bluuebunny/crossref_metadata_2025 huggingface dataset:
Practical methods for measuring the tortuosity of porous materials from binary or gray‐tone tomographic reconstructions
Authors: Gommes Cedric J. , Bons Anton‐Jan , Blacher Silvia , Dunsmuir John H. , Tsou Andy H.
Published: June 2009

Two practical methods are proposed to measure the tortuosity of a porous or permeable material from its tomographic reconstruction. The first method is based on the direct measurement of the shortest distance between two points in the pores, and the second is based on the geodesic reconstruction of the pore or permeation space. Unlike the first method, the second can be directly applied to gray‐tone tomograms, without the need of a segmentation step. The methods are illustrated with an electron tomogram of clay/plastic nanocomposite, an X‐ray microtomogram of sandstone, and a series of model morphologies consisting of penetrable random spheres. For the latter series, the measured tortuosities compare very well with those derived independently from the theoretical effective diffusion coefficients. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Modeling of velocity distribution among microchannels with triangle manifolds
Authors: Pan Minqiang , Tang Yong , Yu Hao , Chen Hongqing
Published: June 2009

A model of velocity distribution among microchannels with triangle manifolds is proposed. According to the flow behaviors analyzed by Fluent, the manifolds are divided into several approximate rectangular channels, and then an equivalent simplified resistance network model is developed to establish the relationships between the velocities and pressure drops in microchannels and approximate rectangular channels. The velocity distributions are calculated under two situations, respectively, considering and ignoring singular losses. The outcomes of the present study are compared with Fluent's simulated results to analyze the effects of singular losses on the velocity distributions. It indicates that the proposed model is suitable for the calculation of velocity distribution among microchannels with obtuse angled or right triangle manifolds under low Reynolds numbers. The premise of ignoring singular losses is that the frictional pressure drops are three times larger than the singular pressure drops in each flow loop. The manifold optimization results indicate that the velocity distribution among microchannels with right triangle manifolds is much more uniform than that of the corresponding one with obtuse angled manifolds. © 2009 American Institute of Chemical Engineers AIChE J, 55: 1969–1982, 2009
Snap‐off of a liquid drop immersed in another liquid flowing through a constricted capillary
Authors: Peña T. J. , Carvalho M. S. , Alvarado V.
Published: June 2009

Emulsions are encountered at different stages of oil production processes, often impacting many aspects of oilfield operations. Emulsions may form as oil and water come in contact inside the reservoir rock, valves, pumps, and other equipments. Snap‐off is a possible mechanism to explain emulsion formation in two‐phase flow in porous media. Quartz capillary tubes with a constriction (pore neck) served to analyze snap‐off of long (“infinite”) oil droplets as a function of capillary number and oil‐water viscosity ratio. The flow of large oil drops through the constriction and the drop break‐up process were visualized using an optical microscope. Snap‐off occurrence was mapped as a function of flow parameters. High oil viscosity suppresses the breakup process, whereas snap‐up was always observed at low dispersed‐phase viscosity. At moderate viscosity oil/water ratio, snap‐off was observed only at low capillary number. Mechanistic explanations based on competing forces in the liquid phases were proposed. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Behavioral patterns of drop impingement onto rigid substrates with a wide range of wettability and different surface temperatures
Authors: Li Xiying , Ma Xuehu , Lan Zhong
Published: June 2009

This article concerns behavioral patterns of droplet impingement onto solid substrates covering a wide range of wettability from hydrophilic to superhydrophobic surfaces heated at different temperatures. For droplet impingement onto partial hydrophobic surfaces (mirror‐polished Cu substrate), the maximum heights of receding droplet undergoing a consecutive increment with surface temperature can be explained taking account of Marangoni flow. Also, the relation to predict the increment of droplet heights with surface temperature was manifested in the light of lubrication approximation combined with energy conservation. However, this relation is only valid for droplet impacts onto partial hydrophobic surface, because the recoiling droplet height was observed to be independent of surface temperature for both hydrophilic and superhydrophobic targets. This phenomenon was attributed to inherent wettability accompanying larger contact angle hysteresis for the hydrophilic substrate and to the presence of an adiabatic gas layer between the composite surface and impacting droplet, for the superhydrophobic target. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Saliva of the graminivorous Theropithecus gelada lacks proline‐rich proteins and tannin‐binding capacity
Authors: Mau Marcus , Südekum Karl‐Heinz , Johann Achim , Sliwa Alexander , Kaiser Thomas M.
Published: June 2009

Gelada baboons are the sole survivors of the genus Theropithecus and the only known graminivorous primates. They developed special adaptations to their diet such as high‐crowned teeth for processing hard and abrasive feed. The fine‐tuning of salivary protein composition might be another key mechanism that is used by species for adapting to the environment and competing with rivals for exploiting new ecological niches. In order to test whether gelada (graminivorous) and hamadryas baboons (omnivorous) differ in their salivary protein composition, we compared whole saliva samples of captive Theropithecus gelada and Papio hamadryas using gel electrophoresis and tannin‐binding assay. We hypothesized that the amount of proline‐rich salivary proteins with tannin‐binding capacity is higher in baboons consuming a feed with high dicot/monocot rations. Dicots produce tannins as a chemical defense system, discouraging animals from eating them. In contrast to dicots, monocots do not synthesize tannins. The presence of tannin‐binding proteins in saliva should effectively inactivate the dicot tannin‐based defense mechanism and increase the dietary breadth and/or the capability to switch between monocots and dicot leaves. The lack of such tannin‐binding proteins in saliva would indicate a narrow dietary spectrum more restricted to monocots.

We found T. gelada to completely lack proline‐rich proteins (PRPs) and tannin‐binding capacity similar to a great variety of other grazing mammals. In contrast, P. hamadryas does possess PRPs with tannin‐binding activity. The findings support a growing body of evidence suggesting a high‐level specialization of T. gelada to grass diets. However, it remains unclear, whether loss of salivary tannin‐binding capacity drove the gelada into its narrow feeding niche, or whether this loss is the result of a long process of increased specialization. Thus, from an ecological point of view, T. gelada appears to be more vulnerable to environmental changes than other baboon species owing to its narrow dietary traits. Am. J. Primatol. 71:663–669, 2009. © 2009 Wiley‐Liss, Inc.
Intracranial atherosclerotic disease: An update
Authors: Qureshi Adnan I. , Feldmann Edward , Gomez Camilo R. , Johnston S. Claiborne , Kasner Scott E. , Quick Donald C. , Rasmussen Peter A. , Suri M. Fareed K. , Taylor Robert A. , Zaidat Osama O.
Published: June 2009

The consensus conference on intracranial atherosclerosis provides a comprehensive review of the existing literature relevant to the epidemiology, diagnosis, prevention, and treatment of intracranial atherosclerosis, and identifies principles of management and research priorities. Patients who have suffered a stroke or transient ischemic attack attributed to stenosis (50–99%) of a major intracranial artery face a 12 to 14% risk for subsequent stroke during the 2‐year period after the initial ischemic event, despite treatment with antithrombotic medications. The annual risk for subsequent stroke may exceed 20% in high‐risk groups. In patients with intracranial atherosclerotic disease, short‐term and long‐term anticoagulation is not superior to antiplatelet treatment. Overall, the subgroup analyses from randomized trials provide evidence about benefit of aggressive atherogenic risk factor management. Intracranial angioplasty with or without stent placement has evolved as a therapeutic option for patients with symptomatic intracranial atherosclerotic disease, particularly those with high‐grade stenosis with recurrent ischemic symptoms, medication failure, or both. A multicenter randomized trial is currently under way to compare stent placement with intense medical management for patients with high‐grade symptomatic intracranial atherosclerotic disease. Ann Neurol 2009;66:730–738
Modification of natural polymer via free radical graft copolymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid in aqueous media and study of swelling and metal ion sorption behavior
Authors: Srivastava Arti , Behari Kunj
Published: June 2009

In the present article, the graft copolymer of xanthan gum with 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) was synthesized using potassium bromate/ascorbic acid as a redox initiator in aqueous medium; reaction conditions were optimized to obtain maximum % grafting ratio (%G). The optimum concentration of BrO ion, ascorbic acid, H+ ion, and AMPS for maximum %G were 8.0 × 10−3, 2.8 × 10−3, 4.0 × 10−3, and 33.2 × 10−3 mol dm−3, respectively. The maximum %G (433.0) occurred at a minimum concentration of xanthan gum, i.e., 0.6 g dm−3. The optimum time duration and temperature of the reaction for maximum % of grafting were 180 min and 45°C, respectively. The graft copolymer was characterized by FTIR spectroscopy. The thermal analysis of xanthan gum and prepared graft copolymer was performed in a nitrogen atmosphere to study their thermal behavior. It was observed that the PDT (polymer decomposition temperature) of graft copolymer is lower than that of xanthan gum, whereas the IPDT (integral procedural decomposition temperature) of graft copolymer is higher than that of xanthan gum, making the former more thermally stable. The swelling and metal ion sorption capability of graft copolymer was investigated. The metal ion sorption behavior of graft copolymer was studied for five metal ions (Cu++, Ni++, Zn++, Pb++, Hg++). Our results show that the grafted sample absorbs a good amount of water and the metal ion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis, characterization, and properties of amphiphilic block copolymer of acrylamide‐styrene by self‐emulsifying microemulsion method
Authors: Ge Zhen , Luo Yunjun
Published: June 2009

The copolymerization system of acrylamide (AM) and styrene (St) was acquired by using amphiphilic block copolymer PAM‐b‐PSt with lower molecular weight as polymeric surfactant, and then the microemulsion phase diagram was drawn. The appropriate copolymerization systems were chosen in the phase diagram, and higher molecular weight amphiphilic block copolymers PAM‐b‐PSt were prepared by self‐emulsifying microemulsion method. The chemical composition and structure of the products were analyzed by FTIR, 1H‐NMR, 13C‐NMR, GPC, and UV; the block structure of products was characterized by DSC, and the hydrophobic association property of the products was studied by the fluorescence probe and rotating viscosity measurement. The results showed that O/W microemulsion was also acquired by using the polymeric surfactant; 3 g polymeric surfactant was only used to disperse 0.25 g St into aqueous solution, which showed higher emulsifying efficiency. At the same time, the use of self‐emulsifying microemulsion copolymerizing system can avoid back treatment of small molecular surfactant and the purified block polymer was prepared in one step; the prepared copolymers have good hydrophobic association properties and their aqueous solution showed evident viscosity increment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Studies on synthesis of modified epoxidized novolac resin from renewable resource material for application in surface coating
Authors: Yadav Ranjana , Awasthi Poonam , Srivastava Deepak
Published: June 2009

Five blend samples of cardanol‐based epoxidized novolac resin containing varying concentrations of carboxyl‐terminated poly(butadiene‐co‐acrylonitrile) (CTBN) ranging between 0 and 25 wt % with an interval of 5 wt % were prepared. The epoxidized novolac resin (ECF) was synthesized from the epoxidation of cardanol‐based novolac‐type phenolic resin (CF) with molar excess of epichlorohydrin (i.e., about 10 mol at 120°C in basic medium). The CF resin was synthesized with a molar ratio of 1 : 0.5 of CF using dicarboxylic acid catalyst such as succinic acid at 120°C for 5 h. The pure epoxy and its blend were cured with stoichiometric amounts of polyamine curing agent. The formation of various products during the synthesis of cardanol‐based novolac resin, epoxidized novolac resin, and blending of epoxidized novolac resin with CTBN have been studied by Fourier transform infrared (FTIR) spectroscopic analysis. Further, a reaction mechanism for the step‐growth reaction was proposed on the basis of the results of FTIR analysis. Also, the structures of CF and ECF were proposed on the basis of the results of nuclear magnetic resonance and MALDI‐TOF mass spectroscopic analysis along with gel permeation chromatographic (GPC) analysis. GPC analysis resulted in Mn of 670 gmol−1. The blend sample having 15 wt % CTBN concentration showed minimum cure time, whereas the presence of CTBN in blend systems showed marginal change in the values of ΔH. A clear‐cut two‐step mass loss in dynamic thermogravimetric trace of unmodified and CTBN‐modified systems was observed. Thermal stability of the blend sample containing 15 wt % CTBN into the pure epoxy resin was the highest among all other prepared systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Formation of a bicontinuous structure membrane of polyvinylidene fluoride in diphenyl carbonate diluent via thermally induced phase separation
Authors: Lin Yakai , Tang Yuanhui , Ma Hengyu , Yang Jian , Tian Ye , Ma Wenzhong , Wang Xiaolin
Published: June 2009

Diphenyl carbonate was used as a diluent to prepare microporous polyvinylidene fluoride (PVDF) membrane via thermally induced phase‐separation method. The liquid–liquid phase‐separation phenomenon was found in PVDF/diphenyl carbonate system during the thermally induced phase‐separation process. The monotectic point of this system appeared at a high polymer concentration approximately 56 wt %. This suggested that PVDF membrane with a bicontinuous or cellular structure could be obtained when the PVDF concentration was less than this point value. The effects of polymer concentration and quenching temperature on the membrane structure, porosity, and tensile strength were also investigated. The results showed that low polymer concentration and high quenching temperature led to a large pore size membrane. The tensile strength of the membrane increased with increase in the polymer concentration, but the porosity of the membrane decreased. On condition that the PVDF concentration was higher than 60 wt %, only polymer crystallization occurred and a typical compact spherulitic structure was obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Properties of cotton fabrics treated by protease and its multienzyme combinations
Authors: Kalantzi Styliani , Mamma Diomi , Kalogeris Emmanuel , Kekos Dimitris
Published: June 2009

A commercial serine‐type protease preparation (Alcalase) was examined as a scouring agent for cotton fabrics. Application of the enzyme induced moderate changes in the composition of fibers that were mainly associated with the removal of protein and waxes. The relationship between the compositional modifications and structural transformations, which were reflected in the crystallinity index of the bioscoured cotton fibers, was demonstrated. The protease‐treated textiles displayed superior whiteness and outstanding compressional resilience but exhibited a poor hydrophilicity and dyeing capacity. One‐step scouring at neutral conditions, where proteolytic activity was supported by multienzyme combinations, could generate textiles with sufficient water absorbency and advanced performance. The implementation of the appropriate scouring conditions (concentration and combination of enzymes) could form fabrics with the desired physicochemical and micromechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis of novel poly(ether ketone diphenyl ketone ether ketone ketone)s by electrophilic Friedel–Crafts solution polycondensation
Authors: Cai Mingzhong , Xi Qin , Ding Nengwen , Song Cai‐Sheng
Published: June 2009

4,4′‐Bis(4‐phenoxybenzoyl)diphenyl was prepared by the Friedel–Crafts reaction of 4‐bromobenzoyl chloride and diphenyl followed by condensation with potassium phenoxide. Novel aromatic poly(ether ketone diphenyl ketone ether ketone ketone)s were obtained by the electrophilic Friedel–Crafts solution copolycondensation of 4,4′‐bis(4‐phenoxybenzoyl)diphenyl with a mixture of isophthaloyl chloride and terephthaloyl chloride over a wide range of isophthaloyl chloride/terephthaloyl chloride molar ratios in the presence of anhydrous aluminum chloride and N‐methylpyrrolidone in 1,2‐dichloroethane. The influence of the reaction conditions on the preparation of the copolymers was examined. The copolymers were characterized with different physicochemical techniques. Because of the incorporation of diphenyl, the resulting copolymers exhibited outstanding thermal stability. The glass‐transition temperatures were above 174°C, the melting temperatures were above 342°C, and the 5% weight loss temperatures were above 544°C in nitrogen. All these copolymers were semicrystalline and insoluble in organic solvents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Studies on the electrospun submicron fibers of SIS and its mechanical properties
Authors: Feng Shu‐Qin , Shen Xin‐Yuan , Fu Zhong‐Yu , Ji Ya‐Li
Published: June 2009

The submicron fibers were prepared via electrospinning the styrene–isoprene–styrene (SIS) triblock copolymer from a pure solvent of tetrahydrofuran (THF) and a mixed solvent of THF and N, N‐dimethylformamide (DMF). The addition of DMF to THF resulted in a beneficial effect on the fiber formation and the electrospinnability. The obtained results revealed that the fibers were only formed in a narrow solution concentration range of 8–15 wt %; the morphology, diameter, structure, and mechanical performance of as‐spun fibers from PS and SIS solutions were affected by the composition weight ratio and the solution properties; and those from the solution at the intermediate concentration of 10 wt % exhibited a maximum tensile strength and strain at break. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis of poly(methyl methacrylate) via reverse atom transfer radical polymerization catalyzed by FeCl3/lactic acid
Authors: Zhou Wenying , Chen Hou , Liang Ying , Yu Mengmeng , Chen Lichun
Published: June 2009

Reverse atom transfer radical polymerization (RATRP) of methyl methacrylate (MMA) with azobisisobutyronitrile (AIBN)/FeCl3/lactic acid as initiating system was successfully carried out in N,N‐dimethylformamide (DMF) for the first time. Kinetics as well as molecular weight distribution data indicated towards the controlled nature of polymerization. The polymerization not only showed the best control of molecular weight and its distribution but also provided a rather rapid reaction rate with the molar ratio of [MMA]:[AIBN]:[FeCl3]:[lactic acid] = 300 : 1 : 1 : 2. The polymerization rate increased with increasing the polymerization temperature. The apparent activation energy was calculated to be 47.90 kJ/mol. The rate of polymerization in DMF was faster than that in acetonitrile, cyclohexanone, toluene, and xylene. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Modulating the mechanical properties of poly(diol citrates) via the incorporation of a second type of crosslink network
Authors: Zhao Haichao , Ameer Guillermo A.
Published: June 2009

Novel citric acid‐based polyesters were synthesized by condensation of citric acid, 1,8‐octanediol, and unsaturated monomers such as glycerol 1,3‐diglycerolate diacrylate and bis(hydroxypropylfumarate). Under the synthesis conditions used, the crosslinked elastomeric network exhibited a wide range of mechanical properties. The mechanical properties of acrylated elastomers ranged from 7.4 to 75.9 MPa for Young's modulus, 2.8 to 15.7 MPa for ultimate tensile stress, and 86 to 133% for elongation at break. The mechanical properties of fumarate‐containing elastomers ranged from 16.4 to 38.3 MPa for Young's modulus, 5.5 to 10.2 MPa for ultimate tensile stress, and 218 to 260% for elongation at break, which depended on the content of 1‐vinyl‐2‐pyrrolidinone. Addition of a secondary crosslink network is a viable method to increase the range of mechanical properties of citric acid‐based biodegradable elastomers. The glass transition temperature (Tg) of the elastomers is between −12.7 and −1.6°C, confirming that all the elastomers are in a rubbery state at room temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of nanofillers on carboxymethyl cellulose/hydroxyethyl cellulose hydrogels
Authors: Dai Qizhou , Kadla John F.
Published: June 2009

The effect of hydrophilic nanoparticles (oxidized cellulose nanocrystals (CNC) and montmorillonite nanoclay) on the properties of a sodium carboxymethylcellulose (CMC)/hydroxyethylcellulose (HEC) hydrogel system was investigated. Visually, the CNC reinforced cellulosic hydrogel‐composites were transparent over all CNC loadings, whereas those reinforced with organoclay were opaque even at low clay loadings despite the nanoparticles being well dispersed. Incorporation of CNC into the cellulosic hydrogels led to an increase in the compressive modulus of CNC‐hydrogel composites, but a corresponding decrease in the swelling ratio. However, the addition of CNCs enabled a reduction in the amount of cross‐linker required to obtain a given compressive modulus and swelling behavior. It was observed that the surface charge density of the CNCs had no significant effect on the compression modulus or swelling behavior of the CMC/HEC hydrogel composites. By contrast, the organoclay reinforced CMC/HEC hydrogels did not show any trend in compression modulus or swelling ratio with organoclay content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Tracing a major Roman road in the area of ancient Helike by resistivity tomography
Authors: Tsokas G. N. , Tsourlos P. I. , Stampolidis A. , Katsonopoulou D. , Soter S.
Published: June 2009

In his journey through Achaea in the second century AD, Pausanias mentioned the destroyed Classical site of Helike on the sea and noted that its ruins were still visible underwater near the southwest shore of the Corinthian Gulf. In 2001, the Helike Project excavators discovered on the coastal plain of Helike southeast of Aigion the first ruins of Classical buildings, buried under lagoon sediments 3 m deep. They also found segments of a major Roman road oriented NW–SE and buried 1–1.50 m deep under the contemporary surface. Pausanias referred to the main road through the Helike plain, which he followed during his visit. According to his description, he saw the submerged ruins of Helike toward the sea north of the Roman road. Tracing the exact location of the road would, therefore, help to locate the lost city. We employed resistivity tomography to explore the areas between trenches where the road had been unearthed and also to investigate its possible extension beyond those locations. Since 2004, resistivity studies performed by grids or single profiles have been carried out at 11 locations. As a result, the ancient road was detected for a length of about 2 km. It was also imaged either in two‐dimensional or three‐dimensional contexts at all the locations where it was detected. Copyright © 2009 John Wiley & Sons, Ltd.
From the air to beneath the soil – revealing and mapping great war trenches at Ploegsteert (Comines‐Warneton), Belgium
Authors: Masters P. , Stichelbaut B.
Published: June 2009

Recent military battlefield sites are often recorded by accident during geophysical investigations researching into earlier archaeological landscapes. The First World War (Great War) perhaps left its traces like no other war before or since in Europe. For the first time, a large area, some 16 ha in extent, has been surveyed over a modern conflict landscape. The authors have attempted to combine two remote sensing techniques: analysis of contemporary Great War aerial photographs and geophysical prospection techniques. The combination of two different approaches leads to a more comprehensive understanding of the Great War battlefield and an understanding of the value of remote sensing in this new area of applied research. Copyright © 2009 John Wiley & Sons, Ltd.
Expression and regulation of the bile acid transporter, OSTα‐OSTβ in rat and human intestine and liver
Authors: Khan Ansar A. , Chow Edwin C. Y. , Porte Robert J. , Pang K. Sandy , Groothuis Geny M. M.
Published: June 2009

The regulation of the OSTα and OSTβ expression was studied in the rat jejunum, ileum, colon and liver and in human ileum and liver by ligands for the farnesoid X receptor (FXR), pregnane X receptor (PXR), vitamin D receptor (VDR) and glucocorticoid receptor (GR) using precision cut tissue slices. The gradient of protein and mRNA expression in segments of the intestine for rOSTα and rOSTβ paralleled that of rASBT. OSTα and OSTβ mRNA expression, quantified by qRT‐PCR, in rat jejunum, ileum, colon and liver, and in human ileum and liver was positively regulated by FXR and GR ligands. In contrast, the VDR ligand, 1,25(OH)2D3 decreased the expression of rOSTα‐rOSTβ in rat intestine, but had no effect on human ileum, and rat and human liver slices. Lithocholic acid (LCA) decreased the expression of rOSTα and rOSTβ in rat ileum but induced OSTα‐OSTβ expression in rat liver slices, and human ileum and liver slices. The PXR ligand, pregnenolone‐16α carbonitrile (PCN) had no effect. This study suggest that, apart from FXR ligands, the OSTα and OSTβ genes are also regulated by VDR and GR ligands and not by PXR ligands. This study show that VDR ligands exerted different effects on OSTα‐OSTβ in the rat and human intestine and liver compared with other nuclear receptors, FXR, PXR, and GR, pointing to species‐ and organ‐specific differences in the regulation of OSTα‐OSTβ genes. Copyright © 2009 John Wiley & Sons, Ltd.
Transport characteristics of candesartan in human intestinal Caco‐2 cell line
Authors: Zhou Lingjie , Chen Xiaoping , Gu Yuanqing , Liang Jianying
Published: June 2009

The intestinal absorptive characteristics and the efflux mechanisms of candesartan (CDS), a novel angiotensin II type 1 receptor blocker, were investigated. The Caco‐2 cells were used as models of the intestinal mucosa to assess uptake and transport of CDS. The determination of CDS was performed by HPLC‐Flu. In the Caco‐2 cells, the uptake and absorptive transport of CDS were pH‐independent (in the pH range 6.0–8.0). Passive membrane diffusion dominates the absorptive transport behavior of CDS across Caco‐2 cells, while secretory transport was a concentration‐dependent and saturable process. In the presence of cyclosporin A and verapamil, potent inhibitors of P‐glycoprotein (P‐gp), the Pratio decreased from 3.8 to 2.3 and 1.8, respectively, and permeation of apical to basolateral was enhanced. Overall, the current study suggests that efflux transporters are capable of mediating the absorption and secretion of CDS, and they may play significant roles in limiting the oral absorption of CDS. Copyright © 2009 John Wiley & Sons, Ltd.
The relation between the specific absorption rate and electromagnetic field intensity for heterogeneous exposure conditions at mobile communications frequencies
Authors: Neubauer Georg , Preiner Patrick , Cecil Stefan , Mitrevski Niki , Gonter Johannes , Garn Heinrich
Published: June 2009

The relation between the incident electromagnetic field strength and both the whole‐body and the local specific absorption rate (SAR) was investigated for typical heterogeneous exposure scenarios for frequencies relevant for mobile communication. The results were compared to results from plane wave exposure. Heterogeneous exposure arises from multiple path propagation of the electromagnetic waves to the location of interest. It is shown that plane wave exposure does not represent worst‐case exposure conditions. When the electric field strength arising at plane wave exposure is compared to the electric field strength averaged over the volume of the human body occurring during multipath exposure, 12% of all heterogeneous cases examined represent worse exposure conditions than plane wave exposure for whole‐body exposure at 946 MHz, 15% at 1840 MHz, and 22% at 2140 MHz. The deviation between plane wave and heterogeneous whole‐body SAR ranges from −54% to 54%. For partial‐body SAR averaged over 10 g of tissue, a range from −93% to 209% was found when comparing multiple wave exposure to single incoming plane waves. The investigations performed using the Visible Human as phantom showed that the basic restrictions are met as long as the reference levels are not exceeded. However, this must not be necessarily the case when different phantoms are used to perform similar investigations because recent studies demonstrated that reference levels might not be conservative when phantoms of children are used. Therefore, the results of this work indicate the need to extend the investigations to numerical simulations with additional human phantoms representing parts of the human population having different anatomy and morphology compared to the phantom used within the frame of this project. This also applies to phantoms of children. Bioelectromagnetics 30:651–662, 2009. © 2009 Wiley‐Liss, Inc.
Zum Querkraftwiderstand bei Leichtbetonbalken ohne Querkraftbewehrung
Authors: Basche Holger D. , Keller Christina
Published: June 2009

In diesem Beitrag wird über Biegeschubversuche mit Leichtbetonbalken ohne Querkraftbewehrung berichtet, die ein ausgeprägtes Nachbruchverhalten aufwiesen. Die Versuchsergebnisse der Leichtbetonbalken werfen die Frage auf, ob die Querkraftbemessung in der neuen DIN 1045‐1 in der Lage ist, hoch spröde Betone wie ALWAC (All Lightweight Aggregate Concrete) hinreichend sicher zu erfassen. In diesem Zusammenhang wird näher auf den Maßstabseffekt eingegangen.

Es wurde ein Modell für das Tragverhalten von Biegeschubbalken nach Auftreten des Biegeschubrisses entwickelt, das auf der Kinematik von miteinander verbundenen Festkörpern anstelle von Fachwerkstäben beruht. Ein Ansatz der Tragkapazität im Nachbruchbereich für die Praxis wird nicht empfohlen.

Shear Strength of Lightweight Concrete without Shear Reinforcement

This paper presents results of shear beam tests with lightweight concrete and without shear reinforcement exhibiting a distinct post peak behavior. The shear test results raise the question whether the shear design in DIN 1045‐1 can also cover very brittle concrete types as ALWAC (All Lightweight Aggregate Concrete) with a sufficient safety level. The size effect in shear beams is discussed.

A model for the load bearing behavior after formation of the inclined crack based on the kinematics of a set of rigid bodies is developed. A consideration of the additional load capacity in the post peak range in design formulas is not recommended.
Versuche zur Ermüdungsfestigkeit alter Betonstähle
Authors: Fehlmann Patrick , Vogel Thomas
Published: June 2009

Die Frage der Ermüdungssicherheit hat im Zusammenhang mit der Überprüfung bestehender Stahlbetonbauwerke, insbesondere Brücken, an Aktualität gewonnen. Während auf der Einwirkungsseite die Anzahl der Lastwechsel und die Lasten, die die Brücke im Laufe ihres Lebens erfahren hat, von Bedeutung sind, sind es auf der Widerstandsseite die Genauigkeit des Tragwerkmodells und die Materialkennwerte. Mit Letzteren befasst sich dieser Aufsatz. Der wichtigste Parameter auf der Widerstandsseite ist die Ermüdungsfestigkeit des Betonstahls. Mittels Dauerschwingversuchen wurde die Ermüdungsfestigkeit von vier Betonstahlsorten ermittelt. Zwei Sorten stammen von abgebrochenen Brücken aus den 1950er Jahren; zwei weitere sind kürzlich produzierte Sorten von Ring‐ und Stabmaterial der Betonstahlsorte B 500 B. Das Ziel der Versuche bestand darin, festzustellen, ob das Alter einer Stahlbetonkonstruktion einen Einfluss auf die Ermüdungsfestigkeit des Betonstahls hat. Im Aufsatz werden die Problematik beim Nachweis der Ermüdungssicherheit bestehender Brücken kurz geschildert, die Versuche beschrieben und deren Resultate diskutiert.

Fatigue Tests with Old Reinforcing Steels

Recently, fatigue safety has become an issue with respect to surveying the condition of existing structures, in particular bridges. While questions considering traffic loads and frequencies dominate the calculations of the appropriate load scenarios, the accuracy of the structural model and material properties play a vital role for the calculation of the resistance. This article deals with the latter. The most important parameter on the resistance side is the fatigue strength of the reinforcement. Therefore, fatigue strength of four brands of reinforcing steel was determined in fatigue tests. Two brands of reinforcement bars could be gathered during demolition work of two bridges which were built in the 1950ies. Another two brands of new reinforcing steel B 500 B, a rod‐steel and a steel from the roll, were tested. The aim of the tests was to prove whether age and environment of the built‐in reinforcement bars affect their fatigue resistance or not. The article briefly describes the difficulties with verifying the fatigue safety of existing bridges while the main part deals with the experimental work and the discussion of the test results.
Bemessung der Verankerung von Befestigungen in Beton
Authors: Eligehausen Rolf , Fuchs Werner
Published: June 2009

Die neue CEN/TS 1992‐4 ist eine Vornorm, die aus fünf Teilen besteht und Bemessungsverfahren für Kopfbolzen, Ankerschienen sowie mechanische und chemische Befestigungsmittel zur Übertragung von Lasten in tragende Beton‐ und Stahlbetonkonstruktionen enthält. Voraussetzung für die Bemessung nach dieser CEN/TS ist, dass die Verwendung der zu bemessenden Befestigungsmittel über eine Europäische Technische Spezifikation wie z. B. eine Europäische Technische Zulassung (ETA) nachgewiesen ist. Die Bemessungsverfahren stellen den aktuellen Stand der Technik dar. Die CEN/TS 1992‐4 ist für alle Anwendungen gültig, die in den Bereich der EN 1992‐1 fallen und deshalb auch ein Bestandteil von Eurocode 2 geworden. Die Bemessung des Anbauteils ist nicht abgedeckt. Die Inhalte der CEN/TS 1992‐4‐Reihe werden in diesem Beitrag kurz vorgestellt.

Design of Fastenings for Use in Concrete – the new CEN/TS series

The new CEN/TS 1992‐4 series is a pre‐standard consisting of 5 parts which provides design methods for headed studs, anchor channels as well as post‐installed mechanical and chemical fasteners for structural purposes to transmit actions into concrete and reinforced concrete structures. The CEN/TS applies to fasteners with established suitability for the specified application in concrete covered by provisions such as European Technical Approvals (ETAs). The design methods represent the actual stateof‐ art. The CEN/TS 1992‐4 is valid for applications which fall within the scope of the series EN 1992. The design of the fixture is not covered. The content of the CEN7TS 1992‐4 series is shortly presented in this paper.
Instandsetzungskonzept für einen chloridbelasteten Brückenüberbau zur Sicherung der Dauerhaftigkeit
Authors: Albertin‐Hummel Ursula , Brandt Bernd
Published: June 2009

Brücken sind ständig der Witterung und hoher dynamischer Belastung ausgesetzt. Mit den Jahren hinterlassen diese Beanspruchungen ihre Spuren. Mängel und Schäden treten auf, die die Dauerhaftigkeit nachteilig beeinflussen. Langfristig werden dadurch auch die Stand‐ und Verkehrssicherheit gefährdet. Am Beispiel der Autobahntalbrücke Schallermühle im Zuge der Bundesautobahn A3 Nürnberg – Regensburg wird ein Instandsetzungskonzept zur Sicherung der Dauerhaftigkeit vorgestellt. Die Talbrücke Schallermühle ist eine sechsfeldrige, vorgespannte Brücke, die eine hohe Chloridbelastung und feuchte Stellen mit Ausblühungen aufweist. Zur Behebung dieser Schäden werden allgemeine Überlegungen diskutiert. Mit umfangreichen Berechnungen werden Verstärkungsmaßnahmen und verschiedene Instandsetzungsmodelle numerisch untersucht und die Instandsetzung geplant. Das Instandsetzungskonzept umfasst Verstärkungen sowie Betonersatz an der Oberund Unterseite der Überbauten und eine Erneuerung der Abdichtung.
Mcl‐1 overexpression leads to higher viabilities and increased production of humanized monoclonal antibody in Chinese hamster ovary cells
Authors: Majors Brian S. , Betenbaugh Michael J. , Pederson Nels E. , Chiang Gisela G.
Published: June 2009

Bioreactor stresses, including nutrient deprivation, shear stress, and byproduct accumulation can cause apoptosis, leading to lower recombinant protein yields and increased costs in downstream processing. Although cell engineering strategies utilizing the overexpression of antiapoptotic Bcl‐2 family proteins such as Bcl‐2 and Bcl‐xL potently inhibit apoptosis, no studies have examined the use of the Bcl‐2 family protein, Mcl‐1, in commercial mammalian cell culture processes. Here, we overexpress both the wild type Mcl‐1 protein and a Mcl‐1 mutant protein that is not degraded by the proteasome in a serum‐free Chinese hamster ovary (CHO) cell line producing a therapeutic antibody. The expression of Mcl‐1 led to increased viabilities in fed‐batch culture, with cell lines expressing the Mcl‐1 mutant maintaining ∼90% viability after 14 days when compared with 65% for control cells. In addition to enhanced culture viability, Mcl‐1‐expressing cell lines were isolated that consistently showed increases in antibody production of 20–35% when compared with control cultures. The quality of the antibody product was not affected in the Mcl‐1‐expressing cell lines, and Mcl‐1‐expressing cells exhibited 3‐fold lower caspase‐3 activation when compared with the control cell lines. Altogether, the expression of Mcl‐1 represents a promising alternative cell engineering strategy to delay apoptosis and increase recombinant protein production in CHO cells. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
The fermentation stoichiometry of Thermotoga neapolitana and influence of temperature, oxygen, and pH on hydrogen production
Authors: Munro Sarah A. , Zinder Stephen H. , Walker Larry P.
Published: June 2009

The hyperthermophilic bacterium, Thermotoga neapolitana, has potential for use in biological hydrogen (H2) production. The objectives of this study were to (1) determine the fermentation stoichiometry of Thermotoga neapolitana and examine H2 production at various growth temperatures, (2) investigate the effect of oxygen (O2) on H2 production, and (3) determine the cause of glucose consumption inhibition. Batch fermentation experiments were conducted at temperatures of 60, 65, 70, 77, and 85°C to determine product yield coefficients and volumetric productivity rates. Yield coefficients did not show significant changes with respect to growth temperature and the rate of H2 production reached maximum levels in both the 77°C and 85°C experiments. The fermentation stoichiometry for T. neapolitana at 85°C was 3.8 mol H2, 2 mol CO2, 1.8 mol acetate, and 0.1 mol lactate produced per mol of glucose consumed. Under microaerobic conditions H2 production did not increase when compared to anaerobic conditions, which supports other evidence in the literature that T. neapolitana does not produce H2 through microaerobic metabolism. Glucose consumption was inhibited by a decrease in pH. When pH was adjusted with buffer addition cultures completely consumed available glucose. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust enzymatic saccharification of hardwoods
Authors: Wang G. S. , Pan X. J. , Zhu J. Y. , Gleisner R. , Rockwood D.
Published: June 2009

This study demonstrates sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust bioconversion of hardwoods. With only about 4% sodium bisulfite charge on aspen and 30‐min pretreatment at temperature 180°C, SPORL can achieve near‐complete cellulose conversion to glucose in a wide range of pretreatment liquor of pH 2.0–4.5 in only about 10 h enzymatic hydrolysis. The enzyme loading was about 20 FPU cellulase plus 30 CBU β‐glucosidase per gram of cellulose. The production of fermentation inhibitor furfural was less than 20 mg/g of aspen wood at pH 4.5. With pH 4.5, SPORL avoided reactor corrosion problem and eliminated the need for substrate neutralization prior to enzymatic hydrolysis. Similar results were obtained from maple and eucalyptus. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Progress technology in microencapsulation methods for cell therapy
Authors: Rabanel Jean‐Michel , Banquy Xavier , Zouaoui Hamza , Mokhtar Mohamed , Hildgen Patrice
Published: June 2009

Cell encapsulation in microcapsules allows the in situ delivery of secreted proteins to treat different pathological conditions. Spherical microcapsules offer optimal surface‐to‐volume ratio for protein and nutrient diffusion, and thus, cell viability. This technology permits cell survival along with protein secretion activity upon appropriate host stimuli without the deleterious effects of immunosuppressant drugs. Microcapsules can be classified in 3 categories: matrix‐core/shell microcapsules, liquid‐core/shell microcapsules, and cells‐core/shell microcapsules (or conformal coating). Many preparation techniques using natural or synthetic polymers as well as inorganic compounds have been reported. Matrix‐core/shell microcapsules in which cells are hydrogel‐embedded, exemplified by alginates capsule, is by far the most studied method. Numerous refinement of the technique have been proposed over the years such as better material characterization and purification, improvements in microbead generation methods, and new microbeads coating techniques. Other approaches, based on liquid‐core capsules showed improved protein production and increased cell survival. But aside those more traditional techniques, new techniques are emerging in response to shortcomings of existing methods. More recently, direct cell aggregate coating have been proposed to minimize membrane thickness and implants size. Microcapsule performances are largely dictated by the physicochemical properties of the materials and the preparation techniques employed. Despite numerous promising pre‐clinical results, at the present time each methods proposed need further improvements before reaching the clinical phase. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
The Synechocystis sp. PCC6803 Sfp‐Type Phosphopantetheinyl Transferase Does Not Possess Characteristic Broad‐Range Activity
Authors: Roberts Alexandra A. , Copp Janine N. , Marahiel Mohamed A. , Neilan Brett A.
Published: June 2009

The cyanobacterium Synechocystis sp. PCC6803 harbours one phosphopantetheinyl transferase (PPTase), Sppt. Protein modelling supported previous bioinformatics analyses, which suggested that Sppt is a Sfp‐type PPTase with the potential to phosphopantetheinylate a broad range of carrier proteins from both primary and secondary metabolism. However, no natural products are synthesised by this species, which raises interesting evolutionary and functional questions. Phosphopantetheinylation assays and kinetic data demonstrate that Sppt was able to activate its cognate fatty acid synthesis carrier protein, SACP, but was unable to effectively activate various cyanobacterial carrier proteins from secondary metabolism or glycolipid biosynthesis pathways. To our knowledge, this is the first example of a PPTase with a Sfp‐type structure, but with activity more closely resembling AcpS‐type enzymes. The broad‐range PPTase from Nodularia spumigena NSOR10 was introduced into Synechocystis sp. PCC6803 and was shown to activate a noncognate carrier protein, in vivo. This engineered strain could provide a future biotechnological platform for the heterologous expression of cyanobacterial biosynthetic gene clusters.
Eosin Y‐Sensitized Artificial Photosynthesis by Highly Efficient Visible‐Light‐Driven Regeneration of Nicotinamide Cofactor
Authors: Lee Sahng Ha , Nam Dong Heon , Kim Jae Hong , Baeg Jin‐Ook , Park Chan Beum
Published: June 2009

Dye‐sensitized photosynthesis: Eosin Y (EY), a dye photosensitizer, works efficiently as a molecular photoelectrode by catalyzing the visible‐light‐driven electron‐transfer reaction for efficient regeneration of NADH through a photosensitizer–electron relay dyad. Injection of the photosensitized electron resulted in highly accelerated regeneration of NADH, which can be used by glutamate dehydrogenase for the photosynthesis of L‐glutamate.

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Translational Diffusion and Interaction of a Photoreceptor and Its Cognate Transducer Observed in Giant Unilamellar Vesicles by Using Dual‐Focus FCS
Authors: Kriegsmann Jana , Gregor Ingo , von der Hocht Iris , Klare Johann , Engelhard Martin , Enderlein Jörg , Fitter Jörg
Published: June 2009

In order to monitor membrane–protein binding in lipid bilayers at physiological protein concentrations, we employed the recently developed dual‐focus fluorescence correlation spectroscopy (2fFCS) technique. In a case study on a photoreceptor consisting of seven transmembrane helices and its cognate transducer (two transmembrane helices), the lateral diffusion for these integral membrane proteins was analyzed in giant unilamellar vesicles (GUVs). The two‐dimensional diffusion coefficients of both separately diffusing proteins differ significantly, with D=2.2×10−8 cm2 s−1 for the photoreceptor and with D=4.1×10−8 cm2 s−1 for the transducer. In GUVs with both membrane proteins present together, we observed significantly smaller diffusion coefficients for labelled transducer molecules; this indicates the presence of larger diffusing units and therefore intermolecular protein binding. Based on the phenomenological dependence of diffusion coefficients on the molecule's cylindrical radius, we are able to estimate the degree of membrane protein binding on a quantitative level.
Spatio‐Temporal Control of Cell Coculture Interactions on Surfaces
Authors: Lee Eun‐Ju , Chan Eugene W. L. , Yousaf Muhammad N.
Published: June 2009

Coculture control: We report a combined photochemical and electroactive self‐assembled monolayer (SAM)‐based substrate strategy to generate a coculture platform with spatial and temporal control of cell–cell interactions. These dynamic substrates can present a variety of ligands on the surface for biospecific interactions between the ligands and cell surface receptors. Photopatterning enables the ligands to be immobilized in patterns and even gradients.

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