bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and study of metal ion sorption capacity of xanthan gum‐g‐2‐acrylamido‐2‐methyl‐1‐propane sulphonic acid
Authors: Srivastava Abhishek , Behari Kunj
Published: January 2007

In this study, xanthan gum‐g‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) was synthesized by free radical polymerization using bromate/thiourea redox pair in inert atmosphere. Various studies have been conducted to observe the effect of reactants on grafting parameters by varying the reactant concentration and to understand the physical–chemical properties. Grafting ratio, add on, and conversion showed a decrease on increasing the concentration of xanthan gum. The grafting parameters increased on increasing the concentration of AMPS from 3 × 10−2 to 6 × 10−2 mol dm−3, BrO3 from 2 × 10−3 to 8 × 10−3 mol dm−3, and thiourea from 1 × 10−3 to 2.8 × 10−3 mol dm−3, respectively. Optimum temperature and time for grafting of AMPS on xanthan gum were found to be 35°C and 120 min. Water swelling capacity, swelling ratio, metal ion uptake, and metal retention capacity were also studied, and it was found that grafted polymer shows better enhancement in these properties than substrate. Graft copolymer was characterized by FTIR and thermal analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 470–478, 2007
Synthesis and nonlinear optical properties of polyphosphazenes with binaphtholyl and indole side groups
Authors: Li Zhen , Qin Jingui , Yang Zhou , Ye Cheng
Published: January 2007

New polyphosphazenes (P2 and P3) that contain indole‐based chromophore and binaphtholyl moieties as side chains are prepared by a new postfunctional strategy. Molecular structural characterization for the high polymers was presented by 1H‐NMR, IR and UV‐Visible spectra, gel permeation chromatograply, and differential scanning calorimetry. The glass transition temperature of P2 was determined to be 168°C, higher than those polyphosphazenes reported previously in the literatures. P2 and P3 are thermal stable and easily soluble in high polar solvents. The maximum absorption of P2 in chloroform was at 425 nm and cuts off at about 550 nm, while that of P3 was 393 nm and 500 nm, respectively, which resulted in a wide transparency window. The poled films of P2 and P3 reveal a resonant d33 value of 20 pm/V and 14 pm/V, respectively, by second harmonic generation measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 365–371, 2007
Photophysical studies of polyvinylcarbazole polymer films
Authors: Patel Shruti , Ramrakhiani M. , Bisen D. P.
Published: January 2007

Polyvinylcarbazole (PVK) films have been prepared by solution method. Their absorption spectra, photoluminescence, and electroluminescence have been studied. Absorption in pure PVK is found to be high at lower wavelengths in UV region and decreases in visible range. In case of I2 doped PVK, absorption is observed in visible region also. The photoluminescence is obtained in pure PVK when exited by violet or blue light but in case of I2 doped PVK, similar excitation gives low intensity peaks in yellow–green region. The results indicate that I2 levels in PVK causes absorption in 400–600 nm wavelength range and makes the deexcitation of the molecules nonradiative. Light emission by application of ac voltage from mains up to 100 V has been studied. Nonlinear increase in emission intensity has been observed with increasing voltage. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 722–726, 2007
Ozonolysis of polybutadienes with different microstructure in solution
Authors: Anachkov M. P. , Rakovsky S. K. , Zaikov G. E.
Published: January 2007

The reaction of ozone with 1,4‐cis‐polybutadiene and polybutadiene having the following linking of the butadiene units: 1,4‐cis (47%), 1,4‐trans (42%), 1,2 (11%) was investigated in CCl4 solution. It was found out by means of IR‐spectroscopy and 1H‐NMR spectroscopy that the basic ozonolysis products of both elastomers are ozonides and aldehydes. The aldehyde:ozonide ratio was 11 : 89 and 27 : 73 for E‐BR and BR, respectively. In addition, epoxide groups were detected, only in the case of BR, and their yield was about 10% of that of the aldehydes. On the basis of BR ozonolysis it was established that the ozonide yield from 1,4‐trans units is about 50%. By using the aldehyde yields, an evaluation was made of the efficiency of ozone degradation of the two polybutadienes, according to which the respective value of BR is considerably higher than that of E‐BR. A reaction mechanism is proposed, which explains the formation of the identified functional groups and the differences in the ozone degradation of the studied elastomers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 427–433, 2007
Thermal degradation of epoxy resin reinforced with polypropylene fibers
Authors: Prabhu T. Niranjana , Hemalatha Y. J. , Harish V. , Prashantha K. , Iyengar P.
Published: January 2007

The influence of polypropylene fibers on the thermal degradation of epoxy composites was investigated with thermogravimetric analysis. Three composites with 5, 10, or 15 wt % polypropylene fibers were prepared with epoxy as a matrix material. The polypropylene fibers, used as reinforcing materials, retarded the thermal decomposition, and increasing the weight percentage of the fiber material increased the thermal stability to a certain extent. Of the three composites, the 10 wt % polypropylene fiber/epoxy resin composite showed very good thermal stability, which was indicated by the increase in the resin decomposition temperature from 280°C for the 5 wt % polypropylene fiber/epoxy resin composite to 375°C for the 10 wt % polypropylene fiber/epoxy resin composite. The Horowitz–Metzger method was used to calculate the activation energies, and the results were tabulated. A morphological analysis was carried out with scanning electron microscopy to evaluate the dispersion of the fibers in the epoxy matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 500–503, 2007
Synthesis of starch‐based plastic films by electron beam irradiation
Authors: El‐Mohdy H. L. Abd
Published: January 2007

Starch‐based plastic films were prepared by the electron beam irradiation of starch and poly(vinyl alcohol) (PVA) in a physical gel state at room temperature. The influence of starch/PVA composition, irradiation dose, and plasticizer (glycerol) on the properties of the plastic films was investigated. The gel fraction of the starch/PVA films increased with both the radiation dose and PVA content in the plastic film and decreased with increasing glycerol concentration. The starch/PVA compatibility was determined by measurement of the thermal properties of the starch/PVA blends with various compositions with differential scanning calorimetry. The swelling of the starch/PVA films increased with increasing PVA content and decreasing irradiation dose. Mechanical studies were carried out, and the tensile strength of the films decreased at high starch ratios in the starch‐based mixture. This was due to the decrease in the degree of crosslinking of starch. Furthermore, when PVA, a biodegradable and flexible‐chain polymer, was incorporated into the starch‐based films, the properties of the films, such as the flexibility (elongation at break), were obviously improved. The tensile strength of the films decreased with increasing glycerol concentration, but elongation at break increased up to a maximum value at a 20% glycerol concentration, and then, it leveled off and decreased slightly. Biodegradation of the starch/PVA plastic films was indicated by weight loss (%) after burial in soil and morphological shape, which was detected by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 504–513, 2007
Influence of support friability and concentration of α‐olefins on gas‐phase ethylene polymerization over polymer‐supported metallocene/methylaluminoxane catalysts
Authors: Hammawa Hassan , Wanke Sieghard E.
Published: January 2007

The effects of support friability (Φ) and ethylene/comonomer ratios were investigated over supported metallocene/methylaluminoxane catalysts prepared with nine different porous polymeric supports and various comonomer concentrations with a 2‐L reactor operated in the semibatch gas‐phase mode at 80°C and 1.4 MPa. Φ of the supports was measured with a newly devised method. The performance of the supported catalysts depended on support Φ as follows. The average homopolymerization activities varied from less than 6 t of polyethylene (PE) (mol of Zr)−1 h−1 for low‐Φ catalysts to 10–20 t of PE (mol of Zr)−1 h−1 for moderate‐Φ catalysts and up to 100 t of PE (mol of Zr)−1 h−1 for the high‐Φ catalysts. The presence of 1‐hexene and propylene comonomers increased the activity of the low‐Φ catalysts by up to 20‐fold and 50‐fold, respectively; that is, there were very marked comonomer effects. Activity enhancement by 1‐hexene was less than 3‐fold for the moderate‐Φ catalysts, whereas the high‐Φ catalysts showed little activity enhancement. Sometimes, 1‐hexene even resulted in activity reductions. Very different particle morphologies were obtained with the catalysts of different Φ's. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 514–527, 2007
X‐ray pole figures to assess orientation in PVC sheets
Authors: Gilbert Marianne , Ross David H , Kim Hwan Chul
Published: January 2007

A series of X‐ray pole figures were obtained from oriented and unoriented rigid polyvinyl chloride sheets. From these, information about crystallite orientation in uniaxially and biaxially drawn sheets stretched at 90°C was obtained. Uniaxial orientation produced two crystallite orientations with the extent of orientation increasing with draw ratio; for biaxial samples the chain direction (c) was distributed uniformly in the plane of the sheet, with the planar orientation improving as draw ratio increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 528–535, 2007
Spectroscopic study of interactions between model direct dyes and cotton
Authors: Pielesz Anna
Published: January 2007

Although examined for years, interactions between direct dyes and the chemical structure of cotton cellulose remain an interesting, and still not entirely known, chemical phenomenon occurring in the fiber. Ten model azo dyes have been studied in aqueous solution, as dye powders and on cotton fabric using 13C MAS NMR and UV–visible spectroscopy. NMR spectroscopy indicates that model azo dyes, especially dye 8, interact by π‐stacking at the central biphenyl group, and that there is hydrogen bonding with cellulose. Model azo dyes are present as the azo or hydrazone tautomer. The UV–visible λmax indicate that shifts are attributed to adsorption of model azo dyes into cellulose surfaces. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 758–766, 2007
Synthesis and characterization of novel saponified guar‐graft‐poly(acrylonitrile)/silica nanocomposite materials
Authors: Singh Vandana , Tiwari Ashutosh , Pandey Sadanand , Singh Somit K. , Sanghi Rashmi
Published: January 2007

The combination of carbohydrates with silicon‐based ceramic materials offers attractive means of production for high performance materials. Present article describes the synthesis of novel nanocomposites out of SiO2 and saponified guar‐graft‐poly(acrylonitrile) (SG). Tetraethoxysilane was used as the precursor for silica and growth of SiO2 phase was allowed concurrently in the presence of SG. The material so obtained was thermally treated at 80°C, 160°C, 500°C, and 900°C to study the effect of thermal curing on its properties. During the curing process, silanol surface groups of silica globules reacted to create the reinforced SiO2‐SG substance. It was observed that at 900°C, the SiO2 phase crystallized out in tetragonal shape (similar to Cristobalite form of silica) in presence of SG. The chemical, structural and textural characteristics of the composites were determined by FTIR, XRD, TGA‐DTA, SEM and BET studies. The materials were also evaluated as efficient Zn2+ metal binder. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 536–544, 2007
Effect of solid‐state shearing of poly(ethylene terephtalate) on isothermal crystallization and fiber structure formation
Authors: Huang Liqian , Pan Lihua , Inoue Takashi
Published: January 2007

Solid‐state shearing was applied on recycled poly(ethylene terephtalate) (PET) using twin‐screw extruder. The shearing effect on isothermal crystallization was investigated by DSC. Structure formation in melt spinning was also studied by characterizing the spun fibers. It was found that the solid‐state shearing imposes a great influence on its crystallization behavior. Crystallization peak temperature of the sheared PET (199°C) was much higher than that of the PET without shearing (188°C). Overall isothermal crystallization rate was found to be accelerated to more than 50 times by the shearing. The shearing effect remained even after fiber spinning (melt processing). Differences in crystallization behavior, fiber structure formation, and tensile properties of the fibers were found. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 787–791, 2007
Melt‐processed biodegradable polyester blends of poly(L‐lactic acid) and poly(ε‐caprolactone): Effects of processing conditions on biodegradation
Authors: Tsuji Hideto , Horikawa Gen , Itsuno Shinichi
Published: January 2007

Biodegradable polyester blends were prepared from poly(L‐lactic acid) (PLLA) and poly(ε‐caprolactone) (PCL) (50/50) by melt‐blending, and the effects of processing conditions (shear rate, time, and strain) of melt‐blending on proteinase‐K‐ and lipase‐catalyzed enzymatic degradability were investigated using gravimetry, differential scanning calorimetry, and scanning electron microscopy. The proteinase‐K‐catalyzed degradation rate of the blend films increased and leveled off with increasing the shear rate, time, or strain for melt‐blending, except for the shortest shear time of 60 s. The optimal processing conditions of melt‐blending giving the maximum rate of lipase‐catalyzed degradation were 9.6 × 102 s−1 and 180 s, whereas a deviation from these conditions caused a reduction in lipase‐catalyzed enzymatic degradation rate. At the highest shear rate of 2.2 × 103 s−1, PCL‐rich phase was continuous in the blend films, irrespective of the shear time (or shear strain), whereas PLLA‐rich phase changed from dispersed to continuous by increasing the shear time (or shear strain). This study revealed that the biodegradability of PLLA/PCL blend materials can be manipulated by altering the processing conditions of melt‐blending (shear rate, time, or strain) or the sizes and morphology of PLLA‐rich and PCL‐rich domains. The method reported in the present study can be utilized for controlling the biodegradability of other biodegradable polyester blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 831–841, 2007
Relaxation time and conductivity of comb‐like gel polymer electrolytes
Authors: Qi Li , Dong Shaojun
Published: January 2007

Using the copolymer of acrylonitrile (AN), methyl methacrylate (MMA), and poly(ethylene glycol) methyl ether methacrylate as a backbone and poly(ethylene glycol) methyl ether (PEGME) with 1100 molecular weight as side chains, comb‐like gel polymers and their Li salt complexes were synthesized. The dynamic mechanical properties and conductivities were investigated. Results showed that the gel copolymer electrolytes possess two glass transitions: α‐transition and β‐transition. Based on the time–temperature equivalence principle, a master curve was constructed by selecting Tα as reference temperature. By reference to T0 = 50°C, the relation between log τc and c was found to be linear. The master curves are displaced progressively to higher frequencies as the content of plasticizer is increased. The relation between log τp and the content of plasticizer is also linear. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 576–584, 2007
Effect of nonconjugated polymers on the conjugation length and structure of poly(3‐octylthiophene) in ternary polymer blend
Authors: Huang Ying‐Jie , Hsieh Tar‐Hwa , Wang Yen‐Zen , Chuang Ching‐Nan , Chen Ya‐Ping , Huang Ping‐Tsung , Ho Ko‐Shan
Published: January 2007

The shifting of λmax (π‐π* transition) of P3OT (poly(3‐n‐octylthiophene)) was used to monitor the degree of miscibility between P3OT and the matrix polymers. In the ternary blend system, 1% of P3OT is soluble in a uniform PMMA/EVA20 mixed matrix and does not interfere with the miscibility between PMMA and EVA20 (ethylene‐vinyl acetate copolymer with 20% of vinyl acetate). But 5% of P3OT can attract EVA20 out of the matrix and induce the separation from 95% of PMMA/EVA20 matrix and cause the doublet peak of λmax. Likewise, the DSC thermograms do not demonstrate the melting‐point depression of EVA20 in a 5% P3OT ternary system. However, the melting‐point depression did occur only for 1% of P3OT. IR‐spectra demonstrate that the methylene groups affinity contributed to the misciblity either in 1% P3OT/PMMA or in P3OT (1 and 5%)/EVA20. The solubility difference of P3OT in PMMA (poor) and EVA20 (better) creates a continuous morphology for obtaining a highly conjugated path in a nonconjugated matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 773–781, 2007
Graft copolymerization of styrene or methyl methacrylate onto syndiotactic polystyrene by ATRP technique
Authors: Abbasian Mojtaba , Rahmani Sohrab , Mohammadi Reza , Entezami Ali Akbar
Published: January 2007

Functionalized syndiotactic polystyrene (sPS) copolymers, including sPS‐graft‐atactic polystyrene (aPS) copolymer or sPS‐graft‐poly(methyl methacrylate) (PMMA) copolymer, were synthesized and characterized. sPS has been synthesized by using half sandwich titanocene/methylaluminoxane catalyst in homogenous conditions. Then, α‐phenyl chloroacetylation of sPS was accomplished in a heterogeneous process by using carbon disulfide as dispersing medium and α‐phenyl chloroacetyl chloride and anhydrous aluminum chloride as acetylating agent and catalyst, respectively. The graft copolymer of sPS with aPS or PMMA were synthesized by atom transfer radical polymerization using α‐phenyl chloroacethylated sPS as initiator and CuBr and bipyridine as catalyst. The structure of obtained copolymer was investigated by 1H NMR, FTIR spectroscopy, and thermal behavior of copolymers was performed by differential scanning calorimetry analyses. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 611–619, 2007
Processable and colorless fluorinated poly(ether imide)s based on an isopropylidene‐containing bis(ether anhydride) and various aromatic bis(ether amine)s bearing trifluoromethyl groups
Authors: Huang Sheng‐Yu , Yang Chin‐Ping , Hsiao Sheng‐Huei
Published: January 2007

A series of novel organosoluble and light‐colored fluorinated poly(ether imide)s (PEIs) (IV) having inherent viscosities of 0.43–0.59 dL/g were prepared from 4,4′‐[1,4‐phenylenbis(isopropylidene‐1,4‐phenyleneoxy)]diphthalic anhydride (I) and various trifluoromethyl‐substituted aromatic bis(ether amine)s by a standard two‐step process with thermal and chemical imidization of poly(amic acid) precursors. These PEIs showed excellent solubility in many organic solvents and could be solution‐cast into transparent and tough films. These films were essentially colorless, with an UV–visible absorption edge of 361–375 nm and a very low b* value (a yellowness index) of 15.3–17.0. They also showed good thermal stability with glass‐transition temperature of 191–248°C, 10% weight loss temperature in excess of 494°C, and char yields at 800°C in nitrogen more than 39%. The thermally cured PEI films showed good mechanical properties with tensile strengths of 83–96 MPa, elongations at break of 8–11%, and initial moduli of 1.7–2.0 GPa. They possessed lower dielectric constants of 3.25–3.72 (1 MHz). In comparison with the V series nonfluorinated PEIs, the IV series showed better solubility, lower color intensity, and lower dielectric constants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 620–628, 2007
Blends of triazine‐based hyperbranched polyether with LDPE and plasticized PVC
Authors: Borah Jyotishmoy , Karak Niranjan
Published: January 2007

Triazine‐based hyperbranched polyether was obtained by earlier reported method and blended with low density polyethylene (LDPE) and plasticized poly(vinyl chloride) (PVC) separately to improve some desirable properties of those linear polymers. The properties like processability, mechanical properties, flammability, etc. of those linear polymers were studied by blending with 1–7.5 phr of hyperbranched polyether. The mechanical properties were also measured after thermal aging and leaching in different chemical media. SEM study indicates that both polymers exhibit homogenous morphology at all dose levels. The mechanical properties like tensile strength, elongation at break, hardness, etc. of LDPE and PVC increase with the increase of dose level of hyperbranched polyether. The flame retardant behavior as measured by limiting oxygen index (LOI) for all blends indicates an enhanced LOI value compared to the polymer without hyperbranched polyether. The processing behavior of both types of blends as measured by solution viscosity and melt flow rate value indicates that hyperbranched polyether acts as a process aid for those base polymers. The effect of leaching and heat aging of these linear polymers on the mechanical properties showed that hyperbranched polyether is a superior antidegradant compared to the commercially used N‐isopropyl‐N‐phenyl p‐phenylene diamine. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 648–654, 2007
Comparison of the growth process and electrochemical properties of polyaniline films prepared by pulse potentiostatic and potentiostatic method on titanium electrode
Authors: Zhou H. H. , Wen J. B. , Ning X. H. , Fu C. P. , Chen J. H. , Kuang Y. F.
Published: January 2007

Polyaniline (PANI) films were deposited on titanium (Ti) electrode in a bath containing 0.3 mol L−1 aniline and 1 mol L−1 HNO3 by pulse potentiostatic method (PPM) and potentiostatic method (PM). The chronoamperograms during aniline polymerization were recorded, and the morphologies of PANI films prepared with different polymerization periods were examined under scanning electron microscope. The difference between the processes of PANI films growth was studied. The growth processes of PANI films prepared by PPM and PM are divided into two stages. For both PPM and PM, the first stage corresponds to the formation of a compact granular PANI layer on the surface of Ti electrode. The second stage corresponds to further growth of PANI film on the surface of the compact granular PANI film. However, the PANI films prepared by PPM and PM show different morphologies in this stage. In addition, the electrochemical properties of the PANI films prepared by PPM and PM are obviously different. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 458–463, 2007
User modeling for personalized Web search with self‐organizing map
Authors: Ding Chen , Patra Jagdish C.
Published: January 2007

The widely used Web search engines index and recommend individual Web pages in response to a few keywords queries to assist users in locating relevant documents. However, the Web search engines give different users the same answer set, although the users may have different preferences. A personalized Web search would carry out the search for each user according to his or her preferences. To conduct the personalized Web search, the authors provide a novel approach to model the user profile with a self‐organizing map (SOM). Their results indicate that SOM is capable of helping the user to find the related category for each query used in the Web search to make a personalized Web search effective.
Kinetic modeling of phototrophic biofilms: The PHOBIA model
Authors: Wolf Gundula , Picioreanu Cristian , van Loosdrecht Mark C.M.
Published: January 2007

A kinetic model for mixed phototrophic biofilms is introduced, which focuses on the interactions between photoautotrophic, heterotrophic, and chemoautotrophic (nitrifying) functional microbial groups. Biofilm‐specific phenomena are taken into account, such as extracellular polymeric substances (EPS) production by phototrophs as well as gradients of substrates and light in the biofilm. Acid–base equilibria, in particular carbon speciation, are explicitly accounted for, allowing for the determination of pH profiles across the biofilm. Further to previous models reported in literature, the PHOBIA model combines a number of kinetic mechanisms specific to phototrophic microbial communities, such as internal polyglucose storage under dynamic light conditions, phototrophic growth in the darkness using internally stored reserves, photoadaptation and photoinhibition, preference for ammonia over nitrate as N‐source and the ability to utilize bicarbonate as a carbon source in the absence of CO2. The sensitivity of the PHOBIA model to a number of key parameters is analyzed. An example on the potential use of phototrophic biofilms in wastewater polishing is discussed, where their performance is compared with conventional algal ponds. The PHOBIA model is presented in a manner that is compatible with other reference models in the area of water treatment. Its current version forms a theoretical base which is readily extendable once further experimental observations become available. Biotechnol. Bioeng. 2007; 97: 1064–1079. © 2007 Wiley Periodicals, Inc.
Enhanced preparation of adeno‐associated viral vectors by using high hydrostatic pressure to selectively inactivate helper adenovirus
Authors: Leonard Joshua N. , Ferstl Peter , Delgado Antonio , Schaffer David V.
Published: January 2007

Gene delivery vectors based on adeno‐associated virus (AAV) have significant therapeutic potential, but much room for improvement remains in the areas of vector engineering and production. AAV production requires complementation with either helper virus, such as adenovirus, or plasmids containing helper genes, and helper virus‐based approaches have distinct advantages in the use of bioreactors to produce large quantities of AAV vectors for clinical applications. However, helper viruses must eventually be inactivated and removed from AAV preparations to ensure safety. The current practice of thermally inactivating adenovirus is problematic as it can also inactivate AAV. Here, we report a novel method using high hydrostatic pressure (HHP) to selectively and completely inactivate helper adenovirus without any detectable loss of functional AAV vectors. The pressure inactivation kinetics of human adenovirus serotype 5 and the high‐pressure stabilities of AAV serotypes 2 and 5 (AAV2, AAV5), which were previously unknown, were characterized. Adenovirus was inactivated beyond detection at 260 MPa or higher, whereas AAV2 was stable up to ∼450 MPa, and surprisingly, AAV5 was stable up to at least 700 MPa. The viral genomic DNA of pressure‐inactivated AAV2 was made sensitive to DNAse I digestion, suggesting that gross changes in particle structure had occurred, and this hypothesis was further supported by transmission electron microscopy. This approach should be useful in the laboratory‐ and clinical‐scale production of AAV gene delivery vectors. Moreover, HHP provides a tool for probing the biophysical properties of AAV, which may facilitate understanding and improving the functions of this important virus. Biotechnol. Bioeng. 2007; 97: 1170–1179. © 2007 Wiley Periodicals, Inc.
Effects of Operational Variables on Nitrogen Removal Performances and Its Control in a Pre‐Denitrification Plant
Authors: Wang X. L. , Peng Y. Z. , Ma Y. , Wang S. Y.
Published: January 2007

The aim of this work is to study the effects of six operational variables, i.e., dissolved oxygen (DO), nitrate recirculation flow, sludge recycle flow, sludge wastage flow, external carbon dosage, and anoxic volume fraction, on the performance of nitrogen removal and its control in a pre‐denitrification plant. The results obtained show that the six operational variables have a significant influence on nitrogen removal in such a system, while the utilization of the control strategies can improve the situation to a significant extent. The control of DO concentration should be correlated with the influent ammonia load, the effluent requirement and nitrification type. The anoxic effluent nitrate concentration should be controlled at ca. 2 mg/L or the ORP value at the end of the anoxic zone should be controlled at ca. –90 mV. The control of the sludge recycling flow by online monitoring of the sludge blanket height (SBH), is an alternative to the conventional control of the constant sludge recycle flow. It may be possible to achieve the automatic control of sludge wastage flow by online measuring of the ammonia concentration and the nitrification capacity of the sludge. The recirculation of nitrate and external carbon dosage should be simultaneously controlled to optimize nitrogen removal. The anoxic volume fraction should also be optimized, to ensure a good balance between nitrification and denitrification.
Modeling of the Seedless Grape Drying Process using the Generalized Differential Quadrature Method
Authors: Esmaiili M. , Rezazadeh G. , Sotudeh‐Gharebagh R. , Tahmasebi A.
Published: January 2007

Mathematical modeling of the grape drying process is important in understanding the transport phenomena involved in the production and processing of dried grapes. Drying models proposed in the literature have simplifying assumptions, and thus ignore important phenomena such as shrinkage and changes in transport properties which occur during the drying process. Consequently, a mathematical model is developed for the seedless grape drying process, which considers the effects neglected in previous models. Since an analytic solution to this nonlinear model is impossible, the generalized differential quadrature method is used to solve the models' equations. The model is validated with experimental data obtained from a laboratory scale convective tray dryer operating at 50–70 °C and an air velocity of 1.5 m/s. Model predictions are in close agreement with experimental data due to the inclusion in the model of shrinkage and variation in moisture diffusivity. Model results can serve as a framework to improve the performance of existing and novel dryers, and also in the design of process simulators for dryers.
Triboelectrostatic Separation of Fly Ash with Different Charging Materials
Authors: Soong Y. , Irdi G. A. , McLendon T. R. , Hedges S. W. , Dilmor R. M. , Griffith C. , Romanov V. , Haljasmaa I.
Published: January 2007

A combination of mechanical sieving and triboelectrostatic separation were used to separate fly ash. The results indicate that a simple separation of unburned carbon from fly ash is achievable at particle sizes of 74 and 44 microns. Subsequently, triboelectrostatic separations were conducted via a louvered plate separator. The results show that the final carbon content in the products, which can be as low as 1.5 % or as high as 60 % with different mineral components, can be further adjusted with the combination of sieving, louvered plate separator with a tribocharger made of different materials (copper and Teflon), and the location on the louvered plate where the fly ash particles were collected.
Noncatalytic Hydrolysis of Iminodiacetonitrile in Near‐Critical Water – A Green Process for the Manufacture of Iminodiacetic Acid
Authors: Duan P.‐G. , Wang X. , Dai L.‐Y.
Published: January 2007

The hydrolysis of iminodiacetonitrile (IDAN) in near‐critical water, without added catalysts, has been successfully conducted with temperature and residence time ranges of 200–260 °C and 10–60 min, respectively. The effects of temperature, pressure, and initial reactant/water ratio on the reaction rate and yield have been investigated. The final reaction products primarily included iminodiacetic acid (IDA) and ammonia associated with other by‐products; gas formation was negligible. The maximum yield of IDA was 92.3 mol.‐% at 210 °C and 10 MPa, with a conversion of almost 100 %.The apparent activation energy and ln A of IDAN hydrolysis were evaluated as 45.77 ± 5.26 kJ/mol and 8.6 ± 0.1 min–1, respectively, based on the assumption of first‐order reaction. The reaction mechanism and scheme were similar to those of base‐catalyzed reactions of nitriles examined in less severe conditions.
Technology Optimization of Wet Flue Gas Desulfurization Process
Authors: Hrastel I. , Gerbec M. , Stergaršek A.
Published: January 2007

Optimization of the wet limestone (calcite) flue gas desulfurization (FGD) process is described, with the focus on the layout of subprocesses and equipment. The aim of optimization was to check the effectiveness and reliability of alternative layouts, involving intermediate product (gypsum) storage in the absorber make‐up tank, instant production of limestone slurry from powder in a wet screw conveyer and automatic gypsum dewatering line operation. Three alternatives, standard layout, optimized layout and optimized layout without reheating of treated gas, were designed and tested in a small industrial FGD plant. The comparison included evaluation of desulfurization efficiency, economical feasibility (considering a 125 MW power plant) and reliability of operation. The efficiency of the system was not affected by the layouts. Investment costs were reduced by 5 and 15 % for alternatives 1 and 2, respectively, compared to standard offers on the market. With respect to operating costs, variable operating and maintenance costs could be decreased by 0.5 up to 2.5 %, respectively. As shown by risk and reliability analysis, the availability of the system in both alternative layouts remained unchanged or was better with regard to the standard layout.
Determination of Liquid Radial Spreading Coefficients of Some Highly Effective Packings
Authors: Dzhonova‐Atanasova D. , Kolev N. , Nakov S.
Published: January 2007

The liquid radial spreading coefficient of packings for absorption and rectification columns is necessary to determine the packing height which ensures uniform liquid distribution over the column cross section. The existing calculation methods can be used theoretically only when this coefficient is independent of the liquid superficial velocity, which is often not the case. A tracer method free from this limitation is developed and tested. The spreading coefficients for different sizes of modern, highly effective packings (Raschig Super‐Ring, Ralu‐Flow, and impulse metal tower packing) are determined. Practically, in the range of the experimental error, the spreading coefficients of these packings are independent of the liquid superficial velocity. For such packings the tracer method is expected to give the same results as the existing single jet method. Some differences between the results of these two methods are discussed and an explanation is proposed.
Effects of Ionic Environments on Bovine Serum Albumin Fouling in a Cross‐Flow Ultrafiltration System
Authors: Salgın S.
Published: January 2007

The influence of electrostatic interactions on membrane fouling during the separation of bovine serum albumin (BSA) from solution was studied in a cross‐flow ultrafiltration system. Experiments were carried out at different pH values between 3.78 and 7.46; and for different ionic strengths between 0.001 M and 0.1 M. The changes in permeate flux, cake layer resistance, zeta potentials of BSA and polyether sulfone (PES) membranes, and electrostatic interaction energies, were evaluated. At all of the ionic conditions studied, PES membranes are negatively charged. However, BSA molecules are either negatively or positively charged depending on the ionic environment. Whereas the cake layer resistance decreased with increasing pH and ionic strength, the permeate fluxes increased. The calculated electrostatic energy was a minimum at the isoelectric point (IEP) of BSA. However, at this point, the cake resistances corresponding to fouling at each ionic strength, were not minimized. Below the IEP of BSA, the electrostatic forces were attractive, while above the IEP, repulsive electrostatic forces were dominant.
Protonenaustauschmembranen durch strahlungsinduzierte Pfropfpolymerisation von Glycidylmethacrylat auf ETFE – Modifizierung mit Butylacrylat und Acrylnitril
Authors: Schmidt C. , Glück T. , Schmidt‐Naake G.
Published: January 2007

Die Suche nach Alternativen zum meist verwendeten Nafion® für polymere Protonenaustauschmembranen in Wasserstoff‐Brennstoffzellen ist seit Jahren Gegenstand zahlreicher Forschungsaktivitäten. Diese Arbeit stellt Systeme auf Basis von Poly(tetraflourethylen‐alt‐ethylen) (ETFE) vor, das über die einfache und vielseitige strahlungsinduzierte Pfropfpolymerisation mit Glycidylmethacrylat gepfropft und durch Sulfonierung in Austauschmembranen überführt wird. Im Vordergrund steht dabei die Modifizierung dieser Systeme durch Copolymerisation mit Butylacrylat und Acrylnitril und die Charakterisierung der Materialien in Hinblick auf mechanische und thermische Stabilität, Wasseraufnahme und Ionenleitfähigkeit.
Fluoroartemisinins: Metabolically More Stable Antimalarial Artemisinin Derivatives
Authors: Bégué Jean‐Pierre , Bonnet‐Delpon Danièle
Published: January 2007

This report is an overview on the design, preparation, and evaluation of metabolically stable artemisinins, using fluorine substitution. The chemical challenges encountered for the incorporation of fluorine‐containing elements and the preparation of a large range of 10‐trifluoromethyl artemisinin derivatives are detailed. Impact of the fluorine substitution on the antimalarial activity is also highlighted. Preclinical data of lead compounds, and evidence for their strong and prolonged antimalarial activity are presented.
Chemical Tools to Investigate Sphingolipid Metabolism and Functions
Authors: Delgado Antonio , Casas Josefina , Llebaria Amadeu , Abad José Luis , Fabriás Gemma
Published: January 2007

Sphingolipids comprise an important group of biomolecules, some of which have been shown to play important roles in the regulation of many cell functions. From a structural standpoint, they all share a long 2‐amino‐1,3‐diol chain, which can be either saturated (sphinganine), hydroxylated at C4 (phytosphingosine), or unsaturated at C4 (sphingosine) as in most mammalian cells. N‐acylation of sphingosine leads to ceramide, a key intermediate in sphingolipd metabolism that can be enzymatically modified at the C1‐OH position to other biologically important sphingolipids, such as sphingomyelin or glycosphingolipids. In addition, both ceramide and sphingosine can be phosphorylated at C1‐OH to give ceramide‐1‐phosphate and sphingosine‐1‐phosphate, respectively. To better understand the biological and biophysical roles of sphingolipids, many efforts have been made to design synthetic analogues as chemical tools able to unravel their structure–activity relationships, and to alter their cellular levels. This last approach has been thoroughly studied by the development of specific inhibitors of some key enzymes that play an important role in biosynthesis or metabolism of these intriguing lipids. With the above premises in mind, the aim of this review is to collect, in a systematic way, the recent efforts described in the literature leading to the development of new chemical entities specifically designed to achieve the above goals.
Cells meeting our immunophenotypic criteria of endothelial cells are large platelets
Authors: Strijbos Michiel H. , Kraan Jaco , den Bakker Michael A. , Lambrecht Bart N. , Sleijfer Stefan , Gratama Jan W.
Published: January 2007

Background

Circulating endothelial cells (CEC) are shed from damaged vasculature, making them a rational choice to serve as surrogate marker for vascular damage. Currently, various techniques and CEC definitions are in use, and their standardization and validation is needed. A flow cytometric single platform assay defining CEC as forward light scatter (FSC)low‐to‐intermedate, sideward light scatter (SSC)low, CD45−, CD31++ and CD146+ is a promising approach to enumerate CEC because of its simplicity (Mancuso et al., Blood 2001;97:3658–3661). Here, we set out to confirm the endothelial nature of these cells.

Methods

We isolated cells with a FSClow‐to‐intermediate, SSClow, CD31++, CD45dim immunophenotype (termed “cells meeting our immunophenotypic criteria for endothelial cells” [CMOIC]) from healthy donors to study the expression of endothelium‐associated markers using several techniques. Special attention was paid to reagents identifying the endothelial cell‐specific marker CD146. We compared antigen expression patterns of CMOIC with those of the HUVEC endothelial cell line and lymphocytes. Electron microscopy was used to detect the presence of endothelial cell‐specific Weibel–Palade bodies in the sorted cells.

Results

CD146 expression was negative on CMOIC for all tested CD146 mAbs, but positive on HUVEC cells and a minor subset of T lymphocytes. Using flow cytometry, we found no expression of any endothelium‐associated marker except for CD31 and CD34. HUVEC cells were positive for all endothelial markers except for CD34. Evaluation of CMOIC morphology showed a homogenous population of cells with a highly irregular nucleus‐like structure and positive endothelial immunohistochemistry. CMOIC contained neither nuclei nor DNA. Electron microscopy revealed the absence of a nucleus, the absence of endothelial specific Weibel–Palade bodies, and revealed CMOIC to be large platelets.

Conclusion

The vast majority of cells with the immunophenotype FSClow‐to‐intermediate, SSClow, CD45−, CD31++ do not express CD146 and are large platelets rather than endothelial cells. © 2007 Clinical Cytometry Society.
Exposure to environmental enrichment elicits differential hippocampal cell proliferation: Role of individual responsiveness to anxiety
Authors: Leal‐Galicia Perla , Saldívar‐González Alfredo , Morimoto Sumiko , Arias Clorinda
Published: January 2007

Environmental enrichment (EE) is a largely employed behavioral procedure in which animals are exposed to high stimulation compared with conventional housing conditions. Animal exposure to an EE exerts beneficial effects on the performance of different learning tasks and induces a number of behavioral, neurochemical, and neuroanatomical changes including hippocampal cell proliferation. However, the importance of voluntary interaction with the environment in these changes has not been clearly resolved yet. Moreover, the effects of a complex environment on animal emotionality still remains questionable and has not been explored in detail under conditions that allow unmasking individual responses among subjects in a group. The present study was aimed at exposing groups of rats to an EE, and analyzing individual differences in activity levels during EE sessions. We observed differences with respect to the activity level displayed by rats during the enriched sessions, which correlated with differences in the rate of hippocampal cell proliferation. It is suggested that exposure to EE may reduce anxiety‐like behaviors and may elicit individual differences on emotional reactions positively linked with hippocampal neurogenesis and testosterone levels. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Sexually dimorphic SCAMP1 expression in the forebrain motor pathway for song production of juvenile zebra finches
Authors: Tang Yu Ping , Peabody Camilla , Tomaszycki Michelle L. , Wade Juli
Published: January 2007

Mechanisms regulating sexual differentiation of the zebra finch song system are not well understood. The present study was designed to more fully characterize secretory carrier membrane protein 1 (SCAMP1), which was identified in a cDNA microarray screen as showing increased expression in the forebrains of developing male compared with female zebra finches. We completed the sequence of the open reading frame and used in situ hybridization to compare mRNA in song control regions of juvenile (25‐day‐old) individuals. Expression was significantly greater in the HVC (used as a proper name) and robust nucleus of the arcopallium (RA) in males than in females. Immunohistochemistry revealed that SCAMP1 protein is also expressed in these two brain regions, and qualitatively appears greater in males. Western analysis confirmed that the protein is increased in the telencephalon of males when compared with females at 25 days of age. These results are consistent with the idea that SCAMP1 is involved in masculinization of these brain areas, perhaps facilitating the survival of cells within them. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Gaseous neuromodulator‐related genes expressed in the brain of honeybee Apis mellifera
Authors: Watanabe Takayuki , Kikuchi Mika , Hatakeyama Dai , Shiga Takumi , Yamamoto Takehiro , Aonuma Hitoshi , Takahata Masakazu , Suzuki Norio , Ito Etsuro
Published: January 2007

Nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO) are thought to act as gaseous neuromodulators in the brain across species. For example, in the brain of honeybee Apis mellifera, NO plays important roles in olfactory learning and discrimination, but the existence of H2S‐ and CO‐mediated signaling pathways remains unknown. In the present study, we identified the genes of nitric oxide synthase (NOS), soluble guanylyl cyclase (sGC), cystathionine β‐synthase (CBS), and heme oxygenase (HO) from the honeybee brain. The honeybee brain contains at least one gene for each of NOS, CBS, and HO. The deduced proteins for NOS, CBS, and HO are thought to contain domains to generate NO, H2S, and CO, respectively, and to contain putative Ca2+/calmodulin‐binding domains. On the other hand, the honeybee brain contains three subunits of sGC: sGCα1, sGCβ1, and sGCβ3. Phylogenetic analysis of sGC revealed that Apis sGCα1 and sGCβ1 are closely related to NO‐ and CO‐sensitive sGC subunits, whereas Apis sGCβ3 is closely related to insect O2‐sensitive sGC subunits. In addition, we performed in situ hybridization for Apis NOS mRNA and NADPH‐diaphorase histochemistry in the honeybee brain. The NOS gene was strongly expressed in the optic lobes and in the Kenyon cells of the mushroom bodies. NOS activity was detected in the optic lobes, the mushroom bodies, the central body complex, the lateral protocerebral lobes, and the antennal lobes. These findings suggest that NO is involved in various brain functions and that H2S and CO can be endogenously produced in the honeybee brain. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Tris(dibenzo[a,d]cycloheptenyl)phosphane: A Bulky Monodentate or Tetrapodal Ligand
Authors: Fischbach Urs , Rüegger Heinz , Grützmacher Hansjörg
Published: January 2007

The tetradendate phosphane tris(5H‐dibenzo[a,d]cyclohepten‐5‐yl)phosphane (trop3P, 1) was synthesized from tris(trimethylsilyl)phosphane and 5‐chloro‐5H‐dibenzo[a,d]cycloheptene. Sulfurization of 1 with elemental sulfur led to trop3P=S. Complexes of 1 with AgI, AuI, RhI, IrI, and PdII were prepared. The structures of trop3P (1), trop3P=S (2), [AgCl(trop3P)] (3), [Au(trop3P)(MeCN)]PF6 (5), [RhCl(trop3P)] (6) and [Pd(trop3P)(H2O)](OTf)2 (9) were determined by X‐ray diffraction studies. In the coinage metal complexes, 1 serves as monodentate extremely bulky κ1‐phosphane ligand (cone angle ca. 250°). In the RhI, IrI, and PdII complexes, 1 acts as tetradendate ligand. CP MAS NMR spectroscopy shows that the span of the chemical shift tensor increases in 7, 6, and 9 in this order (Ω = 310 ppm, 410 ppm, 465 ppm) and contains two strongly deshielded components, which are responsible for the unusual high frequency isotropic shift of the 31P resonances. This property correlates inversely with the metal to olefin backbonding (M→C=Ctrop) and δ(31P) decreases with increasing M→C=Ctrop in the order 9 (δ = 260 ppm) > 7 (δ = 196 ppm) > 6 (δ = 135 ppm) > 3 (δ = –30.9 ppm). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)