Littérature scientifique sur le sujet « Physico-Chemical Parametres »

Sedimentation is a process that erodes and transports soil particles into water bodies. Sediment reduces storage capacity, lifespan of stream basins, water quality.The Ubelle stream was 465m length, 25 to 45m width and 60m depth. The stream basin served the people of the community as a multipurpose stream for fishing, swimming, laundry and sources of water for domestic uses. Soil analysis showed, excess sediment has been transported into the stream basin within a period of 15 years. Siltation occupied 57.07m, out of the 60m, leaving 1.00 to 2.93m in depth.This reduced the water storage and w a t e r q u a l i t y . Soil samples analysis w a s dominated by very fine sand, ranging between 84.08 to 85.57 %. These indicate silty-clay soils silted the stream basin. Porosity ranged from 6 to 14%. This is low, indicating the soil is dense with low volume of voids relative to the volume of solids; meaning, it is more porous, less cohesive; and prone to erosive forces. Bulk density ranged from 2.27- 2.50g/cm 3 . This is high compared to average standard values of 1.33g/cm 3 . High bulk density reduces infiltration of water into the soil and increases overland flow resulting in erosion. Therefore the stream basin was silted by silty-clay soils. Being a multipurpose stream; the physico-chemical parametres of the stream water was not suitable for drinking, but suitable for aquaculture. Erosion control measures like vegetative covers, afforestation along the river bed will avoid more soil loss. The stream water should be treated before use for drinking and other domestic uses.

The coastal area of Albania is characterized by specific constructions, parts of which are the coastal wetlands and its lagooning. Lagoons are very specific bodies of water that acquire an interesting status along with the indisputable values they have. The value of knowing the physico-chemical properties of the water of the Narta Lagoon is related to many processes that occur within the lagoon and in the environments around it. The study was carried out on the Narta Lagoon to identify the chemical and physical characteristics of the water. For the determination of the physico-chemical properties, a certain methodology has been followed, which includes the establishment of a network of five stations for sampling the water of the lagoon and the determination of the level of certain physico-chemical parameters. The physico-chemical parameters that were determined are: temperature (T), pH, dissolved oxygen (O2), BOD5, S%, Cl-, ECw, NH4+, NO2-, P-PO43-, hardness. The most pronounced differences of the physico-chemical levels are those that belong to the data of the south-east station. According to the level of different components for all the stations, a degree of homogeneity in the physico-chemical composition is observed. Only the physico-chemical feature of the water at south-eastern part of the lagoon makes a difference, which is related to the influence of the urban discharge channel of the city of Vlora. The physico-chemical parameters that interpret pollution such as: dissolved oxygen (O2), BOD5, NH4+, NO2-, NO3-, PO43-, hardness is higher than in other stations of the lagoon.

The objective of the present study is to examine the physico-chemical properties of Indigofera zollingeriana seed oil. Physico-chemical parameters of oils are important in the determination of edibility and other industrial applications. All the laboratory analysis were carried out using standard procedures according to AOAC (2000). The acid value, peroxide value, iodine value, saponfication value, refractive index and free fatty acids of cold pressed Indigofera zollingeriana seed oil was found to be 17.11 mg NaOH/g, 23.04 meq/kg, 180.4 gI2/100g, 118.7 mg/KOH/g and 14.10 %. The refractive index (20oC) and specific gravity (25oC) was 2.01 and 1.02 respectively. The extracted oil was Indigo in colour at liquid state. It was concluded the oil has a high acid value, peroxide value and free fatty acid which favours the use of the oil for industrial use such as soap production and cosmetics.

The issue of acid deposition and associated environmental problems has received special attention during recent decades and has been the subject of extensive research in a number of countries. However, there are no recent studies on acid deposition in Cardiff. Weekly rainfall samples were obtained from two urban areas in Cardiff from February 2006 to July 2007 and analysed for pH, electrical conductivity and major ions; SO42−, NO3−, Cl−, Ca2+, Na+, Mg2+, K+ and Pb2+. The chemical composition of precipitation was analysed in conjunction with meteorological variables to evaluate temporal and seasonal variations. Annual wet deposition was estimated, and enrichment factors determined. The pH of individual precipitations fluctuated excessively with a wide range from 4.9 to 6.6 indicating high variability in the acid sources and in neutralisation processes. Correlations between calcium and sulphate imply that CaSO4 may merge with the rainfall and neutralise the acidity. The volume-weighted mean concentrations of NO3− and non-sea salt SO42− were 24.1 and 31.4 μeq l−1, respectively. With the exception of the sea salt ions, no distinct spatial variations in ion composition were observed. Enrichment factors were calculated for most ions and higher correlation coefficients were obtained among most of the ions. Sea-derived material (Na+, Mg2+ and Cl−) showed pronounced cycles in concentration with maxima in autumn/winter. The Cl- (102 kg ha-1 yr-1) and Na+ (66 kg ha-1 yr-1) showed the highest wet deposition flux compared to the other ions. Anthropogenic and crustal sources made a significant contribution to both the acidification and neutralisation of precipitation in Cardiff. In all rain samples SO4-2 concentration exceeded NO3- concentration. Statistical analysis showed no significant differences in the physico-chemical parameters of the rainfall samples between the sites when tested at p<0.05. However, the ionic concentrations of wet precipitation depicted significant seasonal differences except for rainfall volume, K+, NO3- and SO4-2

The recent increase in crude oil cost arose interest in cheaper oils, usually called “opportunity crudes”. These oils are difficult to transport and treat, mainly because of their sulphur content, acidity and high density, but their cheap price makes them attractive, because refineries capable of processing them could gain a higher profit. Opportunity crudes composition affects process parameters and they can also cause corrosion and failures in plant equipment. It is well known that the main corrosive agents are the naphthenic acids (NAs), but the mechanism is complex and very little is known about it since there are many factors affecting it such as type of acids, temperature, sulphur compounds and fluid velocity. Thus damage process has not been clarified yet and at this time there is no accurate model available for predicting crude oil corrosiveness. Though considerable work has been done to understand NA corrosion in refineries, it turned out to be unsuccessful when the interdependence of NAs type and corrosion effects is considered. The objective of the research activity was to get more insight into the relationships between physico-chemical properties of crude oils and corrosion, in order to build a model aimed at identification of a corrosivity index which might help operators to determine the aggressiveness of processed fluids. For this purpose an analytical protocol was identified in order to determine the main molecular characteristics, such as number of carbon atoms, rings and average molecular weight. After some preliminary high temperature and pressure tests, a new equipment was developed and designed capable of reproducing real plant conditions. The small-scale plant was first used with a reference fluid consisting of gasoil and a commercial mixture of NAs, and then tested with actual crudes. The use of experimental design and of proper analytical techniques allowed to build a model for the corrosion of two different materials.

Microarrays containing long oligonucleotides provide sensitive and specific detection of gene expression and are becoming a popular experimental platform. In the process of designing an oligonucleotide microarray for Brucella, we optimized the overall design of the array and created probes to distinguish among the known Brucella species. A 3-way genome comparison identified a set of genes which occur uniquely in only one or two of the sequenced Brucella genomes. Reverse transcriptase PCR assays of over one hundred unique and pairwise-differential regions identified in Brucella revealed several groups of genes that are transcribed in vivo with potential significance for virulence. The structural and thermodynamic properties of a set of 70mer oligonucleotide probes for a combined B. abortus, B. melitensis and B. suis microarray were modeled to help perform quantitative interpretation of the microarray data. Prediction and thermodynamic analysis of secondary structure formation in a genome-wide set of transcripts from Brucella suis 1330 demonstrated that properties of the target molecule have the potential to strongly influence the rate and extent of hybridization between transcript and an oligonucleotide probe in a microarray experiment. Despite relatively high hybridization temperatures used in the modeling process, parts of the target molecules are predicted to be inaccessible to intermolecular hybridization due to the formation of stable intramolecular secondary structure. Features in the Brucella genomes with potential diagnostic use were identified, and the extent to which target secondary structure, a molecular property which is not considered in the array design process, may influence the quality of results was characterized.
Master of Science

Après une dizaine d'années de recherche, les verres autonettoyants ont été commercialisés en 2001. Leur principe est basé sur les propriétés photocatalytiques d'une couche submicronique de TiO2 déposée à leur surface. Sous l'action du rayonnement solaire et en présence d'oxygène, ils sont capables de dégrader les salissures organiques adsorbées en surface. Le présent travail a pour but d'apporter une meilleure compréhension des interactions entre la couche TiO2 et les salissures réelles, ainsi que d'évaluer les cinétiques de dégradation photocatalytique de polluants modèles par les verres. L'influence de différents paramètres tels que la température, les caractéristiques de l'irradiation, la nature des familles des polluants a été étudiée et corrélée aux performances des verres.

Yeasts form an important part of many ecosystems and significantly contribute to biodiversity. However, yeast biodiversity in the North West Province remains largely unexplored. The aim of this study was to determine the diversity and characteristics of yeasts from water sources in the North West Province, South Africa. Samples were collected over a two year period and included three rivers, a spruit and an inland lake. Temperature, pH, and electrical conductivity (EC) were measured on site using a multi-probe. Nitrate (NO3-N), nitrite (NO2-N) and phosphate (PO42-) levels were determined in the laboratory using Hatch kits and equipment. The pH ranged from 7.2 to 9.2. Elevated EC levels (36-70 mS) were detected especially at the Harts River and Barberspan (38-165 mS) sites. Physico-chemical parameter levels were higher during the cold dry sampling period compared to the warm rainy sampling period. Levels and diversity of yeasts were determined using the membrane filtration method. The highest level of yeasts was detected in the Mooi River and Schoonspruit during 2010 and 2011 sampling periods. Pigmented and non-pigmented yeasts were enumerated from all samples. Over the two year period the highest number of pigmented yeasts was detected in the Schoonspruit samples. In some cases there were significant (P<0.05) differences between pigmented and non-pigmented yeast levels among the sites. The diazonium blue B (DBB) test was carried out to distinguish between ascomycetous and basidiomycetous yeasts. These isolates were then identified using the API ID 32C system. Yeasts isolates were identified as belonging to the following genera: Candida, Cryptococcus, Pichia, Rhodotorula and Zygosaccharomyces. In addition using 26S rRNA gene sequencing Aureobasidium spp., Clavispora spp., Cystofilobasidium spp., Hanseniaspora spp., Meyerozyma spp., Sporidiobolus spp., and Wickerhamomyces spp.were also identified. The diversity and abundance of yeasts in the water sources demonstrated that opportunistic pathogens were present. This was supported by results that indicated some isolates could grow at 37°C and higher. In conclusion, our results provide preliminary information on the distribution and diversity of yeasts in water sources of the North West Province, South Africa.
Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.

Molecularly imprinted polymers (MIPs) are new type of materials with tailor made molecular recognition sites. Despite their enormous potential in separations, sensing and pharmaceutical industry, MIPs have so far failed to achieve significant commercial application. This is in part due to lack of understanding of MIPs at a molecular level, strong binding site heterogeneity and poor compatibility with aqueous solvents. This work is aimed at improving overall MIP performance and quality, with special focus on the improvement of compatibility with aqueous environment. Compatibility with aqueous solvents was achieved by (i) employing a molecular modelling step prior to polynerisation, (ii) by studying the ionic properties of the polymer and (iii) by analysis of the influence of different polymerisation conditions. The study of the pressure and magnetic field effects on polymers allowed us to produce materials with increased stability, lower binding site heterogeneity and higher affinity, as compared to standard imprinted materials. To minimise site heterogeneity imprinted nanoparticles with ca. 90 kDa were produced using a living polymerisation method. The particles with essentially uniform population of binding sites were obtained by employing affinity chromatography with immobilised template. As a model system variety of drugs were imprinted with the polymers being able to discriminate between closely related structural analogues in aqueous media. This work had substantial effect on success of project Pisarro - Piezoelectric Sensing Arrays for Biomolecular Interactions and Gas Monitoring where range of imprinted polymers were designed with high affinity to drugs of abuse. Currently 1 work is in progress aimed at application of these materials in commercial sensors for forensic use.

Molecularly imprinted polymers (MIPs) are new type of materials with tailor made molecular recognition sites. Despite their enormous potential in separations, sensing and pharmaceutical industry, MIPs have so far failed to achieve significant commercial application. This is in part due to lack of understanding of MIPs at a molecular level, strong binding site heterogeneity and poor compatibility with aqueous solvents. This work is aimed at improving overall MIP performance and quality, with special focus on the improvement of compatibility with aqueous environment. Compatibility with aqueous solvents was achieved by (i) employing a molecular modelling step prior to polynerisation, (ii) by studying the ionic properties of the polymer and (iii) by analysis of the influence of different polymerisation conditions. The study of the pressure and magnetic field effects on polymers allowed us to produce materials with increased stability, lower binding site heterogeneity and higher affinity, as compared to standard imprinted materials. To minimise site heterogeneity imprinted nanoparticles with ca. 90 kDa were produced using a living polymerisation method. The particles with essentially uniform population of binding sites were obtained by employing affinity chromatography with immobilised template. As a model system variety of drugs were imprinted with the polymers being able to discriminate between closely related structural analogues in aqueous media. This work had substantial effect on success of project Pisarro - Piezoelectric Sensing Arrays for Biomolecular Interactions and Gas Monitoring where range of imprinted polymers were designed with high affinity to drugs of abuse. Currently 1 work is in progress aimed at application of these materials in commercial sensors for forensic use.

Sa  jedne  strane  se  eksploatacija  šljunka  navodi kao  značajan  ugrožavajući  faktor  sa  velikim negativnim  uticajem  na  vodena  staništa  i biodiverzitet,  dok  same  šljunkare  mogu predstavljati  vredne  refugijume  akavtičnog  biodiverziteta.  Osnovni  cilj  disertacije  je određivanje  najznačajnijih  i  relevantnih hidromorfoloških  parametara  koji  utiču  na strukturiranje  makrofitskih  zajednica  u šljunkarama  duž  plavnog  područja  reke  Drine  i određivanje  korelacije  između  izdvojenih parametara  i  kvantitativnih  indeksa  makrofita.Istraživanje  je  vršeno  u  toku  letnjih  meseci 2015, 2016, 2017 i 2018. godine na 18 šljunkara (60 istraživačkih vegetacijskih sektora) u okviru tri   eksploataciona  polja  u  Crnoj  Bari, Badovincima  i  Lipničkom  Šoru  i  na  četiri prirodna  fluvijalna  jezera  (13  istraživačkih vegetacijskih  sektora)  u  plavnom  području  reke Drine.  Makrofitska  vegetacija  je  konstatovana na svih 18 istraţivanih šljunkara, prikupljenih na tri eksploataciona polja (Badovinci, Crna Bara  iLipniĉki Šor). Zabeležena je 31 biljna vrsta. Kao najučestalije,  sa  najvećom  apsolutnom pokrovnošću izdvojile su se vrste:  Potamogeton nodosus  Poiret,  Ceratophyllum  demersum  L subsp.  demersum,  Myriophyllum  spicatum  L,Najas  marina  L  i   Chara  globularis  Thuill  Na četiri prirodna fluvijalna jezera zabeleženo je 13 vrsta.  Vrste  Vallisneria  spiralis  L,  Elodea canadensis  Michx,  Callitriche  palustris  L, Potamogeton  natans  L  i  Nuphar  lutea  (L)  Sm izdvojile  su  se  kao  konstantne  i  dominantne. Vrednosti svih kvantitativnih indeksa makrofita,značajno  su  veće  za  šljunkare  u  poređenju  sa prirodnim  fluvijalnim  jezerima  na  nivouLEAFPACS  sektora.  Na  istraživanim šljunkarama,  analizom  klasterovanja  jeizdvojeno  13  vegetacijskih  grupa  (VG):  VG1 Ceratophyllum  demersum,  VG2  Ceratophyllum demersum  -  Valisneria  spiralis,  VG3  Chara contraria,  VG4  Chara  globularis,  VG5  Elodea canadensis,  VG6  Elodea  nuttallii,  VG7  Najas marina,  VG8  Najas  minor,  VG9  Nitellopsis obtusa,  VG10  Nuphar  lutea,  VG11 Potamogeton  nodosus,  VG12  Potamogeton natans  i   VG13  Potamogeton  pectinatus.  Na prirodnim  fluvijalnim  jezerima  konstatovane  su četiri  vegetacijske  grupe:  VG5  Elodea canadensis,  VG10  Nuphar  lutea,  VG12 Potamogeton natans  i  VG14  Typha latifolia.  Na osnovu izmerenih fizičko-hemijskih parametara,kvalitet vode u većini šljunkara odgovara II klasi kvaliteta, na osnovu čega se mogu okarakterisati kao  vodna  tela  sa  dobrim  i  boljim  ekološkim potencijalom. Sve šljunkare i fluvijalna jezera se klasifikuju  kao  visoko  alkalna.  Kvalitet  vode  u prirodnim  fluvijalnim  jezerima  odgovara  III  – IV  klasi  kvaliteta  voda,  pri  čemu  se  mogu okarakterisati  kao  vodna  tela  sa  slabim  do umerenim  ekološkim  statusom.  Značajno  većevrednosti  ukupnih  suspendovanih  materija, hemijske  i  biološke  potrošnje  kiseonika, ukupnog  organskog  kiseonika  i  nitrata zabeležene su na prirodnim fluvijalnim jezerima u poređenju sa šljunkarama. Izmerene vrednosti fizičko-hemijskih  parametara  ukazuju  na mezotrofni  karakter  lokaliteta  u  Badovincima  i mezo-eutrofni  karakter  lokaliteta  u  Lipničkom Šoru,  dok  se  šljunkare  na  teritoriji  Crne  Bare mogu  okarakterisati  kao  eutrofna  jezera.Vrednosti  LHMS  (modifikacionog)  skora  za šljunkare kretale su se u rasponu od 9  –  15, dok su vrednosti LHQA skora (stanišnog diverziteta) bile u rasponu izmeĊu 33  –  44. Sliĉne vrednosti za  LHQA  skor  su  izraĉunate  i  za  prirodna fluvijalna  jezera  (36  –  49).  MeĊutim,  vrednostiLHMS  skora  za  prirodna  fluvijalna  jezera  su znaĉajno  veće  u  odnosu  na  vrednosti  LHMS skora za šljunkare. Ovi podaci ukazuju na manje prisustvo  antropogenog  pritiska  na  šljunkarama u poređenju sa prirodnim fluvijalnim jezerima uistraţivanom  podruĉju.  Fizičko -hemijski  i hidromorfološki  parametri  zajedno  su  objasnili 57.07  %  od  ukupne  varijanse  vegetacijskih podataka,  sa  16.57  %  deljenog  efekta.  Fizičkohemijski  parametri  kvaliteta  vode  objasnili  su 17.02  %  varijabilnosti  u  strukturi  makrofitske vegetacije.  Kao  najsignifikantniji  parametriizdvojili  su  se:  saturacija  vode  kiseonikom,ukupni  organski  ugljenik,  površinski  aktivne materije, temperatura, elektroprovodljivost, pH i ukpni  alkalitet.  Hidromorfološki  parametri  su objasnili  23.48  %  varijabilnosti  u  strukturi makrofitske  vegetacije.  Kao  najsignifikantnije varijable,  izdvojile  su  se:  struktura  vegetacije  u priobalnoj  zoni,  diverzitet  prirodnih  tipova staništa  priobalne  zone,  prirodnost  obale, diverzitet  prirodnog  supstrata  litorala,masimalna dubina šljunkara, površina šljunkara,indeks relativne dubine, udaljenost šljunkara od glavnog  reĉnog  toka  i  starost  šljunkara. Hidrološki  parametri  su  objasnili  8.38  % varijabilnosti u strukturi  makrofitske vegetacije. Kao  najsignifikantnije  varijable,  izdvojile  su  se broj plavnih talasa u vegetacionoj sezoni tokom godine u kojoj je vršeno uzorkovanje vegetacije i broj plavnih talasa u prolećnom periodu za sve četiri  godine.  Ovi  rezultati  potvrđuju  direktni destruktivni  uticaj  plavnih  talasa  na  vodenu vegetaciju u vegetacionoj sezoni, kao i indirektni uticaj prolećnih poplava, usled uticaja na trofički status  vode.  Sumarno,  šljunkare  u  plavnom području  reke  Drine  predstavljaju  optimalno stanište  za  razvoj  retke  i  ugroţene  makrofitske flore.  Od  ukupnog  broja  zabeleženih  vrsta makrofita,  30  %  se  kategoriše  kao  zaštićeno  ili ugroženo na nacionalnom nivou.  Značajno veće vrednosti  konzervacionih  indeksa  ustanovljene su  za  šljunkare  u  poređenju  sa  prirodnim fluvijalnim jezerima, što ukazuje na njihov visok ekološki  potencijal.  Ustanovljen  je  visok diverzitet  prioritetnih  tipova  akvatiĉnih  staništa prema  Pravilniku  o  kriterijumima  za  izdvajanje tipova  staništa,  o  tipovima  staništa,  osetljivim, ugroženim,  retkim  i  za  zaštitu  prioritetnim tipovima  staništa  i  o  merama  zaštite  za  njihovo očuvanje, Aneksu I, Direktive Evropske unije ozaštiti  prirodnih  staništa  i  divlje  flore  i  faune (Natura  2000),  Rezoluciji  br.  4  Konvencije  o očuvanju  evropske  divlje  flore  i  faune  i prirodnih  staništa (EMERALD)  i  Evropskoj crvenoj  listi  staništa.  Vrednosti  izdvojenih atributa  šljunkara  mogli  bi  se  iskoristiti  u procesu  ranog  planiranja  i  projektovanja eksploatacionih  polja  u  plavnom  području  reke Drine  i  na  drugim,  sličnim  lokalitetima. Generalna preporuka je da se dva tipa šljunkara kreiraju  u  okviru  jednog  eksploatacionog  polja. Prvi  tip,  odnosno  šljunkare  koje  bi  podržavale pionirsku  vegetaciju  pršljenčica  trebale  bi  da budu locirane na razdaljini do 100 m od glavnog rečnog  toka,  površine  do  1000  m 2 i  da  imaju vrednost indeksa relativne dubine > 5 %. Drugi tip  šljunkara  koje  bi  podržavale  vegetaciju karakterističnu  za  nizijska  fluvijalna  jezera trebale bi da budu locirane na razdaljani od oko 300 m od glavnog rečnog toka, dubine 3  –  4  m (najmanje 2 m), površine između 10000 i 20000 m ² (najmanje  4000  m ² ),  različitih  vrednosti indeksa relativne dubine, ali  ne preko 5 %. Sva eksploataciona  polja  bi  trebalo  isplanirati  i isprojektovati  kako  bi  se  minimizirao  uticaj  na priobalnu  i  obalnu  zonu.  Pridržavanjem  datih smernica  povećao  bi  se  diverzitet  i  kvalitet staništa,  kao  i  konzervacioni  potencijal šljunkara. Kreiranjem šljunkara na naĉin kao što je predloženo u ovoj disertaciji omogućila bi se spontana  rekultivacija  eksploatacionih polja,odnosno  remedijacija  u  cilju  poboljšanja kvaliteta vode i renaturalizacija staništa, čime bi se  znatno  smanjili,  ili  u  potpunosti  eliminisali, troškovi tehničke rekultivacije terena.
Gravel pit lakes in the river floodplains represent a kind of ecological paradox. Gravel exploitation was recognised  as  important  factor  significantlyaffecting  aquatic  habitats  and  biodiversity.  On the  other  hand,  gravel  pit  lakes  are  valuable biodiversity  refugiums,  potentially  supporting rarae  species  and  habitats.  The  aim  of  this dissertation  was  to  determine  the  most significant  and  relevant  hydromorphological parameters  in  structuring  macrophyte assemblages  in gravel pit  lakes along the Drina River floodplain and to determine the correlation between  selected  parameters  and  macrophyte quantitative  indices.  The  research  was  carried out at the 18 gravel pit lakes (60 survey sectors) in  Crna  Bara,  Badovinci  and  Lipnicki  Sor  and four natural fluvial lakes (13 survey sectors), in the  Drina  River  floodplain  during  the  summer months  of  2015,  2016,  2017  and  2018.Macrophyte  vegetation  was  recorded  in  all  18 gravel pit lakes, in total supporting 31 taxa.  The most  abundant  species,  with  highest  tot al  cover value  were Potamogeton  nodosus,Ceratophyllum  demersum  subsp.  demersum, Myriophyllum  spicatum,  Najas  marina  and Chara  globularis.  Fluvial  lakes  supported  13 macrophyte  taxa  with  Vallisneria  spiralis, Elodea  canadensis,  Callitriche  palustris,Potamogeton  natans  and  Nuphar  lutea  as constant and dominant  species.  The values of all macrophyte  quantitative  indices  found  to  be significantly  higher  in  the  gravel  pit  lakes compared  to  the  fluvial  ones.  The  cluster analysis  revealed  14  aquatic  vegetation  groups (VG).  At  16  out  of  18  gravel  pit  lakes  13 vegetation  groups  were  revealed:  VG1Ceratophyllum  demersum,  VG2  Ceratophyllum demersum- Valisneria  spiralis,  VG3  Chara contraria,  VG4  Chara  globularis,  VG5  Elodea  canadensis,  VG6  Elodea  nuttallii,  VG7  Najas marina,  VG8  Najas  minor,  VG9  Nitellopsis obtusa,  VG10  Nuphar  lutea,  VG11 Potamogeton  nodosus,  VG12  Potamogeton natans, VG13  Potamogeton pectinatus), Natural fluvial  lakes  supported  4  vegetation  groups: VG5  Elodea  canadensis,  VG10  Nuphar  lutea, VG12  Potamogeton  natans  and  VG14  Typha latifolia.  All  gravel  pit  lakes  can  be characterized  as  water  bodies  with  good  to maximal  ecological  potential,  while  all  the fluvial ones can be characterized as water bidies with  poor  to  moderate  ecological  status.  The values  of  total  suspended  supstances,  chemical and  biological  oxygen  demand,  total  organic carbon  and  nitrates  were  significantly  higher  in the natural  fluvial  lakes compared to the gravel pit  ones.  Measured  level  of  physico-chemical parameters  indicating  mesotrophic  character  of gravel  pit  lakes  in  Badovinci  and  mesoeutrophic  in  Lipnicki  Sor,  while  all  the  gravel pits  in  Crna  Bara  could  be  characterized  as eutrophic.  Similar  range  values  were  calculated for  LHQA  for  gravel  pit  and  fluvial  lakes  (36 – 49). However, natural lakes  showed significantly higher  values  for  LHMS  score.  The  above mentioned,  indicates  higher  anthropogenic pressures  on  natural  fluvial  lakes  compared  to gravel  pit  ones.  Physico-chemical  and hydromorphological  parameters  together explained  about  57  %  of  the  total  variance  of macrophyte  assemblages  with  16.57  %  of  the shared effect. After accounting for the effects of physico-chemical  parameters  (17.02  %), hydromorphological  variables  explained  around 23 % of the total variance.  The most significant water  quality variables  were: oxygen saturation, total  organic  carbon,  surfactants, ,electroconductivity,  pH  and total alkalinity. The The most significant hydromorphology  variables for  structuring  macrophyte  assemblages  were: riparian  vegetation  structural  complexity, diversity  of  natural  landcover  types  in  riparianzone, shore structural habitat  diversity, diversity of  natural littoral zone, maximal  lake depth, lake surface  area,  relative  depth  ratio,  lake  distance from  r iver  main  channel  and  lake   age.Hydrologycal parameters were explained 8.38 % of  variance  in  structuring  macrophyte assemblages.  The  most  significant  hydrology variables  were  the  number  of  floods  in vegetation  season  in  first  year  when  vegetation was sampled, and the number of spring floods in all four research years. These results   confirm the direct destructive influence of summer floods  on aquatic vegetation, as   well as the indirect impact of  spring  floods,  due  to  the  impact  on  trophic status  of  water.  Gravel  pit  lakes  in  te  Drina River floodplain  represent an optimal habitat   for rare  and  threatened  macrophyte  flora.  Of  the total  macrophyte  species  recorded,  30  %  were categorized  as  protected  or threatened.  At  least one  strictly  protected,  protected  or  threatened species  was  recorded  in  each  gravel  pit  lake. Significantly  higher  values  of  conservation indices  (C  and  Csp  score)  found  to  be significantly  higher  in  the  gravel  pit  lakes compared  to  the  fluvial  ones.  High  habitat diversity  and  conservation  value  of  the  sites have  been  recorded  according  to  the  National Rulebook,  Annex  I  of  Habitats  Directive (NATURA 2000), Resolution  no. 4 of the Bern Convention (EMERALD) and the European Red List  of  Habitats.  Values  of  selected  lake attributes can be used for early-design phases of future  gravel  extraction  in  the  Drina  River floodplain  area,  and  in  other  similar  sites. Therefore,  general  recommendations  are  that two gravel pit types should be excavated within the  single  extraction  area  in  order  to  support pioneering charophyte vegetation and vegetation of typical eutrophic lowland floodplain lakes as well.  The  first  hydromorphological  lake  type, suitable  for  stonewort  species,  should  be excavated up to 100 m from river main channel, saving  a  surface  area  up  to  1000  m 2 and  a relative depth ratio > 5 %. The second gravel pit type  should  be  located  about  300  m  from  river main channel, with preferable maximal depth inrange  3–4  m  (at  least  2  m  depth),  and  a  lake surface area between 10000 m 2 and 20000 m 2 (at least  4000  m 2 ).  Relative  depth  ratio  may  vary, but should be less than 5 %. Generally, all sites should  be  designed  with  the  minimal  impact to the  riparian  and  shore  zones.  These  proposed measures  would  considerably  increase  lake habitat diversity and their conservation potential. Creating  gravel  pit  lakes  as  proposed  in  this dissertation    would  allow  spontaneous recultivation  of  exploitation  fields,  remediation in  order  to  improve  water  quality  and renaturalization  of  habitats,  which  will significantly reduce, or completely eliminate, the costs of terrain technical recultivation.

This study aimed to assess the ecological status/potential of the Čemernica and Dičina rivers (Zapadna Morava basin) based on epilithic diatoms and supporting physico-chemical parameters, as well as to explore indicative properties of the detected macroalgae. The sampling and analysis of benthic algae and measurement of physico-chemical parameters were carried out in August 2023. The ecological status/potential of the Čemernica River was poor to bad at all investigated sites (ČR1, ČR2, ČR3) based on diatom indices and physico-chemical parameters. Low diatom indices values and the presence of the macroalgae Stigeoclonium tenue indicated organic pollution. In the Dičina River, good ecological status was assessed at all sites (DR1-DR4) based on the diatom indices, while poor ecological status has been assessed at almost all sites (DR1, DR2, DR3) based on the physico-chemical parameters, except at DR4, where the ecological status was good. The high coverage of Cladophora glomerata in both rivers indicated nutrient loading, which aligned with the results of the physico-chemical parameters.

The well-known concept of third body was introduced by Godet in the seventies to characterise the discontinuous and heterogeneous interface that separates two bodies in contact. This thin layer (from some nanometers to some micrometers high) appears to possess its own rheology depending of contact conditions, material properties and often, extra unknown parameters. If its main common role concerns essentially mechanical aspects such as velocity accommodation, load carrying capacity and solid lubricant, it plays an important role in other physical aspects. For example, it ensures the thermal continuity between two bodies in contact and explains the jump of temperature observed experimentally. Moreover, it is able to capture the maximal temperature through its thickness. Due to the difficulty to instrument a real contact without disturbing the local rheology, observations of the third body rheology occur only on simplified experimental set-up. To reproduce and try to understand “real contact in presence of third body”, numerical tools have been developed and adapt to face new challenge raised by the third-body concept. The discontinuity and heterogeneity of such interface led researchers to use discrete element methods (DEM) to describe its evolution. Several improvments of the method allow to deal with the mechanical and the thermal behaviour of such media but without interactions. The integration of physicochemical aspects is presented in the paper to link thermal and mechanical behaviour and proposed a model able to represent the multi-physical feature of a contact interface.

The water samples collected from four localities of the middle course of the Zapadna Morava River during 2020 were analyzed via the selected physico-chemical parameters with the aim to estimate the quality of surface water. According to the results of selected physico-chemical parameters (pH, conductivity, dissolved oxygen, chemical oxygen demand, biochemical oxygen demand), analyzed surface water show a good chemical status, while the values of nutrient content (nitrate, nitrite, ammonium ion, total phosphorus) indicated the poor chemical status especially at the locality 4 probably due to the outflow of wastewater from the city of Čačak as well as from the influence of the polluted water of the Čemernica River.