STUDIA CHEMIA - Issue no.3 / 2019 - Table of contents

Centenarul universității clujene ne oferă prilejul unei retrospective care să reflecte începuturile, dezvoltarea și contribuțiile școlii clujene de chimie in cercetarea științifică românească și prezența sa în știința chimică internațională. Trebuie să spunem de la început că acestea nu sunt neglijabile, deși multă vreme condițiile nu au fost comparabile cu cele din țările mai avansate.

În chimia clujeană s-au perindat mai multe generații, care dincolo de pregătirea de specialitate a studenților au adus fiecare ceva nou în preocupările științifice, în pas cu dezvoltarea chimiei și apariția unor noi domenii.

Încă de la începuturile sale, imediat după înființarea universității românești de la Cluj, chimia – încadrată în Facultatea de Științe, s-a manifestat și în cercetarea științifică, datorită profesorilor întemeietori care nu s-au mulțumit cu o activitate didactică remarcabilă, ci au introdus și spiritul științific în activitatea noii instituții. Aceștia sunt profesorii Adriano OSTROGOVICH (chimie organică), Dan RADULESCU (chimie organică, chimie fizică) și Gheorghe SPACU (chimie anorganică).

Activitatea profesorilor întemeietori s-a manifestat în perioada antebelică și a fost urmată de o generație de continuatori, care –formați înainte - au dus chimia clujeană și în perioada postbelică, în cadrul Facultății de Chimie. Aici se remarcă profesorii Raluca RIPAN (chimie anorganică), Ion TĂNĂSESCU (chimie organică), Candin LITEANU (chimie analitică), Ion CĂDARIU (chimie fizică), Gheorghe Constantin MACAROVICI (chimie generală). Activitatea acestor profesori a continuat până în deceniile 5-6.

O nouă generație cuprinde profesorii Emil CHIFU (chimie fizică), Gheorghe MARCU (chimie anorganică), Alexandru SILBERG, Maria IONESCU, Valer FĂRCĂŞAN, Nicolae ALMASI (chimie organică), Sorin MAGER (stereochimie), Ladislau KEKEDY (chimie analitică). A urmat o noua generație, cu profesorii Liviu ONICIU, Gheorghe NIAC, Janos ZSAKO, Ioan BÂLDEA (chimie fizică), Judith MUREŞAN (chimie macromoleculară). Crearea secției de inginerie chimică, datorată profesorului Liviu LITERAT, a adăugat o nouă dimensiune facultății.

Generația ultimă, contemporană, care și-a încheiat recent activitatea sau este în pragul pensionării, cuprinde – printre alții – profesorii Cătălin POPESCU, Maria TOMOAIA-COTIŞEL, Ossi HOROVITZ, Liana Maria MUREŞAN (chimie fizică), Ioan SILBERG, Ion GROSU, Luminița SILAGHI-DUMITRESCU, Ioan CRISTEA, Mircea V. DIUDEA, Ioan OPREAN, Mircea VLASSA, Mircea DĂRĂBANŢU (chimie organică), Ionel HAIDUC, Cristian SILVESTRU, Stanislav COSTA, Mariana RUSU, Rodica MICU-SEMENIUC, Maria CURTUI, Letiția GHIZDAVU, Adrian PĂTRUŢ (chimie anorganică, organometalică și supramoleculară), Ioan SILAGHI-DUMITRESCU (chimie computațională), Costel SÂRBU, Emil CORDOS, Simion GOCAN, Teodor HODISAN, Iovanca HAIDUC (chimie analitică), Şerban AGACHI, Petru ILEA, Ioan BÂTIU, Eugenia GAVRILĂ (inginerie chimică), Florin Dan IRIMIE (biocataliză și inginerie biochimică).

Contribuțiile școlii clujene de chimie au fost recunoscute în țară prin alegerea unor profesori ca membri ai Academiei Române: profesorii Gheorghe SPACU, Raluca RIPAN (prima femeie academician), Ion TĂNĂSESCU, Gheorghe Constantin MACAROVICI, Ionel HAIDUC, Ioan SILBERG, Ioan SILAGHIDUMITRESCU, Cristian SILVESTRU, Ion GROSU.

Generația contemporană de tineri conferențiari, ale căror nume nu le cităm deocamdată, își așteaptă rândul și promite continuarea la același nivel a cercetării științifice din Facultatea de Chimie și Inginerie Chimică.

Este dificil de prezentat într-un spațiu redus, domeniile abordate de-a lungul unui secol în cercetarea științifică clujeană în domeniul chimiei, preocupările și rezultatele, poate uneori performanțele mai deosebite. Încă de la începuturi, chimiștii clujeni au publicat nu numai în revistele naționale (se remarcă la început Buletinul Societății de Științe din Cluj, apoi Revue Roumaine de Chimie, Studia Universitatis Babeș-Bolyai-Chemia, Revista de Chimie), ci au fost prezenți și în revistele internaționale. Mai ales în ultimii 30 ani, dar și înainte, nume ale chimiștilor universității clujene pot fi întâlnite în cele mai prestigioase reviste internaționale și uneori, ca autori, chiar pe coperțile unor cărți publicate în străinătate. Un rol însemnat au avut colaborările internaționale, desfășurate timp de mai mulți ani. Îmbunătățirea continuă a dotărilor facultății (de exemplu cu aparatură avansată de spectrometrie, cromatografie, spectroscopie și difractometrie de raze X) au facilitat cercetări independente, la nivel comparabil cu cel din universitățile europene.

Cercetările abordate în Facultatea de Chimie și Inginerie Chimică, cu contribuții recunoscute, se referă la sinteza organică (heterocicluri, sinteza Tănăsescu, substanțe biologic active), combinații coordinative (reactivul Spacu), polioxometalați, compuși organometalici, chimie supramoleculară, cicluri anorganice, biocataliză și tehnologii biochimice, radiochimie, chimie coloidală și chimia suprafețelor, electrochimie, cinetică chimică, chimie teoretică și computațională, analiza chimică, instrumentație, tehnologii de captare si stocare a carbonului, modelarea, simularea, intensificarea, automatizarea și optimizarea proceselor chimice si biochimice etc.

La împlinirea unui secol de activitate didactică și științifică, Facultatea de Chimie și Inginerie Chimică privește cu satisfacție în trecut și cu optimism în viitor.

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The intramolecular interactions in pseudo-geminally substituted [2.2] paracyclophanes induced by chalchogenide halides is reviewed. The subtitution reactions with sulfur dichloride and disulfur dichloride and the addition reactions of selenium dihalides and diselenium dichlorides are highlighted.

Keywords: acetylenes, allenes, [2.2]paracyclophane, propargylic alcohols, selenium halides, sulfur halides

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Inhibitors of electrochemical processes have useful applications in corrosion protection of metals and alloys, as well as in galvanotechnics as levellers for the cathodic metal deposition. Active substances of drugs are good inhibitors, taking into account that they have in their molecules structures containing π electrons or lone pair electrons, being able to adsorb on the metal surfaces through weak physical or strong chemical interactions. Significant inhibition efficiency of several drugs have been proved many years ago, but unfortunately, drugs are expensive and their practical applications as corrosion inhibitors for metal and alloys has been delayed. In the present papers, the studies on the inhibition properties in metal corrosion processes of expired drugs have been emphasized, starting with the paper of R. S. Abdel Hameed, published in 2009. There are few studies on the expired drugs used as levellers in the cathodic metal deposition.

Keywords: expired drugs, corrosion inhibitors, inhibition efficiency, galvanic levellers

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This review article describes the major structural features of layer double hydroxides (LDHs), gives an overview of their synthetic and modification methods as well as the structural characterization possibilities both the generally used and those, which can only be used for specific LDHs. The catalytic use of these materials without calcination, i.e. the layered structure is preserved, are also highlighted. The paper places the authors’ works of about the last decade in the framework of recent papers and review articles of this broad field.

Keywords: layered double hydroxides; synthetic and characterization methods; catalytic application of the as-prepared forms.

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The catalytic potential of triflate-based activated carbon composites has been investigated in phenprocoumon (C3-alkylated compound) synthesis, through the alkylation of 4-hydroxycoumarin with phenyl-ethyl-carbinol. The main reaction products are O- and C3-alkylated compounds. However, O-alkylated product is more easily produced to the detriment of the C3-alkylated compound, the selective synthesis of the last being a challenge in these conditions. Both the conversion of 4-hydroxycoumarin and the selectivity to C3-alkylated compound is highly influenced by the physico-chemical characteristics of the catalysts and the reaction conditions. The highest 4-hydroxycoumarin conversions (16.0- 30.0%) and selectivity to phenprocoumon (94.0-99.7%) were achieved with triflate-based activated carbon composites, characterized by the existence of strong Brønsted acid sites, optimal Lewis/Brønsted acid ratio, and bimodal micro-/mesoporosity.

Keywords: triflic acid; activated carbon, Friedel-Crafts alkylation, 4-hydroxycoumarin; phenprocoumon

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Reactions of imidazolium ylides with dimethyl acetylenedicarboxylate in polar solvents (methanol) were studied. In the competition between cycloaddition versus hydrolysis, the last one prevails leading to base heterocycle, diene structures and benzoate esters. A feasible reaction mechanism is presented. When fused pyrrolo-imidazole derivatives are desirable to be obtained, polar solvents should be avoided.

Keywords: imidazolium ylides, hydrolysis, cycloaddition, reaction mechanism, diene, pyrrolo-imidazole derivatives

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Two series of new fused pyrrolo[3’,4’:3,4]pyrrolo[1,2-a]quinoline and pyrrolo[3',4':3,4]pyrrolo[2,1-a]isoquinoline derivatives were synthesized and evaluated for the antimicrobial activity. The synthetic approach involves cycloimmonium ylides as 1,3-dipol intermediates. The structures of all synthesized compounds were proved by analytical and spectroscopic data. Crystal structure of compound 11a has been also determined by single crystal XRD. The synthesized compounds were evaluated for their expected antimicrobial activity against Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922 and Candida albicans ATCC10231, but no one showed activity against all the reference strains.

Keywords: heterocycles, cycloaddition, quinolines, isoquinolines, antibacterial

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Mesoporous TiO2 coatings were prepared by sol-gel dipcoating method on glass and SiO2 coated glass substrates. They were modified with silver by two different methods: impregnation of as-prepared coatings in AgNO3 aqueous solution; coating deposition from precursor sols containing AgNO3. Transmittance spectra, refractive index, layer thickness and porosity were determined by UV-Vis spectroscopy. Crystallinity of the samples was characterized by XRD, and the morphology and structure by HR-TEM. Photoinduced wettability conversion of the samples was studied, and it was found that the presence of the SiO2 barrier layer and the silver content had significant effect on the wetting behaviour. The photoactivity and reusability of the samples were investigated with methyl orange dye degradation under ultra-violet (UV) irradiation. TiO2 coatings impregnated in 1M AgNO3 solution were found to be the most stable photocatalyst system.

Keywords: TiO2, photocatalysis, self-cleaning, dye degradation, sol-gel coatings

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SnO2 nanoparticles were successfully synthesized by precipitation method, in the presence of hexadecyltrimethyl ammonium bromide (CTAB) and polyethylene glycol 600 (PEG 600) as surfactants. The obtained SnO2 nanoparticles were characterized by X-ray diffraction (XRD), porosity and surface area measurements (BET), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS). Also, photocatalytic properties toward degradation of Rhodamine B (RhB) were investigated. It was found that morpho-structural properties are influenced by the preparative conditions of doped SnO2 nanoparticles.

Keywords: SnO2; nanoparticles; photocatalytic properties

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Fumaric acid, one of the most important organic acids with various applications in industries, can be obtained by fungal fermentation processes, mainly by using Rhizopus oryzae as producing microorganism. The challenges are to maintain pellet morphology of fungy and to optimize the multiple factors that influence fumaric acid production. The main objective of this study is to improve fumaric acid production by varying n-dodecane concentration levels in batch fungal fermentations. This strategy leads to an increase of fumaric acid concentration for about 1.2 times in system with 5% n-dodecane but a higher hydrocarbon concentration induced inhibition phenomenon to fumaric acid production.

Keywords: fumaric acid, fermentation, Rhizopus oryzae, oxygen-vector, ndodecane

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In this paper, the flow of bovine serum albumin (BSA) solutions in physiological serum was investigated at different concentrations from 1 to 10 g/dL and temperatures from 4°C to 80°C. Some peculiar behaviours were depicted as a function of thermodynamic and shear conditions. The intermolecular interactions, the electroviscous effects, the shear forces as well as the temperature influence the shear viscosity of BSA solutions.

Keywords: BSA, shear flow, shear induced aggregation, activation energy, associates

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The ability of different thermodynamic models to predict the phase behaviour of carbon dioxide (1) + 1,2-dimethoxyethane (2) binary system is tested. The model chosen is the General Equation of State (GEOS) coupled with classical van der Waals mixing rules (two-parameter conventional mixing rule, 2PCMR). Comparisons were made with the GEOS3C, Soave-Redlich- Kwong (SRK), and Peng-Robinson (PR) cubic equations of state (EoS) too. A single set of binary parameters for each model was used to predict correctly the global phase behaviour of the system.

Keywords: carbon dioxide, 1,2-dimethoxyethane, high-pressures, vapour-liquid equilibrium, equations of state, GEOS, GEOS3C

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In packed fractionation, the liquid phase can be forced to become continuous, and the vapor phase dispersed, realizing emulsification regime. The paper presents the efficiency comparing results of packed fractionation with respect to the fractionation in an empty flooded column, as well as the influence of the heat flux and of the temperature inside the column’s jacket. Experiments for determining the boiling heat transfer of the different methanol – ethanol concentration mixtures were performed. The variation of the boiling heat transfer coefficient at different concentrations of methanol-ethanol mixtures has a minimum, corresponding to the maximum of the difference between concentrations of vapor phase in equilibrium with the liquid phase.

Keywords: fractionation, flooded columns, boiling heat transfer

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This open-label, non-randomized, two-period and sequential study aimed to evaluate a potential kinetic interaction between zolpidem ((N,N-dimethyl-2-[6-methyl-2-(4-methylphenyl)imidazo[1,2-a]pyridin-3-yl]acetamide), a widely known and used sedative-hypnotic and duloxetine ((3S)-N-methyl- 3-naphthalen-1-yloxy-3-thiophen-2-ylpropan-1-amine), an antidepressant. A total of 23 healthy volunteers received the following medications: period 1 (Reference) - zolpidem 5 mg (single dose) and period 2 (Test) - zolpidem 5 mg and duloxetine 30 mg. Non-compartmental method was employed to determine the pharmacokinetic parameters of zolpidem and its main metabolite, zolpidem phenyl-4-carboxylic acid (Z4CA) while analysis of variance (ANOVA) was used to test the differences between study periods. Zolpidem exhibited similar pharmacokinetics with or without duloxetine (Cmax: 59.64±27.64 ng/mL vs 53.28±22.77 ng/mL, AUC0-t: 239.45±158.26 ng*h/mL vs 217.21±135.95 ng*h/mL, AUC0-∞: 245.87±161.84 ng*h/mL vs 224.61±138.86 ng*h/mL, t1/2: 2.97±2.06 vs 3.12±1.86 h). Subsequently, no marked changes were observed for Z4CA. The statistical test confirmed that duloxetine had no significant influence on the exposure to zolpidem and Z4CA (p < 0.05 for all pharmacokinetic parameters). In conclusion, the study results excluded the possibility of a pharmacokinetic drug-drug interaction between these two drugs. Future investigations should focus on potential undesirable pharmacodynamic effects.

Keywords: zolpidem, duloxetine, kinetic interaction, healthy volunteers

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Rosemary, a native Mediterranean plant is a well-known source of phytochemicals with antioxidant activity attributed mainly to diterpenoids and flavonoids. The aim of the study was to establish an accurate evaluation of the rosemary metabolite profiles from several accessions under changing environmental conditions (water stress and soil salinity) comparing two sampling seasons (summer vs. spring) from four different habitats in Eastern Spain. The methodology was based on the identification and the quantitative evaluation of phytochemicals (phenolic acid derivatives, flavonoids, diterpenes and triterpenes) by HPLC coupled with diode-array detection and electrospray ionization mass spectrometry (ESI+-MS). Phytochemical profiles were statistically compared by factorial ANOVA, cluster analysis, principal component analysis and univariate analysis (Pearson correlations), that allowed the discrimination between the extract composition in correlation to their habitat and stress conditions. Out of twenty-three compounds identified, the major ones were represented by diterpenoids (carnosic acid, carnosol and oxidized metabolites rosmanol, epirosmanol, rosmadial, rosmanol methyl ether) and flavonoids, which showed significant metabolic regulation induced by water stress. The main conclusion of the work is that the diterpene derivatives and their oxidized metabolites maybe considered as optimal biomarkers of the environmental stress in Rosmarinus officinalis.

Keywords: Rosmarinus officinalis environmental stress; high performance liquid chromatography & mass spectrometry; metabolomic profile

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This study aimed to find alternative, cheap and fast procedures to incorporate Doxorubicin in small unilamellar nanoliposomes made of Dipalmitoyl Phosphatidyl Choline and Cholesterol. It was compared the entrapment efficiency of doxorubicin in “home-made” liposomes (1) and in ImmunoSOME liposomes (2), a commercial, expensive formulation. It was obtained an entrapment efficiency of 27.6 % vs 12.1% for formulatios (1) vs (2). The liposomes’ size and zeta-potential of formulation (1) ranged from 116 and 120 nm, being smaller than in formulation (2). The zeta potential was negative for both formulations and showed a better stability and monodispersibility also for formulation (1). This fast procedure is convenient and assure efficient doxorubicin entrapment in the monodisperse nanoliposomes. Such simple formulations, easier to be obtained, can offer also good quality/ price ratios and can be produced at larger scale, with higher incorporation efficiency for experimental in vivo studies which aims the targeted delivery of Doxorubicin to cancer tumors in animals.

Keywords: Liposomes, Doxorubicin encapsulation, size and zeta potential

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A mononuclear complex of Zn(II) with the Schiff base ligand derived from o-vanillin and 2,2-dimethyl-1,3-diaminopropane (H2valdmpn) was obtained and structurally characterized by X-ray diffraction on single crystal. In the [Zn(valdmpn)(H2O)] complex the metal ion is pentacoordianated with a square pyramidal geometry. The luminescent properties of the complex were investigated in solid state and solution following the influence of the solvent.

Keywords: Zinc complexes, bicompartmental ligands, luminescence

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A mercury film was pre-coated on glassy-carbon electrodes to improve the precision and detection limit of the electrodes in anodic stripping voltammetry. A mixed solution containing 0.1 mg/l Zn2+, 0.01 mg/l Pb2+, 0.01 mg/l Cd2+, and 0.5 mg/l Cu2+ was used to investigate the simultaneous detection of these ions by the electrode. The influence of the base solution pH and the accumulation time on the electrochemical reactions of Cu2+, Zn2+, Cd2+, and Pb2+ were investigated, as well as the effect of the concentration of the film coating solution and the number of mercury coating step on the stripping signals of the four ions. Optimizing the parameters of the pre-coated mercury film improved the precision of the glassy-carbon electrode in evidence. When the base solution pH was 4.68, and the accumulation time was 300 s, the positions of the stripping peaks were optimal, and the peak signals were at a maximum. When the concentration of the film coating solution was 0.03 mol/l HgCl2, and the mercury coating step was repeated three times, the prepared electrode showed a moderately high elution peak with little noise. The optimized electrode demonstrated superior precision and detection limits in the simultaneous detection of Zn2+, Cd2+, Pb2+, and Cu2+, compared with the uncoated electrode. The calibration curves were highly linear with determination coefficients (R2) of 0.9913 (Cu2+), 0.9939 (Pb2+), 0.9933 (Cd2+), and 0.9962 (Zn2+); the detection limits (μg/l) were 5 for Cu2+, 1 for Pb2+, 0.1 for Cd2+, and 10 for Zn2+, and the relative standard deviations obtained from five replicate experiments were 4.1% (Cu2+), 2.1% (Pb2+), 2.7% (Cd2+), and 3.4% (Zn2+). It is reasonable to suppose that the precision and detection limits of this mercury film electrode may meet the requirements for the simultaneous detection of multiple heavy metal ions in water in the natural environment.

Keywords: Glassy-Carbon Electrode, Mercury Film, Heavy Metal Ions, Anodic Stripping Voltammetry

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In this study, phenolic compounds, antioxidant and anticholinesterase activities of Cyclotrichium origanifolium (Labill.) Manden & Scheng and Thymus sipyleus Boiss teas were investigated. Two methods were used for the preparation of the teas: infusion and decoction. The quantitative amounts of the phenolic contents were determined by LC-MS/MS. Anticholinesterase activity was measured by Ellman method. Also, the antioxidant activity of the tea samples was determined by three methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, β-carotene linoleic acid and CUPRAC assays. Flavonoids and derivatives were the most abundant components of the C. origanifolium and T. sipyleus teas. The infusion of C. origanifolium and decoction of T. sipyleus were found to be rich in phenolics. The tea samples exhibited beneficial antioxidant and anticholinesterase activities. There is a useful relationship between the antioxidant capacity and polyphenolic composition of the decoction and infusion of C. origanifolium and T. sipyleus. This study supported that C. origanifolium and T. sipyleus used as tea traditionally, are source of natural antioxidant.

Keywords: Cyclotrichium origanifolium; Thymus sipyleus; phenolics; anticholinesterase; antioxidant.

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In this paper, a comparative study of the physico-chemical properties and composition of walnuts and peanuts oils obtained by cold pressing or Soxhlet extraction in hexane was performed. The physical properties (color, density, refractive index, acidity, saponification, iodine and peroxide values, rheological behavior), the distribution of the major fatty acids in oils (through gas-chromatographic analysis) and the metal content were determined.

Keywords: cold pressing, extraction, oil, peanuts, viscosity, walnuts

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Papaver rhoeas L. (Papaveraceae) is an annual grass native to many regions of the world, which is known to possess several pharmacological activities. It is also known that represent a rich source of anthocyanins. In this study, the content of the anthocyanin was determined in the examined various extracts of fresh petals by HPLC analysis. The most represented anthocyanins in the extracts of Papaver rhoeas L. are delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside, peonidin-3-O-glucoside, petunidin-3-O-glucoside, petunidin-3-acetylglucoside, and delphinidin-3-p-coumaroylglucoside. Acyl derivatives of anthocyanins in the water extract have not been identified. By comparing the contents of individual anthocyanins, the glycosides (polar) are better extracted with 50% alcohol solution, and their acyl derivatives are better extracted with pure alcohol. The water solution is the least suitable for anthocyanin extraction.

Keywords: anthocyanins, Papaver rhoeas L., HPLC analysis

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