This paper aims to assess the influence of clogging on paving material (pervious concrete) drainage characteristics as well as the influence of the properties of an unbound base layer on drainage ...characteristics of the whole paving system. The clogging influence has been studied measuring the drainage characteristics on pervious concrete flags before and after their clogging, according to ASTM C1701-09. Additionally, the drainage characteristics of uncontaminated pervious concrete as a paving material was assessed using the falling head method. To assess the influence of properties of an unbound base course (UBC) on drainage characteristics of the whole paving system, the unbound base layer was compacted in two different levels of compaction and the drainage characteristics were measured (according to ASTM C1701-09). It is concluded that pervious concrete prepared with a smaller aggregate fraction is more prone to clogging. Regarding the influence of UBC, it is important to find a balance between pervious concrete infiltration and UBC exfiltration rate, particularly in a case of pervious concrete flags made of coarse aggregate.
Agricultural biomass has great bioenergy potential due to its availability, and it is a carbon-free energy source. During biomass incineration, biomass ash is formed, which is still considered as a ...waste without proper disposal and management solutions. Various biomass ash utilization options were investigated, mainly concerning engineering issues (the mechanical characterization of newly produced building materials or products), and there is a lack of knowledge of environmental issues arising from this “waste” material utilization in civil engineering practice. The main aim of this research is discussion of a different agricultural biomass characteristics as a fuel, the impact of agricultural biomass ashes (ABA) on the mechanical properties of stabilized soil with a particular emphasis on the environmental impacts within this kind of waste management. The results of this study indicate improved geotechnical characteristics of low-plasticity clay stabilized by lime/ABA binder. In addition to mechanical characterization for materials embedded in road embankments and subgrades, appropriate environmental risk assessment needs to be performed, and the results of this study indicate that the amount of ABAs added to the soil for roadworks should not have adverse effects on the soil fauna in the surrounding environment.
The aim of this study was the verification of unmanned aerial system (UAS) application in vehicle swept path analyses by analysing the advantages and disadvantages and comparing field test results ...with two software solutions. In this study, swept-path analyses were performed for two vehicle types and two turning angles. UAS images were used to extract the vehicle swept path and the results were compared with two commonly used swept-path analysis software. The results indicated larger deviations between the swept paths for an angle of 125° for a light truck. For both analysed vehicles and turning angles, larger deviations were observed for the outermost point trajectory. Passenger cars occupy less space performing 125° turns than software analysis predicts, indicating that they are on the safe side when designing vehicle manipulative surfaces. For the analysed light truck, a larger turning radius was observed than the predicted for a 125° turning angle, which may be caused by the approaching and turning speeds under which the test was performed. Finally, while the UAS recording process is relatively simple and fast, data processing is demanding and time-consuming. To fulfil its full potential within swept path analyses, UAS needs to be complemented by proper data analysis software solutions for faster and more accurate swept path extraction, which would improve and rationalise the traffic area designing process.
During road construction, granular materials for the unbound base course (UBC) and cement-bound base course (CBC) are mostly compacted by vibratory rollers. A widespread laboratory test for ...determining the optimal moisture content (OMC) and maximum dry density (MDD) of the mixture for installation in UBC and CBC is the Proctor test. Considering that the Proctor test does not produce any vibrations during compaction, this paper compares the Proctor test and the vibrating hammer test. The examination was conducted on UBC and CBC with varying cement content and aggregate types. All mixtures were compacted by both methods with the aim of determining the compaction and strength characteristics. The results indicated the high comparability of the two test methods for mixtures with natural aggregate in terms of MDD, OMC, density and strength characteristics (California bearing ratio (CBR) for UBC and 28-day compressive strength for CBC). For mixtures with higher cement content, the OMC difference depending on the laboratory compaction method used can be significant, so the laboratory compaction method should be chosen carefully, particularly for moisture-susceptible materials. This paper also reveals that by increasing the proportion of rubber in the mixture, the compaction and strength characteristics differ significantly due to the compaction method. Therefore, when using alternative and insufficiently researched materials, the compaction method should also be chosen carefully.
Vancomycin-resistant enterococci (VRE), especially
Enterococcus faecium
, have emerged as significant nosocomial pathogens and patients with impaired host defenses are at a particular risk of VRE ...infection. The most common occurrence is asymptomatic colonization of the gastrointestinal tract that can persist for a long time and serve as a reservoir for transmission of VRE to other patients. We present a case of a patient who was diagnosed with acute myelogenous leukemia and suffered from bone marrow aplasia following induction therapy. The patient received prolonged broad-spectrum antimicrobial therapy. During hospital stay, the patient developed
Clostridium difficile
infection (CDI) and was found to be colonized with a strain of
Enterococcus faecium
resistant to vancomycin during therapy for CDI. This case also highlights the role of risk factors that could contribute to development of resistance, particularly CDI. Early detection of VRE colonization or infection is a crucial component in hospital program designed to prevent transmission of nosocomial infections. Surveillance cultures of such patients should be mandatory.
The application of recycled rubber in cement bound base courses (CBC) has recently become a subject of research. There are several advantages of the application of rubber in CBC. One is the ...environmental benefit considering the major problem of disposing of end-of-life tires (ELT), whose number is rapidly increasing in the modern world. On the other hand, CBC is known as the most rigid course of pavement, and is very prone to cracking. Rubber has the potential to reduce the cracking, which is another benefit of its use in those courses. This paper presents laboratory research on a reference mixture and five rubberized mixtures with different fractions of recycled rubber. The mixtures are modified with 20 % of rubber as a replacement for sand. Three fractions of granulated rubber and two fractions of rubber threads are used. The research encompasses the impact of rubber of different sizes and shapes on the Proctor elements of the CBC mixture. Furthermore, specific surface area (SSA) and SEM analysis is presented. The SSA value was found to be the most influential factor on the optimal moisture content (OMC) values, which is confirmed by SEM images. SEM analysis showed that larger particles have a flatter surface and demand higher water content. Furthermore, the rubber particle shape has a greater impact on the mixture MDD compared to the particle size, while the rubber particle size has a greater effect on the OMC compared to the rubber particle shape. Finally, the effect of the rubber particle size and shape on the OMC and MDD can be neglected and the production of cement bound aggregate incorporating waste rubber can be designed and built using reference values of the OMC and MDD.
The rapid and ongoing spread of carbapenemase-producing
has led to a global health threat. However, a limited number of studies have addressed this problem in the marine environment. We investigated ...their emergence in the coastal waters of the central Adriatic Sea (Croatia), which are recipients of submarine effluents from two wastewater treatment plants. Fifteen KPC-producing
(nine
, four
and two
) were recovered, and susceptibility testing to 14 antimicrobials from 10 classes showed that four isolates were extensively drug resistant (XDR) and two were resistant to colistin. After ERIC and BOX-PCR typing, eight isolates were selected for whole genome sequencing. The
isolates belonged to serotype O21:H27 and sequence type (ST) 2795, while
isolates were assigned to STs 37 and 534. Large-scale genome analysis revealed an arsenal of 137 genes conferring resistance to 19 antimicrobial drug classes, 35 genes associated with virulence, and 20 plasmid replicons. The isolates simultaneously carried 43-90 genes encoding for antibiotic resistance, while four isolates co-harbored carbapenemase genes
and
. The
was associated with IncL-type plasmids in
and
. Importantly, the
in four
isolates was located on ~40 kb IncP6 broad-host-range plasmids which recently emerged as
vesicles, providing first report of these
-bearing resistance plasmids circulating in
in Europe. This study also represents the first evidence of XDR and potentially virulent strains of KPC-producing
in coastal waters and the co-occurrence of
and
carbapenemase genes in this species. The leakage of these strains through submarine effluents into coastal waters is of concern, indicating a reservoir of this infectious threat in the marine environment.
This paper investigates the durability of cement-bound layers with steel slag as a partial aggregate replacement. Mixtures with various amounts of slag and cement are investigated for their ...durability after freeze-thaw cycles and exposure to de-icing agent. Optical microscopy analysis is conducted as a method for assessing the behaviour of low-strength material in order to determine why the application of slag resulted in greater compressive strength and durability properties. It was shown that this method is suitable for providing more details and insights into the material's internal structure. All the mixtures show a loss in compressive strength after exposure to freeze-thaw cycles and de-icers, but this loss is more pronounced in mixtures with gravel-only aggregates. A strong linear correlation is obtained between 28-day compressive strength and retained compressive strength after 10 freeze-thaw cycles. The main conclusion of the research presented here is that steel slag aggregate presents good potential for use in adverse climates, and it is possible to predict the freeze-thaw resistance of cement-bound aggregate on the basis of compressive strength.
Vancomycin-resistant Enterococcus faecium (VREfm) is an opportunistic pathogen among the highest global priorities regarding public and environmental health. Following One Health approach, we ...determined for the first time the antibiotic resistance and virulence genes, and sequence types (STs) affiliation of VREfm recovered simultaneously from marine beach waters, submarine outfall of a wastewater treatment plant and an offshore discharge of untreated sewage, and compared them with the surveillance VREfm from regional university hospital in Croatia to assess the hazard of their transmission and routes of introduction into the natural environment. Importantly, VREfm recovered from wastewater, coastal bathing waters and hospital shared similar virulence, multidrug resistance, and ST profiles, posing a major public health threat. All isolates carried the vanA gene, while one clinical isolate also possessed the vanC2/C3 gene. The hospital strains largely carried the aminoglycoside-resistance genes aac(6′)-Ie-aph(2″)-Ia, and aph(2″)-Ib and aph(2″)-Id, which were also predominant in the environmental isolates. The hyl gene was the most prevalent virulence gene. The isolates belonged to 10 STs of the clonal complex CC17, a major epidemic lineage associated with hospital infections and outbreaks, with ST117 and ST889 common to waterborne and hospital isolates, pointing to their sewage-driven dissemination.
To gain better insight into the diversity of accompanying taxons in the surveyed water matrices, microbiome taxonomic profiling was carried out using Illumina-based 16S rDNA sequencing and their resistome features predicted using the PICRUSt2 bioinformatics tool. An additional 60 pathogenic bacterial genera were identified, among which Arcobacter, Acinetobacter, Escherichia-Shigella, Bacteroides and Pseudomonas were the most abundant and associated with a plethora of antibiotic resistance genes and modules, providing further evidence of the hazardous effects of wastewater discharges, including the treated ones, on the natural aquatic environment that should be adequately addressed from a sanitary and technological perspective.
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•Hospital and environmental vancomycin-resistant Enterococcus faecium were studied.•VREfm enter marine environment by outfalls of treated and untreated wastewater.•VanA genotype predominates among hospital and waterborne isolates in Croatia.•Hospital and environmental VREfm carry similar virulence and resistance genes.•Microbiome analysis revealed accompanying pathogenic taxa and resistance genes.
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