Holistic Analysis of the Tribological Interfaces of an Axial Piston Pump – Focusing on the Pump Efficiency

Research work performed on an axial piston pump is shown in a holistic manner, analyzing each lubricating interface by linking their gap height and temperature behavior to the overall pump efficiency. The temperature field and dynamic fluid film height were measured in two of the three lubricating interfaces. This is the first time that the temperature fields and gap heights were simultaneously measured in two of the main three interfaces of an axial piston machine. For a deeper analysis of the measurement data, all gaps were simulated with a numerical tool which takes solid body deformation due to temperature and pressure loads into account. This unique combination of both extensive measurement data and sophisticated simulation resulted in novel trends that clarify the complex phenomena occurring in these hydrostatic fluid films.     

Iterative Antimicrobial Candidate Selection from Informed D‐/L‐Peptide Dimer Libraries

Growing resistance to antibiotics, as well as newly emerging pathogens, stimulate the investigation of antimicrobial peptides (AMPs) as therapeutic agents. Here, we report a new library design concept based on a stochastic distribution of natural AMP amino acid sequences onto half‐length synthetic peptides. For these compounds, a non‐natural motif of alternating D ‐ and L ‐backbone stereochemistry of the peptide chain predisposed for β‐helix formation was explored. Synthetic D ‐/L ‐peptides with permuted half‐length sequences were delineated from a full‐length starter sequence and covalently recombined to create two‐dimensional compound arrays for antibacterial screening. Using the natural AMP magainin as a seed sequence, we identified and iteratively optimized hit compounds showing high antimicrobial activity against Gram‐positive and Gram‐negative bacteria with low hemolytic activity. Cryo‐electron microscopy characterized the membrane‐associated mechanism of action of the new D ‐/L ‐peptide antibiotics.     

Toll-Like Receptor and Accessory Molecule mRNA Expression in Humans and Mice as Well as in Murine Autoimmunity,Transient Inflammation,and Progressive Fibrosis

The cell type-, organ-, and species-specific expression of the Toll-like receptors (TLRs) are well described, but little is known about the respective expression profiles of their accessory molecules. We therefore determined the mRNA expression levels of LBP, MD2, CD36, CD14, granulin, HMGB1, LL37, GRP94, UNC93b1, TRIL, PRAT4A, AP3B1, AEP and the respective TLRs in human and mouse solid organs. Humans and mice displayed significant differences between their respective mRNA expression patterns of these factors. In addition, the expression profiles in transient tissue inflammation upon renal ischemia-reperfusion injury, in spleens and kidneys from mice with lupus-like systemic autoimmunity, and in progressive tissue fibrosis upon unilateral ureteral obstruction were studied. Several TLR co-factors were specifically regulated during the different phases of these disease entities, suggesting a functional involvement in the disease process. Thus, the organ- and species-specific expression patterns need to be considered in the design and interpretation of studies related to TLR-mediated innate immunity, which seems to be involved in the tissue injury phase, in the phase of tissue regeneration, and in progressive tissue remodelling.     

Selective oxidation of ammonia to nitrogen on transition metal containing mixed metal oxides

The selective catalytic oxidation of ammonia to nitrogen (NH₃-SCO) has been studied over hydrotalcite derived mixed metal oxides containing Cu, Co, Fe or Ni. XRD, BET, NH₃-TPD and TPR techniques were used for catalysts characterization. Results of NH₃-SCO were compared with those of selective catalytic reduction of NO with NH₃ (NO-SCR). Reaction mechanism was studied by temperature-programmed surface reaction (TPSR) and activity tests with a various contact time. Catalytic performance of the studied samples depends on both kind and loading of transition metals in the mixed metal oxide system. The Cu-containing samples have been found to be the most active catalysts of the NH₃-SCO process. Transition metal loading strongly influences distribution of ammonia oxidation products. The highest selectivity to N₂ was measured for the catalysts with the lowest transition metal content.     

Synthesis and crosslinking properties of phenolphtalein dimethacrylate

Summary By reacting esterification of phenolphtalein with methacrylate chloride, phenolphtalein dimethacrylate was obtained. Based on the results of elemental analysis, FTIR, ¹H-NMR and ¹³C-NMR spectra, the structure of the product was proposed. The dimethacrylate was used as new crosslinker to crosslink poly(methyl methacrylate) (PMMA). The influence of the amount dimethacrylate on the crosslink density and some properties of the crosslinked polymers networks such as swelling, mechanical properties (tensile strength and elongation at break) and thermal stability were examined.     

Inhibition of Neuronal Necroptosis Mediated by RIPK1 Provides Neuroprotective Effects on Hypoxia and Ischemia In Vitro and In Vivo

Ischemic brain injury is a widespread pathological condition, the main components of which are a deficiency of oxygen and energy substrates. In recent years, a number of new forms of cell death, including necroptosis, have been described. In necroptosis, a cascade of interactions between the kinases RIPK1 and RIPK3 and the MLKL protein leads to the formation of a specialized death complex called the necrosome, which triggers MLKL-mediated destruction of the cell membrane and necroptotic cell death. Necroptosis probably plays an important role in the development of ischemia/reperfusion injury and can be considered as a potential target for finding methods to correct the disruption of neural networks in ischemic damage. In the present study, we demonstrated that blockade of RIPK1 kinase by Necrostatin-1 preserved the viability of cells in primary hippocampal cultures in an in vitro model of glucose deprivation. The effect of RIPK1 blockade on the bioelectrical and metabolic calcium activity of neuron-glial networks in vitro using calcium imaging and multi-electrode arrays was assessed for the first time. RIPK1 blockade was shown to partially preserve both calcium and bioelectric activity of neuron-glial networks under ischemic factors. However, it should be noted that RIPK1 blockade does not preserve the network parameters of the collective calcium dynamics of neuron-glial networks, despite the maintenance of network bioelectrical activity (the number of bursts and the number of spikes in the bursts). To confirm the data obtained in vitro, we studied the effect of RIPK1 blockade on the resistance of small laboratory animals to in vivo modeling of hypoxia and cerebral ischemia. The use of Necrostatin-1 increases the survival rate of C57BL mice in modeling both acute hypobaric hypoxia and ischemic brain damage.     

Furfural Oxidation with Hydrogen Peroxide Over ZSM-5 Based Micro-Mesoporous Aluminosilicates

Micro-mesoporous aluminosilicates based on ZSM-5 zeolite, obtained by a dual template method, as well as in the presence of a dual-functional template (i.e. a Gemini-type surfactant), were tested in the oxidation of furfural with hydrogen peroxide. Even substantial changes in acidity and porosity of the catalysts result in minor variations of selectivity towards the desired products. Application of the synthesized zeolite-based materials in the oxidation of furfural with hydrogen peroxide leads to formation of 2(5H)-furanone (yield up to 28.5%) and succinic acid (up to 19.5%) as the main C4 reaction products. The kinetic model developed previously to treat the results for oxidation of furfural over sulfated zirconia was able to describe the data also for micro-mesoporous aluminosilicates.

Graphical Abstract

     

Rapid Assessment of Frying Performance Using Small Size Samples of Oils/Fats

A rapid, effective test mimicking actual frying was developed to assess the frying performance of oils and fats using small size samples. To a small volume of the oil to be tested, a formulated food consisting of gelatinized potato starch, glucose and silica gel (4:1:1 w/w) were added and content heated at 185 ± 5 °C with mixing for 2 h. Thermo-oxidative degradation of the oil was assessed by the measurement of the total amount of polar components and their composition, including degradation of tocopherols. The developed fast test accurately mimics actual frying done using an institutional fryer as assessed by the accumulation and composition of total polar components and the amount of residual tocopherols. The validity of the test was assessed using the following oils: regular canola, high oleic– low linolenic canola, and high oleic sunflower. Comparison of data between the fast frying test and institutional frying revealed a lack of significant differences. The developed frying test provides reliable quantitative and qualitative data describing the performance of the frying oil/fat. The rapid frying procedure allows assessment of the frying performance of oils at the early stages of development where usually only small amounts of the sample are available and when a large number of samples have to be tested assessing effects of oil additives.     

Investigations on electrochemical α-methoxylation of selected dipeptides

Voltamperometric studies on the indirect electrochemical α-methoxylation of Boc-Pro-Gly-OMe and Boc-Val-Gly-OMe in MeOH in the presence of NaCl or NaBr as the mediator suggested that the first reaction step was a direct N-halogenation of the dipeptide by active chlorine or bromine adsorbed on the electrode surface. The kind of mediator (NaCl or NaBr), its concentration, the current density, and the applied electric charge had a significant influence on the reaction course. In the case of Boc-Pro-Gly-OMe, the use of sodium bromide was necessary to obtain a relatively high ratio of α-monomethoxylation to α,α-dimethoxylation. For Boc-Val-Gly-OMe, the selectivity for α-monomethoxylation was close to 100%, independently of the mediator. Optimisation of the selected electrolysis parameters allowed us to significantly improve the yield and selectivity of the α-methoxylation of Boc-Pro-Gly-OMe (Kardassis et al. Tetrahedron 54:3471, 1998) and to obtain good results in the α-methoxylation of Boc-Val-Gly-OMe.