The oxidation of bitumen witnessed in-situ by infrared spectroscopy

During the production and recycling of asphalt concrete, bitumen in contact with inorganic particles is exposed to air at high temperatures. As a result an oxidation of bitumen, also known as aging, occurs. The reaction between bitumen and air at 163 °C was studied insitu with and without the presence of inorganic impurities by means of fourier transform infrared spectroscopy in the attenuated reflectance mode. This oxidation was discovered to be a step-wise reaction facilitated by the oxidation of thiols and creation of peroxides within the system. The rate of reaction was demonstrated to depend on the type of impurity present, of which iron (III) chloride was the strongest catalyst. It was further demonstrated that the oxidation reaction is inhibited by the adsorption of thiol species present in the system on copper particles. Combining copper with the iron (III) chloride-containing system also resulted in the inhibition of signal increase in the sulfoxide region of the spectra. The results of this preliminary research on the bitumen oxidation reaction presented are proposed for further research regarding control of aging of asphalt concrete, especially during the recycling works.     

Double-Headed Cationic Lipopeptides: An Emerging Class of Antimicrobials

Antimicrobial peptides (AMPs) constitute a promising tool in the development of novel therapeutic agents useful in a wide range of bacterial and fungal infections. Among the modifications improving pharmacokinetic and pharmacodynamic characteristics of natural AMPs, an important role is played by lipidation. This study focuses on the newly designed and synthesized lipopeptides containing multiple Lys residues or their shorter homologues with palmitic acid (C₁₆) attached to the side chain of a residue located in the center of the peptide sequence. The approach resulted in the development of lipopeptides representing a model of surfactants with two polar headgroups. The aim of this study is to explain how variations in the length of the peptide chain or the hydrocarbon side chain of an amino acid residue modified with C₁₆, affect biological functions of lipopeptides, their self-assembling propensity, and their mode of action.     

Sprouted wheat grain with ferritin overexpression as a potential source of iron for cereal product fortification

Grains of winter wheat (Korweta variety) were partially germinated in an abiotic stress condition (0–15 mM FeSO₄ solutions) in order to accumulate iron by ferritin overexpression. The physical, chemical, biochemical properties and technological parameters of the obtained material as well as their resistance to an insect storage pest—granary weevil—were analyzed. Sprouted wheat grains with overexpression of ferritin contain 52 times more iron, more than 50 % in form of ferritin. The contents of reducing sugars, crude protein, fiber and ash as well as amylolytic activity increased significantly in sprouted wheat grain, while starch, fat, wet gluten, falling number and inhibition activity against granary weevil α-amylase decreased. Germinated wheat grain enriched with iron strongly affected granary weevil developmental parameters. Despite the fact that technological parameters of the product were deteriorated, it is worth to consider this material application as an iron supplement for cereal products, when the application of soybean is impossible.     

Psycho-social work conditions as risk factors for premature birth and newborn hypotrophy

On the basis of the studies carried out the authors verified a hypothesis that psychosocial work conditions and occupational stress are risk factors for premature birth and newborn hypotrophy. The following aspects were considered in the evaluation of psycho-social work conditions: (a) work-related psychological demands; (b) the extent to what an employee is able to control the situation at work; (c) occupational stress arising from the discrepancy between work-related demands and the extent of control over the work situation; and (d) interpersonal relations at work. The analysis covered 219 cases of premature births and 159 cases of newborn hypotrophy. The control group comprised 586 women sampled randomly who gave birth at term to a healthy baby with correct birth weight. The authors found that ill interpersonal relations and a low level of control over the situation at work elevate the risk of giving birth to a baby with hypotrophy, while good interpersonal relations and a high level of control over the situation at work play a protective role. The effect of these psycho-social factors applied only to hypotrophy of a newborn and it was related neither to other features of occupational work nor to biomedical factors. It seems that this kind of factors may have generally less pronounced impact on premature birth.     

Selectivity study of the differential impedance analysis—comparison with the complex non-linear least-squares method

The analytical power of the differential impedance analysis (DIA) as a new approach for model identification is investigated. The minimum of the ratio q of the two time-constants T₁ and T₂ (q=T₂/T₁) describing a two step reaction with ladder structure, at which the second time-constant T₂ is recognized, is accepted as a measure for the selectivity evaluation. The investigation is performed on synthetic models with variation of q in the interval from 30 to 0.001. The influence of data quality is studied by applying data truncation from seven to two digits, as well as by introduction of a wild point. Experimental data measured on two actual dummy cells with q equal to 30 and 0.03, respectively, are also analyzed. The results are compared with those obtained by applying the algorithm of the wide-spread complex non-linear least-squares method, performed on zview software product. The comparative study demonstrates a higher selectivity of the DIA, combined with an additional noise immunity and increased robustness of the analysis.     

Application of microwave vacuum drying for snack production: Characteristics of pure cheese puffs

The aim of the study was to obtain and describe crispy snacks purely made of cheese (also referred to as ‘pure’ cheese snacks) using microwave vacuum drying technology. An acid‐set ripened cheese (Harzer cheese) was tested as the raw material. Cutting, hot air drying and microwave vacuum drying were applied in the technology process. This paper investigates the impact of these processes on the physical properties of the puffs; it also includes sensory evaluation of the resulting product. The cheese pieces expanded by ca. 1000% of their original size with a sharp decrease in the bulk density of the puffed samples. Water activity, hardness and brittleness of the cheese puffs were 0.35, 1511.17 g and 3.20 mm, respectively. The CIE LAB coordinates (in spin position), L*, a* and b*, were 82.81, 1.51 and 20.54, respectively. This paper shows that a new form of dairy product can be produced using microwave technology.     

Tribochemical behaviour of the selected mesogenic additive in n-hexadecane

Summary Tribochemical behaviour of the selected mesogenic compound (4-butylcyclohexanoic acid p-hexaoxyphenyl ester) was investigated by means of ball-on-disk machine at ambient and elevated temperatures. To selection of the thermal conditions of tribological tests DSC technique was used and to analyse tribochemical products layered on the wear tracks—SEM/EDS, FTIRM and XPS ones. Obtained results show that the mesogen dissolved in n-hexadecane is an effective antiwear additive which decreases temperature of the lubricant. This is favoured mainly by tribochemical processes.     

Tribochemical Conversions of Zinc Dialkyldithiophosphate (ZDDP) Under Extremely Different Pressure Conditions

The authors performed ball-on-disk and four-ball tests. The former gave much less severe conditions than the latter. A ZDDP-containing package, blended with a mineral base oil, was tested. Completely different mechanisms of ZDDP conversions were observed. During ball-on-disk tests, ZDDP undergoes partial tribochemical decomposition. It results in a modification of the surface of test specimens—organic compounds are produced and zinc atoms diffuse into the surface. During four-ball tests, advanced structural decomposition of ZDDP takes place—S and P take part in tribochemical reactions. Probably inorganic compounds are produced, whereas there is a lack of a layer of organic ones adsorbed on the surface. The generation of inorganic compounds results from chemical reactions of decomposed ZDDP with the surface of steel specimens as well as diffusion of some elements (e.g. S) into the surface. Good antiseizure properties of such inorganic structures help to improve the tribological characteristics under severe test conditions.     

Cloning and Characterization of a Thermostable Endolysin of Bacteriophage TP-84 as a Potential Disinfectant and Biofilm-Removing Biological Agent

The obligatory step in the life cycle of a lytic bacteriophage is the release of its progeny particles from infected bacterial cells. The main barrier to overcome is the cell wall, composed of crosslinked peptidoglycan, which counteracts the pressure prevailing in the cytoplasm and protects the cell against osmotic lysis and mechanical damage. Bacteriophages have developed two strategies leading to the release of progeny particles: the inhibition of peptidoglycan synthesis and enzymatic cleavage by a bacteriophage-coded endolysin. In this study, we cloned and investigated the TP84_28 endolysin of the bacteriophage TP-84, which infects thermophilic Geobacillus stearothermophilus, determined the enzymatic characteristics, and initially evaluated the endolysin application as a non-invasive agent for disinfecting surfaces, including those exposed to high temperatures. Both the native and recombinant TP84_28 endolysins, obtained through the Escherichia coli T7-lac expression system, are highly thermostable and retain trace activity after incubation at 100 °C for 30 min. The proteins exhibit strong bacterial wall digestion activity up to 77.6 °C, decreasing to marginal activity at ambient temperatures. We assayed the lysis of various types of bacteria using TP84_28 endolysins: Gram-positive, Gram-negative, encapsulated, and pathogenic. Significant lytic activity was observed on the thermophilic and mesophilic Gram-positive bacteria and, to a lesser extent, on the thermophilic and mesophilic Gram-negative bacteria. The thermostable TP84_28 endolysin seems to be a promising mild agent for disinfecting surfaces exposed to high temperatures.