Cohen-Macaulay permutation graphs

In this article, we characterize Cohen-Macaulay permutation graphs. In particular, we show that a permutation graph is Cohen-Macaulay if and only if it is well-covered and there exists a unique way of partitioning its vertex set into $r$ disjoint maximal cliques, where $r$ is the cardinality of a maximal independent set of the graph. We also provide some sufficient conditions for a comparability graph to be a uniquely partially orderable (UPO) graph.Comment: 8 pages, 2 figures; comments are welcom

Thin Surface Layer of Plasma Treated Polyethylene

This paper reports on the effect of argon plasma on the high density polyethylene surface. The aim is to alter the surface in a manner and scale resulting in a stronger metal/polymer valence. The specimens are exposed to the direct current discharge, the irradiation time and power being variables. Electron paramagnetic resonance and X-ray photoelectron spectroscopy (EPR and XPS, respectively) are employed to determine the plasma effect. The surface wettability is studied by goniometry. The plasma treatment leads to radical generation and activation of such agents as oxygen, thus the surface wettability is significantly increased. The evolution ofthe treated surface in different media is studied. The influence of an increased oxygen concentration and the storage medium on the concentration gradient within the surface monolayers is proved. The EPR data show a gradual and very slow decrease in the number of radicals present on the treated surface after 2000 h. Also evidence is given for partial dissolution of the treated surface in water.Представлены результаты изучения влияния плазмы аргона на поверхность полиэтилена высокой плотности. Целью исследования является изменение поверхности таким образом, чтобы увеличить валентность ме­талла/полимера. Образцы подвергали воз­действию разряда постоянного тока, при этом время воздействия и мощность являлись переменными величинами. Для опре­деления влияния плазмы использовали электронный парамагнитный резонанс (ЭПР) и фотоэлектронную рентгеновскую спектроскопию. Смачиваемость поверхнос­ти изучали с использованием гониометрии. Плазменная обработка ведет к образованию радикалов и активизации таких реагентов, как кислород и таким образом, значительно увеличивается смачиваемость поверхности. Исследована эволюция обработанной по­верхности в различных средах. Приведено подтверждение влияния повышенной кон­центрации кислорода и среды на градиент концентрации в поверхностных монослоях. Данные ЭПР свидетельствуют о постепен­ном и очень медленном уменьшении коли­чества радикалов на обработанной поверхности после 2000 ч. Приведены также дан­ные о частичном растворении обработанной поверхности в воде

Conformational transition of the Ixodes ricinus salivary serpin Iripin 4

Iripin 4, one of the many salivary serpins from Ixodes ricinus ticks with an as yet unexplained function, crystallized in two different structural conformations, namely the native partially relaxed state and the cleaved serpin. The native structure was solved at a resolution of 2.3 amp; 8197; and the structure of the cleaved conformation was solved at 2.0 amp; 8197; resolution. Furthermore, structural changes were observed when the reactive centre loop transitioned from the native conformation to the cleaved conformation. In addition to this finding, it was confirmed that Glu341 represents a primary substrate recognition site for the inhibitory mechanism. The presence of glutamate instead of the typical arginine in the P1 recognition site of all structurally characterized I. ricinus serpins PDB entries 7b2t, 7pmu and 7ahp , except for the tyrosine in the P1 site of Iripin 2 formerly IRS 2; PDB entry 3nda , would explain the absence of inhibition of the tested proteases that cleave their substrate after arginine. Further research on Iripin 4 should focus on functional analysis of this interesting serpi

Nanowire antennas embedding single quantum dots: towards the emission of indistinguishable photons

Nanowire antennas embedding a single semiconductor quantum dot (QD) represent an appealing solid-state platform for photonic quantum technologies. We present recent work aiming at generating indistinguishable photons with this system. We first investigate decoherence channels that spectrally broaden the QD emission, and discuss in particular the impact of nanowire thermal vibrations. We also develop nanowire optical nanocavities, which provide a large acceleration of the QD spontaneous emission, so that it becomes less sensitive to environmental noises

Tick Salivary Sialostatin L Represses the Initiation of Immune Responses by Targeting IRF4-Dependent Transcription in Murine Mast Cells

Pathogenesis and treatment of chronic pulmonary disease