Is There a Negative Thermal Expansion in Supported Metal Nanoparticles? An In-Situ X-ray Absorption Study Coupled with Neural Network Analysis

Interactions with their support, adsorbates and unique structural motifs are responsible for the many intriguing properties and potential applications of supported metal nanoparticles (NPs). At the same time, they complicate the interpretation of experimental data. In fact, the methods and approaches that work well for the ex situ analysis of bulk materials may be inaccurate or introduce artifacts in the in situ analysis of nanomaterials. Here we revisit the controversial topic of negative thermal expansion and anomalies in the Debye temperature reported for oxide-supported metal NPs. In situ X-ray absorption experimental data collected for Pt NPs in ultrahigh vacuum and an advanced data analysis approach based on an artificial neural network demonstrate that Pt NPs do not exhibit intrinsic negative thermal expansion. Similarly as for bulk materials, in the absence of adsorbates the bond lengths in metal NPs increase with temperature. The previously reported anomalies in particle size-dependent Debye temperatures can also be linked to the artifacts in the interpretation of conventional X-ray absorption data of disordered materials such as NPs

The Survivability of Symmetrical Hierarchical Networks with Radial Reserve

In this paper we shall consider the Symmetrical Hierarchical Network (SHN) and show that SHN possesses poor properties of survivability. There are several methods for raising the survivability of SHN. Here we consider the effectiveness of radial reserve to raise the survivability of SHN taking account of destruction of the main radial edges, and radial reserve

Quantum gravitational optics: the induced phase

The geometrical approximation of the extended Maxwell equation in curved spacetime incorporating interactions induced by the vacuum polarization effects is considered. Taking into account these QED interactions and employing the analogy between eikonal equation in geometrical optics and Hamilton-Jacobi equation for the particle motion, we study the phase structure of the modified theory. There is a complicated, local induced phase which is believed to be responsible for the modification of the classical picture of light ray. The main features of QGO could be obtained through the study of this induced phase. We discuss initial principles in conventional and modified geometrical optics and compare the results.Comment: 10 pages, REVTex forma

A case report of orbital hydatid cyst in Shahrekord

زمینه و هدف: بیماری کیست هیداتید یکی از مهم ترین و شایع ترین بیماری های مشترک انسان و دام است که ناشی از ابتلای انسان به مرحله لاروی انگل اکی نوکوکوس گرانولوزوس (Echinococus granulosus) می باشد. این بیماری با طیف وسیعی از علا یم و یافته های بالینی مشخص می شود که عمدتاً به دلیل درگیر شدن و ایجاد کیست در ارگان های مختلف از جمله کبد، ریه، مغز، طحال و سایر قسمت های بدن می باشد. در موارد کمی نیز کیست در داخل چشم تشکیل شده که کیست هیداتید اربیتال نامیده می شود. با توجه به اینکه این بیماری در استان چهارمحال و بختیاری نسبتاً فراوان است، هدف از گزارش این مورد آشنایی پزشکان با علائم بالینی همراه کیست هیداتید اربیتال می باشد. گزارش مورد: بیمار پسری 11ساله ای است که با پروپتوزیس بدون درد و بدون ضربان مراجعه کرد. در سی تی اسکن ضایعه کیستیک رتروبولبار گزارش شد. بیمار با تشخیص کیست هیداتید بستری و کیست با روش جراحی خارج شد. در آزمایشات پاتولوژی نیز تشخیص کیست هیداتید تأیید گردید. در این بیمار نتیجه درمان رضایت بخش بود و بعد از درمان علایم کاملا بهبود یافت. نتیجه گیری: با توجه به وجود بیماری کیست هیداتید در منطقه، چشم پزشکان باید کیست هیداتید را در تشخیص افتراقی پروپتوز یک طرفه قرار دهند

Site-dependent charge transfer at the Pt(111)-ZnPc interface and the effect of iodine

The electronic structure of ZnPc, from sub-monolayers to thick films, on bare and iodated Pt(111) is studied by means of X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and scanning tunneling microscopy (STM). Our results suggest that at low coverage ZnPc lies almost parallel to the Pt(111) substrate, in a non-planar configuration induced by Zn-Pt attraction, leading to an inhomogeneous charge distribution within the molecule and charge transfer to the molecule. ZnPc does not form a complete monolayer on the Pt surface, due to a surface-mediated intermolecular repulsion. At higher coverage ZnPc adopts a tilted geometry, due to a reduced molecule-substrate interaction. Our photoemission results illustrate that ZnPc is practically decoupled from Pt, already from the second layer. Pre-deposition of iodine on Pt hinders the Zn-Pt attraction, leading to a non-distorted first layer ZnPc in contact with Pt(111)-I $\left(\sqrt{3}\times\sqrt{3}\right)$ or Pt(111)-I $\left(\sqrt{7}\times\sqrt{7}\right)$, and a more homogeneous charge distribution and charge transfer at the interface. On increased ZnPc thickness iodine is dissolved in the organic film where it acts as an electron acceptor dopant.Comment: 12 pages, 9 figure

Nematic and Polar order in Active Filament Solutions

Using a microscopic model of interacting polar biofilaments and motor proteins, we characterize the phase diagram of both homogeneous and inhomogeneous states in terms of experimental parameters. The polarity of motor clusters is key in determining the organization of the filaments in homogeneous isotropic, polarized and nematic states, while motor-induced bundling yields spatially inhomogeneous structures.Comment: 4 pages. 3 figure

Three new infrared bands of the He-OCS complex

Three new infrared bands of the weakly-bound He-OCS complex are studied, using tunable lasers to probe a pulsed supersonic slit jet expansion. They correspond to the (0400) <-- (0000), (1001)<-- (0000), and (0401) <-- (0000) transitions of OCS at 2105, 2918, and 2937 cm-1, respectively. The latter band is about 7900 times weaker than the previously studied OCS nu1 fundamental. Vibrational shifts relative to the free OCS monomer are found to be additive. Since carbonyl sulfide has previously been shown to be a valuable probe of superfluid quantum solvation effects in helium clusters and droplets, the present results could be useful for future studies of vibrational effects in such systems.Comment: 16 pages, 1 figure, 4 table