Experimental and Prenemilary Numerical Evaluation of Pressure Drops under the Conditions of the Stratified Gas-Liquid Flow in a Horizontal Pipe Filled with Metal Foam

The paper reports the results of experimental tests and numerical simulations related to the pressure drop during two-phase air-water mixture flow through a pipe containing metal foam packing. Aluminium foam with 40 PPI open cells was used in the tests. A horizontal pipe with an internal diameter of 10 mm was used, and the foam only occupied a section of the pipe length equal to 240 mm. In the section of the pipe upwards of the foam, stratified flow pattern was generated, i.e., the most characteristic type for the gas-liquid flow. The results of the experimental research were compared with the values derived on the basis of the empirical method, which was developed for several different metal foams and two-phase systems. The values derived from measurements and calculations were subsequently applied to validate one numerical simulation method that is known to be particularly applicable for two-phase gas-liquid flow through metal foams. As a final result, the phenomena resulting from the presence of foam in the stratified flow through a gas-liquid system, the deficiencies of the methods applied in calculating pressure drops and modeling their values in accordance with the adopted numerical procedure were indicated. All research and modelling were carried out with the purpose of testing the potential of metal foam use in pipes dedicated to heat exchanger design, particularly ones intended to improve energy efficiency

Attachment of Proteolytic Enzyme Inhibitors to Vascular Prosthesis—An Analysis of Binding and Antimicrobial Properties

Prosthetic infections are associated with high morbidity, mortality, and relapse rates, making them still a serious problem for implantology. Staphylococcus aureus is one of the most common bacterial pathogens causing prosthetic infections. In response to the increasing rate of bacterial resistance to commonly used antibiotics, this work proposes a method for combating pathogenic microorganisms by modifying the surfaces of synthetic polymeric biomaterials using proteolytic enzyme inhibitors (serine protease inhibitors—4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride and puromycin). While using techniques based on the immobilization of biologically active molecules, it is important to monitor the changes occurring on the surface of the modified biomaterial, where spectroscopic techniques (e.g., FTIR) are ideal. ATR-FTIR measurements demonstrated that the immobilization of both inhibitors caused large structural changes on the surface of the tested vascular prostheses (polyester or polytetrafluoroethylene) and showed that they were covalently bonded to the surfaces of the biomaterials. Next, the bactericidal and antibiofilm activities of the tested serine protease inhibitors were determined using the CLSM microscopic technique with fluorescent staining. During LIVE/DEAD analyses, a significant decrease in the formation of Staphylococcus aureus biofilm after exposure to selected concentrations of native inhibitors (0.02–0.06 mg/mL for puromycin and 0.2–1 mg/mL for 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride) was demonstrated

Antimycobacterial Activity of <i>Sida hermaphrodita</i> (L.) Rusby (Malvaceae) Seed Extract

The current prevalence of such lifestyle diseases as mycobacteriosis and tuberculosis is a result of the growing resistance of microorganisms to the available antibiotics and their significant toxicity. Therefore, plants can successfully become a source of new therapeutic agents. The aim of this study was to investigate the effect of protein extract from Sida hermaphrodita seeds on the morphology, structure, and viability of Mycobacterium smegmatis and to carry out proteomic characterization of the protein extract. The analyses were carried out using fluorescence and transmission microscopy, atomic force microscopy, and spectroscopy. The proteomic studies were performed using liquid chromatography coupled to tandem mass spectrometry. The studies showed that the seed extract applied at concentrations of 50–150 µg/mL exerted a statistically significant effect on M. smegmatis cells, that is, a reduction of the viability of the bacteria and induction of changes in the structure of the mycobacterial cell wall. Additionally, the SEM analysis confirmed that the extract did not have a cytotoxic or cytopathic effect on fibroblast cells. The proteomic analysis revealed the presence of structural, storage, and enzymatic proteins and peptides in the extract, which are typical for seeds. Proteins and peptides with antimicrobial activity identified as vicillins and lipid-transporting proteins were also determined in the protein profile of the extract

Can 2-oxoglutarate prevent changes in bone evoked by omeprazole?

Objective: Proton-pump inhibitors, such as omeprazole, are widely used in the prevention and treatment of gastroesophageal diseases. However, an association between proton-pump inhibitors and the increased risk of bone fractures has been observed, especially in patients treated for extended periods. Conversely, 2-oxoglutarate, a precursor of hydroxyproline, the most abundant amino acid in bone collagen, counteracts the bone loss. The aim of the present study was to elucidate the influence of omeprazole on bone and investigate whether dietary 2-oxoglutarate supplementation could prevent the effects of omeprazole. Methods: Eighteen male Sprague-Dawley rats were used. Rats received omeprazole in the diet and 2-oxoglutarate in the drinking water. Body and organ weights and serum concentrations of cholecystokinin and gastrin were measured. The femurs, tibias, and calvarias were collected. Histomorphometric analysis of bone and cartilage tissues was conducted. Bone densitometric and peripheral quantitative computed tomographic analyses of the femur and tibia were performed. Results: Omeprazole decreased the femur and tibia weights, the mechanical properties of the femur, the volumetric bone density and content, the trabecular and cortical bone mineral content, the total, trabecular, and cortical bone areas, the mean cortical thickness, and the periosteal circumference of the femur. Omeprazole had a minor effect on the examined bone morphology and exerted negligible effects on the cartilage. 2-Oxoglutarate lowered the gastrin concentration. Conclusions: Omeprazole treatment exerts its effects mostly on bone mineralization and cancellous bone, adversely affecting bone properties. This adverse effect of omeprazole was not markedly abolished by 2-oxoglutaric acid, which acted as an anti-hypergastrinemic agent. (C) 2013 Elsevier Inc. All rights reserved

Exopolysaccharide Carbohydrate Structure and Biofilm Formation by Rhizobium leguminosarum bv. trifolii Strains Inhabiting Nodules of Trifoliumrepens Growing on an Old Zn–Pb–Cd-Polluted Waste Heap Area

Heavy metals polluting the 100-year-old waste heap in Bolesław (Poland) are acting as a natural selection factor and may contribute to adaptations of organisms living in this area, including Trifolium repens and its root nodule microsymbionts—rhizobia. Exopolysaccharides (EPS), exuded extracellularly and associated with bacterial cell walls, possess variable structures depending on environmental conditions; they can bind metals and are involved in biofilm formation. In order to examine the effects of long-term exposure to metal pollution on EPS structure and biofilm formation of rhizobia, Rhizobium leguminosarum bv. trifolii strains originating from the waste heap area and a non-polluted reference site were investigated for the characteristics of the sugar fraction of their EPS using gas chromatography mass-spectrometry and also for biofilm formation and structural characteristics using confocal laser scanning microscopy under control conditions as well as when exposed to toxic concentrations of zinc, lead, and cadmium. Significant differences in EPS structure, biofilm thickness, and ratio of living/dead bacteria in the biofilm were found between strains originating from the waste heap and from the reference site, both without exposure to metals and under metal exposure. Received results indicate that studied rhizobia can be assumed as potentially useful in remediation processes

A Mutation in the <i>Mesorhizobium loti oatB</i> Gene Alters the Physicochemical Properties of the Bacterial Cell Wall and Reduces Survival inside <i>Acanthamoeba castellanii</i>

In our previous report, we had shown that the free-living amoeba Acanthamoeba castellanii influenced the abundance, competiveness, and virulence of Mesorhizobium loti NZP2213, the microsymbiont of agriculturally important plants of the genus Lotus. The molecular basis of this phenomenon; however, had not been explored. In the present study, we demonstrated that oatB, the O-acetyltransferase encoding gene located in the lipopolysaccharide (LPS) synthesis cluster of M. loti, was responsible for maintaining the protective capacity of the bacterial cell envelope, necessary for the bacteria to fight environmental stress and survive inside amoeba cells. Using co-culture assays combined with fluorescence and electron microscopy, we showed that an oatB mutant, unlike the parental strain, was efficiently destroyed after rapid internalization by amoebae. Sensitivity and permeability studies of the oatB mutant, together with topography and nanomechanical investigations with the use of atomic force microscopy (AFM), indicated that the incomplete substitution of lipid A-core moieties with O-polysaccharide (O-PS) residues rendered the mutant more sensitive to hydrophobic compounds. Likewise, the truncated LPS moieties, rather than the lack of O-acetyl groups, made the oatB mutant susceptible to the bactericidal mechanisms (nitrosative stress and the action of lytic enzymes) of A. castellanii