Browsing by Author "Duca, Gheorghe"

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APEL CĂTRE PARTIDELE PARLAMENTARE PROEUROPENE
(Academia de Ştiinţe a Moldovei, 2014) Duca, Gheorghe; Tighineanu, Ion; Rusnac, Gheorghe; Guceac, Ion; Hanganu, Aurelia
APLICAREA METODELOR FIZICO-CHIMICE COMBINATE LA ÎNLĂTURAREA POLUANȚILOR TEXTILI DIN SOLUȚII APOASE
(2022) Mocanu, Larisa; Duca, Gheorghe
Scopul lucrării constă în stabilirea condițiilor optime de epurare a efluenților sintetici și apelor uzate industriale textile de agenți de colorare și agenți auxiliari prin aplicarea metodelor fizico-chimice combinate, elaborarea schemelor de tratare și integrarea acestora în procesul de epurare, pentru a menține un conținut chimic admisibil a apelor naturale, conform standardelor în vigoare.
Aplicarea metodelor fizico-chimice combinate la înlăturarea poluanților textili din soluții apoase: Monografie
(CEP USM, 2023) Mocanu, Larisa; Gonța, Maria; Duca, Gheorghe; Matveevici, Vera
În lucrare s-au studiat procesele de epurare a efluenților sintetici și a apelor uzate industriale cu conținut sporit de poluanți textili greu biodegradabili, care fiind evacuați fără o epurare preventivă produc un impact negativ asupra mediului acvatic.
ASSESSMENT OF KINETIC PARAME TERS IN THE WATERS OF THE NISTRU COURSE IN THE SECT ION NASLAVCEA – DUBASARI
(Academia de Știinițe a Moldovei, 2006) Bunduchi, Elena; Duca, Gheorghe; Gladchi, Viorica; Goreaceva, Nelli; Mardari, Igor
The current work represents the results of a monitoring executed on Nistru River waters between October 2003 and September 2005. The water quality was valuated on the basis of such kinetic indicators as redox state and capacity of inhibition. The obtained results shows that Nistru River water in the segment Naslavcea village – Dubasari barrage are continuously polluted with reducing substances that diminish the H2O2 content, that actually determines the redox state of natural waters and the content of free radicals
ASSESSMENT OF KINETIC PARAMETERS IN THE WATERS OF THE NISTRU COURSE IN THE SECTION NASLAVCEA – DUBASARI
(2006) Bunduchi, Elena; Duca, Gheorghe; Gladchi, Viorica; Goreaceva, Nelli; Mardari, Igor
The current work represents the results of a monitoring executed on Nistru River waters between October 2003 and September 2005. The water quality was evaluated on the basis of such kinetic indicators as redox state and capacity of inhibition. The obtained results shows that Nistru River water in the segment Naslavcea village – Dubasari barrage are continuously polluted with reducing substances that diminish the H2O2 content, that actually determines the redox state of natural waters and the content of free radicals
CAPACITATEA DE AUTOPURIFICARE BIOLOGICĂ A APELOR NATURALE ŞI UZATE PRIN EVALUAREA RAPORTULUI DINTRE POLUANŢII BIODEGRADABILI ŞI CEI TOXICI
(CEP USM, 2024) Duca, Gheorghe; Sandu, Maria; Gladchi, Viorica; Lis, Angela; Blonschi, Vladislav
Studiul dat evidențiază impactul semnificativ al poluării chimice a mediului acvatic, provenite din diverse surse continue, intermitente şi accidentale - cu o atenţie specială acordată râurilor mici din Republica Moldova. În articol se aplică metodologia evaluării capacității de autopurificare biologică a apelor naturale şi reziduale, utilizând parametrii consumul biochimic de oxigen (CBO5) şi consumul chimic de oxigen (CCOCr). Aceşti parametri sunt esenţiali pentru aprecierea aportului proceselor de biodegradare a poluanţilor în apele naturale şi reziduale. În baza raportului CBO5/CCOCr apele se clasifică în cinci nivele de autopurificare, de la eficientă până la imposibilă. Lucrarea subliniază necesitatea respectării cerinţelor normative pentru epurarea apelor uzate provenite din diferite sectoare economice. Pentru monitorizarea respectării acestor cerinţe se sugerează calcularea capacităţii de autopurificare folosind raportul CBO5/CCOCr.
CATALYTIC OXIDATION OF 2, 2 DI (HYDROXYMETHYL) PROPIONIC ACID
(Academia de Ştiinţe a Moldovei, 2017) Mocanu, Larisa; Gonta, Maria; Duca, Gheorghe
CERCETAREA COMPUTAȚIONALĂ A ACIDULUI DIHIDROXIFUMARIC ȘI A DERIVAȚILOR ACESTUIA CU ACTIVITATE ANTIOXIDANTĂ
(Editura USM, 2023) Bolocan, Natalia; Duca, Gheorghe
Capitolul de față descrie aplicarea metodelor computaționale în cercetarea proceselor de izomerizare/tautomerizare a acidului dihidroxifumaric (DHF), pentru calculul indicilor de reactivitate globală și locală a derivaților noi ai DHF, pentru demonstrarea validității procedurii KID în gaz, apă și metanol. În cadrul cercetării de față, a fost efectuată în premieră analiza predictivă prin metode de calcul a proprietăților de absorbție, distribuție, metabolism, excreție și toxicitate a derivaților cercetați, care au demonstrat proprietăți similare medicamentului. Au fost construite radarele de biodisponibilitate a substanțelor cercetate, demonstrând proprietăți semnificativ asemănătoare medicamentelor. De asemenea, pentru prima dată, utilizând metoda andocării moleculare, a fost demonstrat potențialul semnificativ de inhibiție a proteazei principale a virusului SARS-CoV-2 de către toți compușii supuși studiului.
CERCETAREA PROPRIETĂȚILOR ANTIRADICALICE ALE ACIDULUI DIHIDROXIFUMARIC ȘI A UNOR DERIVAȚI AI SĂI CU APLICAREA METODELOR CINETICE ȘI COMPUTAȚIONALE
(2023) Bolocan, Natalia; Duca, Gheorghe
Scopul tezei: constă în cercetarea prin metode cinetice și cuanto-chimice a activității antiradicalice a acidului dihidroxifumaric și a zece derivați ai săi, obținuți în cadrul acestei lucrări.
CHEMICAL AUTOPURIFICATION OF ACTIVE BLUE DYE-POLLUTED NATURAL WATER
(Academy of Sciences of Moldova, 2017) Bunduchi, Elena; Gladchi, Viorica; Duca, Gheorghe
CHEMICAL COMPOSITION FROM THE DNIESTER RIVER TRIBUTARIES
(2013) Gladchi, Viorica; Duca, Gheorghe; Goreaceva, Nelli; Bunduchi, Elena; Lis, Angela
This article presents the results obtained in the framework of the project 09.832.08.06A The role of the tributaries on formation of the Dniester river water and the study of the waters quality of sources/fountains in the catchment area of the Dniester river as sources of water supply and for irrigation in the State Program, ScientificResearches and of the management of waters quality.
CHEMICAL COMPOSITION FROM THE DNIESTER RIVER TRIBUTARIES
(2013) Gladchi, Viorica; Duca, Gheorghe; Goreaceva, Nelli; Bunduchi, Elena; Lis, Angela
This article presents the results obtained in the framework of the project 09.832.08.06A The role of the tributaries on formation of the Dniester river water and the study of the waters quality of sources/fountains in the catchment area of the Dniester river as sources of water supply and for irrigation in the State Program, Scientific Researches and of the management of waters quality.
CLIMATIC CHANGES AND SURFACE WATER QUALITY ON REPUBLIC OF MOLDOVAS TERRITORY
(Springer Nature Switzerland AG, 2020) Duca, Gheorghe; Nedealcov, Maria; Gladchi, Viorica; Travin, Serghei
The current state of global warming requires the expansion of the overall knowledge as well as regional particularities of climate change. The study finds that the Republic of Moldova is facing an accelerated pace of climate change that contributes to a more intense aridisation process and heat waves, with long periods of manifestation in the last years and argues that adaptation to the effects of climate change must be an important element for national policies and actions. Also, the authors establish that for Moldova climate change is a new challenge for water quality that requires great attention and a distinct scientific approach, which implies the participation of various domains of science. In this context, the study proposes an integrated knowledge based approach towards adapting to climate change effects in a broad context of natural and social systems, which incorporate scientific, legal, economic and ecological measures. The authors propose the development of plans and actions based on knowledge transfer and new technologies in order to achieve a better protection and adequate management of water resources in vulnerable areas.
CLOSED-CYCLE INTENSIFIED TECHNOLOGY FOR SUSTAINABLE BIOCHEMICAL PRODUCTION OF ALTERNATIVE FUELS FROM AGRICULTURAL WASTES
(Academia de Ştiinţe a Moldovei, 2017) Covaliova, Olga; Covaliov, Victor; Bobeica, Valentin; Nenno, Vladimir; Duca, Gheorghe
COMPOZIŢIA CHIMICĂ ŞI STAREA REDOX A APELOR NISTRULUI MEDIAL
(2008) Gladchi, Viorica; Goreaceva, Nelli; Duca, Gheorghe; Bunduchi, Elena; Borodaev, Ruslan; Mardari, Igor; Romanciuc, Lidia
The result of construction of a hydrochemical system in the section line of the Dniester River at Novodniestrovsk was the achievement of practically total control of the river flow in the Moldovan part. At the same time, this system controls not only the seasonal variation of the level of the river but also forms a new hydrological and hydrochemical regime of the river as a result of the controlled discharge of water through the Novosdniestrovsk barrage. The level of impact of this process on the quality of waters was the main objective of current research. With this purpose during the years 2005-2006 there were performed investigations in the segment of the River starting with buffer reservoir (200 m below the barrage) at Naslavcea and ending with c. Dubasari (100 m below the Dubasari barrage). Water samples were collected in 6 different section lines. The parameters measured included: water temperature, pH, Eh, rH, hydrogen peroxide content, OH radicals content, dissolved oxygen, total amounts of iron, copper, soluble forms of nitrogen compounds, COD, BOD5 and others. A special attention was drawn to the analysis of the redox state of waters, the content of OH radicals and other parameters that were affected by man-made systems or activities. In the frames of the project 8 expeditions were carried out.
COORDINATION PECULIARITIES OF THE SALICYLALDEHYDE S-METHYLISOTHIOSEMICARBAZONE IN THE PALLADIUM COMPLEXES
(Academia de Ştiinţe a Moldovei, 2006) Revenco, Mihail; Bourosh, Pavlina; Duca, Gheorghe; Simonov, Yurii; Bulmaga, Petru; Jora, Elena; Gdaniec, Maria; Ketrush, Petru
Two coordination modes of salicylaldehyde S-methylthiosemicarbazone (Me-S-HSATSC-NH2) have been observed in the palladium complexes with this ligand. The interaction between Me-S-HSATSC-NH2 and tetrachloropalladate gives rise to the formation of a compound of the composition Pd(Me-S-SATSC-NH2)Cl which one has a planar structure. The organic ligand behaves as a monodeprotonated acid coordinated by O,N,S donor atoms set. This is the only case when the thioalkylated thiosemicarbazone uses the sulfur atom for coordination. The forth position in the coordination polyhedron of the complex is occupied by the chloride ion.figureMolecular structure of [Pd(Me-S-SATSC-NH2)Cl] and [Pd(Me-S-SATSC-N-NO)NO2]When the solution of K2[Pd(NO2)4] was treated with Me-S-HSATSC-NH2, the organic reagent undergoes a more dramatic chemical transformation carrying out to the formation of a new derivative of thiosemicarbazide – nitrozothioamide Me-S-SATSC-N-NO. The newly synthesized organic reagent is a monodeprotonated acid bound via O,N,N donor set, while the alkylated sulfur atom is uncoordinated. The forth site is occupied by NO2-ion coordinated by nitrogen atom (see fig.). The possible causes, driving the system to the formation of nitrosothioamide, and the impact of the anion on the coordination mode of the organic ligand will be discussed.
CRISTOFOR SIMIONESCU
(2007) Duca, Gheorghe; Vlad, Pavel; Gulea, Aurelian; Turtă, Constantin; Batîr, Dumitru; Lupașcu, Tudor; Revenco, Mihail
CYCLODEXTRINS – FIELDS OF APPLICATION. PART I
(Academia de Știinițe a Moldovei, 2008) Duca, Gheorghe; Boldescu, Veaceslav
This review is dedicated to different fi elds of use of cyclodextrins, a family of three cyclic natural oligosaccharides and their derivatives. The fi rst part of the review gives a brief description of the main and the most recent developed applications of cyclodextrins in food, cosmetic industry, environmental protection technologies and agriculture. Different products based on inclusion complexes with cyclodextrins and technologies with different use of cyclodextrins and inclusion complexes are described.
Derivați noi ai acidului dihidroxifumaric: cercetări cinetice și computaționale: Monografie
(Editura USM, 2023) Bolocan, Natalia; Duca, Gheorghe
Această monografie, bazată pe teza de doctorat în științe chimice a Nataliei Bolocan, scrisă sub îndrumarea Acad. Prof. Gheorghe Duca și consolidată prin publicațiile științifice recente, se prezintă ca un studiu amplu și meticulos în domeniul chimiei fizice și computaționale. Lucrarea își propune să exploreze complexitatea și aplicabilitatea acidului dihidroxifumaric (DHF) și a derivaților săi, cu un accent particular pe caracteristicile lor chimice și cuantice.
THE DIMINISHING OF THE CONTENT OF TEXTILE DIRECT DYES AND AUXILIARY COMPOUNDS DURING THEIR CATALYTIC OXIDATION
(Institute of Chemistry of ASM, 2014) Gonta, Maria; Duca, Gheorghe; Matveevici, Vera; Mocanu, Larisa
Advanced oxidation methods of organic compounds lead to their partial mineralization and increase of the adsorption process effi ciency on the surface of oxidized activated carbon. We have studied the oxidation process using model solutions containing mixture of dye direct brown (DB), ethylene glycol (EGL) and sodium lauryl sulfate (SLS) under the action of Fenton reagent, in the presence and absence of UV irradiation or under the action of electric current (in the electrochemical cell). The same studies were performed by replacing the iron (II) ion with titanium dioxide. We have found that the degree of oxidation and mineralization increases by photocatalytic oxidation and decreases the concentration of organic compounds. Due to the oxidation of dye molecules and other auxiliary components, by strong oxidation ability of free OH* radicals, which evolve to the formation of carbon dioxide, water and low molecular organic compounds (alcohols, ketones, organic acids) are forming. The decrease of the concentration of mixture of organic compounds (for the values of COD-Cr) depends on the nature of catalysts and the presence of electric current. The degree of oxidation is greater in the presence of iron (II) ions than in the presence of titanium dioxide after oxidation of the mixture of organic compounds with hydrogen peroxide in model solutions. This is explained by the fact that UV irradiation increases the concentration of free OH* radicals as iron ions further decompose hydrogen peroxide, but in the presence of titanium dioxide, the leading band electrons are accepted by free OH* radicals, converting these radicals to ions, as shown in the mechanism by Garcia J., et al. This leads to a decrease of the concentration of OH* radicals in model solution and reducing the effect of oxidation, respectively. On the contrary, in the presence of electric current electrons are accepted by the electrode, and the OH* radicals concentration does not decrease, but increases, and this leads to the enhancement of the oxidation effect and mineralization of organic compounds.