bluuebunny/crossref_metadata_2025_split huggingface dataset:
TiO2 Nanoparticle–Photopolymer Composites for Volume Holographic Recording
Authors: Sánchez C. , Escuti M. J. , van Heesch C. , Bastiaansen C. W. M. , Broer D. J. , Loos J. , Nussbaumer R. 
Published: September 2005

AbstractA new and efficient photopolymer for the recording of volume holograms is presented. The material comprises a mixture of UV‐sensitive acrylates and grafted titanium dioxide nanoparticles with an average size of 4 nm. We report the formation of holographic gratings with refractive‐index modulation amplitudes of up to 15.5 × 10–3—an improvement of more than a factor of four over the base material without nanoparticles—while maintaining a low level of scattering and a high transparency in the visible‐wavelength range. The influence of the composition of the acrylate system on the final properties of the holographic material is also investigated and discussed. The presence of multifunctional monomers favors the compositional segregation of the different components, while the addition of monofunctional acrylate, highly compatible with the grafting of the nanoparticles, favors the dilution of these nanoparticles.
Bonding Polyether onto ZnO Nanoparticles: An Effective Method for Preparing Polymer Nanocomposites with Tunable Luminescence and Stable Conductivity
Authors: Xiong H.‐M. , Wang Z.‐D. , Liu D.‐P. , Chen J.‐S. , Wang Y.‐G. , Xia Y.‐Y. 
Published: September 2005

AbstractA series of new polymer nanocomposites, ZnO(PEGME), in which ZnO nanoparticles and poly(ethylene glycol methyl ether) (PEGME) molecules are connected by covalent bonds, have been synthesized by a sol–gel route and purified by a non‐solvent method. Various characterization techniques have been employed to determine the compositions and structures of the ZnO(PEGME)s, and their luminescent properties and ionic conductivities (after dissolving lithium salts to form solid polymer electrolytes) have been measured and compared with their counterparts—polymer nanocomposites prepared by mixing PEGME and ZnO nanoparticles physically. These comparisons prove that ZnO(PEGME) hybrids derived from chemical reactions have much better properties and stabilities than their counterparts. As a result, tunable photoluminescence of ZnO nanoparticles and stable conductivity of solid polymer electrolytes have been realized successfully.
2,7‐Carbazolenevinylene‐Based Oligomer Thin‐Film Transistors: High Mobility Through Structural Ordering
Authors: Drolet N. , Morin J.‐F. , Leclerc N. , Wakim S. , Tao Y. , Leclerc M. 
Published: September 2005

AbstractWe have fabricated organic field‐effect transistors based on thin films of 2,7‐carbazole oligomeric semiconductors 1,4‐bis(vinylene‐(N‐hexyl‐2‐carbazole))phenylene (CPC), 1,4‐bis(vinylene‐(N′‐methyl‐7′‐hexyl‐2′‐carbazole))benzene (RCPCR), N‐hexyl‐2,7‐bis(vinylene‐(N‐hexyl‐2‐carbazole))carbazole (CCC), and N‐methyl‐2,7‐bis(vinylene‐(7‐hexyl‐N‐methyl‐2‐carbazole))carbazole (RCCCR). The organic semiconductors are deposited by thermal evaporation on bare and chemically modified silicon dioxide surfaces (SiO2/Si) held at different temperatures varying from 25 to 200 °C during deposition. The resulting thin films have been characterized using UV‐vis and Fourier‐transform infrared spectroscopies, scanning electron microscopy, and X‐ray diffraction, and the observed top‐contact transistor performances have been correlated with thin‐film properties. We found that these new π‐conjugated oligomers can form highly ordered structures and reach high hole mobilities. Devices using CPC as the active semiconductor have exhibited mobilities as high as 0.3 cm2 V–1 s–1 with on/off current ratios of up to 107. These features make CPC and 2,7‐carbazolenevinylene‐based oligomers attractive candidates for device applications.
Evaluation by Chemical Parameters of the Pollution State of the Agricultural‐Industrial Settlement of the Fucino Plain
Authors: Ruggieri Fabrizio , Fanelli Maria , di Pasquale Dorina , Burri Ezio , Petitta Marco , Mazzeo Pietro 
Published: September 2005

AbstractIn the present work are reported the results of a monitoring on a vast scale, carried out through evaluation of opportune chemical parameters, of the pollution state of the agricultural‐industrial settlement of the Fucino Plain. The parameters took into consideration have been the presence of wide consumption pesticides and of ionic species as Cl−, NO2−, NO3−, NH4+, the quantification of the dissolved oxygen, of the temperature, of the conductivity, of pH and eH. Collected data are used for chemometric elaboration. The water systems examined, by means of drawing campaigns carried out at regular intervals in winter, spring, summer, and autumnal seasons, are represented by superficial waters constituting a network of irrigation canals fed by stratum and meteoric waters. In this work are reported the results relative to the drawing campaigns.
Evaluation of Chlorinated By‐Products in Drinking Waters of Clentral Friuli (Italy)
Authors: Goi Daniele , Tubaro Franco , Barbone Fabio , Dolcetti Giuliano , Bontempell Gino 
Published: September 2005

AbstractDrinkable water supplied by aqueducts undergoes preliminar potabilization which, in Italy, is mainly accomplished by chlorine addition. The bactericidal action involved in this process is always accompanied by chlorination and oxidation of organic species (mainly humic and fulvic acids) naturally present in treated waters, so that many disinfection by‐products (DBPs) are formed, such as trihalomethanes (THMs) and halo‐acetic acids (HAA), which can represent a chemical risk for public health. The aim of this study was the monitoring of DBPs in drinking water disinfected by chlorination, supplied by four different aqueducts of Central Friuli (Italy). DBP evaluations were performed in water samples consisting of both input and output of disinfection plants. The results of analytical determinations were worked out to provide the THM and HAA parameters for disinfected waters, while in feeding waters the following different conventional parameters were adopted : (i) trihalomethanes formation potential (THMFP), (ii) halo‐acetic acids formation potential (HAAFP) and (iii) UV absorbance at 254 nm (UV254). The quite moderate content of chlorinated products found in all samples considered highlighted the excellent quality of potabilized waters available in Central Friuli. Moreover, our results confirmed that the majority of DBPs formed when chlorine is used for water disinfection consists of THMs, while chlorites and chlorates prevailed when potabilization is accomplished by using chlorine dioxide. Finally, simple UV254 monitoring turned out to be a profitable approach for the determination of chlorinated by‐products only when THMs prevail among DBPs.
Determination of Polycyclic Aromatic Hydrocarbons (PAHs) and Total Fats in Human Milk
Authors: del Bubba Massimo , Zanieri Laura , Galvan Paola , Donzelli Gian Paolo , Checchini Leonardo , Lepri Luciano 
Published: September 2005

AbstractA sensitive and reliable analytical method was developed for the simultaneous extraction of PAHs and total fats and their determination in the human milk. The method involved a liquid‐liquid extraction of PAHs and fats, followed by the gravimetric determination of the latter. PAHs were separated from lipids by size exclusion chromatography eluting with methylene chloride and analysed by gaschromatography coupled with mass spectrometry (GC/MS). The recovery of analytes was in the range of 42‐101 % and agreed well with their boiling temperatures (R2 = 0.779). Precision of the method was found between 7.6 and 19 %. Quantification and detection limits for individual PAHs ranged from 0.011 to 0.032 and from 0.006 to 0.022 μg/Kg milk (wet weight), respectively. Quantification limit for the total fat determination was 0.26 g/Kg milk (wet weight). This procedure, applied to milk samples of ten healthy, non‐smoking, Italian primiparae, living in rural or low‐traffic zones, allowed for the identification and quantitative determination of naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, benzo(b)fluoranthene and benzo(k)fluoranthene in the mean concentration range 0.114 ‐ 6.95 μg/Kg milk (wet weight). The most volatile compounds, which were not investigated elsewhere, were found at much higher concentrations than those observed for the others. No relation was found between PAH and total fat concentrations.
The Protonation of Polyacrylate in Seawater. Analysis of Concentration Effects
Authors: Battaglia Gianluca , Crea Francesco , Crea Pasquale , Sammartano Silvio 
Published: September 2005

AbstractThe protonation of polyacrylate (PAA, MW 2 kDa) was studied potentiometrically at 25 °C, in mixed electrolyte aqueous solution simulating the composition of seawater, in the salinity range 30 ≤ S ≤ 40. The salt composition of different solutions was varied in order to study its effect on apparent protonation constants. Results were analysed using two fairly different approaches: by simple regression analysis on a combination of concentration parameters and salinity, and by canonical correlation analysis. Unexpectedly we found that variations on protonation constants, due to the different relative component concentrations, are fairly low, revealing a sort of buffering capacity of seawater respect to protonation properties of polyacrylate (and likely for other HMW and LMW polycarboxylates). The intrinsic protonation constant of polyacrylate 2 kDa at 25 °C and 35 salinity is ${\rm log} \bar K^{\rm H^\ast} = {\rm log} K_{\rm int} = 4.399 \pm 0.004$. The use of different pH scales and standard seawater compositions is also discussed.
Use of Multivariate Analysis of MIR Spectra to Study Bread Staling
Authors: Cocch Marina , Foca Giorgia , Marchetti Andrea , Sighinolfi Simona , Tassi Lorenzo , Ulrici Alessandro 
Published: September 2005

AbstractDifferent kinds of bread, stored at constant temperature and at controlled humidity conditions for a week since their manufacturing date, were analysed by Attenuated Total Reflectance‐Fourier Transform InfraRed (ATR‐FTIR) spectroscopy. The collected spectra were processed by Principal Component Analysis (PCA), in order to evaluate the changes occurring during bread ageing. For the sake of comparison, the 1060‐950 cm−1‐1 spectral window has been also investigated by curve‐fitting methods. It was observed that the first PC increases monotonically with ageing of samples. Furthermore, the more influential variables on PC1 correspond to spectral regions where are located stretching and bending bands, which are mainly attributed to typical starch bonds vibrations.
Distribution of Heavy Metal Concentrations in Surface Sediments in Dubai Creeks, United Arab Emirates
Authors: Howari Fares M. 
Published: September 2005

AbstractDubai is developing rapidly and many developmental activities are concentrated around its Creek. The present study reports the lateral distribution of heavy metals and compares it with local historical record of heavy metal concentrations. For this purpose surface sediment samples were collected and analyzed for metal contents, total organic carbon content (TOC), mineralogy and grain size. The percentages of the different grain size fraction of the collected sediments were as follow 65 % for sand size, 15 % for silt size fraction, and the rest accounted for clay size fraction. The microscopic analyses indicate that the sediment composed mainly from carbonate and quartz with traces of rock fragments. Such mineral composition is not believed to be a potential source of heavy metal. The study found that the average recorded heavy metal concentrations in the collected sediment samples were 87, 96, 127, 38.5, and 279 ppm for Cr, Cu, Ni, Pb, and Zn, respectively. Those values were slightly higher than metal concentrations recoded in 2001 with 1.22 (Cr), 2.5 (Cu), 2.87 (Ni), 0.69 (Pb), and 2.1 (Zn) folds. However, in 2001 and 2003 the measured metal contents, along the creek, were lower than those of the average earth crust. Along the Creek most metals recorded the highest concentrations in the upper reach of the Creek. The distribution of the measured heavy metals was not affected significantly with the TOC values. The present study also documented obvious related point sources of pollution.
Synthesis and Efficiency of a Chelating Fiber for Preconcentration and Separation of Trace Au(III) and Pd(IV) from Solution Samples
Authors: Lian Ning , Chang Xijun , Zheng Hong , Wang Sui , Dong Yuming , Lai Shoujun 
Published: September 2005

AbstractA novel poly(acryl‐benzoylamidrazone‐acryl‐benzoylhydrazine) chelating fiber was synthesized simply from nitrilon (polyacrylonitrile fiber). The structure of the chelating fiber was verified with the help of FT‐IR spectrum. The parameters influencing the efficiency of the fiber for concentrating trace amounts of Au(III) and Pd(IV) were investigated in detail. Trace Au(III) and Pd(IV) were enriched and separated from real sample solutions and detected using inductively coupled plasma atomic emission spectrometry (ICP‐AES) with satisfactory results. The experiments show that the method is rapid, precise, simple and convenient to use.
Electrochemical determination of 6‐Mercaptopurine at silver microdisk electrodes
Authors: Li Mao‐guo , Wang Yin‐ling , Wang Guang‐feng , Fang Bin 
Published: September 2005

AbstractThe electrochemical behaviour of 6–mercaptopurine (6–MP) at a microdisk electrode is investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that 6–MP can be strongly adsorbed on the surface of the static mercury drop electrode (SMDE) and reacts with Ag+ ions which are produced at positive potentials. 6–MP yields a well–defined cathodic stripping signal during the negative scan at about −0.812 V (vs. SCE) in pH 9.0 phosphate buffer solution. The electrode has hence been used for the determination of 6–MP by differential pulse voltammetry (DPV). The linear range is between 2.0 × 10−7 and 5.0 × 10−5 mol/l, with the calculated detection limit (S/N=3) of 8.0 × 10−8 mol/l. The relative standard deviation is 3.0 % for eight successive determinations of 4.0 × 10−5 mol/l 6–MP. The determination of 6–MP in tablets has also been carried out and satisfactory results have been obtained.
Preparation of Poly(Propyleneimine) Dendrimer Immobilized Silica Gel and its Application as Novel Microcolumn Packing for the On‐Line FI Preconcentration and Separation of Platinum
Authors: Liu Peng , Wu Xiongzhi , Pu Qiaosheng , Su Zhixing 
Published: September 2005

AbstractA G4.0 poly(propyleneimine) dendrimer immobilized silica gel (PPID‐SG) was prepared with a divergent approach from γ‐aminopropyl silica gel (APSG) by repeating the reactions: 1) cyanoethylation of ‐NH2 and 2) reduction of –CN. Then it was successfully applied as the microcolumn packing for the on‐line flow‐injection (FI) preconcentration and separation and flame atomic absorption spectrometry (FAAS) determination of Pt. A limit of detection (LOD) of 0.014 μg/mL was obtained when 0.5 μg/mL Pt in chloride acid of PH = 3 was preconcentrated with a sample flow rate of 4.6 mL/min for 60s and the relative standard deviation (RSD) was 2.65 %. Coexisting metal ions with concentration of 5.0 mg/mL and anion ions of 20.0 mg/ml have no interference in the determination of Pt. The proposed method was successfully applied to the determination of Pt in nickel alloy and anode slime samples.
Intrazellulärer Proteinabbau: von einer ungenauen Vorstellung vom Lysosom und Ubiquitin‐Proteasom‐ System bis hin zu menschlichen Krankheiten und zum Wirkstoff‐Targeting (Nobel‐Vortrag)
Authors: Ciechanover Aaron 
Published: September 2005

AbstractZwischen den 50er und 80er Jahren des letzten Jahrhunderts befassten sich Biochemiker und Molekularbiologen in der Hauptsache damit, wie genetische Information der DNA in RNA umgeschrieben und dann in Proteine übersetzt wird – wie diese Proteine abgebaut werden, blieb hingegen eine lange vernachlässigte Frage. Nach der Entdeckung des Lysosoms durch Christian de Duve ging man davon aus, dass zelluläre Proteine in dieser Organelle abgebaut werden. Es gab zwar einige experimentelle Hinweise, dass die intrazelluläre Proteolyse nicht‐lysosomal abläuft, der Mechanismus blieb aber unbekannt. Gelöst wurde das Rätsel mit der Entdeckung des Ubiquitin‐Proteasom‐Systems. Wir wissen heute, dass der Abbau intrazellulärer Proteine an der Regulation zahlreicher zellulärer Prozesse beteiligt ist, darunter Zellzyklus und Zellteilung, Bereitstellung von Transkriptionsfaktoren und zelluläre Qualitätskontrolle. Es überrascht daher nicht, dass Anomalien dieses Systems mit der Pathogenese menschlicher Erkrankungen wie Tumoren und neurodegenerativen Störungen in Verbindung gebracht wurden. Entsprechend intensiviert hat man in der Folge Bemühungen, Wirkstoffe auf Basis dieses Pathogenesemechanismus zu entwickeln.magnified image
Intracellular Protein Degradation: From a Vague Idea, through the Lysosome and the Ubiquitin–Proteasome System, and onto Human Diseases and Drug Targeting (Nobel Lecture)
Authors: Ciechanover Aaron 
Published: September 2005

AbstractBetween the 1950s and 1980s, scientists were focusing mostly on how the genetic code is transcribed to RNA and translated to proteins, but how proteins are degraded has remained a neglected research area. With the discovery of the lysosome by Christian de Duve it was assumed that cellular proteins are degraded within this organelle. Yet, several independent lines of experimental evidence strongly suggested that intracellular proteolysis is largely non‐lysosomal, but the mechanisms involved remained obscure. The discovery of the ubiquitin–proteasome system resolved the enigma. We now recognize that degradation of intracellular proteins is involved in regulation of a broad array of cellular processes, such as the cell cycle and division, regulation of transcription factors, and assurance of the cellular quality control. Not surprisingly, aberrations in the system have been implicated in the pathogenesis of human disease, such as malignancies and neurodegenerative disorders, which led subsequently to an increasing effort to develop mechanism‐based drugs. chemical structure image
Synthesis of Novel Benzoic Acid Derivatives with Benzothiazolyl Subunit and Evaluation as Aldose Reductase Inhibitors
Authors: Rakowitz Dietmar , Hennig Barbara , Nagano Marietta , Steger Stefan , Costantino Luca , Matuszczak Barbara 
Published: September 2005

AbstractSeveral methyl benzothiazolyloxybenzoates, S‐isosters, and the corresponding benzoic acids were synthesized and tested as aldose reductase inhibitors (ARIs). Out of this series, the ester derivative 2a–7 was found to exhibit the highest enzyme‐inhibitoric activity. In order to investigate this unexpected result, further modifications were carried out which allowed us to explain this finding and to open a path to a novel class of ARIs.
Synthesis of Some 2(3H)‐Benzoxazolone Derivatives and their in‐vitro Effects on Human Leukocyte Myeloperoxidase Activity
Authors: Soyer Zeynep , Bas Meral , Pabuccuoglu Aysun , Pabuccuoglu Varol 
Published: September 2005

AbstractMyeloperoxidase (MPO), a heme protein expressed by polymorphonuclear leukocytes, generates potent oxidants which are proposed to contribute to tissue damage during inflammation and certain pathogenesis such as neurodegenerative disorders. In this study, twenty ω‐[2‐oxo‐3H‐benzoxazol‐3‐yl]‐N‐phenylacetamide and propionamide derivatives having substituents of different lipophilic and electronic nature on the N‐phenyl ring were synthesized to evaluate the inhibitory effects on in vitro leukocyte MPO chlorinating activity. The most active compounds in the series were the derivatives bearing 2‐methyl and 4‐nitro substituent on the N‐phenyl ring.
Synthesis and Antiviral Evaluation of Novel 6′(α)‐Methyl‐Branched Carbovir Analogues
Authors: Kim Jin Woo , Hong Joon Hee 
Published: September 2005

AbstractA new stereoselective synthesis of 6′‐branched Carbovir analogues was accomplished in this study. The introduction of a methyl group in the requisite 6′(α)‐position was carried out using an ester enolate alkylation (LHMDS, CH3I). The desired cyclopentenol 7 was synthesized via a Felkin‐Anh‐controlled Grignard addition and ring‐closing metathesis using second‐generation Grubbs' catalyst. The natural bases (adenine, cytosine) were efficiently coupled using a Pd(0) catalyst. When the synthesized compounds were examined for their activity against several viruses such as the HIV‐1, HSV‐1, HSV‐2, and HCMV, the adenine analogue 12 exhibited moderate antiviral activity against the HCMV.
On the Synthesis of Bioisosters of O‐Benzothiazolyloxybenzoic Acids and Evaluation as Aldose Reductase Inhibitors
Authors: Rakowitz Dietmar , Muigg Patric , Schröder Nicole , Matuszczak Barbara 
Published: September 2005

AbstractIn continuation of our attempts to develop novel aldose reductase inhibitors (ARIs), a number of compounds characterized by bioisosteric replacement of pharmacophors were prepared. On the one hand, the acidic function was formally replaced by an oxime or a nitro group and on the other hand the lipophilic substituent was modified. The results of the biological evaluation of these derivatives enabled us to gain insight into structural features critical for the aldose reductase inhibition.
A Sensitive and Simple Method for the Determination of Chondroitin Sulfate A with Crystal Violet by Resonance Rayleigh Scattering Technique
Authors: Li Taishan , Liu Shaopu , Liu Zhongfang , Hu Xiaoli 
Published: September 2005

AbstractResonance Rayleigh scattering (RRS) spectra resulting from interaction between chondroitin sulfate A (CSA) and crystal violet (CV) have been investigated and applied to the determination of CSA. Though the intensity of RRS has proved very weak for CSA and CV, respectively, it can be greatly enhanced when both interact and form a supramolecular complex. A new RRS spectrum appears with a maximum scattering peak at 328 nm. In this paper, the optimum conditions of the interaction, influencing factors, and the relationship between the relative intensity of RRS (ΔI) and the concentration of CSA have been thoroughly investigated. A new method of determination for the trace amount of CSA has been developed, which combines a simple procedure, high sensitivity, and a low detection limit of 4.8 ng/mL. It has been applied with satisfactory results to the determination of CSA in CSA injection samples and synthetic samples.