Experimental investigation of seismic behaviour of the ancient Protiron monument model

Throughout history, dry-stone masonry structures have been strengthened with different types of metal connectors in order to increase their resistance which enabled their survival, especially in the seismically active area. One such example is the ancient Protiron monument placed in the Peristyle square of the Diocletian's Palace in Split, Croatia. The Protiron was built at the turn of the 3rd century as a stone masonry structure with dowels embedded between its base, columns, capitals and broad gable. The stone blocks in the broad gable were connected by metal clamps during restoration at the beginning of the 20th century. In order to study the seismic performance of the strengthened stone masonry structures, an experimental investigation of seismic behaviour of a physical model of the Protiron was performed on the shaking table. The model was designed as a true replica model in a length scale of 1:4 and exposed to representative earthquake with increasing intensities up to collapse. The tests provided a clear insight into system behaviour, damage mechanism and failure under intensive seismic load, especially into the efficiency of connecting elements, which had a special role in increasing seismic resistance and protection of the structure from collapse. Additionally, this experiment provided valuable data for verification and calibration of numerical models for strengthened stone masonry structures.     

Photometric and spectrophotometric observations of Nova Delphini 1967

Photographic, photovisual and photoelectric (V) observations of Nova Delphini 1967 were made from August 8 to October 31 (Table I, Figure 1). Simultaneously spectrophotometric measurements of the continuum were made on objective prism exposures extending to November 26, and spectrophotometric gradients derived (Tables II and III; Figures 3, 4, and 5). The continuum of Nova near its flat maximum is close to that of an early-type star in contrast to late-type absorptionline spectrum.     

An analysis of close binaries (CB) based on photometric measurements (V)

The author considers the current problematics in the determination of the orbital and physical parameters for active close binaries (CB) of W Ser type based on the interpretation of photometric observations. In the particular case one analyses the light curves of CB RX Cas in the framework of the accretion-disc model explained in the second paper of this series (Djuraevi, 1992a). The change of the light curves with that of the system's physical-activity phase is analysed and the orbital and physical parameters of the system are determined for the maximum, minimum and the transition regime of the physical activity by applying the inverse-problem method described in the third paper of the series (Djuraevi, 1992b). In the paper a graphical illustration of the solutions obtained is also given.     

3rd Regional Symposium on Landslides in the Adriatic-Balkan Region (3rd ReSyLAB)—a final report

The 3rd Regional Symposium on Landslides in the Adriatic-Balkan Region (3rd ReSyLAB) was held in Ljubljana, Slovenia, from June 11 to 13, 2017, with 70 participants from nine countries (Austria, Bosnia and Hercegovina, Croatia, Czech Republic, Italy, Republic of Macedonia, Serbia, Slovenia, Spain)—scientists, engineers, researchers, students, experts, politicians, and other decision-makers working in the area of landslide risk reduction in the region. The ReSyLAB is a biannual event organized by the Adriatic-Balkan Network of the International Consortium on Landslides (ICL ABN). Being an important form of activities of this ICL regional network comprising of six ICL members from four countries, it was also a contribution of the International Consortium on Landslides (ICL) to the implementation of the Sendai Framework for Disaster Risk Reduction 2015–2030. This article reports on the main outcomes of the 3rd ReSyLAB Symposium. Altogether, 41 abstracts were published in the symposium book of abstracts, and the symposium proceedings with over 20 reviewed full papers are under preparation to be printed early in 2018. During the 3rd ReSyLAB, a five invited keynote lectures have been presented, and 28 oral presentations are given to the audience. An important part of the symposium was a Round Table entitled “Enhancing cooperation between landslide research community and end users.” On the last day of the symposium, over 30 experts participated in two post-symposium study tours in Slovenia.     

Size-differential feeding in Pinna nobilis L. (Mollusca: Bivalvia): Exploitation of detritus,phytoplankton and zooplankton

The endangered fan shell Pinna nobilis is a large bivalve mollusc (<120 cm shell length) endemic to the Mediterranean that lives one-third buried in soft substrata, generally in shallow coastal waters. We hypothesised that P. nobilis of different sizes would ingest different food sources, because small fan shells will inhale material from closer to the substratum than do large fan shells. We studied stomach contents and faeces of 18 fan shells, 6 small (mean 23.0 cm length), 6 medium-sized (mean 41.5 cm length) and 6 large (mean 62.7 cm length) living in a small area of a low-energy coastal detritic bottom characterised by mud, sand and macroalgae at Mali Ston Bay, Croatia. We found that all P. nobilis ingested copious quantities of undetermined detritus (probably at least 95% of ingested material), phytoplankton, micro and mesozooplankton and pollen grains. Large P. nobilis stomach contents showed a preponderance of water column calanoid copepods, while small fan shells had higher numbers of bivalve larvae. All fan shells took in high numbers of harpacticoid copepods that are benthonic, feeding on microbial communities of detritus and benthic vegetation. There was also a significant selection of phytoplankton species, some apparently occurring between inhalation and ingestion. The stomach contents of small P. nobilis had a higher organic matter content than either medium-sized or large fan shells; this indicated that small fan shells ingested detritus of higher organic content than did larger P. nobilis. As the faeces of all P. nobilis had similar organic matter content, this also indicates higher assimilation efficiencies in small fan shells. The demonstration of differential dietary selectivity by different sized animals has implications for future trophic studies of this endangered species. This study also provides the first demonstration of predation on zooplankton by P. nobilis.     

Characterization of atmospheric surfactants in the bulk precipitation by electrochemical tools

Characterization of atmospheric surfactants in bulk precipitations was carried out by adsorption study at the mercury electrode/solution interface using phase sensitive AC voltammetry. The structure and permeability of the adsorbed organic films at the mercury electrode was tested using the redox processes of lead and cadmium ions as electrochemical tools. The effects of organic matter from the bulk precipitations (rainwater and melted snow) were compared to those obtained for aqueous solutions of model substances: aromatic hydrocarbon (naphtalene), anionic surfactant (sodium dodecylbenzene sulfonate, NDBS), protein (albumine) and selected model substances suggested to be representative of water soluble organic compounds (WSOC) in atmospheric water (monocarboxylic, dicarboxylic, and polyacidic compounds and levoglucosan). It was found that substances like humic acid and 3-hydroxybutanoic acid may play an important role in atmospheric heterogeneous chemistry because of their surface active potential.     

An analysis of close binaries (CB) based on photometric measurements (VII)

The paper is devoted to the actual problematics in the determination of orbital and physical parameters of active CB on the basis of the interpretation of photometric observations. One solves the problem in two stages: by obtaining a synthetic light curve in the case when the parameters of the corresponding CB model (Djuraevi, 1992a) are given a priori (direct problem) and by determining the parameters of the given model for which the best fit between the synthetic light curve and the observations is achieved (inverse problem) (Djuraevi, 1992b). In this paper, the above procedure is applied to a particular case of an interpretation of CB light curves AU Ser and RV Corvi.     

Evaluation of the Mytilus galloprovincialis Lam. digestive gland metallothionein as a biomarker in a long-term field study: seasonal and spatial variability

A study was made of seasonal and spatial variability of metallothionein (MT) concentrations, determined spectrophotometrically in the soluble fraction of the digestive gland of mussels Mytilus galloprovincialis, collected between 1999 and 2001 from several coastal and estuarine locations along the central Eastern Adriatic coast (Croatia). The seasonal influence on the MT and metal concentrations (higher values in winter-spring season, than in summer-autumn season) is more pronounced than the local site-specific influence. Furthermore, within each season a significant site-specific dependence on the MT and trace metal variations can be detected. An inverse relationship of mussel condition index (CI) and temperature with MT and trace metals levels indicates the influence of food abundance and mussel annual reproductive cycle. Substantially higher concentrations of both MT and Cd were recorded in mussels inhabiting estuarine locations, possibly indicating a markedly higher Cd bioavailability at these locations. The positive correlations obtained between MT and Cd in all seasons except autumn support an argument for application of digestive gland MT as a biomarker of Cd exposure, providing evidence for assessing the most appropriate season for mussel sampling.