bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective electrochemically controlled process for perchlorate removal using poly(aniline‐co‐o‐aminophenol)/multiwalled carbon nanotubes
Authors: Zhang Ya , Liu Xuanming , Li Qin
Published: July 2012

The study on perchlorate removal from simulated wastewater was carried out using a conducting copolymer poly(aniline‐co‐o‐aminophenol) (PANOA) polymerized on multiwalled carbon nanotubes (MWNTs)‐modified glassy carbon (GC) electrode. The cyclic voltammograms demonstrated that the PANOA/MWNTs GC electrode in a NaCl solution containing NaClO4 had a good redox activity, reversibility, and stability in a wide range of pHs tested (from pH <1 to 9.0). The ratio of ClO/Cl− in PANOA/MWNTs was up to 80.8%, which was 10.0% in the solution, indicating that PANOA/MWNTs had a relatively high affinity to perchlorate. The result of X‐ray photoelectron spectroscopy revealed a fact that Cl− ions can be strongly adsorbed on MWNTs, which resulted in an improvement in the electrical activity of PANOA and perchlorate removal. Therefore, it is possible to develop a green process for removing perchlorate from wastewater using PANOA/MWNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and characterization of 4‐dodecyloxyphenyl and (4′‐dodecyloxy‐4‐biphenyl)methylene‐substituted bispyrrolylvinylthiophene‐based polysquaraines having good solubility and very low bandgap for light absorption
Authors: Huo Erfu , Yang Daobin , Zhang Zhanyuan , Lu Zhiyun , Sun Huiqin , Xin Xing , Huang Yan , Liu Yu , Jiang Qing
Published: July 2012

In this work, two very low band‐gap (∼1.0 eV) alternate conjugated copolymers bearing bispyrrolylvinylthiophene‐based polysquaraine backbone (PVTVPS) have been synthesized. In comparison with their analogous polymer with 2‐ethylhexyl side chain on the pyrrole segment, which possesses poor solubility after long‐time storage, the two target polymers with 4‐dodecyloxyphenyl (PVTVPS‐Ph) or (4′‐dodecyloxy‐4‐biphenyl)methylene (PVTVPS‐Ph2) side chains exhibit dramatically improved solubility. Furthermore, PVTVPS‐Ph shows unexpected thermochromism in the Vis–near‐infrared (NIR) region of 600–1100 nm at 80–160°C in solution and thin film. This may be attributed to the presence of relatively rigid phenyl substituent restricting the free rotation between the D (pyrrole) and A (squaraine) segments of the main chain. To our knowledge, this is the first report on NIR thermochromic polysquaraines. Nevertheless, in the case of PVTVPS‐Ph2, no thermochromism could be observed because of the existence of free‐rotating methylene linkage bridge between biphenyl unit and the conjugated polymer skeleton. When compared with PVTVPS‐Ph, PVTVPS‐Ph2 has much improved thermostability and broader absorption property. Hence, PVTVPS‐Ph2 is a more prospective candidate as photovoltaic materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Pressure‐activated microsyringe composite scaffold of poly(L‐lactic acid) and carbon nanotubes for bone tissue engineering
Authors: Vozzi Giovanni , Corallo Claudio , Daraio Chiara
Published: July 2012

Tissue engineering is an innovative interdisciplinary field in which bioengineers and life scientists try to regenerate and reproduce natural tissues through the use of biodegradable structures, calledscaffolds, with the aim of mimicking the specific tissue extracellular matrix (ECM). Carbon nanotubes (CNTs) offer a natural platform for obtaining composite microfabricated scaffolds thanks to their excellent mechanical properties and their good biocompatibility. In this study, we microfabricated three‐dimensional (3D) scaffolds by mixing poly(L‐lactic acid) (PLLA) and multiwalled carbon nanotubes (MWCNTs) for bone tissue engineering. We measured their mechanical properties and studied their biocompatibility with human fetal osteoblasts (hFOB 1.19). The 3D microfabricated PLLA/MWCNTs nanocomposite scaffolds showed higher stiffness and cell viability than the pure 3D microfabricated PLLA scaffolds. The results of this preliminary work suggest that biopolymer/CNT microcomposites and nanocomposites could be used as effective building blocks to replace ECMs in bone tissue engineering applications. The final goal is the creation of innovative scaffolds for implants and tissue regeneration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of cross‐linking time on the thermal and mechanical properties and pervaporation performance of poly(vinyl alcohol) membrane cross‐linked with fumaric acid used for dehydration of isopropanol
Authors: Heydari Maryam , Moheb Ahmad , Ghiaci Mehran , Masoomi Mahmood
Published: July 2012

Cross‐linked poly (vinyl alcohol) membranes were prepared using fumaric acid as the cross‐linking agent and were used for the pervaporation separation of water/isopropanol mixtures. Cross‐linking process was carried out at 150°C at three different times of 10, 30, and 60 min. The membranes were characterized by different known methods of FT‐IR, TGA, XRD as well as tensile test. The effects of cross‐linking time on the thermal and mechanical properties of the membranes and also their pervaporation performance were investigated. Formation of more ester groups by increasing the cross‐linking time was confirmed by the FT‐IR results. TGA analyses showed that thermal stability of the membranes is improved by prolonging the duration of cross‐linking process. This was due to the formation of more compact structure in the membranes. The XRD results revealed that the crystalline regions of the membranes were relatively diminished with an increase in the cross‐linking time. No specific trend was observed for the variation of tensile strength at break with the cross‐linking time. The PVA membrane cross‐linked for 60 min showed high selectivity of 1492 for water permeation for the feed mixture containing 10 wt % water. The temperature dependency of the permeation flux was investigated using Arrhenius relationship, and the activation energy values were calculated for total permeation (Ep), water (Epw), and IPA (EpIPA) fluxes. Lower value of Epw in comparison with EpIPA supported excellent dehydration performance of the cross‐linked membranes. Despite large increase in activation energy of water with prolonged cross‐linking time, the selectivity was improved. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2013
Effect of nano‐silica on the mechanical, thermal, and crystalline properties of poly(vinyl alcohol)/nano‐silica films
Authors: Wang Chao , Wei Jingwei , Xia Bingxiang , Chen Xian , He Bobing
Published: July 2012

Poly(vinyl alcohol)/nano‐silica (PVA/nano‐SiO2) films were prepared through extrusion blowing with the addition of water and glycerin as plasticizer. The characteristic properties of PVA/nano‐SiO2films were investigated by differential scanning calorimetry, dynamic mechanical analysis, Haake torque rheometry, and atomic force microscopy (AFM). The results showed that the mechanical properties of PVA/nano‐SiO2were improved dramatically. The tensile strength of the nanofilms increased from 62 MPa to 104 MPa with loading 0.3 wt % nano‐SiO2and the tear strength was improved from 222 KN/m to 580 KN/m. The crystallinity of the films loaded with 0.4 wt. % nano‐SiO2decreased from 32.2% to 21.0% and the AFM images indicated that the amorphous region of nanofilms increased with increasing nano‐SiO2content. The storage modulus and loss modulus increased to two and nearly three times with 0.3 wt % nano‐SiO2loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Structure and morphology of linear polyethylene extrudates induced by elongational flow
Authors: Rybnikar Frantisek , Kaszonyiova Martina , Cermak Roman , Habrova Veronika , Obadal Martin
Published: July 2012

This study focuses on the structure, morphology, and properties of linear polyethylene (PE) profiles manufactured by continuous extrusion. High level of chain orientation was achieved using specific flow and processing conditions. An extrusion die with semihyperbolic convergency was used to generate high percentage of elongational flow and chain extension. Simultaneously, high extrusion pressure and relatively low melt temperature led to flow‐induced crystallization of PE extended chains. The structure of PE tapes consists of crystal aggregates with different level of orientation and crystallinity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation of polyaniline/nylon conducting fabric by layer‐by‐layer assembly method
Authors: He Jinsong , Li Rong , Gu Feng
Published: July 2012

In this article, layer‐by‐layer assembly technology was used to prepare polyaniline (PANI)/nylon conducting fabrics. PANI/nylon conductive composite fabrics were prepared by deposition of polyanion (PSS) and polycation (aniline cation) alternately. The pretreatment with PSS was discussed. The influence of the reaction time, aniline concentration, acid concentration and assembly time on the conductivity, and K/S values of composite fabric was studied. The optical reaction condition of assembly should be: the concentration of PSS was 20 g/L, the PSS‐treated nylon immersion in blended bath for 24 min, ammonium persulfate 0.1 mol/L, aniline 0.1 mol/L, p‐toluene sulfonic acid 0.3 mol/L. In the end, the conductive composite fabrics were characterized by fourier transformed Infrared‐attenuated total reflection spectroscopy and compared with pure nylon fabrics. At the same time, scanning electron microscopy, atomic force microscope (AFM), thermogravimetric analysis (TG), and mechanical properties were studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
The Enamel Microstructures of Bovine Mandibular Incisors
Authors: Wang Chaoyang , Li Yining , Wang Xiaomiao , Zhang Ling , Tiantang  , Fu Baiping
Published: July 2012

Bovine teeth have been considered as an excellent substitute for human teeth for dental research, however, the enamel microstructures of bovine incisors that include arrangements of prisms and interprisms, and their spatial relationships have not been well described. The aim of this study was to investigate the detail enamel microstructures of bovine incisors. Eight bovine mandibular incisors were cut into 77 pieces at eight equal intervals either in the longitudinal direction or in the horizontal direction before each piece had been tangentially cut (parallel to enamel–dentin junction) through the middle of the enamel thickness. All the sectioned surfaces were treated 1 M HCl for 10 sec to expose the prisms and interprisms before observation by scanning electron microscopy. The parallel enamel prisms were located in all the outer enamel, the cervical region and the incisal ridge of the bovine incisors. Most labial inner enamel and the cingulum of lingual inner enamel were composed of the Hunter–Schreger bands with the characteristics of decussating groups of prisms and decussating planes between interprisms and prisms. The interprisms were thicker in the inner enamel than in the outer enamel. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.
IDENTIFICATION OF THE WESTERN TARNISHED PLANT BUG (Lygus hesperus) OLFACTORY CO‐RECEPTOR ORCO: EXPRESSION PROFILE AND CONFIRMATION OF ATYPICAL MEMBRANE TOPOLOGY
Authors: Hull J. Joe , Hoffmann Eric J. , Perera Omaththage P. , Snodgrass Gordon L.
Published: July 2012

Lygus hesperus (western tarnished plant bug) is an agronomically important pest species of numerous cropping systems. Similar to other insects, a critical component underlying behaviors is the perception and discrimination of olfactory cues. Consequently, the molecular basis of olfaction in this species is of interest. To begin to address this issue, we utilized homology‐based PCR as a commonly accepted abbreviation but if necessary it is polymerase chain reaction methods to identify the L. hesperus olfactory receptor co‐receptor (Orco) ortholog, a receptor that has been shown to be essential for olfaction. The L. hesperus Orco (LhOrco) shares significant sequence homology with known Orco proteins in other insects. Parallel experiments using the sympatric sister species, Lygus lineolaris (tarnished plant bug), revealed that the Lygus Orco gene was completely conserved. Surprisingly, a majority of the membrane topology prediction algorithms used in the study predicted LhOrco to have both the N and C terminus intracellular. In vitro immunofluorescent microscopy experiments designed to probe the membrane topology of transiently expressed LhOrco, however, refuted those predictions and confirmed that the protein adopts the inverted topology (intracellular N terminus and an extracellular C terminus) characteristic of Orco proteins. RT‐PCR analyses indicated that LhOrco transcripts are predominantly expressed in adult antennae and to a lesser degree in traditionally nonolfactory chemosensory tissues of the proboscis and legs. Expression is not developmentally regulated because transcripts were detected in all nymphal stages as well as eggs. Taken together, the results suggest that LhOrco likely plays a critical role in mediating L. hesperus odorant perception and discrimination.
IDENTIFICATION OF A CALMODULIN‐BINDING SITE WITHIN THE DOMAIN I OF BACILLUS THURINGIENSISCry3Aa TOXIN
Authors: Ochoa‐Campuzano Camila , Sánchez Jorge , García‐Robles Inmaculada , Real M. Dolores , Rausell Carolina , Sánchez Jorge
Published: July 2012

Bacillus thuringiensis Cry3Aa toxin is a coleopteran specific toxin highly active against Colorado Potato Beetle (CPB).We have recently shown thatCry3Aa toxin is proteolytically cleaved by CPBmidgut membrane associated metalloproteases and that this cleavage is inhibited by ADAMmetalloprotease inhibitors. In the present study, we investigated whether the Cry3Aa toxin is a calmodulin (CaM) binding protein, as it is the case of several different ADAMshedding substrates. In pull‐down assays using agarose beads conjugated with CaM, we demonstrated that Cry3Aa toxin specifically binds to CaMin a calcium‐independent manner. Furthermore, we used gel shift assays and 1H NMRspectra to demonstrate that CaMbinds to a 16‐amino acid synthetic peptide corresponding to residues N256‐V271 within the domain I of Cry3Aa toxin. Finally, to investigate whether CaM has any effect on Cry3Aa toxin CPBmidgut membrane associated proteolysis, cleavage assays were performed in the presence of the CaM‐specific inhibitor trifluoperazine. We showed that trifluoperazine significantly increased Cry3Aa toxin proteolysis and also decreased Cry3Aa larval toxicity.
3‐Nitro‐2H‐chromenes as a New Class of Inhibitors against Thioredoxin Reductase and Proliferation of Cancer Cells
Authors: Xiao Guo‐Qiang , Liang Bao‐Xia , Chen Shu‐Han , Ou Tian‐Miao , Bu Xian‐Zhang , Yan Ming
Published: July 2012

A series of 3‐nitrochromenes were designed and synthesized. These compounds showed good inhibitory activity against thioredoxin reductase (TrxR) and the proliferation of A549 cancer cells. The structure–activity relationship analysis indicates that the 3‐nitrochromene scaffold is the crucial pharmacophore for achieving good inhibitory activity. The bromo‐substitutions at the 6‐ and 8‐position of 3‐nitrochromene significantly increase the inhibitory activity.
Stability Analysis of Linear Time‐Invariant Distributed‐Order Systems
Authors: Jiao Zhuang , Chen YangQuan , Zhong Yisheng
Published: July 2012

The bounded‐input bounded‐output stability condition of a linear time invariant (LTI) distributed‐order system over integral interval (0,1) has been established for the first time. Two cases about weighting function of the distributed order are investigated, and sufficient and necessary conditions of stability for these two types of distributed‐order systems are derived. Based on the complex integration analysis, time‐domain responses of distributed‐order systems are also given by analytical method, and numerical examples are presented to illustrate the proposed conditions.
Active Control for a Perturbed Flexible Structure: An Experimental Study
Authors: Pujol Gisela , Acho Leonardo
Published: July 2012

A linear dynamic control is developed for a flexible structure subject to external ground perturbation. This active controller is based on H
∞ frame‐work and designed using linear matrix inequality techniques. According to experiments, our control strategy improves the closed‐loop system performance when it is compared with respect to a given controller.
Microscopic modeling of large‐scale pedestrian–vehicle conflicts in the city of Madinah, Saudi Arabia
Authors: Abdelgawad Hossam , Shalaby Amer , Abdulhai Baher , Gutub Adnan Abdul‐Aziz
Published: July 2012

This paper presents a micro‐simulation modeling framework for evaluating pedestrian–vehicle conflicts in crowded crossing areas. The framework adopts a simulation approach that models vehicles and pedestrians at the microscopic level while satisfying two sets of constraints: (1) flow constraints and (2) non‐collision constraints. Pedestrians move across two‐directional cells as opposed to one‐dimensional lanes as in the case of vehicles; therefore, extra caution is considered when modeling the shared space between vehicles and pedestrians. The framework is used to assess large‐scale pedestrian–vehicle conflicts in a highly congested ring road in the City of Madinah that carries 20 000 vehicles/hour and crossed by 140 000 pedestrians/hour after a major congregational prayer. The quantitative and visual results of the simulation exhibits serious conflicts between pedestrians and vehicles, resulting in considerable delays for pedestrians crossing the road (9 minutes average delay) and slow traffic conditions (average speed <10 km/hour). The model is then used to evaluate the following three mitigating strategies: (1) pedestrian‐only phase; (2) grade separation; and (3) pedestrian mall. A matrix of operational measures of effectiveness for network‐wide performance (e.g., average travel time, average speed) and for pedestrian‐specific performance (e.g., mean speed, mean density, mean delay, mean moving time) is used to assess the effectiveness of the proposed strategies. Copyright © 2012 John Wiley & Sons, Ltd.
Enhanced early expression of membrane receptors with the Rous sarcoma virus promoter in baculovirus‐infected insect cells
Authors: Näreoja Katja , Åkerman Karl E. , Näsman Johnny
Published: July 2012

The effect of the Rous sarcoma virus (RSV) long terminal repeat enhancer/promoter on expression levels of complementary DNAs (cDNAs) encoding seven transmembrane receptors was studied using the baculovirus expression vector system. Expression of the human α2B‐adrenoceptor (AR) cDNA under the control of the polyhedrin (POL) promoter produced up to 7.6 pmol/mg protein at 28 H post infection (p.i.) in Sf9 cells. The addition of the RSV promoter increased the expression to 11.6 pmol/mg protein. Dramatic increases in expression levels at early times were also obtained with the α2A‐AR, the M1 and M4 muscarinic receptors, and the orexin OX1 receptor. Analysis of the time‐dependent expression revealed that expression driven by the RSV promoter reaches almost maximum 24 H p.i. and that this promoter is superior to the often used POL promoter at early times p.i. when functional studies need to be performed. Functional enhancement of signaling as a result of early expression is demonstrated with the α2B‐AR and the OX1 receptor. Finally, enhanced green fluorescent protein fluorescence in living cells was used to monitor expression by various viral promoters. The results verified the early transcriptional activity of the RSV promoter, whereas the cytomegalovirus promoter was found to be poorly active in Sf9 cells.
Kinetics and Energetics of the Reaction ClO ± O2 (1Δg) → ClO3
Authors: Handwerk V. , Zellner R.
Published: July 2012

The rate coefficient for reaction between ClO (2II) and O2 (1Δg) has been measured using a flow/flash photolysis technique. An upper limit of k1 ≤ 3·10−15 cm3/s at 298 K was found. The formation of symmetrical ClO3 (2A1) as a product is spin and orbital symmetry allowed but is probably prevented by an activation barrier and by equilibrium constraints. The rate coefficient for quenching of O2(1Δ) by Cl2 was found to be 2·10−17 cm3/s at 298 K.
A new bath for the electrodeposition of aluminium. IV. The electrochemical behaviour of the rotating aluminium disc electrode in pure LiAlH4/THF‐toluene solutions
Authors: Badawy W. A. , Hilal N.
Published: July 2012

The electrochemical behaviour of the rotating aluminium disc electrode in LiAlH4/tetrahydrofuran (THF)‐toluene solutions was studied. The kinetic parameters controlling the electrode process were investigated. The effect of concentration of LiAlH4, the speed of rotation of the rotating disc electrode, and the temperature on the current density‐potential behaviour of the aluminium electrode during the anodic and cathodic polarization was analyzed. The results were compared with those obtained for pur AlCl3 or AlCl3 + LiAlH4/THF‐toluene solutions.
Interaction of ethylene glycol with alumina supported copper —an FTIR study
Authors: Jobson E. , Baiker A. , Wokaun A.
Published: July 2012

The adsorption of ethylene glycol on γ‐alumina as well as on an alumina‐supported copper catalyst has been studied under working conditions using transient FTIR experiments. Time‐dependent spectra were recorded after exposure of the substrates to a pulse of ethylene glycol, or to subsequent stepwise increases in the ethylene glycol concentration. On alumina both dehydration and dehydrogenation products were observed; on supported copper dehydration was suppressed and only the aldehyde formed by dehydrogenation of the reactant glycol was observed. Hydrogen was found to prevent the formation of dialdehydic species (surface bound glyoxal) which were observed in nitrogen carrier gas. The relevance of these results to the mechanism of the copper‐catalyzed amination of alcohols is discussed.
High temperature dissociation of CN
Authors: Mozzhukhin E. , Burmeister M. , Roth P.
Published: July 2012

The thermal decomposition of CN radicals has been measured behind reflected shock waves in the temperature range 4060 K ≤ T ≤ 6060 K. Very low initial concentrations of C2N2 highly diluted in argon were shock heated and the concentrations of N and C atoms were monitored in the post shock reaction zone by using Atomin Resonance Absorption Spectroscopy (ARAS). From the initial slope of the measured N and C atom concentration profiles, a rate coefficient for the reaction

CN + M → C + N + M of (R2)

k2 = 2.5 · 1014 exp(−71000 K/T cm3 mol−1 s−1

could be directly determined. For the secondary reactions

CN + CN → C2 + C2 (R3)

CN + C → C2 + N (R4)

CN + N → R2 + C (R5)

rate coefficients were obtained from best computer fits of the experimental results. The inferred values of these rate coefficients are given in this paper.
The reaction of CH2(X̄3B1) with C6H6
Authors: Böhland T. , Héberger K. , Temps F. , Gg. Wagner H.
Published: July 2012

The kinetics of the reaction CH2(X̄3B1) + C6H6 → products (1) has been studied in a discharge flow reactor using Laser Magnetic Resonance (LMR) detection for CH2. The experiments yielded the overall rate constant kexp1 = (4.7 ± 2.4) · 10t3 exp(−(37.5 ± 2.4) kJ mol−1/RT) in the temperature range 448 K ≦T ≦ 683 K. The product formation was investigated for reaction (1) as well as the corresponding reaction CH2(ã1A1) + C6H6 → products (2) in a stationary photolysis reactor employing gas chromatographic analysis by photolyzing mixtures of CH2CO and C6H6 at λ1 = 366 nm and λ2 = 313 nm. The relative yields of the products cycloheptatriene (CHT) and toluene (T) were found to depend on the wavelength, [T]/([CHT] + [T]) = (0.13 ± 0.02) and (0.23 ± 0.02) at λ1, and λ2, respectively. The implications of these results and the mechanisms are discussed.
The local order in liquid dimethylsulfoxide and KI‐dimethylsulfoxide solution determined by X‐ray and neutron diffraction experiments
Authors: Bertagnolli H. , Schultz E. , Chieux P.
Published: July 2012

The intra‐ and intermolecular structure of liquid dimethylsulfoxide (DMSO) was investigated by X‐ray and neutron diffraction. The weighted sums of the atom pair correlation functions were evaluated by Fourier transformation of the total corrected intensities obtained by applying the usual data reduction procedures on the measured intensities. Subsequently the intramolecular structures were determined and the intermolecular contributions were separated from the total intensities. The X‐ray scattering data obtained from a concentrate KI‐DMSO mixture (mole fraction K+ = 0.1231, mole fraction DMSO = 0.7538) were evaluated in the same manner. In case of pure DMSO X‐ray and neutron data were combined to eliminate single atom pair correlation functions in order to assign distances to atom pairs. Additionally structural models of the local order in the liquids were deduced and refined by least square fits of the intermolecular reduced intensities. It turned out that the local order of pure liquid DMSO is similar to the crystal structure. The KI‐DMSO mixture consists of solvent separated ion pairs according to our calculations.
Disordering and heat capacity of sodium hexabromouranate (IV)
Authors: Gambino M. , Gaune P. , Szczepaniak W.
Published: July 2012

Heat capacity measurements of Na2UBr6 have been carried out in the temperature range 473 — 723 K with differential scanning calorimetry (DSC). Na2UBr6 undergoes a λ‐transition in the range 550–683 K which was ascribed to disordering in the cationic sub‐lattice. Enthalpy and entropy of this transition are equal to 8.8 kJ · mol−1 and 13.8 J · mol−1 K−1, respectively. The results were compared with literature data on structure and electrical conductivity.
Nuclear quadrupole coupling in hexachlorometallates A2[MCl6] and A'[MCl6], A⊕, A'2⊕ = several inorganic or organic cations, M = Sn, Pb, Te, Pt
Authors: Borchers Dirk , Weiss Alarich
Published: July 2012

The electric field gradient (EFG) at the chlorine site of the hexachlorometallates A2[MCl6] and A'[MCl6], M = Sn, Te, Pb, Pt, and A⊕, A'2⊕ = alkali metal ion, hexahydrated bivalent metal ion, or organic ammonium cation, is investigated and the dependence of the EFG on the size of the cation is discussed. — For the cubic alkali hexachlorometallates the observed trend in the EFG with increasing size of the cation is corroborated by quantum mechanical calculations using the Multiple‐Scattering‐Xα‐method (MS‐Xα) and the point charge model. A correlation v(35Cl) ∼ 1/r3 is found, where r is the distance between the ions in the lattice and the chlorine nucleus considered. For hexachlorometallates with organic cations, like pyridine, piperazine, 4‐picoline, ethylenediamine, 1.3‐propylenediamine, and other aliphatic or aromatic amines, this 1/r3 dependence is found for the averaged 35Cl NQR frequency, too. This is due to the distortion of the [MCl6]2⊕ octahedra, caused by hydrogen bonds N—H…Cl, and to the decrease of the lattice symmetry because of non‐sphericity of the cations. — A hydrogen bond has a large influence on the properties of one of the chlorine atoms of the hexachlorometallate complex. The M‐Cl distance is increased and therefore the EFG at the nucleus site is decreased. However, the average of the M‐Cl bond lengths or the 35Cl NQR frequencies, taken over all six chlorine atoms of a [MCl6]2⊕ complex, is not influenced by the chemical nature of the cation but only by its size or the size of the unit cell, respectively. The increase of 35Cl NQR frequency with increasing size of the cation originates from a decrease of the lattice energy.
The Equation of State of Dense Liquid Iodine up to 1000°C and 200 MPa
Authors: Erdmann R. , Schmutzler R. W.
Published: July 2012

Density measurements of liquid iodine from the melting curve up to 1000°C and 200 MPa are reported. The measurements have been performed in an internally heated autoclave by a dilatometric method. The results indicate, that liquid iodine remains a normal molecular liquid along its liquid‐vapour coexistence curve. The observed strong curvatures of the isochores at high pressures and high temperatures are consistent with the assumption of a formation of strongly localized charged centers resembling a partial dissociation of iodine into solvated ions.
1H NMR Studies on Cationic Dynamics in Solid Methylguanidinium, 1,1‐Dimethylguanidinium, 1,2,3‐Trimethylguanidinium, and 1,1,3,3‐Tetramethylguanidinium Chlorides
Authors: Furukawa Yoshihiro , Kojima Chiaki , Nakamura Daiyu
Published: July 2012

The temperature dependence of 1H NMR second moments and spin‐lattice relaxation times, T1 and T1ϱ in the laboratory and rotating frames, respectively, were observed for solid methylguanidinium (MeguH+), 1,1‐dimethylguanidinium (1,1‐Me2guH+), 1,2,3‐trimethylguanidinium (1,2,3‐Me3guH+), and 1,1,3,3‐tetramethylguanidinium (1,1,3,3‐Me4guH+) chlorides. Phase transitions were found for (1,1‐Me2guH)Cl and (1,2,3‐Me3guH)Cl at 400 and 409 K, respectively, which were confirmed by differential thermal analysis experiments. Below room temperature, rapid C3 reorientational motions of CH3 groups were detected for the all cations in the above crystals. The activation energy for the motion of each CH3 group in the cations was evaluated. Above room temperature, the temperature dependences of T1ϱ were determined against T−1 for (1,1‐Me2guH)Cl, (1,1,3,3‐Me4guH)Cl, and their partially deuterated (NH2 → ND2) analogs. For these salts, 1H T1ρ minima were observed and could be interpreted as arising from the 180° flip motions of the NMe2 group and also of the whole cation for (1,1‐Me2guH)Cl and its deuterated analog about the C+—NMe2 axis of the cations, and the whole cationic 180° flip motion about the C+—NH2 or C+—ND2 bond axis of the cation for (1,1,3,3‐Me4guH)Cl or its deuterated analog, respectively, in addition to the NMe2 180° flip motions.
Alkali Metal Picrate Complexes of “Crowned”‐Phthalocyanines. Solid State Structures and Electrical Properties
Authors: Sielcken O. E. , van Lindert H. C. A. , Drenth W. , Schoonman J. , Schram J. , Nolte R. J. M.
Published: July 2012

Molecules of copper phthalocyanine substituted with four 18‐crown‐6 moieties, were aggregated with the help of K+, Rb+, and Cs+ picrates. Possible structures were proposed based on computer analysis of X‐ray powder diffraction patterns: for the crowned phthalocyanine an orthorhombic cell with: a = 50.77, b = 25, c = 8.7 Å. For its metal picrate complexes, tetragonal structures were found: a = b = 22.76, c = 12.99 Å (K+‐complex); a = b = 29.44, c = 10.63 Å (Cs+‐complex); a = b = 29.44, c = 10.40 Å (Rb+‐complex). A.c. impedance spectroscopy showed an increase in the electronic conductivity of 2 to 3 powers of ten, if crowned phthalocyanine was aggregated by means of a metal picrate salt. In the K+ complex only electronic conductivity could be detected. The Rb+ and Cs+ complexes exhibited cation conductivity as well.
Photo‐Akustische (PA) Phasenwinkelspektroskopie an wäßrigen Farbstofflösungen — Einführung einer semiempirischen Phasenwinkelfunktion
Authors: Holter A. , Perkampus H.‐H.
Published: July 2012

The phase angle functions ϕ(β) are discussed in terms of the composite piston model and of the Poulet‐Chambron‐Unterreiner approximation of the Rosencwaig‐Gersho theory. Specially in the case of the refined CP model the expressions for the real and imaginary part of the appropriate equations are given explicitely. — The comparison of experimental values with functions ϕ(β) calculated in this way shows that the models described in the literature are unable to reproduce the experimental pattern of the function ϕexp(β) for β < ∞. — Therefore, a semiempirical phase angle function was set up, which describes the pattern of the experimental values in every detail. The parameters Pz and Pe introduced are obviously valid for aqueous solutions in general, as the simulation of the phaseangle spectra of different dye solutions shows. — In highly concentrated solutions, e.g. β → ∞, the absorption coefficients can be determined by the reverse function of the phase angle function of the PCU approximation; absorption coefficients at these concentrations are not accessible to direct photometric measurements.
Excess Enthalpies of Alkyl Formates + (n‐Alkanes or 1‐Chloroalkanes). Experimental Data and their Analysis in Terms of the UNIFAC Model
Authors: Ortega Juan
Published: July 2012

hE data, obtained at 298.15 K and atmospheric pressure, are presented for the binary systems alkyl formates (propyl and butyl) with n‐alkanes (n‐heptane, n‐octane and n‐nonane) and with 1‐chloroalkanes (1‐chloropentane, 1‐chlorohexane, 1‐chloroheptane and 1‐chlorooctane). The results for hE indicate interactions of alkyl formates which are stronger with aliphatic hydrocarbons than with alkyl chlorides. Experimental results are examined on the basis of the UNIFAC group‐contribution model. In general, the model represents the available experimental hE data with limits of errors smaller than 8%.
Ellipsometric Study of the Complex Dielectric Function of KxKCl1‐x Approaching the NM‐M Transition
Authors: Nattland D. , Freyland W.
Published: July 2012

We report the first ellipsometric measurements of the optical constants, refractive index n and absorption coefficient k, for a fluid system at high temperatures, i.e. salt rich KxKCl1‐x solutions up to 800°C. The applicability and realization of the ellipsometric technique under these experimental conditions is described in detail. First data of the optical conductivity σ (ω, x) and the real part of the dielectric function ϵ1 (ω, x) are presented. In a qualitative discussion of these results emphasis is given on the NM‐M transition region. The behaviour of σ (ω, x) in the IR‐region indicates the occurrence of metal clustering approaching the NM‐M transition. From the dielectric anomaly of ϵ1 (x) it is concluded that the onset of metallic behaviour is well separated from the consolute composition of the critical point of liquid‐liquid immiscibility.
The Phasediagram of the Semiconductor Alloy ZnkHg(1‐k)SelTe(1‐l)
Authors: Leute Volkmar , Plate Hermann
Published: July 2012

The phase diagram of the quasiternary system ZnkHg(1‐k)SelTe(1‐l) was investigated by X‐ray diffraction and DTA measurements. The phase diagrams of the quasibinary subsystems were recalculated using the interaction parameters determined from the isothermal quasiternary sections. The subsolidus region of the quasiternary system shows an extended miscibility gap inspite of complete solid solutions on the quasibinary edges. The tie line field is fan shaped converging on the ZnSe corner of the phase square. The enthalpies of pair formation in the sublattices are calculated using the model of 4‐particle‐clusters. It is also shown, that the assumption of random distribution for the clusters is a rather good approximation for the calculation of the quasiternary phase diagram.
Absorption Spectra and Fluorescence Behaviour of Benzopyrylium Compounds
Authors: Haucke Günter , Czerney Peter , Igney Constance , Hartmann Horst
Published: July 2012

Absorption and fluorescence data of a wide variety of substituted flavylium salts and their 2‐naphthyl substituted derivatives in two solvents of different polarity are studied with respect to the influence of the flexibility of the chromophoric system both in their ground and excited states. The experimental results are in accordance with the assumption that for typical non‐bridged 2‐aryl substituted benzopyrylium salts electronic transitions occur from a distribution of non‐planar conformations of the ground state conformers to the excited state ones, which in solution tend to relax to a more planar thermically equilibrated geometry, although fluorescence rate constant data indicate that also fluorescence may originate from somewhat twisted conformations. A polar solvent supports the tendency of certain substituted molecules to occur in the excited state in a non‐fluorescent twisted configuration (TICT state). As the consequence, many flexible donor substituted benzopyrylium salts exhibit a strong decrease of their fluorescence quantum yield in polar solvents.
Kinetics of Reactions of Hydroxyl Radicals with a Series of Aliphatic Aldehydes
Authors: Dóbé S. , Khachatryan L. A. , Bérces T.
Published: July 2012

The kinetics of reactions of hydroxyl radical with acetaldehyde and its alkyl and halogen substituted derivatives has been investigated in the temperature range 298 – 520 K with the discharge flow/resonance fluorescence technique. The following reactions were studied and Arrhanius parameters were obtained (the preexponential factors are given in 1012 cm3 mol−1 s−1, the activation energies in kJ mol−1 units):

(1) OH + CF3CHO A = 7 (assumed;) E = 5.9

(2) OH + CCl3CHO A = 7.1 ± 1.5 E = 5.0 ± 0.8

(3) OH + CH3CHO A = 5.1 ± 1.1 E = −1.7 ± 0.7

(4) OH + (CH3)2CHCHO A = 9.5 ± 3.0 E = −2.6 ± 1.2

(5) OH + (CH3)4CCHO A = 8 ± 4 E = −3.4 ± 1.7
Vanadia Layers Supported on Titania — an FTIR and Raman Investigation
Authors: Schraml M. , Fluhr W. , Wokaun A. , Baiker A.
Published: July 2012

The structure of monolayers and multilayers of V2O5 supported on TiO2 has been investigated by laser Raman spectroscopy. For the catalyst prepared by a single impregnation, disordered polymeric arrays of sixfold‐coordinated vanadium ions are detected. Second impregnation increases the number of Vv centers anchored on the support but does not create new types of structure in detectable amounts. In the third impregnation step additional layers of V2O5 are immobilized on top of the first layer, as evidenced by characteristic Raman bands at ∼996 cm−1 and 285 cm−1. The intensity of these bands from higher layers increases after the fourth impregnation; at this stage the highest specific activity of the supported catalyst for selective catalytic reduction of NO is achieved. The above conclusions are confirmed by FTIR measurements, which reveal structural differences between the vanadia species immobilized in the first and subsequent layers.
The Surface‐vacancy Bonded H2O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing
Authors: Ernst Lajos
Published: July 2012

In the electrostatic processing of raw potash salt the mutual contact charging of its components is an important step. — The contact charging may be component‐selectively stimulated by, mainly, organic acid additives, added to the salt in concentrations of 10 ppm‐s under conditions of well‐defined relative humidity of the ambient air. This technology was developed purely empirically and the mechanism of the stimulated contact charging is as yet unknown. — In the present work some light will be shed onto this mechanism. Results for the contact charging of NaCl versus KCl and versus some metals, stimulated by one of the most frequently used additives, salicylic acid, have been considered. Based on photoemission data from water adsorbed on alkali halide (100) crystal faces, it is suggested that H2O molecules, bonded in surface cation vacancies may have a role in the additive‐induced stimulation of the contact charging. On a NaCl(100) face they may capture the proton from the salicylic acid molecules forming vacancy‐trapped H3O+ ions, with their charge screened by the lattice and quasi‐free salicylate ions. The ionization energy of the latter is so small that their surplus electron may be injected readily into any of the possible contact partners. — The model describes the essential features of the contact charging stimulation of the electrostatic salt processing. The component‐selectivity is as yet not understood, however, the model supplies useful hints related to its possible causes.
Fluids in the Gravitational Field Exact Treatment of One Dimensional Systems
Authors: Schröer W.
Published: July 2012

Partition functions and thermodynamic functions for fluids in one‐dimensional model systems interacting with a gravitational field are investigated. The intermolecular potential is chosen in a manner that only next‐neighbour particles interact, which allows for an exact evaluation of the partition function using elementary methods. The local contributions to the thermodynamic functions are determined by the local pressure. The variation of the Gibbs potential and the density as functions of the height, may show a point of inflexion as real two phase systems. This is discussed for rigid particles interacting with a square well potential, and allowed to assume two states of different lengths.
Solution Non‐Randomness and the W‐Shape Concentration Dependence of CEp for Hexafluorobenzene and Chloronaphthalene in Hydrocarbons
Authors: Andreoli‐Ball L. , Costas M. , Patterson D. , Rubio R. G. , Masegosa R. M. , Caceres M.
Published: July 2012

Excess heat capacities, CEp have been obtained through the concentration range at 25°C for five sets of systems of type An + B: hexafluorobenzene + 2,2,4‐trimethylpentanc and 2,2,4,4,6,8,8‐heptamethylnonane; hexafluorobenzene + cyclohexane (10° W) and dicyclohexyl (W); 1‐chloronaphthalene + 2,2‐dimethylbutane, 2,2,4‐trimethylpentane (W) and 2,2,4,4,6,8,8‐heptamethylncnane (W), 1‐chloronaphthalene + n‐hexadecane; 1‐chloronaphthalene + cyclohexane and dicyclohexyl (15°, W). For the systems indicated, CEp has a W‐shape, i.e., two minima separated by a maximum or two changes of sign of the curvature. The W‐shape does not occur for hexafluorobenzene + cyclohexane at 25° but appears at 10°. Temperature and molecular size act on CEp through the degree of solution non‐randomness as indicated by GE and the concentration‐concentration correlation function, Scc which is a good predictor for the W‐shape and of the concentration at which the maximum appears. The W‐shape corresponds to an Scc value greater than 0.7 and GE > 800 J mol−1, the temperature being within 100 K of the UCST.
Calculation of Thermodynamic Properties of Binary Fluid Mixtures to High Temperatures and High Pressures
Authors: Heilig M. , Franck E. U.
Published: July 2012

An equation of state is presented, which permits prediction of binodal phase equilibrium surfaces and critical curves to 2000 bar and higher for binary fluid systems of partners, which differ significantly in molecular size and polarity. The procedure is an extension and improvement of an equation suggested earlier by Christoforakos and Franck. The equation of state consists of a hard body repulsion term and an additive pertubation term, which takes care of the attractive molecular interaction. For the repulsion, a Carnahan‐Starling‐One‐Fluid (CSOF) expression or suitable extensions are used, which are discussed. The attractive term uses square well potentials. Pairwise three‐body interaction as with second and third virial coefficients is introduced with a Padbapproximant (SWPA). The result is a satisfactory improvement for the calculation of the three‐dimensional binodal surface even for unsymmetric systems like water‐hexane. Critical curves and binodal surfaces, calculated and experimental, to 2500 bar and 400°C are shown for H2O‐N2, H2O ‐ CO2 and H2O ‐hexane: The necessary parameters are given. Extension to three‐phase equilibria and to ternary and quaternary systems is possible.
Induced Smectic Phases and Demixing in Mixtures of Alkanes and Other Nonmesogenic Compounds with Alkyloxy‐ and Alkyl‐cyanobiphenyls
Authors: Heuer H. , Kneppe H. , Schneider F.
Published: July 2012

Demixing / Liquid Crystals / Phase Diagrams / Smectic Phases

n‐Heptyloxy‐ and n‐heptylcyanobiphenyl show induced smectic phases in mixtures with n‐alkanes, n‐alcohols, and n‐alkylbenzenes. Alkyloxycyanobiphenyls with shorter alkyl chains (hexyl and pentyl homologues) show miscibility gaps with an upper consolution temperature in mixtures with alkanes. It is obvious that demixing and induction of smectic phases are related processes and we believe, therefore, that the induction of smectic phases in these mixtures is a microscopical demixing in polar and non‐polar layers. X‐ray measurements in heptyloxycyanobiphenyl/tridecane mixtures support this idea.
Proteinadsorption auf alkylsubstituierten Oberflächen
Authors: Jennissen Herbert P.
Published: July 2012

When confronted with the chromatographic separation of proteins one often has to cope with a large number of parameters which have either been set by the producer or oneself and which in many cases are only poorly understood. Therefore in this paper some of the fundamentals involved in the mechanism of protein adsorption on alkyl‐substituted gel surfaces will be treated. Although a large number of papers have been published on protein adsorption there is no general theory on the adsorption mechanism. The possibility of synthesizing surfaces for adsorption in a controlled way on hydrophilic gels has become feasible after the introduction of affinity chromatography. Since this technique has allowed the elucidation of a number of general mechanistic principles involved in the protein adsorption process and the corresponding sorption kinetics these results will be primarily discussed here.
Operational Modes of Chromatographic Separation Processes
Authors: Antia Firoz D. , Horváth Csaba
Published: July 2012

An overview of the three major operational modes of chromatography — frontal, elution and displacement — is presented with emphasis on their application to the preparative purification of biopolymers. The theoretical basis of the techniques is discussed and some of their features are illustrated with the help of computer simulated chromatograms.
The System Acetone — Water — Glycerol and its Application in Liquid‐Liquid Extraction of Proteins
Authors: Hampe Manfred J. , Schermuly Wolfgang
Published: July 2012

Acetone and glycerol are only partially miscible at room temperature. Addition of up to 50 mole‐% water is allowed without removing the miscibility gap. By varying the water content, the polarities of the raffinate and extract phases can be adjusted to favorite conditions for the extraction of proteins. Short settling and coalescence times result from both rather high density differences and a relative high interfacial tension of up to 7 mN/m. Thus, the system can be handled in common extraction columns, which is an important process design aspect. Recovery of proteins from both phases is very simple, as this liquid‐liquid extraction system does not contain polymers of a molecular weight similar to the proteins. Distribution equilibria of peroxidase, alk. phosphatase and oxytocin will be given.
Selection of Solvents for Extractive Fermentations
Authors: Müller U. , Träger M. , Onken U.
Published: July 2012

Product yield in fermentation processes is often limited by product inhibition or degradation. This may be avoided by extracting the product from the broth during the fermentation. Solvents to be used in these extractive fermentations must be selective for the product and nontoxic for the microorganisms. The procedure of solvent selection is exemplified for the case of formation of cycloheximide by Streptomyces griseus. It is shown that substituted polyglycols, in particular alkylphenol polyethoxylates, are well suited to the requirements of extractive fermentations of antibiotics. In order to prevent foaming the polyglycolether chain of the molecule should contain a few propoxy groups.
Chromatographic Purification of Proteins — Support from Physico‐Chemical Research
Authors: Jagschies Günter
Published: July 2012

On the molecular level, physical chemistry can contribute a lot to the better understanding and easier planning of chromatographic purification steps for biological substances. Particularly in the complex situation faced in the development of purification sequences for proteins, good strategic advice is required to cut down both time and costs needed to optimize results. This article relates some results from physical chemistry to a commercial application situation, and asks for further engagement to produce even more user‐friendly results for the applicative work with chromatography.