Straw/Nano-Additive Hybrids as Functional Fillers for Natural Rubber Biocomposites

Currently, up to 215 million metric tons of harvestable straw are available in Europe, 50% of the crops come from wheat, 25% from barley and 25% from maize. More than half of the production remains undeveloped. The overproduction of straw in the world means that the current methods of its management are insufficient. The article describes the production method and characterization of natural rubber biocomposites containing cereal straw powder modified with functional nano-additives in the form of carbon black, silica and halloysite nanotubes. The use of cereal straw in the elastomer matrix should contribute to obtaining a product with good mechanical properties while ensuring a low cost of the composite. In turn, the application of the mechanical modification process will allow the combination of specific properties of raw materials to obtain new, advanced elastomeric materials. As part of the work, hybrid fillers based on mechanically modified cereal straw were produced. The impact of hybrid fillers on mechanical, rheometric and damping properties was assessed. The flammability and susceptibility of the obtained biocomposites to aging processes were determined. The use of hybrid fillers based on mechanically modified straw allowed us to obtain a higher cross-linking density of vulcanizates (even up to 40% compared to the reference sample), and thus higher values of the rheometric moment during the vulcanization process of rubber mixtures (from approx. 10% (10 phr of filler) up to 50% (30 phr of filler) in relation to the unfilled system) and higher hardness of vulcanizates (by about 30–70%). The curing time of the blends was slightly longer, but the obtained composites were characterized by significantly higher tensile strength. The use of fillers in the elastomer matrix increased the modulus at 100, 200 and 300% and the elongation at break. Moreover, greater resistance of vulcanizates to the combustion process was confirmed

Maximising performance of a hospital’s HBOT laboratory using the theory of constraints

Purpose: The paper presents an application of the Theory of Constraints (TOC) aimed at defining and maximising the potential of hyperbaric chamber as a key resource in a specialist hospital. Design/methodology/approach: The authors developed their own TOC based method of process improvement, supported by tools of Lean Management. Various constraints including an external one were taken into consideration. As a follow-up a project using the method was carried out in a hospital’s Hyperbaric Oxygen Therapy laboratory. Findings: The developed and implemented practical solution has improved patients’ access to the service at about 40% per day, shortened patients’ waiting time at about 90% and helped to overcome the threat of financial underperformance. Moreover, in combination with strict safety rules, the solution has proven its high resistance against difficulties caused by the COVID-19 pandemic. Research limitations/implications: A hyperbaric therapy is a narrow branch of medicine, therefore application of the method in other healthcare domains will require an appropriate adaptation. Practical implications: Despite the narrow subject of the study, the described approach is universal and can be used to maximise the capacity utilisation of various critical resources in hospitals and other healthcare providers. Originality/value: This is the first known to the authors application of a TOC/Lean based systematic hybrid approach to improve performance of a healthcare provider, which is taking into account several constraints including an external one. Additionally, this is the first paper on TOC in healthcare published in Poland

Modified Nanoclays/Straw Fillers as Functional Additives of Natural Rubber Biocomposites

Increasingly, raw materials of natural origin are used as fillers in polymer composites. Such biocomposites have satisfactory properties. To ensure above-average functional properties, modifications of biofillers with other materials are also used. The presented research work aimed to produce and characterize elastomeric materials with a straw-based filler and four different types of montmorillonite. The main research goal was to obtain improved functional parameters of vulcanizates based on natural rubber. A series of composites filled with straw and certain types of modified and unmodified nano-clays in various ratios and amounts were prepared. Then, they were subjected to a series of tests to assess the impact of the hybrids used on the final product. It has been shown that the addition of optimal amounts of biofillers can, inter alia, increase the tensile strength of the composite, improve damping properties, extend the burning time of the material and affect the course of vulcanization or cross-linking density

Study on the Effect of Zinc on the Rheological, Mechanical and Thermal Properties and Fire Hazard of Unfilled and Filled CR/BR Vulcanizates

This paper discusses the cross-linking and functional properties of elastomer composites containing chloroprene rubber (CR) and butadiene rubber (BR) cured in the presence of zinc (Zn) and reinforced with mineral fillers. The research aimed to evaluate the effectiveness of zinc as a new cross-linking substance with the simultaneous production of elastomer materials with good mechanical properties and a reduced fire hazard. The article concerns the study and explanation of the dependencies influencing the processing and functional properties of unfilled or filled elastomer blends containing different elastomers ratio or different zinc’s amount. The following fillers were used: silica, kaolin, chalk and montmorillonite. The results revealed that the cross-linking degree of CR/BR blends decreased with the increasing amount of butadiene rubber in the blends. The mechanical properties of the cured blends depended on the proportion of elastomers in the composites, the zinc amount, and the presence and type of filler. The flammability of CR/BR/Zn vulcanizates has been investigated before and after the filling. The parameters assessed by the oxygen index method and cone calorimetry, characterizing the behavior of the tested CR/BR/Zn vulcanizates under fire conditions, have shown that they constitute a low fire hazard and can be considered as non-flammable materials

Amnion as an Innovative Antiseptic Carrier: A Comparison of the Efficacy of Allogeneic and Xenogeneic Transplantations in the Context of Burn Therapy

Background and Objectives: The amniotic membrane is widely used in the treatment of chronic wounds, in toxic epidermal necrolysis (TEN), and in the treatment of burns. In our clinical practice, we use amniotic dressings on shallow skin wounds caused by burns. Counteracting infections is an important aspect of working with burn wounds. Therefore, the main goals of this work are to demonstrate the usefulness of amniotic membrane soaked in antiseptics for the prevention of wound infections and to compare the antibacterial efficacy of selected variants of allogeneic and xenogeneic amniotic membrane grafts soaked in specific antiseptic agents. Materials and Methods: The studied material consisted of human and pig placenta. The human and animal amnions were divided in two parts. The first part consisted of amniotic discs placed on rigid mesh discs and preparing the fresh amnion. The second part of the amnion was frozen at a temperature of −80 °C for 24 h. Then, it was radio-sterilized with a dose of 35 kGy. The amniotic discs were placed on rigid mesh to prepare the radiation-sterilized amnion. The amniotic discs were placed in a 12-well plate and immersed in 3 mL of the appropriate antiseptic solutions: Prontosan, Braunol, Borasol, Microdacyn, Octenilin, Sutrisept, and NaCl as a control. The amniotic discs were incubated in antiseptics for 3 h. The microbiological tests were conducted by placing the antiseptic-infused amniotic discs on microbiological media inoculated with hospital strains. Results: The largest average zone of growth inhibition was observed in dressings soaked with Sutrisept, Braunol, and Prontosan. The greatest inhibition of bacterial growth was achieved for radiation-sterilized porcine amnion impregnated with Braunol and Sutrisept, as well as for radiation-sterilized human amnion impregnated with Braunol. Conclusions: Human and porcine amniotic membrane is effective in carrying antiseptics. Radiation-sterilized amnion seems to inhibit the growth of microorganisms better than fresh amnion

Direct laser interference lithography in periodical treatment of biomaterials

The paper presents the results of research on modern laser micromachining technology based on utilization of the interference field of high energy, pulse laser beams. The influence of radiation polarization on a pattern shape in an interference image has been analyzed theoretically. Values of laser ablation threshold for titanium and diamond-like coatings were determined experimentally. The particular advantages of the direct laser interference lithography method have been shown in a series of tests devoted to the periodical surface topography modification, including creation of hierarchical structures with different periods and feature dimensions. Another trial of tests has confirmed also the application potential of this technique in shaping of implant surfaces as well as preparation of scaffolds for cells and tissues culturing in bioengineering.[b]Keywords[/b]: materials engineering, laser micromachining, interference lithography, titanium alloys, diamond-like carbon layers, biomaterial

Bezpośrednia laserowa litografia interferencyjna w periodycznej obróbce biomateriałów

The paper presents the results of research on modern laser micromachining technology based on utilization of the interference field of high energy, pulse laser beams. The influence of radiation polarization on a pattern shape in an interference image has been analyzed theoretically. Values of laser ablation threshold for titanium and diamond-like coatings were determined experimentally. The particular advantages of the direct laser interference lithography method have been shown in a series of tests devoted to the periodical surface topography modification, including creation of hierarchical structures with different periods and feature dimensions. Another trial of tests has confirmed also the application potential of this technique in shaping of implant surfaces as well as preparation of scaffolds for cells and tissues culturing in bioengineering.[b]Keywords[/b]: materials engineering, laser micromachining, interference lithography, titanium alloys, diamond-like carbon layers, biomaterial

Preliminary Research on the Effect of Hyperbaric Oxygen Therapy in Patients with Post-COVID-19 Syndrome

Negative consequences and medical complications of COVID-19 can persist for up to several months after initial recovery. These consequences can include stroke, diabetes, decreased lung diffusing capacity, sleep apnea, pulmonary fibrosis, arrhythmia, myocarditis, fatigue, headaches, muscle aches, heart rate fluctuations, sleep problems, memory problems, nervousness, anxiety, and other neurological disorders. Thirty-one patients who reported symptoms related to previous COVID-19 disease of both sexes were enrolled in the initial program. The patients underwent compression sessions in a multiplace hyperbaric chamber. Each patient underwent a cycle of 15 compressions. Before the first session, each participant completed a venous blood gas test, a Fullerton test, and two spirometry tests (one before the Fullerton test and one after the test). Patients completed psychotechnical tests, a questionnaire on quality of life (Polish version of EQ-5D-5L), and a questionnaire on specific symptoms accompanying the disease and post-infection symptoms. The results showed significant improvements in areas such as quality of life, endurance and strength, some spirometric parameters, the anion gap and lactate levels, working memory, and attention in the group of treated patients. In contrast, there were no changes in pH, pO2, pCO2, glucose, and excess alkaline values. A follow-up interview confirmed that the beneficial effects were maintained over time. Considering the results obtained, including the apparent improvement in the patient’s clinical condition, it can be concluded that the use of 15 compression sessions was temporarily associated with a noticeable improvement in health and performance parameters as well as improvement in certain blood gas parameters