Koncentracija metala u vodi i sedimentu reke Dunav

Voda je osnov opstanka živog sveta koji je u njoj i nastao. Dve trećine zemljine površine je pod vodom. Bez obzira na značaj vode na opstanak živog sveta ljudska vrsta prema vodi nema odgovarajući odnos. O tome govore podaci o zagađenju okeana, mora, vodotokova (reke, potoci) i jezera. Antropogeno zagađenje vode, dakle, poreklom od čoveka, javlja se kao posledica direktnog ili indirektnog ispuštanja zagađivača u vodu, bez adekvatnog postupka sa štetnim i opasnim jedinjenjima. Najčešći zagađivači vode posledica su otpadnih voda i voda koje dolaze sa površina zemlje (naročito obradivih površina). Zagađenost vode je blisko povezana za povećanim potrebama stanovništva za vodenim resursima. Povećane potrebe rastu sa porastom stanovništva, razvoja privrede i tehnologije. Veća potrošnja vode znači i veću količinu otpadnih voda. Dospevanjem u reke otpadne vode menjaju fizička (boja, miris, ukus, providnost), hemijska (sastav) i biološka svojstva (živi svet reka). Naša zemlja nema odgovarajuće propise za procenu kvaliteta sedimenta pa se, zbog toga, koriste standardi kvaliteta prema kanadskom zakonodavstvu, preporuke ICPDR-a (International Commission for the Protection of the Danube River ), a pojedini parametri se procenjuju korišćenjem holandske metodologije. Prema kanadskom zakonodavstvu definisane su dve vrednosti: niža vrednost ISQGs (Interim Sediment Quality Guideline) predstavlja privremene preporuke koje su dobijene teorijskim putem i iznad kojih je moguć uticaj na akvatične organizme, dok je druga, viša, vrednost PEL (Probable Effect Level), vrednost iznad koje je uticaj na akvatične organizme verovatan. Poređenjem sa kanadskim preporukama, sadržaj žive je prekoračen na skoro svim ispitanim lokalitetima, prema ISQG vrednosti. Viša PEL vrednost ukazuje na verovatno prisutne negativne toksične efekte na akvatične organizme i sedimente u dva ispitivana profila u Dunavu (profil A i profil B). Pojava žive u sedimentu je posledica ispuštanja industrijskih otpadnih voda (naročito iz pogona za proizvodnju hlora), upotrebe živinih pesticida za zaštitu semena, upotrebe živinih jedinjenja u upaljačima eksplozivnih sredstava (posledice ratnog konflikta 1999.godine) i upotreba žive u mernim uređajima (u toku razaranja industrijskih postrojenja za vreme konflikta 1999. godine uništen je deo ove merne opreme). Arsen je poznat po negativnim ekotoksičnim efektima, a negov sadržaj u sedimentu reke Dunav nije bio iznad ICPDR vrednosti. Sadržaj drugih teških metala, cinka, bakra, kadmijuma i olova (profil B) je bio u ispod vrednosti propisane ICPDR. Kako se sam proces zagađivanja vode teško može sprečiti, zaštita voda, prvenstveno, je usmerena na smanjenje uticaja, a u najboljem slučaju, potpuno uklanjanjanje uticaja teških metala. To se postiže kroz opšte ekološke (radne akcije, ekološki aktivizam) kao i specifične mere (obrazovanje, sredstva javnog informisanja). Najvažnije je utvrđivanje kvaliteta vode i mogućnosti vodotoka da primi otpadne vode, registovanje svih mogućih zagađivača (njihova lokacije i stepen zagađivanja), obavljanje stalnih kontrola otpadnih voda u blizini vodotokova, prečišćavanje otpadnih voda i izmeštanje industrije na mesta na kojima će zagađivanje biti minimalno

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at √s = 13 TeV

A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb−1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level

Search for top squark pair production in a final state with two tau leptons in proton-proton collisions at root s=13 TeV

A search for pair production of the supersymmetric partner of the top quark, the top squark, in proton-proton collision events at s = 13 TeV is presented in a final state containing hadronically decaying tau leptons and large missing transverse momentum. This final state is highly sensitive to high-tan beta or higgsino-like scenarios in which decays of electroweak gauginos to tau leptons are dominant. The search uses a data set corresponding to an integrated luminosity of 77.2 fb(-1), which was recorded with the CMS detector during 2016 and 2017. No significant excess is observed with respect to the background prediction. Exclusion limits at 95% confidence level are presented in the top squark and lightest neutralino mass plane within the framework of simplified models, in which top squark masses up to 1100 GeV are excluded for a nearly massless neutralino.Peer reviewe

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

Combination of CMS searches for heavy resonances decaying to pairs of bosons or leptons

CMS Collaboration: et al.A statistical combination of searches for heavy resonances decaying to pairs of bosons or leptons is presented. The data correspond to an integrated luminosity of 35.9 fb collected during 2016 by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data are found to be consistent with expectations from the standard model background. Exclusion limits are set in the context of models of spin-1 heavy vector triplets and of spin-2 bulk gravitons. For mass-degenerate W′ and Z′ resonances that predominantly couple to the standard model gauge bosons, the mass exclusion at 95% confidence level of heavy vector bosons is extended to 4.5 TeV as compared to 3.8 TeV determined from the best individual channel. This excluded mass increases to 5.0 TeV if the resonances couple predominantly to fermions.Individuals have received support from the Marie-Curie program and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 752730, and 765710 (European Union); the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509 and the Programa Severo Ochoa del Principado de Asturias