The etiology of oxidative stress in the various species of animals,a review

Oxidative stress is the consequence of an imbalance of pro‐oxidants and antioxidants leading to cell damage and tissue injury. The exhaustion of antioxidant systems is one of the reasons for the occurrence of oxidative stress, which results in avalanche production of reactive oxygen species (ROS) or free radicals. High oxidative stress is common in organs and tissues with high metabolic and energy demands, including skeletal and heart muscle, liver and blood cells. Stress arises in animals in response to unavoidable or adverse environmental conditions. In the external environment, which affects the body of the cow, there are four main groups of stressors: physical, chemical, biological and psychological. Physical stressors include fluctuations in ambient temperature as well as mechanical injuries. High ambient temperature is one of the factors affecting the productivity of cows. Biological stressors are conditioned by errors and irregularities in habits. Both of these phenomena have an adverse impact on both the resistance of animals and fertility and are the etiological agent of oxidative stress. Various mechanisms may be responsible for metal‐induced oxidative stress: direct or indirect generation of ROS, depletion of glutathione and inhibition of antioxidant enzymes are well known for all redox‐active and redox‐inactive metals. © 2014 Society of Chemical Industry     

3-D reconstruction by extended depth-of-field in failure analysis – Case study I: Qualitative fractographic investigation of fractured bolts in a partial valve

Extended depth-of-field 3-D reconstruction is an image processing based technique associated to optical microscopy for qualitative or quantitative analysis of surfaces topographies. It is proposed here as a low-cost alternative to scanning electron microscopy or confocal laser scanning microscopy methods in some cases in failure analysis. A case study of fractured bolts in a partial valve from a petrochemical plant is presented in this paper to illustrate a qualitative fractographic investigation using this technique.     

Landscape memory in abandoned areas—physical and ecological perspectives (Central European mountains case study)

Using the concept of landscape memory we examined the relationship between persistence of anthropogenic landforms and their botanical composition several decades after depopulation of Karpno village (Sudetes Mts), which represents the socio-economic and ecological processes typical for mountainous areas in post-war Central Europe. The research was based on geomorphic and botanical field surveys. Evidence of anthropogenic landscape memory still persists in local land morphology and ecosystem composition, despite the apparent homogeneity of large-scale landscape features. Former human activities continue to affect local site properties, which results in a mosaic of diverse habitats. Plant species composition of secondary ecosystems remains different from both their anthropogenic precursors and surrounding natural communities. Persistent habitat eutrophication slows down competitive exclusion of shade intolerant species in sites overgrown by forest canopy. Observed evidence cannot be explained without knowledge of local history, which is vital for planning development and conservation of bio-cultural landscapes.     

Correlative light‐electron fractography for fatigue striations characterization in metallic alloys

The correlative light‐electron fractography technique combines correlative microscopy concepts to the extended depth‐from‐focus reconstruction method, associating the reliable topographic information of 3‐D maps from light microscopy ordered Z‐stacks to the finest lateral resolution and large focus depth from scanning electron microscopy. Fatigue striations spacing analysis can be precisely measured, by correcting the mean surface tilting with the knowledge of local elevation data from elevation maps. This new technique aims to improve the accuracy of quantitative fractography in fatigue fracture investigations. Microsc. Res. Tech. 76:909–913, 2013. © 2013 Wiley Periodicals, Inc.     

Multi-stage crystallization for resolution of enantiomeric mixtures in a solid solution forming system

A systematic procedure for synthesizing the multi-stage crystallization process was developed for resolution of enantiomeric mixtures involving solid solutions in the crystalline phase. The model compound investigated was citalopram oxalate, which revealed a complete solid solution in the solid phase. The counter-current multi-stage batch crystallization was suggested to isolate the target enantiomer from enantiomerically enriched mixtures. The solid–liquid equilibria in the presence of a solvent and the distribution diagrams were quantified and used in designing the crystallization process and defining adequate processing conditions. Different flowsheet schemes were considered and compared with respect to the process performance. The design procedure was verified by the experimental separation of enantiomeric mixtures of citalopram.     

Structural,topographical, and mechanical characteristics of purified polyhydroxyoctanoate polymer

Insight into the topographic and mechanical properties of biomaterials allows for efficient selection of a material for a specific application. Here, atomic force microscopy (AFM) and force spectroscopy were exploited to reveal the topographic and mechanical characteristics of charcoal-purified, solvent-cast polyhydroxyoctanoate (PHO) film. The root mean square surface roughness of a PHO surface derived from ethyl acetate, acetone, or chloroform solution was 13.2, 11.5, or 30.9 nm, respectively, for 100 μm² AFM images. The distribution of the local Young's modulus had a maximum of 25.4, 14.1, and 12.6 MPa for PHO films obtained from ethyl acetate, acetone, and chloroform solution, respectively. The positron annihilation spectroscopy measurements allowed us to determine the free volume in the polymer film structure (9.38%). Moreover, a number of additional techniques (X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, gel permeation chromatography, NMR, infrared spectroscopy, and polarized light microscopy) were used to reveal PHO features. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47192.     

Hydroxy-PCBs, methoxy-PCBs and hydroxy-methoxy-PCBs: metabolites of polychlorinated biphenyls formed in vitro by tobacco cells

While the metabolism of polychlorinated biphenyls (PCBs) in plant cells is a rarely studied field, hydroxy-PCBs have been detected in several studies involving the use of various plant species. The ability of the tobacco (Nicotiana tabacum) callus culture WSC-38 to metabolize six dichlorobiphenyls under aseptic conditions was studied, and the resulting PCB metabolites were analyzed. WSC-38 cultures were cultivated with individual dichlorinated PCB congeners. The metabolites were identified based on mass spectra characteristics after gas chromatography separation. In addition, metabolites of PCB 9 (2,5-dichlorobiphenyl) were identified by comparing their retention characteristics with the available standards. In most cases at least two hydroxy-PCBs were produced from each parent PCB. Methoxy-PCBs and hydroxy-methoxy-PCBs were other groups of metabolites produced. To the best of our knowledge, ours is the first report to determine the presence of methoxy- and hydroxy-methoxy-metabolites of PCBs in plants. The role of the O-methyltransferases (OMTs) in the methylation of hydroxy-PCBs is discussed. As methoxy-metabolites of acetophenone were found among our samples, we posit that the OMTs responsible for the methylation of these compounds are also involved in the metabolism of PCBs in cultures of WSC-38.     

The Influence of UV Varnishes on the Content of Cysteine and Methionine in Women Nail Plates—Chromatographic Studies

The main purpose of this work was to determine if the use of hybrid nail polishes causes changes in concentration of the most important sulfur amino acids that build nail plate structures, cysteine and methionine. We found that the average contents of cysteine and methionine in studied samples before the use of hybrid manicure were 1275.3 ± 145.9 nmol mg⁻¹ and 111.7 ± 23.8 nmol mg⁻¹, respectively. After six months of hybrid manicure use, the average amount of these sulfur amino acids in studied samples were 22.1% and 36.5% lower in the case of cysteine and methionine, respectively. The average amounts of cysteine and methionine in nail plate samples after the use of hybrid manicures were 992.4 ± 96.2 nmol mg⁻¹ and 70.9 ± 14.8 nmol mg⁻¹, respectively. We also confirmed that in studied women the application of UV light varnishes reduced the thickness of the nail plate, from 0.50 ± 0.12 mm before to 0.46 ± 0.12 mm after the use of the hybrid manicure.     

Microencapsulation of ADN with HTPB-based membrane in the presence of the bonding agents Tepan or Tepanol**

Ammonium dinitramide (ADN) has appeared as a promising oxidizer for green propellants and thereby a potential substitute for ammonium perchlorate, largely in use in composite propellants for tactical and strategic long-range missiles. The novelty lies in replacing ammonium perchlorate with a chlorine-free oxidizer less harmful to the health and environment. However, ADN is hygroscopic and can potentially react with other chemical components, which could be overcome by microencapsulating the particles. The simple coacervation method was tested herein to microencapsulate ADN with a membrane made of hydroxyl-terminated polybutadiene as pre-polymer and methylene diphenyl diisocyanate as the curing agent. The effect of polyamine bonding agents on the capsule formation was tested by adding 0.5 or 2 % of Tepan or Tepanol, whose efficacy to bond to ADN was confirmed by detecting ammonia release through infrared spectroscopy. The capsule membrane was examined by optical and scanning electron microscopy. The dissolution time and rate were the parameters adopted to quantify permeability in a straight dissolution test in water, which demonstrated that 0.5 % Tepanol can provide the most effective protection. The infrared spectroscopy indicated that 60 °C temperature for prolonged periods, normally experienced by propellants, does not chemically affect the capsules’ membrane but can turn it lumpy. In conclusion, these polyamine bonding agents can assist the capsule formation over ADN particles using the simple coacervation method, however, their functionality on mechanical properties of propellants needs to be substantiated in forthcoming works as well as the effect of the concentration of bonding agents on propellant formulations.