Preparation and characterization of thermostable chiral extended polyamides bearing N‐phthaloyl‐L‐leucine pendent architectures in green media

Ionic liquids (ILs) are often well‐known benign solvents capable of replacing conventional organic solvents, and they have become attractive solvents for many chemical reactions. Aromatic polyamides (PAs) have received particular interest in past years because of their high thermal and chemical resistance and their potential as high‐performance materials for different applications. In this investigation, the preparation of extended PAs derived from 5‐aminoisophthalic acid containing chiral pendent linkage (N‐phthaloyl‐L ‐leucine) with various aromatic diamines was studied. The bulky monomer 5‐(4‐methyl‐2‐phthalimidylpentanoylamino)isophthalic acid was prepared in three steps. Direct polyamidation of this monomer with several commercially available diamines in the presence of IL (1,3‐dipropylimidazolium bromide) and triphenyl phosphite gave novel PAs in good yields and inherent viscosities in the range of 0.38–0.55 dL g^?1. Because of the existence of amino acid in this architect, the resulting polymers are optically active. All of these PAs showed good solubility and readily dissolved in many organic solvents. Characterization of all the products was performed by FTIR, specific rotation, and representative ones by ¹H NMR, elemental analysis, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). TGA exhibited that two elite polymers were stable, with 10% weight loss recorded above 410 and 430°C in the nitrogen atmosphere. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Understanding the Role of LFA-1 in Leukocyte Adhesion Deficiency Type I (LAD I): Moving towards Inflammation?

LFA-1 (Lymphocyte function-associated antigen-1) is a heterodimeric integrin (CD11a/CD18) present on the surface of all leukocytes; it is essential for leukocyte recruitment to the site of tissue inflammation, but also for other immunological processes such as T cell activation and formation of the immunological synapse. Absent or dysfunctional expression of LFA-1, caused by mutations in the ITGB2 (integrin subunit beta 2) gene, results in a rare immunodeficiency syndrome known as Leukocyte adhesion deficiency type I (LAD I). Patients suffering from severe LAD I present with recurrent infections of the skin and mucosa, as well as inflammatory symptoms complicating the clinical course of the disease before and after allogeneic hematopoietic stem cell transplantation (alloHSCT); alloHSCT is currently the only established curative treatment option. With this review, we aim to provide an overview of the intrinsic role of inflammation in LAD I.     

Heterogeneities in Cell Cycle Checkpoint Activation Following Doxorubicin Treatment Reveal Targetable Vulnerabilities in TP53 Mutated Ultra High-Risk Neuroblastoma Cell Lines

Most chemotherapeutics target DNA integrity and thereby trigger tumour cell death through activation of DNA damage responses that are tightly coupled to the cell cycle. Disturbances in cell cycle regulation can therefore lead to treatment resistance. Here, a comprehensive analysis of cell cycle checkpoint activation following doxorubicin (doxo) treatment was performed using flow cytometry, immunofluorescence and live-cell imaging in a panel of TP53 mutated ultra high-risk neuroblastoma (NB) cell lines, SK-N-DZ, Kelly, SK-N-AS, SK-N-FI, and BE(2)-C. Following treatment, a dose-dependent accumulation in either S- and/or G2/M-phase was observed. This coincided with a heterogeneous increase of cell cycle checkpoint proteins, i.e., phos-ATM, phos-CHK1, phos-CHK2, Wee1, p21^Cip1/Waf1, and p27^Kip among the cell lines. Combination treatment with doxo and a small-molecule inhibitor of ATM showed a delay in regrowth in SK-N-DZ, of CHK1 in BE(2)-C, of Wee1 in SK-N-FI and BE(2)-C, and of p21 in Kelly and BE(2)-C. Further investigation revealed, in all tested cell lines, a subset of cells arrested in mitosis, indicating independence on the intra-S- and/or G2/M-checkpoints. Taken together, we mapped distinct cell cycle checkpoints in ultra high-risk NB cell lines and identified checkpoint dependent and independent druggable targets.     

4- and 6-GS/s 4-bit frequency-translating hybrid ADCs in 90-nm CMOS

Two frequency-translating hybrid analog-to-digital converters (FTH-ADCs) are implemented using building blocks that are designed and fabricated in a 90-nm CMOS technology. These blocks include a mixer, a filter, and an ADC that are cascaded to build each analog processing path of the FTH-ADC. The mixer-filter path is designed with sufficient linearity and signal-to-noise-and-distortion ratio (SNDR) to accommodate for the desired resolution of the path ADC. A 4-bit flash ADC structure is used in each path. This path has a signal bandwidth of 0.5 GHz and frequency-translates the input signal into baseband and digitizes it with the sample rate of 2 GHz. Multiple such mixer-filter-ADC paths are then combined together with proper mixing frequencies in order to implement two- and three-channel ADC systems. The two- and three-channel systems have overall input bandwidths of 2 and 3 GHz and effective conversion rates of 4 and 6 GS/s, respectively, while maintaining their single-path resolution across their entire input bandwidths. The implemented architecture provides an extendible solution to improve the speed of ADCs by incorporating them in an FTH-ADC architecture.     

Investigations of Human and Organizational Factors in hazardous vapor accidents

This paper presents a model to assess the contribution of Human and Organizational Factor (HOF) to accidents. The proposed model is made up of two phases. The first phase is the qualitative analysis of HOF responsible for accidents, which utilizes Human Factors Analysis and Classification System (HFACS) to seek out latent HOFs. The hierarchy of HOFs identified in the first phase provides inputs for the analysis in the second phase, which is a quantitative analysis using Bayesian Network (BN). BN enhances the ability of HFACS by allowing investigators or domain experts to measure the degree of relationships among the HOFs. In order to estimate the conditional probabilities of BN, fuzzy analytical hierarchy process and decomposition method are applied in the model. Case studies show that the model is capable of seeking out critical latent human and organizational errors and carrying out quantitative analysis of accidents. Thereafter, corresponding safety prevention measures are derived.     

Simulation of early-stage clustering in ternary metal alloys using the phase-field crystal method

Phase-field crystal methodology is applied, for the first time, to study the effect of alloy composition on the clustering behavior of a quenched/aged supersaturated ternary Al alloy system. An analysis of the work of formation is adapted from a methodology developed in Fallah et al. to describe the dislocation-mediated nucleation and growth mechanisms of early clusters in binary alloys [Phys Rev B 2012;86:134112]. Consistent with the experiments, we demonstrate that the addition of Mg to an Al–1.1Cu alloy increases the nucleation rate of clusters in the quenched/aged state by increasing the effective driving force for nucleation, enhancing the dislocation stress relaxation and decreasing the surface energy associated with the Cu-rich co-clusters of Cu–Mg. Furthermore, we show that it is thermodynamically favorable for small subcritical clusters to have higher affinity for Mg than larger post-critical Cu-rich clusters, particularly depicting a two-stage clustering phenomenon.     

Atomistic investigation of clustering phenomenon in the Al–Cu system: Three-dimensional phase-field crystal simulation and HRTEM/HRSTEM characterization

Early-stage clustering in quenched/aged supersaturated Al–Cu alloys is simulated and characterized at the atomic scale to study the structural and compositional evolution of clusters. A three-dimensional analysis of the nucleation and growth mechanisms of early clusters in binary alloys is built upon a phase-field crystal (PFC) methodology previously developed in two dimensions by Fallah et al. [Phys. Rev. B. 86, 134112 (2012)]. The dislocation-mediated nucleation of clusters, reproduced in three dimensions, is compared against new results of atomistic characterization using high-resolution transmission electron microscopy (HRTEM) and high-resolution scanning transmission electron microscopy (HRSTEM). Consistent with the simulation results, analysis of HRTEM micrographs reveals the association of quenched-in dislocations with the early clusters. Moreover, the PFC model and HRSTEM observations show remarkable agreement on the non-equilibrium evolution of composition within the early clusters as well as their preferred growth orientation and spherical-to-ellipsoidal morphological transition.     

Effect of dopant concentration and particle size on fluorescence properties of Y2O3:Eu3+ derived in presence of NIPAM/AAc copolymer

Y₂O₃:Eu³⁺ nano phosphors (about 65 nm in size) were prepared via co-precipitation method by using co-polymer NIPAM/AAc as a template with narrow size distribution. The aim of the paper is to indicate the co-polymer influence on size and luminescence characteristics of nano phosphors. In this respect, phase content and morphology were characterized by X-ray diffraction and transmission electron microscopy. All the powders were well crystallized and the particles were clearly spherical with good dispersibility. Luminescence measurements were used to investigate the role of precursor in powders and the utmost luminescence intensity was observed at 4 mol% of Eu³⁺ while the quenching concentration of Eu³⁺ ions has occurred at 5 mol%.