Lipid Dynamics in Diisobutylene-Maleic Acid (DIBMA) Lipid Particles in Presence of Sensory Rhodopsin II

Amphiphilic diisobutylene/maleic acid (DIBMA) copolymers extract lipid-encased membrane proteins from lipid bilayers in a detergent-free manner, yielding nanosized, discoidal DIBMA lipid particles (DIBMALPs). Depending on the DIBMA/lipid ratio, the size of DIBMALPs can be broadly varied which makes them suitable for the incorporation of proteins of different sizes. Here, we examine the influence of the DIBMALP sizes and the presence of protein on the dynamics of encased lipids. As shown by a set of biophysical methods, the stability of DIBMALPs remains unaffected at different DIBMA/lipid ratios. Coarse-grained molecular dynamics simulations confirm the formation of viable DIBMALPs with an overall size of up to 35 nm. Electron paramagnetic resonance spectroscopy of nitroxides located at the 5th, 12th or 16th carbon atom positions in phosphatidylcholine-based spin labels reveals that the dynamics of enclosed lipids are not altered by the DIBMALP size. The presence of the membrane protein sensory rhodopsin II from Natronomonas pharaonis (NpSRII) results in a slight increase in the lipid dynamics compared to empty DIBMALPs. The light-induced photocycle shows full functionality of DIBMALPs-embedded NpSRII and a significant effect of the protein-to-lipid ratio during preparation on the NpSRII dynamics. This study indicates a possible expansion of the applicability of the DIBMALP technology on studies of membrane protein–protein interaction and oligomerization in a constraining environment.     

Magnetic Core–Shell Molecularly Imprinted Nano-Conjugates for Extraction of Antazoline and Hydroxyantazoline from Human Plasma—Material Characterization,Theoretical Analysis and Pharmacokinetics

The aim of this study was to develop magnetic molecularly imprinted nano-conjugate sorbent for effective dispersive solid phase extraction of antazoline (ANT) and its metabolite, hydroxyantazoline (ANT-OH) in analytical method employing liquid chromatography coupled with mass spectrometry method. The core–shell material was characterized in terms of adsorption properties, morphology and structure. The heterogeneous population of adsorption sites towards ANT-OH was characterized by two K_d and two B_max values: K_d (1) = 0.319 µg L⁻¹ and B_max (1) = 0.240 μg g⁻¹, and K_d (2) = 34.6 µg L⁻¹ and B_max (2) = 5.82 μg g⁻¹. The elemental composition of magnetic sorbent was as follows: 17.55, 37.33, 9.14, 34.94 wt% for Si, C, Fe and O, respectively. The extraction protocol was optimized, and the obtained results were explained using theoretical analysis. Finally, the analytical method was validated prior to application to pharmacokinetic study in which the ANT was administrated intravenously to three healthy volunteers. The results prove that the novel sorbent could be useful in extraction of ANT and ANT-OH from human plasma and that the analytical strategy could be a versatile tool to explain a potential and pharmacological activity of ANT and ANT-OH.     

Increasing validity through replication: an illustrative TDD case

Software Quality Journal - Software engineering (SE) experiments suffer from threats to validity that may impact their results. Replication allows researchers building on top of previous...     

Pyrolysis of Complexes of Metallosulphophthalocyanines with Chitosan for Obtaining Graphite-Like Structures

Journal of Inorganic and Organometallic Polymers and Materials - The pyrolysis of chitosan and its polymeric complexes with metal phthalocyanines was studied by thermochemical and spectral methods....     

Effect of a nisin-producing lactococcal starter on the late blowing defect of cheese caused by Clostridium tyrobutyricum

Clostridium tyrobutyricum causes swelling, cracks and off-flavours of cheeses (late blowing defect, LBD) due to butyric acid fermentation. To control this spoilage bacterium, we investigated the use of nisinogenic Lactococcus lactis subsp. lactis INIA 415 as starter in cheeses contaminated with C. tyrobutyricum spores. Control cheese made with spores showed LBD after 14 days of ripening. However, in cheese made with the bacteriocin producer and spores, in which (unlike control cheese) bacteriocin activity was detected throughout ripening, LBD occurred after 21 days. At this stage, level of lactic acid was 1.22-fold higher (P < 0.01) and concentrations of propionic and butyric acids were 2.15- and 2.32-fold, respectively, lower (P < 0.01) in cheese made with the nisin producer than in control cheese, according to the less pronounced spoilage symptoms showed by the former cheese. The bacteriocin producer delayed the appearance of LBD, although it cannot arrest completely C. tyrobutyricum growth.     

A psychological contract perspective of vertical and distributed leadership in project-based organizations

The primary purpose of this study is to examine the relationship between two leadership styles (vertical and distributed), conceptualized through types of decisions made (strategic and operational/tactical), and the state of psychological contract (fulfillment/breach) at three different levels of the organizational hierarchy in project-based organizations. The explorative analysis of eight organizations from India and Australia demonstrates the prevalence of distributed leadership: operational and technical decisions are usually entrusted to the project team and project managers, while strategic decisions are made by senior management. The study suggests that three factors facilitate a specific leadership style (vertical or distributed): organizational culture, knowledge sharing and project management practices, which in turn impact the state of psychological contract (fulfillment/breach). A flexible, collaborative organizational culture supports knowledge sharing and the adoption of agile methods, enabling distributed leadership and leading to psychological contract fulfillment.     

Carbon nanomaterials based on plant biopolymers as radionuclides sorbent

Abstract

The technogenic human activities associated with the operation of nuclear power facilities lead to the contamination of natural water bodies and soils with radioactive substances, including heavy radionuclides, such as uranium and thorium. Purification of natural water bodies is a pressing environmental issue. A study of the adsorption capacity for heavy U²³⁸ and Th²³² radionuclides by the samples of new carbon nanomaterials was conducted. Nanocarbon materials was synthesized based on vegetal polymers, such as technical lignin, starch and from lignocellulosic material—the bark. It was established that the investigated samples have different sorption indices in relation to radionuclides, which is determined by their chemical composition, as well as by the surface-capillary properties of carbonized materials. It is shown that the content of mobile and fixed forms of radionuclides on the investigated sorbents are significantly different. High sorption capacity of the carbonated lignin sample with respect to uranium are shown. A sample of nanocarbon materials synthesized based on the lignocellulosic complex of the bark exhibits high sorption properties in relation to thorium. The possibility of using the carbonic nanomaterial as the sorbents of radionuclides is shown.