the backbone of a DPP‐based copolymer.