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The following work covers several issues. It discusses environmental factors identified in the scientific literature, especially pollutants emitted during fires that can be found crucial in terms of their contribution to occupational exposure among firefighters. Moreover, the authors described the issue of transferring pollutants indoors on the surface of items of clothing, equipment, and other elements by firefighters, which is commonly indicated in many studies. It was shown that this occurrence can be a secondary source of numerous substances inside rooms, in which firefighters stay before or after fire and rescue operations. Chronic and long-term exposure in the context of causing life-long health hazards (including carcinogenic effects) has a greater impact than occasional staying in a highly polluted environment (for instance during an extinguishing action). Due to the above, the summary of the following work contains recommendations concerning subjects of studies that need to be soon conducted to decrease the level of occupational exposure of firefighters caused by environmental factors. [ABSTRACT FROM AUTHOR]

The purpose of the article was to analyse the reliability, maintainability, and availability estimates of firefighting and rescue engines. Analysing the reliability parameters of heavy firefighting and rescue vehicles over time requires knowledge of their failures. In this article, failure data from the six years of maintenance of ten heavy firefighting and rescue vehicles from ten were analysed in relation to two main subsystems. Reliability analysis was performed and the best-fit distribution was found, with the parameters calculated. For both subsystems, the chassis combined with the cabin and the superstructure, the 2P-Weibull distribution was identified as the most suitable fit. The availability and maintenance indicators for each vehicle and the individual subsystems were calculated. It was clearly defined that there exists a significant difference between the two subsystems analysed in terms of failure characteristics, as well as maintainability and availability parameters. [ABSTRACT FROM AUTHOR]

A firefighter's helmet is used as a basic personal protective equipment item. The purpose of the helmet is to absorb a part of mechanical impact acting towards the rescuer's cervical spine, which may lead to its injury. The aim of the study was to determine the effect of changes in the helmet design on the threshold passive forces transferred to the firefighter's cervical spine. The test subjects were firefighter's helmets compliant with the European standard for helmets used by fire brigades. The study was carried out under model conditions, using special equipment with a head model and an additional force sensor placed under it, where the cervical spine is anatomically located. The central impact energy was assumed to be 60 J. A semi-spherically ended beater was used. The experimentally determined force-displacement characteristics revealed two phases of force increase. Using polyurethane foam as a cushioning insert instead of the expanded polyester used in older designs reduced values of forces in the first phase of the characteristic. There were many cases where the critical passive force value was exceeded, which would have resulted in the cervical spine injury. Modifications in material selection and component manufacturing technology affect the protective capabilities of firefighter's helmets and result in their improvement. Nevertheless, helmets that are currently in use are still affected by forces whose values exceed the ones that are considered to be safe for a firefighter. [ABSTRACT FROM AUTHOR]

Air pollution in the vicinity of roads is a complex and growing problem. In urbanised areas, there are many sources of dust emissions, but one of the main ones is road traffic. Investigating and assessing the physical and chemical properties of road dust and, more specifically, dust collected from surface courses is one way of providing an opportunity not only to identify the contribution of the emitters concerned to the formation of dust air pollution in the vicinity of roads but above all the environmental risks associated with traffic emissions. The study aimed to analyse the elemental composition of dust with a fraction <0.1 mm, collected from asphalt and concrete roads characterised by the highest technical and service parameters in Poland. The samples were analysed using a Shimadzu EDX 7000 energy-dispersive X-ray fluorescence spectrometer, then the results were statistically analysed using the t-Welch test, and the enrichment factors EF were determined. It was shown that road dust with a grain size of less than 0.1 mm collected from asphalt surface course was extremely highly enriched in Cu, Cr, Pb and S, while that from the concrete surface course was enriched in Zn and Zr, indicating a strong anthropogenic origin of these elements; exhaust gases were identified as their source. Irrespective of the type of surface course, very high dust enrichment occurs for Ca, Mn, Ni, S, Ti and Y. These elements may originate from the abrasion process of vehicle tyres. For road dust collected from both road types, the most similar EF values were found for Fe, K, Mn, Si, Sr and Ti. The source of these elements is most likely the roadside soil. It follows that the type of road surface is not the main determinant of the composition of road dust with a fraction <0.1 mm. [ABSTRACT FROM AUTHOR]

The aim of the research in the Poleski National Park was to determine the concentration of radionuclides and heavy metals in the soil and to evaluate the absorbed dose and the average annual effective dose as a result of external exposure to ground-based radiation sources. The spread of anthropogenic radionuclide concentration in the Poleski National Park was the highest. This is a first-of-its-kind study in Poland. The annual effective dose calculated for the Poleski National Park was over three times higher than the average worldwide value. Soil samples were subjected to mineralization using a TITAN MPS with a rotor. Subsequently, the metals in the obtained solutions were determined using the atomic absorption spectrometry method with flame atomization (AAS FM). The content of copper Cu, nickel Ni, lead Pb, cadmium Cd, and chromium Cr did exceed the average content neither in Europe nor around the world. The soils of the Poleski National Park are characterized by pollution with the tested heavy metals, especially cadmium Cd. [ABSTRACT FROM AUTHOR]

This year marks the 20th anniversary of the publication by the Institute of Mother and Child in Warsaw of a document establishing the Polish standards for preventive health care of school-age children and adolescents by general practitioners, which are still in force today. Since then, their health status and the health risk factors have changed. Polish society and its expectations of health care are also different. The Polish economy has grown, and the proportion of the public budget spent on health care has increased. The current system of preventive health care for young people seems to be facing a problem. Over the past decade, the percentage of children and adolescents attending preventive medical visits in Poland has decreased by approximately 30%. During well-care visits, doctors commonly avoid selected physical examinations and sensitive topics, such as sexuality or mental health. It appears that most young people visit doctors only because they falsely believe that check-up visits are mandatory and usually rate the experience negatively. The co-authors of this paper conclude that there is a need for a broad debate on the Polish standards of preventive health care for adolescents and their possible reform, which would lead to their adaptation to the challenges of modern times and the opportunities offered by the progress of medical science and technology. The selection of topics is subjective and certainly does not cover all aspects requiring attention. The authors’ intention is to contribute to further discussion rather than to provide a basis for conclusions or postulates. [ABSTRACT FROM AUTHOR]

The objective of the study was to carry out an analysis of changes in mechanical properties of polymer composites in conditions of thermal load. Such an analysis may allow an initial verification of possibilities of deploying new composites in production of fire helmet shells. The reference material chosen for testing was the Ultramid composite, which is currently used for the production of fire helmet shells. In addition three different materials were selected that contained reinforcement by glass fibres bearing the trade name of Tarnamid, which are not used in manufacturing of shells. Testing was conducted in conditions of quasi-static load, during which compressive tests were performed. Mechanical loads were applied at different levels of thermal exposure, which was to simulate presence in fire conditions. Results of tests indicated that the Tarnamid composites are characterised by better compressive strength and rigidity determined on the basis of the Young module value than Ultramid PA66 GF25 used in the production of head protective shells. It has also been proven that thermal loads contribute to significant degradation in strength and rigidity of tested materials, which affects adversely protective properties of the helmet.

This study was undertaken to analyze the influence of nozzle type on a mass spray density. The results indicated that the most uniform droplet distribution and spraying area was observed for the impact nozzle P 54. The highest mass spray density and the lowest spraying were noticed for the spiral nozzle TF 6. The high values of mass spray density for TF 6 nozzle were associated with the high K-factor value and the low spray angle. The results also showed that the construction of spiral nozzles influence the stream structure. The value of average mass spray density was twice as low for CW-50 F nozzle compared to TF 6.

Among the many different chemicals in the air, polycyclic aromatic hydrocarbons (PAHs) pose a serious threat to human health. Firefighters are exposed to them both during fire suppression and in fire vehicles and fire stations due to inhalation of the fumes from contaminated clothing and personal protective equipment. This study aimed to estimate the exposure and cancer risk caused by suspended particulate matter and PAHs present in these particles. Air samples were collected for 4 months in a garage of the fire station in a small town, located in an urban–rural area. PAH concentrations were measured using the gas chromatography method with mass spectrometry (GC/MS). The concentration of PM4 (particulate matter with a diameter below 4µm) and TSP (total suspended particulate) in the fire station garage was 7 and 9 times higher than outside, respectively. The calculated values of health hazard risks associated with the exposure to PAHs in PM4 and TSP are: a toxic equivalent (TEQ) up to 10.36 and 23.3, incremental lifetime cancer risk (ILCR) up to 3.45 and 4.65 and hazard quotient (HQ) up to 0.42 and 0.57, respectively. A significantly increased risk of cancers in the professional group of firefighters was found. [ABSTRACT FROM AUTHOR]

Background and Objectives: Since vaccination against COVID-19 is available for over a year and the population of immunized individuals with autoimmune disorders is higher than several months before, an evaluation of safety and registered adverse events can be made. We conducted a large study of side effects following the COVID-19 vaccine among patients with multiple (MS) sclerosis treated with disease-modifying therapies (DMTs) and analyzed factors predisposing for particular adverse events. Methods: We gathered data of individuals with MS treated with DMTs from 19 Polish MS Centers, who reported at least one adverse event following COVID-19 vaccination. The information was obtained by neurologists using a questionnaire. The same questionnaire was used at all MS Centers. To assess the relevance of reported adverse events, we used Fisher's exact test, t -test, and U -Menn-Whutney test. Results: A total of 1,668 patients with MS and reports of adverse events after COVID-19 vaccination were finally included in the study. Besides one case marked as "red flag", all adverse events were classified as mild. Pain at the injection site was the most common adverse event, with a greater frequency after the first dose. Pain at the injection site was significantly more frequent after the first dose among individuals with a lower disability (EDSS ≤2). The reported adverse events following immunization did not differ over sex. According to age, pain at the injection site was more common among individuals between 30 and 40 years old, only after the first vaccination dose. None of the DMTs predisposed for particular side effects. Conclusions: According to our findings, vaccination against COVID-19 among patients with MS treated with DMTs is safe. Our study can contribute to reducing hesitancy toward vaccination among patients with MS. [ABSTRACT FROM AUTHOR]

(1) Background: The present study aims to report the side effects of vaccination against coronavirus disease 2019 (COVID-19) among patients with multiple sclerosis (MS) who were being treated with disease-modifying therapies (DMTs) in Poland. (2) Methods: The study included 2261 patients with MS who were being treated with DMTs, and who were vaccinated against COVID-19 in 16 Polish MS centers. The data collected were demographic information, specific MS characteristics, current DMTs, type of vaccine, side effects after vaccination, time of side-effect symptom onset and resolution, applied treatment, relapse occurrence, and incidence of COVID-19 after vaccination. The results were presented using maximum likelihood estimates of the odds ratio, t-test, Pearson's chi-squared test, Fisher's exact p, and logistic regression. The statistical analyses were performed using STATA 15 software. (3) Of the 2261 sampled patients, 1862 (82.4%) were vaccinated with nucleoside-modified messenger RNA (mRNA) vaccines. Mild symptoms after immunization, often after the first dose, were reported in 70.6% of individuals. Symptoms included arm pain (47.5% after the first dose and 38.7% after the second dose), fever/chills/flu-like symptoms (17.1% after the first dose and 20.5% after the second dose), and fatigue (10.3% after the first dose and 11.3% after the second dose). Only one individual presented with severe side effects (pro-thrombotic complications) after vaccination. None of the DMTs in the presented cohort were predisposed to the development of side effects. Nine patients (0.4%) had a SARS-CoV-2 infection confirmed despite vaccination. (4) Conclusions: Vaccination against SARS-CoV-2 is safe for people with MS who are being treated with DMTs. Most adverse events following vaccination are mild and the acute relapse incidence is low. [ABSTRACT FROM AUTHOR]

The aim of the study was to determinate the fracture mechanism of firefighters' helmets caused by the impact load in simulated operational conditions. Moreover the aim of the study was to assess the reliability of the personal protective equipment. Tests were conducted with the use of the drop tower system. On each type of helmet 5 impact tests were performed. The active force corresponding to impact energy of 60 J and the passive force (force in the place of the neck spine) was registered. Based on the results, it can be statement that helmets' structure influences their reliability and values of the active and passive forces. Additionally, the majority of tested helmets exceeded the acceptable threshold values of passive force. [ABSTRACT FROM AUTHOR]

Featured Application: The results of the study could improve the practical use of sorbents and neutralizers during chemical rescue operations. Undertaking effective and prompt action during chemical events is an important measure in preventing the spread of contamination. Studies have shown that despite very high surface activity of nanocrystalline metal oxides, their use does not reduce the fire hazard for hydrocarbon spills and alcohols more effectively than commonly used sorbents during fire rescue operations. Other limitations of specimens containing nanocrystalline oxides have also been proven, such as the maximum absorption similar to commonly used specimens, as well as high costs of conducting the acid neutralization process without increasing the level of safety of operations. Results obtained allowed the determination of proposed principles of effective and economically appropriate application of nanocrystalline metal oxides in rescue units. [ABSTRACT FROM AUTHOR]

The article examines how United Nations and Human Rights Treaty Body Review was foreseen as a chance to re-evaluate the system that monitors countries' compliance with international human rights obligations. It mentions about need of multilateralism with great mobilization for the rights, voice and leadership of women and girls.

The paper presents analysis of the availability of medium firefighting and rescue vehicles chassis used by State Fire Brigade in Warsaw. For analysis of availability of vehicles chassis the technical availability factor has been used. Additionally, in the paper time to restore of the vehicles chassis regarding causes of unavailability has been presented. In the tests the data obtained from the Decision Support System (DSS) of Warsaw State Fire Brigade were applied. The research included the period from January 2012 to May 2015. Based on the results, it can be statement that the operating mileage is the crucial factor of operating degradation of firefighting vehicles chassis. [ABSTRACT FROM AUTHOR]

In this paper the reliability assessment of structural reliability of the selected light-cured dental composites based on the biaxial flexural strength test results has been presented. A two-parameter Weibull distribution was applied as a reliability model in order to estimate probability of strength maintenance in the analysed population. Weibull distribution parameters were interpreted as a characteristic material strength (scale parameter) and structural reliability parameter in terms of ability to maintain strength by each of specimen from the general population (shape parameter). 20 composite specimens underwent strength tests, including 2 'flow' type composites and 2 standard composites (with typical filler content). 'Flow' type composites were characterized with lower characteristic strength and higher structural reliability comparing to other studied composites. [ABSTRACT FROM AUTHOR]

The conditions of the gastrointestinal tract may change the physicochemical properties of nanoparticles (NPs) and therewith the bioavailability of orally taken NPs. Therefore, we assessed the impact ofin vitrogastrointestinal digestion on the protein corona of polystyrene NPs (PS-NPs) and their subsequent translocation across anin vitrointestinal barrier. A co-culture of intestinal Caco-2 and HT29-MTX cells was exposed to 50 nm PS-NPs of different charges (positive and negative) in two forms: pristine and digested in anin vitrogastrointestinal digestion model.In vitrodigestion significantly increased the translocation of all, except the “neutral”, PS-NPs. Uponin vitrodigestion, translocation was 4-fold higher for positively charged NPs and 80- and 1.7-fold higher for two types of negatively charged NPs. Digestion significantly reduced the amount of protein in the corona of three out of four types of NPs. This reduction of proteins was 4.8-fold for “neutral”, 3.5-fold for positively charged and 1.8-fold for one type of negatively charged PS-NPs.In vitrodigestion also affected the composition of the protein corona of PS-NPs by decreasing the presence of higher molecular weight proteins and shifting the protein content of the corona to low molecular weight proteins. These findings are the first to report thatin vitrogastrointestinal digestion significantly affects the protein corona and significantly increases thein vitrotranslocation of differently charged PS-NPs. These findings stress the importance of including thein vitrodigestion in futurein vitrointestinal translocation screening studies for risk assessment of orally taken NPs. [ABSTRACT FROM PUBLISHER]

Intestinal translocation is a key factor for determining bioavailability of nanoparticles (NPs) after oral uptake. Therefore, we evaluated threein vitrointestinal cell models of increasing complexity which might affect the translocation of NPs: a mono-culture (Caco-2 cells), a co-culture with mucus secreting HT29-MTX cells and a tri-culture with M-cells. Cell models were exposed to well characterized differently sized (50 and 100 nm) and charged (neutral, positively and negatively) polystyrene NPs. In addition, two types of negatively charged NPs with different surface chemistries were used. Size strongly affected the translocation of NPs, ranging up to 7.8% for the 50 nm NPs and 0.8% for the 100 nm NPs. Surface charge of NPs affected the translocation, however, surface chemistry seems more important, as the two types of negatively charged 50 nm NPs had an over 30-fold difference in translocation. Compared with the Caco-2 mono-culture, presence of mucus significantly reduced the translocation of neutral 50 nm NPs, but significantly increased the translocation of one type of negatively charged NPs. Incorporation of M-cells shifted the translocation rates for both NPs closer to those in the mono-culture model. The relative pattern of NP translocation in all three models was similar, but the absolute amounts of translocated NPs differed per model. We conclude that for comparing the relative translocation of different NPs, using one intestinal model is sufficient. To choose the most representative model for risk assessment,in vivoexperiments are now needed to determine thein vivotranslocation rates of the used NPs. [ABSTRACT FROM PUBLISHER]

• Physical activity has been proved as beneficial in multiple sclerosis (MS). • COVID-19 pandemic has affected physical activity of people with MS (PwMS). • Greater interest in online training was observed among PwMS under lockdown conditions. • Innovative systems delivering rehabilitation outside hospital are an urgent need. COVID-19 pandemic has affected people with multiple sclerosis (PwMS) on various levels. Pandemic lockdown influenced the access to typical measures of physical activity such as out-door training or gym exercises. We performed a survey assessing physical activity during pandemic lockdown among PwMS treated in our MS center. The questionnaire encompassed questions regarding physical activity before and during lockdown, including the employment of online technologies. The survey was completed by 262 PwMS. Physical activity before lockdown was declared by 74.4% of PwMS, regular exercises were declared by 30.9% of participants. Among physically active PwMS 50.5% limited their physical activity during the COVID-19 lockdown. The decrease in physical activity was reported more frequently by PwMS with higher levels of disability, particularly declaring regular exercises before lockdown. In the opinion of 39,7% of PwMS online training could replace standard exercises, however only 19,9% of PwMS were actively looking for online training during the lockdown. The interest in online exercise was greatest in the group ≤30 years of age and EDSS ≤2. Synchronous exercises were the preferred online training, particularly among PwMS with EDSS≥4. Our findings indicate a need for systematic educational and organizational measures, promoting physical activity among PwMS and acknowledging pandemic conditions. [ABSTRACT FROM AUTHOR]

Multiple sclerosis (MS) is a chronic disease with an inflammatory and neurodegenerative pathology. Axonal loss and neurodegeneration occurs early in the disease course and may lead to irreversible neurological impairment. Changes in brain volume, observed from the earliest stage of MS and proceeding throughout the disease course, may be an accurate measure of neurodegeneration and tissue damage. There are a number of magnetic resonance imaging-based methods for determining global or regional brain volume, including cross-sectional (e.g. brain parenchymal fraction) and longitudinal techniques (e.g. SIENA [Structural Image Evaluation using Normalization of Atrophy]). Although these methods are sensitive and reproducible, caution must be exercised when interpreting brain volume data, as numerous factors (e.g. pseudoatrophy) may have a confounding effect on measurements, especially in a disease with complex pathological substrates such as MS. Brain volume loss has been correlated with disability progression and cognitive impairment in MS, with the loss of grey matter volume more closely correlated with clinical measures than loss of white matter volume. Preventing brain volume loss may therefore have important clinical implications affecting treatment decisions, with several clinical trials now demonstrating an effect of disease-modifying treatments (DMTs) on reducing brain volume loss. In clinical practice, it may therefore be important to consider the potential impact of a therapy on reducing the rate of brain volume loss. This article reviews the measurement of brain volume in clinical trials and practice, the effect of DMTs on brain volume change across trials and the clinical relevance of brain volume loss in MS. [ABSTRACT FROM AUTHOR]

Oral ingestion is an important exposure route for silver nanoparticles (AgNPs), but their fate during gastrointestinal digestion is unknown. This was studied for 60 nm AgNPs and silver ions (AgNO3) using in vitro human digestion model. Samples after saliva, gastric and intestinal digestion were analysed with SP-ICPMS, DLS and SEM-EDX. In presence of proteins, after gastric digestion the number of particles dropped significantly, to rise back to original values after the intestinal digestion. SEM-EDX revealed that reduction in number of particles was caused by their clustering. These clusters were composed of AgNPs and chlorine. During intestinal digestion, these clusters disintegrated back into single 60 nm AgNPs. The authors conclude that these AgNPs under physiological conditions can reach the intestinal wall in their initial size and composition. Importantly, intestinal digestion of AgNO3 in presence of proteins resulted in particle formation. These nanoparticles (of 20-30 nm) were composed of silver, sulphur and chlorine. [ABSTRACT FROM AUTHOR]

As more investigations into factors affecting the quality of life of patients with multiple sclerosis (MS) are undertaken, it is becoming increasingly apparent that certain comorbidities and associated symptoms commonly found in these patients differ in incidence, pathophysiology and other factors compared with the general population. Many of these MS-related symptoms are frequently ignored in assessments of disease status and are often not considered to be associated with the disease. Research into how such comorbidities and symptoms can be diagnosed and treated within the MS population is lacking. This information gap adds further complexity to disease management and represents an unmet need in MS, particularly as early recognition and treatment of these conditions can improve patient outcomes. In this manuscript, we sought to review the literature on the comorbidities and symptoms of MS and to summarize the evidence for treatments that have been or may be used to alleviate them. [ABSTRACT FROM PUBLISHER]

Objective: Antigen-specific therapy targeting selective inhibition of autoreactive responses holds promise for controlling multiple sclerosis (MS) without disturbing homeostasis of the whole immune system. Key autoantigens in MS include myelin proteins, such as myelin basic protein (MBP), proteolipid protein (PLP), and myelin oligodendrocyte glycoprotein (MOG). In this study, we examined the effect of transdermal therapy with myelin peptides on immune responses in the skin, lymph nodes, and peripheral blood immune cells of MS patients. Methods: In a 1-year placebo-controlled study, 30 patients with relapsing-remitting MS were treated transdermally with a mixture of 3 myelin peptides: MBP85-99, PLP139-151, and MOG35-55, or placebo. The phenotype of immune cells in the skin was assessed using immunohistochemistry. Cell populations in lymph nodes were analyzed using flow cytometry. In peripheral blood immune cells, cytokine production was measured by enzyme-linked immunosorbent assay, and myelin-specific proliferation was examined by carboxyfluorescein succinimidyl ester-based assay. Results: We found that myelin peptides applied transdermally to MS patients activated dendritic Langerhans cells in the skin at the site of immunization and induced a unique population of granular dendritic cells in local lymph nodes. In the periphery, transdermal immunization with myelin peptides resulted in the generation of type 1, interleukin-10-producing regulatory T cells, suppression of specific autoreactive proliferative responses, and suppression of interferon-γ and transforming growth factor-β production. Interpretation: We demonstrate for the first time the immunoregulatory potential of transdermal immunization with myelin peptides in MS patients. Ann Neurol 2010;68:593-601 [ABSTRACT FROM AUTHOR]

The article presents results of experimental studies on mechanical properties of the polymer-composite material used in manufacturing firefighting helmets. Conducted studies included static and impact strength tests, as well as a shock absorption test of glass fiber-reinforced polyamide 66 (PA66) samples and firefighting helmets. Samples were subject to the impact of thermal shocks before or during being placed under a mechanical load. A significant influence of thermal shocks on mechanical properties of glass fiber-reinforced PA66 was shown. The decrease in strength and elastic properties after cyclic heat shocks ranged from a few to several dozen percent. The average bending strength and modulus during the 170 degree Celsius shock dropped to several dozen percent from the room temperature strength. Under these thermal conditions, the impact strength was lost, and the lateral deflection of the helmet shells increased by approximately 300%. Moreover, while forcing a thermal shock occurring during the heat load, it was noticed that the character of a composite damage changes from the elasto-brittle type into the elasto-plastic one. It was also proved that changes in mechanical and elastic properties of the material used in a helmet shell can affect the protective abilities of a helmet. [ABSTRACT FROM AUTHOR]

This study aimed to determine the relative densities of populations of particles emitted in fire experiments of selected materials through direct measurement and parametrization of size distribution as number (NSD), volume (VSD), and mass (MSD). As objects of investigation, four typical materials used in construction and furniture were chosen: pinewood (PINE), laminated particle board (LPB), polyurethane (PUR), and poly(methyl methacrylate) (PMMA). The NSD and VSD were measured using an electric low-pressure impactor, while MSD was measured by weighing filters from the impactor using a microbalance. The parametrization of distributions was made assuming that each distribution can be expressed as the sum of an arbitrary number of log-normal distributions. In all materials, except PINE, the distributions of the particles emitted in fire experiments were the sum of two log-normal distributions; in PINE, the distribution was accounted for by only one log-normal distribution. The parametrization facilitated the determination of volume and mass abundances, and therefore, the relative density. The VSDs of particles generated in PINE, LPB, and PUR fires have similar location parameters, with a median volume diameter of 0.2–0.3 µm, whereas that of particles generated during PMMA burning is 0.7 µm. To validate the presented method, we burned samples made of the four materials in similar proportions and compared the measured VSD with the VSD predicted based on the weighted sum of VSD of raw materials. The measured VSD shifted toward smaller diameters than the predicted ones due to thermal decomposition at higher temperatures. [ABSTRACT FROM AUTHOR]

Background: In patients with structural idiopathic scoliosis the body asymmetries involve the pelvis and the lower limbs; they are included in many theories debating the pathogenesis of idiopathic scoliosis. Methods: Hip joint range of motion was studied in 158 adolescent girls, aged 10-18 years (mean 14.2 ± 2.0) with structural idiopathic scoliosis of 20-83° of Cobb angle (mean 43.0° ± 14.5°) and compared to 57 controls, sex and age matched. Hip range of rotation was examined in prone position, the pelvis level controlled with an inclinometer; hip adduction was tested in five different positions. Results: In girls with structural scoliosis the symmetry of hip rotation was less frequent (p = 0.0047), the difference between left and right hip range of internal rotation was significantly higher (p = 0.0013), and the static rotational offset of the pelvis, calculated from the mid-points of rotation, revealed significantly greater (p = 0.0092) than in healthy controls. The detected asymmetries comprised no limitation of hip range of motion, but a transposition of the sector of motion, mainly towards internal rotation in one hip and external rotation in the opposite hip. The data failed to demonstrate the curve type, the Cobb angle, the angle of trunk rotation or the curve progression factor to be related to the hip joint asymmetrical range of motion. Conclusion: Numerous asymmetries around the hip were detected, most of them were expressed equally in scoliotics and in controls. Pathogenic implications concern producing a "torsional offset" of muscles patterns of activation around the spine in adolescent girls with structural idiopathic scoliosis during gait. [ABSTRACT FROM AUTHOR]

We compared the potential therapeutic effect of vaccination with DNA constructs encoding two encephalitogenic proteins, PLP and MOG, on the outcome of subsequent sensitization of EAE induced in SJL/J and C57/B6 mice. Early sensitization for EAE (4 weeks after DNA vaccination) caused recipient animals to develop enhanced disease with DNA-encoding PLP but not with DNA-encoding MOG. Late sensitization (more than 10 weeks) resulted in an amelioration of EAE in animals vaccinated with both PLP and MOG DNA constructs. These results, confirming the DNA-mediated ameliorating effect on EAE, also indicate significant differences in the kinetics of development of EAE tolerance in response to vaccination with different DNA-encoding myelin antigens. Since PLP and MOG require different MHC presentation and induce different EAE models, the results point to potential differences in immune system requirements for efficient DNA-induced amelioration of the autoimmune response. [Copyright &y& Elsevier]

With easy-to-process 3D printing materials and fast production, the quality of dental services can be improved. In the conventional procedure, the dentist makes temporary crowns directly in the patient's mouth, e.g., from the most commonly used bis-acrylic composites. Temporary crowns made directly in the office without the use of CAD/CAM are often of inferior quality, which directly results in impaired hygiene, poorer masticatory mechanics, greater deposition of plaque, calculus and sediment, and may adversely affect periodontal and gum health. The mechanical strength, resistance to aging and abrasion of 3D printing materials are higher than those of the soft materials used in conventional methods. This translates into durability. The patient leaves the surgery with a restoration of higher utility quality compared to the conventional method. The objective of the paper was to determine the influence of aging in artificial saliva of AM (additive manufacturing) orthodontic composites on their functional properties. For the purpose of the study, fillings well-known worldwide were selected. These were traditional UV-curable resins (M I, M II, M III, M V) and a hybrid material based on a UV-curable resin (M VI). Samples were stored in artificial saliva at 37 ± 1 °C in a thermal chamber for 6 months. Indentation hardness, frictional tests and sliding wear measurements were conducted. A comparison between various materials was made. Descriptive statistics, degradation coefficients, H2E, Archard wear and specific wear rate were calculated. The Weibull statistical test for indentation hardness was performed and Hertzian contact stresses for the frictional association were calculated for unaged (M I, M II, M III, M V, M VI) and aged (M I AS, M II AS, M III AS, M V AS, M VI AS) samples. M I exhibited the lowest average hardness among the unaged materials, while M III AS had the lowest average hardness among the aged materials. Comparably low hardness was demonstrated by the M I AS material. The coefficient of friction values for the aged samples were found to be higher. The lowest wear value was demonstrated by the M I material. The wear resistance of most of the tested materials deteriorated after aging. The M VI AS material had the highest increase in wear. According to the results provided, not only the chemical composition and structure, but also aging have a great impact on the indentation hardness and wear resistance of the tested orthodontic materials. [ABSTRACT FROM AUTHOR]

The paper presents the results of the research into the impact of impregnation of wood on its bending strength and elastic modulus under normal conditions and after thermal treatment and investigates its structural reliability. Pinewood, non-impregnated and pressure impregnated with a solution with SiO2 nanoparticles, was used in this research. The use of nanoparticles decreases the flammability of timber among others. Some of the tested samples were treated at 250 °C. This temperature corresponds to the boundary of the self-ignition of wood. This elevated temperature was assumed to be reached by a given speed of heating within 10 min, and then the samples were stored in these conditions for 10 and 20 min. The tests demonstrate that the bending strength of the impregnated wood was slightly improved, the impregnation did not impact the elastic modulus of the material in all such conditions, and the residual strength decreased less for the wood impregnated after being exposed to the elevated temperatures. The reliability analysis proves a positive effect of impregnation with a solution with SiO2 on the durability of wood, both after being exposed to normal and elevated temperatures. The distribution of the failure rates indicates a more intensive degradation of non-impregnated wood. The distribution of the survival function demonstrates a more probable non-destruction of impregnated wood after elevated temperature conditions. [ABSTRACT FROM AUTHOR]

This study discusses a quantitative fatigue evaluation of polymer–ceramic composites for dental restorations, i.e., commercial material (Filtek Z550) and experimental materials Ex-nano (G), Ex-flow (G). Their evaluation is based on the following descriptors: microhardness, scratch resistance, and sliding wear. In order to reflect factors of environmental degradation conditions, thermal fatigue was simulated with a special computer-controlled device performing algorithms of thermocycling. Specimens intended for the surface strength and wear tests underwent 104 hydrothermal fatigue cycles. Thermocycling was preceded by aging, which meant immersing the specimens in artificial saliva at 37 °C for 30 days. Microhardness tests were performed with the Vickers hardness test method. The scratch test was done with a Rockwell diamond cone indenter. Sliding ball-on-disc friction tests were performed against an alumina ball in the presence of artificial saliva. A direct positive correlation was found between thermocycling fatigue and microhardness. The dominant mechanism of the wear of the experimental composites after thermocycling is the removal of fragments of the materials in the form of flakes from the friction surface (spalling). Hydrothermal fatigue is synergistic with mechanical fatigue. [ABSTRACT FROM AUTHOR]

This study discusses a quantitative fatigue evaluation of polymer–ceramic composites for dental restorations, i.e., commercial (Filtek Z550) and experimental Ex-nano (G), Ex-flow (G). Their evaluation is based on the following descriptors: mechanical strength, elastic modulus and strain work to fracture. Supposed to reflect factors of environmental degradation conditions, thermal fatigue was simulated with a special computer-controlled device performing algorithms of thermocycling. The specimens intended for the strength test underwent 104 hydro-thermal fatigue cycles. This procedure of thermocycling was preceded by aging, which meant immersing the specimens in artificial saliva at 37 °C for 30 days. The strength tests after aging only and after aging and thermocycles were performed in line with the three-point flexural strength (TFS) test, specified in ISO 4049, and the biaxial flexural strength (BFS) test, specifically piston-on-three-ball in accordance with ISO 6872. Based on the results, it can be stated that composites with higher volume content of inorganic particles after aging only show higher strength than materials with lower filler particle content. For example, the average flexural bending strength of the Ex-flow (G) composite was about 45% lower than the value obtained for the Ex-nano (G) material. The residual strength after thermocycles is significantly lower for the experimental composites, whereas a smaller decrease in strength is recorded for the commercial composites. Decreases in strength were about 4% (Filtek Z550), 43% (Ex-nano (G)), and 29% (Ex-flow (G)) for the BFS test; and about 17% (Filtek Z550), 55% (Ex-nano (G)), 60% (Ex-flow (G)) for the TFS test. The elastic modulus of the experimental composites after only aging is higher (about 42%) than that of the commercial composite, but the elastic modulus of the commercial composite increases significantly after thermocycling. A descriptor known as strain work to fracture turns out to be a good descriptor for evaluating the hydro-thermal fatigue of the tested polymer–ceramic composites. [ABSTRACT FROM AUTHOR]

This paper discusses the problem of thermocycling effect of light-curing polymer–ceramic composites. Cyclic thermal shocks were simulated in laboratory conditions. As a rule, these loads were supposed to reproduce the actual conditions of biomaterials exploitation. Periodically variable stresses occurring in dental restorations are associated with the wear of cold and hot foods and beverages. They lead to changes in the properties of composites, including the properties of the surface layer. The aim of the work was to assess the impact of cyclic hydrothermal interactions on the properties of the surface layer of composites relevant to the operational quality. Two commercial materials manufactured by the world's leading producer (3M ESPE)—Filtek Z550, Filtek Flow and two experimental, micro-hybrid and flow type composites marked Ex-mhyb(P) and Ex-flow(P), respectively. All tests were carried out before and after hydro-thermal cycles (flowing water thermocycling). Micro-hardness test using the Vickers method, indentation hardness, and resistance to tribological wear in a ball–disc system in sliding friction conditions were performed. In addition, observations of the surface layer of composites on the SEM (scanning electron microscope) were carried out. It was noticed that semi-liquid composites, containing a smaller amount of filler, retain higher stability of mechanical and tribological properties of the surface layer under cyclic hydro-thermal loads. Coefficient of friction of samples after hydro-thermal cycles increased for micro-hybrid materials and Filtek Flow (FFlow) composite. In the case of Ex-flow(P) material, the coefficient of friction decreased. The microhardness of composites also changed, the variability of this size depended on the type of material. Composites with a higher content of filler particles were characterized by greater variability of microhardness under the influence of thermocycles. The resistance to tribological wear also changed in a similar way. Composites containing higher volume fraction of inorganic filler showed higher tribological wear after thermocycling. The wear resistance of flow composites changed to a lesser extent, after thermocycling increased. The paper also showed that, in real kinematic nodes, the surface layer of light-curing ceramic–polymer composites is exposed to significant non-tribological (erosive, thermal, and chemical) defects that synergize with tribological ones. In slip pairs loaded dynamically, under mixed friction conditions, tribological wear of PMCCs (polymer matrix ceramic composites) is manifested by spalling (spalling of the material flakes, in particular the polymer phase) and pitting (crushing wear caused by wear products, in particular large filler particles or clusters, previously adhesively extracted). [ABSTRACT FROM AUTHOR]

This study aimed to determine the relative densities of populations of particles emitted in fire experiments of selected materials through direct measurement and parametrization of size distribution as number (NSD), volume (VSD), and mass (MSD). As objects of investigation, four typical materials used in construction and furniture were chosen: pinewood (PINE), laminated particle board (LPB), polyurethane (PUR), and poly(methyl methacrylate) (PMMA). The NSD and VSD were measured using an electric low-pressure impactor, while MSD was measured by weighing filters from the impactor using a microbalance. The parametrization of distributions was made assuming that each distribution can be expressed as the sum of an arbitrary number of log-normal distributions. In all materials, except PINE, the distributions of the particles emitted in fire experiments were the sum of two log-normal distributions; in PINE, the distribution was accounted for by only one log-normal distribution. The parametrization facilitated the determination of volume and mass abundances, and therefore, the relative density. The VSDs of particles generated in PINE, LPB, and PUR fires have similar location parameters, with a median volume diameter of 0.2-0.3 µm, whereas that of particles generated during PMMA burning is 0.7 µm. To validate the presented method, we burned samples made of the four materials in similar proportions and compared the measured VSD with the VSD predicted based on the weighted sum of VSD of raw materials. The measured VSD shifted toward smaller diameters than the predicted ones due to thermal decomposition at higher temperatures.

The article presents results of experimental studies on mechanical properties of the polymer-composite material used in manufacturing firefighting helmets. Conducted studies included static and impact strength tests, as well as a shock absorption test of glass fiber-reinforced polyamide 66 (PA66) samples and firefighting helmets. Samples were subject to the impact of thermal shocks before or during being placed under a mechanical load. A significant influence of thermal shocks on mechanical properties of glass fiber-reinforced PA66 was shown. The decrease in strength and elastic properties after cyclic heat shocks ranged from a few to several dozen percent. The average bending strength and modulus during the 170 degree Celsius shock dropped to several dozen percent from the room temperature strength. Under these thermal conditions, the impact strength was lost, and the lateral deflection of the helmet shells increased by approximately 300%. Moreover, while forcing a thermal shock occurring during the heat load, it was noticed that the character of a composite damage changes from the elasto-brittle type into the elasto-plastic one. It was also proved that changes in mechanical and elastic properties of the material used in a helmet shell can affect the protective abilities of a helmet.

Purpose: For splinting or designing adhesive bridges, reconstructive composite structures with increased mechanical properties owing to embedded reinforcement fibres are used. The aim of this article was to determine the influence of glass and aramid fibres on the mechanical strength of composites reinforced with these fibres., Methods: Two polymer-ceramic microhybrid materials: Boston and Herculite were tested. Three types of reinforcement fibres were used: aramid (Podwiązka) with a single layer weave, a single layer weave glass fibre (FSO) and triple layer weave glass fibre (FSO evo). Tests were conducted in accordance with the requirements of ISO 4049:2009. The following material types were chosen for research: Boston, Boston + Podwiązka, Herculite, Herculite + Podwiązka, Herculite + FSO and Herculite + FSO evo. The scope of research included: flexural strength B, bending modulus of elasticity εB and work to failure of the reinforced composite Wfb. Additionally, microscopic observations of fracture occurring in samples were made., Results: In comparison: the Herculite (97.7 MPa) type with the Herculite + FSO evo (177.5 MPa) type was characterized by the highest strength. Fibre reinforcement resulted in decreasing the elasticity modulus: Herculite + reinforcement (6.86 GPa; 6.33 GPa; 6.11 GPa) in comparison with the Herculite (9.84 GPa) and respectively Boston + reinforcement (10.08 GPa) as compared with the Boston (11.81 GPa)., Conclusions: Using glass fibres increases flexural strength of the test composites. Using aramid fibres does not change their strength. The elasticity modulus of the reinforced reconstructive structures decreases after application of either type of fibres. However, their resistance to the crack initiation increases.