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The paper aimed to determine humus quality in Terra rossa soils under olive groves with different soil management types. A total of 10 top-soil samples (0-20 cm) were collected in olive groves of Middle Dalmatia, Croatia, out of which 5 were from the traditional low-input olive groves (TOG) and 5 in the intensive olive groves (IOG). The soil samples were analyzed for basic soil properties, soil organic carbon (SOC), and fractional composition of humic substances. Spectroscopic characterization of humic substances was carried out by measuring absorbance in the VIS spectral range (400-700 nm). Optical index E4/E6 (ratio of optical absorbance at 465 to 665 nm for humic substances in solution) was calculated. The mean value of SOC in soils under TOG (3.06%) was lower than in soils under IOG (3.88%). Higher variations of carbon in humic (CHA) and fulvic acid (CFA) were observed in the soils under IOG. The mean CHA/CFA ratio in soils under TOG was higher than in soils of IOG (1.78 and 1.26, respectively). The soils under TOG had fulvic-humic to humic types, while the soils of IOG had humic-fulvic to humic types of humus. A lower mean E4/E6 index of soils under TOG than IOG (3.78 and 4.36, respectively) confirmed the results of the classical analytical method. Our findings reveal higher variation and lower humus quality in soils under intensive olive cultivation.

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The study aimed to evaluate the humus quality of anthropogenic soils derived from flysch deposits. A total of 10 samples were collected in the top-soil horizon (0-20 cm) of olive groves in Kaštela Bay in Middle Dalmatia, Croatia. Five samples were taken from traditional low-input olive groves (TOG), and the other five samples were from intensive ones (IOG). The soil samples were analysed for basic soil properties: particle size distribution, pH, carbonate content, P2O5, K2O, and soil organic carbon (SOC) content. Humic substance isolation was done following the procedure given by Schnitzer (1982). Spectroscopic characterization of humic substances was carried out by measuring absorbances in VIS spectral range (400-700 nm). Optical index E4/E6 (ratio of optical absorbance at 465 and 665 nm for humic substances in solution) was calculated. The mean value of SOC content in soils of TOG was lower than in soils under IOG (1.20 and 1.60%, respectively). The absorption spectrum of the studied soils showed a monotonous decrease of absorbance from 400 to 700 nm. The E4/E6 indices for soils under TOG varied from 4.60 to 5.00, while for soils under IOG were in the range of 4.83 - 6.89. The E4/E6 indices > 4 revealed low humus quality in studied soils. However, soils under TOG have lower mean values E4/E6 index in comparison to soils under IOG (4.76 and 5.70, respectively), indicating slightly higher humus quality. [ABSTRACT FROM AUTHOR]

The collection Manuscripta Americana in Berlin consists of fragmented codices acquired by Alexander von Humboldt in Mexico. Some of these Humboldt Codices are published as hieroglyphic writings of the Aztecs in “Vues des Cordilleres et Monuments des Peuples indigènes de l’Amerique”. Starting from a special compilation of seven fragments on plate 36 in the “Atlas”, we investigated the corresponding original fragments using material analysis in order to clarify their historical relations. The analyses were carried out with X-ray fluorescence analysis, VIS spectroscopy, and infrared spectroscopy in diffuse reflection and revealed typical indigenous colors like cochineal, indigo, and organic yellows (e.g. mangrove and zacatlaxcalli). Four fragments under investigation show exactly the same material and thus must once have belonged together in one compendium. An additional manuscript from Mizquiahuala also shown on plate 36 can be matched to another one that is not published in the “Atlas”.

The collection Manuscripta Americana in Berlin consists of fragmented codices acquired by Alexander von Humboldt in Mexico. Some of these Humboldt Codices are published as hieroglyphic writings of the Aztecs in "Vues des Cordilleres et Monuments des Peuples indigènes de l'Amerique". Starting from a special compilation of seven fragments on plate 36 in the "Atlas", we investigated the corresponding original fragments using material analysis in order to clarify their historical relations. The analyses were carried out with X-ray fluorescence analysis, VIS spectroscopy, and infrared spectroscopy in diffuse reflection and revealed typical indigenous colors like cochineal, indigo, and organic yellows (e.g. mangrove and zacatlaxcalli). Four fragments under investigation show exactly the same material and thus must once have belonged together in one compendium. An additional manuscript from Mizquiahuala also shown on plate 36 can be matched to another one that is not published in the "Atlas". [ABSTRACT FROM AUTHOR]

Herein, the proof of concept of a sodium polysulfide battery consisting of two electrode chambers being separated by a solid electrolyte is described. The concept is suited for dissolved polysulfide cathodes and has the advantage that both half reactions can be optimized separately. The formation of solid sulfide discharge products is identified as the major limiting factor for cell cycling. This issue can be alleviated by adding solid P2S5. Further improvement can be achieved by replacing diglyme (2G) as the cathode compartment solvent with tetramethylurea (TMU). Using TMU, the cell cycles with Coulombic efficiencies >99% and capacities of 800 mAh g−1 are maintained for at least 30 cycles. Viscosity, density, conductivity, and the electrochemical stability window values of the 2G‐ and TMU‐based electrolytes are compared. The latter shows higher viscosity (2.806 vs 1.603 mPa s), higher density (1.016 vs 0.996 g cc−1), and higher conductivity (4.27 vs 1.45 mS cm−1). The oxidative stability limit of the TMU electrolyte is 3.2 V versus Na+/Na, which is sufficient for polysulfide redox reactions. Vis spectroscopy is used to follow the electrode reaction. In case of TMU, the reaction is based on the redox activity of S3−• radicals (blue coloration of the catholyte solution). [ABSTRACT FROM AUTHOR]

The collection Manuscripta Americana in Berlin consists of fragmented codices acquired by Alexander von Humboldt in Mexico. Some of these Humboldt Codices are published as hieroglyphic writings of the Aztecs in "Vues des Cordilleres et Monuments des Peuples indigènes de l'Amerique". Starting from a special compilation of seven fragments on plate 36 in the "Atlas", we investigated the corresponding original fragments using material analysis in order to clarify their historical relations. The analyses were carried out with X-ray fluorescence analysis, VIS spectroscopy, and infrared spectroscopy in diffuse reflection and revealed typical indigenous colors like cochineal, indigo, and organic yellows (e.g. mangrove and zacatlaxcalli). Four fragments under investigation show exactly the same material and thus must once have belonged together in one compendium. An additional manuscript from Mizquiahuala also shown on plate 36 can be matched to another one that is not published in the "Atlas". [ABSTRACT FROM AUTHOR]

In this work two new perchlorate based inorganic salts with N -methylformamide (NMF) as a crystal solvate, Cu(ClO 4) 2 ·4NMF and Ni(ClO 4) 2 ·6NMF were synthesized and their structures confirmed by X-ray analysis. The influence of water content on absorption spectra M(ClO 4) 2 · x NMF (where M = Co, Ni or Cu) in water ˗ N -methylformamide mixtures was investigated and overall molar absorption coefficients were calculated. Density, viscosity and electrical conductivity measurements of these salts in NMF were performed at the temperature T = 298.15 K, atmospheric pressure and in the concentration range up to ~0.2 mol·dm−3. All obtained results are compared with those obtained in water. From the calculated volumetric and viscometric parameters, nature of interactions between transition metal ions with peptide bond model system based on NMF were discussed. • Anhydrous Cu(ClO 4) 2 ·4NMF, Co(ClO 4) 2 ·6NMF and Ni(ClO 4) 2 ·6NMF were investigated. • VIS spectroscopy, density, viscosity, conductivity of {M(ClO 4) 2 · x NMF + NMF; x = 4 or 6} were performed. • Indicated water molecule replacement with NMF molecules in ions coordination sphere. • Strong ion-dipole interactions and complexes formation between NMF molecules and investigated ions. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles have received great interest for their use in cancer diagnostics and therapy. They can be loaded with the chemotherapeutic agents and used for the targeted delivery to the tumor and the retention of the drugs there under the external magnetic field. In the present paper, we investigated the interaction between magnetic Fe3O4 nanoparticles, both bare and coated with trisodium citrate, and anticancer drug doxorubicin in the base and acidic forms, respectively. The changes in the drug absorption spectra in the visible region and the shift of ferromagnetic resonance spectra taking place at the drug-nanoparticle interaction were analyzed. The spectrophotometric titration data were processed using the Langmuir model of equilibrium binding. For both systems, we report the calculated thermodynamic binding parameters including the drug-nanoparticle binding constants and binding site sizes. We show that in order to interact with the doxorubicin molecules in acidic form, the surface of the nanoparticles needs to be modified with trisodium citrate which provides their surface with the negative charge. At the same time, the bare magnetite nanoparticles are able to interact with the base form of the drug. The comparison of the binding parameters in both systems has shown that the nanoparticle-citrate-doxorubicin system is more promising in terms of biomedical application. [ABSTRACT FROM AUTHOR]

Highlights • FT-IR combined with PLS estimate the ageing level of Sherry wine. • Vis spectroscopy combined with PLS estimate the ageing level of Sherry wine. • Chromatic parameters combined with PLS estimate the ageing level of Sherry wine. • Spectroscopic analysis can improve the ageing system for Sherry wines. Abstract During the ageing period, diverse physicochemical changes occur affecting the quality of the final product. For this reason, it is important to study and optimize this step. Fourier transform infrared (FT-IR) and UV–visible (UV–Vis) spectroscopic techniques combined with multivariate analysis were used to obtain regression models to correlate both spectroscopic data and chromatic parameters with the ageing level of high quality Sherry wines. Three spectral ranges were obtained that contain the highest variance: two different fingerprint ranges in FT-IR (1100–2000 cm−1 and 2300–2999 cm−1) and one range in the visible region (380–450 nm). The regression model has enabled full differentiation between the seven levels of ageing in the wine explored. A good linear regression fit (R2 above 0.95) was obtained regardless of the ranges used. The results demonstrate that both spectroscopic techniques can be used to optimize the ageing process in a simple and fast way. [ABSTRACT FROM AUTHOR]

Abstract In industrial electrodialysis (ED) processes, to ensure a stable and reliable operation for a long period, alkaline cleaning processes, such as cleaning in place (CIP), are often used to suppress fouling of anion exchange membranes (AEMs). However, alkali CIP causes a reduction in the AEM performance, especially for AEMs containing polyvinyl chloride (PVC) as backing cloth and/or binder. To clarify the relationship between alkali attack and performance reduction of AEMs quantitatively, an alkali immersion test was conducted using a commercially available AEM containing PVC, with different immersion times, at various temperatures and NaOH concentrations, to obtain test pieces. Electrochemical and mechanical measurements of the test pieces revealed a reduction in Young's modulus and subsequent increase in water content of the AEMs and resulted in a reduction of the electrical resistance and proton rejection of the AEMs. ATR-FTIR and XRF analyses support that dehydrochlorination of PVC and production of polyene in the AEMs by alkali resulting in such performance reductions. Visible light (VIS) absorption and microscopic observation of the test pieces showed that polyene was produced in the backing cloth and binder. Moreover, using the VIS absorbance data, a prediction method for performance reduction in an AEM was proposed. Highlights • Anion exchange membranes (AEMs) with PVC were immersed in various alkali solutions. • Polyene formation was observed in both backing cloth and binder in the AEMs. • Young's modulus of the AEMs affects its water content. • Modified spring model can explain the change in water content observed in the tests. • Using absorbance at 600 nm, the change in electrochemical properties can be predicted. [ABSTRACT FROM AUTHOR]

A new compound, [Nd(NCS) 3 (2,2′-bipyridine) 2 (H 2 O)] (C 28 H 24 N 8 NdO 2 S 3 ), was obtained and investigated for its photophysical properties. Coordination systems of lanthanide-organic compounds are promising materials with applications as efficient luminophores. Organic ligands with chromophore groups (for example double bonds or aromatic rings) can intensify luminescence efficiency (antenna effect). The title compound crystallizes in a triclinic system with the space group P-1 and the following unit cell parameters: a = 9.698 (3), b = 13.000 (4), c = 13.219 (4) Å, α = 110.36 (3), β = 94.12 (2) γ = 97.53 (2)°. The coordination number of the Nd 3+ ion is 8. The molecules of 2,2′-bipyridine coordinate to the Nd 3+ ion via N atoms. Thus, the neodymium complex, based on this ligand, might have different optical properties from complexes with coordinating Nd–ligand bonds via O atoms bonds only. Additionally, we used another ligand – isothiocyanate ion – inorganic ion, which also coordinates via N atoms. In the absorption and emission spectra of the title compounds at low temperatures, the splitting of the 4f–4f transitions indicates a single low symmetry of the Nd 3+ ion in the title compound. This fact confirms our X-ray structural results. The lower nephelauxetic parameter (β), positive bonding parameter (b 1/2 ), and Sinha parameter (δ) indicate a somewhat covalent character of the bond between the metal and the ligand but the Nd N,O coordination bonds of [Nd(NCS) 3 (2,2′-bipyridine) 2 (H 2 O)] indicate a more covalent character than Nd O-only bonds but less covalent than Nd N-only bonds. The experimental data of the decay time of the 4 F 3/2 state of the Nd 3+ ion for the title compound were fitted using the biexponential function. These values are small and amount to 0.65 and 0.16 μs [ABSTRACT FROM AUTHOR]

Fe doped SnO2 transparent thin film nanostructures were grown by chemical solution deposition and its electric field induced resistive switching properties were investigated for non-volatile resistive random access memory (RRAM) applications. Simple, low temperature solution process growth of SnO2:Fe thin film nanostructures was employed. Grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM), respectively, confirmed a phase pure cubic growth with mono-disperse nanocrystallites of ~ 20 nm. Sharp interface with substrate and top metal electrodes were achieved. Reproducible hysteresis in the I-V curves with symmetrical resistance switching ratio of more than 4 x 103 at a low operating voltage of ± 1.1 V has been demonstrated. Large values of memory retention of about 5 moths; confirmed the nonvolatile behaviour of the device cell consisting of Ag/SnO2:Fe/Ag planar structure. A mechanism involving the space charge limited current combined with Schottky conduction at the metal/oxide interface is proposed. A possible mechanism of the formation and rupture of conducting filament is proposed based on the Joule heating effect with external electron injection at the Ag/SnO2 interface. [ABSTRACT FROM AUTHOR]

A novel cell for complex spectroelectrochemical and nanomorphological characterization of phthalocyanine has been developed. The applicability and universality of the cell allows performing both in-situ and ex-situ characterization of the same sample, in solid and solution state, respectively, which was demonstrated on tetramethyltetra-3,4-pyridine-porphyrazino cobalt as water soluble and tetraneopentoxyphthalocyanine cobalt as water insoluble phthalocyanine based compound. The cell is composed of a planar freely replaceable bottom formed by a basal plane of highly ordered pyrolytic graphite. It allows complete characterization of modified electrode on same electrode, from spectral observation of modification process via atomic force microscopy to spectroelectrochemical characterization of redox and catalytic behavior. The relatively inert HOPG electrode serves as a substrate for phthalocyanine compounds and also as a backscattering mirror for in-situ reflection spectroscopy. This makes the cell suitable for spectroelectrochemical studies of phthalocyanine both as HOPG-supported thin film and in the solution. Moreover, the cell can take the advantage of optional utilization of supported thin layer interface of two immiscible electrolyte solutions allowing spectroelectrochemical analysis of sub-microgram quantities of water insoluble compounds. Graphical abstract: . [ABSTRACT FROM AUTHOR]

The aim of the article is to investigate the potential of honey discrimination (on the base of its botanical origins) by Vis spectroscopy and chemometric analysis. Fifty-five samples from three types of honey (acacia, linden, and honeydew) are measured by a spectrophotometer "Helios Omega" with recorded wavelength range of 380~780 nm for calibration of honey classifier. Firstly, principal components analysis (PCA) is used for reducing the number of inputs and for a proper visualization of the experimental results. Next, the first two principal components (PCs) are combined separately with k-means clustering (KMC), Naïve Bayes classification (NBC), and linear and quadratic discriminant analysis (LDA, QDA) to develop PC-KMC, PC-NBC, PC-LDA and PC-QDA models, respectively. The comparative analysis of the four classifiers is based on leave-one-out-cross validation test carried out in MATLAB environment. [ABSTRACT FROM AUTHOR]

We have synthesized a series of NiII-pdto complexes - [Ni(pdto)(NO3)]NO3·H2O (C1), [Ni(pdto)(H2O)2](NO3)2 (C2), and [Ni(pdto)(NO3)(H2O)]NO3 (C3), with pdto = 1,8-bis(2- pyridyl)-3,6-dithiaoctane - with different spectroscopic responses associated with the coordination modes of the nitrato moiety. Through UV/Vis spectroscopy and electrochemical experiments it was established that in acetonitrile solution the compounds C1, C2, and C3 are each transformed into the same chemical species [Ni(pdto)NO3]+. Cyclic voltammetry experiments gave evidence of two consecutive one-electron transfers associated with NiII-(pdto) + 1 e-→NiI- (pdto) and NiI-(pdto) + 1 e-→Ni0 + pdto processes, which are in agreement with the high flexibility of the pdto ligand with regard to accommodating the preferred geometry of the central atom. The complexation reaction between pdto and the starting salt Ni(NO)3·6H2O in acetonitrile was also studied by UV/Vis spectroscopy and cyclic voltammetry. A linear relationship between the experimentally determined value of 10 Dq and the Δ(EHOMO-LUMO) energy values obtained by computational methods was found. [ABSTRACT FROM AUTHOR]

A series of N -methyl alkylaminomethane-1,1-diphosphonic acids ( 3a – g ) with a common tertiary nitrogen atom (CH 3 –N–R) bearing linear or branched alkyl, cycloheptyl or phenylalkyl R substituents was synthesized in the reaction of diethylphosphonate with triethyl orthoformate and secondary amine followed by hydrolysis, and by the Eschweiler–Clarke methylation of the alkylaminomethane-1,1-diphosphonic acids with formic acid and formaldehyde. Complex-formation abilities of 3a – g towards copper(II) in solution were studied by means of pH-potentiometry, ESI-MS spectrometry, UV–Vis and EPR methods. Evaluation of stability constants for the Cu(II) complexes of 3a – g has revealed their dependence on a combination of steric and electronic effects imposed by R substituents. It has been demonstrated that compounds with linear or branched alkyl on the N atom ( 3a , 3d , 3e ) form the most stable complexes with Cu(II), the least stable are complexes of 3f , which can be attributed to the steric effect imposed by cycloheptyl ring attached directly to the N atom. In addition to the main [Cu(HL) 2 ] complexes, with well-known {O, O} chelating binding mode, [Cu(HL)L] and [CuL 2 ] species with the {O, N} donor set, protonated dinuclear [Cu 2 H x L 3 ] ( x = 4, 5, 6) species have been detected in all studied systems. The nitrogen coordination in the [Cu(HL)L] and [CuL 2 ] complex has been confirmed by Vis and EPR spectra. [ABSTRACT FROM AUTHOR]

Red-purple natural sensitizers are prepared from anthocyanins and betalains rich section of plants which are extracted by simple methods without further modifications such as commercial juice (Welch grape juice) and juices obtained by fresh squeezing or hot water extraction. No special treatments on the surface of TiO2 electrode has been made to enhance the adhesion between natural dye and TiO2. An outstandingly high power conversion efficiency (η) of DSSCs are obtained from purple yam (2.05%), pomegranate (1.35%) and Welch grape juice (0.82%). ORAC (Oxygen Radical Absorbing Capacity) and VIS spectroscopy data can be used as a guideline for the conversion efficiency indicator of DSSCs using anthocyanins (without tannins) dyes. On the contrary, only ORAC can be used as a guideline for the conversion efficiency indicator of DSSCs in the case of anthocyanins (with tannins) dyes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Relationship of absorbance difference index (IAD) to internal quality of stored apples evaluated. [•] ‘Fuji’, ‘Royal Gala’ and Aurora Golden Gala™ tested in air and CA stored apples with 1-MCP treatment. [•] IAD index does not consistently correlate to internal quality attributes when 1-MCP or CA is applied. [ABSTRACT FROM AUTHOR]

Gold nanoparticles are attractive as sensing materials because of their size and shape are related with their optical properties. The color change produced by the aggregation of functionalized AuNPs allows the detection of arsenic at low levels. A simple, cheap and fast analytical procedure to perform arsenic determination using functionalized gold nanoparticles (AuNPs) and VIS spectrometry as a detection technique is studied. Three different synthesis procedures to obtain the AuNPs and two different functionalization modes were studied. AuNPs functionalized with GSH-DTT-CYs-PDCA were selected as the most adequate. The correlation between the decrease in the absorbance signal and the arsenic concentration was good in the 2–20µgl−1interval. Repeatability, expressed as average of RSD (%), obtained for the different arsenic concentrations studied was 0.6%. The average value of the analytical recovery was 99.7%. The detection and quantifications limits were 2.5 and 8.4µgl−1 respectively. These limits are sufficient to detect World Health Organization’s guideline value of 10µgl−1. [ABSTRACT FROM AUTHOR]

In this study, ethylene vinyl acetate-fly ash (EVA-FA) composites were prepared by the melt mixing technique using a rheomixer for the purpose of removing 2,4,6-trichlorophenol (TCP) and p-nitrophenol (PNP) from water. The fly ash was characterized by X-ray fluorescence spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD); the composites were characterized using SEM and XRD. Brunauer, Emmett, and Teller (BET) measurements revealed a surface area ( SBET) of 0.07110 m2/g for the fly ash. The adsorption of TCP and PNP were monitored by UV-Vis spectrophotometer. The maximum adsorption of PNP was obtained at pH 5 after a contact period of 12 h, whereas that of the TCP was obtained at pH 4 after a period of 10 h has elapsed. The equilibrium adsorption data were evaluated using Langmuir and Freundlich adsorption isotherm models. The Langmuir adsorption model gave the better correlation coefficients for the equilibrium adsorption data. The kinetics data followed the pseudo-second-order model for both TCP and PNP. The theoretical maximum adsorption capacity ( qmax) of the adsorbent used in the study was found to be 3.424 mg/g and 2.544 mg/g for TCP and PNP, respectively. The desorption of the phenols from the composites was performed using 0.2 M NaOH. About 82.6% and 76.3% of TCP and PNP were recovered, respectively. The study showed that the pH of the solution and contact time play a significant role in the adsorption process. Furthermore, we have demonstrated that EVA-FA composites have the potential to adsorb phenols from acidic water solutions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Abstract: The stability constants and coordination modes of the copper(II) heteroligand complexes Cu2+–L1–L2 formed by ethylenediamine (en), diethylenetriamine (dien), N,N,N′,N″,N″-pentamethyldiethylene triamine (Me5dien) (=ligand L1) and DL-2-amino-3-phosphonopropionic acid (β-Asp(P)=ligand L2) have been determined in an aqueous solution (25.00°C and I =0.2moldm−3 KCl) by pH-metric, spectrophotometric and EPR methods. Heteroligand complexes with [Cu(L1)(β-Asp(P))]− stoichiometry are formed in all studied Cu2+–L1–L2 ternary systems. Additionally, in the system with en and dien the protonated [Cu(L1)(H–β-Asp(P))] species is postulated. The results indicate the tridentate coordination mode of β-Asp(P) and the tetragonal geometry for the [Cu(en)(β-Asp(P))]− species. If ligand L1 is dien or Me5dien, five-coordinated heteroligand copper(II) complexes are supported. For the [Cu(dien)(β-Asp(P))]− complex the geometry slightly deviated from square pyramidal is postulated, whereas for the [Cu(Me5dien)(β-Asp(P))]− species somewhat stronger geometry distortion is observed. In both complexes of tridentate amines, β-Asp(P) reveals similar coordination ability as α-Ala and coordinates to the copper(II) ion in the amino acid manner with the formation of five-membered chelate ring. [Copyright &y& Elsevier]

Solution equilibrium studies on Cu-L-L ternary systems have been performed by pH-potentiometry, UV-Vis spectrophotometry and EPR methods {where L corresponds to a polyamine such as ethylenediamine (en), diethylenetriamine (dien), N, N, N′, N′, N″-pentamethyldiethylenetriamine (Medien)} and L denotes 2-aminoethylphosphonic acid (β-alaninephosphonic acid)}. The results suggest the formation of heteroligand complexes with [Cu(L)(β-Ala(P))] stoichiometry in all of the studied systems. Additionally, in the system with en, [Cu(en)(β-Ala(P))H] is formed in basic solutions. Our spectroscopic results indicate tetragonal geometry for the [Cu(en)(β-Ala(P))] species, a geometry slightly deviated from square pyramidal for the [Cu(dien)(β-Ala(P))] complex, and somewhat stronger geometry distortion was present for the [Cu(Medien)(β-Ala(P))] complex. The coordination modes in these heteroligand complexes are discussed. [ABSTRACT FROM AUTHOR]

Microspectrometry in the visible range is routinely applied in comparative examination of criminalistic traces such as paint chips, single fibers, and inks on questioned documents. It makes it possible to analyze a very small amount of sample and provides objective information about its color as well as helping to distinguish samples of similar colors. Measurements of Vis spectra are performed both in transmittance and reflectance mode, depending on the kind of traces. Application of the CIELab color system enables us to define color precisely and make use of color databases. [ABSTRACT FROM AUTHOR]

Solution equilibrium studies on Cu-L-L ternary systems have been performed by pH-potentiometry, UV-Vis spectrophotometry and EPR methods (L corresponds to polyamines such as ethylenediamine (en), diethylenetriamine (dien), or N, N, N′, N′, N″-pentamethyldiethylenetriamine (Medien) and L represents 1-aminoethylphosphonic acid ( α-alaninephosphonic acid)). The obtained results suggest the formation of heteroligand complexes with [Cu(L)( α-Ala(P))] stoichiometry in all studied systems. Additionally, in the system with en the [Cu(en)( α-Ala(P))H] species is formed in basic solution. Our spectroscopic results indicate tetragonal geometry for the [Cu(en)( α-Ala(P))] species, geometry slightly deviated from square pyramidal for the [Cu(dien)( α-Ala(P))] complex and strongly deviated from square pyramidal towards trigonal bipyramidal for the [Cu(Medien)( α-Ala(P))] species. The coordination modes in these heteroligand complexes are discussed. [ABSTRACT FROM AUTHOR]

The purpose of this research was to investigate the efficiency of the sorption of copper (II) ions on biopolymeric materials. Blends between poly (vinyl alcohol) [PVA] (DH=98%, DP=900) as a synthetic polymer and scleroglucan (Sclg) as a natural biopolymer have been prepared by repeated freezing-thawing cycles. The sorption capacity of the cryogel against Cu2+ ions has been determined by VIS Spectroscopy. The alteration of the PVA cryogel properties by Sclg addition and by Cu2+ ions sorption has been investigated by FTIR Spectroscopy. The highest efficiency in Cu2+ ions sorption has been obtained for cryogels containing scleroglucan (Sclg) and poly(vinyl alcohol) (PVA) in 1:9 weight ratio by comparing to pure PVA cryogels. [ABSTRACT FROM AUTHOR]

Solution equilibrium studies on the Cu(II)-polyamine-(aminomethyl)phosphonic acid (glycinephosphonic acid) ternary systems (polyamine: ethylenediamine (en), diethylenetriamine (dien), N, N, N′, N′, N″-pentamethyldiethylenetriamine (Me5dien)) have been performed by pH-potentiometry, UV–vis spectrophotometry and EPR methods. The obtained results suggest the formation of the heteroligand complexes with [Cu(A)(Gly(P))] stoichiometry in all studied systems. Additionally, in the systems with dien the protonated [Cu(dien)(H–Gly(P))]+ species also exists in acid solution and in the system with en the [Cu(en)(Gly(P))H-1]− species is formed in the basic solution. Our spectroscopic results indicate the tetragonal geometry for the [Cu(en)(Gly(P))] species, the geometry slightly deviated from square pyramidal for the [Cu(dien)(Gly(P))] complex and strongly deviated from square pyramidal towards trigonal bipyramidal for the [Cu(Me5dien)(Gly(P))] species. The coordination modes in these heteroligand complexes are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Solution equilibrium studies on the Cu(II)–polyamine–methionine ternary systems (polyamine: ethylenediamine (en), diethylenetriamine (dien), N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (Me5dien)) have been performed by pH-potentiometry, UV–Vis spectrophotometry and EPR methods. The obtained results suggest the formation of the mixed-ligand complexes with [Cu(A)(Met)]+ stoichiometry in all studied systems. Our spectroscopic results indicate the tetragonal geometry for [Cu(en)(Met)]+, the geometry slightly deviated from square pyramidal for [Cu(dien)(Met)]+ and strongly deviated from square pyramidal towards trigonal bipyramidal for the [Cu(Me5dien)(Met)]+ species. The coordination modes in these mixed-ligand complexes are discussed. [Copyright &y& Elsevier]

Abstract: Solution equilibrium studies on the Cu(II)–polyamine–histidine ternary systems (polyamine: ethylenediamine (en), diethylenetriamine (dien), N,N,N′,N″,N″-pentamethyldiethylenetriamine (Me5dien)) have been performed by pH-potentiometry, UV–Vis spectrophotometry and EPR methods. The obtained results suggest the formation of the mixed-ligand complexes with [Cu(A)(His)]+ stoichiometry in all studied systems. Additionally, in the systems with dien and Me5dien protonated [Cu(A)(H–His)]2+ species also exists in acid solution. Our spectroscopic results indicate the tetragonal geometry for the [Cu(en)(His)]+, the geometry slightly deviated from square pyramidal for the [Cu(dien)(His)]+ and strongly deviated from square pyramidal towards trigonal bipyramidal for the [Cu(Me5dien)(His)]+ species. The coordination modes in these mixed-ligand complexes are discussed. [Copyright &y& Elsevier]

In peach fruit (Prunus persica L. Batsch), establishing the optimal harvest time is a crucial issue, since fruit shelf-life potential and quality are closely related to the ripening stage at harvest. In order to develop a non-destructive index for monitoring the progression of ripening, the difference in absorbance between two wavelengths near the chlorophyll-a absorption peak (670 and 720nm; index of absorbance difference, I AD) was related to the time course of ethylene production during on-tree ripening of peaches (cv. ‘Fayette’) and nectarines (cvs. ‘Laura’ and ‘Stark Red Gold’). For each variety, consecutive stages of ripening, as defined according to ethylene production (pre-climacteric, climacteric, post-climacteric), occurred in the same ranges of I AD in different years (2003 and 2004). In 2005, the relationship I AD/ethylene production was used to classify fruit at harvest according to their ripening stage (class 0: pre-climacteric; class 1: onset of climacteric; class 2: climacteric). For each cultivar, the transition from class 1 to 2 was marked by increased ethylene production, and reduced flesh firmness (FF) and titratable acidity (TA). In contrast, fruit quality traits did not discriminate between fruit belonging to classes 0 and 1. In ‘Stark Red Gold’ nectarines, the robustness of the I AD was further corroborated by changes in transcript levels of genes which are either up- or down-regulated during peach fruit ripening. Class 0 fruit had the lowest transcript amount of the up-regulated genes and the highest of the down-regulated ones, while the opposite occurred in class 2 fruit. Moreover, mRNA abundance of some marker genes discriminated class 0 and 1 fruit. Peaches and nectarines graded at harvest according to the I AD also differed in their postharvest ripening behaviour: fruit with higher I AD produced lower amounts of ethylene, began to soften later, and maintained higher TA than those with lower I AD. Present data demonstrate that the I AD identifies physiological changes occurring during ripening regardless of the fact that they might have or not led to appreciable modifications in fruit quality. Therefore, the I AD can be regarded as a very promising tool both for practical and scientific applications, since it allows to monitor on-tree fruit ripening, to establish accurately the optimal harvest time, and to reduce the variability which is present in fruit batches. [Copyright &y& Elsevier]

Abstract: The stability constants and coordination modes of the mixed-ligand complexes formed by copper(II) ion and ethylenediamine as a primary ligand and methioninehydroxamic acid (Metha) or histidinehydroxamic acid (Hisha) as a secondary ligand L were determined by potentiometric titration, UV–Vis and EPR spectroscopy. The obtained results suggest the formation of mixed-ligand species in basic solution with 4N coordination – both amine and hydroxamic nitrogens of Metha or Hisha (NH2, Nha) and two amine nitrogens of en (2×NH2) in the equatorial plane. [Copyright &y& Elsevier]

Interaction of cationic dyes, thionine (Th) and methylene blue (MB), with smectites in the aqueous dispersions was investigated using visible spectroscopy. Smectite samples of various layer charge were used: low-charge laponite (Lap), middle-charge Kunipia F montmorillonite (Kun) and high-charge fluorohectorite (FH). Dyes cations formed monomers, dimers and larger-size aggregates of H-type (sandwich type) and in a few cases of J-type (head-to-tail association). Each form of the dye was identified using visible (VIS) spectroscopy. The effects of layer charge, the type of the dye and smectite, and the influence of dye/clay ratio on the formation of specific dye species were compared. Negligible influence of the dye loading was observed for most cases, being always much lower than the effect of the layer charge density. Dye/Lap reaction systems were dominated by isolated dye cations. H-dimers and larger-size molecular aggregates were formed on the surface of this clay only at the highest loading tested (0.50 mmol/g). On the other hand, the reaction systems with a middle-charge Kun montmorillonite contained roughly equal amounts of dye monomers and H-aggregates at low loadings and slightly more H-aggregates were formed at high loadings. The spectra of dye/FH reaction systems were always dominated by the bands assigned to H-aggregates. The surface of high-charge densities induced destabilization and decomposition of Th cations especially at high dye concentrations on clay surface. The effects of silicate structure and composition on the optical properties of adsorbed dyes were not identified. [Copyright &y& Elsevier]

Photoisomerization reactions of cationic azobenzene dyes in solutions, dispersions, and films of layered silicates were studied by visible (Vis) spectroscopy. The dyes isomerized reversibly from thermodynamically more stable trans-isomers to cis-isomers when irradiated with ultraviolet (UV) light. Observed trends were compared with the optical changes of the dyes that occurred as a consequence of their adsorption at the silicate surface. Small fractions of the dyes are likely to have isomerized during the adsorption process, even without the UV-light irradiation. The aggregation of the dyes was another reaction taking place at the surface of the silicates. The extent of the UV-light-induced isomerization reactions was reduced for the adsorbed dye cations. The reaction proceeded readily for a dye with monovalent cations. However, the photoisomerization was practically negligible in both dispersions and films of layered silicates for a dye with bivalent cations, whereas the isomerization proceeded in solution. This phenomenon was interpreted in terms of the attractive electrostatic forces between the substrate and the dye cations, which hindered the isomerization reaction. The layer charge of silicates affected the orientation of the dye cations as observed by X-ray diffraction (XRD) measurements. However, the choice of silicate did not significantly affect the fundamental aspects and the described basic trends of the UV-light-induced isomerization reaction. [Copyright &y& Elsevier]

The optical properties of reaction systems composed from a pseudoisocyanine (PIC) solution and dispersed layered silicates were studied using visible spectroscopy. Two series of reduced-charge montmorillonites were used as the silicate materials. Each series consisted of eight samples with different layer charges, which were prepared from one parent material. Observed trends were verified with another series of dioctahedral and trioctahedral smectites of different layer charges, structure, and origin. The layer charge density of the silicates significantly affected the aggregation of PIC cations. In addition to the formation of J-aggregates, dye spectral bleaching was also observed. Silicates with very low charge densities induced neither significant aggregation nor spectral bleaching of the dye. The highest levels of PIC J-aggregate formation were found in dispersions of the layered silicates with a medium surface charge. However, reversible spectral bleaching was also observed in some cases. PIC dye cations probably change their conformations during the adsorption process, due to the tension resulting from the large size of the cations and the relatively high charge density at the silicate surface. The bleached dye recovers, at least partially, with the rearrangement and redistribution of the dye cations over the time. In contrast, the presence of silicates with very high charge densities (synthetic taeniolite and fluorohectorite) led to the very fast and irreversible decomposition of the PIC. Perhaps, the tension in adsorbed dye cations, induced by the high charge density at the silicate surface, resulted in significant destabilization and a decomposition reaction of the chromophore. [Copyright &y& Elsevier]

In this paper two methods of preparation of yttrium orthovanadate nanopowders were presented: Solid State Reaction (top – down approach) and Solution Combustion Synthesis (bottom – up approach). For starting structural characterization, X – Ray Powder Diffraction (XPRD) and Field Emission Scanning Electron Microscopy (FESEM) were used. We report the change in reflection spectra in europium doped YVO 4 nanopowders with comparison to its bulk analog. In UV–Vis reflection spectra we consider the change in values of band gap in these structures, after resizing it from bulk to nanomaterial. In Far – Infrared (FIR) reflection spectra, we registered the existence of Surface Optical Phonon (SOP) and different multi – phonon processes which alter the reflection spectra of bulk YVO 4. The influence of Eu ions is reflected through multi – phonon processes that occur and are connected with energy transfer from YVO 4 lattice to Eu ions. All IR spectra were modeled using classical oscillator model with Drude part added which takes into account the free carrier contribution. Since our samples are distinctively inhomogeneous materials, we use Effective Medium theory in Maxwell Garnett approximation to model its effective dieletric function. [Display omitted] • Eu3+ doped YVO 4 prepared by two methods: SCS and SSR. • We report the change in reflection spectra in europium doped YVO 4 nanopowders. • We register the existence of Surface Optical Phonon (SOP) and multi – phonon processes. • SOP mode plays a role of longitudinal optical (LO) phonon. • SOP frequency has a linear dependence on filling factor. [ABSTRACT FROM AUTHOR]

The addition of different ionenes, polycations with defined structure and charge distances, to methylorange 1 in very dilute solutions of water resulted in an observable shift of the absorption maxima from 464 nm to shorter wavelengths. The extent of this so-called metachromasy effect was found to be dependent on the nature of the hydrophobic unit of the polymer backbone. The comparison of UV/VIS spectra's of these solutions with the absorption of a film of a model substance - a dication with methylorange as counteranion - lead to the conclusion that ionenes undergo an exchange of the counteranions when added to a dilute solution of methylorange. Precipitation is slowed down, but the absorption is equivalent with solid product. The new absorption spectra of methylorange can be explained by the interaction of the quaternary nitrogen with the dye anion. [ABSTRACT FROM AUTHOR]