Catalytic oxidation of Rhodamine B in aqueous solutions with sulphate radicals over Co3O4/MgO and CoFe2O4/MgO
Original Research Article
Pages 761 – 767
I. A. Slavova, St. G. Christoskova, M. K. Stoyanova
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Abstract
The oxidative degradation of Rhodamine B (RhB) in aqueous solutions with peroxymonosulphate (PMS) was studied using Co3O4/MgO and CoFe2O4/MgO as catalysts. The as-prepared samples demonstrated strong PMS-activating ability despite low active phase loading percentage (5 wt%) and very low catalysts concentration ( 0.15 g dm-3). The performance of the supported catalysts was found much better than that of their bulk analogues and mechanical mixtures of corresponding bulk oxide and bare MgO due to the crucial role of basic support for facilitating decomposition of PMS into highly reactive radicals. RhB degradation was found to follow the first order kinetics. The effect of catalyst dosage, PMS concentration, and pH on the rate of RhB oxidation was investigated. The radical species generated from the catalytic decomposition of PMS were identified by quenching studies.

Modeling of the relationship between biological activity of delta-selective enkephalin analogues and docking results by polynomials
Original Research Article
Pages 768 – 774
F.I. Sapundzhi, T.A. Dzimbova, N.S. Pencheva, P.B. Milanov
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Abstract
One of the areas of bioinformatics is the development of fast and reliable methods for predicting the biological activity of compounds. This will facilitate the design of new compounds and reduce costs. The process of creating selective ligands of a delta opioid receptor (DOR) was directed towards the synthesis of enkephalin analogues. Their biological activity was determined by using in vivo and in vitro methods, which allows establishing the relationship between structure and biological activity. The relationship between the values of the ChemScore scoring function from the docking procedure in GOLD 5.2 and the values of the total energy of the ligand-receptor complex in Molegro was modeled with first- to third-degree polynomials and a surface fitted method. The polynomial surface of third degree displayed the best fit, assessed by the least squares method. In our previous study with the theoretical model of DOR (PDBid:1ozc) the relationship between the values of efficacy of the compound, the values of the GoldScore scoring function from the docking procedure in GOLD 5.2 and the values of the total energy of the ligand-receptor complex in Mollegro was established. This relationship was modeled with a third-degree polynomial in software MATLAB. The aim of the present work was to find an optimal fitting polynomial function modeling the relationship between the quantitative parameters of in vitro bioassay and the values of the scoring functions from molecular docking with crystal structure of DOR (PDBid:4ej4) and delta-opioid ligands using the least squares method. The third-degree polynomial was successfully used for modeling the relationship between the efficacy of delta-selective enkephalin analogues and docking results. It was described by a polynomial surface of third degree.

Shear on particles exposed to backswept mixing flow with a view to stress-sensitive cell response
Original Research Article
Pages 775 – 781
S.D. Vlaev, D. Georgiev
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Abstract
The flow impact over a spherical particle immersed in a biofluid at the impeller plane of a stirred laboratory bioreactor is examined. Based on the entire particle surface, the system mimics the flow effect upon living cells at growth being affected by hydrodynamic stress. Backswept (BS) circulation flow showed weak shear effect and was expected to stand as prospective operational means for growth in suspension cultures. A dual modified backswept impeller was selected to generate the flow circulation around the particle. Computational fluid dynamics (CFD) methodology was used. The shear distribution was obtained in the reactor inner volume as well as on the surface of the immersed body. The maximum wall-shear rate values were determined to be in the range from 1200 to 4000 s-1. Evidence is given for areas of critical performance that imply cell damage in practical culture.

Evaluation of chemical composition, energy and biological value of typical Bulgarian traditional foods derivatives
Original Research Article
Pages 782 – 786
D.S. Hristov, S.K. Velikov, V.E. Vodenicharov, S.P. Tsanova-Savov, F.T. Ribarova
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Abstract
A great number of recent scientific studies provide data characterizing the chemical composition of traditional foods from different geographical regions and describe their essentiality for healthy nutrition. The information concerning Bulgarian traditional foods is scarce. The aim of the current study is to assess the energy and biological value of Bulgarian traditional foods by implementing modern scientific approaches to food chemical composition data. The study covers a total of 15 products typical of the traditional Bulgarian diet. The original data are obtained by application of routine methods for the determination of total protein and fat, and classical chromatographic analysis of amino acids (AA) composition. New advanced approaches to assess the proteins biological value and energy content of the studied traditional Bulgarian foods were applied. New information is presented about the composition of amino acids and their proteins biological value in the examined Bulgarian traditional foods. Their energy content was determined in compliance with current scientific requirements. The content of saturated fats is also listed and their necessity and essentiality for health is clarified. The new data for the chemical composition of traditional foods in Bulgarian diet will play an important role in the assessment of nutritional intake, supporting human health and contributing to the revitalization of Bulgarian food chemistry, nutrition and technology.

Spectrophotometric investigations on liquid-liquid extraction systems containing cobalt and tetrazolium salts. Application of the developed method for analysis of the cobalt content of biological samples (mushrooms and tobaccos)
Original Research Article
Pages 787 – 791
L. Dospatliev, M. Ivanova
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Abstract
The study presents a newly-developed method for extraction-spectrophotometric determination of Co (II) in samples by means of iodnitrotetrazolium chloride (INT). According to our studies, the electronic spectrum of the cobalt ion associate has a peak at 630 nm. The INT:[Co(SCN)4] ratio in the triple ion-associate complex was 2:1, and due to the good solubility of the Co(II) ion associate and INT in 1,2-dichloroethane, maximum extraction into the organic phase was achieved for 30 s. The molar absorptivity of the studied ion associate INT2[Co(SCN)4] was ε630 = 0.6×103 L/mol cm. Sandell’s sensitivity of the method was 9.8×10-2 μg/cm2. The maximum quantity of Co was extracted with INT at pH 2-7. Maximum absorption of the extracts was registered at thiocyanate ions concentration (≥ 1M) in the aqueous phase. The ion associate displayed the highest absorption at INT concentration ≥ 6×10-4 М. The relationship between Co (II) concentration and absorption was linear in the range of 6 – 125 μg Co(II) in 10 ml aqueous solutions. The content of Co in Amanita calsarea was 1.543 ± 0.158 mg/kg dry weight, in Boletus pinophilus - 0.257 ± 0.042 mg/kg dry weight and in Burley tobacco - 1.967 ± 0.229 mg/kg dry weight. The extraction-spectrophotometric method for cobalt determination in biological samples with iodnitrotetrazolium chloride, developed in the present study, is characterized with high speed, selectivity and satisfactory accuracy.

Novel dextran/β-cyclodextrin and dextran macroporous cryogels for topical delivery of curcumin in the treatment of cutaneous T-cell lymphoma
Original Research Article
Pages 792 – 799
M. Iv. Slavkova, D. B. Momekova, B. D. Kostova, G. Tz. Momekov, P. D. Petrov
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Abstract
Cutaneous T-cell lymphoma (CTCL) is a rare disease affecting middle-aged as well as paediatric patients. The early stages might be successfully treated with local medications. As a phytochemical with pleiotropic pharmacological activity including anti-inflammatory and anti-cancer activity curcumin presents a safe alternative to the current state for the early therapy of CTCL, albeit its low water solubility and chemical instability. In this study, original sponge-like cryogels based on dextran/β-cyclodextrin mixture and pure dextran were prepared and assessed as platforms for topical controlled delivery of curcumin. Cryogel carriers with macroporous structure were synthesized by photochemical crosslinking in frozen state and subsequent thawing. Curcumin was successfully loaded into the cryogels by physical adsorption and satisfactory encapsulation efficiency was achieved, especially in the case of dextran/β-cyclodextrin systems (57.8 %). The in vitro dissolution tests showed sustained release of the API within 72 h and when dextran/β-cyclodextrin was used as a carrier no burst effect was noticed. In addition, cytotoxicity assessment on both tumour and non-malignant cells was performed whereby comparable activity and selectivity with the free drug were evident. The proposed novel macroporous cryogel systems with curcumin show aptitude for application as controlled dermal drug delivery systems for the treatment of CTCL.

Synthesis of 5-nitrosalicylaldehyde based hydrazones and DFT-calculations of their structure and reactivity
Original Research Article
Pages 800 – 806
B. I. Nikolova-Mladenova, S. E. Angelova
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Abstract
New aroylhydrazones derived from 5-nitrosalicylaldehyde, namely 5-nitrosalicylaldehyde benzoylhydrazone, 5-nitrosalicylaldehyde-4-hydroxybenzoylhydrazone and 5-nitrosalicylaldehyde isonicotinoylhydrazone were designed and synthesized. The compounds were characterized by elemental and thermogravimetric analyses, IR, 1H and 13C NMR spectroscopy. Geometry optimization of the neutral hydrazones were carried out using density functional theory with Becke’s three-parameter hybrid method and correlation functional of Lee, Yang and Parr with 6-31+G (d,p) basis set. The calculated bond lengths and angles of the new hydrazones are in good agreement with the experimental electron diffraction data. Molecular electrostatic potential calculations showed that the most preferred sites for iron chelation are the carbonyl oxygen atom, the imine nitrogen atom and the hydroxyl oxygen atom.

Optimal energy management in brewing
Original Research Article
Pages 807 – 815
D. S. Nikolova, B. B. Ivanov, D. G. Dobruzhaliev
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Abstract
The energy performance is one very important parameter in evaluating the resilience of industrial processes. The optimal usage of the energy is a key task today, because it determines the state of the environment and the final product’s price. In this paper is described a method for minimizing energy consumption by heat integration in conventional brewing. A scheme for heat integration with usage of separated heat tanks is proposed, their aim is to save heat energy. A mathematical model that describes the heat transfer processes is developed. Based on this model is proposed a strategy for optimal management of energy resources with separate heat tanks. The optimization task is formulated in accordance with the mathematical nonlinear programming MNLP and is solved with the program package GAMS. The proposed method was tested with data from a real working production.

Diamond green dye adsorptive removal from water by carrot pulpy waste and potato peels
Original Research Article
Pages 816 – 822
R. Rehman, S. Alam, L. Mitu
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Abstract
Diamond green dye is an example of textile dye. In this study, Daucus carota (carrot) waste and Solanum tuberosum (potato) peels were used for dye removal from water. These are low-cost and commonly available materials. Their adsorption capacity for Diamond green dye was tested for the first time in this study for possible application on industrial scale water treatment. Optimum conditions for the removal of 25 ppm of Diamond green dye from 100 mL of synthetic wastewater by carrot pulpy waste were: 0.6 g adsorbent dose, pH 2.0, 40 min contact time, 30oC temperature and 150 rpm agitation speed. Using potato peels, the optimum conditions were: 0.4 g adsorbent dose, pH 1.0, 15 min contact time, 30oC temperature and 50 rpm agitation speed. Various conditions affecting the sorption of Diamond green dye from water were optimized by carrying out isothermal and kinetic studies. Isothermal studies indicated that chemisorptive mode is predominant over physio-sorption with maximum removal capacities for carrot waste and potato peels of 4.14 and 3.13 mg/g, respectively. Kinetic studies pointed to a pseudo-second order model. Both materials are suitable for bulk-scale removal of Diamond green dye from waste water streams.

Analysis of caffeine contents in commercial beverages and tea samples of Pakistan using UV/Visible spectrometry
Original Research Article
Pages 823 – 828
R. Rehman, S.Ashraf
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Abstract
In this study, caffeine contents in tea samples and beverages were determined photometrically using UV/Visible spectrometry which is a rapid, precise and accurate method. Calibration solutions were prepared in the concentration range of 1-25 ppm from a 100 ppm stock solution. Absorbance of all calibration solutions was measured at the absorption maximum at 274 nm. Caffeine was extracted from tea samples and beverages by chloroform and reading was performed against chloroform as a reference. The concentration of unknown samples was read from the calibration graph. Various concentrations of caffeine were present in the tea samples and beverages. Results showed that in case of tea samples the highest amount of caffeine (16.111 mg/g) was present in Tetley and the lowest amount (0.251 mg/g) - in Ghatnctr. In case of beverages the highest amount of caffeine (222.3 mg/L) was present in Boost and the lowest (0.101 mg/L) - in 7-up.

Experimental studies on a horn-shaped booster pellet
Original Research Article
Pages 829 – 835
L.-Sh Hu, B.-F. Sun
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Abstract
All insensitive munitions contain explosive trains which need to meet insensitive munitions criteria but reliably initiate the main charge explosives. The traditional cylindrical booster pellets have insufficient energy output for reliably initiating the insensitive main charge explosives. To ensure that the requirement can be achieved, a horn-shaped booster pellet having high initiation capacity was designed and experimentally studied. The results show that the horn-shaped booster pellet has higher initiation capacity than the cylindrical booster pellet for the same mass and density of explosive. The convergence pressure of the horn-shaped booster pellet is 34 GPa, which is higher than the value of 27 GPa for the cylindrical booster pellet.

Phytochemical composition and biological activity of Echium italicum L. plant extracts
Original Research Article
Pages 836 – 845
I. D. Bošković, D. A. Đukić, P. Z. Mašković, L. G. Mandić
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Abstract
The aim of this study was to assess the biological activity of five different extracts of the plant Echium italicum L. and to determine their phytochemical composition. The chloroform, ethyl-acetate, ethanol, acetone and petroleum ether extracts of the plant were examined. The ethanol extract of the plant E. italicum had the highest content of total phenolics and flavonoids, while the chloroform and acetone extracts had the highest tannin content. Several different methods were used to determine the antioxidant activity of the tested extracts, and the ethanol and acetone extracts of the plant displayed the best antioxidant activity. HPLC analysis showed that the main phenolic compounds in the tested extracts were rosmarinic acid, chlorogenic acid, p-hydroxybenzoic acid and rutin. Evaluation of the antimicrobial activity of plant extracts was conducted by to the microdilution method. The results of MIC ranged from 3.91 to 500 μg/ml. Determinations of cytotoxic activity were done according to the MTT assay on human rhabdomyosarcom cells (RD), a cell line derived from human cervix carcinoma (Hep2c) and a cell line derived from mouse fibroblast carcinoma (L2OB). This study suggests that the examined extracts of the plant E. italicum L. may serve as sources of antioxidants and antibiotic agents.

Theoretical basis for the corrosion inhibition feature of Argan oil
Original Research Article
Pages 846 – 851
G. Gece
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Abstract
Natural oils play a pivotal role in corrosion inhibition of various metals and alloys. However, their potential inhibition efficiency in acidic media has been barely investigated from a theoretical point of view. Despite a shared experimental justification, the corrosion inhibition feature of such oils resulted in a sustained debate on how the inhibition mechanism could be related to their ingredients. Given the need to better understand the protection behaviour of Argan oil on carbon steel in molar HCl solutions, the electronic properties of two unsaturated fatty acids, i.e., oleic and linoleic acids were studied by density functional theory (DFT) calculations. The protonated forms of oleic and linoleic acids yielded quantum chemical parameters that confirm linoleic acid to be the most stable unsaturated fatty acid, which seems to be responsible for the inhibition efficiency of Argan oil in acidic medium.

Modeling of the physicochemical properties of aliphatic alcohols using topological indices and quantitative structure-property relationship
Original Research Article
Pages 852 – 858
F. Arjmand, F. Shafiei
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Abstract
QSPR models are mathematical equations that attempt to correlate chemical structure with a wide variety of physical, chemical and biological properties. In this study, the relationships between the Randic' (1χ), Balaban (J), Wiener polarity (Wp), Hyper Wiener (WW), Szeged (Sz), Harary (H), and Wiener (W) indices to the entropy (S) , thermal energy (Eth) and heat capacity (CV) of alcohols are presented. Physicochemical properties are determined by the quantum mechanics methodology at the Hartree-Fock (HF) level using the ab initio 6-31G basic set. Multiple linear regressions (MLR) and backward methods were employed to obtain the QSPR models. After MLR analysis, we studied the validation of linearity between the molecular descriptors in the best models for the used properties. The satisfactory results obtained show that the combination of the three descriptors (1χ, J, W) is excellent to predict heat capacity and thermal energy while the three descriptors (J, W, WP) are useful to predict the entropy of the 158 aliphatic alcohols.

Improvement of physical and optical properties of chitosan-rice starch films pre-treated with ultrasound
Original Research Article
Pages 859 – 867
U. Vr. Brodnjak
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Abstract
Transparent films of chitosan, rice starch and a blend of chitosan-rice starch were prepared using water, malic acid and glycerol as a plasticiser. Before casting, the film solutions were treated with ultrasound with a view to improve the physical, optical and surface properties of the films. The results showed that an ultrasonic treatment improved elasticity, moisture resistance and transparency of the films. For all ultrasound-treated films, elongation at break and tensile strength increased, especially for the blend films. Moreover, the moisture content decreased proportionally to the increase in thickness with decreasing film solubility for all treated samples. The surface of the untreated blend film was more uneven compared to chitosan and rice starch films, which improved after the treatment. The preparation of film solutions using ultrasound is an improved procedure to increase many properties of biodegradable films.

Removal of lead (Pb2+) from synthetic wastewater using calcium pectate
Original Research Article
Pages 868 – 873
D. Paliulis, A. Krinickaitė
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Abstract
The present work deals with the use of calcium pectate as a biosorbent for Pb(II) ions removal from aqueous solutions. Surface morphology of the adsorbent was analysed by scanning electron microscopy (SEM). The surface chemical nature of the biosorbent was studied by Fourier transform infrared spectroscopy (FTIR). The FTIR results revealed that amide, ether, alcohol and carbonyl functional groups are responsible for Pb(II) biosorption onto calcium pectate. Batch experiments were carried out to investigate the effects of pH, time, and initial metal ion concentration on the adsorption of Pb(II) ions by the biosorbent in synthetic wastewater. The optimum contact time and pH for the removal of Pb(II) ions were 480 min and pH 5.0, respectively. It was found that the maximum loading capacity of the biosorbent was 4.45 mg·g−1 for Pb(II) ions. Results indicated that the mechanism of Pb(II) ions adsorption onto calcium pectate is ion exchange between Ca(II) and Pb(II) ions in the solution. The equilibrium data were analysed according to the linear forms of the Langmuir and Freundlich isotherms. Freundlich model gives a better fit than the Langmuir model. The results suggest that calcium pectate can be used as an effective, low cost, and eco-friendly green adsorbent for the removal of Pb(II) ions from aqueous solutions.

Study of the possibility of using IXRF technique to detect the elements present in dust using Monte Carlo N Particles
Original Research Article
Pages 874 – 878
H. R. Dehghan, A. Negarestani, M. R. Rezaie
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Abstract
Detecting heavy metals present in soil and dust as a major factor of environmental pollution has got a particular importance. An experimental (laboratory) method based on energy-dispersive X-ray fluorescence (EDXRF) technique was utilized so far to detect the elements. In this research, the Monte Carlo method based on the EDXRF technique was used to detect the elements. MCNPX2.7 code is based on Monte Carlo calculations and is able to trace 32 particles including photons within the range of X-rays and γ-rays. In this paper, the outcomes of multi-source EDXRF simulation technique were compared with the experimental results. The comparison shows that multi-source EDXRF technique(IXRF) is able to detect the percentage of elements present in soil and dust with a high compatibility.

Storage effect on phenolic content and antioxidant activity in selected fruit extracts
Original Research Article
Pages 879 – 883
B. Radovanović, A. Radovanović, V. Nikolić, N. Manojlović, J. Dimitrijević
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Abstract
The objectives of this study were to investigate the influence of light and temperature on the content of phenolic compounds and its correlation with antioxidant activity in selected fruit extracts (strawberry (Fragaria vesca), blackberry (Rubus fruticosus), raspberry (Rubus idaeus), and sour cherry (Prunus cerasus)). The antioxidant capacity evaluated using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH▪) scavenging assays ranged from 90.87% to 96.50%. The content of target phenolic compounds showed high correlation with the antioxidant activity (r2 = 0.829) and with the content of anthocyanins (r2 = 0.995) of the investigated fruit extracts. Total phenol content was monitored in fruit extracts stored at 7 °C for 23 days and at room temperature (25 °C) for 90 days. All fruit extracts exhibited fluctuations in total phenol contents with an initial increase after 4 days, followed by a decrease at both storage temperatures. These changes were not significant during 23 days of storage and the investigated fruit extracts can be used as an easily accessible source of natural antioxidants in food and pharmaceutical supplements.

Preconcentration and determination of cadmium in some samples using solid phase extraction with slotted quartz tube flame atomic absorption spectrometry
Original Research Article
Pages 884– 889
Y. Arslan, D. Trak, E. Kendüzler
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Abstract
In this study, a two-step preconcentration method is proposed for the determination of trace amounts of Cd(II). In the first preconcentration step, Amberlite CG-120 resin was used. After the separation and preconcentration of Cd(II), a slotted quartz tube was used for its FAAS determination. In this part, the slotted quartz tube was used as the second preconcentration step. Some experimental parameters influencing the separation and preconcentration of Cd(II) were separately optimized. The total enrichment factor was found to be 920 after the two steps of preconcentration and the detection limit was found to be 0.1 μg/L. Accuracy of the method was checked by analysing a standard reference material (Environmental Matrix Reference Material, Lake Water, TMDA-70.2). The proposed two-step preconcentration method was applied to the analysis of drinking water.

A comparative study on the ionization constants of a Schiff's base in differentenvironments by multiwavelength UV-Vis spectroscopy
Original Research Article
Pages 890 – 895
K. Alizadeh, H. Soltani-Afarani
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Abstract
In the present study, the Schiff’s base 5-bromo-2-([(2-mercaptophenyl)imino] methyl)phenol was covalently immobilized on agarose, cellulose acetate and sol–gel membranes. A multiwavelength spectrophotometric method was applied to study the acidity constants of immobilized and dissolved forms of the mentioned compound in universal buffer solutions of various pH,recorded over the wavelength range 200- 800 nm. The protolytic equilibrium constants, spectral profiles, concentration diagrams and number of components were calculated. Not unexpectedly, different apparent pKa values were obtained. The values of the acidity constants of 5-bromo-2-([(2-mercaptophenyl)imino] methyl)phenol were different in various environments. The reason was that solute properties, such as ionization constants, depend on the composition and properties of its surrounding sphere, therefore they are very sensitive to membrane components.

Investigation of biodegradation and growth kinetics of dairy wastewater in a batch reactor
Original Research Article
Pages 896 – 900
T. T. Bayram, A. Nuhoğlu, E. Aladağ
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Abstract
In this study, biodegradation of dairy wastewater was investigated under aerobic conditions in a batch reactor. A minimum concentration of 100 mg L-1 and a maximum concentration of 1000 mg L-1 of COD in the wastewater were used. The culture substrate removal kinetics was followed and the specific growth rate was fitted to the Monod model. The kinetic coefficients KS and μmax were found to be 46.55 mg L-1 and 0.0344 h-1, respectively. The regression coefficient was 0.99. The compatibility of actual and predicted results of microbial growth and substrate removal was compared with this model. Results indicated that predicted and actual values fitted each other with 89% compatibility.

Cytotoxicity and DNA binding of copper (II) and zinc (II) complexes of flavonoids: quercitrin, myricitrin, rutin
Original Research Article
Pages 901 – 907
B. Atabey-Ozdemir, O. Demirkiran, U. Yildiz, I. O.Tekin, B. Coban
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Abstract
Flavonoids: quercitrin, myricitrin and rutin and their metal complexes were comparatively investigated for binding to DNA by means of spectrophotometric methods and DNAse activities were evaluated via agarose gel electrophoresis of pBR322. Free flavonoids bind to DNA in an intercalative mode, but Cu(II) complexes of these flavonoids bind even stronger due to the electrostatic interaction of the metal in addition to the intercalation. Flavonoids show protective effect against DNA cleavage in the presence of peroxide. However, Cu(II) and Zn(II) complexes of these flavonoids cause multiple scissions on the DNA backbone. In addition, Cu(II) complexes of the flavonoids have stronger DNAse activity. Moreover, myricitrin was found two times more cytotoxic when combined with metal ions (Cu2+ or Zn2+) than when used alone against peripheral blood mononuclear cells.

DNA binding by copper (II) complexes of semithiocarbazone containing ligands
Original Research Article
Pages 908 – 913
B. Coban, N. Eser, I. Babahan
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Abstract
DNA binding properties of two previously synthesized copper complexes of vic-dioximes bearing thiosemicarbazone units (2E)-2-[4-(dimethylamino)benzylidene]-N-[(1Z,2E)-N-hydroxy-2-(hydroxyimino)ethanimidoyl]hydrazine carbo-thioamide (1) and (2E)-2-[4-(diethylamino)benzylidene]-N-[(1Z,2E)-N-hydroxy-2-(hydroxyimino)ethanimidoyl] hydrazine carbothioamide (2), were investigated using absorption spectroscopy, fluorescence spectroscopy, and agarose gel electrophoresis methods. Experimental studies suggested that the complexes bind to DNA through intercalation. Their intrinsic binding constants (Kb) were calculated as 1: 5.50 ± 0.25 × 104 M−1; 2: 2.10 ± 0.18 × 105 M−1. These complexes also promote the cleavage of plasmid pBR322, both in the absence and presence of hydrogen peroxide.

Liquid-liquid extraction studies of ruthenium(III) from malonate medium using n-octylaniline as an ion-pairing reagent: study of catalyst and alloys
Original Research Article
Pages 914 – 922
A. P. Gaikwad, V. J. Suryavanshi, M. A. Anuse
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Abstract
Herein we have developed a solvent extraction system for ruthenium(III) by using 0.1 M n-octylaniline in 0.05 M malonate medium at pH 3.5. Various operational parameters like pH, reagent concentration, weak organic acid, equilibrium time, and loading capacity of extractant were optimized for the quantitative recovery of ruthenium(III). Stoichiometry of the extracted species was resolved by the slope ratio analysis method. The extraction takes place by formation of an ion-pair complex between the [CH3(CH2)7C6H4NH3]+(org) species and the [Ru(C3H2O4)2]-(aq) species. The association of these two species yielded the uncharged neutral extractable species [CH3(CH2)7C6H4NH3+ Ru(C3H2O4)-2](org). The stoichiometry of the extracted species was found to be 1: 2: 1 (metal: acid: extractant). The soundness of the proposed method was checked by extracting ruthenium(III) from binary and ternary mixtures and various catalysts were also investigated.

Chemical composition and bioactive properties of the essential oil of Rhinanthus angustifolius subsp. grandiflorus
Original Research Article
Pages 923 – 927
A. A. Kaya, O. Üçüncü, Ş. M. İlter, C. Baltacı, S. Öztürk
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Abstract
In this study, the chemical composition and antimicrobial activities of the essential oil of the Rhinanthus angustifolius subsp. grandiflorus plant were investigated. Essential oil was obtained from all parts of the plant by hydrodistillation and was analyzed by GC-FID and GC-MS. 31 components representing 99.46% of the total oils were characterized. The main components of these species were found to be 2,3-dihydro-5-methyl-1H-indene (25.14%), α-cubebene (19.27%), 1-hexadecene (15.59%) and hexadecanoic acid (12.14%). The antimicrobial activity of the isolated essential oil was investigated. Antimicrobial activity was observed against B. cereus, E. coli, E.coli O157:H7 and S. Aureus microorganisms. Moreover, an effect on the ferments of B. cereus, E. coli, E.coli O157:H7 and S. Aureus was detected.

GC analysis in evaluation of changes in fatty acids content of selected fats during storage and heating
Original Research Article
Pages 928 – 935
R. Kowalski, G. Kowalska, U. Pankiewicz, M. Sujka, K. Kałwa
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Abstract
The purpose of the paper was the comparison of quantitative changes in fatty acids composition in selected fats (soybean, sunflower, rapeseed, and olive oils, as well as margarine, butter and porcine lard) during their storage and heating. Comparison of quantitative analysis results expressed as absolute fatty acids amounts (g 100 g-1 – internal standard addition method) with their relative contents after summing up the analyzed components to 100% (internal normalization method), is presented. Experimental data revealed a great differentiation between quantitative results of particular fatty acids groups expressed as absolute amounts (g 100 g-1), and as percentages assuming that the sum of fatty acids in a sample was 100%. In general, the obtained results indicated that long-term storage at both ambient and elevated temperature led to a decrease in SFA, MUFA and PUFA contents (g 100 g-1 of sample) in the triacylglycerols fraction. Comparison of absolute and relative contents indicated that more credible results could be achieved only by means of analytical techniques based on internal standard addition or other analytically-equivalent methods that can give a full quantitative representation of the absolute amounts of substances tested.

Preparation of modified diatomite filler via a starch-fatty acid complex coating method for improvement of paper strength properties
Original Research Article
Pages 936 – 942
W. Shang, X. Qian, H. Liang
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Abstract
In this work, diatomite particles were modified to improve the bondability of diatomite particles with pulp fibers via a starch-fatty acid complex coating method. The SEM results illustrated that the surface of the modified diatomite particles was covered by the complex coatings. The coating efficiency of the starch-fatty acid complex on diatomite surface was up to 98%. Modified diatomite had good shear resistance. Compared with the handsheet filled unmodified diatomite, the handsheet filled with modified diatomite had higher strength properties and smaller bulk. The higher zeta potential and larger particle size of modified diatomite were responsible for the higher retention of modified diatomite filler. This work provided a technical support for the application of diatomite as a novel papermaking filler.

Influence of sensitizing treatment on the corrosion resistance of Incoloy 028 alloy
Original Research Article
Pages 943 – 947
Z.Q. Yu, G.S. Zhou, S.D. Zhu, J.M. Li, L.J. Li
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Abstract
The influence of the precipitated phases on Incoloy 028 alloy was investigated via a sensitizing treatment at various sensitizing times and temperatures, weight loss and electrochemical testing methods were used, and the influence of the precipitated phases on the corrosion resistance on Incoloy 028 alloy was discussed on the basis of the significant characteristics of the polarization curves and Nyquist plots. The results showed that the corrosion resistance of Incoloy 028 was influenced by the precipitated phases; the corrosion rate of Incoloy 028 alloy initially increased and then decreased with the increasing sensitizing temperature; the most severe corrosion occurred at 900 oC; and the elemental contents of Cr and Mo in the corrosion area were lower than those in the non-corroded area on the alloy surface, indicating that the corrosion resistance on the precipitated phase area was weakened..

Influence of nano-serpentine mineral powder as a lubricating additive on the high- temperature tribological properties of metal friction pairs
Original Research Article
Pages 948 – 954
Z. N. Jia, Y. Y. Yang, X. W. Qi, X. M. Song
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Abstract
High-temperature tribological properties of 45 steel friction pairs were investigated, and nano-serpentine mineral powder (nano-serpentine), nano-serpentine mineral powder + nano-lamellar expandable graphite (Nano-EG + nano-serpentine) were used as mineral oil additives, respectively. By means of SEM, TEM and EDS, the worn surface morphology and composition distribution on the contact surfaces with different lubricating additives at high temperature were compared and analyzed. The results show that under high-temperature conditions, using nano-serpentine mineral powder and Nano-EG combined as lubricating oil additives, a self-repairing transfer film is formed. At an early high-temperature friction stage, the friction coefficient decreases with time, which leads to better anti-friction properties. As regards wear resistance, the high-temperature friction tribological properties of 45 steel with a Nano-EG + nano-serpentine additive were superior to those with only nano-serpentine mineral powder additive, which is mainly due to the combination of the good self-lubrication property of Nano-EG and the self-repairing effect of the nano-serpentine mineral powder.

Identification of Clenbuterol by MALDI-TOF Mass Spectrometry
Original Research Article
Pages 955 – 960
Q. Huo, T. Zhou, J. He, J. Q. Xue
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Abstract
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry（MALDI-TOF-MS）was used to analyze macromolecular compounds. The present study focused on how to use MALDI for determination of small molecules such as clenbuterol, and how to explore the matrix to improve the sensitivity. The macromolecular 1,2, 3,4-tetrakis(3',4'-hydroxyphenyl) thiophene matrix not only absorbed the laser energy but also caused sample desorption ionization. At the same time, it did not produce interfering ions of low molecular weight. Moreover, when perfluoro C60 was added to the matrix, sensitivity was improved.

Quality grading system of Jadeite-Jade green based on three colorimetric parameters under CIE standard light sources D65, CWF and A
Original Research Article
Pages 961 – 968
GuoYing
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Abstract
The article deals with the color changes appearing under different light sources due to the individual and combined effects of lightness, hue and chroma. As a result, a green color grading system is created based on color evaluation from its appearance. We tested the color of 277 pieces of green jadeite specimens using Color i5 spectrophotometer based on CIE 1976 L*a*b* uniform color space and Munsell color matching system. It was concluded that the CIE standard light source D65 is more suitable for assessing jadeite-jade green compared with the CIE standard light sources CWF and A. After the alternate use of light sources D65 and A, the color shows a slight yellow tone. While the light source changed from D65 to CWF, the lightness of jadeite-jade green decreased sharply. The jadeite-jade green concentrates on the lightness scope of (5.64, 61.96), and most of them focus on the scope of moderate to brighter lightness of (30, 60). It is shown that the optimal green of jadeite-jade is deep and dark. The support vector machine (SVM) predicts that 20 of 35 unclassified jadeite-jade cabochons should have a corresponding level based on the color green grading system of jadeite-jade. Taking into account the combination of theory and practice, the conclusion is drawn that the color green grading system of jadeite-jade should be calculated in the CIE 1976 L*a*b* uniform color space combined with the Munsell color system for physical color comparison.

Study on the water resistance performance of floor rockmass under different fracture combinations
Original Research Article
Pages 969 – 976
H.L. Yu, J.M. Zhu, Y.S. Zhang, W.Q. Zhang , Zh.Ch. Wang
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Abstract
To obtain the water resistance performance of floor strata under different rock layers and fracture combinations, the propagation mechanisms of different crack combinations in floor strata under mining conditions were simulated by using singular elements. The propagation path of twin cracks under different situations was given by the minimum plastic zone theory according to the change of the fracture factor and the plastic strain of different strata combination cracks under the influence of fault, water pressure and mining. The shortest length of the rock bridge between twin cracks after bursting in different strata combination was obtained. The water resistance performance of every strata combination was analyzed. It was shown that the water resistance performance of the floor strata under the combination soft-soft-hard-hard upward is the worst while the combination of alternating soft-hard is the best. The fracture factor combination and the plastic strain of the crack will reach maximum when mining near to it, and the crack is mostly easy to extend. The shortest length of the rock bridge between the twin cracks after bursting is under the combination of soft rock layers below and hard rock layers above while it is the longest under the combination of alternating soft-hard. The length of the rock bridge between the twin cracks after bursting will be shortened when considering the water pressure inside the crack and fault, which results in a decrease in rock water resistance performance. This paper will provide a reference for floor water inrush prediction in fractured rock mass.

Stagnation point nanofluid flow along a stretching sheet with non-uniform heat generation/absorption and Newtonian heating
Original Research Article
Pages 977 – 985
B. K. Mahatha, R. Nandkeolyar, M. Das, P. Sibanda
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Abstract
The non-uniform heat generation/absorption and Newtonian heating effects on the steady two-dimensional laminar stagnation point boundary layer nanofluid flow past a stretching sheet in the presence of an external uniform magnetic field is investigated. The nanofluid is assumed to be viscous, incompressible and electrically conducting. The effects of Brownian motion and thermophoretic diffusion are taken into account. The governing non-linear partial differential equations are transformed to a set of ordinary differential equations in similarity form which are then solved using Spectral Relaxation Method (SRM). The effects of pertinent flow parameters on the flow, heat and nanoparticle concentration are studied with the help of graphs and tables. The nanofluid model presented in the paper has significant applications in the fluid engineering process where simultaneous effects of heat generation and convecting heating of the bounding surface take place such as in heat exchangers and nuclear reactor cooling.

Mathematical modeling of thin-layer microwave drying of corn husk and investigation of powder properties
Original Research Article
Pages 986 – 993
A. Akdoğan, G. Çalışkan Koç, S. N. Dirim
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Abstract
The aim of this study is to investigate the effect of different microwave powers on the drying kinetics of chopped corn husks and to determine the properties of the corn husk powder obtained after grinding the dried product. The drying behavior of corn husks was determined using eleven commonly used thin-layer models. The obtained powders were analyzed for moisture content, water activity, color, tapped and bulk densities, wettability, flowability, and cohesiveness. In addition, the effective moisture diffusivity and activation energy of corn husks were calculated from drying data. From the analysis of the results, the drying rate and the drying time of corn husk slices considerably decreased with increasing microwave power. Among all used drying models, the Page model was found to satisfactorily describe the kinetics of microwave drying of corn husk. The effective moisture diffusivity values ranged from 2.264×10-10 to 8.941×10-10 m2s-1.

Ultrasound-assisted dispersive liquid-liquid microextraction with HPLC-UV for the simultaneous determination of Diclofenac potassium and Indomethacin in serum and plasma samples: Experimental design and optimization
Original Research Article
Pages 994 – 1000
N. Chamkouri, V. Zare-Shahabadi, A. Niazi
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Abstract
TIn this work, a rapid, simple, and environmentally friendly method based on ultrasound-assisted dispersive liquid-liquid microextraction (UADLLME) was proposed for simultaneous determination of diclofenac potassium and indomethacin in serum and plasma samples. High performance liquid chromatography with UV detection (HPLC-UV) was used. The expermental conditions, including pH of sample solution, type of extraction solvent, time of ultransound, centrifugation condition and ionic strength were investigated and optimized. After screening out the factors with insignificant effect, the remaining factors were optimized using the Central Composite Design. Under the optimal conditions, detection limit were found as 1.09 and 2.18 ng mL-1 for diclofenac potassium and indomethacin respectively and relative standard deviations (RSD) of the analysis less than 3% (n= 5) and detection. Mean recoveries of both in human plasma and serum samples were in the ranges of 92–99%. UADLLME - HPLC-UV was successfully applied for the simultaneous determination of diclofenac potassium and indomethacin in human plasma and serum samples.