Controlling the Deintercalation in Hydrogenated Nitrile Rubber (HNBR)/Organo‐Montmorillonite Nanocomposites by Curing with Peroxide

Summary: The effect of peroxide vulcanization on organoclay dispersion in hydrogenated nitrile rubber (HNBR)/organo‐montmorillonite (organo‐MMT) nanocomposites was investigated. Three types of organoclays were tested, one containing a primary amine and two bearing quaternary intercalants. In contrast to sulfur vulcanization, which in combination with primary amine intercalants produced a confined/deintercalated clay structure, the peroxide curing yielded well‐ordered intercalated nanocomposites. The tensile mechanical performance and oxygen permeability of the HNBR nanocomposites were determined.

Oxygen permeability coefficient ratio for the different HNBR films tested at 0 and 60% relative humidity (i.e., dry and wet conditions, respectively).     

In vivo quantification and pharmacokinetic studies of cotinine in mice after smoke exposure by LC–MS/MS

A sensitive analytical method was developed and validated for the quantification of cotinine in mouse plasma after exposure to smoke of 0.5, 1.0, and 1.5 commercially available cigarettes, using liquid chromatography tandem mass spectrometry. The method was validated over a linear concentration range of 0.075–20.0 ng/mL with the R² value being higher than 0.99. Both the precision (coefficient of variation; %) and accuracy (relative error; %) were within acceptable criteria of <15%. The lower limit of quantification (LLOQ) for cotinine was 0.075 ng/mL with sufficient specificity, accuracy, and precision. Following exposure to 0.5, 1.0, and 1.5 cigarette smoke, it was observed that the AUC and the C_max increased linearly as the doses increased. The pharmacokinetics of cotinine was found linear for the range of 0.5–1.5 commercial cigarette smoke. The quantification of the concentration of cotinine in mouse plasma after smoke exposure will facilitate future behavioral and toxicological experiments in animals and may prove useful in predicting cotinine levels in humans during smoking.     

Photophysics of 9,9-Dimethylacridan-Substituted Phenylstyrylpyrimidines Exhibiting Long-Lived Intramolecular Charge-Transfer Fluorescence and Aggregation-Induced Emission Characteristics

Six pyrimidine-based push–pull systems substituted at positions C2 and C4/6 with phenylacridan and styryl moieties, employing methoxy or N,N-diphenylamino donors, have been designed and synthesized through cross-coupling and Knoevenagel reactions. X-ray analysis confirmed that the molecular structure featured the acridan moiety arranged perpendicularly to the residual π system. Photophysical studies revealed significant differences between the methoxy and N,N-diphenylamino chromophores. Solvatochromic studies revealed that the methoxy derivatives showed dual emission in polar solvents. Time-resolved spectroscopy revealed that the higher energy band involved very fast (<80 ps) fluorescence, whereas the lower energy one included long components (≈30 ns) due to long-lived intramolecular charge-transfer fluorescence. In contrast to N,N-diphenylamino chromophores, the methoxy derivatives also showed aggregation-induced emission in mixtures of THF/water, as well as dual emission in thin films, covering almost the whole visible spectrum with corresponding chromaticity coordinates not far from that of pure white light. These properties render the methoxy derivatives as very promising organic materials for white organic light-emitting diodes.     

Validation and application of a protocol for the extraction and quantitative analysis of sphingomyelin in erythrocyte membranes of patients with non-alcoholic fatty liver disease

JPC – Journal of Planar Chromatography – Modern TLC - A set of constituents of the erythrocyte membrane lipidome has been proposed to serve as biomarkers for liver disease and acute...     

A discrete event simulation model in the case of managing a software project

The design and development of large-scale software projects is a complex endeavor, often facing problems like cost and schedule overruns as well as low quality. Over the last years the management of software development projects has been recognized as the cornerstone point of seeking improvement and solutions. Simulation modeling of the software project process is gaining interest among academics and practitioners, as a method to tackle the complex questions with which relevant enterprises are confronted. It offers support on several issues, such as defining software product development strategies, decision-making regarding process improvement and training, in a time span ranging from a short portion of the life cycle to long term product evolution, with organization-wide implications. The aim of this work is to implement a model simulating a core part of a software project process, enabling the estimation of several project development details such as delivery times and quality metrics. The purpose of the model is to assist project managers in control and monitoring, but also in identifying the best planning alternatives. The model scope covers a portion of the life cycle of an incremental software development venture.     

Evolution of primordial magnetic fields

A new mechanism for the evolution of primordial magnetic fields is described and analysed. The field evolution is followed from the time of its creation until the epoch of structure and galaxy formation. The mechanism takes into account the turbulent behaviour of the early universe plasma, whose properties determine strongly the evolution of the field configuration. A number of other related issues such as the case of an electroweak plasma are also considered. Finally, as an example, the mechanism is applied to specific models.     

Graphene‐Based Inverted Planar Perovskite Solar Cells: Advancements,Fundamental Challenges,and Prospects

Metal halide based perovskite solar cells (PSCs) are considered among the most promising photovoltaic technologies, and already present certified efficiencies that surpass 22 %. The high performance and low fabrication cost make this technology competitive with that of state‐of‐the‐art thin‐film photovoltaics. However, PSCs present some striking disadvantages that hinder their commercialization, including short operational lifetimes, high toxicity, and hysteresis effects, which lower both the performance and long‐term stability of the devices. Herein, work conducted within the last two years is summarized with regard to addressing the challenges of low‐temperature‐processed planar inverted PSCs composed of graphene‐based materials. In addition, critical challenges and the prospects of this field are discussed and some prospects for future research directions are proposed.     

Study of poly(N,N-dimethylacrylamide)/CdS nanocomposite organic/inorganic gels

CdS nanoparticles have been synthesized and stabilized in poly(N,N-dimethylacrylamide) hydrogels. The properties of the composite material have been characterized by UV-vis spectroscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and steady-state and time-resolved luminescence spectroscopy. This material can be obtained in three different states: swollen, shrunk, and freeze-dried. The swollen and the freeze-dried states correspond to a nanocomposite organic/inorganic (wet or dry) gel containing CdS nanoparticles of approximately 50 nm diameter while the shrunk state is a two-phase system containing CdS crystals, which precipitate forming interesting geometrical shapes.     

Chemistry of organophosphonate scale growth inhibitors: two-dimensional, layered polymeric networks in the structure of tetrasodium 2-hydroxyethyl-amino-bis(methylenephosphonate)

Aminomethylene phosphonates are important scale inhibitors applied in diverse areas of technology. This study adds to the existing body of information on this subject and reports the crystal and molecular structures of tetrasodium 2-hydroxyethylamino-bis(methylene-phosphonate) decahydrate ([Na₄(HOCH₂CH₂N(CH₂PO₃)₂)]·10H₂O, 1). The crystal structure of 1 could be described as two-dimensional polymeric layered structure hydrogen bonded into a 3D supramolecular polymeric network. The structure of the tetraanion consists of a “three-arm” backbone stemming from the N atom. Two “arms” are deprotonated methylene phosphonate (-CH₂PO₃²⁻) moieties and the third is a hydroxyethyl (-CH₂CH₂OH) moiety. One Na cation forms an intramolecular complex with two oxygens from separate phosphonate groups, a hydroxyl oxygen, the nitrogen and two lattice water molecules. The position of this Na cation points to a possible coordination site for Ca in a proposed Ca-HEABMP complex (HEABMP=2-hydroxyethylamino-bis(methylene-phosphonate).