Institut IGH (Croatia)

Abstract Chronic hepatitis B virus infection persists as a global health crisis, driving life-threatening liver pathologies such as hepatocellular carcinoma. Central to HBV’s resilience is the covalently closed circular DNA (cccDNA), a viral minichromosome that orchestrates viral transcription and sustains infection. Dissecting cccDNA-driven transcription remains a formidable challenge due to the dense overlap of viral open reading frames, which generates RNA transcripts with shared sequences, complicating precise quantification and hindering efforts to unravel HBV’s transcriptional regulation. To address this bottleneck, we developed a multiplexed assay named ddPCR for Overlapping Transcripts (ddOTs) capable of simultaneously quantifying all major HBV RNA species, including splice variants, with unprecedented specificity and sensitivity. This method overcomes current limitations by leveraging the high-resolution power of ddPCR to deconvolute overlapping transcripts, enabling direct interrogation of individual promoter/enhancer activities and RNA stability. By offering a cost-effective, scalable solution for precise RNA profiling in rare biological samples, this breakthrough tool unlocks new avenues for exploring cccDNA biology and accelerating antiviral drug development.

The sedimentation of drainage canals is a common process and its intensity depends on several geographical and hydrological factors. Drainage canal sediments are frequently polluted by heavy metals or other pollutants; they need to be periodically dredged and ultimately, have to be safely disposed of. Furthermore, pollution in smaller drainages may go undetected because under the Water Framework Directive (Directive 2000/60/EC), catchment areas < 10 km2 do not require monitoring. We investigated the hypothesis that water resources of small sub-catchments exposed to agricultural pollutants accumulate sediment for a longer period (several years) and severely enhance environmental risks. We analyzed the data on sediment mobility in drainage canals for a small lowland catchment in Croatia during 2013–2017. We conducted sediment transport modelling for actual precipitation episodes of a 10-year return period and design precipitation of a 50-year return period. The results indicated that sediments and associated copper pollution persist at the canal bottom for several years, which increases the risk of polluting groundwater and the environment in general. Only copper present at the maximum downstream section of the canal has the possibility of moving to the recipient stream and would only be detected in catchment areas bigger than 10 km2. We proved that smaller water bodies evaluated according to monitoring standards prescribed for the closest larger water can enhance environmental risks.

Seven different concrete mixtures were prepared to estimate the possibility of using pervious concrete for light traffic urban areas. The total porosity, density, compressive strength, flexural strength, abrasion resistance, and traffic noise absorption capacity were tested for all the concrete specimens. The first mixtures corresponded to a standard dense concrete mixture (M1), while the other mixtures were pervious concrete mixtures involving two different types of aggregates (dolomite and steel slag) and different proportions of aggregate fractions. The total porosity, density, compressive strength, flexural strength, abrasion resistance, and traffic noise absorption capacity were tested in the case of all concrete specimens. The total porosity increased, whereas the compressive and flexural strength decreased simultaneously with an increase in the share of coarse aggregate fractions. The abrasion resistance and acoustic characteristics improved if only a fraction of the aggregate was used in pervious concrete preparation.

Optimisation of maintenance planning is an important part of bridge management. The efficiency of condition assessment process is directly influencing the choice of repair and maintenance technique, i.e. measures which have to be undertaken. This paper examines the effect of two opposing maintenance strategies, corrective and preventive maintenance. The condition rating and planned maintenance costs for structural elements of bridges at different ages are compared. In case studies from Croatia and the Netherlands, data from previously performed inspections was compiled in order to correlate age, condition and costs for structural elements. The case studies have been used to assess the impact of different maintenance policies (corrective vs. preventive) on the occurred maintenance costs.

Strateška procjena utjecaja na okoliš predstavlja jedan od upravljačkih alata pri integralnom upravljanju obalnim područjem. Prema zakonodavstvu Republike Hrvatske, strateška procjena utjecaja na okoliš obvezna je za većinu strategija, planova i programa. Principi integralnog upravljanja obalnim područjem, kao što su interdisciplinarnost, usklađenje sektorskih interesa i ekosustavni pristup svoju realizaciju mogu postići kroz stratešku procjenu utjecaja na okoliš u sektorima relevantnim za obalno područje, kao i u prostornim planovima jadranskih županija. Polazeći od specifičnih obilježja istočne obale Jadrana, rad daje pregled zakonske regulative u Republici Hrvatskoj vezane uz integralno upravljanje obalnim područjem i stratešku procjenu utjecaja na okoliš, kao i pregled sektorskih strateških dokumenata i županijskih prostornih planova relevantnih za obalno područje. Donosi se također kratki pregled dosadašnje primjene strateške procjene utjecaja na okoliš u Republici Hrvatskoj. Prednosti i nedostatci primjene strateške procjene utjecaja na okoliš, kao jednog od alata integralnog upravljanja obalnim područjem, predstavljeni su SWOT analizom.

Study of physical-mechanical properties of hardened concrete was made as a part of the final work at the Polytechnic of Zagreb. Cube concrete specimens were made using various concrete recipes. Three kinds of cement and two superplastificators were used with various w/c ratios. Compressive strength of concrete was tested on 126 specimens of different ages. Results were used to determine functional dependence of compressive strength on time, and thus an estimate of the compressive strength based on the early strength. The expression obtained is compared with Eurocode and ACI 209. Also the functional dependence of w / c ratio and compressive strength of concrete is given.

The formulation and resolution of a bi-level transit network design problem in an intermodal network environment is presented in the paper. The lower level of this bi-level problem is a combined mode-choice/assignment intermodal network equilibrium with asymmetric link interactions and variable transit frequencies. The upper level is a transit ridership maximization problem, with the number of transit vehicles allocated toward transit routes as a design variable. A sensitivity based algorithm is proposed for resolution of the bi-level problem.

In the western region of Croatia, small fractions of recycled aggregate have similar properties like small fractions of crushed natural aggregate regarding grain shape and fines content. The focus of this research was to analyze possibilities of using small fractions of recycled aggregate in the cases where only poor quality natural sand is available for production of concrete. The research is based on available data from concrete production in wider region of western Croatia and also on experimental research carried out on several series of mortar samples prepared with recycled and natural fine aggregate. Influence of two-phase mixing method on mortar properties in fresh and hardened state was analyzed. Based on the results of testing, it is concluded that small recycled concrete aggregate may be suitable for use in the concrete production. In concrete mix design, it is recommended to decrease absolute aggregate absorption determined according to HRN EN 1097 and to use double-mixing method, due to its positive effect on the consistency and strength.